Quantificational 4D visualization and mechanism analysis of inhomogeneous electrolyte wetting

The inhomogeneous electrolyte distribution in lithium-ion batteries affects lithium-ion transfer, which attenuates battery performance and leads to thermal runaway. Moreover, real-time quantitative observations and an in-depth understanding of electrolyte wetting remain limited because of the harsh electrochemical environment. In this study, in-situ 4D X-ray computed tomography was used to monitor the electrolyte wetting by adding a contrast agent to the electrolyte. The mechanism through which the winding stress influenced electrolyte wetting was elucidated using a combination of experimental and porous-media-flow simulation methods. The winding stress was found to affect the soaking time and uniformity of the electrolyte distribution. Optimization strategies involving variable tension and pressurized injection improved the uniformity of the electrolyte wetting and shortened the electrolyte wetting time. This study provides practical guidance for the optimization of the electrolyte filling during battery fabrication.