Off-line method of the separation of the electrodes equilibrium state of the Li-ion batteries

To ensure better performances of the Li-ion batteries in applications such as electric vehicles, the monitoring of their state with a BMS (Battery Management System) is required. To this end, non-invasive tools are needed to perform monitoring of the battery at the electrode scale. In this paper, we propose a method to extract from charge and discharge of the battery, the electrodes informations (equilibrium potentials, capacities and lithiation rates as functions of the battery state of charge). A pseudo-OCV model has been used to determine these informations. The proposed method allows to reduce the bias related to the battery overvoltage. Evaluated on a LFP/graphite lithium ion battery, the needed parameters were obtained with an accuracy of about 1 mV on the pseudo-OCV average (between discharge and charge) measurements of the battery. This method can be used for any battery chemestry.