Mechanism of Electrolytic Reduction of SiO2 at Liquid Zn Cathode in Molten CaCl2
Mechanism of Electrolytic Reduction of SiO2 at Liquid Zn Cathode in Molten CaCl2
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DOI：
10.1149/2.1211904jes
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发表时间：
2019
影响因子：
3.9
通讯作者：
Yuanjia Ma;Akifumi Ido;K. Yasuda;R. Hagiwara;T. Homma;T. Nohira
中科院分区：
文献类型：
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作者：
Yuanjia Ma;Akifumi Ido;K. Yasuda;R. Hagiwara;T. Homma;T. Nohira
研究了液态锌阴极在熔融CaCl2中电解还原SiO2的反应机理，建立了太阳级硅的新生产工艺。根据物镜的不同，制备了三种不同类型的Zn/SiO2接触电极。循环伏安法表明SiO2在Zn电极上有两种还原机制。一种是直接电解还原，在比1.55 V更负的25个电位下进行。另一种是26液态Ca-Zn合金在大于0.85 V的负电位下间接还原。通过电解和浸泡实验，证实了两种还原机制均在0.60 V下进行。对0.60 V下29恒电位电解制备的Si进行了ICP-AES杂质分析，确定了定向凝固前金属30元素和P的浓度低于初晶Si的目标水平。32
20 The reaction mechanism of electrolytic reduction of SiO2 at a liquid Zn cathode 21 in molten CaCl2 was investigated with the aim of establishing a new production process 22 of solar-grade Si. Three types of Zn/SiO2 contacting electrodes were prepared 23 depending on the objectives. Cyclic voltammetry suggested two reduction mechanisms 24 of SiO2 at a Zn electrode. One is a direct electrolytic reduction that proceeds at 25 potentials more negative than 1.55 V vs. Ca 2+ /Ca. The other is an indirect reduction by 26 liquid Ca–Zn alloy at potentials more negative than 0.85 V. The both reduction 27 mechanisms were confirmed to proceed at 0.60 V by electrolysis and immersion 28 experiments. Impurity analysis by ICP-AES was conducted for the Si prepared by 29 potentiostatic electrolysis at 0.60 V, and confirmed that the concentrations of the metal 30 elements and P were lower than the target levels for primary Si before directional 31 solidification process. 32