超声强化的高性能直接甲醇燃料电池关键技术及设计理论研究

Direct methanol fuel cell(DMFC) is one of cells which has the highest energy density,while the problem of catalyst poisoning delays the application and popularization of DMFC which is drawing a lot of attentions from academia and industry. At the present stage, Multimetallic electrocatalyst is a most common solution to release the catalyst poisoning which can not be promoted for its high cost and low efficency. In the present research, a novelty method is proposed to release the catalyst poisoning of DMFC using ultrasonic vibration.Minirated ultrasonic transducer is designed in the flow channels of DMFC to realized this method.Advantages of the method include:it can not only release the catalyst poisoning but also improve the steady state performance of DMFC. Moreover,for it can achieve a high anodic methanol oxidation velocity with few catatlyst using ultrasonic,this methdod can reduce the usage of catalyst to reduce the cost of DMFC.In the present research,experiments will be employed to discover the mechanism of performance improvement of DMFC using ultrasonic. Our main attentions are foucsed on the following problems:1)the design theory of a low energy cost and high activity ultrasonic cavitation field;2) flow phenomen of methanol and control method of the motion of cavitation bubbles in the flow channel. Finally, a new design theory will be formed to design a ultrasonic enhanced high performance DMFC,which provides the theoriecal and experimental proofs for applying ultrasonic to improve the performance of DMFC.

直接甲醇燃料电池是能量密度最高的电池之一，其阳极催化剂中毒的问题制约着它的应用与推广，这引起学术界和工业界的广泛关注，多元合金催化是目前最主要的解决办法之一，但因成本高、效率低而得不到推广。本项目提出一种应用超声振动来缓解催化剂中毒的新方法，拟将结构小型化后的超声波换能器与燃料电池阳极流场板中的燃料供给通道进行一体化设计来实现。该方法的优点在于它既可缓解催化剂中毒又能提高燃料电池的稳态性能，而且超声波的引入可使阳极甲醇氧化反应在少量催化剂的情况下快速进行，这样可减少催化剂的使用量从而降低燃料电池成本。本项目将通过实验揭示超声波在提高直接甲醇燃料电池性能中的作用机理，重点研究低能耗高活性空化场的设计理论、燃料供给通道中甲醇燃料的运动规律和空化气泡运动轨迹的控制方法等问题，建立一套基于超声强化的高性能直接甲醇燃料电池的设计理论与实现方法，为应用超声波提高燃料电池性能提供理论依据和实验基础。

直接甲醇燃料电池因能量密度高、工作温度低等优点被期望用作各种便携式设备的电源，而阳极催化剂中毒是制约其应用和推广的主要原因之一。多元合金催化剂虽然能在一定程度上缓解该问题，但同时增加了电池的成本。在这样的背景下，本项目提出了一种利用超声作用缓解催化剂中毒的新方法，并通过在阳极流场板中引入小型的超声换能器实现了一体化设计。项目还通过实验研究了甲醇浓度、超声频率、超声功率等参数对该电池性能的影响，揭示了超声作用在其中的作用机理。实验结果表明当供给的甲醇浓度为2M、超声频率为30kHz（超声换能器的共振频率）、超声功率为4W时电池的性能达到最佳，在该条件下直接甲醇燃料电池的极限电流密度和最大输出功率分别提高了40.54%和30.73%。此外，本项目还拓展研究了利用超声雾化作用来供给燃料从而缓解甲醇渗透问题，并取得了一定的研究成果。该研究成果为提高直接甲醇燃料电池的性能提供了一种新方法，为超声波在直接甲醇燃料电池中的应用提供了实验指导和理论依据。