What are the unique advantages of soft pack batteries?

The soft pack battery is actually the use of aluminum-plastic film as the battery packaging material. In contrast, lithium battery assembly is divided into two categories, one is a soft pack battery, and the other is a metal shell battery. The metal shell unit includes steel shell and aluminum shell, cylinder and square, etc. The packaging materials and structure of soft-pack batteries have a series of advantages such as good safety performance. The soft pack battery is encapsulated with aluminum plastic film. When safety issues occur, soft-shell batteries usually explode, unlike steel or aluminum-shell batteries. Lightweight, the steel shell lithium battery with the same capacity is 40% lighter, and the aluminum shell lithium battery is 20% lighter; the internal resistance of the soft pack battery is smaller than that of the lithium battery, which greatly reduces the self-consumption of the battery. The cycle performance is good, the cycle life of the soft pack battery is longer, and the attenuation of 100 cycles is 4% to 7% less than that of the aluminum case. The design is flexible, the shape can be changed to any shape, and it can be thinner. It can be customized according to customer needs and develop new battery models. According to statistics, the output of square, cylindrical and flexible lithium batteries in my country in 2015 were 17GWh, 10.1GWh and 19.8GWh, accounting for 36.4%, 21.5% and 42.3% respectively. With the introduction of the new energy vehicle subsidy policy, the energy density of the battery system has become an important evaluation indicator. The capacity of the ternary flexible battery is 10-15% larger than that of the steel shell lithium battery of the same size, and 5-10% larger than that of the aluminum shell battery. But the weight is lighter than the steel shell battery and aluminum shell battery of the same size. Therefore, the new subsidy policy is more conducive to ternary flexible batteries. In view of the advantages of soft-pack batteries, industry experts predict that with the development of batteries, the penetration rate of soft-pack batteries in the new energy vehicle market will continue to increase, and soft-pack batteries will account for more than 50% of all types The battery is in the future. The materials used in the shell determine their different packaging methods. The soft bag has aluminum-plastic film and needs to be thermally packaged; the metal shell is usually sealed by laser welding. Usually there are three layers of aluminum plastic film and nylon layer to ensure the appearance of the aluminum plastic film and reduce damage to the casing to ensure that the film will not be deformed before processing the lithium battery, prevent air, especially oxygen, permeate, maintain the internal environment of the battery, and ensure packaging at the same time Aluminum foil has good deformability. The aluminum layer is a layer of metallic aluminum. Its purpose is to prevent water infiltration, maintain a certain thickness and strength of the internal environment of the cells, and prevent external damage to the cells. Lithium batteries are very afraid of water, and generally require extreme water content at the PPM level, so the packaging film must be able to block the penetration of water and gas. Nylon is not waterproof and cannot be protected. At room temperature, metallic aluminum reacts with oxygen in the air to form a dense oxide film to prevent water vapor penetration and protect the inside of cells. The aluminum layer also provides the ductility of the crater when the aluminum plastic film is formed. PP is short for polypropylene. This material is characterized by melting and viscosity at temperatures above 100 degrees Celsius. Therefore, the thermal packaging of the battery mainly depends on the melting and bonding of the PP layer under the thermal effect of the head, and then the head is removed for temperature curing and bonding. Polypropylene is not dissolved and swelled by organic solvents in the battery, effectively preventing the internal electrolyte from contacting the aluminum layer and preventing the aluminum layer from being corroded. The aluminum-plastic film looks very simple, but in fact it is not easy how to evenly and firmly combine the three layers of materials. Unfortunately, the quality of aluminum plastic film is basically imported from Japan, and the domestic quality needs to be improved. 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 process does the lithium battery go through before leaving the factory?