Anchoring intermediate phases via few-layer MoSSe nanosheets in flexible porous carbon fiber for stable lithium ion storage

Abstract

Transition metal chalcogenides (TMCs) have been widely studied as anode materials for lithium-ion batteries (LIBs) due to their high specific capacity properties. However, the dissolution and agglomeration of the unstable reaction intermediate lithium polysulfide inevitably leads to a significant loss of the active ingredient and a reduction in the reversibility of the reaction, resulting in a shortened lifetime. Herein, we successful constructed few-layered ultrathin MoSSe nanosheets embedded in flexible porous carbon nanofibers (MoSSe/CNFs).Firstly, MoSSe/CNFs not only confers superior flexibility and integrity to the carbon fibers through a network of large pores but also enhances the fast electron transport capability. Secondly, the optimized Se-doped MoS3 inside the CNFs structure is formed after the first discharge/charge cycles, can prevent detrimental interfacial side reactions, decrease the Li+ diffusion barriers, increase electronic conductivity, and limit the dissolution of polysulfides or polyselenides in the electrolyte. Finally, the N-doped flexible porous carbon nanofiber accommodates the volume expansion, prevents the aggregation issues of MoS3 and irreversible decomposition of Li2S or Li2Se into the electrolyte ,which can benefit greatly in reaction kinetics and structural stability for improved lithium storage performance. As a result of these improvements, the self-standing MoSSe/CNFs electrodes show a stable capacity of 738 mAh g-1 at 0.5 A g-1 and 578 mAh g-1 at 5 A g-1 with the capacity retention of almost 100% over 950 cycles.