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The original title: "where is the way to anode materials?" "

Compared with other main materials, the discussion degree of negative electrode is not very high. This is mainly because its market is relatively simple, the technical threshold is not too high, the overall understanding is not difficult, and the future development path is relatively clear. In other words, this is an industry where "the building has been basically completed and there are few dark clouds above". Therefore, although corresponding to the positive pole, the negative electrode has neither the right to name the battery nor the heat, which is not surprising.

However, after all, the negative electrode is one of the main materials of the battery, which has a decisive impact on the product performance, and the overall progress of lithium battery technology can not be separated from the development level of the upstream link, ignoring either side can not form an accurate judgment of the big picture of the lithium battery industry. In this article, Fruit Shell hard Technology will focus on negative materials to analyze this key role that is not in the spotlight for readers.

The negative electrode of lithium battery mainly smears the active material on both sides of the current collector (copper foil). In the process of charge and discharge, the negative electrode is responsible for storing and releasing lithium ion and making the current pass through the external circuit. The negative electrode material has a great influence on the energy density, cycle performance, charge-discharge rate and low-temperature discharge performance of lithium battery, which should have the lowest possible electrode potential, higher Li + transfer rate, high Li + intercalation / de-intercalation reversibility, good electrical conductivity and thermodynamic stability.

Affected by the cost composition of lithium batteries of different technology routes, the proportion of negative materials in the cost of lithium batteries fluctuates to a certain extent, about 10%, usually no more than 15% [1].

From the point of view of the technical route, the anode materials of lithium battery can be divided into two categories: carbon and non-carbon, while the further subdivision route is quite complicated, and there are great differences between different materials.

Carbon materials: including graphite, graphene and disordered carbon

Non-carbon materials: to include silicon-based materials, tin-based materials, titanium-based materials, nitrides and so on.

Source: bank of China Securities [2]

At present, the most mainstream negative electrode material is graphite negative electrode, and graphite negative electrode can be further divided into two categories: natural graphite and artificial graphite. It should be emphasized that mesophase carbon microspheres (MCMB) and some other graphitized carbon are graphite materials in general classification, but they are not included when graphite materials are mentioned in the usual discussion context, and only natural graphite and artificial graphite products are covered when graphite materials are mentioned below.

Compared with other anode materials, although the graphite negative electrode is not the best in all aspects, it has the highest comprehensive price ratio and has no obvious deficiency. At the same time, graphite anode materials have a wide range of sources, low price, good safety, and the application technology and production technology are very mature.

Source of information: Kaijin New Energy [1] artificial graphite occupies an absolutely dominant position in the current negative electrode market, and its shipment is much larger than that of negative electrode materials (see Section 3 of this article for detailed market data). The cycle performance of the product, rate performance, expansion rate and other indicators are ahead of natural graphite, but the capacity is low and the production cost is high, which is mainly used in the field of power battery and energy storage battery. The capacity of natural graphite is usually higher than that of artificial graphite, and the production cost is relatively low, but other aspects are basically at an all-round disadvantage, which is mostly used in 3C product batteries.

From the production end, the production process of graphite negative electrode is long, there are many processes, and there are some differences in the production process of different enterprises. The production process of artificial graphite is mainly divided into four links: crushing, granulation, graphitization and screening, and more than ten processes are subdivided. Different enterprises use different production processes in different links, and these differences will affect the final performance of the products.

Source: bank of China Securities [2] in the production process of artificial graphite, crushing and screening are relatively simple, and the technical level of the enterprise is mainly reflected in the two links of granulation and graphitization.

The size, distribution and morphology of graphite particles affect several performance indexes of anode materials. Generally speaking, the smaller the particles are, the better the rate performance and cycle life are, but the worse the first efficiency and compaction density are, and vice versa, and the reasonable particle size distribution (mixing large and small particles) can increase the specific capacity of the negative electrode. the morphology of particles also has a great influence on magnification and low temperature performance. Therefore, in order to meet the needs of downstream customers, negative enterprises need to have the ability to design and control the particle size and morphology to meet the given product performance.

Graphitization refers to the transformation of thermodynamically unstable hexagonal carbon atoms from disordered two-dimensional structure to graphitic carbon with ordered structure of graphite crystals. Artificial graphite uses coke materials as the main raw material and uses high temperature heat treatment (1800 ℃ graphitization process) to change the spatial structure of coke materials and improve their volume density, electrical conductivity, thermal conductivity, corrosion resistance and mechanical processing properties, which have a key impact on the properties of the final artificial graphite products. As the graphitization content is more and involves the important development trend of the negative electrode industry, this link will be explained in detail below.

The production process of natural graphite is mainly divided into four links: purification, modification, mixing and carbonization. Because graphitization, the most prominent process in cost composition, is not involved, the production cost of natural graphite is superior to that of artificial graphite, but this gap can not make up for the deficiency in the performance of the final product.

On the cost side, the cost of natural graphite is greatly affected by the price of upstream raw materials. About 80% of the total cost comes from direct materials, while the rest are carbonization processing fees, direct labor and manufacturing costs. The cost of artificial graphite is mainly concentrated in graphitization and direct materials, of which graphitization accounts for about 40% and 60%, and the sum of the two can account for about 90%. The rest are direct labor and manufacturing costs [2] [3] [4] [5] [6].

Among other anode materials, silicon-based materials receive the most attention, have the greatest hope of industrialization, and have the greatest potential to become the next generation of main anode materials, which we will discuss in detail in the fourth section of this article.

The rest of the technical routes are in a relatively early stage. These materials often have some outstanding indexes, such as higher specific capacity, better cycle performance, better rate performance, etc., but at the same time, they also have key defects, such as the production process is too complex, the cost can not be controlled, some properties have major defects and there is no solution, in short, they can not meet the industrial standards and can not be widely used.

Graphitization, an important trend of key links, is one of the most critical links in the negative supply chain, its capacity directly affects the final capacity of the negative electrode, and price fluctuations also have a very obvious impact on the market and enterprises in the track.

Graphitization is a standard production process with high temperature and high energy consumption, resulting in a very high proportion of energy costs in the total cost, about 40% and 60% [3] [6]. The characteristic of high energy consumption also leads to the problem that graphitization production capacity can not be fully utilized due to the "double control" of graphitization production under the wind of strict energy consumption management in recent years, and it is difficult to approve new capacity.

According to the continuity of production, graphitization process can be divided into intermittent production and continuous production.

Intermittent graphitization: in the process of graphitization, the material does not move after charging, and the power is cut off after heating, graphitization, cooling, etc.

Continuous graphitization: there is no power outage in production, graphitized products need to go through a series of temperature zones, so as to achieve continuous graphitization.

According to the processing equipment, graphitization can be divided into crucible furnace, including Acheson furnace and internal heat series furnace, box furnace and continuous furnace. Both crucible furnace and box furnace belong to intermittent process, while continuous furnace is worthy of the name [6].

Crucible furnace is the mainstream graphitization process, and Acheson furnace is the most commonly used crucible furnace. The process is not difficult, the technology is very mature, and is widely used by enterprises in the industry, but the energy consumption is relatively high, and it is not enough to protect the environment, so it does not accord with the current economic development model.

The box furnace is upgraded from the crucible furnace, the effective volume and use efficiency of the box furnace are obviously higher than that of the crucible furnace, but the total energy consumption is not greatly increased, thus the unit power consumption is greatly reduced. In other words, the box furnace has higher production efficiency, lower energy consumption and more environment-friendly. The defect of box furnace lies in its high technical barrier, which requires accurate control of various parameters in the production process, and puts forward more requirements for the manufacturer's process level and production experience. at present, it is only used skillfully by a small number of head enterprises in the negative industry.

Continuous graphitization represents the future development direction of the industry. Compared with the intermittent process, the continuous graphitization process has no power outage, the process is simple and the production cycle is short, which can save a lot of manpower, material resources and cost expenditure of the intermediate links; the heat utilization is high, and the unit energy consumption is lower; the waste in the production process can be treated centrally, which is more environmentally friendly and meets the needs of industrial upgrading. The defect of the continuous type is that the graphitization degree is low due to the low temperature in the furnace, and the performance of the final product is different from that of the intermittent type, which can not meet the downstream demand. At present, it can only be used in relatively low-end fields, and the equipment maintenance and depreciation costs are more expensive. Some process links are not perfect, in short, mass production technology is in urgent need of breakthrough, has not yet entered large-scale application.

As mentioned above, graphitization accounts for 40% to 60% of the cost of artificial graphite, and reducing graphitization costs is the key to improving the profitability of negative producers, which leads to an industry trend of "integration".

The so-called "integration" means that negative enterprises integrate their own supply chain and build their own graphitized production capacity. Because the graphitization process is relatively independent, the equipment investment demand is large, and the production cycle is long (a cycle is usually 20-30 days [3]), but the process is not complex, so the early negative enterprises mainly carry out graphitization by means of outsourcing production. However, this model has been affected by the upsurge in demand for lithium batteries downstream in recent years, and the demand for negative electrodes has risen synchronously, while the graphitized production capacity as a key link in the production process is insufficient, supply and demand is tight, and processing fees begin to grow rapidly. obviously squeezed the profit space of most negative enterprises with low self-sufficiency rate, but the original planning to save costs began to weaken the profitability of enterprises. It eventually led to a decline in gross profit margin for the entire negative industry in 2021.

Driven by such factors, negative enterprises have begun to acquire or build their own graphitized production lines, reduce outsourcing production, and begin to improve self-financing capacity, so as to reduce costs, enhance profitability, and protect the supply chain. This is one of the most important development trends of the current negative industry, and it is also likely to be one of the core competitiveness of negative enterprises in the future.

The market situation is the same as other lithium battery main materials, the negative electrode materials in recent years have significantly benefited from the rapid development of electric vehicles, the market scale has expanded rapidly, but the overall format is not too complex.

Shipments of anode materials in China rose rapidly from 146000 tons in 2017 to 720000 tons in 2021, with a CAGR (compound annual growth rate) of 49% and a year-on-year growth of 97.3% in 2021. Shipments of negative materials in 2022 were 1.37 million tons, an increase of 90.3% over the same period last year, and the growth rate slowed slightly [8].

Affected by the great differences in technological maturity of different routes and the downstream demand, the product composition of the negative electrode market is relatively simple, the negative electrode of graphite occupies an absolutely dominant position, and the shipment volume of artificial graphite is much higher than that of natural graphite; in other technological routes, silicon-based accounts for most of the cargo, while other routes account for very little.

Specifically, as the comprehensive performance of artificial graphite is better than that of natural graphite, which is more in line with the needs of the downstream power and energy storage market, the proportion of shipments continues to increase, from 69.2% in 2017 to 84% in 2021; affected by performance limitations, the proportion of natural graphite decreased from 26.7% to 14% [3] [9] in the same period. Other negative materials accounted for only 2% of shipments in 2021, of which silicon-based negative electrodes accounted for about 1.53%, while other negative electrodes accounted for only 0.47% [10] [11]. However, in 2022, the proportion of natural graphite increased slightly, to about 15%, mainly related to the low-end demand substitution caused by insufficient supply of artificial graphite, the increase in blending amount and the improvement of production technology [8].

In terms of production capacity, most of the global negative capacity is concentrated in China at the present stage. Chinese enterprises dominate the global market by virtue of the advantages of industrial chain distribution, product performance and cost. In 2021 alone, the proportion of global shipments of negative materials by Chinese companies increased to 86% from 77% in 2020, much higher than in other countries; other production capacity is mainly concentrated in Japanese and Korean enterprises [3].

Data source: East Asia Qianhai Securities [11] from the domestic market pattern, there is no absolute leader of domestic negative electrode production enterprises, but the overall concentration of the industry is very high, and a few leading enterprises jointly dominate the market. Affected by the statistical caliber, the industry concentration given by different institutions is different, but on the whole, the seven enterprises constitute the first and second echelon. They are Beitri, Putailai, Shanshan, Shangtai Science and Technology, Dongguan Kaijin, Zhongke Electric, Xiang Fenghua.

In terms of specific figures, the first echelon is Betteri (24%), Putailai (15%) and Cunninghamia lanceolata (15%), with a total CR3 of 54%; the other four enterprises in the second echelon have a combined market share of 34% [6]. Compared with 2020, CR3 in the negative industry declined (- 2 per cent), but CR7 continued to rise (+ 2 per cent), mainly due to extremely strong downstream demand, insufficient supply capacity of the first echelon full production and consumption, and orders spilling to the second echelon. However, the upstream graphitization capacity constraints led to the supply mainly digested by the head company, and the capacity expansion of enterprises below the third tier could not keep up with the pace of the first and second tier enterprises, resulting in this trend. However, with the gradual landing of the new production capacity of the first echelon and the advance of market share with major customers, the CR3 of the negative industry has rebounded to a certain extent in 2022 [8].

The rise of silicon-based there is no doubt that artificial graphite materials dominate the current negative electrode industry, but it is facing a considerable technological iteration.

At present, lithium batteries have an increasingly strong demand for high energy density, long life, fast charging and other performance, and anode materials must also need to improve the performance. The core problem of graphite material is that its performance is close to the theoretical limit. At present, the actual specific capacity of the most commonly used graphite materials has reached 360~365mAh / g, which is almost the same as the theoretical specific capacity (372mAh / g). The benefit of continuous R & D investment in graphite products has been very limited [12]. At the same time, after fast charging has become the mainstream development direction, the layered structure of graphite material leads to long lithium ion transport path, slow lithium intercalation process, which limits the defect of charging efficiency, and the side reaction will cause lithium precipitation in the process of high current charging. The precipitated lithium metal grows in the form of dendrites, which has the risk of piercing the diaphragm and endangering the safety of the battery, which affect the development of graphite negative electrode in the future. Therefore, it is a broad consensus in the industry to focus on the development of the next generation of anode materials.

At present, a new type of negative electrode material with good performance, high maturity and rapid growth is generally recognized by the industry, which is a silicon-based negative electrode.

The most outstanding advantage of silicon-based battery is its unparalleled theoretical specific capacity. The ideal theoretical specific capacity of the elemental silicon negative electrode is 4200mAh / g, which is about 12 times that of the artificial graphite negative electrode, and it is the known anode material for lithium battery with the highest specific capacity. the silicon-carbon negative electrode (less than 450mAh / g) and silicon-oxygen negative electrode (450~500mAh / g) which have been commercially applied are also stronger than graphite negative electrode [2] [10] [13] [14]. At the same time, the silicon-based negative electrode also has the characteristics of high safety, environment-friendly, abundant reserves and low price of raw materials.

However, the current technical problems of silicon-based batteries are also prominent, which limits their large-scale application. The charge-discharge expansion rate of silicon negative electrode is very high, more than 300% (silica expansion rate is more than 180%), while the graphite material is only about 12% 25% [14]. This will lead to the rupture and pulverization of silicon particles, affecting the direct transfer of electrons on the electrode, causing electrode failure, causing rapid attenuation of battery capacity and affecting battery cycle performance. During the charging process of lithium-ion battery, the organic electrolyte will decompose on the negative surface to form SEI (solid electrolyte interface) film, which irreversibly consumes lithium ion from positive electrode in lithium-ion battery, but the volume change of silicon may destroy SEI film and consume lithium and electrolyte continuously, resulting in low first Coulomb efficiency (first effect) and outstanding capacity attenuation of battery. The contact between silicon and conductive agent and negative binder is poor, resulting in poor overall conductivity of the electrode.

The combined effect of these factors also makes it impossible for silicon-based batteries to land quickly, at least less than the optimistic expectations. A more typical example is the Tesla 4860 battery, which was once rumored to use a silicon-based negative electrode, but it did not do so in the end. This suggests that Tesla may also have failed to properly address the major defects of silicon-based negative electrodes.

In order to solve the expansion coefficient defect of elemental silicon, artificial graphite is usually added in the way of doping in the current practical application, and the mainstream technical route is silicon-carbon negative electrode and silicon-oxygen negative electrode. The former refers to the mixture of nano-silicon and graphite materials, the latter is the composite of silicon oxide and graphite materials. In the composite process of silicon and different materials, the expansion space is usually provided by means of structural design (nanocrystallization and porous silicon). Silicon-based materials mainly provide capacity as active materials in composites, and other materials are used as carriers to buffer volume expansion. In addition, the silicon-based anode material will be designed as a coating structure, and the outermost layer is coated with carbon to act as a conductive network, which can also avoid the side reaction of the electrolyte directly contacting the silicon-based material.

Source of information: Kaijin New Energy [1] from the performance point of view, silicon-carbon negative electrode first efficiency is high, but the volume expansion coefficient is too large, leading to poor cycle performance, generally in 500 to 600 weeks, can not meet the national standard power battery cycle standard of 1000 cycles; on the contrary, silicon oxygen carbon negative electrode, the first effect is relatively low, the cost is high, but the cycle is better [10].

Compared with graphite anode materials, the preparation process of silicon-based anode is complex, the production process is different, and there is no unified product standard. At present, the common preparation methods are chemical vapor deposition, mechanical ball milling, high temperature pyrolysis, sol-gel method [16]. Among them, mechanical ball milling and chemical vapor deposition have relatively simple equipment requirements and low manufacturing cost, so they have a high degree of popularity, but in order to ensure product performance in industry, a variety of processes are also widely used.

From the market point of view, the silicon-based negative electrode is undoubtedly in the early stage of commercialization, the shipments and permeability are at a very low level, and the growth rate is not as fast as the overall expansion speed of the negative electrode industry. In 2021, domestic shipments of silicon-based negative electrodes were about 11000 tons, with a permeability of 1.5%, a year-on-year growth rate of 83% [10] [14].

It can only be said that, despite the clear route, the development of silicon-based negative electrodes still needs technical support and development time in order to develop on a real scale. It is very hopeful that it is true, but for the time being, it is only very hopeful and true.

Short-term deficiency and long-term surplus in addition to the significant pressure of technical iteration, the negative electrode is also faced with a relatively contradictory situation at the energy production end, that is, short-term deficiency and long-term surplus.

The short-term deficiency is related to the extremely strong demand of the downstream lithium battery industry and the characteristics of the graphite industry.

The production process of graphite negative electrode is the standard "high temperature and high power consumption". Under the background of "double control" and "carbon neutralization" at the present stage, the output is limited, and the approval of new high energy consumption projects is very strict. this also leads to the slow expansion of graphite production capacity.

Generally speaking, under the influence of policy regulation, the current negative industry has insufficient effective capacity and slow release of new capacity (especially graphitized capacity), which leads to short-term supply shortage.

However, in the long run, the overcapacity pressure of negative materials is very great. According to GGII incomplete statistics, in the first half of 2022 alone, there were 29 negative material production expansion projects, involving a production capacity of 4.006 million tons [17]. According to the data given by Jiangsu Institute of Chemistry and Chemical Engineering, as of September 2022, the capacity planning of the national anode material base has exceeded 14 million tons [18]. For comparison, H1 shipped 540000 tons of anode materials in 2022 and is expected to be about 1.2 million tons for the whole year. Even if the high growth rate of the new energy vehicle industry is taken into account, demand is unlikely to match the over-expansion of capacity. With the commissioning of new production lines and possible iterations of negative materials, the future overcapacity of the industry is basically inevitable.

Overcapacity inevitably means a continued decline in shipping prices and the ensuing downward cycle. The pressure on profits, the elimination of backward production capacity and the reshuffle of the industry pattern are all very common phenomena in the downward cycle, and the negative material industry will be unavoidable at that time. How to deal with the risk of overcapacity will be another problem that the negative industry must deal with cautiously in addition to product upgrading.

This means that it is necessary for enterprises to pay attention to production process upgrading, cost control and more reasonable and flexible capacity planning.

On the one hand, head enterprises need to focus on improving product quality, better production performance, and can better meet the market demand of negative products, which needs to be achieved by optimizing production processes and technology upgrading. However, for the backward enterprises which rely on demand spillover to achieve growth in recent years, how to deal with the overall overcapacity of the industry will be a very serious problem, and it is normal to be eliminated for the backward enterprises whose technical level is not high and product competitiveness is not strong.

The "integration" mentioned in the third section and the realization of graphitized self-supply is a key measure for negative production enterprises in the cost control side.

On the other hand, in order to expand production capacity and reduce energy costs, companies are more likely to move to regions with lower energy prices, typically the attraction of low electricity prices in southwestern provinces. But this will also increase the pressure on the local dual control, how to obtain the production license has also become the performance of the competitiveness of the enterprise, while the head enterprise with its larger scale and higher investment scale, as well as the ability to provide more jobs, also have an advantage.

For new entrants, it means a worse market environment, and it is likely that the new production capacity will soon face the dilemma of lower negative material prices, and the resolution of this risk is relatively difficult, which is a great test of the competitiveness of enterprises.

The expectation of comprehensive technology iteration can only be said to be a new story of the negative industry, which has just begun.

References:

[1] Guangdong Kaijin New Energy Technology Co., Ltd.: initial public offering prospectus (application draft) .2022.01.07

[2] Bank of China Securities: industry depth report on negative materials for power batteries. 2022.3.17

[3] Guotai Junan Dianxin team: Guojun Dianxin negative material series: graphitization discussion-integrated production capacity is gradually released, negative profit is expected to be improved. Guojun Dianxin New depth observation. 2022.08.14 https://mp.weixin.qq.com/ s / X31vfkeh1Ze8z2OztGNT-g

[4] Pu Tai Lai: Shanghai Pu Tai Lai New Energy Technology Co., Ltd. 2021 Annual report. 2022.04.28

[5] Zheshang Securities: industry promotes integrated layout, new technology accelerates introduction. 2022.04.22

[6] Huaan Securities: graphitization gap is still there, process iteration and integrated layout reshape the negative electrode pattern. 2022.03.08

[7] Review of China's lithium anode market in GGII:2021. Advanced lithium battery. 2022.04.05 https://mp.weixin.qq.com/ s / v5NH7QcQP1F8vZrmvBli8w

[8] inventory of lithium anode materials in China in GGII:2022. Advanced lithium battery. 2023.01.27 https://mp.weixin.qq.com/ s / axZqRmbS4gpPQ6OL0uu6-w

[9] China's lithium anode market shipped 720000 tons in GGII:2021, an increase of 97% over the same period last year, with artificial graphite accounting for a further increase. New industry think tank. 2022.03.31 https://mp.weixin.qq.com/ s / h9y3xUTM-E3LZEU1Ax9gwg

[10] Tianfeng Securities: volume inflection point, optimistic about silicon negative electrode and derivative new materials investment opportunities. 2022.03.20

[11] East Asia Qianhai Securities: anode Materials for Lithium Battery Series reports. 2022.09.28

China International Capital Corporation: 2022 is expected to be the first year of silicon-carbon negative electrode industrialization. Interface News. 2022.03.04 https://www.jiemian.com/ article / 7168862.html

[13] Everbright Securities: sodium battery negative electrode from zero to one, hard carbon material tight encirclement. 2022.11.13

[14] Huaan Securities: Silicon-based negative electrode, the only way to upgrade lithium materials. 2022.05.26

[15] Armen Hareyan:Tesla's 4680 Battery Breakthrough: The Good, the Bad, and What It Means For You .TorqueNews .2022.12.26 https://www.torquenews.com/1/teslas-4680-battery-breakthrough-good-bad-and-what-it-means-you

[16] Bertrand New Materials Group Co., Ltd.: public offering of stock prospectus (application draft) to unspecified qualified investors. 2020.04.29

[17] attention of senior engineers: guard against the risk of overcapacity of negative materials. Advanced lithium battery. 2022.09.04 https://mp.weixin.qq.com/ s / UTmZCRmRWiIkRkdtTes9Ag

[18] JSCIA / JSSCCE: China's anode materials have exceeded 14 million tons! There will be excess capacity in a year. Jiangsu Society of Chemistry and Chemical Engineering. 2022.09.26 https://mp.weixin.qq.com/ s / UdRRI6kf7mkbohIN3tSvgQ

This article comes from the official account of Wechat: fruit Shell hard Technology (ID:guokr233), author: Chen Qianlei

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