The Potential of Na–Air Batteries

Abstract

AbstractSodium–air batteries (SABs) have attracted wide attention in the chemistry society owing to their high energy density, abundant precursor sources, inexpensive materials and reduced manufacture costs, and environmental benignity. This review summarizes the research and progress of the rechargeable SABs based on nonaqueous and aqueous electrolytes. The effects of gas atmosphere, environmental pressure, catalysts, and architectures of the electrodes on the distribution and morphology of discharge products in SABs are also included. The complex and rich sodium electrochemistry of air electrodes is presented, and many electrochemical reaction mechanisms based on the structure design of air electrodes with various catalysts and electrolytes are also summarized. They involve the reversible formation/decomposition reactions of NaO2, Na2O2, Na2CO3, NaHCO3, Na2C2O4, and NaOH. It is a great challenge to seek for highly efficient electrocatalysts, and more stable and less volatile electrolytes to improve the cyclability of nonaqueous SABs. Internal resistance of the cell could be efficiently improved by developing solid electrolytes with high ion conductivity and optimizing the structures of the cells for the high power density of aqueous SABs. How to effectively control the growth and decomposition of discharged products at three‐phase boundary reaction zones by the integration of highly stable electrolytes and optimization of air electrodes is the next challenge urgently needing to be addressed; only then can we realize practical high performance nonaqueous SABs for daily use.