Systematic study and effective improvement of voltammetry for accurate electrochemical window measurement of solid electrolytes

The availability of solid electrolytes promisingly boosts the energy density of lithium-ion batteries (LIBs), yet the accurate voltammetry measurement of their electrochemical windows (EWs) poses a longstanding and critical concern. In this work, the mechanism of EW measurement of electrolytes is explained using the electrical double layer theory. The influence of crucial variables in voltammetry, including the scan mode, the working electrode, and the selection of two- or three-electrode test systems is investigated. Furthermore, the step voltammetry method is proposed and applied to EW testing of the inorganic solid electrolyte Li10GeP2S12 for the first time. Finally, suggestions for EW measurement of electrolytes are presented. The results of this work promote a comprehensive understanding and more accurate EW measurement of electrolytes, facilitating the selection of suitable solid electrolytes to match different cathodes, thus advancing the development of safer high-energy density LIBs.