Topological transformation construction of a CoSe2/N-doped carbon heterojunction with a three-dimensional porous structure for high-performance sodium-ion half/full batteries†
Transition metal selenides have been widely used as anode materials for sodium-ion batteries (SIBs) because of their considerable theoretical capacity and good conductivity. Nevertheless, volume expansion is a serious problem that restricts their performance. Herein, a CoSe2/N-doped carbon heterojunction with a 3D porous structure (CoSe2@NC) is synthesized using a topological transformation process. The generated heterojunction structure and 3D porous structure endow CoSe2@NC with accelerated electron/ion transfer ratio and excellent structural stability. As the anode, the CoSe2@NC based half-cell shows superior rate properties (476.4 mA h g−1 at 0.5 A g−1, 372.2 mA h g−1 at 10.0 A g−1) and good cycling stability (354.1 mA h g−1 at 5.0 A g−1 after 800 cycles). Moreover, the CoSe2@NC||NVPOF full cell, assembled by coupling with Na3V2(PO4)2O2F (NVPOF), exhibits a high energy density (136.6 W h kg−1) under a power density of 185.8 W kg−1. This reflects the great potential of the use of CoSe2@NC in the direction of energy storage.