CN112194198B - Porous high-rate ternary material and preparation method thereof - Google Patents

Porous high-rate ternary material and preparation method thereof Download PDF

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CN112194198B
CN112194198B CN202010881538.3A CN202010881538A CN112194198B CN 112194198 B CN112194198 B CN 112194198B CN 202010881538 A CN202010881538 A CN 202010881538A CN 112194198 B CN112194198 B CN 112194198B
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伏萍萍
徐宁
吕菲
宋英杰
吴孟涛
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Tianjin B&M Science and Technology Co Ltd
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Abstract

A high-multiplying-power nickel-cobalt-manganese-lithium anode material with a porous structure is characterized in that the inside of the anode material is of the porous structure; in the preparation process of the anode material, a pulse crystallization control technology with differentiated bulk phase deposition density areas and a technology for manufacturing pores by using a segmented high-temperature solid-phase reaction of the anode material are adopted, and the preparation method comprises two steps of preparing a nickel-cobalt-manganese-lithium precursor by a pulse method and preparing the nickel-cobalt-manganese-lithium precursor by the pulse method. According to the invention, a precursor with differentiated bulk phase deposition density areas is developed through the crystallization process control of the precursor; and the high-density large-particle precursor reacts later to form a skeleton structure of secondary particles. The prepared porous anode material has the characteristics of high specific capacity, and excellent coulombic efficiency, multiplying power and cycle performance.

Description

Porous high-rate ternary material and preparation method thereof
Technical Field
The invention relates to the field of lithium ion secondary battery anode materials, in particular to a preparation method of a nickel-cobalt-manganese-lithium anode material with a porous structure.
Background
With the continuous popularization and spread of new energy vehicles, ternary materials have become the most mainstream power battery anode materials applied to the new energy vehicles. The high-rate charge-discharge performance of the battery determines the response sensitivity of the electric vehicle, and the cycle life of the battery directly influences the service life of the electric vehicle, so that the rate performance and the cycle life are one of key indexes for measuring the anode material product of the power battery.
Most of the nickel-cobalt-manganese-lithium anode materials commercialized in the current market are solid primary particles or secondary agglomerated particles, the lithium ion conduction path is long, the efficiency of lithium intercalation of active substances under the high-current charge-discharge density is greatly reduced, and the high-rate specific capacity is reduced; on the other hand, the volume change of the active material in the repeated charging and discharging process forms stress, so that cracks and even pulverization appear in the particles, and the cycle life of the battery is shortened. Therefore, how to increase the specific capacity of the material and reduce the volume strain of the active material becomes a technical problem.
Disclosure of Invention
The invention aims to provide a preparation method of a cathode material with excellent rate capability, cycle performance and small volume strain aiming at the problems of a nickel-cobalt-manganese-lithium cathode material.
In order to solve the technical problems, the technical scheme adopted by the invention is as follows:
a preparation method of a porous high-rate ternary material comprises the following steps:
1) Preparing an ammonia water solution, placing the ammonia water solution in a precursor reaction kettle, adding deionized water to adjust the pH value to be within the range of 10-13, and forming a complexing agent solution I;
2) Preparing a soluble salt solution II containing Ni, co and Mn elements according to a designed molar ratio;
3) Pumping the soluble salt solution II into the complexing agent solution I at a constant speed by using a pump to form Ni, co and Mn-ammonia complex ion mother liquor III;
4) Preparing an alkali solution IV, pumping the alkali solution IV into a reaction kettle, simultaneously pumping the alkali solution IV into the reaction kettle at a set speed in cooperation with an ion mother solution III, and controlling the pH value of the solution to be in a pulse change range of 10-13 by adjusting the flow speed of the alkali solution IV; stirring in the reaction kettle at a rotating speed of 100-500 r/min, keeping the temperature of the solution in the reaction kettle at 30-80 ℃, and reacting for no less than 10h to obtain slurry V after the reaction is completed;
the pulse change of the pH value of the solution between 10 and 13 means that the pH value of the solution is alternately changed between 10 and 13 and is maintained for a certain reaction time at the pH value;
5) After the reaction is finished, carrying out solid-liquid separation on the slurry V, washing the solid with deionized water, drying the solid at 100-150 ℃, and sieving to obtain a precursor VI;
6) Weighing the precursor VI, the lithium salt and the additive according to the designed molar ratio, fully and uniformly mixing, placing in an oxygen-containing atmosphere for high-temperature solid-phase reaction, crushing the product, sieving, and demagnetizing to obtain the porous high-rate ternary material.
Preferably, the soluble salt solution II in the step 2) is more than or equal to 0.5 of Ni/(Ni + Co + Mn) in molar ratio.
Preferably, the alkali solution IV in the step 3) is one or two of sodium hydroxide and potassium hydroxide solution, and the concentration is 2-5 mol/L.
Preferably, the pulse condition in the step 4) is that the pulse pH is low-point pH = 10-11, and the duration is 30 min-60 min; the pulse pH high point pH = 12-13, and the duration is 10 min-30 min. (ii) a
Preferably, the designed molar ratio in the step 6) is as follows: li/(Ni + Co + Mn) = 0.99-1.1, and additive/(Ni + Co + Mn) = 0.001-0.1.
Preferably, the additive in step 6) contains one or more elements selected from Ti, mg, al, zr, V, mo, nb, W, Y, sr, etc.
Preferably, the high-temperature solid-phase reaction in the step 6) is a segmented high-temperature solid-phase reaction, and more than 2 temperature platforms are arranged.
Further, the sectional high-temperature solid-phase reaction in the step 6) is divided into 2 temperature platforms, the temperature platform 1 is set to be 400-800 ℃, and the temperature is kept for 2-8 hours; the temperature platform 2 is set to be 780-980 ℃ and is kept for 2-48 h.
The porous high-rate ternary material prepared by the preparation method is applied to lithium ion batteries.
The beneficial effects of the invention are: and introducing pH pulse change in the preparation process of the precursor, wherein the introduction of the step can controllably adjust the ordered change of the size and the density of the precursor primary whiskers, so that primary particles with smaller sizes preferentially undergo softening and solid phase diffusion reactions at lower reaction temperatures in the high-temperature reaction step with a lithium source and migrate to primary particles with larger sizes under the siphoning action in the particles, thereby forming a porous structure in the particles of the positive electrode material.
The rate performance of the porous high-rate ternary material particles can be improved by increasing the internal porosity of the porous high-rate ternary material particles, so that the high-rate charge and discharge performance of the power battery is further improved; on the other hand, the internal pores of the particles provide elastic space for the volume change of the material in the charge and discharge processes, so that the cycle life of the material is prolonged.
Drawings
FIG. 1 is a SEM image of a cross section of a porous high-magnification nickel cobalt manganese lithium material prepared in example 1 of the invention;
FIG. 2 is a flow chart of a preparation process of the porous high-rate nickel cobalt manganese lithium material provided by the invention.
Detailed Description
The present invention will be further described with reference to fig. 1 and 2.
A preparation method of a porous high-rate ternary material comprises the following steps:
1) Preparing an ammonia water solution, placing the ammonia water solution in a precursor reaction kettle, adding deionized water to adjust the pH value to be within the range of 10-13, and forming a complexing agent solution I;
2) Preparing a soluble salt solution II containing Ni, co and Mn elements according to a designed molar ratio;
3) Preparing an alkali solution III with a certain molar concentration;
4) Continuously pumping a complexing agent solution I, a soluble salt solution II and an alkali solution III into a reaction kettle respectively, and regulating the pH value of the solution to be between 10 and 13 through controlling the flow rate of the alkali solution III; the stirring speed in the reaction kettle is 100-500 r/min, the temperature of the solution in the reaction kettle is kept at 30-80 ℃, and the reaction time is not less than 10h;
the pulse change of the pH value of the solution between 10 and 13 means that the pH value of the solution is alternately changed between 10 and 13 and is maintained for a certain reaction time at the pH value;
5) After the reaction is finished, carrying out solid-liquid separation on the slurry, washing the solid with deionized water, drying the solid at 100-150 ℃, and sieving to obtain a precursor IV;
6) Weighing the precursor IV, the lithium salt and the additive according to a designed proportion, fully and uniformly mixing, placing in an oxygen-containing atmosphere for high-temperature solid-phase reaction, crushing a product, sieving, and demagnetizing to obtain the porous high-rate ternary material.
The invention introduces the step of solution pH pulse change, the introduction of the step can controllably adjust the ordered change of the size and the density of the precursor primary whisker, and further, when the step of high-temperature reaction with a lithium source is carried out, primary particles with smaller sizes preferentially undergo softening and solid-phase diffusion reaction at lower reaction temperature and diffuse to the surface and pores of large particles, so that a porous structure is formed inside the anode material particles.
In this step, the choice of the pH and the reaction time at each pH point have a significant influence on the product formation. Selection of the appropriate pH and reaction time controls and varies the size of the precursor primary whiskers, which in turn has a direct effect on the pore size and porosity of the positive electrode material.
Preferably, in the soluble salt solution II in the step 2), the molar ratio of Ni/(Ni + Co + Mn) is more than or equal to 0.5.
Preferably, the alkali solution III in the step 3) is one or two of sodium hydroxide and potassium hydroxide, and the concentration is 2-5 mol/L.
Preferably, the conditions for the solution pH in step 4) to vary in pulses between 10 and 13 are: pulse low-point pH = 10-11, and the duration is 30 min-60 min; the pulse high point pH = 12-13, and the duration is 10 min-30 min.
In the invention, the range of pH pulse change is further optimized, when the pH is more than or equal to 11, the deposition speed is high, the growth time is controlled, and primary particles with small crystal grains and low density can be obtained; when the pH value is less than 11, the deposition speed is slow, and primary particles with large crystal grains and high density can be obtained by properly prolonging the time; the primary particles with small crystal grains and low density are easy to form cavities in the high-temperature solid-phase reaction step with the lithium source, and the primary particles with large crystal grains and high density are easier to form solid particles in the high-temperature solid-phase reaction step with the lithium source.
Preferably, in step 6), the design ratio is, in terms of molar ratio, li/(Ni + Co + Mn) =0.99 to 1.1, and additive/(Ni + Co + Mn) =0.001 to 0.1.
Preferably, the additive in step 6) contains one or more elements selected from Ti, mg, al, zr, V, mo, nb, W, Y, sr, etc.
Preferably, the high-temperature solid-phase reaction in the step 6) is a segmented high-temperature solid-phase reaction, and more than 2 temperature platforms are arranged.
Preferably, the sectional high-temperature solid-phase reaction in the step 6) is divided into 2 temperature platforms, the temperature platform 1 is set to be 400-800 ℃, and the temperature is kept for 2-8 hours; the temperature platform 2 is set to be 780-980 ℃ and is kept for 2-48 h.
The porous high-rate ternary material is prepared by adopting sectional type high-temperature solid-phase reaction, and primary particles with small crystal grains and low density in a low-temperature reaction section preferentially react with a high-temperature solid phase of a lithium source due to large specific surface and high activity and diffuse to the surface of large particles to form a cavity; the primary particles with large crystal grains and high density in the high-temperature reaction section are subjected to high-temperature solid-phase reaction with a lithium source to form a skeleton structure of secondary particles.
The porous high-rate nickel-cobalt-manganese-lithium material prepared by the preparation method can be applied to the anode of a lithium ion battery.
The preparation of the local carbon-coated lithium-rich solid solution oxysulfide cathode material of the present invention is further described in detail with reference to the following specific examples.
Example 1
Porous nickel-cobalt-manganese-lithium Li 1.1 Ni 0.5 Co 0.3 Mn 0.2 O 2+γ The preparation method of the material comprises the following steps:
1) Preparing 2mol/L ammonia water solution, placing the ammonia water solution in a precursor reaction kettle, adding deionized water to adjust the pH value to be within the range of 10-13, and forming complexing agent solution I;
2) Preparing a sulfate solution II of Ni, co and Mn with a molar ratio of 5;
3) Preparing 4mol/L NaOH alkaline solution III;
4) Continuously pumping the solution I, the solution II and the alkali solution III into the reaction kettle at a set speed; controlling the pH value of the solution as follows by adjusting the flow rate of NaOH alkali solution III: pH =10 for 30min, pH =13 for 10min; pH =10 for 30min, pH =13 for 10min \8230;, pH and reaction time so alternate. Stirring in the reaction kettle at the rotating speed of 100 revolutions per minute, keeping the temperature of the solution in the reaction at 30 ℃, and stopping adding the solutions I and II and the NaOH alkali solution III after reacting for 10 hours;
5) Carrying out filter pressing and solid-liquid separation on the slurry obtained by the reaction, washing a filter cake for 3 times by using deionized water, drying in an oven at 150 ℃, and sieving to obtain a nickel-cobalt-manganese precursor IV;
6) Weighing lithium carbonate and a nickel-cobalt-manganese precursor IV according to the molar ratio of Li/(Ni + Co + Mn) =1.1, fully and uniformly mixing in a high-speed mixer, and placing in a high-temperature reaction furnace for roasting in an air atmosphere. The roasting standard is set as follows: heating at the speed of 2 ℃/min, keeping the temperature at 800 ℃ for 2h, and keeping the temperature at 950 ℃ for 24h. Cooling, crushing and sieving the reaction product, and demagnetizing to obtain the porous nickel-cobalt-manganese-lithium Li 1.1 Ni 0.5 Co 0.3 Mn 0.2 O 2+γ A material. The SEM picture of the prepared sample is shown in figure 1, and the material is obviously loose and porous and has rich internal pore channel structure.
Example 2
Porous nickel-cobalt-manganese-lithium Li 1.02 Ni 0.6 Co 0.2 Mn 0.2 O 2+γ The preparation method of the material comprises the following steps:
1) Preparing 2mol/L ammonia water solution, placing the ammonia water solution in a precursor reaction kettle, adding deionized water to adjust the pH value to be within the range of 10-13, and forming a complexing agent solution I;
2) Preparing a sulfate solution II of Ni, co and Mn with a molar ratio of 6,
3) Preparing 4mol/L NaOH alkaline solution III;
4) Continuously pumping the solution I, the solution II and the alkali solution III into the reaction kettle at a set speed; controlling the pH value of the solution as follows by adjusting the flow rate of NaOH alkali solution III: pH =11 for 60min, pH =12 for 10min; pH =11 for 60min, pH =12 for 10min \8230, pH and reaction time thus alternate. Stirring in the reaction kettle at a rotating speed of 300 revolutions per minute, keeping the temperature of the solution in the reaction at 60 ℃, and stopping adding the solutions I and II and the NaOH alkali solution III after reacting for 10 hours;
5) Carrying out filter pressing and solid-liquid separation on the slurry obtained by the reaction, washing a filter cake for 3 times by using deionized water, placing the filter cake in an oven at 100 ℃ for drying, and sieving to obtain a nickel-cobalt-manganese precursor IV;
6) Weighing lithium carbonate and a nickel-cobalt-manganese precursor IV according to the molar ratio of Li/(Ni + Co + Mn) =1.02, fully and uniformly mixing in a high-speed mixer, and placing at high temperatureAnd (4) roasting in a reaction furnace in an oxygen atmosphere. The roasting standard is set as follows: heating at the speed of 2 ℃/min, keeping the temperature at 700 ℃ for 8h, and keeping the temperature at 880 ℃ for 2h. Cooling, crushing and sieving the reaction product to obtain the porous nickel-cobalt-manganese-lithium Li 1.02 Ni 0.6 Co 0.2 Mn 0.2 O 2+γ A material.
Example 3
Porous nickel-cobalt-manganese-lithium Li 1.04 Ni 0.8 Co 0.1 Mn 0.1 O 2+γ The preparation method of the material comprises the following steps:
1) Preparing 2mol/L ammonia water solution, placing the ammonia water solution in a precursor reaction kettle, adding deionized water to adjust the pH value to be within the range of 10-13, and forming a complexing agent solution I;
2) Preparing a sulfate solution II of Ni, co and Mn with a molar ratio of 8,
3) Preparing 4mol/L NaOH alkali solution III;
4) Continuously pumping the solution I, the solution II and the alkali solution III into the reaction kettle at a set speed; adjusting the flow rate of NaOH alkali solution III to control the pH of the solution to be 10.5 and 60min continuously, and controlling the pH to be 12 and 15min continuously; pH =10.5 for 60min, pH =12 for 15min \8230; \8230, pH and reaction time so alternate. The stirring speed in the reaction kettle is 300 r/min, and the temperature of the solution in the reaction kettle is kept at 60 ℃. After reacting for 10 hours, stopping adding the solutions I and II and the NaOH alkali solution III;
5) Carrying out filter pressing and solid-liquid separation on the slurry obtained by the reaction, washing a filter cake for 3 times by using deionized water, placing the filter cake in an oven at 100 ℃ for drying, and sieving to obtain a nickel-cobalt-manganese precursor IV;
6) Weighing lithium carbonate according to the molar ratio of Li/(Ni + Co + Mn) =1.02 and sieving to obtain a nickel-cobalt-manganese precursor IV, fully and uniformly mixing in a high-speed mixer, placing in a high-temperature reaction furnace, and roasting in an oxygen atmosphere. The roasting standard is set as follows: raising the temperature at the speed of 2 ℃/min, keeping the temperature at 400 ℃ for 8h, and keeping the temperature at 780 ℃ for 2h. Cooling, crushing and sieving the reaction product to obtain the porous nickel-cobalt-manganese-lithium Li 1.04 Ni 0.8 Co 0.1 Mn 0.1 O 2+γ A material.
Comparative example 1
In contrast to example 1, there was no step of controlling the pH pulse of the solution.
Li 1.1 Ni 0.5 Co 0.3 Mn 0.2 O 2+γ The preparation method of the material comprises the following steps:
1) Preparing 2mol/L ammonia water solution, placing the ammonia water solution in a precursor reaction kettle, adding deionized water to adjust the pH value to 11, and forming a complexing agent solution I;
2) Preparing a sulfate solution II of Ni, co and Mn with a molar ratio of 5;
3) Preparing 4mol/L NaOH alkaline solution III;
4) Continuously pumping the solution I, the solution II and the alkali solution III into the reaction kettle at a set speed; the flow rate of NaOH alkaline solution III was adjusted to control the pH to 10. Stirring in the reaction kettle at the rotating speed of 100 revolutions per minute, keeping the temperature of the solution in the reaction at 30 ℃, and stopping adding the solutions I and II and the NaOH aqueous alkali after reacting for 10 hours;
5) Carrying out filter pressing and solid-liquid separation on the slurry obtained by the reaction, washing a filter cake for 3 times by using deionized water, drying in an oven at 150 ℃, and sieving to obtain a nickel-cobalt-manganese precursor IV;
6) Weighing lithium carbonate and a nickel-cobalt-manganese precursor IV according to the molar ratio of Li/(Ni + Co + Mn) =1.1, fully and uniformly mixing in a high-speed mixer, and placing in a high-temperature reaction furnace for roasting in an air atmosphere. The roasting standard is set as follows: heating at the speed of 2 ℃/min, keeping the temperature at 800 ℃ for 2h, and keeping the temperature at 950 ℃ for 24h. Cooling, crushing, sieving and demagnetizing the reaction product to obtain the conventional Ni-Co-Mn-Li 1.1 Ni 0.5 Co 0.3 Mn 0.2 O 2 A material.
Comparative example 2
The pH range of the control pulse was adjusted compared to example 2.
Li 1.02 Ni 0.6 Co 0.2 Mn 0.2 O 2+γ The preparation method of the material comprises the following steps:
1) Preparing 2mol/L ammonia water solution, placing the ammonia water solution in a precursor reaction kettle, adding deionized water to adjust the pH value to be within the range of 10-13, and forming a complexing agent solution I;
2) Preparing a sulfate solution II of Ni, co and Mn with a molar ratio of 6,
3) Preparing 4mol/L NaOH alkali solution III;
4) Continuously pumping the solution I, the solution II and the alkali solution III into the reaction kettle at a set speed; adjusting the flow rate of the NaOH aqueous solution III to control the pH value of the solution to be: pH =9 for 60min, pH =14 for 15min; pH =9 for 60min, pH =14 for 15min \8230;, pH and reaction time so alternate. The stirring speed in the reaction kettle is 300 r/min, and the temperature of the solution in the reaction kettle is kept at 60 ℃. After reacting for 10 hours, stopping adding the solutions I and II and the NaOH alkali solution III;
5) Carrying out filter pressing and solid-liquid separation on the slurry obtained by the reaction, washing a filter cake for 3 times by using deionized water, placing the filter cake in an oven at 100 ℃ for drying, and sieving to obtain a nickel-cobalt-manganese precursor IV;
6) Weighing lithium carbonate and a nickel-cobalt-manganese precursor IV according to the molar ratio of Li/(Ni + Co + Mn) =1.02, fully and uniformly mixing in a high-speed mixer, placing in a high-temperature reaction furnace, and roasting in an oxygen atmosphere. The roasting standard is set as follows: the temperature is raised at the speed of 2 ℃/min, the temperature is kept at 700 ℃ for 8h, and the temperature is kept at 880 ℃ for 2h. Cooling, crushing, sieving and demagnetizing the reaction product to obtain the Ni-Co-Mn-Li 1.02 Ni 0.6 Co 0.2 Mn 0.2 O 2+γ A material.
Comparative example 3
The maintenance time of the pulsating pH point was varied compared to example 3.
Li 1.04 Ni 0.8 Co 0.1 Mn 0.1 O 2+γ The preparation method of the material comprises the following steps:
1) Preparing 2mol/L ammonia water solution, placing the ammonia water solution in a precursor reaction kettle, adding deionized water to adjust the pH value to be within the range of 10-13, and forming a complexing agent solution I;
2) Preparing a sulfate solution II of Ni, co and Mn with a molar ratio of 8,
3) Preparing 4mol/L NaOH alkali solution III;
4) Continuously pumping the solution I, the solution II and the alkali solution III into the reaction kettle at a set speed, adjusting the flow rate of the NaOH alkali solution III to control the pH of the solution to be 10.5 for 5min and 12 for 5min; pH =10.5 for 5min, pH =12 for 5min \8230; \8230, pH and reaction time are so alternated. The stirring speed in the reaction kettle is 300 r/min, and the temperature of the solution in the reaction kettle is kept at 60 ℃. After reacting for 10 hours, stopping adding the solutions I and II and the NaOH aqueous alkali IV;
5) Carrying out filter pressing and solid-liquid separation on the slurry obtained by the reaction, washing a filter cake for 3 times by using deionized water, placing the filter cake in an oven at 100 ℃ for drying, and sieving to obtain a nickel-cobalt-manganese precursor V;
6) Weighing lithium carbonate and a nickel-cobalt-manganese precursor V according to the molar ratio of Li/(Ni + Co + Mn) =1.04, fully and uniformly mixing in a high-speed mixer, and placing in a high-temperature reaction furnace for roasting in an oxygen atmosphere. The roasting standard is set as follows: the temperature is raised at the speed of 2 ℃/min, the temperature is kept at 700 ℃ for 8h, and the temperature is kept at 880 ℃ for 2h. Cooling, crushing and sieving the reaction product, and removing magnetism to obtain the conventional nickel-cobalt-manganese-lithium Li 1.04 Ni 0.8 Co 0.1 Mn 0.1 O 2+γ A material.
Experimental conditions:
table 1 lists the reversible specific capacity and first coulombic efficiency of 0.1C lithium ion button cells assembled from samples prepared in the above examples and comparative examples. The testing conditions of the button cell are LR 2032,0.1C 3.0-4.25V, vs. Li + and/Li. The charging and discharging equipment is a blue-electricity charging and discharging instrument.
TABLE 1 comparison table of first charge and discharge performance
Figure BDA0002657216660000111
As can be seen from the data in the table, the reversible capacity of the porous high-rate nickel-cobalt-manganese-lithium material prepared in example 1 of the invention has the same content of NiCoMn as that of comparative example 1, but the specific capacity and coulombic efficiency of the sample in example 1 are superior to those of the comparative example.
This is because example 1 increases the step of pH pulsing, the porosity inside the sample particles increases, the lithium ions are more easily extended inside the active material particles, and the material capacity can be fully utilized. In contrast, comparative example 1, which does not have a pH pulse step, is prepared at a constant pH, and has a solid sphere inside, so that the lithium ion diffusion resistance is large, and the capacity of the material cannot be fully exerted, resulting in a decrease in the coulomb charging and discharging efficiency.
Compared with the examples 2 and 3, the pH range and the reaction time of the comparative examples 2 and 3 are changed, so that the product performance is reduced, the final pore size and the pore distribution condition are determined by the pH pulse condition, and the insufficient reaction and the overlarge porous structure pore are possibly caused by the over-small pH or the over-short pH time; and if the pH value is too high or the pH value is too long, the sample becomes a close-packed ball, the pore structure disappears, and the distribution of the pore size and the porosity has direct influence on the exertion of the electrochemical performance of the product.
Table 2 lists the rate performance of lithium ion button cells assembled from samples made in the above examples. The testing condition of the battery is LR 2032, 3.0-4.25V vs + [ Li ]: charging and discharging for one cycle at 0.1C/0.1C; charging and discharging for one cycle at 0.1C/1C; and charging and discharging for one cycle at 0.1C/5C. The charging and discharging device used is a blue charging and discharging instrument.
Table 2 comparison table of large multiplying power charging and discharging performance
Figure BDA0002657216660000121
As can be seen from the data in the table, the porous high-rate nickel-cobalt-manganese-lithium prepared in the embodiment of the invention has very obvious advantages in rate performance compared with the comparative example. The porosity of the sample is increased in the embodiment, so that lithium ions can be easily expanded into active substance particles, the lithium ions immersed into the electrolyte in the pores can contact more reaction sites, the reaction rate of the material under a high current multiplying power is improved, and the multiplying power performance is obviously improved.
Table 3 lists the capacity retention of 50 weeks of reversible capacity of lithium ion button cells assembled from samples prepared in the above examples. The test conditions of the battery are LR 2032, 45 ℃,1C 3.0-4.25V, vs. Li + and/Li. The charging and discharging device used is a blue charging and discharging instrument.
TABLE 3 comparison of cycle performance
Figure BDA0002657216660000122
Figure BDA0002657216660000131
The data in the table show that the porous high-rate nickel-cobalt-manganese-lithium material prepared by the invention has good capacity retention rate, and the performance of the embodiment is obviously superior to that of the comparative example. Therefore, the porous structure prepared by the pH pulse effectively plays a role in inhibiting the cyclic degradation of the material.
In summary, the disclosure of the present invention is not limited to the above-mentioned embodiments, and persons skilled in the art can easily set forth other embodiments within the technical teaching of the present invention, but such embodiments are included in the scope of the present invention.

Claims (6)

1. The preparation method of the porous high-rate ternary material is characterized by comprising the following steps of:
1) Preparing an ammonia water solution, placing the ammonia water solution in a precursor reaction kettle, adding deionized water to adjust the pH value to be within the range of 10-13, and forming a complexing agent solution I;
2) Preparing a soluble salt solution II containing Ni, co and Mn elements according to a designed molar ratio;
3) Preparing an alkali solution III with a certain molar concentration;
4) Continuously pumping a complexing agent solution I, a soluble salt solution II and an alkali solution III into a reaction kettle respectively, and regulating the pH of the solution to be in a pulse change range of 10-13 by controlling the flow rate of the alkali solution III; the stirring speed in the reaction kettle is 100-500 r/min, the temperature of the solution in the reaction kettle is kept at 30-80 ℃, and the reaction time is not less than 10h;
the pulse change of the pH value of the solution between 10 and 13 means that the pH value of the solution is alternately changed between 10 and 13 and is maintained for a certain reaction time at the pH value;
5) After the reaction is finished, carrying out solid-liquid separation on the slurry, washing the solid by using deionized water, drying the solid at the temperature of 100-150 ℃, and sieving to obtain a precursor IV;
6) Weighing a precursor IV, a lithium salt and an additive according to a design ratio, fully and uniformly mixing, placing in an oxygen-containing atmosphere for high-temperature solid-phase reaction, crushing a product, sieving, and demagnetizing to obtain a porous high-rate ternary material;
the conditions of pulse change of the pH value of the solution in the step 4) between 10 and 13 are as follows: pulse low-point pH = 10-11, and the duration is 30 min-60 min; the pulse high point pH = 12-13, the duration is 10 min-30 min,
the high-temperature solid-phase reaction in the step 6) is a sectional type high-temperature solid-phase reaction, the sectional type high-temperature solid-phase reaction is divided into 2 temperature platforms, the temperature platform 1 is set to be 400-800 ℃, and the temperature is kept for 2-8 h; the temperature platform 2 is set to be 780-980 ℃ and is kept for 2-48 h.
2. The method for preparing the porous high-rate ternary material according to claim 1, wherein the porous high-rate ternary material comprises the following steps: the soluble salt solution II in the step 2) is more than or equal to 0.5 of Ni/(Ni + Co + Mn) in molar ratio.
3. The method for preparing the porous high-rate ternary material according to claim 1, wherein the porous high-rate ternary material comprises the following steps: the alkali solution III in the step 3) is one or two of sodium hydroxide and potassium hydroxide, and the concentration is 2-5 mol/L.
4. The method for preparing the porous high-rate ternary material according to claim 1, wherein the method comprises the following steps: the design proportion in the step 6) is that, in terms of molar ratio, li/(Ni + Co + Mn) = 0.99-1.1, and additive/(Ni + Co + Mn) = 0.001-0.1.
5. The method for preparing the porous high-rate ternary material according to claim 1, wherein the method comprises the following steps: in the step 6), the additive contains one or more elements of Ti, mg, al, zr, V, mo, nb, W, Y and Sr.
6. The porous high-rate ternary material prepared by the preparation method according to any one of claims 1 to 5 is applied to a lithium ion battery.
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