Furnishing Continuous Efficient Bidirectional Polysulfide Conversion for Long-Life and High-Loading Lithium-Sulfur Batteries via the Built-In Electric Field.

Abstract

Most catalysts cannot accelerate uninterrupted conversion of polysulfides, resulting in poor long-cycle and high-loading performance of lithium-sulfur (Li-S) batteries. Herein, rich p-n junction CoS2 /ZnS heterostructures embedded on N-doped carbon nanosheets are fabricated by ion-etching and vulcanization as a continuous and efficient bidirectional catalyst. The p-n junction built-in electric field in the CoS2 /ZnS heterostructure not only accelerates the transformation of lithium polysulfides (LiPSs), but also promotes the diffusion and decomposition for Li2 S the from CoS2 to ZnS avoiding the aggregation of lithium sulfide (Li2 S). Meanwhile, the heterostructure possesses a strong chemisorption ability to anchor LiPSs and superior affinity to induce homogeneous Li deposition. The assembled cell with a CoS2 /ZnS@PP separator delivers a cycling stability with a capacity decay of 0.058% per cycle at 1.0 C after 1000 cycles, and a decent areal capacity of 8.97 mA h cm-2 at an ultrahigh sulfur mass loading of 6 mg cm-2 . This work reveals that the catalyst continuously and efficiently converts polysulfides via abundant built-in electric fields to promote Li-S chemistry.