Cost-Effective, High-Energy-Density, Nonaqueous Nitrobenzene Organic Redox Flow Battery

Abstract

Nonaqueous organic redox flow batteries (NAORFBs) show great promise for grid energy storage but are currently facing key challenges such as high electroactive material cost and low energy density. Herein, we report the electrochemical properties and the potential application of a series of cost-effective electroactive nitrobenzene molecules in NAORFBs. Pairing the low-cost miscible liquid nitrobenzene (NB) with 2,5-di-tert-butyl-1-methoxy-4-(20-methoxyethoxy)-benzene (DBMMB) resulted in a flow battery that provides a high theoretical cell voltage of 2.2 V and a calculated energy density of 192 Wh L −1 . In the charge−discharge testing, this battery delivers a stable cycling capacity retention of 99.5% per cycle over 100 cycles and a 70% energy efficiency at 40 mA cm −2 operation current density, verifying that liquid nitrobenzene is a promising low-cost electroactive anode molecule for NAORFBs.

Carboxyl-Functionalized TEMPO Catholyte Enabling High-Cycling-Stability and High-Energy-Density Aqueous Organic Redox Flow Batteries

“…To address the shortcomings faced by inorganic RFBs, recent efforts have targeted RFBs employing sustainable and tunable organic electroactive molecules due to their high structural tunability, cost-effectiveness, high natural abundance, and safety features. − Apart from the general technical strengths of organic RFBs, aqueous organic RFBs have several additional attracting merits including incorporation of well-developed selective ionic membranes and non-flammable and highly conducting supporting electrolytes. − Great efforts have been taken to develop AORFBs by utilizing water-soluble organic anolytes (e.g., quinones, − viologens, ,, alloxazines, and phenazines) and catholytes (e.g., TEMPO ,− and ferrocenes , ). It should also be pointed out that remarkable development has also been achieved in non-aqueous organic RFBs (NAORFBs). − …”

Elucidating Instabilities Contributing to Capacity Fade in Bipyridine‐Based Materials for Non‐aqueous Flow Batteries

“…Electroactive species for non‐aqueous redox flow batteries have spanned the gamut, from small organic molecules, to metal coordination complexes (MCCs), to large metal‐based clusters, to hybrid systems [6–9] . A recent review by Palmer et al .…”

“…[3][4][5] Electroactive species for non-aqueous redox flow batteries have spanned the gamut, from small organic molecules, to metal coordination complexes (MCCs), to large metal-based clusters, to hybrid systems. [6][7][8][9] A recent review by Palmer et al summarizes the variety of metal-based charge carriers used in nonaqueous flow batteries in the past 5 years. [10] In our previous work, we optimized, modified, and evaluated the performance of symmetric and asymmetric iron bipyridine (bpy) based nonaqueous flow batteries originally published by Mun et al [11][12][13] By varying the electronics of bpy ligands, we tuned the redox potentials of the catholyte and anolyte with the goal of increasing operating voltage in symmetric iron bpy systems.…”

Liquid Nitrobenzene-Based Anolyte Materials for High-Current and -Energy-Density Nonaqueous Redox Flow Batteries

“…Herein, we select four types of anolyte materials based on nitrobenzene (NB), namely, NB, 2-nitrotoluene (2-NT), 3-nitrotoluene (3-NT), and 4-nitrotoluene (4-NT). NB is selected as the basic compound owing to its fast mass- and charge-transfer kinetics, high miscibility, and highly reversible electrochemical moiety. , When liquid 2,5-di- tert -butyl-1-methoxy-4-[2′-methoxyethoxy]­benzene (DBMMB) is used in the cathode side, the battery can yield high energy density. However, the battery suffered from irreversible capacity loss.…”