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

Abstract

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.

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