New 2D materials may enable electric vehicles to get 800km on single charge

Washington: Scientists say they have developed several two-dimensional (2D) materials which may enable electric vehicles to clock up to 800 kilometres on a single charge.

Lithium-air batteries, which are still in the experimental stages of development, can store 10 times more energy than currently used lithium-ion batteries, and they are much lighter, said researchers from the University of Illinois at Chicago (UIC) in the US. Lithium-air batteries could be even more efficient and provide more charge with the incorporation of advanced catalysts made from two-dimensional materials, they said. Catalysts help increase the rate of chemical reactions inside batteries, and depending on the type of material from which the catalyst is made, they can help significantly boost the ability of the battery to hold and provide energy. "We are going to need very high-energy density batteries to power new advanced technologies that are incorporated into phones, laptops and especially electric vehicles," said Amin Salehi-Khojin, an associate professor at UIC.

In the research published in the journal Advanced Materials, Salehi-Khojin and his colleagues synthesised several 2D materials that can serve as catalysts. A number of their 2D materials, when incorporated into experimental lithium-air batteries as the catalyst, enabled the battery to hold up to 10 times more energy than lithium-air batteries containing traditional catalysts. "Currently, electric vehicles average about 100 miles per charge, but with the incorporation of 2D catalysts into lithium-air batteries, we could provide closer to 400 to 500 miles (804 km) per charge, which would be a real game-changer," said Salehi-Khojin.

"This would be a huge breakthrough in energy storage," he said. The researchers synthesised 15 different types of 2D transition metal dichalcogenides or TMDCs. TMDCs are unique compounds because they have high electronic conductivity and fast electron transfer that can be used to participate in reactions with other materials, such as the reactions that take place inside batteries during charging and discharging. The researchers experimentally studied the performance of 15 TMDCs as catalysts in an electrochemical system mimicking a lithium-air battery.

"In their 2D form, these TMDCs have much better electronic properties and greater reactive surface area to participate in electrochemical reactions within a battery while their structure remains stable," said Leily Majidi, a graduate student at UIC. "Reaction rates are much higher with these materials compared to conventional catalysts used such as gold or platinum," Majidi said.

One of the reasons the 2D TDMCs performed so well is because they help speed both charging and discharging reactions occurring in lithium-air batteries. The 2D materials also synergise with the electrolyte -- the material through which ions move during charge and discharge. "The 2D TDMCs and the ionic liquid electrolyte that we used acts as a co-catalyst system that helps the electrons transfer faster, leading to faster charges and more efficient storage and discharge of energy," he said.