Two-dimensional vermiculite nanosheets-modified porous membrane for non-aqueous redox flow batteries

The non-aqueous redox flow batteries (NARFBs) are promising for large-scale energy storage. However, the crossover contamination of active materials seriously imparts the performance. Here, two-dimensional (2D) vermiculite nanosheets modified Celgard porous membrane is prepared by the filtration method. The 2D vermiculite nanosheet layers stacked on the surface of Celgard membrane effectively reduce the crossover effect by sieving electrolytes and active materials through the nanoscale intercalation channels. Furthermore, the surface-governed transport behavior of the 2D vermiculite nanosheets is conducive to the exchange of supporting electrolyte. The resultant NARFB with the modified membrane exhibits higher Coulombic efficiency (95.3% vs. 87.6%) and larger discharge capacity (0.104 vs. 0.093 Ah L⁻¹) without obvious impact on voltage efficiency (90.1% vs. 90.5%) at 2 mA cm⁻². This work provides an efficient strategy to alleviate the crossover effect in NARFBs.