| 1. |
- Cabañero Martínez, Maria Angeles, et al.
(författare)
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Are Polymer‐Based Electrolytes Ready for High‐Voltage Lithium Battery Applications? An Overview of Degradation Mechanisms and Battery Performance
- 2022
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Ingår i: Advanced Energy Materials. - : John Wiley & Sons. - 1614-6832 .- 1614-6840. ; 12:32, s. 2201264-2201264
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Tidskriftsartikel (refereegranskat)abstract
- High-voltage lithium polymer cells are considered an attractive technology that could out-perform commercial lithium-ion batteries in terms of safety, processability, and energy density. Although significant progress has been achieved in the development of polymer electrolytes for high-voltage applications (> 4 V), the cell performance containing these materials still encounters certain challenges. One of the major limitations is posed by poor cyclability, which is affected by the low oxidative stability of standard polyether-based polymer electrolytes. In addition, the high reactivity and structural instability of certain common high-voltage cathode chemistries further aggravate the challenges. In this review, the oxidative stability of polymer electrolytes is comprehensively discussed, along with the key sources of cell degradation, and provides an overview of the fundamental strategies adopted for enhancing their cyclability. In this regard, a statistical analysis of the cell performance is provided by analyzing 186 publications reported in the last 17 years, to demonstrate the gap between the state-of-the-art and the requirements for high-energy density cells. Furthermore, the essential characterization techniques employed in prior research investigating the degradation of these systems are discussed to highlight their prospects and limitations. Based on the derived conclusions, new targets and guidelines are proposed for further research.
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| 2. |
- Jamal, Ali, et al.
(författare)
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Tris(trimethylsilyl) Phosphite and Lithium Difluoro(oxalato)borate as Electrolyte Additives for LiNi0.5Mn1.5O4-Graphite Lithium-Ion Batteries
- 2023
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Ingår i: ChemElectroChem. - : Wiley-VCH Verlagsgesellschaft. - 2196-0216. ; 10:16
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Tidskriftsartikel (refereegranskat)abstract
- Raising the energy density of lithium-ion batteries (LIBs) through the operation of high-voltage cathodes presents a challenge in terms of practical use due to electrolyte degradation. Consequently, it is imperative to explore new materials to circumvent this issue. In this study, a combination of tris(trimethylsilyl) phosphite (TMSPi) and lithium difluoro(oxalato)borate (LiDFOB) is presented as film-forming additives in a conventional LiPF6-containing carbonate-based electrolyte solution in high-voltage LiNi0.5Mn1.5O4-graphite full cells. At high voltage, TMSPi oxidizes on the LiNi0.5Mn1.5O4 (LNMO) cathode surface prior to the decomposition of electrolyte solvents, promoting the formation of a stable cathode electrolyte interphase (CEI) layer. In tandem, given that LiDFOB has a lower reduction potential than ethylene carbonate (EC), it has the possibility of forming a solid electrolyte interphase (SEI) on the graphite anode surface. Combining the two additives was found to suppress the degradation of the electrolyte to a large extent. Among the investigated concentration of the additives, the combination of 1 wt. % TMSPi and 2 wt. % LiDFOB added to LP40 electrolyte exhibits improved capacity retention of 80 % after 400 cycles at 0.3 C, compared to the electrolyte with no additive with 67 % capacity retention over the same period. Thereby, the combination of TMSPi with LiDFOB provides an improvement for high voltage LIBs.
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| 3. |
- Salian, Girish D., et al.
(författare)
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Investigation of Water-Soluble Binders for LiNi0.5Mn1.5O4-Based Full Cells
- 2022
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Ingår i: ChemistryOpen. - : John Wiley & Sons. - 2191-1363. ; 11:6
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Tidskriftsartikel (refereegranskat)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.
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| 4. |
- Salian, Girish D., et al.
(författare)
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Understanding the electrochemical and interfacial behaviour of sulfolane-based electrolytes in LiNi0.5Mn1.5O4-graphite full-cells
- 2023
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Ingår i: Batteries & Supercaps. - : John Wiley & Sons. - 2566-6223. ; n/a:n/a
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Tidskriftsartikel (refereegranskat)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.
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