Low permeability polybenzimidazole (PBI) membrane for redox flow battery

摘要

A redox flow battery membrane, a redox flow battery incorporating the membrane, and a method of forming the membrane are disclosed. The membrane comprises a densified polybenzimidazole gel membrane capable of incorporating a high liquid content without loss of the structure formed according to a process including densification of the gel membrane after in situ hydrolysis of a polyphosphoric acid solvent. The densified membrane is then impregnated with a redox flow battery supporting electrolyte such as sulfuric acid, which has a very high ionic conductivity of about 50 mS/cm or more, and of about 10 -7 cm 2 /s or less, redox couple ions, eg For example, it can operate with low permeability of vanadium ions. Redox flow batteries incorporating membranes can operate at current densities of about 50 mA/cm 2 or more.