Advances in sodium-ion batteries at low-temperature: Challenges and strategies

With the continuing boost in the demand for energy storage, there is an increasing requirement for batteries to be capable of operation in extreme environmental conditions. Sodium-ion batteries (SIBs) have emerged as a highly promising energy storage solution due to their promising performance over a wide range of temperatures and the abundance of sodium resources in the earth's crust. Compared to lithium-ion batteries (LIBs), although sodium ions possess a larger ionic radius, they are more easily desolvated than lithium ions. Furthermore, SIBs have a smaller Stokes radius than lithium ions, resulting in improved sodium-ion mobility in the electrolyte. Nevertheless, SIBs demonstrate a significant decrease in performance at low temperatures (LT), which constrains their operation in harsh weather conditions. Despite the increasing interest in SIBs, there is a notable scarcity of research focusing specifically on their mechanism under LT conditions. This review explores recent research that considers the thermal tolerance of SIBs from an inner chemistry process perspective, spanning a wide temperature spectrum (−70 to 100 °C), particularly at LT conditions. In addition, the enhancement of electrochemical performance in LT SIBs is based on improvements in reaction kinetics and cycling stability achieved through the utilization of effective electrode materials and electrolyte components. Furthermore, the safety concerns associated with SIBs are addressed and effective strategies are proposed for mitigating these issues. Finally, prospects conducted to extend the environmental frontiers of commercial SIBs are discussed mainly from three viewpoints including innovations in materials, development and research of relevant theoretical mechanisms, and intelligent safety management system establishment for larger-scale energy storage SIBs.