Constructing Si/O‐Enriched Cathode Electrolyte Interphase by Amiontrisiloxane Additive for Advanced NCM811/SiC Batteries

LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811) cathode material has been increasingly applied in industry for lithium‐ion batteries owing to its high specific capacity. However, the quick capacity fade of these batteries, especially at high temperatures, remains a major technical issue to be resolved for practical applications. In this work, an aminotrisiloxane compound (HMTSN) as an electrolyte additive to enhance the cycling performance of NCM811 cells by constructing a robust cathode electrolyte interphase (CEI) on the cathode surface and scavenging corrosive acidic species in the electrolyte is designed and synthesized. The trisiloxane moiety in HMTSN forms a homogeneous CEI with a higher Young's modulus in comparison with the baseline electrolyte without 0.5 wt% HMTSN additive. Additionally, the transition metals dissolution and the Li + /Ni 2+ mixing in the NCM811 is significantly inhibited due to the formed CEI and removal of acidic species, thus improved electrochemical performance for NCM811/graphite coin cell, especially the rate capability at 10C. The NCM811/SiC pouch cell demonstrates superior high‐temperature cycling stability at 55 °C, showing a higher capacity retention of 75% after 500 cycles at 0.5C, far exceeding 42% for of the baseline.