Rational Construction Of Transfer Channels Of Novel Membrane Materials And Their Structural Stability

Proton exchange membrane fuel cells have become an important direction of research in the field of new energy because of their fast response,low energy consumption and high efficiency,with the aim of solving the long-standing dependence of human society on fossil fuels and fundamentally solving the severe test of energy and environmental problems.One of the central components of the PEMFC is the membrane electrode,which consists of the catalyst,gas diffusion layer,and the PEM.The proton exchange membrane plays a role in preventing gas permeation and conducting protons in the proton exchange membrane fuel cell,and ultimately affects the comprehensive performance of the proton exchange membrane fuel cell.The development of high-performance proton exchange membranes with high proton conduction and low hydrogen permeation is a key part of the industrial application of proton exchange membrane fuel cells.Therefore,the research process of proton exchange membrane must start from its molecular structure and focus on the key mechanism of its performance at molecular size as well as micro and nano size to lay the foundation for the design and performance exploration of membrane materials.In this study,in order to solve the problems of high cost and poor high-temperature tolerance of commercial Nafion membrane materials,low-cost and better performance acid-base composite membrane materials with non-fluorinated hydrocarbon backbone were prepared.In this paper,the blended membrane materials were prepared by blending norbornene block copolymers with sulfonated polyimide,sulfonated polyether ether ketone and sulfonated polyphenylene ether,respectively,and the physicochemical properties of various blended membrane materials were tested.By combining the proton transport theory,the experimental results were analyzed in depth,and the ion channels and hydrogen bonding networks constructed by the interaction between the acid-base functional groups in the two polymers were investigated for the membrane materials The effects of ion channels and hydrogen bonding networks constructed by the interaction between acid-base functional groups in the two polymers on the physicochemical properties of the membrane materials and on the performance of the corresponding H₂/O₂ fuel cells were investigated.Firstly,the acidic polymer of sulfonated polyimide（SPI）was added to the PNBN as the matrix,and the hydrogen bonding network and ion transport channels were constructed by the interaction between the acid-base functional groups in the acid-base polymer to ensure a certain ionic conductivity and single-cell performance on the basis of low ion exchange capacity,and the effect of the content of sulfonated polyimide polymer on the physical and chemical properties of the membrane was investigated by testing.The effect of the content of polyimide polymer on the physicochemical properties of the membrane materials was investigated.The test results showed that the ion exchange capacity（IEC）of PNBN/SPI membrane was 0.253mmo1 g^-1 at 15%SPI addition,and the proton conductivity was also maximized,reaching22.133 m S cm^-1 at 80°C,which was better than the same group of membrane materials,and the power density of PNBN/SPI-15%could reach 104.3 m W cm^-2.The results show that the interaction of PNBN,a norbornene-based block copolymer,with sulfonated polymers can enhance the electrochemical properties of the membrane materials.In order to achieve enhanced proton conductivity of the composite membrane material and to obtain good cell performance,based on the acid-base composite membrane with a norbornene-based block copolymer matrix,sulfonated polyether ether ketone was used as the polymer matrix,to which norbornene-based block copolymers were added,and compared with the norbornene-based block-based co-blended membrane,the SPEEK/PNBN-x%（x=0,2.5,5,10,15）co-blended membrane The electrochemical properties of the blended membrane materials were significantly improved,and the test results revealed that the mechanical properties of the membrane materials were improved by up to 22%when PNBN was added to the SPEEK matrix at 15%,in addition to the improved dimensional stability of the membrane materials.The interaction between the added PNBN and the amphiphilic groups of SPEEK also has an effect on the electrical conductivity of the membrane,and when the added PNBN is 5%,the proton conductivity（80°C）of SPEEK/PNBN-5%is enhanced by about 11%compared to the SPEEK membrane,and its power density can reach 303.3 m W cm^-2.The experimental results show that PNBN blended with SPEEK can effectively enhance the fuel cell performance.Co-blended acid-base membranes were prepared using sulfonated polyphenylene ether（SPPO）as a substrate and PNBN as the substrate.Compared with the PNBN-based acid-base co-blended membranes,the SPPO/PNBN-x%（x=0,2.5,5,10,15）membranes exhibited high electrochemical performance,and the highest ion exchange capacity and ionic conductivity could reach 1.7 mmol g^-1 and 63 m S cm^-1,and SPPO/PNBN-x%exhibited enhanced oxidative stability compared to SPEEK/PNBN-x%（x=0,2.5,5,10,15）,and the single-cell power density of SPPO/PNBN-5%fuel cell could reach 346.7 m W cm^-2 at 80°C and 100%RH.The results show that the co-hybrid membrane prepared in this experiment has broad application prospects in fuel cells and new energy equipment.