Optimally arranged TiO2@MoS2 heterostructures with effectively induced built-in electric field for high-performance lithium-sulfur batteries

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To overcome the serious technological issues affecting lithium-sulfur (Li-S) batteries, such as sluggish sulfur redox kinetics and the detrimental shuttle effect, heterostructure engineering has been investigated as a strategy to effectively capture soluble lithium polysulfide intermediates and promote their conversion reaction by integrating highly polar metal oxides with catalytically active metals sulfides. However, to fully exploit the outstanding properties of heterostructure-based composites, their detailed structure and interfacial contacts should be designed rationally. Herein, optimally arranged TiO2 and MoS2-based heterostructures (TiO2@MoS2) are fabricated on carbon cloth as a multifunctional interlayer to efficiently trap polysulfide intermediates and accelerate their redox kinetics. Owing to the synergistic effects between TiO2 and MoS2 and the uniform heterointerface distribution that induces the ideally oriented built-in electric field, Li-S batteries with TiO2@MoS2 interlayers exhibit high rate capability (601 mA h g−1 at 5 C), good cycling stability (capacity-fade rate of 0.067% per cycle over 500 cycles at 2 C), and satisfactory areal capacity (5.2 mA h cm−2) under an increased sulfur loading of 5.2 mg cm−2. Moreover, by comparing with a MoS2@TiO2 interlayer composed of reversely arranged heterostructures, the effect of the built-in electric field’s direction on the electrocatalytic reactions of polysulfide intermediates is thoroughly investigated for the first time. The superior electrocatalytic activities of the rationally arranged TiO2@MoS2 interlayer demonstrate the importance of optimizing the built-in electric field of heterostructures for producing high-performance Li-S batteries.