Fluoroethylene Carbonate: Bis(2,2,2,) Trifluoroethyl Carbonate as High Performance Electrolyte Solvent Blend for High Voltage Application in NMC811|| Silicon Oxide-Graphite Lithium Ion Cells,Small Structures

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Fluoroethylene Carbonate: Bis(2,2,2,) Trifluoroethyl Carbonate as High Performance Electrolyte Solvent Blend for High Voltage Application in NMC811|| Silicon Oxide-Graphite Lithium Ion Cells
Small Structures ( IF 13.9 ) Pub Date : 2024-04-18 , DOI: 10.1002/sstr.202400063
Feleke Demelash _{1,

2} , Aurora Gomez‐Martin ₁ , Bastian Heidrich _{1,

2} , Egy Adhitama _{1,

2,

3} , Patrick Harte ₁ , Atif Javed _{1,

2,

3} , Anindityo Arifiadi _{1,

2,

3} , Marlena M. Bela _{1,

2} , Peng Yan ₄ , Patrick Harte ₁ , Diddo Diddens ₄ , Martin Winter _{1,

2,

3,

4} , Philip Niehoff ₁

Affiliation

LiNi_xMn_yCo_zO₂ cathode materials combined with Si-based anode materials are current state-of-the-art high energy density chemistries for lithium ion batteries. Increasing the upper cut-off voltage is an intriguing approach to achieve even higher energy density in lithium ion batteries. However, poor oxidation stability of the state-of-the-art electrolytes leads to transition metal dissolution (TMD), migration, and deposition (TMDMD) on the negative electrode, followed by sudden and rapid capacity fade. Furthermore, the chemical instability of the lithium hexafluorophosphate causes hydro-fluoric acid to develop, which targets the native SiO_x layers on silicon anodes and breaks the chemical bond to the carboxymethylcellulose sodium salt binder. Herein, a fluorine-rich electrolyte formulation consisting of lithium-bis(fluorsulfonyl)imide with fluoroethylene carbonate (FEC): bis(2,2,2,) trifluoroethyl carbonate (BFEC) was applied in NMC811||10%SiO_x-90%graphite cells to achieve high oxidation stability and prevent TMD and deposition. Up-to-date, this is the premier electrochemical performance reported in literature with a capacity retention of 94.5% and 92.2% with 0.5 °C and 4.5 V upper cut-off voltage cycling at 20 and 40 °C after 100 cycles, respectively. The post mortem analysis showed that stabilization is achieved by forming inorganic- and salt-rich interphases that protect the electrolyte versus decomposition at the electrode.

中文翻译：

氟乙烯碳酸酯：双(2,2,2,)三氟乙基碳酸酯作为高性能电解质溶剂混合物，用于 NMC811 中的高压应用||氧化硅-石墨锂离子电池

LiNi _x Mn _y Co _z O ₂正极材料与硅基负极材料相结合是当前最先进的锂离子电池高能量密度化学材料。提高上限截止电压是实现锂离子电池更高能量密度的一种有趣方法。然而，最先进的电解质的氧化稳定性较差，会导致负极上过渡金属溶解（TMD）、迁移和沉积（TMDMD），然后导致容量突然快速衰减。此外，六氟磷酸锂的化学不稳定性会导致氢氟酸的产生，其目标是硅阳极上的天然SiO _x层并破坏与羧甲基纤维素钠盐粘合剂的化学键。在此，由双(氟磺酰基)亚胺锂和碳酸氟乙烯酯(FEC)：碳酸双(2,2,2,)三氟乙酯(BFEC)组成的富氟电解质配方应用于NMC811||10%SiO _x -90 %石墨电池实现高氧化稳定性并防止TMD和沉积。迄今为止，这是文献报道的首要电化学性能，在 0.5 °C 和 4.5 V 上限截止电压、20 °C 和 40 °C 下循环 100 次后，容量保持率分别为 94.5% 和 92.2%。事后分析表明，稳定是通过形成富含无机和盐的界面来实现的，这些界面可以保护电解质免于在电极上分解。

更新日期：2024-04-18

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