How far is the commercialization of solid-state batteries?

In the process of accelerating the transformation of transportation electrification driven by the "dual carbon" goal, power battery innovation has become the key to strengthening the competitive level of new energy vehicles, building national industrial competitiveness, and consolidating corporate competitive advantages. Since the beginning of this year, both vehicle companies and power battery companies have targeted new technologies and laid out a new generation of power batteries - solid-state batteries, and accelerated the release of the solid-state battery "on-board" schedule.

Rush to release the "on-board" schedule

Toyotas long-silent solid-state batteries have made some moves and hopes again. On June 28, Toyota announced the progress of the new generation of electrification technology. A total of four new generation batteries, including performance lithium-ion batteries, popular lithium iron phosphate batteries, high-performance lithium-ion batteries and all-solid-state batteries, will be put on the market in turn from 2026. Among them, all-solid-state batteries are fully promoting research and development with the goal of launching in 2027-2028. It is reported that the range of models equipped with solid-state batteries will reach more than 1,000 kilometers, and fast charging only takes 10 minutes.

Previously, Zhiji Auto, a subsidiary of SAIC Motors, launched the industrys first quasi-900V ultra-fast charging solid-state battery - the first generation of Light Year solid-state battery, and it was first used in Zhijis new sedan Zhiji L6. Subsequently, SAIC Motors announced that "the countdown to the completion of the first all-solid-state battery production line has officially started at 500 days", and SAICs all-solid-state battery based on the polymer-inorganic composite electrolyte technology route will be mass-produced in 2026.

At the same time, GAC Group released an all-solid-state battery on Science and Technology Day. It is understood that this all-solid-state battery uses the third-generation sponge silicon negative electrode and high-area capacity solid-state positive electrode technology, and its energy density can reach more than 400Wh/kg. Compared with the current mass-produced liquid lithium-ion battery, the volume energy density is increased by more than 52%, and the mass energy density is increased by more than 50%, which can easily achieve a range of more than 1,000 kilometers. GAC Group stated that it will complete the development of all-solid-state batteries in 2026, and will first be installed on its Haobo models.

As a global leader in power batteries, CATL also announced the research and development and mass production schedule of all-solid-state batteries for the first time in April this year. "CATLs goal is to produce all-solid-state batteries in small batches by 2027, because mass production will still face cost and other issues." CATL Chief Scientist Wu Kai is still cautious about this. "If technology and manufacturing maturity are used as the evaluation system (scored from 1 to 9), the companys all-solid-state battery research and development is currently at a level of 4 points."

Compared with traditional lithium-ion batteries, all-solid-state batteries are generally considered to be the preferred solution for the next generation of new energy power battery technology internationally due to their potential safety, high energy density, high power characteristics and temperature adaptability. At present, all countries are increasing their investment in tackling this disruptive technology. Sorting out the all-solid-state battery industry timetable released by domestic and foreign companies, industrialization is mainly concentrated in 2027 to 2030. For example, South Koreas SK On said that it is developing two solid-state batteries, polymer oxide composites and sulfides, with the goal of producing prototype products by 2026 and commercializing them in 2028. Samsung SDI is also developing a solid-state battery without a negative electrode, which is expected to be mass-produced in 2027.

Semi-solid batteries are not equal to fully solid-state batteries

In recent years, with the rapid development of the new energy vehicle industry, the industry has become increasingly aware of the limits of traditional liquid lithium batteries. For example, the upper limit of energy density is low, which cannot eradicate consumers mileage anxiety; the overall battery mass is large; low-temperature operation is not smooth, and there are safety hazards in high-temperature environments. Therefore, the industrys call for solid-state batteries to be "installed on the car" is growing.

However, just as companies are accelerating the release of the solid-state battery "installation" schedule, controversy about the concept of solid-state batteries has also followed. After Zhiji Auto launched the news of solid-state batteries "installed on the car", many industry insiders told reporters that the light-year solid-state battery released by Zhiji Auto is actually a semi-solid-state battery.

This was also confirmed by Li Zheng, co-founder of battery supplier Qingtao Energy: "In order to enhance the lithium ion conductivity of solid electrolytes, Qingtao Energy added 10% of infiltration liquid to the electrolyte, which reduced the total liquid content by about 5% compared with traditional ternary lithium batteries. The light-year solid-state battery launched by Zhiji Auto is actually a semi-solid-state battery." According to the different content of electrolyte liquid, batteries can be divided into four categories: liquid (liquid content 10wt% to 25wt%), semi-solid (liquid content 5wt% to 10wt%), quasi-solid (liquid content 0wt% to 5wt%) and full solid (liquid content 0wt%). "Semi-solid batteries are a transitional product between liquid batteries and solid-state batteries and cannot be directly called solid-state batteries." Cui Dongshu, secretary-general of the National Passenger Car Association, made it clear. But the reality is that most of the new battery technology concepts released by companies are being put into this "basket". At present, there are three mainstream technical routes for solid-state batteries, including polymer solid-state batteries, oxide solid-state batteries and sulfide solid-state batteries. Overseas companies such as Japan, South Korea, Europe and the United States prefer the sulfide technology route and are committed to the development of all-solid-state batteries, and the industrialization process is relatively slow; while most domestic companies choose the oxide technology route, and most of the products they develop are semi-solid-state batteries.

"Both domestic car companies and battery suppliers currently have the mass production capacity of semi-solid-state batteries, and it is expected that large quantities of them will be "installed on vehicles" in 2025. However, all-solid-state batteries are still in the breakthrough stage of positive and negative electrode materials. Due to the unresolved problems of materials, mass production has not been achieved in recent years." Zeng Yuqun, chairman of CATL, said.

"From the perspective of the entire industry, China must develop this gradual semi-solid-state technology route, and guard against the subversive risks brought by the radical all-solid-state technology route." Perhaps it is precisely because of this controversy among the people that Ouyang Minggao, an academician of the Chinese Academy of Sciences and a professor at Tsinghua University, particularly emphasized the difference between "semi" and "full" when talking about solid-state batteries.

In his opinion, the industrialization of all-solid-state batteries should aim at 300Wh/kg (weight specific energy) and 600Wh/L (volume specific energy) in the near future, and open up the entire technology chain of all-solid-state batteries. In the medium term, it should aim at 500Wh/kg and 1000Wh/L, and realize commercialization before 2035. "The time for large-scale industrialization is not a sample in the laboratory, nor a paper. The so-called near term is 3 to 5 years, and the medium term is 5 to 10 years." Ouyang Minggao explained.

Three major challenges need to be solved urgently

Compared with the optimism of enterprises, industry experts are slightly conservative about the commercialization process of all-solid-state batteries. "This is because it is difficult for all-solid-state batteries to balance the bottlenecks of battery life and safety, and it is difficult to break through the glass ceiling of battery technology." Ouyang Minggao said that the challenges faced by all-solid-state batteries are interdisciplinary, with extremely high technical barriers, covering materials, interfaces, processes, industrial chains, equipment and other issues.

The first is the scientific and technological challenges of all-solid-state batteries. At present, the industrialization of all-solid-state batteries still needs to be solved from different levels of key materials, interfaces, composite electrodes, and single cells.

At the material level, sulfide electrolytes have poor chemical stability and air stability, making mass production difficult, and the cost of basic lithium sulfide is high. At the same time, silicon-carbon negative electrodes have the problem of large volume expansion, while lithium negative electrodes are not yet mature. At the interface level, the interface compatibility of electrode materials and solid electrolytes is insufficient, including interface side reactions and solid-solid interface mechanical contact. At the electrode level, the charge transport under high-surface-load composite electrode strain conditions is slow. At the electric chip level, the environmental control cost is high and the production efficiency is relatively low. In addition, there is no relevant evaluation standard for the comprehensive evaluation of battery cell performance under vehicle-mounted conditions.

The second is the process equipment challenge of all-solid-state batteries. "If we use a wet process, we can probably keep half of the existing equipment. If we use a dry process, two-thirds of the equipment will be unusable and we have to replace it with new equipment." Ouyang Minggao said.

The last is the challenge of the industrial chain. From the supply perspective, my country has basically built a complete liquid lithium-ion battery industry ecosystem, covering all aspects from upstream mineral resources, material manufacturing, battery production, vehicle application to recycling. The main supply chain of liquid lithium-ion batteries has achieved independent control. If all-solid-state batteries are developed, it will have a significant impact on the existing battery industry chain throughout its life cycle.

Regarding the choice between solid-state and liquid batteries, Ouyang Minggao also said: "Japan and Europe are developing all-solid-state batteries to subvert Chinas advantages. We are just the opposite. We must maintain our advantages and prevent subversion. We must strive to conquer all-solid-state batteries while also optimizing liquid lithium-ion batteries."