Electroconductive Composite Cathode Material Composed of Lithium Fluoride and Lithium-Doped Nickel Oxide with High Utilization for All-Solid-State Batteries

Abstract

The improvement of capacity of cathodic active materials in all-solid-state lithium-ion batteries (ASS-LIBs) is a critical challenge for meeting future electronic power demands. In this study, a composite active material consisting of lithium fluoride (LiF) and nickel oxide (NiO) predoped with lithium ion (Li⁺) at various doping levels (Li(x)NiO), denoted as LiF-Li(x)NiO, was synthesized and applied to ASS-LIBs. Notably, predoping of Li⁺ into NiO enhanced the electronic conductivity throughout the cathode because of the appearance of energy levels at the bandgap region in an original NiO band structure, which improved the utilization efficiency of Li⁺ in LiF-Li(x)NiO. The maximum discharge capacity of 152 mAh g^–1 was achieved when LiF-Li(x)NiO predoped with 20 mol% Li⁺ was employed. We demonstrate that the rational enhancement of electronic conductivity in active materials is a promising strategy for the development of better ASS-LIBs.