Electric car batteries may soon be made of rock

In a decade, solid-state batteries made from rock silicates are expected to become an environmentally friendly, more efficient, and safer alternative to current lithium-ion batteries. 

Researchers at the Technical University of Denmark (DTU) have patented a new superionic material based on potassium silicate, a mineral that can be extracted from ordinary rocks.

New generation of lithium-free batteries 

The lithium-ion battery, commonly used in electric cars, has limitations in terms of capacity, safety, and availability. Lithium is expensive, environmentally harmful, and its scarcity can impede the green transition of car transport. 

As more people switch to electric cars, there is a pressing need for a new generation of lithium-free batteries that are efficient, eco-friendly, and cheaper to produce. This requires developing new materials for the battery’s main components (anode, cathode, and electrolyte) and creating new battery designs. 

Researchers worldwide are focusing on this field to significantly reduce carbon emissions from the transport sector.

Rock silicates for batteries 

At DTU, researcher Mohamad Khoshkalam has developed a material that has the potential to replace lithium in future batteries: solid-state batteries based on potassium and sodium silicates, which are common minerals found in the Earth’s crust. 

These rock silicates, found in ordinary stones, are not sensitive to air and humidity, allowing them to be molded into a paper-thin layer inside the battery.

Enormous potential of potassium silicate 

The potential of this milky-white, paper-thin material based on potassium silicate is enormous. It is inexpensive, eco-friendly, and can be extracted from silicates covering over 90% of the Earth’s surface. 

The material can conduct ions at around 40 degrees and is not sensitive to moisture, making future battery production easier, safer, and cheaper. This is because production can take place in an open atmosphere and at temperatures close to room temperature. 

Additionally, the material works without the addition of expensive and environmentally harmful metals like cobalt, used in lithium-ion batteries to boost capacity and service life.

“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. The ions are large and therefore move slower,” Khoshkalam said.

Superionic material of potassium silicate

The electrolyte in a battery can be a liquid or solid material, allowing ions to move between the battery’s anode and cathode, maintaining the electrical current during discharging and charging. 

The electrolyte is crucial for battery capacity, charging time, lifespan, and safety. The ions in rock silicates generally move slower than those in lithium-based liquid electrolytes or solid-state electrolytes because they are larger and heavier. 

However, Khoshkalam has developed a superionic material of potassium silicate that enables ions to move faster than in lithium-based electrolytes.

“The first measurement with a battery component revealed that the material has 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,” Khoshkalam said.

The rock batteries of the future 

Both researchers and electric car manufacturers consider solid-state batteries to be the future’s super battery. 

Recently, Toyota announced plans to launch an electric car with a lithium solid-state battery by 2027-28. However, several car manufacturers have previously announced electric cars with solid-state batteries only to retract later.

In a solid-state battery, ions travel through a solid material instead of a liquid. This allows for faster ion movement, making the battery more efficient and quicker to charge. 

A single battery cell can be made as thin as a piece of cardboard, with the anode, cathode, and solid-state electrolyte forming ultra-thin layers. This results in more powerful batteries that take up less space, potentially allowing for up to 1,000 km on a single 10-minute charge. 

Additionally, solid-state batteries are more fireproof, as they do not contain combustible liquids.

Challenges and limitations 

However, several challenges remain before solid-state batteries can be marketed. While the technology works well in laboratories, scaling up production is difficult and expensive. 

Battery research is complex and time-consuming, and new ways of producing and sealing batteries must be developed to ensure continuous contact and functionality.

Unlike lithium solid-state batteries, potassium and sodium silicate-based solid-state batteries have a low Technology Readiness Level (TRL), meaning it will take around 10 years to commercialize them. 

Despite the high risk, Khoshkalam remains optimistic. “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,” he said.

Khoshkalam has obtained a patent for the recipe and is establishing the start-up K-Ion to develop solid-state electrolyte components for battery companies. The next step is to create a demo battery to showcase the material’s effectiveness, with a prototype expected within 1-2 years.

—–

Like what you read? Subscribe to our newsletter for engaging articles, exclusive content, and the latest updates.

Check us out on EarthSnap, a free app brought to you by Eric Ralls and Earth.com.

—–