NASICON-based electrode composition for calcium-ion batteries and calcium-ion batteries containing the same

NASICON-structured vanadium phosphate cathode for calcium storage in sodium-vacant sites

This technology is an electrode composition for calcium-ion batteries that uses rhombohedral NASICON-structured NaV2(PO4)3 as a cathode active material, allowing calcium ions (Ca2+) to be reversibly inserted into and extracted from the sites vacated by sodium ions.

Existing cathode materials developed for lithium-ion batteries, such as V2O5, MoO3, and Mo6S8, have struggled with the reversible insertion and extraction of divalent calcium ions. Consequently, applying these materials directly to calcium-ion batteries often results in either the inability to charge and discharge or significantly degraded performance.

This technology involves synthesizing Na3V2(PO4)3 first, then removing a portion of the sodium ions through electrochemical or chemical oxidation to convert it into NaV2(PO4)3, thereby pre-securing active sites for calcium ion transport. It can be applied to next-generation multivalent-ion batteries aimed at reducing reliance on lithium resources and to cathode materials for large-capacity stationary energy storage systems, providing a pathway for developing batteries that utilize abundant and inexpensive calcium as a charge carrier.

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Key Features:

• Na1V2(PO4)3 cathode active material where calcium ions are reversibly inserted into and extracted from the sodium-vacant sites created by the removal of sodium
• Step of preparing a mixture by combining a sodium precursor, a vanadium precursor, and a phosphate in a solvent
• Step of oxidizing the Na3V2(PO4)3 obtained by heating the prepared mixture using electrochemical or chemical methods
• Cathode for calcium secondary batteries formed by applying Na3V2(PO4)3, a binder, and a conductive agent to a current collector, followed by electrochemical oxidation of the electrode

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