Favorable anion adsorption/desorption of high rate NiSe2 nanosheets/hollow mesoporous carbon for battery-supercapacitor hybrid devices

High-rate battery-type cathode materials have attracted wide attention for advanced battery-supercapacitor hybrid (BSH) devices. Herein, a core-shell structure of the hollow mesoporous carbon spheres (HMCS) supported NiSe2 nanosheets (HMCS/NiSe2) is constructed through two-step reactions. The HMCS/NiSe2 shows a max specific capacity of 1,153.5 C.g(-1) at the current density of 1 A.g(-1), and can remain at 774.5 C.g(-1) even at 40 A.g(-1) (the retention rate as high as 67.1%) and then the HMCS/NiSe2 electrode can keep 80.5% specific capacity after 5,000 cycles at a current density of 10 A.g(-1). Moreover, the density functional theory (DFT) calculation confirmed that the introduction HMCS into NiSe2 made adsorption/desorption of OH- easier, which can achieve higher rate capability. The HMCS/NiSe2//6 M KOH//HMCS hybrid device has energy density of 47.15 Wh.kg(-1) and power density of 801.8 W.kg(-1). This work provides a feasible electrode material with a high rate and its preparation method for high energy density and power density energy storage devices.

Automated summary

In this study, a core-shell structure of HMCS/NiSe2 electrode material was successfully constructed, showing excellent performance at high current densities and cycling stability. The modification of NiSe2 with HMCS was confirmed to enhance its rate capability through both theoretical calculations and experimental results. This work provides a feasible electrode material for high energy density and power density energy storage devices.