For new energy vehicles, the durability and convenience […]
For new energy vehicles, the durability and convenience of power energy are the most critical. Nowadays, the development of power batteries is the top priority in the new energy field where electricity is the main energy source. At present, there are three major types of packaging for power batteries: cylindrical, square, and soft bags. Intuitively, they differ only in shape, but at the same time, they also have different technical development and application angles, then the battery will be different because of the shape And what is the difference? Or, which one is more advanced?
Since Sony released its first commercial lithium-ion battery in 1991, the lithium-ion battery has revolutionized the appearance of consumer electronics products, and its cylindrical design has become the most common battery shape at present. For example, alkaline batteries No. 5 and No. 7 are used. This shape design. In the following time, due to the increasing number of battery application scenarios, the square battery headed by Samsung SDI and the soft-pack battery headed by LG Huawei have also entered the market. At present, the three types of technologies are also applied in new energy vehicle products.
◆ Cylindrical battery
Cylindrical batteries can be divided into 14650, 18650, 21700 and other models, which is the name of the battery named by the size of the battery. 18650 is currently the most common battery model on the market and the most mature technology, and 21700 is the new battery that Tesla has promoted in recent years. The size of the single-cell cylindrical battery has become larger, and the amount of electricity is also greater. As a result, the number of batteries can be greatly reduced, which makes the vehicle more advantageous in controlling the battery system.
After years of development, the standardization of cylindrical batteries is relatively high, and it is easy to achieve uniform standards in the industry. In addition, the cylindrical battery also has inherent advantages in heat dissipation. When packaging, a good heat dissipation space is formed between the cylinder and the cylinder. Therefore, some vehicles equipped with the cylindrical battery adopt low-cost air cooling technology.
Tesla is vigorously promoting the 21700 battery technology. It is undeniable that the current high adoption rate of cylindrical batteries in the industry has been affected by Tesla.
For vehicles using cylindrical batteries, it is inevitable to face the battery control problems caused by a large number of battery cells. After all, even if 21700 batteries are used, thousands of cylindrical batteries need to be put together to form a battery pack. Very large. In addition, because the cylindrical battery needs to use a steel case when assembled into a battery pack, its weight is relatively high, and its energy density is insufficient compared to the other two shapes of batteries.
◆ Square battery
The plasticity of the square battery will be stronger, it can be customized according to the specific needs of the product. But this also led to the size of the square battery, and the manufacturing process standard was not as clear as the cylindrical battery. But because of its high flexibility, it has been used in early new energy vehicles for a long time. Car companies can customize the battery size according to the model, without being restricted by the cylindrical battery standard. The square battery was once considered to be the most suitable battery design for new energy automotive applications.
At present, the square battery has been applied to many models, such as BMW's i series models, Roewe ERX5, Weilai ES8, and the BMW 3 Series and 8 Series new energy models also use the square battery technology. BMW also hoped at the time As a result, the goal of lightweighting new energy vehicles is achieved.
◆ Soft pack battery
Because of the superimposed manufacturing method, the soft-pack battery has a smaller volume and a higher energy density, which is very suitable for the needs of China's new energy vehicle market. The soft pack battery can also be customized like a square battery. Especially for hybrid models, when considering the layout and weight of the vehicle, the advantages of the soft battery are more obvious. Because the soft-pack battery pursues a thinner process, it uses an aluminum-plastic film packaging that is lighter than the aluminum case. You can even feel the flow of the internal liquid battery with its thinness. The lighter battery pack can make the overall car weight lower, which also provides car companies with more layout methods. With the advancement of technology, the lighter single cells have more room for energy density.
At present, Buick's VELITE 5 / VELITE 5, Cadillac CT6 plug-in, XT5 hybrid version models, and Nissan's Xuanyi pure electric all use soft pack batteries. Generally speaking, soft-pack batteries are more favored by Korean and American car companies. Both Hyundai and GM's latest new energy models use soft-pack batteries.
◆ Which one is more advanced?
In the current new energy vehicle market, the three battery shapes of cylindrical, square, and soft packs all have a certain proportion of use, and there is no absolute good or bad, but can only be said that each has its own advantages and disadvantages.
Due to the longer development time of cylindrical batteries, the manufacturing process is more mature and the cost is lower. At the same time, there are fixed international standards to measure the quality of the products. However, in terms of battery layout and energy density, cylindrical batteries still have room for further improvement.
While square batteries and soft-pack batteries are difficult to compare with cylindrical batteries in standardization, they can be customized to enable them to better coordinate with vehicles and meet the special needs of different manufacturers and different models. Especially for soft-pack batteries, the use of aluminum film shells can improve safety while ensuring safety, but due to cost constraints, not many car companies have adopted them. Cylindrical, square, and soft-pack batteries have their own value for the market, but cylindrical ternary lithium batteries have become the current mainstream, which is also a compromise between car companies after weighing performance and cost.