Rock turned into battery, new electrolyte can transform EV industry

Researchers have explored a new material based on rock silicates, which can replace lithium in electric car batteries in the future. The material can help develop new kinds of energy storage devices, which could be more affordable and non-sensitive to moisture.

Mohamad Khoshkalam, a researcher from the Technical University of Denmark, found that material based on rock silicates can be a good fit for a solid-state electrolyte.

Potassium and sodium silicates, components of rock silicates, are among the most abundant minerals on Earth. According to the researcher, this material can conduct ions at hot temperatures and is non-sensitive to moisture.

Potential of potassium silicate as a solid-state electrolyte

“The potential of potassium silicate as a solid-state electrolyte has been known for a long time, but in my opinion has been ignored due to challenges with the weight and size of the potassium ions,” said Mohamad Khoshkalam. “The ions are large and, therefore move slower.”

According to researchers, these rock silicates can be found in ordinary stones you pick up on the beach or in your garden. A significant advantage of this new material is its insensitivity to air and humidity. This allows it to be molded into a paper-thin layer within a battery.

Extractable from silicates, this inexpensive, eco-friendly material has the potential to be utilized in a wide array of applications.

But ions in lithium-based liquid electrolytes or solid-state electrolytes move faster when compared to ions in rock silicates. This is because rock silicates are larger and heavier.

A new way to move ions move faster in rock silicates

However, Khoshkalam figured out a way to enable ions to move faster in rock silicates than in lithium-based electrolytes.

“The first measurement with a battery component revealed that the material has a very good conductivity as a solid-state electrolyte. I cannot reveal how I developed the material, as the recipe and the method are now patented,” said Khoshkalam.

Solid-state electrolyte developed using potassium silicate

The researcher created a solid-state electrolyte, a paper-thin material positioned between the anode and cathode of a battery cell. This was achieved by making a powder based on potassium silicate and combining it with a binder and solvent. Subsequently, the liquid solution is poured into a roller that spreads the material into a thin layer.

The material is molded as thin white tapes and dried in a tape cluster, with the capacity to produce up to 10 meters of tape material at a time. Then, the solid state electrolyte is moved into a glove box, where it’s assembled into a solid state battery cell along with the anode and cathode.

But there is still a long way to go as solid-state batteries based on potassium and sodium silicates have a low technology readiness level. The researcher anticipates that it may take a minimum of 10 years for these batteries to be integrated into electric cars.

It’s claimed to be a high-risk technology, where the chance of commercial success is small and the technical challenges are many.

“We have shown that we can find a material for a solid-state electrolyte that is cheap, efficient, eco-friendly, and scalable—and that even performs better than solid-state lithium-based electrolytes,” said Khoshkalam.