CN115172721A - Hollow high-conductivity lithium cathode material and preparation method thereof - Google Patents

Hollow high-conductivity lithium cathode material and preparation method thereof Download PDF

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CN115172721A
CN115172721A CN202210922914.8A CN202210922914A CN115172721A CN 115172721 A CN115172721 A CN 115172721A CN 202210922914 A CN202210922914 A CN 202210922914A CN 115172721 A CN115172721 A CN 115172721A
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precursor
cathode material
hollow
conductivity lithium
hollow high
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伏萍萍
宋英杰
吕菲
徐宁
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Tianjin B&M Science and Technology Co Ltd
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Abstract

The invention provides a hollow high-conductivity lithium anode material and a preparation method thereof, the hollow high-conductivity lithium anode material has more lithium ion diffusion channels, a lithium diffusion path is shortened, the high-rate charge and discharge performance of the material is greatly improved, and an assembled power battery has better power performance; meanwhile, the hollow high-conductivity lithium cathode material adopts a sphere-like shell formed by agglomerating primary nano particles, so that the hollow high-conductivity lithium cathode material has a space for volume expansion, and the toughness of the particles is improved, so that the power battery has longer cycle life; according to the invention, a precursor with a core-shell structure is developed by controlling the crystal growth process of precursor coprecipitation, and a multi-step high-temperature solid-phase reaction is combined, so that an internal loose precursor crystal nucleus is diffused to a compact outer wall of a same crystal phase in the process of generating the anode material to form an internal hollow structure; the compact outer layer of the precursor forms nano primary particles after high-temperature reaction and is assembled into a shell structure.

Description

Hollow high-conductivity lithium cathode material and preparation method thereof
Technical Field
The invention relates to the field of lithium ion secondary battery anode materials, in particular to a hollow high-conductivity lithium anode material and a preparation method thereof.
Background
With the continuous popularization and application of new energy vehicles, lithium ion batteries have become the most mainstream power batteries applied to new energy vehicles. The high-rate charge and 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 lithium ion battery anode materials commercialized in the current market are solid primary particles or secondary agglomerated particles, the lithium ion conduction path is long, and the efficiency of lithium intercalation and deintercalation of active substances under the high-current charge and discharge density is greatly reduced, so that 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 rapidly shortened.
Therefore, it is necessary to provide a new cathode material and a method for preparing the same to solve the above technical problems.
Disclosure of Invention
Aiming at the technical problems brought forward by the background technology, the invention provides a hollow high-conductivity lithium cathode material with excellent rate capability or cycle performance and a preparation method thereof, and on one hand, the hollow high-conductivity lithium cathode material has sufficient lithium conductivity channels, so that the rate capability of the material can be improved; and the toughness of the particles is improved on the other side, and the reversibility of volume change of the material in the charge and discharge processes is maintained, so that the power battery has longer cycle life.
In order to solve the technical problems, the technical scheme adopted by the invention is as follows:
a hollow high-conductivity lithium cathode material is provided with a hollow interior and a sphere-like shell, wherein the sphere-like shell is formed by agglomeration of primary nano particles.
Further, the sphere-like shell is formed by agglomerating 1-2 layers of nano primary particles.
Further, the D50 of the hollow high-conductivity lithium cathode material is 2 to 15 micrometers.
Further, the thickness of the spherical shell is 0.1 to 2 μm.
Further, the size of the nanometer primary particles is 10 to 900nm.
Furthermore, the aperture size of the hollow interior is 0.5 to 13 μm.
Further, the specific surface area BET of the hollow high-conductivity lithium cathode material is 0.6 to 2m 2 /g。
Furthermore, the chemical formula of the hollow high-conductivity lithium cathode material is LiNi x Co y M (1-x-y) O 2 Wherein x =0 to 1,y =0 to 1,M is selected from Mn or Al or the combination thereof.
In order to solve the technical problems, the invention also adopts the technical scheme that:
the preparation method of the hollow high-conductivity lithium cathode material comprises the following steps:
1) Preparation of precursor Crystal nucleus
Carrying out coprecipitation reaction on an alkali solution, a salt solution and a complexing agent solution to obtain a precursor crystal nucleus;
2) Preparation of core-shell precursor
Adjusting the condition of coprecipitation reaction, and continuing the coprecipitation reaction on the precursor crystal nucleus obtained in the step 1) to continue growing a precursor shell layer on the surface of the precursor to obtain a precursor with a core-shell structure, wherein the density of the precursor shell layer is greater than that of the precursor crystal seed;
3) Preparation of hollow high-conductivity lithium cathode material
And mixing the precursor with the core-shell structure with lithium salt, and then carrying out high-temperature solid phase reaction to obtain the hollow high-conductivity lithium cathode material.
Further, in the step 1), the salt solution is a soluble salt solution of Ni, a soluble salt solution of Co, and a soluble salt solution of M; the alkali solution is NaOH solution; the complexing agent is ammonia water solution;
further, in the step 1), a magnetic field perpendicular to the eddy current direction of the liquid is applied during the coprecipitation reaction, and the strength of the magnetic field is 5000 to 20000 gauss.
Further, in the step 1), the pH value of the coprecipitation reaction is controlled to be 12 to 13, and the D50 of the precursor crystal nucleus is less than or equal to 5 mu m.
Further, in the step 2), adjusting the condition of the coprecipitation reaction includes adjusting the pH value of the reaction to 10 to 11.
Further, in the step 3), the high-temperature solid-phase reaction comprises a low-temperature step and a high-temperature step which are sequentially carried out, wherein the temperature of the low-temperature step is 400-800 ℃, the heat preservation time is 4-48h, the temperature of the high-temperature step is 700-1050 ℃, and the heat preservation time is 4-48h.
Compared with the prior art, the invention has the beneficial effects that:
(1) The hollow high-conductivity lithium anode material has more lithium ion diffusion channels, the lithium diffusion path is shortened, the high-rate charge and discharge performance of the material is greatly improved, and the assembled power battery has better power performance; meanwhile, the hollow high-conductivity lithium cathode material adopts a sphere-like shell formed by agglomerating primary nano particles, so that the hollow high-conductivity lithium cathode material has a space for volume expansion, and the toughness of the particles is improved, so that the power battery has a longer cycle life.
(2) According to the invention, a precursor with a core-shell structure is developed by controlling the crystal growth process of precursor coprecipitation, and the precursor crystal nucleus with loose interior is diffused to the compact outer wall of the same crystal phase in the process of generating the anode material by combining step-by-step high-temperature solid-phase reaction to form an internal hollow structure; the compact outer layer of the precursor forms nano primary particles after high-temperature reaction and is assembled into a shell structure.
Drawings
Fig. 1 is an SEM image of a hollow high-conductivity lithium cathode material according to example 1 of the present invention;
FIG. 2 is a CP-SEM image of the cross section of the hollow high-conductivity lithium cathode material in example 1 of the present invention;
FIG. 3 is a cross-sectional hard profile-SEM image of a hollow high-conductivity lithium cathode material in example 1 of the present invention;
FIG. 4 is a SEM image of a cross-section of a core-shell precursor in example 1 of the present invention.
Detailed Description
All the raw materials involved in the present invention are not particularly limited in their sources, and may be either commercially available or prepared according to conventional preparation methods well known to those skilled in the art.
The invention provides a hollow high-conductivity lithium cathode material which is provided with a hollow interior and a sphere-like shell, wherein the sphere-like shell is formed by agglomeration of nano primary particles. That is, the hollow high-conductivity lithium cathode material is hollow sphere-like particles, i.e., nano primary particles are agglomerated to form a sphere-like shell, and the sphere-like shell has a hollow interior therein, and the specific structure can be referred to fig. 2 and fig. 3.
The hollow high-conductivity lithium anode material has more lithium ion diffusion channels, the lithium diffusion path is shortened, the high-rate charge and discharge performance of the material is greatly improved, and the assembled power battery has better power performance; meanwhile, the hollow high-conductivity lithium cathode material adopts a sphere-like shell formed by agglomeration of primary nano particles, so that the hollow high-conductivity lithium cathode material has a space for volume expansion, and the toughness of the particles is improved, so that the power battery has a longer cycle life.
In the invention, the sphere-like shell is formed by agglomerating 1-2 layers of nano primary particles, so that the particles have certain skeleton strength, a buffer space is provided for volume change of materials in the charging and discharging processes, and a good lithium guide channel is provided, so that Li in the electrolyte + Has a faster solid-liquid interface diffusion speed.
In the invention, the D50 of the hollow high-conductivity lithium cathode material is 2 to 15 μm, and can be 2 μm, 5 μm, 8 μm, 10 μm, 12 μm, 15 μm and the like, and other values in the above numerical range can be selected, and are not described in detail herein.
In the present invention, the thickness of the spheroidal shell is 0.1 to 2 μm. When the thickness exceeds 2 μm, the solid-phase diffusion path of lithium ions increases, the number of grain boundaries increases, and the rate capability of the material decreases.
In the present invention, the size of the nano primary particle is 10 to 900nm. When the size of the nanometer primary particles is less than 10nm, the activity of the material is too high; if the thickness exceeds 900nm, solid-phase diffusion of lithium ions is deteriorated, and the rate capability of the material is lowered.
In the present invention, the aperture size of the hollow interior is 0.5 to 13 μm, which may be 0.5 μm, 2.5 μm, 5 μm, 7 μm, 10 μm, 13 μm, and the like, and other values within the above numerical range may be selected, which is not described herein again.
In the invention, the specific surface area BET of the hollow high-conductivity lithium cathode material is 0.6 to 2m 2 (ii) in terms of/g. The positive electrode material with the specific surface area range can give consideration to both electrochemistry and pole piece processing performances.
In the invention, the chemical formula of the hollow high-conductivity lithium cathode material is LiNi x Co y M (1-x-y) O 2 Wherein M is selected from Mn or Al or a combination thereof, and x =0 to 1, y =0 to 1. In the chemical formula, one or more elements of Al, na, K, rb, cs, sc, nb, bi, fe, mo, ti, mg, zn, V, zr and Ru can be doped to improve the chemical property of the material.
The invention also provides a preparation method of the hollow high-conductivity lithium cathode material, which comprises the following steps:
1) Preparation of precursor Crystal nucleus
Carrying out coprecipitation reaction on an alkali solution, a salt solution and a complexing agent solution to obtain a precursor crystal nucleus;
2) Preparation of core-shell precursor
Adjusting the condition of coprecipitation reaction, and continuing the coprecipitation reaction on the precursor crystal nucleus obtained in the step 1) to continue growing a precursor shell layer on the surface of the precursor to obtain a precursor with a core-shell structure, wherein the density of the precursor shell layer is greater than that of the precursor crystal seed;
3) Preparation of hollow high-conductivity lithium cathode material
And mixing the precursor with the core-shell structure with lithium salt, and then carrying out high-temperature solid phase reaction to obtain the hollow high-conductivity lithium cathode material.
According to the invention, a precursor with a core-shell structure is developed by controlling the crystal growth process of precursor coprecipitation, and a high-temperature solid-phase reaction is combined, so that precursor crystal nuclei with loose interiors diffuse towards the compact outer wall of the same crystal phase in the process of generating the anode material, and an internal hollow structure is formed; the compact outer layer of the precursor forms nano primary particles after high-temperature reaction and is assembled into a shell structure.
In the invention, the salt solution in the step 1) is a Ni soluble salt solution, a Co soluble salt solution and an M soluble salt solution. For example, a nickel sulfate solution, a cobalt sulfate solution, a sulfuric acid M solution (an aluminum sulfate solution when M is selected from Al; a manganese sulfate solution when M is Mn; a mixed solution of aluminum sulfate and manganese sulfate when M is selected from Al and Mn); the metal material may be a nickel nitrate solution, a cobalt nitrate solution, or a nitric acid M solution (aluminum nitrate solution when M is selected from Al, manganese nitrate solution when M is Mn, or a mixed solution of aluminum nitrate and manganese nitrate when M is selected from Al and Mn).
In the present invention, in step 1), the alkali solution is preferably a NaOH solution; the complexing agent is preferably an aqueous ammonia solution.
In the present invention, a magnetic field perpendicular to the eddy current direction of the liquid is applied during the coprecipitation reaction, and the strength of the magnetic field is 5000 to 20000 gausses, which may be
5000 gauss, 8000 gauss, 10000 gauss, 15000 gauss, 20000 gauss, etc., and other point values in the above numerical range can be selected, and are not described in detail herein.
In the invention, the pH value of the coprecipitation reaction in the step 1) is controlled to be 12-13, and the precursor crystal nucleus D50 is less than or equal to 5 mu m.
In the invention, the condition for adjusting the coprecipitation reaction in the step 2) comprises adjusting the pH value of the reaction to be 10 to 11.
In the invention, the high-temperature solid-phase reaction in the step 3) comprises a low-temperature step and a high-temperature step which are sequentially carried out, wherein the temperature of the low-temperature step is 400-800 ℃, the heat preservation time is 4-48h, the temperature of the high-temperature step is 700-1050 ℃, and the heat preservation time is 4-48h.
The temperature of the low-temperature step can be 400 ℃, 500 ℃, 600 ℃,700 ℃,800 ℃ and the like, and the heat preservation time can be 4h, 8h, 12h, 16h, 20h, 26h, 30h, 34h, 40h, 48h and the like.
The temperature of the high temperature step can be 700 ℃,800 ℃, 900 ℃, 1000 ℃, 1050 ℃ and the like, and the heat preservation time can be 4h, 8h, 12h, 16h, 20h, 26h, 30h, 34h, 40h, 48h and the like.
Other values within the above range can be selected, and are not further described herein.
The technical solutions of the present invention will be described clearly and completely below with reference to embodiments of the present invention, and it should be apparent that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
To further illustrate the present invention, the following examples are provided for illustration. The starting materials used in the following examples of the present invention, the sources of which are not particularly limited, may be commercially available or prepared according to conventional methods well known to those skilled in the art.
Example 1
This example provides a hollow high-conductivity lithium cathode material LiNi 0.5 Co 0.3 Mn 0.2 O 2 The preparation method comprises the following steps:
1) Preparation of precursor Crystal nucleus
Preparing 1mol/L NaOH solution and 2mol/L ammonia water solution; preparing NiSO (nickel, cobalt and manganese) with a molar ratio of 5 4 Solution, coSO 4 Solution, mnSO 4 Solution, mixing NaOH solution and NiSO 4 Solution, coSO 4 Solution, mnSO 4 Putting the solution and an ammonia water solution into a reaction kettle for coprecipitation reaction, applying a magnetic field perpendicular to the eddy current direction of the liquid during the reaction, wherein the strength of the magnetic field is 7000 gausses, and the pH value of the reaction is controlled to be 12-13, so as to obtain a precursor crystal nucleus with D50=1.5 μm;
2) Preparation of precursor Shell
Adding deionized water, adjusting the pH value of the reaction to be 10-11, and continuously performing coprecipitation reaction on the precursor crystal nucleus obtained in the step 1) for 12 hours to obtain a precursor shell layer with compact growth;
3) Preparation of core-shell precursor
Carrying out solid-liquid separation on the slurry after the reaction in the step 2), washing with deionized water for 3 times, drying in an oven at 150 ℃, and sieving
Then obtaining a precursor with a core-shell structure;
4) Preparation of hollow high-conductivity lithium cathode material
According to Li/(Ni + Co + M)n) =1.04, weighing lithium carbonate and the precursor in a molar ratio of 1, fully and uniformly mixing in a high-speed mixer, placing in a high-temperature reaction furnace, roasting in an air atmosphere, and setting a roasting mode as follows: heating at the speed of 2 ℃/min, keeping the temperature at 800 ℃ for 4h, and keeping the temperature at 950 ℃ for 24h; cooling, crushing, sieving and demagnetizing the reaction product to obtain the hollow high-conductivity lithium anode material LiNi 0.5 Co 0.3 Mn 0.2 O 2 。
Example 2
This example provides a hollow high-conductivity lithium positive electrode material LiNi 0.6 Co 0.2 Mn 0.2 O 2 The preparation method comprises the following steps:
1) Preparation of precursor Crystal nucleus
Preparing 1mol/L NaOH solution and 2mol/L ammonia water solution; preparing NiSO (nickel, cobalt and manganese) with a molar ratio of 6 4 Solution, coSO 4 Solution, mnSO 4 Solution, mixing NaOH solution and NiSO 4 Solution, coSO 4 Solution, mnSO 4 Putting the solution and an ammonia water solution into a reaction kettle for coprecipitation reaction, applying a magnetic field perpendicular to the eddy current direction of the liquid during the reaction, wherein the strength of the magnetic field is 5000 gauss, and the pH value of the reaction is controlled to be 12-13 to obtain a precursor crystal nucleus with D50=3 mu m;
2) Preparation of precursor Shell
Adding deionized water, adjusting the pH value of the reaction to be 10-11, and continuously performing coprecipitation reaction on the precursor crystal nucleus obtained in the step 1) for 8 hours to obtain a precursor shell layer with compact growth;
3) Preparation of core-shell precursor
Carrying out solid-liquid separation on the slurry after the reaction in the step 2), washing with deionized water for 3 times, drying in a 120 ℃ oven, and sieving
Then obtaining a precursor with a core-shell structure;
4) Preparation of hollow high-conductivity lithium cathode material
Weighing lithium hydroxide and the precursor 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, roasting in an oxygen atmosphere, and setting the roasting formula as follows: heating at a speed of 2 deg.C/min and maintaining at 700 deg.CHeating for 8h, keeping the temperature at 880 ℃ for 10h, cooling, crushing, sieving and demagnetizing the reaction product to obtain the hollow high-conductivity lithium anode material LiNi 0.6 Co 0.2 Mn 0.2 O 2 。
Example 3
This example provides a hollow high-conductivity lithium cathode material LiNi 0.8 Co 0.1 Mn 0.1 O 2 The preparation method comprises the following steps:
1) Preparation of precursor Crystal nucleus
Preparing 1mol/L NaOH solution and 2mol/L ammonia water solution; preparing NiSO with a molar ratio of 8 4 Solution, coSO 4 Solution, mnSO 4 Solution, mixing NaOH solution and NiSO 4 Solution, coSO 4 Solution, mnSO 4 Putting the solution and an ammonia water solution into a reaction kettle for coprecipitation reaction, applying a magnetic field perpendicular to the eddy current direction of the liquid during the reaction, wherein the strength of the magnetic field is 8000 Gauss, and the pH value of the reaction is controlled to be 12 to 13, so as to obtain a precursor crystal nucleus with D50=0.5 mu m;
2) Preparation of precursor Shell
Adding deionized water, adjusting the pH value of the reaction to be 10-11, and continuously performing coprecipitation reaction on the precursor crystal nucleus obtained in the step 1) for 15 hours to obtain a precursor shell layer with compact growth;
3) Preparation of core-shell precursor
Carrying out solid-liquid separation on the slurry after the reaction in the step 2), washing with deionized water for 3 times, drying in a drying oven at 100 ℃, and sieving
Then obtaining a precursor with a core-shell structure;
4) Preparation of hollow high-conductivity lithium cathode material
Weighing lithium carbonate and the precursor 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, roasting in an oxygen atmosphere, and setting the roasting mode as follows: heating at the speed of 2 ℃/min, preserving heat at 400 ℃ for 10h, preserving heat at 700 ℃ for 4h, cooling, crushing, sieving and demagnetizing a reaction product to obtain the hollow high-conductivity lithium anode material LiNi 0.8 Co 0.1 Mn 0.1 O 2 。
Comparative example 1
This comparative example provides a positive electrode material LiNi 0.5 Co 0.3 Mn 0.2 O 2 The preparation method is different from that of example 1 in that a magnetic field perpendicular to the direction of the liquid vortex is not applied during the reaction in step 1).
Comparative example 2
This comparative example provides a positive electrode material LiNi 0.6 Co 0.2 Mn 0.2 O 2 The preparation method differs from that of example 2 only in that step 1) extends the reaction time to obtain precursor nuclei having a D50=15 μm.
Comparative example 3
This comparative example provides a positive electrode material LiNi 0.8 Co 0.1 Mn 0.1 O 2 The preparation method is different from that of example 3 only in that the baking standard of step 4) is set as follows: the temperature is raised at the speed of 2 ℃/min and kept at 700 ℃ for 14h.
SEM tests were performed on the hollow high-conductivity lithium cathode material prepared in example 1, and fig. 2 is a cross-sectional CP-SEM image of the hollow high-conductivity lithium cathode material in example 1 according to the present invention; FIG. 3 is a hard cross-sectional SEM image of a hollow high-conductivity lithium cathode material in example 1 of the present invention (a cross-sectional view of the cathode material after freezing with liquid nitrogen); as can be seen from fig. 2 and 3, the hollow high-conductivity lithium cathode material synthesized in example 1 of the present invention has a hollow interior and a spheroidal shell, and the spheroidal shell is formed by agglomeration of primary nanoparticles. The sphere-like shell is formed by agglomerating 1-2 layers of nano primary particles.
Experimental conditions:
table 1 shows the reversible specific capacity and the first coulombic efficiency of the lithium ion button cell assembled by the positive electrode materials prepared in the examples 1 to 3 and the comparative examples 1 to 3 under the condition of 0.1C. The test conditions of the button cell are LR 2032,0.1C 3.0 to 4.25V, vs. Li + and/Li. The charging and discharging device used is a blue charging and discharging instrument.
TABLE 1
Figure DEST_PATH_IMAGE002A
As can be seen from the data in the table, the reversible specific capacity and the first coulombic efficiency of the hollow high-conductivity lithium cathode materials prepared in the embodiments 1 to 3 of the invention are respectively superior to those of the cathode materials prepared in the comparative examples 1 to 3. This is because the hollow high-conductivity lithium cathode material prepared by applying a magnetic field perpendicular to the direction of the liquid vortex in combination with the step-by-step high-temperature solid-phase reaction in example 1 has better crystallinity. Compared with the comparative example 2, the internal crystal nucleus prepared in the example 2 is more suitable for pore forming, and the porosity of the cathode material prepared after high-temperature solid-phase reaction is higher. In example 3, compared with comparative example 3, the fractional calcination is adopted, so that the crystallinity of the hollow high-conductivity lithium cathode material can be improved, the crystallinity is improved, the porosity of the material is increased, and the reversible capacity of the material can be fully exerted.
The rate capability of the lithium-ion button cell assembled by the positive electrode materials prepared in the above examples 1 to 3 and comparative examples 1 to 3 is shown in Table 2. The testing conditions of the battery are LR 2032,3.0 to 4.25V vs. Li + [ Li ]: charging and discharging for one cycle at 0.1C/0.1C; charging and discharging for one cycle at 0.1C/1C; and (4) charging and discharging for one cycle at 0.1C/5C, wherein the used charging and discharging equipment is a blue charging and discharging instrument.
TABLE 2
Figure DEST_PATH_IMAGE004
As can be seen from the data in Table 2, the rate performance of the hollow high-conductivity lithium cathode materials prepared in examples 1 to 3 is respectively obviously superior to that of comparative examples 1 to 3. The hollow high-conductivity lithium cathode material prepared by applying a magnetic field perpendicular to the direction of the liquid eddy current and combining step-by-step high-temperature solid-phase reaction in the embodiment 1 has better crystallinity, reduces cation mixing and discharging, improves the long-range order of a diffusion channel of lithium ions, makes the lithium ions more easily extend into active substance particles, and improves the material reaction rate under high current multiplying power because the lithium ions immersed into the electrolyte in the pores can contact more reaction sites. The size of the internal crystal nucleus prepared in the embodiment 2 is more suitable for pore forming than that of the internal crystal nucleus prepared in the comparative example 2, the porosity of the anode material prepared after high-temperature solid-phase reaction is higher, lithium ions can be more easily expanded into active substance particles, the lithium ions immersed into the electrolyte in the pores can contact more reaction points, and the reaction rate of the material under the high-current multiplying power is improved. In example 3, compared with comparative example 3, the step-by-step roasting method can improve the crystallinity of the hollow high-conductivity lithium cathode material, reduce the mixed discharge of cations and improve the long-range order degree of a diffusion channel of lithium ions.
Table 3 shows the capacity retention rate of 50 weeks of reversible capacity of the lithium-ion button cell assembled by the positive electrode materials prepared in the above examples 1 to 3 and comparative examples 1 to 3. The test conditions of the battery are LR 2032, 45 ℃, 1C,3.0 to 4.25V, vs. Li + and/Li. The charging and discharging equipment is a blue-ray charging and discharging instrument.
TABLE 3
Figure DEST_PATH_IMAGE006
As can be seen from the data in Table 3, the high-conductivity lithium positive electrode materials prepared in examples 1 to 3 have good capacity retention rates as compared with comparative examples 1 to 3, respectively. Therefore, the structure design of the sphere-like shell formed by agglomerating the hollow inner part and the primary nano particles plays a role in inhibiting the material from circularly degrading; the improvement of the crystallinity of the material is beneficial to improving the reversibility of lithium ion extraction/insertion in the charge and discharge processes of the material, and the loss of active substances in the circulating process is reduced, thereby improving the circulating performance of the material. The hollow high-conductivity lithium cathode material adopts a sphere-like shell formed by agglomerating primary nano particles, has a space for volume expansion, and improves the toughness of the particles, so that the power battery has longer cycle life. The reason why the capacity retention ratio of example 2 and example 3 is lower than that of comparative example 1 is that the cycle performance is lower as the Ni content is higher, unlike the material system.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (10)

1. The hollow high-conductivity lithium cathode material is characterized by comprising a hollow interior and a sphere-like shell, wherein the sphere-like shell is formed by agglomerating primary nano particles.
2. The hollow high-conductivity lithium cathode material as claimed in claim 1, wherein the spheroidal shell is formed by agglomeration of 1 to 2 layers of primary nanoparticles.
3. The hollow high-conductivity lithium cathode material according to claim 1, wherein at least one of the following conditions is satisfied:
the D50 of the hollow high-conductivity lithium cathode material is 2-15 mu m;
the thickness of the spherical shell is 0.1 to 2 mu m;
the size of the nano primary particles is 10 to 900nm;
the aperture size of the hollow interior is 0.5 to 13 mu m;
the specific surface area BET of the hollow high-conductivity lithium cathode material is 0.6 to 2m 2 /g。
4. The hollow high-conductivity lithium positive electrode material according to claim 1, wherein the chemical formula is LiNi x Co y M (1-x-y) O 2 Wherein x =0 to 1,y =0 to 1,M is selected from Mn or Al or the combination thereof.
5. The preparation method of the hollow high-conductivity lithium cathode material as claimed in any one of claims 1 to 4, characterized by comprising the following steps:
1) Preparation of precursor Crystal nucleus
Carrying out coprecipitation reaction on an alkali solution, a salt solution and a complexing agent solution to obtain a precursor crystal nucleus;
2) Preparation of core-shell precursor
Adjusting the condition of coprecipitation reaction, and continuing the coprecipitation reaction on the precursor crystal nucleus obtained in the step 1) to continue growing a precursor shell layer on the surface of the precursor to obtain a precursor with a core-shell structure, wherein the density of the precursor shell layer is greater than that of the precursor crystal seed;
3) Preparation of hollow high-conductivity lithium cathode material
And mixing the precursor with the core-shell structure with lithium salt, and then carrying out high-temperature solid phase reaction to obtain the hollow high-conductivity lithium cathode material.
6. The method for preparing the hollow high-conductivity lithium cathode material according to claim 5, wherein in the step 1), the salt solution is a soluble salt solution of Ni, a soluble salt solution of Co, or a soluble salt solution of M; the alkali solution is NaOH solution; the complexing agent is ammonia water solution.
7. The method for preparing the hollow high-conductivity lithium cathode material according to claim 5, wherein in the step 1), a magnetic field perpendicular to the direction of the liquid eddy current is applied during the coprecipitation reaction, and the strength of the magnetic field is 5000 to 20000 gauss.
8. The preparation method of the hollow high-conductivity lithium cathode material as claimed in claim 5, wherein in the step 1), the pH value of the coprecipitation reaction is controlled to be 12 to 13, and the D50 of the precursor crystal nucleus is less than or equal to 5 μm.
9. The preparation method of the hollow high-conductivity lithium cathode material as claimed in claim 5, wherein in the step 2), the adjusting of the conditions of the coprecipitation reaction comprises adjusting the pH value of the reaction to 10 to 11.
10. The method for preparing the hollow high-conductivity lithium cathode material according to claim 5, wherein in the step 3), the high-temperature solid-phase reaction comprises a low-temperature step and a high-temperature step which are sequentially performed, the temperature of the low-temperature step is 400 to 800 ℃, the heat preservation time is 4 to 48h, the temperature of the high-temperature step is 700 to 1050 ℃, and the heat preservation time is 4 to 48h.
CN202210922914.8A 2022-08-02 2022-08-02 Hollow high-conductivity lithium cathode material and preparation method thereof Pending CN115172721A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115490277A (en) * 2022-09-30 2022-12-20 山东精工电子科技股份有限公司 Magnetic field modified ternary material for lithium ion battery and preparation method thereof

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115490277A (en) * 2022-09-30 2022-12-20 山东精工电子科技股份有限公司 Magnetic field modified ternary material for lithium ion battery and preparation method thereof
CN115490277B (en) * 2022-09-30 2024-02-13 山东精工电子科技股份有限公司 Magnetic field modified ternary material for lithium ion battery and preparation method thereof

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