From nanomelting to nanobeads: nanostructured SbxBi1−x alloys anchored in three-dimensional carbon frameworks as a high-performance anode for potassium-ion batteries

Abstract

Potassium-ion batteries (KIBs) are considered a favorable candidate for large-scale electric energy storage system applications owing to the abundance and low-cost of potassium resources. Herein, a series of three-dimensional pomegranate-like Sb_xBi_1−x@C composites are fabricated by a modified Pechini sol–gel method. As an anode for KIBs, the Sb_0.5Bi_0.5@C composite exhibits the optimal performance (382 mA h g⁻¹ at 0.05 A g⁻¹). More importantly, the synergistic effects in the binary alloy bring a promising long-term cycle life (83% capacity retention after 400 cycles) for Sb_0.5Bi_0.5@C. The ex situ X-ray diffraction results reveal the K storage mechanism of this material, which is Sb_0.5Bi_0.5 ↔ KSb_0.5Bi_0.5 ↔ K₃Sb_0.5Bi_0.5 during discharge and charge processes. In addition, a full cell constructed by coupling Sb_0.5Bi_0.5@C with a Prussian blue cathode delivers outstanding electrochemical performance.