A low-sodium sulfur-rich-lithium manganese-based carbonate precursor, a preparation method and application thereof

Abstract

The application provides a low-sodium sulfur-rich-lithium manganese-based carbonate precursor and a preparation method and application thereof, and the preparation method comprises the following steps: simultaneously introducing a nickel-cobalt-manganese mixed solution, a precipitant and a complexing agent into a bottom solution to perform a co-precipitation reaction; after the co-precipitation reaction is completed, aging is performed in an aging solution to obtain the low-sodium sulfur-rich-lithium manganese-based carbonate precursor; and the aging solution comprises an ammonium salt and a lipid organic solvent. The application helps to weaken the interlayer force of the carbonate precursor particles by aging in the aging solution, thereby increasing the distance between the particle layers, opening the Na + and NH4 + replacement channels between the particle layers, effectively reducing the sodium impurity content in the precursor material, and thus preparing a low-sodium sulfur-rich-lithium manganese-based carbonate precursor, and improving the stability and safety of the subsequent positive electrode material.

Description

Technical Field

[0001] This invention belongs to the field of battery materials technology, and relates to a lithium-rich manganese-based precursor, particularly a low-sodium-sulfur lithium-rich manganese-based carbonate precursor and its preparation method and application. Background Technology

[0002] Lithium-ion batteries are widely used in portable laptops, smartphones, and electric vehicles due to their high energy conversion efficiency, long cycle life, and environmental friendliness, making them a key research and development area for large-scale energy storage power stations. Lithium-rich manganese-based precursors are the main raw materials for synthesizing lithium-rich manganese-based battery materials, and their physicochemical properties directly affect battery performance.

[0003] Coprecipitation is currently the mainstream method for preparing lithium-rich manganese-based precursors, primarily using hydroxide and carbonate systems. However, in the coprecipitation process of lithium-rich manganese-based carbonate precursors, due to the high manganese content, the primary particles tend to grow more densely, making it easy for sodium and sulfate ions to be trapped between the precursor crystal layers during the reaction. These ions are difficult to remove during subsequent washing. Ultimately, the excessive sodium impurities remaining in the precursor will occupy some lithium-ion sites during the subsequent cathode sintering process, leading to irreversible capacity reduction and performance degradation of the lithium-rich manganese-based cathode material. Furthermore, residual sulfur will affect the safety performance of the subsequent battery. Therefore, reducing the sodium and sulfur impurity content of lithium-rich manganese carbonate precursors is crucial for improving the performance of lithium-rich manganese-based cathode materials.

[0004] CN113979486A discloses a washing method for carbonate precursors, which involves washing the carbonate precursors by adding the acidic additive boric acid. This process is simple and low-cost, but it can only remove sodium and sulfur residues on the surface of the particles and cannot remove sodium and sulfur encapsulated inside the crystals. The overall removal effect is not obvious, and the acidic additive has a significant impact on the surface morphology and structure of the precursor.

[0005] CN111217409A discloses a washing method for a cathode material precursor, which designs a washing device including a cathode chamber, a mixing chamber, and an anode chamber separated by a cation-selective permeable membrane and an anion-selective permeable membrane in sequence. The precursor slurry is placed in the washing device for treatment, which can effectively reduce the sodium and sulfur content of the precursor product. Although the device has a good removal effect, it requires an additional washing device on the basis of existing washing equipment, and the cation and anion membranes need to be maintained and replaced regularly, which greatly increases the overall operating cost and makes it difficult to use in industrial mass production.

[0006] Therefore, there is a need to provide a low-sodium-sulfur-rich lithium-manganese-based carbonate precursor that is simple to process, has good sodium and sulfur removal effect, and is easy to produce industrially, as well as its preparation method and application. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the present invention aims to provide a low-sodium, sulfur-rich, lithium-manganese-based carbonate precursor, its preparation method, and its applications. The preparation method weakens the interlayer forces between carbonate precursor particles, thereby increasing the distance between particle layers and opening up the Na+ between the particle layers. + and NH4 + The substitution channel effectively reduced the sodium impurity content in the precursor material, thereby preparing a low-sodium, sulfur-rich, lithium-manganese-based carbonate precursor, which improved the stability and safety of the subsequent cathode material.

[0008] To achieve this objective, the present invention adopts the following technical solution:

[0009] In a first aspect, the present invention provides a method for preparing a low-sodium, sulfur-rich, lithium-manganese-based carbonate precursor, the method comprising the following steps:

[0010] A nickel-cobalt-manganese mixed solution, a precipitant, and a complexing agent are simultaneously introduced into the base solution to carry out a coprecipitation reaction. After the coprecipitation reaction is completed, the solution is aged to obtain a low-sodium, sulfur-rich, lithium-based manganese carbonate precursor.

[0011] The aging solution includes ammonium salts and lipid organic solvents.

[0012] This invention prepares a low-sodium, sulfur-rich, lithium-manganese-based carbonate precursor by aging in an aging solution, thereby improving the stability and safety of subsequent cathode materials. The ammonium salt in the aging solution provides a weakly alkaline environment, maintaining a relatively stable pH value and preventing excessive system fluctuations from affecting subsequent performance, while also providing sufficient NH4+. + It can be used to replace some of the residual Na in the precursor. + Furthermore, the intermolecular forces of lipid organic solvents help weaken the interlayer forces of carbonate precursor particles, thereby increasing the distance between particle lamellae and opening up the Na+ between particle lamellae. + and NH4 + The displacement channels effectively reduce the sodium impurity content in the precursor material.

[0013] Preferably, the lipid organic solvent includes any one or a combination of at least two of diethyl oxalate, acetic anhydride, or methyl formate. Typical but non-limiting combinations include a combination of diethyl oxalate and acetic anhydride, a combination of acetic anhydride and methyl formate, a combination of diethyl oxalate and methyl formate, or a combination of diethyl oxalate, acetic anhydride, and methyl formate.

[0014] Preferably, the volume concentration of lipid organic solvents in the aging solution is 0.5-3%, for example, it can be 0.5%, 1%, 1.5%, 2%, 2.5% or 3%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0015] Preferably, the ammonium salt includes any one or a combination of at least two of ammonium bicarbonate, ammonium carbonate, or ammonium oxalate. Typical but non-limiting combinations include a combination of ammonium bicarbonate and ammonium carbonate, a combination of ammonium carbonate and ammonium oxalate, a combination of ammonium bicarbonate and ammonium oxalate, or a combination of ammonium bicarbonate, ammonium carbonate, and ammonium oxalate.

[0016] Preferably, the mass concentration of ammonium salt in the aging solution is 1-30 g / L, for example, it can be 1 g / L, 5 g / L, 10 g / L, 15 g / L, 20 g / L, 25 g / L or 30 g / L, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0017] In this invention, aging refers to aging the remaining slurry after removing the supernatant from the co-precipitation reaction.

[0018] Preferably, the aging temperature is 50-70°C, for example, 50°C, 55°C, 60°C, 65°C or 70°C, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0019] If the aging temperature is too low, it will not be conducive to the function of ammonium salt and organic solvent; if the aging temperature is too high, it will destroy the structure of the precursor particles.

[0020] Preferably, the aging time is 5-10 hours, for example, 5 hours, 6 hours, 8 hours, 9 hours or 10 hours, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0021] Preferably, the base liquid is an alkaline aqueous solution.

[0022] Preferably, the solute in the alkaline aqueous solution includes sodium carbonate and / or sodium bicarbonate.

[0023] Preferably, the pH value of the base solution is ≤9, for example, it can be 6, 7, 7.5, 8, 8.5 or 9, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0024] Preferably, the temperature of the coprecipitation reaction is 40-60℃, for example, 40℃, 45℃, 50℃, 55℃ or 60℃, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0025] Preferably, the pH value of the coprecipitation reaction is 7-9, for example, it can be 7, 7.5, 8, 8.5 or 9, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0026] Preferably, the coprecipitation reaction is carried out under stirring conditions of 500-1000 rpm, for example, 500 rpm, 600 rpm, 800 rpm, 900 rpm or 1000 rpm, but not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0027] Preferably, the precipitant comprises sodium carbonate and / or sodium bicarbonate.

[0028] This invention does not impose further restrictions on the rate of addition of the precipitant, as long as the pH value of the coprecipitation reaction is 7-9.

[0029] Preferably, the complexing agent comprises any one or a combination of at least two of ammonia, ammonium bicarbonate, ammonium carbonate, or ammonium oxalate. Typical but non-limiting combinations include ammonia and ammonium bicarbonate, ammonium bicarbonate and ammonium carbonate, ammonium carbonate and ammonium oxalate, ammonia, ammonium bicarbonate and ammonium carbonate, ammonium bicarbonate, ammonium carbonate and ammonium oxalate, or ammonia, ammonium bicarbonate, ammonium carbonate and ammonium oxalate.

[0030] This invention does not specifically limit the flow rate and concentration of the complexing agent, as long as the concentration of the complexing agent in the system during the coprecipitation reaction can be maintained at 0.5-3 mol / L. For example, it can be 0.5 mol / L, 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L or 3 mol / L, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0031] Preferably, the molar ratio of nickel, cobalt, and manganese in the nickel-cobalt-manganese mixed solution is x:y:z, where x+y+z=1, 0.25≤x≤0.35, y>0, and 0.6≤z≤0.7.

[0032] The values ​​of x satisfy 0.25≤x≤0.35, for example, 0.25, 0.28, 0.3, 0.32 or 0.35; the values ​​of z satisfy 0.6≤z≤0.7, for example, 0.6, 0.62, 0.65, 0.68 or 0.7; and the values ​​of x, y, and z satisfy x+y+z=1.

[0033] Preferably, the metal salts in the nickel-cobalt-manganese mixed solution include nickel salts, cobalt salts, and manganese salts, and the concentration of the metal salts in the nickel-cobalt-manganese mixed solution is 80-120 g / L.

[0034] For example, the nickel salts include, but are not limited to, nickel sulfate.

[0035] For example, the cobalt salt includes, but is not limited to, cobalt sulfate.

[0036] For example, the manganese salt includes, but is not limited to, manganese sulfate.

[0037] In this invention, the concentration of the metal salt in the nickel-cobalt-manganese mixed solution is 80-120 g / L, for example, it can be 80 g / L, 90 g / L, 100 g / L, 110 g / L or 120 g / L, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0038] Preferably, the preparation method further includes solid-liquid separation after aging, followed by washing and drying.

[0039] Preferably, the washing includes washing with pure water 3-7 times, for example, 3 times, 4 times, 5 times, 6 times or 7 times, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0040] Preferably, the drying temperature is 80-130℃, for example, it can be 80℃, 90℃, 100℃, 110℃, 120℃ or 130℃, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0041] In a second aspect, the present invention provides a low-sodium-sulfur-rich lithium-manganese-based carbonate precursor, which is prepared by the preparation method described in the first aspect.

[0042] Preferably, the sodium impurity content in the low-sodium sulfur-rich lithium manganese-based carbonate precursor is ≤600ppm, and the sulfur impurity content is ≤700ppm.

[0043] Thirdly, the present invention provides a low-sodium-sulfur, lithium-rich manganese-based cathode material, which is prepared from the low-sodium-sulfur, lithium-rich manganese-based carbonate precursor described in the second aspect.

[0044] 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.

[0045] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0046] This invention prepares a low-sodium, sulfur-rich, lithium-manganese-based carbonate precursor by aging in an aging solution, thereby improving the stability and safety of subsequent cathode materials. The ammonium salt in the aging solution provides a weakly alkaline environment, maintaining a relatively stable pH value and preventing excessive system fluctuations from affecting subsequent performance, while also providing sufficient NH4. + It can be used to replace some of the residual Na in the precursor. + Furthermore, the intermolecular forces of lipid organic solvents help weaken the interlayer forces of carbonate precursor particles, thereby increasing the distance between particle lamellae and opening up the Na+ between particle lamellae. + and NH4 + The displacement channels effectively reduce the sodium impurity content in the precursor material. Detailed Implementation

[0047] The technical solution of the present invention will be further illustrated below through specific embodiments.

[0048] Example 1

[0049] This embodiment provides a method for preparing a low-sodium, sulfur-rich, lithium-manganese-based carbonate precursor, the preparation method comprising the following steps:

[0050] (1) An alkaline aqueous solution was added to the reactor as the base liquid. The nickel-cobalt-manganese mixed solution, precipitant and complexing agent were simultaneously and concurrently added to the reactor by a peristaltic pump. The stirring speed was controlled at 800 rpm, and the co-precipitation reaction was carried out at 52℃ and pH 7.5.

[0051] The solute in the alkaline aqueous solution is sodium carbonate, and the pH value of the bottom solution is 7.5.

[0052] The molar ratio of nickel, cobalt and manganese in the nickel-cobalt-manganese mixed solution is 0.3:0.05:0.65, and the metal salts therein include nickel sulfate, cobalt sulfate and manganese sulfate, and the concentration of the metal salts is 100 g / L.

[0053] The precipitant is sodium carbonate, and the complexing agent is ammonia; the concentration of the complexing agent in the co-precipitation reaction system is 1 mol / L.

[0054] (2) After the coprecipitation reaction is completed, the mixture is allowed to stand and the supernatant is extracted. The remaining substances are aged in the aging solution.

[0055] The aging solution is a mixture of ammonium salt, lipid organic solvent and water. The ammonium salt is ammonium bicarbonate and the lipid organic solvent is diethyl oxalate. The mass concentration of the ammonium salt in the aging solution is 20 g / L and the volume concentration of the lipid organic solvent in the aging solution is 1.5%.

[0056] The aging process was carried out at a temperature of 60°C for 6 hours.

[0057] (3) The aged slurry was filtered and washed with pure water 5 times, and then dried at 120°C to obtain a low-sodium sulfur-rich lithium manganese-based carbonate precursor.

[0058] Example 2

[0059] This embodiment provides a method for preparing a low-sodium, sulfur-rich, lithium-manganese-based carbonate precursor, the preparation method comprising the following steps:

[0060] (1) An alkaline aqueous solution was added to the reactor as the base liquid. The nickel-cobalt-manganese mixed solution, precipitant and complexing agent were simultaneously and concurrently added to the reactor by a peristaltic pump. The stirring speed was controlled at 700 rpm, and the co-precipitation reaction was carried out at 55°C and pH 8.5.

[0061] The solute in the alkaline aqueous solution is sodium bicarbonate, and the pH value of the bottom solution is 8.5.

[0062] The nickel-cobalt-manganese mixed solution has a molar ratio of nickel, cobalt and manganese of 0.35:0.05:0.6, and the metal salts therein include nickel sulfate, cobalt sulfate and manganese sulfate, with a metal salt concentration of 105 g / L.

[0063] The precipitant is sodium bicarbonate, and the complexing agent is ammonia; the concentration of the complexing agent in the co-precipitation reaction system is 1 mol / L.

[0064] (2) After the coprecipitation reaction is completed, the mixture is allowed to stand and the supernatant is extracted. The remaining substances are aged in the aging solution.

[0065] The aging solution is a mixture of ammonium salt, lipid organic solvent and water. The ammonium salt is ammonium bicarbonate and the lipid organic solvent is diethyl oxalate. The mass concentration of the ammonium salt in the aging solution is 25 g / L and the volume concentration of the lipid organic solvent in the aging solution is 2%.

[0066] The aging process was carried out at a temperature of 60°C for 6 hours.

[0067] (3) The aged slurry was filtered and washed with pure water four times, and then dried at 120°C to obtain a low-sodium sulfur-rich lithium manganese-based carbonate precursor.

[0068] Example 3

[0069] This embodiment provides a method for preparing a low-sodium, sulfur-rich, lithium-manganese-based carbonate precursor, the preparation method comprising the following steps:

[0070] (1) An alkaline aqueous solution was added to the reactor as the base liquid. The nickel-cobalt-manganese mixed solution, precipitant and complexing agent were simultaneously and concurrently added to the reactor by a peristaltic pump. The stirring speed was controlled at 900 rpm, and the co-precipitation reaction was carried out at 50°C and pH 9.

[0071] The solute in the alkaline aqueous solution is sodium carbonate, and the pH value of the bottom solution is 9.

[0072] The molar ratio of nickel, cobalt and manganese in the nickel-cobalt-manganese mixed solution is 0.3:0.05:0.65, and the metal salts therein include nickel sulfate, cobalt sulfate and manganese sulfate, and the concentration of the metal salts is 100 g / L.

[0073] The precipitant is sodium carbonate, and the complexing agent is ammonia; the concentration of the complexing agent in the co-precipitation reaction system is 1 mol / L.

[0074] (2) After the coprecipitation reaction is completed, the mixture is allowed to stand and the supernatant is extracted. The remaining substances are aged in the aging solution.

[0075] The aging solution is a mixture of ammonium salt, lipid organic solvent and water. The ammonium salt is ammonium bicarbonate and the lipid organic solvent is diethyl oxalate. The mass concentration of the ammonium salt in the aging solution is 12 g / L and the volume concentration of the lipid organic solvent in the aging solution is 0.8%.

[0076] The aging process was carried out at a temperature of 60°C for 6 hours.

[0077] (3) The aged slurry was filtered and washed with pure water 5 times, and then dried at 120°C to obtain a low-sodium sulfur-rich lithium manganese-based carbonate precursor.

[0078] Example 4

[0079] This embodiment provides a method for preparing a low-sodium, sulfur-rich, lithium-manganese-based carbonate precursor, the preparation method comprising the following steps:

[0080] (1) An alkaline aqueous solution was added to the reactor as the base liquid. The nickel-cobalt-manganese mixed solution, precipitant and complexing agent were simultaneously and concurrently added to the reactor by a peristaltic pump. The stirring speed was controlled at 800 rpm, and the co-precipitation reaction was carried out at 55°C and pH 7.5.

[0081] The solute in the alkaline aqueous solution is sodium carbonate, and the pH value of the bottom solution is 7.5.

[0082] The nickel-cobalt-manganese mixed solution has a molar ratio of nickel, cobalt and manganese of 0.25:0.05:0.7, and the metal salts therein include nickel sulfate, cobalt sulfate and manganese sulfate, with a metal salt concentration of 90 g / L.

[0083] The precipitant is sodium carbonate, and the complexing agent is ammonium bicarbonate; the concentration of the complexing agent in the co-precipitation reaction system is 1 mol / L.

[0084] (2) After the coprecipitation reaction is completed, the mixture is allowed to stand and the supernatant is extracted. The remaining substances are aged in the aging solution.

[0085] The aging solution is a mixture of ammonium salt, lipid organic solvent and water. The ammonium salt is ammonium carbonate and the lipid organic solvent is diethyl oxalate. The mass concentration of the ammonium salt in the aging solution is 20 g / L and the volume concentration of the lipid organic solvent in the aging solution is 1.5%.

[0086] The aging process was carried out at a temperature of 55°C for 8 hours.

[0087] (3) The aged slurry was filtered and washed with pure water 5 times, and then dried at 100°C to obtain a low-sodium sulfur-rich lithium manganese-based carbonate precursor.

[0088] Example 5

[0089] This embodiment provides a method for preparing a low-sodium, sulfur-rich, lithium-manganese-based carbonate precursor, the preparation method comprising the following steps:

[0090] (1) An alkaline aqueous solution was added to the reactor as the base liquid. The nickel-cobalt-manganese mixed solution, precipitant and complexing agent were simultaneously and concurrently added to the reactor by a peristaltic pump. The stirring speed was controlled at 500 rpm, and the co-precipitation reaction was carried out at 40°C and pH 7.

[0091] The solute in the alkaline aqueous solution is sodium carbonate, and the pH value of the bottom solution is 7.

[0092] The molar ratio of nickel, cobalt and manganese in the nickel-cobalt-manganese mixed solution is 0.3:0.05:0.65, and the metal salts therein include nickel sulfate, cobalt sulfate and manganese sulfate, and the concentration of the metal salts is 80 g / L.

[0093] (2) After the coprecipitation reaction is completed, the mixture is allowed to stand and the supernatant is extracted. The remaining substances are aged in the aging solution.

[0094] The aging solution is a mixture of ammonium salt, lipid organic solvent and water. The ammonium salt is ammonium bicarbonate and the lipid organic solvent is diethyl oxalate. The mass concentration of the ammonium salt in the aging solution is 1 g / L and the volume concentration of the lipid organic solvent in the aging solution is 0.5%.

[0095] The aging temperature was 50°C and the time was 10 hours.

[0096] (3) The aged slurry was filtered and washed with pure water 5 times, and then dried at 80°C to obtain a low-sodium sulfur-rich lithium manganese-based carbonate precursor.

[0097] Example 6

[0098] This embodiment provides a method for preparing a low-sodium, sulfur-rich, lithium-manganese-based carbonate precursor, the preparation method comprising the following steps:

[0099] (1) An alkaline aqueous solution was added to the reactor as the base liquid. The nickel-cobalt-manganese mixed solution, precipitant and complexing agent were simultaneously and concurrently added to the reactor by a peristaltic pump. The stirring speed was controlled at 1000 rpm, and the co-precipitation reaction was carried out at 60℃ and pH 9.

[0100] The solute in the alkaline aqueous solution is sodium carbonate, and the pH value of the bottom solution is 9.

[0101] The nickel-cobalt-manganese mixed solution has a molar ratio of nickel, cobalt and manganese of 0.3:0.05:0.65, and the metal salts therein include nickel sulfate, cobalt sulfate and manganese sulfate, with a metal salt concentration of 120 g / L.

[0102] (2) After the coprecipitation reaction is completed, the mixture is allowed to stand and the supernatant is extracted. The remaining substances are aged in the aging solution.

[0103] The aging solution is a mixture of ammonium salt, lipid organic solvent and water. The ammonium salt is ammonium bicarbonate and the lipid organic solvent is diethyl oxalate. The mass concentration of the ammonium salt in the aging solution is 30 g / L and the volume concentration of the lipid organic solvent in the aging solution is 3%.

[0104] The aging process was carried out at a temperature of 70°C for 5 hours.

[0105] (3) The aged slurry was filtered and washed with pure water 5 times, and then dried at 130°C to obtain a low-sodium sulfur-rich lithium manganese-based carbonate precursor.

[0106] Example 7

[0107] This embodiment provides a method for preparing a low-sodium sulfur-rich lithium manganese-based carbonate precursor. Except for replacing the lipid organic solvent with acetic anhydride, the rest is the same as in Example 1.

[0108] Example 8

[0109] This embodiment provides a method for preparing a low-sodium, sulfur-rich, lithium-manganese-based carbonate precursor. Except for replacing the lipid organic solvent with methyl formate, the method is the same as in Example 1.

[0110] Example 9

[0111] This embodiment provides a method for preparing a low-sodium, sulfur-rich, lithium-manganese-based carbonate precursor. Except for replacing the lipid organic solvent with methyl acetate, the method is the same as in Example 1.

[0112] Example 10

[0113] This embodiment provides a method for preparing a low-sodium, sulfur-rich, lithium-manganese-based carbonate precursor, which is the same as in Example 1 except that the aging temperature is 45°C.

[0114] Example 11

[0115] This embodiment provides a method for preparing a low-sodium sulfur-rich lithium manganese-based carbonate precursor, which is the same as in Example 1 except that the aging temperature is 75°C.

[0116] The preparation method provided in this embodiment has a high aging temperature, which may cause structural damage to the low-sodium sulfur-rich lithium manganese-based carbonate precursor.

[0117] Comparative Example 1

[0118] This comparative example provides a method for preparing a lithium-rich manganese-based carbonate precursor, which is the same as that in Example 1 except that aging is not performed.

[0119] Comparative Example 2

[0120] This comparative example provides a method for preparing a lithium-rich manganese-based carbonate precursor. Except for the aging solution, which is only ammonium bicarbonate with a mass concentration of 20 g / L, the rest is the same as in Example 1.

[0121] Comparative Example 3

[0122] This comparative example provides a method for preparing a lithium-rich manganese-based carbonate precursor. Except for the aging solution being only diethyl oxalate, the rest is the same as in Example 1.

[0123] Performance Characterization

[0124] The sodium and sulfur contents in the precursors obtained from the above embodiments and comparative examples were measured, and the results are shown in Table 1.

[0125] Table 1

[0126]

[0127]

[0128] As shown in Table 1, in conjunction with Example 1 and Comparative Examples 1-3, aging after the co-precipitation reaction can effectively remove sodium and sulfur impurities, and the choice of aging solution is crucial. Ammonium salt and lipid organic solvent alone cannot effectively remove sodium and sulfur as aging solutions. Lipid organic solvent opens the exchange channels between sodium ions and sulfate ions by increasing the spacing of the precursor particle layers, while ammonium salt provides a stable aging system and sufficient ammonium ions, facilitating the replacement of sodium ions. The synergistic presence of both ultimately achieves the efficient removal of sodium and sulfur impurities.

[0129] Furthermore, in conjunction with Examples 1-3, during the aging process of the low-sodium-sulfur, lithium-rich manganese-based carbonate precursor of the present invention, the concentration of the aging solution affects the removal efficiency of sodium sulfur in subsequent washing. If the concentration of the aging solution is too low, the intermolecular forces are weak, and the spacing between the precursor particle layers cannot be effectively increased, weakening the replacement effect of sodium sulfur encapsulated inside the particles. If the concentration of the aging solution is too high, the removal efficiency of sodium sulfur is not significantly improved, but excessive organic solvent will be adsorbed on the particle surface, thereby affecting the physicochemical properties of the precursor, wasting organic solvent, and increasing production costs.

[0130] In summary, this invention prepares a low-sodium, sulfur-rich, lithium-manganese-based carbonate precursor by aging in an aging solution, thereby improving the stability and safety of subsequent cathode materials. The ammonium salt in the aging solution provides a weakly alkaline environment, maintaining a relatively stable pH value and preventing excessive system fluctuations from affecting subsequent performance, while also providing sufficient NH4+. + It can be used to replace some of the residual Na in the precursor. + Furthermore, the intermolecular forces of lipid organic solvents help weaken the interlayer forces of carbonate precursor particles, thereby increasing the distance between particle lamellae and opening up the Na+ between particle lamellae. + and NH4 + The displacement channels effectively reduce the sodium impurity content in the precursor material.

[0131] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a low-sodium, sulfur-rich, lithium-manganese-based carbonate precursor, characterized in that, The preparation method includes the following steps: A nickel-cobalt-manganese mixed solution, a precipitant, and a complexing agent are simultaneously introduced into the base solution to carry out a coprecipitation reaction. After the coprecipitation reaction is completed, the solution is aged to obtain a low-sodium, sulfur-rich, lithium-based manganese carbonate precursor. The aging solution includes ammonium salts and lipid organic solvents; The lipid organic solvent includes any one or a combination of at least two of diethyl oxalate, acetic anhydride, or methyl formate. The mass concentration of ammonium salt in the aging solution is 1-30 g / L.

2. The preparation method according to claim 1, characterized in that, The volume concentration of lipid organic solvents in the aging solution is 0.5-3%.

3. The preparation method according to claim 1, characterized in that, The ammonium salt includes any one or a combination of at least two of ammonium bicarbonate, ammonium carbonate, or ammonium oxalate.

4. The preparation method according to claim 1, characterized in that, The aging temperature is 50-70℃.

5. The preparation method according to claim 1, characterized in that, The aging time is 5-10 hours.

6. The preparation method according to claim 1, characterized in that, The substrate solution is an alkaline aqueous solution.

7. The preparation method according to claim 6, characterized in that, The solutes in the alkaline aqueous solution include sodium carbonate and / or sodium bicarbonate.

8. The preparation method according to claim 1, characterized in that, The pH value of the base solution is ≤9.

9. The preparation method according to claim 1, characterized in that, The temperature of the coprecipitation reaction is 40-60℃.

10. The preparation method according to claim 1, characterized in that, The pH value of the coprecipitation reaction is 7-9.

11. The preparation method according to claim 1, characterized in that, The coprecipitation reaction was carried out under stirring conditions at a speed of 500-1000 rpm.

12. The preparation method according to claim 1, characterized in that, The precipitant includes sodium carbonate and / or sodium bicarbonate.

13. The preparation method according to claim 1, characterized in that, The complexing agent includes any one or a combination of at least two of ammonia, ammonium bicarbonate, ammonium carbonate, or ammonium oxalate.

14. The preparation method according to claim 1, characterized in that, The nickel-cobalt-manganese mixed solution has a nickel-cobalt-manganese molar ratio of x:y:z, where x+y+z=1, 0.25≤x≤0.35, y>0, and 0.6≤z≤0.

7.

15. The preparation method according to claim 1, characterized in that, The metal salts in the nickel-cobalt-manganese mixed solution include nickel salts, cobalt salts, and manganese salts, and the concentration of the metal salts in the nickel-cobalt-manganese mixed solution is 80-120 g / L.

16. A low-sodium, sulfur-rich, lithium-manganese-based carbonate precursor, characterized in that, The low-sodium sulfur-rich lithium manganese-based carbonate precursor is prepared by the preparation method according to any one of claims 1-15.

17. A low-sodium, sulfur-rich, lithium-manganese-based cathode material, characterized in that, The low-sodium sulfur-rich lithium manganese-based cathode material is prepared from the low-sodium sulfur-rich lithium manganese-based carbonate precursor described in claim 16.

Images