α-NiO/Ni(OH)₂/AgNP/F-Graphene Composite for Energy Storage Application

The α-NiO/Ni(OH)2/AgNP/F-graphene composite, which is silver nanoparticles preanchored on the surface of fluorinated graphene (AgNP/FG) and then added to α-NiO/Ni(OH)2, is investigated as a potential battery material. The addition of AgNP/FG endows the electrochemical redox reaction of α-NiO/Ni(OH)2 with a synergistic effect, resulting in enhanced Faradaic efficiency with the redox reactions of silver accompanied by the OER and the ORR. It resulted in enhanced specific capacitance (F g–1) and capacity (mA h g–1). The specific capacitance of α-NiO/Ni(OH)2 increased from 148 to 356 F g–1 with the addition of AgNP(20)/FG, while it increased to 226 F g–1 with the addition of AgNPs alone without F-graphene. The specific capacitance of α-NiO/Ni(OH)2/AgNP(20)/FG further increased up to 1153 F g–1 with a change in the voltage scan rate from 20 to 5 mV/s and the Nafion-free α-NiO/Ni(OH)2/AgNP(20)/FG composite. In a similar trend, the specific capacity of α-NiO/Ni(OH)2 increased from 266 to 545 mA h g–1 by the addition of AgNP(20)/FG. The performance of hybrid Zn–Ni/Ag/air electrochemical reactions by α-NiO/Ni(OH)2/AgNP(200)/FG and Zn-coupled electrodes indicates a potential for a secondary battery. It results in a specific capacity of 1200 mA h g–1 and a specific energy of 660 W h kg–1, which is divided into Zn–Ni reactions of ∼95 W h kg–1 and Zn–Ag/air reactions of ∼420 W h kg–1, while undergoing a Zn–air reaction of ∼145 W h kg–1.