Stabilizing Intermediate Phases via Efficient Entrapment Effects of Layered VS4/SnS@C Heterostructure for Ultralong Lifespan Potassium‐Ion Batteries. (24th June 2021) - Cao, Liang
Abstract: 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 (K2 S, K2 S5 ) inescapability induces large loss of active ingredients and poor reactions reversibility, leading to inferior lifespan. Herein, polar polysulfide VS4 is introduced into SnS nanosheets with constructing layered VS4 /SnS heterostructure anchored in graphene scaffold (VS4 /SnS@C). In this framework, VS4 with unsaturated bridging (S2 ) 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 VS4 /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. Abstract : The layered VS4 /SnS@C heterostructure is well‐designed and fabricated as an advanced anode for potassium‐ion batteries. Due to the rational incorporation of polar VS4, the efficient entrapment effects on the K x S y intermediate are thoroughly revealed by integrating in situ characterizations and theoretical analysis. The synergistic effect of VS4 /SnS@C can strengthen the heterostructural stability and boost the conversion‐alloying reaction reversibility simultaneously, ensuring superior potassium storage during ultra‐long cycling.