Integrated 3D Porous Copper@BiSb Alloy Anodes via Pulse Electrodeposition for High-Performance Potassium-Ion Storage.

Abstract

Antimony (Sb) and bismuth (Bi) are promising alloy-type anode materials for potassium-ion batteries (PIBs), yet Sb suffers from a massive 390% volume expansion during potassiation, while Bi is limited by a relatively low specific capacity of 384 mAh·g-1. Moreover, existing synthesis methods for BiSb alloys are complex, costly, and require binders or conductive additives that impair electrochemical performance. Herein, we innovatively fabricate an integrated 3D porous copper@BiSb (3DPC@BiSb) electrode by pulse electrodepositing BiSb alloy onto a 3D porous copper (3DPC) substrate. The 3DPC scaffold provides abundant active sites, shortens ion diffusion pathways, and mitigates volume expansion, while the binder-free design eliminates interfacial issues. Electrochemical tests demonstrate that the 3DPC@BiSb electrode delivers a reversible capacity of 400.6 mAh·g-1 at 0.1 A·g-1 after 100 cycles and retains 205.0 mAh·g-1 even at 32 C, outperforming most reported alloy-type anodes for PIBs. Kinetic analysis, ex-situ X-ray diffraction, and density functional theory (DFT) calculations reveal that the superior performance originates from the synergistic effect of Sb (high capacity) and Bi (structural stability), enhanced K+ adsorption energy, and reduced diffusion barrier. This work provides a scalable strategy for fabricating integrated alloy anodes capable of large-area electrode preparation. It offers insights into the structure-performance relationship of BiSb-based materials, advancing the development of high-performance thin-film PIBs for renewable energy storage.

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