Alkaline Pre-treatment of the Air Electrode in a Silicon-air Battery

Master thesis (2020)

Authors

J.J.C. Prins Electrical Engineering, Mathematics and Computer Science

Contributors

R.A.C.M.M. van Swaaij Photovoltaic Materials and Devices (mentor)
O Isabella Photovoltaic Materials and Devices (graduation committee member)
M. Wagemaker RST/Storage of Electrochemical Energy (graduation committee member)
Faculty
Electrical Engineering, Mathematics and Computer Science, Electrical Engineering, Mathematics and Computer Science
Copyright: © 2020 Jasper Prins
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Published Date

27-08-2020

Language

English

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Faculty

Electrical Engineering, Mathematics and Computer Science

Abstract

The objective of this research is to evaluate the effect the air electrode has on the discharge performance of an alkaline silicon-air battery. Experiments are conducted to show that alkaline pre-treatment of the air electrode of up to eight hours leads to an increase in both discharge time and discharge potential of the battery. Furthermore, it is shown that alkaline pre-treatments of sixteen and 24 hours also increase the discharge time and discharge potential of the battery with respect to no pre-treatment. However, the increase in discharge time and discharge potential for these pre-treatments is much smaller than for pre-treatments between three and eight hours. A pre-treatment of 110.75 hours results in a discharge time and discharge potential similar to that of no pre-treatment. In the experiments it is also shown that pre-treating the air electrode with water only, instead of an alkaline solution, has no effect. Finally, the experiments show that discharging the battery at a current higher than 150 μA is not supported. A computer model is then used to evaluate the impact of some qualities of the air electrode on the discharge performance of the silicon-air battery. It is found that the electrical conductivity of the air electrode has very little impact, with a very large increase in electrical conductivity resulting in only a very small increase in discharge potential. The micro-pore surface area in the air electrode has slightly more influence on the discharge performance. Still, a relatively large increase in this parameter only results in an increase of approximately 0.2 V in discharge potential. Both of these parameters are found to have no effect on the discharge time of the battery. To explain the significant increase in both discharge potential and discharge time after alkaline pre-treatment found in the experiments two possible reasons are suggested. Firstly, the adsorption of OH- ions contributing to the oxygen reduction reaction activity of the air electrode material. Secondly, other atmospheric gases besides oxygen might be suffocating the micro-pores of the air electrode. Increased micro-pore area as a result of alkaline pre-treatment could explain the extended time before the air electrode is fully suffocated.