One article understands the technical challenges facing nickel-cobalt-aluminum-aluminate

As the backing of power output, the role of batteries in electric vehicles is self-evident. Because of its relatively stable performance, high safety factor, and high number of cycles that can be recharged, lithium iron phosphate batteries are the first choice for power batteries on the market, such as Chevrolet Volt, Nissan Leaf, BYD E6, and Fisker Karma. With the improvement of energy requirements, Sanyuan Lithium is gradually being loved by people. The nature of the material is the key factor in the final specific capacity of lithium batteries. By grinding, the compaction density is increased, and the properties of the material itself are improved by coating. In fact, the nature of the subject matter or the material itself determines the performance of the lithium battery.

The demand for high-energy-density lithium-ion batteries has led to the application and continuous improvement of high-capacity high-Ni ternary materials. With the hot sale of Tesla in the United States, lithium-ion companies such as Panasonic, AESC, Nissan and South Korea's LGC, SKI, and Samsung are all The material selection focuses on high-nickel multi-materials, from the conventional LiNi1/3Co1/3Mn1/3O2 (abbreviated as NCM111), gradually to high-nickel-content multi-material LiNi0.5Co0.2Mn0.3O2 (abbreviated as NCM523), LiNi0. 6Co0.2Mn0.2O (abbreviated as NCM622), LiNi0.8Co0.1Mn0.1O2 (abbreviated as NCM811) and higher nickel have 80% to 89% NCA content of NCA material. We mainly conducted research on NAC materials. Although some of the performance indicators of NCA materials are excellent, the large-scale commercialization of NCA materials is a long and arduous process. To achieve large-scale industrialization, NCA lithium-ion batteries also face many technical challenges.

1, NCA material preparation technology is more difficult

The preparation technology of Ni0.8Co0.15Al0.05(OH)2 precursor of NCA is difficult because of the large difference in precipitation pH between nickel (Co) element and aluminum element, and Al3+ is difficult to complex with ammonia. Therefore, the conventional co-precipitation method, Al3 + very easy to produce flocculent products, and Al (OH) 3 is amphoteric hydroxide, at a higher pH value and decomposed into AlO2-1, resulting in elemental distribution of nickel cobalt aluminum precipitation products Non-uniform, difficult to grow grain size, loose packing density, at the same time, sodium, sulfur and other impurities are more difficult to deal with the problem, until the subsequent use of sodium aluminate technology to solve the problem of co-precipitation of aluminum.

Second, NCA pyrometallurgical sintering preparation technology is difficult, mainly related to the nature of Ni, Ni is +3 price, the raw material for the synthesis of the +2 price, Ni2 + is difficult to oxidize to Ni3 +, need to be completely converted under pure oxygen conditions. Due to the thermodynamic instability of Ni3+, the sintering temperature of NCA cannot be too low or too high, too low Ni2+ is difficult to oxidize to Ni3+, and too high Ni3+ will decompose to Ni2+. Therefore, the optimum sintering temperature is generally 750-800°C.

2, special requirements for production equipment

Because NCA requires a pure oxygen atmosphere, the tightness of the production equipment is required to be high. At the same time, the internal components of the kiln equipment are required to have high oxidation resistance. The production of common multi-material kilns cannot meet the requirements, and domestic equipment manufacturers are suitable for high nickel. The expertise and design experience of professional kilns for cathode materials are insufficient, and quality reliability is not high.

3, high cost of material production

For ordinary ternary materials, only air atmosphere is needed in the production process, and NCA requires a pure oxygen atmosphere, the cost of pure oxygen is high, and the requirements for manufacturing oxygen production and supply equipment are extremely high. At the same time, NCA is sensitive to temperature and humidity, and needs The humidity of the production environment is controlled below 10%, which increases the cost of production and management.

4. It is difficult to design and manufacture the NCA battery

The heat stability of the high-nickel materials in the state of charge is low, resulting in a decrease in the safety of the batteries. It is necessary to carry out system-reliable safety design from the design of the batteries, the design of the power supply system, and the use of power, so that the battery manufacturing enterprises and the end product users have NCA battery safety concerns.

On the other hand, serious gas production during charge and discharge process causes the battery to bulge and deform, and the life cycle and shelf life are reduced. This poses safety hazards to the battery. Therefore, NMA cathode materials are usually used to make 18650-type cylindrical batteries to relieve the problem of battery bulging and deformation.

The surface of the NCA material is highly alkaline, the viscosity of the electrode paste is unstable, and the viscosity tends to increase or even cause jelly phenomenon, resulting in poor coating performance in the production process of the battery plate.

The NCA material is sensitive to moisture and easily absorbs moisture. Li2O in the material continuously reacts with CO2, resulting in deterioration or even failure of the material properties. Therefore, in the production process of the battery, the electrode slurry, plate, and core are very sensitive to moisture, and the entire The production environment has relatively strict humidity requirements, resulting in high equipment investment and production costs. Therefore, domestic battery manufacturers are actively developing NCA battery systems, most of which are in the phase of follow-up research and technology exploration. There is still a certain gap between the requirements of industrial applications.

NCA material faces many challenges, but it is also another major opportunity for development in China's new energy industry and electric vehicle industry. We must strengthen guidance and support for the development and application of related technologies and products, and maintain the same direction as international advanced battery technology. Synchronize and realize the dream of “turning overtaking” for new energy vehicles in China, realize the common transformation and upgrading of upstream and downstream industries, cope with the increasing energy crisis, improve urban air quality, and enable our “A PEC Blue” and “Parade Blue”. "Can be resident in China Blue."