Technical characteristics of lithium batteries -Lithium - Ion Battery Equipment

Comparative breakdown of technical characteristics of cylindrical, prismatic and soft-pack lithium-ion batteries -Lithium - Ion Battery Equipment

Square lithium-ion battery

Square lithium-ion batteries usually refer to aluminum-shell or steel-shell square batteries. The popularity of square batteries is very high in China. With the rise of automotive power lithium-ion batteries in recent years, the contradiction between vehicle mileage and battery capacity has become increasingly prominent. Domestic Power lithium-ion battery manufacturers mostly use aluminum-shell prismatic batteries with higher battery energy density, because the structure of prismatic batteries is relatively simple, unlike cylindrical batteries that use higher-strength stainless steel as the shell and accessories such as explosion-proof safety valves. Therefore, the overall accessory should be light in weight and have a relatively high energy density. Square batteries use two different processes: winding and lamination.

However, because prismatic lithium-ion batteries can be customized according to the size of the product, there are thousands of models on the market, and because there are so many models, it is difficult to unify the process. There is no problem in using square batteries in general electronic products, but for industrial equipment products that require multiple series or parallel connections, it is best to use standardized cylindrical lithium-ion batteries. This way the processing technology is guaranteed and it will be easier to find replacements in the future. of battery.(Lithium - Ion Battery Equipment)

Soft pack lithium-ion battery

The key materials used in soft-packed lithium-ion batteries, such as positive electrode materials, negative electrode materials and separators, are not much different from traditional steel-shell and aluminum-shell lithium-ion batteries. The biggest difference lies in the soft packaging material (aluminum-plastic composite film). It is the most critical and technically difficult material in soft-pack lithium-ion batteries. Flexible packaging materials are usually divided into three layers, namely the outer barrier layer (generally an outer protective layer composed of nylon bOPA or PET), the barrier layer (middle layer aluminum foil) and the inner layer (multifunctional high barrier layer).

The packaging material and structure of the soft-pack battery give it a series of advantages. The Electric Zhijia public account summarizes, for example, the safety performance of the soft-pack battery is good. The soft-pack battery is structurally packaged with aluminum plastic film. When safety problems occur, the soft-pack battery generally It will bulge and crack, instead of exploding like steel-cased or aluminum-cased batteries; it is light in weight, and the weight of soft-pack batteries is 40% lighter than steel-cased lithium-ion batteries of the same capacity, and 20% lighter than aluminum-cased lithium-ion batteries; Small internal resistance, the internal resistance of the soft-pack battery is smaller than that of the lithium-ion battery, which can greatly reduce the self-consumption of the battery; the cycle performance is good, the cycle life of the soft-pack battery is longer, and the attenuation after 100 cycles is 4% less than that of the aluminum case. ~7%; the design is flexible, the shape can be changed to any shape, it can be thinner, and new battery cell models can be customized and developed according to customer needs. The disadvantages of soft-pack batteries are poor consistency, high cost, and prone to leakage. High costs can be dealt with through large-scale processing, while liquid leakage can be dealt with by improving the quality of aluminum plastic films.

Comparative breakdown of technical characteristics

1. Battery shape: Square lithium-ion batteries can be of any size, so they are incomparable to cylindrical batteries.

2. Rate characteristics: There are process limitations for welding multi-pole tabs of cylindrical lithium-ion batteries, so the rate characteristics are slightly worse than the square multi-pole tab method.

3. Discharge platform: The same positive electrode material, negative electrode material, and electrolyte are used, so the discharge platform is theoretically the same. However, the internal resistance of the square battery has a slight advantage, so the discharge platform is slightly higher.

4. Product quality: The cylindrical lithium-ion battery process is very mature, the probability of common secondary slitting defects of pole pieces is low, and the winding process is more mature and automated than the lamination process. The lamination process is still using a semi-manual method. , so there is a negative impact on the quality of the battery.

5. Welding of tabs: The tabs of cylindrical lithium-ion batteries are easier to weld than square lithium-ion batteries. Square batteries are prone to false welding, which affects battery quality.



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