纯甲醇进料自适应式直接甲醇燃料电池传质与电化学反应耦合规律研究

A passive direct methanol fuel cell (DMFC) operating with neat methanol is highly desirable to reduce the volume of the system and maximize the specific energy for portable electronic products' applications. In order to achieve pure methanol as fuel, the self-adaptability of DMFCs needs to be solved including the methanol pervaporation, low concentration of methanol in the anodic catalyst layer, mass transfer of oxygen at cathode and counter-diffusion of water from cathode to anode. We propose that on the basis of using a pervaporation method to convert liquid methanol to methanol vapor as fuels for reducing the crossover of methanol through the proton exchange membrane, a two-dimensional, two-phase, non-isothermal model will be developed to elucidate the law of coupled mass transport of multi-components and electrochemical reactions. Regulation of multilevel distributions of the micro-pores structure and hydrophilic/hydrophobic properties of the electrode is to promote water recovery from cathode to anodic catalyst layer and inhibit the crossover of methanol, through which it's capable of keeping an appropriate concentration of methanol at anodic catalyst layer and effectively avoiding so called "water flooding" at cathode, aiming to realize a self-adaptable operation for the passive DMFC directly fed with neat methanol. Thereby, the advantages of DMFC with higher energy density than conventional batteries can be given full play that speed up the commercialization of DMFCs. The implement of this project can not only make a prediction of coupled complex multi-components, multi-phase, and multi-scale physical-chemical processes, but also lay the technical foundation for the optimization and regulation of new membrane electrode assembly and process intensification of mass transport and electrochemical reactions within electrodes.

面向便携式电子产品应用的全被动微小型直接甲醇燃料电池(DMFC)要有效缩小体积和提高比能量，迫切需要实现纯甲醇直接进样，这就需要解决甲醇的渗透蒸发速率、阳极催化层甲醇低的浓度、氧气传质和水的反扩散等自适性问题。本项目提出采用渗透蒸发方法以甲醇蒸气为燃料，构建全被动式DMFC内多级孔结构可调、多组分传质与电化学反应耦合的非等温模型，阐明电极多级孔结构对多组分传质与电极反应的影响规律，调控微孔层中纳微孔结构多级分布和表面亲憎水性，促进阴极产生的水向阳极催化层的反扩散，并抑制甲醇渗透，解决纯甲醇进样时全被动式DMFC阳极催化层中合适的甲醇浓度通过阴极水的返还实现等自适性问题和阴极"水淹"问题，充分发挥DMFC能量密度高的优势，推进其实用化进程。课题的实施不仅可为复杂的多组分多相多尺度物理化学过程耦合提供模型预测，还可为新型膜电极组件结构优化与调控、电极内传质与电化学反应的过程强化奠定技术基础。

面向便携式电子产品应用的全被动微小型直接甲醇燃料电池(DMFC)要有效缩小体积和提高比能量，迫切需要实现纯甲醇直接进样，这就需要解决甲醇的渗透蒸发速率、阳极催化层甲醇低的浓度和水的反扩散等自适性问题。本项目研究了DMFC中甲醇、水等在纳微多孔介质中的传质规律及其与电化学反应的耦合规律; 采用了渗透蒸发方法控制甲醇浓度，解决了高浓度甲醇或纯甲醇进样的全被动式DMFC阳极催化层中合适甲醇浓度的问题，抑制了甲醇渗透；通过调控电极纳微孔结构的表面性质，实现了多组分、电子和质子在DMFC内有效传递和阴极水的返还。确保了高浓度甲醇或纯甲醇进样的全被动式DMFC自适应性，推进了DMFC的商业化过程。