A Stable, Low Permeable TEMPO Catholyte for Aqueous Total Organic Redox Flow Batteries

Journal Article · Sat Dec 18 00:00:00 EST 2021 · Advanced Energy Materials

DOI:https://doi.org/10.1002/aenm.202102577· OSTI ID:1968560

Hu, Bo ^[1]; Hu, Maowei ^[1]; Luo, Jian ^[1]; Liu, T. Leo  ^[1]

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1. Utah State University, Logan, UT (United States)

We report aqueous organic redox flow batteries (AORFBs) are highly attractive for large-scale energy storage because of their nonflammability, low cost, and sustainability. (2,2,6,6-Tetramethylpiperidin-1-yl)oxyl (TEMPO) derivatives, a class of redox active molecules bearing air-stable free nitroxyl radicals and high redox potential (>0.8 V vs NHE), has been identified as promising catholytes for AORFBs. However, reported TEMPO based molecules are either permeable through ion exchange membranes or not chemically stable enough for long-term energy storage. Herein, a new TEMPO derivative functionalized with a dual-ammonium dicationic group, N¹, N¹, N¹, N³, N₃, 2, 2, 6, 6-nonamethyl-N³-(piperidinyloxy)propane-1,3-bis(ammonium) dichloride (N₂-TEMPO) as a stable, low permeable catholyte for AORFBs is reported. Ultraviolet–visible (UV–vis) and proton nuclear magnetic resonance (¹H-NMR) spectroscopic studies reveal its exceptional stability and ultra-low permeability (1.49 × 10^-12 cm² s^-1). Coupled with 1,1'-bis[3-(trimethylammonio)propyl]-4,4'-bipyridinium tetrachloride ((NPr)₂V) as an anolyte, a 1.35 V N2-TEMPO/(NPr)2V AORFB with 0.5 m electrolytes (9.05 Wh L^-1) delivers a high power density of 114 mW cm^-2 and 100% capacity retention for 400 cycles at 60 mA cm-2. At 1.0 m electrolyte concentrations, the N₂-TEMPO/(NPr)₂V AORFB achieves an energy density of 18.1 Wh L^-1 and capacity retention of 90% for 400 cycles at 60 mA cm^-2.

• Research Organization: Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
• Sponsoring Organization: USDOE; National Science Foundation (NSF); Utah Science Technology and Research initiative (USTAR); China CSC
• Grant/Contract Number: AC05-76RL01830; 1847674; 502995; 1429195
• OSTI ID: 1968560
• Report Number(s): PNNL-SA-169500
• Journal Information: Advanced Energy Materials, Vol. 12, Issue 8; ISSN 1614-6832
• Publisher: Wiley
• Country of Publication: United States
• Language: English

Related Subjects

energy storage
redox flow batteries
radical
renewable energy
TEMPO