**2.2 Viscosity measurement**

Viscosity measurements were conducted with a "DV-2 + PRO" digital viscometer (Shanghai Nirun Co., Ltd.). The electrolyte was placed on a thermostatic dry heater, and the temperature of the solution was measured by a thermocouple thermometer. When the electrolyte reached the predetermined temperature, measure three times the viscosity at each temperature point, and take the average.
