Lithium ion battery cathode material, preparation method and application thereof

Abstract

The application relates to the technical field of positive electrode materials, in particular to a lithium ion battery positive electrode material and a preparation method and application thereof. The preparation method of the lithium ion battery positive electrode material comprises the following steps: uniformly mixing a ternary precursor containing sulfate and a lithium source to obtain premix; placing the premix in an oxygen-containing atmosphere to perform first sintering treatment to obtain first sintered material; placing the first sintered material in a hydrogen sulfide atmosphere and performing second sintering treatment at a temperature of 300-400 DEG C to obtain second sintered material; uniformly mixing the second sintered material with lithium powder and placing the second sintered material in an inert atmosphere to perform third sintering treatment to obtain the lithium ion battery positive electrode material. The application utilizes the phenomenon that the ternary precursor containing sulfate generates elemental sulfur when high-temperature treatment is performed in a hydrogen sulfide atmosphere, performs lithium matching sintering on the treated product to synthesize lithium sulfide coated on the surface of the material, converts the inactivated sulfate into lithium sulfide capable of reversibly deintercalating lithium ions, and thus the capacity and other electrochemical performances of the positive electrode material are improved.

Description

Technical Field

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

[0002] Currently, the technical routes for preparing lithium nickel cobalt aluminum oxide (NCA) are divided into co-precipitation method for preparing LiNi. 1-x-y Co x Al y The preparation of NCAOH involves two stages: the (OH)₂ precursor (NCAOH) and high-temperature sintering. During the NCAOH preparation process, since sulfates are typically used as raw materials, sulfate ions (SO₄²⁻) inevitably exist on the NCAOH surface. 2- Adsorption; simultaneously, in NCAOH, Al in the +3 valence state... 3+ Ni occupies the +2 valence in the layer plate 2+ and Co 2+ The position of the plate causes it to carry a partial positive charge, resulting in SO42-. 2- Intercalation into the NCAOH interlayer maintains electroneutrality, resulting in a high sulfur content in NCAOH. However, the high-temperature sintering temperature of NCA is generally ≤800℃, thus reducing SO4 content. 2- It is difficult to completely decompose, resulting in a high sulfur content in NCA. If sulfate remains in the cathode material, it will not only fail to provide capacity when the cathode material is made into a battery, but will also increase the battery's internal resistance and affect its electrochemical performance.

[0003] Washing with water or alkali can reduce the sulfur content in NCAOH to some extent, but water washing has limited effectiveness, while alkali washing severely corrodes the amphoteric Al matrix, leading to Al... 3+ Leaching disrupts the structural stability of the precursor. Therefore, there is an urgent need for a method that can effectively reduce the sulfate content in the NCAOH precursor while ensuring that the sintered cathode material still exhibits good electrochemical performance. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is to overcome the defect that the high residual amount of sulfate in the existing NCAOH leads to the reduction of the electrochemical performance of the cathode material, thereby providing a lithium-ion battery cathode material, its preparation method and application to solve the above problem.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] In a first aspect, the present invention provides a method for preparing a lithium-ion battery cathode material, comprising:

[0007] A premix is ​​obtained by mixing a ternary precursor containing sulfate and a lithium source.

[0008] The premixed material is placed in an oxygen-containing atmosphere for a first sintering treatment to obtain a sintered material;

[0009] A second sintering process is performed by placing a first sintering material in a hydrogen sulfide atmosphere and sintering it at a temperature of 300-400℃ to obtain a second sintering material.

[0010] The lithium-ion battery cathode material is obtained by mixing the secondary sintering material with lithium powder and then subjecting it to a third sintering treatment in an inert atmosphere.

[0011] Preferably, the ternary precursor is a nickel-cobalt-aluminum ternary precursor; optionally, the molar ratio of Ni, Co, and Al in the nickel-cobalt-aluminum ternary precursor is 90:5:5.

[0012] Preferably, the process of obtaining the nickel-cobalt-aluminum ternary precursor includes: mixing a nickel salt solution, a cobalt salt solution, and an aluminum salt solution to obtain a metal salt mixture, and then continuously introducing an alkaline solution and ammonia water into the metal salt mixture to maintain the pH of the system at 10-11.5 for co-precipitation reaction; wherein at least one of the nickel salt, cobalt salt, and aluminum salt is a sulfate.

[0013] Preferably, the concentration of the metal element in the nickel salt solution, cobalt salt solution, and aluminum salt solution is 2 mol / L.

[0014] And / or, the solvent in the nickel salt solution, cobalt salt solution, and aluminum salt solution is water;

[0015] And / or, the alkaline solution is a 25 wt% aqueous solution of sodium hydroxide;

[0016] And / or, the concentration of the ammonia solution is 10 wt%;

[0017] And / or, the volume ratio of the alkaline solution to ammonia is 1:(0.5-2.0).

[0018] Preferably, the temperature of the co-precipitation reaction is 55-65℃;

[0019] And / or, the duration of the coprecipitation reaction is 18-22 h;

[0020] And / or, the coprecipitation reaction is subjected to stirring;

[0021] And / or, the coprecipitation reaction is followed by aging treatment.

[0022] Preferably, the stirring speed is 300-700 rpm;

[0023] And / or, the aging process lasts for 8-12 hours;

[0024] And / or, the aging process is followed by solid-liquid separation, water washing, and drying.

[0025] Preferably, the lithium source includes lithium hydroxide;

[0026] And / or, the molar ratio of the metal element in the sulfate-containing ternary precursor to the lithium element in the lithium source is 1:1.02; the reason for the over-addition of lithium element is that lithium element is relatively easy to volatilize during the sintering process, and in order to compensate for this loss, the amount of lithium source is usually increased to ensure that the actual lithium content in the final product reaches the expected value.

[0027] And / or, the temperature of the first sintering treatment is 800-950℃;

[0028] And / or, the duration of the first sintering treatment is 8-12 hours;

[0029] And / or, the duration of the second sintering treatment is 5-10 hours.

[0030] Preferably, the mass ratio of the sintered material to lithium powder is 100:(0.5-1.5);

[0031] And / or, the inert atmosphere is nitrogen and / or argon;

[0032] And / or, the temperature of the third sintering treatment is 350-550℃;

[0033] And / or, the duration of the third sintering treatment is 5-10 hours.

[0034] Secondly, the present invention also provides a lithium-ion battery cathode material, which is prepared by the above-mentioned method for preparing lithium-ion battery cathode materials.

[0035] Thirdly, the present invention also provides the application of the above-mentioned lithium-ion battery cathode material in lithium-ion battery cathode sheets.

[0036] In this invention, the reason why the temperature of the second sintering process is not higher than 400°C is that if the hydrogen sulfide atmosphere is sintered in a high-temperature environment above 400°C, hydrogen sulfide decomposition (H2S=H2+S) may occur. That is, at temperatures above 400°C, the sulfur element in the sulfur element generated on the surface of the cathode material may come from hydrogen sulfide gas rather than sulfate ions in the precursor.

[0037] The technical solution of this invention has the following advantages:

[0038] A method for preparing a lithium-ion battery cathode material includes: mixing a ternary precursor containing sulfate and a lithium source to obtain a premix; subjecting the premix to a first sintering treatment in an oxygen-containing atmosphere to obtain a first sintered material; subjecting the first sintered material to a hydrogen sulfide atmosphere and subjecting it to a second sintering treatment at a temperature of 300-400°C to obtain a second sintered material; and mixing the second sintered material with lithium powder and subjecting it to a third sintering treatment in an inert atmosphere to obtain the lithium-ion battery cathode material. This invention utilizes the phenomenon that elemental sulfur is generated when the ternary precursor containing sulfate is subjected to high-temperature treatment in a hydrogen sulfide atmosphere. The product after high-temperature treatment is then subjected to further lithium-ion sintering to synthesize lithium sulfide to coat the material surface, converting inactive sulfate ions into reversibly intercalating and deintercalating lithium ions into lithium sulfide, thereby improving the electrochemical performance of the cathode material, such as capacity. Simultaneously, this invention eliminates the need for pretreatment in the precursor preparation process, reducing the complexity of the precursor manufacturing process and avoiding the leaching of metals during alkaline washing (alkaline washing can reduce the sulfate content in the precursor). Attached Figure Description

[0039] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0040] Figure 1 These are cycle curve test diagrams of the cathode materials prepared in Examples 1-3 and Comparative Examples 1-3 of the present invention. Detailed Implementation

[0041] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0042] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0043] Example 1

[0044] This embodiment provides a method for preparing a lithium-ion battery cathode material, the specific steps of which are as follows:

[0045] 1) Transfer 9 L of 2 mol / L nickel sulfate aqueous solution, 0.5 L of 2 mol / L cobalt sulfate aqueous solution, and 0.5 L of 2 mol / L aluminum sulfate aqueous solution to the reaction vessel respectively;

[0046] 2) 10wt% ammonia water and 25wt% sodium hydroxide aqueous solution were added dropwise to the reaction vessel (the dropwise volume ratio of sodium hydroxide to ammonia water aqueous solution was controlled to be 1:1). The pH value of the final solution in the reaction vessel was controlled to be 10.5. The temperature was controlled to be 60℃ and the stirring speed was 500rpm. The precipitation reaction was carried out for 20h, followed by aging for 10h to obtain the ternary precursor slurry.

[0047] 3) The ternary precursor slurry from step 2) was transferred to a centrifuge for centrifugation, then washed with pure water at a temperature of 65°C for 0.5 hours. After drying, Ni was obtained. 0.9 Co 0.05 Al 0.05 (OH)2 precursor;

[0048] 4) Mix 5.0 mol of the precursor obtained in step 3) with 5.1 mol of lithium hydroxide, and sinter at 800 °C for 10 h in an oxygen atmosphere to obtain a sintered LiNi. 0.9 Co 0.05 Al 0.05 O2;

[0049] 5) The first sintering material from step 4) is sintered at 400℃ in an H2S atmosphere for 5 hours to obtain the second sintering material;

[0050] 6) Weigh 100g of the sintered material from step 5) and 1.0g of nano-lithium powder, and sinter at 350℃ for 5h under a nitrogen atmosphere to obtain active Li2S-coated LiNi. 0.9 Co 0.05 Al 0.05 O2 cathode material.

[0051] Example 2

[0052] This embodiment provides a method for preparing a lithium-ion battery cathode material, the specific steps of which are as follows:

[0053] 1) Transfer 9 L of 2 mol / L nickel sulfate aqueous solution, 0.5 L of 2 mol / L cobalt sulfate aqueous solution, and 0.5 L of 2 mol / L aluminum sulfate aqueous solution to the reaction vessel respectively;

[0054] 2) 10wt% ammonia water and 25wt% sodium hydroxide aqueous solution were added dropwise to the reaction vessel (the dropwise volume ratio of sodium hydroxide to ammonia water aqueous solution was controlled to be 1:2). The pH value of the final solution in the reaction vessel was controlled to be 10.5. The temperature was controlled to be 55℃ and the stirring speed was 700rpm. The precipitation reaction was carried out for 18h, followed by aging for 12h to obtain the ternary precursor slurry.

[0055] 3) The ternary precursor slurry from step 2) was transferred to a centrifuge for centrifugation, then washed with pure water at a temperature of 65°C for 0.5 hours. After drying, Ni was obtained. 0.9 Co 0.05 Al 0.05 (OH)2 precursor;

[0056] 4) Mix 5.0 mol of the precursor obtained in step 3) with 5.1 mol of lithium hydroxide, and sinter at 950 °C for 8 h in an oxygen atmosphere to obtain a sintered LiNi. 0.9 Co 0.05 Al 0.05 O2;

[0057] 5) The first sintering material from step 4) is sintered at 350℃ in an H2S atmosphere for 10 hours to obtain the second sintering material;

[0058] 6) Weigh 100g of the sintered material from step 5) and 0.5g of nano-lithium powder, and sinter at 550℃ for 5h under a nitrogen atmosphere to obtain active Li2S-coated LiNi. 0.9 Co 0.05 Al 0.05 O2 cathode material.

[0059] Example 3

[0060] This embodiment provides a method for preparing a lithium-ion battery cathode material, the specific steps of which are as follows:

[0061] 1) Transfer 9 L of 2 mol / L nickel sulfate aqueous solution, 0.5 L of 2 mol / L cobalt sulfate aqueous solution, and 0.5 L of 2 mol / L aluminum sulfate aqueous solution to the reaction vessel respectively;

[0062] 2) 10wt% ammonia water and 25wt% sodium hydroxide aqueous solution were added dropwise to the reaction vessel (the dropwise volume ratio of sodium hydroxide to ammonia water was controlled to be 1:1.5). The pH value of the final solution in the reaction vessel was controlled to be 10.5. The temperature was controlled to be 65℃ and the stirring speed was 300rpm. The precipitation reaction was carried out for 22h, followed by aging for 8h to obtain the ternary precursor slurry.

[0063] 3) The ternary precursor slurry from step 2) was transferred to a centrifuge for centrifugation, then washed with pure water at a temperature of 65°C for 0.5 hours. After drying, Ni was obtained. 0.9 Co 0.05 Al 0.05 (OH)2 precursor;

[0064] 4) Mix 5.0 mol of the precursor obtained in step 3) with 5.1 mol of lithium hydroxide, and sinter at 890 °C for 12 h in an oxygen atmosphere to obtain a sintered LiNi. 0.9 Co 0.05 Al 0.05 O2;

[0065] 5) The first sintering material from step 4) is sintered at 300℃ in an H2S atmosphere for 7 hours to obtain the second sintering material;

[0066] 6) Weigh 100g of the sintered material from step 5) and 1.5g of nano-lithium powder, and sinter at 350℃ for 10h under a nitrogen atmosphere to obtain active Li2S-coated LiNi. 0.9 Co 0.05 Al 0.05 O2 cathode material.

[0067] Comparative Example 1

[0068] This comparative example provides a method for preparing a lithium-ion battery cathode material, the specific steps of which are as follows:

[0069] 1) Transfer 9 L of 2 mol / L nickel sulfate aqueous solution, 0.5 L of 2 mol / L cobalt sulfate aqueous solution, and 0.5 L of 2 mol / L aluminum sulfate aqueous solution to the reaction vessel respectively;

[0070] 2) 10wt% ammonia water and 25wt% sodium hydroxide aqueous solution were added dropwise to the reaction vessel (the volume ratio of sodium hydroxide to ammonia water aqueous solution was controlled to be 1:1). The pH value of the final solution in the reaction vessel was controlled to be 10.5. The temperature was controlled to be 60℃ and the stirring speed was 500rpm. The precipitation reaction was carried out for 20h, followed by aging for 10h to obtain the ternary precursor slurry.

[0071] 3) The ternary precursor slurry from step 2) was transferred to a centrifuge for centrifugation, then washed with pure water at a temperature of 65°C for 0.5 hours. After drying, Ni was obtained. 0.9 Co 0.05 Al 0.05 (OH)2 precursor;

[0072] 4) After uniformly mixing 5.0 mol of the precursor obtained in step 3) and 5.1 mol of lithium hydroxide, the mixture was sintered at 800 °C for 10 h in an oxygen atmosphere to achieve complete lithiation, thus obtaining the lithium-ion battery cathode material LiNi. 0.9 Co 0.05 Al 0.05 O2.

[0073] Comparative Example 2

[0074] This comparative example provides a method for preparing a lithium-ion battery cathode material, the specific steps of which are as follows:

[0075] 1) Transfer 9 L of 2 mol / L nickel sulfate aqueous solution, 0.5 L of 2 mol / L cobalt sulfate aqueous solution, and 0.5 L of 2 mol / L aluminum sulfate aqueous solution to the reaction vessel respectively;

[0076] 2) 10wt% ammonia water and 25wt% sodium hydroxide aqueous solution were added dropwise to the reaction vessel (the dropwise volume ratio of sodium hydroxide to ammonia water aqueous solution was controlled to be 1:1). The pH value of the final solution in the reaction vessel was controlled to be 10.5. The temperature was controlled to be 60℃ and the stirring speed was 500rpm. The precipitation reaction was carried out for 20h, followed by aging for 10h to obtain the ternary precursor slurry.

[0077] 3) The ternary precursor slurry from step 2) was transferred to a centrifuge for centrifugation, followed by washing with a 5 wt% sodium hydroxide aqueous solution, with the alkaline washing temperature controlled at 65°C and the washing time at 0.5 h. After drying, Ni was obtained. 0.9 Co 0.05 Al 0.05 (OH)2 precursor;

[0078] 4) After uniformly mixing 5.0 mol of the precursor obtained in step 3) and 5.1 mol of lithium hydroxide, the mixture was sintered at 800 °C for 10 h in an oxygen atmosphere to achieve complete lithiation, thus obtaining the lithium-ion battery cathode material LiNi. 0.9 Co 0.05 Al 0.05 O2.

[0079] Comparative Example 3

[0080] This comparative example provides a method for preparing a lithium-ion battery cathode material, the specific steps of which are as follows:

[0081] 1) Transfer 9 L of 2 mol / L nickel sulfate aqueous solution, 0.5 L of 2 mol / L cobalt sulfate aqueous solution, and 0.5 L of 2 mol / L aluminum sulfate aqueous solution to the reaction vessel respectively;

[0082] 2) 10wt% ammonia water and 25wt% sodium hydroxide aqueous solution were added dropwise to the reaction vessel (the dropwise volume ratio of sodium hydroxide to ammonia water aqueous solution was controlled to be 1:1). The pH value of the final solution in the reaction vessel was controlled to be 10.5. The temperature was controlled to be 60℃ and the stirring speed was 500rpm. The precipitation reaction was carried out for 20h, followed by aging for 10h to obtain the ternary precursor slurry.

[0083] 3) The ternary precursor slurry from step 2) was transferred to a centrifuge for centrifugation, then washed with pure water at a temperature of 65°C for 0.5 hours. After drying, Ni was obtained. 0.9 Co 0.05 Al 0.05 (OH)2 precursor;

[0084] 4) Mix 5.0 mol of the precursor obtained in step 3) with 5.1 mol of lithium hydroxide, and sinter at 800 °C for 10 h in an oxygen atmosphere to obtain a sintered LiNi. 0.9 Co 0.05 Al 0.05 O2;

[0085] 5) The first sintering material from step 4) is sintered at 200℃ in an H2S atmosphere for 5 hours to obtain the second sintering material;

[0086] 6) Weigh 100g of the secondary sintering material and 1.0g of nano-lithium powder from step 5), and sinter them at 350°C for 5 hours under a nitrogen atmosphere to obtain the positive electrode material for lithium-ion batteries.

[0087] Test Example 1

[0088] The cathode materials prepared in the above embodiments and comparative examples were subjected to qualitative analysis of elemental sulfur, quantitative analysis of sulfur content, and electrochemical performance testing.

[0089] The qualitative and quantitative testing methods for elemental sulfur are as follows: Weigh 1g of the cathode material and add it to 100mL of a mixed detection solution of N,N-dimethylformamide and hydrazine hydrate (volume ratio 1:1). If the mixed detection solution turns blue, it indicates that the cathode material contains elemental sulfur. The time from when the blue color appears until the mixed detection solution completely fades is recorded as t. The sulfur content of the analyte is calculated using formula 1) t = 7700m - 7.82 or formula 2) t = 3.76n / 0.00664 + 62.06. When t < 100 seconds, formula 1) is used; when t ≥ 100 seconds, formula 2) is used. In formulas 1) and 2), t represents the time required for the detection solution to completely fade from blue in seconds, and m and n represent the sulfur content of the analyte in milligrams. Dividing these values ​​by the weight of 1g of the cathode material and then converting the result to ppm yields the elemental sulfur content in the cathode material (1ppm = 0.001mg / g).

[0090] The electrochemical performance testing method is as follows: Positive electrode material, carbon black, and polyvinylidene fluoride (PVDF) are weighed and mixed at a mass ratio of 8:1:1. N-methylpyrrolidone (NMP, in an amount 10 times the mass of PVDF) is added to prepare the positive electrode slurry. The slurry is then uniformly coated onto aluminum foil (coating amount 6 mg / cm²). 2 Baking at 105℃ for 2 hours, the baked electrode sheets are cut and pressed in a tablet press at 25 MPa to cut out small round pieces (1.3 cm in diameter). The pieces are then assembled in a nitrogen atmosphere, where the moisture and oxygen content is less than 0.1 ppm. The small round pieces are placed on the positive electrode side of the coin cell casing, with the coated side facing away from the positive electrode. 50 μL of 1 mol / L electrolyte (EC, DMC, and EMC in a volume ratio of 1:1:1) is added. A Celgard 2500 separator is placed in the separator, and another 50 μL of electrolyte is added. Pure lithium sheets are then placed in the negative electrode, along with a gasket and spring. The coin cell negative electrode casing is then assembled to form a CR2032 coin cell, which is then tested for electrical performance using a Blue Electric testing system. The charge / discharge cycle was set as follows: the first cycle charged to 4.35V at a rate of 0.1C, then discharged to 2.8V at a rate of 0.1C; the second cycle charged and discharged at 0.5C; subsequently, 50 cycles were performed using a 1C charge and 1C discharge cycle to test the cycle retention rate. The test results are shown in Table 1 and... Figure 1 As shown.

[0091] Table 1

[0092]

[0093] In Examples 1-3, because the precursor preparation process involved water washing, the precursor contained SO4. 2- Residual residues, firstly after the precursor and lithium salt are sintered, SO4 2- The sulfur element in the Li2SO4 on the surface of the ternary material is converted into elemental sulfur by sintering in an H2S atmosphere. Finally, lithium powder is coated and sintered in an inert atmosphere to convert the elemental sulfur on the surface of the ternary material into Li2S that can carry lithium ions, thereby improving the capacity and cycle performance of the material.

[0094] Compared with Example 1, no sintering was performed under H2S atmosphere in Comparative Example 1. In the end, the S on the surface of the ternary material still exists in the form of Li2SO4. Li2SO4 has no capacity and lithium-ion transport ability, resulting in poor capacity and cycle performance.

[0095] Compared to Example 1, Comparative Example 2 involved alkaline washing during precursor preparation, which effectively removed SO42-. 2-While alkaline washing can remove alkali ions, it can also cause the amphoteric Al ions to dissolve, leading to a decrease in the structural stability of the cathode material. Furthermore, some alkali may remain on the surface of the cathode material, resulting in increased side reactions between the residual alkali and the electrolyte during charging and discharging, which in turn leads to the lowest cycle performance and specific capacity.

[0096] Compared to Example 1, although sintering was performed in an H2S atmosphere, the sintering temperature was low, and no elemental sulfur was generated on the surface of the ternary material after sintering. That is, sulfur still exists in the form of Li2SO4, resulting in lower material capacity and cycle performance.

[0097] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing a lithium-ion battery cathode material, characterized in that, include: A premix is ​​obtained by mixing a ternary precursor containing sulfate and a lithium source. The premixed material is placed in an oxygen-containing atmosphere for a first sintering treatment to obtain a sintered material; A second sintering process is performed by placing a first sintering material in a hydrogen sulfide atmosphere and sintering it at a temperature of 300-400℃ to obtain a second sintering material. The lithium-ion battery cathode material is obtained by mixing the second sintering material with lithium powder and then subjecting it to a third sintering treatment in an inert atmosphere. The ternary precursor is a nickel-cobalt-aluminum ternary precursor; The process of obtaining the nickel-cobalt-aluminum ternary precursor includes: mixing nickel salt solution, cobalt salt solution and aluminum salt solution to obtain a metal salt mixture, and then continuously introducing alkaline solution and ammonia water into the metal salt mixture to maintain the pH of the system at 10-11.5 for co-precipitation reaction; wherein, at least one of the nickel salt, cobalt salt and aluminum salt is a sulfate.

2. The preparation method according to claim 1, characterized in that, The molar ratio of Ni, Co, and Al in the nickel-cobalt-aluminum ternary precursor is 90:5:

5.

3. The preparation method according to claim 1, characterized in that, The concentration of the metal element in the nickel salt solution, cobalt salt solution, and aluminum salt solution is 2 mol / L. And / or, the solvent in the nickel salt solution, cobalt salt solution, and aluminum salt solution is water; And / or, the alkaline solution is a 25 wt% aqueous solution of sodium hydroxide; And / or, the concentration of the ammonia solution is 10 wt%; And / or, the volume ratio of the alkaline solution to ammonia is 1:(0.5-2.0).

4. The preparation method according to claim 1 or 2, characterized in that, The temperature for the coprecipitation reaction is 55-65℃; And / or, the duration of the coprecipitation reaction is 18-22 h; And / or, the coprecipitation reaction is subjected to stirring; And / or, the coprecipitation reaction is followed by aging treatment.

5. The preparation method according to claim 4, characterized in that, The stirring speed is 300-700 rpm; And / or, the aging treatment lasts for 8-12 hours; And / or, the aging process is followed by solid-liquid separation, water washing, and drying.

6. The preparation method according to claim 1 or 2, characterized in that, The lithium source includes lithium hydroxide; And / or, the molar ratio of the metal element in the sulfate-containing ternary precursor to the lithium element in the lithium source is 1:1.02; And / or, the temperature of the first sintering treatment is 800-950℃; And / or, the duration of the first sintering treatment is 8-12 h; And / or, the duration of the second sintering treatment is 5-10 h.

7. The preparation method according to claim 1 or 2, characterized in that, The mass ratio of the sintered material to lithium powder is 100:(0.5-1.5). And / or, the inert atmosphere is nitrogen and / or argon; And / or, the temperature of the third sintering treatment is 350-550℃; And / or, the duration of the third sintering treatment is 5-10 h.

8. A lithium-ion battery cathode material, characterized in that, It is prepared by the method for preparing lithium-ion battery cathode material according to any one of claims 1-7.

9. The application of the lithium-ion battery cathode material according to claim 8 in the cathode sheet of a lithium-ion battery.

Images