A method to implement the electrode-entropy differentiation for lithium batteries

Abstract

This work presents the method and apparatus for the reproduction of the electrode-entropy differentiation approach which provides a tool to nondesctructively determine the contribution of each electrode to the battery total entropy by performing a comparative study with another battery which shares the same composition for only one of its electrodes (semi-similar types). The 2 cells must go through the same aging process so the proposed method can be applied as follow. Firstly, an optional pre-processing step is performed, followed by linear regression between capacity loss and entropy evolution over the full SOC range. Then, a correlation is computed for each SOC value between the entropy evolution of the two cells. The result of that correlation shows at which SOC the evolution of the two cells is similar. Postulating that half-cells of the same chemistry going under the same aging conditions age the same way, the common-mode highlighted by the correlation is the SOC-domain at which the entropy of the common half-cell is dominating. This method allows improves prior art by removing the need for custom-made half-cells of the same battery composition. The feasibility of the electrode-entropy differentiation methods is postulated, and the method is detailed. A validation study is performed on a set of batteries and the method feasibility is confirmed by the results obtained. This paper: Demonstrates the feasibility of extracting the entropy from the comparative study between the subject cell and a reference. Includes a validation test. Suggest application of the method in the field of electrodes diagnosis.