The lithium-ion battery is a cornerstone of our electric age — powering everything from e-bikes to grid-scale storage. As demand grows for higher energy density and safer storage, scientists are hitting a stubborn obstacle: the unruly behaviour of lithium metal inside solid-state batteries.
These batteries, often touted as the next great leap in energy storage, replace flammable liquid electrolytes with safer, solid materials. Yet even these solid electrolytes aren’t immune to a dangerous phenomenon: the growth of lithium dendrites — branch-like structures that can pierce the battery from within.
Researchers at Xiamen University, China [24.5°N, 118.1°E] have now proposed a novel solution: reshape the internal structure of the battery’s electrolyte itself, making it less welcoming to dendrites. Their approach involves amorphising the grain boundaries — or in simpler terms, intentionally “melting and freezing” tiny fault lines in the solid material to make them less hospitable to these growing lithium structures.
It’s a quiet revolution in materials science, and one that could extend the lifespan, safety, and performance of next-generation batteries for everything from electric vehicles to renewable energy storage.
Why Are Dendrites Dangerous?
Inside a battery, lithium ions move back and forth between electrodes during charging and discharging. In ideal conditions, they settle smoothly into their destination. But in solid-state batteries, the path isn’t always smooth. Crystalline materials — like the garnet-type Li₇La₃Zr₂O₁₂ (LLZO) used in many experimental solid electrolytes — contain grain boundaries — the internal “seams” where crystalline regions meet. These spots are weak points where lithium can clump and form jagged branches.
These boundaries, the research shows, can act like fault lines in a city: places where stress builds, ions collect unevenly, and cracks can begin. Over time, lithium can cluster here, form metallic protrusions, and grow into sharp, tree-like dendrites that eventually pierce the battery and cause short circuits or fires.
What the Researchers Did Differently
The team at Xiamen University approached this problem not with new materials, but with a new way of modifying existing ones. Using molecular dynamics simulations and machine learning, they studied exactly how lithium behaves at grain boundaries.
They found that lithium ions are drawn to grain boundaries where the structure is looser or more porous. Once they cluster there, they’re more likely to form dendritic “roots” — from which protrusions can grow.
To stop this, they tried something counterintuitive: they melted the grain boundary slightly, turning it from a perfect crystal into an amorphous zone — essentially a small region where atoms are arranged more randomly. The bulk of the material remained crystalline and conductive, but the grain boundaries became less accommodating to lithium buildup.
Positive Outcomes
Their simulations showed that these amorphous grain boundaries:
- Reduced lithium clumping
- Smoothed out charge distribution
- Improved mechanical flexibility, so the battery could better tolerate stress
- Eliminated sharp lithium protrusions that usually signal the start of dendrite growth
While this local amorphisation does slightly reduce overall ion conductivity (because disordered regions are less conductive than crystals), the gain in uniformity and safety appears to more than offset the loss.
What This Means in Practice
For battery manufacturers and researchers across Northern Europe and Canada, where both EV uptake and battery research are growing fast, this work offers a powerful design insight: it’s not just about materials, but about their internal architecture.
In particular:
- Solid-state EV batteries — still in early development — need to overcome safety concerns to scale. This research directly targets that challenge.
- Grid-scale batteries, which may use solid electrolytes for durability, benefit from longer life and lower fire risk.
- Battery recycling and reuse could become more viable if dendrite-related failure modes are reduced.
It also suggests a path forward using existing materials, rather than waiting for entirely new chemistries. LLZO is already a widely studied solid electrolyte; this study shows how to make it behave better — not by replacing it, but by redesigning its weak spots.
The Road Ahead
This isn’t a commercial breakthrough — not yet. But it’s a major step toward engineering batteries from the inside out, with deliberate control over not just chemistry but microstructure. As solid-state batteries move from labs to cars and homes, this level of detail will become essential.
In a world that demands cleaner transport, resilient grids, and longer-lived electronics, it’s the quiet, crystalline revolutions like this one that help turn ambition into reality.
Source
Grain boundary amorphization as a strategy to mitigate lithium dendrite growth in solid-state batteries, Nature Communications, 2025-05-19
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