Sodium-ion rechargeable battery

Abstract

Provided is a sodium ion secondary battery that exhibits a high capacity and an excellent safety.　This sodium ion secondary battery characteristically comprises: a positive electrode that contains a positive electrode active material comprising a crystallized glass that contains crystals represented by the general formula NaxMyP2Oz (1 ≤ x ≤ 2.8, 0.95 ≤ y ≤ 1.6, 6.5 ≤ z ≤ 8, and M is at least one selection from Fe, Ni, Co, Mn, and Cr); a negative electrode that contains a negative electrode active material comprising hard carbon; and a nonaqueous electrolyte.

Claims

1. General formula Na ｘ M ｙ P ２ O ｚ A positive electrode comprising a positive electrode active material made of crystallized glass containing crystals represented by (1 ≤ x ≤ 2.8, 0.95 ≤ y ≤ 1.6, 6.5 ≤ z ≤ 8, where M is at least one selected from Fe, Ni, Co, Mn, and Cr), A negative electrode containing a negative electrode active material made of hard carbon, and non-aqueous electrolyte, Equipped with, A sodium-ion secondary battery characterized in that the hard carbon is coated with a coating layer containing beta-alumina crystals or NASICON crystals.

2. The positive electrode active material is, ｘ MP ２ O ７ The sodium-ion secondary battery according to claim 1, characterized in that it is made of crystallized glass containing crystals represented by (1 ≤ x ≤ 2, where M is at least one selected from Fe, Ni, Co, Mn, and Cr).

3. The positive electrode active material is represented by the general formula Na ｘ FeP ２ O ７ The sodium ion secondary battery according to claim 1, characterized in that it comprises a crystallized glass containing a crystal represented by (1 ≦ x ≦ 2).

4. The sodium-ion secondary battery according to any one of claims 1 to 3, characterized in that the positive electrode active material is coated with a carbon material.

5. The sodium ion secondary battery according to any one of claims 1 to 3, characterized in that the positive electrode active material consists of secondary particles.

6. A sodium-ion secondary battery according to any one of claims 1 to 3, characterized in that the non-aqueous electrolyte comprises an organic electrolyte and / or a gel polymer electrolyte.

7. An electrical device characterized by using a sodium-ion secondary battery as described in any one of claims 1 to 3.

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