钒电池电解液迁移性质的测定和半经验估算

The all vanadium redox flow battery (VRFB), an highly efficient energy-storage system could be operated with larger charge-discharged capacity and higher charge-discharged rate than some traditional battery system, shows great promise as a reliable and desired energy storage system for a wide range of applications such as wind turbine generators, photovoltaic power and intelligent networks. In the VRFB, the vanadium electrolyte is the core in the process of energy storage- release, so the thermodynamic properties of vanadium electrolyte is one of the key components in determining the performance and life of VRFB system..During the last National Natural Science Foundation, we studied and predicted the static thermodynamic properties of vanadium electrolyte adequately, which providing fundamental data for optimization and improvement of perfomance VRFB. Furthurmore, we realized that the transportation properties of Vanadium redox flow battery electrolyte, such as conductivity, viscosity, diffusion coefficient and transport number of Vanadium ion, showed more and more importance for the effective operation and regulation of the energy of VRFB energy storage system during the practical application. .Therefore, in this program, with the static thermodynamic properties be continued (such as surface tension), we focus on the determination and estimatation of the transportation properties for vanadium electrolyte. We hope to gain a semi-empirical formula to estimate the viscosity and the other transportation property for different state of vanadium electrolyte. So, as the continuation and development of the last Foundation Program, the results of this applied program would not only be used in other electrolyte system, but also enrich the content of solution study. And these results would help to the further Innovation and development of VRFB energy storage system.

钒电池作为可大容量、快速充放电、高效率的液流储能电池，在风能、太阳能发电及智能电网对大规模储能需求方面，极具应用前景。电解液是钒电池能量存储转换的核心，其热力学性质是决定电池系统性能和运行寿命的关键之一。青年基金项目已对钒溶液的静态热力学性质进行了充分系统的测定与预测，为钒电池运行状态优化控制和性能的提高提供基础数据。申请者在钒电池储能示范系统的实际运行中发现，钒溶液电导率、粘度、扩散系数、钒离子迁移数等迁移性质对钒电池储能系统的有效运行与能量调控十分重要。为此本项目在继续研究表面张力等静态性质的同时，重点对钒溶液的粘度、流动活化能、扩散系数、钒离子迁移数等迁移性质进行测定与估算，获得粘度方程等半经验公式，实现对不同状态钒溶液迁移性质的估算。本项目是前一个青年基金的继续和发展，其成果也将适用于其它电解质溶液体系，丰富溶液化学研究内容，达到溶液化学研究支撑新的钒电池应用创新开发的目的。

钒电池作为可大容量、快速充放电、高效率的液流储能电池，在风能、太阳能发电及智能电网对大规模储能需求方面，极具应用前景。电解液是钒电池能量存储转换的核心，其热力学性质是决定电池系统性能和运行寿命的关键之一。尤其是粘度等迁移性质，是反映溶液粘滞流动性质的重要参数，是提高电堆功率密度、优化系统能效的重要依据，是钒电池储能系统容量及能量管理的科学基础。.本项目系统测定了二元、三元以及部分四元钒溶液体系的粘度、密度、电导等迁移性质，计算了相关的热力学参数，并获得这些性质随温度、浓度的变化规律，深入探讨了离子溶剂化状态和离子缔合等微观相互作用；建立基于摩尔电导率与粘度的Walden规则的电导性质预测、基于黏滞流动活化能ΔμE≠的粘度性质预测，以及基于摩尔表面Gibbs自由能的表面张力性质预测方法，实现了钒溶液的迁移性质的预测，并可以进一步进行扩散系数以及钒离子迁移数等迁移性质的估算。同时，本项目还拓展了研究内容，进行了溶液/电极界面热效应、在线的溶液热力学性质研究，探讨了钒离子与水分子的迁移速率即及扩散系数对电极反应热效应的影响，并提出基于钒电解液粘度的在线监控液流电池SOC的方法，推进溶液理论研究与实际应用的结合。.本项目实现了钒溶液的研究，从静态热力学性质延伸到溶液的迁移性质，拓展了钒溶液热力学的研究空间，并为钒溶液在钒电池中的应用提供重要的科学支撑。同时，本项目提出的新概念和新方法也很有可能成为处理其它类似复杂电解质溶液体系的有力工具，在一定程度上促进溶液热力学理论和方法的发展。