PSI All-Solid-State Lithium Metal Battery Breakthrough

PSI all-solid-state lithium metal battery achieved a major technical leap as the Paul Scherrer Institute (PSI) in Switzerland announced a breakthrough that moves next-generation batteries closer to commercial reality. These batteries promise higher energy density, faster charging, and improved safety compared with today’s lithium-ion cells used in electric vehicles, consumer electronics, and energy storage systems.
All-solid-state batteries replace flammable liquid electrolytes with solid materials, which significantly lowers the risk of fire while enabling more compact and powerful battery designs. Despite these advantages, large-scale deployment has been limited by two persistent technical barriers that directly affect performance and lifetime.
Why lithium dendrites limit PSI all-solid-state lithium metal battery performance
One of the most serious problems in the PSI all-solid-state lithium metal battery is the formation of lithium dendrites. These microscopic, needle-like structures can grow inside the cell during charging and eventually pierce the solid electrolyte, creating internal short circuits that compromise safety and durability.
Another equally critical challenge is the unstable interface between the lithium metal anode and the solid electrolyte. Poor contact at this boundary increases resistance, reduces cycle life, and makes high-speed charging unreliable, preventing solid-state batteries from meeting automotive-grade performance standards.
How PSI improved solid electrolyte stability and conductivity
To overcome these hurdles, PSI engineers developed a new manufacturing process centered on LPSCl, a sulphide-based solid electrolyte known for its exceptionally high lithium-ion conductivity. This material supports rapid ion movement, which is essential for fast-charging and high-power applications.
Instead of using aggressive heat and pressure, the PSI team adopted a gentler sintering technique that applies moderate pressure and a low temperature of around 80 degrees Celsius. This approach allowed LPSCl particles to bond into a dense and compact structure without degrading the material’s properties, improving both mechanical strength and electrochemical performance.
Key benefits of this optimized structure include:

• Higher resistance to lithium dendrite penetration

• Maintained high ionic conductivity for fast charging

• Improved mechanical stability under repeated cycling

How lithium fluoride coating enhances the PSI all-solid-state lithium metal battery
While the improved electrolyte structure delivered major gains, it was not enough to guarantee stable fast-charging. To further enhance reliability, PSI added an ultra-thin lithium fluoride coating measuring just 65 nanometres on the lithium metal surface.
This protective layer plays several important roles:

• It shields the solid electrolyte from chemical breakdown when in contact with lithium.

• It prevents the formation of inactive lithium that would otherwise reduce capacity.

• It creates a physical barrier that blocks lithium dendrites from growing through the electrolyte.

Together, the advanced sintering process and the lithium fluoride coating significantly improve safety, durability, and charging performance, positioning PSI’s technology as a strong contender for next-generation electric vehicle and energy storage applications.