Detailed explanation of the difference between cylindrical ternary lithium battery and square ternary lithium battery

The energy density ratio refers to the capacity of the battery per unit weight. Cylindrical monomers are calculated according to the current domestic mainstream 18650 (1.75AH), and the energy density ratio can reach 215WH/Kg, and the square monomers can reach 205WH/Kg according to 50AH. The system group rate is around 60% for 18650, and the square is around 70%. (The system grouping rate can imagine putting ham in the box. The gap between the square hams is smaller, so the system grouping rate is higher.) In this way, the energy density ratio of the 18650 battery pack system is about 129WH/Kg, and the square battery pack system The energy density ratio is about 143WH/Kg. When the energy density ratio of 18650 and square cells reaches the same in the future, square lithium battery packs with a higher grouping rate will have more distinct advantages. Rate of charge and discharge rate u003d charge and discharge current / rated capacity, the higher the rate, the faster the charging speed supported by the battery. The domestically manufactured mainstream horizontal energy cell 18650 is about 1C, and the square can reach about 1.5-2C (the thermal management needs to be solved), and there is still some distance from the policy goal of 3C. However, it is entirely possible that the square manufacturing process will become more and more perfect to achieve the established target 3C. The cycle life is 2000 times when 1C is charged and 1C is discharged. The remaining capacity of the best square cell can still reach 80%, while the capacity of the best 18650 cell is only 70%. It can be seen that the cycle life of the square battery is better than that of the 18650 battery. Consistency The consistency of cells is the biggest headache for cell companies. For our users, the more cells there are, the more difficult it is to control consistency. Assuming that the defective rate of a battery cell is one in 100,000, the round battery pack consists of 7000 18650 cells, the square battery pack consists of 250 cells, and a battery pack without defective products is deemed qualified. Then the pass rate of the round cell battery pack is 0.99999^7000u003d93.2%, and the pass rate of the square cell battery pack is 0.99999^245u003d99.7%. Of course, the theoretical knowledge about battery consistency is much more complicated than this. Here, Pike just gives an example to illustrate that using a battery pack with a larger cell capacity and a smaller number of square cells is more conducive to control consistency. Manufacturing cost The manufacturing cost contains material cost, equipment cost, artificial hydroelectric field cost and hidden auxiliary material cost. At present, the comprehensive cost of 18650 of mainstream companies can be controlled at about 0.5 yuan/WH, and the comprehensive cost of square is about 0.8 yuan/WH. Before the rise of the new energy automobile industry, 18650 batteries have been widely used in various fields such as electronic products and industrial equipment. However, the single capacity of the 18650 battery cell is relatively low, which is not enough to meet the requirements of electric vehicles, so Tesla has developed the 21700 model. At present, the high degree of equipment automation is where the cylinder company can most save labor costs, but the production and sales chain of the cylinder has been very mature, and the compressed space is almost gone. There is still a lot of room for improvement in the size and electrode thickness of the square cells. In terms of size, it is getting bigger and bigger. From the initial 20AH to the current 50AH batch products are now on the market. The larger the capacity, the lower the cost of WH, so Paike believes that it is entirely possible that the cost will be flat when the large-capacity square is mass-produced. 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: What are the development directions of special binders for lithium batteries?