Towards a high efficiency and low-cost aqueous redox flow battery: A short review.

The aqueous redox flow battery (ARFB), a promising large-scale energy storage technology, has been widely researched and developed in both academic and industry over the past decades owing to its intrinsic safety and modular designability. However, compared to other technologies (e.g. Li-ion batteries), the relatively low energy density, inferior efficiency, and high investment cost of the ARFB limit its further applications. Although tremendous efforts have been made to improve the performance as well as the cost-effectiveness of ARFB by various approaches, it is still a challenge to recognize a united and general roadmap for the next commercial-available ARFB. Here we review the evaluation criteria for the performance of flow batteries and the development status of different types of flow batteries. The factors affecting the performance of flow batteries are analyzed and discussed, along with the feasible means of improvement and the cost of different types of flow batteries, which is expected to provide useful references for the further development of high-efficiency and low-cost flow batteries. • Performance/cost balance is the key to low cost flow batteries • The characteristics of various aqueous redox flow batteries are discussed • Challenges include low energy density, slow kinetics, and instability • Future trends favor aqueous organic and iron-based chemistries [ABSTRACT FROM AUTHOR]