Japan Researchers Reveal How Silicon Anodes Withstand Stress In solid-state batteries.

Researchers in Japan have used advanced X-ray imaging to show how silicon anodes in all-solid-state batteries keep part of their contact with the solid electrolyte even as they expand and shrink during charging. The finding could help improve the design of next-generation electric-vehicle (EV) batteries.

Silicon can hold far more lithium than the graphite used in today’s batteries, making it attractive for high-energy solid-state systems. But it also swells by more than four times during charging, often breaking contact with the solid electrolyte and reducing battery life.

Use Of Nano-Tomography

A team led by Professor Yuki Orikasa at Ritsumeikan University used operando synchrotron X-ray micro- and nano-tomography — a technique that captures 3D images while the battery is running — to watch the silicon–electrolyte interface in real time. The study was published in ACS Nano recently.

The researchers found that even when silicon particles form voids and pull away from the electrolyte, thin layers of the electrolyte stay attached. These small “bridges” preserve some ion flow and allow the battery to keep operating.

Pattern Of Silicon Detachment

High-resolution images also showed that the silicon does not detach evenly. The separation begins along the sides of the particles, where pressure is lower, while the top and bottom surfaces remain better connected. This partial contact helps keep lithium ions moving despite the structural changes.

Small fragments of the sulfide-based electrolyte were also found clinging to the silicon after cycling, providing additional anchoring points.

The team linked the battery’s initial capacity loss to the first formation of these voids. But after the void pattern stabilised, later cycles showed little further degradation.

The findings, the researchers said, could guide engineers in designing solid-state batteries that better manage mechanical stress. Improving how electrolyte materials stick to silicon and controlling pressure inside the electrode could help maintain performance.

Orikasa said the work shows that “not all interfacial separation is harmful,” as partial contact can still support stable operation. The study highlights how nanoscale mechanics strongly influence battery durability and could aid future electric-vehicle and grid-storage technologies.