Electrode Plate, Electrode Assembly, Battery Cell, Battery, and Electric Appliance

1 . An electrode plate, comprising:

a current collector; and

an active substance layer disposed on a surface of at least one side of the current collector;

wherein:

the active substance layer has a first active substance region and a second active substance region;

a sectional area S 2 of the second active substance region in a preset section is smaller than a sectional area S of the active substance layer in the preset section, the preset section being parallel to a preset surface and passing through the second active substance region, and the preset surface being a surface of the current collector and the active substance layer being located at the preset surface;

a porosity P 1 of the first active substance region is smaller than a porosity P 2 of the second active substance region; and

pores in the first active substance region and in the second active substance region all have a pore size smaller than or equal to 1 μm.

2 . The electrode plate according to claim 1 , wherein a difference between P 2 and P 1 ranges from 3% to 20%.

3 . The electrode plate according to claim 1 , wherein:

P 1 ranges from 15% to 35%; and/or

P 2 ranges from 20% to 50%.

4 . The electrode plate according to claim 1 , wherein:

both the first active substance region and the second active substance region have an active substance of lithium iron phosphate; and

a ratio of a compaction density C 1 of the first active substance region to a compaction density C 2 of the second active substance region ranges from 1.02 to 1.7.

5 . The electrode plate according to claim 4 , wherein:

C 1 ranges from 2.3 g/cm 3 to 2.7 g/cm 3 ; and

C 2 ranges from 1.6 g/cm 3 to 2.2 g/cm 3 .

6 . The electrode plate according to claim 1 , wherein:

both the first active substance region and the second active substance region have an active substance of a ternary cathode material; and

a ratio of a compaction density C 1 of the first active substance region to a compaction density C 2 of the second active substance region ranges from 1.02 to 1.5.

7 . The electrode plate according to claim 6 , wherein:

C 1 ranges from 3.1 g/cm 3 to 3.7 g/cm 3 ; and

C 2 ranges from 2.5 g/cm 3 to 3 g/cm 3 .

8 . The electrode plate according to claim 1 , wherein:

both the first active substance region and the second active substance region have an active substance of graphite; and

a ratio of a compaction density C 1 of the first active substance region to a compaction density C 2 of the second active substance region ranges from 1.1 to 1.7.

9 . The electrode plate according to claim 8 , wherein:

C 1 ranges from 1.3 g/cm 3 to 1.8 g/cm 3 ; and

C 2 ranges from 1.1 g/cm 3 to 1.5 g/cm 3 .

10 . The electrode plate according to claim 1 , wherein at least one of following conditions is satisfied:

S×2.5%≤S 2 ≤S×30%; and

the active substance layer has a thickness of h, and the second active substance region has a thickness of h 2 , where h×30%≤h 2 ≤h×100%.

11 . The electrode plate according to claim 1 , wherein in a width direction of the electrode plate, a minimum distance between the second active substance region and a center of the active substance layer is smaller than or equal to 35% of a size of the active substance layer.

12 . The electrode plate according to claim 1 , wherein in a width direction of the electrode plate, a minimum distance between the second active substance region and an edge of the active substance layer is smaller than or equal to 20% of a size M of the active substance layer.

13 . The electrode plate according to claim 1 , wherein:

the second active substance region is one of a plurality of second active substance regions distributed at intervals along a length direction of the electrode plate; and

in a width direction of the electrode plate, at least one of following conditions is satisfied:

a minimum distance between the second active substance region and a center of the active substance layer is smaller than or equal to 10% of a size of the active substance layer; and

a distance between two ends of each of the second active substance regions is larger than or equal to 30% of the size of the active substance layer.

14 . The electrode plate according to claim 1 , wherein:

the second active substance region is one of a plurality of second active substance regions distributed at intervals along a width direction of the electrode plate; and

in the width direction of the electrode plate, a spacing between two adjacent ones of the second active substance regions is smaller than or equal to 20% of a size of the active substance layer.

15 . The electrode plate according to claim 1 , wherein:

a thickness of the second active substance region is larger than or equal to 30% of a thickness of the active substance layer and smaller than or equal to 60% of the thickness of the active substance layer; and

a distance from the second active substance region to a surface of the active substance layer is smaller than a distance from the active substance layer to the preset surface.

16 . An electrode assembly, comprising:

a positive electrode plate;

a negative electrode plate; and

a separator separating the positive electrode plate and the negative electrode plate;

wherein at least one of the positive electrode plate or the negative electrode plate comprises:

a current collector; and

an active substance layer disposed on a surface of at least one side of the current collector;

wherein:

the active substance layer has a first active substance region and a second active substance region;

a sectional area of the second active substance region in a preset section is smaller than a sectional area of the active substance layer in the preset section, the preset section being parallel to a preset surface and passing through the second active substance region, and the preset surface being a surface of the current collector and the active substance layer being located at the preset surface;

a porosity of the first active substance region is smaller than a porosity of the second active substance region; and

pores in the first active substance region and in the second active substance region all have a pore size smaller than or equal to 1 μm.

17 . The electrode assembly according to claim 16 , wherein:

the electrode assembly is of a winding structure, a width direction of the at least one of the positive electrode plate or the negative electrode plate is identical with an axial direction of the electrode assembly, and a length direction of the at least one of the positive electrode plate or the negative electrode plate is identical with a winding direction of the electrode assembly; and

the electrode assembly has a diameter of d, and in the winding direction of the electrode assembly, each region having an arc length of πd/4 has at least a part of the second active substance region.

18 . A battery cell, comprising:

a housing; and

an electrode assembly accommodated in the housing and comprising:

a positive electrode plate;

a negative electrode plate; and

a separator separating the positive electrode plate and the negative electrode plate;

wherein at least one of the positive electrode plate or the negative electrode plate comprises:

a current collector; and

an active substance layer disposed on a surface of at least one side of the current collector;

wherein:

the active substance layer has a first active substance region and a second active substance region;

a sectional area of the second active substance region in a preset section is smaller than a sectional area of the active substance layer in the preset section, the preset section being parallel to a preset surface and passing through the second active substance region, and the preset surface being a surface of the current collector and the active substance layer being located at the preset surface;

a porosity of the first active substance region is smaller than a porosity of the second active substance region; and

pores in the first active substance region and in the second active substance region all have a pore size smaller than or equal to 1 μm.