The yolk-shell nanorod structure of Ni₃Se₂@C electrodes boosting charge transfer and cyclability in high-performance...

Developing novel electrode materials with reasonable structures and ideal conductivity is of great significance for energy storage devices. In this work, Ni₃Se₂@C yolk-shell nanorods are grown on nickel foam (NF) via a one-step selenization and carbonization process. The carbon shell not only improves the conductivity and charge transfer of electrodes, but also inhibits the dissociation of Ni₃Se₂ core during redox reactions, which is crucial to electrochemical performances of SCs. Owing to the yolk-shell nanorod structure, the Ni₃Se₂@C electrode exhibits an outstanding specific capacitance of 1669.7F g^-1 at 1 A g^-1. Moreover, an asymmetric supercapacitor (ASC) is successfully assembled using Ni₃Se₂@C and active carbon (AC) electrodes as the anode and cathode respectively, which delivers remarkable energy-storage characteristics. Specifically, the Ni₃Se₂@C//AC ASC shows a high energy density (31.0 Wh kg^-1) at a power density (723.7 W kg^-1), and stable cycling performance (97% capacitance retention after 9000 cycles). These results make the Ni₃Se₂@C a promising electrode for SCs.