Investigation of lead-acid battery water loss by in-situ electrochemical impedance spectroscopy

Understanding the chemical reactions that occur during lead-acid battery aging is useful for predicting battery life and repairing batteries for reuse. Current research on lead-acid battery degradation primarily focuses on their capacity and lifespan while disregarding the chemical changes that take place during battery aging. Motivated by this, this paper aims to utilize in-situ electrochemical impedance spectroscopy (in-situ EIS) to develop a clear indicator of water loss, which is a key battery aging process and could be repaired, through unique water loss experiments. These experiments were designed to ensure that the percentage of water in the electrolyte or the volume of electrolyte was the only factor that affected in-situ EIS in each experiment, and these values were regularly changed to simulate water loss in a specially designed transparent lead-acid battery. Through an improved equivalent circuit model (ECM) and grey relation analysis (GRA), this work shows that the variation of double-layer capacity and internal resistance can indicate added water content and electrolyte volume. The developed method is simple and can be applied to identify and respond to battery water loss effectively.