Poor cycling performance for many high voltage lithium ion batteries (LIB) has been attributed to damage of the anode solid electrolyte interphase (SEI) resulting from crossover reactions. Transition-metal ion crossover has been proposed as a primary source of SEI damage and capacity loss, especially for high-voltage spinel cathodes. However, deposition of transition metals on the anode SEI may not be the primary source of SEI degradation. This investigation focuses on the oxidative decomposition of LiPF₆ in ethylene carbonate (EC)-based carbonate electrolytes to generate acidic species which subsequently cross over to the anode and degrade the anode SEI components. The generation of the strong acid, difluorophosphoric acid (F₂PO₂H), has been quantified for both graphite || LiNi_0.5Mn_1.5O₄ and graphite || LiMn₂O₄ cells. There is a correlation between the concentration F₂PO₂H, SEI degradation, and the capacity loss of the cells.

中文翻译：

---

电解液氧化和二氟磷酸生成在锂离子电池交叉和容量衰减中的作用

许多高压锂离子电池 (LIB) 的循环性能不佳归因于交叉反应导致阳极固体电解质中间相 (SEI) 的损坏。过渡金属离子交叉被认为是 SEI 损坏和容量损失的主要来源，尤其是对于高压尖晶石阴极。然而，过渡金属在阳极 SEI 上的沉积可能不是 SEI 降解的主要来源。该研究的重点是 LiPF ₆在基于碳酸亚乙酯 (EC) 的碳酸盐电解质中的氧化分解，以生成酸性物质，随后这些物质会转移到阳极并降解阳极 SEI 组分。生成强酸二氟磷酸（F ₂ PO ₂H), 已被量化为石墨 || LiNi _0.5 Mn _1.5 O ₄和石墨 || LiMn ₂ O ₄电池。F ₂ PO ₂ H浓度、SEI 降解和电池容量损失之间存在相关性。