Doping Engineering of M-N-C Electrocatalyst Based Membrane-Electrode Assembly for High-Performance Aqueous Polysulfides Redox Flow Batteries

Polysulfides aqueous redox flow batteries (PS-ARFBs) with large theoretical capacity and low cost are one of the most promising solutions for large-scale energy storage technology. However, sluggish electrochemical redox kinetics and nonnegligible crossover of aqueous polysulfides restrict the battery performances. Herein, it is found that the Co, Zn dual-doped N-C complex have enhanced electrochemical adsorption behaviors for Na2S2. It exhibits significantly electrochemical redox activity compared to the bare glassy carbon electrode. And the redox reversibility is also improved from Delta V = 210 mV on Zn-doped N-C complex to Delta V = 164 mV on Co, Zn-doped N-C complex. Furthermore, membrane-electrode assembly (MEA) based on Co, Zn-doped N-C complex is firstly proposed to enhance the redox performances and relieve the crossover in PS-ARFBs. Thus, an impressively high and reversible capacity of 157.5 Ah L-1 for Na2S2 with a high capacity utilization of 97.9% could be achieved. Moreover, a full cell PS-ARFB with Na2S2 anolyte and Na-4[Fe(CN)(6)] catholyte exhibits high energy efficiency approximate to 88.4% at 10 mA cm(-2). A very low capacity decay rate of 0.0025% per cycle is also achieved at 60 mA cm(-2) over 200 cycles.

Automated summary

Co, Zn dual-doped N-C complex enhances the electrochemical adsorption behaviors for Na2S2 and improves the redox activity compared to the bare glassy carbon electrode. The membrane-electrode assembly (MEA) based on Co, Zn-doped N-C complex enhances the redox performances and relieves the crossover in PS-ARFBs, achieving an impressively high and reversible capacity of 157.5 Ah L-1 for Na2S2. Moreover, a full cell PS-ARFB exhibits high energy efficiency of approximately 88.4% at 10 mA cm(-2) and a very low capacity decay rate of 0.0025% per cycle at 60 mA cm(-2) over 200 cycles.