Embedding Antimony Nanoparticles into a Nitrogen-Doped Porous Carbon Matrix for High-Performance Potassium-Ion Battery Anode

Antimony (Sb) has the advantages of high theoretical K⁺ storage capacity, low alloying potential, and excellent electrical conductivity, and it is a promising active anode material for potassium-ion batteries (PIBs). In this work, a series of Sb/NC nanocomposites were prepared by the sol–gel method and carbothermic reduction technique, encapsulating Sb particles in a nitrogen (N)-doped three-dimensional porous carbon matrix. The results show that Sb/NC nanocomposites with a unique porous structure and optimal Sb content can be obtained by simply adjusting the amount of organic carbon source during the synthesis process. When used as anodes for PIBs, they exhibit high capacity, good cycling stability, and excellent rate performance (at a current density of 100 mA/g, the initial reversible discharge specific capacity reached 476.9 mAh/g; it remained at 418.0 mAh/g after 50 cycles, corresponding to a capacity retention of approximately 87.6%. At a higher current density of 500 mA/g, the discharge capacity was 310.1 mAh/g). This can be attributed to the porous carbon matrix and uniformly dispersed Sb nanoparticles in Sb/NC, which together alleviate the stress during the K⁺ alloying process, enhancing its cycling stability. In addition, the N-doped carbon matrix not only enhances the diffusion rate of K⁺ but also significantly increases the contact area between active electrode material and electrolyte, thereby improving the K⁺ storage performance of Sb/NC at high current densities.