Solid State Sodium Air Batteries Seen as Promising Green Energy Source

A research team led by Professor Byoungwoo Kang and Dr. Heetaek Park from the Department of Materials Science and Engineering at Pohang University of Science and Technology (POSTECH) has successfully developed a high-energy, high-efficiency all-solid-state sodium-air battery. This innovative battery can reversibly utilize sodium (Na) and air without requiring any special equipment, marking a significant advancement in the field of next-generation high-capacity secondary batteries.

Key Features and Benefits:

Metal-Air Battery Technology: Metal-air batteries, which use abundant resources such as oxygen and metals like sodium, are considered promising for green technologies such as electric vehicles and energy storage systems. These batteries draw power from the reaction of metals with oxygen.

Challenge of Carbonate Formation: A common issue with metal-air batteries is the formation of carbonate byproducts when the metal reacts with atmospheric carbon dioxide (CO2) and water vapor (H2O). This carbonate formation reduces the battery's efficiency. Traditionally, metal-air batteries require additional equipment, like an oxygen permeation membrane, to purify or selectively use atmospheric oxygen, which complicates the system.

Use of Nasicon Solid Electrolyte: The research team addressed the carbonate issue by using Nasicon, a Na superionic conductor and solid electrolyte composed of elements such as Na, silicon (Si), and zirconium (Zr). Nasicon is capable of ion movement in the solid state and demonstrates high electrochemical and chemical stability. This solid electrolyte effectively protects the sodium metal electrodes from the air and facilitates the breakdown of the carbonate formed during the electrochemical cell operation.

Enhanced Energy Efficiency: By leveraging Nasicon, the team achieved a reversible electrochemical reaction involving carbonate, which increased the energy density of the cell. This increase was accomplished by raising the working voltage and significantly reducing the voltage gap during charging and discharging, thereby enhancing the overall energy efficiency of the battery.

Impact and Applications:

This development has substantial implications for green technologies, particularly in improving the efficiency and performance of batteries used in electric vehicles and energy storage systems. The ability to create a high-energy, high-efficiency battery without the need for complex additional equipment simplifies the manufacturing process and reduces costs. The research underscores the potential of all-solid-state sodium-air batteries to become a viable and efficient alternative to current battery technologies, contributing to the advancement of sustainable energy solutions.