Ni(OH)2-Co2(OH)3Cl bilayer nanocomposites supported by Ni foams for binder-free electrodes of high-performance hybrid supercapacitors

Abstract Electrochemical materials with ordered nanostructure are widely researched due to the larger contact area with electrolyte and higher utilization rate of electroactive material. Therefore, Ni(OH) 2 -Co 2 (OH) 3 Cl bilayer nanocomposites are firstly synthesized and directly used as binder-free electrodes of high-performance hybrid supercapacitors. Structural characterization results indicate that the as-obtained products belong to bilayer nanocomposites, i.e. : the underlying inter-crosslinked nanosheets are Ni(OH) 2 and the upper embellished flower-like materials are Co 2 (OH) 3 Cl. Electrochemical tests demonstrate that Ni(OH) 2 -Co 2 (OH) 3 Cl bilayer nanocomposites possess higher specific capacity compared with inter-crosslinked Ni(OH) 2 nanosheets. More importantly, hybrid supercapacitors based on Ni(OH) 2 -Co 2 (OH) 3 Cl bilayer nanocomposites and chitosan-derived biomass carbon exhibit high energy density of 37.6 W h kg −1 at power density of 257.8 W kg −1 and 98.21% capacity retention rate after 10,000 charge-discharge cycles. Meanwhile, a mini fan and the “heart” composed of ten LEDs can be easily powered by two tandem hybrid supercapacitors. Hence, it is anticipated that the Ni(OH) 2 -Co 2 (OH) 3 Cl bilayer nanocomposites are the promising materials for hybrid supercapacitors in the future.