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The dispute between NCM and NCA on ternary lithium batteries
The ternary lithium battery, and believes that it will become the main battery type in the field of power batteries, especially in the field of passenger cars. Compared with lithium iron phosphate batteries, it has higher specific energy and specific power, which is more suitable for passenger cars. Demand. In the past 2017, China’s ternary batteries achieved 15GWh, accounting for 44.71%. Although slightly lower than lithium iron phosphate batteries, with the development of passenger car electric vehicles, we can expect that it will soon become Absolutely first.
However, it is worth noting that the ternary lithium battery in our country is mainly NCM battery, not the NCA ternary lithium battery used on Tesla, then, What is the difference between the two and what will happen in the future? Let's take a brief look at it together. First of all, no matter NCM or NCA, both refer to the battery cathode material. NCM means the cathode material is composed of three materials of nickel, cobalt and manganese in a certain proportion, while the cathode material of NCA is composed of nickel, cobalt and aluminum. Both 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 is different, the former is manganese and the latter is aluminum.
A basic fact is that as the nickel content increases, the specific capacity of the ternary cathode material gradually increases, and the energy density of the battery cell will also increase. Therefore, in NCM batteries, according to the different contents of the three, NCM materials can be divided into NCM111, NCM523, NCM622, NCM811, etc., where the following numbers represent the ratio of the three. Under the increasing demand for cruising range, the specific energy requirement of the battery is higher, and the price of cobalt, which is a rare metal, continues to rise, the high nickel system NCM811 will become an important development direction in the future.
The common ratio of nickel, cobalt and aluminum in NCA is 8:1.5:0.5, and the content of aluminum is very small. Therefore, it can be understood that it is close to a binary material, with Al (transition Metal) instead of manganese is modified by ion doping and surface coating of lithium nickel cobalt manganate. Ion doping can enhance the stability of the material and improve the cycle performance of the material. However, in the production process, because Al is an amphoteric metal, it is not easy to precipitate, so there is a threshold in the production process of NCA materials.
Due to the high technical barriers of NCA materials, the current production capacity is mainly concentrated in Japan and South Korea, while mass production in my country is relatively small. The main suppliers are Sumitomo, Japan Chemical Industry Co., Ltd. and Toda Chemical (Toda), and South Korea’s Ecopro and GSEM also have a small number of products sold. Among them, Toda mainly supplies Japanese AESC and South Korea LGC, Sumitomo mainly supplies Panasonic and PEVE, and South Korea's Ecopro corresponds to SDI. NCA batteries have not yet been mass-produced in China. The main difficulties are: 1. The poor thermal stability of high-nickel materials under a charged state leads to a decrease in the safety of batteries, which makes battery manufacturers and end-product users more vulnerable to NCA batteries. There are concerns about safety, and it is necessary to carry out a reliable and safe design of the system from the design of the battery cell, the design of the power supply system, and the use of the power supply. 2. There is serious gas production during the charging and discharging process, which will cause the battery to swell and deform, the cycle and shelf life will be reduced, and the battery has safety hazards. Therefore, the pressure-resistant cylindrical battery shell is usually used to make the NCA battery, which reduces the gas production to control the battery swelling Deformation problem. 3. NCA requires that the humidity be controlled below 10% in the whole process of battery production, while other materials currently only need to be injected to strictly control the humidity. This poses a big challenge for domestic enterprises.
Currently, there is no public data. You can compare the energy density, safety and cost performance of NCA and NCM811 in detail. It is difficult to say which is better. 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 increase the volume on the basis of 21700, which will pose a greater challenge to battery safety management. For these reasons, the current output of China's NCA batteries is relatively small, and it is reasonable to say that the installed capacity of NCA batteries in 2017 was only 286.5MWh.
However, after consulting Tesla’s relevant information, it was found that Panasonic and Tesla recently jointly launched the 21700 NCA battery with a single energy density close to about 300Wh/kg. It is about 10% higher than the 250Wh/kg of the original 18650 battery, which is almost the highest energy density mass-produced lithium-ion battery in the world. This figure is far higher than the energy density level of the NCM523 battery cell with the highest utilization rate in China, which is 200Wh/kg, and is also significantly higher than the energy density level of the NCM811 battery that has just appeared and is the most advanced in the country, that is, the cell is up to 250Wh/kg. The maximum system level is 200Wh/kg. Therefore, it is still necessary to research and develop NCA batteries. Fortunately, most of the domestic battery companies have already taken action in this regard, just to see when they can break through the technical barriers and form mass production capabilities. Both NCM and NCA are high-nickel ternary lithium batteries. The biggest advantage is that they have high specific energy and can provide more sufficient power for vehicles. If, but in terms of energy demand, NCA batteries seem to have more advantages, but considering the manufacturing process, cost, and current technical conditions, Chinese battery companies are currently mainly focused on producing NCM. However, almost all large-scale battery companies are actively researching and developing NCA. It can be expected that China will be able to break through the technical barriers of Japan and South Korea in the future and mass produce NCA batteries on a large scale. NCM and NCA batteries will simultaneously become the main framework of ternary lithium batteries.