Chemical Reaction Complex Processes

Advanced Energy Utilization Division Chemical Reaction Complex Processes Research Section

Professor : Toshiyuki NOHIRA
Associate Professor : Tsutomu KODAKI
Assistant Professor : Takayuki YAMAMOTO

We are studying materials and systems to realize renewable energies like photovoltaics and bioenergy as the major primary energy source for human beings. We are conducting innovative researches that cover the phases from basic research to applications mainly based on electrochemistry and biochemistry.

http://www.iae.kyoto-u.ac.jp/chemical/en/index.html

Development of new production processes for solar silicon utilizing molten salt electrolysis

Crystalline silicon solar cells are the most spreading in the world owing to the advantages of high efficiency, high durability, harmlessness for the environment, and abundant resources. Naturally, they are expected to play a major role in the era of full-fledged dissemination of solar cells. However, high purity silicon (or solar-grade silicon, 6N purity),
which is necessary for the solar cells, is currently produced by a similar method that was developed for the production of semiconductor-grade silicon (11N purity). A new production method of solar-grade silicon is required because the conventional production method has the disadvantages of low energy efficiency, low productivity, and high cost. From this background, we have proposed a new production method of silicon from the purified silica (SiO2) feedstock by using molten salt electrolysis. We have already verified the principle of the method, and are now tackling the development of continuous electrolysis process and the improvement of purity. The conventional production process of crystalline silicon solar cells also has several other problems such as the large kerf loss and the complex process of cell production. So, we have proposed a new production method of crystalline silicon film by molten salt electroplating. For this method, we have already confirmed the principle as well. We are now taking on the research on the improvement of film quality and the utilization of SiCl4 as a silicon source.

A new production method of solar-grade silicon by the electrochemical reduction of silica in molten salt

We have proposed a new production method of silicon which utilizes electrochemical reduction of powdery SiO2 in molten CaCl2 (left). A photo of the sample obtained in the principle verification experiment (top right). A photo of the crystalline silicon rod prepared from the electrochemically produced silicon powder by a floating zone method (bottom right).

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A new production method of silicon films for solar cells by the molten slat electroplating

We have proposed a new production method of crystalline silicon films by electroplating in molten KF-KCl (left). An SEM image of the crystalline silicon film electroplated on a silver wire (top right). An EBSD image of the electroplated silicon film showing its high crystallinity (bottom right).

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Highly efficient energy production from biomass

Associate Professor : Tsutomu KODAKI

The more efficient use of biomass is demanded to solve the global crises such as exhaustion of fossil fuel and global warming. We focus on the highly efficient production of ethanol from biomass using genetic engineering.

Strategy for construction of efficient ethanol production system from biomass.

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