泡沫钛集流-扩散一体化封装结构的微型直接甲醇燃料电池研究

The performance of the micro direct methanol fuel cell (DMFC) with tranditional structure is limited because of the high mass transfer resistance and contact resistance between the current collector and diffusion layer and failure of diffusion layer made of carbon fibre. In order to reduce the resistance and so as to improve the output performance and working life of DMFC, a novel micro DMFC with integrated assembly structure of current collection and diffusion based on titanium foam is proposed on the basis of our preliminary work. The distribution of normal stress on the active area of membrane electrode assembly (MEA) under assembly load is investigated first. The evolution of the normal stress under creep load of superpolymer gasket is also studied. Then, the two-phase seepage of methanol - carbon dioxide in the anode and that of oxygen - liquid water in the cathode are researched to investigate the effect of the electrode structure on the mass transfer efficiency of the reactant and product. An overall internal resistance model of DMFC is built to investigate the influence of the integrated electrode on the internal ohmic resistance. Subsequently, the Kriging surrogate model is used to optimize the parameters of the electrode structure and fuel cell. Finally, a micro DMFC with integrated assembly structure of current collection and diffusion based on titanium foam is manufactured and tested according to the above results.

在项目组前期工作基础上，针对传统结构微型直接甲醇燃料电池传质阻抗与集流板-扩散层界面接触电阻过高及碳纤维类扩散层易失效等对电池性能的限制，提出并验证泡沫钛集流-扩散一体化封装结构的微型直接甲醇燃料电池，通过减少反应物输运和电子传导环节，降低燃料电池内传质阻抗和内电阻，提高电池输出性能和使用寿命。本项目将首先研究集流-扩散一体化结构燃料电池膜电极活性区在封装载荷下的法向应力分布、及法向应力在高聚物密封垫圈蠕变特性作用下的演化规律；然后研究电极结构中阳极甲醇水溶液-二氧化碳及阴极氧气-液态水双相渗流机理和全电池内电阻模型，探明电极结构参数对反应物与生成物传质效率和电池欧姆内阻的影响模式，并基于Kriging代理模型对燃料电池电极结构封装参数进行优化；最后基于上述结果制备出泡沫钛集流-扩散一体化封装结构的微型直接甲醇燃料电池，对其特性进行验证。

针对传统结构微型甲醇燃料电池传质阻抗与界面接触电阻过高等对电池性能的限制，本项目提出并验证了泡沫钛集流扩散一体化电极这一新结构的微型直接甲醇燃料电池，其峰值功率密度比传统采用碳纸的甲醇燃料电池高12%，在此基础上采用三维石墨烯这一新结构材料作为燃料电池的一体化阳极，其峰值功率密度更比用碳纸的燃料电池高达24%。项目通过研究集流板特征尺寸对电池输出性能的影响，得到了电极流场较佳的特征尺寸；在此基础上设计了集流扩散一体化电池并封装为纽扣式这一新结构，电池厚度仅为3mm；通过对电极内物料输运和电池内电阻模型仿真获得了电极内物料传输规律和阻抗特性；最后基于高斯过程代理模型对前述测得的实验数据进行拟合，获得了预测燃料电池性能的经验公式参数。研究成果对微型燃料电池技术发展具有重要学术参考及实际应用价值。