Water-suspended graphene as electrolyte additive in zinc-air alkaline battery system

Abstract

Zinc-air (Zn-air) batteries possess high-energy density due to surplus air involved in reduction reaction at air cathode and are an important energy source used for automobiles and grid storage. In this study, the scope of improvements in the efficiency of Zn-air batteries are investigated through addition of water-soluble graphene (WSG) as a corrosion inhibitor in 1 M KOH electrolyte. Phase and microstructure analysis for the synthesized WSG shows the formation of few layers of graphene due to the presence of an intense XRD peak of carbon at 26.3° and the flake-like structure confirmed by SEM. The discharge capacity, corrosion behavior, and electrochemical impedance analysis performed on conventional Zn-air battery shows improved performance when tested with WSG as an additive in 1 M KOH electrolyte. Results from short-circuit test show that immersion of WSG in 1 M KOH electrolyte increased the current density from 20.3 to 26.43 mAcm−2. Whereas, galvanostatic discharge measurement reveals that Zn-air battery in WSG added with 1 M KOH electrolyte has a specific discharge capacity of ~ 212.6 mAhg−1 higher than that obtained in 1 M KOH electrolyte (~ 160.4 mAhg−1).Overall, the WSG-based Zn-air battery shows good self-discharge capacity and higher electrochemical activity during discharge holds promise as an electrolyte additive for Zn-air system.