Grafting and Solubilization of Redox‐Active Organic Materials for Aqueous Redox Flow Batteries

This study concerns the development of sustainable design strategies of aqueous electrolytes for redox flow batteries using redox‐active organic materials. A green spontaneous grafting reaction occurs between a redox‐active organic radical and an electrochemically activated structural modifier at room temperature through a simple mixing step. Then, a physical mixing method is used to formulate a structured aqueous electrolyte and enables aqueous solubilization of the organic solute from below 0.5 to 1.5 m beyond the conventional dissolution limit. The as‐obtained concentrated mixture can be readily used as catholyte for a redox flow battery. A record high discharge cell voltage (1.6 V onset output voltage) in aqueous non‐hybrid flow cell is attained by using the studied electrolytes. Hard graft: Sustainable design strategies for aqueous electrolytes in redox flow batteries using redox‐active organic materials. The obtained concentrated mixtures can be readily used as catholyte for a redox flow battery. A record high discharge cell voltage is attained in an aqueous non‐hybrid flow cell.