Positive electrode material, preparation method and application thereof

Abstract

The present application relates to a positive electrode material and its preparation method and application. The preparation method of the positive electrode material of the present application comprises the following steps: providing a metal salt solution, the metal salt solution comprising Ni 2+ 、Co 2+ 、Mn 2+ and Al 3+ A precipitant solution comprising lactic acid and ammonium carbonate is dropwise added to a metal salt solution to obtain a lactate precursor; and the lactate precursor and a lithium source are co-sintered. The method for preparing the cathode material of the present application enables precise control of the molar ratio of each element of nickel, cobalt, manganese, and aluminum to produce a cathode material having a desired chemical composition.

Description

Technical Field

[0001] The present application relates to the technical field of lithium-ion batteries, and in particular to a positive electrode material and a preparation method and application thereof. Background Art

[0002] Using cathode materials with higher specific capacity is an effective measure to enhance the range of new energy vehicles. High-nickel cathode materials with nickel content exceeding 80% have high specific capacity and are often used to improve the range of new energy vehicles. However, their disadvantage is a shorter cycle life. Compared to traditional ternary high-nickel cathode materials, nickel-cobalt-manganese-aluminum quaternary high-nickel cathode materials achieve both higher specific capacity and higher cycle performance.

[0003] However, in the traditional preparation method of nickel-cobalt-manganese-aluminum quaternary high-nickel positive electrode material, it is difficult to achieve precise control of the molar ratio of each element of nickel, cobalt, manganese and aluminum to prepare a positive electrode material with a chemical composition that meets the requirements. Summary of the Invention

[0004] Based on this, it is necessary to provide a positive electrode material and its preparation method and application. The preparation method of the positive electrode material of the present application can achieve precise control of the molar ratio of each element of nickel, cobalt, manganese and aluminum to prepare a positive electrode material with a chemical composition that meets the requirements.

[0005] In a first aspect, the present application provides a method for preparing a positive electrode material, comprising the following steps:

[0006] Provide a metal salt solution, the metal salt solution including Ni 2+ 、Co 2+ 、Mn 2+ and Al 3+ ;

[0007] adding a precipitant solution dropwise to the metal salt solution, wherein the precipitant solution comprises lactic acid and ammonium carbonate to obtain a lactate precursor;

[0008] The lactate precursor and the lithium source are sintered together.

[0009] In some embodiments, during the process of adding the precipitant solution dropwise to the metal salt solution, the temperature of the metal salt solution is controlled to be 30° C. to 40° C.

[0010] In some embodiments, the time for adding the precipitant solution dropwise to the metal salt solution is 15 hours to 30 hours.

[0011] In some embodiments, the metal salt solution contains Ni 2+ 、Co 2+ 、Mn 2+ and Al 3+The ratio of the total molar amount of to the molar amount of lactic acid in the precipitant solution is 1:(0.8~1.2).

[0012] In some embodiments, in the precipitant solution, the molar ratio of lactic acid to ammonium carbonate is 1:(1-1.8).

[0013] In some embodiments, the metal salt solution contains Ni 2+ 、Co 2+ 、Mn 2+ and Al 3+ The total molar concentration is 0.8mol / L~1.2mol / L.

[0014] In some embodiments, the total molar concentration of lactic acid and ammonium carbonate in the precipitant solution is 0.8 mol / L to 1.2 mol / L.

[0015] In some embodiments, the solute of the metal salt solution includes NiSO4·6H2O, CoSO4·7H2O, MnSO4·H2O and Al2(SO4)3·18H2O.

[0016] In some embodiments, the metal salt solution contains Ni 2+ 、Co 2+ 、Mn 2+ and Al 3+ The molar ratio is a:b:c:d, wherein a is 0.8~0.9, b is 0.05~0.1, c is 0.025~0.05, and d is 0.025~0.05.

[0017] In a second aspect, the present application also provides a positive electrode material prepared by any of the above methods for preparing the positive electrode material.

[0018] In some embodiments, the positive electrode material comprises a LiNi l Co m Mn n Al o O2 material, wherein l is 0.8~0.9, m is 0.05~0.1, n is 0.025~0.05, o is 0.025~0.05, l+m+n+o=1.

[0019] In a third aspect, the present application provides a positive electrode sheet, comprising a current collector and an active layer located on the surface of the current collector, wherein the active layer comprises any of the positive electrode materials described above.

[0020] In a fourth aspect, the present application provides a lithium-ion battery comprising the positive electrode sheet described above.

[0021] In the preparation method of the positive electrode material, a precipitant solution including lactic acid and ammonium carbonate is used to precipitate Ni in the metal salt solution. 2+ 、Co 2+ 、Mn 2+ and Al 3+ Co-precipitation was performed to obtain Ni 2+ 、Co 2+ 、Mn 2+ and Al 3+ Compared with the traditional method of preparing quaternary cathode materials using strong bases such as sodium hydroxide as precipitants for co-precipitation, the above-mentioned method of preparing cathode materials can achieve Ni 2+ 、Co 2+ 、Mn 2+ and Al 3+ Better co-precipitation effect can solve the problem of Al 3+ The rapid precipitation of nickel, cobalt, manganese and aluminum leads to the problem that the molar ratio of each element is difficult to accurately control. The preparation method of the positive electrode material of the present application can achieve accurate control of the molar ratio of each element of nickel, cobalt, manganese and aluminum to prepare a positive electrode material with a chemical composition that meets the requirements.

[0022] Further, a precipitant solution comprising lactic acid and ammonium carbonate is used to precipitate Ni in the metal salt solution. 2+ 、Co 2+ 、Mn 2+ and Al 3+ The relatively mild operating conditions for co-precipitation reduce reliance on temperature, pressure, reaction environment, and other factors, reducing uncertainty in the production process and making the production process easier to control. Furthermore, these mild process conditions help protect the product structure from damage during the reaction, maintaining its integrity and excellent performance. Furthermore, these mild operating conditions reduce reliance on expensive equipment suitable for strong base reactions, lowering investment costs for production facilities and enhancing the process's adaptability and flexibility.

[0023] Furthermore, by achieving precise control of the molar ratios of nickel, cobalt, manganese and aluminum elements, it helps to optimize the crystal structure and electrochemical properties of the positive electrode material, thereby improving the overall performance of lithium-ion batteries, such as capacity, cycle life and rate performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is an SEM image of the high-nickel positive electrode material prepared in Example 1 of the present application;

[0025] Figure 2 This is the XRD pattern of the high-nickel positive electrode material prepared in Examples 1 to 5 of the present application;

[0026] Figure 3A comparison chart of the cycle performance of high-nickel positive electrode materials prepared in Examples 1 to 3 of the present application;

[0027] Figure 4 This is a comparison chart of the rate performance of high-nickel positive electrode materials prepared in Examples 1 to 3 of the present application. DETAILED DESCRIPTION

[0028] To make the above-mentioned objects, features, and advantages of the present application more clearly understood, the specific embodiments of the present application are described in detail below. The following description sets forth many specific details to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways than those described herein, and those skilled in the art can make similar modifications without violating the scope of the present application. Therefore, the present application is not limited to the specific embodiments disclosed below.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0030] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0031] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of such features. In the description of this application, "plurality" means at least two, for example, two, three, etc., unless otherwise specifically defined.

[0032] An embodiment of the present application provides a method for preparing a positive electrode material, comprising the following steps:

[0033] Provide a metal salt solution, the metal salt solution includes Ni 2+ 、Co 2+ 、Mn 2+ and Al3+ ;

[0034] adding a precipitant solution comprising lactic acid and ammonium carbonate dropwise to a metal salt solution to obtain a lactate precursor;

[0035] The lactate precursor and the lithium source are sintered together.

[0036] In the preparation method of the positive electrode material, a precipitant solution including lactic acid and ammonium carbonate is used to precipitate Ni in the metal salt solution. 2+ 、Co 2+ 、Mn 2+ and Al 3+ Co-precipitation was performed to obtain Ni 2+ 、Co 2+ 、Mn 2+ and Al 3+ Compared with the traditional method of preparing quaternary cathode materials using strong bases such as sodium hydroxide as precipitants for co-precipitation, the above-mentioned method of preparing cathode materials can achieve Ni 2+ 、Co 2+ 、Mn 2+ and Al 3+ Better co-precipitation effect can solve the problem of Al 3+ The rapid precipitation of nickel, cobalt, manganese and aluminum leads to the problem that the molar ratio of each element is difficult to accurately control. The preparation method of the positive electrode material of the present application can achieve accurate control of the molar ratio of each element of nickel, cobalt, manganese and aluminum to prepare a positive electrode material with a chemical composition that meets the requirements.

[0037] Further, a precipitant solution comprising lactic acid and ammonium carbonate is used to precipitate Ni in the metal salt solution. 2+ 、Co 2+ 、Mn 2+ and Al 3+ The relatively mild operating conditions for co-precipitation reduce reliance on temperature, pressure, reaction environment, and other factors, reducing uncertainty in the production process and making the production process easier to control. Furthermore, these mild process conditions help protect the product structure from damage during the reaction, maintaining its integrity and excellent performance. Furthermore, these mild operating conditions reduce reliance on expensive equipment suitable for strong base reactions, lowering investment costs for production facilities and enhancing the process's adaptability and flexibility.

[0038] Furthermore, precise control of the molar ratios of nickel, cobalt, manganese, and aluminum helps optimize the crystal structure and electrochemical properties of the cathode material, thereby improving the overall performance of lithium-ion batteries, such as capacity, cycle life, and rate capability. At the same time, the relatively inexpensive transition metal Mn can be used to replace the small amount of Co in the cathode material, effectively avoiding the cost issues associated with reliance on metallic Co.

[0039] In some embodiments, during the process of adding the precipitant solution dropwise to the metal salt solution, the temperature of the metal salt solution is controlled to be 30° C. to 40° C.

[0040] During the process of adding the precipitant solution to the metal salt solution, controlling the temperature of the metal salt solution to 30°C to 40°C can achieve a good co-precipitation effect. At the same time, the co-precipitation operating conditions are relatively mild, which can reduce dependence on conditions such as temperature, pressure, and reaction environment, and reduce uncertainty in the production process. Optionally, during the process of adding the precipitant solution to the metal salt solution, the temperature of the metal salt solution is controlled to 30°C, 32°C, 34°C, 36°C, 38°C, or 40°C. Alternatively, during the process of adding the precipitant solution to the metal salt solution, the temperature of the metal salt solution can also be controlled within a range between any two of the above temperatures.

[0041] In some embodiments, the time for adding the precipitant solution dropwise to the metal salt solution is 15 hours to 30 hours.

[0042] In the above-mentioned time range of adding the precipitant solution dropwise to the metal salt solution, the Ni 2+ 、Co 2+ 、Mn 2+ and Al 3+ A slower coprecipitation can achieve a better coprecipitation effect. Optionally, the time for adding the precipitant solution to the metal salt solution is 15 hours, 18 hours, 20 hours, 22 hours, 25 hours, 28 hours or 30 hours, or the time for adding the precipitant solution to the metal salt solution can also be within the range between any two of the above times.

[0043] In some embodiments, stirring is continued during the process of adding the precipitant solution dropwise to the metal salt solution.

[0044] In some embodiments, the stirring rate is 1000 r / min to 1500 r / min.

[0045] Optionally, the stirring rate is 1000 r / min, 1100 r / min, 1200 r / min, 1300 r / min, 1400 r / min or 1500 r / min, or the stirring rate may be within a range between any two of the above rates.

[0046] In some embodiments, after obtaining the lactate precursor, the following steps are further included:

[0047] The lactate precursor is subjected to solid-liquid separation and dried.

[0048] In some embodiments, the drying method is vacuum drying.

[0049] In some embodiments, the drying temperature is 60°C to 120°C.

[0050] Optionally, the drying temperature is 60°C, 70°C, 80°C, 90°C, 100°C, 110°C or 120°C, or the drying temperature may be within a range between any two of the above temperatures.

[0051] In some embodiments, the drying time is 24 hours to 36 hours.

[0052] Optionally, the drying time is 24 hours, 26 hours, 28 hours, 30 hours, 32 hours, 34 hours or 36 hours, or the drying time may be within a range between any two of the above times.

[0053] In some embodiments, the metal salt solution contains Ni 2+ 、Co 2+ 、Mn 2+ and Al 3+ The ratio of the total molar amount of and the molar amount of lactic acid in the precipitant solution is 1: (0.8~1.2).

[0054] In the above metal salt solution, Ni 2+ 、Co 2+ 、Mn 2+ and Al 3+ The total molar amount of Ni in the metal salt solution and the molar amount of lactic acid in the precipitant solution can achieve a good co-precipitation effect, thereby preparing the lactate precursor. 2+ 、Co 2+ 、Mn 2+ and Al 3+ The ratio of the total molar amount of Ni in the metal salt solution to the molar amount of lactic acid in the precipitant solution is 1:0.8, 1:0.85, 1:0.9, 1:0.95, 1:1, 1:1.05, 1:1.1, 1:1.15 or 1:1.2, or the total molar amount of Ni in the metal salt solution is 1:0.8, 1:0.85, 1:0.9, 1:0.95, 1:1, 1:1.05, 1:1.1, 1:1.15 or 1:1.2. 2+ 、Co 2+ 、Mn 2+ and Al 3+ The ratio of the total molar amount of to the molar amount of lactic acid in the precipitant solution can also be within the range between any two of the above ratios.

[0055] In some embodiments, in the precipitant solution, the molar ratio of lactic acid to ammonium carbonate is 1:(1-1.8).

[0056] In the above-mentioned precipitant solution, within the range of the molar ratio of lactic acid to ammonium carbonate, a good coprecipitation effect can be achieved, thereby preparing the lactate precursor. Optionally, the molar ratio of lactic acid to ammonium carbonate in the precipitant solution is 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7 or 1:1.8, or the molar ratio of lactic acid to ammonium carbonate in the precipitant solution can also be within the range between any two of the above ratios.

[0057] In some embodiments, the metal salt solution contains Ni 2+ 、Co 2+ 、Mn 2+ and Al 3+ The total molar concentration is 0.8mol / L~1.2mol / L.

[0058] Alternatively, Ni in the metal salt solution 2+ 、Co 2+ 、Mn 2+ and Al 3+ The total molar concentration of Ni in the metal salt solution is 0.8mol / L, 0.85mol / L, 0.9mol / L, 0.95mol / L, 1mol / L, 1.05mol / L, 1.1mol / L, 1.15mol / L or 1.2mol / L, or 2+ 、Co 2+ 、Mn 2+ and Al 3+ The total molar concentration can also be within the range between any two of the above molar concentrations.

[0059] In some embodiments, the total molar concentration of lactic acid and ammonium carbonate in the precipitant solution is 0.8 mol / L to 1.2 mol / L.

[0060] Optionally, the total molar concentration of lactic acid and ammonium carbonate in the precipitant solution is 0.8 mol / L, 0.85 mol / L, 0.9 mol / L, 0.95 mol / L, 1 mol / L, 1.05 mol / L, 1.1 mol / L, 1.15 mol / L or 1.2 mol / L, or the total molar concentration of lactic acid and ammonium carbonate in the precipitant solution may be within the range between any two of the above molar concentrations.

[0061] In some embodiments, the solute of the metal salt solution includes NiSO4·6H2O, CoSO4·7H2O, MnSO4·H2O and Al2(SO4)3·18H2O.

[0062] NiSO4·6H2O, CoSO4·7H2O, MnSO4·H2O and Al2(SO4)3·18H2O are more stable at room temperature, easily soluble in water and have higher solubility, which is more conducive to the preparation of suspension.

[0063] In some embodiments, the metal salt solution contains Ni 2+ 、Co 2+ 、Mn 2+ and Al 3+ The molar ratio is a:b:c:d, wherein a is 0.8~0.9, b is 0.05~0.1, c is 0.025~0.05, and d is 0.025~0.05.

[0064] In the above metal salt solution, Ni 2+ 、Co 2+ 、Mn 2+ and Al 3+ Within the range of the molar ratio of , a positive electrode material with both high specific capacity and cycle performance can be prepared. Optionally, a is 0.81, 0.82, 0.83, 0.84, 0.85, 0.86, 0.87, 0.88, 0.89 or 0.9, or, a may also be in the range between any two of the above values. Optionally, b is 0.05, 0.06, 0.07, 0.08, 0.09 or 0.1, or, b may also be in the range between any two of the above values. Optionally, c is 0.025, 0.03, 0.035, 0.04, 0.045 or 0.05, or, c may also be in the range between any two of the above values. Optionally, d is 0.025, 0.03, 0.035, 0.04, 0.045 or 0.05, or, d may also be in the range between any two of the above values.

[0065] In some embodiments, the co-sintering of the lactate precursor and the lithium source comprises the following steps:

[0066] performing a first sintering treatment on the lactate precursor;

[0067] The lactate precursor after the first sintering treatment is mixed with a lithium source and heated to perform a second sintering treatment.

[0068] In some embodiments, the molar ratio of the lactate precursor to the lithium source is 1:(1.05-1.1).

[0069] Optionally, the molar ratio of the lactate precursor to the lithium source is 1:1.05, 1:1.06, 1:1.07, 1:1.08, 1:1.09 or 1:1.1, or the molar ratio of the lactate precursor to the lithium source may be within the range between any two of the above molar ratios.

[0070] In some embodiments, the heating rate of the first sintering process is 4° C. / min to 6° C. / min.

[0071] Optionally, the heating rate of the first sintering process is 4°C / min, 4.5°C / min, 5°C / min, 5.5°C / min or 6°C / min, or the heating rate of the first sintering process may be within a range between any two of the above heating rates.

[0072] In some embodiments, the temperature of the first sintering process is 400°C to 600°C.

[0073] Optionally, the temperature of the first sintering treatment is 400°C, 420°C, 440°C, 460°C, 480°C, 500°C, 520°C, 540°C, 560°C, 580°C or 600°C, or the temperature of the first sintering treatment may be within the range between any two of the above temperatures.

[0074] In some embodiments, the first sintering treatment lasts for 3 hours to 5 hours.

[0075] Optionally, the time of the first sintering treatment is 3h, 3.2h, 3.4h, 3.6h, 3.8h, 4h, 4.2h, 4.4h, 4.6h, 4.8h or 5h, or the time of the first sintering treatment may also be within the range between any two of the above times.

[0076] In some embodiments, the temperature of the second sintering process is 650°C to 850°C.

[0077] Optionally, the temperature of the second sintering treatment is 650°C, 670°C, 690°C, 710°C, 730°C, 750°C, 770°C, 790°C, 810°C, 830°C or 850°C, or, the temperature of the second sintering treatment may be within the range between any two of the above temperatures.

[0078] In some embodiments, the heating rate of the second sintering process is 4° C. / min to 6° C. / min.

[0079] Optionally, the heating rate of the second sintering process is 4°C / min, 4.5°C / min, 5°C / min, 5.5°C / min or 6°C / min, or the heating rate of the second sintering process may be within a range between any two of the above heating rates.

[0080] In some embodiments, the second sintering treatment lasts for 5 hours to 8 hours.

[0081] Optionally, the time of the second sintering treatment is 5 hours, 5.5 hours, 6 hours, 6.5 hours, 7 hours, 7.5 hours or 8 hours, or the time of the second sintering treatment may also be within the range between any two of the above times.

[0082] Another embodiment of the present application further provides a positive electrode material prepared by any of the above methods for preparing the positive electrode material.

[0083] In some embodiments, the positive electrode material comprises a LiNi l Co m Mn n Al o O2 material, wherein l is 0.8~0.9, m is 0.05~0.1, n is 0.025~0.05, o is 0.025~0.05, l+m+n+o=1.

[0084] The above-mentioned high nickel quaternary positive electrode material can have both high specific capacity and cycle performance. Optionally, l is 0.81, 0.82, 0.83, 0.84, 0.85, 0.86, 0.87, 0.88, 0.89 or 0.9, or, l can also be in the range between any two of the above values. Optionally, m is 0.05, 0.06, 0.07, 0.08, 0.09 or 0.1, or, m can also be in the range between any two of the above values. Optionally, n is 0.025, 0.03, 0.035, 0.04, 0.045 or 0.05, or, n can also be in the range between any two of the above values. Optionally, o is 0.025, 0.03, 0.035, 0.04, 0.045 or 0.05, or, o can also be in the range between any two of the above values.

[0085] Another embodiment of the present application further provides a positive electrode plate, comprising a current collector and an active layer located on the surface of the current collector, wherein the active layer comprises any one of the above-mentioned positive electrode materials.

[0086] Another embodiment of the present application further provides a lithium-ion battery, comprising the above-mentioned positive electrode plate.

[0087] The following are specific embodiments

[0088] Example 1

[0089] Preparation method of positive electrode material:

[0090] (1) NiSO4·6H2O, CoSO4·7H2O, MnSO4·H2O and Al2(SO4)3·18H2O were weighed in sequence according to the molar ratio of 0.83:0.07:0.05:0.025, dissolved in a certain amount of deionized water to prepare a 1 mol / L metal salt solution. 2+ 、Co 2+ 、Mn 2+ and Al 3+ The total molar amount of lactic acid: the molar ratio of ammonium carbonate is 1:1:1. The corresponding molar amounts of lactic acid and ammonium carbonate are weighed in sequence and prepared with deionized water to form a precipitant solution. The total molar amount of lactic acid and ammonium carbonate in the precipitant solution is 1 mol / L.

[0091] (2) The metal salt solution was kept warm in an oil bath. The precipitant solution was added dropwise to the metal salt solution at 30°C and 1200 r / min with stirring, and the reaction was continued for 21 hours.

[0092] (3) The product was filtered, washed, and then vacuum dried at 120 °C for 24 hours to obtain Ni 0.83 Co 0.07 Mn 0.05 Al 0.05 C2O4 lactate precursor.

[0093] (4) The lactate precursor was heated to 500°C in a muffle furnace at a heating rate of 5°C / min and kept warm for 4 hours. The lactate precursor was then mixed with Li2CO3 at a molar ratio of 1:1.05, and the mixture was heated to 800°C at a heating rate of 5°C / min and kept warm for 6 hours to obtain LiNi 0.83 Co 0.07 Mn 0.05 Al 0.05 O2 high nickel positive electrode material.

[0094] Example 2

[0095] Preparation method of positive electrode material:

[0096] The preparation method of the positive electrode material in Example 2 is basically the same as that in Example 1, except that: in step (1), Ni 2+ 、Co 2+ 、Mn 2+ and Al 3+ The total molar amount of: lactic acid: ammonium carbonate molar ratio = 1:1:1.2.

[0097] Example 3

[0098] Preparation method of positive electrode material:

[0099] The preparation method of the positive electrode material in Example 3 is basically the same as that in Example 1, except that: in step (1), Ni 2+ 、Co 2+ 、Mn 2+ and Al 3+ The total molar amount of: lactic acid: ammonium carbonate molar ratio = 1:1:1.4.

[0100] Example 4

[0101] Preparation method of positive electrode material:

[0102] The preparation method of the positive electrode material in Example 4 is basically the same as that in Example 1, except that: in step (1), Ni 2+ 、Co 2+ 、Mn 2+ and Al 3+ The total molar amount of: lactic acid: ammonium carbonate molar ratio = 1:1:1.6.

[0103] Example 5

[0104] Preparation method of positive electrode material:

[0105] The preparation method of the positive electrode material in Example 5 is basically the same as that in Example 1, except that: in step (1), Ni 2+ 、Co 2+ 、Mn 2+ and Al 3+ The total molar amount of: lactic acid: ammonium carbonate molar ratio = 1:1:1.8.

[0106] Test Example 1

[0107] The cathode material prepared in Example 1 was subjected to SEM testing. The results are as follows: Figure 1 shown.

[0108] Test Example 2

[0109] The positive electrode materials prepared in Examples 1 to 5 were subjected to XRD testing. The results are as follows: Figure 2 shown.

[0110] Test Example 3

[0111] The positive electrode materials provided in Examples 1 to 5 are used as positive electrode materials to prepare lithium batteries. The specific assembly process is as follows:

[0112] The positive electrode material of each example was used as the positive electrode active material. The positive electrode material, binder PVDF, and conductive agent Super P were weighed in a mass ratio of 8:1:1, placed in a 10 mL small beaker and mixed evenly, and then an appropriate amount of N-methylpyrrolidone (NMP) was added dropwise. After stirring into a uniform slurry, it was coated on a dry aluminum foil using a scraper (150 mm). It was first placed in a blast drying oven at 80°C for 8 hours, and then transferred to a vacuum drying oven at 120°C for 12 hours. The completely dried electrode was punched into a circular positive electrode sheet with a diameter of 12 mm using a sheet punching machine, and then weighed and transferred to a glove box for standby use.

[0113] The prepared cathode sheet served as the positive electrode, metallic lithium served as the negative electrode, 1 mol / L LiPF₆ dissolved in a 1:1 volume ratio of ethylene carbonate (EC) and dimethyl carbonate (DMC) as the electrolyte, and Celgard 2400 polypropylene microporous membrane served as the separator. All materials were placed in a glove box filled with high-purity argon (O₂ <0.1 ppm, H₂O <0.1 ppm) to assemble into CR2032 button cells, which were then sealed using a sealing machine. Finally, the assembled CR2032 button cells were left to activate at room temperature for 12 hours before use.

[0114] Test Example 4

[0115] The initial constant current charge and discharge capacity and the discharge capacity after 100 cycles of the CR2032 button batteries prepared with the positive electrode materials provided in Examples 1 to 5 were tested respectively, and the capacity retention rate was calculated. The results are shown in Table 1 below, where the test voltage range is 3.0V~5.0V (vs. Li + / Li), with a rate of 1C.

[0116] Table 1

[0117]

[0118] Reference Figure 3 As can be seen from Table 1, the CR2032 button batteries prepared from the positive electrode materials provided in Examples 1 to 5 have higher specific capacity and cycle performance.

[0119] Test Example 5

[0120] CR2032 button batteries prepared from the positive electrode materials provided in Examples 1 to 5 were tested and cycled five times at rates of 0.1C, 0.2C, 0.5C, 1C, 2C, and 0.5C, respectively, to measure the rate performance of the lithium batteries. The results are shown in Table 2 below.

[0121] Table 2

[0122]

[0123] Reference Figure 4As can be seen from Table 2, the CR2032 button batteries prepared from the positive electrode materials provided in Examples 1 to 5 have high rate performance.

[0124] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0125] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art could make several modifications and improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the patent in this application shall be based on the appended claims, and the specification and drawings may be used to interpret the claims.

Claims

1. A method for preparing a positive electrode material, characterized in that: The steps include: Provide a metal salt solution, the metal salt solution including Ni 2+ 、Co 2+ 、Mn 2+ and Al 3+ ; adding a precipitant solution comprising lactic acid and ammonium carbonate dropwise to the metal salt solution to obtain a lactate precursor; During the process of adding the precipitant solution dropwise to the metal salt solution, the temperature of the metal salt solution is controlled to be 30° C. to 40° C.; and the time for adding the precipitant solution dropwise to the metal salt solution is 20 hours to 30 hours; The lactate precursor and the lithium source are sintered together.

2. The method for preparing the positive electrode material according to claim 1, wherein: The metal salt solution contains Ni 2+ 、Co 2+ 、Mn 2+ and Al 3+ The ratio of the total molar amount of to the molar amount of lactic acid in the precipitant solution is 1:(0.8-1.2); and / or, In the precipitant solution, the molar ratio of lactic acid to ammonium carbonate is 1:(1-1.8).

3. The method for preparing the positive electrode material according to claim 1, wherein: The metal salt solution contains Ni 2+ 、Co 2+ 、Mn 2+ and Al 3+ The total molar concentration is 0.8 mol / L to 1.2 mol / L; and / or, In the precipitant solution, the total molar concentration of lactic acid and ammonium carbonate is 0.8 mol / L to 1.2 mol / L.

4. The method for preparing a positive electrode material according to any one of claims 1 to 3, characterized in that: The solutes of the metal salt solution include NiSO4·6H2O, CoSO4·7H2O, MnSO4·H2O and Al2(SO4)3·18H2O.

5. The method for preparing a positive electrode material according to any one of claims 1 to 3, characterized in that: The metal salt solution contains Ni 2+ 、Co 2+ 、Mn 2+ and Al 3+ The molar ratio is a:b:c:d, wherein a is 0.8 to 0.9, b is 0.05 to 0.1, c is 0.025 to 0.05, and d is 0.025 to 0.

05.

6. A positive electrode material, characterized in that The cathode material is prepared by the method for preparing the cathode material according to any one of claims 1 to 5.

7. The positive electrode material according to claim 6, characterized in that Including chemical formula LiNi l Co m Mn n Al o O2 material, wherein l is 0.8-0.9, m is 0.05-0.1, n is 0.025-0.05, o is 0.025-0.05, and l+m+n+o=1.

8. A positive electrode plate, characterized in that: The invention comprises a current collector and an active layer located on the surface of the current collector, wherein the active layer comprises the positive electrode material according to any one of claims 6 to 7.

9. A lithium-ion battery, characterized in that: Including the positive electrode sheet according to claim 8.

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