An Aqueous Redox‐Flow Battery with High Capacity and Power: The TEMPTMA/MV System

TLDR

Redox‑flow batteries can store large amounts of electric energy, making them attractive for stabilizing wind and solar farms, but most designs rely on acidic metal salts or low‑performance organics. The study introduces a battery that uses TEMPTMA and MV as redox‑active materials in a simple, safe aqueous solution. The battery employs TEMPTMA and MV dissolved in a simple, safe aqueous solution as the redox‑active components. The TEMPTMA/MV battery delivers 54 Ah L⁻¹ capacity (38 Wh L⁻¹ at 1.4 V) and peak current densities up to 200 mA cm⁻², making it suitable for compact high‑capacity, high‑power applications.

Abstract

Redox-flow batteries (RFB) can easily store large amounts of electric energy and thereby mitigate the fluctuating output of renewable power plants. They are widely discussed as energy-storage solutions for wind and solar farms to improve the stability of the electrical grid. Most common RFB concepts are based on strongly acidic metal-salt solutions or poorly performing organics. Herein we present a battery which employs the highly soluble N,N,N-2,2,6,6-heptamethylpiperidinyl oxy-4-ammonium chloride (TEMPTMA) and the viologen derivative N,N'-dimethyl-4,4-bipyridinium dichloride (MV) in a simple and safe aqueous solution as redox-active materials. The resulting battery using these electrolyte solutions has capacities of 54 Ah L-1 , giving a total energy density of 38 Wh L-1 at a cell voltage of 1.4 V. With peak current densities of up to 200 mA cm-2 the TEMPTMA/MV system is a suitable candidate for compact high-capacity and high-power applications.