What are the effects of moisture on lithium batteries?

The influence of moisture on the discharge capacity The first discharge capacity of the battery decreases with the increase of moisture in the battery. Under the condition of a constant lithium source, the change of the battery's first discharge capacity is mainly restricted by two important factors. 1. The formation of SEI film consumes part of Li and causes irreversible capacity loss. The lithium alkyl carbonate generated during the single-electron reduction process can also react with trace water in the electrolyte, 2ROC02Li+H2O→LieC03+C02+2ROH, when After CO2 is generated, a new chemical reaction occurs on the surface of the negative electrode at a low potential: 2C02+2Li++2e→LieC03+CO. 2. After the SEI film is formed, in the presence of H2O, H2O will promote the decomposition of LiPF6 in the electrolyte and shorten the battery discharge time, LiPF6→LiF+PFs, PFs+H2O→POF3+2HF. The influence of moisture on the internal resistance of lithium batteries As the moisture of the battery increases, the internal resistance tends to rise. There are two important factors for the difference in battery internal resistance. 1. The difference in SEI film leads to the difference in battery internal resistance. In the electrolyte solvent system, trace amounts of water can form an SEI film with Li2CO3 as the main component, with good stability, uniformity and compactness, and its internal resistance is small. 2. When the moisture content is more than the required content of the system to form the SEI film, POF3 and LiF will be precipitated on the surface of the SEI film, which will cause the internal resistance of the battery to increase. The influence of moisture on the attenuation of battery cycle capacity The attenuation of battery capacity gradually decreases with the increase in moisture content. This is related to the density and uniformity of the SEI film. When the SEI film is uniform and dense, the electrolyte solvent is not easy to embed in the negative electrode, occupying the Li ten intercalated vacancies, so the capacity attenuation is small. On the contrary, when the part of the SEI film is not dense or uniform, it is relatively easy for the Li intercalated vacancies to be occupied by the electrolyte solvent. LieC03 is the most important component to form a uniform and dense SEI film. In the electrolyte solvent system, when the water content is excessive, the SEI film will not be dense and uneven locally, so the capacity attenuation increases. Disclaimer: Some pictures and content of articles published on this site are from the Internet. If there is any infringement, please contact to delete. Previous: What is the cause of the explosion of the secondary battery?