A cost-effective nafion/lignin composite membrane with low vanadium ion permeation for high performance vanadium redox flow battery

Here we report an eco-friendly Nafion/lignin composite membrane with excellent performance for vanadium redox flow battery (VRFB). Through facile solution casting, the Nafion/lignin composite membrane presents the merits of high conductivity and low vanadium ions permeability. Under high current density (120 mA cm(-2)), the VRFB single cell with the optimized Nafion/lignin composite membrane exhibits superior performance metrics to commercial counterpart: high Coulombic efficiency (similar to 97.4%) and energy efficiency (similar to 82.7%), and prominent cyclability with slower capacity decay for similar to 52.8% capacity retention after 1000 cycles (vs. Nafion 212 membrane similar to 34.8% after only 150 cycles). More importantly, compared with the pristine Nafion 212 membrane, the cost of the composite membrane is reduced sharply by reducing the usage amount of Nafion polymer, while maintaining the membrane stability. Thus, the Nafion/lignin composite membrane is one of the competitive candidates for VRFB towards commercialization.

Automated summary

The Nafion/lignin composite membrane shows excellent performance in VRFB, with high conductivity, low vanadium ions permeability, and outstanding cycling stability. Compared to commercial counterparts, it exhibits higher Coulombic efficiency and energy efficiency.