Currently, the market for anode materials largely consists of a mix of natural and synthetic graphite, which increases both battery capacity and cycle life, according to a professional with many years of experience in the lithium-ion battery anode material field. It is understood that initially, only MCMB (mesophase carbon microspheres) were commercially available as anode materials, followed by the widespread use of synthetic graphite. While natural graphite was also available at that time, many manufacturers did not utilize it effectively. With continuous advancements in battery technology and electrolyte technology, natural graphite, due to its lower price, is increasingly being used in various types of lithium-ion batteries.
In commercial applications, graphite-based carbon materials are relatively mature in technology and have relatively stable market prices. However, due to the increasing demands on energy density, power density, and safety performance of lithium-ion power batteries, high-capacity, high-safety, stable, and low-cost anode materials have become a hot topic of research and discussion.
Qiao Yongmin, R&D Director of Shanghai Shanshan Technology Co., Ltd., pointed out that the anode materials for power lithium-ion batteries have not yet formed their own system, and manufacturers have different choices.
A blend of artificial and natural graphite
"In China, artificial graphite was the first material used, but in recent years, natural graphite has started to be used instead. Currently, the domestic shipment volume of natural graphite is still very high," said Wang Zheng, director of the Advanced Materials Division of Shenzhen BTR.
He believes that artificial graphite has relatively better cycle performance, but natural graphite, if made well, will also have good cycle performance. BTR mainly exports, and Samsung uses BTR's natural graphite, which has a very high cost-performance ratio. The key is the matching with the electrolyte.
Generally speaking, natural graphite has high capacity, high compaction, good processing performance, and low cost, but poor safety, poor cycle performance, and is more selective in its choice of electrolyte. However, because it can improve the capacity of the positive electrode and reduce the relative cost, it is widely used in small batteries and mobile phone batteries. Artificial graphite has lower capacity, lower compaction, difficult-to-control processing performance, and high cost, but good cycle and rate performance and is not selective in its choice of electrolyte. It is generally used in high-capacity and high-rate batteries.
Reporters learned that as most manufacturers are now pursuing higher energy density, the requirements for the compaction density of the anode materials are also increasing. However, pure natural graphite has a large cyclic expansion, consumes a lot of electrolyte, has poor liquid absorption under high compaction, and poor rate performance, so there are not many that can be used in high-capacity systems.
The stability and cycle life of natural graphite products depend on the production and processing procedures and technology control of each factory. A negative electrode material technology R&D personnel told reporters that the reason why Japan can also make batteries with good capacity and performance using natural graphite is that they buy graphite powder supplied by domestic manufacturers, process it further, and then use it or resell it back to the domestic market at a high price. At present, China's technology level is not yet good at using natural graphite.
He also pointed out that because domestic battery companies still lack technology, the domestic market currently mainly uses a mixture of natural and artificial graphite, which reduces costs and also lowers the difficulty of battery manufacturing.
Many mobile phone battery manufacturers are now mixing artificial graphite in certain proportions to compensate for the shortcomings of natural graphite. For example, aluminum-cased batteries use high-end natural graphite mixed with a small amount of low-end artificial graphite, which has shown good results in improving cycle life and reducing costs. Ms. Xu, a business manager at a negative electrode material factory in Qingdao, pointed out that as customers' requirements for various performance aspects increase, high-end artificial graphite will be widely used in mobile phone batteries.
Huang Yuehua, deputy general manager of Changsha Xingcheng, also stated that the domestic market currently mainly uses artificial graphite, while natural graphite has limited raw materials and a simple manufacturing process, with a maximum capacity of only 370mAh/g, while artificial graphite can currently achieve more than 400mAh/g.
He believes that the use of artificial graphite will increasingly surpass that of natural graphite in the next two years.
Selection of high-rate anode materials
With the development of power lithium-ion batteries in recent years, and people's pursuit of fast charging and high-rate charging performance, high-rate electrode materials have received increasing attention.
BTR's natural graphite is primarily used in consumer batteries, while Changsha Xingcheng's artificial graphite is mainly targeted at the power lithium-ion battery market. In 2011, the company's power anode materials accounted for 40% of its business. Huang Yuehua stated that natural graphite is limited by raw material availability, while artificial graphite has a wider range of raw material sources.
In response, Wang Zheng believes that the main raw material for artificial graphite is petroleum coke, which has an unstable source and therefore poor batch-to-batch consistency. Natural graphite, on the other hand, uses raw materials derived from graphite mines, resulting in excellent consistency.
Japan also primarily uses natural graphite, and BTR accounts for about 30% of the entire anode material market in China, most of which is natural graphite.
Although artificial graphite was used earlier in China, the core technologies are still monopolized by Japanese manufacturers. "In the long run, I believe natural graphite is the trend," a negative electrode material technician told reporters.
He stated that Japan has already used natural graphite in its power lithium-ion batteries, which involves coating the surface of natural graphite with a layer of conductive carbon black to address issues related to liquid absorption and crystal orientation. However, this slightly affects capacity and initial efficiency. Domestically, some researchers have also coated natural graphite with hard carbon, but the results are not uniform, and batch-to-batch stability is poor, hindering widespread adoption.
Furthermore, lithium titanate, with its excellent safety, cycle life, and high-rate charge/discharge performance, has become one of the best choices for anode materials in power lithium-ion batteries. Qiao Yongmin believes that lithium titanate has a certain demand potential in hybrid vehicles and energy storage. However, due to its high voltage platform, difficulties in solving problems such as gas expansion, insufficient technology from domestic manufacturers, and high price, it is currently not feasible for mass production. From a cost perspective, soft carbon and natural graphite may be the future application trend; however, the reality is that high-temperature performance remains a challenge, making the practical application of soft carbon and hard carbon currently difficult.
Industry insiders say that soft carbon has no advantage when used alone, but it can make up for its shortcomings when mixed with graphite. It can be used in power lithium-ion batteries or energy storage. For example, soft carbon in Japan is basically mixed with artificial graphite and is currently being promoted.
Fueled by the new energy concept, investment in the lithium battery industry is heating up, and the establishment of factories in China by Japanese anode material giants has further intensified competition. DangSheng Technology (300073.SZ), which holds a 40% stake in Changsha Xingcheng, disclosed that Changsha Xingcheng's performance in the first quarter of this year was not ideal.
Huang Yuehua said that the economic environment was not good in 2011, and the company's revenue was 20 million. It has improved slightly in the last month or two. In recent years, there have been more and more small companies producing anode materials.
Regarding the impact of Japanese anode material giants building factories in China on the domestic anode material industry, Wang Zheng believes that this is not necessarily a bad thing for BTR, given its advantages in the industrial chain. In his view, competition in the anode material market ultimately depends on technology; those with technological advantages naturally have the confidence to face competition.
