Design and mechanism study of multi-phase materials for cathodes in high-performance supercapacitors

Binder-free porous multi-phase electrodes were grown on Ni foam substrates using a hydrothermal method. This multi-phase electrode was inspired by high-entropy materials, which constituents with different atomic sizes can be used to fabricate electrodes with a high strength, high hardness, and good corrosion resistance. Owing to their unique microscopic structure, well-organized, independent, nanoscale multi-phase electrodes present high electrical conductivities and good ion transport abilities, rendering them attractive for high-performance energy storage systems. Herein, Ni-Cu-Fe-Co- and Mn-containing multi-phase electrodes were fabricated at different reaction times. Among them, the optimized multi-phase electrode, which was fabricated after 12 h of heating, exhibited a remarkably high specific capacity of 1011 mAh g(-1) at a current density of 3 A g(-1). And an excellent cycling stability of 87% after 5000 charge-discharge cycles at a current density of 10 A g(-1). The asymmetric supercapacitor fabricated using the optimized multi-phase composite and graphene as the cathode and anode, respectively, presented a high energy density of 53.2 W h kg(-1) and excellent power density of 1302.7 W h kg(-1), and could turn on a light-emitting diode. Thus, adjustable high-performance electrodes can be used to develop new energy storage applications.