Discussion on the effect of uniform infiltration of electrolyte in lithium battery

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2019-12-30

With years of work, we have summed up an experience for lithium-ion batteries. For lithium electronic batteries, the most important word-"uniform", why is this word so important? From the perspective of the entire production process of lithium batteries, it is a homogenization process. The purpose of homogenization is to "uniformly" (emphatically) mix the active substances, conductive agents, binders and other components together. Then there is the coating process. The key is to ensure the "uniformity" of the coating amount and avoid problems such as poor product consistency caused by fluctuations in the coating amount. Then there is the liquid injection process, it is also necessary to ensure that the electrolyte is "evenly" infiltrated inside the battery core to ensure battery performance and cycle life; in the production process of the battery module, it is important to have the consistency of the single battery, that is, "uniformity". To ensure that the performance of the battery pack is fully utilized.

How to ensure that the electrolyte is fully and evenly infiltrated in the lithium battery core is a difficult problem that has plagued lithium battery production for many years, and countless lithium battery engineers have paid a lot of effort for it. In order to improve the infiltration effect of the diaphragm and the electrolyte, Ethan Rao et al. of the University of California, USA, by coating a layer of perfluorophenyl azide PFPA on the surface of the ordinary polymer diaphragm, thus greatly improving the wettability between the electrolyte and the diaphragm. The good wettability of the separator can significantly improve the performance of lithium-ion batteries, which is reflected in the reduction of internal resistance.

Generally, we believe that gravity will have a certain influence on the wettability of lithium ion batteries. Therefore, in order to ensure the wetting effect, it is necessary to "turn over" the lithium ion batteries after liquid injection regularly. However, W.J. Weydanz found that gravity has little influence on the wetting process of electrolyte by analyzing the wetting speed in the upper and lower directions, and the influence of gravity on the wetting process of lithium ion batteries can be basically ignored.