Positive electrode sheet and lithium-ion battery using same

Abstract

The present application provides a positive electrode sheet and a lithium-ion battery using same. The positive electrode sheet comprises a current collector and a positive electrode active coating comprising a positive electrode active material. The positive electrode active material comprises at least three of particles N1, particles N2, particles N3, particles N4, and particles N5, wherein particles N1 are a positive electrode active material having a particle size of not more than 100 nm, particles N2 are a positive electrode active material having a particle size of 100-150 nm, particles N3 are a positive electrode active material having a particle size of 150-250 nm, particles N4 are a positive electrode active material having a particle size of 250-500 nm, and particles N5 are a positive electrode active material having a particle size of more than 500 nm. In the positive electrode active material, upon calculation on the basis of mass ratio, the ratio of particles N1 is X1, the ratio of particles N2 is X2, the ratio of particles N3 is X3, the ratio of particles N4 is X4, and the ratio of particles N5 is X5; and a normalization function is obtained by means of performing power normalization on X1, X2, X3, X4 and X5, and R2 corresponding to the normalization function is more than or equal to 0.9. The positive electrode sheet has both a relatively high compaction density and good lithium-ion transport performance.

Claims

1. A positive electrode sheet, comprising a current collector and a positive electrode active coating containing a positive electrode active material, wherein the positive electrode active material comprises at least three of particles N1, N2, N3, N4, and N5, wherein particle N1 is a positive electrode active material with a particle size not exceeding 100 nm, particle N2 is a positive electrode active material with a particle size of 100-150 nm, particle N3 is a positive electrode active material with a particle size of 150-250 nm, particle N4 is the aforementioned positive electrode active material with a particle size of 250-500 nm, and particle N5 is the positive electrode active material with a particle size exceeding 500 nm; In the positive electrode active material, based on mass percentage, the proportion of particle N1 is X1, the proportion of particle N2 is X2, the proportion of particle N3 is X3, the proportion of particle N4 is X4, and the proportion of particle N5 is X5. A normalization function is obtained by performing power-law normalization on X1, X2, X3, X4, and X5. The corresponding R of the normalization function is... 2 ≥0.

9.

2. The positive electrode as described in claim 1, wherein, The normalization equation satisfies the coefficient of determination R. 2 ≥0.

99.

3. The positive electrode as described in claim 1, wherein: Let Y represent the normalization function, Y = aX 3 +bX 2 +cX+d; Y satisfies that at least one of a, b, and c is not 0.

4. The positive electrode as described in claim 3, wherein: In the normalization function, the value of a ranges from -0.1 to 0.1, the value of b ranges from -0.5 to 0.5, the value of c ranges from -1.0 to 1.0, and the value of d ranges from -0.97 to 0.

97.

5. The positive electrode as described in claim 1, wherein, The positive electrode active material includes at least four of the following: particles N1, N2, N3, N4, and N5.

6. The positive electrode as described in claim 5, wherein, Based on mass percentage, the total proportion of particles N1, N2, N3, and N4 in the positive electrode active material is not less than 60%.

7. The positive electrode as described in claim 6, wherein, The positive electrode active material includes particles N1, N2, N3, and N4.

8. The positive electrode as described in claim 7, wherein, Calculated as a percentage by mass: The proportion of particles N1 in the positive electrode active material is 5%~15%; The proportion of N2 particles in the positive electrode active material is 20%~40% (X2); The proportion of the N3 particles in the positive electrode active material is 25%~40%; The proportion of particles N4 in the positive electrode active material is 10%~40%; The proportion of particles N5 in the positive electrode active material is 0%~15%.

9. The positive electrode sheet according to any one of claims 1 to 8, wherein: The positive electrode active material includes a phosphate material, the general formula of which is Li. 1+x Fe y M z P α O β Where -0.05≤x≤0.15; 0.95≤y+z≤1.0, y≠0, 0.98≤α≤1.0, 3.95≤β≤4.0, and M includes at least one of Mn, Al, Mg, Ti, and Na.

10. The positive electrode as described in claim 9, wherein: The positive electrode active material includes a phosphate composite material, which includes a core containing the phosphate material and an outer coating layer covering the core. The outer coating layer contains Me and / or C elements, wherein the Me element is selected from at least one of Fe, Mn, Al, Mg, Ti, and Na elements.

11. A lithium-ion battery, wherein: The lithium-ion battery includes the positive electrode sheet as described in any one of claims 1 to 10.

12. The lithium-ion battery of claim 11, wherein: The compaction density of the positive electrode active coating is 2.55~2.85 g / cm³. 3 .

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