# Multiscale Engineering of PEO Electrolytes for High‐Voltage and Ultrastable Solid‐State Lithium Batteries With Exceptional Room‐Temperature Performance

## TL;DR

This paper presents a new method to improve solid-state lithium batteries by enhancing ion transport and stability at room temperature.

## Contribution

A multiscale engineering strategy using PEG-PDMAEMAH+·NO3− additives to optimize PEO electrolytes for high performance.

## Key findings

- The engineered electrolyte enables stable operation at near-room temperature without liquid plasticizers.
- The 4.3 V LiNi0.8Co0.1Mn0.1O2 cell retains 82.7% capacity after 500 cycles.
- The LiFePO4 cell operates stably for 1200 cycles at 0.5 C.

## Abstract

Poly(ethylene oxide) (PEO) electrolytes show significant promise for flexible solid‐state batteries, yet face insufficient ion transport kinetics and interfacial stability. Herein, we propose a multiscale engineering that synergistically modulates both macro‐mesoscopic polymer architectures and microscopic solvation configurations by incorporating poly(ethylene oxide)‐poly(2‐dimethylaminoethyl methacrylate) nitrate (PEG‐PDMAEMAH+·NO3
−) additives. The introduced polycationic chains effectively disrupt PEO crystallinity, promote segmental motion and enhance the solubility of NO3
−. Importantly, NO3
− with high donor number can competitively coordinate with Li+, weakening the ethylene oxide‐Li+ chelation and thereby boosting bulk Li+ mobility. The resulting anion‐rich solvation structure lowers the desolvation energy barrier and fosters the formation of robust, highly conductive inorganic‐rich solid electrolyte interlayers at both the cathode and anode, which enhances the interfacial kinetics and high‐voltage tolerance. Consequently, the engineered PEO electrolyte enables lithium metal batteries to operate stably at near‐room temperature (30°C) without liquid plasticizers. Correspondingly, the 4.3 V LiNi0.8Co0.1Mn0.1O2 cell achieves stable cycling over 500 cycles at 0.2 C with a high capacity retention (82.7%), while the LiFePO4 cell maintains stable operation for 1200 cycles at 0.5 C (30°C). The proposed strategy creates an avenue to accelerate the eventual commercialization of the polymer electrolytes for solid‐state lithium batteries.

Incorporating poly(ethylene oxide)‐poly(2‐dimethylaminoethyl methacrylate) nitrate (PEG‐PDMAEMAH+·NO3
−) enhances amorphous‐phase conduction with optimized solvation in engineered PEO–PD–Li electrolytes for solid‐state lithium metal batteries.