What are the technical levels and characteristics of ternary material batteries?

Compared with traditional fuel vehicles, new energy vehicles have problems such as range, charging time, safety performance, battery life, and battery cost, which are key factors restricting consumer purchasing power and the popularity of new energy vehicles. There are six main points of correspondence between power battery technology performance and new energy vehicle performance:

1. Energy density: The higher the energy density, the longer the range of new energy vehicles;

2. Power density: The higher the power density, the better the acceleration and climbing performance of new energy vehicles;

3. High and low temperature performance: the wider the application range of high and low temperatures, the wider the applicable temperature range of new energy vehicles;

4. Cycle life: The longer the cycle life, the longer the service life of the power battery of new energy vehicles;

5. Safety performance - the decisive factor for the safety of new energy vehicles;

6. Rate performance: The shorter the charging time, the better the vehicle's power performance.

The performance of power batteries directly determines the performance of new energy vehicles. The improvement of power battery performance depends on technological progress. Continuous technological progress drives the continuous improvement of power battery energy density, continuous optimization of product performance, continuous reduction of production costs, and continuous improvement of overall cost performance.

The competent departments of various governments have urged the power battery industry to accelerate technological progress and industrial upgrading by formulating industry development technology roadmaps and new energy vehicle subsidy policies.

Power batteries with high energy density and excellent safety performance are the direction that governments and leading battery manufacturers are competing to develop and focus on. In 2009, the Japanese government proposed the research and development goal of "by 2020, the energy density of power battery cells for pure electric vehicles will reach 250Wh/kg, and by 2030 it will reach 500Wh/kg"; in 2015, the American Advanced Battery Alliance proposed "to appease consumers' anxiety about the mileage of electric vehicles, the energy density of battery cells will be increased from the original 220Wh/kg to 350Wh/kg in 2020, and the system energy density will reach 235Wh/kg." According to the "Automobile Technology and Engineering Standards" issued by China in 2017,

According to the "Medium- and Long-Term Development Plan for the Automobile Industry", by 2020, the annual production and sales of new energy vehicles will reach 2 million, the energy density of power battery cells will reach more than 300Wh/kg, and strive to achieve 350Wh/kg, the system energy density will strive to reach 260Wh/kg, and the cost will be reduced to less than 1 yuan/Wh; by 2025, new energy vehicles will account for more than 20% of automobile production and sales, and the energy density of power battery systems will reach 350Wh/kg.

The key to improving energy density lies in the positive electrode material. The positive electrode material determines the main performance of lithium-ion batteries . According to the positive electrode material, lithium-ion batteries can be divided into technical routes such as lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate and ternary materials. Among them, ternary materials refer to positive electrode materials containing three elements of nickel, cobalt and manganese or three elements of nickel, cobalt and aluminum, namely lithium nickel cobalt manganese oxide (hereinafter referred to as "NCM") or lithium nickel cobalt aluminum oxide (hereinafter referred to as "NCA"). In the field of power batteries, it has experienced a development process from lithium cobalt oxide and lithium manganese oxide to lithium iron phosphate and ternary materials.

Image source: Farasis Energy's prospectus

Limited by the energy density bottleneck of lithium iron phosphate batteries (especially the low volume energy density, which makes it difficult to apply to passenger cars with limited space), in order to achieve goals such as high energy density of power batteries, long driving range of new energy vehicles and low configuration cost, ternary materials have become one of the mainstream technological development routes in the power battery industry, especially in the field of new energy passenger cars and special-purpose vehicles with higher performance requirements.

According to the different contents of nickel, cobalt and manganese in the ternary material, NCM material can be divided into NCM523, NCM622, NCM811, etc. NCM523 refers to the chemical composition of the ternary material Li (Ni0.5Co0.2Mn0.3) O2. NCA replaces the manganese element with aluminum. The technical advantage of ternary materials lies in the combination of the advantages of LiCoO2, LiNiO2, LiMnO2 or LiAlO2, so that Ni, Co, Mn or Al can play a synergistic effect. The main function of Ni is to increase the energy density; the main function of Co is to stabilize the layered structure of the ternary material, improve the electronic conductivity of the material and improve the cycle performance; the main function of Mn is to reduce costs and improve the structural stability and safety of the material. Different element ratios can obtain different electrode characteristics.

Image source: Farasis Energy's prospectus

Taking into account the progress of technology, manufacturing process and other factors, NCM523 is the most widely used ternary material at present. Domestic and foreign power battery companies are accelerating the development of ternary power battery products with high nickel positive electrode materials such as NCM811 or NCA.

There are certain barriers to the research and development and industrialization of high-nickel ternary material batteries. From a technical perspective, as the proportion of nickel increases, the mixing effect of nickel ions and lithium ions becomes more obvious, and it is necessary to solve the problems of reduced cycle life and poor thermal stability caused by the mixing effect through the overall formula design of battery materials. From an industrial production perspective, high-nickel ternary materials are extremely demanding in terms of precursor sintering and material production environment requirements, and it is extremely difficult to release effective production capacity, and the requirements for power battery production links are also higher. In addition, with the increase of nickel elements, the positive electrode material is more active, which has a greater impact on the safety of power batteries. Therefore, the introduction of high-nickel ternary materials requires higher technical strength and process manufacturing capabilities of power battery companies.