Cathode-electrolyte integrating strategy enabling solid-state lithium metal battery with enhanced cycle stability

Abstract

Solid-state lithium metal batteries as promising energy storage devices have gathered many attentions for its appealing properties, such as improved safety and capacity density. Nevertheless, high interfacial resistance, uneven current density and severe Li dendrite growth caused by rigid contact at the cathode-electrolyte interface in solid-state batteries greatly restrict its electrochemical performance and further practical application. Herein, a cathode-electrolyte integrating strategy is proposed to achieve the soft interfacial contact through employing poly(vinylidene fluoride)-based composite electrolyte as the cathode binder and subsequent heat-pressing procedure. Due to the modification strategy, fabricated cells with integrated structure show lower resistance, faster Li-ion transport, enhanced capacity and improved cycle stability. The integrated LiFePO₄/Li cell exhibits superior electrochemical performance, which present a capacity retention of 93.8% and 91.6% after 300 cycles at 0.5 C and 400 cycles at 1 C, respectively, being able to compare favorably with the conventional cells using liquid electrolyte. Overall, the study provides a solution for designing advanced solid-state lithium metal batteries.