Beyond conventional limits: Advancements and insights in broadening operating temperature ranges of supercapacitors

Supercapacitors (SCs), renowned for their exceptional power density and robust cycle life, are fast becoming indispensable in the realm of energy storage. Yet, their limited operational temperature range presents a significant barrier to their employment in extreme environments. This review offers a comprehensive exploration of recent strides made in broadening the operational temperature boundaries of SCs, with a sharp emphasis on trailblazing strategies and materials. It encompasses meticulous electrolyte engineering, innovative electrode material design, separator modifications, and the creation of advanced integrated architectures. At the core of this exploration lies the multifaceted universe of electrolytes, where the spotlight shines on the diversity and potential of aqueous, gel, organic, and ionic liquid electrolytes. Further, we underscore the pivotal role of electrode materials, emphasizing the importance of fine-tuning pore structures, surface areas, and intrinsic properties to enhance ion transport kinetics. Additionally, the often underappreciated yet critical function of separators in maintaining safety under wide-temperature operational windows is also thoroughly discussed. To conclude, we recognize the enduring challenges and look towards the horizon, exploring prospects concerning the development of cost-effective, high-performance materials, and optimized device designs that consider multicomponent interactions. The objective of this review is to offer valuable insights, fostering further advancements of SCs, particularly in adapting to and functioning within extreme environmental conditions.