Author/Baked bun under the stars
Edit/Spinach Starry Sky
Typography/Fried liver under the stars
In last year's lithium battery circle, when everyone's eyes were focused on the installation of lithium cathode iron phosphate and lithium ternary lithium, the negative players were also quietly working hard to surprise everyone.
This amazing weapon is a silicon-based anode material.
In a nutshell, the reason why anode companies actively study the next generation of anode materials is nothing more than two points, on the one hand, the downstream power battery shipments have been sharply increased by the sales of new energy vehicles, and the future is very good (the compound growth rate of anode materials in the past five years has reached 40%), and players want to use differentiated materials to seize the next highland of the negative electrode. On the other hand, with the increasing energy density requirements of power batteries, graphite's contribution to the improvement of battery energy density has approached the ceiling.
Once the ceiling comes, all that's left is the inner roll. So players have to find a new way out.
No, the pace of industrialization is so rapid. Amprius in the United States recently announced that the first batch of silicon carbon anode material lithium batteries came out first, and the energy density far exceeded Tesla's Model 3 (73% higher).
Silicon Carbon Anode Advent (Interface News)
Of course, those who know Musk know that he is definitely not someone who sits still and lets players overtake. Our team once introduced Tesla's 4680 cylindrical battery. When it comes to this battery, everyone's first reaction may be that it is a large 18650 battery, but behind this battery, it is not known that it is also using a silicon-based anode material.
Mass production of silicon carbon anode battery (Sina Finance)
You're just looking at the blue sky, but Musk is looking at the vastness of the universe.
Then again, is the silicon-based anode material really that flawless? On the road to the new generation of anode materials, which players are facing difficulties and desperately moving forward? Today I will take you to find out.
First, forge the long board, make up for the short board
After all, it is a new generation of negative electrode material, here are two more sentences (but also buried a burden for the following).
As one of the four kings of the battery (positive and negative electrodes, electrolyte, diaphragm), the specific capacity (the amount of electricity that can be released per unit weight of active substance) plays a vital role in improving the energy density of the battery. We have argued beyond reproach that the negative electrode material is graphite (the specific capacity of artificial graphite is 310~370mAh/g). Indeed, the proportion of graphite negative polar shipments last year exceeded 98%.
Classification of anode materials ("Basic Scientific Problems of Lithium-ion Batteries (VIII.)-Anode Materials")
And the silicon-based anode? At present, the specific capacity of the silicon-based negative electrode is about 580mAh/g higher than that of artificial graphite, and the reserves of silicon are also very large, and the safety will be better (lithium dendrites are not prone to cause cell short circuits). In the case of the graphite anode specific capacity reaching the limit, the silicon-based negative electrode found an opportunity to overtake in the corner, and it reportedly increased the energy density of the battery by more than 8%.
Since the long board has been very clear, whether it can be industrialized depends on whether the shortcomings of the technology are fatal.
In fact, the silicon carbon anode did not appear on the first day. In the 1990s, Japan successfully developed lithium-ion batteries with petcoke as the negative electrode. In the more than two decades since, the technology has not come out of the door of the laboratory. So what's the problem with it? Now what's the solution?
1, a charge and discharge, it expands
When silicon is charged and discharged, because the silicon crystal is a regular tetrahedral structure (graphite is a layered structure), it is easier to expand, and the expansion rate can reach 300%. This makes the battery more unstable. No one wants to make their beloved car a time bomb.
How to crack it? Silicon nanostructures are a good choice so that stress can be better released during expansion and crushing is avoided.
Schematic diagram of silicon expansion
2. The first cycle efficiency is low
We generally use the first coulomb efficiency (referred to as the first effect) to measure the charge and discharge capacity of lithium-ion batteries. And with the increase of silicon content, the first effect is getting lower and lower. It's like the two ends of a seesaw, you have to find a balance. This balancing method is to pre-fill lithium, that is, to pre-add a small amount of lithium to the negative electrode to supplement the lithium consumed during the formation of the side reaction and the solid electrolyte interface (SEI) membrane, which can improve the first effect.
The role of pre-supplement lithium (CNKI)
To make a simple analogy, it is like being afraid that the important guests in the invitation will not eat enough, you simply order a few more dishes, and plan ahead just in case, it is better than making up for the dead sheep.
Second, how beautiful is the future, and how cruel is the competition?
Since the problem of silicon carbon anode is being solved and optimized little by little, this means that the road of industrialization is getting closer and closer to us. At present, major players mainly mix silicon carbon into graphite and mix it.
From the forecasts of various agencies, the inflection point of the penetration rate of the silicon carbon anode will start from 2023, and the expected shipment volume will reach 22,000 tons by 2025 (this data will only be 0.6 million tons in 2020), a compound growth rate of 70%, are you not impressed?
Silicon Carbon Anode Shipment Forecast (GGII)
The author feels that the prediction of such high growth can be made by the joint efforts of industry players. Downstream OEMs have also begun to be optimistic about the prospects of this technology. Tesla is at the forefront of industrialization. Domestic players such as Guoxuan Hi-Tech (002074) 210Wh/Kg battery core has applied silicon anode for the first time, while having a production capacity of 500 tons of silicon carbon anode. GAC (601238) Aion LX uses sponge silicon anode chip battery technology for a range of more than 1,000 kilometers. NIO also uses silicon anodes in battery technology.
Power Battery Technology Path (Tianfeng Securities)
Matching the supply and demand of the upstream and downstream of the industrial chain is a sufficient and necessary condition for forming a virtuous circle of the industry.
Downstream recognition, technological breakthroughs, and outstanding advantages have allowed upstream negative players to begin to accelerate the industrialization process with peace of mind. For example, the representative of the existing graphite anode, Bertry (835185) (currently the first domestic market share, shipments of 75,000 tons), Pu Tailai (603659), Shanshan shares (600884) and so on have begun to seek transformation. Of course, there are also battery companies like the Guoxuan Hi-Tech just mentioned that have also begun to extend upstream. In addition, there are players who cut in as upstream silicon material companies, such as Silicon Treasure Technology (300019), Shi Dashenghua (603026), Xinan Shares (600596) and so on.
The trend of dividing the cake is getting worse.
Domestic players laying out silicon carbon anodes (company announcement)
Finally, we take Beiterui, Putailai, Silicon Treasure Technology and Boqian New Materials (actively developing the research and development and promotion of upstream nano-silicon powder) as examples to analyze the financial performance of each company. From the three-factor decomposition of ROE (net asset yield), it can be seen that the ROE of Silicon Treasure Technology shows a trend of increasing year by year, mainly due to the rise of its net interest rate, and then the logic behind it is the price of silicone raw materials in 2018, resulting in its cost rise. Bertry's ROE continued to decline, until last year's significant increase in downstream demand, the performance has improved, as can be seen from the stock price.
Player ROE summary
At present, as some downstream players who pursue black technology have begun to load silicon carbon anodes, the road to industrialization has become smoother and smoother. If all goes well and there is no black swan event, other OEMs will gradually follow suit, and next year may be the year of mass production.
The investment is expected, and the layout should be early. Remember, never when drumming is the last stick of flowers.
Note: This article does not constitute any investment advice. The stock market is risky, and you need to be cautious when entering the market. There is no harm in buying and selling.