ELECTRODE SHEET AND ELECTRODE SHEET ASSEMBLY

1 . An electrode sheet, comprising:

a current collector having a first surface and a second surface opposite to the first surface;

a first active material layer covering at least a part of the first surface; and

a second active material layer covering at least a part of the second surface.

2 . The electrode sheet of claim 1 , wherein the electrode sheet is a positive electrode sheet, the first active material layer and the second active material layer have identical active materials, a difference between a particle size D 10 of active material particles of the first active material layer and a particle size D 10 of active material particles of the second active material layer is 0.05 μm˜0.3 μm; a difference between a particle size D 50 of the active material particles of the first active material layer and a particle size D 50 of the active material particles of the second active material layer is 1 μm˜4 μm; and a difference between a particle size D 90 of the active material particles of the first active material layer and a particle size D 90 of the active material particles of the second active material layer is 3 μm˜5 μm; or

the electrode sheet is the positive electrode sheet, the first active material layer and the second active material layer have different active materials, a difference between a particle size D 10 of active material particles of the first active material layer and a particle size D 10 of active material particles of the second active material layer is 1 μm˜3 μm; a difference between a particle size D 50 of the active material particles of the first active material layer and a particle size D 50 of the active material particles of the second active material layer is 2 μm˜5 μm; and a difference between a particle size D 90 of the active material particles of the first active material layer and a particle size D 90 of the active material particles of the second active material layer is 3 μm˜25 μm.

3 . The electrode sheet of claim 1 , wherein the electrode sheet is a negative electrode sheet, the first active material layer and the second active material layer have identical active materials, a difference between a particle size D 10 of active material particles of the first active material layer and a particle size D 10 of active material particles of the second active material layer is 0.1 μm˜4 μm; a difference between a particle size D 50 of the active material particles of the first active material layer and a particle size D 50 of the active material particles of the second active material layer is 0.1 μm˜8 μm; and a difference between a particle size D 90 of the active material particles of the first active material layer and a particle size D 90 of the active material particles of the second active material layer is 0.1 μm˜10 μm; or

the electrode sheet is the negative electrode sheet, the first active material layer and the second active material layer have different active materials, a difference between a particle size D 10 of active material particles of the first active material layer and a particle size D 10 of active material particles of the second active material layer is 0.1 μm˜4 μm; a difference between a particle size D 50 of the active material particles of the first active material layer and a particle size D 50 of the active material particles of the second active material layer is 0.1 μm˜10 μm; and a difference between a particle size D 90 of the active material particles of the first active material layer and a particle size D 90 of the active material particles of the second active material layer is 0.1 μm˜20 μm.

4 . The electrode sheet of claim 2 , wherein when the first active material layer and the second active material layer have the identical active materials, and a difference between a compacted density of the active material particles of the first active material layer and a compacted density of the active material particles of the second active material layer is no less than 0.02 g/cm 3 ; or

the electrode sheet is the positive electrode sheet, the first active material layer and the second active material layer have the different active materials, and a difference between a compacted density of the active material particles of the first active material layer and a compacted density of the active material particles of the second active material layer is no less than 0.8 g/cm 3 .

5 . The electrode sheet of claim 3 , wherein a difference between a compacted density of the active material particles of the first active material layer and a compacted density of the active material particles of the second active material layer is 0.1 g/cm 3 ˜1.8 g/cm 3 .

6 . The electrode sheet of claim 2 , wherein the active material of the first active material layer and/or the second active material layer is lithium iron phosphate, and the lithium iron phosphate satisfies following conditions:

a particle size D 10 is greater than 0.4 μm;

a particle size D 50 is 0.8 μm˜4 μm; and

a particle size D 90 is 3 μm˜10 μm.

7 . The electrode sheet of claim 2 , wherein the active material of the first active material layer and/or the second active material layer is ternary single crystal material, and the ternary single crystal material satisfies following conditions:

the particle size D 10 is greater than 1.5 μm;

the particle size D 50 is 4 μm˜10 μm; and

the particle size D 90 is 9 μm˜20 μm.

8 . The electrode sheet of claim 2 , wherein the active material of the first active material layer and/or the second active material layer is ternary polycrystalline material, and the ternary polycrystalline material satisfies following conditions:

the particle size D 10 is greater than 1.5 μm;

the particle size D 50 is 8 μm˜12 μm; and

the particle size D 90 is 18 μm˜34 μm.

9 . The electrode sheet of claim 3 , wherein the active material of the first active material layer and/or the second active material layer is graphite, and the graphite satisfies following conditions:

the particle size D 10 is greater than 4 μm;

the particle size D 50 is 7 μm˜15 μm; and

the particle size D 90 is no more than 30 μm.

10 . The electrode sheet of claim 3 , wherein the active material of the first active material layer and/or the second active material layer is silicon carbide, and the silicon carbide satisfies following conditions:

the particle size D 10 is 1 μm˜4 μm;

the particle size D 50 is 4 μm˜8 μm; and

the particle size D 90 is 9 μm˜12 μm.

11 . The electrode sheet of claim 3 , wherein the active material of the first active material layer and/or the second active material layer is mesocarbon microbeads, and the mesocarbon microbeads satisfy following conditions:

the particle size D 10 is greater than 4 μm;

the particle size D 50 is 7˜15 μm; and

the particle size D 90 is no more than 30 μm.

12 . The electrode sheet of claim 1 , wherein the first active material layer and the second active material layer each comprise lithium iron phosphate, a difference between a carbon coating amount of the lithium iron phosphate in the first active material layer and a carbon coating amount of the lithium iron phosphate in the second active material layer is greater than or equal to 0.1%, and the carbon coating amount is a ratio of a mass of the carbon to a total mass of the lithium iron phosphate and the carbon.

13 . The electrode sheet of claim 2 , wherein when the first active material layer and the second active material layer have the identical active materials, a difference between a specific surface area of the active material particles of the first active material layer and a specific surface area of the active material particles of the second active material layer is 0.1 m 2 /g˜8 m 2 /g; or

when the first active material layer and the second active material layer have the different active materials, a difference between a specific surface area of the active material particles of the first active material layer and a specific surface area of the active material particles of the second active material layer is 7 m 2 /g˜15 m 2 /g.

14 . The electrode sheet of claim 3 , wherein when the first active material layer and the second active material layer have the identical active materials, a difference between a specific surface area of the active material particles of the first active material layer and a specific surface area of the active material particles of the second active material layer is 0.2 m 2 /g˜8 m 2 /g; or

when the first active material layer and the second active material layer have the different active materials, a difference between a specific surface area of the active material particles of the first active material layer and a specific surface area of the active material particles of the second active material layer is 0.5 m 2 /g˜8 m 2 /g.

15 . The electrode sheet of claim 2 , wherein when the first active material layer and the second active material layer have the identical active materials, a difference between a gram capacity of the active material particles of the first active material layer and a gram capacity of the active material particles of the second active material layer is 10 mAh/g˜60 mAh/g; or

when the first active material layer and the second active material layer have the different active materials, a difference between a gram capacity of the active material particles of the first active material layer and a gram capacity of the active material particles of the second active material layer is 20 mAh/g˜110 mAh/g.

16 . The electrode sheet of claim 3 , wherein when the first active material layer and the second active material layer have the identical active materials, a difference between a gram capacity of the active material particles of the first active material layer and a gram capacity of the active material particles of the second active material layer is 10 mAh/g˜100 mAh/g; or

when the first active material layer and the second active material layer have the different active materials, a difference between a gram capacity of the active material particles of the first active material layer and a gram capacity of the active material particles of the second active material layer is 10 mAh/g˜200 mAh/g.

17 . The electrode sheet of claim 2 , wherein a difference between a thickness of the first active material layer and a thickness of the second active material layer is 5 μm˜50 μm.

18 . The electrode sheet of claim 3 , wherein a difference between a thickness of the first active material layer and a thickness of the second active material layer is 5 μm˜100 μm.

19 . An electrode sheet assembly, comprising a separator, and two electrode sheets which are located at two sides of the separator and have opposite polarities; wherein

at least one of the two electrode sheets comprises:

a current collector having a first surface and a second surface opposite to the first surface;

a first active material layer covering at least a part of the first surface; and

a second active material layer covering at least a part of the second surface.

20 . The electrode sheet assembly of claim 19 , wherein one of a positive current collector and a negative current collector of the electrode sheet assembly is a composite current collector, and another is a metal foil current collector.