Comparison of Structure and Technical Characteristics between Square and Soft pack Lithium ion Batteries
There are currently two main packaging methods for lithium-ion batteries: square packaging and soft packaging. Different packaging structures imply different characteristics, each with its own advantages and disadvantages.
Square lithium-ion battery
Square lithium-ion batteries, commonly known as aluminum or steel angle gauge battery cases, have a high penetration rate of square cells in China. With the rise of automotive power lithium batteries in recent years, the capacity of life journey batteries has become increasingly prominent. Domestic power lithium battery manufacturers choose high energy density aluminum square batteries as the main choice because the cell structure is relatively short. Unlike cylindrical batteries, square batteries use high-strength stainless steel as the outer shell and have accessories such as explosion-proof safety valves. Therefore, the entire accessory component is lightweight and has a relatively high energy density. There are two different processes for square batteries: winding and laminating.
However, due to the fact that square lithium-ion batteries can be customized according to the size of the product, there are thousands of different types on the market, and due to the large number of types, it is difficult to unify the process. The use of square batteries in general electronic products is not a problem, but it is more important than a series of parallel industrial equipment products to fully utilize the production of standardized cylindrical lithium-ion batteries. Therefore, the production process ensures that it will be easier to find and replace batteries in the future.
Soft pack lithium-ion battery
The key data for the use of soft pack lithium-ion batteries include positive electrode data, negative electrode data, and barriers. The difference between steel and traditional aluminum lithium-ion batteries is not significant. The biggest difference is the data of the soft pack (aluminum-plastic composite film), which is the most important and technically difficult data in soft pack lithium-ion batteries. Soft packaging information is usually divided into three layers, namely the outer resistance layer (usually composed of nylon BOPA or PET outer protective layer), the permeation resistance layer (aluminum foil intermediate layer), and the inner layer (multifunctional high resistance layer).
Soft pack battery packaging materials and structures have a series of advantages, such as good safety functions, aluminum plastic film packaging for the selection structure of soft pack batteries, attacks on safety issues, and the fact that soft pack batteries usually rupture instead of exploding like steel or aluminum shell batteries; Lightweight, soft pack batteries are 40% lighter than steel lithium-ion batteries of the same capacity and 20% lighter than aluminum lithium-ion batteries; The internal resistance is very small. The internal resistance of a battery is smaller than that of a lithium-ion battery. Having good cycling function, the soft pack battery has a longer cycle life, and the attenuation after 100 cycles is 4%~7% smaller than that of the aluminum shell. Flexible design, adjustable shape, can be thinner, can be customized according to customer needs, and new types of batteries can be developed. The shortcomings of soft pack batteries are poor consistency, high cost, and short-term attack leakage. High costs can be addressed through large-scale production, and leakage can be treated by improving the quality of aluminum-plastic film.
