腈基功能化有机硅氧烷成膜添加剂的合成及其在NCM811/Li电池中的应用

Synthesis of Nitrile-Functionalized Organosiloxane as Film-Forming Additive for NCM811 Lithium-Ion Batteries

设计合成了一种腈基功能化有机硅氧烷化合物2-甲基-4-(1,1,3,3,3-五甲基二硅氧烷)丁腈(DSMCN),研究其作为电解液添加剂在高能量密度高镍三元NCM811电池中的电化学性能。利用线性扫描伏安法(LSV)测试了DSMCN的氧化电位,考察了DSMCN添加剂对富镍三元NCM811电池的循环、倍率和高温等条件下的电化学性能。在25℃下,NCM811/Li电池在1 C倍率下循环200圈后,容量保持率由基础电解液的80.93%提升至94.89%;在55℃的高温下,容量保持率从59.52%提升至88.09%。电化学阻抗谱(EIS)、扫描电子显微镜(SEM)和X射线衍射(XRD)等测试发现,DSMCN化合物能够在NCM811电极表面参与形成更稳定、均匀致密的正极电解质界面膜,展现出更优的电化学动力学特征,降低了界面阻抗,有利于常/高温下电极/电解液界面的Li+扩散和电荷转移,从而提高了NCM811电池的电化学性能。

A nitrile-containing organodisiloxane compound 2-methyl-4-(1,1,3,3,3-pentamethyldisiloxane)butanenitrile(DSMCN)was designed and synthesized as an efficient electrolyte additive for improving the electrochemical performance of high energy density NCM811 batteries.The oxidation potential of the compound was tested using linear scanning voltammetry(LSV),and the electrochemical performances of NCM811 cells with DSMCN additive,including the cycling,rate and high-temperature performance were investigated and compared with those with the base electrolytes without DSMCN.The results demonstrated that the capacity retention of NCM811/Li half cells at room temperature was improved from 80.93%of the base electrolyte to 94.89%after 200 cycles at 1 C,while the capacity retention at a high temperature of 55℃was increased from 59.52%to 88.09%.Electrochemical impedance spectroscopy(EIS),scanning electron microscopy(SEM),and X-ray diffraction(XRD)tests revealed that DSMCN participates in forming a more stable,uniform,and dense cathode electrolyte interphase layer on the NCM811 electrode surface,which leads to improved electrochemical kinetics,reduced interfacial impedance,and enhanced Li+diffusion and charge transfer at the electrode/electrolyte interface under both normal and high-temperature conditions,thereby improving the electrochemical performance of NCM811 batteries.