POSITIVE ELECTRODE PIECE, BATTERY AND ELECTRONIC DEVICE

Abstract

The present application provides a positive electrode piece, a battery and an electric device. A first aspect of the present disclosure provides a positive electrode piece, the positive electrode piece includes a positive electrode current collector and a positive electrode active layer provided on at least one surface of the positive electrode current collector, and the positive electrode active layer includes a positive electrode active material; in a plane composed of a length direction and a thickness direction of the positive electrode piece, particles of the positive electrode active material have a longest distance a in the length direction of the positive electrode piece, and have a longest distance b in the thickness direction of the positive electrode piece, and in a region not less than 25 μm*25 μm, the number of the particles of the positive electrode active material meeting a/b≥3 is N, where N≥2.

Claims

1. A positive electrode piece, wherein the positive electrode piece comprises a positive electrode current collector and a positive electrode active layer provided on at least one surface of the positive electrode current collector, and the positive electrode active layer comprises a positive electrode active material; in a plane composed of a length direction and a thickness direction of the positive electrode piece, particles of the positive electrode active material have a longest distance a in the length direction of the positive electrode piece, and have a longest distance b in the thickness direction of the positive electrode piece, and in a region not less than 25 μm*25 μm, the number of the particles of the positive electrode active material meeting a/b≥3 is N, wherein N≥2.

2. The positive electrode piece according to claim 1, wherein the positive electrode active material is Li.sub.n−xNa.sub.xCo.sub.1−yMe.sub.yO.sub.2, 0.70≤n≤1, 0<x≤0.15, 0≤y≤0.15, and Me is selected from one or more of Al, Mg, Ti, Zr, Ni, Mn, Y, La, Sr, W, Sc, Ce, P, Nb, V, Ta, and Te.

3. The positive electrode piece according to claim 1, wherein X-ray diffraction pattern of the positive electrode active material has a peak 002 corresponding to a crystal plane 002, a peak 102 corresponding to a crystal plane 102, and a peak 103 corresponding to a crystal plane 103.

4. The positive electrode piece according to claim 3, wherein a diffraction angle 2θ of the crystal plane 002 is equal to 18.6°±0.5°, a diffraction angle 2θ corresponding to the peak 102 is equal to 41.7°±0.5°, and a diffraction angle 2θ corresponding to the peak 103 is equal to 47.1°±0.5°.

5. The positive electrode piece according to claim 1, wherein the X-ray diffraction pattern of the positive electrode active material has a peak 101 corresponding to a crystal plane 101 and a peak 004 corresponding to a crystal plane 004, and a peak intensity ratio of the peak 101 to the peak 004 is m, wherein m≥1.5.

6. The positive electrode piece according to claim 1, wherein a particle size of the positive electrode active material is 6-18 μm.

7. The positive electrode piece according to claim 1, wherein the positive electrode active material has a conductivity of ≥1E.sup.−4 S/cm under a force of ≥4 KN; and a compaction density of ≥3.75 g/cm.sup.3 under a force of ≥30 KN.

8. The positive electrode piece according to claim 1, wherein a compaction density of the positive electrode piece is ≥4.0 g/cm.sup.3.

9. A battery, comprising the positive electrode piece according to claim 1.

10. The battery according to claim 9, wherein the positive electrode active material is Li.sub.n−xNa.sub.xCo.sub.1−yMe.sub.yO.sub.2, 0.70≤n≤1, 0<x≤0.15, 0≤y≤0.15, and Me is selected from one or more of Al, Mg, Ti, Zr, Ni, Mn, Y, La, Sr, W, Sc, Ce, P, Nb, V, Ta, and Te.

11. The battery according to claim 9, wherein X-ray diffraction pattern of the positive electrode active material has a peak 002 corresponding to a crystal plane 002, a peak 102 corresponding to a crystal plane 102, and a peak 103 corresponding to a crystal plane 103.

12. The battery according to claim 11, wherein a diffraction angle 2θ of the crystal plane 002 is equal to 18.6°±0.5°, a diffraction angle 2θ corresponding to the peak 102 is equal to 41.7°±0.5°, and a diffraction angle 2θ corresponding to the peak 103 is equal to 47.1°±0.5.

13. The battery according to claim 9, wherein the X-ray diffraction pattern of the positive electrode active material has a peak 101 corresponding to a crystal plane 101 and a peak 004 corresponding to a crystal plane 004, and a peak intensity ratio of the peak 101 to the peak 004 is m, wherein m≥1.5.

14. The battery according to claim 9, wherein a particle size of the positive electrode active material is 6-18 μm.

15. The battery according to claim 9, wherein the positive electrode active material has a conductivity of ≥1E.sup.−4 S/cm under a force of ≥4 KN; and a compaction density of ≥3.75 g/cm.sup.3 under a force of ≥30 KN.

16. The battery according to claim 9, wherein a compaction density of the positive electrode piece is ≥4.0 g/cm.sup.3.

17. An electronic device, comprising the battery according to claim 9.

18. The electronic device according to claim 17, wherein the positive electrode active material is Li.sub.n−xNa.sub.xCo.sub.1−yMe.sub.yO.sub.2, 0.70≤n≤1, 0<x≤0.15, 0≤y≤0.15, and Me is selected from one or more of Al, Mg, Ti, Zr, Ni, Mn, Y, La, Sr, W, Sc, Ce, P, Nb, V, Ta, and Te.

19. The electronic device according to claim 17, wherein X-ray diffraction pattern of the positive electrode active material has a peak 002 corresponding to a crystal plane 002, a peak 102 corresponding to a crystal plane 102, and a peak 103 corresponding to a crystal plane 103.

20. The electronic device according to claim 19, wherein a diffraction angle 2θ of the crystal plane 002 is equal to 18.6°±0.5°, a diffraction angle 2θ corresponding to the peak 102 is equal to 41.7°±0.5°, and a diffraction angle 2θ corresponding to the peak 103 is equal to 47.1°±0.5.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0044] FIG. 1 is a CP-SEM diagram of a positive electrode piece provided by an example of the present disclosure.

DESCRIPTION OF REFERENCE NUMERALS

[0045] 100—positive electrode current collector;

[0046] 200—positive electrode active material.

DESCRIPTION OF EMBODIMENTS

[0047] In order to make the objectives, technical solutions and advantages of the present disclosure more clear, the following will describe the technical solutions in the examples of the present disclosure clearly and completely in combination with the examples of the present disclosure. Obviously, the described examples are part of the examples of the present disclosure, not all of them. Based on the examples of the present disclosure, all other examples obtained by those skilled in the art without creative work belong to the scope of the present disclosure.

[0048] Unless otherwise specified, experimental methods used in the following examples are conventional methods; reagents, materials, and the like used in the following examples can be obtained from commercial sources unless otherwise specified.

EXAMPLE 1

[0049] A preparation method of a positive electrode material provided in this example includes the following steps: [0050] (1) weigh 3.656 kg of sodium carbonate powder and 29.105 kg of cobalt nitrate hexahydrate powder, put them into a high-speed mixing device, mix them at 300 rpm for 3 minutes, mix them at 500 rpm for 5 minutes, mix them at 1000 rpm for 10 minutes, and then take out the mixture, and after confirming that there is no small white spot of white sodium carbonate in the mixture, it is considered that the mixture is uniform; [0051] (2) take 30 g of the mixture and put it into a ceramic crucible, conduct a high-temperature sintering using a well muffle furnace with device model of VBF-1200X with a temperature rise rate for sintering temperature rise curve of 5° C./min, conduct a constant temperature sintering for 10 hours when the temperature rises to 750° C., and naturally cool down to room temperature and take out the sample after sintering to obtain the sintered Na.sub.0.69CoO.sub.2, a compound containing cobalt and sodium; [0052] (3) add 200 ml of deionized water, 10.49 g of lithium hydroxide monohydrate and 10.59 g of lithium chloride into a reaction vessel, stir for 5 minutes at a water temperature of 78° C. and a rotating speed of 20 rpm, then weigh 10 g of Na.sub.0.69CoO.sub.2, the compound containing cobalt element and sodium element obtained in step 2, and keep them for continuous reaction at 78° C. and a rotating speed of 20 rpm for 8 hours; [0053] (4) after the reaction, take out the reaction product, conduct suction filtration washing with deionized water for three times, then dry it in an air drying oven at 90° C. for 8 hours to obtain the positive electrode material.

EXAMPLE 2

[0054] A preparation method of a positive electrode material provided in this example may refer to Example 1, the difference lies in that: [0055] (3) add 200 ml of deionized water, 10.49 g of lithium hydroxide monohydrate and 21.71 g of lithium bromide into a reaction vessel, stir for 5 minutes at a water temperature of 78° C. and a rotating speed of 20 rpm, then weigh 10 g of Na.sub.0.69CoO.sub.2, the compound containing cobalt element and sodium element obtained in step 2, and keep them for continuous reaction at 78° C. and a rotating speed of 20 rpm for 8 hours.

EXAMPLE 3

[0056] A preparation method of a positive electrode material provided in this example may refer to Example 1, the difference lies in that: [0057] (3) add 200 ml of deionized water, 10.49 g of lithium hydroxide monohydrate and 33.46 g of lithium iodide into a reaction vessel, stir for 5 minutes at a water temperature of 78° C. and a rotating speed of 20 rpm, then weigh 10 g of Na.sub.0.69CoO.sub.2, the compound containing cobalt element and sodium element obtained in step 2, and keep them for continuous reaction at 78° C. and a rotating speed of 20 rpm for 8 hours.

EXAMPLE 4

[0058] A preparation method of a positive electrode material provided in this example may refer to Example 1, the difference lies in that: [0059] (3) add 200 ml of deionized water, 10.49 g of lithium hydroxide monohydrate and 6.48 g of lithium fluoride into a reaction vessel, stir for 5 minutes at a water temperature of 78° C. and a rotating speed of 20 rpm, then weigh 10 g of Na.sub.0.69CoO.sub.2, the compound containing cobalt element and sodium element obtained in step 2, and keep them for continuous reaction at 78° C. and a rotating speed of 20 rpm for 8 hours.

EXAMPLE 5

[0060] A preparation method of a positive electrode material provided in this example may refer to Example 1, the difference lies in that: [0061] (3) add 200 ml of deionized water, 16.78 g of lithium hydroxide monohydrate and 3.69 g of lithium carbonate into a reaction vessel, stir for 5 minutes at a water temperature of 78° C. and a rotating speed of 20 rpm, then weigh 10 g of Na.sub.0.69CoO.sub.2, the compound containing cobalt element and sodium element obtained in step 2, and keep them for continuous reaction at 78° C. and a rotating speed of 20 rpm for 8 hours.

EXAMPLE 6

[0062] A preparation method of a positive electrode material provided in this example may refer to Example 1, the difference lies in that: [0063] (3) add 200 ml of deionized water, 16.78 g of lithium hydroxide monohydrate and 16.96 g of lithium chloride into a reaction vessel, stir for 5 minutes at a water temperature of 78° C. and a rotating speed of 20 rpm, then weigh 10 g of Na.sub.0.69CoO.sub.2, the compound containing cobalt element and sodium element obtained in step 2, and keep them for continuous reaction at 78° C. and a rotating speed of 20 rpm for 8 hours.

EXAMPLE 7

[0064] A preparation method of a positive electrode material provided in this example may refer to Example 1, the difference lies in that: [0065] (3) add 200 ml of deionized water, 16.78 g of lithium hydroxide monohydrate and 4.24 g of lithium chloride into a reaction vessel, stir for 5 minutes at a water temperature of 78° C. and a rotating speed of 20 rpm, then weigh 10 g of Na.sub.0.69CoO.sub.2, the compound containing cobalt element and sodium element obtained in step 2, and keep them for continuous reaction at 78° C. and a rotating speed of 20 rpm for 8 hours.

EXAMPLE 8

[0066] A preparation method of a positive electrode material provided in this example may refer to Example 1, the difference lies in that: [0067] (3) add 200 ml of deionized water, 10.49 g of lithium hydroxide monohydrate and 10.59 g of lithium chloride into a reaction vessel, stir for 5 minutes at a water temperature of 78° C. and a rotating speed of 30 rpm, then weigh 10 g of Na.sub.0.69CoO.sub.2, the compound containing cobalt element and sodium element obtained in step 2, and keep them for continuous reaction at 78° C. and a rotating speed of 30 rpm for 8 hours.

EXAMPLE 9

[0068] A preparation method of a positive electrode material provided in this example may refer to Example 1, the difference lies in that: [0069] (1) weigh 2.138 kg of sodium oxide powder and 29.105 kg of cobalt nitrate hexahydrate powder, put them into a high-speed mixing device, mix them at 300 rpm for 3 minutes, mix them at 500 rpm for 5 minutes, mix them at 1000 rpm for 10 minutes, and then take out the mixture, and after confirming that there is no small white spot of white sodium oxide in the mixture, it is considered that the mixture is uniform.

EXAMPLE 10

[0070] A preparation method of a positive electrode material provided in this example may refer to Example 1, the difference lies in that: [0071] (1) weigh 3.656 kg of sodium carbonate powder and 7.493 kg of cobalt monoxide powder, put them into a high-speed mixing device, mix them at 300 rpm for 3 minutes, mix them at 500 rpm for 5 minutes, mix them at 1000 rpm for 10 minutes, and then take out the mixture, and after confirming that there is no small white spot of white sodium oxide in the mixture, it is considered that the mixture is uniform.

EXAMPLE 11

[0072] A preparation method of a positive electrode material provided in this example may refer to Example 1, the difference lies in that: [0073] (1) weigh 3.656 kg of sodium carbonate powder and 9.293 kg of cobalt hydroxide powder, put them into a high-speed mixing device, mix them at 300 rpm for 3 minutes, mix them at 500 rpm for 5 minutes, mix them at 1000 rpm for 10 minutes, and then take out the mixture, and after confirming that there is no small white spot of white sodium carbonate in the mixture, it is considered that the mixture is uniform.

EXAMPLE 12

[0074] A preparation method of a positive electrode material provided in this example may refer to Example 1, the difference lies in that: [0075] (1) weigh 3.656 kg of sodium carbonate powder and 8.026 kg of tricobalt tetraoxide powder, put them into a high-speed mixing device, mix them at 300 rpm for 3 minutes, mix them at 500 rpm for 5 minutes, mix them at 1000 rpm for 10 minutes, and then take out the mixture, and after confirming that there is no small white spot of white sodium carbonate in the mixture, it is considered that the mixture is uniform.

EXAMPLE 13

[0076] A preparation method of a positive electrode material provided in this example may refer to Example 1, the difference lies in that: [0077] (1) weigh 3.656 kg of sodium carbonate powder, 9.200 kg of cobalt hydroxide powder and 50.98 g of nano aluminium oxide powder, put them into a high-speed mixing device, mix them at 300 rpm for 3 minutes, mix them at 500 rpm for 5 minutes, mix them at 1000 rpm for 10 minutes, and then take out the mixture, and after confirming that there is no small white spot of white sodium carbonate in the mixture, it is considered that the mixture is uniform.

EXAMPLE 14

[0078] A preparation method of a positive electrode material provided in this example may refer to Example 1, the difference lies in that: [0079] (1) weigh 3.656 kg of sodium carbonate powder, 9.014 kg of cobalt hydroxide powder and 152.94 g of nano aluminium oxide powder, put them into a high-speed mixing device, mix them at 300 rpm for 3 minutes, mix them at 500 rpm for 5 minutes, mix them at 1000 rpm for 10 minutes, and then take out the mixture, and after confirming that there is no small white spot of white sodium carbonate in the mixture, it is considered that the mixture is uniform.

EXAMPLE 15

[0080] A preparation method of a positive electrode material provided in this example may refer to Example 1, the difference lies in that: [0081] (1) weigh 3.656 kg of sodium carbonate powder, 8.828 kg of cobalt hydroxide powder and 254.9 g of nano aluminium oxide powder, put them into a high-speed mixing device, mix them at 300 rpm for 3 minutes, mix them at 500 rpm for 5 minutes, mix them at 1000 rpm for 10 minutes, and then take out the mixture, and after confirming that there is no small white spot of white sodium carbonate in the mixture, it is considered that the mixture is uniform.

EXAMPLE 16

[0082] A preparation method of a positive electrode material provided in this example may refer to Example 1, the difference lies in that: [0083] (1) weigh 3.656 kg of sodium carbonate powder, 9.200 kg of cobalt hydroxide powder and 40.30 g of nano magnesium oxide powder, put them into a high-speed mixing device, mix them at 300 rpm for 3 minutes, mix them at 500 rpm for 5 minutes, mix them at 1000 rpm for 10 minutes, and then take out the mixture, and after confirming that there is no small white spot of white sodium carbonate in the mixture, it is considered that the mixture is uniform;

EXAMPLE 17

[0084] A preparation method of a positive electrode material provided in this example may refer to Example 1, the difference lies in that: [0085] (1) weigh 3.656 kg of sodium carbonate powder, 9.014 kg of cobalt hydroxide powder and 120.91 g of nano magnesium oxide powder, put them into a high-speed mixing device, mix them at 300 rpm for 3 minutes, mix them at 500 rpm for 5 minutes, mix them at 1000 rpm for 10 minutes, and then take out the mixture, and after confirming that there is no small white spot of white sodium carbonate in the mixture, it is considered that the mixture is uniform.

EXAMPLE 18

[0086] A preparation method of a positive electrode material provided in this example may refer to Example 1, the difference lies in that: [0087] (1) weigh 3.656 kg of sodium carbonate powder, 8.828 kg of cobalt hydroxide powder and 201.52 g of nano magnesium oxide powder, put them into a high-speed mixing device, mix them at 300 rpm for 3 minutes, mix them at 500 rpm for 5 minutes, mix them at 1000 rpm for 10 minutes, and then take out the mixture, and after confirming that there is no small white spot of white sodium carbonate in the mixture, it is considered that the mixture is uniform.

EXAMPLE 19

[0088] A preparation method of a positive electrode material provided in this example may refer to Example 1, the difference lies in that: [0089] (1) weigh 2.138 kg of sodium oxide powder and 9.293 kg of cobalt hydroxide powder, put them into a high-speed mixing device, mix them at 300 rpm for 3 minutes, mix them at 500 rpm for 5 minutes, mix them at 1000 rpm for 10 minutes, and then take out the mixture, and after confirming that there is no small white spot of white sodium oxide in the mixture, it is considered that the mixture is uniform.

EXAMPLE 20

[0090] A preparation method of a positive electrode material provided in this example may refer to Example 1, the difference lies in that: [0091] (1) weigh 2.138 kg of sodium oxide powder, 9.200 kg of cobalt hydroxide powder and 50.98 g of nano aluminium oxide powder, put them into a high-speed mixing device, mix them at 300 rpm for 3 minutes, mix them at 500 rpm for 5 minutes, mix them at 1000 rpm for 10 minutes, and then take out the mixture, and after confirming that there is no small white spot of white sodium oxide in the mixture, it is considered that the mixture is uniform.

EXAMPLE 21

[0092] A preparation method of a positive electrode material provided in this example may refer to Example 1, the difference lies in that: [0093] (1) weigh 2.138 kg of sodium oxide powder, 9.014 kg of cobalt hydroxide powder and 152.94 g of nano aluminium oxide powder, put them into a high-speed mixing device, mix them at 300 rpm for 3 minutes, mix them at 500 rpm for 5 minutes, mix them at 1000 rpm for 10 minutes, and then take out the mixture, and after confirming that there is no small white spot of white sodium carbonate in the mixture, it is considered that the mixture is uniform.

EXAMPLE 22

[0094] A preparation method of a positive electrode material provided in this example may refer to Example 1, the difference lies in that: [0095] (1) weigh 2.138 kg of sodium oxide powder, 8.828 kg of cobalt hydroxide powder and 254.9 g of nano aluminium oxide powder, put them into a high-speed mixing device, mix them at 300 rpm for 3 minutes, mix them at 500 rpm for 5 minutes, mix them at 1000 rpm for 10 minutes, and then take out the mixture, and after confirming that there is no small white spot of white sodium oxide in the mixture, it is considered that the mixture is uniform.

COMPARATIVE EXAMPLE 1

[0096] A positive electrode material provided by this comparative example is conventional undoped lithium cobaltate, and its chemical composition is Li.sub.1.003CoO.sub.2, a preparation method thereof includes the following steps: [0097] (1) weigh lithium carbonate and conventional undoped spherical particles of Co.sub.3O.sub.4 purchased in the market in a molar ratio of Li:Co=100.3:100, mix the two substances at 300 rpm for 3 minutes, at 500 rpm for 5 minutes, and at 1000 rpm for 10 minutes using the same mixing device as the examples, and then take out the mixture, and after confirming that there is no small white spot of white lithium carbonate in the mixture, it is considered that the mixture is uniform; [0098] (2) take 30 g of the mixture and put it into a ceramic crucible, conduct a high-temperature sintering using a well muffle furnace with device model of VBF-1200X with a temperature rise rate for sintering temperature rise curve of 5° C./min, conduct a constant temperature sintering for 10 hours when the temperature rises to 1050° C., and naturally cool down to room temperature and take out the sample after sintering to obtain the sintered L.sub.1.003CoO.sub.2, a compound containing cobalt and lithium; [0099] (3) crush and grind the sintered lithium cobaltate, and then put the powder in muffle furnace again for sintering at 950° C. for 8 hours; crush the sintered product to obtain Li.sub.1.003CoO.sub.2 with D50 being 15.2 μm without any doping and coating.

COMPARATIVE EXAMPLE 2

[0100] A positive electrode material provided by this comparative example is doped and coated lithium cobaltate for high voltage, with its chemical composition being Li.sub.1.0028Co.sub.0.982Al.sub.0.014Mg.sub.0.002La.sub.0.002O.sub.2; [0101] a preparation method of the positive electrode material includes the following steps: [0102] (1) weigh lithium carbonate, conventional spherical Co.sub.3O.sub.4 particles doped with Al and La and purchased in the market and magnesium oxide particles in to a molar ratio of Li:Co:Mg=100.28:98.2:0.2, with stoichiometric ratio of the Co.sub.3O.sub.4 particles is Co:Al:La=98.2:1.4:0.2, mix the two substances at 300 rpm for 3 minutes, at 500 rpm for 5 minutes, and at 1000 rpm for 10 minutes using the same mixing device as the examples, and then take out the mixture, and after confirming that there is no small white spot of white lithium carbonate in the mixture, it is considered that the mixture is uniform; [0103] (2) take 30 g of the mixture and put it into a ceramic crucible, conduct a high-temperature sintering using a well muffle furnace with device model of VBF-1200X with a temperature rise rate for sintering temperature rise curve of 5° C./min, conduct a constant temperature sintering for 10 hours when the temperature rises to 1030° C., and naturally cool down to room temperature and take out the sample after sintering to obtain the sintered Li.sub.1.0028Co.sub.0.982Al.sub.0.014Mg.sub.0.002La.sub.0.002O.sub.2, a compound containing cobalt and lithium; [0104] (3) crush and grind the sintered lithium cobaltate, weigh it and titanium dioxide in a molar ratio of Co:Ti=98.2:0.2, then put the two substances into a high-speed mixing device, set a mixing procedure, mix them at 300 rpm for 3 minutes, mix them at 500 rpm for 5 minutes, mix them at 1000 rpm for 10 minutes, and then take out the mixture; put the powder in the muffle furnace again for sintering at 950° C. for 8 hours, and then crush the sintered product to obtain Li.sub.1.0028Co.sub.0.982Al.sub.0.014Mg.sub.0.002La.sub.0.002Ti.sub.0.002O.sub.2, a doped and coated lithium cobaltate material for high voltage, with D50 of 14.8 μm.

COMPARATIVE EXAMPLE 3

[0105] A preparation method of a positive electrode material provided in this comparative example may refer to Example 1, the difference lies in that: [0106] (3) weigh 10.49 g of lithium hydroxide monohydrate, 10.59 g of lithium chloride and 10 g of Na.sub.0.69CoO.sub.2, the compound containing cobalt and sodium obtained in step 2, add them into a mixer, mix them evenly and sinter them at high temperature of 300° C. for 5 hours.

COMPARATIVE EXAMPLE 4

[0107] A preparation method of a positive electrode material provided in this comparative example may refer to Example 1, the difference lies in that: [0108] (3) weigh 10.49 g of lithium hydroxide monohydrate, 10.59 g of lithium chloride and 10 g of Na.sub.0.69CoO.sub.2, the compound containing cobalt and sodium obtained in step 2, add them into a mixer, mix them evenly and sinter them at high temperature of 250° C. for 5 hours.

[0109] XRD tests, conductivity tests and compaction density tests are carried out on the positive electrode materials provided by Examples 1-22 and Comparative Examples 1-4. The test results of crystal plane diffraction angle, peak intensity ratio, conductivity and compaction density obtained by the XRD tests are shown in Table 1:

TABLE-US-00001 TABLE 1 Test results of the positive electrode active materials provided by Examples 1-22 and Comparative Examples 1-4 Peak intensity ratio of Powder crystal compaction plane 101/ Powder density 2θ value of 2θ value of 2θ value of crystal conductivity under crystal plane crystal plane crystal plane plane 004 under 8KN 30KN 002 (°) 102 (°) 103 (°) (m) (S/cm) (g/cm.sup.3) Example 1  18.5937 41.7818 47.139 1.799 2.32E.sup.−02 3.84 Example 2  18.62 41.7687 47.0864 2.018 3.72E.sup.−02 3.91 Example 3  18.6069 41.703 47.0733 3.427 5.05E.sup.−02 3.89 Example 4  18.5675 41.6768 47.0208 3.889 6.63E.sup.−02 3.92 Example 5  18.5675 41.6768 47.0208 4.086 2.90E.sup.−03 3.94 Example 6  18.5806 41.6899 47.047 2.81 5.74E.sup.−03 3.86 Example 7  18.5675 41.703 47.0339 4.604 9.27E.sup.−03 3.98 Example 8  18.5675 41.6899 47.047 1.833 1.30E.sup.−02 3.96 Example 9  18.5675 41.6899 47.047 2.805 2.16E.sup.−02 3.98 Example 10 18.5543 41.6768 47.0208 1.695 3.93E.sup.−02 3.89 Example 11 18.5543 41.6636 47.0208 2.585 5.89E.sup.−02 3.87 Example 12 18.5806 41.6899 47.0339 2.162 7.91E.sup.−02 3.88 Example 13 18.5806 41.703 47.047 2.965 1.50E.sup.−02 3.90 Example 14 18.5806 41.6899 47.0339 3.348 2.20E.sup.−02 3.85 Example 15 18.5675 41.703 47.0339 4.538 3.10E.sup.−02 3.89 Example 16 18.5806 41.703 47.047 2.103 3.98E.sup.−02 3.91 Example 17 18.5675 41.703 47.0208 4.356  1.722E.sup.−02 3.92 Example 18 18.5675 41.6899 47.0208 5.349 7.94E.sup.−03 3.94 Example 19 18.5675 41.6899 47.047 2.535 1.02E.sup.−02 3.93 Example 20 18.5675 41.6768 47.0339 3.578 1.12E.sup.−02 3.92 Example 21 18.5543 41.6899 47.0339 5.76 1.80E.sup.−02 3.92 Example 22 18.5543 41.6899 47.0208 6.862 7.94E.sup.−03 3.90 Comparative No No No / 4.68E.sup.−07 3.74 Example 1 characteristic characteristic characteristic peak peak peak Comparative No No No / 5.93E.sup.−07 3.75 Example 2 characteristic characteristic characteristic peak peak peak Comparative 18.5825 41.6885 47.0338 1.459 3.38E.sup.−03 3.56 Example 3 Comparative 18.5782 41.6977 47.0309 1.363 3.11E.sup.−03 3.44 Example 4

[0110] According to the data in Table 1, compared with Comparative Examples 1-2, the positive electrode active materials provided by the present disclosure have characteristic peaks corresponding to the crystal plane 002, the crystal plane 102 and the crystal plane 103, and the conductivity is ≥1E.sup.−4 S/cm under a force of 8 KN, and the compaction density is ≥3.75 g/cm.sup.3 under a force of 30 KN, which shows that the positive electrode active materials provided by the present disclosure have better discharge gram capacity, structural stability and conductivity. Meanwhile, the positive electrode active materials provided by the present disclosure are easy to be compacted, which is helpful to improve the compaction density of a positive electrode piece.

[0111] According to the XRD data provided by Examples 1-12 in Table 1, different raw materials and their ratios have a certain influence on phase peak position and the peak intensity of the positive electrode materials; it can be seen according to the XRD data provided by Examples 13-22 that with an increase of doped element content, the peak intensity ratio of crystal plane 101 to crystal plane 004 in the positive electrode materials increases significantly; it can be seen according to the Comparative Examples 3-4 that the peak intensity ratio m of the crystal plane 101 and the crystal plane 004 in the positive electrode materials prepared according to the solution method provided by the present disclosure is significantly increased compared with an ion exchange reaction by the means of sintering.

[0112] Button cell capacities of the positive electrode active materials prepared from Examples 1-22 and Comparative Examples 1-4 are tested. A preparation method of a button cell is as follows: mix the positive electrode active material with conductive carbon black (SP) and PVDF in a weight ratio of 8:1:1, disperse them in a solvent to obtain a positive electrode active layer slurry, coat the slurry on an aluminum foil current collector, and roll to prepare a positive electrode piece; then, punch the positive electrode piece with a die to obtain small round pieces with a diameter of 12 mm, conduct drying treatment and weighing treatment, then assemble the button cell by a button cell shell of type 2025, a Li metal round piece as the negative electrode, and conventional high voltage lithium cobaltate electrolyte in a glove box under Ar protective atmosphere. After the button cell is made, it is left to stand for 4 hours in a normal environment, and then a first charge and discharge capacity test is carried out, with the test conditions as below: charging to 4.5V at 0.1 C, charging to 0.025 C at constant voltage, and cutting off to stand for 3 minutes, then discharging to 3.0V at 0.1 C. The first discharge gram capacity C0 mAh/g is recorded, and at the same time, a discharge gram capacity within the range from the beginning of discharge to the cut-off voltage 4.4V is defined as C1 mAh/g, the gram capacity discharged within discharge voltage range of 3.8V-3.7V in the discharge capacity is defined as C2 mAh/g, and C1/C0 and C2/C0 are calculated. The results are shown in Table 2.

[0113] The positive electrode active materials provided according to Examples 1-22 and Comparative Examples 1-2 are mixed, after a certain amount of amplification, with conductive carbon black and PVDF in a weight ratio of 96:2:2, dispersed in a solvent to prepare a positive electrode active layer slurry, the slurry is coated on a surface of a positive electrode aluminum current collector, rolled according to the compaction density shown in Table 2 to prepare the positive electrode piece, which is treated with CP and then is subjected to SEM imaging test, and the number N of particles of the positive electrode active material with a/b≥3 is counted at a magnification of 5000 (i.e., sampling region is 25 μm*25 μm). The statistical results are shown in Table 2.

[0114] The positive electrode piece, a negative electrode piece, a separator and electrolyte are assembled to obtain a lithium ion battery, where a preparation method of the negative electrode piece includes: mixing artificial graphite, styrene butadiene rubber (SBR), sodium carboxymethylcellulose and conductive carbon black in a weight ratio of 94:3:2:1, dispersing the mixture in water and mixing by revolution-rotation mixing equipment, to obtain a negative electrode active layer slurry, and coat the slurry on a negative electrode copper current collector to obtain the negative electrode piece; [0115] the electrolyte includes an organic solvent an additive, and the organic solvent includes ethylene carbonate (EC), diethyl carbonate (DEC), propylene carbonate (PC) and fluoroethylene carbonate (FEC), and the additive has the following structure:

##STR00002##

then cycle performance of the lithium ion battery is tested. The cycle performance test process is as follows: at 25° C., charge to 4.50V at a constant current with a charge rate of 1 C, then charge to 4.50V at a constant voltage with a charge rate of 0.05 C, and then discharge to 3.0V at a discharge rate of 1 C. This charge and discharge cycle is repeated for 500 times. A discharge capacity at the first cycle and a discharge capacity at the 500th cycle are determined, to calculate capacity retention rate after the cycles: capacity retention rate after cycles=(discharge capacity at the 500th cycle)/(discharge capacity at the first cycle)*100%. The results are shown in Table 2.

TABLE-US-00002 TABLE 2 Performance test results of the positive electrode pieces and the lithium ion batteries assembled according to Examples 1-22 and Comparative Examples 1-4 First Compaction discharge Capacity density of gram retention positive capacity rate after electrode for button 500 cycles piece cell C0 for full Group (g/cm.sup.3) Value N (mAh/g) C1/C0 C2/C0 battery Example 1 4.23 3 201.2 11.30% 29.60% 85.30% Example 2 4.29 2 200.7 10.90% 29.90% 85.83% Example 3 4.18 3 200.3 10.30% 30.20% 84.97% Example 4 4.25 4 201.4 11.10% 29.70% 86.56% Example 5 4.3 3 202.5 11.90% 29.60% 86.02% Example 6 4.28 2 202 12.20% 30.10% 84.83% Example 7 4.19 3 199.8 12.60% 31.50% 86.39% Example 8 4.21 4 201.3 11.50% 28.90% 83.98% Example 9 4.35 3 201 11.30% 29.80% 85.76% Example 10 4.24 4 200.8 12.10% 30.05% 86.13% Example 11 4.32 3 202.3 10.85% 31.06% 85.93% Example 12 4.22 2 201.4 12.30% 29.45% 86.77% Example 13 4.26 4 199.5 11.70% 30.64% 87.81% Example 14 4.29 5 198.4 12.34% 31.47% 88.34% Example 15 4.3 5 197.4 12.98% 32.05% 88.76% Example 16 4.22 4 200 11.87% 29.86% 86.98% Example 17 4.26 5 198.7 12.48% 30.96% 87.44% Example 18 4.2 6 198 13.13% 31.07% 88.65% Example 19 4.26 3 201.4 11.59% 29.64% 84.86% Example 20 4.25 4 199.9 11.78% 29.63% 86.76% Example 21 4.27 4 199.1 12.18% 30.32% 87.95% Example 22 4.22 5 198.4 13.04% 31.05% 88.35% Comparative 4.1 0 195.4  6.54%  0.46% 56.32% Example 1 Comparative 4.12 0 187.8  5.87%  0.52% 78.42% Example 2 Comparative 3.89 0 189.6  9.08% 24.89% 79.45% Example 3 Comparative 3.92 0 190.4  8.17% 24.68% 78.87% Example 4

[0116] It can be seen from Table 2 that the positive electrode pieces prepared according to the positive electrode active materials provided by the present disclosure are suitable for higher compaction density, which is benefit from the accordion stacking structure in the positive electrode pieces, the particle number N meeting a/b≥3 in the same region is also significantly increased, which indicates that particle regularity of the positive electrode active material is improved, and with the increase of content of the doped elements, the number of the particles meeting this condition is significantly increased. It can be seen from Examples 13-22 that, with the increase of the content of the doped elements in the positive electrode active material, the number N of the particles is also increased, indicating that the particle regularity increases significantly, which is helpful to improve the cycle performance of lithium ion batteries.

[0117] It can be seen from Table 2 that the gram capacity of the positive electrode active material provided by the present disclosure has significantly increased, specifically, C1/C0≥9%, C2/C0≥25%, which indicates that the positive electrode active material with a particular structure provided by the present disclosure has more charging and discharging platforms and higher gram capacity play. In addition, based on lower platform voltage and better structural stability of the positive electrode active material, the lithium ion batteries have capacity retention rate of 80% or more after 500 cycles, and have good cycle performance at high voltage.

[0118] To sum up, the positive electrode active material provided by the present disclosure can enable the lithium ion battery to have high discharge gram capacity and excellent cycle performance at high voltage, and can meet people's thinning demand for lithium ion batteries.

[0119] Finally, it should be noted that the above examples are only used to illustrate the technical solution of the present disclosure, not to limit it; although the present disclosure has been described in detail with reference to the above-mentioned examples, those skilled in the art should understand that they can still modify the technical solutions recited in the above-mentioned examples, or replace equivalently some or all of the technical features therein; however, these modifications or replacements do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the examples of the present disclosure.