Secondary battery and preparation method thereof, and battery module, battery pack, and apparatus containing such secondary battery
Embodiments provide a secondary battery and a preparation method thereof, and a battery module, battery pack, and apparatus containing such secondary battery. In those embodiments, a negative electrode plate includes a negative-electrode current collector and a negative-electrode film layer that is disposed on at least one surface of the negative-electrode current collector and that includes a negative-electrode active material. The negative-electrode active material contains graphite, and the negative electrode plate satisfies that, when the negative electrode plate and a lithium metal sheet constitute a button battery which is discharged to 5.0 mV at 0.05 C, a capacity increment curve V-dQ/dV of the button battery has a third-order lithiation phase transition peak of graphite at position 0.055V-0.085V.
1. A lithium ion secondary battery, comprising a cathode, an anode, a separator, and an electrolyte, wherein the anode comprises a negative electrode plate, wherein the negative electrode plate comprises a negative-electrode current collector and a negative-electrode film layer that is disposed on at least one surface of the negative-electrode current collector and that comprises a negative-electrode active material, the negative-electrode active material containing graphite, wherein the graphite comprises artificial graphite, wherein a median particle size by volume D v 50 of the negative-electrode active material satisfies 8 μm≤D v 50≤16 μm, wherein an areal density (AD) of the negative-electrode film layer satisfies 0.09 kg/m 2 ≤AD≤0.117 kg/m 2 , wherein a press density (PD) of the negative-electrode film layer satisfies 1.53 g/m 3 ≤PD≤1.68 g/m 3 , wherein the negative electrode plate satisfies the following:
when the negative electrode plate and a lithium metal sheet constitute a button battery which is discharged to 5.0 millivolts (mV) at 0.05 Coulomb (C), a capacity increment curve V-dQ/dV of the button battery has a third-order lithiation phase transition peak of graphite at position 0.055 volts (V)-0.085V.
2. The secondary battery according to claim 1 , wherein the capacity increment curve V-dQ/dV has the third-order lithiation phase transition peak of graphite at position 0.057V-0.077V.
3. The secondary battery according to claim 1 , wherein a peak intensity of the third-order lithiation phase transition peak of graphite is −3 Ah/V/g to −15 Ah/V/g.
4. The secondary battery according to claim 1 , wherein the median particle size by volume D v 50 of the negative-electrode active material satisfies 9.5 μm≤D v 50≤14.5 μm.
5. The secondary battery according to claim 1 , wherein the areal density (AD) of the negative-electrode film layer satisfies 0.094 kg/m 2 ≤AD≤0.107 kg/m 2 .
6. The secondary battery according to claim 1 , wherein a mass percentage of the artificial graphite in the negative-electrode active material is ≥60%.
7. The secondary battery according to claim 1 , wherein the negative-electrode active material contains natural graphite; and wherein a mass percentage of the natural graphite in the negative-electrode active material is ≤40%.
8. The secondary battery according to claim 1 , wherein the negative-electrode active material comprises secondary particles; and wherein a number percentage of the secondary particles in the negative-electrode active material is ≥60%.
9. The secondary battery according to claim 1 , wherein a particle size uniformity of the negative-electrode active material is 0.3 to 0.4.
10. The secondary battery according to claim 1 , wherein the negative-electrode active material further satisfies one or more of the following:
(1) a particle size span (D v 90-D v 10)/D v 50 of the negative-electrode active material satisfies 1.0≤(D v 90-D v 10)/D v 50≤1.4;
(2) a degree of graphitization of the negative-electrode active material is 93% to 95%;
(3) a powder OI value of the negative-electrode active material is 2.5 to 4.5;
(4) a tap density of the negative-electrode active material is 0.8 g/m 3 to 1.2 g/m 3 ;
(5) a powder press density of the negative-electrode active material at a pressure of 30 kN is 1.65 g/m 3 to 1.85 g/m 3 ; and
(6) a gram capacity of the negative-electrode active material is 350 mAh/g to 360 mAh/g.
11. The secondary battery according to claim 1 , wherein the negative-electrode film layer satisfies one or more of the following:
(1) a porosity P of the negative-electrode film layer satisfies 25%≤P≤45%; and
(2) an adhesion F between the negative-electrode film layer and the negative-electrode current collector satisfies 4.5 N/m≤F≤15 N/m.
12. The secondary battery according to claim 1 , wherein the cathode comprises a positive electrode plate, the positive electrode plate comprising a positive-electrode current collector and a positive-electrode film layer that is disposed on at least one surface of the positive-electrode current collector and that comprises a positive-electrode active material, and the positive-electrode active material containing one or more of lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium iron phosphate, a composite material of lithium iron phosphate and carbon.
13. A battery module, comprising the secondary battery according to claim 1 .
14. A battery pack, comprising the battery module according to claim 13 .
15. The secondary battery according to claim 6 , wherein the mass percentage of the artificial graphite in the negative-electrode active material is 80% to 100%.
16. The secondary battery according to claim 7 , wherein the mass percentage of the natural graphite in the negative-electrode active material is 10% to 30%.
17. The secondary battery according to claim 8 , wherein the number percentage of the secondary particles in the negative-electrode active material is 80% to 100%.
18. The secondary battery according to claim 9 , wherein the particle size uniformity of the negative-electrode active material is 0.31 to 0.36.