低共熔溶剂中的质量-电荷传输特性分析及以其为电解液的液流电池性能改善研究

Nowadays, the energy density of the redox flow battery is far from the initial anticipation. One of the main reasons is that the solubility of active redox couples is very low. Enlarging the energy density of redox flow battery is critically important for the reduction of system volume, the wideness of application scope and the decline of capital cost. The previous research works have shown that using non-aqueous electrolyte enables the improvement in solubility of active ions, which means the improvement in energy density. Besides, the non-aqueous electrolyte can enlarge the electrochemical window for redox flow battery. However, the transport rate and electrochemical reaction rate for the active ions in non-aqueous electrolyte are approximately one order of magnitude lower than that in the conventional aqueous electrolyte, such that the performance of the flow battery with non-aqueous electrolyte is largely reduced. To address these problems, we propose this project. Firstly, we will accurately measure the key transport parameters inside the porous electrode in the non-aqueous deep eutectic solvent (DES) electrolyte, like effective diffusivity and ion mobility via electrochemical approaches. Then the effects of external filed and electrolyte additive will be studied, followed by proposing some methods to synergistically enhance the ion transport and electrochemical reactions in DES. With the aid of the measured key transport parameters, we will then develop a comprehensive numerical model to describe the coupled mass transport and electrochemical processes within the flow battery with DES electrolyte. The effects of operating condition, electrode material property and flow field in the flow field on the cell performance and system efficiency will be modeled. By analyzing the experimental and modeling results, we will propose the schemes to improve the performance and system efficiency. Finally, a lab-scale prototype of flow battery with DES electrolyte will be set up for demonstration. This project is meaningful for exploring the mechanism of coupled mass and electron transport in the DES, enhancing the performance and efficiency of the energy storage system and pratically advancing the utilization of sustainable energy sources.

目前液流电池的能量密度还未达预期目标，主要的原因是活性物质在电解液中的溶解度过低。前期的研究表明使用非水系电解液能有效提高电池的能量密度。但是在非水体系电解液中，电池性能有很大的下降。针对这些问题，本项目拟对在一类价格低廉的非水电解液体系--低共熔溶剂（Deep eutectic solvents，DES）中活性物质的传输和电化学特性进行研究。在DES中，用电化学的方法精确确定液流电池的活性物质在多孔电极内的关键传质参数，如有效扩散系数和离子淌度等。研究外场作用和电解液添加剂对活性物质传质和电化学反应的影响。探索在DES电解液中实现传质过程和电化学反应的协同强化的途径。建立一个DES电解液液流电池数值模型。通过分析实验和模拟结果，揭示提高性能和改进效率的规律并据此建立一个小型的演示液流电池。该项目对提高液流电池的性能和效率，促进可再生能源的利用有重要的意义。

目前液流电池的能量密度还未达预期目标，主要的原因是活性物质在电解液中的溶解度过低。前期的研究表明使用非水系电解液能有效提高电池的能量密度。但是在非水体系电解液中，电池性能有很大的下降。针对这些问题，本项目围绕对在一类价格低廉的非水电解液体系--低共熔溶剂（Deep eutectic solvents，DES）中活性物质的传输和电化学特性进行研究。在DES中，用电化学的方法精确确定液流电池的活性物质在多孔电极内的关键传质参数，如有效扩散系数和离子淌度等。研究极性气体、支持电解液、金属离子电解液添加剂和外场作用（磁场和超声波）对活性物质传质和电化学反应的影响，并探索其在DES电解液中的协同作用规律，并实现传质过程和电化学反应的协同强化。建立了一个DES电解液液流电池数值模型，模拟电极结构和运行参数对电池性能的影响。通过分析实验和模拟结果，揭示提高性能和改进效率的规律并由此建立一个小型的演示液流电池。该项目对提高非水系液流电池的性能和效率，促进可再生能源的高效低价利用有重要的意义。