A battery layer reduces pressure in solid-state batteries, improves ion flow, increases energy density, and supports battery life.
Researchers at the Korea Electrotechnology Research Institute have developed a nano-tin interlayer that allows all-solid-state batteries to operate at 2 MPa of pressure, a reduction from the pressures required in experimental systems. The advance could remove an engineering barrier to commercializing solid-state batteries by eliminating the need for pressurization hardware.
In tests, battery cells using the nano-tin interlayer achieved energy densities exceeding 350 Wh/kg, above the 150–250 Wh/kg range in lithium-ion batteries used in consumer electronics and electric vehicles. Pouch cells also retained more than 81 percent of their capacity after 500 charge-discharge cycles, indicating stability.
The challenge in all-solid-state batteries has been maintaining ion movement across solid interfaces. Unlike lithium-ion batteries, which use liquid electrolytes to maintain contact between components, solid-state designs rely on physical contact between electrolytes and electrodes. When that contact weakens, interfacial resistance rises, slowing ion transport and reducing performance.
To compensate, most approaches depend on applying external pressure—often tens of megapascals—or adding interface coatings. Both strategies add manufacturing steps, increase cost, and reduce packaging efficiency, particularly in electric vehicle battery systems where weight and volume matter.
The nano-tin interlayer is designed to address those limits. Applied as a coating of tin powder through transfer printing, the material creates a pathway for lithium-ion transport while protecting the lithium metal anode from degradation during charging. Researchers found that the layer lowers interfacial resistance and suppresses the formation of lithium dendrites—deposits that can damage cells and create safety risks.
That combination is important for lithium metal anodes, which are considered necessary for achieving energy densities but have remained difficult to stabilize in solid-state systems. By reducing stress and limiting resistance, the tin interlayer improves performance and durability without support systems.
The team also used simulations to examine how tin-based alloys regulate lithium transport at the atomic and electronic scale. The modeling helped explain how the interlayer stabilizes the battery interface and could provide a framework for designing interlayer materials.
The study also showed that the approach can scale to pouch cells, a requirement for battery manufacturing. Potential applications include electric vehicles, humanoid robots, and grid-scale energy storage, where energy density and safety are important.
