WO2023178900A1 - Lithium nickel manganese cobalt oxide gradient positive electrode material and preparation method therefor - Google Patents

Lithium nickel manganese cobalt oxide gradient positive electrode material and preparation method therefor Download PDF

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WO2023178900A1
WO2023178900A1 PCT/CN2022/108632 CN2022108632W WO2023178900A1 WO 2023178900 A1 WO2023178900 A1 WO 2023178900A1 CN 2022108632 W CN2022108632 W CN 2022108632W WO 2023178900 A1 WO2023178900 A1 WO 2023178900A1
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gradient
cathode material
lithium nickel
lithium
nickel cobalt
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PCT/CN2022/108632
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French (fr)
Chinese (zh)
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许开华
李伟
谢军
桑雨辰
周晓燕
陈玉君
张翔
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格林美(无锡)能源材料有限公司
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Publication of WO2023178900A1 publication Critical patent/WO2023178900A1/en

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    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00Electrodes
    • H01M4/02Electrodes composed of, or comprising, active material
    • H01M4/36Selection of substances as active materials, active masses, active liquids
    • H01M4/48Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/50Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
    • H01M4/505Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00Electrodes
    • H01M4/02Electrodes composed of, or comprising, active material
    • H01M4/36Selection of substances as active materials, active masses, active liquids
    • H01M4/48Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10Energy storage using batteries

Definitions

  • the present invention relates to the technical field of positive electrode materials, and in particular to a nickel cobalt lithium manganate gradient positive electrode material and a preparation method thereof.
  • Lithium nickel cobalt manganate ternary lithium ion battery cathode material is widely used in the field of new energy vehicles due to its high energy density.
  • High nickel enrichment is generally used to maximize reversible capacity.
  • the cycle and thermal stability gradually decrease, resulting in a reduction in the cycle life of the battery. Therefore, some studies have proposed that by controlling the gradual decrease of nickel from the core to the particle surface, that is, the higher nickel content in the core contributes to a higher discharge capacity, and the higher cobalt and manganese content in the outer layer provides more structural stability, thereby improving the material interface. Stability and battery cycle life.
  • the differences in composition and structure between the core and the shell during the sintering process cause the core and shell to shrink to varying degrees during the cycle and gradually separate, thereby inhibiting the diffusion-migration process of ions/electrons between the core and the shell, resulting in Decrease in long-term cyclic performance of materials.
  • the purpose of the present invention is to overcome the above technical deficiencies, propose a lithium nickel cobalt manganate gradient cathode material and a preparation method thereof, and solve the problem of unreasonable sintering processes of nickel cobalt lithium manganate gradient cathode materials with gradient changes in nickel content in the prior art, resulting in material Technical issues that degrade performance.
  • the inventor found that since the nickel content gradually increased from the outer shell to the core, due to the concentration diffusion mechanism during the sintering process, the nickel in the core part gradually diffused to the surface, and the content of manganese and cobalt on the surface was higher than that in the core, gradually Diffusion to the interior, theoretically the optimal calcination temperature increases step by step from the core to the shell. Therefore, it is hoped that through temperature gradient calcination, the core and shell will be in their respective optimal sintering conditions to avoid core and shell composition and structural differences during the sintering process, which will cause the core and shell to shrink to varying degrees and gradually separate during the cycle, thereby improving the long-term durability of the material. Cycle performance.
  • the first aspect of the present invention provides a method for preparing a lithium nickel cobalt manganate gradient cathode material, which includes the following steps:
  • lithium nickel cobalt manganate gradient cathode material precursor wherein, the nickel content in the lithium nickel cobalt manganate gradient cathode material precursor decreases from the core to the outer shell, and the cobalt and manganese contents increase from the core to the outer shell;
  • the lithium nickel cobalt manganate gradient cathode material precursor and the lithium source are mixed evenly and then gradient calcination is performed to obtain the nickel cobalt lithium manganate gradient cathode material; wherein, the gradient calcination process includes: controlling the calcination temperature to decrease the calcination temperature gradient.
  • a second aspect of the present invention provides a lithium nickel cobalt manganate gradient positive electrode material, which is obtained by the preparation method of a lithium nickel cobalt manganate gradient positive electrode material provided by the first aspect of the present invention.
  • the beneficial effects of the present invention include:
  • the present invention uses temperature gradient calcination to keep the core and shell in their respective optimal sintering conditions to avoid core and shell composition and structural differences during the sintering process, causing the core and shell to shrink to varying degrees and gradually separate during the cycle, thereby effectively improving the long-term durability of the material. Cycle performance.
  • a first aspect of the invention provides a method for preparing a lithium nickel cobalt manganate gradient cathode material, which includes the following steps:
  • the gradient calcination process includes: controlling the calcination temperature to achieve a calcination temperature gradient decline.
  • the steps of obtaining the nickel-cobalt lithium manganate gradient cathode material precursor include:
  • n groups of mixed salt solutions containing nickel sources, cobalt sources and manganese sources with different nickel contents where n is a positive integer ⁇ 2; in some embodiments of the present invention, n is 3; nickel source It is at least one of nickel sulfate, nickel chloride, nickel nitrate, and nickel acetate.
  • the cobalt source is at least one of cobalt sulfate, cobalt chloride, cobalt nitrate, and cobalt acetate.
  • the manganese source is manganese sulfate, manganese chloride, At least one of manganese nitrate and manganese acetate.
  • the nickel source, cobalt source and manganese source are configured into three metal ratios according to the nickel, cobalt and manganese metal molar ratios of 5:2:3, 7:1:2 and 90:5:5 respectively.
  • the mixed salt solutions are respectively counted as A metal salt solution, B metal salt solution, and C metal salt solution; further, in the above mixed salt solution, the total metal ion concentration of nickel, cobalt, and manganese is 1 to 3 mol/L.
  • step S13 of the present invention the steps of sequentially mixing n groups of mixed salt solutions with different nickel contents with an alkali solution and a complexing agent solution for continuous reaction include:
  • step S133 Repeat step S132 to perform the mixing reaction in sequence until the nth reaction solution is obtained, and undergoes aging, filtration, washing and drying to obtain the nickel cobalt lithium manganate gradient cathode material precursor;
  • i is a positive integer, 1 ⁇ i ⁇ i+1 ⁇ n
  • the nickel content of the i-th group of mixed salt solutions is greater than the nickel content of the i+1-th group of mixed salt solutions
  • the cobalt-manganese content of the i-th group of mixed salt solutions It is less than the cobalt and manganese content of the mixed salt solution of the i+1 group, thereby achieving a gradient decrease in nickel content from the core to the outer shell, and a gradient increase in the cobalt and manganese content from the core to the outer shell.
  • the mixed salt solution, alkali solution, and complexing agent are all introduced into the reaction system at a certain flow rate.
  • the nickel source, the cobalt source and the manganese source are respectively configured to the total metal ion concentration according to the nickel, cobalt and manganese metal molar ratios of 5:2:3, 7:1:2 and 90:5:5.
  • a mixed salt solution of 1 to 3 mol/L is counted as A metal salt solution, B metal salt solution, and C metal salt solution respectively, and the feed rate of the mixed salt solution, alkali solution, and complexing agent solution is 1 mol/h respectively.
  • 0.5mol/h and 2mol/h the reaction times of A metal salt solution, B metal salt solution and C metal salt solution are 4h, 6h and 20h respectively.
  • the lithium source is lithium hydroxide or lithium carbonate.
  • the lithium source is lithium hydroxide monohydrate (LiOH ⁇ H 2 O).
  • the molar ratio of the lithium nickel cobalt manganate gradient cathode material precursor to the lithium source is 1: (1.01 to 1.1).
  • the molar ratio of the nickel cobalt lithium manganate gradient cathode material precursor to the lithium source is The molar ratio of sources is 1:1.04.
  • the calcination temperature is controlled according to the optimal sintering temperature of each layer of the nickel cobalt lithium manganate gradient cathode material precursor to reduce the calcination temperature gradient, so that each layer structure is at its own optimal sintering temperature to avoid occurrences during the sintering process.
  • the differences in the composition and structure of the core and shell cause the core and shell to shrink to varying degrees and gradually separate during the cycle, thus improving the long-term cycle performance of the material.
  • the optimal sintering temperature of each layer of the gradient cathode material precursor of lithium nickel cobalt manganate was obtained by conducting a sintering DOE test on lithium salt and lithium nickel cobalt manganate ternary cathode material precursor of different compositions at different temperatures.
  • the fluctuation range of different proportions is ⁇ 0.01, and the fluctuation range of different temperatures is generally ⁇ 10°C.
  • the nickel cobalt lithium manganate ternary cathode material obtained from the above-mentioned DOE test has been discharged after electrochemical testing.
  • the sintering parameters (temperature, etc.) with the largest specific capacity and best cycle performance are the optimal values. This process is an existing technology and will not be described in detail here.
  • the optimal sintering temperature of the precursor hydroxide Ni 0.81 Co 0.08 Mn 0.11 (OH) 2 is 800 to 820°C, and the optimal sintering temperature of the precursor hydroxide Ni 0.5 Co 0.2 Mn
  • the optimal sintering temperature of 0.3 (OH) 2 is 900 ⁇ 920°C
  • the optimal sintering temperature of precursor hydroxide Ni 0.7 Co 0.1 Mn 0.2 (OH) 2 is 840 ⁇ 860°C
  • the optimal sintering temperature of 0.05 Mn 0.05 (OH) 2 is 740 ⁇ 760°C.
  • the gradient calcination process was carried out in an oxygen atmosphere.
  • the sintering time corresponding to the lowest sintering temperature is 6 to 12 hours, and the sintering time corresponding to other sintering temperatures except the lowest sintering temperature is 0.5 to 1.5 hours. Within this time range, the obtained lithium nickel cobalt manganate gradient cathode material has better battery performance.
  • a flux is also added during the above gradient calcination process.
  • the present invention can reduce the calcination temperature of the shell part, make the shell material recrystallize at a relatively low temperature, reduce the temperature difference between the outer shell part and the core part, and weaken the occurrence of cores during the sintering process.
  • the differences in composition and structure between the shells cause the core and shell to shrink and separate to varying degrees during the cycle, ultimately improving the cycle performance of the cathode material.
  • the amount of flux added should not be too high.
  • the molar ratio of the nickel cobalt lithium manganate gradient cathode material precursor to the cosolvent is 1: (0.00001 ⁇ 0.003), and further is 1: (0.00001 ⁇ 0.001);
  • the cosolvent is selected from boron, silicon, magnesium, and calcium. At least one of oxides, hydroxides, carbonates or chlorides.
  • a second aspect of the present invention provides a lithium nickel cobalt manganate gradient positive electrode material, which is obtained by the preparation method of a lithium nickel cobalt manganate gradient positive electrode material provided by the first aspect of the present invention.
  • the preparation process of the gradient precursor hydroxide with the nickel content gradually decreasing from the core to the shell is as follows:
  • NiSO 4 ⁇ 6H 2 O, CoSO 4 ⁇ 7H 2 O and MnSO 4 ⁇ H 2 O are respectively configured into the total A mixed salt solution with a metal ion concentration of 2mol/L of A, B, and C; then prepare a 1mol/L ammonia solution and a 4mol/L sodium hydroxide solution; first add the high-nickel metal salt solution in C, NaOH solution and ammonia solution were simultaneously pumped into the reaction kettle at pump speeds of 1 mol/h, 0.5 mol/h and 2 mol/h.
  • the reaction temperature was controlled between 40-60°C and the reaction pH was between 10-13.
  • the reaction process Use nitrogen as protection; during this process, the metal ions passed into the kettle are complexed by ammonium ions, uniformly forming a large number of nuclei; after the reaction proceeds for 20 hours, C is switched to B metal salt solution and is passed into the kettle to form Intermediate buffer layer; after continuing the reaction for 6 hours, pass the A mixed salt solution into the kettle, and continue the reaction for 4 hours before ending; after aging, filtration, washing and drying, a gradient precursor hydroxide with a gradually decreasing nickel content from the core to the shell is obtained Ni 0.81 Co 0.08 Mn 0.11 (OH) 2 .
  • the gradient precursor hydroxide, LiOH monohydrate, and boron oxide according to the molar ratio of 1:1.04:0.001, place them in a ball mill tank and mix them evenly. Place the mixture in an oxygen atmosphere furnace for gradient calcination. The reaction is completed. Finally, the gradient cathode material is obtained after cooling, crushing and sieving.
  • the specific gradient calcination process is as follows: first, the temperature is raised from room temperature to 900°C at a heating rate of 2°C/min, kept for 1 hour, then lowered to 850°C at a cooling rate of 5°C/min, and kept for 1 hour. Finally, the temperature was lowered to 750°C and kept warm for 10 hours.
  • the specific gradient calcination process is as follows: first, the temperature is raised from room temperature to 920°C at a heating rate of 2°C/min, kept for 1 hour, then lowered to 850°C at a cooling rate of 5°C/min, and kept for 1 hour. Finally, the temperature was lowered to 750°C and kept warm for 10 hours.
  • the specific gradient calcination process is as follows: first, the temperature is raised from room temperature to 900°C at a heating rate of 2°C/min, kept for 1 hour, then lowered to 850°C at a cooling rate of 5°C/min, and kept for 1 hour. Finally, the temperature was lowered to 750°C and kept for 10 hours.
  • the gradient precursor hydroxide LiOH monohydrate and boron oxide according to the molar ratio of 1:1.04:0.005
  • mix them evenly in a ball mill jar and place the mixture in an oxygen atmosphere furnace for gradient calcination.
  • the reaction is completed.
  • the gradient cathode material is obtained after cooling, crushing and sieving.
  • the specific gradient calcination process is as follows: first, the temperature is raised from room temperature to 900°C at a heating rate of 2°C/min, kept for 1 hour, then lowered to 850°C at a cooling rate of 5°C/min, and kept for 1 hour. Finally, the temperature was lowered to 750°C and kept for 10 hours.
  • the gradient precursor hydroxide, LiOH monohydrate, and boron oxide according to the molar ratio of 1:1.04:0.001, place them in a ball mill tank and mix them evenly. Place the mixture in an oxygen atmosphere furnace for gradient calcination. The reaction is completed. Finally, the gradient cathode material is obtained after cooling, crushing and sieving.
  • the specific gradient calcination process is: first, the temperature is raised from room temperature to 750°C at a heating rate of 2°C/min, kept for 10 hours, then the temperature is raised to 850°C, kept for 1 hour, and finally the temperature is raised to 900°C. Keep warm for 1 hour.
  • the gradient precursor hydroxide, LiOH monohydrate, and boron oxide according to the molar ratio of 1:1.04:0.001, place them in a ball mill tank and mix them evenly. Place the mixture in an oxygen atmosphere furnace for gradient calcination. The reaction is completed. Finally, the gradient cathode material is obtained after cooling, crushing and sieving. Among them, the gradient calcination process is as follows: first, the temperature is raised from room temperature to 900°C at a heating rate of 2°C/min, maintained for 4 hours, and then lowered to 850°C at a cooling rate of 5°C/min, and maintained for 4 hours. Finally, the temperature was lowered to 750°C and kept warm for 4 hours.
  • the gradient precursor hydroxide LiOH monohydrate and boron oxide according to the molar ratio of 1:1.04:0.001, place them in a ball mill tank and mix them evenly. Place the mixture in an oxygen atmosphere furnace for calcination. After the reaction is completed , after cooling, crushing and screening, the gradient cathode material is obtained. Among them, the specific calcination process is: raising the temperature to 800°C and holding it for 12 hours.

Abstract

Disclosed in the present invention are a lithium nickel manganese cobalt oxide gradient positive electrode material and a preparation method therefor. The preparation method comprises the following steps: obtaining a lithium nickel manganese cobalt oxide gradient positive electrode material precursor, the nickel content in the lithium nickel manganese cobalt oxide gradient positive electrode material precursor decreasing from a core to a shell in a gradient mode, and the cobalt and manganese contents increasing from the core to the shell in a gradient mode; and uniformly mixing the lithium nickel manganese cobalt oxide gradient positive electrode material precursor with a lithium source, and then carrying out gradient calcination, thereby obtaining the lithium nickel manganese cobalt oxide gradient positive electrode material, the gradient calcination process comprising controlling the calcination temperature so that the calcination temperature decreases in a gradient mode. According to the present invention, by means of gradient temperature-based calcination, the core and the shell are in respective optimal sintering conditions, so as to avoid differences in core and shell components and structures in a sintering process, which may cause different degrees of shrinkage and gradual separation of the core and the shell in a cycling process, thereby effectively improving the long-term cycle performance of the material.

Description

一种镍钴锰酸锂梯度正极材料及其制备方法A kind of nickel cobalt lithium manganate gradient cathode material and preparation method thereof 技术领域Technical field
本发明涉及正极材料技术领域,尤其是涉及一种镍钴锰酸锂梯度正极材料及其制备方法。The present invention relates to the technical field of positive electrode materials, and in particular to a nickel cobalt lithium manganate gradient positive electrode material and a preparation method thereof.
背景技术Background technique
镍钴锰酸锂三元锂离子电池正极材料由于具有高的能量密度被广泛应用于新能源汽车领域。Lithium nickel cobalt manganate ternary lithium ion battery cathode material is widely used in the field of new energy vehicles due to its high energy density.
一般采用高镍富集来实现最大化可逆容量。但是随着镍含量的提高,高镍材料的阳离子混排变得越来越多,循环、热稳定性逐渐下降,由此导致电池的循环寿命降低。因此,有研究提出通过控制内核至颗粒表面的镍逐渐递减,即内核较高的镍含量贡献更高的放电容量,外层较高的钴锰含量提供更多的结构稳定,从而改善材料界面的稳定性和电池的循环寿命。但是在烧结过程中出现核壳之间成分和结构上的差异使核与壳在循环过程中出现不同程度的收缩,并逐渐分离,从而抑制离子/电子在核壳间的扩散-迁移过程,造成材料长期循环性能的下降。High nickel enrichment is generally used to maximize reversible capacity. However, as the nickel content increases, more and more cations are mixed in high-nickel materials, and the cycle and thermal stability gradually decrease, resulting in a reduction in the cycle life of the battery. Therefore, some studies have proposed that by controlling the gradual decrease of nickel from the core to the particle surface, that is, the higher nickel content in the core contributes to a higher discharge capacity, and the higher cobalt and manganese content in the outer layer provides more structural stability, thereby improving the material interface. Stability and battery cycle life. However, the differences in composition and structure between the core and the shell during the sintering process cause the core and shell to shrink to varying degrees during the cycle and gradually separate, thereby inhibiting the diffusion-migration process of ions/electrons between the core and the shell, resulting in Decrease in long-term cyclic performance of materials.
发明内容Contents of the invention
本发明的目的在于克服上述技术不足,提出一种镍钴锰酸锂梯度正极 材料及其制备方法,解决现有技术中镍含量梯度变化的镍钴锰酸锂梯度正极材料烧结工艺不合理导致材料性能下降的技术问题。The purpose of the present invention is to overcome the above technical deficiencies, propose a lithium nickel cobalt manganate gradient cathode material and a preparation method thereof, and solve the problem of unreasonable sintering processes of nickel cobalt lithium manganate gradient cathode materials with gradient changes in nickel content in the prior art, resulting in material Technical issues that degrade performance.
在试验过程中,发明人发现,由于镍的含量从外壳至内核逐渐增加,在烧结过程中因为浓度扩散机制,内核部分的镍逐渐向表面扩散,表面的锰和钴的含量高于内核,逐渐向内部扩散,理论上从核至壳的最佳煅烧温度是逐级升高的。因此希望通过温度梯度煅烧,使核壳处于各自的最佳烧结条件以避免烧结过程中出现核壳成分和结构差异导致核壳在循环过程中出现不同程度的收缩并逐渐分离,从而提高材料的长期循环性能。During the experiment, the inventor found that since the nickel content gradually increased from the outer shell to the core, due to the concentration diffusion mechanism during the sintering process, the nickel in the core part gradually diffused to the surface, and the content of manganese and cobalt on the surface was higher than that in the core, gradually Diffusion to the interior, theoretically the optimal calcination temperature increases step by step from the core to the shell. Therefore, it is hoped that through temperature gradient calcination, the core and shell will be in their respective optimal sintering conditions to avoid core and shell composition and structural differences during the sintering process, which will cause the core and shell to shrink to varying degrees and gradually separate during the cycle, thereby improving the long-term durability of the material. Cycle performance.
基于此,本发明的第一方面提供了一种镍钴锰酸锂梯度正极材料的制备方法,包括以下步骤:Based on this, the first aspect of the present invention provides a method for preparing a lithium nickel cobalt manganate gradient cathode material, which includes the following steps:
获得镍钴锰酸锂梯度正极材料前驱体;其中,所述镍钴锰酸锂梯度正极材料前驱体中的镍含量从内核至外壳梯度下降,钴和锰含量从内核至外壳梯度上升;Obtain a lithium nickel cobalt manganate gradient cathode material precursor; wherein, the nickel content in the lithium nickel cobalt manganate gradient cathode material precursor decreases from the core to the outer shell, and the cobalt and manganese contents increase from the core to the outer shell;
将所述镍钴锰酸锂梯度正极材料前驱体和锂源混合均匀后进行梯度煅烧,获得镍钴锰酸锂梯度正极材料;其中,梯度煅烧的过程包括:控制煅烧温度使煅烧温度梯度下降。The lithium nickel cobalt manganate gradient cathode material precursor and the lithium source are mixed evenly and then gradient calcination is performed to obtain the nickel cobalt lithium manganate gradient cathode material; wherein, the gradient calcination process includes: controlling the calcination temperature to decrease the calcination temperature gradient.
本发明的第二方面提供一种镍钴锰酸锂梯度正极材料,该镍钴锰酸锂梯度正极材料通过本发明第一方面提供的镍钴锰酸锂梯度正极材料的制备方法得到。A second aspect of the present invention provides a lithium nickel cobalt manganate gradient positive electrode material, which is obtained by the preparation method of a lithium nickel cobalt manganate gradient positive electrode material provided by the first aspect of the present invention.
与现有技术相比,本发明的有益效果包括:Compared with the existing technology, the beneficial effects of the present invention include:
本发明通过温度梯度煅烧使核壳处于各自的最佳烧结条件以避免烧结过程中出现核壳成分和结构差异导致核壳在循环过程中出现不同程度的收 缩并逐渐分离,从而有效提高材料的长期循环性能。The present invention uses temperature gradient calcination to keep the core and shell in their respective optimal sintering conditions to avoid core and shell composition and structural differences during the sintering process, causing the core and shell to shrink to varying degrees and gradually separate during the cycle, thereby effectively improving the long-term durability of the material. Cycle performance.
具体实施方式Detailed ways
为了使本发明的目的、技术方案及优点更加清楚明白,以下结合实施例,对本发明进行进一步详细说明。应当理解,此处所描述的具体实施例仅仅用以解释本发明,并不用于限定本发明。In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with examples. It should be understood that the specific embodiments described here are only used to explain the present invention and are not intended to limit the present invention.
本发明的第一方面提供了一种镍钴锰酸锂梯度正极材料的制备方法,包括以下步骤:A first aspect of the invention provides a method for preparing a lithium nickel cobalt manganate gradient cathode material, which includes the following steps:
S1、获得镍钴锰酸锂梯度正极材料前驱体;其中,所述镍钴锰酸锂梯度正极材料前驱体中的镍含量从内核至外壳梯度下降,钴和锰含量从内核至外壳梯度上升;S1. Obtain a lithium nickel cobalt manganate gradient cathode material precursor; wherein, the nickel content in the nickel cobalt lithium manganate gradient cathode material precursor decreases from the core to the outer shell, and the cobalt and manganese contents increase from the core to the outer shell;
S2、将所述镍钴锰酸锂梯度正极材料前驱体和锂源混合均匀后进行梯度煅烧,获得镍钴锰酸锂梯度正极材料;其中,梯度煅烧的过程包括:控制煅烧温度使煅烧温度梯度下降。S2. Mix the lithium nickel cobalt manganate gradient cathode material precursor and the lithium source evenly and then perform gradient calcination to obtain the nickel cobalt lithium manganate gradient cathode material; wherein, the gradient calcination process includes: controlling the calcination temperature to achieve a calcination temperature gradient decline.
本发明中,获得镍钴锰酸锂梯度正极材料前驱体的步骤包括:In the present invention, the steps of obtaining the nickel-cobalt lithium manganate gradient cathode material precursor include:
S11、配制n组具有不同镍含量的含有镍源、钴源和锰源的混合盐溶液;其中,n为≥2的正整数;在本发明的一些具体实施方式中,n为3;镍源为硫酸镍、氯化镍、硝酸镍、醋酸镍中的至少一种,钴源为硫酸钴、氯化钴、硝酸钴、醋酸钴中的至少一种,锰源为硫酸锰、氯化锰、硝酸锰、醋酸锰中的至少一种。在本发明的一些具体实施方式中,按镍钴锰金属摩尔比5:2:3、7:1:2和90:5:5分别将镍源、钴源和锰源配置成三种金属比例的混合盐溶液,分别计为A金属盐溶液、B金属盐溶液、C金属盐 溶液;进一步地,上述混合盐溶液中,镍钴锰总金属离子浓度为1~3mol/L。S11. Prepare n groups of mixed salt solutions containing nickel sources, cobalt sources and manganese sources with different nickel contents; where n is a positive integer ≥ 2; in some embodiments of the present invention, n is 3; nickel source It is at least one of nickel sulfate, nickel chloride, nickel nitrate, and nickel acetate. The cobalt source is at least one of cobalt sulfate, cobalt chloride, cobalt nitrate, and cobalt acetate. The manganese source is manganese sulfate, manganese chloride, At least one of manganese nitrate and manganese acetate. In some specific embodiments of the present invention, the nickel source, cobalt source and manganese source are configured into three metal ratios according to the nickel, cobalt and manganese metal molar ratios of 5:2:3, 7:1:2 and 90:5:5 respectively. The mixed salt solutions are respectively counted as A metal salt solution, B metal salt solution, and C metal salt solution; further, in the above mixed salt solution, the total metal ion concentration of nickel, cobalt, and manganese is 1 to 3 mol/L.
S12、配制碱溶液和络合剂溶液;其中,碱为氢氧化钠、氢氧化钾中的至少一种;碱溶液的浓度为2~6mol/L,进一步为4mol/L;络合剂为氨水、柠檬酸中的至少一种;络合剂溶液的浓度为0.5~5mol/L,进一步为1mol/L。S12. Prepare an alkali solution and a complexing agent solution; wherein the alkali is at least one of sodium hydroxide and potassium hydroxide; the concentration of the alkali solution is 2 to 6 mol/L, and further 4 mol/L; the complexing agent is ammonia water , at least one of citric acid; the concentration of the complexing agent solution is 0.5~5mol/L, further 1mol/L.
S13、将n组不同镍含量的混合盐溶液依次与碱溶液、络合剂溶液混合,进行连续反应,制备得到镍钴锰酸锂梯度正极材料前驱体;其中,反应温度控制在40~60℃之间,反应pH在10~13之间,反应过程以氮气作为保护。S13. Mix n groups of mixed salt solutions with different nickel contents in sequence with an alkali solution and a complexing agent solution, and perform a continuous reaction to prepare a nickel cobalt lithium manganate gradient cathode material precursor; the reaction temperature is controlled at 40 to 60°C. The reaction pH is between 10 and 13, and the reaction process is protected by nitrogen.
本发明的步骤S13中,将n组不同镍含量的混合盐溶液依次与碱溶液、络合剂溶液混合进行连续反应的步骤包括:In step S13 of the present invention, the steps of sequentially mixing n groups of mixed salt solutions with different nickel contents with an alkali solution and a complexing agent solution for continuous reaction include:
S131、将第1组混合盐溶液、碱溶液、络合剂溶液通入反应容器中反应,得到第1次反应溶液;S131. Pour the first group of mixed salt solutions, alkali solutions, and complexing agent solutions into the reaction vessel for reaction to obtain the first reaction solution;
S132、将第i次反应溶液、第i+1组混合盐溶液、碱溶液、络合剂溶液混合反应,得到第i+1次反应溶液;S132. Mix and react the i-th reaction solution, the i+1-th group of mixed salt solutions, alkali solutions, and complexing agent solutions to obtain the i+1-th reaction solution;
S133、重复S132步骤依次进行混合反应,直至得到第n次反应溶液,并经过陈化、过滤、洗涤和干燥,得到镍钴锰酸锂梯度正极材料前驱体;S133. Repeat step S132 to perform the mixing reaction in sequence until the nth reaction solution is obtained, and undergoes aging, filtration, washing and drying to obtain the nickel cobalt lithium manganate gradient cathode material precursor;
其中,i为正整数,1≤i<i+1≤n,且第i组混合盐溶液的镍含量大于第i+1组混合盐溶液的镍含量,第i组混合盐溶液的钴锰含量小于第i+1组混合盐溶液的钴锰含量,从而实现镍含量从内核至外壳梯度下降、钴和锰含量从内核至外壳梯度上升。Among them, i is a positive integer, 1≤i<i+1≤n, and the nickel content of the i-th group of mixed salt solutions is greater than the nickel content of the i+1-th group of mixed salt solutions, and the cobalt-manganese content of the i-th group of mixed salt solutions It is less than the cobalt and manganese content of the mixed salt solution of the i+1 group, thereby achieving a gradient decrease in nickel content from the core to the outer shell, and a gradient increase in the cobalt and manganese content from the core to the outer shell.
在本发明的一些优选实施方式中,混合盐溶液、碱溶液、络合剂均以一定的流速通入反应体系中。In some preferred embodiments of the present invention, the mixed salt solution, alkali solution, and complexing agent are all introduced into the reaction system at a certain flow rate.
在本发明的一些具体实施方式中,按镍钴锰金属摩尔比5:2:3、7:1: 2和90:5:5分别将镍源、钴源和锰源配置成总金属离子浓度为1~3mol/L的混合盐溶液,分别计为A金属盐溶液、B金属盐溶液、C金属盐溶液,且混合盐溶液、碱溶液、络合剂溶液的通入速率分别为1mol/h、0.5mol/h和2mol/h,A金属盐溶液、B金属盐溶液、C金属盐溶液的反应时间分别为4h、6h、20h。In some specific embodiments of the present invention, the nickel source, the cobalt source and the manganese source are respectively configured to the total metal ion concentration according to the nickel, cobalt and manganese metal molar ratios of 5:2:3, 7:1:2 and 90:5:5. A mixed salt solution of 1 to 3 mol/L is counted as A metal salt solution, B metal salt solution, and C metal salt solution respectively, and the feed rate of the mixed salt solution, alkali solution, and complexing agent solution is 1 mol/h respectively. , 0.5mol/h and 2mol/h, the reaction times of A metal salt solution, B metal salt solution and C metal salt solution are 4h, 6h and 20h respectively.
本发明中,锂源为氢氧化锂或碳酸锂。在本发明的一些具体实施方式中,锂源为单水氢氧化锂(LiOH·H 2O)。进一步地,镍钴锰酸锂梯度正极材料前驱体与锂源的摩尔比为1:(1.01~1.1),在本发明的一些具体实施方式中,镍钴锰酸锂梯度正极材料前驱体与锂源的摩尔比为1:1.04。 In the present invention, the lithium source is lithium hydroxide or lithium carbonate. In some embodiments of the invention, the lithium source is lithium hydroxide monohydrate (LiOH·H 2 O). Further, the molar ratio of the lithium nickel cobalt manganate gradient cathode material precursor to the lithium source is 1: (1.01 to 1.1). In some embodiments of the invention, the molar ratio of the nickel cobalt lithium manganate gradient cathode material precursor to the lithium source is The molar ratio of sources is 1:1.04.
本发明中,根据镍钴锰酸锂梯度正极材料前驱体各层的最佳烧结温度控制煅烧温度使煅烧温度梯度下降,使各层结构分别处于其各自的最佳烧结温度以避免烧结过程中出现核壳成分和结构差异导致核壳在循环过程中出现不同程度的收缩并逐渐分离,从而提高材料的长期循环性能。镍钴锰酸锂梯度正极材料前驱体各层的最佳烧结温度通过对锂盐和不同组成的镍钴锰酸锂三元正极材料前驱体在不同温度下进行一次烧结DOE试验获得,由于时间和成本的原因,不同配比的波动范围为±0.01,不同温度的波动范围一般为±10℃,由上述所述DOE试验得到的镍钴锰酸锂三元正极材料,经过电化学测试后,放电比容量最大、循环性能最好的烧结参数(温度等)即为最佳值,该过程为现有技术,在此不做详述。在本发明的一些具体实施方式中,经过DOE实验,前驱体氢氧化物Ni 0.81Co 0.08Mn 0.11(OH) 2的最佳烧结温度为800~820℃,前驱体氢氧化物Ni 0.5Co 0.2Mn 0.3(OH) 2的最佳烧结温度为900~920℃,前驱体氢氧化物Ni 0.7Co 0.1Mn 0.2(OH) 2的最佳烧结温度为 840~860℃,前驱体氢氧化物Ni 0.90Co 0.05Mn 0.05(OH) 2的最佳烧结温度为740~760℃。进一步地,梯度煅烧的过程在氧气气氛下进行。 In the present invention, the calcination temperature is controlled according to the optimal sintering temperature of each layer of the nickel cobalt lithium manganate gradient cathode material precursor to reduce the calcination temperature gradient, so that each layer structure is at its own optimal sintering temperature to avoid occurrences during the sintering process. The differences in the composition and structure of the core and shell cause the core and shell to shrink to varying degrees and gradually separate during the cycle, thus improving the long-term cycle performance of the material. The optimal sintering temperature of each layer of the gradient cathode material precursor of lithium nickel cobalt manganate was obtained by conducting a sintering DOE test on lithium salt and lithium nickel cobalt manganate ternary cathode material precursor of different compositions at different temperatures. Due to time and Due to cost reasons, the fluctuation range of different proportions is ±0.01, and the fluctuation range of different temperatures is generally ±10°C. The nickel cobalt lithium manganate ternary cathode material obtained from the above-mentioned DOE test has been discharged after electrochemical testing. The sintering parameters (temperature, etc.) with the largest specific capacity and best cycle performance are the optimal values. This process is an existing technology and will not be described in detail here. In some specific embodiments of the present invention, through DOE experiments, the optimal sintering temperature of the precursor hydroxide Ni 0.81 Co 0.08 Mn 0.11 (OH) 2 is 800 to 820°C, and the optimal sintering temperature of the precursor hydroxide Ni 0.5 Co 0.2 Mn The optimal sintering temperature of 0.3 (OH) 2 is 900~920℃, the optimal sintering temperature of precursor hydroxide Ni 0.7 Co 0.1 Mn 0.2 (OH) 2 is 840~860℃, and the optimal sintering temperature of precursor hydroxide Ni 0.90 Co The optimal sintering temperature of 0.05 Mn 0.05 (OH) 2 is 740~760℃. Furthermore, the gradient calcination process was carried out in an oxygen atmosphere.
在本发明的一些优选实施方式中,最低烧结温度对应的烧结时间为6~12h,除最低烧结温度的其他烧结温度对应的烧结时间为0.5~1.5h。在该时间范围内,所得镍钴锰酸锂梯度正极材料具有更优的电池性能。In some preferred embodiments of the present invention, the sintering time corresponding to the lowest sintering temperature is 6 to 12 hours, and the sintering time corresponding to other sintering temperatures except the lowest sintering temperature is 0.5 to 1.5 hours. Within this time range, the obtained lithium nickel cobalt manganate gradient cathode material has better battery performance.
在本发明的一些优选实施方式中,上述梯度煅烧过程中,还加入了助熔剂。本发明通过在梯度煅烧过程中引入助熔剂,可以降低外壳部分煅烧温度,使外壳材料在相对较低温度下重结晶,减少外层壳部分与核部分的温度差,减弱在烧结过程中出现核壳之间成分和结构上的差异使内核与外壳在循环过程中出现不同程度的收缩、分离,最终提高正极材料的循环性能。但助熔剂的加入量也不宜过高。优选地,镍钴锰酸锂梯度正极材料前驱体与助溶剂的摩尔比为1:(0.00001~0.003),更进一步为1:(0.00001~0.001);助溶剂选自硼、硅、镁、钙的氧化物、氢氧化物、碳酸盐或氯化物中的至少一种。In some preferred embodiments of the present invention, a flux is also added during the above gradient calcination process. By introducing flux in the gradient calcination process, the present invention can reduce the calcination temperature of the shell part, make the shell material recrystallize at a relatively low temperature, reduce the temperature difference between the outer shell part and the core part, and weaken the occurrence of cores during the sintering process. The differences in composition and structure between the shells cause the core and shell to shrink and separate to varying degrees during the cycle, ultimately improving the cycle performance of the cathode material. However, the amount of flux added should not be too high. Preferably, the molar ratio of the nickel cobalt lithium manganate gradient cathode material precursor to the cosolvent is 1: (0.00001~0.003), and further is 1: (0.00001~0.001); the cosolvent is selected from boron, silicon, magnesium, and calcium. At least one of oxides, hydroxides, carbonates or chlorides.
本发明的第二方面提供一种镍钴锰酸锂梯度正极材料,该镍钴锰酸锂梯度正极材料通过本发明第一方面提供的镍钴锰酸锂梯度正极材料的制备方法得到。A second aspect of the present invention provides a lithium nickel cobalt manganate gradient positive electrode material, which is obtained by the preparation method of a lithium nickel cobalt manganate gradient positive electrode material provided by the first aspect of the present invention.
为避免赘述,本发明以下各实施例和对比例中,从核至壳镍含量逐渐下降的梯度前驱体氢氧化物的制备过程如下:To avoid redundancy, in the following examples and comparative examples of the present invention, the preparation process of the gradient precursor hydroxide with the nickel content gradually decreasing from the core to the shell is as follows:
按镍钴锰金属摩尔比5:2:3、7:1:2和90:5:5,分别将NiSO 4·6H 2O、CoSO 4·7H 2O和MnSO 4·H 2O配置成总金属离子浓度为2mol/L的A、B、C三种金属比例的混合盐溶液;再配置好1mol/L氨水溶液和4mol/L氢氧化钠 溶液;先将C中的高镍金属盐溶液、NaOH溶液和氨水溶液按照1mol/h、0.5mol/h和2mol/h的泵速同时泵入反应釜中,反应温度控制在40-60℃之间,反应pH在10-13之间,反应过程以氮气作为保护;该过程中,通入釜内的金属离子通过氨根离子的络合,均匀形成大量的核;反应进行20h后,再将C切换为B金属盐溶液通入釜内,形成中间缓冲层;继续反应6h后,将A混合盐溶液通入釜内,继续反应4h后结束;经过陈化、过滤、洗涤和干燥得到从核至壳镍含量逐渐下降的梯度前驱体氢氧化物Ni 0.81Co 0.08Mn 0.11(OH) 2According to the nickel-cobalt-manganese metal molar ratios of 5:2:3, 7:1:2 and 90:5:5, NiSO 4 ·6H 2 O, CoSO 4 ·7H 2 O and MnSO 4 ·H 2 O are respectively configured into the total A mixed salt solution with a metal ion concentration of 2mol/L of A, B, and C; then prepare a 1mol/L ammonia solution and a 4mol/L sodium hydroxide solution; first add the high-nickel metal salt solution in C, NaOH solution and ammonia solution were simultaneously pumped into the reaction kettle at pump speeds of 1 mol/h, 0.5 mol/h and 2 mol/h. The reaction temperature was controlled between 40-60°C and the reaction pH was between 10-13. The reaction process Use nitrogen as protection; during this process, the metal ions passed into the kettle are complexed by ammonium ions, uniformly forming a large number of nuclei; after the reaction proceeds for 20 hours, C is switched to B metal salt solution and is passed into the kettle to form Intermediate buffer layer; after continuing the reaction for 6 hours, pass the A mixed salt solution into the kettle, and continue the reaction for 4 hours before ending; after aging, filtration, washing and drying, a gradient precursor hydroxide with a gradually decreasing nickel content from the core to the shell is obtained Ni 0.81 Co 0.08 Mn 0.11 (OH) 2 .
实施例1Example 1
将梯度前驱体氢氧化物、单水LiOH、氧化硼按照1:1.04:0.001的摩尔比例称取后,置于球磨罐内混合均匀,将混合料放在氧气气氛炉中进行梯度煅烧,反应结束后,经过冷却、破碎和过筛得到梯度正极材料。其中,梯度煅烧过程具体为:首先将温度按照2℃/min的升温速率从室温升至900℃,保温1h,再按照5℃/min的降温速率将温度降至850℃,继续保温1h,最后将温度降至750℃后保温10h。Weigh the gradient precursor hydroxide, LiOH monohydrate, and boron oxide according to the molar ratio of 1:1.04:0.001, place them in a ball mill tank and mix them evenly. Place the mixture in an oxygen atmosphere furnace for gradient calcination. The reaction is completed. Finally, the gradient cathode material is obtained after cooling, crushing and sieving. Among them, the specific gradient calcination process is as follows: first, the temperature is raised from room temperature to 900°C at a heating rate of 2°C/min, kept for 1 hour, then lowered to 850°C at a cooling rate of 5°C/min, and kept for 1 hour. Finally, the temperature was lowered to 750°C and kept warm for 10 hours.
实施例2Example 2
将梯度前驱体氢氧化物、单水LiOH按照1:1.04的摩尔比例称取后,置于球磨罐内混合均匀,将混合料放在氧气气氛炉中进行梯度煅烧,反应结束后,经过冷却、破碎和过筛得到梯度正极材料。其中,梯度煅烧过程具体为:首先将温度按照2℃/min的升温速率从室温升至920℃,保温1h,再按照5℃/min的降温速率将温度降至850℃,继续保温1h,最后将温度降至750℃后保温10h。Weigh the gradient precursor hydroxide and monohydrate LiOH according to the molar ratio of 1:1.04, place them in a ball mill tank and mix them evenly. Place the mixture in an oxygen atmosphere furnace for gradient calcination. After the reaction is completed, cool and Crush and sieve to obtain gradient cathode material. Among them, the specific gradient calcination process is as follows: first, the temperature is raised from room temperature to 920°C at a heating rate of 2°C/min, kept for 1 hour, then lowered to 850°C at a cooling rate of 5°C/min, and kept for 1 hour. Finally, the temperature was lowered to 750°C and kept warm for 10 hours.
实施例3Example 3
将梯度前驱体氢氧化物、单水LiOH和氧化硼按照1:1.04:0.003的摩尔比例称取后,置于球磨罐内混合均匀,将混合料放在氧气气氛炉中进行梯度煅烧,反应结束后,经过冷却、破碎和过筛得到梯度正极材料。其中,梯度煅烧过程具体为:首先将温度按照2℃/min的升温速率从室温升至900℃,保温1h,再按照5℃/min的降温速率将温度降至850℃,继续保温1h,最后再降温至750℃保温10h。After weighing the gradient precursor hydroxide, LiOH monohydrate and boron oxide according to the molar ratio of 1:1.04:0.003, place them in a ball mill tank and mix them evenly. Place the mixture in an oxygen atmosphere furnace for gradient calcination. The reaction is completed. Finally, the gradient cathode material is obtained after cooling, crushing and sieving. Among them, the specific gradient calcination process is as follows: first, the temperature is raised from room temperature to 900°C at a heating rate of 2°C/min, kept for 1 hour, then lowered to 850°C at a cooling rate of 5°C/min, and kept for 1 hour. Finally, the temperature was lowered to 750°C and kept for 10 hours.
实施例4Example 4
将梯度前驱体氢氧化物、单水LiOH和氧化硼按照1:1.04:0.005的摩尔比例称取后,置于球磨罐内混合均匀,将混合料放在氧气气氛炉中进行梯度煅烧,反应结束后,经过冷却、破碎和过筛得到梯度正极材料。其中,梯度煅烧过程具体为:首先将温度按照2℃/min的升温速率从室温升至900℃,保温1h,再按照5℃/min的降温速率将温度降至850℃,继续保温1h,最后再降温至750℃保温10h。Weigh the gradient precursor hydroxide, LiOH monohydrate and boron oxide according to the molar ratio of 1:1.04:0.005, mix them evenly in a ball mill jar, and place the mixture in an oxygen atmosphere furnace for gradient calcination. The reaction is completed. Finally, the gradient cathode material is obtained after cooling, crushing and sieving. Among them, the specific gradient calcination process is as follows: first, the temperature is raised from room temperature to 900°C at a heating rate of 2°C/min, kept for 1 hour, then lowered to 850°C at a cooling rate of 5°C/min, and kept for 1 hour. Finally, the temperature was lowered to 750°C and kept for 10 hours.
对比例1Comparative example 1
将梯度前驱体氢氧化物、单水LiOH、氧化硼按照1:1.04:0.001的摩尔比例称取后,置于球磨罐内混合均匀,将混合料放在氧气气氛炉中进行梯度煅烧,反应结束后,经过冷却、破碎和过筛得到梯度正极材料。其中,梯度煅烧过程具体为:首先将温度按照2℃/min的升温速率从室温升至750℃,保温10h,再将温度升至850℃,继续保温1h,最后将温度升至900℃后保温1h。Weigh the gradient precursor hydroxide, LiOH monohydrate, and boron oxide according to the molar ratio of 1:1.04:0.001, place them in a ball mill tank and mix them evenly. Place the mixture in an oxygen atmosphere furnace for gradient calcination. The reaction is completed. Finally, the gradient cathode material is obtained after cooling, crushing and sieving. Among them, the specific gradient calcination process is: first, the temperature is raised from room temperature to 750°C at a heating rate of 2°C/min, kept for 10 hours, then the temperature is raised to 850°C, kept for 1 hour, and finally the temperature is raised to 900°C. Keep warm for 1 hour.
对比例2Comparative example 2
将梯度前驱体氢氧化物、单水LiOH、氧化硼按照1:1.04:0.001的摩尔比例称取后,置于球磨罐内混合均匀,将混合料放在氧气气氛炉中进行梯度煅烧,反应结束后,经过冷却、破碎和过筛得到梯度正极材料。其中,梯度煅烧过程具体为:首先将温度按照2℃/min的升温速率从室温升至900℃,保温4h,再按照5℃/min的降温速率将温度降至850℃,继续保温4h,最后将温度降至750℃后保温4h。Weigh the gradient precursor hydroxide, LiOH monohydrate, and boron oxide according to the molar ratio of 1:1.04:0.001, place them in a ball mill tank and mix them evenly. Place the mixture in an oxygen atmosphere furnace for gradient calcination. The reaction is completed. Finally, the gradient cathode material is obtained after cooling, crushing and sieving. Among them, the gradient calcination process is as follows: first, the temperature is raised from room temperature to 900°C at a heating rate of 2°C/min, maintained for 4 hours, and then lowered to 850°C at a cooling rate of 5°C/min, and maintained for 4 hours. Finally, the temperature was lowered to 750°C and kept warm for 4 hours.
对比例3Comparative example 3
将梯度前驱体氢氧化物、单水LiOH按照1:1.04的摩尔比例称取后,置于球磨罐内混合均匀,将混合料放在氧气气氛炉中进行煅烧,反应结束后,经过冷却、破碎和过筛得到梯度正极材料。其中,煅烧过程具体为:将温度升至820℃保温12h。Weigh the gradient precursor hydroxide and monohydrate LiOH according to the molar ratio of 1:1.04, place them in a ball mill tank and mix them evenly. Place the mixture in an oxygen atmosphere furnace for calcination. After the reaction is completed, it is cooled and crushed. and sieved to obtain gradient cathode materials. Among them, the specific calcination process is: raising the temperature to 820°C and holding it for 12 hours.
对比例4Comparative example 4
将梯度前驱体氢氧化物、单水LiOH和氧化硼按照1:1.04:0.001的摩尔比例称取后,置于球磨罐内混合均匀,将混合料放在氧气气氛炉中进行煅烧,反应结束后,经过冷却、破碎和过筛得到梯度正极材料。其中,煅烧过程具体为:将温度升至800℃保温12h。Weigh the gradient precursor hydroxide, LiOH monohydrate and boron oxide according to the molar ratio of 1:1.04:0.001, place them in a ball mill tank and mix them evenly. Place the mixture in an oxygen atmosphere furnace for calcination. After the reaction is completed , after cooling, crushing and screening, the gradient cathode material is obtained. Among them, the specific calcination process is: raising the temperature to 800°C and holding it for 12 hours.
试验组test group
将制备的正极材料分别与导电剂乙炔炭黑,粘结剂PVDF按照质量比92:4:4比例混合均匀,加入适量的1-甲基-2吡咯烷酮球磨1小时配成浆料均匀涂在铝片上,烘干、压片制成正极片。以金属锂片为负极组装成2032扣式电池,采用蓝电测试系统进行电性能测试,充放电电压2.5~4.25V,首圈按照0.2/0.2C充放电测试,再以0.5C/1C循环50圈。具体测试结果见表 1。Mix the prepared positive electrode material with the conductive agent acetylene carbon black and the binder PVDF according to the mass ratio of 92:4:4, add an appropriate amount of 1-methyl-2-pyrrolidone and ball-mill for 1 hour to form a slurry that is evenly coated on aluminum on the sheet, dried and pressed into sheets to make positive electrode sheets. A 2032 button battery is assembled with metal lithium sheets as the negative electrode. The blue battery test system is used for electrical performance testing. The charge and discharge voltage is 2.5~4.25V. The first cycle is charged and discharged at 0.2/0.2C, and then cycled at 0.5C/1C for 50 seconds. lock up. The specific test results are shown in Table 1.
表1Table 1
Figure PCTCN2022108632-appb-000001
Figure PCTCN2022108632-appb-000001
通过表1可以看出,本发明实施例1~4所得梯度正极材料明显具有更好的循环性能。It can be seen from Table 1 that the gradient cathode materials obtained in Examples 1 to 4 of the present invention obviously have better cycle performance.
以上所述本发明的具体实施方式,并不构成对本发明保护范围的限定。任何根据本发明的技术构思所做出的各种其他相应的改变与变形,均应包含在本发明权利要求的保护范围内。The above-described specific embodiments of the present invention do not limit the scope of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention shall be included in the protection scope of the claims of the present invention.

Claims (10)

  1. 一种镍钴锰酸锂梯度正极材料的制备方法,其特征在于,包括以下步骤:A method for preparing a lithium nickel cobalt manganate gradient cathode material, which is characterized by comprising the following steps:
    获得镍钴锰酸锂梯度正极材料前驱体;其中,所述镍钴锰酸锂梯度正极材料前驱体中的镍含量从内核至外壳梯度下降,钴和锰含量从内核至外壳梯度上升;Obtain a lithium nickel cobalt manganate gradient cathode material precursor; wherein, the nickel content in the lithium nickel cobalt manganate gradient cathode material precursor decreases from the core to the outer shell, and the cobalt and manganese contents increase from the core to the outer shell;
    将所述镍钴锰酸锂梯度正极材料前驱体和锂源混合均匀后进行梯度煅烧,获得镍钴锰酸锂梯度正极材料;其中,所述梯度煅烧的过程包括:控制煅烧温度使所述煅烧温度梯度下降。Mix the lithium nickel cobalt manganate gradient cathode material precursor and the lithium source evenly and then perform gradient calcination to obtain the nickel cobalt lithium manganate gradient cathode material; wherein the gradient calcination process includes: controlling the calcination temperature to make the calcination Temperature gradient decreases.
  2. 根据权利要求1所述镍钴锰酸锂梯度正极材料的制备方法,其特征在于,所述获得镍钴锰酸锂梯度正极材料前驱体的步骤包括:The preparation method of lithium nickel cobalt manganate gradient cathode material according to claim 1, characterized in that the step of obtaining the precursor of lithium nickel cobalt manganate gradient cathode material includes:
    S11、配制n组具有不同镍含量的含有镍源、钴源和锰源的混合盐溶液;S11. Prepare n groups of mixed salt solutions containing nickel source, cobalt source and manganese source with different nickel contents;
    S12、配制碱溶液和络合剂溶液;S12. Prepare alkali solution and complexing agent solution;
    S13、将n组不同镍含量的混合盐溶液依次与碱溶液、络合剂溶液混合,进行连续反应,制备得到镍钴锰酸锂梯度正极材料前驱体;S13. Mix n groups of mixed salt solutions with different nickel contents in sequence with an alkali solution and a complexing agent solution, and perform continuous reactions to prepare a nickel cobalt lithium manganate gradient cathode material precursor;
    其中,n为≥2的正整数。Among them, n is a positive integer ≥ 2.
  3. 根据权利要求2所述镍钴锰酸锂梯度正极材料的制备方法,其特征在于,将n组不同镍含量的混合盐溶液依次与碱溶液、络合剂溶液混合进行连续反应的步骤包括:The preparation method of lithium nickel cobalt manganate gradient cathode material according to claim 2, characterized in that the step of mixing n groups of mixed salt solutions with different nickel contents with an alkali solution and a complexing agent solution for continuous reaction includes:
    S131、将第1组混合盐溶液、碱溶液、络合剂溶液通入反应容器中反应,得到第1次反应溶液;S131. Pour the first group of mixed salt solutions, alkali solutions, and complexing agent solutions into the reaction vessel for reaction to obtain the first reaction solution;
    S132、将第i次反应溶液、第i+1组混合盐溶液、碱溶液、络合剂溶液 混合反应,得到第i+1次反应溶液;S132. Mix and react the i-th reaction solution, the i+1-th group of mixed salt solutions, alkali solutions, and complexing agent solutions to obtain the i+1-th reaction solution;
    S133、重复S132步骤依次进行混合反应,直至得到第n次反应溶液,并经过陈化、过滤、洗涤和干燥,得到镍钴锰酸锂梯度正极材料前驱体;S133. Repeat step S132 to perform the mixing reaction in sequence until the nth reaction solution is obtained, and undergoes aging, filtration, washing and drying to obtain the nickel cobalt lithium manganate gradient cathode material precursor;
    其中,i为正整数,1≤i<i+1≤n,且第i组混合盐溶液的镍含量大于第i+1组混合盐溶液的镍含量,第i组混合盐溶液的钴锰含量小于第i+1组混合盐溶液的钴锰含量。Among them, i is a positive integer, 1≤i<i+1≤n, and the nickel content of the i-th group of mixed salt solutions is greater than the nickel content of the i+1-th group of mixed salt solutions, and the cobalt-manganese content of the i-th group of mixed salt solutions Less than the cobalt and manganese content of the mixed salt solution of the i+1 group.
  4. 根据权利要求2所述镍钴锰酸锂梯度正极材料的制备方法,其特征在于,n为3,且所述配制n组具有不同镍含量的含有镍源、钴源和锰源的混合盐溶液包括:按镍钴锰金属摩尔比5:2:3、7:1:2和90:5:5分别将镍源、钴源和锰源配置成三种金属比例的混合盐溶液。The preparation method of lithium nickel cobalt manganate gradient cathode material according to claim 2, characterized in that n is 3, and the preparation of n groups of mixed salt solutions containing nickel source, cobalt source and manganese source with different nickel contents It includes: configuring the nickel source, cobalt source and manganese source into a mixed salt solution with three metal ratios according to the nickel, cobalt and manganese metal molar ratios of 5:2:3, 7:1:2 and 90:5:5 respectively.
  5. 根据权利要求2所述镍钴锰酸锂梯度正极材料的制备方法,其特征在于,所述将n组不同镍含量的混合盐溶液依次与碱溶液、络合剂溶液混合,进行连续反应的步骤中,反应温度控制在40~60℃之间,反应pH为10~13,反应过程以氮气作为保护。The preparation method of lithium nickel cobalt manganate gradient cathode material according to claim 2, characterized in that the step of mixing n groups of mixed salt solutions with different nickel contents with an alkali solution and a complexing agent solution in sequence to perform a continuous reaction , the reaction temperature is controlled between 40 and 60°C, the reaction pH is between 10 and 13, and nitrogen is used as protection during the reaction process.
  6. 根据权利要求1所述镍钴锰酸锂梯度正极材料的制备方法,其特征在于,根据镍钴锰酸锂梯度正极材料前驱体各层的最佳烧结温度控制煅烧温度使煅烧温度梯度下降;所述镍钴锰酸锂梯度正极材料前驱体各层的最佳烧结温度通过对锂盐和不同组成的镍钴锰酸锂三元正极材料前驱体在不同温度下进行一次烧结DOE试验获得,由所述DOE试验得到的镍钴锰酸锂三元正极材料,经过电化学测试后,放电比容量最大、循环性能最好的烧结温度即为最佳烧结温度。The preparation method of lithium nickel cobalt manganate gradient cathode material according to claim 1, characterized in that the calcination temperature is controlled according to the optimal sintering temperature of each layer of the lithium nickel cobalt manganate gradient cathode material precursor to reduce the calcination temperature gradient; The optimal sintering temperature of each layer of the lithium nickel cobalt manganate gradient cathode material precursor was obtained by conducting a sintering DOE test on lithium salts and lithium nickel cobalt manganate ternary cathode material precursors of different compositions at different temperatures. For the lithium nickel cobalt manganate ternary cathode material obtained from the DOE test, after electrochemical testing, the sintering temperature with the largest discharge specific capacity and the best cycle performance is the optimal sintering temperature.
  7. 根据权利要求1所述镍钴锰酸锂梯度正极材料的制备方法,其特征在于,所述梯度煅烧的过程在氧气气氛下进行。The method for preparing a gradient cathode material of lithium nickel cobalt manganate according to claim 1, characterized in that the gradient calcination process is carried out in an oxygen atmosphere.
  8. 根据权利要求1所述镍钴锰酸锂梯度正极材料的制备方法,其特征在于,最低烧结温度对应的烧结时间为6~12h,除最低烧结温度的其他烧结温度对应的烧结时间为0.5~1.5h。The preparation method of lithium nickel cobalt manganate gradient cathode material according to claim 1, characterized in that the sintering time corresponding to the lowest sintering temperature is 6 to 12 hours, and the sintering time corresponding to other sintering temperatures except the lowest sintering temperature is 0.5 to 1.5 h.
  9. 根据权利要求1所述镍钴锰酸锂梯度正极材料的制备方法,其特征在于,所述梯度煅烧过程中,还加入了助熔剂,且所述镍钴锰酸锂梯度正极材料前驱体与助溶剂的摩尔比为1:(0.00001~0.003);所述助溶剂选自硼、硅、镁、钙的氧化物、氢氧化物、碳酸盐或氯化物中的至少一种。The preparation method of lithium nickel cobalt manganate gradient cathode material according to claim 1, characterized in that, during the gradient calcination process, a flux is also added, and the precursor of the lithium nickel cobalt manganate gradient cathode material is mixed with a flux. The molar ratio of the solvent is 1: (0.00001-0.003); the co-solvent is selected from at least one of boron, silicon, magnesium and calcium oxides, hydroxides, carbonates or chlorides.
  10. 一种镍钴锰酸锂梯度正极材料,其特征在于,所述镍钴锰酸锂梯度正极材料通过权利要求1~9中任一项所述镍钴锰酸锂梯度正极材料的制备方法得到。A lithium nickel cobalt manganate gradient cathode material, characterized in that the lithium nickel cobalt manganate gradient cathode material is obtained by the preparation method of the lithium nickel cobalt manganate gradient cathode material described in any one of claims 1 to 9.
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