Phase regulation enabling dense polymer-based composite electrolytes for solid-state lithium metal batteries.

Wu, Qian; Fang, Mandi; Jiao, Shizhe; Li, Siyuan; Zhang, Shichao; Shen, Zeyu; Mao, Shulan; Mao, Jiale et al. · Nat Commun · 2023

basic_science · Level V

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Abstract

Solid polymer electrolytes with large-scale processability and interfacial compatibility are promising candidates for solid-state lithium metal batteries. Among various systems, poly(vinylidene fluoride)-based polymer electrolytes with residual solvent are appealing for room-temperature battery operations. However, their porous structure and limited ionic conductivity hinder practical application. Herein, we propose a phase regulation strategy to disrupt the symmetry of poly(vinylidene fluoride) chains and obtain the dense composite electrolyte through the incorporation of MoSe<sub>2</sub> sheets. The electrolyte with high dielectric constant can optimize the solvation structures to achieve high ionic conductivity and low activation energy. The in-situ reactions between MoSe<sub>2</sub> and Li metal generate Li<sub>2</sub>Se fast conductor in solid electrolyte interphase, which improves the Coulombic efficiency and interfacial kinetics. The solid-state Li||Li cells achieve robust cycling at 1 mA cm<sup>-2</sup>, and the Li||LiNi<sub>0.8</sub>Co<sub>0.1</sub>Mn<sub>0.1</sub>O<sub>2</sub> full cells show practical performance at high rate (3C), high loading (2.6 mAh cm<sup>-2</sup>) and in pouch cell.