Research on low-temperature sodium-ion batteries: Challenges, strategies and prospect

On the strength of the low-temperature tolerance, sodium-ion batteries (SIBs) are considered a promising complementary to lithium-ion batteries for applications in high-latitude, high-cold, deep-space, and deep-earth environments. However, the low-temperature performance of SIBs remains a challenge due to the sluggish Na⁺ diffusion kinetics in electrode materials and unstable electrode-electrolyte interface reactions. Therefore, the sound strategies of electrodes and electrolytes designed to optimize the low-temperature performance of SIBs are of great significance. In this review, the research and challenges of electrolytes, anode and cathode materials for low-temperature SIBs are critical emphasized focusing on the Na⁺ storage mechanism in electrode materials and the composition of electrolytes. In addition, the related strategies to improve low-temperature performance are summarized, including the selection of sodium salt anions, the use of multi-solvent components, and the incorporation of additives in electrolytes; as well as defect, interface, and nanostructure engineering for cathodes; and morphology engineering, elements doping, pore structure for anodes. Finally, the review provides an in-depth analysis of the solvated Na⁺ structure and the electrode/electrolyte interface mechanism and offers insights to the design of electrode materials, with the aim of facilitating the commercialization and large-scale deployment of SIBs in low-temperature conditions.