| 1. |
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| 2. |
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| 3. |
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| 4. |
- Andersson, Edvin K. W., et al.
(author)
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Initial SEI formation in LiBOB-, LiDFOB- and LiBF4-containing PEO electrolytes
- 2024
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In: Journal of Materials Chemistry A. - : Royal Society of Chemistry. - 2050-7488 .- 2050-7496. ; 12:15, s. 9184-9199
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Journal article (peer-reviewed)abstract
- A limiting factor for solid polymer electrolyte (SPE)-based Li-batteries is the functionality of the electrolyte decomposition layer that is spontaneously formed at the Li metal anode. A deeper understanding of this layer will facilitate its improvement. This study investigates three SPEs – polyethylene oxide:lithium tetrafluoroborate (PEO:LiBF4), polyethylene oxide:lithium bis(oxalate)borate (PEO:LiBOB), and polyethylene oxide:lithium difluoro(oxalato)borate (PEO:LiDFOB) – using a combination of electrochemical impedance spectroscopy (EIS), galvanostatic cycling, in situ Li deposition photoelectron spectroscopy (PES), and ab initio molecular dynamics (AIMD) simulations. Through this combination, the cell performance of PEO:LiDFOB can be connected to the initial SPE decomposition at the anode interface. It is found that PEO:LiDFOB had the highest capacity retention, which is correlated to having the least decomposition at the interface. This indicates that the lower SPE decomposition at the interface still creates a more effective decomposition layer, which is capable of preventing further electrolyte decomposition. Moreover, the PES results indicate formation of polyethylene in the SEI in cells based on PEO electrolytes. This is supported by AIMD that shows a polyethylene formation pathway through free-radical polymerization of ethylene.
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| 5. |
- Andersson, Rassmus, et al.
(author)
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Designing Polyurethane Solid Polymer Electrolytes for High-Temperature Lithium Metal Batteries
- 2022
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In: ACS Applied Energy Materials. - : American Chemical Society (ACS). - 2574-0962. ; 5:1, s. 407-418
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Journal article (peer-reviewed)abstract
- Potentially high-performance lithium metal cells in extreme high-temperature electrochemical environments is a challenging but attractive battery concept that requires stable and robust electrolytes to avoid severely limiting lifetimes of the cells. Here, the properties of tailored polyester and polycarbonate diols as the soft segments in polyurethanes are investigated and electrochemically evaluated for use as solid polymer electrolytes in lithium metal batteries. The polyurethanes demonstrate high mechanical stability against deformation at low flow rates and moreover at temperatures up above 100 degrees C, enabled by the hard urethane segments. The results further indicate transferrable ion transport properties of the pure polymers when incorporated as the soft segments in the polyurethanes, offering designing opportunities of the polyurethane by tuning the soft segment ratio and composition. Long-term electrochemical cycling of polyurethane-containing cells in lithium metal batteries at 80 degrees C proves the stability at elevated temperatures as well as the compatibility with lithium metal with stable cycling maintained after 2000 cycles.
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| 6. |
- Andersson, Rassmus
(author)
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Discovering new ground in ion transport: Exploring coordination effects in polymer electrolytes : – From method development to battery implementation
- 2024
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Doctoral thesis (other academic/artistic)abstract
- The exponentially increasing demand for portable and stationary energy storage devices is pushing the development of lithium-ion batteries (LIBs). This requires safer and more sustainable electrolytes where solid polymer electrolytes (SPEs) are a viable alternative to the flammable liquid electrolytes used nowadays. However, SPEs are characterized by poor ionic conductivity compared to their liquid equivalents, preventing large-scale implementation. Furthermore, to meet the increasing production rate of batteries, alternative battery chemistries based on more abundant resources than Li are explored. To address these matters, a fundamental understanding of ion transport in SPEs for a range of relevant cations is vital in the development process.In the thesis, the ion transport is explored on a fundamental level for Li+ in addition to cations “beyond Li” such as Na+, K+ and Mg2+ in polyether-, polyester- and polycarbonate-based SPEs, where the core encompasses the connection between the ion coordination strength and the transference number (T+). New methods to investigate these properties have been developed especially targeting these more challenging cations. To study the ion coordination strength, two qualitative and one quantitative methods based on NMR and FTIR, are presented. In addition, eNMR and EIS have been combined to determine T+.Regardless of the cation investigated, the strongest coordination was observed for polyethylene oxide, stemming from its chelating effect on the cations. In contrast, poly(trimethylene carbonate) exhibited the weakest coordination, while poly(ε-caprolactone) fell in between. A direct correlation between the coordination strength and the T+ was also recognized, where strong interactions are accompanied by low T+ and vice versa. Moreover, the divalent Mg2+ displayed particularly interesting transport characteristics, where the [MgTFSI]+ speciation appears to be a large contributor to the net Mg mobility. Lastly, the outcome of incorporating an ion-conducting polymer as the soft segment in polyurethanes is that the transport mechanism of the pure SPE remains. In combination with sustained long-term cycling in lithium metal batteries, the polyurethanes illustrate opportunities for new designs by adjusting the soft segments. Similarly, the properties of poly(1-oxoheptamethylene) can be controlled by tuning its saturation degree, which is crucial for the ion conduction and mechanical properties in lithium metal batteries, since it highly affects the crystallinity and the crosslinking of the systems.In summary, this thesis contributes toward the understanding of ion transport in systems belonging to “next-generation” batteries, where SPEs for lithium-metal batteries as well as for cations “beyond Li” are considered to play an important part.
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| 7. |
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| 8. |
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| 9. |
- Andersson, Rassmus, et al.
(author)
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Micro versus Nano : Impact of Particle Size on the Flow Characteristics of Silicon Anode Slurries
- 2020
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In: ENERGY TECHNOLOGY. - : WILEY-V C H VERLAG GMBH. - 2194-4288 .- 2194-4296. ; 8:7
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Journal article (peer-reviewed)abstract
- Silicon is interesting for use as a negative electrode material in Li-ion batteries due to its extremely high gravimetric capacity compared with today's state-of-the-art material, graphite. However, during cycling the Si particles suffer from large volume changes, leading to particle cracking, electrolyte decompositions, and electrode disintegration. Although utilizing nm-sized particles can mitigate some of these issues, it would instead be more cost-effective to incorporate mu m-sized silicon particles in the anode. Herein, it is shown that the size of the Si particles not only influences the electrode cycling properties but also has a decisive impact on the processing characteristics during electrode preparation. In water-based slurries and suspensions containing mu m-Si and nm-Si particles, the smaller particles consistently give higher viscosities and more pronounced viscoelastic properties, particularly at low shear rates. This difference is observed even when the Si particles are present as a minor component in blends with graphite. It is found that the viscosity follows the particle volume fraction divided by the particle radius, suggesting that it is dependent on the surface area concentration of the Si particles.
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| 10. |
- Andersson, Rassmus, et al.
(author)
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Quantifying the ion coordination strength in polymer electrolytes
- 2022
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In: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry. - 1463-9076 .- 1463-9084. ; 24:26, s. 16343-16352
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Journal article (peer-reviewed)abstract
- In the progress of implementing solid polymer electrolytes (SPEs) into batteries, fundamental understanding of the processes occurring within and in the vicinity of the SPE are required. An important but so far relatively unexplored parameter influencing the ion transport properties is the ion coordination strength. Our understanding of the coordination chemistry and its role for the ion transport is partly hampered by the scarcity of suitable methods to measure this phenomenon. Herein, two qualitative methods and one quantitative method to assess the ion coordination strength are presented, contrasted and discussed for TFSI-based salts of Li+, Na+ and Mg2+ in polyethylene oxide (PEO), poly(epsilon-caprolactone) (PCL) and poly(trimethylene carbonate) (PTMC). For the qualitative methods, the coordination strength is probed by studying the equilibrium between cation coordination to polymer ligands or solvent molecules, whereas the quantitative method studies the ion dissociation equilibrium of salts in solvent-free polymers. All methods are in agreement that regardless of cation, the strongest coordination strength is observed for PEO, while PTMC exhibits the weakest coordination strength. Considering the cations, the weakest coordination is observed for Mg2+ in all polymers, indicative of the strong ion-ion interactions in Mg(TFSI)(2), whilst the coordination strength for Li+ and Na+ seems to be more influenced by the interplay between the cation charge/radius and the polymer structure. The trends observed are in excellent agreement with previously observed transference numbers, confirming the importance and its connection to the ion transport in SPEs.
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| 11. |
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| 12. |
- Bengtsson, Katarina, et al.
(author)
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Plasticized polyethylene glycol as sacrificial support and template material for syringe-based 3D-printing
- 2015
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Other publication (other academic/artistic)abstract
- Syringe-based 3D-printing is a powerful additive manufacturing method for fabricating short runs (small volumes) of components from multiple materials with a wide range of viscosities. However, objects that are hollow or not in complete contact with the printer’s stage are difficult to fabricate. Using a sacrificial template as a supporting layer enables bottom-up construction of complex structures. Template materials based on polyethylene glycol (PEG) plasticized with organic carbonates to tune their rheological (shear-thinning) and thermal (crystallization) properties have been evaluated, including results from rheometry, differential scanning calorimetry, dissolution rate, chemical compatibility with polydimethylsiloxane (PDMS), and general functionality in a syringe-based 3D-printer. A family of such blends yields material that is easily printed, is stable over time, is soluble in water, and can support other materials and larger structures without collapsing. These mixtures are proposed for use with other extrudable or mouldable materials to enable 3D-printed devices with complex unsupported geometries.
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| 13. |
- Bergfelt, Andreas, et al.
(author)
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A Mechanical Robust yet highly Conductive Diblock Copolymer-based Solid Polymer Electrolyte for Room Temperature Structural Battery Applications
- 2020
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In: ACS Applied Polymer Materials. - : American Chemical Society (ACS). - 2637-6105. ; 2:2, s. 939-948
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Journal article (peer-reviewed)abstract
- In this paper we present a solid polymer electrolyte (SPE) that uniquely combines ionic conductivity and mechanical robustness. This is achieved with a diblock copolymer poly(benzyl methacrylate)-poly(ε-caprolactone-r-trimethylene carbonate). The SPE with 16.7 wt% lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) showed the highest ionic conductivity (9.1×10−6 S cm−1 at 30 °C) and apparent transference number (T+) of 0.64 ± 0.04. Due to the employment of the benzyl methacrylate hard-block, this SPE is mechanically robust with a storage modulus (E') of 0.2 GPa below 40 °C, similar to polystyrene, thus making it a suitable material also for load-bearing constructions. The cell Li|SPE|LiFePO4 is able to cycle reliably at 30 °C for over 300 cycles. The promising mechanical properties, desired for compatibility with Li-metal, together with the fact that BCT is a highly reliable electrolyte material makes this SPE an excellent candidate for next-generation all-solid-state batteries.
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| 14. |
- Bertoli, Luca, et al.
(author)
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Combination of solid polymer electrolytes and lithiophilic zinc for improved plating/stripping efficiency in anode-free lithium metal solid-state batteries
- 2023
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In: Electrochimica Acta. - : Elsevier BV. - 0013-4686 .- 1873-3859. ; 464
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Journal article (peer-reviewed)abstract
- Anode-free lithium metal batteries and solid-state batteries represent some of the most promising alternatives to the current Li-ion technology. The possibility to reach high energy density, due to the exploitation of Li-metal plating/stripping and the elimination of excess anode material, motivate the interest at both academic and in-dustrial levels. Despite these favourable properties, the use of Li-metal has always been extremely challenging and inefficient. This becomes particularly relevant in anode-free systems where no excess of lithium is introduced in the cell. The efficiency and quality of the deposition process is therefore of utmost importance. To optimize the Li-metal plating process, a combination of solid polymer electrolytes and a lithiophilic metal is applied herein, using in situ deposition of a zinc interlayer from a PEO-based SPE to modify the Cu current collector. Im-provements in specific capacity, coulombic efficiency and cyclability with the addition of zinc as lithiophilic metal is verified in full anode-free solid-state Li-batteries, while plating/stripping in half-cell configuration provides additional insights into the relevant mechanisms. The exploitation of the in situ deposited lithiophilic layer reveals an innovative and practical optimization strategy for the future of anode-free solid-state batteries.
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| 15. |
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| 16. |
- Ebadi, Mahsa, et al.
(author)
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Assessing structure and stability of polymer/lithium-metal interfaces from first-principles calculations
- 2019
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In: Journal of Materials Chemistry A. - : Royal Society of Chemistry. - 2050-7488 .- 2050-7496. ; 7:14, s. 8394-8404
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Journal article (peer-reviewed)abstract
- Solid polymer electrolytes (SPEs) are promising candidates for Li metal battery applications, but the interface between these two categories of materials has so far been studied only to a limited degree. A better understanding of interfacial phenomena, primarily polymer degradation, is essential for improving battery performance. The aim of this study is to get insights into atomistic surface interaction and the early stages of solid electrolyte interphase formation between ionically conductive SPE host polymers and the Li metal electrode. A range of SPE candidates are studied, representative of major host material classes: polyethers, polyalcohols, polyesters, polycarbonates, polyamines and polynitriles. Density functional theory (DFT) calculations are carried out to study the stability and the electronic structure of such polymer/Li interfaces. The adsorption energies indicated a stronger adhesion to Li metal of polymers with ester/carbonate and nitrile functional groups. Together with a higher charge redistribution, a higher reactivity of these polymers is predicted as compared to the other electrolyte hosts. Products such as alkoxides and CO are obtained from the degradation of ester- and carbonate-based polymers by AIMD simulations, in agreement with experimental studies. Analogous to low-molecular-weight organic carbonates, decomposition pathways through C-carbonyl-O-ethereal and C-ethereal-O-ethereal bond cleavage can be assumed, with carbonate-containing fragments being thermodynamically favorable.
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| 17. |
- Ebadi, Mahsa, et al.
(author)
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Restricted Ion Transport by Plasticizing Side Chains in Polycarbonate-Based Solid Electrolytes
- 2020
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In: Macromolecules. - : American Chemical Society (ACS). - 0024-9297 .- 1520-5835. ; 53:3, s. 764-774
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Journal article (peer-reviewed)abstract
- Increasing the ionic conductivity has for decades been an overriding goal in the development of solid polymer electrolytes. According to fundamental theories on ion transport mechanisms in polymers, the ionic conductivity is strongly correlated to free volume and segmental mobility of the polymer for the conventional transport processes. Therefore, incorporating plasticizing side chains onto the main chain of the polymer host often appears as a clear-cut strategy to improve the ionic conductivity of the system through lowering of the glass transition temperature (T-g) This intended correlation between Tg and ionic conductivity is, however, not consistently observed in practice. The aim of this study is therefore to elucidate this interplay between segmental mobility and polymer structure in polymer electrolyte systems comprising plasticizing side chains. To this end, we utilize the synthetic versatility of the ion-conductive poly(trimethylene carbonate) (PTMC) platform. Two types of host polymers with side chains added to a PTMC backbone are employed, and the resulting electrolytes are investigated together with the side chain-free analogue both by experiment and with molecular dynamics (MD) simulations. The results show that while added side chains do indeed lead to a lower Tg, the total ionic conductivity is highest in the host matrix without side chains. It was seen in the MD simulations that while side chains promote ionic mobility associated with the polymer chain, the more efficient interchain hopping transport mechanism occurs with a higher probability in the system without side chains. This is connected to a significantly higher solvation site diversity for the Li+ ions in the side-chain-free system, providing better conduction paths. These results strongly indicate that the side chains in fact restrict the mobility of the Li+ ions in the polymer hosts.
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| 18. |
- Elbouazzaoui, Kenza, et al.
(author)
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Ionic transport in solid-state composite poly(trimethylene carbonate)-Li6.7Al0.3La3Zr2O12 electrolytes : The interplay between surface chemistry and ceramic particle loading
- 2023
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In: Electrochimica Acta. - : Elsevier BV. - 0013-4686 .- 1873-3859. ; 462
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Journal article (peer-reviewed)abstract
- The ionic transport in solid-state composite electrolytes based on poly(trimethylene carbonate) (PTMC) with LiTFSI salt and garnet-type ion-conducting Li6.7Al0.3-La3Zr2O12 (LLZO) ceramic particles is here investigated for a range of different compositions. Positive effects on ionic conductivity have previously been reported for LLZO incorporated into poly(ethylene oxide) (PEO), but the origin of these effects is unclear since the inclusion of particles also affects polymer crystallinity. PTMC is, in contrast to PEO, a fully amorphous polymer, and therefore here chosen for the design of a more straight-forward composite electrolyte (CPE) system to study ionic transport. With LLZO loadings ranging from 5 to 70 wt%, the CPE with 30 wt% of LLZO exhibits the highest ionic conductivity with a cationic transference number of 0.94 at 60 degrees C. This is significantly higher than for the pristine PTMC polymer electrolyte. Generally, low to moderate LLZO loadings display a gradual increase of the ionic conductivity, transference number and also of the polymer-cation coordination number. The combined contributions of ionic transport along polymer-ceramic interfaces and Lewis acid-base interaction between the LLZO particles and the LiTFSI salt can explain this enhancement. With loadings of LLZO above 50 wt%, a detrimental effect on the ionic conductivity was however observed. This could be explained by agglomeration of ceramic particles, and by a partial coverage of LLZO particles with a Li2CO3 layer. Consequently, inner polymer-particle interfaces become more resistive, and Li+conduction is prevented along interfacial pathways. The presence of Li2CO3 has more detrimental impact at higher LLZO loadings, since inter-particle connectivity will be hampered, and this is vital for efficient ionic transport. This suggests that there is an interplay between the LLZO particle surface chemistry with its loading, which ultimately controls the Li-ion transport.
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| 19. |
- Emilsson, Samuel, et al.
(author)
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Exploring the use of oligomeric carbonates as porogens and ion-conductors in phase-separated structural electrolytes for Lithium-ion batteries
- 2023
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In: Electrochimica Acta. - : Elsevier BV. - 0013-4686 .- 1873-3859. ; 449
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Journal article (peer-reviewed)abstract
- Phase-separated structural battery electrolytes (SBEs) have the potential to enhance the mechanical stability of the electrolyte while maintaining a high ion conduction. This can be achieved via polymerization-induced phase separation (PIPS), which creates a two-phase system with a liquid electrolyte percolating a mesoporous ther-moset. While previous studies have used commercially available liquid electrolytes, this study investigates the use of novel oligomeric carbonates to enhanced the safety of the SBEs. Increasing the carbonate chain length significantly enhances the thermal stability of the SBEs. Tuning the molecular structure of the liquid electrolyte has a significant effect on the PIPS process and SBE morphology. Using a combination of analyses on a series of wet and dried SBEs, the complex interplay between the phases is interpreted. When an increased pore size is achieved, it leads to a lower MacMullin number (NM). A conductivity of 2 x 10-5 S/cm with a NM=13 could be achieved, while maintaining a thermal stability up to 150 degrees C. The present study demonstrates a versatile approach to tailor this type of electrolyte.
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| 20. |
- Eriksson, Therese, 1992-, et al.
(author)
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Carbonyl-Containing Solid Polymer Electrolyte Host Materials : Conduction and Coordination in Polyketone, Polyester, and Polycarbonate Systems
- 2022
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In: Macromolecules. - : American Chemical Society (ACS). - 0024-9297 .- 1520-5835. ; 55:24, s. 10940-10949
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Journal article (peer-reviewed)abstract
- Research on solid polymer electrolytes (SPEs) is now moving beyond the realm of polyethers that have dominated the field for several decades. A promising alternative group of candidates for SPE host materials is carbonyl-containing polymers. In this work, SPE properties of three different types of carbonyl-coordinating polymers are compared: polycarbonates, polyesters, and polyketones. The investigated polymers were chosen to be as structurally similar as possible, with only the functional group being different, thereby giving direct insights into the role of the noncoordinating main-chain oxygens. As revealed by experimental measurements as well as molecular dynamics simulations, the polyketone possesses the lowest glass transition temperature, but the ion transport is limited by a high degree of crystallinity. The polycarbonate, on the other hand, displays a relatively low coordination strength but is instead limited by its low molecular flexibility. The polyester performs generally as an intermediate between the other two, which is reasonable when considering its structural relation to the alternatives. This work demonstrates that local changes in the coordinating environment of carbonyl-containing polymers can have a large effect on the overall ion conduction, thereby also showing that desired transport properties can be achieved by fine-tuning the polymer chemistry of carbonyl-containing systems.
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| 21. |
- Eriksson, Therese, 1992-
(author)
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Cation Conduction and Coordination in Carbonyl-Containing Compounds : Li+ Transport in Alternative Polymer Electrolyte Host Materials
- 2021
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Doctoral thesis (other academic/artistic)abstract
- The field of solid polymer electrolytes (SPEs) used to create safer lithium-ion batteries has been dominated by polyethylene oxide (PEO) since the discovery of its ion-conducting properties in the 1970s. In this thesis, as an alternative, the ion coordination and conduction properties of SPEs based on polyketones, polyesters and polycarbonates are investigated. Instead of having only an ether oxygen on the backbone (like PEO) the functional group in all three of these polymer classes contains a carbonyl oxygen, which is the main coordinating motif on the polymer backbone. The polyesters and polycarbonates do, however, have one or two more oxygens in the functional group compared to the polyketones. This was shown to have a great effect on the SPE properties. The key properties that have been studied in this work are the ionic conductivity, glass transition temperature, degree of crystallinity, coordination strength, and the transport number. The polymers are both studied individually and comparatively. The polyketone electrolytes studied in this thesis are novel to the solid polymer electrolyte field, and not as established as the polyesters and polycarbonates. The polyketone-based electrolytes have a high degree of crystallinity and the lithium coordination strength is quite high, therefore the ion transport is significantly reduced. Results with a higher salt concentration, however, suggest that with a more amorphous polyketone electrolyte, the transport properties could be significantly improved. The challenge with the polycarbonates is not the degree of crystallinity, as most of the ones studied herein are amorphous, but instead the high glass transition temperature. They are thereby restricted by the low degree of segmental motion present. This problem could not be solved by lowering the glass transition temperature by the addition of side-chains, as the side-chains instead block the pathway of the lithium ions. A positive aspect seen in the polycarbonate-based electrolytes was the high lithium transference number, which is significantly higher than both the polyketones’ and the polyester’s. The polyester is also semi-crystalline; the degree of crystallinity can be reduced by the addition of salt or nanoparticles though. Synthesising a polyester-polycarbonate copolymer is also an option to create an amorphous polymer. The polyester is somewhat of a midway between the polyketone and polycarbonate, both in its molecular structure as well as in its physical and ion transport properties. It does, however, show the highest ionic conductivity out of the three as it has a rather low glass transition temperature and not too strong ion coordination. This work highlights the physical, coordination and conduction properties found in carbonyl-containing polymer host materials. Even though the polyketones, polyesters and polycarbonates are structurally quite similar, their properties can vary significantly. They are, however, all likely candidates for tomorrow’s solid-state lithium-ion batteries.
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| 22. |
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| 23. |
- Eriksson, Therese, 1992-, et al.
(author)
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Effects of nanoparticle addition to poly(epsilon-caprolactone) electrolytes : Crystallinity, conductivity and ambient temperature battery cycling
- 2019
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In: Electrochimica Acta. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0013-4686 .- 1873-3859. ; 300, s. 489-496
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Journal article (peer-reviewed)abstract
- It has previously been shown that nanoparticle additives can, in a simple way, significantly improve the ionic conductivity in solid polymer electrolyte systems with the semi-crystalline poly(ethylene oxide) (PEO) as a host material. It has been suggested that the improved ionic conductivity is a result of reduced degree of crystallinity and additional conductivity mechanisms occurring in the material. In this work, this principle is applied to another semi-crystalline polymer host: poly(epsilon-caprolactone) (PCL). This is a polymer with comparable properties (T-g, T-m, etc.) as PEO, and constitute a promising material for use in solid polymer electrolytes for lithium ion batteries. 15 wt% of the respective nanoparticles TiO2, Al2O3 and h-BN have been added to the PCL-LiTFSI solid polymer electrolyte in an attempt to increase the conductivity and achieve stable room temperature cyclability. The crystallinity, ionic conductivity and electrochemical properties were investigated by differential scanning calorimetry, electrochemical impedance spectroscopy and galvanostatic cycling of cells. The results showed that with an addition of 15 wt% Al2O3, the degree of crystallinity is reduced to 6-7% and the ionic conductivity increased to 6-7 x 10(-6) S cm(-1) at room temperature, allowing successful cycling of cells at 30 degrees C, while h-BN did not contribute to similar improvements. The effect of nanoparticles, however, differ significantly from previous observations in PEO systems, which could be explained by different surface-polymer interactions or the degree of ordering in the amorphous phases of the materials.
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| 24. |
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| 25. |
- Eriksson, Therese, 1992-, et al.
(author)
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Polyketones as Host Materials for Solid Polymer Electrolytes
- 2020
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In: Journal of the Electrochemical Society. - : ELECTROCHEMICAL SOC INC. - 0013-4651 .- 1945-7111. ; 167:7
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Journal article (peer-reviewed)abstract
- While solid polymer electrolytes (SPEs) have great potential for use in future lithium-based batteries, they do, however, not display conductivity at a sufficient level as compared to liquid electrolytes. To reach the needed requirements of lithium batteries it is therefore necessary to explore new materials classes to serve as novel polymer hosts. In this work, SPEs based on the polyketone poly(3,3-dimethylpentane-2,4-dione) were investigated. Polyketones are structurally similar to several polycarbonate and polyester SPE hosts investigated before but have, due to the lack of additional oxygen atoms in the coordinating motif, even more electronwithdrawing carbonyl groups and could therefore display better properties for coordination to the salt cation. In electrolyte compositions comprising 25-40 wt% LiTFSI salt, it was observed that this polyketone indeed conducts lithium ions with a high cation transference number, but that the ionic conductivity is limited by the semi-crystallinity of the polymer matrix. The crystallinity decreases with increasing salt content, and a fully amorphous SPE can be produced at 40 wt% salt, accompanied by an ionic conductivity of 3 x 10(-7) S cm(-1) at 32 degrees C. This opens up for further exploration of polyketone systems for SPE-based batteries.
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| 26. |
- Eriksson, Therese, 1992-, et al.
(author)
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The Role of Coordination Strength in Solid Polymer Electrolytes: Compositional Dependence of Transference Numbers in thePoly(ε-Caprolactone)–Poly(Trimethylene Carbonate) System
- 2021
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In: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry. - 1463-9076 .- 1463-9084. ; 23:45, s. 25550-25557
-
Journal article (peer-reviewed)abstract
- Both polyesters and polycarbonates have been proposed as alternatives to polyethers as host materials for future polymer electrolytes for solid-state lithium-ion batteries. While being comparatively similar functional groups, the electron density on the coordinating carbonyl oxygen is different, thereby rendering different coordinating strength towards lithium ions. In this study, the transport properties of poly(epsilon-caprolactone) and poly(trimethylene carbonate) as well as random copolymers of systematically varied composition of the two have been investigated, in order to better elucidate the role of the coordination strength. The cationic transference number, a property well-connected with the complexing ability of the polymer, was shown to depend almost linearly on the ester content of the copolymer, increasing from 0.49 for the pure poly(epsilon-caprolactone) to 0.83 for pure poly(trimethylene carbonate). Contradictory to the transference number measurements that suggest a stronger lithium-to-ester coordination, DFT calculations showed that the carbonyl oxygen in the carbonate coordinates more strongly to the lithium ion than that of the ester. FT-IR measurements showed the coordination number to be higher in the polyester system, resulting in a higher total coordination strength and thereby resolving the paradox. This likely originates in properties that are specific of polymeric solvent systems, e.g. steric properties and chain dynamics, which influence the coordination chemistry. These results highlight the complexity in polymeric systems and their ion transport properties in comparison to low-molecular-weight analogues, and how polymer structure and steric effects together affect the coordination strength and transport properties.
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| 27. |
- Gerz, Isabelle, et al.
(author)
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Oligomer Electrolytes for Light-Emitting Electrochemical Cells : Influence of the End Groups on Ion Coordination, Ion Binding, and Turn-on Kinetics
- 2019
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In: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 11:43, s. 40372-40381
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Journal article (peer-reviewed)abstract
- The electrolyte is an essential constituent of the light-emitting electrochemical cell (LEC), since its operating mechanism is dependent on the redistribution of mobile ions in the active layer. Recent developments of new ion transporters have yielded high-performance devices, but knowledge about the interactions between the ionic species and the ion transporters and the influence of these interactions on the LEC performance is lacking. We therefore present a combined computational and experimental effort that demonstrates that the selection of the end group in a star-branched oligomeric ion transporter based on trimethylolpropane ethoxylate has a paramount influence on the ionic interactions in the electrolyte and thereby also on the performance of the corresponding LECs. With hydroxyl end groups, the the salt is strongly coordinated to the ion transporter, which leads to suppression of ion pairing, but the penalty is a hindered ion release and a slow turn-on for the LEC devices. With methoxy end groups, an intermediate coordination strength is seen together with the formation of contact ion pairs, but the LEC performance is very good with fast turn-on. Using a series of ion transporters with alkyl carbonate end groups, the ion transporter:cation coordination strength is lowered further, but the turn-on kinetics are slower than what is seen for devices comprising the methoxy end-capped ion transporter.
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| 28. |
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| 29. |
- Gogoi, Neeha, et al.
(author)
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Reactivity of Organosilicon Additives with Water in Li-ion Batteries
- 2024
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In: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 128:4, s. 1654-1662
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Journal article (peer-reviewed)abstract
- Introducing small volumes of organosilicon-containing additives as part of lithium-ion battery (LIB) electrolyte engineering has been getting a lot of attention owing to these additives’ multifunctional properties. Tris(trimethylsilyl)phosphate (TMSPa) is a prominent member of this class of additives and scavenges Lewis bases such as water, although the rate at which the reaction occurs and the fate of the resultant product in the battery system still remain unknown. Herein, we have employed complementary nuclear magnetic resonance and gas chromatography–mass spectrometry to systematically study the reactivity of TMSPa with water in conventional organic carbonate solvents mimicking the Li-ion cell environment. The reaction products are identified, and a working reaction pathway is proposed by following the chemical evolution of the products over varying time and temperatures. We found that the main reaction products are trimethylsilanol (TMSOH) and phosphoric acid (H3PO4); however, various P–O–Si-containing intermediates were also found. Similar to water, the Lewis base TMSOH can undergo reaction with TMSPa at room temperature to form hexamethyldisiloxane and can also activate ethylene carbonate (EC) ring-opening reactions at elevated temperatures (≥80 °C), yielding a TMS derivative with ethylene glycol (TMS-EG). While the formation of TMS-EG at the expense of EC is in principle an unwanted parasitic reaction, it should be noted that this reaction is only activated at elevated temperatures in comparison to EC ring-opening by H2O, which takes place at ≥40 °C. Thus, the study underlines the advantages of organo-silicon compounds as electrolyte additives. Elucidating the reaction mechanism in model systems like this is important for future studies of similar additives in order to improve the accuracy of additive exploration in LIBs.
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| 30. |
- Gudla, Harish, et al.
(author)
-
To Hop or Not to Hop – Unveiling Different Modes of Ion Transport in Solid Polymer Electrolytes Through Molecular Dynamics Simulations
-
Other publication (other academic/artistic)abstract
- In this work, a quantitative method is developed to estimate different ion transport mechanisms in solid polymer electrolyte (SPE) systems. The well-explored poly(ethylene oxide) (PEO) is studied along with the poly(ɛ-caprolactone) (PCL) at different molecular weights and LiTFSI salt concentrations. By tracking the cation coordination changes, three transport mechanisms are categorized, i.e., ion hopping, continuous motion (successive change of the coordination sphere), and vehicular transport. The observed dominant transport mechanism is the continuous motion, and changes from polymer-mediated to anion-mediated with increasing salt concentration. Furthermore, a higher influence of polymer-mediated vehicular transport is observed in PCL systems than in PEO systems, and a correlation is found between the anion-mediated continuous motion and the cation transference number, irrespective of polymer and salt concentrations. In both systems, ion hopping is essentially absent, as can be expected in systems with strong ion–polymer interactions. The results illustrate both how the usual description of ion transport in polymer electrolytes as coupled to segmental motions is too simplistic to catch the full essence of the ion transport phenomena, whereas the frequently used notion of “ion hopping” in the majority of cases is incorrect for SPEs.
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| 31. |
- Hernández, Guiomar, et al.
(author)
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Do non-coordinating polymers function as host materials for solid polymer electrolytes? : The case of PVdF-HFP
- 2023
-
In: Journal of Materials Chemistry A. - : Royal Society of Chemistry. - 2050-7488 .- 2050-7496. ; 11:28, s. 15329-15335
-
Journal article (peer-reviewed)abstract
- In the search for novel solid polymer electrolytes (SPEs), primarily targeting battery applications, a range of different polymers is currently being explored. In this context, the non-coordinating poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP) polymer is a frequently utilized system. Considering that PVdF-HFP should be a poor solvent for cation salts, it is counterintuitive that this is a functional host material for SPEs. Here, we do an in-depth study of the salt dissolution properties and ionic conductivity of PVdF-HFP-based electrolytes, using two different fabrication methods and also employing a low-molecular-weight solvent analogue. It is seen that PVdF-HFP is remarkably poor as an SPE host, despite its comparatively high dielectric constant, and that the salt dissolution properties instead are controlled by fluorophilic interactions of the anion with the polymer.
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| 32. |
- Hernández, Guiomar, et al.
(author)
-
Elimination of Fluorination : The Influence of Fluorine-Free Electrolytes on the Performance of LiNi1/3Mn1/3Co1/3O2/Silicon-Graphite Li-Ion Battery Cells
- 2020
-
In: ACS Sustainable Chemistry and Engineering. - : AMER CHEMICAL SOC. - 2168-0485. ; 8:27, s. 10041-10052
-
Journal article (peer-reviewed)abstract
- In the quest for environmentally friendly and safe batteries, moving from fluorinated electrolytes that are toxic and release corrosive compounds, such as HF, is a necessary step. Here, the effects of electrolyte fluorination are investigated for full cells combining silicon- graphite composite electrodes with Li-Ni1/3Mn1/3Co1/3O2 (NMC111) cathodes, a viable cell chemistry for a range of potential battery applications, by means of electrochemical testing and postmortem surface analysis. A fluorine-free electrolyte based on lithium bis(oxalato) borate (LiBOB) and vinylene carbonate (VC) is able to provide higher discharge capacity (147 mAh g(NMC)(-1)) and longer cycle life at C/10 (84.4% capacity retention after 200 cycles) than a cell with a highly fluorinated electrolyte containing LiPF6, fluoroethylene carbonate (FEC) and VC. The cell with the fluorine-free electrolyte is able to form a stable solid electrolyte interphase (SEI) layer, has low overpotential, and shows a slow increase in cell resistance that leads to improved electrochemical performance. Although the power capability is limiting the performance of the fluorine-free electrolyte due to higher interfacial resistance, it is still able to provide long cycle life at C/2 and outperforms the highly fluorinated electrolyte at 40 degrees C. X-ray photoelectron spectroscopy (XPS) results showed a F-rich SEI with the highly fluorinated electrolyte, while the fluorine-free electrolyte formed an O-rich SEI. Although their composition is different, the electrochemical results show that both the highly fluorinated and fluorine-free electrolytes are able to stabilize the silicon-based anode and support stable cycling in full cells. While these results demonstrate the possibility to use a nonfluorinated electrolyte in high-energy-density full cells, they also address new challenges toward environmentally friendly and nontoxic electrolytes.
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| 33. |
- Hernández, Guiomar, et al.
(author)
-
Fluorine-Free Electrolytes for Lithium and Sodium Batteries
- 2022
-
In: Batteries & Supercaps. - : John Wiley & Sons. - 2566-6223. ; 5:6
-
Research review (peer-reviewed)abstract
- Fluorinated components in the form of salts, solvents and/or additives are a staple of electrolytes for high-performance Li- and Na-ion batteries, but this comes at a cost. Issues like potential toxicity, corrosivity and environmental concerns have sparked interest in fluorine-free alternatives. Of course, these electrolytes should be able to deliver performance that is on par with the electrolytes being in use today in commercial batteries. This begs the question: Are we there yet? This review outlines why fluorine is regarded as an essential component in battery electrolytes, along with the numerous problems it causes and possible strategies to eliminate it from Li- and Na-ion battery electrolytes. The examples provided demonstrate the possibilities of creating fully fluorine-free electrolytes with similar performance as their fluorinated counterparts, but also that there is still a lot of room for improvement, not least in terms of optimizing the fluorine-free systems independently of their fluorinated predecessors.
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| 34. |
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| 35. |
- Hernández, Guiomar, et al.
(author)
-
Going beyond sweep voltammetry : Alternative approaches in search of the elusive electrochemical stability of polymer electrolytes
- 2021
-
In: Journal of the Electrochemical Society. - : The Electrochemical Society. - 0013-4651 .- 1945-7111. ; 168:10
-
Journal article (peer-reviewed)abstract
- Solid polymer electrolytes (SPEs) are promising candidates for solid-state lithium-ion batteries. Potentially, they can be used with lithium metal anodes and high-voltage cathodes, provided that their electrochemical stability is sufficient. Thus far, the oxidative stability has largely been asserted based on results obtained with sweep voltammetry, which are often determined and reliant on arbitrary assessments that are highly dependent on the experimental conditions and do not take the interaction between the electrolyte and the electrode material into account. In this study, alternative techniques are introduced to address the pitfalls of sweep voltammetry for determining the oxidative stability of SPEs. Staircase voltammetry involves static conditions and eliminates the kinetic aspects of sweep voltammetry, and coupled with impedance spectroscopy provides information of changes in resistance and interphase layer formation. Synthetic charge–discharge profile voltammetry applies the real voltage profile of the active material of interest. The added effect of the electrode active material is investigated with a cut-off increase cell cycling method where the upper cut-off voltage during galvanostatic cycling is gradually increased. The feasibility of these techniques has been tested with both poly(ethylene oxide) and poly(trimethylene carbonate) combined with LiTFSI, thereby showing the applicability for several categories of SPEs.
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| 36. |
- Hernández, Guiomar, et al.
(author)
-
Non-Fluorinated Electrolytes for Si-based Li-ion Battery Anodes
- 2018
-
Conference paper (other academic/artistic)abstract
- Although the performance of lithium-ion batteries has been improved to some extent since the initial commercialization,1 cycling stability, safety and sustainability still present some challenges and concerns. In this regard, the battery electrolyte plays an important role. State-of-the-art electrolytes contain the electrolyte salt LiPF6, susceptible to undergo defluorination reactions and form toxic and corrosive compounds, such as HF. Yet, fluorine-containing electrolytes are often considered necessary for enhanced battery performance. On the other hand, replacing LiPF6 with fluorine-free salts would reduce cost, increase safety and decrease toxicity, both in the manufacturing and recycling processes. Among the available fluorine-free salts, lithium bis(oxalato)borate (LiBOB) is a viable candidate due to its enhanced thermal stability.2 Furthermore, additives in the electrolyte are another common source of fluorine, not least fluoroethylene carbonate (FEC) which can form a stable solid electrolyte interface (SEI).3Herein, we compare the cell performance of fluorinated and non-fluorinated electrolytes in NMC/Si-Graphite full cells. Three electrolytes are tested: (1) LP57 (1 M LiPF6 in ethylene carbonate (EC):ethyl methyl carbonate (EMC) 3:7 vol/vol); (2) LP57 with 10 wt% FEC and 2 wt% vinylene carbonate (VC); and (3) 0.7 M LiBOB in EC:EMC 3:7 vol/vol and 2 wt% VC.The cells containing the conventional electrolyte, LP57, feature a rapid capacity fade and continuous decrease in coulombic efficiency. The cell performance is improved when adding SEI-forming additives to the electrolyte (LP57 with FEC and VC). In addition, stable cycling for over 200 cycles are obtained for both the fluorinated (LP57 with FEC and VC) and non-fluorinated (LiBOB with VC) electrolytes.Characterisation by X-ray photoelectron spectroscopy (XPS) of the anode surface showed higher amounts of carbonate species and a thicker SEI layer with the non-fluorinated electrolyte compared to the fluorinated one.1 J. Electrochem. Soc. 2017, 164, A5019-A5025.2 ChemSusChem 2017, 10, 2431-2448.3 J. Electrochem. Soc. 2014, 161, A1933-A1938.
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| 37. |
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| 38. |
- Höglund, Odd, et al.
(author)
-
A new resorbable device for ligation of blood vessels - A pilot study
- 2011
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In: Acta Veterinaria Scandinavica. - : Springer Science and Business Media LLC. - 0044-605X .- 1751-0147. ; 53, s. 47-
-
Journal article (peer-reviewed)abstract
- Background: During surgery, controlled haemostasis to prevent blood loss is vital for a successful outcome. It can be difficult to ligate vessels located deep in the abdomen. A device that is easy to use and enables secure ligatures could be beneficial. Cable ties made of nylon have been used for ligation but the non-resorbable material caused tissue reactions. The objective of this study was to use a resorbable material to construct a device with a self-locking mechanism and to test its mechanical strength and ligation efficiency. Methods: The device was manufactured by injection moulding of polydioxanone, a resorbable polymer used for suture materials. Polydioxanone with inherent viscosities of 1.9 dL/g and 1.3 dL/g were tested. The device consisted of a perforated flexible band which could be pulled through a case with a locking mechanism. After a first version of the device had been tested, some improvements were made. The locking case was downsized, corners were rounded off, the band was made thicker and the mould was redesigned to produce longer devices. Tensile tests were performed with the second version. The first version of the device was used to ligate the ovarian pedicle in a euthanized dog and to test echogenicity of the device with ultrasound. Compression of vessels of the ovarian pedicle was examined by histology. Both versions of the device were tested for haemostasis of and tissue grip on renal arteries in six anaesthetised pigs. Results: The tensile strength of the flexible band of the devices with inherent viscosity of 1.9 dL/g was 50.1 +/- 5.5 N (range 35.2-62.9 N, n = 11) and the devices with inherent viscosity of 1.3 dL/g had a tensile strength of 39.8 +/- 8.1 N (range 18.6-54.2 N, n = 11). Injection moulding of the polymer with lower inherent viscosity resulted in a longer flow distance. Both versions of the device had an effective tissue grip and complete haemostasis of renal arteries was verified. The device attached to the ovarian pedicle could be seen with ultrasound, and vessel compression and occlusion were verified by histology. Conclusions: Tests of functionality of the device showed complete haemostasis and good tissue grip. Devices with a band of sufficient length were easily applied and tightened in tissue.
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| 39. |
- Jeschull, Fabian, et al.
(author)
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Multivalent Cation Transport in Polymer Electrolytes : Reflections on an Old Problem
- 2024
-
In: Advanced Energy Materials. - : Wiley-VCH Verlagsgesellschaft. - 1614-6832 .- 1614-6840. ; 14:4
-
Journal article (peer-reviewed)abstract
- Today an unprecedented diversification is witnessed in battery technologies towards so-called post-Li batteries, which include both other monovalent (Na+ or K+) and multivalent ions (e.g., Mg2+ or Ca2+). This development is driven, among other factors, by goals to establish more sustainable and cheaper raw material platforms, using more abundant raw material, while maintaining high energy densities. For these new technologies a decisive role falls to the electrolyte, that ultimately needs to form stable electrode-electrolyte interfaces and provide sufficient ionic conductivity, while guaranteeing high safety. The transport of metal-ions in a polymer matrix is studied extensively as solid electrolytes for battery applications, particularly for Li-ion batteries and are now also considered for multivalent systems. This poses a great challenge as ion transport in the solid becomes increasingly difficult for multivalent ions. Interestingly, this topic is a subject of interest for many years in the 80s and 90s and many of the problems then are still causing issues today. Owing to recent progress in this field new possibilities arise for multivalent ion transport in solid polymer electrolytes. For this reason, in this perspective a stroll down memory lane is taken, discuss current advancements and dare a peek into the future.
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| 40. |
- Johansson, Isabell, et al.
(author)
-
Improving the Electrochemical Stability of a Polyester-Polycarbonate Solid Polymer Electrolyte by Zwitterionic Additives
- 2022
-
In: ACS Applied Energy Materials. - : American Chemical Society (ACS). - 2574-0962. ; 5:8, s. 10002-10012
-
Journal article (peer-reviewed)abstract
- Rechargeable batteries with solid polymer electrolytes (SPEs), Li-metal anodes, and high-voltage cathodes like LiNixMnyCozO2 (NMC) are promising next-generation high-energy-density storage solutions. However, these types of cells typically experience rapid failure during galvanostatic cycling, visible as an incoherent voltage noise during charging. Herein, two imidazolium-based zwitterions, with varied sulfonate-bearing chain length, are added to a poly(epsilon-caprolactone-co-trimethylene carbonate):LiTFSI electrolyte as cycling-enhancing additives to study their effect on the electrochemical stability of the electrolyte and the cycling performance of half-cells with NMC cathodes. The oxidative stability is studied with two different voltammetric methods using cells with inert working electrodes: the commonly used cyclic voltammetry and staircase voltammetry. The specific effects of the NMC cathode on the electrolyte stability is moreover investigated with cutoff increase cell cycling (CICC) to study the chemical and electrochemical compatibility between the active material and the SPE. Zwitterionic additives proved to enhance the electrochemical stability of the SPE and to facilitate improved galvanostatic cycling stability in half-cells with NMC by preventing the decomposition of LiTFSI at the polymer-cathode interface, as indicated by X-ray photoelectron spectroscopy (XPS).
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| 41. |
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| 42. |
- Johansson, Isabell L., et al.
(author)
-
Mechanically Stable UV-Crosslinked Polyester-Polycarbonate Solid Polymer Electrolyte for High-Temperature Batteries
- 2020
-
In: Batteries & Supercaps. - : WILEY-V C H VERLAG GMBH. - 2566-6223. ; 3:6, s. 527-533
-
Journal article (peer-reviewed)abstract
- Due to the mechanism with which solid polymer electrolytes use to conduct ions, these materials are generally more suitable for high-temperature applications where the ionic conductivity is sufficient and where liquid electrolytes show insufficient stability. To enable high-temperature cycling of polymer electrolytes, the mechanical stability has to be improved. Herein, we report successful long-term cycling of a solid polyester-polycarbonate - poly(epsilon-caprolactone-co-trimethylene carbonate) (poly(CL-co-TMC)) - electrolyte cross-linked through the addition of multifunctional acrylates and the use of UV-irradiation, allowing stable cycling of cells for more than 100 cycles at 80 degrees C, with good rate capabilities (0.2 mA cm(-2)) and Coulombic efficiencies exceeding 99 %. Both the mechanical properties and the ionic conductivity of the mechanically stabilized poly(CL-co-TMC) were investigated and optimized to reduce the frequency dependence of the moduli while still achieving an acceptable ionic conductivity at elevated temperature. These results indicate that the poly(CL-co-TMC) system can straight-forwardly be modified to allow for higher-temperature applications.
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| 43. |
- Johansson, Isabell L., 1994-
(author)
-
The Art of Cycling – Polymer Electrolytes at Extreme Conditions
- 2023
-
Doctoral thesis (other academic/artistic)abstract
- With the rapid development of batteries for applications like electric vehicles and energy storage devices, it is essential to design and develop batteries with improved safety, long cycle life, and high energy density. To achieve this goal, the development and improvement of solid-state batteries, containing solid polymer electrolytes, is a promising solution. The interest in polymer electrolytes is primarily owed to their proposed compatibility with high temperatures and reactive electrodes, such as metallic lithium, and their ability to withstand higher temperatures than traditional liquid electrolytes. Cycling polymer electrolytes at high temperature and with high-voltage cathodes, such as lithium-nickel-manganese-cobalt-oxide (NMC) involves a combination of high chemical, electrochemical, and mechanical stability, as well as the understanding of how to achieve these properties.This thesis provides an overview of some challenges and possibilities of cycling batteries with polymer electrolytes at high temperatures and with high-voltage cathodes. With a focus on the stability of the polymer electrolyte, the effect of changing the polymer host material, the electrolyte salt, and the introduction of additives for enhanced mechanical stability or electrochemical stability, were all evaluated by both standard techniques and techniques developed for polymer electrolytes. Long-term cycling at high temperature was achieved for a poly(ε-caprolactone-co-trimethylene carbonate) (PCL-PTMC) electrolyte by crosslinking additives that increase the mechanical stability of the polymer electrolyte; however, the cycling with high-voltage cathodes also required a high electrochemical stability of the polymer electrolyte. With the techniques developed herein, such as cut-off increase cell cycling, the electrochemical stability of PCL-PTMC was evaluated. By introducing zwitterionic additives to PCL-PTMC, the cycling performance with NMC was enhanced and the enhancement proved to stem from prevention of electrolyte salt decomposition. Finally, by changing the electrolyte salt, it was found that cycling with NMC was possible for PCL-PTMC below its oxidative degradation potential, as long as the electrolyte had an ionic conductivity that was high enough. By utilizing additives, the long-term stability and electrochemical stability toward NMC was also improved. Overall, cycling solid polymer electrolytes at high temperatures and with high-voltage cathodes presents a unique set of challenges, which require that the electrochemical stability of the electrolyte is accurately described, and that the following properties are high: ionic conductivity, electrochemical and mechanical stability; all of which can be improved by utilizing additives in the polymer electrolyte.
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| 44. |
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| 45. |
- Lee, Tian Khoon, et al.
(author)
-
Polyester-ZrO2 Nanocomposite Electrolytes with High Li Transference Numbers for Ambient Temperature All-Solid-State Lithium Batteries
- 2021
-
In: Batteries & Supercaps. - : John Wiley & Sons. - 2566-6223. ; 4:4, s. 653-662
-
Journal article (peer-reviewed)abstract
- Polyester- and polycarbonate-based polymer electrolytes have attracted great interest after displaying promising functionality for solid-state Li batteries. In this present work, poly(epsilon-caprolactone-co-trimethylene carbonate) electrolytes are further developed by the inclusion of ZrO2 particles, prepared by an in situ sol-gel method. SEM micrographs show that the ZrO2 particles are uniform and 30-50 nm in size. Contrary to many studies on filler-polymer electrolytes, the changes in ionic conductivity are less significant upon addition of zirconia filler to the polymer electrolyte, but remain at similar to 10(-5) S cm(-1) at room temperature. This can be explained by the amorphous nature of the polymer. Instead, high lithium transference numbers (0.83-0.87) were obtained. Plating/stripping tests with Li metal electrodes show long-term cycling performance for >1000 cycles at 0.2 mA cm(-2). Promising solid-state lithium battery cycling results at ambient temperature using the material are also shown.
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| 46. |
- Li, Zhenguang, et al.
(author)
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A concentrated poly(ethylene carbonate)/poly(trimethylene carbonate) blend electrolyte for all-solid-state Li battery
- 2019
-
In: Polymer journal. - : NATURE PUBLISHING GROUP. - 0032-3896 .- 1349-0540. ; 51:8, s. 753-760
-
Journal article (peer-reviewed)abstract
- Electrochemical and ion-transport properties of polymer blend electrolytes comprising poly(ethylene carbonate) (PEC), poly (trimethylene carbonate) (PTMC) and lithium bis(fluorosulfonyl) imide (LiFSI) were studied in this work, and the electrolyte with the best blend composition was applied in all-solid-state Li batteries. The ionic conductivity of both PEC and PTMC single-polymer electrolytes increased with increasing Li salt concentration. All PEC and PTMC blend electrolytes show ionic conductivities on the order of 10(-5) S cm(-1) at 50 degrees C, and the ionic conductivities increase slightly with increasing PEC contents. The PEC6PTMC4-LiFSI 150 mol% electrolyte demonstrated better Li/electrolyte electrochemical and interfacial stability than that of PEC and PTMC single-polymer electrolytes and maintained a polarization as low as 5 mV for up to 200 h during Li metal plating and stripping. A Li vertical bar SPE vertical bar LFP cell with the PEC6PTMC4-LiFSI 150 mol% electrolyte exhibited reversible charge/discharge capacities close to 150 mAh g(-1) at 50 degrees C and a C/10 rate, which is 88% of the theoretical value (170 mAh g(-1)).
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| 47. |
- Li, Zhenguang, et al.
(author)
-
Ion-Conductive and Thermal Properties of a Synergistic Poly(ethylene carbonate)/Poly(trimethylene carbonate) Blend Electrolyte
- 2018
-
In: Macromolecular rapid communications. - : WILEY-V C H VERLAG GMBH. - 1022-1336 .- 1521-3927. ; 39:14
-
Journal article (peer-reviewed)abstract
- Electrolytes comprising poly(ethylene carbonate) (PEC)/poly(trimethylene carbonate) (PTM C) with lithium bis(trifluoromethane sulfonyl)imide (LiTFSI) are prepared by a simple solvent casting method. Although PEC and PTMC have similar chemical structures, they are immiscible and two glass transitions are present in the differential scanning calorimetry (DSC) measurements. Interestingly, these two polymers change to miscible blends with the addition of LiTFSI, and the ionic conductivity increases with increasing lithium salt concentration. The optimum composition of the blend electrolyte is achieved at PEC6PTMC4, with a conductivity as high as 10(-6) S cm(-1) at 50 degrees C. This value is greater than that for single PEC- and PTMC-based electrolytes. Moreover, the thermal stability of the blend-based electrolytes is improved as compared to PEC-based electrolytes. It is clear that the interaction between C=O groups and Li+ gives rise to a compatible amorphous phase of PEC and PTMC.
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| 48. |
- Lindh, E. Mattias, et al.
(author)
-
The Weak Microcavity as an Enabler for Bright and Fault-tolerant Light-emitting Electrochemical Cells
- 2018
-
In: Scientific Reports. - : Nature Publishing Group. - 2045-2322. ; 8
-
Journal article (peer-reviewed)abstract
- The light-emitting electrochemical cell (LEC) is functional at substantial active-layer thickness, and is as such heralded for being fit for low-cost and fault-tolerant solution-based fabrication. We report here that this statement should be moderated, and that in order to obtain a strong luminous output, it is fundamentally important to fabricate LEC devices with a designed thickness of the active layer. By systematic experimentation and simulation, we demonstrate that weak optical microcavity effects are prominent in a common LEC system, and that the luminance and efficiency, as well as the emission color and the angular intensity, vary in a periodic manner with the active-layer thickness. Importantly, we demonstrate that high-performance light-emission can be attained from LEC devices with a significant active-layer thickness of 300 nm, which implies that low-cost solution-processed LECs are indeed a realistic option, provided that the device structure has been appropriately designed from an optical perspective.
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| 49. |
- Lv, Fei, et al.
(author)
-
Challenges and development of composite solid-state electrolytes for high-performance lithium ion batteries
- 2019
-
In: Journal of Power Sources. - : Elsevier. - 0378-7753 .- 1873-2755. ; 441
-
Research review (peer-reviewed)abstract
- The safety concerns and the pursuit of high energy density have stimulated the development of high-performance solid-state lithium ion batteries. Therefore, the key component in solid-state lithium batteries, i.e. the solid-state electrolytes, also has attracted tremendous attention due to its non-flammability and good adaptability to high-voltage cathodes/lithium metal anodes. An in-depth understanding of the existing problems of solid-state electrolytes and proposed strategies for addressing these problems is crucial for the efficient design of high-performance solid-state electrolytes. In this review, we systematically summarized the current limitations of composite solid-state electrolytes and efforts to overcome them, and gave some proposals for the future perspectives of solid-state electrolytes with the aim to provide practical guidance for the researchers in this area.
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| 50. |
- Mandal, Prithwiraj, et al.
(author)
-
Influence of Binder Crystallinity on the Performance of Si Electrodes with Poly(vinyl alcohol) Binders
- 2021
-
In: ACS Applied Energy Materials. - : American Chemical Society (ACS). - 2574-0962. ; 4:4, s. 3008-3016
-
Journal article (peer-reviewed)abstract
- Silicon is a highly promising electrode material for Li-ion batteries because of its high theoretical capacity, but severe volume changes during cycling leads to pulverization and rapid capacity fading. The use of alternative and water-soluble polymer binders such as poly(vinyl alcohol) (PVA) or poly(acrylic acid) (PAA) can improve the cycling performance of Si-based Li-ion batteries. Here, we investigate the effect of the substitution of the hydroxyl groups of PVA chains by carboxylic acid and acetate groups on the electrochemical performance of Si anodes in Li-ion batteries. Using modified PVAs, a model system is created spanning the chemical space between PVA and PAA, and the role of different Si-adhering functionalities is investigated. When comparing the electrochemical performance of Li-ion battery cells using Si anodes and the investigated binder systems, PVA with the highest degree of hydrolysis exhibits a superior performance (100 cycles with 1019 mAh g(-1)) compared to modified PVAs and PAA as a binder for Si anodes. An increased degree of hydrolysis of PVA is also seen to be beneficial for high capacity retention. These effects can be largely explained by the crystallinity of the binder system, which renders an improved electrode integrity during cycling and less swelling of the Si particles.
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