Fraunhofer ISI has developed a roadmap for solid state batteries that takes into account a wide range of materials, components, and the cell level to the application level. In it, current and latest research findings are critically evaluated and the development potential of solid-state batteries is compared with those of proven lithium-ion batteries over the next ten years. The roadmap shows: Solid state batteries have a lot of potential, but they have to prove their commercial viability in the next five years.
Existing lithium-ion batteries (LIB) are based on liquid electrolytes and are currently used in many mobile and stationary applications. However, the potential for improvement decreases as technology advances – this technology is expected to slowly reach its limits in the next decade. Solid-state batteries (SSB) containing solid electrolytes, which are currently in development and could be brought to market in the coming years, promise improvements in several important performance parameters. The entire battery sector could benefit from this and from the further parallel development of LIB technology, which will remain dominant over the next few years.
Based on a comprehensive literature search, expert surveys, and expert workshop, the battery experts at Fraunhofer ISI have developed a roadmap in which the three most promising solid electrolytes currently – oxide electrolytes, sulfide electrolytes and polymer electrolytes – have been closely examined and compared with expected developments in Lithium ion batteries.
Solid state batteries have great potential
The results show that solid-state batteries (SSB) need to make significant improvements in performance compared to the latest liquid electrolyte LIBs in order to achieve relevant market shares. Important performance parameters are energy density, safety, service life, costs and the ability to fast charge. Solid state batteries have the potential to surpass classic LIBs in terms of energy density, especially because they allow the use of Li-metal anodes. In addition, its safety is considered high, even at the cellular level, because it does not contain any flammable liquids. Their service life can exceed that of liquid electrolyte LIBs, but technical challenges such as volume changes during charging or discharging remain to be overcome. At the start of their market launch, the costs of solid-state batteries are likely to be significantly higher than those of existing LIBs, in part due to lower production volumes. The rapid charging capacity of solid-state batteries is currently limited by the typically low ionic conductivity of solid electrolytes, but their design can be adapted specifically for this purpose. In general, it should be noted that improving one performance parameter often comes at the expense of another and batteries can be tailored to specific needs and applications.
The automotive market has the greatest overall potential for solid-state batteries and is likely to become their main field of application in the medium to long term. Solid-state batteries based on sulfide electrolytes can initially be used in the consumer sector, such as laptops, smartphones or power tools, since the requirements and test methods are less stringent here. The automotive market is likely to be the first application area of solid-state oxide batteries – from around 2028. Due to the high initial costs, it is envisaged that solid state batteries will initially be used in the upper market segments. Cost reductions through long-term expansion effects could help the technology open up more areas of application, such as trucks, fixed storage or, after 2035, in passenger aviation.
Future market shares will remain manageable in principle
With regard to future market developments, solid state battery production, which is currently still less than 2 GWh globally and based on SSB polymer, is expected to increase sharply between 2025 and 2030 – when solid state batteries based on oxide electrolytes are introduced. and sulfides in the market. Production capacity is estimated at 15 to 55 GWh in 2030 and 40 to 120 GWh in 2035, which is about one to two percent of the then emerging LIB market. Thus, liquid electrolyte LIBs will dominate the market for the foreseeable future.
In addition to assessments of application areas and market developments, the roadmap also provides data on the obstacles that solid state batteries will have to overcome in order to penetrate the market in the future. Dr. Thomas Schmaltz, who coordinated the research work on the roadmap at Fraunhofer ISI, identifies three main challenges:
“First of all, it is not yet expected which solid-state battery concept will ultimately have the best performance, which would require parallel development of different approaches and therefore higher investments. Second, solid-state batteries will be in constant competition with liquid electrolyte lithium-ion batteries, Because of their initially high costs, they will have to generate significant performance improvements, indicating that the initial applications will tend to be in the premium sector.Third, strong private and public funding beyond research funding is essential in order to catch up with European players compared to Asian and American players. In patenting, product development, production technologies, pilot production, emerging and industrial activities – if this is successful, Europe can in the future play a leading role in the development of solid-state battery technologies.”