Numerical Modelling and Experiments of Silicon Electrodeposition by Solid Oxide Membrane - Molten Salt Electrolysis

Moudgal, Aditya

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Numerical Modelling and Experiments of Silicon Electrodeposition by Solid Oxide Membrane - Molten Salt Electrolysis

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The demand for cost-effective and sustainable solar energy has spurred the need for cheaper, cleaner solar panels with low carbon footprints. One critical component of solar panels is silicon, whose energy intensive, multistep manufacturing process has been an obstacle in achieving low stable prices. This project explores mathematical modelling and experimentation methods of achieving high purity solar grade silicon through solid oxide membrane (SOM) – molten salt electrolysis in a single step with no carbon by-product. SOM electrolysis has been previously employed in the production of magnesium, titanium, and tantalum. In this work, the anodic primary, secondary, and tertiary current density distributions are modelled. The models used a simplified unit of a large-scale cell with an electrolyte conductivity value of 438 S m-1 with a flux composition of MgF2 – CaF2 – CaO – Y2O3 – SiO2. The anodic current density distribution was found to be between 0.5 ~ 1 A cm-2. An optimal cathodic thickness beyond which current density changes minimally was found to be 6 cm. The magnetohydrodynamic (MHD) effects due to current flowing through the conductor are modelled and show a very slow flow rate in the electrolyte compared to an analytical calculation. Lab scale experimental work shows pure silicon deposits in the flux using a solid silicon cathode at an operating temperature of 11000C.

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