Development of Tetraarylphosphonium/Tetrakis(pentafluorophenyl)borate (TAPR/TFAB) salts as non-aqueous electrolytes for organic redox flow batteries

Abstract

A series of weakly coordinating cations/anions (TAPR/TFAB) ion pairs are, herein, being proposed as non-aqueous electrolytes for high capacity ORFBs. These were accessed via a Palladiumcatalyzed approach followed by the simple filtration/isolation of the product. These substituted tetraarylphosphonium/tetrakis(pentafluorophenyl)borate salts 1-4 where the substituents are a pmethoxy (1), a 3,4-dimethoxy (2), a p-phenyl (3), and a p-trimethylsilylacetylene (TMSA) (4) have potential use in several industries owing to their unique solubility in low polarity solvents. These salts constitute a new class of molecular ion pairs which can promote charge dissociation even in low polarity solvents because of their large size and bulkiness. The result being an increased conductivity in those media that can be useful for electrochemistry, advances in catalysis, battery technology, petroleum handling etc. This work supports the national security goal of fostering the development of affordable, clean and renewable energy source and storage.