Se-doped CoP nanoparticles confined in 3D porous carbon frameworks with enlarged interlayer spacings boost potassium-ion storage

Abstract Se-doped CoP nanoparticles with the size of 10–50 nm that are uniformly confined in 3D porous carbon frameworks (Se-CoP/C) and are fabricated via a facile pyrolysis and phosphorization/selenization approach. When employed as K-ion battery anodes, the as-produced Se-CoP/C composite shows outstanding rate capability and long cycle life. Heteroatom Se-doping on CoP effectively modifies the lattice of CoP with expanded d-spacings for accelerating K-ion insertion/extraction. Se-doping also provides increased active sites and improved lattice stability of CoP towards high specific capacities and their retention over long-term cycling. The 3D porous carbon frameworks offer sufficient pathways for fast electron and K-ion transport and diffusion whilst accommodate the volume changes and prevent the agglomeration of the anchored Se-CoP nanoparticles. Benefiting from the synergistic effects of the unique nanostructure and atomic-level Se-doping, a high specific capacity of 111.1 mA h g−1 can be maintained at 2000 mA g−1 after 1200 cycles. An exceptional high-rate capability of 115.3 mAh g−1 at 3000 mA g−1 was also achieved. This study provides new opportunities for the development of heteroatom-doped CoP-based anode materials for future K-ion batteries.