基于结构连续可调控三维多孔电极的微流体燃料电池传输特性及性能强化

A microfluidic fuel cell is a type of simplified miniature power sources, which utilizes the co-laminar flow nature of fuel/oxidant in microchannel and therefore eliminates the traditional proton exchange membrane. However, present power supply can’t meet the power demand of micro electromechanical systems. In this proposal, we try to use the novel three dimensional (3D) direct-ink writing printing technique to construct the open porous structure for electrodes. This structure is promising in improving the electrochemical-active surface area and facilitating the mass transportation interior the electrodes, and further boosting the cell performance and fuel utilization. As one type of electrochemical energy transformation techniques, the microfluidic fuel cell with 3D porous electrodes is studied from the aspects of multiphase flow, multicomponent mass transportation, distribution of open pores and electricity-generation properties by experimental and theoretical calculation methods. The effects of pore structure (e.g. pore size, pore distribution) and operational parameters on the power-generation properties are studied. It is hopefully established the characteristics of flow field and multicomponent mass transportation interior the complicated porous electrodes. Based on the equations of charge conservation, energy conservation and potential distribution, it is hopefully established the models of mass transportation and power generation interior the whole microfluidic fuel cell. These models are promising in illustrating the roles of pore structure in mass transportation and power-generation property, and can serve as a theoretical basis to micro fuel cells to be a power-supply for the micro electromechanical systems.

微流体燃料电池是一种结构简化的微能源技术，它利用燃料/氧化剂溶液的自然分层流动移除了传统的质子交换膜，但其目前的功率输出仍不能为微机电等微小系统供电。本项目利用新兴的三维打印直接墨水书写技术，通过构建电极侧连续可调控的开放孔隙结构增加了电极的电化学活性面积和强化了电极内的物质传输，提高了电池性能和燃料利用率。针对具有多孔电极的微流体燃料电池这一电化学能源转化技术，从多相流体流动与多组分物质传输、开放孔隙分布和产电特性等方面开展系统的创新性实验和理论研究工作，研究孔隙大小、分布等孔特性以及环境参数、运行方式等外部因素对电池能量输出的影响规律，获得微流体在连续可调控多孔电极内的流场分布和多组分传输特性；基于电荷守恒、能量守恒及电位分布方程，获得电池内物质传输模型及性能预测模型，揭示电池内孔隙结构、物质传输和电池能量输出之间的关系，为微型燃料电池成为可靠的微机电电源技术奠定理论基础。

微流体燃料电池是一种结构简单的微能源技术，它利用燃料/氧化剂溶液的自然分层流动取代了传统的质子交换膜，但现有的功率输出仍不能在芯片上为微小系统供电，电极在受限空间内缓慢的传质成为限制其性能输出的瓶颈问题。本项目针对上述问题，利用多种方法构建了孔隙结构、孔隙尺寸等孔特性连续可调控的三维多孔电极，实验研究了商用多孔电极（泡沫镍）及自组装的石墨烯气凝胶、银纳米线气凝胶等多孔电极孔隙大小、分布、电极厚度等电极物理性质变化对电极物质传输及电化学性能的影响；通过墨水书写技术、模板法、溶胶-凝胶等多种方法进一步构建了孔特性可控的石墨烯气凝胶，揭示了具有三维可调控多孔电极的微流体燃料电池内物质传递及其对产电性能的影响规律，大幅度提升了微流体燃料电池开路电压和功率输出；获得了含有电化学反应的三维可调控多孔电极内多组分传输模型，在此基础上成功耦合了微通道内层流流动阴极侧反应及电极间氢离子传输规律，揭示了微通道内反应物浓度、电流密度与电位分布之间的关系。针对具有三维可调控多孔电极的微流体燃料电池内两相流动与传输现象，从理论角度研究了商用多孔电极和自组装银纳米线气凝胶复杂微孔隙结构内物质输运与生化反应的耦合作用关系，及催化反应界面分布对电极反应速率的影响规律；获得了微流道内耦合电化学反应、反应物传输、荷电粒子传递的理论模型，揭示了微流体燃料电池内物质分布及传输规律，从而为微型电化学能源系统及芯片式电化学传感器的研究发展奠定了理论基础。