High-performance Li6PS5Cl-based all-solid-state lithium-ion batteries

Abstract

All-solid-state lithium-ion batteries (ASSLIBs) owing to their advantage of enhanced safety are considered to be a promising candidate for next-generation energy storage devices. However, the poor cycling performance and low areal capacities of ASSLIBs with S, Li₂S or traditional oxide cathodes hinder the development of high-energy-density ASSLIBs. Herein, a Li₆PS₅Cl solid-state electrolyte has been systematically investigated for use as a cathode active material in ASSLIBs for the first time. ASSLIBs employing Li₆PS₅Cl as both the active material and electrolyte with a Li–In alloy anode are fabricated. A Li₆PS₅Cl-based cell with an active material loading of 3.1 mg cm⁻² exhibits a high discharge capacity of around 535 mA h g⁻¹ after 650 cycles at 56 mA g⁻¹ (∼0.1C) at room temperature, which is the highest value among ASSLIBs using sulfide SSEs as active materials and is even comparable with those of cells with S, Li₂S or transition metal sulfides as the active material. This superior long-term cycling performance is attributed to the highly reversible electrochemical activity of Li₆PS₅Cl revealed by ex situ XRD and XPS analyses.