Performance Optimization Of Direct Methanol Fuel Cell Based On Gradient Membrane Electrode Assembly Design And Cloud Intelligent Monitoring System

In order to meet the global green and low-carbon development trend,developing new energy,realizing energy transformation,reducing fossil energy consumption and building a green and low-carbon energy system are important measures to achieve global carbon neutrality.As an efficient and green electrochemical power generation device,a direct methanol fuel cell(DMFC)can directly convert the chemical energy stored in methanol into electricity energy without going through the heat engine process and out of the restriction of Carnot cycle,which has the characteristics of high energy conversion efficiency,simple structure,wide fuel source and convenient transportation.It is considered to be a new alternative to lithium-ion batteries and has a wide application perspective as small mobile power and micro power.Currently,there are urgent problems to be solved in the large-scale commercialization of DMFC,such as slow kinetics of anode methanol oxidation reaction,uneven reaction distribution inside the cell,methanol crossover,optimization of operating conditions,etc.The membrane electrode assembly(MEA)is the core component of DMFC,and its structure and operating conditions are closely related to the performance and stability of the cell.Therefore,the construction of a high performance MEA and the control of mutually coordinated operating conditions become the key to optimize the performance of DMFC,which can ensure the proper transport of reactants and products,improve the reaction kinetic rate,expand the electrochemical active area,increase the catalyst active sites and reduce the methanol crossover.To this end,this thesis begins with the development of a new electrode structure,and then preliminary explores the use of a cloud-based intelligent monitoring system to track the maximum power point(MPP)of the fuel cell to achieve its optimal operating conditions.Firstly,a gradient catalyst loading electrode was prepared in the in-plane direction of the electrode.Different loadings of catalysts were distributed in different regions in the in-plane direction,with the gradient electrodes having lower catalyst loading nearthe inlet and higher near the outlet for the anode and cathode catalyst layer.The polarization curves,electrochemical impedance spectroscopy tests,and stability tests were performed on the gradient loading catalyst electrodes at different temperatures.It is shown that the gradient catalyst loading electrode in the in-plane direction improves the catalyst utilization and cell stability,and reduces the material transport resistance,which improves the discharge performance of the cell and slows down the degradation of performance.Secondly,a novel gradient catalyst layer anode structure was constructed in the through-plane direction.Covalent organic framework(COF)material with high specific surface area and high porosity were incorporated into the DMFC anode catalyst to construct gradient catalyst layer anode structure.The structure consists of a high catalyst loading outer catalyst layer incorporated with COF material near the microporous layer(MPL)and a conventional inner catalyst layer with low catalyst loading near the membrane side.Therefore,in the gradient catalyst layer structure,there existed a catalyst concentration gradient and porosity gradient,which achieved a methanol gradient oxidation process.The effect of the novel gradient catalyst layer anode structure on DMFC was investigated by polarization curve tests,electrochemical impedance spectroscopy and cyclic voltammetry tests.It is shown that the incorporation of the appropriate amount of COF material can expand the electrochemical active surface area of the outer catalyst layer,increase the catalyst reaction sites and improve the performance of the cell,and the presence of the inner catalyst layer reduces the methanol crossover,improves the utilization of methanol and improves the discharge performance of the high concentration methanol cell.Finally,a preliminary exploration of Cloud Intelligent Monitoring and Edge Computing based fuel cell system was set up for the development and optimization of cell performance.The system includes a fuel cell,an auxiliary equipment system,a fuel cell cloud operation database module,a cloud intelligent module,and a fuel cell monitoring data terminal module.These system modules can quickly and accurately track the MPP of the fuel cell through positive and negative feedback regulation,and quickly send the MPP signal back to the fuel cell auxiliary equipment system so that it can quickly regulate the operating parameters of the fuel cell to achieve the best operating conditions.