Intercalation-conversion hybrid cathodes enabling Li–S full-cell architectures with jointly superior gravimetric and volumetric energy densities

Abstract

A common practise in the research of Li–S batteries is to use high electrode porosity and excessive electrolytes to boost sulfur-specific capacity. Here we propose a class of dense intercalation-conversion hybrid cathodes by combining intercalation-type Mo6S8 with conversion-type sulfur to realize a Li–S full cell. The mechanically hard Mo6S8 with fast Li-ion transport ability, high electronic conductivity, active capacity contribution and high affinity for lithium polysulfides is shown to be an ideal backbone to immobilize the sulfur species and unlock their high gravimetric capacity. Cycling stability and rate capability are reported under realistic conditions of low carbon content (~10 wt%), low electrolyte/active material ratio (~1.2 µl mg−1), low cathode porosity (~55 vol%) and high mass loading (>10 mg cm−2). A pouch cell assembled based on the hybrid cathode and a 2× excess Li metal anode is able to simultaneously deliver a gravimetric energy density of 366 Wh kg−1 and a volumetric energy density of 581 Wh l−1. Despite tremendous progress in the development of LiS batteries, their performance at the full-cell level is not as competitive as state-of-the-art Li-ion batteries. Here the authors report a full-cell architecture making use of a hybrid intercalation-conversion cathode, enabling both high volumetric and gravimetric energy densities.