Alumina powder, alumina slurry, alumina-containing coating layer, multilayer separation membrane and secondary battery

1. An alumina powder wherein a ratio (TBD/LBD) of a tapped bulk density (TBD) to a loose bulk density (LBD) is 1.5 or more, and wherein a BET specific surface area is 3.0 to 7.0 m 2 /g and a ratio (D90/D10) of a particle diameter equivalent to 90% in the volume-based cumulative particle size distribution (D90) to a particle diameter equivalent to 10% in the volume-based cumulative particle size distribution (D10) is 3.0 to 4.0.

2. The alumina powder according to claim 1 , wherein the alumina powder has a purity of 99.9% by mass or less.

3. The alumina powder according to claim 1 , wherein TBD/LBD is 1.82 to 1.90.

4. The alumina powder according to claim 1 , wherein the LBD is 0.39 to 0.44 g/cm 3 and the TBD is 0.72 to 0.80 g/cm 3 .

5. The alumina powder according to claim 1 , wherein a particle diameter equivalent to 50% in the volume-based cumulative particle size distribution (D50) is 0.45 to 0.65 μm.

6. The alumina powder according to claim 5 , wherein a particle diameter equivalent to 100% in the volume-based cumulative particle size distribution (D100) is 3.5 μm or less.

7. The alumina powder according to claim 1 , wherein the content of particles having a particle diameter of 20 μm or more is less than 100 ppm.

8. An alumina slurry comprising: the alumina powder according to claim 1 ; a binder; and a solvent.

9. An alumina-containing coating layer comprising: the alumina powder according to claim 1 ; and a binder.

10. A multilayer separation membrane comprising: a separation membrane; and the alumina-containing coating layer according to claim 9 formed on at least one surface of the separation membrane.

11. A secondary battery comprising:

a first electrode, a separation membrane and a second electrode laminated sequentially; and

an alumina-containing coating layer formed of the alumina powder according to claim 1 , the alumina-containing coating layer being formed on at least one surface of the first electrode, the separation membrane or the second electrode.

12. The secondary battery according to claim 11 , wherein the alumina-containing coating layer is formed on at least one interface of an interface between the first electrode and the separation membrane or an interface between the second electrode and the separation membrane.

13. The secondary battery according to claim 11 , wherein the alumina-containing coating layer entirely coats at least one surface the first electrode, the separation membrane or the second electrode.

14. The secondary battery according to claim 11 ,

wherein the alumina-containing coating layer is formed on the separation membrane, and

wherein the alumina-containing coating layer is formed of a binder containing the alumina powder and a water-soluble polymer.

15. The secondary battery according to claim 11 ,

wherein the alumina-containing coating layer is formed on the separation membrane, and

wherein the alumina-containing coating layer is formed of a binder containing the alumina powder and an aromatic polymer.

16. The secondary battery according to claim 11 ,

wherein the alumina-containing coating layer is formed on the separation membrane, and

wherein the alumina-containing coating layer is formed of a binder containing the alumina powder and a fluorine-containing resin or a fluorine-containing rubber.

17. The secondary battery according to claim 11 ,

wherein the alumina-containing coating layer is formed on the separation membrane, and

wherein the alumina-containing coating layer is formed of a binder containing the alumina powder and acrylate-based monomer or a copolymer of two or more monomers.