π-d conjugation regulates the cathode/electrolyte interface in all-solid-state lithium-ion batteries

Abstract

All-solid-state lithium-ion batteries have great scope in the development of advanced secondary batteries owing to their high energy density and nonflammability. However, high contact resistance at the solid/solid (electrode/electrolyte) interface and the possible existence of side reactions limit their large-scale applications. In this study, a π-d conjugated coordination structure was established between a cathode and electrolyte: 2,5-dihydroxy-1,4-benzoquinone (DHBQ) was the cathode and polyvinylidene fluoride-based Li_0.33La_0.557TiO₃ (PVDF-LLTO) polymer was the solid-state electrolyte. First-principle calculations and performed experiments showed that CO and O–H groups in DHBQ can be coordinated with La³⁺ in LLTO, and this π-d conjugate coordination structure strengthens the contact interface between the electrode material and solid electrolyte, which further increases the cycling life and durability of all-solid-state batteries.