Solid-state batteries are often seen as one of the most promising technologies for the future of electric vehicles and clean energy.
They could offer safer batteries with higher performance than the lithium-ion batteries used today.
But despite years of research, scientists still face major technical challenges before these batteries can become widely available.
Now, researchers from Osaka Metropolitan University have discovered a surprisingly simple way to improve the performance of all-solid-state batteries without needing expensive new materials.
Their study, published in the Journal of Energy Storage, shows that changing the size mix of tiny particles inside the battery can significantly improve the movement of lithium ions, which is one of the key factors controlling battery performance.
Unlike conventional lithium-ion batteries, which use flammable liquid electrolytes, all-solid-state batteries use solid materials to move ions between electrodes.
This design could make batteries safer and more stable, reducing the risk of overheating or fires. Many experts believe solid-state batteries could eventually allow electric vehicles to charge faster and travel farther.
However, moving lithium ions through solid materials is much more difficult than through liquids.
Inside the battery, tiny particles called solid electrolytes are packed closely together. Lithium ions must travel through narrow, twisting pathways between these particles. Scientists call this complicated route “tortuosity.” The more winding and crowded the pathways are, the harder it becomes for ions to move efficiently. This creates resistance and slows battery performance.
To better understand this problem, the research team led by Associate Professor Shuji Ohsaki studied a sulfide-based solid electrolyte material called lithium phosphorus sulfur chloride, or LPSCl.
The scientists carefully changed the sizes of the particles by adjusting grinding conditions during production. They then examined how different particle-size combinations affected the battery’s internal structure and conductivity.
Using advanced computer simulations and imaging techniques, the researchers were able to visualize the microscopic routes that lithium ions travel inside the battery.
They discovered that batteries performed better when the electrolyte particles came in a mix of different sizes rather than all being the same size.
Larger particles were able to cut through clusters of smaller particles, creating smoother and more direct pathways for ions to travel. In a sense, the bigger particles acted like shortcuts or bypass roads inside the battery.
Because of this improved structure, ions needed to cross fewer particle boundaries, allowing them to move more quickly and efficiently through the electrode.
The findings are important because they suggest manufacturers may be able to improve battery performance simply by optimizing how particles are mixed during production, rather than inventing entirely new battery materials.
According to the researchers, this approach could help improve the fast charging and discharging performance of future electric vehicles while also making battery manufacturing more efficient and affordable.
As industries around the world push toward cleaner energy and carbon neutrality, advances like this could help bring practical solid-state batteries closer to everyday use.
