the development of solid-state lithium batteries is in a period of industry breaking the shell.

The next gold mine is hidden in the technical route of lithium batteries

As far as the historical process, as small as the industrial development, it has never been achieved overnight.The application of new technology takes a long time to deposit diligence. This is true for photovoltaics, wind power, and lithium batteries.

In the long run, at the cognitive level, the secondary stock market is clearly an afterthought.

The moment when the industry is truly ushering in the highlights in the secondary market is clearly behind the actual development of the industry, and it is necessary for representative companies to grow up and enter the trading stage of the secondary market. After being promoted by founders, pioneers, salesmen, pricers, and followers, it has been widely spread.

Therefore, if you want to be a foresighter, you must always pay attention to the development of the industry.

At the moment, the development of solid-state lithium batteries is in a period of industry breaking the shell. (The lithium battery we often say refers to a lithium battery that uses liquid electrolyte materials, called liquid lithium batteries, and a lithium battery that uses solid electrolyte materials is called solid-state lithium batteries, or solid-state batteries for short.)

the development of solid-state lithium batteries is in a period of industry breaking the shell

Compared with the dullness in the secondary market, solid-state lithium batteries are no less popular in the over-the-counter capital market than liquid lithium batteries. Every few days, there are reports on major production capacity planning, equity participation and cooperation.

For example, recently, Thomas Schmall, a member of the board of directors of the Volkswagen Group, said that the company will spend up to 30 billion euros on the planned European cell factory and securing important raw materials.

Not only that, many companies have thrown out large-scale investments. Automobile groups including BMW, Mercedes-Benz, Volkswagen, Hyundai, Toyota, Honda, and Nissan all regard the field of solid-state lithium batteries as the battery technology direction of their next-generation electric vehicles.

China’s major leaders have also begun the advancement of solid-state lithium batteries.

Ganfeng Lithium (002460.SZ) stated on the investor interaction platform on November 30 that Ganfeng solid-state batteries have been installed on Dongfeng E70 electric vehicles.

Ganfeng solid-state batteries have been installed on Dongfeng E70 electric vehicles

Enjie has invested 1.3 billion yuan in the Jiangsu project to develop solid electrolyte coated diaphragms. Xiaomi and Huawei jointly invested in Weilan New Energy, a supplier of semi-solid batteries.

Good news came from the application side. Weilai’s new sedan ET7 will be equipped with a 150kWh semi-solid battery with an energy density of 360Wh/kg, and the driving range will exceed 1,000 kilometers.

This means that the energy density has been greatly increased on the original basis, and the driving range has been extended. It is reported that Guoxuan Hi-Tech is actively preparing for mass production of semi-solid batteries with a battery life of over 1,000 kilometers.

The competition of solid-state lithium batteries is not only reflected at the enterprise level, but also rises to the game at the government level. Countries around the world are vigorously supporting the R&D and industrial layout of solid-state lithium battery technology.

In Europe, the German government invested 1 billion euros to support the R&D and production of solid-state battery technology, and many automotive leaders have joined the alliance.

In addition, the European Union has jointly invested 3.2 billion euros and raised 5 billion euros from private investors for the development of solid-state batteries. The United States, Japan, and South Korea have all proposed corresponding subsidies and support policies for the development of solid-state lithium batteries.

The reason why most countries vigorously promote the development of solid-state lithium batteries, apart from conforming to the future development direction, is that China’s position on the existing liquid lithium battery track is difficult to shake.

In order to change this situation, some governments need to be one step ahead.

With regard to the advancement of solid-state batteries, the Chinese government has not blindly promulgated corresponding policies earlier.

The leading advantage that China has established in the field of lithium batteries will still enjoy relatively large marginal benefits for a certain period of time. The existing industrial structure takes into account the cost and landing nature, and is the most appropriate choice.

However, slowing does not mean neglect. In the future, lithium batteries will inevitably move forward in the direction of high performance, and solid-state batteries have increasingly become a deterministic development path.

Therefore, while enjoying the dividends of the liquid lithium battery industry, we must also actively develop new technologies.

while enjoying the dividends of the liquid lithium battery industry, we must also actively develop new technologies

In November 2020, the “New Energy Automobile Industry Development Plan (2021-2035)” issued by the Chinese government clearly requires “accelerating the R&D and industrialization of solid-state power battery technology.”

Then, the question arises, what are the advantages of solid-state batteries? From the enterprise to the country, all efforts are made on the solid-state battery track.

What is the current development status? We must know that the current liquid lithium battery technology is developing in full swing. What are the future prospects?

This report aims to explain the above questions that linger in the minds of investors.

Disappearing electrolyte

In order to clarify these problems, it is inevitable to conduct comparative studies on various aspects of liquid lithium batteries and solid-state lithium batteries.

First of all, both are lithium batteries, the principle is also similar, the difference is that the battery composition is different.

The current composition of liquid lithium batteries includes four major materials: positive electrode, negative electrode, electrolyte, and separator. The composition of solid-state batteries includes three major materials: positive electrode, negative electrode, and electrolyte.

The difference is obvious. The solid-state lithium battery replaces the original electrolyte and diaphragm with a solid-state electrolyte.

The solid-state lithium battery replaces the original electrolyte and diaphragm with a solid-state electrolyte

The core elements that affect the promotion and application of lithium batteries are nothing more than three aspects, safety, performance, and cost.

First of all, we start with safety. The existing liquid lithium batteries have been criticized for a long time in terms of safety. The working principle of liquid lithium battery clearly explains why.

After a while, it was tired from playing and wanted to go home, but it didn’t have the energy. At this time, it needs to be charged. After charging it, it will have the energy to swim back to its home at the negative electrode.

However, to go home can not be delayed for too long, you need to charge quickly, the temperature rises significantly during fast charging, which makes more lithium ions want to go home.

However, there are not enough beds in the negative electrode home. Homeless lithium ions can only sleep outside and precipitate on the surface of the negative electrode to gradually form dendritic lithium, which may pierce the electrolyte, cause a short circuit, and cause an accident.

Dendrites form on the negative electrode of the battery

Presumably, readers are no strangers to the fire incident of new energy vehicles.

According to statistics, there will be 45 new energy vehicle recalls in 2020, involving 357,000 vehicles, accounting for 5.3% of the total number of recalls for the year, of which 112,000 vehicles were recalled due to defects in the three-electric system, accounting for 31.3% of the total number of new energy vehicle recalls .

It can be seen that the power battery is an important hidden danger to car safety. The promotion of solid-state batteries starts here.

One obvious difference between solid-state lithium batteries and liquid lithium batteries is that they do not use flammable electrolyte, which is often the main cause of fires in new energy vehicles.

Electrolyte is the current conducting medium used in stages, but it does not mean that it is optimal. Its structure principle has problems such as temperature sensitivity, product decomposition at high temperatures, strong corrosiveness, flammability and easy leakage.

After a short circuit occurs, the liquid electrolyte inside the lithium battery is ignited due to a large increase in local temperature.

Even if the method of adding flame retardant and high temperature resistant film is adopted at this stage, the safety problem of the battery has not been effectively solved.

The solid-state lithium battery uses a non-flammable solid electrolyte as a conductive medium.

The most prominent advantage is safety, and it reduces the sensitivity of the battery pack to temperature and eliminates short circuits caused by high and low temperature problems caused by precipitation. With good insulation, the positive and negative electrodes are effectively blocked.

Relying on the shape and material of the electrolyte, it solves the problem of flammability, and also brings about the difficulties of low conductivity and high resistance.

It is not difficult to understand that in the liquid environment, the lithium ion movement is more smooth, and the contact between the solid material and the positive and negative electrodes is not as close as that of the liquid material, and the fast charging performance is not good.

For example, one bottle is filled with water and the other bottle is filled with paper. The space in the former bottle is obviously less than that in the latter.
Obviously, the replacement of electrolyte is not only the conversion of liquid to solid, in addition to safety, it also needs to achieve higher capacity density enhancement. At this time, there are more stringent requirements for material performance, which is a comprehensive consideration of stability, conductivity, cost, and technology.

The electrolytes of solid-state batteries that are currently in use or are close to commercial use are: polymer, sulfide, and oxide.

The electrolytes of solid state batteries that are currently in use or are close to commercial use are polymer, sulfide, and oxide

Polymers are easy to be electrolyzed under the working voltage of 4V and above, even if they have good contact with the positive and negative electrodes, it is difficult to be a big responsibility.

Sulfide overcomes the bottleneck of poor conductivity of solid electrolyte, but has higher resistance. It is easy to have side reactions with air, water, etc., and there are still many challenges to overcome in the process.

Oxide performance is among the two, and it has become an ideal material at the current stage by virtue of its comprehensive performance.

Due to differences in technology understanding, mastery, and development, the choice of technology path is quite controversial.

Ganfeng Lithium, Taiwan Huineng, Qingtao Energy and others have laid out oxide solid-state battery technology routes.

Japanese and Korean companies mostly use the sulfide solid electrolyte technology route; Chinese companies mostly use the oxide route; European and American companies have diversified choices. For example, Solid Power mainly takes the sulfide route, and Quantum Scape chose the oxide route.

Radar chart of different solid electrolyte performance

Break the energy density bottleneck

When it comes to performance, the performance of liquid lithium batteries is not satisfactory.

With the gradual penetration of new energy vehicles, they have begun to play an important role in long-distance travel during holidays. However, the performance results are very poor. A piece of news on the long holiday of November this year illustrates the problem well.

According to China Finance and Economics, on October 1, a new energy vehicle owner returning from Shenzhen to Hunan spent more than five hours charging the vehicle in the service area.

“During these four hours, I didn’t even dare to go to the bathroom because I was afraid of being cut in the queue. At that time, there were more than 20 cars in the line. Forget it, I had to line up for at least three hours to persuade many cars behind me. Return.”

For a long time, battery life and fast charging are the beautiful and embarrassing facts of liquid lithium batteries. How to improve battery life and fast charging capabilities is the crux of further accelerating the penetration rate.

According to China’s “Energy-saving and New Energy Vehicle Technology Roadmap 2.0” released in October 2020, the annual energy density target of China’s pure electric vehicle power batteries in 2025 is 400Wh/kg, and the target in 2030 is 500Wh/kg.

However, the energy density of ternary lithium batteries in China is currently striving to exceed 300Wh/kg, while the upper limit of the energy density of lithium iron phosphate batteries is about 180Wh/kg.

China's ternary lithium battery energy density is striving to break through

However, the energy density of ternary lithium batteries in China is currently striving to exceed 300Wh/kg, while the upper limit of the energy density of lithium iron phosphate batteries is about 180Wh/kg.

From this point of view, under the current lithium battery technology, it is difficult to achieve future energy target demand by the path of high nickel alone. Even if more efficient batteries such as 9* are launched, limited by materials, it is a real task to accumulate qualitative changes. difficult.

So, is there a better solution to increase energy density? After we further studied the factors that affect energy density, we found the answer.

The theoretical energy density of lithium batteries mainly depends on the gram capacity of the anode and cathode materials and the working voltage. It can be found through research that the greater the voltage, the greater the energy density.

It is not difficult to understand that when a lithium battery is working, the battery voltage will drop with the decrease of power. Assuming other conditions remain the same, under the same current, the working time of high voltage is obviously longer than that of low voltage.

An analogy: a higher reservoir can hold more water, and it will take longer to drain with the same faucet.

Then, it means that the energy density of lithium batteries can be enhanced by increasing the operating voltage.
However, due to current liquid lithium battery materials and safety limitations, the voltage difference between the positive and negative electrodes is generally within 4.2V. Therefore, it is difficult to achieve this with current materials.

Another key indicator is the specific (gram) capacity. As the name suggests, its meaning is how much mAh (milliampere hour) the lithium battery material contains per gram.

The larger the specific capacity, the higher the energy density.

Simply put, it means that the same weight carries more lithium ions, and the more lithium ions participate in the chemical reaction, the greater the energy. However, the existing positive and negative electrode materials for liquid lithium batteries also pose certain constraints on future demand.

Comparison of specific capacities of different positivenegative terminals

In addition to improving the safety performance of solid-state batteries, it also breaks the bottleneck that restricts the energy density of lithium batteries.

From the voltage point of view, the negative electrode can effectively increase the voltage difference to 5V after using metal lithium in the future, which will undoubtedly increase the endurance.

From the point of view of specific capacity, the specific capacity of metallic lithium can reach 3860mAh/g.

This is equivalent to arranging a five-star villa for Li-ion, and the existing graphite is only 365mAh/g, which can barely maintain the living conditions, and there may be no berths when they come back late. The difference between the two is clear at a glance.

In the future, materials with high specific capacity such as lithium-rich manganese-based materials will also be used in the development of positive electrodes. Obviously, the application of high specific capacity materials is the only way to further increase the energy density.

Technology path difference

This link often determines success or failure, and if the best technology cannot effectively reduce costs, the replacement is nothing but empty talk.

According to Nissan’s plan, the 2028 all-solid-state battery can reduce the cost of the battery pack to US$75 per kilowatt-hour (equivalent to approximately RMB 478), and will further reduce the cost to US$65 per kilowatt-hour (equivalent to approximately RMB 413) in the future.

However, the current cost of ternary lithium batteries exceeds 1,000 yuan/kWh. Given the shortage of raw materials in the future, the room for cost reduction is not optimistic.

From this point of view, if solid-state batteries develop as expected, there will be a broad alternative market. Then, the next question comes to the choice of a specific technical path.

At this stage, solid-state batteries will still use the positive and negative electrodes of liquid lithium batteries, instead of electrolytes and separators. Then, what determines the difference in the technological path is the difference in the choice of electrolyte.

As mentioned above, in the current main electrolyte technology path, because the polymer is easy to be electrolyzed under the working voltage of 4V and above, and it needs to exceed room temperature to work normally, even if it has been mass-produced, it is not a future technology choice.

Oxides are mainly classified into thin-film and non-thin-film types.

The thin-film type mainly uses LiPON (lithium phosphorus oxide nitrogen) as the electrolyte material, while the non-film type refers to crystalline oxide electrolytes other than LiPON. Among them, LLZO (lithium lanthanum zirconium oxide) is the mainstream .

Thin-film products have excellent performance and have been used in relatively primary and small-scale applications in the fields of microelectronics and consumer electronics.

However, the capacity of thin-film batteries is small, often less than the mAh level, which is barely enough in the fields of microelectronics and consumer electronics. When it reaches the Ah level of passenger cars, the shortcomings are fully exposed.

The industry has tried to increase the battery capacity by adding battery packs in series and parallel, but there are problems such as high cost and process difficulties.

However, non-film oxide products have excellent overall performance and are currently popular for development.

It has become a key development direction for Chinese companies, and Taiwan Huineng and Jiangsu Qingtao are both leading companies on this track. Some products have been put on the market, but there are also disadvantages that the ion conductivity is lower than that of the film type.

Another technological path for capital focus is sulfide batteries

Sulfides mainly include thio-LISICON, LiGPS, LiSnPS, LiSiPS, Li2S-P2S5, Li2S-SiS2, Li2S-B2S3, etc., and their conductivity is close to or even higher than that of organic electrolytes.

At the same time, it has the characteristics of high thermal stability, good safety performance, and wide electrochemical stability window (up to 5V). It has outstanding advantages in high power and high and low temperature solid-state batteries.

However, most sulfide materials have poor air stability and will react with water to form irritating hydrogen sulfide gas. It can be said that its development potential is the greatest, and it is also the most difficult.

In the production process, coating + multiple hot pressing and adding a buffer layer are required to improve the interface performance.

In addition, new materials are constantly being introduced. A few months ago, a new solid electrolyte material for lithium batteries-lithium zirconium chloride was designed and synthesized by Ma Cheng’s team, a professor at the University of Science and Technology of China.

According to reports, the advent of lithium zirconium chloride has successfully reduced the cost of raw materials with a thickness of 50 microns to 1.38 US dollars per square meter, while the corresponding cost of the cheapest chloride solid electrolyte before this was 23.05 US dollars per square meter.

It is reported that the raw material cost of 10 US dollars per square meter is the limit for solid electrolytes to be competitive. Of course, the problem also exists. Poor stability is the key to restricting its industrialization development. The team is currently working hard to overcome this link.

From the perspective of the development direction of the solid-state lithium battery industry in the future, the industry’s cognition is not much different, basically from the liquid lithium battery-semi-solid-solid state; the replacement of the electrolyte separator is completed first, and then the positive and negative electrodes are replaced.

Solid-state battery development strategy

In order to solve the problem of interface contact inside the all-solid-state battery, and at the same time make full use of the existing liquid lithium-ion battery production process and equipment to reduce manufacturing costs. The current technical route of solid-state batteries is to give priority to the development of hybrid solid-liquid lithium batteries, gradually reduce the content of liquid electrolyte, and finally realize all-solid-state lithium batteries.

It can be said that the process route of solid-state batteries is still immature, the industrialization still takes time, and the road to cost reduction is long.

But on the other hand, under the trend of capital promotion, broad technology paths, and talent focus, it is expected to accelerate the production learning curve, shorten the process know-how time, and the arrival of industrialization may exceed expectations.

It is predicted that solid-state battery shipments will grow rapidly from 2020 to 2030, and global demand is expected to reach 1.7 GWh, 44.2 GWh, and 494.9 GWh in 2020, 2025, and 2030, respectively. The global market space is expected to reach 150 billion yuan in 2030. above.


Under the background of high demand for new energy vehicles, the competition for power batteries is particularly fierce. Although liquid lithium batteries are currently dominating one side, sodium batteries, aluminum batteries, hydrogen fuel cells, and solid-state lithium batteries have all launched challenges.

However, just as a hundred schools of thought have brought about academic prosperity, various technological paths have found their own application directions in the fields of energy storage, commercial vehicles, and passenger cars.

What is certain is that the competition of multiple technological paths is beneficial to the development of the industry, which is expected to shorten the industry’s cognitive time and promote the healthy development of the industry.

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