Zero-Direct-Carbon-Emission Production of Si Epitaxy Enabled by Solid Oxide Membrane (SOM) Electrolysis

State-of-the-art Solar-grade silicon production is energy intensive and has a negative impact on the environment. Due to the rapid growth of the Si-based photovoltaic (PV) industry, it is necessary to develop a greener technology for silicon production. Solid oxide membrane (SOM) electrolysis is a proven versatile green technology that can be developed to economically produce many important metal or metal compounds from their oxides. This work will discuss the application of SOM electrolysis to produce solar-grade silicon epitaxially from silica in a single-step, which results in net zero-carbon emission. The high-temperature SOM electrolysis cell employs stable molten oxide-fluoride bath with silicon wafer cathode and stabilized zirconia membrane-based novel anodes. The cell design and process parameters are selected to enable high-efficiency silicon deposition on the Si-wafer cathode and mitigate undesired side-reactions. The SOM process is electrochemically characterized with detailed microstructural analysis of the Si deposit on the Si wafer cathode.