Double Transition-Metal Chalcogenide as a High-Performance Lithium-Ion Battery Anode Material

Abstract

Transition-metal dichalcogenides (TMDs) are a recent addition to a growing list of anode materials for the next-generation lithium-ion battery (LIB). The actual performance of TMDs is however constrained by their limited electronic conductivity. For example, MoS2, the most studied TMD, does not have adequate rate performance even in the few-layer form or after compounding with nitrogen-doped graphene (NG). WS2, a TMD with a higher intrinsic electronic conductivity, is more suitable for high rate applications but its theoretical capacity is lower than that of MoS2. Hence, we hypothesize that a composition-optimized composite of MoS2, WS2, and NG may provide high capacity concurrently with good rate performance. This is a report on the design and preparation of double transition-metal chalcogenide (MoS2/WS2)-nitrogen doped graphene composites where the complementarity of component functions may be maximized. For example the best sample in this study could deliver a high discharge capacity of 1195 mAh·g–1 at 100 mA·g–1 concurrently with good cycle stability (average of 0.02% capacity fade per cycle for 100 cycles) and high rate performance (only 23% capacity reduction with a 50 fold increase in current density from 100 mA·g–1 to 5000 mA·g–1).