Innovation in Production Method of Solar Silicon

2015 Fiscal Year Final Research Report

• Project/Area Number: 23246131
• Research Category: Grant-in-Aid for Scientific Research (A)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Metal making engineering
• Research Institution: Kyoto University
• Principal Investigator: Nohira Toshiyuki 京都大学, エネルギー理工学研究所, 教授 (00303876)
• Project Period (FY): 2011-04-01 – 2016-03-31
• Keywords: 太陽電池用シリコン / シリカ / 溶融塩電解 / 低リン / 低ホウ素 / 連続プロセス

Outline of Final Research Achievements

We developed the new production process of silicon with low concentrations of boron and phosphorous by the electrochemical reduction of silica in molten CaCl2 at 1123 K. The lowest impurity level of the obtained silicon was confirmed to be B < 0.5 ppm and P < 0.4 ppm by ICP-MS and GD-MS. Aiming at the development of a continuous production method, we investigated the electrochemical reduction of silica on a liquid zinc cathode in molten CaCl2 at 1123 K. By SEM/EDX analysis, silica powder was confirmed to be reduced to silicon. Moreover, we succeeded in the recovery of silicon from the liquid Zn-Si alloy.

Free Research Field

電気化学、溶融塩