A monolayer self-assembled bridging design enabling cycling stability of quasi-solid-state lithium metal batteries

Abstract

Quasi-solid-state or solid-state lithium-metal batteries have emerged as a promising candidate for next-generation energy storage systems, due to their remarkable potential to achieve ultrahigh energy densities and superior safety. However, achieving effective interfacial contact between solid-state electrolytes and electrodes remains a critical challenge, restricting their electrochemical performance. Herein, a dual-reactive siloxane agent is introduced into an in-situ polymerized polymer electrolyte as a bridging promoter, enabling ultra-conformal interfacial contact with rapid ion transport kinetics at Li metal anode. This strategy transforms the inactive LiOH layer on the lithium metal surface into Li–O–Si bonds, achieving both in-situ grafting and self-assembly. Subsequently, the secondary reactive site undergoes ring-opening copolymerization with the precursor electrolyte. Thus, this strategy facilitates a seamless interfacial connection between the electrolyte and lithium metal anode, optimizing ionic conductivity and significantly enhancing the air stability of Li metal anodes. The resulting Li@Si//LiFePO₄ full battery displays remarkable cycling stability, with negligible capacity loss over 600 cycles. This straightforward and practical interfacial modification strategy presents an innovative solution to overcome the interfacial challenges in solid-state lithium-metal batteries.