37results about How to "Reduced mass transfer polarization" patented technology

The invention discloses a carbon nanofiber, a diffusion layer, a membrane electrode, a fuel cell, a preparation method and an application thereof. The preparation method of the carbon nanofiber comprises the following steps: S1, drying the spinning solution after electrospinning; wherein, the spinning solution includes a polymer and a solvent, and the mass of the polymer in the spinning solution Fraction is 6~10%, described polymer comprises nitrogen-containing polymer, and described nitrogen-containing polymer is one or more in polyacrylonitrile, polyvinylpyrrolidone, polyethylimide and polyaniline; The temperature of the carbonization is 60-80°C; S2, high-temperature carbonization, the temperature of the carbonization is 750-950°C. The diffusion layer prepared by the carbon nanofiber has large pore volume, small material diffusion free path and strong material transmission capacity.

The invention relates to a platinum-based catalyst having high catalytic activity and high durability and adopting porous carbon nano fibers as a carrier and a preparation method of the platinum-based catalyst, and particularly relates to a method of improving the catalytic activity and durability of a catalyst adopting a loose three-dimensional netted through structure composed of the porous carbon nano fibers as a carrier to load nano platinum particles and an application of the catalyst in a proton exchanging membrane fuel cell. According to the platinum-based catalyst adopting the porous carbon nano fibers as the carrier, the porous carbon nano fibers which are used as the carrier form a loose three-dimensional netted through structure, and metal platinum is loaded on the porous carbon nano fibers; the catalytic activity of the platinum-based catalyst adopting the porous carbon nano fibers as the carrier is as follows: the peak potential is 100mA ahead of that of a platinum-carbon catalyst, and the utilization rate of platinum reaches 80 percent; the durability of the platinum-based catalyst adopting the porous carbon nano fibers as the carrier is as follows: the ECSA retention rate after the fuel cell is circulated for 1000 times can reach 50 percent.

The invention discloses a membrane electrode with ultra-low oxygen mass transfer resistance; the membrane electrode includes an anode catalyst layer, a proton exchange membrane and a cathode catalyst layer; the catalyst in the cathode catalyst layer is modified with negative charges, and the cathode catalyst layer Also doped with negatively charged carbon supports. The invention modifies the carbon carrier of the cathode catalytic layer in the membrane electrode with negative charges, so as to optimize the distribution of the ionomer and achieve the purpose of reducing the oxygen mass transfer resistance in the cathode catalytic layer. In addition, the local oxygen concentration near the active sites is enhanced by doping an appropriate amount of negatively charged carbon supports. In a word, by modifying the negative charge and doping the negative charge carbon carrier, the local mass transfer resistance in the electrode can be optimized to improve the performance of the battery.

The invention relates to a carbon dioxide electroreduction cathode and a preparation method thereof. The cathode structure is based on carbon paper, carbon felt or carbon cloth, and two catalyst layers with different pore diameters are sequentially attached to one side of the substrate. The substrate, the nano-carbon layer doped with large-aperture heteroatoms, the metal with small-aperture and the nano-carbon layer doped with heteroatoms are in sequence. Catalyst layer with large pore size is beneficial for CO 2 Transmission and product transmission, reduce mass transfer resistance; heteroatom-doped nano-carbon layer with small pore size is beneficial to increase catalyst reactivity specific surface area, improve reactivity; apply this structure to ERC, greatly expand the three-phase The area of ​​the electrochemical reaction interface improves the utilization rate of the catalyst, which is beneficial to reduce the mass transfer polarization of the electrolytic cell, and utilizes its interaction with CO 2 Adsorptivity or chemical bond formation between electroreduction products increases the selectivity and conversion rate of specified reduction products, and achieves the goal of high selectivity for reduction products.

The invention relates to an organic liquid flow battery. The anode electrolyte is a bromide quaternary ammonium salt solution, the anode electrolyte is a bisanhydride solution, and the above solutions all use organic solvents. Among them, the one-electron redox reaction of quaternary ammonium bromide occurs at the positive electrode, and the two-electron redox reaction of bisanhydrides occurs at the negative electrode. Since the positive and negative electrodes of the battery use organic redox couples, no metal elements participate in the electrochemical reaction, the electrolyte is an organic system, and the redox couples can be electrochemically modified to adjust the electrode potential, so the battery has a wide voltage window, It has the characteristics of high energy density, simple assembly process, and low cost.

The invention describes an ordered catalytic layer of a membrane electrode, including the construction of an ordered structure, the formation of a metal / alloy that can absorb hydrogen / CO, and the in-situ reduction preparation of a thin-layer catalyst. Some metals or alloys have adsorbed H 2 and the role of CO, the adsorbed H 2 and CO have reducing properties for the preparation of thin-layer catalysts, and the loading of the catalyst is determined by the adsorbed H 2 / CO volume control. The membrane electrode structure prepared by the invention has the advantages of low catalyst loading, high catalyst utilization rate, excellent mass transfer, high stability and the like, while avoiding the use of ion polymers in the catalytic layer as proton conductors.

The invention discloses a flow field plate and an iron-chromium flow battery, comprising an electrolyte solution inlet, an electrolyte solution outlet, an inflow-limiting channel, an outflow-limiting channel, a divided inflow channel, and a divided outflow channel; the electrolyte solution outlet and The outflow-limiting channel is connected, the electrolyte solution inlet is connected to the inflow-limiting channel, the outflow-limiting channel diverges at least two outflow channels, the inflow-limiting channel diverges at least two inflow channels, the outflow channel and the The end of the inflow channel is a blind end; the outflow channel and the inflow channel form a serpentine cross structure or a parallel cross structure. The present invention improves fluid resistance distribution, reduces fluid resistance, and reduces internal bypass current loss, so that internal bypass current loss is controlled within 1%, thereby improving the mass transfer effect of the electrolyte solution in the carbon paper electrode, thus possibly reducing the electrode The mass transfer polarization on .

The invention relates to a carbon-sulfur composite for positive electrodes of lithium-sulfur batteries and its preparation and application. The composite includes carbon materials and elemental sulfur, wherein the carbon materials have a gradient ordered tertiary pore structure, and the pore diameter of the tertiary channels is The distribution range is that micropores less than 2nm are used as primary pores, small mesopores around 3-10nm are used as secondary pores, and large mesopores of 10-30nm are used as tertiary pores. The secondary pores are located on the pore wall of the tertiary pores. The primary pores are located on the pore wall of the secondary pores; the elemental sulfur is filled in the pores of the carbon material, and the elemental sulfur accounts for 10-80wt% of the total amount of the compound. The carbon-sulfur composite is used in lithium-sulfur secondary batteries, exhibits high sulfur utilization rate and good cycle stability, and has the advantages of simple preparation process, good repeatability, low cost and microscopic controllability.

The invention relates to a fuel cell technology and aims to provide a direct methanol fuel cell with homogeneous assisted catalysis and porous carbon-supported platinum catalysis. According to preparation of methanol fuel in the battery, 1 liter of sulfuric acid with a mass concentration of 5 to 10 wt% is taken and heated to 50 to 70 DEG C; 0.1 to 1 mol of V2O5 is added, reacting under stirring for 5 h is carried out, and after filtering, a (VO2)2SO4 sulfuric acid solution is obtained; after cooling to room temperature, 1 to 4 liters of methanol aqueous solution with a mass concentration of 50to 60 wt% are added, (VO2)2SO4 changes to (VO)SO4 through uniform mixing, and modified methanol fuel containing a cocatalyst (VO)SO4 is obtained. Oxidation and carbon monoxide poisoning on the surface of a platinum catalyst in the electrochemical oxidation process of methanol are avoided through the assisted catalytic effect of VO<2+> ions; and the performance of direct methanol fuel cell is improved through the synergy of the high activity of carbon-loaded platinum and the assisted catalytic effect of liquid phase VO<2+> ions. (VO)SO4 can be recycled, the cost can be effectively reduced, andthe application and the popularization of methanol fuel cells are facilitated.

The invention discloses an electrode for electrochemical reduction of carbon dioxide and its preparation and application. It includes a base layer and a Sn catalyst nano-layer attached to the base layer. cm-2, the Sn in the electrode is composed of one or more of 1nm-500nm nanowires, nanorods, and nanofibers. The invention significantly increases the specific surface area and active area of ​​the electrode by in-situ growing Sn nanorods with abundant edge active sites on the substrate, and improves the Faradaic efficiency of the electrode for electrochemically reducing carbon dioxide to formic acid.

The invention relates to an electrode for electrochemical reduction of carbon dioxide to prepare hydrocarbons and its preparation and application. The electrode consists of a base layer, a thin film layer composed of porous copper nanoparticles and an ordered layer; the outer surface of the flaky base layer is attached with A film layer composed of porous nanoparticles, with a copper whisker layer attached to the surface of the film layer composed of porous copper nanoparticles; the thickness of the base layer is 100-500 μm; the thickness of the porous nano-film layer is 100-200 μm; the thickness of the copper whisker layer is about 100nm ~ 500μm. The electrode with this structure effectively increases the reactive area, improves the mass transfer of reactants, and is beneficial to reduce the reaction polarization resistance and mass transfer polarization resistance, thereby improving the conversion efficiency of CO2; Regulation can improve the selectivity of ERC reaction products; this structure can improve the stability of Cu metal, thereby increasing the lifetime of ERC reaction catalysts.

The invention discloses a porous conductive additive and a preparation method thereof. The porous conductive additive consists of graphene-based particles, having flaky particle shapes, the size distribution of 0.01-5 microns in a planar direction, the size distribution of 0.1-50 nanometers in a thickness direction, and through holes with the diameters of 1-1000 nanometers inside, with the porosity of 20-70%. The preparation method comprises the following steps of: dispersing a graphene-based material into a solvent to obtain a dispersion solution, adding a pore forming agent in a mass ratio of the pore forming agent to the graphene-based material of 0.1-1000, and performing ultrasonic treatment or mixing to obtain a uniform mixed solution; heating the mixed solution, removing the solvent, drying an obtained solid, and heating the solid in an oxygen-free protective atmosphere to obtain the porous conductive additive. The porous conductive additive has very high conductivity efficiency and can optimize a pore structure in an electrode and reduce ion conducting paths.