Key Findings
The SOLiD project has achieved breakthroughs in electrode dry processing, polymer electrolyte formulation, and digital quality control to enable the industrial scaling of solid-state lithium-metal batteries (SSBs). A primary technical milestone is the development of PESDA, a polyester-based electrolyte formulation unveiled by mid-2025 that retains 95% of capacity after 120 cycles in prototype cells and exhibits tensile yields up to 250% before failure.
Technical Details
To eliminate toxic solvents and energy-intensive drying, SOLiD is implementing roll-to-roll (R2R) dry extrusion coating. This process blends active cathode material, polymer binder electrolyte, and conductive additives into uniform films. The use of ALD-protected NMC811 allows this dry extrusion to occur under ambient conditions, removing the requirement for a dry room.
On the anode side, the project has scaled pulsed laser deposition (PLD) to create a lithium layer thinner than 10 micrometres, topped with a protective lithium-alloy layer to prevent dendrite formation. For quality assurance, the project integrated smart inspection tools—including particle detection, optical monitoring, and electrochemical impedance spectroscopy—into a digital twin. This AI-driven system links inspection data to process control to reduce defects and improve yields.
Background & Context
Launched in September 2022, SOLiD consists of 13 partners across eight countries. The project addresses the limitations of traditional lithium-ion batteries, such as the volatility of liquid electrolytes and the reliance on cobalt. By replacing graphite with lithium metal anodes and utilizing solid polymers, these SSBs can store up to 70% more energy in the same volume while reducing fire risks and dependence on critical raw materials.
Significance & Outlook
The transition to pilot-scale production is already underway, with validated roll-to-roll PLD-deposited lithium in coin cells and ALD-processed cathode materials at kilo scale. These advancements provide a roadmap for European battery sovereignty, offering a template for future gigafactories to produce safer, lighter, and more energy-efficient batteries for the EV market.
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