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 for potassium-ion batteries (KIBs). However, the cycling stability of TMS is unsatisfactory owing to the large K ion intercalation/deintercalation. Herein, 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 mAh g-1 is acquired. When the current density increases to 500mA g-1, the CoSe2@NC can still maintain a capacity of 184.5 mAh g-1 after 1000 cycles. The high performance, easy compositing and low cost of the CoSe2@NC makes it a favorable material for KIBs application.