The (110) plane dominated FeSe₂ particle microspheres@N-doped carbon interweaved network structure for enhanced potassium storage

Transition metal dichalcogenides (TMDs) have the potential to be a high-capacity anode material for potassium ion batteries (PIBs) due to their multielectron transfer, while their rapid capacity decay hinders the commercial application due to large-sized K⁺. Herein, we design a new strategy to synthesize the (110) plane dominated FeSe₂ particle microspheres coated by N-doped carbon (FeSe₂@C). The (110) plane dominated FeSe₂ can better facilitate the storage of the large-sized K⁺, and the surface carbon can inhibit the overgrowth of solid electrolyte interphase (SEI) during cycling. In addition, the porous structure provides abundant channels for K⁺ diffusion, benefiting the rate performance. More importantly, the FeSe₂ microparticles would break down into smaller nanoparticles and mix with carbon layer to form interweaved network after cycling, which could expose more active sites for K⁺ redox and enhance the structure stability, thus improving the specific capacity and cycling stability. As an anode material, this unique structure delivers a high capacity (363.2 mA h g⁻¹ at 0.2 A g⁻¹ over 200 cycles) and remarkable rate capability (285.2 mAh g⁻¹ at 20 A g⁻¹) in PIBs. Impressively, the FeSe₂@C anode achieves a remarkable long-term cyclability (0.013 % capacity decay per cycle over 1000 cycles at 2 A g⁻¹).