Flower-like heterostructured MoP–MoS2 hierarchical nanoreactor enabling effective anchoring for LiPS and enhanced kinetics for high performance Li–S batteries

Abstract

Lithium-sulfur batteries have been considered as one of the most promising energy storage candidates due to their high energy density and low cost. However, the low electrical conductivity of elemental sulfur, notorious LiPS shuttle and sluggish redox kinetics bring about fast capacity fade and poor rate capabilities. To solve these problems, herein a modification strategy of functional separator is introduced by coating heterostructured MoP–MoS2 and porous carbon nanofibers (PCNFs) on the surface of a Celgard separator. Moreover, for the first time, we detailly discuss the effect of the ratio of component (MoP:MoS2) in the heterostructured MoP–MoS2 materials on the electrochemical performance. The coating layer exhibits both satisfactory interception ability for LiPS shuttle and fast LiPS conversion ability due to abundant anchoring sites of MoP–MoS2 heterojunction nanoflowers and shortened lithium ion channel of the prepared PCNFs. Benefiting from these advantages, the assembled Li–S battery with a MoP-50/PCNFs separator exhibits 1090.02 mAh g-1, and high discharge capacity of 884.67 mAh g-1 even after 300 cycles at 1 C. The initial discharge capacity of MoP-50/PCNFs separator at 2 C and 5 C are about 1050.4 and 728.22 mAh g-1, and retains about 698.4 mAh g-1 after 400 cycles and 431.28 mAh g-1 after 500 cycles. The novel work will provide a new strategy by which the modified separator with transition metal phosphides can be applied in the design of high-performance Li–S batteries and shows great potential for practical application.