Two-dimensional layered transition metal disulphides for effective encapsulation of high-capacity lithium sulphide cathodes

Abstract

Fully lithiated lithium sulphide (Li₂S) is currently being explored as a promising cathode material for emerging energy storage applications. Like their sulphur counterparts, Li₂S cathodes require effective encapsulation to reduce the dissolution of intermediate lithium polysulphide (Li₂S_n, n=4–8) species into the electrolyte. Here we report, the encapsulation of Li₂S cathodes using two-dimensional layered transition metal disulphides that possess a combination of high conductivity and strong binding with Li₂S/Li₂S_n species. In particular, using titanium disulphide as an encapsulation material, we demonstrate a high specific capacity of 503mAhg-1Li2S under high C-rate conditions (4C) as well as high areal capacity of 3.0 mAh cm⁻² under high mass-loading conditions (5.3mgLi2Scm-2). This work opens up the new prospect of using transition metal disulphides instead of conventional carbon-based materials for effective encapsulation of high-capacity electrode materials.