Secondary battery and device containing same
This application discloses a secondary battery and a device containing the secondary battery. A positive active material of the secondary battery includes one or more of lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and a modified material thereof. A negative active material of the secondary battery includes a silicon-oxygen compound and graphite. A separator of the secondary battery includes a substrate and a coating layer. The secondary battery satisfies: 7.5 ≤ 3 4 6 0 E D - ( D 50 - D C 50 × 0.75 - T 18 ) ≤ 11.5 , where ED≥270 Wh/Kg, 11 μm≤D50≤18.5 μm, 11 μm≤D C 50≤20 μm. The secondary battery according to this application achieves relatively high cycle performance while achieving a relatively high energy density concurrently.
1 . A secondary battery, comprising a positive electrode plate, a negative electrode plate, and a separator, the positive electrode plate comprises a positive active material, the negative electrode plate comprises a negative active material, and the separator comprises a substrate and a coating layer which is selected from the group consisting of an inorganic particle coating layer and a polymer coating layer, wherein
the positive active material comprises one or more of lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, or a modified material thereof, wherein the modified material includes one or more of coating modified material and doping modified material;
the negative active material comprises a silicon-oxygen compound and graphite; and
the secondary battery satisfies:
7
.
5
≤
3
4
6
0
E
D
-
(
D
50
-
D
C
50
×
0.75
-
T
18
)
≤
11.5
,
where
270 Wh/Kg≤ED≤320 Wh/Kg, 11 μm≤D50≤18.5 μm, 11 μm≤D C 50≤20 μm, 5 μm≤T≤9 μm; and
ED is a weight energy density of the secondary battery, measured in units of Wh/Kg;
D50 is a volume average particle size of the negative active material, measured in units of μm,
D C 50 is a volume average particle size of the graphite, measured in units of μm, and
T is a thickness of the substrate of the separator, measured in units of μm.
2 . The secondary battery according to claim 1 , wherein the secondary battery satisfies:
8
≤
3
4
6
0
E
D
-
(
D
50
-
D
C
50
×
0.75
-
T
18
)
≤
10.5
.
3 . The secondary battery according to claim 1 , wherein the secondary battery further satisfies one or more of the following conditions (1) to (4):
(1) 15 μm≤D50≤18 μm;
(2) 13 μm≤D C 50≤20 μm;
(3) the volume average particle size D Si 50 of the silicon-oxygen compound satisfies 5 μm≤D Si 50≤12 μm; and
(4) a mass ratio of the silicon-oxygen compound to the graphite is 0.1 to 0.7.
4 . The secondary battery according to claim 3 , wherein the volume average particle size D Si 50 of the silicon-oxygen compound satisfies 6 μm≤D Si 50 ≤10 μm.
5 . The secondary battery according to claim 3 , wherein the mass ratio of the silicon-oxygen compound to the graphite is 0.2 to 0.4.
6 . The secondary battery according to claim 1 , wherein the separator has a porosity of from 35% to 45%.
7 . The secondary battery according to claim 6 , wherein the separator has a porosity of from 38% to 42%.
8 . The secondary battery according to claim 1 , wherein a total thickness T S of the separator satisfies: 10 μm≤T S ≤16 μm.
9 . The secondary battery according to claim 8 , wherein a total thickness Ts of the separator satisfies 11 μm≤Ts≤14 μm.
10 . The secondary battery according to claim 1 , wherein the negative active material comprising graphite is one or more selected from the group consisting of artificial graphite and natural graphite.
11 . The secondary battery according to claim 1 , wherein the positive active material comprises one or more of Li a Ni b Co c M d M′ e O f A g or Li a Ni b Co c M d M′ e O f A g with a coating layer coated on at least a part of the surface of the Li a Ni b Co c M d M′ e O f A g , wherein 0.8≤a≤1.2, 0.5≤b<1, 0<c<1, 0<d<1, 0≤e≤0.1, 1≤f≤2, and 0≤g≤1, M is one or more selected from the group of Mn and Al, M′ is one or more selected from the group of Zr, Al, Zn, Cu, Cr, Mg, Fe, V, Ti, and B, and A is one or more selected from the group of N, F, S, and Cl.
12 . The secondary battery according to claim 1 , wherein the positive active material comprises particles where at least some part of particles are monocrystal particles.
13 . The secondary battery according to claim 12 , wherein the positive active material has a volume average particle size D a 50 satisfying: 8 μm≤D a 50≤ 12 μm.
14 . The secondary battery according to claim 13 , wherein the positive active material has a volume average particle size D a 50 of satisfying: 9 μm≤D a 50 ≤11 μm.
15 . The secondary battery according to claim 1 , wherein 6 μm≤T≤9 μm.
16 . A device, comprising a secondary battery, wherein the secondary battery comprises a positive electrode plate, a negative electrode plate, and a separator, the positive electrode plate comprises a positive active material, the negative electrode plate comprises a negative active material, and the separator comprises a substrate and a coating layer which is selected from the group consisting of an inorganic particle coating layer and a polymer coating layer, wherein
the positive active material comprises one or more of lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, or a modified material thereof, wherein the modified material includes one or more of coating modified material and doping modified material;
the negative active material comprises a silicon-oxygen compound and graphite; and
the secondary battery satisfies:
7
.
5
≤
3
4
6
0
E
D
-
(
D
50
-
D
C
50
×
0.75
-
T
18
)
≤
11.5
,
where
270 Wh/Kg≤ED≤320 Wh/Kg, 11 μm≤D50≤18.5 μm, 11 μm≤D C 50≤20 μm, 5 μm≤T≤9 μm; and
ED is a weight energy density of the secondary battery, measured in units of Wh/Kg;
D50 is a volume average particle size of the negative active material, measured in units of μm,
D C 50 is a volume average particle size of the graphite, measured in units of μm, and
T is a thickness of the substrate of the separator, measured in units of μm.