Interface engineering of MoS2/CoS2 heterojunction encapsulated in carbon matrix as high-energy durable anode for lithium-ion batteries

Graphite anodes are limited by low capacity and instability. Conversion-type transition metal sulfides (TMSs) offer high energy density, yet single-component TMSs suffer from rapid capacity decay thanks to volume changes, hindering practical implementation. This study explored a high-specific energy anode material MoS 2 /CoS 2 @C. The composite was based on two-dimensional layered 2H-MoS 2 nanosheets, featuring uniformly distributed CoS 2 nanoparticles on the surface. Finally, the carbon material was encapsulated onto the sulfide surface. A heterojunction is formed at the interface between CoS 2 and MoS 2 , which modulated the surface electronic structure, inhibited aggregation, and facilitated the formation of high-quality TMSs nanocrystals. Additionally, the carbon serves as a confining layer for the TMSs, enabling enhanced cycling stability. The material exhibits a remarkable specific capacity exceeding 730 mAh·g −1 after 380 cycles at a rate of 0.5C in coin-type half-cells. Furthermore, when utilized in pouch cells with a lithium metal anode, it retains a capacity of 436.5 mAh·g −1 following 100 cycles. Theoretical calculations reveal optimized electronic arrangement at the heterojunction interface, where the constructed built-in electric field facilitates lithium-ion transport. The lithium-ion migration energy barrier is reduced from 0.78 eV to 0.34 eV, thereby significantly accelerating reaction kinetics. Furthermore, the lithium metal pouch cells demonstrate no thermal runaway behavior even after undergoing abuse tests such as extrusion, overcharging, and short-circuiting. These results highlight the potential of MoS 2 /CoS 2 @C as a promising anode material for advanced lithium-ion battery systems, offering excellent energy storage capacity, prolonged cycling stability, and improved operational safety.