SOLID – Research at the heart of electromobility

Press Release /

© F. Frech, Fraunhofer ISC
The new production route – the first fully functional single cell is planned to be available within a year.

No chance without them: High-performance batteries are the key to electromobility. And the market is growing. Europe expects to see a lot more of electric vehicles by 2030. The EU commission is promoting the development of high-performance batteries accordingly. Among the researchers working to make the vision come true are those of the Fraunhofer Institute for Silicate Research ISC in Würzburg, Germany. They take part in the collaborative project SOLID that was recently launched to develop a simple low-cost method for battery mass production via the sol-gel route. The aim is to provide industry with the much needed large-scale production option for safe high-performance lithium-based solid state batteries.

The project raises new hopes to accelerate the advance of electromobility: lithium-based solid state batteries from sol-gel materials are considered a future-proof solution on the path towards safe, low-cost but high-performance batteries able to combine high charging speed with long cycle life.

Today, it is mostly conventional lithium-ion batteries that are used in electric vehicles or bicycles. This type of battery enables comparatively high energy and power densities but there is a limit to further voltage increase which puts a stop to ever rising performance levels. Also, the charging speed needs to be controlled to avoid overheating.

Solid state batteries, on the other hand, offer the clear advantage of wider voltage windows. Another benefit is their inorganic construction which means that they are not flammable.

The SOLID consortium now set out to make battery cells from sol-gel layers and so develop new low-cost concepts for lithium-based solid state batteries that offer both higher power density and higher voltage. A battery of the same weight and volume as a conventional one could store significantly more energy this way. Currently available lithium-based solid state batteries are costly and not suitable for mass production or they fail to be stable enough for high power densities. The SOLID researchers are about to change all this.


SOLID stands for innovative solid state batteries based on sol-gel materials with lithium metal anode and implemented 3D structuring. The project is funded by the Federal Ministry for Education and Research BMBF. Funding was granted for three years up to September 2020 and totals 3.2 million euros. Visionary input comes from the Fraunhofer R&D Center for Electromobility Bavaria located at the Fraunhofer ISC in Würzburg. The Center is also acting as co-cordinator.

The SOLID team has ambitious aims: in just a year from project launch they want to present the first fully functional single cell based on the new solid state battery concept. The most challenging part will be to realize the required layer thicknesses via the sol-gel route. Layers of the required thicknesses are complex to synthesize, produce and cure and the idea seems to clash with good ion conductivity. But the plan is to employ smart coating method that will not only allow for the desired layer thicknesses but also yield high performance.

The task assigned to the Fraunhofer R&D Center Electromobility Bavaria is to produce the current collector layer, the electrolyte layer and the cathode layer via the sol-gel route. Andreas Wolf, project leader at the Fraunhofer ISC in Würzburg, is very confident: “Our research will considerably advance the use of solid state batteries by enabling their low-cost, industry-scale production. It will lead to a new robust battery with high power density and turn out to be a milestone in electromobility.

Project details
SOLID – Innovative Festkörperbatterien auf Basis von Sol-Gel-Matierialien mit Li-Metallanode und implementierter 3D-Strukturierung
Coordinator: VARTA Microbattery GmbH
Co-coordinator: Fraunhofer ISC, Fraunhofer FuE-Zentrum Elektromobilität Bayern
Project term: 1 October 2017 to 30 September 2020
Funded by the Federal Ministry for Education and  Research BMBF - grant agreement 03XP0129E


VARTA Microbattery GmbH, Ellwangen
Applied Materials WEB Coating GmbH, Alzenau
COATEMA Coating Machinery GmbH, Dormagen
LUNOVU GmbH, Herzogenrath
Fraunhofer ISC, Würzburg
Fraunhofer ISE, Freiburg

Read more about Battery Materials and Batteries on the website of Fraunhofer ISC.