Electrochemical and Engineering Approaches Toward Technological Advancement of Non-aqueous Redox Flow Batteries. PhD thesis, Masdar Institute of Science and Technology.

  • Musbaudeen O. Bamgbopa

Student thesis: Doctoral Thesis

Abstract

Non-aqueous redox flow batteries (NARFBs) – developed with the aim of providing higher energy density than their aqueous redox flow batteries (RFBs), have presently not been able to fulfil the target. The setbacks including; low active species solubility, costly electrolytes, high internal resistance and incompatible membranes, still persist – contributing to low cycle efficiency. This dissertation addresses these issues towards technological advancements of NARFBs for possible future commercialization. Firstly, a systematic examination of the use of solvent mixtures for NARFBs was explored to increase energy density and efficiency, considering active species solubility, electrolyte conductivity, and redox reaction rates among a number of binary and ternary solvent mixtures. An optimum solvent mixture was identified – which also provided good capacity retention, following studies on the influence of the solvent on crossover through different membranes was done. This work also presents a developed inexpensive, fast-charging capable iron–chromium NARFB – pointing out an additional potential advantage NARFBs can have over aqueous RFBs. Development and testing of a composite Nafion/SiO2 membrane provided low active permeability which helped achieve long cycling of the battery, thereby opening up the potential of NARFBs with multiple active species. To address issues encountered with commercial ion exchange membranes in NARFB electrolyte environments, as well as a cost reduction measure, this work also explored the prospects of applying membraneless designs for macro-scale RFBs. A new design of a membraneless RFB based on immiscible electrolytes was presented, capable of recharging and recirculation of the same electrolyte streams for multiple cycles and maintains the advantages of the decoupled power and energy densities.
Date of AwardDec 2017
Original languageAmerican English

Keywords

  • Energy storage
  • Electrochemical and Engineering Approaches
  • electrochemical energy storage.

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