高浓度甲醇可控汽化传输对DMFC性能的影响

Effect of controlled feeding with high concentration methanol on DMFC's performance

被动式直接甲醇燃料电池(DMFC)要突出高比能的优势必须首先解决高浓度甲醇进料问题。近年来,基于渗透蒸发膜(PVF)的高浓度甲醇进料技术备受关注,但PVF的作用机制和甲醇蒸汽浓度与电池性能之间的关系尚不明确。通过建立的渗透蒸发装置-气相色谱-电池测试系统联用测试方法,实现了甲醇蒸汽浓度的在线监测和可控调节,研究了PVF活化处理时间、温度、液体甲醇浓度及载气流量对产生的甲醇蒸汽浓度的影响,研究了甲醇蒸汽流量、浓度、水汽含量与DMFC性能之间的关系。结果发现:当总流速50 mL/min、甲醇蒸汽浓度4.35×10^(-3)mol/L、水蒸气含量12.22%时,DMFC性能最佳,其最大功率密度可达32.8 mW/cm^2;在室温下40 mA/cm^2恒流放电128 h后电压仍维持在约310 mV,良好的稳定性为被动式DMFC的可靠运行奠定了基础。

To ensure the advantage of high energy density for passive direct methanol fuel cell (DMFC), the key issue is to feed DMFC directly with high concentration methanol. Recently, there is a major breakthrough by using pervaporation film (PVF) to control the methanol feeding. However, it is still unclear about the methanol transfer mechanismand the relationship between the concentration of vapor methanol and the DMFC performance. Herein, an online test systemwas designed, which included pervaporation device, gas chromatogramand fuel cell test system. The effects of PVF treatment time, temperature, methanol concentration and carrier flow rate on the corresponding gaseous methanol concentration were fully discussed. Afterwards, the relationship between the vapor fuel (such as the flow rate, methanol concentration and water content, etc.) and the DMFC performance was investigated quantitatively. The passive DMFC achieves a maximum power density of 31.3 mW/cm^2, when the total flow rate is 50 mL/min, the concentration of gaseous methanol is 4.35×10^-3 mol/L, and the water humidity is 12.22%. The DMFC also exhibits good stability even after discharging for 128 h at a current density of 40 mA/cm^2 at room temperature.