The anode electrode of a lithium-ion battery is made by mixing a negative electrode active material carbon material or a non-carbon material, a binder and an additive, and pasting the paste on both sides of a copper foil, and drying and rolling.
The anode material is one of the key factors determining the performance of lithium-ion batteries, and it holds the safety lifeline of power batteries. The anode materials currently used in commercial lithium-ion batteries mainly include: ①graphite carbon materials, divided into natural graphite and artificial graphite; ② disordered carbon materials, including hard carbon, soft carbon, etc .; ③ lithium titanate materials; ④ silicon-based Materials are mainly divided into carbon-coated silicon oxide composite materials, nano-silicon-carbon composite materials, and amorphous silicon alloys.
According to the survey data of the Lithium Power Research Institute of Industrial and Industrial Research, in 2017, China ’s lithium battery anode material output was 146,000 tons, an increase of 23.7% compared with last year. In addition, the output value of China's negative electrode market increased by 28.5% year-on-year to 8.3 billion yuan, a higher growth rate than the same period, mainly due to the increase in needle coke prices and the increase in graphitization processing costs.
In lithium-ion battery anode materials, in addition to graphitized mesocarbon microspheres (MCMB), amorphous carbon, silicon or tin, which occupy a small portion of the market share, natural graphite and artificial graphite occupy more than 90% of the anode material market share . Natural graphite has the advantages of large reserves, low cost, mature supporting technology and equipment, and safety and non-toxicity. Its shortcomings such as low initial coulomb efficiency and poor rate performance can be solved by spheroidizing particles and surface coating technology. Meet the requirements of consumer electronics for small battery performance. In addition to similar advantages compared with natural graphite, artificial graphite has smaller graphite grains, a lower degree of graphitization, and a smaller degree of crystal orientation, so it is superior to natural graphite in terms of rate performance, volume expansion, and prevention of electrode rebound.
In 2017, the shipment of artificial graphite increased strongly, reaching 102,000 tons, an increase of 30% year-on-year, accounting for nearly 70% of all anode material shipments, followed by natural graphite, accounting for 25%. The main reason is that artificial graphite accounts for more than 90% of the negative battery materials used in new energy vehicles, which has greatly boosted their demand. In addition, the proportion of high-end digital products has continued to increase. For lithium batteries, large-rate charge and discharge, cycle performance, and safety Performance requirements are gradually increasing, so the market uses artificial graphite instead of natural graphite.
At the same time as graphite-based anode materials dominate, new materials such as lithium titanate materials and silicon-based materials are also constantly developing, and are considered to be an important direction for the development of anode materials for lithium-ion batteries in the future. The silicon-based materials developed in China in recent years can basically meet the requirements of high specific capacity, high power characteristics and long cycle life, but industrialization must also break through technological, cost and environmental constraints.
Lithium battery anode material market overview
Globally, the anode material industry is mainly concentrated in Japan and China. The two countries have a global market share of more than 95%, with high concentration and low product substitution risks. Hitachi Chemicals in Japan and Bateri in China are leading companies in the two countries, and their global market share is close to 50% (2015). Bertrand's customer base includes Samsung, LG, Panasonic, BYD, Tianjin Lishen, Hefei Guoxuan, Coslight Power and many other well-known domestic and foreign enterprises. Its products are also used in many products such as electronic products and power batteries. As the growth rate of the consumer electronics market slows, the growth of the natural graphite and artificial graphite markets will gradually slow down, but the proportion of high-magnification and high-capacity products will gradually increase.
In addition, lithium-ion battery anode materials show diversity, and silicon-carbon (Si-C) composite materials have become a new trend. With the advancement of technology, the anode materials for lithium-ion batteries have developed from single artificial graphite to natural graphite, mesocarbon microspheres, artificial graphite, soft carbon, hard carbon, amorphous carbon, lithium titanate, silicon carbon alloy, etc. Coexistence of multiple negative electrode materials. Natural graphite anode materials have made great progress in technology, with a reversible capacity of more than 360mAh / g, and have been widely used in consumer lithium-ion batteries. It is expected that in the future of small batteries, high-capacity batteries will still be dominated by natural graphite; artificial graphite anode materials are currently widely used, which has the advantage of long life and the disadvantage of relatively low capacity. Current improvements in artificial graphite technology make artificial graphite reversible The capacity is up to 350mAh / g. The composite of artificial graphite and natural graphite has been recognized by many battery manufacturers as a negative electrode material for lithium ion batteries. In terms of consumer electronics, the energy density of batteries needs to be improved. New high-capacity anode materials represented by silicon-carbon (Si-C) composite materials are the future development trend. In terms of power batteries, lithium titanate materials are the new development direction. . At present, the annual shipments of non-carbon materials such as lithium titanate and silicon-based materials account for less than 1% (2016). With the continuous development of manufacturing processes and modification processes, these non-carbon anodes have greater potential Materials will gradually be used more widely.