FeSb2 Nanoparticles Embedded in 3D Porous Carbon Framework: an Robust Anode Material for Potassium Storage with Long Activation Process

Due to their characteristics of high capacity and appropriate potassiation/depotassiation potential, Sb-based materials have become a class of promising anode materials for potassium ion batteries (PIBs). However, the huge strain induced by potassiation/depotassiation limits their ability to periodically accept/release K+. Herein, a composite with FeSb2 nanoparticles embedded in a 3D porous carbon framework (FeSb2@3DPC) is successfully constructed as an extremely stable anode material for PIBs. Benefiting from the synergistic effect of the design of nano and porous structures, the introduction of the inactive metal Fe, the firm anchoring of the FeSb2 nanoparticles by the carbon material, and the incomplete reaction of the FeSb2, the FeSb2@3DPC can achieve an ultra-long cycle life of over 4000 cycles at a current density of 500 mA g(-1). Furthermore, ex situ X-ray diffraction and transmission electron microscopy reveal a gradual activation process of FeSb2 for potassium storage. Fortunately, after activation, the electrochemical polarization of the FeSb2@3DPC anode gradually alleviates and the capacitance-controlled charge storage mode further dominates compared with the diffusion-controlled mode, all of which promote the FeSb2@3DPC to maintain the stable potassium storage capability.