One-pot hydrothermal synthesis of 3D Cu2Se/CoSe composite as a novel battery-type cathode material with enhanced capacitive properties

Transition metal selenides as a new kind of battery-type cathode material for supercapacitors have recently drawn increasing interest. Herein, the novel three-dimensional (3D) Cu2Se/CoSe composite is synthesized via a facile one-pot hydrothermal approach and firstly utilized as a battery-type supercapacitor cathode material. Due to the synergistic effect of the Cu2Se nanoparticles and ultrathin CoSe nanosheets as well as unique 3D porous composite structure with a big specific surface area, mesopore/macropore-rich structure and splendid electronic conductivity, the as-resulted Cu2Se/CoSe composite electrode displays an enhanced specific capacity of 108.6 mAh g−1 at 1 A g−1 and rate property with 88.8%, 63.0% and 52.9% of capacity retention at 10, 50 and 100 A g−1 in comparison with the single Cu2Se and CoSe electrodes. The exceptional kinetic behavior of the Cu2Se/CoSe composite electrode can be elucidated by the calculated diffusion coefficient and charge contribution ratio obtained from the cyclic voltammetry curves. Moreover, the as-prepared Cu2Se/CoSe composite electrode manifests excellent cycle stability with 113.5% of initial capacity retention at 10 A g−1 after 10,000 cycles. The appealing results above reveal that the as-obtained Cu2Se/CoSe composite can be considered as a prospective battery-type cathode material for supercapacitors.