Electrode active material, electrode, and nonaqueous electrolyte secondary battery

1. An electrode active material comprising a mixture of 10 parts by weight to 900 parts by weight of a first lithium mixed metal oxide and 100 parts by weight of a second lithium mixed metal oxide, wherein:

the first lithium mixed metal oxide is in a powder form and has a BET specific surface area of 3 m 2 /g or more and 30 m 2 /g or less;

the second lithium mixed metal oxide is in a powder form and has a BET specific surface area of 0.1 m 2 /g or more and 2 m 2 /g or less; and

the first lithium mixed metal oxide is constituted of primary particles having a diameter within a range of 0.01 μm or more and 0.5 μm or less, and aggregated particles having an average diameter of 0.05 μm or more and 2 μm or less formed by aggregating primary particles particles having a diameter within the above range.

2. The electrode active material according to claim 1 , wherein the first lithium mixed metal oxide contains Fe.

3. The electrode active material according to claim 2 , wherein the first lithium mixed metal oxide is represented by the formula (1):

Li(Ni 1-x-y Mn x Fe y )O 2   (1)

wherein, x is more than 0 and less than 1,

y is more than 0 and less than 1, and

x+y is more than 0 and less than 1.

4. The electrode active material according to claim 3 , wherein x is 0.1 or more and 0.7 or less, y is 0.01 or more and 0.5 or less, and x+y is 0.11 or more and less than 1.

5. The electrode active material according to claim 1 , wherein the second lithium mixed metal oxide is constituted of primary particles having a diameter within a range of 0.1 μm or more and 1 μm or less, and aggregated particles having an average diameter of 3 μm or more and 20 μm or less formed by aggregating primary particles having a diameter within the above range.

6. The electrode active material according to claim 1 , wherein the second lithium mixed metal oxide contains Ni or Co.

7. The electrode active material according to claim 6 , wherein the second lithium mixed metal oxide is represented by the formula (2):

Li(Ni 1-a-b Co a M b )O 2   (2)

wherein, M represents one or more kinds selected from the group consisting of Ti, V, Mn, B, Al and Ga, a is 0 or more and 1 or less, b is 0 or more and 0.5 or less, and a+b is 0 or more and less than 1.

8. An electrode comprising the electrode active material according to claim 1 .

9. A nonaqueous electrolyte secondary battery comprising the electrode according to claim 8 as a positive electrode.

10. The nonaqueous electrolyte secondary battery according to claim 9 , further comprising a separator.

11. The nonaqueous electrolyte secondary battery according to claim 10 , wherein the separator comprises a laminate film in which a heat resistant porous layer and a porous film are stacked each other.

12. An electrode active material which is obtained by mixing a powdery first lithium mixed metal oxide having a BET specific surface area of 3 m 2 /g or more and 30m 2 /g or less with a powdery second lithium mixed metal oxide having a BET specific surface area of 0.1 m 2 /g or more and 2 m 2 /g or less in a mixing ratio of 10 parts by weight or more and 900 parts by weight or less of the first lithium mixed metal oxide per 100 parts by weight of the second lithium mixed metal oxide, wherein the first lithium mixed metal oxide is constituted of primary particles having a diameter within a range of 0.01 μm or more and 0.5 μm or less, and aggregated particles having an average diameter of 0.05 μm or more and 2 μm or less formed by aggregating primary particles having a diameter within the above range.