Breakthrough: All-Solid-State Sodium-Air Battery Developed by Researchers

Secondary batteries play a crucial role in advancing green technologies, particularly in applications such as electric vehicles and energy storage systems. The emergence of next-generation high-capacity secondary batteries, known as "metal-air batteries," has sparked significant interest due to their ability to harness power from abundant resources like oxygen and metals readily available on Earth. However, a key challenge faced by these batteries is the formation of carbonate—a byproduct of the reaction between metal and oxygen, involving atmospheric carbon dioxide (CO2) and water vapor (H2O)—which can compromise battery efficiency.

To overcome this challenge, researchers have been exploring innovative solutions. Despite their name, metal-air batteries often require additional components such as an oxygen permeation membrane to purify oxygen or selectively utilize atmospheric oxygen. In a recent study, a team of scientists turned to Nasicon, a Na superionic conductor and solid electrolyte, to address the carbonate issue effectively. Comprising elements like sodium, silicon, and zirconium, Nasicon demonstrates high electrochemical and chemical stability, making it an ideal candidate for enhancing battery performance.

By leveraging Nasicon as a solid electrolyte, the research team successfully protected sodium metal electrodes from exposure to air and facilitated the breakdown of carbonate formed during the operation of the electrochemical cell. This breakthrough led to a reversible electrochemical reaction involving carbonate, resulting in a notable increase in the cell's energy density by raising the working voltage and reducing the voltage gap during charging and discharging processes. As a result, the energy efficiency of the battery was significantly enhanced, marking a significant advancement in the field of energy storage technology.

One of the key highlights of the study was the development of an all-solid-state sodium-air battery cell that exhibited superior kinetic capability through the in-situ formation of catholyte. This catholyte enabled fast sodium ion conduction within the electrode, enhancing the overall performance of the battery. Notably, the cell operated solely on metal and air without the need for additional specialized equipment, such as an oxygen filtration device, showcasing its simplicity and efficiency.

Professor Byoungwoo Kang, who spearheaded the research, expressed his optimism about the findings, stating, "We have devised a method to address the longstanding challenge of carbonate formation in high-energy metal-air batteries. Our goal is to lead the next generation of all-solid-state metal-air batteries by leveraging a solid electrolyte-based cell platform that offers stability in ambient conditions and a wide voltage range." The research was supported by the Mid-Career Researcher Program of the National Research Foundation of Korea and BK21(+), underscoring the collaborative efforts that drove this groundbreaking innovation.