Two oxalatoborate ionic liquids (ILs), which are commonly utilized as electrolyte additives that form a protective layer on the cathode surface, are investigated for the first time as electrode additives. Cathodes based on LiNi0.5Mn1.5O4 (LNMO) containing 3 wt% ILs, i.e., "IL‐enriched cathodes", exhibit capacity values above 120 mAh/g with high Coulombic efficiencies throughout cycling over 200 times. A cathode without ILs also exhibits a capacity of 119 mAh/g but its Coulombic efficiency becomes low and unstable after 109 cycles. In addition, when 0.3 M ILs are added to conventional carbonate‐based electrolytes, the battery cycle life improves but there is a reduction in the capacity probably due to low ionic conductivity of the electrolyte mixtures. Post‐mortem analyses of electrodes retrieved from cycled cells highlight less electrolyte decomposition and less cathode corrosion, enabled by using the IL as the additive in LNMO, which are confirmed by a particle shape with smooth surface identical to the fresh cathode. The study demonstrates that oxalatoborate ILs can be used as the electrode additive, and this provides a new concept for cathode formulations for high performance batteries with a small amount of ILs.

中文翻译：

---

离子液体作为高压锂电池正极添加剂

两种草酸硼酸盐离子液体（IL）通常用作电解质添加剂，在阴极表面形成保护层，这是首次将其作为电极添加剂进行研究。基于含有 3 wt% IL 的 LiNi0.5Mn1.5O4 (LNMO) 的阴极，即“富含 IL 的阴极”，在超过 200 次的循环过程中表现出高于 120 mAh/g 的容量值和高库仑效率。没有ILs的正极也表现出119 mAh/g的容量，但其库仑效率在109次循环后变得低且不稳定。此外，当将 0.3 M IL 添加到传统的碳酸酯基电解质中时，电池循环寿命得到改善，但容量会降低，这可能是由于电解质混合物的离子电导率较低。对从循环电池中取出的电极进行的尸检分析强调，通过使用 IL 作为 LNMO 中的添加剂，可以减少电解质分解和减少阴极腐蚀，这通过具有与新鲜阴极相同的光滑表面的颗粒形状来证实。研究表明，草酸硼酸盐离子液体可用作电极添加剂，这为少量液体液体的高性能电池的正极配方提供了新概念。