Predictive Zeta Potential Measurement Method Applicable to Nonaqueous Solvents in High-concentration Dispersion Systems for the System of LiClO4–Propylene Carbonate Solution and LiCoO2 Powder Sheet (Supporting Information)
We have established a method for measuring the zeta potential generated at the interface between a nonaqueous electrolyte solution utilized in LiClO4/propylene carbonate (PC) electrolyte and lithium cobalt oxide (LiCoO2) by the streaming potential method. Since the surface potential of the metal oxide dispersed in the aprotic nonaqueous solvent contains only a very small amount of water-based potential-determining ions such as H+ and OH−, the potential is determined by the adsorption of the solvated electrolyte itself. Unlike aqueous systems with potential-determining ions that exhibit specific adsorption, it took a very long time until the equilibrium state of the ion distribution near the solid surface was reached and the potential stabilized, with a time constant that amounted to about 5 minutes. Therefore, a detailed analysis of the change over time of the potential after the pressure setting showed that the predictive potential showed a change over time with almost a single relaxation having certain time constant. The measurement time of the streaming potential was corresponded to about the time constant, and the resulting zeta potential showed an anomalous concentration dependence as a maximum around 1.0 mol L−1 PC and a minimum at 1.5 mol L−1 PC for the concentration of each solution.