The effect of alkaline electrolytes and silver nanoparticles on the electrochemical performance of the dilithium nickel bis(tungstate) as electrode materials for high-performance asymmetric supercapacitor

In the present work, the dilithium nickel bis(tungstate), Li2Ni(WO4)(2), is synthesized by an easy chemical method (self-combustion) and followed by a coating of silver nanoparticles (Ag NPs) by reduction of silver ions (Ag+) to improve their electrical conductivity. These materials are explored for the first time as a positive electrode of a supercapacitor. The electrochemical properties of the Li2Ni(WO4)(2) and Li2Ni (WO4)(2)@Ag electrodes are determined in three alkaline electrolytes such as LiOH, NaOH, and KOH using CV, GCD, and EIS. The specific capacity of the Li2Ni(WO4)(2) electrode changed depending on the type of electrolyte where the LiOH electrolyte shows the highest value of 580.4 C/g at 1 A/g. The Li2Ni(WO4)(2)@Ag electrode can demonstrate a specific capacity almost 2.5 times higher (1402 C/g at 1 A/g) than the electrode without silver and excellent retention capacity of 89.2% after 10,000 cycles at 20 A/g. In addition, the asymmetrical supercapacitor Li2Ni(WO4)(2)@Ag//alpha-MnO2/rGO was assembled and provided a high energy density of 96.4 Wh/kg at 900 W/kg and has an excellent retention capacity (77.9%) after 10,000 cycles of charge-discharge tests at 10 A/g. Moreover, two asymmetric supercapacitors in series were used to light a red LED for 1742 s and a motor for 53 s (C) 2021 Elsevier B.V. All rights reserved.