Achieving Stable and Ultrafast Potassium Storage of Antimony Anode via Dual Confinement of MXene@Carbon Framework

Antimony-based anode materials are recognized for their high potassium storage capacities and appropriate operating potentials. However, the large volume expansion of Sb during the potassiation/depotassiation process, which results in a quick capacity decay, severely limits its practical application in potassium-ion batteries (PIBs). Here, a carbon-coated Sb/MXene heterostructure composite (CSM) is synthesized by adsorption of Sb³⁺ on MXene nanosheets via Sb-O-Ti bonds followed by carbothermic reduction to construct dual-confined MXene@carbon conductive framework capable of withstanding high volume expansion of Sb and conducive to enabling accelerated electron transfer kinetics. The CSM composite, particularly CSM-700, when configured as an anode for PIBs, realized high capacity (484.4 mAh g^-1 at 0.1 A g^-1 ), an ultra-stable cycling performance with a high reversible capacity of 435.9 mAh g^-1 at 0.1 A g^-1 after 100 cycles corresponding to a capacity retention rate of 90.0%, and superior rate performance of 323.0 mAh g^-1 at 1 A g^-1 . The proposed strategy offers a simple route to construct high-performance Sb-based anodes for advanced PIBs.