Strain Redistribution in Metal-Sulfide-Composite Anode for Enhancing Volumetric Lithium Storage

Volumetric capacity, though being the most important metric for batteries, remains difficult to improve. This work demonstrates that the large volume expansion of active materials can be buffered when they are loaded on a backbone with medium volume expansion during lithium insertion, thus achieving a high volumetric specific capacity with acceptable cycling stability. Specifically, we imbedded SnS inside a MoS2@C brochosome-like matrix. The composite delivers tremendously improved volumetric specific capacity due to the synergy between the high-capacity SnS with alloy-type lithium storage mechanism and the MoS2@C brochosome-like backbone with moderate lithium storage capability and stable structure. This composite delivers highly reversible capacity and excellent capacity retention (720 mAh cm(-3) after 200 cycles at 200 mA g(-1)), and superior rate capacity of 465 mAh cm(-3) at 4 Ag-1. Such structure, involving a porous, stable and active matrix and a high-capacity filler in the pores, could be a general structural guidance for making electrode materials with high volumetric specific capacity.