Nano-sized flexible hollow carbon buffer layer improves capacitance of micro-nano NiS2/C electrode in supercapacitors

Abstract Surface modification of electrode materials is considered as an effect method to improve the charge-discharge performances base on the conductivity and structure stability. In this paper, the surfaces of synthetic micro-nano NiS2/C particles were rebuilt by the nano-sized flexible hollow carbon buffer layer (FHCBL). The NiS2/C@FHCBL exhibits excellent capacitances and cycle stability in supercapacitor. The largest specific capacitance of 1872 F g−1 was obtained under density of 1 A g−1, excellent rate performance of 79.1 % retention at 10 A g−1 and cycle performance with 92 % retention after 5000 cycles, which apparently higher than that of micro-nano NiS2/C electrodes. The fabricated liquid-state NiS2/C@FHCBL||AC hybrid supercapacitor also shows high specific energy and excellent cycling stability with keeping 88.1 % retention after 5000 cycles. Further research shows that the nano-sized flexible hollow carbon buffer layer could not only reveal porous carbon effect, and increase the performances of supercapacitor, but also solve the difficult fill, low active materials mass of porous carbon composites. This research indicates a large kind of materials for potential application in energy storage systems.