title: A Protocol for Electrochemical Evaluations and State of Charge Diagnostics of a Symmetric Organic Redox Flow Battery.
abstract: Redox flow batteries have been considered as one of the most promising stationary energy storage solutions for improving the reliability of the power grid and deployment of renewable energy technologies. Among the many flow battery chemistries, non-aqueous flow batteries have the potential to achieve high energy density because of the broad voltage windows of non-aqueous electrolytes. However, significant technical hurdles exist currently limiting non-aqueous flow batteries to demonstrate their full potential, such as low redox concentrations, low operating currents, under-explored battery status monitoring, etc. In an attempt to address these limitations, we recently reported a non-aqueous flow battery based on a highly soluble, redox-active organic nitronyl nitroxide radical compound, 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (PTIO). This redox material exhibits an ambipolar electrochemical property, and therefore can serve as both anolyte and catholyte redox materials to form a symmetric flow battery chemistry. Moreover, we demonstrated that Fourier transform infrared (FTIR) spectroscopy could measure the PTIO concentrations during the PTIO flow battery cycling and offer reasonably accurate detection of the battery state of charge (SOC), as cross-validated by electron spin resonance (ESR) measurements. Herein we present a video protocol for the electrochemical evaluation and SOC diagnosis of the PTIO symmetric flow battery. With a detailed description, we experimentally demonstrated the route to achieve such purposes. This protocol aims to spark more interests and insights on the safety and reliability in the field of non-aqueous redox flow batteries.
authors.affiliation: Joint Center for Energy Storage Research (JCESR); Energy & Environment Directorate, Pacific Northwest National Laboratory.
authors.forename: Wentao
authors.initials: W
authors.lastname: Duan
authors.affiliation: Joint Center for Energy Storage Research (JCESR); Earth & Biological Systems Directorate, Pacific Northwest National Laboratory.
authors.forename: Rama S
authors.initials: RS
authors.lastname: Vemuri
authors.affiliation: Earth & Biological Systems Directorate, Pacific Northwest National Laboratory.
authors.forename: Dehong
authors.initials: D
authors.lastname: Hu
authors.affiliation: Joint Center for Energy Storage Research (JCESR); Physical & Computational Sciences Directorate, Pacific Northwest National Laboratory.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Yang
authors.affiliation: Joint Center for Energy Storage Research (JCESR); Energy & Environment Directorate, Pacific Northwest National Laboratory; Xiaoliang.Wei@pnnl.gov.
authors.forename: Xiaoliang
authors.initials: X
authors.lastname: Wei
mesh_terms: D003497:Cyclic N-Oxides / Q000737:chemistry*; D011211:Electric Power Supplies; D004563:Electrochemistry / Q000379:methods*; D004566:Electrodes; D004573:Electrolytes / Q000737:chemistry; D016166:Free Radical Scavengers / Q000737:chemistry*; D007093:Imidazoles / Q000737:chemistry*; D009930:Organic Chemicals; D010084:Oxidation-Reduction; D015203:Reproducibility of Results; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D003497:Cyclic N-Oxides; D004573:Electrolytes; D016166:Free Radical Scavengers; D007093:Imidazoles; D009930:Organic Chemicals; C079391:2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide