Smooth surfaces to improve rechargeable batteries

1 min read

Smooth surfaces on solid electrolytes could improve rechargeable lithium batteries, found MIT researchers.

According to the team, the problem is that researchers have been focusing on the wrong properties in their search for a solid electrolyte material. The prevailing idea was that the material's firmness or ‘squishiness’ – a property called shear modulus – determined whether dendrites could penetrate into the electrolyte.

The new study however is said to show that it's the smoothness of the surface that matters most. Microscopic nicks and scratches on the electrolyte's surface could provide a toehold for the metallic deposits, which then form dendrites.

"The formation of dendrites, leading to eventual short-circuit failures, has been the main reason that lithium-metal rechargeable batteries have not been possible," Professor Yet-Ming Chiang explained.

The study showed that the way dendrites form in stiff solid materials follows a completely different process than those that form in liquid electrolytes.

The researchers therefore believe that focusing on achieving smoother surfaces could eliminate or greatly reduce the problem of dendrite formation in batteries with a solid electrolyte.

In addition to avoiding the flammability problem associated with liquid electrolytes, this approach could make it possible to use a solid lithium metal electrode as well. According to the group, doing so could potentially double a lithium-ion battery's energy capacity, which is crucial for both vehicles and portable devices.