Functional Electrolyte Additives for Sodium‐Ion and Sodium‐Metal Batteries: Progress and Perspectives

Abstract Sodium‐based rechargeable batteries are considered one of the strongest contenders for the next generation of power storage devices. Functional electrolytes with additives play a crucial role in influencing the electrochemical performance of sodium‐based batteries. The addition of small doses of additives can greatly enhance the electrolyte, improving energy density, cycling performance, and safety. This paper presents an overview of recent research focused on novel additives for sodium‐ion batteries (SIBs) and sodium‐metal batteries (SMBs). The additives are categorized based on their specific functions, including film‐forming, flame retardant, overcharge protection, high‐voltage, acid and water removal, inhibition of gas production, high and low temperature and protection of sodium metal anode. The working mechanisms for these additives are thoroughly explained. Finally, potential future research directions are proposed.