The Hidden Aspects of Batteries: Mechanisms, Strategies, Challenges and Future Directions of Gas Generation in Sodium-Ion Batteries

The accelerated evolution of portable devices, electric vehicles, and energy storage systems has introduced heightened expectations regarding the cost, charge rates, lifespan, and safety of sodium-ion batteries (SIBs). However, SIBs produce gas during the cycling and storage processes, leading to battery volume expansion, dislocation of the pole plates and diaphragm, and increased battery polarization. These factors contribute significantly to battery lifespan reduction and safety issues. Thus, gaining a thorough understanding of the gas generation mechanism in SIBs, as this will facilitate a profound comprehension of the intricate interactions between electrodes and electrolytes, and provide efficacious guidance for optimizing battery performance. This paper reviews recent advancements in the research on gas generation mechanisms in SIBs, with a particular focus on gas suppression strategies to enhance battery safety. Finally, this paper identifies current issues that remain to be addressed in the study of battery gas generation and suggests avenues for further exploration of gas generation mechanisms and the development of more effective gas suppression strategies. It is anticipated that this review will promote further advancements in the performance, gas suppression, and safety of SIBs, particularly in high-energy-density systems.