Image source @ Visual China
Text | Core lithium words, the author | Lin Xiaochen
At the "Tesla Battery Day" held in September 2020, Tesla subversively released the "4680 Battery".
This kind of battery is not only significantly larger than the 18650 and 21700 batteries in size, but also has a higher energy density, the energy of the single cell is increased by 5 times, and the output power is increased by 6 times, which is expected to reduce the price of power batteries by more than 56%.
The application scenario of electric vehicles is more special, the space capacity is extremely limited, in order to ensure sufficient mileage, it puts forward certain requirements for the energy density of power batteries, which is also the key to restricting the development of the industry. The core of tesla's 4680 battery's significantly improved efficiency lies in three aspects: electrodeless ear mode, dry electrode process, and silicon-based negative electrode application.
The electrodeless ear mode complements the dry electrode process, and its core purpose is to reduce the internal resistance of the conductive path, from the previous 20mΩ to 2mΩ; on the other hand, the application of the silicon-based anode is expected to break through the theoretical capacity limit of the traditional negative electrode and achieve a comprehensive breakthrough in the energy density of the power battery.
All along, the negative pole of the power battery has been calm, the advantage of cost performance makes graphite become a recognized technical route in the industry, in the absence of new driving force, the negative pole companies will focus on the development of cost reduction and efficiency.
But this calm may be broken by the 4680 battery, when the 4680 battery is officially released, the penetration rate of the silicon-based negative electrode will continue to increase. Will the 4680 battery discharge be the beginning of the next industrial iteration of the lithium battery anode? What are the reasons that restrict the silicon-based anode replacement of artificial graphite to become the mainstream of the industry?
01 An iterative history of the negative electrode
The concept of lithium batteries was first proposed in the early 20th century, but it was not until 1991 that Sony of Japan officially realized commercial production.
The earliest batch of lithium batteries used petcoke anodes, which were quickly phased out due to their low specific capacity and replaced by a material called intermediate phase carbon microspheres (MCMB).
Although MCMB has been significantly improved compared with the first generation of negative electrode materials, there is still a problem of low specific capacity, coupled with the need to consume a large amount of organic solvents in the preparation process, so the cost remains high, almost several times more than the current negative electrode materials.
Lithium batteries were born in Japan, the early stage of industry development of Japanese companies have always occupied the absolute right to speak, before 2000, the mainland lithium battery enterprises almost all of the anode materials from Japan imports.
The first to achieve MCMB domestic substitution is Shanshan shares, when Shanshan shares with the help of the technical strength of Anshan Thermal Energy Research Institute, the first MCMB production line in the mainland was established, successfully reducing the price of MCMB anode materials significantly.
Almost at the same time as Shanshan mass-produced MCMB, Professor Wang Chengyang of Tianjin University also developed MCMB related technology, and subsequently authorized this technology to Tianjin Tiezhong Coal Chemical Company. In 2008, Tianjin Iron City was acquired by Bertry.
When the mainland realizes the domestic replacement of MCMB, in fact, the market demand for lithium batteries has changed, and mobile phones and laptops have become the main landing scenarios of lithium batteries, which puts forward certain requirements for the capacity density of lithium batteries.
With the continuous improvement of the penetration rate of lithium batteries in the 3C digital field, graphite materials with higher capacity have gradually replaced MCMB. The first to replace MCMB is the natural graphite material, which was first done by Beret. Almost at the same time as natural graphite, there is artificial graphite, although the price of artificial graphite is slightly higher, it is not easy to expand, the cycle is better, the charge and discharge rate is good, and it is suitable for more application scenarios.
Overall, the lithium battery anode continues the industrial iteration route of petroleum coke, MCMB, natural graphite, and artificial graphite. Specific capacity and expansion rate are the most concerned performance parameters.
In 2011, natural graphite has become the material with the highest market share, accounting for 59%; artificial graphite ranks second with a market share of 30%, and MCMB's market share is only 8%.
It was in the early stages of graphite replacing MCMB, and the market was still based on cost as the primary consideration. The physical and chemical properties of natural graphite and artificial graphite are not so big, so the market is more willing to accept natural graphite with higher cost performance.
However, by 2015, the proportion of natural graphite anodes fell to 55%, and in 2020, it plummeted to 16%; the market share of artificial graphite anodes increased from 30% all the way to 84%.
Why has the artificial graphite anuseroid achieved the crushing trend of natural graphite in recent years? The reason is the rapid outbreak of new energy vehicle tracks.
The artificial graphite anode has the advantages of long cycle life and fast charging and discharging, resulting in power battery manufacturers unanimously choosing the slightly more expensive artificial graphite as the mainstream route.
Throughout the development of lithium battery anode materials, which lithium battery anode has become the mainstream of the market mainly depends on the application scenario at that time. After the basic performance is satisfied, the core competitiveness of the negative electrode manufacturer no longer depends on research and development, but how to reduce costs and increase efficiency, which also leads to a general convergence of profit trends in the entire industry.
02 Tesla opened the negative "magic box"
It is the market demand that determines the choice of anode material, and Tesla's 4680 battery solution is expected to break the long-term market expectations for anode material.
What is the biggest change brought by the 4680 battery? That is, compared with the 21700 battery, it is close to 5 times the capacity increase, 6 times the power increase and 16% mileage increase, which solves the pain point of today's power battery lack of range.
Electric vehicles have long been trapped by the short range caused by the low density of power battery capabilities.
Previously, the industry mainly focused on the improvement of the energy density of power batteries on the choice of cathode materials, but to this day there is still a route dispute between ternary batteries and lithium iron phosphate, and it is obvious that there is no consensus conclusion in the cathode industry.
The significance of Tesla's 4680 battery is that it breaks through the traditional thinking of battery manufacturers focusing on the positive pole, and instead improves the energy density and efficiency of the maximum expansion of the power battery through the battery structure and negative electrode.
For the graphite anode, the current capacity of high-end products has been able to reach 360-365mAh/g, almost reaching the theoretical capacity of 372mAh/g ceiling, in the power battery energy density has not been able to perfectly meet the needs of electric vehicles, the search for higher gram capacity of the negative electrode material has become the general trend.
Looking at all anode materials, only silicon-based materials can significantly increase the gram capacity of the negative electrode, which is likely to become the next generation of anode products. But at the same time, there are fatal flaws in the silicon-based anode, limiting the rapid popularization of this technology.
First of all, the silicon-based negative electrode expansion multiple is large, it is easy to deform, and secondly, the cycle performance is significantly lower than the graphite anode, the conductivity is not very good, coupled with the high selling price, resulting in the delay in obtaining the favor of downstream manufacturers.
Subject to these defects, silicon-based materials are difficult to quickly apply to anode materials in the short term, the current solution in the industry is the way of silicon-based material composite graphite, has been able to achieve a specific capacity of more than 400mAh / g battery solution.
03 Triple change triggered by the 4680 battery
Tesla's 4680 battery solution is expected to bring drastic triple industrial changes to the lithium battery anode.
The entire anode industry has changed from graphite to silicon-based composites, which will be the first major change brought by the 4680 battery to the anode of the lithium battery.
Before the 4680 battery, silicon-based materials have actually been added to the negative electrode scheme by some manufacturers in small quantities, such as the 21700 battery anode of tesla Model 3, which adds 5% of the silicon-based material. The data shows that in 2020, the domestic shipment of silicon-based materials is only 0.9 million tons, and the industry penetration rate is only about 2.5%.
However, the emergence of 4680 batteries is expected to drive the market demand for silicon-based anodes, and the penetration rate of the entire silicon-based material in the negative electrode is expected to double.
Behind the increased permeability of silicon-based materials, the core conductive agent carbon nanotubes may become another beneficiary material, which is the second major change brought about by the 4680 battery.
Because the conductivity of silicon-based materials is very poor, after the comprehensive discharge, the first choice to solve the problem of conductivity is the industry generally takes the way of adding conductive agents to solve.
At present, the traditional conductive agent of "carbon black + conductive graphite" is widely used in the industry, but the traditional conductive agent is added in large quantities and mainly relies on imports. In recent years, carbon nanotubes are a rising new conductive agent with small additions and obvious advantages.
Carbon nanotubes are tubular nanoscale graphite crystals with good electrical conductivity. Carbon nanotubes are often added to the cathode material as a conductive agent to improve the conductivity of lithium battery pole plates, which is enough to improve the magnification performance and cycle life of lithium batteries.
In 2014, carbon nanotubes were only a kind of cold conductive agent accounting for 13.6%, and with the release of domestic power batteries, the penetration rate of carbon nanotubes has been continuously improved, and the market share has increased to 31.8% by 2018. Continuing today's trend, by 2025, the market share of carbon nanotubes is expected to exceed 60%.
Mainland China already has the independent production capacity of carbon nanotubes, the current domestic enterprises engaged in carbon nanotubes include Tiannai Technology, Cabot, Qingdao Haoxin, Jiyue Nano, German Nano, Wuxi Dongheng and so on.
Among them, Tiannai Technology is an absolute industry leader. In terms of shipments, the market share of Tiannai Technology in 2020 is as high as 32.3%, while the second and third places are 23.8% and 19.6%, and the gap is obvious.
The upcoming third change is that the 4680 battery may change the existing pattern of the current negative electrode industry from the essence.
In 2020, China's anode materials market is mainly divided by 4 major enterprises, With Beret, Putailai (Jiangxi Zichen), Shanshan Shares, and Kaijin Energy occupying 22%, 18%, 17% and 14% of the market share respectively, and CR4 occupying a total of 71% of the market share.
At present, the market share of the negative electrode of each enterprise is mainly affected by the capacity of graphite anode, with the outbreak of silicon-based materials in the future, the market share of the entire negative electrode may change drastically, and those companies that are earlier in the layout of silicon-based materials will seize market share in advance.
Focusing on the global silicon-based anode industry, Japan's Shin-etsu is the most advanced in technological strength, while in the domestic market, Barrett is the forerunner in the industry, and Putailai and Shanshan shares are currently catching up.
As early as September 2020, Barrett's silicon-based anode has been officially put into production, and the market expects that this year's shipments will be about 3,000 tons, which is ahead of other companies and is most likely to become the biggest beneficiary of the silicon-based anode.
Pu Tailai is currently the second oldest in the negative market. In the layout of silicon-based materials, Putailai has cooperated with the Institute of Physics of the Chinese Academy of Sciences to complete the second generation of products and participate in the testing and certification of downstream users, and is expected to start to increase in the next few years.
Shanshan shares are mainly focused on silicon oxygen anode, has been in the consumer and small power market to achieve batch applications, power batteries are still testing and certification, is also in the early stage of mass production.
In addition, Kaijin Energy, Zhongke Electric and other companies are also actively laying out silicon-based anodes, hoping to seize the next iteration of the anode industry.
In general, the lithium battery anode from graphite materials to silicon-based materials has become a recognized technical direction in the industry, and the formal release of 4680 batteries is likely to stimulate the overall demand for silicon-based materials, which will not only reshape the entire lithium battery anode industry pattern, but also drive the development of related conductive agent industries.
The 4680 battery solution is not Tesla alone, and battery manufacturers such as BAK Battery and Ewell Lithium Energy have also begun to develop their own "4680 solutions". This means that the 4680 battery discharge will most likely become a high probability event, and this is also expected to become the beginning of the next iteration of the lithium battery negative electrode.