Fabrication and evaluation of nickel containing nanofibres for solid oxide fuel cell anodes using electrospinning technique

Sammanfattning: The energy demand of the world continues to increase, while world's resources are exploited over its capacity. One way of facing these demands is to extend the use of fuel cells. A fuel cell converts chemical energy into electrical energy through a series of chemical and electrochemical reactions. A solid oxide fuel cell (SOFC) is unique since it only contains solid materials and the cell has a fuel flexibility. Since the anode is the oxidising part of the SOFC, the anode material will greatly affect the overall cell performance and therefore the chosen material needs to hold various properties to ensure the efficiency of the fuel cell. A high porosity is required to facilitate fuel and gas transport through the anode and to maintain the porosity, the material needs to be chemically and thermally stable during the lifetime of the cell. The anode needs to provide enough active sites for the oxidising reaction to occur, good ion and electron conductivity is crucial as well as a high catalytic activity. These properties need to be combined with a cost efficient material and a simple production. This Master's thesis focus on a simple method for anode fabrication, by producing Ni-8YSZ nanofibres through electrospinning, a technique where fibres are formed by applying a high voltage over a syringe with anode solution and a collector plate. The nanofibres are evaluated by changing the electrospinning parameters and ratio between the materials. A closer distance between the needle of the syringe and the collector as well as a higher applied voltage increases the diameter of the fibres, whereas the nickel content seems to have no effect on the fibre structure. The XRD shows that the size of the crystals increases with higher sintering temperatures, which will generate vacancies in the fibre structure, enhancing the catalyst and improving the catalytic activity of the anode. The structure of the fibres produced with different polymers exhibit dissimilar appearance and an increased concentration results in an enlargement in diameter due to a higher viscosity of the solution. Due to its flexibility, the electrospinning method is suited for production of SOFC anodes. The fibres can easily be designed to fit specific needs by adjusting parameters, and a wide range of materials and setups can be used. However, the performance and the structure of the fibres need to be further investigated before a production method for SOFC anodes using electrospinning can be economically beneficial.