离子树脂状态对PEMFC催化层局域传质阻力的作用机理研究

The commercial application of proton exchange membrane fuel cell (PEMFC) has been postponed due to its high cost. Although the reduction of Pt loading brings down the cost of fuel cell system, a low Pt loading is always accompanied by the increase of oxygen local transport resistance in catalyst layer, which results in serious concentration polarization. As ionomer is a significant factor for local transport resistance, the effect of ionomer on the local transport resistance is essential to illuminate the mechanism of local transport process and relieve concentration polarization. However, the bulk transport resistance in catalyst layer interfere the quantitation of local transport resistance, which prevent a deeper insight into the relationship between interface and transport resistance. To improve the comprehension of local transport process, this project will study the effect of ionomer on local transport resistance based on in-situ quantitation. Firstly, we will design the methodology of ionomer adjustment and investigate the essential properties. Secondly, we will quantitate transport resistances in catalyst layer by the “dual-layer cathode” design and illuminate the mechanism of transport process. At last, the optimized MEAs with low Pt loading and efficient transport process will be designed based on the result of mechanism study.

成本问题是限制车用质子交换膜燃料电池商业化应用的主要瓶颈。降低电池的铂载量可以大幅降低成本，但是却会提高催化层内氧气的局域传质阻力，进而造成严重的传质极化损失。离子树脂就是影响催化层局域传质阻力的一个关键因素，因此研究其对局域传质阻力的作用机理对降低低铂电池的催化层传质阻力、缓解传质极化具有重要意义。但是由于催化层内体相传质阻力的存在，很难对局域传质阻力进行量化研究，这就制约了人们对离子树脂-传质阻力关系的进一步认知。针对这一问题，本项目拟从在线量化的基础上开展离子树脂状态对局域传质阻力作用机理的研究。首先建立离子树脂状态的调节策略，研究相关特征；其次依托“双层阴极结构”膜电极在线测量传质阻力值，揭示离子树脂状态与局域传质阻力的量化关系，阐明相关机理；最终依据机理调节离子树脂，设计具有高效传质效率的低铂载量膜电极。

离子树脂就是影响催化层传质阻力的一个关键因素，因此研究其对传质阻力的作用机理对降低低铂电池的催化层传质阻力、缓解传质极化具有重要意义。本项目通过修饰碳载体、调整分散体系表面能，使离子树脂在催化层中体现出了不同的分布状态，并考察了对应状态下燃料电池氧气传质阻力及电池性能，揭示了离子树脂对传质阻力的影响机理。基于对相关机理的应用，设计出了多款具有较低氧气传质阻力的膜电极，并已开始启动产业化进程。

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