NEGATIVE ELECTRODE PLATE AND PREPARATION METHOD THEREOF, BATTERY CELL, BATTERY, AND ELECTRICAL DEVICE
Provided are a negative electrode plate and a preparation method thereof, a battery cell, a battery, and an electrical device. The negative electrode plate includes a current collector and a film layer disposed on the current collector. The film layer includes a first part and a second part disposed along a thickness direction of the film layer. The first part is disposed on the current collector. The second part is disposed on the first part. The first part includes a first active material. The second part includes a second active material. The first active material includes a first carbon-based material. The second active material includes a second carbon-based material containing a coating layer. A powder compaction density of the first active material is greater than a powder compaction density of the second active material.
1 . A negative electrode plate, characterized in that the negative electrode plate comprises:
a current collector and a film layer disposed on the current collector, wherein
the film layer comprises a first part and a second part disposed along a thickness direction of the film layer, the first part is disposed on the current collector, and the second part is disposed on the first part; and
the first part comprises a first active material, the second part comprises a second active material, the first active material comprises a first carbon-based material, the second active material comprises a second carbon-based material containing a coating layer, and a powder compaction density of the first active material is greater than a powder compaction density of the second active material.
2 . The negative electrode plate according to claim 1 , characterized in that the powder compaction density ρ 2 of the second active material under a pressure of 50000 N satisfies: 1.50 g/cc≤ρ 2 ≤2.00 g/cc.
3 . The negative electrode plate according to claim 1 , characterized in that a powder compaction density ρ 2-1 of the second carbon-based material under a pressure of 50000 N satisfies: 1.60 g/cc≤ρ 2-1 ≤1.95 g/cc.
4 . The negative electrode plate according to claim 1 , characterized in that the second carbon-based material comprises a primary particle.
5 . The negative electrode plate according to claim 1 , characterized in that the coating layer comprises amorphous carbon.
6 . The negative electrode plate according to claim 1 , characterized in that the second carbon-based material satisfies at least one of the following conditions (1) to (3):
(1) a specific surface area of the second carbon-based material is SSA 2 , 1.0 m 2 /g≤SSA 2 ≤3.0 m 2 /g;
(2) a volume median diameter of the second carbon-based material is D V 50 2 , 6.0 μm≤D V 50 2 ≤18.0 μm; or
(3) a gravimetric specific capacity of the second carbon-based material is C m2 , 345 mAh/g≤C m2 ≤360 mAh/g.
7 . The negative electrode plate according to claim 1 , characterized in that the powder compaction density ρ 1 of the first active material under a pressure of 50000 N satisfies: 1.70 g/cc≤ρ 1 ≤2.05 g/cc.
8 . The negative electrode plate according to claim 1 , characterized in that the powder compaction density ρ 1-1 of the first carbon-based material under a pressure of 50000 N satisfies: 1.80 g/cc≤ρ 1-1 ≤2.05 g/cc.
9 . The negative electrode plate according to claim 1 , characterized in that the first carbon-based material comprises micro-oxidized artificial graphite.
10 . The negative electrode plate according to claim 1 , characterized in that the first carbon-based material comprises a secondary particle.
11 . The negative electrode plate according to claim 10 , characterized in that, in the first carbon-based material, a number percentage n of the secondary particles satisfies: 70%≤n≤90%.
12 . The negative electrode plate according to claim 1 , characterized in that the first carbon-based material satisfies at least one of the following conditions (4) to (6):
(4) a specific surface area of the first carbon-based material is SSA 1 , 1.6 m 2 /g≤SSA 1 ≤3.5 m 2 /g;
(5) a volume median diameter of the first carbon-based material is D V 50 1 , 10.0 μm≤D V 50 1 ≤30.0 μm; or
(6) a gravimetric specific capacity of the first carbon-based material is C m1 , 350 mAh/g≤C m1 ≤365 mAh/g.
13 . The negative electrode plate according to claim 1 , characterized in that the first active material further comprises natural graphite.
14 . The negative electrode plate according to claim 13 , characterized in that a ratio of a mass m 2 of the natural graphite to a mass m 1 of the first active material satisfies: 0%<m 2 /m 1 ≤50%.
15 . The negative electrode plate according to claim 1 , characterized in that a ratio of a thickness h 1 of the first part to a thickness h of the film layer satisfies: 40%≤h 1 /h≤60%.
16 . The negative electrode plate according to claim 1 , characterized in that a ratio of a thickness h 2 of the second part to a thickness h of the film layer satisfies: 40%≤h 2 /h≤60%.
17 . A method for preparing a negative electrode plate, characterized in that the method comprises:
providing a current collector;
preparing a first part of a film layer on the current collector, wherein the first part comprises a first active material, and the first active material comprises a first carbon-based material;
preparing a second part of the film layer on the first part of the film layer, wherein the second part comprises a second active material, the second active material comprises a second carbon-based material containing a coating layer, and a powder compaction density of the first active material is greater than a powder compaction density of the second active material.
18 . A battery cell, characterized in that the battery cell comprises the negative electrode plate according to claim 1 .
19 . A battery, characterized in that the battery comprises the battery cell according to claim 18 .
20 . An electrical device, wherein the electrical device comprises the battery cell according to claim 18 .