SnS2 nanoparticles embedded in sulfurized polyacrylonitrile composite fibers for high-performance potassium-ion batteries

Potassium-ion batteries (PIBs) have garnered significant attention as a promising alternative to commercial lithium-ion batteries (LIBs) due to abundant and cost-efficient potassium reserves. However, the large size of potassium ions and the resulting sluggish reaction kinetics present major obstacles to the widespread use of PIBs. Herein, we present a simple method to ingeniously encapsulate SnS₂ nanoparticles within sulfurized polyacrylonitrile (SPAN) fibers (SnS₂@SPAN) for serving as a high-performance PIB anode. The large interlayer spacing of SnS₂ provides a fast transport channel for potassium ions during charge–discharge cycles, while the one-dimensional SPAN skeleton offers massive binding sites and shortens the diffusion path for potassium ions, facilitating faster reaction kinetics. Additionally, the excellent ductility of SPAN can effectively accommodate the large volume changes that occur in SnS₂ upon potassium-ion insertion, thereby enhancing the cyclic stability of SnS₂. Benefiting from the above advantages, the SnS₂@SPAN composites exhibit impressive cyclability over 500 cycles at 4 A g⁻¹, with a capacity retention rate close to 100%. This study provides an effective approach for stabilizing high-capacity PIB anode materials with large volume variations.