直接甲酸钠/铁氰化钾微流体燃料电池性能研究

Performance Research of the Direct Sodium Formate/Potassium Ferricyanide Microfluidic Fuel Cell

微流体燃料电池(MFC)利用两股流体在微通道内呈平行层流的特性,无需传统燃料电池中的质子交换膜,自动将燃料与氧化剂隔开.本工作构建了阴阳极均为碱性介质且阴极无催化剂即可反应的直接甲酸钠/铁氰化钾MFC,考察了反应物流速、氧化剂浓度、燃料浓度对该电池产电性能的影响.实验结果表明,在反应物流速为200μL·min^(−1),铁氰化钾氧化剂浓度为1 mol·L^(−1),甲酸钠燃料浓度为1.5 mol·L^(−1)时,该微流体燃料电池性能达到最优,其最高功率密度为123.93 mW·cm^(−2),极限电流密度为220.93 mA·cm^(−2).为了获得该电池的稳定运行性能,对电池进行了恒电压放电实验.结果表明,该电池在2.25 h内可以持续较稳定地放电.此外,对该电池在开路状态下进行了电化学阻抗谱测试,获得该电池内阻为18.4Ω.

Microfluidic fuel cells(MFCs)exploit the two fluids to form the parallel flow in the microchannel,naturally sep-arating the fuel and oxidant,and eliminate the proton exchange membranes in the traditional fuel cells.These membrane-free fuel cells not only have outstanding advantages such as wide selections of the reactants and simple configurations,but also tackle issues related to the membranes including membrane deformation and degradation and so on.To gain the all-alkaline MFC in the anode and cathode,we constructed the direct sodium formate/potassium ferricyanide microfluidic fuel cell with the catalyst-free cathode.Sodium formate was used as the fuel,potassium ferricyanide was adopted as the oxidant,and the electrolytes in the anode and cathode were both sodium hydroxide solutions.We investigated the effects of the flow rates,oxidant concentrations,fuel concentrations on the performance of the MFC.The performance of the MFC was gained by the linear sweep voltammetry from the open circuit voltage to 0.0 V with the sweep rate of 10 mV·s^(−1).Experimental results showed that the performance of the MFC achieved the optimum,with the peak power density of 123.93 mW·cm^(−2) and the limiting current density of 220.93 mA·cm^(−2) under the conditions of 200μL·min^(−1) flow rate,1 mol·L^(−1) potassium ferricyanide and 1.5 mol·L^(−1) sodium formate.The discharge test and electrochemical impedance spectroscopy(EIS)measurement were carried out under the conditions of the optimal cell performance.To evaluate the stability of this MFC,the discharge perfor-mance of the MFC under the constant voltage(0.78 V)was measured.The result showed that the MFC could stably discharge for about 2.25 h.Moreover,the internal resistance of the fuel cell was gained by the EIS measurement in the frequency range from 1 MHz to 50 mHz with the amplitude of 10 mV.After fitting the EIS result,the internal resistance of the MFC under the open-circuit voltage was 18.4Ω.