MOF-derived carbon-coated NiS/NiS2 yolk-shell spheres as a satisfactory positive electrode material for hybrid supercapacitors
Jing Wang, Shuo Li, Ning Fu, Dayong Tian, Yong Zheng, Fang Wang, Chao Liu, Xiaolong Wang, Zhongyuan Zhou, Yongsheng Niu, Hao Liu, Guoxiu Wang, Shichun Mu, Jiahuan Luo
Abstract
Optimizing the performance of electrode materials to improve the energy density of supercapacitors is the focus of current research. Construction and design with complex yolk-shell structure, as a supercapacitor electrode material, are of great significance and challenging. Herein, a self-sacrificing template strategy was used to construct uniform carbon-modified NiS/NiS 2 yolk-shell spheres using a Ni-based metal–organic framework (Ni-soc-MOF) as the precursors. Especially, the carbon shells produced by the pyrolysis of the organic ligand can improve mechanical stability and electron conductivity. Therefore, the as-obtained NiS/NiS 2 @C nanocomposites display a high specific capacity (1082 C g −1 at 1 A g −1 ) and outstanding cycling stability (85% capacity retention after 5000 cycles). In addition, a hybrid supercapacitor device based on the yolk-shell NiS/NiS 2 @C nanocomposite and porous carbon can deliver a high energy density of 56.2 Wh kg −1 at 800 W kg −1 , while exhibiting an excellent capacity retention of 86% after 10,000 charge/discharge cycles, demonstrating the promising potential of yolk-shell NiS/NiS 2 @C nanocomposites via Ni-soc-MOF-derived route in practical application.