Secondary battery and apparatus containing the same

1. A secondary battery, comprising an outer packaging film and an electrode assembly and an electrolyte accommodated in the outer packaging film, the electrode assembly comprising a positive electrode plate, a negative electrode plate and a separator, the positive electrode plate comprising a positive electrode current collector and a positive electrode membrane arranged on at least one surface of the positive electrode current collector and comprising a positive electrode active material, the negative electrode plate comprising a negative electrode current collector and a negative electrode membrane arranged on at least one surface of the negative electrode current collector and comprising a negative electrode active material, wherein the positive electrode active material is selected from at least one of a lithium-contained nickel cobalt manganese oxide or a lithium-contained nickel cobalt aluminum oxide, and the negative electrode active material comprises a silicon-based material and a carbon material;

and the secondary battery satisfies: −4≤2*√{square root over (C)}*C si *C si +0.1−L−F≤2,

C≥15 Ah, 25 cm≤L≤35 cm, 3 N/mm≤F≤9 N/mm;

wherein:

C— a rated capacity of the secondary battery, in Ah;

C si — a mass proportion of the silicon-based material in the negative electrode active material;

L— a projection length of the outer packaging film, in cm; and

F— a packaging strength of a packaging area of the outer packaging film, in N/mm.

2. The secondary battery according to claim 1 , wherein: −3.5≤2*√{square root over (C)}*C si *C si +0.1−L−F≤0.

3. The secondary battery according to claim 1 , wherein: 50 Ah≤C≤80 Ah.

4. The secondary battery according to claim 1 , wherein: 28 cm≤L≤32 cm.

5. The secondary battery according to claim 1 , wherein: 3 N/mm≤F≤8 N/mm.

6. The secondary battery according to claim 1 , wherein: the mass proportion of the silicon-based material in the negative electrode active material satisfies C si ≤40%.

7. The secondary battery according to claim 1 , wherein: a thickness T of the packaging area of the outer packaging film is 0.2 mm≤T≤0.4 mm.

8. The secondary battery according to claim 1 , wherein: a projection width W of the outer packaging film is 8.5 cm≤W≤11 cm.

9. The secondary battery according to claim 1 , wherein: the positive electrode active material is selected from 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 at least part of the surface provided with a coating layer, wherein, 0.8≤a≤1.2, 0.5≤b<1, 0<c<1, 0<d<1, 0≤e≤0.1, 1≤f≤2, 0≤g≤1, M is selected from one or more of Mn and Al, M′ is selected from one or more of Zr, Al, Zn, Cu, Cr, Mg, Fe, V, Ti and B, and A is selected from one or more of N, F, S and Cl.

10. The secondary battery according to claim 1 , wherein: at least part of the positive electrode active material comprises single crystal particles.

11. The secondary battery according to claim 1 , wherein: the silicon-based material is selected from one or more of elemental silicon, a silicon-oxygen compound, a silicon-carbon composite, a silicon-nitrogen compound and a silicon alloy.

12. The secondary battery according to claim 1 , wherein: the carbon material comprises one or more of graphite, soft carbon and hard carbon.

13. The secondary battery according to claim 1 , wherein: the silicon-based material is selected from one or more of elemental silicon, a silicon-oxygen compound, a silicon-carbon composite, a silicon-nitrogen compound and a silicon alloy;

and, the carbon material comprises one or more of graphite, soft carbon and hard carbon.

14. The secondary battery according to claim 1 , wherein: a volume average particle diameter D c50 of the positive electrode active material is from 8 μm to 15 μm.

15. The secondary battery according to claim 1 , wherein: a volume average particle diameter D a50 of the negative electrode active material is from 11 μm to 18 μm.

16. The secondary battery according to claim 1 , wherein: a volume average particle diameter D c50 of the positive electrode active material is from 8 μm to 15 μm;

and, a volume average particle diameter D a50 of the negative electrode active material is from 11 μm to 18 μm.

17. An apparatus, comprising:

a secondary battery, comprising an outer packaging film and an electrode assembly and an electrolyte accommodated in the outer packaging film, the electrode assembly comprising a positive electrode plate, a negative electrode plate and a separator, the positive electrode plate comprising a positive electrode current collector and a positive electrode membrane arranged on at least one surface of the positive electrode current collector and comprising a positive electrode active material, the negative electrode plate comprising a negative electrode current collector and a negative electrode membrane arranged on at least one surface of the negative electrode current collector and comprising a negative electrode active material, wherein the positive electrode active material is selected from at least one of a lithium-contained nickel cobalt manganese oxide or a lithium-contained nickel cobalt aluminum oxide, and the negative electrode active material comprises a silicon-based material and a carbon material;

and the secondary battery satisfies: −4≤2*√{square root over (C)}*C si *C si +0.1−L−F≤2,

C≥15 Ah, 25 cm≤L≤35 cm, 3 N/mm≤F≤9 N/mm;

wherein:

C— a rated capacity of the secondary battery, in Ah;

C si — a mass proportion of the silicon-based material in the negative electrode active material;

L—a projection length of the outer packaging film, in cm; and

F— a packaging strength of a packaging area of the outer packaging film, in N/mm.