Redox flow batteries (RFBs) are among the most investigated technologies for large scale energy storage applications. Since the first commercialization of all-vanadium RFB (in the early 90’s), the technology has evolved towards the development of new systems. This review focuses on three innovative concepts including aqueous organic RFB (AO-RFB), dual-circuit RFB and redox solid booster-based RFB. We will highlight the recent advances in the last five years and discuss the main challenges encountered. Particularly, we focused on the utilization of redox-mediated process to reach higher energy density than conventional RFB.