| 1. |
- Ahlberg Tidblad, Annika, et al.
(författare)
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Future Material Developments for Electric Vehicle Battery Cells Answering Growing Demands from an End-User Perspective
- 2021
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Ingår i: Energies. - : MDPI. - 1996-1073. ; 14:14
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Forskningsöversikt (refereegranskat)abstract
- Nowadays, batteries for electric vehicles are expected to have a high energy density, allow fast charging and maintain long cycle life, while providing affordable traction, and complying with stringent safety and environmental standards. Extensive research on novel materials at cell level is hence needed for the continuous improvement of the batteries coupled towards achieving these requirements. This article firstly delves into future developments in electric vehicles from a technology perspective, and the perspective of changing end-user demands. After these end-user needs are defined, their translation into future battery requirements is described. A detailed review of expected material developments follows, to address these dynamic and changing needs. Developments on anodes, cathodes, electrolyte and cell level will be discussed. Finally, a special section will discuss the safety aspects with these increasing end-user demands and how to overcome these issues.
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| 2. |
- Dhillon, Shweta, et al.
(författare)
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Modelling capacity fade in silicon-graphite composite electrodes for lithium-ion batteries
- 2021
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Ingår i: Electrochimica Acta. - : Elsevier. - 0013-4686 .- 1873-3859. ; 377
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Tidskriftsartikel (refereegranskat)abstract
- Silicon-based composite electrodes in lithium ion batteries attract increasing attention because of their high theoretical capacity. Here, numerical simulations are used to better understand the interplay between electrochemical and morphological behavior of the silicon-graphite (1:2.7) composite electrode during galvanostatic cycling. Finite element methodology is used to solve a one-dimensional model based on the porous electrode and concentrated solution theory. Porosity changes in the silicon electrode and solid electrolyte interphase layer growth are also included in the model. The simulation results show that at lower rates, the electrode with high initial porosity is being fully utilized before the lower cut-off potential is reached. When comparing the computational results with experimental observations, it can be seen that the main reason for capacity fade is the increase in tortuosity in the diffusion pathway of lithium ions due to cracking of the silicon composite electrode upon electrochemical cycling.
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| 3. |
- Hernández, Guiomar, et al.
(författare)
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Going beyond sweep voltammetry : Alternative approaches in search of the elusive electrochemical stability of polymer electrolytes
- 2021
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Ingår i: Journal of the Electrochemical Society. - : The Electrochemical Society. - 0013-4651 .- 1945-7111. ; 168:10
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Tidskriftsartikel (refereegranskat)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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| 4. |
- Lee, Tian Khoon, et al.
(författare)
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Polyester-ZrO2 Nanocomposite Electrolytes with High Li Transference Numbers for Ambient Temperature All-Solid-State Lithium Batteries
- 2021
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Ingår i: Batteries & Supercaps. - : John Wiley & Sons. - 2566-6223. ; 4:4, s. 653-662
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Tidskriftsartikel (refereegranskat)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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| 5. |
- Mandal, Prithwiraj, et al.
(författare)
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Influence of Binder Crystallinity on the Performance of Si Electrodes with Poly(vinyl alcohol) Binders
- 2021
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Ingår i: ACS Applied Energy Materials. - : American Chemical Society (ACS). - 2574-0962. ; 4:4, s. 3008-3016
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Tidskriftsartikel (refereegranskat)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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| 6. |
- Nkosi, Funeka P., et al.
(författare)
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Garnet-Poly(epsilon-caprolactone-co-trimethylene carbonate) Polymer-in-Ceramic Composite Electrolyte for All-Solid-State Lithium-Ion Batteries
- 2021
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Ingår i: ACS Applied Energy Materials. - : American Chemical Society (ACS). - 2574-0962. ; 4:3, s. 2531-2542
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Tidskriftsartikel (refereegranskat)abstract
- A composite electrolyte based on a garnet electrolyte (LLZO) and polyester-based co-polymer (80:20 epsilon-caprolactone (CL)-trimethylene carbonate, PCL-PTMC with LiTFSI salt) is prepared. Integrating the merits of both ceramic and co-polymer electrolytes is expected to address the poor ionic conductivity and high interfacial resistance in solid-state lithium-ion batteries. The composite electrolyte with 80 wt % LLZO and 20 wt % polymer (PCL-PTMC and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) at 72:28 wt %) exhibited a Li-ion conductivity of 1.31 X 10(-4) S/cm and a transference number (t(Li+)) of 0.84 at 60 degrees C, notably higher than those of the pristine PCL-PTMC electrolyte. The prepared composite electrolyte also exhibited an electrochemical stability of up to 5.4 V vs Li+/Li. The interface between the composite electrolyte and a LiFePO4 (LFP) cathode was also improved by direct incorporation of the polymer electrolyte as a binder in the cathode coating. A Li/composite electrolyte/LFP solid-state cell provided a discharge capacity of ca. 140 mAh/g and suitable cycling stability at 55 degrees C after 40 cycles. This study clearly suggests that this type of amorphous polyester-based polymers can be applied in polymer-in-ceramic composite electrolytes for the realization of advanced all-solid-state lithium-ion batteries.
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| 7. |
- Park, Bumjun, et al.
(författare)
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Ion Coordination and Transport in Magnesium Polymer Electrolytes Based on Polyester-co-Polycarbonate
- 2021
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Ingår i: Energy Material Advances. - : American Association for the Advancement of Science (AAAS). - 2692-7640. ; 2021, s. 1-14
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Tidskriftsartikel (refereegranskat)abstract
- Magnesium-ion-conducting solid polymer electrolytes have been studied for rechargeable Mg metal batteries, one of the beyond-Li-ion systems. In this paper, magnesium polymer electrolytes with magnesium bis(trifluoromethane)sulfonimide (Mg(TFSI)2) salt in poly(ε-caprolactone-co-trimethylene carbonate) (PCL-PTMC) were investigated and compared with the poly(ethylene oxide) (PEO) analogs. Both thermal properties and vibrational spectroscopy indicated that the total ion conduction in the PEO electrolytes was dominated by the anion conduction due to strong polymer coordination with fully dissociated Mg2+. On the other hand, in PCL-PTMC electrolytes, there is relatively weaker polymer–cation coordination and increased anion–cation coordination. Sporadic Mg- and F-rich particles were observed on the Cu electrodes after polarization tests in Cu|Mg cells with PCL-PTMC electrolyte, suggesting that Mg was conducted in the ion complex form (MgxTFSIy) to the copper working electrode to be reduced which resulted in anion decomposition. However, the Mg metal deposition/stripping was not favorable with either Mg(TFSI)2 in PCL-PTMC or Mg(TFSI)2 in PEO, which inhibited quantitative analysis of magnesium conduction. A remaining challenge is thus to accurately assess transport numbers in these systems.
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