Electrode including active materials having coat materials with different isoelectric points, and battery using same

1. An electrode comprising:

a collector; and

an electrode mix layer disposed on the collector, the electrode mix layer comprising:

an active material A provided with a core portion A and a coat material A disposed on a surface of the core portion A, and

an active material B provided with a core portion B and a coat material B disposed on a surface of the core portion B, wherein:

the coat material A has an isoelectric point, based on an electrophoretic method, of 7 or lower,

the coat material B has an isoelectric point, based on the electrophoretic method, of 7 or higher,

the isoelectric point of at least one of the coat material A and the coat material B is not 7, and

the active material A and the active material B have different surface charge states.

2. The electrode according to claim 1 , wherein an average particle size Da of the active material A and an average particle size Db of the active material B satisfy the following expression: 1≤(Db/Da)≤2.

3. The electrode according to claim 1 , wherein the isoelectric point of the coat material A is 5 or lower.

4. The electrode according to claim 1 , wherein the isoelectric point of the coat material A is lower than 2.

5. The electrode according to claim 1 , wherein the coat material A is selected from the group consisting of WO 3 , V 3 O 8 , Ta 2 O 5 , and TiO 2 .

6. The electrode according to claim 1 , wherein the coat material B is selected from the group consisting of Nb 2 O 3 , Y 2 O 3 , ThO 2 , BeO, CuO, ZnO, CdO, AlOOH, Cu(OH) 2 , Cd(OH) 2 , Ni(OH) 2 , and Mg(OH) 2 .

7. The electrode according to claim 1 , wherein the isoelectric point of the coat material B is higher than 9.

8. The electrode according to claim 1 , wherein the isoelectric point of the coat material B is 10 or higher.

9. The electrode according to claim 1 , wherein a difference between the isoelectric point of the coat material A and the isoelectric point of the coat material B is 4 or greater.

10. The electrode according to claim 1 , wherein a difference between the isoelectric point of the coat material A and the isoelectric point of the coat material B is 7.2 or greater.

11. The electrode according to claim 1 , wherein the coat material A and the coat material B are disposed on the surfaces of the core portion A and the core portion B, respectively, in a dotted pattern.

12. The electrode according to claim 1 , wherein each of the active material A and the active material B are disposed throughout an entire thickness of the electrode mix layer.

13. The electrode according to claim 1 , wherein when dividing the electrode mix layer in two in a thickness direction, into an upper layer portion and a lower layer portion that is closer to the collector than the upper layer,

the lower layer portion contains more of the active material B than of the active material A, and

the upper layer portion contains more of the active material A than of the active material B.

14. The electrode according to claim 13 , wherein at least one of the lower layer portion and the upper layer portion contains both the active material A and the active material B.

15. The electrode according to claim 1 ,

wherein when dividing the electrode mix layer in three in a thickness direction, into a first layer, a second layer and a third layer, sequentially from a side facing the collector, and

when P1 represents a total of outer peripheral lengths of the active materials B included in the first layer, and P3 represents a total of outer peripheral lengths of the active materials B included in the third layer,

the P1 and the P3 satisfy the following expression: 1≤(P1/P3)≤4.

16. The electrode according to claim 15 , wherein at least one of the first layer, the second layer, and the third layer contains both the active material A and the active material B.

17. A battery comprising the electrode according to claim 1 .