Reversible and irreversible dilation of lithium-ion battery electrodes investigated by in-situ dilatometry

The technique of electrochemical in-situ dilatometry is applied to study the intercalation induced macroscopic expansion of electrodes for lithium-ion batteries. A full cell setup is used to investigate the expansion under real conditions. This method enables in-situ measurement of expansion under defined pressure, using conventional electrodes, separators and electrolytes. To understand the influence of the microstructure, the swelling behavior of different LiNi1/3 Mn1/3 Co1/3 O2 (NMC) positive electrodes and graphite negative electrodes is measured and systematically analyzed. A theoretical approach for assessment of reversible electrode displacement in a full cell is developed, by using a low number of material specific input parameters. Electrochemical in-situ dilatometry is able to show differences in irreversible dilation depending on electrode design and therefore it is a powerful technique for stability and lifetime assessment.