Silicon-carbon anodes, which have high hopes, seem to be hindered in terms
of application. According to industry insiders, currently only BAK, Lishen, and
Penghui have small batch samples, and they are all used in cylindrical
batteries. There are still many problems that cannot be solved on the
application side of square aluminum shells and soft bags.
The application is blocked
According to research, since the second half of last year, a small amount
of lithium batteries using silicon-carbon anodes have been pushed into the
high-end digital market. But when it comes to power batteries, large-scale
applications seem to be just around the corner.
Industry insiders said that the popularity of silicon-carbon anode
materials has been greatly improved, but it has never been able to be loaded
into cars in large quantities. There are two reasons. First, during the mass
production process of batteries, there are still problems such as rapid capacity
attenuation, easy deformation of batteries, and insufficient cycle times. There
are not many truly good silicon carbon anode products and well-used battery
manufacturers; Second, the cost performance is not high. When the battery
capacity is increased by 5%-10%, the cost of the battery will increase by
20%-30% or even higher. High-nickel ternary + silicon-carbon composite materials
have always been considered a golden match, but separators and electrolytes all
have problems that require one-to-one matching, and it is still difficult to
find matching electrolytes.
A deputy chief engineer of a major negative electrode materials
manufacturer said that not only are there problems on the application side, but
they also have problems with mass production of negative electrodes. The size of
silicon particles in silicon-carbon composite materials cannot exceed 200-300nm,
and the technical barriers to key indicators such as its surface, particle size
distribution, impurities, and surface passivation thickness are also very high.
Currently, many domestic manufacturers cannot reach it. The cost of purchasing
nano silicon powder is too high.
"The energy density of the battery systems currently used in vehicles is
not very high. Generally, the energy density of a single unit is between
210-260Wh/kg, and the system specific energy is between 140-165Wh/kg." Ma Xin,
chairman of Jiangsu Taixing Zhongxin Energy The doctor said that the current
gram capacity of good artificial graphite anode materials is close to the
theoretical 372mAh/g. In a period when battery prices are relatively sensitive,
this technical indicator can reach 260wh/kg. But when we make batteries, we have
maximized the cathode capacity. Our extensive experiments in mass-producing
300wh/kg batteries have proven that only good silicon-carbon negative electrodes
can be used to make 300wh/kg power batteries. Therefore, current battery
manufacturers use technology comparison Simple graphite anodes have only
temporarily bypassed the research on silicon-carbon anode batteries. However, as
subsidies put forward higher requirements for energy density, battery factories
must use silicon carbon anode materials.
At present, some anode material manufacturers are still committed to
improving the performance of artificial graphite anode materials. After all, the
first efficiency has been increased to 95% or even 97%. For anode material
manufacturers, there is still a lot of room for improvement. Xu Junhong, general
manager of Luoyang Yuexing, said that the company is increasing the gram
capacity by adding nanopores to the coating layer.
The irreversible trend of silicon carbon
The 2018 semi-annual report of Shanshan Co., Ltd. (600884) mentioned that
from the perspective of product trends, as the energy density requirements of
power batteries increase, silicon-carbon anodes will be the focus of future
development. Although the actual growth of silicon-carbon anodes in the first
half of 2018 Shipments are very limited, but the trend of the silicon-carbon
anode route is already very clear.
In addition to Shanshan Co., Ltd., Jiangxi Zichen, Shenzhen Beterui, etc.
have already laid out the production of silicon carbon anode materials.
Currently, they have launched several silicon carbon anode materials and have a
certain production capacity. CATL, BYD, Guoxuan Hi-Tech, Lishen The industrial
application of silicon carbon anodes by leading companies such as , BAK,
Wanxiang A123, and Micromacro Power is also advancing.
Starting Point Research (SPIR) believes that some large-scale anode
material companies in China have begun to deploy silicon-carbon materials.
Battery companies are also affected by the policy push for battery energy
density and have begun large-scale research and development of high-capacity
silicon-carbon material batteries. With the new domestic As the number of
companies entering silicon-carbon materials increases and scale is formed, their
prices will inevitably fall. In summary, it is expected that silicon-carbon
materials will become a new generation of leading anode materials for
high-capacity batteries in the next two to three years.
In fact, domestic companies have been relatively slow in industrializing
silicon-carbon anodes. Panasonic mass-produced NCR18650C batteries using
silicon-carbon anode materials as early as 2013. Tesla has successfully applied
silicon-carbon anodes to Model 3; GS Yuasa has also launched silicon-based anode
material lithium batteries, which have been used in Mitsubishi On the car.
Foreign media have also reported that Panasonic, as Tesla's sole battery
supplier, is considering cooperating with Tesla to build a super battery factory
in China. Although the final news has not been confirmed, Tesla has signed an
investment agreement for a pure electric vehicle project on July 10, and the
super factory will be located in the Lingang area of Shanghai.
At present, taking cylindrical batteries as an example, domestic 18650
cylindrical batteries are generally 2.6Ah. Samsung and LG can produce 2.8Ah and
2.9Ah respectively, but their production capacity is very large, they have
always been low-priced and their products are consistent. It is much better than
domestic products, and we do not rule out the possibility that they can seize
the market at low prices. In fact, the biggest pressure comes from Panasonic.
Their current mass-produced products have reached 4.0Ah. Once they enter the
Chinese market, the threat to domestic companies will be fatal. At present, only
BAK in the industry has released a 3.0Ah high-energy battery and installed it on
Leap cars.
"We have solved the problems of battery deformation and low cycle life."
Dr. Ma Xin said that the 18650 battery factory with 3.2Ah high nickel + silicon
carbon anode is being tested, and the 4.93Ah class mass production battery cell
sample has also been completed.
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