Park Min Woo, Park Sewon, Choi Nam-Soon
School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), 50, UNIST-gil, Ulsan 44919, Republic of Korea.
ACS Appl Mater Interfaces. 2020 Sep 30;12(39):43694-43704. doi: 10.1021/acsami.0c11996. Epub 2020 Sep 16.
The introduction of a trimethylsilyl (TMS) motif in electrolyte additives for lithium-ion batteries is regarded as an effectual approach to remove corrosive hydrofluoric acid (HF) that structurally and compositionally damages the electrode-electrolyte interface and gives rise to transition metal dissolution from the cathode. Herein, we present that electrolyte additives with TMS moieties lead to continued capacity loss of polycrystalline (PC)-LiNiCoMnO (NCM811) cathodes coupled with graphite anodes compared to additives without TMS as the cycle progresses. Through a comparative study using electrolyte additives with and without TMS moieties, it is revealed that the TMS group is prone to react with residual lithium compounds, in particular, lithium hydroxide (LiOH) on the PC-NCM811 cathode, and the resulting TMS-OH triggers the decomposition of PF created by the autocatalytic decomposition of LiPF that generates reactive species, namely, HF and POF. This work aims to offer a way to build favorable interface structures for Ni-rich cathodes covered with residual lithium compounds through a study to figure out the roles of TMS moieties of electrolyte additives.
在锂离子电池电解质添加剂中引入三甲基硅基（TMS）基团被认为是一种有效的方法，可去除腐蚀性氢氟酸（HF），这种酸会在结构和成分上破坏电极 - 电解质界面，并导致过渡金属从阴极溶解。在此，我们表明，与不含TMS的添加剂相比，随着循环的进行，含有TMS基团的电解质添加剂会导致多晶（PC）-LiNiCoMnO（NCM811）阴极与石墨阳极耦合时持续的容量损失。通过使用含和不含TMS基团的电解质添加剂的对比研究发现，TMS基团易于与残留的锂化合物反应，特别是PC-NCM811阴极上的氢氧化锂（LiOH），生成的TMS-OH会引发由LiPF自催化分解产生的PF的分解，LiPF自催化分解会产生活性物质，即HF和POF。这项工作旨在通过研究弄清楚电解质添加剂中TMS基团的作用，为覆盖有残留锂化合物的富镍阴极构建良好的界面结构提供一种方法。
