Solid-state magnesium batteries could become significantly more durable thanks to a new alloy design developed by researchers at Tohoku University. The team found a way to turn chemical reactions that normally degrade battery performance into a mechanism that improves stability and ion transport.

The advance addresses one of the biggest challenges facing solid-state magnesium batteries. While these batteries are considered a promising alternative to lithium-ion technology because of their potential safety and lower material costs, unwanted reactions at the interface between battery components often reduce performance and shorten battery life.

Researchers discovered that these interfacial reactions do not necessarily need to be eliminated. Instead, carefully controlling them can improve how magnesium ions move through the battery while maintaining long-term stability.

The team developed a magnesium-tin (Mg-Sn) alloy anode designed to balance chemical reactivity and ion transport. By modifying both the surface and internal structure of the anode, the researchers created conditions that support more uniform magnesium deposition and smoother ion movement during charging and discharging.

Turning flaws useful

“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 (WPI-AIMR).

“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.”

To build the improved anode, the researchers introduced tin into magnesium. The combination forms a stable compound known as Mg2Sn, which helps regulate reactions occurring inside the battery.

The team tested several magnesium-based alloys containing different secondary phases to determine which composition offered the best electrochemical performance. They evaluated the materials under battery operating conditions, measuring factors such as ion transport, interfacial stability, and cycling behavior.

Among all the tested materials, the optimized Mg-Sn alloy delivered the strongest overall performance. According to the researchers, the alloy maintained stable operation for more than 1,300 hours during solid-state battery testing.

The material also demonstrated more than 400 times longer cycling performance compared with pure magnesium, a result that suggests substantial gains in battery longevity.

Stable cycling breakthrough

Solid-state batteries replace flammable liquid electrolytes with solid materials, reducing fire risks and potentially increasing energy density. However, the solid-solid interfaces inside these batteries often create resistance, instability, and mechanical degradation that limit performance.

The researchers argue that future battery development should focus not only on improving ion conductivity but also on controlling the chemical reactions occurring at these interfaces.

Their findings suggest that balancing reactivity and ion transport simultaneously could provide a new design strategy for solid-state battery systems.

The approach may have implications beyond magnesium batteries. Similar engineering methods could potentially be applied to other next-generation battery chemistries where interface stability remains a critical challenge.

As demand grows for safer and longer-lasting energy storage systems, the work offers a new way of thinking about battery design. Rather than treating interfacial reactions solely as a problem, researchers may be able to harness them to improve performance and extend battery life.

The study was published in ACS Energy Letters.