Cross‐Phase Impurity–Interphase Regulation for Suppressing Thermally Accelerated Failure in Ni‐Rich Pouch Lithium‐Ion Batteries

ABSTRACT Practical LiNi 0.8 Co 0.1 Mn 0.1 O 2 ||graphite pouch cells suffer rapid degradation under thermal stress because liquid‐phase impurity reactions, electrode interphase failure, and cathode–anode cross‐talk are tightly coupled. However, most strategies are designed to address either impurity chemistry or interphase chemistry, leaving the amplified cross‐talk between electrolyte degradation and electrode failure unresolved. Here, we propose a cross‐phase impurity–interphase regulation strategy using p‐Phenylenebis(dimethylvinylsilane) (PDVS) for LiNi 0.8 Co 0.1 Mn 0.1 O 2 ||graphite pouch cells. The vinyl‐dimethylsilyl groups endow PDVS with synchronized liquid‐phase scavenging and solid‐phase interphase‐forming capability. In the liquid phase, PDVS acts as an impurity scavenger, lowering HF from 90.88 ppm to 29.44 ppm while reducing residual H 2 O from 10.65 to 8.45 ppm, thereby suppressing LiPF 6 hydrolysis and reducing the accumulation of corrosive by‐products. At the solid interfaces, PDVS preferentially participates in interfacial reactions to construct Si‐containing cathode‐electrolyte interphase and solid‐electrolyte interphase on the Ni‐rich cathode and graphite anode, mitigating electrolyte decomposition, gas evolution, transition‐metal crossover, and resistance growth. Consequently, 2 Ah LiNi 0.8 Co 0.1 Mn 0.1 O 2 ||graphite pouch cells retain 92.81% capacity after 304 cycles at 45°C, show reduced swelling during 60°C storage, and maintain 86.5% capacity after over 1620 cycles at 25°C. This work establishes cross‐phase impurity–interphase regulation as a manufacturing‐compatible electrolyte design principle for thermally durable Ni‐rich pouch cells.