Current status and future perspectives of low-temperature electrolytes for supercapacitors

Supercapacitors are critical for high-power applications due to their fast charge-discharge capabilities and long lifespans. However, achieving high performance at ultra-low temperatures remains a significant challenge, limiting their use in extreme environments. The electrolyte responsible for ion transport is the key factor governing the low-temperature performance of supercapacitors. In this perspective, we focus on the recent advances in low-temperature electrolytes for supercapacitors. We first introduce the critical physical parameters for evaluating low-temperature electrolytes. Then, we emphasize the key design strategies for low-temperature electrolytes, followed by a detailed discussion of their anti-freezing mechanisms, encompassing aqueous, organic, ionic liquid, and gel-based electrolytes. Additionally, particular emphasis is placed on the theoretical simulation and advanced characterization techniques, given their capability to elucidate the microscopic structure of the electrolyte and provide comprehensive insights into its energy storage mechanism. Finally, we have provided an outlook on the current challenges and future development directions of low-temperature electrolytes, which is expected to offer promising strategies for reliable, high-performance supercapacitors in ultra-low temperature applications.