Developing\nSuperior Potassium Ion Storage Performance\nthrough Regulating the Bi/Sb Ratio in Three-Dimensional Porous Bi<sub><i>x</i></sub>Sb<sub><i>y</i></sub>@C Anode Material

Sb-based\nalloy anode materials have garnered a great deal of attention\nin potassium ion batteries (PIBs) due to their high capacity and suitable\nworking potential. Nevertheless, they still undergo significant volume\nexpansion during the potassiation/depotassiation process, which leads\nto a poor performance in PIBs. Herein, three-dimensional (3D) porous\nBi<sub><i>x</i></sub>Sb<sub><i>y</i></sub>@C is\nsynthesized by using a mass-producible and facile conventional solid-state\nreaction method. Owing to the reasonable design of the carbon matrix\nstructure and synergistic effects brought about by the introduction\nof bismuth, the composites achieve an outstanding electrochemical\nperformance as a PIB anode material. BiSb<sub>3</sub>@C composite\nexhibits a high capacity of 382 mAh g<sup>–1</sup> at 0.5 A\ng<sup>–1</sup> after 800 cycles. Furthermore, it also displays\nan excellent rate capability, delivering 172 mAh g<sup>–1</sup> at 20 A g<sup>–1</sup>. The potential practical application\nof BiSb<sub>3</sub>@C is also evaluated via assembling full PIBs using\nPrussian Blue as a counter electrode, which demonstrates a pretty\ngood electrochemical performance. In addition, the potassiation/depotassiation\nreaction mechanism is systematically studied by using ex situ X-ray\ndiffraction (XRD) technology.