A high selective membrane based on SPEEK and sulfonated lignin-modified GO for vanadium redox flow batteries

Addressing the membrane’s dilemma between H + conduction and V n+ ion crossover is a challenge for developing the vanadium redox flow batteries (VRFBs). Herein, we developed a series of composite membranes by incorporating sulfonated lignin-modified graphene oxide (GO@SL) into sulfonated polyether ether ketone (SPEEK). The GO@SL effectively improves H + conduction and V n+ ion resistance of the SPEEK/GO@SL. Relative to the pure SPEEK, the SPEEK/GO@SL composite membranes exhibit higher selectivity (144.8 × 10 3 S min cm −3 ). The SPEEK/GO@SL-2 exhibits a higher energy efficiency (81.2% at 100 mA cm −2 ) and excellent stability. This work validates the significant potential of the GO@SL composite for crafting next-generation ion exchange membranes, offering a promising strategy to overcome the conductivity-permeability trade-off.