Comparison of cylindrical lithium battery and pouch lithium battery

Introduction of cylindrical battery and pouch battery
1. Cylindrical battery: The structure of a typical cylindrical battery includes: casing, cap, positive electrode, negative electrode, separator, electrolyte, PTC element, gasket, safety valve, etc. Generally, the battery shell is the negative pole of the battery, the cap is the positive pole of the battery, and the battery shell is made of nickel-plated steel plate.

2. Soft-pack battery: The key materials used in soft-pack lithium batteries, the positive electrode material, negative electrode material and diaphragm, are not much different from traditional steel and aluminum shell lithium batteries. The biggest difference lies in the soft packaging material (aluminum-plastic composite film), which is the most critical and technically difficult material in soft-pack lithium batteries. Flexible packaging materials are usually divided into three layers, namely the outer resistance layer (generally the outer protective layer composed of nylon BOPA or PET), the barrier layer (the middle layer of aluminum foil) and the inner layer (multifunctional high barrier layer).

Comparison of cylindrical battery and pouch battery
1. Safety: The safety performance of the pouch battery is better. The structure of the pouch battery is packaged with aluminum-plastic film. When a safety problem occurs, the pouch battery will generally burst open, unlike steel or aluminum shell cells. Explosion occurs like that; it is superior to cylindrical lithium batteries in terms of safety performance.

2. Battery weight: The weight of the soft-pack battery is relatively light, and the weight of the soft-pack battery is 40% lighter than the steel-cased lithium battery of the same capacity, and 20% lighter than the cylindrical aluminum-cased lithium battery;

3. Internal resistance: The internal resistance of the pouch battery is small, and the internal resistance of the pouch battery is smaller than that of the cylindrical battery, which can greatly reduce the self-consumption of the battery;

4. Cycle performance: The cycle performance of the pouch battery is good, the cycle life of the pouch battery is longer, and the attenuation of 100 cycles is 4% to 7% less than that of a cylindrical aluminum case battery;

5. Battery size: The design of the pouch battery is more flexible, the shape can be changed into any shape, and it can be thinner. It can be customized according to the needs of customers and develop new cell models. Cylindrical lithium batteries do not have this condition.

6. Cost control: Compared with cylindrical lithium batteries, the disadvantages of pouch batteries are poor consistency, high cost, and easy leakage. The high cost can be solved by large-scale production, and the leakage can be solved by improving the quality of aluminum-plastic film.