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).