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Researchers in South Korea have successfully demonstrated the use of free ambient air as fuel by harnessing a sodium-based solid electrolyte to solve the carbonate problem that has slowed the development of metal-air batteries. Its sodium-air cell has demonstrated high efficiency, higher energy density and a wide voltage range.
Metal-air batteries, which use lithium or sodium, have attracted great interest due to their exceptionally high theoretical gravimetric energy densities. These batteries rely primarily on the use of pure oxygen for the formation and decomposition of metal oxides, rather than ambient air.
Although ambient air is a more practical option, the CO2 and H2O present in the air cause serious irreversible reactions, such as the formation of carbonates and hydroxides, which often degrade a battery. To solve this problem, metal-air stacks often require additional equipment, such as an oxygen permeation membrane to purify it or selectively use atmospheric oxygen.
Now, researchers at Pohang University of Science and Technology (POSTECH) in South Korea have developed a high-energy, high-efficiency solid-state sodium-air battery that can use sodium and air reversibly without the need for equipment. specials.
The team used Nasicon, a sodium superionic conductor and solid electrolyte, to address the carbonate problem. Nasicon, composed of elements such as sodium, silicon and zirconium, allows the movement of ions in the solid state while demonstrating great electrochemical and chemical stability.
Taking advantage of this solid electrolyte, the team protected the sodium metal electrodes from the air and facilitated the decomposition of the carbonate formed during the operation of the electrochemical cell. |
