Chemical Reaction Complex Processes

Advanced Energy Utilization Division Chemical Reaction Complex Processes Research Section

Professor : Toshiyuki NOHIRA
Program-Specific Associate Professor : Kenji KAWAGUCHI
Assistant Professor : Takayuki YAMAMOTO
Assistant Professor : Yutaro NORIKAWA

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. Also, 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 improvement of fi lm 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

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

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Development of Plating Process of Titanium Utilizing Molten Salt Electrolysis

To utilize surface properties of titanium and its alloys, a method to form a titanium film on the substrate has shown great promise. We are developing a plating method in molten salt as a method that enables uniform titanium deposition even on substrates with complex shapes.

Obtained Ti films with smooth surface by the molten salt electroplating

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Development of next-generation batteries using highly-safe ionic liquid electrolytes

Renewable energy resources such as solar and wind power are intermittent resources, and their power generations are largely dependent on the weather. Thus, introduction of a large amount of renewable energy requires large-scale power storage systems such as large-sized batteries. Although current lithium-ion batteries are candidates for large-sized batteries, scarce resources (lithium, cobalt) and flammable electrolytes (organic solvents) are used as main components, which will be a major barrier for the widespread distribution in the future. Therefore, we are now developing next-generation batteries utilizing abundant resources (sodium, potassium, etc.) and safer electrolytes (ionic liquids).

Principle of potassium-ion battery

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