A Multifunctional Silicon-Doped Polyether Network for Double Stable Interfaces in Quasi-Solid-State Lithium Metal Batteries

Abstract

Polymer-based quasi-solid-state electrolyte (QSE) is an effective means to solve the safety problem of lithium (Li) metal batteries, and stable solid-electrolyte-interface (SEI) layers between electrolyte and anode/cathode are highly required for their long-term stability. Herein, it is demonstrated that a silicon-doped polyether functions as a multifunctional unit, which can induce the formation of stable and robust SEI layers with rich Li_xSiO_y on both the surfaces of cathode and anode. It simultaneously solves the compatibility of electrolyte and electrodes in the quasi-solid-state Li-metal battery. Moreover, the robust polymer skeleton with a cross-linked network is beneficial to inhibit liquid volatilization and improve battery safety. The assembled Li|QSE|LiFePO₄ batteries show a capacity retention rate as high as 97.5% after 400 cycles at 1 C (30 °C), and reach 78.1% after 1000 cycles. Furthermore, there is almost no attenuation of reversible capacity after 100 cycles for the assembled Li|QSE|LiNi_0.8Mn_0.1Co_0.1O₂ batteries. The concept of silicon-doped polymer with a crosslinking structure provides an important strategy for designing solid-state or quasi-solid-state polymer electrolytes for the stable long-term operation of both anode and cathode.