The difference between aluminum-cased square lithium batteries and aluminum-plastic film soft-packed square lithium batteries. With the rise of automobile power batteries in recent years, the contradiction between automobile cruising range and battery capacity has become increasingly prominent. Since prismatic batteries have a simpler structure, unlike cylindrical batteries, which use higher-strength stainless steel as casings and accessories with explosion-proof safety valves, Power lithium battery manufacturers mostly use aluminum-cased square batteries with higher battery energy density.
Main difference
1. Square lithium batteries generally use metal aluminum as the battery casing. Since the aluminum material is soft, the thickness of the battery changes when the internal pressure increases during the charging and discharging process and due to gas production and other reasons. In severe cases, it may even cause electrical expansion. In extreme cases, the battery explosion-proof valve opens, causing battery leakage and causing safety accidents. Therefore, analyzing the relevant factors that cause battery thickness problems is of great significance to improving battery thickness performance.
A soft-pack lithium battery is a liquid lithium-ion battery covered with a polymer shell. Since the outer packaging of soft-pack batteries is mostly made of aluminum-plastic film, once there is an internal problem, the soft-pack battery will bulge from the surface of the battery. The weak parts are bulged, and the safety is relatively high.
2. The electrolyte used in aluminum-cased square lithium batteries is liquid, which is easily frozen in low-temperature environments. The internal resistance greatly increases, affecting the battery’s discharge capacity, and may even cause lithium precipitation, which makes the battery deactivate in low-temperature environments; aluminum-plastic Membrane soft-packed square lithium batteries can achieve diversified shapes, higher capacity and greater energy density at low temperatures, and can meet the needs of more equipment applications.
3. The quality and energy density of aluminum-plastic film soft-packed square lithium batteries are higher than those of aluminum-cased square lithium batteries. Aluminum-plastic film soft-packed square lithium batteries of the same volume are about 10%-20% lighter than aluminum-cased square lithium batteries. . Under the current technical conditions, the plasticity of aluminum-plastic film soft-packed square lithium batteries is stronger than that of aluminum-cased square lithium batteries, especially for hybrid models when the layout and weight of the vehicle need to be considered at the same time, aluminum-plastic film soft-packed square lithium batteries The advantages are even more obvious.
4. In terms of manufacturing costs, the materials of aluminum-cased square lithium batteries have been completely localized, and their technical requirements for battery materials are lower than those of aluminum-plastic film soft-packed square lithium batteries. At the same capacity, the overall material cost is higher than that of aluminum-plastic film soft-packed square lithium batteries. Lithium batteries are about 10% lower. The processing of finished aluminum-shell square lithium batteries is relatively simple, and Pack lithium battery packs are reliable and have obvious cost advantages. In addition, the aluminum-cased square lithium battery packaging adopts laser sealing technology, which has strong sealing performance and can effectively avoid the problems of aging and air leakage at the seal.
Advantages and Disadvantages of Aluminum Case Square Lithium Batteries
Advantages: Aluminum shell square lithium battery packaging has high reliability; high system energy efficiency; relatively light weight and high energy density; relatively simple structure, relatively convenient expansion, is currently an important option to increase energy density by increasing cell capacity; single If the unit capacity is large, the system structure is relatively simple, making it possible to monitor each unit one by one; another benefit brought by the simplicity of the system is relatively good stability.
Disadvantages: Since aluminum-cased square lithium batteries can be customized according to the size of the product, there are thousands of models on the market, and because there are too many models, the process is difficult to unify; the level of production automation is not high, and individual differences The reliability is relatively large, and in large-scale applications, there is a problem that the system life is much lower than the single life.
Advantages and disadvantages of aluminum-plastic film soft-packed square lithium batteries
Advantages: Aluminum-plastic film soft-packed square lithium batteries have large deformation space, are light in weight, and have a small proportion of inactive parts. The weight of soft-packed batteries is 40% lighter than steel-cased lithium batteries of the same capacity, and 20% lighter than aluminum-cased batteries; the same Compared with the size specifications, the capacity of soft-pack batteries is 10-15% higher than that of steel-shell batteries of the same size, and 5-10% higher than that of aluminum-shell batteries. The strength of the shell is low, and the mechanical damage to the internal structure is caused during the cycle. The stress is small, which is beneficial to the cycle life; the tab position is sufficient, and the heat is evenly distributed during charging and discharging.
Disadvantages: low shell strength and strong dependence on grouping technology; compared with the winding production method, the production efficiency of lamination is relatively low;
In general, aluminum-cased square lithium batteries and aluminum-plastic film soft-packed square lithium batteries have their own advantages and disadvantages. Each battery has its own dominant field. For example, among aluminum-cased square lithium batteries, there are more lithium iron phosphate batteries. , there are more ternary lithium batteries in aluminum-plastic film soft-packed square lithium batteries. With the introduction of new subsidy policies for new energy vehicles, the system energy density of batteries has become an important assessment indicator.
Whether it is aluminum-cased square lithium batteries or aluminum-plastic film soft-packed square lithium batteries, they are currently developing rapidly because they are well used in their respective application fields. Domestic power battery manufacturers are predicting that square shapes will become the mainstream of power batteries. Through continuous technological innovation, the energy density of vehicle batteries will continue to increase, and battery performance will become even better.
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