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1.	Abbafati, Cristiana, et al. (author) 2020 Journal article (peer-reviewed)
2.	Lodge, Andrew W., et al. (author) Critical appraisal on the role of catalysts for the oxygen reduction reaction in lithium-oxygen batteries 2014 In: Electrochimica Acta. - : Elsevier BV. - 0013-4686 .- 1873-3859. ; 140, s. 168-173 Journal article (peer-reviewed)abstract This work reports a detailed characterization of the reduction of oxygen in pyrrolidinium-based ionic liquids for application to lithium-oxygen batteries. It is found that, in the absence of Li+, all electron transfer kinetics are fast, and therefore, the reactions are limited by the mass transport rate. Reversible reduction of O-2 to O-2(center dot-) and O-2(center dot-) to O-2(2-) take place at E-0 = 2.1 V and 0.8 V vs. Li+/Li, respectively. In the presence of Li+, O-2 is reduced to LiO2 first and then to Li2O2. The solubility product constant of Li2O2 is found to be around 10(-51), corroborating the hypothesis that electrode passivation by Li2O2 deposition is an important issue that limits the capacity delivered by lithium-oxygen batteries. Enhancing the rate of Li2O2 formation by using different electrode materials would probably lead to faster electrode passivation and hence smaller charge due to oxygen reduction (smaller capacity of the battery). On the contrary, soluble redox catalysts can not only increase the reaction rate of Li2O2 formation but also avoid electrode passivation since the fast diffusion of the soluble redox catalyst would displace the formation of Li2O2 at a sufficient distance from the electrode surface.
3.	Mikheenkova, Anastasiia, et al. (author) Ageing of High Energy Density Automotive Li-Ion Batteries : The Effect of Temperature and State-of-Charge 2023 In: Journal of the Electrochemical Society. - : The Electrochemical Society. - 0013-4651 .- 1945-7111. ; 170:8 Journal article (peer-reviewed)abstract Lithium ion batteries (LIB) have become a cornerstone of the shift to electric transportation. In an attempt to decrease the production load and prolong battery life, understanding different degradation mechanisms in state-of-the-art LIBs is essential. Here, we analyze how operational temperature and state-of-charge (SoC) range in cycling influence the ageing of automotive grade 21700 batteries, extracted from a Tesla 3 long Range 2018 battery pack with positive electrode containing LiNixCoyAlzO2 (NCA) and negative electrode containing SiOx-C. In the given study we use a combination of electrochemical and material analysis to understand degradation sources in the cell. Herein we show that loss of lithium inventory is the main degradation mode in the cells, with loss of material on the negative electrode as there is a significant contributor when cycled in the low SoC range. Degradation of NCA dominates at elevated temperatures with combination of cycling to high SoC (beyond 50%).
4.	Mikheenkova, Anastasiia, et al. (author) Visualizing ageing-induced heterogeneity within large prismatic lithium-ion batteries for electric cars using diffraction radiography 2024 In: Journal of Power Sources. - : Elsevier BV. - 0378-7753 .- 1873-2755. ; 599 Journal article (peer-reviewed)abstract In this study, Synchrotron X-ray diffraction (XRD) radiography was utilized to investigate the ageing heterogeneity in 48 Ah prismatic lithium-ion cells with Ni-rich LiNi0.8Mn0.1Co0.1O2 (NMC811) as the positive electrode active material and graphite as the negative electrode active material after ∼2800 cycles. The study revealed that the area closest to the positive electrode tab is most vulnerable to degradation, particularly impacting the NMC material. Application of principal component analysis allowed to differentiate and visualize part of positive electrode material that has a different degradation due to the lithium plating. A comparison of non-destructive X-ray diffraction-based methods and electrochemical characterization method which was performed on the opened cell has shown an importance of a complementary approach. Our results highlight the feasibility of employing non-destructive techniques to study large prismatic cells, thereby presenting extensive opportunities for advancements in battery research and industry.
5.	Smith, Alexander J., et al. (author) Localized lithium plating under mild cycling conditions in high-energy lithium-ion batteries 2023 In: Journal of Power Sources. - : Elsevier. - 0378-7753 .- 1873-2755. ; 573 Journal article (peer-reviewed)abstract Conditions such as the temperature and pressure experienced by lithium-ion battery components are dependent on cell geometry and can vary widely within a large cell. The resulting uneven degradation is challenging to study at the full cell level but can be revealed upon disassembly and post mortem analysis. In this work, we report localized lithium plating in automotive-grade, prismatic lithium-ion cells, also under cycling conditions generally considered to be mild (e.g., 5–65 %SOC, 23 °C, 0.5C cycle rate). Dead lithium content is quantified using 7Li nuclear magnetic resonance spectroscopy in both electrode and separator samples, corresponding to substantial capacity fade (26–46%) of the full cells. Severe lithium plating is typically initiated in regions near the positive tab, in which both the separators and negative electrodes are ultimately deactivated. High pressure arises during cycling, and we propose a deactivation mechanism based on high local stress due to electrode expansion and external constraint. Further, we develop a model to demonstrate that component deactivation can result in lithium plating even under mild cycling conditions. Notably, components harvested from regions with no detected lithium plating maintained adequate electrochemical performance.
6.	Svens, Pontus, 1970-, et al. (author) Evaluating Performance and Cycle Life Improvements in the Latest Generations of Prismatic Lithium-Ion Batteries 2022 In: IEEE TRANSACTIONS ON TRANSPORTATION ELECTRIFICATION. - : Institute of Electrical and Electronics Engineers (IEEE). - 2332-7782. ; 8:3, s. 3696-3706 Journal article (peer-reviewed)abstract During the last decade, the market interest for electrified vehicles has increased considerably alongside global climate initiatives. This has coincided with vast improvements in automotive-grade, lithium-ion battery performance. This has increased the range of battery electric vehicles and plug-in hybrids, but lifetime remains a challenge. Aging during fast charging is especially difficult to understand due to its nonlinear dependence on charge rate, state-of-charge, and temperature. We present results from fast charging of several energy-optimized, prismatic lithium-ion battery cell generations with a nickel manganese cobalt (NMC)/graphite chemistry through comparison of capacity retention, resistance, and dQ/dV analysis. Changes in cell design have increased energy density by almost 50% over six years of cell development and acceptable cycle life can be expected, even under fast charging, when restricting the usage of the available capacity. Even though this approach reduces the useable energy density of a battery system, this tradeoff could still be acceptable for vehicle applications where conventional overnight charging is not possible. The tested cell format has been used for a decade in electrified vehicles. The ongoing development and improvement of this cell format by several cell manufacturers suggests that it will continue to be a good choice for future vehicles.
7.	Aktekin, Burak, et al. (author) Understanding the Capacity Loss in LiNi0.5Mn1.5O4-Li4Ti5O12 Lithium-Ion Cells at Ambient and Elevated Temperatures 2018 In: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 122:21, s. 11234-11248 Journal article (peer-reviewed)abstract The high-voltage spinel LiNi0.5Mn1.5O4, (LNMO) is an attractive positive electrode because of its operating voltage around 4.7 V (vs Li/Li+) and high power capability. However, problems including electrolyte decomposition at high voltage and transition metal dissolution, especially at elevated temperatures, have limited its potential use in practical full cells. In this paper, a fundamental study for LNMO parallel to Li4Ti5O12 (LTO) full cells has been performed to understand the effect of different capacity fading mechanisms contributing to overall cell failure. Electrochemical characterization of cells in different configurations (regular full cells, back-to-back pseudo-full cells, and 3-electrode full cells) combined with an intermittent current interruption technique have been performed. Capacity fade in the full cell configuration was mainly due to progressively limited lithiation of electrodes caused by a more severe degree of parasitic reactions at the LTO electrode, while the contributions from active mass loss from LNMO or increases in internal cell resistance were minor. A comparison of cell formats constructed with and without the possibility of cross-talk indicates that the parasitic reactions on LTO occur because of the transfer of reaction products from the LNMO side. The efficiency of LTO is more sensitive to temperature, causing a dramatic increase in the fading rate at 55 degrees C. These observations show how important the electrode interactions (cross-talk) can be for the overall cell behavior. Additionally, internal resistance measurements showed that the positive electrode was mainly responsible for the increase of resistance over cycling, especially at 55 degrees C. Surface characterization showed that LNMO surface layers were relatively thin when compared with the solid electrolyte interphase (SEI) on LTO. The SEI on LTO does not contribute significantly to overall internal resistance even though these films are relatively thick. X-ray absorption near-edge spectroscopy measurements showed that the Mn and Ni observed on the anode were not in the metallic state; the presence of elemental metals in the SEI is therefore not implicated in the observed fading mechanism through a simple reduction process of migrated metal cations.
8.	Bergfelt, Andreas, et al. (author) A Mechanical Robust yet highly Conductive Diblock Copolymer-based Solid Polymer Electrolyte for Room Temperature Structural Battery Applications 2020 In: ACS Applied Polymer Materials. - : American Chemical Society (ACS). - 2637-6105. ; 2:2, s. 939-948 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.
9.	Bergfelt, Andreas, et al. (author) ε-Caprolactone-based solid polymer electrolytes for lithium-ion batteries : synthesis, electrochemical characterization and mechanical stabilization by block copolymerization 2018 In: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 8:30, s. 16716-16725 Journal article (peer-reviewed)abstract In this work, three types of polymers based on epsilon-caprolactone have been synthesized: poly(epsilon-caprolactone), polystyrene-poly(epsilon-caprolactone), and polystyrene-poly(epsilon-caprolactone-r-trimethylene carbonate) (SCT), where the polystyrene block was introduced to improve the electrochemical and mechanical performance of the material. Solid polymer electrolytes (SPEs) were produced by blending the polymers with 10-40 wt% lithium bis(trifluoromethane) sulfonimide (LiTFSI). Battery devices were thereafter constructed to evaluate the cycling performance. The best performing battery half-cell utilized an SPE consisting of SCT and 17 wt% LiTFSI as both binder and electrolyte; a Li vertical bar SPE vertical bar LiFePO4 cell that cycled at 40 degrees C gave a discharge capacity of about 140 mA h g(-1) at C/5 for 100 cycles, which was superior to the other investigated electrolytes. Dynamic mechanical analysis (DMA) showed that the storage modulus E' was about 5 MPa for this electrolyte.
10.	Chien, Yu-Chuan, 1990-, et al. (author) Impact of Compression on the Electrochemical Performance of the Sulfur/Carbon Composite Electrode in Lithium-Sulfur Batteries 2022 In: Batteries & Supercaps. - : Wiley-VCH Verlagsgesellschaft. - 2566-6223. ; 5:7 Journal article (peer-reviewed)abstract While lithium-sulfur batteries theoretically have both high gravimetric specific energy and volumetric energy density, only its specific energy has been experimentally demonstrated to surpass that of the state-of-the-art lithium-ion systems at cell level. One major reason for the unrealized energy density is the low capacity density of the highly porous sulfur/carbon composite as the positive electrode. In this work, mechanical compression at elevated temperature is demonstrated to be an effective method to increase the capacity density of the electrode by at least 90 % and moreover extends its cycle life. Distinct impacts of compression on the resistance profiles of electrodes with different thickness are investigated by tortuosity factors derived from both electrochemical impedance spectroscopy, X-ray computed tomography and kinetic analysis based on operando X-ray diffraction. The results highlights the importance of a homogeneous electrode structure highlight lithium-sulfur system.
11.	Chien, Yu-Chuan, 1990-, et al. (author) Poly(Ethylene Glycol-block-2-Ethyl-2-Oxazoline) as Cathode Binder in Lithium-Sulfur Batteries 2021 In: ChemistryOpen. - : John Wiley & Sons. - 2191-1363. ; 10:10, s. 960-965 Journal article (peer-reviewed)abstract Functional binders constitute a strategy to overcome several challenges that lithium-sulfur (Li-S) batteries are facing due to soluble reaction intermediates in the positive electrode. Poly (ethylene oxide) (PEO) and poly (vinylpyrrolidone) (PVP) are in this context a previously well-explored binder mixture. Their ether and amide groups possess affinity to the dissolved sulfur species, which enhances the sulfur utilization and mitigates the parasitic redox shuttle. However, the immiscibility of PEO and PVP is a concern for electrode stability. Copolymers comprising ether and amide groups are thus promising candidates to improve the stability the system. Here, a series of poly (ethylene glycol-block-2-ethyl-2-oxazoline) with various block lengths is synthesized and explored as binders in S/C composite electrodes in Li-S cells. While the electrochemical analyses show that although the sulfur utilization and capacity retention of the tested electrodes are similar, the integrity of the as-cast electrodes can play a key role for power capability.
12.	Chien, Yu-Chuan, 1990-, et al. (author) Rapid determination of solid-state diffusion coefficients in Li-based batteries via intermittent current interruption method 2023 In: Nature Communications. - : Springer Nature. - 2041-1723. ; 14:1 Journal article (peer-reviewed)abstract The galvanostatic intermittent titration technique (GITT) is considered the go-to method for determining the Li+ diffusion coefficients in insertion electrode materials. However, GITT-based methods are either time-consuming, prone to analysis pitfalls or require sophisticated interpretation models. Here, we propose the intermittent current interruption (ICI) method as a reliable, accurate and faster alternative to GITT-based methods. Using Fick’s laws, we prove that the ICI method renders the same information as the GITT within a certain duration of time since the current interruption. Via experimental measurements, we also demonstrate that the results from ICI and GITT methods match where the assumption of semi-infinite diffusion applies. Moreover, the benefit of the non-disruptive ICI method to operando materials characterization is exhibited by correlating the continuously monitored diffusion coefficient of Li+ in a LiNi0.8Mn0.1Co0.1O2-based electrode to its structural changes captured by operando X-ray diffraction measurements.
13.	Chien, Yu-Chuan, 1990-, et al. (author) Towards reliable three-electrode cells for lithium–sulfur batteries 2022 In: Chemical Communications. - : Royal Society of Chemistry (RSC). - 1359-7345 .- 1364-548X. ; 58:5, s. 705-708 Journal article (peer-reviewed)abstract Three-electrode measurements are valuable to the understanding of the electrochemical processes in a battery system. However, their application in lithium–sulfur chemistry is difficult due to the complexity of the system and thus rarely reported. Here, we present a simple three-electrode cell format with relatively good life time and minimum interference with the cell operation.
14.	Jeschull, Fabian, et al. (author) A stable graphite negative electrode for the lithium-sulfur battery 2015 In: Chemical Communications. - 1359-7345 .- 1364-548X. ; 51:96, s. 17100-17103 Journal article (peer-reviewed)
15.	Jeschull, Fabian, et al. (author) Functional binders as graphite exfoliation suppressants in aggressive electrolytes for lithium-ion batteries 2015 In: Electrochimica Acta. - : Elsevier BV. - 0013-4686 .- 1873-3859. ; 175, s. 141-150 Journal article (peer-reviewed)abstract A comparative study of various electrode binders for graphite electrodes was conducted in a carbonate-based electrolyte with a high content of propylene carbonate (PC) as a means to evaluate anode degradation in presence of different binders. Because of its direct contact with the active material, a binder can be interpreted as an interfacial layer and as a local part of the electrolyte, the properties of which greatly depend on the interaction with the liquid electrolyte. In this work we demonstrate how a carefully chosen binder can create a specific surface environment that can protect graphite from exfoliation when the binder exhibits poor solubility in the electrolyte solvent and good surface adhesion to the active material. The exceptional stability of graphite electrodes containing poly(acrylic acid) sodium salt (PAA-Na) and carboxymethyl cellulose sodium salt (CMC-Na), respectively, in a PC-rich electrolyte is explained through the understanding of binder swelling and functionality. Interfacial resistances and electrochemical stability were investigated with impedance spectroscopy and galvanostatic cycling. Electrode morphologies and distributions of material were analysed with SEM and EDX. Evidence is presented that the surface selectivity increases with concentration of functional groups and polymer flexibility. Therefore only the less selective, stiff polymer with less functional groups, CMC-Na, provides sufficient protection at low binder contents.
16.	Jeschull, Fabian, et al. (author) Influence of inactive electrode components on degradation phenomena in nano-Si electrodes for Li-ion batteries 2016 In: Journal of Power Sources. - : Elsevier BV. - 0378-7753 .- 1873-2755. ; 325, s. 513-524 Journal article (peer-reviewed)abstract The electrode morphology and electrochemistry of silicon nanocomposite electrodes containing either carboxymethyl cellulose (CMC-Na) or poly(acrylic acid) (PAA) binders are examined in context of their working surface area. Using porous carbon (Ketjenblack) additives, coatings with poor adhesion properties and deep cracks were obtained. The morphology is also reflected in the electrochemical behavior under capacity-limited conditions. Mapping the differential capacity versus potential over all cycles yields detailed insights into the degradation processes and shows the onset of cell failure with the emergence of lithium-rich silicon alloys at low potentials, well before capacity fading is observed. Fading occurs faster with electrodes containing PAA binder. The surface area of the electrode components is a major cause of increased irreversible reaction and capacity fade. Synchrotron-based X-ray photoelectron spectroscopy on aged, uncycled electrodes revealed accelerated conversion of the native SiOx-layer to detrimental SiOxFy in presence of Ketjenblack. In contrast, a conventional carbon black better preserved the SiOx-layer. This effect is attributed to preferred adsorption of binder on high surface area electrode components and highlights the role of binders as 'artificial SEI-layers'. This work demonstrates that optimization of nanocomposites requires careful balancing of the surface areas and amounts of all the electrode components applied.
17.	Lacey, Matthew J, et al. (author) Analysis of soluble intermediates in the lithium-sulfur battery by a simple in situ electrochemical probe 2014 In: Electrochemistry communications. - : Elsevier BV. - 1388-2481 .- 1873-1902. ; 46, s. 91-93 Journal article (peer-reviewed)abstract This paper describes a simple setup using a thin, insulated platinum wire as an in situ electrochemical probe for analysis of the soluble polysulfide intermediates formed and consumed during the course of the discharge process of a lithium-sulfur cell. The probe, sharing common reference and counter electrodes with the cell, can be used to follow the changes in concentration of polysulfides in the electrolyte. The results herein both support and complement more advanced techniques studied elsewhere for understanding the dominant processes occurring in the cell.
18.	Lacey, Matthew J., et al. (author) Functional, water-soluble binders for improved capacity and stability of lithium-sulfur batteries 2014 In: Journal of Power Sources. - : Elsevier BV. - 0378-7753 .- 1873-2755. ; 264, s. 8-14 Journal article (peer-reviewed)abstract Binders based on mixtures of poly(ethylene oxide) (PEO) and poly(vinylpyrrolidone) (PVP) are here shown to significantly improve the reversible capacity and capacity retention of lithium- sulfur batteries compared to conventional binders. This mixed binder formulation combines the local improvement to the solvent system offered by PEO and the lithium (poly)sulfide-stabilising effect of PVP. Cells with cathodes made of simple mixtures of sulfur powder and carbon black with a binder of 4:1 PEO:PVP exhibited a reversible capacity of over 1000 mAh g(-1) at C/5 after 50 cycles and 800 mAh g(-1) at 1C after 200 cycles. Furthermore, these materials are water soluble, environmentally friendly and widely available, making them particularly interesting for large-scale production and applications in, for example, electric vehicles.
19.	Lacey, Matthew J., et al. (author) Porosity Blocking in Highly Porous Carbon Black by PVdF Binder and Its Implications for the Li-S System 2014 In: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 118:45, s. 25890-25898 Journal article (peer-reviewed)abstract In this work, the influence of cathode binders on the porosity of composite electrodes for lithiumsulfur (LiS) batteries employing high surface area carbon blacks has been closely scrutinized. This has been accomplished by comparison of PVdF with the related copolymer, PVdF-HFP. Analysis of carbon black porosity after addition of binder in NMP solution reveals that PVdF(-HFP) fills pores of almost any size in carbon black, which can effect a severe reduction in pore volume and surface area accessible to the electrolyte in a LiS cell. Noting the different swelling behavior of both binders, the implications of pore filling by the binder on the electrochemistry of LiS cells can be determined. Because of the low swellability of PVdF in dimethoxyethane:dioxolane (DME:DOL)-based electrolytes, access of the electrolyte to the carbon surface area and pore volume is restricted, with potentially severe detrimental effects on the available capacity of the cell. Furthermore, this effect is still clearly significant for common binder loadings and with preinfiltration of sulfur; this study is therefore a clear demonstration that PVdF is an unsuitable choice of binder for the lithiumsulfur system and that alternatives must be considered.
20.	Lacey, Matthew J., et al. (author) The Li-S battery : an investigation of redox shuttle and self-discharge behaviour with LiNO3-containing electrolytes 2016 In: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 6:5, s. 3632-3641 Journal article (peer-reviewed)abstract The polysulfide redox shuttle and self-discharge behaviour of lithium-sulfur (Li-S) cells containing the electrolyte additive LiNO3 has been thoroughly explored by a range of electrochemical and surface analysis techniques on simple Li-S (i.e., not specifically optimised to resist self-discharge) and symmetrical Li-Li cells. Despite the relatively effective passivation of the negative electrode by LiNO3, fully charged cells self-discharged a quarter of their capacity within 3 days, although in the short-term cells can be recharged without any noticeable capacity loss. The processes governing the rate and reversibility of self-discharge in these cells have been investigated and explained in terms of the reactions of polysulfides occurring at both electrodes during idle conditions.
21.	Lacey, Matthew J., et al. (author) Visualising the problems with balancing lithium-sulfur batteries by "mapping'' internal resistance 2015 In: Chemical Communications. - : Royal Society of Chemistry (RSC). - 1359-7345 .- 1364-548X. ; 51:92, s. 16502-16505 Journal article (peer-reviewed)abstract Frequent and continuous determination of battery internal resistance by a simple current-interrupt method enables the visualisation of cell behaviour through the creation of resistance "maps'', showing changes in resistance as a function of both capacity and cycle number. This new approach is applied here for the investigation of cell failure in the lithium-sulfur system with Li electrode excesses optimised towards practically relevant specifications.
22.	Lacey, Matthew J., et al. (author) Why PEO as a binder or polymer coating increases capacity in the Li-S system 2013 In: Chemical Communications. - : Royal Society of Chemistry (RSC). - 1359-7345 .- 1364-548X. ; 49:76, s. 8531-8533 Journal article (peer-reviewed)abstract PEO, used either as a binder or a polymer coating, and PEGDME, used as an electrolyte additive, are shown to increase the reversible capacity of Li-S cells. The effect, in all three cases, is the same: an improved solvent system for the electrochemistry of sulfur species and suppression of cathode passivation on discharge. This constitutes a novel interpretation of the mechanistic behaviour of polyethers in the Li-S system, and sheds new light upon several previous studies.
23.	Mathew, Alma, et al. (author) Investigating oxidative stability of lithium-ion battery electrolytes using synthetic charge-discharge profile voltammetry 2021 In: Journal of Power Sources Advances. - : Elsevier. - 2666-2485. ; 11 Journal article (peer-reviewed)abstract Electrolytes are an integral part of any electrochemical energy storage systems, including batteries. Among the many properties which determine the applicability of a Li-ion battery electrolyte, electrochemical stability - and for high voltage electrodes, in particular anodic stability - is a key parameter to consider. Despite being simple and straightforward to employ, the conventional linear sweep voltammetry (LSV) technique often leads to an over-estimation of the oxidative stability. In this study, an alternative approach termed Synthetic Charge-discharge Profile Voltammetry (SCPV) is explored to investigate the oxidative electrolyte stability. We have found this to be a convenient method of quantifying the anodic stability of the electrolyte in a more practically representative manner, in which passivation kinetics and electrode potential changes at the electrode-electrolyte interface are more appropriately reproduced. The viability of this technique is explored with liquid electrolytes based on ether, carbonate, sulfone and carbonate-sulfone mixtures, all with lithium hexafluorophosphate (LiPF6) salt, tested for a potential profile equivalent to LiNi0.5Mn1.5O4 electrodes. The credibility of this technique is validated by correlations to the coulombic efficiencies of corresponding half-cells.
24.	Mathew, Alma, et al. (author) Understanding the Capacity Fade in Polyacrylonitrile Binder-based LiNi0.5Mn1.5O4 Cells 2022 In: Batteries & Supercaps. - : John Wiley & Sons. - 2566-6223. ; 5:12 Journal article (peer-reviewed)abstract Abstract Binders are electrochemically inactive components that have a crucial impact in battery ageing although being present in only small amounts, typically 1?3?% w/w in commercial products. The electrochemical performance of a battery can be tailored via these inactive materials by optimizing the electrode integrity and surface chemistry. Polyacrylonitrile (PAN) for LiNi0.5Mn1.5O4 (LNMO) half-cells is here investigated as a binder material to enable a stable electrode-electrolyte interface. Despite being previously described in literature as an oxidatively stable polymer, it is shown that PAN degrades and develops resistive layers within the LNMO cathode. We demonstrate continuous internal resistance increase in LNMO-based cells during battery operation using intermittent current interruption (ICI) technique. Through a combination of on-line electrochemical mass spectrometry (OEMS) and X-ray photoelectron spectroscopy (XPS) characterization techniques, the degradation products can be identified as solid on the LNMO electrode surface, and no excessive gas formation seen. The increased resistance and parasitic processes are correlated to side-reactions of the PAN, possibly intramolecular cyclization, which can be identified as the main cause of the comparatively fast capacity fade.
25.	Mikheenkova, Anastasiia, et al. (author) Ageing of High Energy Density Automotive Li-ion Batteries: The Effect of Temperature and State-of-Charge Other publication (other academic/artistic)abstract Lithium ion batteries (LIB) have become a cornerstone of the shift to electric transportation. In an attempt to decrease the production load and prolong battery life, understanding different degradation mechanisms in state-of-the-art LIBs is essential. Here, we analyze how operational temperature and state-of-charge (SoC) range in cycling influence the ageing of automotive grade 21700 batteries, extracted from a Tesla 3 Long Range 2018 battery pack with positive electrode containing LiNixCoyAlzO2 (NCA) and negative electrode containing SiOx-C. In the given study we use a combination of electrochemical and material analysis to understand degradation sources in the cell. Herein we show that loss of lithium inventory is the main degradation mode in the cells, with loss of material on the negative electrode as there is a significant contributor when cycled in the low SoC range. Degradation of NCA dominates at elevated temperatures with combination of cycling to high SoC (beyond 50%).
26.	Mikheenkova, Anastasiia, et al. (author) Resolving high potential structural deterioration in Ni-rich layered cathode materials for lithium-ion batteries operando 2023 In: Journal of Energy Storage. - : Elsevier. - 2352-152X .- 2352-1538. ; 57 Journal article (peer-reviewed)abstract LixNi0.90Co0.05Al0.05O2 (NCA) extracted from an automotive battery cell is studied using a combination of in-house operando techniques to understand the correlation between gas evolution and structural collapse when NCA is cycled to high potentials in a lithium-ion battery configuration. The operando techniques comprise X-ray diffraction (XRD) and online electrochemical mass spectrometry (OEMS), and cycled using intermittent current interruption (ICI). The ICI cycling protocol is used to assess the dynamic change in resistance as well as to provide a validation of the operando setups. Both gas evolution and structural collapse have previously been observed as degradation mechanisms of Ni-rich electrodes including NCA, however, their causal link is still under debate. Here our presented results show a correlation between the decrease of the interlayer distance in NCA with both an increase in CO2 evolution and diffusion resistance above 4.1 V. Additionally, particle cracking, which is a mechanism often correlated with gas evolution, was found to be reversible and visible before gas evolution and Li diffusion resistance increase. The ICI technique is shown to be useful for the correlation of operando experiments on parallel setups and evaluation of mass transport dependent processes.
27.	Mindemark, Jonas, et al. (author) Beyond PEO-Alternative host materials for Li+-conducting solid polymer electrolytes 2018 In: Progress in polymer science. - : Elsevier BV. - 0079-6700 .- 1873-1619. ; 81, s. 114-143 Research review (peer-reviewed)abstract The bulk of the scientific literature on Li-conducting solid (solvent-free) polymer electrolytes (SPEs) for applications such as Li-based batteries is focused on polyether-based materials, not least the archetypal poly(ethylene oxide) (PEO). A significant number of alternative polymer hosts have, however, been explored over the years, encompassing materials such as polycarbonates, polyesters, polynitriles, polyalcohols and polyamines. These display fundamentally different properties to those of polyethers, and might therefore be able to resolve the key issues restricting SPEs from realizing their full potential, for example in terms of ionic conductivity, chemical or electrochemical stability and temperature sensitivity. It is further interesting that many of these polymer materials complex Li-ions less strongly than PEO and facilitate ion transport through different mechanisms than polyethers, which is likely critical for true advancement in the area. In this review, >30 years of research on these 'alternative' Li-ion-conducting SPE host materials are summarized and discussed in the perspective of their potential application in electrochemical devices, with a clear focus on Li batteries. Key challenges and strategies forward and beyond the current PEO-based paradigm are highlighted.
28.	Misiewicz, Casimir, et al. (author) Online electrochemical mass spectrometry on large-format Li-ion cells 2023 In: Journal of Power Sources. - : Elsevier. - 0378-7753 .- 1873-2755. ; 554 Journal article (peer-reviewed)abstract Advances in methodologies for real-time analysis of batteries have come a long way, especially with the development of Operando Electrochemical Mass Spectrometry (OEMS). These approaches allow for the deter-mination of side reactions during battery cycling with unprecedented selectivity and sensitivity, providing vital information necessary for determination of lifetime-limiting processes. However, the work thus far has primarily been carried out on model battery systems, where cell atmospheres are largely altered (through open flow, closed cell, and intermittent sampling approaches) and operation conditions are therefore not comparable with real-life situations. Herein, the development and validation of an intermittently closed OEMS system adapted for readily available commercial batteries is showcased. We provide a detailed description of a unique analysis design for large-format PHEV2 cells, with subsequent pressure and gassing data. A qualitative analysis of the results shows that side reactions brought on by structural transitions within both electrodes can be clearly observed. Transi-tions causing large volume changes in graphite induce H2 and C2H4 as SEI reformation products while the c lattice collapse in NMC induces CO2 evolution (through O2 release). OEMS can therefore be used for the quick and effective study of commercially available rechargeable batteries without influencing the internal battery chemistry.
29.	Ostli, Elise R., et al. (author) Limitations of Ultrathin Al2O3 Coatings on LNMO Cathodes 2021 In: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 6:45, s. 30644-30655 Journal article (peer-reviewed)abstract This study demonstrates the application of Al2O3 coatings for the high-voltage cathode material LiNi0.5–xMn1.5+xO4−δ (LNMO) by atomic layer deposition. The ultrathin and uniform coatings (0.6–1.7 nm) were deposited on LNMO particles and characterized by scanning transmission electron microscopy, inductively coupled plasma mass spectrometry, and X-ray photoelectron spectroscopy. Galvanostatic charge discharge cycling in half cells revealed, in contrast to many published studies, that even coatings of a thickness of 1 nm were detrimental to the cycling performance of LNMO. The complete coverage of the LNMO particles by the Al2O3 coating can form a Li-ion diffusion barrier, which leads to high overpotentials and reduced reversible capacity. Several reports on Al2O3-coated LNMO using alternative coating methods, which would lead to a less homogeneous coating, revealed the superior electrochemical properties of the Al2O3-coated LNMO, suggesting that complete coverage of the particles might in fact be a disadvantage. We show that transition metal ion dissolution during prolonged cycling at 50 °C is not hindered by the coating, resulting in Ni and Mn deposits on the Li counter electrode. The Al2O3-coated LNMO particles showed severe signs of pitting dissolution, which may be attributed to HF attack caused by side reactions between the electrolyte and the Al2O3 coating, which can lead to additional HF formation. The pitting dissolution was most severe for the thickest coating (1.7 nm). The uniform coating coverage may lead to non-uniform conduction paths for Li, where the active sites are more susceptible to HF attack. Few benefits of applications of very thin, uniform, and amorphous Al2O3 coatings could thus be verified, and the coating is not offering long-term protection from HF attack.
30.	Salian, Girish D., et al. (author) Investigation of Water-Soluble Binders for LiNi0.5Mn1.5O4-Based Full Cells 2022 In: ChemistryOpen. - : John Wiley & Sons. - 2191-1363. ; 11:6 Journal article (peer-reviewed)abstract Two water-soluble binders of carboxymethyl cellulose (CMC) and sodium alginate (SA) have been studied in comparison with N-methylpyrrolidone-soluble poly(vinylidene difluoride-co-hexafluoropropylene) (PVdF-HFP) to understand their effect on the electrochemical performance of a high-voltage lithium nickel manganese oxide (LNMO) cathode. The electrochemical performance has been investigated in full cells using a Li4Ti5O12 (LTO) anode. At room temperature, LNMO cathodes prepared with aqueous binders provided a similar electrochemical performance as those prepared with PVdF-HFP. However, at 55 degrees C, the full cells containing LNMO with the aqueous binders showed higher cycling stability. The results are supported by intermittent current interruption resistance measurements, wherein the electrodes with SA showed lower resistance. The surface layer formed on the electrodes after cycling has been characterized by X-ray photoelectron spectroscopy. The amount of transition metal dissolutions was comparable for all three cells. However, the amount of hydrogen fluoride (HF) content in the electrolyte cycled at 55 degrees C is lower in the cell with the SA binder. These results suggest that use of water-soluble binders could provide a practical and more sustainable alternative to PVdF-based binders for the fabrication of LNMO electrodes.
31.	Salian, Girish D., et al. (author) Understanding the electrochemical and interfacial behaviour of sulfolane-based electrolytes in LiNi0.5Mn1.5O4-graphite full-cells 2023 In: Batteries & Supercaps. - : John Wiley & Sons. - 2566-6223. ; n/a:n/a Journal article (peer-reviewed)abstract An ethylene carbonate-free electrolyte composed of 1 M lithium bis(fluorosulfonyl) imide (LiFSI) in sulfolane (SL) is studied here for LiNi0.5Mn1.5O4-graphite full-cells. An important focus on the evaluation of the anodic stability of the SL electrolyte and the passivation layers formed on LNMO and graphite is being analysed along with intermittent current interruption (ICI) technique to observe the resistance while cycling. The results show that the sulfolane electrolyte shows more degradation at higher potentials unlike previous reports which suggested higher oxidative stability. However, the passivation layers formed due to this electrolyte degradation prevents further degradation. The resistance measurements show that major resistance arises from the cathode. The pressure evolution during the formation cycles suggests that there is lower gas evolution with sulfolane electrolyte than in the conventional electrolyte. The study opens a new outlook on the sulfolane based electrolyte especially regarding its oxidative/anodic stability.
32.	Srivastav, Shruti, et al. (author) State-of-charge indication in Li-ion batteries by simulated impedance spectroscopy 2017 In: Journal of Applied Electrochemistry. - : Springer Science and Business Media LLC. - 0021-891X .- 1572-8838. ; 47:2, s. 229-236 Journal article (peer-reviewed)abstract We here explore the possibilities of correlating experimental cell impedance with finite element methodology modelling for state-of-charge (SoC) indication in LiFePO-based half-cells. The impedance response has been modelled sequentially during battery cycling using Newman theory, and is compared with experimental data. It is found that the charge-transfer resistance is dependent of SoC during battery charging, which can be modelled in good agreement with experimental results. Moreover, it is seen that cell design parameters-e.g. calendering-dependent electrode porosity-influence the EIS response and can thus be estimated using the presented methodology.
33.	Sun, Bing, et al. (author) Electrodeposition of thin poly(propylene glycol) acrylate electrolytes on 3D-nanopillar electrodes 2014 In: Electrochimica Acta. - : Elsevier BV. - 0013-4686 .- 1873-3859. ; 137, s. 320-327 Journal article (peer-reviewed)
34.	Østli, Elise R., et al. (author) On the Durability of Protective Titania Coatings on High‐Voltage Spinel Cathodes 2022 In: ChemSusChem. - : John Wiley & Sons. - 1864-5631 .- 1864-564X. ; 15:12 Journal article (peer-reviewed)abstract TiO2-coating of LiNi0.5-xMn1.5+xO4 (LNMO) by atomic layer deposition (ALD) has been studied as a strategy to stabilize the cathode/electrolyte interface and mitigate transition metal (TM) ion dissolution. The TiO2 coatings were found to be uniform, with thicknesses estimated to 0.2, 0.3, and 0.6 nm for the LNMO powders exposed to 5, 10, and 20 ALD cycles, respectively. While electrochemical characterization in half-cells revealed little to no improvement in the capacity retention neither at 20 nor at 50 °C, improved capacity retention and coulombic efficiencies were demonstrated for the TiO2-coated LNMO in LNMO\|\|graphite full-cells at 20 °C. This improvement in cycling stability could partly be attributed to thinner cathode electrolyte interphase on the TiO2-coated samples. Additionally, energy-dispersive X-ray spectroscopy revealed a thinner solid electrolyte interphase on the graphite electrode cycled against TiO2-coated LNMO, indicating retardation of TM dissolution by the TiO2-coating.

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