Secondary battery and apparatus containing the secondary battery
This application discloses a secondary battery including a positive electrode plate and a negative electrode plate, wherein the positive electrode plate comprises a positive electrode current collector and a positive electrode film disposed on a surface of the positive electrode current collector and comprising a positive active material, the negative electrode plate comprises a negative electrode current collector and a negative electrode film disposed on a surface of the negative electrode current collector and comprising a negative active material. The positive active material comprises one or more of layered lithium transition metal oxides and modified compounds thereof, and a resistance R of the negative electrode plate satisfies: 6.0 mΩ≤R≤12.0 mΩ; or the positive active material comprises one or more of lithium-containing phosphates with olivine structure and modified compounds thereof, and a resistance R of the negative electrode plate satisfies: 3.0 mΩ≤R≤7.0 mΩ.
1. A secondary battery, comprising a positive electrode plate and a negative electrode plate, the positive electrode plate comprising a positive electrode current collector and a positive electrode film that is disposed on at least one surface of the positive electrode current collector and comprises a positive active material, the negative electrode plate comprising a negative electrode current collector and a negative electrode film that is disposed on at least one surface of the negative electrode current collector and comprises a negative active material,
wherein the positive active material comprises one or more of layered lithium transition metal oxides and layered lithium transition metal oxides are modified by doping and/or surface coating;
the negative active material comprises a first material and a second material, the first material comprises artificial graphite, the second material comprises natural graphite,
the natural graphite has a powder resistivity of from 10.0 mΩ·cm to 14.0 mΩ·cm under a pressure of from 8 MPa;
the artificial graphite has a powder resistivity of from 11.0 mΩ·cm to 16.0 mΩ·cm under a pressure of 8 MPa; and
the negative electrode plate has a resistance R satisfying 6 mΩ≤R≤12.0 mΩ.
2. The secondary battery according to claim 1 , wherein the natural graphite constitutes from 10% to 50% by mass of the negative active material.
3. The secondary battery according to claim 1 , wherein the negative active material has a volume average particle diameter Dv50 of from 11 μm to 15 μm.
4. The secondary battery according to claim 1 , wherein the negative active material has a graphitization degree of from 92% to 96%.
5. The secondary battery according to claim 1 , wherein the negative electrode film has an areal density of from 10 mg/cm 2 to 13 mg/cm 2 ; and/or
the negative electrode film has a compacted density of from 1.6 g/cm 3 to 1.8 g/cm 3 .
6. The secondary battery according to claim 1 , wherein the layered lithium transition metal oxide comprises one or more of lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide and modified compounds thereof.
7. The secondary battery according to claim 1 , wherein any two circular regions with a same area on the negative electrode plate are respectively denoted as a first region and a second region, and a distance between a center of the first region and the second region is 20 cm, and an electrode plate resistance R 1 of the first region and an electrode plate resistance R 2 of the second region satisfy: R 1 −R 2 /≤3.
8. An apparatus, comprising the secondary battery according to claim 1 .
9. The secondary battery according to claim 1 , wherein the natural graphite constitutes from 15% to 30% by mass of the negative active material.
10. The secondary battery according to claim 1 , wherein the natural graphite has a powder resistivity of from 11.0 mΩ·cm to 13.0 mΩ·cm under a pressure of from 8 MPa; and/or,
the artificial graphite has a powder resistivity of from 13.0 mΩ·cm to 15.0 mΩ·cm under a pressure of 8 MPa.
11. The secondary battery according to claim 1 , wherein the negative active material has a volume average particle diameter Dv50 of from 12 μm to 14 μm.
12. The secondary battery according to claim 1 , wherein the negative active material has a graphitization degree of from 93% to 95%.
13. The secondary battery according to claim 1 , wherein the negative electrode film has an areal density of from 10.5 mg/cm 2 to 11.5 mg/cm 2 ; and/or
the negative electrode film has a compacted density of from 1.65 g/cm 3 to 1.75 g/cm 3 .
14. A secondary battery, comprising a positive electrode plate and a negative electrode plate, the positive electrode plate comprising a positive electrode current collector and a positive electrode film disposed on at least one surface of the positive electrode current collector and comprises a positive active material, the negative electrode plate comprising a negative electrode current collector and a negative electrode film on at least one surface of the negative electrode current collector and comprises a negative active material,
wherein the positive active material comprises layered lithium transition metal oxide;
the negative active material comprises artificial graphite and natural graphite;
the natural graphite has a mass percentage from 10% to 30% based on a total mass of the negative active material, a powder resistivity of from 10.0 mΩ·cm to 14.0 mΩ·cm under a pressure of from 8 MPa, a Dv50 from 12.4 μm to 18.2 μm, and a graphitization degree of from 92.7% to 97.2%;
the artificial graphite has a powder resistivity of from 11.0 mΩ·cm to 16.0 mΩ·cm under a pressure of 8 MPa, a Dv50 from 10.5 μm to 15.5 μm, and a graphitization degree of from 96.5% to 98.1%; and
the negative electrode plate has a resistance R satisfying 6 mΩ≤R≤12 mΩ.
15. The secondary battery according to claim 1 , wherein a mass ratio of the artificial graphite to the natural graphite in the negative active material is 9:1 to 75:25.
16. The secondary battery according to claim 14 , wherein a mass ratio of the artificial graphite to the natural graphite in the negative active material is 9:1 to 75:25.