System and method for purification of electrolytic salt
AssigneeArizona Board of Regents on behalf of Arizona State University
InventorsMeng Tao, Xiaofei Han
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Abstract
Methods and systems for removing impurities from an electrolytic salt are disclosed. After removal of impurities from the salt, the salt can be subjected to electrorefining to produce high-purity materials, for example silicon. Impurities are removed from the salt using a system that includes a first working electrode, a counter electrode, and at least one reference electrode. A second working electrode can also be utilized. The salt may be utilized in an electrorefining system, for example a system operated in a single phase or multiple phase operation to produce high-purity materials, such as solar-grade silicon.
Claims9
A method for purifying a salt having multiple impurities, the method comprising:
- providing a system comprising a first working electrode, a counter electrode, a reference electrode, and a system control, wherein the first working electrode, the counter electrode, and the reference electrode are electrically coupled to the salt;
- setting, via the system control, a desired electrical potential between the reference electrode and the first working electrode;
- applying sufficient electrical energy to the system to cause a negatively-charged first targeted impurity within the salt to deposit on the surface of the first working electrode;
- removing the first working electrode from the salt;
- electrically coupling a second working electrode to the salt;
- setting, via the system control, a desired electrical potential between the reference electrode and the second working electrode;
- and
- applying sufficient electrical energy to the system to cause a positively-charged second targeted impurity within the salt to deposit on the surface of the second working electrode.
A method, comprising:
- in a vessel, removing a positively-charged impurity from a salt via operation of a purification system comprising a working electrode, a counter electrode, and a reference electrode by applying a sufficient electrical energy to the system between the reference electrode and the working electrode to cause the positively-charged impurity to deposit on the working electrode, wherein the salt comprises a non-oxygen anion and a metal cation having a more negative standard reduction potential than silicon;
- replacing the working electrode with a second working electrode;
- in the vessel, removing a negatively-charged impurity from the salt via the purification system by applying a sufficient electrical energy between the reference electrode and the second working electrode to cause the negatively-charged impurity to deposit on the second working electrode;
- and
- in the vessel, electrorefining silicon using the salt as an electrolyte.
Dependencies are inferred from the claim text.