Performance comparison of semi-solid-state batteries with liquid electrolyte batteries: a perspective from vehicle operation

Electrolyte solidification technology is one of the most important trends in improving the safety and cycle performance of batteries. In this study, 12 vehicles of two mass production versions from the same manufacturer are selected. The batteries they carry are liquid electrolyte batteries and semi-solid-state batteries that use gel solidification technology, respectively. Calculations and comparative analysis of ohmic internal resistance, capacity degradation, cell consistency, and incremental capacity curves are performed. Semi-solid-state batteries have a larger range of variation in ohmic internal resistance, i.e., lower at high temperatures and higher at low temperatures. Within the temperature range of 5 °C to 39 °C, the minimum internal resistance of liquid electrolyte batteries is approximately 0.02 Ω (0.01783 Ω to 0.02098 Ω), while the maximum internal resistance is approximately 0.04 Ω (0.03881 Ω to 0.04616 Ω). The minimum internal resistance of semi-solid-state batteries is approximately 0.01 Ω (0.00971 Ω to 0.01357 Ω), while the maximum internal resistance is around 0.06 Ω (0.05354 Ω to 0.06373 Ω). In terms of capacity, liquid electrolyte batteries have more stable decay rates across vehicles, while semi-solid-state batteries have more fluctuating capacity degradation rates. The capacity degradation rates of liquid electrolyte batteries remain around −0.0002, while those of semi-solid-state batteries fluctuate between −0.0003 and 0. In terms of inconsistency, semi-solid-state batteries have less volatility in the voltage distribution of cells but perform poorly in extreme cells. In terms of the incremental capacity curve, liquid electrolyte batteries show a significant peak shift, while the peak change of semi-solid batteries is not significant. Comparing the parameters of the two battery types from a vehicle operation perspective provides a clear understanding of the current shortcomings of semi-solid-state batteries, facilitating targeted optimization and adjustments in the future. The performance comparison has important guiding significance for the development of solid-state batteries.