Lithium-air batteries are poised to become the next replacement for currently used lithium-ion batteries that power electric vehicles, cell-phones, and computers. Lithium-air batteries can store ten times more energy than lithium-ion batteries, and they are much lighter. But lithium-air batteries could be even more efficient and provide more charge with the incorporation of advanced catalysts made from two-dimensional materials. Catalysts help increase the rate of chemical reactions inside batteries and depending on the type of material from which the catalyst is made, can help significantly boost the ability of the battery to hold and provide energy.
Researchers synthesized several 2D materials that can serve as catalysts. A number of the 2D materials, when incorporated into experimental lithium-air batteries as the catalyst, enabled the battery to hold up to ten 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, that number could be 400 to 500 miles per charge.
Fifteen different types of 2D transition metal dichalcogenides (TMDCs) were synthesized. 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 performance of 15 TMDCs as catalysts were studied in an electrochemical system mimicking a lithium-air battery. The 2D TMDCs helped speed both charging and discharging reactions occurring in lithium-air batteries. The 2D materials also synergize with the electrolyte — the material through which ions move during charge and discharge. The 2D TMDCs and the ionic liquid electrolyte used act as a co-catalyst system that helps the electrons transfer faster, leading to faster charges and more efficient storage and discharge of energy.