CN111640936B - Lithium-rich manganese-based positive electrode material, preparation method thereof and lithium ion battery - Google Patents
Lithium-rich manganese-based positive electrode material, preparation method thereof and lithium ion battery Download PDFInfo
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Abstract
The invention discloses a lithium-rich manganese-based positive electrode material, a preparation method thereof and a lithium ion battery, wherein the preparation method of the lithium-rich manganese-based positive electrode material comprises the following steps: s1 precursor preparation: dissolving required nickel salt, cobalt salt and manganese salt in deionized water according to a molar ratio of nickel ions to cobalt ions to manganese ions of 0.146:0.058:0.579 to form a mixed metal salt solution, then respectively pumping the mixed metal salt solution and a precipitator solution into a reaction kettle by using a peristaltic pump to mix, adding a complexing agent to adjust the pH value, continuously stirring for reaction to generate a precipitate, and washing, drying, crushing and sieving the precipitate after the reaction is completed to obtain a precursor; s2, calcining: grinding and mixing the precursor and a lithium source, and then placing the mixture in a muffle furnace to sinter to obtain a target anode material Li [ Li ] Li 0.217 Ni 0.146 Co 0.058 Mn 0.579 ]O 2 . The precursor is prepared by adopting a coprecipitation method and then calcined with a lithium source to obtain the cathode material, the process is simple, the production cost is low, and the target cathode material obtained under the molar ratio has strong structural stability, good cycle stability and good rate capability.
Description
Technical Field
The invention relates to the technical field of lithium ion batteries, in particular to a lithium-rich manganese-based positive electrode material, a preparation method thereof and a lithium ion battery.
Background
In the field of green chemical power sources, compared with traditional lead-acid batteries, zinc-manganese batteries, nickel-cadmium batteries and nickel-hydrogen batteries, lithium ion batteries are one of the main power batteries of new energy automobiles at present due to the advantages of high energy density, long cycle life, environmental friendliness and the like. The lithium ion battery mainly comprises a positive electrode material, a negative electrode material, electrolyte, a diaphragm and a shell, wherein the positive electrode material is a core component of the lithium ion battery and directly determines the overall performance of the lithium ion battery.
Currently, lithium cobaltate, ternary materials, lithium iron phosphate and lithium manganate are commercialized as positive electrode materials, and the energy density of the lithium iron phosphate and the lithium manganate is low; although the energy density of lithium cobaltate and ternary materials is greatly improved, the metal cobalt is in short supply and expensive, and the safety is still to be further improved.
The lithium-rich manganese-based positive electrode material has the advantages of high specific capacity, low cost and environmental friendliness, and is widely concerned and researched by scientific research institutions and the industry. The preparation method of the lithium-rich manganese-based anode material is similar to that of a ternary material, and comprises a coprecipitation method, a sol-gel method, a high-temperature solid phase method and the like, and the practical industrial application mainly comprises the high-temperature solid phase method and the coprecipitation method which are simple in process flow and convenient to control.
However, the lithium-rich manganese-based positive electrode material still faces many problems, of which the first coulombic efficiency is low, the voltage drop is severe, the rate performance is poor, and the like are major problems. The preparation method of the lithium-rich manganese-based cathode material still has the problems of complex process, high production cost, lower cycling stability and rate capability and poorer product structure stability.
Disclosure of Invention
In view of the above technical drawbacks, a first object of the present invention is to provide a method for preparing a lithium-rich manganese-based positive electrode material, which has a simple process and a stable structure.
In order to realize the purpose, the invention provides the following technical scheme:
a preparation method of a lithium-rich manganese-based positive electrode material comprises the following steps:
s1 precursor preparation: dissolving required nickel salt, cobalt salt and manganese salt into deionized water according to the molar ratio of nickel ions to cobalt ions to manganese ions of 0.146 to 0.058 to form a mixed metal salt solution, then respectively pumping the mixed metal salt solution and a precipitator solution into a reaction kettle by using a peristaltic pump to mix, adding a complexing agent to adjust the pH value, continuously stirring for reaction to generate a precipitate, aging after complete reaction, washing, drying, crushing and sieving the aged precipitate to obtain a precursor;
s2, calcining: mixing the precursor with a lithium sourceGrinding, mixing, placing in a muffle furnace, and sintering to obtain the target anode material Li [ Li ] 0.217 Ni 0.146 Co 0.058 Mn 0.579 ]O 2 。
By adopting the technical scheme, the precursor is prepared by adopting a coprecipitation method and then is calcined with a lithium source to obtain the cathode material, the process is simple, the production cost is low, and the target cathode material obtained under the molar ratio has strong structural stability, good cycling stability and good rate capability.
The invention is further configured to: the total concentration of metal ions of the mixed metal salt solution in the S1 precursor preparation is 1-3mol/L, and the nickel salt, the cobalt salt and the manganese salt are all sulfates.
The invention is further configured to: the precipitant is one or more of sodium carbonate and sodium hydroxide, and the molar concentration of the precipitant solution is the same as the molar concentration of the total metal ions in the mixed metal salt solution.
The invention is further configured to: the complexing agent is one or more of ammonia water and ammonium bicarbonate, and the molar concentration of the complexing agent is 5-10mol/L.
The invention is further configured to: in the preparation of the S1 precursor, the feeding speed of a peristaltic pump is 200-2000mL/h; the temperature of water bath in the reaction kettle is 40-70 ℃, the stirring speed is 400-900rpm, the pH value is 7-12, and the aging is carried out for 6-12h; the drying temperature of the precipitate is 80-120 ℃, and the drying time is 6-12h.
The invention is further configured to: the lithium source is one or more of lithium hydroxide, lithium carbonate, lithium acetate and lithium nitrate, and the lithium source is mixed with the precursor in an excess of 1-15% according to the proportion of the final product.
The invention is further configured to: in the calcination of S2, the sintering temperature rise rate is 2-10 ℃/min, the pre-sintering is carried out for 5-10h at 400-700 ℃, and then the calcination is carried out for 10-18h at 750-1000 ℃; the muffle furnace is an oxygen atmosphere muffle furnace.
The invention is further configured to: the method also comprises S3 surface modification, and the specific process is as follows:
firstly, immersing a positive electrode material into a 0.2mol/L nitric acid solution for soaking for 2-3h, filtering, washing with water, and drying to obtain an acid-treated positive electrode material;
step two, uniformly mixing 1-1.4 parts of dibenzoyl peroxide, 0.1-0.15 part of acetanilide and 60-80 parts of dimethylbenzene to prepare an initiator solution, uniformly mixing 20-24 parts of liquid fluororubber, 8-10 parts of maleic anhydride and 150-200 parts of dimethylbenzene, heating to 80-85 ℃, dropwise adding the initiator solution, finishing dripping for 40-50min, heating to 90-95 ℃ after finishing dripping, reacting for 2-3h, adding anhydrous methanol to precipitate a product, and drying at 40-45 ℃ to constant weight to obtain a modifier;
thirdly, mixing 1-1.5 parts of modifier, 80-100 parts of dimethylbenzene and 80-100 parts of acetone, adding 10-15 parts of nano titanium dioxide, shearing and dispersing at the speed of 800-1000r/min for 5min, then heating to 60-65 ℃, carrying out reflux reaction for 2-3h, filtering, washing with alcohol, drying and crushing to obtain modified nano titanium dioxide;
and fourthly, uniformly mixing 1-1.3 parts of modified nano titanium dioxide, 80-100 parts of water and 8-10 parts of acid-treated cathode material, evaporating to dryness at 80-85 ℃ to obtain mixed powder, heating to 500-550 ℃, and continuing for 5-6 hours to obtain the modified cathode material.
By adopting the technical scheme, the nano titanium dioxide is modified, so that the agglomeration problem is solved, and the nano titanium dioxide is easy to disperse in an aqueous solution; on the other hand, the nano titanium dioxide is easy to coat on the surface of the anode material, and has high dielectric constant, thereby being beneficial to improving the rate capability of the anode material.
The second purpose of the invention is to provide a lithium-rich manganese-based cathode material, which is prepared by the preparation method.
By adopting the technical scheme, the microscopic morphology of the layered lithium-rich manganese-based positive electrode material is single crystal particles which are uniformly distributed and have the particle size of 200-300nm, the structural stability is high, and the compaction density of a voltage platform and the material is improved, so that the voltage drop is reduced, and the cycle performance is improved.
The third purpose of the invention is to provide a lithium ion battery, wherein the positive electrode material is the lithium-rich manganese-based positive electrode material.
By adopting the technical scheme, the reversible capacity, the discharge capacity and the cycling stability of the battery are effectively improved.
In conclusion, the invention has the following beneficial effects:
1. the layered lithium-rich manganese-based positive electrode material adopts a coprecipitation method to prepare a hydroxide precursor, so that a lithium source and the precursor are mixed more uniformly, lithium salt can be fully dispersed on the surface of precursor particles of the lithium-rich manganese-based positive electrode material, the consistency and the stability of the positive electrode material are improved, the particle size and the shape of the lithium-rich manganese-based positive electrode material are controllable, the particle size distribution is uniform, and single crystal particles of about 200-300nm are presented;
2. the preparation method disclosed by the invention is simple in process, does not need complex procedures such as pretreatment, post-treatment and the like, greatly reduces the process cost, simplifies the process operation, and simultaneously improves the uniform stability of the structure of the layered lithium-rich manganese-based cathode material;
3. the reversible capacity, the discharge capacity and the cycling stability of a battery assembled by the lithium-rich manganese-based cathode material are effectively improved.
Drawings
FIG. 1 is a scanning electron microscope image of the precursor of the lithium-rich manganese-based positive electrode material prepared in the fourth example;
FIG. 2 is a scanning electron microscope image of the lithium manganese-based positive electrode material with 0% lithium carbonate excess prepared in example four;
FIG. 3 is a scanning electron microscope image of the lithium-rich manganese-based positive electrode material with 5% lithium carbonate excess prepared in example V;
fig. 4 is a scanning electron microscope image of the lithium-rich manganese-based positive electrode material with 10% lithium carbonate excess prepared in example six;
FIG. 5 shows that the lithium-rich manganese-based positive electrode material in the four to six examples is prepared into a positive electrode sheet with the temperature of 0.05C (1C =250 mA/g) -1 ) Comparing the first charging and discharging curves;
fig. 6 is a graph comparing the rate cycle performance of positive plates made of the lithium-rich manganese-based positive electrode materials of the fourth to sixth examples.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings.
The first embodiment is as follows:
the preparation method of the lithium-rich manganese-based positive electrode material comprises the following steps:
s1 precursor preparation: dissolving required nickel sulfate, cobalt sulfate and manganese sulfate into deionized water according to the molar ratio of nickel ions to cobalt ions to manganese ions of 0.146.058 to 0.579 to form a mixed metal salt solution with the total metal ion concentration of 1mol/L, and then respectively pumping the mixed metal salt solution and 1mol/L sodium carbonate solution into a reaction kettle by a peristaltic pump for mixing, wherein the feeding speed of the peristaltic pump is 200mL/h; adding 5mol/L ammonium bicarbonate solution to adjust the pH value to 7, keeping the water bath temperature of the reaction kettle at 70 ℃, the stirring speed at 900rpm, continuously stirring to react to generate precipitate, aging for 6 hours after the reaction is completed, washing the precipitate with deionized water until no sulfate radical remains, drying for 12 hours at 80 ℃, crushing and sieving to obtain a precursor Ni 0.146 Co 0.058 Mn 0.579 (OH) 2 ；
S2, calcining: grinding and mixing the precursor and lithium hydroxide, putting the lithium hydroxide in a muffle furnace in an oxygen atmosphere for sintering according to the proportion of 5% of the final product, wherein the sintering temperature rise rate is 10 ℃/min, pre-sintering at 700 ℃ for 10h, and then calcining at 1000 ℃ for 18h to obtain the target anode material Li [ Li ] Li 0.217 Ni 0.146 Co 0.058 Mn 0.579 ]O 2 。
Example two:
a preparation method of a lithium-rich manganese-based positive electrode material comprises the following steps:
s1 precursor preparation: dissolving required nickel sulfate, cobalt sulfate and manganese sulfate into deionized water according to the molar ratio of nickel ions to cobalt ions to manganese ions of 0.146.058 to 0.579 to form a mixed metal salt solution with the total metal ion concentration of 3mol/L, and then respectively pumping the mixed metal salt solution and 3mol/L sodium carbonate solution into a reaction kettle by a peristaltic pump for mixing, wherein the feeding speed of the peristaltic pump is 2000mL/h; then 8mol/L ammonia water is added to adjust the pH value to 12, the water bath temperature in the reaction kettle is 40 ℃, the stirring speed is 400rpm,continuously stirring for reaction to generate precipitate, aging for 12h after complete reaction, washing the precipitate with deionized water until no sulfate radical remains, drying for 6h at 100 ℃, crushing and sieving to obtain precursor Ni 0.146 Co 0.058 Mn 0.579 (OH) 2 ；
S2, calcining: grinding and mixing the precursor and lithium acetate, placing the lithium acetate in a muffle furnace in an oxygen atmosphere for sintering at a sintering temperature rise rate of 2 ℃/min after the lithium acetate is excessive by 5 percent according to the proportion of a final product, pre-sintering at 400 ℃ for 6h, and then calcining at 750 ℃ for 10h to obtain a target anode material Li [ Li ] Li 0.217 Ni 0.146 Co 0.058 Mn 0.579 ]O 2 。
Example three:
a preparation method of a lithium-rich manganese-based positive electrode material comprises the following steps:
s1 precursor preparation: dissolving required nickel sulfate, cobalt sulfate and manganese sulfate into deionized water according to the molar ratio of nickel ions to cobalt ions to manganese ions of 0.146.058 to 0.579 to form a mixed metal salt solution with the total metal ion concentration of 2mol/L, and then respectively pumping the mixed metal salt solution and 2mol/L sodium hydroxide solution into a reaction kettle by a peristaltic pump for mixing, wherein the feeding speed of the peristaltic pump is 500mL/h; adding 10mol/L ammonia water to adjust the pH value to 11, keeping the water bath temperature of the reaction kettle at 60 ℃, stirring at the rotating speed of 600rpm, continuously stirring to react to generate a precipitate, aging for 10 hours after the reaction is completed, washing the precipitate with deionized water until no sulfate radical remains, drying for 10 hours at 120 ℃, crushing and sieving to obtain a precursor Ni 0.146 Co 0.058 Mn 0.579 (OH) 2 ；
S2, calcining: grinding and mixing the precursor and lithium nitrate, putting the lithium nitrate in a muffle furnace in an oxygen atmosphere for sintering at the temperature rise rate of 3 ℃/min after the lithium nitrate is 5% in excess according to the proportion of a final product, pre-sintering at 450 ℃ for 5h, and then calcining at 900 ℃ for 12h to obtain a target anode material Li [ Li ] Li 0.217 Ni 0.146 Co 0.058 Mn 0.579 ]O 2 。
Example four:
a preparation method of a lithium-rich manganese-based positive electrode material comprises the following steps:
s1 precursor preparation: dissolving required nickel sulfate, cobalt sulfate and manganese sulfate into deionized water according to the molar ratio of nickel ions to cobalt ions to manganese ions of 0.146 to 0.058 to form 2mol/L mixed metal salt solution, and then respectively pumping the mixed metal salt solution and 2mol/L sodium hydroxide solution into a reaction kettle for mixing by using a peristaltic pump, wherein the feeding speed of the peristaltic pump is 500mL/h; adding 10mol/L ammonia water to adjust the pH value to 11, keeping the water bath temperature of the reaction kettle at 60 ℃, stirring at the rotating speed of 600rpm, continuously stirring to react to generate precipitate, aging for 10 hours after complete reaction, washing the precipitate with deionized water until no sulfate radical remains, drying for 10 hours at 120 ℃, crushing and sieving to obtain a precursor Ni 0.146 Co 0.058 Mn 0.579 (OH) 2 ；
S2, calcining: grinding and mixing the precursor and lithium carbonate, placing the lithium carbonate in a muffle furnace in an oxygen atmosphere for sintering at the temperature rise rate of 3 ℃/min without excessive lithium carbonate according to the proportion of a final product, presintering at 450 ℃ for 5h, and calcining at 900 ℃ for 12h to obtain a target anode material Li [ Li ] Li 0.217 Ni 0.146 Co 0.058 Mn 0.579 ]O 2 。
As can be seen from FIG. 1, the particle morphology and size distribution of the precursor is uniform. As can be seen from FIG. 2, the sintered target material is in the form of single crystal grains of uniform size, closely distributed, and about 200-300nm in size.
Example five:
the difference from example four is that lithium carbonate is present in an excess of 5% in proportion to the final product.
As can be seen from FIG. 3, the sintered target material exhibits a state of single crystal grains of uniform size, closely distributed, and about 200-300nm in size.
Example six:
the difference from example four is that lithium carbonate is present in a proportion of the final product in excess of 10%.
As can be seen from FIG. 4, the sintered target material exhibits a state of single crystal grains of uniform size, closely distributed, and about 200-300nm in size.
As can be seen from FIG. 5, the lithium-rich manganese-based positive electrode material with 5% excess lithium carbonate has good electrochemical performance, relatively small first charge-discharge polarization, relatively high capacity exertion ratio, and 236.2mAh/g of first discharge capacity.
As can be seen from fig. 6, the lithium-rich manganese-based positive electrode material with 5% excess lithium carbonate has good rate cycle performance, high capacity as a whole, and significantly improved cycle stability.
Example seven:
the difference from the fourth embodiment is that the preparation method of the lithium-rich manganese base further comprises S3 surface modification, and the specific process is as follows:
firstly, immersing a positive electrode material into a 0.2mol/L nitric acid solution for soaking for 2 hours, filtering, washing with water, and drying to obtain an acid-treated positive electrode material;
step two, uniformly mixing 1 part of dibenzoyl peroxide, 0.1 part of acetanilide and 60 parts of dimethylbenzene to prepare an initiator solution, uniformly mixing 20 parts of liquid fluororubber, 8 parts of maleic anhydride and 150 parts of dimethylbenzene, heating to 80 ℃, then dropwise adding the initiator solution, finishing dripping 40min, heating to 90 ℃ after finishing dripping, reacting for 2h, then adding anhydrous methanol to precipitate a product, and drying at 40 ℃ to constant weight to obtain a modifier;
thirdly, mixing 1 part of modifier, 80 parts of dimethylbenzene and 80 parts of acetone, adding 10 parts of nano titanium dioxide, shearing and dispersing at the speed of 800r/min for 5min, then heating to 60 ℃, performing reflux reaction for 2h, filtering, washing with alcohol, drying and crushing to obtain modified nano titanium dioxide;
and fourthly, uniformly mixing 1 part of modified nano titanium dioxide, 80 parts of water and 8 parts of acid-treated cathode material, evaporating to dryness at 80 ℃ to obtain mixed powder, heating to 500 ℃, and continuing for 5 hours to obtain the modified cathode material.
Liquid fluororubbers are purchased from japan.
Example eight:
the difference from the fourth embodiment is that the preparation method of the lithium-rich manganese base also comprises S3 surface modification, and the specific process is as follows:
firstly, immersing a positive electrode material into a 0.2mol/L nitric acid solution for soaking for 3 hours, filtering, washing with water, and drying to obtain an acid-treated positive electrode material;
step two, uniformly mixing 1.4 parts of dibenzoyl peroxide, 0.15 part of acetanilide and 80 parts of dimethylbenzene to prepare an initiator solution, uniformly mixing 24 parts of liquid fluororubber, 10 parts of maleic anhydride and 200 parts of dimethylbenzene, heating to 85 ℃, then dropwise adding the initiator solution, finishing dripping for 50min, heating to 95 ℃ after finishing dripping, reacting for 3h, then adding anhydrous methanol to precipitate a product, and drying at 45 ℃ to constant weight to obtain a modifier;
thirdly, mixing 1.5 parts of modifier, 100 parts of dimethylbenzene and 100 parts of acetone, adding 15 parts of nano titanium dioxide, shearing and dispersing at the speed of 1000r/min for 5min, then heating to 65 ℃, carrying out reflux reaction for 3h, filtering, washing with alcohol, drying and crushing to obtain modified nano titanium dioxide;
and fourthly, uniformly mixing 1.3 parts of modified nano titanium dioxide, 100 parts of water and 10 parts of acid-treated cathode material, evaporating to dryness at 85 ℃ to obtain mixed powder, heating to 550 ℃, and continuing for 6 hours to obtain the modified cathode material.
Liquid fluororubbers are purchased from japan.
Example nine:
the difference from the fourth embodiment is that the preparation method of the lithium-rich manganese base further comprises S3 surface modification, and the specific process is as follows:
firstly, immersing a positive electrode material into a 0.2mol/L nitric acid solution for soaking for 2.5 hours, filtering, washing with water, and drying to obtain an acid-treated positive electrode material;
step two, uniformly mixing 1.2 parts of dibenzoyl peroxide, 0.12 part of acetanilide and 70 parts of dimethylbenzene to prepare an initiator solution, uniformly mixing 22 parts of liquid fluororubber, 9 parts of maleic anhydride and 180 parts of dimethylbenzene, heating to 82 ℃, then dropwise adding the initiator solution, finishing dripping for 45min, heating to 92 ℃ after finishing dripping, reacting for 2.5h, then adding anhydrous methanol to precipitate a product, and drying at 42 ℃ to constant weight to obtain a modifier;
thirdly, mixing 1.2 parts of modifier, 90 parts of dimethylbenzene and 90 parts of acetone, adding 12 parts of nano titanium dioxide, shearing and dispersing at the rate of 900r/min for 5min, then heating to 62 ℃, carrying out reflux reaction for 2.5h, filtering, washing with alcohol, drying and crushing to obtain modified nano titanium dioxide;
and fourthly, uniformly mixing 1.2 parts of modified nano titanium dioxide, 90 parts of water and 9 parts of acid-treated cathode material, evaporating to dryness at 82 ℃ to obtain mixed powder, heating to 520 ℃, and continuing for 5.5 hours to obtain the modified cathode material.
Liquid fluororubbers are purchased from japan.
In comparison with the fifth embodiment, the positive electrode sheets prepared from the modified positive electrode materials of the seventh to ninth embodiments are 1C (1C =250 mA/g) -1 ) At the same cycle number, the capacity is higher by 26.8% on average.
Example ten:
a lithium ion battery, wherein the cathode material is selected from any one of the lithium-rich manganese-based cathode materials obtained in the first to ninth embodiments.
The embodiments of the present invention are all preferred embodiments of the present invention, and the scope of the present invention is not limited thereby, so: equivalent changes made according to the structure, shape and principle of the invention shall be covered by the protection scope of the invention.
Claims (9)
1. The preparation method of the lithium-rich manganese-based positive electrode material is characterized by comprising the following steps of:
s1 precursor preparation: dissolving required nickel salt, cobalt salt and manganese salt into deionized water according to the molar ratio of nickel ions to cobalt ions to manganese ions of 0.146 to 0.058 to form a mixed metal salt solution, then respectively pumping the mixed metal salt solution and a precipitator solution into a reaction kettle by using a peristaltic pump to mix, adding a complexing agent to adjust the pH value, continuously stirring for reaction to generate a precipitate, aging after complete reaction, washing, drying, crushing and sieving the aged precipitate to obtain a precursor;
s2, calcining: grinding and mixing the precursor and a lithium source, and then placing the mixture in a muffle furnace to sinter to obtain a target anode material Li [ Li ] Li 0.217 Ni 0.146 Co 0.058 Mn 0.579 ]O 2 ；
S3, surface modification: firstly, immersing a positive electrode material into a 0.2mol/L nitric acid solution for soaking for 2-3h, filtering, washing with water, and drying to obtain an acid-treated positive electrode material;
step two, uniformly mixing 1-1.4 parts of dibenzoyl peroxide, 0.1-0.15 part of acetanilide and 60-80 parts of dimethylbenzene to prepare an initiator solution, uniformly mixing 20-24 parts of liquid fluororubber, 8-10 parts of maleic anhydride and 150-200 parts of dimethylbenzene, heating to 80-85 ℃, dropwise adding the initiator solution, finishing dripping for 40-50min, heating to 90-95 ℃ after finishing dripping, reacting for 2-3h, adding anhydrous methanol to precipitate a product, and drying at 40-45 ℃ to constant weight to obtain a modifier;
thirdly, mixing 1-1.5 parts of modifier, 80-100 parts of dimethylbenzene and 80-100 parts of acetone, adding 10-15 parts of nano titanium dioxide, shearing and dispersing at the speed of 800-1000r/min for 5min, then heating to 60-65 ℃, carrying out reflux reaction for 2-3h, filtering, washing with alcohol, drying and crushing to obtain modified nano titanium dioxide;
and fourthly, uniformly mixing 1-1.3 parts of modified nano titanium dioxide, 80-100 parts of water and 8-10 parts of acid-treated cathode material, evaporating to dryness at 80-85 ℃ to obtain mixed powder, heating to 500-550 ℃, and continuing for 5-6 hours to obtain the modified cathode material.
2. The preparation method of the lithium-rich manganese-based positive electrode material according to claim 1, characterized in that: the total concentration of metal ions in the mixed metal salt solution in the S1 precursor preparation is 1-3mol/L, and the nickel salt, the cobalt salt and the manganese salt are all sulfates.
3. The preparation method of the lithium-rich manganese-based positive electrode material according to claim 1, characterized in that: the precipitant is one or more of sodium carbonate and sodium hydroxide, and the molar concentration of the precipitant solution is the same as the molar concentration of total metal ions in the mixed metal salt solution.
4. The preparation method of the lithium-rich manganese-based positive electrode material according to claim 1, characterized in that: the complexing agent is one or more of ammonia water and ammonium bicarbonate, and the molar concentration of the complexing agent is 5-10mol/L.
5. The preparation method of the lithium-rich manganese-based positive electrode material according to claim 1, characterized by comprising the following steps: in the preparation of the S1 precursor, the feeding speed of a peristaltic pump is 200-2000mL/h; the temperature of the water bath in the reaction kettle is 40-70 ℃, the stirring speed is 400-900rpm, the pH value is 7-12, and the aging is carried out for 6-12h; the drying temperature of the precipitate is 80-120 ℃, and the drying time is 6-12h.
6. The preparation method of the lithium-rich manganese-based positive electrode material according to claim 1, characterized in that: the lithium source is one or more of lithium hydroxide, lithium carbonate, lithium acetate and lithium nitrate, and the lithium source is mixed with the precursor in an excess of 1-15% according to the proportion of the final product.
7. The preparation method of the lithium-rich manganese-based positive electrode material according to claim 1, characterized in that: in the calcination of S2, the sintering temperature rise rate is 2-10 ℃/min, the pre-sintering is carried out for 5-10h at 400-700 ℃, and then the calcination is carried out for 10-18h at 750-1000 ℃; the muffle furnace is an oxygen atmosphere muffle furnace.
8. A lithium-rich manganese-based positive electrode material prepared by the preparation method of any one of claims 1 to 7.
9. A lithium ion battery, characterized by: the positive electrode material is the lithium-rich manganese-based positive electrode material according to claim 8.
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