Abstract:The use of various electrolyte materials in a lithium ion battery must be studied under stable electrochemical conditions; therefore, the LiClO4 activity coefficients in water at the temperatures described in this work are the result of an electrochemical cell (ISE): Na-ISE|LiClO4(m)|ClO4-ISE. For this study, the determination of activity coefficients was carried out using the Pitzer and Debye–Hückel equations to represent the relationship between log γ and molality. For the system used with the electrochemical cell, it has good the behavior of mean ionic activity coefficients of LiClO4 for all temperatures, and at a temperature of 298.15 K, there is good agreement between the experimental data and the data in the literature.