Preparation of N-B doped composite electrode for iron-chromium redox flow battery

Iron-chromium redox flow battery(ICRFB)is an electrochemical energy storage technology that plays a vital role in dealing with the problems of discontinuity and instability of massive new energy generation and improving the acceptance capacity of the power grid.Carbon cloth electrode(CC)is the main site where the electrochemical reaction occurs,which always suffers from the disadvantages of poor electrochemical reactivity.A new N-B codoped co-regulation Ti composite CC electrode(T-B-CC)is firstly generated and applied to ICRFB,where the REDOX reaction can be promoted significantly owing to the plentiful active sites generated on the modified electrode.As contrasted with ICRFB with normal CC electrode,after 50 battery charge/discharge cycles,the discharge capacity(1,990.3 mAh vs 1,155.8 mAh)and electrolyte utilization(61.88%vs 35.94%)of ICRFB with CC electrode(T-B-CC)are significantly improved.Furthermore,the energy efficiency(EE)is maintained at about 82.7%under 50 cycles,which is 9.3%higher than that of the pristine electrically assembled cells.The comodulation of heteroatom doping and the introduction of Ti catalysts is a simple and easy method to improve the dynamics of the Cr^(3+)/Cr^(2+)and Fe^(3+)/Fe^(2+)reactions,enhancing the performance of ICRFBs.

Synergistic effect of electrode defect regulation and Bi catalyst deposition on the performance of iron–chromium redox flow battery

Iron-chromium redox flow batteries (ICRFBs) possess advantages of high safety,long cycle time,and lowcost.Increasing Cr^(3+)/Cr^(2+)reaction activity is suggested as one of the most promising strategies to improve the performance and prolong the lifetime of ICRFBs.To improve the slow reaction kinetics of the negative electrode,a type of defected carbon cloth with Bismuth (Bi) catalyst introduction is prepared by defect engineering method and electrochemical deposition,which provided defect sites and active sites to catalyze the redox couple’s reaction of ICRFBs.Furthermore,this modified carbon cloth adsorbs Cr(Ⅲ)hydrate more easily,which has a more stable structure and can significantly improve the performance of ICRFBs.Both experimental analysis and theoretical calculation indicated that the modified electrode has excellent electrocatalytic ability,which can enhance the reaction rate of Cr^(3+)/Cr^(2+),improve capacity retention and stabilize cycling performance.The capacity degradation rate of an ICRFB single cell with the modified electrodes is just 0.23%per cycle at a current density of 140 m A/cm^(2).Additionally,the energy efficiency (EE) remains around 83%,which is 8.45%higher than that of the pristine electrode assembled battery under 60 cycles.This work supplies a simple method to obtain a high-performance electrode material for ICRFBs and makes it a practical solution to promote ICFRBs large-scale commercialization process.