Process for synthesizing nickel cobalt lithium manganate positive electrode material

Abstract

The invention relates to a nickel cobalt lithium manganate positive electrode material, in particular to a process for synthesizing the nickel cobalt lithium manganate positive electrode material, which comprises the following steps: weighing MnSO4, CoSO4 and NiSO4 according to a stoichiometric ratio, adding water for dissolving to prepare a mixed metal ion solution, and putting the solution into a reaction kettle; dropwise adding concentrated ammonia water and excessive NaOH solution into the reaction kettle while stirring, and carrying out water bath reaction; aging reaction precipitates, washing, carrying out suction filtration, drying, putting the dried reaction precipitates and Li2CO3 in a stoichiometric ratio into a planetary ball mill, and adding a dispersing agent for mechanical activation; drying the activated slurry in a drying oven to obtain a precursor; pre-sintering the precursor; and after pre-sintering, grinding and roasting to obtain the nickel cobalt lithium manganate positive electrode material. The nickel cobalt lithium manganate positive electrode material is synthesized by adopting a coprecipitation method, and the precursor is mechanically activated in the synthesis process, so that the precursor is uniform in particle distribution and uniform in particle size; and pre-sintering and roasting to obtain the cobalt nickel lithium manganate positive electrode material with excellent electrochemical performance.

Description

Technical Field

[0001] This invention relates to nickel-cobalt-manganese lithium battery cathode materials, specifically a process for synthesizing nickel-cobalt-manganese lithium cathode materials. Background Technology

[0002] In recent years, novel lithium-ion composite cathode materials have developed rapidly, especially nickel-cobalt-manganese-lithium cathode materials, which have become a research hotspot for experts and scholars both domestically and internationally. Compared with commercially available LiCoO2, nickel-cobalt-manganese-lithium cathode materials have the advantage of lower cost; compared with LiNiO2, nickel-cobalt-manganese-lithium cathode materials are easier to synthesize, and have relatively better cycle performance and thermal stability; compared with spinel LiMn2O4, nickel-cobalt-manganese-lithium cathode materials have a more stable structure during charge and discharge, do not exhibit the Jahn-Teller effect, and have stable Mn ions, preventing dissolution of Mn ions in the electrolyte; compared with LiFePO4, nickel-cobalt-manganese-lithium cathode materials have a higher tap density and a higher potential plateau.

[0003] Currently, the preparation methods for nickel-cobalt-manganese-lithium cathode materials include high-temperature solid-state method, co-precipitation method, sol-gel method, spray pyrolysis method, hydrothermal synthesis method and combustion method, etc. However, the co-precipitation method is still the most commonly used. This method is complex to operate, has poor repeatability, and requires strict control of experimental conditions, which to some extent limits the industrial production and practical application of nickel-cobalt-manganese-lithium cathode materials. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a process for obtaining lithium nickel cobalt manganese oxide cathode materials with excellent electrochemical performance, comprising the following steps: The technical solution adopted in this invention is: a process for synthesizing lithium nickel cobalt manganese oxide cathode material, which includes the following steps: (1) Weigh MnSO4, CoSO4 and NiSO4 according to the stoichiometric ratio, add water to dissolve them, prepare a mixed metal ion solution, and place the solution in a reaction vessel; (2) Add concentrated ammonia and excess NaOH solution dropwise to the above reaction vessel while stirring to carry out a water bath reaction; (3) After aging, washing, filtering and drying the reaction precipitate, place it in a planetary ball mill with Li2CO3 in stoichiometric ratio and add a dispersant for mechanical activation; (4) Then the activated slurry is placed in a drying oven to dry, and the precursor is obtained; (5) Preheat the precursor; (6) After pre-calcination, the material is ground and then calcined to obtain lithium nickel cobalt manganese oxide cathode material.

[0005] Preferably, the stirring speed is 500-600 r / min and the stirring time is 4-5 h.

[0006] Preferably, the temperature of the water bath reaction is 50-60℃.

[0007] Preferably, the drying oven is kept at a temperature of 60-80°C during the drying process.

[0008] Preferably, the pre-firing temperature is 450-550℃ and the time is 4-5 hours.

[0009] Preferably, the roasting temperature is 800-900℃ and the time is 9-10h.

[0010] As a preferred method, mechanical activation is performed using a planetary ball mill at a rotation speed of 180-220 r / min for 3.5-4.5 h.

[0011] As a preferred option, the mass ratio of balls to material during mechanical activation is (8-9):1.

[0012] As can be seen from the above technical solutions, the present invention uses a co-precipitation method to synthesize lithium nickel cobalt manganese oxide cathode materials. During the synthesis process, the precursor is mechanically activated to make the precursor particles uniformly distributed and uniform in size. Then, the lithium cobalt nickel manganese oxide cathode material with excellent electrochemical performance is obtained through pre-calcination and roasting. Detailed Implementation

[0013] The present invention will now be described in detail. The illustrative embodiments and descriptions herein are used to explain the invention, but are not intended to limit the invention.

[0014] A process for synthesizing lithium nickel cobalt manganese oxide cathode material includes the following steps: (1) Weigh MnSO4, CoSO4 and NiSO4 according to the stoichiometric ratio, dissolve them in water to prepare a mixed metal ion solution, and place the solution in a reaction vessel. Then, while stirring, add concentrated ammonia and excess NaOH solution dropwise to the above reaction vessel for a water bath reaction. The temperature of the water bath reaction is 50-60℃, and the titration rate is controlled. The stirring speed is 500-600 r / min, and the solution is mixed in the reaction vessel while stirring to form a precipitate. After the titration is completed, stir for another 4-5 hours and then stop stirring to allow the precipitate to age, wash, filter and dry.

[0015] (2) Then, place the stoichiometric amount of Li2CO3 in a planetary ball mill and add a dispersant for mechanical activation. Anhydrous ethanol or similar dispersants can be used, which are beneficial for dispersion and ball milling. Mechanical activation is performed using a planetary ball mill with a ball-to-material mass ratio of (8-9):1, which results in better activation. The planetary ball mill is operated at a speed of 180-220 r / min, and the activation time is 3.5-4.5 h. This can improve the interfacial contact between materials, promote the generation and growth of crystal nuclei in the subsequent synthesis process, and achieve the effect of grain refinement.

[0016] (3) Then the activated slurry is placed in a drying oven to dry, and the precursor is obtained; during drying, the drying oven is kept at a temperature of 60-80℃.

[0017] (4) The precursor is pre-calcined at a temperature of 450-550℃ for 4-5 hours. After pre-calcination, it is ground and then roasted at a temperature of 800-900℃ for 9-10 hours to obtain lithium cobalt-nickel-manganese oxide cathode material.

[0018] Example 1 MnSO4, CoSO4, and NiSO4 were weighed according to stoichiometric ratio and dissolved in water to prepare a mixed metal ion solution. The solution was placed in a reaction vessel, and concentrated ammonia and excess NaOH solution were added dropwise while stirring to carry out a water bath reaction at 50℃ and a stirring speed of 500 r / min. After titration, stirring was stopped after 4 hours. The precipitate was then aged, washed, filtered, and dried, and then placed in a planetary ball mill with stoichiometric Li2CO3 and an appropriate amount of anhydrous ethanol. The mixture was then ball-milled at a ball-to-material mass ratio of 8:1 and a speed of 180 r / min for 4.5 hours. The ball-milled slurry was then dried in a drying oven at 60℃ to obtain the precursor. The precursor was pre-calcined at 450℃ for 5 hours. After pre-calcination, it was ground and then calcined at 800℃ for 10 hours to obtain lithium nickel cobalt manganese oxide cathode material. Performance tests on the material yielded the following results: initial charge / discharge specific capacities of 196 mAh / g and 187 mAh / g, respectively; starting from the second week, the charge / discharge efficiency reached over 98%, and the discharge specific capacity in the eighth week was 176 mAh / g, with a capacity retention rate of 94.1%.

[0019] Example 2 MnSO4, CoSO4, and NiSO4 were weighed according to stoichiometric ratio and dissolved in water to prepare a mixed metal ion solution. The solution was placed in a reaction vessel, and concentrated ammonia and excess NaOH solution were added dropwise while stirring to carry out a water bath reaction at 55℃ and a stirring speed of 550 r / min. After titration, stirring was stopped after 4.5 h. The precipitate was then aged, washed, filtered, and dried, and then placed in a planetary ball mill with stoichiometric Li2CO3 and an appropriate amount of anhydrous ethanol. The mixture was then ball-milled for 4 h at a ball-to-material mass ratio of 8.5:1 and a speed of 200 r / min. The ball-milled slurry was then dried in a drying oven at 70℃ to obtain a precursor. The precursor was pre-calcined at 500℃ for 4.5 h. After pre-calcination, it was ground and then calcined at 850℃ for 9.5 h to obtain lithium nickel cobalt manganese oxide cathode material. Performance tests on the material yielded the following results: initial charge and discharge specific capacities of 213 mAh / g and 201 mAh / g, respectively; starting from the second week, the charge and discharge efficiency reached over 99%, and the discharge specific capacity was 191 mAh / g in the eighth week, with a capacity retention rate exceeding 95%.

[0020] Example 3 MnSO4, CoSO4, and NiSO4 were weighed according to stoichiometric ratio and dissolved in water to prepare a mixed metal ion solution. The solution was placed in a reaction vessel, and concentrated ammonia and excess NaOH solution were added dropwise while stirring to carry out a water bath reaction at 60℃ and a stirring speed of 600 r / min. After titration, stirring was stopped after 5 h. The precipitate was then aged, washed, filtered, and dried, and then placed in a planetary ball mill with stoichiometric Li2CO3 and an appropriate amount of anhydrous ethanol. The mixture was then ball-milled for 3.5 h at a ball-to-material mass ratio of 9:1 and a speed of 220 r / min. The ball-milled slurry was then dried in an 80℃ drying oven to obtain a precursor. The precursor was pre-calcined at 550℃ for 4 h. After pre-calcination, it was ground and then calcined at 900℃ for 9 h to obtain lithium nickel cobalt manganese oxide cathode material. Performance tests on the material yielded the following results: initial charge / discharge specific capacities of 203 mAh / g and 192 mAh / g, respectively; starting from the second week, the charge / discharge efficiency reached over 98%, and the discharge specific capacity was 180 mAh / g in the eighth week, with a capacity retention rate of 93.7%.

[0021] The technical solutions provided by the embodiments of the present invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the embodiments of the present invention. The descriptions of the embodiments above are only for helping to understand the principles of the embodiments of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the embodiments of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A process for synthesizing a lithium nickel cobalt manganese oxide cathode material, comprising the following steps: (1) taking MnSO4, CoSO4 and NiSO4 in stoichiometric ratio, dissolving in water to form a mixed metal ion solution, and placing the solution in a reaction kettle; (2) adding concentrated ammonia water and excess NaOH solution into the reaction kettle while stirring, and performing a water bath reaction; (3) aging, washing, suction filtering and drying the reaction precipitate, placing the precipitate in a planetary ball mill together with stoichiometric Li2CO3 and a dispersant, and performing mechanical activation; (4) then drying the activated slurry in a drying oven to obtain a precursor; (5) pre-sintering the precursor; (6) grinding the pre-sintered precursor, re-sintering, and obtaining the lithium nickel cobalt manganese oxide cathode material.

2. The process for synthesizing lithium nickel cobalt manganese oxide cathode material according to claim 1, characterized in that: The stirring speed is 500-600 r / min, and the stirring time is 4-5 h.

3. The process for synthesizing lithium nickel cobalt manganese oxide cathode material according to claim 1, characterized in that: The water bath reaction temperature is 50-60℃.

4. The process for synthesizing lithium nickel cobalt manganese oxide cathode material according to claim 1, characterized in that: The drying temperature is 60-80℃.

5. The process for synthesizing lithium nickel cobalt manganese oxide cathode material according to claim 1, wherein: The pre-sintering temperature is 450-550℃, and the time is 4-5 h.

6. The process for synthesizing lithium nickel cobalt manganese oxide cathode material according to claim 1, wherein: The sintering temperature is 800-900℃, and the time is 9-10 h.

7. The process for synthesizing lithium nickel cobalt manganese oxide cathode material according to claim 1, wherein: The planetary ball mill is used for mechanical activation, the planetary ball mill is operated at a speed of 180-220 r / min, and the mechanical activation time is 3.5-4.5 h.

8. The process for synthesizing lithium nickel cobalt manganese oxide cathode material according to claim 1, wherein: The ball-to-material mass ratio during mechanical activation is (8-9):1.