NCM and NCA route dispute

We introduced the ternary lithium battery in the previous article and thought it would become the main battery type in the power battery, especially in the passenger car field. Compared with the lithium iron phosphate battery, it has higher specific energy and ratio, power, more in line with the needs of passenger cars. In the past 2017, China's ternary battery achieved 15GWh, accounting for 44.71%, although slightly lower than lithium iron phosphate battery, but with the power of passenger car electric car, we can expect it to become soon absolutely the first.

However, it is worth noting that our country's ternary lithium battery is mainly NCM battery, not the NCA ternary lithium battery used on Tesla. So, what is the difference between the two, the future development is How will we come together to understand.

First of all, NCM or NCA refers to the positive electrode material of the battery. NCM means that the positive electrode material is composed of three materials of nickel, cobalt and manganese, and the positive electrode material of NCA is composed of nickel, cobalt and aluminum. They are the chemical initials of related elements. It can be seen that the first two of the two ternary materials are the same, both nickel and cobalt, only the last one being different, the former being manganese and the latter being aluminum.

A basic fact is that as the content of nickel increases, the specific capacity of the ternary cathode material gradually increases, and the energy density of the cell increases. Therefore, in the NCM battery, according to the content of the three, the NCM material can be divided into NCM111, NCM523, NCM622, NCM811, etc., wherein the latter numbers represent the ratio of the three. Under the demand for more and more cruising range, the specific energy of the battery needs to be higher. Together with the rising price of cobalt as a rare metal, the NCM811 of the high nickel system will become an important development direction in the future.

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The common ratio of nickel-cobalt-aluminum in NCA is 8:1.5:0.5 and the content of aluminum are very small. Therefore, it can be understood that it is close to binary material, and Al (transition metal) is substituted for manganese, and lithium nickel cobalt manganese oxide is passed through the ion. Doping and surface coating are modified, and ion doping can enhance the stability of the material and improve the cycle performance of the material. However, in the production process, since Al is an amphoteric metal and is not easily precipitated, there is a threshold for the NCA material fabrication process.

Due to the high technical barriers of NCA materials, the current production capacity is mainly concentrated in Japan and South Korea, and China's mass production is relatively small. Major suppliers include Sumitomo, Japan Chemical Industry Co., Ltd. and Toda Chemical (Toda), and Korea's Ecopro and GSEM also sell a small number of products. Among them, Toda mainly supplies Japan AESC and South Korea LGC, Sumitomo mainly supplies Panasonic and PEVE, and Korea's Ecopro corresponding customer is SDI.

NCA batteries have not been mass-produced in China. The main difficulties are:

1. The thermal stability of the high-nickel material under the state of charge is poor, resulting in a decrease in the safety of the battery, which makes the battery manufacturer and the end product users have concerns about the safety of the NCA battery, and needs to design from the battery core and the power system. And the use of power supply and other aspects of the system for reliable security design.

Second, there is serious gas production during the charging and discharging process, which will cause the battery to bulge and deform, the cycle and the shelf life are reduced, and the battery has potential safety hazards. Therefore, the NCA battery is usually made of a pressure-resistant cylindrical battery case, which reduces the gas production to control the battery bulging, deformation problem.

Third, NCA requires that the humidity should be controlled below 10% in the whole process of battery production, while other materials currently only require strict control of humidity during the liquid injection process. This poses a great challenge to domestic companies.

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There is no published data yet, and the energy density, safety and cost performance of NCA and NCM811 can be compared in detail. It is difficult to say that it is better or worse. However, some experts pointed out that NCA and NCM811 are relatively close in performance, but NCM811 is slightly cheaper in price. Moreover, the NCA system battery is not perfect. If you want to further increase the energy density, you need to continue to make a large volume based on the 21700, which will pose greater challenges to battery safety management. For these reasons, the current production of NCA batteries in China is relatively small, and it is reasonable. In 2017, the loading of NCA batteries was only 286.5MWh.

However, the author consulted the relevant information of Tesla and found that Panasonic recently launched a 21700 NCA battery jointly with Tesla. The energy density of the monomer is close to 300Wh/kg, which is about 10% higher than the 250Wh/kg of the original 18650 battery. It is almost the world's highest energy density lithium-ion battery. This figure is far higher than the energy density level of 200Wh/kg of the NCM523 battery cell with the highest domestic usage rate, and it is also significantly higher than the energy density level of the NCM811 battery which is just emerging and leading in China, that is, the highest monomer is 250Wh/kg. The system has a maximum level of 200Wh/kg. Therefore, for NCA batteries, it is still necessary to develop. Fortunately, most domestic battery companies have already taken action in this regard, just to see when they can break through technical barriers and form mass production capabilities.

The page contains the contents of the machine translation.