Development Trend of Lithium Battery

by:CTECHi     2021-07-14

The internal components of the three types of power lithium batteries, cylindrical, square, and soft pack, are not much different. They are all lithium batteries. The core difference is that the cylindrical and square batteries mainly use metal materials as the outer shell, while the soft pack lithium battery uses aluminum-plastic film. As a package shell. The detailed analysis is as follows:

Cylindrical battery

● Suppliers: Panasonic, Sony, Johnson Controls

●Using models: all Tesla series, JAC IEV series

●Advantages: mature production technology, low PACK cost, battery products High yield rate, good heat dissipation performance

●Disadvantage: heavy weight

The cylindrical battery commonly used in new energy vehicles is long It is very similar to the AA battery that we use every day. This battery has a long history, mature production technology, and international standards. We often mention the Tesla 21700, this number actually refers to its size of 21 mm × 70 mm.

In addition, because of its own shape, when many cylindrical batteries are arranged together, they can leave a gap for heat dissipation. If the square batteries are arranged together, there is no center. Crevice.

But this kind of battery has a characteristic, the energy density of the single cell is low, if you want the same capacity, you must have more batteries, plus a metal casing must be used, resulting in a heavy weight .

Rectangular battery

●Suppliers: Samsung, CATL, Guoxuan Hi-Tech

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●Using models: BMW i3, Roewe ERX5, Weilai ES8, BYD series, GAC Trumpchi New Energy GE3

● Advantages: flexible layout, can Realization of customization and good security

● Disadvantages: the monomers are highly different, and the standards are difficult to be unified

▲The package is good Square battery

The biggest feature of square battery is that it can be customized according to different cars. To put it simply and crudely, it means that OEMs and suppliers can design a set for one car. The battery layout plan, but this in disguise increases the human capital cost of both parties; it also creates another problem. The battery of each car is different, resulting in the large number of square battery models on the market, and it is difficult to unify the process.

Think about it. If you are Party B, should you take a ready-made template and apply it easily, or should you have been discussing with your customers to make a customized version?

Soft pack battery

●Suppliers: LG Chem, Funeng Technology

●Using models: Buick VELITE5, Nissan Leaf, Chery eQ, BAIC New Energy

●Advantages: light weight, high energy density

●Disadvantages: The monomers are very different, the standards are difficult to be unified, and the mechanical strength is poor

▲Buick VELITE6 soft pack battery

Soft pack batteries are also very common in daily life, such as mobile phone batteries. It uses aluminum-plastic film as the packaging material, which is obviously lighter than the above two batteries using metal casing; but naturally, the above two methods are not as good as the battery protection.

Is the future the world of soft pack batteries?

The biggest advantage of the soft pack battery is that it can increase the energy density of the power battery on the existing technical level. According to the statistics of Gaogong Lithium Battery, the soft pack battery is 20% lighter than the aluminum shell battery of the same capacity, and the capacity is 50% higher than the aluminum shell battery of the same size.

The subsidy policy for 19 years is still unclear, but it is certain that the subsidy amount is closely related to the energy density of the battery, and the soft pack battery has a huge advantage in this regard.

The localization of aluminum-plastic film is a problem

So why do many manufacturers not use soft pack batteries? As mentioned earlier, the aluminum-plastic film is the biggest difference between the soft pack battery and the previous two batteries. After the monolithic battery is assembled, it is sealed with aluminum-plastic film to form a battery, and the aluminum-plastic film is used to protect the contents. This thing is also common in daily life, such as the outer packaging of capsules...

The main problem is that aluminum-plastic film is generally monopolized by Japanese manufacturers, and Japan’s DNP owns its own market. The rate is close to 50%, and the remaining Showa Denko can also account for about 25%. The two companies have also issued their own process standards.

Aluminum plastic film manufacturing process

Because of the process, equipment and other reasons, domestic manufacturers, certain indicators of the product are up to For those that are not below the Japanese standard, for example, the depth of drawing is about 5 mm for domestically produced ones, while Japan requires 8-12 mm.

Of course, there are also many excellent domestic suppliers who are constantly working hard, such as Xinlun Technology (acquired Japan's Tu0026T aluminum-plastic film business), and Shanghai Zijiang.

Do battery manufacturers favor soft pack batteries?

According to forecasts, the domestic soft pack power battery shipments in 2020 are expected to be 35.9MWh, with a penetration rate of 38%, which is an increase compared to the 5.5MWh shipment in 2017. About 30MWh.

Under the premise that domestic policies are highly inclined to energy density and cruising range, the high energy density and low weight of soft pack batteries are its biggest advantages, which are enough to make manufacturers and suppliers The business tends to choose it. However, the consistency of its single-cell batteries needs to be improved, and industry standards similar to cylindrical batteries need to be continuously improved. The improvement of core technology is also the key to whether the soft pack battery can become the mainstream in the future.

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