Endowing nonionic membrane with superior ionic selectivity by using g-C3N4 for redox flow battery
Chunxiao Wu, Shanfu Lu, Haining Wang, Sian Chen, Yan Xiang
Abstract
Increasing selectivity without sacrificing ionic conductivity of membranes is desirable for advanced vanadium redox flow batteries (VRFBs) as protons serve as charge-balancing ions, limiting the power density and battery efficiency. g-C 3 N 4 nanosheets have previously been used to construct proton-exchange membranes (PEM) but only modest performance harvests. Here to leverage advanced membrane using g-C 3 N 4 , we reveal the underlying factor that yields desired performance, scrutinizing both computationally and experimentally. g-C 3 N 4 nanosheets are introduced into nonionic host matrix for membrane construction, addressing the twofold goal of facilitating proton transport and vanadium ion repulsion. Our membrane demonstrates high ionic conductivity of 44.4 mS/cm and selectivity of 4.8 × 10 6 S⋅min/cm 3 . The assembled battery reaches the columbic efficiency of 99% and energy efficiency of 85% at 200 mA/cm 2 , and robust cycling stability.