钒电池负极反应动力学研究与高性能负极的构建

Vanadium flow battery (VFB) is one of the most promising energy storage technologies which are used to support the wide application of the renewable energy sources, but currently its further development is limited by its energy storage cost. The development of the high power stack for VFB might be an important approach to reducing the corresponding energy storage cost. However, the polarization of the negative process during the discharging process (especially for the high rate discharge) for a VFB is much more than that of the positive, so it is necessary to conduct the specialized kinetic research in the negative reaction and illuminate the limiting factor of negative process. Based on these, the advanced negative electrode materials for VFB will be constructed and then the high power stack could be developed. .However, it is hard to construct the intense research in the negative reaction because of the coupling of the potential windows of the negative reaction and hydrogen evolution reaction. Based on this, the hydrogen inhibiting components are firstly used to separate the negative reaction of VFB and hydrogen evolution reaction. Following the kinetic research in the negative research could be conducted on the premise of eliminating the disturbance of hydrogen evolution reaction, and the kinetic equation of the negative reaction in addition to the corresponding influence rule are established at last. The other innovation point of this project is that the limiting factor of negative process could be illuminated by studying the interrelationship of the hydrogen inhibiting components, the active groups and the kinetic characteristics of the negative reaction. And the optimal design and verification of the advanced negative electrode materials will be carried out finally. The completion of this project will provide strong theory support for the design and preparation of the electrode materials used in VFB, as well as play an important role in the development kinetics theory of the negative process.

作为支撑可再生能源普及应用最具潜力的储能技术之一，钒电池的储能成本是现阶段制约其发展的关键，而开发高功率电堆则是降低其储能成本的重要途径。但钒电池在放电过程（尤其大电流放电）中负极的极化远大于正极，须针对钒电池负极反应进行动力学研究，阐明负极过程的限制性因素，从而实现高性能负极的构建以及高功率电堆的开发。.然而钒电池负极反应和析氢副反应电位区间的重叠导致难以针对负极反应进行深入研究。基于此，本项目率先提出利用析氢抑制组分，实现钒离子负极反应和析氢副反应的有效分离，进而对负极反应展开动力学研究，建立负极反应动力学方程及其影响规律；本项目另一个创新点在于通过深入研究析氢抑制组分、活性基团与负极反应动力学行为的内在关系，阐明负极过程的限制性因素，并最终实现高性能负极材料的设计与优化验证。本项目不仅为高性能钒电池负极材料的设计提供科学依据，同时对发展和完善负极过程动力学理论发挥积极作用。

作为支撑可再生能源普及应用最具潜力的储能技术之一，钒电池的储能成本是现阶段制约其发展的关键，而开发高功率电堆则是降低其储能成本的重要途径。但钒电池在放电过程中负极的极化远大于正极，须针对钒电池负极反应进行动力学研究，阐明负极过程的限制性因素，从而实现高性能负极的构建以及高功率电堆的开发。然而钒电池负极反应和析氢副反应电位区间的重叠导致难以针对负极反应进行深入研究。.基于此,我们通过控制极化电位与电极表面状态的方法，有效地避免了析氢副反应的影响,针对钒电池负极过程进行了系统的动力学研究。结果发现钒电池负极反应仅为简单的单电子转移过程，氢离子并不参与反应，在此基础上建立了石墨电极表面V3+还原反应的动力学方程，并发现钒离子浓度以及温度的增加均有利于V3+/V2+的电化学反应，且负极钒离子的传质速率与电化学反应速率均小于正极。.通过活性基团的修饰可以提高负极的电催化活性，但同时会降低其析氢过电位，生成的原子态H会占据电极活性位点，进而导致严重的电化学极化，因此我们可以推断负极过程是钒电池性能的限制性过程。针对钒电池限制性负极，我们从有效比表面和析氢过电位两个角度进行了高效钒电池负极的构建。首先通过不同方法制备了几种具有高有效比表面的电极材料：PRGO/ECNFs、GO/CF复合电极、CO2活化的碳毡电极和有序多孔电极。结果表明：提升电极的电化学反应面积可以有效改善电极尤其是负极的电化学活性，进而提升电池效率。该方法简单高效，更易于实现工程化，为高活性钒电池电极材料的制备提供了新的设计思路。其次结合静电纺丝技术，将具有高析氢过电位的金属铟和锡引入到电纺纤维中，制得了具有高析氢过电位的纳米碳纤维复合电极。结果表明：该复合电极不仅对负极反应具有优异的电催化活性，对析氢副反应也具有明显的抑制作用，有望成为一种新型、高效的钒电池负极材料。.本项目不仅为高性能钒电池负极材料的设计提供科学依据，同时对发展和完善负极过程动力学理论发挥积极作用。

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