The entropy variation DS is related to the structural changes of the active materials during operation. The corresponding energy variations may result in heat generation or consumption depending on the SoC and the current sign. This behavior can be modeled by Equation (1) where I is the current, T is the absolute temperature (in Kelvin), n is the number of exchanged electrons during the reaction (n 1⁄4 1 here) and F is the Faraday constant