There is an urgent need to break through the trade-off between proton conductivity and ion selectivity of proton exchange membrane(PEM)in vanadium flow battery(VFB).Proton channels in PEM are the key to controlling th...There is an urgent need to break through the trade-off between proton conductivity and ion selectivity of proton exchange membrane(PEM)in vanadium flow battery(VFB).Proton channels in PEM are the key to controlling the ion sieving and proton conductivity in VFB.Herein,two types of proton channels are reconstructed in the hybrid membrane via introducing modified Zr-MOFs(IM-UIO-66-AS)into SPEEK matrix.Internal proton channels in IM-UIO-66-AS and interfacial proton channels between grafted imidazole groups on Zr-MOFs and SPEEK greatly improve the conductivity of the IM-UIO-66-AS/SPEEK hybrid membrane.More importantly,both reconstructed proton channels block the vanadium-ion permeation to realize enhanced ion selectivity according to the size sieving and Donnan exclusion effects,respectively.Moreover,the hybrid membrane exhibits good mechanical property and dimensional stability.Benefiting from such rational design,a VFB loading with the optimized membrane exhibits enhanced voltage efficiency of 79.9%and outstanding energy efficiency of 79.6%at 200 m A cm^(-2),and keeps a notable cycle stability for 300 cycles in the long-term cycling test.Therefore,this study provides inspiration for preparing next-generation PEMs with high ion selectivity and proton conductivity for VFB application.展开更多
The high cost and complex modification process of carbon felt electrodes limits its further popularization in vanadium redox flow batteries(VFBs).By introducing low-cost melamine foam,nitrogen,phosphorus,and sulfur co...The high cost and complex modification process of carbon felt electrodes limits its further popularization in vanadium redox flow batteries(VFBs).By introducing low-cost melamine foam,nitrogen,phosphorus,and sulfur co-doped carbon nanotubes/melamine foam composite electrode(NPS-CNTs-CMF)is designed and fabricated via immersing melamine foam in a solution containing N,P,and S co-doped CNTs.The integration of modified CNTs significantly enhances the conductivity and hydrophilicity of the electrode.Moreover,the composite electrode also demonstrates outstanding electrocatalytic activity owing to the heteroatom doping that further inspired the electrocatalytic activity of CNTs.Density function theory cal-culations further uncover that introducing heteroatoms on CNTs not only promotes the adsorption of vanadium ions but also facilitates the electron transfer between vanadium ions and MF substrate.As a result,the battery loading with NPS-CNTs-CMF exhibits excellent battery performance,achieving energy efficiency of 80.12%at 300 mA cm^(-2).Additionally,the long-term cycling stability is attained over 200 consecutive charge-discharge cycles at 300 mA cm^(−2).This study provides a novel melamine foam mate-rial with low cost and simple modification,and this new composite structure stimulates the development of high-performance electrodes in VFBs.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.21975267)the Central Guidance on Local Science and Technology Development Fund of Liaoning Province(No:2022JH6/100100001)。
文摘There is an urgent need to break through the trade-off between proton conductivity and ion selectivity of proton exchange membrane(PEM)in vanadium flow battery(VFB).Proton channels in PEM are the key to controlling the ion sieving and proton conductivity in VFB.Herein,two types of proton channels are reconstructed in the hybrid membrane via introducing modified Zr-MOFs(IM-UIO-66-AS)into SPEEK matrix.Internal proton channels in IM-UIO-66-AS and interfacial proton channels between grafted imidazole groups on Zr-MOFs and SPEEK greatly improve the conductivity of the IM-UIO-66-AS/SPEEK hybrid membrane.More importantly,both reconstructed proton channels block the vanadium-ion permeation to realize enhanced ion selectivity according to the size sieving and Donnan exclusion effects,respectively.Moreover,the hybrid membrane exhibits good mechanical property and dimensional stability.Benefiting from such rational design,a VFB loading with the optimized membrane exhibits enhanced voltage efficiency of 79.9%and outstanding energy efficiency of 79.6%at 200 m A cm^(-2),and keeps a notable cycle stability for 300 cycles in the long-term cycling test.Therefore,this study provides inspiration for preparing next-generation PEMs with high ion selectivity and proton conductivity for VFB application.
基金supported by the National Key R&D Program of China(Grant No.2022YFB2404901)the National Natural Science Foundation of China(Grant No.21975267)the Central Guidance on Local Science and Technology Development Fund of Liaoning Province(No.2022JH6/100100001).
文摘The high cost and complex modification process of carbon felt electrodes limits its further popularization in vanadium redox flow batteries(VFBs).By introducing low-cost melamine foam,nitrogen,phosphorus,and sulfur co-doped carbon nanotubes/melamine foam composite electrode(NPS-CNTs-CMF)is designed and fabricated via immersing melamine foam in a solution containing N,P,and S co-doped CNTs.The integration of modified CNTs significantly enhances the conductivity and hydrophilicity of the electrode.Moreover,the composite electrode also demonstrates outstanding electrocatalytic activity owing to the heteroatom doping that further inspired the electrocatalytic activity of CNTs.Density function theory cal-culations further uncover that introducing heteroatoms on CNTs not only promotes the adsorption of vanadium ions but also facilitates the electron transfer between vanadium ions and MF substrate.As a result,the battery loading with NPS-CNTs-CMF exhibits excellent battery performance,achieving energy efficiency of 80.12%at 300 mA cm^(-2).Additionally,the long-term cycling stability is attained over 200 consecutive charge-discharge cycles at 300 mA cm^(−2).This study provides a novel melamine foam mate-rial with low cost and simple modification,and this new composite structure stimulates the development of high-performance electrodes in VFBs.
