Rapid spray-crosslinked assembly of a stable high-performance polyelectrolyte bipolar membrane

Bipolar membrane processes have evolved as one of the most promising technologies in the field of acid and base production as well as many interesting separation applications. Herein, we report a rapid spray-crosslinked assembly for fabricating a high-performance polyelectrolyte bipolar membrane. Polyvinyl alcohol (PVA), glutaricdialdehyde (GA) and polyethyleneimine (PEI) are alternatively and successively sprayed onto a supporting cation-exchange membrane. GA crosslinked PVA and PEI are responsible for the interlayer and anion-exchange layer, respectively. Under optimal conditions, at a current density of 100 mA cm−2, the cell voltage of the BPM was as low as 1.79 V. Moreover, it has been demonstrated that the spray crosslinked membrane has good stability in acid and alkali harsh conditions. In contrast to the traditional casting method, spray assembly combined with chemical cross-linking can tune the membrane thickness at the nanoscale and microscale levels, as well as increase its charge density and ion-exchange capacity. This facile approach might open a new way to efficiently and flexibly produce various bipolar membranes with different polyelectrolytes.