Soft case, cylindrical, square lithium battery which is best

Today we are going to talk about the shape of the battery. According to different packaging forms, lithium batteries are divided into cylindrical batteries, square batteries and soft pack batteries. Then there is the division of different models, such as 18650 lithium batteries, 26650 lithium batteries, etc. Different structures also mean that they have different characteristics. Today, let us take a look at the advantages and disadvantages of the three types of batteries.

Cylindrical battery: long development time and the most mature technology

The development time of cylindrical batteries is the longest, and the technology is also the most mature, with a high degree of standardization. Moreover, because the cylindrical battery has a large space between the cells when it is packaged, this type of battery has a great advantage in heat dissipation. Many models equipped with cylindrical batteries have adopted lower-cost air-cooling technology.

However, the excessive number of batteries is a tricky problem. Even in vehicles with high energy density batteries, thousands of cylindrical batteries need to be put together, which also puts forward higher requirements for the vehicle battery management system. In addition, because the cylindrical battery needs to use a steel shell when assembled into a battery pack, its weight is relatively high. Theoretically, the energy density of the cylindrical battery is lower than that of the other two batteries.

At present, many models on the market use this type of battery. The most representative one is Tesla’s model 3, which uses a model of 21700 (where 21 means the diameter of the cylindrical battery is 21mm, and 70 means the battery length is 70mm, 0 means that its type is cylindrical battery)

Square battery: simple structure and light weight

The popularity of prismatic batteries in China is very high. Because the structure of prismatic batteries is relatively simple, the production process is not complicated, and because prismatic batteries do not use high-strength stainless steel as the shell like cylindrical batteries, the energy density of prismatic batteries is theoretically The energy density is higher than that of cylindrical batteries. However, because prismatic batteries are generally designed for customization, the production process of prismatic batteries is difficult to be unified, and the degree of standardization is low. Currently, Weilai's ES6, ES8, Emgrand EV and other models all use square batteries.

Soft pack battery: high energy density, better battery layout flexibility

      The soft pack battery uses a superimposed manufacturing method, which is thinner than the other two types of batteries in volume, so its energy density is theoretically the highest of the three batteries. And because of the small size of the soft pack battery, there should be quite a lot of batteries like some digital products, and they are not limited by size. So its flexibility in battery layout is better than the other two types of batteries.

to sum up

In the current new energy vehicle market, the cylindrical, square, and soft pack batteries are all equipped with models, and there is no absolute difference between good and bad, it can only be said that each has its own advantages. In terms of cell energy density, in theory, the soft pack battery is the highest, followed by the square battery, and the cylindrical battery is the smallest.