F, Ca co-doped lithium-rich manganese-based precursor, preparation method and application thereof

Abstract

The application discloses a kind of F, Ca double-doped lithium-rich manganese-based precursor and its preparation method and application.The preparation method includes the following steps: 1) preparation includes nickel element, manganese element, calcium element and optional cobalt element mixed salt solution;2) the mixed salt solution, precipitant solution and complexing agent solution are added into the bottom liquid in parallel, after co-precipitation reaction for a period of time t1, continue to carry out co-precipitation reaction for time t2 by adding sodium fluoride solution in parallel, and F, Ca double-doped lithium-rich manganese-based precursor is obtained.The calcium element and fluorine element are added in different stages of co-precipitation reaction in the application, first use nickel, manganese, calcium element to build crystal nucleus, then use the crystal nucleus as growth point, use mixed salt solution containing nickel element, manganese element and calcium element, precipitant solution, complexing agent solution and sodium fluoride solution to continue growing precursor on the surface of crystal nucleus, which can effectively control the element distribution in the precursor, so that fluorine element and calcium element can synergistically enhance the performance of the precursor, and the first effect and cycle performance of the positive electrode material prepared by using the precursor are greatly improved.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and specifically to an F / Ca dual-doped lithium-rich manganese-based precursor, its preparation method, and its application. Background Technology

[0002] In recent years, more and more car companies have announced their ultra-long range versions of models. However, on the one hand, the existing material system is getting closer and closer to its theoretical limit; on the other hand, ultra-long range has also led to a significant increase in battery costs.

[0003] Lithium-rich manganese-based materials are low-cost, high-performance materials. On the one hand, the theoretical capacity of lithium-rich manganese-based materials is much higher than that of existing material systems. On the other hand, lithium-rich manganese-based materials also have a higher discharge platform at higher voltages, which can further improve their actual capacity. Therefore, lithium-rich manganese-based materials have great development potential in the fields of aviation batteries and solid-state batteries.

[0004] However, existing conventional lithium-rich manganese-based materials have poor cycle stability and are difficult to release their theoretical performance in practical applications. Further improvements are urgently needed to promote their commercial development.

[0005] Improving the electrochemical performance of cathode materials prepared using lithium-rich manganese-based materials by doping the precursors is an effective method. For example, CN112701273B discloses a fluorine-doped lithium-rich manganese-based cathode material and its preparation method, wherein the lithium-rich manganese-based cathode material has the general chemical formula: xLi2MnO3·(1-x)LiMO 2-y F 2yWherein, 0.1≤x≤0.9, 0<y≤0.05, and M is one or more of Ni, Co, Mn, Cr, Fe, Ti, Mo, Ru, V, Nb, Zr, and Sn; the preparation method includes the following steps: 1) preparing a fluorine-doped lithium-rich manganese-based precursor: according to the above chemical formula, using a corresponding soluble metal salt, precipitant, soluble fluorine-containing compound, and water, a fluorine-doped lithium-rich manganese-based precursor is prepared by precipitation reaction at a certain system temperature; 2) preparing a fluorine-doped lithium-rich manganese-based cathode material: the fluorine-doped lithium-rich manganese-based precursor obtained in step 1) is uniformly mixed with a lithium salt, and the fluorine-doped lithium-rich manganese-based cathode material is obtained by pre-calcination and high-temperature sintering. This method uses a soluble fluorine-containing compound as a fluorine source, and fluorine doping is achieved simultaneously during the co-precipitation of the lithium-rich manganese-based precursor, resulting in good doping uniformity and significantly improved cycle performance of the lithium-rich material after doping. For example, CN112993260A discloses a doped ternary precursor, its preparation method, cathode material, and battery. The preparation method includes: mixing a fluoride salt with an alkaline solution to adjust the pH, adding a nickel-cobalt-manganese material, and reacting to obtain the doped ternary precursor. The molar amount of the metal element in the fluoride salt is 0.1% to 1% of the total molar amount of nickel, cobalt, and manganese in the nickel-cobalt-manganese material. This method utilizes the fluoride salt as a seed crystal introduced in the precursor stage, reacting with the nickel-cobalt-manganese material to obtain a ternary precursor doped with metal elements and fluorine. It features a simple preparation process, readily available raw materials, and ease of industrial production.

[0006] However, existing methods for element doping in precursors do not effectively control the distribution of elements in the precursors, resulting in the need for further improvement in the first-efficiency and cycle performance of the prepared cathode materials. Summary of the Invention

[0007] To address the aforementioned problems in the existing technology, the purpose of this invention is to propose an F, Ca dual-doped lithium-rich manganese-based precursor, its preparation method, and its application.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] In a first aspect, the present invention provides a method for preparing an F, Ca dual-doped lithium-rich manganese-based precursor, the preparation method comprising the following steps:

[0010] (1) Prepare a mixed salt solution containing nickel, manganese, calcium and optionally cobalt;

[0011] (2) The mixed salt solution, precipitant solution and complexing agent solution are added to the bottom liquid in parallel flow. After a period of time t1, sodium fluoride solution is added in parallel flow and the coprecipitation reaction is continued for time t2 to obtain F and Ca doped lithium-rich manganese-based precursor.

[0012] In this invention, "optional cobalt element" means that the mixed salt solution may or may not contain cobalt element.

[0013] The method of this invention involves adding calcium and fluorine elements at different stages of the co-precipitation reaction. First, a crystal nucleus is constructed using nickel, manganese, and calcium elements. Then, using this crystal nucleus as a growth point, a precursor is grown on the surface of the crystal nucleus using a mixed salt solution containing nickel, manganese, and calcium elements, a precipitant solution, a complexing agent solution, and a sodium fluoride solution. This method can effectively control the elemental distribution in the precursor, allowing fluorine and calcium elements to synergistically enhance each other and improve the performance of the precursor. The first-efficiency and cycle performance of the cathode material prepared using this precursor are significantly improved.

[0014] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. The technical objectives and beneficial effects of the present invention can be better achieved and realized through the following preferred technical solutions.

[0015] Preferably, in step (1), the molar ratio of nickel, manganese and calcium is x:y:z:a, where x is 0.25-0.4, y is 0-0.1, z is 0.6-0.75, a is 0.001-0.01, and x+y+z+a=1. For example, x can be 0.25, 0.27, 0.3, 0.32, 0.33, 0.35, 0.37, or 0.4, etc.; y can be 0, 0.005, 0.01, 0.015, 0.02, 0.025, 0.03, 0.035, 0.04, 0.045, 0.05, 0.055, 0.06, 0.065, 0.07, 0.075, 0.08, 0.09, or 0.1, etc.; z can be 0.6, 0.62, 0.63, 0.65, 0.68, 0.7, 0.72, 0.74, or 0.75, etc.; a can be 0.001, 0.002, 0.003, 0.005, 0.006, 0.008, 0.009, or 0.01, etc.

[0016] Preferably, in the mixed salt solution of step (1), the calcium element is derived from a calcium source, which includes at least one of calcium nitrate, calcium sulfate, calcium chloride, calcium citrate, and calcium gluconate.

[0017] Preferably, in the mixed salt solution of step (1), the nickel element is derived from a nickel source, which includes at least one of nickel nitrate, nickel sulfate, and nickel chloride.

[0018] Preferably, the cobalt element in step (1) is derived from a cobalt source, which includes at least one of cobalt nitrate, cobalt sulfate, and cobalt chloride.

[0019] Preferably, in the mixed salt solution of step (1), the manganese element is derived from a manganese source, which includes at least one of manganese nitrate, manganese sulfate, and manganese chloride.

[0020] Preferably, the total metal concentration in the mixed salt solution in step (1) is 2 mol / L-4 mol / L, for example, it can be 2 mol / L, 2.2 mol / L, 2.5 mol / L, 3 mol / L, 3.5 mol / L or 4 mol / L, etc.

[0021] As a preferred technical solution for the preparation method of the F, Ca dual-doped lithium-rich manganese-based precursor of the present invention, the precipitant in the precipitant solution in step (2) includes sodium hydroxide solution.

[0022] Preferably, the concentration of the precipitant solution in step (2) is 2 mol / L-5 mol / L, for example, it can be 2 mol / L, 2.5 mol / L, 3 mol / L, 3.5 mol / L, 4 mol / L, 4.5 mol / L or 5 mol / L, etc.

[0023] Preferably, the complexing agent solution in step (2) comprises any one or a combination of at least two of the following: ammonia solution, citric acid solution, sodium citrate solution, and tartaric acid solution. It should be noted that when using the above solutions in combination, acidic and alkaline solutions should be avoided.

[0024] Preferably, the concentration of the complexing agent solution in step (2) is 0.1 mol / L-0.3 mol / L, for example, it can be 0.1 mol / L, 0.15 mol / L, 0.2 mol / L, 0.25 mol / L or 0.3 mol / L, etc.

[0025] Preferably, the base liquid in step (2) is a mixed solution of water, sodium hydroxide and complexing agent solution.

[0026] Preferably, the pH value of the base solution is 11.0-12.0, for example, it can be 11.0, 11.2, 11.3, 11.5, 11.7, 11.8 or 12.0, etc.

[0027] Preferably, the complexing agent in the base liquid includes at least one of ammonia, citric acid, sodium citrate, and tartaric acid.

[0028] Preferably, the concentration of the complexing agent in the base solution is 0.1 mol / L-0.3 mol / L, for example, it can be 0.1 mol / L, 0.15 mol / L, 0.2 mol / L, 0.25 mol / L or 0.3 mol / L, etc.

[0029] Preferably, the concentration of the sodium fluoride solution in step (2) is 0.1 mol / L-0.3 mol / L, for example, it can be 0.1 mol / L, 0.15 mol / L, 0.2 mol / L, 0.25 mol / L or 0.3 mol / L, etc.

[0030] Preferably, the coprecipitation reaction in step (2) is carried out in a protective gas atmosphere.

[0031] The present invention does not specifically limit the type of protective gas, including but not limited to nitrogen (N2).

[0032] Preferably, the temperature of the coprecipitation reaction in step (2) is 25℃-80℃, for example, it can be 25℃, 30℃, 35℃, 40℃, 45℃, 50℃, 55℃, 60℃, 65℃, 70℃, 75℃ or 80℃, etc.

[0033] Preferably, during the coprecipitation reaction in step (2), the pH value of the reaction system is maintained in the range of 10.0-11.5. For example, the pH value can be 10.0, 10.2, 10.4, 10.5, 10.6, 10.8, 11.0, 11.1, 11.2, 11.3, 11.4 or 11.5.

[0034] Preferably, the coprecipitation reaction in step (2) is continuously stirred, and the stirring speed is 200r / min-400r / min, for example, it can be 200r / min, 230r / min, 260r / min, 280r / min, 300r / min, 325r / min, 350r / min, 375r / min or 400r / min, etc.

[0035] In the preferred embodiment of the method for preparing the F, Ca dual-doped lithium-rich manganese-based precursor of the present invention, t1:t2 = 1:(20-50), for example, it can be 1:20, 1:22, 1:25, 1:28, 1:30, 1:32, 1:34, 1:36, 1:38, 1:40, 1:43, 1:46, or 1:50, etc. t2 ≥ 60h, for example, it can be 60h, 62h, 65h, 68h, 70h, 72h, 75h, 78h, 80h, 83h, 86h, 88h, 90h, or 92h, etc.

[0036] In a second aspect, the present invention provides an F and Ca dual-doped lithium-rich manganese-based precursor, which is prepared by the method described in the first aspect.

[0037] Preferably, the morphology of the F, Ca dual-doped lithium-rich manganese-based precursor is spherical.

[0038] Thirdly, the present invention provides an F, Ca dual-doped lithium-rich manganese-based cathode material, wherein the F, Ca dual-doped lithium-rich manganese-based cathode material is prepared by using the F, Ca dual-doped lithium-rich manganese-based precursor described in the second aspect.

[0039] Preferably, the morphology of the F and Ca dual-doped lithium-rich manganese-based cathode material is spherical.

[0040] Fourthly, the present invention provides a method for preparing an F / Ca dual-doped lithium-rich manganese-based cathode material as described in the third aspect, the method comprising the following steps:

[0041] The F and Ca dual-doped lithium-rich manganese-based precursor was mixed with a lithium source and then calcined to obtain the F and Ca dual-doped lithium-rich manganese-based cathode material.

[0042] Preferably, the stoichiometric ratio of the F, Ca dual-doped lithium-rich manganese-based precursor to the lithium source is 1:(1.25-1.3), for example, it can be 1:1.25, 1:1.26, 1:1.27, 1:1.28, 1:1.29 or 1:1.3, etc.

[0043] Preferably, the calcination temperature is 700℃-900℃, for example, it can be 700℃, 720℃, 730℃, 740℃, 750℃, 760℃, 780℃, 800℃, 820℃, 830℃, 840℃, 850℃, 860℃, 880℃ or 900℃, etc.

[0044] Preferably, the calcination time is 8h-15h, for example, it can be 8h, 8.5h, 9h, 9.5h, 10h, 10.5h, 11h, 11.5h, 12h, 12.5h, 13h, 13.5h, 14h or 15h.

[0045] Fifthly, the present invention provides a lithium-ion battery comprising the F and Ca dual-doped lithium-rich manganese-based cathode material described in the third aspect.

[0046] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0047] Compared with existing technologies, the present invention has the following beneficial effects:

[0048] The method of this invention involves adding calcium and fluorine elements at different stages of the co-precipitation reaction. First, a crystal nucleus is constructed using nickel, manganese, and calcium elements. Then, using this crystal nucleus as a growth point, a precursor is grown on the surface of the crystal nucleus using a mixed salt solution containing nickel, manganese, and calcium elements, a precipitant solution, a complexing agent solution, and a sodium fluoride solution. This method can effectively control the elemental distribution in the precursor, allowing fluorine and calcium elements to synergistically enhance each other and improve the performance of the precursor. The first-efficiency and cycle performance of the cathode material prepared using this precursor are significantly improved. Detailed Implementation

[0049] The technical solution of the present invention will be further illustrated below through specific embodiments.

[0050] Example 1

[0051] This embodiment provides a method for preparing an F, Ca dual-doped lithium-rich manganese-based precursor, the preparation method comprising the following steps:

[0052] Step 1: Weigh out nickel chloride, manganese chloride and calcium citrate according to the stoichiometric ratio Ni:Mn:Ca = 0.2975:0.69625:0.00625, and prepare a 2 mol / L mixed salt solution.

[0053] Step 2: Add water, sodium hydroxide, and ammonia solution to the reactor as a base solution to make the pH of the base solution 12.0 and the ammonia concentration 0.3 mol / L. Introduce N2 and control the temperature at 70℃. Add the mixed salt solution from Step 1, 2 mol / L sodium hydroxide solution, and 0.3 mol / L ammonia solution to the base solution in parallel flow and stir continuously at 300 r / min. Maintain the pH of the reaction system within the range of 11.0-11.5. After reacting for 3 hours, add 0.1 mol / L sodium fluoride solution to the reactor in parallel flow. Continue to introduce the mixed salt solution, sodium hydroxide solution, and ammonia solution from Step 1, maintain stirring and pH within the range of 11.0-11.5, and continue the reaction for 90 hours. After washing, drying, and sieving, obtain spherical hydroxide, which is the F, Ca dual-doped lithium-rich manganese-based precursor.

[0054] This embodiment also provides an F / Ca dual-doped lithium-rich manganese-based cathode material, the preparation method of which includes the following steps:

[0055] The F and Ca dual-doped lithium-rich manganese-based material prepared above was mixed with LiOH at a stoichiometric ratio of 1:1.3, heated to 800℃, held at that temperature for 10 hours, and then cooled in the furnace to obtain a spherical lithium-rich manganese-based cathode material.

[0056] Example 2

[0057] This embodiment provides a method for preparing an F, Ca dual-doped lithium-rich manganese-based precursor, the preparation method comprising the following steps:

[0058] Step 1: Weigh out nickel nitrate, cobalt nitrate, manganese nitrate, and calcium nitrate according to the stoichiometric ratio Ni:Co:Mn:Ca = 0.27:0.05:0.67:0.01, and prepare a 3 mol / L mixed salt solution.

[0059] Step 2: Add water, sodium hydroxide, and ammonia solution to the reactor as the base solution, making the pH of the base solution 11.0 and the ammonia concentration 0.2 mol / L. Introduce N2 and control the temperature at 80℃. Add the mixed salt solution from Step 1, 4 mol / L sodium hydroxide solution, and 0.2 mol / L ammonia solution to the base solution in parallel flow, and continue stirring at 400 r / min to maintain the pH of the reaction system within the range of 10.0-10.5. After reacting for 3 hours, add 0.2 mol / L sodium fluoride solution to the reactor in parallel flow, while continuing to introduce the mixed salt solution, sodium hydroxide solution, and ammonia solution from Step 1, maintaining stirring and pH within the range of 10.0-10.5, and continue reacting for 80 hours. After washing, drying, and sieving, spherical hydroxide is obtained, which is the preparation of the F, Ca dual-doped lithium-rich manganese-based precursor.

[0060] This embodiment also provides an F / Ca dual-doped lithium-rich manganese-based cathode material, the preparation method of which includes the following steps:

[0061] The F and Ca dual-doped lithium-rich manganese-based material prepared above was mixed with Li2CO3 at a stoichiometric ratio of 1:1.26, heated to 750℃, held at that temperature for 14 hours, and then cooled in the furnace to obtain a near-spherical lithium-rich manganese-based cathode material.

[0062] Example 3

[0063] This embodiment provides a method for preparing an F, Ca dual-doped lithium-rich manganese-based precursor, the preparation method comprising the following steps:

[0064] Step 1: Weigh out nickel sulfate, cobalt sulfate, manganese sulfate and calcium sulfate according to the stoichiometric ratio Ni:Co:Mn:Ca = 0.342:0.03:0.62:0.008, and prepare a 4 mol / L mixed salt solution.

[0065] Step 2: Add water, sodium hydroxide, and ammonia solution to the reactor as the base solution, making the pH of the base solution 11.5 and the ammonia concentration 0.1 mol / L. Introduce N2 and control the temperature at 55℃. Add the mixed salt solution from Step 1, 3 mol / L sodium hydroxide solution, and 0.25 mol / L ammonia solution to the base solution in parallel flow, and continue stirring at 200 r / min to maintain the pH of the reaction system within the range of 10.2-10.7. After reacting for 2 hours, add 0.3 mol / L sodium fluoride solution to the reactor in parallel flow, while continuing to introduce the mixed salt solution, sodium hydroxide solution, and ammonia solution from Step 1, maintaining stirring and the pH within the range of 10.2-10.7, and continue reacting for 60 hours. After washing, drying, and sieving, spherical hydroxides are obtained, which is the preparation of the F, Ca dual-doped lithium-rich manganese-based precursor.

[0066] This embodiment also provides an F / Ca dual-doped lithium-rich manganese-based cathode material, the preparation method of which includes the following steps:

[0067] The F and Ca dual-doped lithium-rich manganese-based material prepared above was mixed with LiOH at a stoichiometric ratio of 1:1.25, heated to 900℃, held at that temperature for 8 hours, and then cooled in the furnace to obtain a near-spherical lithium-rich manganese-based cathode material.

[0068] Example 4

[0069] The difference between this embodiment and Embodiment 1 is that the times 3h and 90h in step 2 are replaced with 6h and 87h, respectively.

[0070] Example 5

[0071] The difference between this embodiment and Embodiment 1 is that the times 3h and 90h in step 2 are replaced with 1.5h and 91.5h, respectively.

[0072] Comparative Example 1

[0073] The difference between this comparative example and Example 1 is that step 2 is as follows: water, sodium hydroxide, and ammonia solution are added to the reaction vessel as a base solution to make the pH of the base solution 12.0 and the ammonia concentration 0.3 mol / L. N2 is introduced and the temperature is controlled at 70°C. The mixed salt solution from step 1, 2 mol / L sodium hydroxide solution, 0.3 mol / L ammonia solution, and 0.1 mol / L sodium fluoride solution are added to the base solution in parallel flow and stirred continuously at a speed of 300 r / min to maintain the pH of the reaction system in the range of 11.0-11.5. The reaction is carried out for 93 h. After washing, drying, and sieving, F and Ca dual-doped lithium-rich manganese-based precursor is obtained.

[0074] Battery assembly:

[0075] A 7% (w / w) polyvinylidene fluoride (PVDF) solution was prepared using N-methylpyrrolidone as a solvent. The positive electrode material, PVDF, and conductive carbon black provided in Examples 1-5 and Comparative Example 1 were mixed uniformly at a mass ratio of 95:2:3. The mixture was then coated onto aluminum foil. The coated electrode was placed in a vacuum drying oven at 90°C and vacuum-dried for 4 hours, then rolled to a surface density of 4 mg / cm³. 2 -7mg / cm 2 For backup, a lithium metal sheet is used as the counter electrode, and a 1 mol / L LiPF6 three-component mixed solvent is used as the electrolyte in a mixture of EC:DMC:EMC = 1:1:1 (volume ratio). The mixture is then assembled into a 2032 type coin cell in an argon-filled glove box.

[0076] Performance testing:

[0077] The test conditions were 2.0-4.5V, 0.2C, and the test results are shown in Table 1.

[0078] Table 1

[0079]

[0080] As shown in Table 1, the method of the present invention adds calcium and fluorine elements at different stages of the co-precipitation reaction. First, a crystal nucleus is constructed using nickel, manganese, and calcium elements. Then, using this crystal nucleus as a growth point, a precursor is further grown on the surface of the crystal nucleus using a mixed salt solution containing nickel, manganese, and calcium elements, a precipitant solution, a complexing agent solution, and a sodium fluoride solution. This can effectively control the elemental distribution in the precursor, allowing fluorine and calcium elements to synergistically enhance each other and improve the performance of the precursor. The first-efficiency and cycle performance of the cathode material prepared using this precursor are significantly improved.

[0081] Meanwhile, a comparison between Example 1 and Examples 4-5 shows that both excessively large and excessively small nickel-cobalt-manganese-calcium cores will affect the material properties.

[0082] A comparison of Example 1 and Comparative Example 1 shows that forming a nickel-cobalt-manganese-calcium core first, and then continuing the reaction on it, is beneficial to improving the overall performance of the material.

[0083] The applicant declares that the detailed method of the present invention is illustrated by the above embodiments, but the present invention is not limited to the above detailed method, that is, it does not mean that the present invention must rely on the above detailed method to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing an F / Ca dual-doped lithium-rich manganese-based precursor, characterized in that, The preparation method includes the following steps: (1) Prepare a mixed salt solution containing nickel, manganese and calcium; or, prepare a mixed salt solution containing nickel, manganese, calcium and cobalt. In step (1), the molar ratio of nickel, cobalt, manganese and calcium is x:y:z:a, where x is 0.25-0.4, y is 0-0.1, z is 0.6-0.75, a is 0.001-0.01, and x+y+z+a=1; (2) The mixed salt solution, precipitant solution and complexing agent solution are added to the bottom liquid in parallel flow. After a period of time t1, sodium fluoride solution is added in parallel flow and the coprecipitation reaction is continued for time t2 to obtain F and Ca double-doped lithium-rich manganese-based precursor. During the coprecipitation reaction described in step (2), the pH value of the reaction system is maintained in the range of 10.0-11.5; t1: t2=1:(20-50), t2≥60h.

2. The preparation method according to claim 1, characterized in that, In the mixed salt solution of step (1), the calcium element comes from a calcium source, which includes at least one of calcium nitrate, calcium sulfate, calcium chloride, calcium citrate, and calcium gluconate.

3. The preparation method according to claim 1, characterized in that, In the mixed salt solution of step (1), the nickel element comes from a nickel source, which includes at least one of nickel nitrate, nickel sulfate and nickel chloride.

4. The preparation method according to claim 1, characterized in that, The cobalt element in step (1) is derived from a cobalt source, which includes at least one of cobalt nitrate, cobalt sulfate, and cobalt chloride.

5. The preparation method according to claim 1, characterized in that, In the mixed salt solution of step (1), the manganese element comes from a manganese source, which includes at least one of manganese nitrate, manganese sulfate and manganese chloride.

6. The preparation method according to claim 1, characterized in that, The total metal concentration in the mixed salt solution in step (1) is 2 mol / L-4 mol / L.

7. The preparation method according to claim 1, characterized in that, The precipitant in the precipitant solution in step (2) includes sodium hydroxide solution.

8. The preparation method according to claim 1, characterized in that, The concentration of the precipitant solution in step (2) is 2 mol / L-5 mol / L.

9. The preparation method according to claim 1, characterized in that, The complexing agent solution in step (2) includes any one or a combination of at least two of the following: ammonia solution, citric acid solution, sodium citrate solution and tartaric acid solution.

10. The preparation method according to claim 1, characterized in that, The concentration of the complexing agent solution in step (2) is 0.1 mol / L-0.3 mol / L.

11. The preparation method according to claim 1, characterized in that, The base liquid in step (2) is a mixture of water, sodium hydroxide and complexing agent solution.

12. The preparation method according to claim 1, characterized in that, The pH value of the base solution is 11.0-12.

0.

13. The preparation method according to claim 1, characterized in that, The complexing agent in the base liquid includes at least one of ammonia, citric acid, sodium citrate, and tartaric acid.

14. The preparation method according to claim 1, characterized in that, The concentration of the complexing agent in the substrate is 0.1 mol / L to 0.3 mol / L.

15. The preparation method according to claim 1, characterized in that, The concentration of the sodium fluoride solution in step (2) is 0.1 mol / L-0.3 mol / L.

16. The preparation method according to claim 1, characterized in that, The coprecipitation reaction in step (2) is carried out under a protective gas atmosphere.

17. The preparation method according to claim 1, characterized in that, The temperature of the coprecipitation reaction in step (2) is 25℃-80℃.

18. The preparation method according to claim 1, characterized in that, During the coprecipitation reaction in step (2), the stirring is carried out continuously at a speed of 200 r / min-400 r / min.

19. An F, Ca dual-doped lithium-rich manganese-based precursor, characterized in that, The F, Ca dual-doped lithium-rich manganese-based precursor is prepared by the method described in any one of claims 1-18.

20. The F, Ca dual-doped lithium-rich manganese-based precursor according to claim 19, characterized in that, The morphology of the F and Ca dual-doped lithium-rich manganese-based precursor is spherical.

21. An F / Ca dual-doped lithium-rich manganese-based cathode material, characterized in that, The F, Ca dual-doped lithium-rich manganese-based cathode material is prepared by using the F, Ca dual-doped lithium-rich manganese-based precursor as described in claim 19 or 20.

22. The F / Ca dual-doped lithium-rich manganese-based cathode material according to claim 21, characterized in that, The morphology of the F and Ca dual-doped lithium-rich manganese-based cathode material is spherical.

23. A method for preparing the F, Ca dual-doped lithium-rich manganese-based cathode material as described in claim 21 or 22, characterized in that, The preparation method includes the following steps: The F and Ca dual-doped lithium-rich manganese-based precursor was mixed with a lithium source and then calcined to obtain the F and Ca dual-doped lithium-rich manganese-based cathode material.

24. The preparation method according to claim 23, characterized in that, The stoichiometric ratio of the F, Ca dual-doped lithium-rich manganese-based precursor to the lithium source is 1:(1.25-1.3).

25. The preparation method according to claim 23, characterized in that, The calcination temperature is 700℃-900℃.

26. The preparation method according to claim 23, characterized in that, The calcination time is 8h-15h.

27. A lithium-ion battery, characterized in that, The lithium-ion battery includes the F, Ca dual-doped lithium-rich manganese-based cathode material as described in claim 21 or 22.

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