Christoph Roitzheim

 

Electrochemical characterization of the non-aqueous Si–air batteries under different operating conditions

Figure 1: Schematic presentation of a Si–air cell using a non-aqueous electrolyte Copyright: C. Roitzheim Figure 1: Schematic presentation of a Si–air cell using a non-aqueous electrolyte

Development of new energy storage systems for portable electronic devices and electro mobility are the focus of research due to an increased demand on resource efficient energy materials. Metal–air batteries, in this respect, are potentially good candidates due to their high theoretical specific energies and availability of anode materials. Among the others, silicon was considered as a promising anode for primary Si–air batteries for possessing a specific energy of 8470 Wh/kg.[1] Additionally, silicon is the second most abundant element in earth’s crust and there are no safety issues. Also, the reaction products can be easily handled and are environmentally friendly.[2, 3, 4]

One of the main issues of Si–air batteries is the corrosion of silicon when aqueous alkaline electrolyte is employed.[5] To overcome this problem and enhance the discharge efficiency, a non-aqueous room temperature ionic liquid (RTIL) e.g. 1-ethyl-3-methyl-imidazolium fluorohydrogenate (EMIm(HF)2.3F) can be utilized as electrolyte which promises better battery performances.[2]

This master thesis focuses on investigations of Si–air full- and half-cells employing EMIm(HF)2.3F as electrolyte. The aim is to find out the optimum operating conditions for Si–air full-cells and to assess the impact of each electrode on the discharge profiles. The electrochemical characterization will be performed by galvanostatic discharge and potentiodynamic polarization experiments. The surface characterization of the silicon anode will be carried out by laser scanning microscopy (LSM). Consequently, it will be possible to propose a mechanism for the discharge limitation.

[1] G. Cohn, A. Altberg, D. D. Macdonald, Y. Ein-Eli, Electrochimica Acta 2011, 58, 161-164.

[2] G. Cohn, Y. Ein-Eli, Journal of Power Sources 2010, 195, 4963-4970.

[3] G. Cohn, D. Starosvetsky, R. Hagiwara, D. D. Macdonald, Y. Ein-Eli, Electrochemistry Communications 2009, 11, 1916-1918.

[4] G. Cohn, D. D. Macdonald, Y. Ein-Eli, ChemSusChem 2011, 4, 1124-1129.

[5] Y. E. Durmus, Ö. Aslanbas, S. Kayser, H. Tempel, F. Hausen, L. de Haart, J. Granwehr, Y. Ein-Eli, R.-A. Eichel, H. Kungl, Electrochimica Acta 2017, 225, 215-224.