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What is the "811" argument in the ternary lithium battery?

Date2020-9-15   On Click:525

  • Recently, in the field of new energy vehicles, the discussion on whether to abandon the NCM811 route in the Ningde era is still fermenting. Although the Ningde era has officially responded that "811 will continue to be the main attack strategy of the Ningde era in the short term", this has not yet quelled the outside debate.
    Many international organizations predict that high-nickel ternary material batteries will become the main force of power batteries in the next few years. The energy has reached the level of 300Wh/kg. In the future, as the cobalt content is reduced and the nickel content is increased, the energy density will be further increased. increase. Under the global electrification trend, the power battery industry is increasingly calling for high-nickel ternary batteries, and battery energy density, cycle life, cost control and other issues have become the core of battery manufacturers' attention.

    Is there any problem with the high nickel battery route? How to solve the battery safety problem? Who is the dominant force in the future power battery? Has become a puzzle for the outside world.

    1. Is there any problem with the high nickel route?

    The latest battery data shows that from January to July 2020, the total installed capacity of power batteries in my country is 22.5GWh. Among the four battery cell routes that are fully commercialized in the market, lithium iron phosphate, lithium cobalt oxide, lithium manganate, and ternary materials, the cumulative load of ternary batteries is 15.9GWh, accounting for 70.6% of the total load; lithium iron phosphate The battery installed capacity has accumulated 6.5GWh, accounting for 28.8% of the total installed capacity.

    It can be found that ternary material batteries have occupied an absolute share of power battery loading. What is ternary material? Take Ningde era 811 as an example, that is, a ternary lithium battery with nickel, cobalt and manganese in the cathode material and a content ratio of 8:1:1. In addition to NCM811, there are currently ternary lithium batteries represented by NCM523 (5:2:3 nickel-cobalt-manganese ratio) and NCM622 (6:2:2) on the market, both of which are the mainstream routes of battery factories.

    The difference between the above components lies in the level of nickel content. Generally speaking, nickel can increase the activity of the material, thereby increasing the energy density, which means that the greater the nickel content, the better the battery performance. In practical applications, the system energy density of models equipped with NCM811 batteries can reach more than 170Wh/kg, and the corresponding cruising range can be close to 700KM. Therefore, in the market, the battery types are subdivided according to the model level. NCM811 becomes the first choice for electric vehicles with a battery life of more than 700KM, and NCM523 supplies models with 500-700KM.

    Of course, the market space of lithium iron phosphate cannot be denied. In the current environment, lithium iron phosphate is safer, has longer battery life, and more durable models. It is easier for car companies to transfer value to consumers. Therefore, lithium iron phosphate is more suitable for urban public transportation and is also suitable for 500KM. In terms of energy storage, lithium iron phosphate is also more advantageous.

    Relevant data shows that the installed capacity of high-nickel batteries in 2019 has exceeded 3GWh. Related agencies predict that as many automobile manufacturers such as BMW, Volkswagen, and GM announce the introduction of high-nickel batteries, the market demand for high-nickel batteries will increase in the future. increase. In this context, South Korean battery company SK Innovation is ready to produce NCM 9/0.5/0.5 batteries. At the same time, Japanese and Korean battery companies such as LG, Samsung, and Panasonic are also accelerating the development and mass production of cobalt-free batteries. Among them, LG will provide GM with a 90% nickel ternary lithium battery in 2021.

    In addition to market orientation, the rising cost of cobalt in ternary materials has also pushed companies to ease cost pressures by "reducing solids and increasing nickel". Since 2017, the price of cobalt raw materials has continued to rise. At present, the domestic transaction price of cobalt sulfate and cobalt chloride is between 54,000 and 66,000 yuan/ton, and the average price of electrolytic cobalt has been as high as 674,000 yuan/ton. According to industry insiders, the cost price of a cobalt-free laminated battery is about 8%-10% lower than that of the 811 at the cell level. On the whole, there is no problem with the high nickel battery route.

    2. Battery safety is a collaborative matter of multiple parties

    Because the higher the specific gravity of nickel, the higher the energy density of the corresponding battery, and the battery life can be improved. Nickel, as one of the elements with relatively high metal activity, means that the higher the specific gravity, the worse the stability and safety of the battery. Therefore, the supporting active and passive safety solution of the 811 battery is also a huge challenge to the entire supply chain.

    From the perspective of industry professionals, high-nickel cathodes must be matched with silicon-carbon anodes with extremely high technical barriers, ceramic diaphragms, and high-voltage electrolytes to give full play to the advantages of high energy density. In an interview with reporters, Wang Binggang, head of the National New Energy Vehicle Innovation Engineering Expert Group, said: “For electric vehicles, the safety architecture of the entire vehicle must be considered, which can be avoided through sensors, electronic control systems, insulating materials, and harder shells. The heat is out of control. Nowadays, there are 4 million new energy vehicles, and the degree of market promotion proves that the battery of the ternary material is safe, and the specific cause of the fire of the electric vehicle cannot be fully proved to be the cause of the ternary material."

    The industry continues to reflect on safety issues, and the blind pursuit of high energy density has once become the target of public criticism. However, new energy vehicle safety accidents are mainly caused by thermal runaway. Thermal runaway is not only the result, but the causes are also complicated. The source of the accident is difficult to identify, and the safety issue should be highly regarded. Ouyang Minggao, an academician of the Chinese Academy of Sciences, once introduced that the safety of electric vehicle power batteries includes intrinsic safety, passive safety, and active safety. "As Wang Binggang said, the market capacity of 4 million has proved that the intrinsic safety of batteries has been gradually improved. Therefore, there is still much room for improvement in passive safety and active safety.

    How to solve the passive safety and active safety of battery packs is also a huge challenge facing the industry. As the nickel content increases, the stability of the positive electrode material decreases, and the capacity loss of cyclic charging and discharging and the capacity of high-temperature environments accelerate decay. In this regard, Wang Zidong, deputy secretary general of the China Power Battery Innovation Alliance, pointed out that the safety management of the battery pack is the key, especially during the fast charging, the difference between the batteries in the battery pack increases, and there is no complete battery group safety control and control. With thermal management technology, battery safety and long life cycle cannot be guaranteed.

    At present, reducing the thickness of the electrode, changing the battery structure, and choosing materials more suitable for fast charging are the areas of accelerated exploration in the field of power batteries. However, from a cost perspective, the above changes will increase the production cost of power batteries. At the same time, Reducing the energy density will also reduce the life of the power battery system. Therefore, the battery safety issue cannot only be discussed at the level of material selection, but also requires the strength of the integrated industry to optimize it from overall consideration. "Multi-party coordinated improvement is the foundation of the sound development of power batteries," Wang Zidong told reporters. At the same time, many people in the industry, including Ouyang Minggao, believe that artificial intelligence, big data, and cloud platforms can be introduced in active safety to improve battery management, battery early warning, battery charging control, and battery life prediction and evaluation. With the promotion of application, the accumulation of more data from OEMs and battery factories is conducive to the further improvement of safety early warning technology.

    3. High nickel ternary lithium has more room for improvement

    To be sure, the ternary material battery does improve the performance of new energy vehicles. From the initial NEDC 300KM battery life to the NEDC 650KM battery life now, the improvement effect of the ternary material battery is obvious.

    Song Jian, executive vice president of Tsinghua University Automotive Engineering Development Research Institute and deputy director of the State Key Laboratory of Automotive Safety and Energy, said in an interview: "From the perspective of materials, the current energy density of lithium iron phosphate batteries is close to its physical limit. In the long run, high-nickel ternary lithium is more suitable for long-term development."

    The reporter combed through the differences between ternary lithium and high-nickel ternary lithium, combined with the opinions of professionals, and found that the safety of power batteries can be solved by "soft means." At present, from the perspective of global battery companies and vehicle manufacturers promoting the "cobalt-free battery" research and development process, cobalt, the most unstable ternary material, can be replaced by other materials. By reducing the proportion of cobalt and increasing the nickel content, it will be able to reach 800km and 1000km in the future.

    Compared with cobalt with a collapsed structure at 130°C, lithium, manganese, and aluminum have a higher tolerance. Although to a certain extent, the industry has tended to be cautious about the use of ternary material batteries, but what remains unchanged is that high performance is always the core of electric vehicles' victory over fuel vehicles. At the same time, it should be noted that the Ningde era, as a head battery company, does not just follow the NCM811 technical route, but also revealed that the next generation will target metal-free batteries, that is, the direction of lithium batteries without nickel and cobalt.

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