Salt cavern redox flow battery: The next-generation long-duration, large-scale energy storage system

Large-scale, long-duration energy storage systems are crucial to achieving the goal of carbon neutrality. Among the various existing energy storage technologies, redox flow batteries have the potential to store a significant amount of energy. In the redox flow battery system, the above-ground electrolyte storage tanks are usually bulky and expensive. Underground salt caverns, which have a space of hundred-thousand cubic meters, are being explored as potential alternatives to conventional electrolyte tanks for storing electrolytes. The salt caverns possess high safety, large storage capacity, constant temperature, and low cost, making salt cavern redox flow batteries promising next-generation energy storage systems in the era of carbon neutrality. This study reviews the fundamental concepts and research progress of salt cavern redox flow batteries and explores recently proposed organic active substances under near-neutral pH conditions. Prospects of salt cavern redox flow batteries are summarized and analyzed.