CoSe2/N-doped carbon porous nanoframe as an anode material for potassium-ion storage

Transition metal selenides (TMS), on account of their relatively high theoretical capacity, unique electrical properties, easy compositing and low cost, are considered to be a candidate anode material for potassium-ion batteries. However, the cycling stability of TMS is unsatisfactory owing to the large intercalation/deintercalation of K ions. Herein, a CoSe2/N-doped carbon porous frame (CoSe2@NC) is successfully synthesized through a simple mixing and sintering approach and displays excellent potassium storage performance. Plentiful C–N bonds in the precursor can induce the formation of homogeneous N-doped carbon matrix and C–N–Co bonds, thus endowing robust structure and high electronic conductivity for superior cycling stability. Therefore, the unique porous nanoframe suppresses volume expansion and provides more diffusion paths for K ions. After 1000 cycles at 50 mA g−1, a high capacity of 311.3 mA h g−1 is acquired. When the current density increases to 500 mA g−1, the CoSe2@NC can still maintain a capacity of 184.5 mA h g−1 after 1000 cycles. The high performance, easy compositing and low cost of the CoSe2@NC make it a favorable material for application in KIBs.