A high-performance battery-like supercapacitor electrode with a continuous NiTe network skeleton running throughout Co(OH)2/Co9S8 nanohybrid

Abstract There has been an ongoing effort in pursuing high-energy-density supercapacitor to facilitate its practical applications in energy storage devices. Currently, constructing a composite electrode using multiple battery-type materials or battery-like capacitive materials has been perceived as a promising solution. On one hand, the rational composition/microstructure design is highly desirable to improve the volumetric stress distribution and enhance the overall electrical conductivity. Accordingly, we develop a battery-like (Co(OH)2/Co9S8)@NiTe/Ni composite electrode, in which the continuous NiTe network skeleton running throughout Co(OH)2/Co9S8 nanohybrid acts as the fast electron transfer channel and the buffer against volumetric strain. The electrode delivers a high areal capacitance of 5.28 F cm−2 at a current density of 10 mA cm−2 and demonstrates a super-long cycle life of 50,000 cycles due to the good electrical conductivity, buffer effect of NiTe skeleton and the capacitance contributions from multiple constituents. Thereafter, the assembled aqueous or quasi-solid-state (Co(OH)2/Co9S8)@NiTe/Ni//AC asymmetric supercapacitor demonstrates high areal energy density exceeding 0.88 mWh cm−2 as well as long cycle life exceeding 35,000 cycles. The fabricated battery-like supercapacitor electrode can be engineered to satisfy the long-term, high-power and high-energy-density application requirements.