The Puzzle of Solid-State Batteries

Imagine that new energy vehicles can easily achieve a cruising range of over 1,000 kilometers, significantly reduce charging time, and eliminate the risk of fire and explosion... The blueprint outlined by solid-state batteries is extremely appealing to all players in the new energy field.

At this technological transformation juncture, a battle for the future energy landscape has quietly begun. From automobile manufacturers to battery producers, from research institutions to the capital market, the solid-state battery sector is ablaze with competition.

Recently, a research team from the Chinese Academy of Sciences has achieved multiple technological breakthroughs, which are expected to solve the "bottleneck" problems of all-solid-state batteries. The industry has also brought good news. Mercedes-Benz was the first to announce the completion of a test for an all-solid-state battery with a cruising range of over 1,000 kilometers; Chery released its self-developed all-solid-state battery module for the first time; and Toyota's solid-state battery has officially obtained production permission in Japan.

In the past few years, the concept of solid-state batteries has been a hot topic in academia, the industry, and even the capital market. However, despite frequently making headlines, it has a bit of a "crying wolf" feeling - the prospects are infinite in the publicity, but in reality, it is still stuck on key problems such as materials and costs, and the actual commercial mass production is still a long way off. Jiemian News reported that to prevent the market from confusing semi-solid-state batteries with solid-state batteries, relevant authorities are planning to issue a new document to uniformly name "semi-solid-state batteries" as "solid-liquid batteries."

So, the question is, has the inflection point of this energy revolution really arrived?

The Technological Inflection Point Has Arrived

Different from liquid batteries that use a mature system, solid-state batteries represent a comprehensive innovation in material systems and manufacturing processes. Therefore, solid-state batteries also have more advantages compared to liquid batteries: no need to worry about thermal runaway and relatively safe; higher energy density and longer cruising range; able to adapt to extreme environments and faster charging, etc.

Among them, cruising range and safety are the core concerns of current new energy vehicle consumers. The former directly determines travel convenience, while the latter is an important source of security for choosing electric vehicles.

Especially recently, there have been several incidents of new energy vehicle spontaneous combustion, impact explosions, etc., involving different automobile manufacturers, which means that safety issues are not isolated cases. Solid-state batteries can specifically solve this problem, so they naturally become the technological direction expected by the market and may even become a key variable affecting the further penetration of new energy vehicles.

However, although solid-state batteries have many advantages, they have not been mass-produced for vehicles so far. It is not that automobile manufacturers "don't want to do it," but rather "can't do it." There are still many unsolved problems for solid-state batteries to achieve technological breakthroughs and mass production.

To put it simply, lithium batteries that have been mass-produced for vehicles, that is, liquid batteries, have essential differences in structure and performance from solid-state batteries, resulting in significant gaps in safety and cruising ability between the two.

The organic solvents in liquid batteries are flammable and highly corrosive. As a result, once a lithium battery is impacted, exposed to water, or subjected to high temperatures, it may cause combustion, explosion, etc. Solid-state batteries, on the other hand, partially or completely replace the original electrolyte with a solid electrolyte, which can greatly improve the safety and energy density of the battery.

According to the different contents of electrolyte, batteries can be subdivided into four categories: liquid (25%), semi-solid (5% - 10%), quasi-solid (0% - 5%), and all-solid (0%). Currently, many automobile manufacturers or battery companies claim to have achieved "solid-state batteries in vehicles." However, whether it is semi-solid or all-solid, although it seems to be just a one-character difference, the technological content and performance are far from each other.

Wu Kai, the chief scientist of CATL, pointed out that to achieve the industrialization of all-solid-state batteries, four major problems need to be solved: the solid-solid interface, the application of lithium metal anodes, the instability of sulfide electrolytes in the air and the relatively high synthesis cost, and the production process of all-solid-state batteries.

The primary problem is the contact at the solid-solid interface. Due to the small contact area between the cathode material and the solid electrolyte, the transmission efficiency of lithium ions is affected, resulting in a decline in battery performance and a shortened lifespan. In addition, poor interface contact can easily form lithium dendrites, which can pierce the solid electrolyte during the charge-discharge cycle and easily cause an internal short circuit.

Recently, a team led by researcher Huang Xuejie from the Institute of Physics of the Chinese Academy of Sciences, in collaboration with multiple institutions, developed an anion regulation technology, which solved the problem of the difficult close contact between the electrolyte and the lithium electrode in all-solid-state lithium metal batteries.

The Huang Xuejie team introduced iodine ions into the electrolyte, which can be regarded as a "special glue." When the battery is working, it can actively attract lithium ions and automatically fill all the gaps and holes, keeping the electrode and the electrolyte in close contact at all times.

The researchers also conducted a detailed characterization of the battery interface after cycling and found that the doped electrolyte maintained close physical contact after cycling, with no holes or lithium dendrites formed, and the performance remained stable after hundreds of charge-discharge cycles.

Secondly, there have been new breakthroughs in solid-state battery materials. A research team from the Institute of Metal Research of the Chinese Academy of Sciences used the design flexibility of polymer molecules to prepare a new material that achieves interface integration at the molecular scale and can resist tension and pulling;

A research team from Tsinghua University used fluorinated polyether materials to modify the electrolyte, and the "fluoride protective shell" formed can prevent the electrolyte from being "punctured" at high voltages.

Finally, in terms of raw materials, the price of sulfide electrolytes has dropped significantly in the past two years, from 70,000 - 80,000 yuan per kilogram in 2023 to 10,000 - 20,000 yuan per kilogram in 2025. The industry expects it to drop to 7,000 yuan per kilogram in 2026.

Some material companies have also developed a new synthesis process for lithium sulfide, which is expected to further reduce the manufacturing cost of sulfide solid electrolytes and provide conditions for the commercial mass production of all-solid-state batteries.

Mass Production and Delivery in 2027?

Favorable news has been frequently reported in the laboratory, and the industry has also given a clear timeline. The year 2027 has become a key node for the mass production of solid-state batteries.

Currently, the all-solid-state batteries of global leading manufacturers such as CATL, Gotion High-Tech, Toyota, and Samsung SDI have all entered the trial production stage, and each has given its own mass production timeline.

CATL plans to achieve small-scale mass production in 2027; Gotion High-Tech has entered the pilot mass production stage and has started the design work for a 2GWh mass production line; Sunwoda aims to achieve an energy density of over 500Wh/kg for all-solid-state batteries in 2027; and Toyota has stated that it will launch pure electric vehicles equipped with all-solid-state batteries between 2027 and 2028.

However, it is worth noting that most leading companies are referring to small-scale mass production, which means that it is still quite difficult to truly promote the use of solid-state batteries in vehicles.

The commercial application of solid-state batteries is not just a matter of the efforts of research teams. It also involves the formulation of process standards, the control of the stability of mass production yield, and the connection and adaptation with the production end of downstream automobile manufacturers. It is a huge systematic project.

Firstly, the requirements for production processes and equipment for solid-state batteries are much higher than those for liquid batteries. Data shows that the cost of liquid lithium batteries is about 100 - 150 US dollars per kWh, while the cost of solid-state batteries is 400 - 800 US dollars per kWh, 3 - 4 times that of lithium batteries.

Currently, the technology of solid-state batteries is not yet fully mature, which means that most battery factories still need to go through a test stage of "high cost input and low production efficiency" before they can optimize the cost curve.

Secondly, the implementation of the production line is another major challenge. The production line for all-solid-state batteries is quite different from that for liquid batteries. Special equipment needs to be developed, and the entire production line needs to operate in an ultra-dry environment.

Such a high-cost and high-uncertainty investment obviously cannot be completed by individual battery manufacturers alone. It also requires the standardized advancement and interest balance of the entire industrial chain.

To put it simply, relevant policies need to be implemented and promoted, and there needs to be a large-scale demand in the new energy vehicle market. Only by unifying technical standards and sharing the upfront investment costs can the uncertainty in each link be reduced and the production line be truly implemented.

Finally, the cooperation between battery factories and automobile manufacturers is also crucial. Before solid-state batteries are used in vehicles, automobile manufacturers need to conduct multiple rounds of assessments on the quality, lifespan, and safety of the batteries; after officially entering production, the yield rate and supply chain stability of solid-state batteries will determine whether they can be truly mass-produced on a large scale.

Therefore, for solid-state batteries to truly emerge from the laboratory, it is not just a matter of automobile manufacturers and battery producers talking on their own. It requires the joint promotion of the entire industrial chain. It should be a "shared joy," not a "solitary joy."

Not Necessarily Solid-State Batteries

However, at a time when the concept of solid-state batteries is hot, CATL stated at its Q3 2025 earnings conference that "it will not disclose the progress of solid-state batteries for the time being and will leave it to time to prove."

Even earlier, there were widespread rumors that "CATL plans to mass-produce solid-state batteries with an energy density of 450Wh/kg in 2027." CATL even came forward to refute the rumor, stating that solid-state batteries still need to face a series of engineering problems. It is expected to achieve small-scale trial production in 2027 and large-scale mass production and commercial application around 2030.

CATL has a bit of a "remaining sober while others are drunk" attitude. One reason is that CATL has enough "cards" in its hand and is strong enough, so it has no intention of riding on the wave of solid-state batteries.

In April this year, CATL released three revolutionary power battery products. Among them, the world's first mass-produced sodium-ion battery can maintain 90% of its energy at a low temperature of -40°C, further breaking the resource boundary.

This also means that the new energy industry has entered a multi-core era. Although all-solid-state batteries are good, they are not the only solution for pure electric vehicles. In the future, the batteries installed in pure electric vehicles may present a "graded adaptation" pattern:

All-solid-state batteries have no short - comings in terms of cruising range, performance, charging, and safety, but they are relatively expensive and are more likely to be installed in high - end pure electric vehicles;

The overall material cost of sodium - ion batteries is 30% - 40% lower than that of lithium batteries. They perform better at low temperatures, but have a shorter cycle life and generally lower energy density than lithium batteries. They are more suitable for entry - level products or energy storage scenarios that require low - temperature startup. After comprehensively considering the balance between practicality and cost, technologically mature lithium batteries will cover most mainstream models.

Therefore, although solid - state batteries represent the future direction of battery technology, automobile manufacturers do not have to bet on solid - state batteries. With the increasing maturity of various energy - replenishing methods such as fast charging and battery swapping, automobile manufacturers can completely build their competitiveness by optimizing existing battery technologies and deploying a diversified energy - replenishing ecosystem.

In contrast, solid - state batteries are expected to break through the incremental ceiling first in the low - altitude economy and the robotics field. These products have basically the same requirements for battery safety, cruising range, and density as the automotive field, but are less price - sensitive, providing a large - scale application scenario for the early commercialization of solid - state batteries.

GGI predicts that the demand for humanoid robot batteries will exceed 100GWh by 2030, with a compound annual growth rate of over 100% from 2025 to 2030. Currently, many battery manufacturers have started to deploy in the robotics field. For example, Sunwoda is developing high - rate solid - state batteries to meet the dynamic needs of robots; Funeng is collaborating with Mercedes - Benz to develop semi - solid - state batteries, which are currently being tested on robot platforms.

These early commercialization attempts have accumulated key data and experience for the technological iteration, cost control, and ultimate entry into the broader electric vehicle and energy storage markets of solid - state batteries. With more industrial chain enterprises joining, it is expected to form a positive cycle of "technological improvement - scenario expansion - cost reduction - larger - scale application" to accelerate the development of solid - state batteries.

Looking globally, countries are accelerating in the solid - state battery race, and the power of science is gradually overcoming the "tough problems." However, before the market cheers, the industry still needs to rationally view its commercialization process. Solid - state batteries are not "universal batteries," and there is not just one answer for technological iteration and industrial upgrading in the energy field.