Solid-state battery cell hits 465 Wh/kg density, targets aerospace and defense applications

European battery startup SOLiTHOR has produced its first 10 Ah demonstration cell, marking an increase in the physical scale of its solid-state lithium battery technology. The company intends for this larger format to show that its laboratory chemistry can transition into commercial production for industries requiring specialized power sources.
Alongside the production of the larger cell, the company reported stack-level energy densities of 465 Wh/kg and 1400 Wh/L within a pouch design. Engineers reached these figures by introducing a high-loading cathode with an areal capacity of 8mAh/cm2 into the company’s proprietary Solid Composite Electrolyte.
Unlike traditional lithium-ion systems or certain semi-solid designs, this chemistry uses a sol-gel process that functions without requiring any liquid electrolyte injections during assembly.
Laboratory evaluations indicate specific performance characteristics under varied operational environments. When testing multilayer pouch cells at a temperature of 25°C, the cells sustained continuous discharge rates reaching 5C without experiencing major drops in capacity.
Performance limits and safety metrics
The same units tolerated short 30-second power pulses up to 10C when held at a 50% state of charge. This specific energy discharge behavior is relevant for machinery that requires brief, intense energy outputs, such as unmanned aerial vehicles during departure and descent sequences.
“SOLiTHOR has developed a chemistry that allows the industry to rethink the manufacturing of solid-state battery cells,” said Dr. Fanny Bardé, Co-Founder and Chief Technology Officer at SOLiTHOR.
Long-term stability tests were conducted on smaller 1 Ah multilayer pouch cells. These units completed more than 500 full discharge cycles while maintaining over 80% of their original storage capacity, which provides an initial benchmark for the operational lifespan of the chemistry.
During standardized safety protocols, the fully charged multilayer cells were subjected to intentional overcharging and direct nail penetration.
Production economics and industry targets
“In safety assessments, SOLiTHOR’s technology successfully passed the overcharge and nail penetration tests on a 100% charge multilayer pouch cell with no smoke, leakage, thermal runaway, or fire,” highlighted the company in a press release.
“These technical achievements not only prove that the chemistry works, but that it delivers the combination of energy density, power performance, and cycle life required for practical applications,” added Bardé.
The manufacturing framework for the new chemistry relies on roll-to-roll processing systems already common in the battery sector. By removing the liquid filling stage entirely and accelerating the subsequent chemical formation and aging protocols, the production timeline for these steps is shortened by two-thirds.
Because these specific phases normally represent one-quarter of total cell manufacturing expenditures, their reduction alters the overall processing economics.
Facility adaptation for market deployment
“Existing Li-ion facilities can be upgraded for solid-state production with no new equipment, limited switching costs, and reduced operational costs,” noted the press release.
The company is targeting initial applications for its battery cells within the aerospace, maritime, transport, and defense sectors.
“With this major technical update, we are demonstrating that our technology can be realistically produced, satisfying the demands of high-performance and high-value applications within aerospace, dual-use, and mobility,” concluded Rodrigo P. Navarro, CEO at SOLiTHOR.