TiO2-Driven graphite exfoliation: a facile approach for designing a high-performance BiSb3/TiO2@multilayer graphene anode for potassium-ion batteries

Abstract

As an alloying-type anode material for potassium-ion batteries (PIBs), antimony (Sb) has garnered considerable research interest owing to its high reversible capacity and suitable potassium insertion voltages. Nevertheless, the significant volume expansion change during potassiation/depotassiation processes leads to severe structural degradation, hindering its practical application. In this work, by combining nanostructure-designing, graphene compositing, and alloying strategies, a Sb-based material is synthesized via a facile ball-milling technique, where graphite is mechanically exfoliated in situ by TiO₂ to obtain multilayer graphene, and then, BiSb₃ alloy is wrapped by the graphene to construct BiSb₃/TiO₂@multilayer graphene (BST@MLG) nanosheets. The nanosheet structure enhances the permeation of the electrolyte, increases active sites, and effectively alleviates volume stress during the charge/discharge process. In addition, the graphene network establishes a fast ion-transport channel, significantly improving the kinetic properties. Thus, the material shows an outstanding performance; BST@MLG delivers a reversible capacity of 388.7 mAh g⁻¹ at 1.0 A g⁻¹ with a capacity retention of 88.5% after 850 cycles. Even at 10 A g⁻¹, it still maintains a charge capacity of 162.5 mAh g⁻¹. This method provides an effective strategy for developing high-performance potassium-ion battery electrode materials.