Positive electrode material, method for preparing same, and use thereof

Abstract

The present application relates to a positive electrode material, a method for preparing same, and use thereof. The method of the present application comprises the following steps: providing a metal salt solution comprising Ni2+, Co2+, Mn2+, and Al3+; dropwise adding a precipitant solution to the metal salt solution, so as to give a lactate precursor, the precipitant solution comprising lactic acid and ammonium carbonate; and co-sintering the lactate precursor and a lithium source. The method of the present application can achieve precise control of the molar proportions of nickel, cobalt, manganese, and aluminum to prepare a positive electrode material having a qualified chemical composition.

Description

Cathode materials, their preparation methods and applications Technical Field

[0001] This application relates to the field of lithium-ion battery technology, and in particular to a cathode material, its preparation method, and its application. Background Technology

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

[0003] However, in the traditional preparation methods of nickel-cobalt-manganese-aluminum quaternary high-nickel cathode materials, it is difficult to achieve precise control of the molar ratio of each element in nickel, cobalt, manganese, and aluminum to prepare cathode materials with the required chemical composition. Summary of the Invention

[0004] Therefore, it is necessary to provide a cathode material, its preparation method, and its application. The cathode material preparation method of this application can achieve precise control of the molar ratio of nickel, cobalt, manganese, and aluminum to prepare a cathode material with a satisfactory chemical composition.

[0005] In a first aspect, this application provides a method for preparing a cathode material, comprising the following steps:

[0006] A metal salt solution is provided, the metal salt solution comprising Ni 2+ Co 2+ Mn 2+ And Al 3+ ;

[0007] A precipitant solution comprising lactic acid and ammonium carbonate is added dropwise to the metal salt solution to obtain a lactate precursor.

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

[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 precipitant solution is added dropwise to the metal salt solution over a period of 15 to 30 hours.

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

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

[0013] In some embodiments, Ni in the metal salt solution 2+ Co 2+ Mn 2+ And Al 3+ The total molar concentration is 0.8 mol / L to 1.2 mol / 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 solutes in the metal salt solution include NiSO4·6H2O, CoSO4·7H2O, MnSO4·H2O, and Al2(SO4)3·18H2O.

[0016] In some embodiments, Ni in the metal salt solution 2+ Co 2+ Mn 2+ And Al 3+ The molar ratio is a:b:c:d, where 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] Secondly, this application also provides a cathode material, which is prepared by any of the cathode material preparation methods described above.

[0018] In some embodiments, the cathode material includes LiNi. l Co m Mn n Al o The material of O2 has l = 0.8–0.9, m = 0.05–0.1, n = 0.025–0.05, o = 0.025–0.05, and l + m + n + o = 1.

[0019] Thirdly, this application provides a positive electrode sheet, including a current collector and an active layer located on the surface of the current collector, the active layer comprising the positive electrode material described in any of the above claims.

[0020] Fourthly, this application provides a lithium-ion battery, including the positive electrode sheet described above.

[0021] In the above-mentioned method for preparing the cathode 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 is performed to obtain Ni 2+ Co 2+ Mn 2+ And Al 3+ The lactate precursor. Compared to traditional methods for preparing quaternary cathode materials using strong bases such as sodium hydroxide as precipitants for co-precipitation, the above-mentioned cathode material preparation method can achieve Ni 2+ Co 2+ Mn 2+ And Al 3+ The better co-precipitation effect can solve the problem of Al in traditional preparation methods. 3+ Rapid precipitation of nickel, cobalt, manganese, and aluminum leads to the problem of difficulty in precisely controlling the molar ratio of these elements. The cathode material preparation method of this application enables precise control of the molar ratio of nickel, cobalt, manganese, and aluminum to prepare cathode materials with the required chemical composition.

[0022] Furthermore, 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 coprecipitation process operates under milder conditions, reducing dependence on temperature, pressure, and reaction environment, thus minimizing uncertainties and making the process easier to control. Simultaneously, the milder process conditions help protect the product structure from damage during the reaction, maintaining its integrity and excellent properties. Furthermore, the milder operating conditions reduce reliance on expensive equipment suitable for strong base reactions, lowering investment costs for production facilities and enhancing the applicability and flexibility of the process.

[0023] Furthermore, by achieving precise control over the molar ratio of nickel, cobalt, manganese, and aluminum, it is possible to optimize the crystal structure and electrochemical performance of the cathode material, thereby improving the overall performance of lithium-ion batteries, such as capacity, cycle life, and rate performance. Attached Figure Description

[0024] Figure 1 is a SEM image of the high-nickel cathode material prepared in Example 1 of this application;

[0025] Figure 2 shows the XRD patterns of the high-nickel cathode materials prepared in Examples 1-5 of this application;

[0026] Figure 3 is a comparison of the cycle performance of the high-nickel cathode materials prepared in Examples 1-3 of this application;

[0027] Figure 4 is a comparison of the rate performance of the high-nickel cathode materials prepared in Examples 1 to 3 of this application. Detailed Implementation

[0028] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, a detailed description of specific embodiments of this application is provided below. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this 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 one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the 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 this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0031] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

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

[0033] Provide a metal salt solution, the metal salt solution including Ni 2+ Co 2+ Mn 2+ And Al 3+ ;

[0034] A precipitant solution, comprising lactic acid and ammonium carbonate, is added dropwise to a metal salt solution to obtain a lactate precursor.

[0035] The lactate precursor and lithium source are co-sintered.

[0036] In the above-mentioned method for preparing the cathode 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 is performed to obtain Ni 2+ Co 2+ Mn 2+ And Al 3+ The lactate precursor. Compared to traditional methods for preparing quaternary cathode materials using strong bases such as sodium hydroxide as precipitants for co-precipitation, the above-mentioned cathode material preparation method can achieve Ni 2+ Co 2+ Mn 2+ And Al 3+ The better co-precipitation effect can solve the problem of Al in traditional preparation methods. 3+ Rapid precipitation of nickel, cobalt, manganese, and aluminum leads to the problem of difficulty in precisely controlling the molar ratio of these elements. The cathode material preparation method of this application enables precise control of the molar ratio of nickel, cobalt, manganese, and aluminum to prepare cathode materials with the required chemical composition.

[0037] Furthermore, 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 coprecipitation process operates under milder conditions, reducing dependence on temperature, pressure, and reaction environment, thus minimizing uncertainties and making the process easier to control. Simultaneously, the milder process conditions help protect the product structure from damage during the reaction, maintaining its integrity and excellent properties. Furthermore, the milder operating conditions reduce reliance on expensive equipment suitable for strong base reactions, lowering investment costs for production facilities and enhancing the applicability and flexibility of the process.

[0038] Furthermore, by precisely controlling the molar ratio of nickel, cobalt, manganese, and aluminum, it is possible to optimize the crystal structure and electrochemical performance of the cathode material, thereby improving the overall performance of lithium-ion batteries, such as capacity, cycle life, and rate performance. Simultaneously, the relatively inexpensive transition metal Mn can be used to replace a small amount of Co in the cathode material, effectively avoiding the cost issues associated with dependence on Co.

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

[0040] During the dropwise addition of the precipitant solution to the metal salt solution, controlling the temperature of the metal salt solution to be between 30℃ and 40℃ achieves a good co-precipitation effect. Simultaneously, the co-precipitation operating conditions are relatively mild, reducing dependence on temperature, pressure, and reaction environment, and lowering uncertainties in the production process. Optionally, during the dropwise addition of the precipitant solution to the metal salt solution, the temperature of the metal salt solution can be controlled at 30℃, 32℃, 34℃, 36℃, 38℃, or 40℃; alternatively, the temperature of the metal salt solution can be controlled within any two of the aforementioned temperature ranges.

[0041] In some embodiments, the precipitant solution is added dropwise to the metal salt solution over a period of 15 to 30 hours.

[0042] Within the time range for adding the precipitant solution to the metal salt solution as described above, a longer addition time allows Ni to... 2+ Co 2+ Mn 2+ And Al 3+ Slower co-precipitation can achieve better co-precipitation results. Optionally, the time for adding the precipitant solution to the metal salt solution can be 15h, 18h, 20h, 22h, 25h, 28h, or 30h, or the time for adding the precipitant solution to the metal salt solution can be within any two of the above time ranges.

[0043] In some embodiments, stirring is carried out continuously 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 the range of any two of the above rates.

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

[0047] The lactate precursor was subjected to solid-liquid separation and drying.

[0048] In some of these implementations, the drying method is vacuum drying.

[0049] In some of these 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 any two of the above temperatures.

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

[0052] Optionally, the drying time is 24h, 26h, 28h, 30h, 32h, 34h or 36h, or the drying time can be within any two of the above times.

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

[0054] Ni in the above metal salt solution 2+ Co 2+ Mn 2+ And Al 3+ Within a certain range of the ratio of the total molar amount of lactic acid to the molar amount of lactic acid in the precipitant solution, a good co-precipitation effect can be achieved, thereby preparing the lactate precursor. Optionally, Ni in the metal salt solution 2+ Co 2+ Mn 2+ And Al 3+ The ratio of the total molar amount 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 ratio of Ni in the metal salt solution is... 2+ Co 2+ Mn 2+ And Al 3+ The ratio of the total molar amount 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, the molar ratio of lactic acid to ammonium carbonate in the precipitant solution is 1:(1 to 1.8).

[0056] Within the range of the molar ratio of lactic acid to ammonium carbonate in the above-mentioned precipitant solution, a good co-precipitation effect can be achieved, thereby preparing the lactate precursor. Optionally, the molar ratio of lactic acid to ammonium carbonate in the precipitant solution can be 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, Ni in the metal salt solution 2+ Co 2+ Mn 2+ And Al 3+ The total molar concentration is 0.8 mol / L to 1.2 mol / L.

[0058] Optionally, Ni in the metal salt solution 2+ Co 2+ Mn 2+ And Al 3+ The total molar concentration 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, in the metal salt solution, Ni 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. Alternatively, the total molar concentration of lactic acid and ammonium carbonate in the precipitant solution may also be within the range of any two of the above molar concentrations.

[0061] In some embodiments, the solutes in the metal salt solution include 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 and readily soluble in water, making them more suitable for preparing suspensions.

[0063] In some embodiments, Ni in the metal salt solution 2+ Co 2+ Mn 2+ And Al 3+ The molar ratio is a:b:c:d, where 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] Ni in the above metal salt solution 2+ Co 2+ Mn 2+ And Al 3+ Within the range of molar ratios, cathode materials with both high specific capacity and high 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 can be within the range of any two of the above values. Optionally, b is 0.05, 0.06, 0.07, 0.08, 0.09, or 0.1, or b can be within the range of any two of the above values. Optionally, c is 0.025, 0.03, 0.035, 0.04, 0.045, or 0.05, or c can be within the range of any two of the above values. Optionally, d is 0.025, 0.03, 0.035, 0.04, 0.045, or 0.05, or d can be within the range of any two of the above values.

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

[0066] The lactate precursor is subjected to a first sintering treatment;

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

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

[0069] Optionally, the molar ratio of lactate precursor to 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 lactate precursor to lithium source can be within any two of the above molar ratios.

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

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

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

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

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

[0075] Optionally, the first sintering treatment time is 3h, 3.2h, 3.4h, 3.6h, 3.8h, 4h, 4.2h, 4.4h, 4.6h, 4.8h or 5h, or the first sintering treatment time can be within 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 of 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 treatment is 4℃ / min, 4.5℃ / min, 5℃ / min, 5.5℃ / min or 6℃ / min, or the heating rate of the second sintering treatment may be within the range of any two of the above heating rates.

[0080] In some embodiments, the second sintering process takes 5 to 8 hours.

[0081] Optionally, the second sintering treatment time is 5h, 5.5h, 6h, 6.5h, 7h, 7.5h or 8h, or the second sintering treatment time can be within any two of the above times.

[0082] Another embodiment of this application provides a cathode material, which is prepared by any of the cathode material preparation methods described above.

[0083] In some embodiments, the cathode material includes LiNi. l Co m Mn n Al o The material of O2 has l = 0.8–0.9, m = 0.05–0.1, n = 0.025–0.05, o = 0.025–0.05, and l + m + n + o = 1.

[0084] The aforementioned high-nickel quaternary cathode material can simultaneously possess high specific capacity and high 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 be within 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 be within 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 be within 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 be within any two of the above values.

[0085] Another embodiment of this application provides a positive electrode sheet, including a current collector and an active layer located on the surface of the current collector, wherein the active layer includes the positive electrode material described above.

[0086] Another embodiment of this application provides a lithium-ion battery, including the above-described positive electrode.

[0087] The following are specific embodiments.

[0088] Example 1

[0089] Methods for preparing cathode materials:

[0090] (1) Weigh NiSO4·6H2O, CoSO4·7H2O, MnSO4·H2O, and Al2(SO4)3·18H2O sequentially according to a molar ratio of 0.83:0.07:0.05:0.025, dissolve them in a certain amount of deionized water to prepare a 1 mol / L metal salt solution, and then dissolve Ni in the metal salt solution according to the molar ratio of 0.83:0.07:0.05:0.025. 2+ Co 2+ Mn 2+ And Al 3+ The total molar amount of lactic acid and the molar ratio of ammonium carbonate are 1:1:1. Weigh the corresponding molar amounts of lactic acid and ammonium carbonate in sequence, and prepare 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. Under the conditions of 30°C and 1200r / min stirring, the precipitant solution was added dropwise to the metal salt solution and the reaction was continued for 21 hours.

[0092] (3) The product was filtered and washed, and then dried under 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 held for 4 h. Then, the lactate precursor and Li2CO3 were mixed at a molar ratio of 1:1.05, heated to 800°C at a heating rate of 5°C / min and held for 6 h to obtain LiNi. 0.83 Co 0.07 Mn 0.05 Al 0.05 O2 high-nickel cathode material.

[0094] Example 2

[0095] Methods for preparing cathode materials:

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

[0097] Example 3

[0098] Methods for preparing cathode materials:

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

[0100] Example 4

[0101] Methods for preparing cathode materials:

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

[0103] Example 5

[0104] Methods for preparing cathode materials:

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

[0106] Experimental Example 1

[0107] The cathode material prepared in Example 1 was subjected to SEM testing, and the results are shown in Figure 1.

[0108] Experimental Example 2

[0109] The cathode materials prepared in Examples 1 to 5 were subjected to XRD tests, and the results are shown in Figure 2.

[0110] Experimental Example 3

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

[0112] Using the positive electrode materials of each embodiment as positive electrode active materials, the positive electrode materials, binder PVDF, and conductive agent Super P were weighed at a mass ratio of 8:1:1 and placed in a 10mL beaker. After mixing evenly, an appropriate amount of N-methylpyrrolidone (NMP) was added and stirred into a uniform slurry. The slurry was then coated onto dry aluminum foil using a scraper (150mm). The foil was first placed in a forced-air drying oven at 80℃ for 8 hours, and then transferred to a vacuum drying oven at 120℃ for 12 hours. The completely dried electrode sheets were then processed into 12mm diameter circular positive electrode sheets using a stamping machine and weighed and transferred to a glove box for later use.

[0113] Using the prepared positive electrode sheet as the positive electrode and metallic lithium as the negative electrode, a 1 mol / L LiPF6 solution dissolved in a mixed solvent of ethylene carbonate (EC) and dimethyl carbonate (DMC) (volume ratio = 1:1) was used as the electrolyte. A Celgard 2400 polypropylene microporous membrane was used as the separator. All materials were placed in a glove box filled with high-purity argon gas (O2 < 0.1 ppm, H2O < 0.1 ppm) and assembled into a CR2032 coin cell. The coin cell was then sealed using a sealing machine. Finally, the assembled CR2032 coin cell was allowed to stand at room temperature for 12 hours for activation before use.

[0114] Test Example 4

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

[0116] Table 1

[0117] As can be seen from Figure 3 and Table 1, the CR2032 coin cells prepared from the cathode materials provided in Examples 1-5 have high specific capacity and cycle performance.

[0118] Experimental Example 5

[0119] The CR2032 coin cells prepared with the cathode materials provided in Examples 1 to 5 were tested by cycling 5 times at rates of 0.1C, 0.2C, 0.5C, 1C, 2C and 0.5C respectively. The rate performance of the lithium batteries was measured and the results are shown in Table 2 below.

[0120] Table 2

[0121] As can be seen from Figure 4 and Table 2, the CR2032 coin cells prepared from the cathode materials provided in Examples 1-5 have high rate performance.

[0122] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above 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.

[0123] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims, and the specification and drawings can be used to interpret the content of the claims.

Claims

1. A method for preparing a positive electrode material, characterized in that, Includes the following steps: A metal salt solution is provided, the metal salt solution comprising Ni 2+ Co 2+ Mn 2+ And Al 3+ ; A precipitant solution comprising lactic acid and ammonium carbonate is added dropwise to the metal salt solution to obtain a lactate precursor. The lactate precursor and the lithium source are co-sintered.

2. The method for preparing the cathode material according to claim 1, characterized in that, 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℃~40℃; and / or, The precipitant solution is added dropwise to the metal salt solution over a period of 15 to 30 hours.

3. The method for preparing the cathode material according to claim 1, characterized in that, Ni in metal salt solution 2+ Co 2+ Mn 2+ And Al 3+ The ratio of the total molar amount 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 to 1.8).

4. The method for preparing the cathode material according to claim 1, characterized in that, Ni in metal salt solution 2+ Co 2+ Mn 2+ And Al 3+ The total molar concentration is 0.8 mol / L to 1.2 mol / L; and / or, The total molar concentration of lactic acid and ammonium carbonate in the precipitant solution is 0.8 mol / L to 1.2 mol / L.

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

6. The method for preparing the cathode material according to any one of claims 1 to 4, characterized in that, Ni in metal salt solution 2+ Co 2+ Mn 2+ And Al 3+ The molar ratio is a:b:c:d, where 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, It is prepared by the method for preparing the cathode material according to any one of claims 1 to 6.

8. The cathode material according to claim 7, characterized in that, Including chemical formula LiNi l Co m Mn n Al o The material of O2 has l = 0.8–0.9, m = 0.05–0.1, n = 0.025–0.05, o = 0.025–0.05, and l + m + n + o = 1.

9. A positive electrode sheet, characterized in that, It includes a current collector and an active layer located on the surface of the current collector, the active layer comprising the positive electrode material according to any one of claims 7 to 8.

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

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