What is the reason for battery self-discharge?

There are many situations that cause physical micro-short circuits, which can be divided into the following categories: a. Dust and burrs: many manufacturers will find black spots on the diaphragm when the battery with large self-discharge is disassembled. The middle position is mostly due to dust breakdown and edge The burr is the place where the majority is located. This is easier to distinguish; b. Cathode metal impurities: Why should this be classified into this category? In fact, the metal impurities of the positive electrode also penetrate the separator after the charging reaction, forming black on the separator. For example, many positive iron-lithium materials will face the problem of excessive self-discharge, which is caused by excessive iron impurities; c. negative electrode metal impurities: due to the formation of primary batteries, negative electrode metal impurities will Dissociate and deposit on the diaphragm to cause the diaphragm to conduct and form a physical micro-short circuit. Some low-end anode materials in China often encounter this situation; d. Metal impurities in auxiliary materials: such as adhesive tape. 2. Chemical reaction a. Moisture: Moisture causes the electrolyte to decompose, resulting in low pressure; in addition, moisture is a catalyst in the entire battery, which will generate strong Lewis acid, which will continuously corrode the SEI film and consume lithium sources and cause low battery voltage; b. Electrolyte solvent: the addition of some electrolyte solvents will cause the battery voltage to drop too fast. These solvents are not resistant to oxidation, and slow chemical reactions occur during storage, which consumes capacity and causes the voltage to drop; c. SEI film does not It is well formed. During the storage process, due to the certain temperature of the warehouse, the SEI film will fall off and re-react, resulting in battery flatulence, low pressure, etc.; poor packaging and over-sealing of the tabs may cause corrosion of the tabs and consume the lithium source Low pressure; if other locations are over-sealed, the electrolyte may corrode the aluminum foil through the CPP layer, causing perforation of the aluminum-plastic film, and entering moisture to cause low pressure flatulence 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 article: How to properly use and maintain model aircraft batteries?