Synthesis of nickel-tin oxide/nitrogen-doped reduced graphene oxide composite for asymmetric supercapacitor device

Nickel (Ni) oxide is widely used as supercapacitor electrode materials, but interrogation of tin (Sn) with nickel oxide has not been explored in detail. Herein, Nickel-tin oxide/Nitrogen-doped reduced graphene oxide (NSR) was successfully prepared via hydrothermal method. Various physicochemical analyses showed that the morphology of the synthesized materials can be controlled by varying the Ni:Sn ratio in the initial precursor. Sn played an important role for tuning the morphology as well as the electrochemical performance of the supercapacitor. Nitrogen doping on reduced graphene oxide sheets might improve the electrochemical performance of the electrode materials. It was found that the NSR 2 composite (Ni²⁺/Sn²⁺ = 1:1) showed highest specific capacitance of ∼ 1650 F g⁻¹ at 3 A g⁻¹ current density. An asymmetric supercapacitor (ASC) device fabricated with NSR 2 as positive electrode and sonochemically reduced graphene oxide as the negative electrode materials. The fabricated ASC device exhibited highest energy density of ∼ 38.41 W h kg⁻¹ at a power density of ∼ 2.026 kW kg⁻¹. The retention of energy density was found to be ∼ 79% when the power density increased to ∼ 7.342 kW kg⁻¹. The device showed ∼ 89% capacitance retention after 10,000 continuous GCD cycles. Two ASC devices connected in series was capable to power a 1.8 V red LED light for ∼ 1 min.