摘要
本文采用分散涂层法在聚丙烯腈碳毡表面涂覆溶胶凝胶处理的间二苯酚糖醛介孔碳,合成了一种新型的全钒氧化还原液流电池阳极材料.介孔碳涂层修饰的碳毡分别在900和1100°C下经过退火处理,对所得样品的形貌、表面化学性质、电化学性能进行了表征,并与未经修饰的碳毡进行了比较.结果表明,介孔碳涂层的引入显著增加了材料的比表面积,特别是1100°C下退火处理的样品,其表面的活性含氧基团明显增多.介孔碳涂层对电化学性能的影响呈现出混合效应.循环伏安法测试表明,介孔碳涂层修饰使V(IV)/V(V)氧化还原反应对的氧化和还原反应的最大电淋度增加了约3 0%,这可以归因于材料表面活性反应位点的增加.然而,介孔碳涂层同时导致了电导率的降低,体现为氧化还原峰分离和电荷迁移阻抗的增加.对电导率的这一负面效应可通过1100°C以上高温热处理缓解,从而改善其表面石墨化以减弱氧化还原峰分离和电荷迁移阻抗,使其能与未修饰的碳毡相当.
A novel anode material for all-vanadium redox flow battery was synthesized by dispersion coating of sol-gel processed(resorcinol-furaldehyde) mesoporous carbon(MPC) onto the surface of polyacrylonitrile carbon felt(CF).The coated samples were then annealed at 900℃ and1100℃ and the subsequent morphology,surface chemistry,and electrochemical properties of the MPC coated CF were characterized and compared with an uncoated CF.Addition of the MPC coating is shown to dramatically increase surface area while also increasing the number of active surface oxygen groups particularly for samples annealed at 1100℃.MPC coating shows a mixed effect on electrochemical properties.Characterization with cyclic voltammetry reveals the introduction of MPC coating provides roughly 30%increase in peak current density for the oxidation and reduction reactions of the V(IV)/V(V) redox couple,which is attributed to the significantly increased number of active reaction sites.However,MPC coating seems to be accompanied by a reduction in conductivity as demonstrated by increased redox peak separation and charge transfer resistance.This negative effect on conductivity can be mitigated by heat treatment(at or above 1100℃) which improves surface graphitization reducing redox peak separation and charge transfer resistance such that it is comparable with uncoated samples.
基金
support of UniEnergy Technologies and the University of Washington Clean Energy Institute
