A positive electrode material, a positive electrode sheet including the same, and a battery

Abstract

The application belongs to the technical field of batteries, and particularly relates to a positive electrode material, a positive electrode sheet comprising the positive electrode material and a battery. x1 Na y1 Co 1‑ z1 M 1 z1 O2·beta Li a (Ni x2 Co y2 Mn 1‑x2‑y2‑z2 M 2 z2 )O2, wherein the positive electrode material has only one characteristic diffraction peak in the range of 18-19 degrees of 2theta diffraction angle in an X-ray diffraction pattern, and a lithium-nickel mixed arrangement ratio is less than 3%, and the positive electrode material has good structural stability at a high voltage, thereby improving the cycle performance of a lithium ion battery at a high voltage.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of batteries, and particularly relates to a positive electrode material, a positive electrode sheet comprising the positive electrode material and a battery. BACKGROUND

[0002] With the development of science and the improvement of lithium ion battery technology, higher and higher requirements are put forward for the capacity of lithium ion batteries. In order to improve the capacity of lithium ion batteries, an important way is to improve the charge-discharge voltage. However, the positive electrode material of the lithium ion battery will be unstable in structure, irreversible phase transition will occur, the capacity will rapidly decay, and the cycle performance will rapidly decrease at high voltage due to high Li extraction. SUMMARY

[0003] In order to improve the deficiencies of the prior art, the purpose of the present application is to provide a positive electrode material, a positive electrode sheet comprising the positive electrode material and a battery. The positive electrode material can maintain structural stability at high voltage, reduce capacity decay, and improve the cycle performance and rate performance of the lithium ion battery composed of the positive electrode material.

[0004] The purpose of the present application is achieved by the following technical solutions:

[0005] A positive electrode material, the chemical formula of the positive electrode material is

[0006] alpha Li x1 Na y1 Co 1-z1 M 1 z1 O2.beta Li a (Ni x2 Co y2 Mn 1-x2-y2-z2 M 2 z2 )O2, wherein 0<beta<alpha<1, and

[0007] alpha+beta=1; 0.9 1 is at least one of Al, Mg, Ti, Mn, Zr, B, P, Te, Nb, W, La, Y; 0.3 2 is at least one of Al, Mg, Ti, Zr, B, Te, Nb, W, Si, and the X-ray diffraction pattern of the positive electrode material has only one characteristic diffraction peak in the range of 18°-19° of 2 theta diffraction angle.

[0008] According to an embodiment of the present application, the half-peak width of the characteristic diffraction peak of the positive electrode material at a 2θ diffraction angle in the range of 18° to 19° in the X-ray diffraction pattern of the positive electrode material is greater than or equal to 0.15, preferably greater than or equal to 0.15 and less than or equal to 0.20.

[0009] According to an embodiment of the present application, the positive electrode material has an O2 phase stacking structure.

[0010] According to an embodiment of the present application, the (101) crystal face characteristic diffraction peak of the positive electrode material exists in the range of 38.10° to 38.20° at a 2θ diffraction angle in the X-ray diffraction pattern of the positive electrode active material.

[0011] According to an embodiment of the present application, the (103) crystal face characteristic diffraction peak of the positive electrode material exists in the range of 46.90° to 47.00° at a 2θ diffraction angle in the X-ray diffraction pattern of the positive electrode active material.

[0012] According to an embodiment of the present application, the (104) crystal face characteristic diffraction peak of the positive electrode material exists in the range of 46.20° to 46.30° at a 2θ diffraction angle in the X-ray diffraction pattern of the positive electrode active material.

[0013] According to an embodiment of the present application, the positive electrode material satisfies at least one of the following relationships:

[0014] 0.9 < I1 / I3 < 3.8;

[0015] 1.1 < I2 / I3 < 4.8;

[0016] wherein I1 is the peak intensity of the (101) crystal face characteristic diffraction peak of the positive electrode material; I2 is the peak intensity of the (103) crystal face characteristic diffraction peak of the positive electrode material; and I3 is the peak intensity of the (104) crystal face characteristic diffraction peak of the positive electrode material.

[0017] According to an embodiment of the present application, the average particle size of the positive electrode material is 5 μm to 20 μm.

[0018] According to an embodiment of the present application, the lithium-nickel mixing ratio of the positive electrode material is less than 3%.

[0019] Preferably, the lithium-nickel mixing ratio of the positive electrode material is less than 3% after XRD refinement.

[0020] The present application also provides a positive electrode sheet comprising the positive electrode material described above.

[0021] The present application also provides a battery comprising the positive electrode material described above, or the battery comprising the positive electrode sheet described above.

[0022] According to an embodiment of the present application, the charge cut-off voltage of the battery is greater than or equal to 4.5V.

[0023] Advantages of the present application:

[0024] The positive electrode material provided by the present application has good structural stability at high voltage, reduces capacity decay, and improves the cycle performance and rate performance of a lithium ion battery composed of the positive electrode material. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 XRD pattern of the positive electrode material in Example 1.

[0026] Figure 2 SEM pattern of the positive electrode material in Example 1.

[0027] Figure 3 dQ / dV curve of the positive electrode material in Example 1 and Comparative Example 1.

[0028] Figure 4 Cycle capacity retention curve of the battery in Example 1 and Comparative Example 1.

[0029] Figure 5 XRD pattern of the positive electrode material in Comparative Example 2.

[0030] Figure 6 XRD pattern of the positive electrode material in Comparative Example 3. DETAILED DESCRIPTION

[0031] As described above, the present application provides a positive electrode material, the chemical formula of the positive electrode material is αLi x1 Na y1 Co 1- z1 M 1 z1 O2·βLi a (Ni x2 Co y2 Mn 1-x2-y2-z2 M 2 z2 )O2, wherein 0<β<α<1, and α+β=1; 0.9<a<1.1, 0.8<x1<1, 0<y1<0.05, 0≤z1<0.1, M 1 is at least one of Al, Mg, Ti, Mn, Zr, B, P, Te, Nb, W, La, Y; 0.3≤x2≤0.8, 0.05≤y2≤0.3, 0.6≤x2+y2≤0.9, 0≤z2<0.1, M 2at least one of Al, Mg, Ti, Zr, B, Te, Nb, W, Si, and the positive electrode material has only one characteristic diffraction peak in the range of 18° to 19° in a 2θ diffraction angle of an X-ray diffraction pattern of the positive electrode material.

[0032] According to an embodiment of the present application, the content of Li element in the positive electrode material can fluctuate within a range. Exemplarily, the chemical formula of the positive electrode material is αLi x1 Na y1 Co 1-z1 M 1 z1 O2·βLi a (Ni x2 Co y2 Mn 1-x2-y2-z2 M 2 z2 )O2, wherein 0.9 < a < 1.1, 0.8 < x1 < 1.

[0033] According to an embodiment of the present application, M 1 elements and M 2 elements can improve the structural stability of the positive electrode material, but when the content of the doping elements is too high, it can cause excessive capacity loss. Within the range defined in the present application (0 ≤ z1 < 0.1, 0 ≤ z2 < 0.1), the structural stability can be improved while ensuring the capacity.

[0034] According to an embodiment of the present application, 0.6 ≤ α < 1 (such as 0.7, 0.8, 0.9 or 0.95), 0 < β ≤ 0.4 (such as 0.05, 0.1, 0.2 or 0.3).

[0035] According to an embodiment of the present application, the half-peak width of the characteristic diffraction peak in the range of 18° to 19° in the 2θ diffraction angle of the X-ray diffraction pattern of the positive electrode material is greater than or equal to 0.15.

[0036] According to an embodiment of the present application, the half-peak width of the characteristic diffraction peak in the range of 18° to 19° in the 2θ diffraction angle of the X-ray diffraction pattern of the positive electrode material is greater than or equal to 0.15 and less than or equal to 0.20.

[0037] According to an embodiment of the present application, the positive electrode material has an O2 phase stacking structure.

[0038] According to an embodiment of the present application, the positive electrode active material has a (101) crystal face characteristic diffraction peak of the positive electrode material in the range of 38.10° to 38.20° in the 2θ diffraction angle of the X-ray diffraction pattern.

[0039] According to an embodiment of the present application, the (103) crystal face characteristic diffraction peak of the positive electrode material exists in the X-ray diffraction pattern of the positive electrode active material at a 2θ diffraction angle in the range of 46.90°-47.00°.

[0040] According to an embodiment of the present application, the (104) crystal face characteristic diffraction peak of the positive electrode material exists in the X-ray diffraction pattern of the positive electrode active material at a 2θ diffraction angle in the range of 46.20°-46.30°.

[0041] According to an embodiment of the present application, the positive electrode material satisfies at least one of the following relationships:

[0042] 0.9<I1 / I3<3.8;

[0043] 1.1<I2 / I3<4.8;

[0044] wherein I1 is the peak intensity of the (101) crystal face characteristic diffraction peak of the positive electrode material; I2 is the peak intensity of the (103) crystal face characteristic diffraction peak of the positive electrode material; and I3 is the peak intensity of the (104) crystal face characteristic diffraction peak of the positive electrode material.

[0045] According to an embodiment of the present application, when the positive electrode material satisfies 0.9<I1 / I3<3.8; 1.1<I2 / I3<4.8, the positive electrode material has good structural stability and excellent cycle performance at high voltage. When the positive electrode material does not satisfy 0.9<I1 / I3<3.8; 1.1<I2 / I3<4.8, the structural stability of the positive electrode material decreases, and the cycle performance of the battery deteriorates.

[0046] According to an embodiment of the present application, the average particle size of the positive electrode material is 5 μm-20 μm. When the average particle size is too small, the side reaction with the electrolyte increases, resulting in a decrease in cycle performance. When the average particle size is too large, the rate performance is affected.

[0047] According to an embodiment of the present application, the maximum voltage platform range in the charge curve of the positive electrode material is 3.75-3.8 V, and the maximum voltage platform range in the discharge curve is 3.7-3.75 V.

[0048] According to an embodiment of the present application, the lithium-nickel mixing ratio of the positive electrode material is <3%, which is much smaller than the 10% of conventional ternary materials. In this range, the positive electrode material has more excellent electrochemical performance during the cycle process.

[0049] The present application also provides a preparation method of the positive electrode material, which comprises the following steps:

[0050] (a) preparing M 1 doped (Co 1-z1 M1 z1 3O4 precursor:

[0051] Soluble cobalt salts and M-containing 1 Sulfates of elements are classified according to Co:M 1 Solvents were added in a molar ratio of (1-z1):z1, and precipitants and complexing agents were added at a concentration of 0.5–3 mol / L. The pH was adjusted to between 5 and 8 to induce precipitation. The precipitate was then placed in an air-atmosphere sintering furnace and sintered at 400–800 °C for 5–15 h. After sintering, the product was ground and sieved to obtain M. 1 Doped (Co) 1-z1 M 1 z1 )3O4, where 0≤z1<0.1;

[0052] (b) Preparation of M 2 Doped Ni x2 Co y2 Mn 1-x2-y2-z2 M 2 z2 (OH)2 precursor:

[0053] Cobalt sulfate, manganese sulfate, nickel sulfate, and substances containing M 2 Sulfates of elements are arranged in the order Ni:Co:Mn:M 2 A mixed metal salt solution was prepared by adding metal salts in a molar ratio of x2:y2:(1-x2-y2-z2):z2; precipitant and complexing agent were added at a concentration of 0.1–3 mol / L, and the pH was adjusted to between 10 and 13 to carry out a coprecipitation reaction; then the coprecipitate was centrifuged, washed, and dried to obtain M. 2 Doped Ni x2 Co y2 Mn 1-x2-y2-z2 M 2 z2 (OH)2 precursor;

[0054] (c) Preparation of M 1 Doped sodium cobalt oxide Na m Co 1-z1 M 1 z1 O2:

[0055] M 1 Doped (Co) 1-z1 M 1 z1 Na₃O₄ precursor and Na₂CO₃ were mixed at a Na:Co molar ratio of (0.7–0.78):1. The homogeneous powder was then sintered in an oxygen atmosphere at 750–950 °C for 24–36 h to obtain M.1 doped sodium cobalt oxide Na m Co 1-z1 M 1 z1 O2, wherein 0.7≤m<0.78;

[0056] (d) preparing M 2 doped sodium nickel cobalt manganese oxide Na n Ni x2 Co y2 Mn 1-x2-y2-z2 M 2 z2 O2:

[0057] preparing M 2 doped sodium nickel cobalt manganese oxide Na n Ni x2 Co y2 Mn 1-x2-y2-z2 M 2 z2 O2 and Na2CO3 in a Na:Co molar ratio of (1-1.2):1, and then sintering the mixed powder in an oxygen atmosphere at a temperature of 600-900°C for 18-32h to obtain M 2 doped sodium nickel cobalt manganese oxide Na n Ni x2 Co y2 Mn 1-x2-y2-z2 M 2 z2 O2, wherein 1≤n<1.2;

[0058] (e) mixing Na m Co 1-z1 M 1 z1 O2 and Na n Ni x2 Co y2 Mn 1-x2-y2-z2 M 2 z2 O2, and then mixing with a lithium salt in a Na:Li molar ratio of 0.01-0.2, and sintering in an air atmosphere at a temperature of 250-400°C for 1-8h, and then washing the reaction product with deionized water to remove surface residues, and drying to obtain the positive electrode material.

[0059] According to an embodiment of the present application, in step (a), the soluble cobalt salt is selected from at least one of cobalt sulfate, cobalt chloride, cobalt nitrate, and cobalt acetate.

[0060] According to an embodiment of the present application, in step (a), the solvent is selected from deionized water.

[0061] According to an embodiment of the present application, in step (a), the precipitant is at least one selected from the group consisting of sodium carbonate, sodium hydroxide, and sodium bicarbonate.

[0062] According to an embodiment of the present application, in step (a), the complexing agent is ammonia.

[0063] According to an embodiment of the present application, in step (a), the molar ratio of the complexing agent to the precipitant is 0.2 to 1:1.

[0064] According to an embodiment of the present application, in step (b), the solvent is deionized water.

[0065] According to an embodiment of the present application, in step (b), the precipitant is at least one selected from the group consisting of sodium carbonate, sodium hydroxide, and sodium bicarbonate.

[0066] According to an embodiment of the present application, in step (b), the complexing agent is ammonia.

[0067] According to an embodiment of the present application, in step (b), the molar ratio of the complexing agent to the precipitant is 0.1 to 1:1.

[0068] According to an embodiment of the present application, in step (e), the Na m Co 1-z1 M 1 z1 O2 and Na n Ni x2 Co y2 Mn 1-x2-y2- z2 M 2 z2 O2 are mixed in a weight ratio of (60 to 95):(40 to 5).

[0069] According to an embodiment of the present application, in step (e), the lithium salt is at least one selected from the group consisting of lithium hydroxide, lithium nitrate, and lithium chloride.

[0070] The present application also provides a positive electrode sheet including the positive electrode material.

[0071] According to an embodiment of the present application, the positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer disposed on at least one side surface of the positive electrode current collector, the positive electrode active material layer including the positive electrode material.

[0072] According to an embodiment of the present application, the positive electrode active material layer further includes a conductive agent and a binder.

[0073] According to an embodiment of the present application, the mass percentage of each component in the positive electrode active material layer is: 70-99wt% of positive electrode material, 0.5-15wt% of conductive agent, and 0.5-15wt% of binder.

[0074] Preferably, the mass percentage of each component in the positive electrode active material layer is: 80-98wt% of positive electrode material, 1-10wt% of conductive agent, and 1-10wt% of binder.

[0075] More preferably, the mass percentage of each component in the positive electrode active material layer is: 90-96wt% of positive electrode material, 2-5wt% of conductive agent, and 2-5wt% of binder.

[0076] The present application also provides a battery comprising the positive electrode material described above, or a battery comprising the positive electrode sheet described above.

[0077] According to an embodiment of the present application, the charge cut-off voltage of the battery is greater than or equal to 4.5V.

[0078] According to an embodiment of the present application, the use of the battery is not particularly limited, and can be used in any 3C electronic product known in the prior art.

[0079] The present application will be further described in conjunction with specific examples. It should be understood that the following examples are only illustrative and explanatory of the present application, and should not be interpreted as limiting the scope of protection of the present application. Any technology realized based on the above description of the present application is encompassed within the scope of the present application.

[0080] The experimental methods used in the following examples are conventional methods unless otherwise specified; the reagents, materials, etc. used in the following examples are commercially available unless otherwise specified.

[0081] Example 1

[0082] The chemical formula of the positive electrode material in this example is:

[0083] 0.7Li 0.95 Na 0.02 Co 0.97 Al 0.03 O2·0.3Li(Ni 0.6 Co 0.095 Mn 0.3 Al 0.005 )O2, the Li / Ni mixing ratio of the positive electrode material is 2.5%, the XRD pattern thereof is shown in Figure 1 , and the SEM morphology thereof is shown in Figure 2 , and the preparation steps are as follows:

[0084] (1) Co 0.97 Al 0.003 )3O4 precursor doped with Al element and Ni 0.6 Co 0.095 Mn 0.3 Al 0.005 (OH)2 precursor by co-precipitation and sintering:

[0085] (1.1) Preparation of Co 0.97 Al 0.003 )3O4 precursor: Cobalt sulfate and aluminum sulfate were added to deionized water in a molar ratio of 0.97:0.03, and precipitant sodium hydroxide and complexing agent ammonia were added at a concentration of 1.2 mol / L, wherein the molar ratio of the complexing agent to the precipitant was 0.5, the pH was adjusted to 7.5, and precipitation was carried out; then the precipitate was placed in a sintering furnace in an air atmosphere and sintered at 600°C for 8h, and after sintering, the product was ground and sieved to obtain a Co 0.97 Al 0.003 )3O4 precursor doped with Al element;

[0086] (1.2) Preparation of Ni 0.6 Co 0.095 Mn 0.3 Al 0.005 (OH)2 precursor: Cobalt sulfate, manganese sulfate, nickel sulfate, and aluminum sulfate were added to the solvent deionized water to prepare a mixed metal salt solution in a molar ratio of Ni:Co:Mn:Al of 0.6:0.095:0.3:0.005; precipitant sodium hydroxide and complexing agent ammonia were added at a concentration of 2 mol / L, wherein the molar ratio of the complexing agent to the precipitant was 0.4, the pH was adjusted to 12, and the co-precipitation reaction was carried out; then the co-precipitate was treated by centrifugation, washing, and drying to obtain a Ni 0.6 Co 0.095 Mn 0.3 Al 0.005 (OH)2 precursor doped with Al element;

[0087] (2) Solid-phase sintering to prepare sodium cobalt oxide Na 0.72 Co 0.97 Al 0.03 O2 and sodium nickel cobalt manganese oxide NaNi 0.6 Co 0.095 Mn 0.3 Al 0.005 O2:

[0088] (2.1) Preparation of Na 0.72 Co 0.97 Al 0.03 O2 doped with Al element: Co 0.97Al 0.003 )3O4 precursor and Na2CO3 were mixed in a molar ratio of Na:Co of 0.72:1, and then the mixed powder was sintered in an oxygen atmosphere at a sintering temperature of 800℃ for 24h to obtain an Al element-doped sodium cobalt oxide Na 0.72 Co 0.97 Al 0.03 O2.

[0089] (2.2) Preparation of an Al element-doped sodium nickel cobalt manganese oxide NaNi 0.6 Co 0.095 Mn 0.3 Al 0.005 O2: sodium carbonate and the Al element-doped sodium nickel cobalt manganese oxide Ni 0.6 Co 0.095 Mn 0.3 Al 0.005 (OH)2 were mixed in a molar ratio of Na:Co of 1.1:1, and then the mixed powder was sintered in an oxygen atmosphere at a temperature of 650℃ for 24h to obtain an Al element-doped sodium nickel cobalt manganese oxide NaNi 0.6 Co 0.095 Mn 0.3 Al 0.005 O2.

[0090] (3) Ion exchange method to obtain the positive electrode material:

[0091] Na 0.72 Co 0.97 Al 0.03 O2 and NaNi 0.6 Co 0.095 Mn 0.3 Al 0.005 O2 were mixed in a weight ratio of 70:30, and then mixed with lithium nitrate in a Na:Li molar ratio of 0.1, and sintered in an air atmosphere at a temperature of 280℃ for 1h, and then the reaction product was washed with deionized water for multiple times to remove surface residues, and dried to obtain the positive electrode material.

[0092] Figure 3 is the dQ / dV curve of the positive electrode material in Example 1 and Comparative Example 1. It can be seen from Figure 3 that the charge and discharge voltage platforms in the dQ / dV curve of the positive electrode material of the present application can be well integrated, and no new voltage platform is generated, indicating that no new phase change occurs in the positive electrode material during the charging and discharging process, and the positive electrode material has good electrochemical performance.

[0093] Example 2

[0094] The chemical formula of the positive electrode material in this example is:

[0095] 0.8Li 0.95 Na 0.02 Co 0.97 Al 0.03 O2·0.2Li(Ni 0.6 Co 0.095 Mn 0.3 Al 0.005 )O2, the Li / Ni cation mixing ratio of the positive electrode material is 2.20%, the preparation process is the same as that of Example 1, except that in step (3) the weight ratio of Na 0.72 Co 0.97 Al 0.03 O2 and NaNi 0.6 Co 0.095 Mn 0.3 Al 0.005 O2 is 80:20, and the rest is the same.

[0096] Example 3

[0097] The chemical formula of the positive electrode material in this example is:

[0098] 0.9Li 0.95 Na 0.02 Co 0.97 Al 0.03 O2·0.1Li(Ni 0.6 Co 0.095 Mn 0.3 Al 0.005 )O2, the Li / Ni cation mixing ratio of the positive electrode material is 1.9%, the preparation process is the same as that of Example 1, except that in step (3) the weight ratio of Na 0.72 Co 0.97 Al 0.03 O2 and NaNi 0.6 Co 0.095 Mn 0.3 Al 0.005 O2 is 90:10, and the rest is the same.

[0099] Example 4

[0100] The chemical formula of the positive electrode material in this example is:

[0101] 0.7Li 0.95 Na 0.02 CoO2·0.3Li(Ni 0.6 Co 0.1 Mn 0.3 )O2, the Li / Ni cation mixing ratio of the positive electrode material is 2.20%, the preparation process is the same as that of Example 1, except that in step (1) no Al element is added, and the rest is the same.

[0102] Comparative Example 1

[0103] The chemical formula of the cathode material in this comparative example is:

[0104] 0.5Li 0.95 Na 0.02 Co 0.97 Al 0.03 O2·0.5Li(Ni 0.6 Co 0.095 Mn 0.3 Al 0.005 )O2, the Li / Ni cation mixing ratio of which is 4.0%, and the preparation process is the same as that of Example 1, except that in step (3) the weight ratio of NaNi 0.72 Co 0.97 Al 0.03 O2 and NaNi 0.6 Co 0.095 Mn 0.3 Al 0.005 O2 is 50:50, and the rest is the same.

[0105] Comparative Example 2

[0106] The chemical formula of the cathode material in this comparative example is Li 0.95 Na 0.02 Co 0.97 Al 0.03 O2, and the preparation process is the same as that of Example 1, except that in step (3) the weight ratio of NaNi 0.72 Co 0.97 Al 0.03 O2 and NaNi 0.6 Co 0.095 Mn 0.3 Al 0.005 O2 is 100:0, and the rest is the same.

[0107] Comparative Example 3

[0108] The chemical formula of the cathode material in this comparative example is Li(Ni 0.6 Co 0.095 Mn 0.3 Al 0.005 )O2, and the preparation process is the same as that of Example 1, except that in step (3) the weight ratio of NaNi 0.72 Co 0.97 Al 0.03 O2 and NaNi 0.6 Co 0.095 Mn 0.3 Al 0.005 O2 is 0:100, and the rest is the same.

[0109] Test Example

[0110] The above examples and comparative examples all use CR2032 button batteries to test the electrochemical performance of the above-mentioned positive electrode materials, and the button batteries are prepared according to the following method:

[0111] The positive electrode sheet uses NMP as a solvent, and the positive electrode active material (the positive electrode material prepared in the examples and comparative examples), the conductive agent Super P, and the binder polyvinylidene fluoride PVDF are stirred uniformly in a degassing machine according to a mass ratio of 97:1.5:1.5 to prepare a slurry positive electrode slurry with a solid content of 70%, and the positive electrode slurry is uniformly coated on the surface of an aluminum foil, and then baked in a vacuum oven at 100°C for 12h, followed by rolling, cutting, to obtain a positive electrode sheet.

[0112] The positive electrode sheet and lithium sheet negative electrode, PP / PE / PP three-layer separator, and 1mol / L LiPF6 / (EC+DEC) electrolyte (volume ratio 1:1) are assembled into a button battery for electrochemical testing in a glove box.

[0113] Performance test of the above-prepared button battery:

[0114] The test temperature is 25°C, and under the condition of a voltage range of 3.0-4.5V, the rate performance test is first performed, wherein the charge rate is 0.1C, and the discharge rate is 0.1C, 0.5C, 1C, 2C, and 5C in turn, and the rate performance test is shown in Table 2. Then, the cycle performance test is performed under the condition of a charge-discharge rate of 0.5C and a voltage range of 3.0-4.55V, and the cycle is 50 cycles, and the capacity retention rate (%) after 50 cycles = the discharge capacity of the 55th cycle / the discharge capacity of the 6th cycle x 100%.

[0115] SEM test:

[0116] The morphology and element distribution of the powder can be tested and analyzed by scanning electron microscopy.

[0117] Element composition test:

[0118] The ICP detector is used to test the element content of the positive electrode material powder; for the positive electrode sheet containing the positive electrode material, the positive electrode sheet is dissolved with NMP, then filtered, washed and dried to obtain the powder, and then the ICP detector is used for element content test and analysis.

[0119] X-ray test:

[0120] The XRD pattern and XRD refinement data of the positive electrode material are obtained by using Bruker D8 Advance to obtain the Li / Ni mixing ratio.

[0121] Table 1: XRD test results of positive electrode materials in examples and comparative examples

[0122]

[0123]

[0124] Table 2: Performance test results of batteries assembled with positive electrode materials in examples and comparative examples

[0125]

[0126] Table 1 shows the XRD test results of positive electrode materials in examples and comparative examples, and the results show that the lithium-nickel mixing arrangement of the positive electrode materials in examples is low, which helps to increase the structural stability of the positive electrode materials during the cycle process and improve the cycle performance. The electrochemical performance results of the examples and comparative examples described in Table 2 show that the positive electrode materials provided by the present application all have the characteristics of high capacity, good cycle performance and excellent rate performance.

[0127] The above describes the embodiments of the present application. However, the present application is not limited to the above-described embodiments. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A positive electrode material, the positive electrode material having a chemical formula of: Li a Ni b Co c Al d O 2 0.6≤a<1, 0<β≤0.4, and a+β=1; a Li x1 Na y1 Co 1-z1 M 1 z1 O2·βLi a (Ni x2 Co y2 Mn 1-x2-y2-z2 M 2 z2 )O2, wherein, The positive electrode material satisfies at least one of the following relationships: 0.9 < a < 1.1, 0.8 < x1 < 1, 0 < y1 < 0.05, 0 ≤ z1 < 0.1, M 1 is at least one of Al, Mg, Ti, Mn, Zr, B, P, Te, Nb, W, La, Y; 0.3 ≤ x2 ≤ 0.8, 0.05 ≤ y2 ≤ 0.3, 0.6 ≤ x2 + y2 ≤ 0.9, 0 ≤ z2 < 0.1, M 2 is at least one of Al, Mg, Ti, Zr, B, Te, Nb, W, Si, and the positive electrode material has only one characteristic diffraction peak in the range of 18°~19° in the 2θ diffraction angle of the X-ray diffraction pattern of the positive electrode material; the positive electrode material has an O2 phase stacking structure; 0.9<I1 / I3<3.8; 1.1<I2 / I3<4.8; Wherein, I1 is the peak intensity of the (101) crystal plane characteristic diffraction peak of the positive electrode material; I2 is the peak intensity of the (103) crystal plane characteristic diffraction peak of the positive electrode material; I3 is the peak intensity of the (104) crystal plane characteristic diffraction peak of the positive electrode material; The X-ray diffraction pattern of the positive electrode material has a (101) crystal plane characteristic diffraction peak at a 2θ diffraction angle in the range of 38.10°-38.20°; the X-ray diffraction pattern of the positive electrode material has a (103) crystal plane characteristic diffraction peak at a 2θ diffraction angle in the range of 46.90°-47.00°; the X-ray diffraction pattern of the positive electrode material has a (104) crystal plane characteristic diffraction peak at a 2θ diffraction angle in the range of 46.20°-46.30°. The half-peak width of the characteristic diffraction peak of the X-ray diffraction pattern of the positive electrode material at a 2θ diffraction angle in the range of 18°-19° is greater than or equal to 0.

15.

2. The positive electrode material of claim 1, wherein, The average particle size of the positive electrode material is 5μm-20μm; 3. The positive electrode material of claim 1, wherein, And / or, the lithium-nickel mixing ratio of the positive electrode material is less than 3%. The positive electrode sheet comprises the positive electrode material according to any one of claims 1-3.

4. A positive electrode sheet characterized by comprising: The battery comprises the positive electrode material according to any one of claims 1-3, or the battery comprises the positive electrode sheet according to claim 4.

5. A battery, characterized by The charging cut-off voltage of the battery is greater than or equal to 4.5V.

6. The battery of claim 5, wherein, ​

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