Comparison and decomposition of technical characteristics of cylindrical, square and soft-pack lithium batteries

Square lithium battery Square lithium battery usually refers to aluminum shell or steel shell square battery. The popularity of square battery is very high in China. With the rise of automobile power lithium-ion batteries in recent years, the contradiction between automobile mileage and battery capacity has become increasingly prominent. , Domestic power lithium-ion battery manufacturers mostly use aluminum shell square batteries with higher battery energy density, because the structure of square batteries is relatively simple, unlike cylindrical batteries that use high-strength stainless steel as the shell and have explosion-proof safety valves, etc. Accessories, so the overall accessories should be lighter and have a higher relative energy density. Square batteries have two different processes: winding and lamination. But because the square lithium battery 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, it is difficult to unify the process. There is no problem using square batteries in general electronic products, but for industrial equipment products that require multiple series and parallel connections, it is best to use standardized processing cylindrical lithium batteries, so that the processing technology is guaranteed, and it will be easier to find replacements in the future. battery. There is little difference between the positive electrode material, negative electrode material and separator used in the soft pack lithium battery and the traditional steel shell and aluminum shell lithium battery. The biggest difference lies in the soft packaging material (aluminum-plastic composite film) , This is the most critical and technically difficult material in the soft pack lithium battery. Flexible packaging materials are usually divided into three layers, namely outer barrier layer (usually an outer protective layer composed of nylon BOPA or PET), barrier layer (middle layer aluminum foil) and inner layer (multifunctional high barrier layer). The packaging material and structure of the soft pack battery give it a series of advantages. According to the summary of the public account of the electric zhijia, for example, the safety performance is good. The soft pack battery is packaged with aluminum-plastic film in the structure. When a safety problem occurs, the soft pack battery is generally Will swell and crack, unlike steel shell or aluminum shell batteries that explode; light weight, the weight of the soft pack battery is 40% lighter than the steel shell lithium battery of the same capacity, and 20% lighter than the aluminum shell lithium battery; internal resistance Small, the internal resistance of the soft pack battery is smaller than that of the lithium 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 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, it can be thinner, and it can be customized according to customer needs, and new battery cell models can be developed. The disadvantages of soft-pack batteries are poor consistency, high cost, and easy leakage. High cost can be dealt with by large-scale processing, and liquid leakage can be dealt with by improving the quality of aluminum plastic film. Comparison of technical characteristics 1. Battery shape: The square lithium battery can be of any size, so it is incomparable to cylindrical batteries. 2. Rate characteristics: Cylindrical lithium battery welding multi-electrode is limited by the process, so the rate characteristics are slightly worse than the square multi-electrode method. 3. Discharge platform: the same cathode material, anode material, and electrolyte are used, so theoretically the discharge platform is The same, but the internal resistance of the square battery has a slight advantage, so the discharge platform is slightly higher. 4. Product quality: Cylindrical lithium battery technology is very mature, the probability of common secondary slitting defects of the pole piece is low, and the winding process is more mature and automated than the lamination process. The lamination process is currently still using semi-manual methods. Therefore, there is an adverse effect on the quality of the battery. 5. Lug welding: cylindrical lithium battery lugs are easier to weld than square lithium batteries, and square batteries are prone to false welding that affects battery quality. 6. PACK into groups: round batteries are relatively easier to use, so the PACK method is simple and the heat dissipation effect is good. The heat dissipation problem should be handled when the square batteries are PACK. 7. Structural features: the chemical activity at the corners of the square battery is poor, and the performance of the battery is obviously degraded after long-term use. 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: How do lead-acid batteries replace the electrolyte?