Construction of sea urchin-like NiCo-bimetallic selenide/N-dope carbon composite for high-performance sodium ion hybrid capacitors

As a high-performance energy storage device, sodium-ion hybrid capacitors (SIHCs) still face the challenge of finding anode materials with fast kinetic behavior and stability to match capacitive electrode materials with fast kinetics. Transition metal selenides are expected to be ideal anode materials for batteries due to their high theoretical sodium storage capacity and fast ion diffusion rate. However, large volume change and poor conductivity hinder their practical application. In this paper, NiCo-bimetallic selenide embedded in N-doped porous carbon matrix (NiCoSe 2 /NC), presenting a spherical architecture similar to that of a sea urchin, was prepared by controllable selenization of NiCo-bimetallic organic framework. The synergistic effect between nickel‑cobalt selenides increases the sodium storage active sites and improves the conductivity and structural stability. The good conductive network and ion transport channel formed by N-doped hierarchically porous carbon can effectively improve the kinetic behavior, alleviate the volume change and maintain the structural stability of the material during the energy storage process. Consequently, the as-built SIHC based on the NiCoSe 2 /NC anode and home-made porous carbon cathode has high energy-power characteristics (113.1 Wh kg −1 /14 kW kg −1 ) and excellent cycle stability (98.6% capacity retention after 10,000 cycles at 1 A g −1 ), showing great potential for application in the energy storage field.