Measuring Method of Electrochemically Active Surface Area in All‐Solid‐State Lithium‐Ion Batteries

A simple electrolyte/electrode interface using a thin film of active material in cathode is constructed to enable measurement of electrochemically active surface area (ECSA) in all‐solid‐state batteries. The correlation between specific capacitance and specific surface area at the interface is investigated. The correlation has a linear relationship and give a calibration curve. Using the calibration curve as a clue, ECSA of a composite electrode is quantitatively determined from the specific capacitance of the composite cell obtained using electrochemical impedance spectroscopy.