Effect of the mass transport limitations on the stability window of electrolytes for metal-ion batteries

Stationary battery systems have been proposed as plausible alternative for the storage of renewable energy sources in power grid. For this application aqueous electrolytes are preferred, which offer several important advantages compared to organic electrolytes i.e. non-flammability, cost effectiveness, as well as higher ionic conductivity, solubility and thermal capacity. This work was undertaken to investigate the influence of pH on the electrochemical stability window of aqueous electrolytes for metal-ion batteries. The pH was deliberately controlled in the range from pH 2 to 11. Electrochemical chronopotentiometry method served for the electrochemical stability window measurements. It has been observed that the pH critically influenced the measured dynamic stability window, which shows a maximum and almost pH independent value for pH ranging from 5 to 9. The presence of buffering ions and gelling agents strongly affects the dynamic stability window of the electrolyte through the transport overpotential.