The battery revolution: How far is solid-state battery from mass production?

The development of batteries has gone through nearly two hundred years of history, and now lithium-ion batteries are the most outstanding secondary energy storage batteries. High operating voltage, fast charge, and discharge characteristics, long cycle life, no memory effect, and many other advantages make it the first choice for large-scale applications in today’s digital products and electric vehicles.

Although the performance of lithium-ion batteries is excellent, the development also has challenges and obstacles that are difficult to overcome: the structural characteristics of batteries limit the performance of batteries. The existing battery structure is the root cause of battery aging and safety hazards.

The principle of battery power generation is that the two electrode materials exchange ions with each other in the electrolyte, but because of this structure, the reaction interface will always exist, and the battery is always in a working state, resulting in a situation of easy aging and safety hazards.

For example, the fact that electric vehicles stall in winter is because the performance of the battery fails under low-temperature conditions. Material scientists and battery engineers have proposed many approaches to battery materials. For example, a large amount of organic solvent is mixed into the electrolyte to reduce the solidification temperature of the electrolyte. However, this makes the electrolyte more flammable, sacrificing the safety of the battery.

Some scientists have also tried to replace the electrode material, but the energy of the battery has increased, but it cannot resist thermal runaway; fast charging will cause the battery interface to be too flammable, and its safety cannot be guaranteed. It is solved from the system idea of optimizing battery management, but it brings about a decrease in energy density and an increase in unit cost.

In order to make the battery adaptable to low temperature, high activity, and high-temperature stability, it seems that the battery cannot have the best of both worlds. Energy density, safety, fast charging, and other elements cannot be perfectly integrated into the battery. If these problems are solved, the scale development of new energy vehicles will revolutionize and reshape the automobile industry for a century.

Therefore, the ultimate development goal of power batteries is also compatible with the advantages of safety, high energy density, good cycle performance, and fast charging speed.

As the new terminator of lithium batteries, solid-state batteries are becoming the trump card for new energy vehicles to kill fuel vehicles.

Power battery’s evolution

When new energy vehicles can replace fuel vehicles, the accepted answer in the power battery market is that the energy density of the battery system of existing electric vehicles has to be doubled, from the common 160wh/kg to 400wh/kg. To solve the energy density problem of batteries, the solution must be the innovation of power batteries.

We know that the mainstream power batteries in the electric vehicle market are ternary lithium batteries and lithium iron sulfate batteries. If they are classified according to the physical state of the electrolyte, these two batteries are typical liquid batteries. If you want to eliminate mileage anxiety and innovate the new energy vehicle market, the performance characterization of solid-state batteries is the goal of power battery development. Solid-state batteries are also known as the new development direction of lithium batteries in the future.

The popular choices in the field of power batteries are ternary lithium and lithium iron sulfate, which are not perfect choices. Ternary lithium battery, high energy density, but poor high-temperature resistance, lithium iron phosphate battery, high safety, but the upper limit of energy density is low. Liquid lithium-ion batteries generally have safety hazards such as electrolyte oxidation, electrode expansion, and high-temperature runaway, and can only sacrifice energy density in exchange for stability. The solid-state battery can be compatible with the shortcomings of both: it can not only meet the needs of energy density but also take into account safety.

As for solid-state batteries, because solid-state materials are used as electrolytes, they have no continuous reaction interface, and by-products will not dissolve in the interface, so it will have better stability and cycle characteristics. At the same time, the drying and leakage problems faced by liquid electrolytes will not exist. This makes solid-state batteries far superior to ternary lithium batteries and lithium iron phosphate in terms of safety and life cycle.

In addition, solid-state batteries have the characteristics of high-temperature resistance, no corrosion, small size, and high energy density, which avoid the main weaknesses of traditional liquid lithium batteries. According to reports, a solid-state car has a cruising range of up to 1,000 kilometers, and it only takes 10 minutes to charge. Over time, the solid-state battery will deteriorate less.

All-solid-state batteries using solid electrolytes are relatively safer and have better performance, while traditional liquid lithium-ion batteries are gradually unable to meet the standards of advanced technology: it can improve cruising range and be safer. Therefore, all-solid-state batteries have become a new development trend in the power battery industry.

New entrants one after another: the market opportunity

In November 2020, the “New Energy Vehicle Industry Development Plan (2021-2035)” issued by the General Office of the State Council clearly requires that the R&D and industrialization of solid-state power battery technology be accelerated. It is predicted that by 2030, the global solid-state battery market will exceed 6 billion US dollars (about 38.3 billion yuan), and the Chinese market will account for more than 50%.

The good performance indicators of solid-state batteries in the laboratory mean rich commercial value, which has also become the driving force for enterprises to accelerate their layout and seize the commanding heights of technology. Domestic and foreign enterprises and institutions have put on the agenda for the research and development and mass production of power batteries.

Toyota’s plan for power batteries is also earlier. Toyota’s vehicle-grade solid-state batteries have more than 1,000 patents, ranking among the top in the world, and most of them are innovative patents with high commercial value. At CES 2022, Gill Pratt, Toyota’s chief scientist and director of the Toyota Research Institute, reiterated that the first Toyota vehicles with solid-state battery technology will arrive around 2025.

Thomas Schmall, chief technology officer of Volkswagen Group Components, said in an interview last year that Volkswagen has high hopes for the development of a new generation of solid-state batteries. The company hopes to form a complete solid-state battery sales model in 2025 to supply solid-state batteries to the market, and plans to Build 6 large battery factories in Europe by 2030, with a total annual production capacity of 240GWh.

BMW Group released a plan, saying that it plans to achieve mass production by 2030; LG Energy is also developing all-solid-state batteries, which are expected to be mass-produced in 2026.

The development of domestic solid-state batteries is also in full swing, and the technical route is mixed between all-solid and semi-solid. The battery industry leader CATL has previously disclosed two patents related to solid-state batteries and announced in May last year that samples of solid-state batteries can already be made, but there is still a long way to go before commercialization. It will not be launched to the market until 2030. SAIC announced in June last year that it will launch solid-state lithium batteries with high safety, high energy density, and commercial applications in 2025.

Players who choose to target semi-solid R&D as a compromise include Weilan New Energy, Qingdao Development, Guoxuan Hi-Tech, Ganfeng Lithium Battery, etc. Although they also have all-solid-state battery production lines, the mass-produced all-solid-state batteries are mainly used in consumer Electronics, special power supply, and other fields. The off-line semi-solid batteries used in new energy vehicles are currently in the verification test stage.

NIO has previously advertised that it is equipped with solid-state batteries, which has made the industry interested. After the listing, this so-called solid-state battery also showed its final appearance. It is not an all-solid-state battery that the industry has been waiting for. Li Bin of NIO mainly pulled off a marketing gimmick. The battery pack equipped with the ET7 car is actually a half solid-state battery. However, the attention and discussion caused by the gimmick also made NIO’s new car stand out. The battery with a battery life of more than 1000km has made people see the potential of solid-state batteries.

Whether it is the timetable set by car companies or the mass production time given by industry researchers and experts, they all point to 2025 and 2030, but at present, there is no sign of advance. There is a tendency to continue to delay towards 2030. We see that it will take a period of dormant development from going out of the laboratory to the large-scale implementation, and the actual implementation of large-scale mass production is hindered and long.

The long road to mass-production

Compared with other lithium-ion power batteries, the technical indicators of solid-state batteries are superior, but these data are also inhouse indicators in the laboratory. In the process of actual mass production, there are still many bottlenecks that have not yet been overcome.

1. The technical indicators of solid-state batteries still need to be improved. Solid electrolytes have low ionic conductivity, slow charging, poor solid/solid interface contact and stability, and electrolytes are sensitive to air.

2. The manufacturing process is complex and the production process is immature. For example, the oxide and sulfide electrolytes used in the manufacture of solid-state batteries are porous ceramic materials, which are characterized by brittleness.

3. The manufacturing cost is high. The preparation process of all-solid-state batteries is complicated, and the solid electrolyte is relatively expensive. At this stage, the cost of all-solid-state electrolyte lithium power batteries is relatively high.

4. The industrial chain is not yet complete, making it difficult to mass-produce. At this stage, solid-state batteries are mostly experimental products in the laboratory. There are only a handful of batteries that have actually been tested. With the existing technical level and equipment capabilities, the yield of finished products cannot be guaranteed, let alone large-scale mass production. listed.

The solution to these real-world bottlenecks is not so easy. Fisker, which has been developing solid-state batteries for several years, said at the beginning of last year that it would abandon the development of all-solid-state batteries. This decision also means that years of research on solid-state batteries have been in vain. The lithium battery unicorn company Massachusetts Solid Energy (SES) also gave up the research and development of all-solid-state battery technology and chose the solid-liquid mixed semi-solid battery route. In the final tackling stage, the old players in these solid-state batteries chose to give up, which to a certain extent shows that the final R&D sprint stage of solid-state batteries is more difficult and dangerous than the 90% of the mileage that has been completed.

In short, for solid-state batteries, whether it is the energy density, cycle life, safety, cost and other elements of the technical indicators, whichever is missing is a stumbling block on the road to large-scale commercialization.

Whether the company still adheres to the all-solid-state battery route or chooses the semi-solid-state route as a compromise, there are uncertainties in the technical route of solid-state batteries. The mainstream view in the industry is that semi-solid-state batteries may be able to achieve mass production around 2025, but it will take at least 10 years for all-solid-state batteries to be fully commercialized. With the development of the ten-year timeline, no one can be 100% sure whether solid-state batteries are the ultimate route for power batteries.

From research and development to verification and implementation of industrial products, it is impossible to get out without a decade. Solid-state batteries are still in the process of exploration from materials to structures to manufacturing techniques. As an emerging power battery option, it also takes time to settle and brew. Only in this way can the mileage of new energy vehicles be extended for a long time, subvert the century-old industry of innovative automobiles, and also contribute to the ecological construction of green travel.