Polyethylene oxide (PEO)-based electrolytes are crucial for the safety and energy density of solid-state batteries but suffer from poor oxidation resistance at high voltages. This study introduces a Lewis-acid coordinated strategy using Mg²⁺ and Al³⁺ to improve the cyclic stability of 4.8 V-class PEO-based batteries. The strong electron-withdrawing ability of the added ions weakens the electron density of ether oxygen (EO) chains, limiting the interaction between EO chains and cathodes at high state of charge. Batteries using this electrolyte and Ni-rich cathodes achieve 4.8 V stability over 300 cycles. Industrial-scale electrolyte membranes and Ah-level pouch cells exceeding 586 Wh kg⁻¹ with good cyclic stability demonstrate the practical potential of this strategy.

Hanwen An, Menglu Li, Qingsong Liu, Yajie Song, Jiaxuan Liu, Zhihang Yu, Xingjiang Liu, Biao Deng, Jiajun Wang