Lithium ion power battery is the most potential vehicle battery at present, mainly composed of anode material, cathode material, diaphragm, electrolyte and other parts. At present, the research and development and production of anode materials have been relatively mature. Anode material, diaphragm and electrolyte are the core materials of lithium ion battery, accounting for 70% of battery cost. Among them, the anode material has the highest added value, accounting for about 30% of the cost of lithium battery. The technological breakthrough of these three core materials will play an important role in promoting the performance improvement of lithium ion power battery.
At present, lithium cobalt oxide, lithium nickelate, lithium manganese oxide, lithium cobalt nickelmanganese oxide (ternary material) and lithium iron phosphate are the main anode materials applied in lithium batteries.
Lithium cobalt oxide: research began in 1980 and entered the market in the 1990s. It belongs to a-nafe02 type layered rock salt structure, which is stable in structure. It is a very mature anode material product, and currently occupies the leading position in the anode material market of lithium battery. However, due to its high price and poor resistance to overcharging, its service life is short, and cobalt is radioactive, which is not conducive to environmental protection, so its development is limited.
Lithium nickelate: the price of lithium nickel oxide is cheaper than lithium cobalt oxide, and the theoretical energy density is up to 276mAh/g, but the production is difficult, and the safety and stability are not good. Technically, doped elements such as Co,Mn,Al and F are adopted to improve its performance. Due to many parameters and large amount of work, the progress of improving lithium nickelate technology is slow at present.
Lithium manganate: abundant manganese resources, low price, high safety, easy to prepare, become the ideal anode material for lithium ion batteries. Previously, LiMn204 with spinel structure was commonly used. It has high working voltage, but low theoretical capacity and poor compatibility with electrolytes. Materials will dissolve slowly in electrolytes. In recent years, trivalent manganese oxide LiMn204 with layered structure has been newly developed. Its theoretical capacity is 286mAh/g, and its actual capacity has reached about 200mAh/g, which is greatly improved compared with LiMn204 in both theoretical capacity and practical capacity. However, there are still structural instability in charging and discharging process, and the problem of dissolution at high working temperature.
Lithium cobalt-nickel-manganate: it is the ternary material commonly said now, which combines the advantages of lithium cobalt-nickel-manganate and lithium manganate, and has been applied in both small low-power batteries and high-power power batteries. But cobalt, one of the materials used in the battery, is a precious metal, and its price fluctuates greatly, which has a great impact on the price of lithium cobalt. The price of ternary materials is lower than that of lithium cobalt oxide when cobalt is at a high price. But when cobalt is cheap, the advantage of ternary materials over lithium cobalt oxide is greatly reduced. With the development of iron phosphate and lithium technology with better performance, ternary materials are mostly considered as the transition materials before large-scale production of lithium iron phosphate.
Lithium iron phosphate: of all the anode materials, the LiFePO4 anode lithium ion battery is theoretically the cheapest. Another feature of it is pollution free to the environment. In addition, it is the most promising current output power battery in large current discharge rate discharge (5~10C discharge), discharge voltage stability, safety, long life and other aspects are better than other kinds of materials. At present, A123 company has been able to make even nanoscale ultrafine particles of lithium iron phosphate anode material, increasing the particle and total surface area.Furthermore, the discharge power and stability of lithium iron phosphate batteries are improved.