Necklacelike biomass derived N-doped carbon fibers with encapsulated Sb enable stable potassium-ion storage

Antimony, as the anode of potassium ion batteries, has a satisfactory theoretical specific capacity (660 mAh g⁻¹). However, the lattice expansion after potassization and insufficient conductivity of antimony hinder the practical application of Antimony based electrodes. A novel synthesis strategy for necklacelike biomass derived carbon fibers linked with MOF encapsulated Sb nanoparticles composite electrode is reported, wherein the unique structure of metal-organic frameworks (MOFs) is utilized to achieve nanoscale confinement and the inherent adsorption properties of fungi are exploited to construct conductive networks. The unique carbon encapsulation of MOF materials effectively controls the size of antimony particles and limits the expansion after potassization. The fixation of one-dimensional carbon fiber can prevent the powdering and shedding of the active materials and improve the cycle life of the composite electrodes. Electrochemical experiments and theoretical calculations show that NCFs@Sb@C anode has good conductivity and fast potassium ion diffusion kinetics. After 400 cycles at 1 A g⁻¹, NCFs@Sb@C still has a high reversible specific capacity of 129.3 mAh g⁻¹, which is significantly better than that of NCFs and Sb@C. In addition, the full cell of NCFs@Sb@C anode matched with PTCDA cathode exhibits good cycling stability, demonstrating the practical application potential of this composite electrode.