Positive electrode material and preparation method and application thereof

Abstract

The invention relates to a positive electrode material and a preparation method and application thereof. The preparation method of the positive electrode material comprises the following steps: providing a metal salt solution which comprises Ni < 2 + >, Co < 2 + >, Mn < 2 + > and Al < 3 + >; a precipitant solution is dropwise added into the metal salt solution, the precipitant solution comprises lactic acid and ammonium carbonate, and a lactate precursor is obtained; and co-sintering the lactate precursor and a lithium source. According to the preparation method of the positive electrode material, the molar ratio of nickel, cobalt, manganese and aluminum elements can be accurately controlled so as to prepare the positive electrode material with the chemical composition meeting the requirement.

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] The use of cathode materials with higher specific capacity is an effective measure to enhance the endurance of new energy vehicles. High-nickel cathode materials with a nickel content of more than 80% have higher specific capacity and are often used to improve the endurance of new energy vehicles, but their disadvantage is that their cycle life is short. Compared with traditional ternary high-nickel cathode materials, nickel-cobalt-manganese-aluminum quaternary high-nickel cathode materials can achieve both higher specific capacity and 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 a preparation method and application thereof. 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 comprising Ni 2+ 、Co 2+ , Mn 2+ and Al 3+ ;

[0007] Adding a precipitant solution dropwise to the metal salt solution, wherein the precipitant solution includes 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 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 and 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-mentioned methods for preparing the positive electrode material.

[0018] In some embodiments, the positive electrode material includes a LiNi l Co m Mn n Al o O2 material, where 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.

[0019] In a third aspect, the present application 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 of the positive electrode materials described above.

[0020] In a fourth aspect, the present application provides a lithium-ion battery, comprising the positive electrode plate 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 causes the molar ratio of each element to be 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 mild operating conditions for coprecipitation can reduce the dependence on temperature, pressure, reaction environment and other conditions, reduce the uncertainty in the production process, and make the production process easier to control. At the same time, mild process conditions help protect the product structure from being destroyed during the reaction process, maintaining its integrity and excellent performance. In addition, mild operating conditions also reduce the dependence on expensive equipment that can be used for strong base reactions, reduce the investment cost of production facilities, and enhance the applicability and flexibility of the process.

[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] FIG1 is a SEM image of a high-nickel positive electrode material prepared in Example 1 of the present application;

[0025] FIG2 is an XRD diagram of the high nickel positive electrode material prepared in Examples 1 to 5 of the present application;

[0026] FIG3 is a comparison chart of the cycle performance of high nickel positive electrode materials prepared in Examples 1 to 3 of the present application;

[0027] FIG. 4 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] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below. In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used herein includes any and all combinations of one or more of the related 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 referred device or element 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] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, "plurality" means at least two, such as two, three, etc., unless otherwise clearly and 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 Al 3+ ;

[0034] Adding a precipitant solution dropwise to a metal salt solution, the precipitant solution comprising lactic acid and ammonium carbonate, 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 causes the molar ratio of each element to be 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 mild operating conditions for coprecipitation can reduce the dependence on temperature, pressure, reaction environment and other conditions, reduce the uncertainty in the production process, and make the production process easier to control. At the same time, mild process conditions help protect the product structure from being destroyed during the reaction process, maintaining its integrity and excellent performance. In addition, mild operating conditions also reduce the dependence on expensive equipment that can be used for strong base reactions, reduce the investment cost of production facilities, and enhance the applicability and flexibility of the process.

[0038] Furthermore, by achieving precise control of the molar ratio of each element of nickel, cobalt, manganese and aluminum, it is helpful 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. At the same time, relatively cheap transition metal Mn can be used to replace a small amount of Co in the positive electrode material, which can effectively avoid the cost problem caused by dependence on metal 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] In the process of dripping the precipitant solution into the metal salt solution, the temperature of the metal salt solution is controlled to be 30°C to 40°C, which can achieve a better co-precipitation effect. At the same time, the operating conditions of the co-precipitation are relatively mild, which can reduce the dependence on conditions such as temperature, pressure, and reaction environment, and reduce the uncertainty in the production process. Optionally, in the process of dripping the precipitant solution into the metal salt solution, the temperature of the metal salt solution is controlled to be 30°C, 32°C, 34°C, 36°C, 38°C or 40°C, or, in the process of dripping the precipitant solution into the metal salt solution, the temperature of the metal salt solution can also be controlled within the 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 h to 30 h.

[0042] In the above-mentioned time range of adding the precipitant solution dropwise to the metal salt solution, 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 15h, 18h, 20h, 22h, 25h, 28h or 30h, 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 also be within the 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 h, 26 h, 28 h, 30 h, 32 h, 34 h or 36 h, or the drying time may be within the 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+ In the range of 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, a good coprecipitation effect can be achieved, 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 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, in the precipitant solution, the molar ratio of lactic acid to ammonium carbonate 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, in the precipitant solution, the molar ratio of lactic acid to ammonium carbonate 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] Optionally, the metal salt solution Ni 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 may 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 also 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 having 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 process of sintering the lactate precursor and the lithium source together comprises the following steps:

[0066] subjecting the lactate precursor to a first sintering treatment;

[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 also 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 process 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 also be within the range between any two of the above heating rates.

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

[0081] Optionally, the time of the second sintering treatment is 5 h, 5.5 h, 6 h, 6.5 h, 7 h, 7.5 h or 8 h, 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, which is prepared by any of the above methods for preparing the positive electrode material.

[0083] In some embodiments, the positive electrode material includes a LiNi l Co m Mn n Al o O2 material, where 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.

[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 into a precipitant solution with deionized water. 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, and 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 dried in vacuum 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 then kept warm for 4 hours. The lactate precursor was then mixed with Li2CO3 at a molar ratio of 1:1.05, and then 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 positive electrode material prepared in Example 1 was subjected to SEM testing, and the results are shown in FIG1 .

[0108] Test Example 2

[0109] The positive electrode materials prepared in Examples 1 to 5 were subjected to XRD testing, and the results are shown in FIG2 .

[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, and the specific assembly process is as follows:

[0112] The positive electrode material of each embodiment was used as the positive electrode active material, and the positive electrode material, binder PVDF, and conductive agent Super P were weighed in a mass ratio of 8:1:1. The mixture was 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, the slurry was coated on a dry aluminum foil using a scraper (150 mm). The slurry was first placed in a blast drying oven at 80°C for 8 h, and then transferred to a vacuum drying oven at 120°C for 12 h. 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 positive electrode sheet was used as the positive electrode, metal lithium as the negative electrode, 1 mol / L LiPF6 dissolved in a mixed solvent of ethylene carbonate (EC) and dimethyl carbonate (DMC) (volume ratio = 1:1) as the electrolyte, Celgard 2400 polypropylene microporous membrane as the diaphragm, all materials were placed in a glove box filled with high-purity argon (O2 < 0.1ppm, H2O < 0.1ppm), assembled into a CR2032 button battery, and sealed with a sealing machine. Finally, the assembled CR2032 button battery was left to stand at room temperature for 12 hours for activation.

[0114] Test Example 4

[0115] The first constant current charge and discharge capacity and the discharge capacity after 100 cycles of the CR2032 button batteries prepared from 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] 3 and Table 1, it can be seen that the CR2032 button-type 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] The CR2032 button cells made of the positive electrode materials provided in Examples 1 to 5 were tested and cycled 5 times at rates of 0.1C, 0.2C, 0.5C, 1C, 2C and 0.5C, and the rate performance of the lithium battery was measured. The results are shown in Table 2 below.

[0121] Table 2

[0122]

[0123] 4 and Table 2, it can be seen that the CR2032 button-type batteries prepared from the positive electrode materials provided in Examples 1 to 5 have a high rate performance.

[0124] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described 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-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims, and the description and drawings may be used to interpret the contents of 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 comprising Ni 2+ 、Co 2+ , Mn 2+ and Al 3+ ; Adding a precipitant solution dropwise to the metal salt solution, wherein the precipitant solution includes lactic acid and ammonium carbonate to obtain a lactate precursor; The lactate precursor and the lithium source are sintered together.

2. The method for preparing the positive electrode material according to claim 1, characterized in that: In 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 / or, The time for adding the precipitant solution dropwise to the metal salt solution is 15 h to 30 h.

3. The method for preparing the positive electrode material according to claim 1, characterized in that: 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).

4. The method for preparing the positive electrode material according to claim 1, characterized in that: 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.

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

6. The method for preparing the positive electrode material according to any one of claims 1 to 4, 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 0.8-0.9, b is 0.05-0.1, c is 0.025-0.05, and d is 0.025-0.

05.

7. 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 6.

8. The positive electrode material according to claim 7, characterized in that Including chemical formula LiNi l Co m Mn n Al o O2 material, where 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.

9. A positive electrode sheet, characterized in that: It 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 7 to 8.

10. A lithium ion battery, characterized in that: Including the positive electrode sheet as described in claim 9.

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