Electrochemical stability of steel, Ti, and Cu current collectors in water-in-salt electrolyte for green batteries and supercapacitors

The electrochemical behaviour of steel, copper, and titanium current collectors was studied in aqueous solutions of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) at various concentrations, from 0.5 up to 20 m. As the concentration of the electrolyte increases, the electrochemical window of water stability widens according to the water-in-salt concept. The metal grids have been studied electrochemically, both under anodic and cathodic conditions, by means of cyclic voltammetry and chronoamperometry. Subsequently, a microscopic analysis with SEM and compositional analysis with XPS was carried out to evaluate the surface modifications following electrochemical stress. We found that copper is not very suitable for this kind of application, while titanium and steel showed interesting behaviour and large electrochemical window.

Automated summary

This study investigates the electrochemical behavior of steel, copper, and titanium current collectors in LiTFSI solutions of different concentrations. It is found that the electrochemical window of water stability widens with increasing electrolyte concentration, based on the water-in-salt concept. The metal grids are studied using cyclic voltammetry and chronoamperometry under both anodic and cathodic conditions. Microscopic and compositional analyses reveal that copper is not suitable for this application, while titanium and steel show interesting behavior and a large electrochemical window.