Study Of Influencing Factors Of Cell Voltage In Filter-press Type Electrolyzer

With consumption of the fossil fuel, human are facing energy crisis and environmental crisis. Hydrogen as the secondary energy has attracted much attention because of its high efficiency and clean. One of the problems is high-energy consumption for alkaline water electrolysis. Hence, reduction of the energy consumption is the key to the technology, which could play important role in large-scale hydrogen production. As a simple, mature and friendly technology, alkaline water electrolysis has many advantages in hydrogen production. Filter-press type eletcrolyzers are widely used in alkaline water electrolysis, due to easy operation, simple structure, etc. This thesis studied effect of polarization time on polarization and the influcing factors of cell voltage in filter-press type electrolyzers from point of electrodes,diaphragm and cell structure.It was found that the anodic polarization curve tended to be steady when polarization time was70min. The cathodic polarization time was90min. The effect of electrodes on cell voltage was studied. The porous structure and mesh structure of nickel reduced the overpotential by increasing the specific surface area. Nickel foam alloy electrodes showed low overpotential compared to thermally sprayed Ni-Al alloy. Cell voltage increased as the pore number increased when the electrodes were nickel foams; Cell voltage decreased as the pore number decreased for nickel mesh electrodes. Ni-Co and Ni-Mo electrodes were prepared on different nickel foams by electro-deposition. EDS elemental analysis results showed that content of cobalt of Ni-Co electrodes have a great effect on cell voltage. The cell voltage decreased as the system temperature increased. High temperature raised the surface reaction on alloy electrodes.Cell voltage of sulfonated pps diaphragm, asbestos diaphragm and modified polyolefin membrane were compared. It was found sulfonated pps diaphragms had lowest cell voltage in these three diaphragms. Compared with asbestos diaphragm, pps diaphragms have lower interface resistance and higher porosity. The cell voltage of sulfonated pps diaphragms with different thickness were compared. Cell voltage decreased as thickness reduced.The effects of cell structure on cell voltage were studied. Cell voltage decreased with increasing flow of electrolyte. The cell voltage was lower when the front side of outer frame was used as the cathode chamber. The cell voltage decreased when aperture of the inner frame increased for nickel foam electrodes. The cell voltage decreased when aperture of the inner frame increased for nickel mesh electrodes. The results showed that in zero gap system, cell structure had an effect on cell voltage. The cell voltage was lower as the mastoid plates were connectors. The mastoid plates could be replaced by nickel foam and nickel mesh electrodes to reduce production cost. The contact resistance reduced by increasing the cathode area and welding electrodes. Cell voltage were decreased by30mV and24mV respectively when cathode area increased in the current density of3000A/m2,4000A/m2. Cell voltages of thermal spraying Ni-Al alloy and nickel mesh welding electrodes was74mV lower and79mV than that of unwelding electrodes in the current density of4000A/m2.