Breaking through 300Wh/kg, the industrialization of silicon-carbon anode accelerates

As a powerful tool to break through the shackles of battery energy density, the industrialization process of silicon-based negative electrode materials is accelerating. So far, many car companies including Tesla, BYD, NIO, SAIC Zhiji, GAC Aion, Mercedes-Benz, and Zeekr have already started or are about to install silicon-based negative electrode power batteries. Leading battery manufacturers such as CATL, EVE Energy, and Guoxuan High-tech have also deployed silicon-based negative electrode power battery products.

"Silicon-based negative electrode is the new type of negative electrode material most likely to be used on a large scale in the future, and its application is becoming a battleground for battery performance differentiation." Industry organizations analyzed that it is predicted that by 2025, the global demand for silicon-based negative electrode materials is expected to reach 200,000 tons, of which the penetration rate in consumer batteries is expected to reach 50%, corresponding to a demand of about 70,000 tons; the penetration rate in cylindrical and square power batteries will reach 35% and 20% respectively, corresponding to a demand of about 130,000 tons.

As downstream electric vehicle companies continue to increase their requirements for power battery energy density, Northeast Securities believes that the transition of lithium battery negative electrode materials from graphite systems to silicon-based negative electrodes will be the future direction of technological upgrades. In the future, the system of silicon-based negative electrodes combined with high-nickel ternary materials may become one of the mainstream development trends, and the industrialization of silicon-based negative electrodes is about to come.

01

Battery leaders are more optimistic about the technology route

The performance of silicon-based materials is extremely outstanding, and they can achieve a "dimensionality reduction attack" on the current mainstream graphite materials . Theoretically, the specific capacity of graphite negative electrode materials is 372mAh/g, and the actual mass-produced products have reached 360mAh/g, which has approached the theoretical maximum value and basically reached the limit level of industrialization. The theoretical gram capacity of silicon negative electrode can be as high as 4200mAh/g, which is more than 10 times that of graphite materials.

At present, many companies have developed batteries with energy densities exceeding 300Wh/kg, precisely because they use a combination of high nickel and silicon negative electrode materials. For example, the silicon-doped lithium-supplemented battery from CATL used in SAIC Zhiji has a cell energy density of over 300Wh/kg; NIO released a 150kWh battery pack that uses inorganic pre-lithiation silicon-carbon negative electrode technology, with a cell energy density of 360Wh/kg.

According to industry insiders, silicon-based negative electrode materials mainly include two technical directions: silicon-carbon and silicon-oxygen. Currently, silicon-oxygen technology is mature but has a low upper limit, "the main limitations are the first charge and discharge efficiency and energy density (the upper limit of gram capacity is relatively low)", and silicon-carbon negative electrode with high first efficiency is the medium- and long-term choice for battery factories.

However, silicon-carbon negative electrodes also have the disadvantages of large expansion and poor cycle performance. It is understood that due to the material characteristics of silicon-carbon negative electrodes, they will expand and shrink during the charging and discharging process, and their maximum volume expansion rate is as high as 300%, which is much higher than the 10-12% of graphite negative electrodes. In addition, the current general cycle life of silicon-carbon negative electrodes is 300-500 times, while the cycle life of artificial graphite negative electrodes can exceed 3,000 times. This also affects the industrialization process of silicon-carbon negative electrodes.

The industry has been seeking technological breakthroughs. Tianfeng Securities pointed out that due to its better consistency, the expansion rate of porous silicon-carbon composite materials prepared by chemical vapor deposition (CVD) is lower, and the corresponding cycle performance has also been significantly improved. "From the perspective of improving energy density in the medium and long term, CATL encourages material manufacturers to develop silicon-carbon negative electrodes, especially chemical vapor deposition methods," the agency said.

Of course, due to the relatively complex process technology of CVD deposition of silicon-carbon negative electrode materials, high requirements for product stability, and the fact that raw materials have not yet been mass-produced, it has a high threshold and cost.

02

Mass production is accelerating

At present, many material manufacturers are increasing their investment in silicon-carbon anode projects. According to incomplete statistics from industry organizations, from the beginning of 2023 to September this year, more than 400,000 tons of silicon-carbon anode material production capacity planning projects have been launched, involving an investment of more than 20 billion yuan. Leading manufacturers such as B&T, Shanshan Co., Ltd., and Putailai have all made plans.

On September 15, the first batch of production lines of Anhui Bondrui Nano-scale Silicon-Carbon Anode Materials and Slurry Conductive Project was put into production. It is reported that the total investment of the project is about 6 billion yuan. After completion, it can produce 50,000 tons of nano-scale silicon-carbon anode materials and 200,000 tons of supporting new conductive agents annually.

According to Battery China, Shanshan Co., Ltd., a leading negative electrode material company, has made breakthroughs in the core technology of mass synthesis of silicon-based negative electrode material precursors and achieved mass supply of silicon-based negative electrodes. The company has also built a 40,000-ton integrated silicon-based negative electrode production capacity base in Ningbo, and the first phase of the project is expected to be put into trial production in the second half of this year.

Another material leader , BYD Battery, currently has a silicon-carbon negative electrode production capacity of 5,000 tons/year, and the company has also invested 5 billion yuan to build a project with an annual output of 40,000 tons of silicon-based negative electrode materials . The first phase of the project is expected to be completed and put into production in 2024. It is expected that by 2028 it will have a silicon-based production capacity of about 50,000 tons/year.

According to Putailai, the company's CVD deposited silicon-carbon anode products are being introduced smoothly to consumer customers , and the pilot line capacity is in short supply. The company is accelerating the construction of the capacity of Anhui Zichen's 12,000 tons/year silicon-based anode material project, and it is expected that the first batch of production capacity will be formed in early 2025.

In addition, Dow Technology revealed that its silicon-oxygen negative electrode materials and new gas-phase silicon-carbon negative electrode materials have been sent for evaluation and have been recognized by some customers. Zhongke Electric disclosed that its silicon-carbon negative electrode has completed the pilot production line, and some products have been sent to customers for testing and recognized. Xiangfenghua said that the silicon-carbon negative electrode material products developed by its company are in the pilot stage and have the conditions for industrialization. Binhai Energy disclosed that its silicon-carbon products have completed the determination of small-scale test conditions.

The industry is generally optimistic about the application prospects of silicon-carbon anodes. In the view of industry insiders, with the continuous improvement of silicon-carbon anode process technology, the continuous development and cost reduction of raw materials, and further exploration of the mixing ratio of silicon-carbon anodes, silicon-carbon anode products will continue to expand in the field of power batteries in the future, and CVD deposited silicon-carbon anodes will also show their prowess, helping to continuously improve the performance of power batteries.