Progress is being made in the rechargeability and reaction kinetics of sodium-air batteries by researchers from the Canadian Light Source and Western University.
The understanding of sodium-air battery systems and their chemical composition and charging behaviour will play a role designing more road-worthy batteries for EVs.
The limited mileage of today’s EVs because of the low energy storage of current battery systems is a major reason why these vehicles are not more common on the road.
“Metal-air cells use different chemistry from conventional lithium-ion batteries, making them more suited to compete with gasoline,” said Dr. Xueliang Sun, of Western University. “Development of new rechargeable battery systems with higher energy density will increase the EVs mileage and make them more practical for everyday use. On the other side, higher energy density battery systems will pave the road for renewable energy sources in order to decrease emissions and climate change consequences.”
Sodium Peroxide and Sodium Superoxide
The researchers experimentally investigated different “discharge products” from the sodium-air batteries under various physicochemical conditions.
Products such as sodium peroxide and sodium superoxide are produced. Understanding of discharge products is critical to the charging cycle of the battery cell, because various oxides exhibit different charging potentials.
“We took advantage of the high brightness and high-energy resolution of the photoemission endstation, using a surface sensitive technique to identify the different states of the sodium oxides,” said CLS staff scientist Dr. Xiaoyu Cui. “We could also monitor the change in the chemical composition of the products by changing the kinetic parameters of the cell. The conclusive data from the CLS helped us confirm our hypothesis.”
Only a handful of studies have ever looked at sodium-air battery systems, according to the researchers, with limited understanding behind the chemistry of the cell.
“Although lots of research has been done to develop rechargeable, high energy metal-air battery cells during the past decade, there is still a long road ahead to achieve a practical high-energy battery system that can meet the demand for our current EVs,” said Sun. “We are working to develop novel materials for different battery systems to increase the energy density and lifecycle.
“Metal-air batteries are less expensive compared with other battery systems such as lithium-ion. Specifically, sodium-air batteries are very cost effective since the materials can easily be supplied from natural resources – sodium and oxygen being among the most abundant elements on earth.”
Source: http://www.techfragments.com/2834/sodium-air-batteries-could-replace-lithium-ion-in-electric-vehicles/
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