Developing Superior Potassium Ion Storage Performance through Regulating the Bi/Sb Ratio in Three-Dimensional Porous Bi_<i>x</i>Sb_<i>y</i>@C Anode Material

Sb-based alloy anode materials have garnered a great deal of attention in potassium ion batteries (PIBs) due to their high capacity and suitable working potential. Nevertheless, they still undergo significant volume expansion during the potassiation/depotassiation process, which leads to a poor performance in PIBs. Herein, three-dimensional (3D) porous BixSby@C is synthesized by using a mass-producible and facile conventional solid-state reaction method. Owing to the reasonable design of the carbon matrix structure and synergistic effects brought about by the introduction of bismuth, the composites achieve an outstanding electrochemical performance as a PIB anode material. BiSb3@C composite exhibits a high capacity of 382 mAh g–1 at 0.5 A g–1 after 800 cycles. Furthermore, it also displays an excellent rate capability, delivering 172 mAh g–1 at 20 A g–1. The potential practical application of BiSb3@C is also evaluated via assembling full PIBs using Prussian Blue as a counter electrode, which demonstrates a pretty good electrochemical performance. In addition, the potassiation/depotassiation reaction mechanism is systematically studied by using ex situ X-ray diffraction (XRD) technology.