Development of Magnesium EBPVD Magnesium Anode Material for use in a 'Green' Battery

Open Access
Author:
Gresh, Robert William
Area of Honors:
Engineering Science
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • Mark William Horn, Thesis Supervisor
  • Barbara Shaw, Honors Advisor
  • Judith A Todd, Faculty Reader
Keywords:
  • battery
  • electron beam
  • physical vapor deposition
  • magnesium
  • thin films
  • corrosion
  • electrochemical
  • structure
  • anode
Abstract:
The development of a “green” battery with a magnesium anode and polymer cathode could help to meet current energy needs while decreasing the negative environmental impact that is caused by disposable batteries. There are many advantages to developing magnesium for use as an anode material. Magnesium is a fairly inexpensive and environmentally friendly material when compared to competing anode materials such as aluminum, zinc and lithium. The specific compositions of magnesium alloys can be varied and the structure of magnesium films can be controlled through the method of Electron Beam Physical Vapor Deposition (EBPVD). This thesis discusses the electrochemical and structural characteristics of MgAlZn alloy thin films deposited via EBPVD. Magnesium alloy thin films targeted to have 6% Al and 1% Zn were deposited with varying thicknesses of 3.01 µm, 5.89 µm, 7.17 µm and 7.79 µm were analyzed and compared. Scanning electron microscopy was used to image the surface and cross-sectional views of the films. The SEM analysis provided a measurement of thickness from the cross-sectional view. SEM analysis on the surface of each film indicated that thicker films have a more defined surface structure and, therefore, more surface area. AZ61 thin films were tested using polarization resistance and electrochemical impedance spectroscopy in order to evaluate their electrochemical characteristics. The corrosion rates determined by these tests were compared and it was found that corrosion rate increases as a function of film thickness, which is likely caused by the increase in surface area. ICP analysis showed that the thin films contained very little Al and Zn in their compositions. Further investigation is required to confirm the conclusions of this thesis. Advanced imaging methods such as FESEM and XRD can be used to gain more information on the surface structure of the films. Several methods of fabricating thin films can be used to increase percentage of Al and Zn in the composition of the films.