Cationic dynamic elastomer electrolyte enabling all-solid-state lithium batteries

Abstract

Elastomeric solid polymer electrolytes (SPEs), exhibiting excellent toughness and interfacial stability with lithium (Li) metal anodes, are promising electrolytes for safe and durable all-solid-state Li-batteries. However, many elastomeric SPEs suffer from low conductivity, necessitating addition of liquid electrolytes which can compromise mechanical integrity and cause leakages. Herein, we introduce a fully solid-state elastomeric poly(triazolium) (PT-Li) SPE, which integrates the principles of poly(ionic liquid) (PIL) and covalent adaptable network (CAN) -based electrolytes to achieve enhanced performance characteristics. Like PILs, PT-Li possesses a wide electrochemical window (up to 5.2 V). Meanwhile, like CANs, dynamic triazolium crosslinking enables PT-Li to remain mechanically robust when cycling (shear loss factor ≤ 0.2 at 60 °C) while facilitating (re)processing under heat and pressure. Additionally, the cationic triazolium moieties facilitate Li⁺ -ion mobility (ionic conductivity, σ = 3.2 × 10⁻⁵ S cm⁻¹ at 30 °C, 2 × 10⁻⁴ S cm⁻¹ at 60 °C; lithium transference, T_Li⁺ = 0.74). This enabled PT-Lis to exhibit excellent cycling performances in all-solid-state Li | LiFePO₄ cells with uniform Li⁺ deposition at the Li anode interface and enhanced rate capability. The tunability and (re)processability enabled by dynamic covalent crosslinks represent a promising strategy for the development of robust all-solid-state lithium batteries.