WS2-MoS2-biocarbon heterostructure for high-performance potassium ion storage

WS2/MoS2 heterojunctions can enhance the diffusion kinetics of potassium ions to achieve a high capacity and overcome their low electrical conductivity with the use of the biogenic carbon framework. [Display omitted] •The layered WS2/MoS2 heterostructures anchored on a biogenic carbon (BioC) framework was successfully created.•This unique WS2/MoS2 heterostructures exhibits outstanding activity and stability.•The optimized WS2/MoS2/BioC composite delivers high specific capacity and diffusion rate. Potassium ion batteries (PIBs) have attracted increasing attention due to their inexpensive elemental potassium resources and excellent theoretical electrochemical properties. Two-dimensional metal sulfides exhibit a high specific capacity as potassium ion hosts, but the high diffusion barriers for potassium ions lead to a poor reversibility of the reaction and make the theoretical capacity difficult to achieve. Here, the sulphide MoS2 was introduced into WS2 nanosheets to construct layered WS2/MoS2 heterostructures anchored on a biogenic carbon (BioC) framework. The MoS2 in the framework served as an anchoring site to stabilise the intermediate product KxSy and to increase the WS2 layer spacing. Interfacial electric fields and potassium ion migration channels with high conversion reversibility were also formed in the layered heterostructures. The results confirmed that the reversibility of the reaction and the potassium ion diffusion rate were improved. As a result, the WS2-MoS2-BioC electrode achieves high specific capacity and diffusion rate, with a reversible specific capacity of up to 517.1 mAh g−1 at 0.1 A g−1, and a three order of magnitude improvement in potassium ion diffusion performance compared to that of MoS2-BioC. This heterostructure design strategy provides ideas for the development of metal sulphide anodes for potassium ion batteries.