Solid-state magnesium batteries could become far more durable thanks to a new alloy design from researchers at Japan's Tohoku University. The team found a way to turn the chemical reactions that normally degrade battery performance into a mechanism that instead improves stability and ion transport, reporting their results in the journal ACS Energy Letters.
Turning a flaw into a feature
Solid-state magnesium batteries are considered a promising alternative to lithium-ion cells because of their potential safety and lower material costs. But unwanted reactions at the interface between battery components often sap performance and shorten lifespan. The Tohoku team discovered those interfacial reactions do not need to be eliminated; carefully guiding them can actually improve how magnesium ions move through the cell while keeping it stable.
"For a long time, interfacial reactions were treated as something to avoid," said Hao Li, Distinguished Professor at Tohoku University's Advanced Institute for Materials Research. "But our results show that when these reactions are carefully guided rather than suppressed, they can help solid-state magnesium batteries perform far more effectively."
The magnesium-tin recipe
To build a better anode, the researchers introduced tin into magnesium, forming a stable compound known as Mg2Sn that helps regulate the reactions inside the battery. By modifying both the surface and internal structure of the anode, they created conditions for more uniform magnesium deposition and smoother ion movement during charging and discharging.
The team tested several magnesium-based alloys with different secondary phases under real battery operating conditions, measuring ion transport, interfacial stability and cycling behavior. The optimized magnesium-tin alloy delivered the strongest overall performance, maintaining stable operation for more than 1,300 hours and showing over 400 times longer cycling life than pure magnesium.
A new design strategy
The researchers argue that future battery development should focus not only on improving ion conductivity but also on controlling the chemical reactions at solid-solid interfaces, which often create resistance and mechanical degradation. The approach may extend beyond magnesium to other next-generation chemistries where interface stability is a critical challenge.
The work adds to a busy stretch of battery and energy-storage progress, from Ganfeng's 500 Wh/kg solid-state milestone to grid-scale deployments such as Adani Green's record 3.37 GWh battery in India. As demand grows for safer, longer-lasting storage, the Tohoku findings offer a new way of thinking about how batteries are designed.
Reporting based on coverage from Interesting Engineering and ACS Energy Letters.