Stabilizing Intermediate Phases via Efficient Entrapment Effects of Layered VS4/SnS@C Heterostructure for Ultralong Lifespan Potassium-Ion Batteries

Potassium-ion batteries (PIBs) have appealed increasing attention due to the inexpensive K-element resources and satisfactory electrochemical properties. Presently, there are still challenges for developing desirable anode materials. Two-dimensional metal sulfides exhibit high specific capacity as host for PIBs, yet the dissolution and agglomeration of unstable reaction intermediate K x S y (K 2 S, K 2 S 5 ) inescapability induces large loss of active ingredients and poor reactions reversibility, leading to inferior lifespan. Herein, polar polysulfide VS 4 is introduced into SnS nanosheets with constructing layered VS 4 /SnS heterostructure anchored in graphene scaffold (VS 4 /SnS@C). In this framework, VS 4 with unsaturated bridging (S 2 ) 2– can act as the anchoring sites to stabilize intermediates K x S y with efficient entrapment effects. Moreover, the heterostructure can maintain layered SnS and regulate the distribution of K x S y with high conversion reversibility. The reaction reversibility and intermediate absorptivity are enhanced, as confirmed by in situ X-ray diffraction analysis and theoretical calculations. Consequently, the VS 4 /SnS@C electrode exhibits ultra-long lifespans, which achieves a capacity of 168.4 mAh g –1 at 1 A g –1 after 6000 cycles. This strategy of heterostructure design facilitates the understanding of K-storage mechanisms and significantly enhances the reaction reversibility, providing a thought to address the challenges in metal sulfide anodes toward the development of high-performance PIBs.