CN117457868A - Tantalum doped titanium dioxide and Li 2 SnO 3 Double-layer coated modified ternary positive electrode material, and preparation method and application thereof - Google Patents

Tantalum doped titanium dioxide and Li 2 SnO 3 Double-layer coated modified ternary positive electrode material, and preparation method and application thereof Download PDF

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CN117457868A
CN117457868A CN202311415520.4A CN202311415520A CN117457868A CN 117457868 A CN117457868 A CN 117457868A CN 202311415520 A CN202311415520 A CN 202311415520A CN 117457868 A CN117457868 A CN 117457868A
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tantalum
coating
lithium
double
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李猷
李明哲
胡彬
杨允杰
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Huading Guolian Battery Material Co ltd
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Huading Guolian Battery Material Co ltd
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Abstract

Tantalum doped titanium dioxide and Li 2 SnO 3 A double-layer coating modified ternary positive electrode material, a preparation method and application thereof belong to the technical field of lithium ion batteries, and the general formula of the material is as follows: li (Li) 2 SnO 3 @Ta‑TiO 2‑x @LiNi x Co y Mn z Al a Zr b Ta c Sr d O 2 X+y+z+a+b+c+d=1. The preparation method comprises the following steps: mixing the precursor, the lithium source and the additive uniformly, performing primary sintering, performing wet coating after water washing and dispersing, and performing secondary sintering coating, dry coating and three times of sintering coating. According to the invention, the ternary material is modified, the multielement bulk phase doping is introduced to stabilize the crystal structure, and the coating effect can be realized at the nano level while washing to reduce residual alkali; the invention improves the electrolyte corrosion resistance and lithium ion diffusion coefficient of the crystal material, and has the advantages of high electronic conductivity, high ion mobility, low attenuation rate in long-cycle test and the like.

Description

Tantalum doped titanium dioxide and Li 2 SnO 3 Double-layer coated modified ternary positive electrode material, and preparation method and application thereof
Technical Field
The invention belongs to the technical field of lithium ion batteries, and particularly relates to tantalum doped titanium dioxide and Li 2 SnO 3 Double-layer coating modified ternary positive electrode material, and preparation method and application thereof.
Background
Along with the rapid development of the power battery and the continuous improvement of the requirement of energy density, the requirements on the positive electrode material end are also raised, the nickel cobalt lithium manganate ternary positive electrode material is distinguished by high specific energy and high specific power, and ternary materials NCM111, NCM523, NCM811 and the like with different proportions are widely studied. At present, the main development direction of the ternary material is the development trend of high nickel and low cobalt, single crystallization and high voltage, however, the ternary material with high nickel and low cobalt has Ni under the condition of high cut-off voltage 4+ The chemical structure is unstable under the deep charge and discharge condition, and the layered structure is converted into a spinel structure; the ternary material with high nickel and low cobalt also has the problems of mixed discharge of lithium and nickel, unstable TM (transition metal) -O bond, release of lattice oxygen in the charge and discharge process, and the like.
At present, the problems are solvedThe modification means of the ternary material is mainly realized by cladding and doping, wherein the doping can be divided into metal ion doping and nonmetal ion doping, the metal ion doping is replaced according to the difference of ion radius, the ion positions are also different, for example, the doping ion radius is larger than that of the replacing ion, and the layered crystal structure after stable delithiation can effectively improve Li at the same time + Is a migration rate of (a); the doped ions occupy the transition metal position, so that the layered structure of NCM can be effectively inhibited from being turned into a spinel structure during deep lithium removal. The non-metal ion is doped with O 2- Ions of similar ionic radius, e.g. F - 、B 3+ To replace O 2- The sites form more stable Li-F bonds and B-O bonds, stabilize the NCM crystal structure and prevent the precipitation of lattice oxygen. The ternary material coating modification can achieve different modification effects according to different coating materials, such as polypyrrole, graphene and the like coating a layer of electronic conductive material with nanometer thickness, so that the electronic conductivity of the ternary material can be improved; the coating of a layer of stable oxide can effectively prevent the residual lithium on the surface of the material from reacting with moisture and carbon dioxide in the air and also can protect the lithium from being corroded by electrolyte; the lithium ion conductive material is coated, and the lithium ion conductivity of the material can be remarkably improved due to the three-dimensional lithium ion diffusion channel and the stable internal structure.
The Chinese patent publication No. CN114220965A discloses a preparation method of a high-nickel ternary cathode material, which comprises the steps of mixing, sintering and crushing ternary material and lithium salt, and then performing two-sintering cladding to prepare the ternary cathode material, wherein the cladding layer is synthesized by mixing and sintering metal oxidation and LiOH to synthesize Li 2 MoO 4 、Li 2 WO 4 Or Li (lithium) 2 SnO 3 . The ternary material prepared by the method has uniform primary particle size, tight combination between the primary particles and Li formation on the surface of the primary particles 2 MoO 4 、Li 2 WO 4 Or Li (lithium) 2 SnO 3 And the plasma conductor coating layer forms a protective layer and a lithium ion conductor on the material, so that the capacity, the circulation and the rate performance of the material are improved. However, the primary sintering is carried out under the low temperature condition of lithium deficiency, so that the crystals of the primary particles are grownWhen the length is unstable and the subsequent liquid-phase secondary lithium supplementation is carried out, the ternary material is subjected to the liquid-phase secondary lithium supplementation under the condition of unstable crystal structure, so that the metal element manganese is easily dissolved, and the crystal structure is completely destroyed.
For example, chinese patent publication No. CN107946551A discloses a doped lithium nickel manganese oxide material, a modified lithium nickel manganese oxide positive electrode material and a preparation method thereof, and the prepared material has uniform particle distribution and Li 2 SnO 3 The modified lithium nickel manganese oxide anode material is obtained by uniformly coating the surface of the doped lithium nickel manganese oxide material, and has good structural stability, cycle performance and thermal stability. However, the above patent uses sol-gel method to coat lithium ion conductor Li 2 SnO 3 Although the uniform coating at the molecular level can be achieved, the cost of industrialized application is high, the optimization and control of the process technology are complex, and only the ion conductor layer is introduced for modification, and although the diffusion coefficient of lithium ions can be improved, the precipitation of lattice oxygen cannot be inhibited during the cyclic test under high current, so that the capacity attenuation at the later stage of the cell cycle is obvious.
Disclosure of Invention
The invention provides a lithium nickel cobalt manganese oxide ternary material, which gradually increases the loading duty ratio in the field of power batteries due to high energy density and specific capacity, but has the advantages that lattice oxygen is separated out in the circulating process, the layered structure is converted to spinel so as to lead irreversible capacity loss, and the ternary material also has lithium nickel mixed discharge and unstable TM (transition metal) -O bond, so that the problems can be solved 2 SnO 3 The double-layer coating modified ternary cathode material comprises a double-layer coating modified ternary cathode material, a preparation method and application thereof, elements such as Al, zr, ta and the like are doped in a bulk phase to form a strong chemical bond with oxygen to inhibit precipitation of lattice oxygen, so that mixed discharge of lithium and nickel is reduced, the introduction of tantalum doped titanium dioxide and a rapid lithium ion conductor layer inhibit side reaction with electrolyte, the diffusion coefficient of lithium ions is improved, and the requirement of high-rate charge and discharge is met.
The technical scheme adopted by the invention for solving the technical problems is as follows:
the invention provides tantalum doped titanium dioxide and Li 2 SnO 3 The general formula of the double-layer coating modified ternary anode material is as follows: li (Li) 2 SnO 3 @Ta-TiO 2-x @LiNi x Co y Mn z Al a Zr b Ta c Sr d O 2 ，x+y+z+a+b+c+d＝1。
As a preferred embodiment, 0.5.ltoreq.x < 1.0, 0.ltoreq.y < 0.5,0 < z.ltoreq.1-x-y.
As a preferred embodiment, the sum of the amounts of the substances of the transition metal elements Ni, co and Mn is expressed by TM, and the molar ratio of Li to TM is (0.9-1.2) to 1.
The invention provides tantalum doped titanium dioxide and Li 2 SnO 3 The preparation method of the double-layer coated modified ternary positive electrode material mainly comprises the following steps:
(1) The ternary material precursor nickel cobalt manganese hydroxide Ni x Co y Mn z (OH) 2 Uniformly mixing a lithium source and an additive according to the molar ratio of 1:0.9-1.2:0.0001-0.01, and then carrying out primary sintering solid phase reaction, wherein a gradient heating sintering mode is adopted: heating to 400-550 ℃ for the first time, wherein the heat preservation time is 4-8 h, and the heating rate is 1-20 ℃/min; heating to 600-1000 ℃ for the second time, wherein the heat preservation time is 6-14 h, and the heating rate is 1-20 ℃/min; obtain a one-bake doped semi-finished product ternary material matrix LiNi x Co y Mn z Al a Zr b Ta c Sr d O 2 ；
(2) Doping a semi-finished product ternary material matrix LiNi by one-step sintering x Co y Mn z Al a Zr b Ta c Sr d O 2 After washing, dispersing in a solvent, and recording as a dispersion liquid A; dispersing tantalum salt in a solvent, and dropwise adding a titanium salt solution according to the molar ratio of the tantalum salt to the titanium salt (0.001-0.1) to 1, and marking as a dispersion liquid B; transferring the dispersion liquid B into the dispersion liquid A for wet coating, wherein the titanium salt and the one-bake doped semi-finished product ternary material matrix LiNi x Co y Mn z Al a Zr b Ta c Sr d O 2 The mass ratio of (2) is 200ppm-100000ppm, and the secondary sintering coating is carried out after stirring, evaporation, drying and grinding, twoThe sintering coating temperature is 300-500 ℃, the heat preservation time is 4-8 h, the heating rate is 1-20 ℃/min, and the semi-finished product Ta-TiO is obtained 2-x @LiNi x Co y Mn z Al a Zr b Ta c Sr d O 2 ；
(3) Li is mixed with 2 SnO 3 And a semi-finished Ta-TiO 2-x @LiNi x Co y Mn z Al a Zr b Ta c Sr d O 2 Uniformly mixing 200ppm to 90000ppm by mass ratio, then carrying out dry coating, and then carrying out three times of sintering coating, wherein the temperature of the three times of sintering coating is 300 ℃ to 600 ℃, and the heat preservation time is 3h to 10h, so as to obtain tantalum doped titanium dioxide and Li 2 SnO 3 Double-layer coating modified ternary anode material.
In a preferred embodiment, in the step (1), the lithium source is selected from one or more of lithium carbonate, lithium hydroxide and lithium oxalate.
In a preferred embodiment, in step (1), the additive is selected from the group consisting of Al 2 O 3 、ZrO 2 、Ta 2 O 5 One or more of SrO.
In a preferred embodiment, in step (2), the tantalum salt is tantalum oxide, tantalum chloride or tantalum oxalate.
In a preferred embodiment, in the step (2), the titanium salt is titanium sulfate, titanium chloride, titanium oxalate, sodium citrate titanium salt or tetrabutyl titanate.
In a preferred embodiment, in the step (2), the stirring speed is 300rpm to 2000rpm, the evaporating temperature is 80 ℃ to 120 ℃, and the drying temperature is 90 ℃ to 150 ℃.
In a preferred embodiment, in step (3), the Li 2 SnO 3 The preparation process of (2) is as follows:
dissolving lithium salt and tin salt in a molar ratio of (2-3) to 1 in a solvent for hydrothermal synthesis reaction, wherein the reaction temperature is 140-180 ℃ and the reaction time is 10-20 h; collecting reaction products, washing, drying at 60-90 deg.C for 6-12 hr, and grinding to obtain Li 2 SnO 3 。
As a preferred embodiment, the lithium salt is lithium carbonate, lithium hydroxide, lithium oxalate or lithium methoxide; the tin salt is tin chloride, tin methane sulfonate or stannate.
The invention provides tantalum doped titanium dioxide and Li 2 SnO 3 The double-layer coating modified ternary positive electrode material is applied to preparation of a secondary battery positive electrode plate and a secondary battery.
The beneficial effects of the invention are as follows:
1. zr is introduced based on a typical nickel-cobalt-manganese ternary material 4+ 、Al 3+ 、Sr 2+ 、Ta 5+ The additives are subjected to bulk doping, and then through primary sintering solid phase reaction, the stability of the layered structure of the ternary material subjected to deep lithium removal under high cut-off voltage can be greatly stabilized, the conversion of the layered structure to a spinel structure and the precipitation of lattice oxygen are inhibited, and meanwhile, the size and the particle strength of single crystal particles are adjusted and optimized.
2. In the invention, the product after the primary sintering solid phase reaction is subjected to water washing dispersion treatment, so that the residual LiOH and Li on the surface of the ternary material can be further reduced 2 CO 3 Further improving the cycle performance and the safety performance of the secondary battery.
3. According to the invention, the tantalum doped titanium dioxide oxide layer is designed, so that the electrolyte can be prevented from corroding the material to damage the layered crystal structure in the electrochemical test process, the precipitation of lattice oxygen can be prevented, and meanwhile, the tantalum doped titanium dioxide electronic coordination is unsaturated to generate oxygen vacancies so as to improve the conductivity of the material.
4. In the invention, wet coating is carried out first, and then secondary sintering coating is carried out, wherein the adopted wet coating can lead the coating effect of the tantalum doped titanium dioxide to be more uniform and better.
5. After secondary sintering, double-layer coated rapid lithium ion conductor Li is introduced 2 SnO 3 The dry coating and the three-time sintering coating are carried out, so that a stable three-dimensional lithium ion diffusion channel can be provided, the diffusion rate of lithium ions is improved, the electrode polarization is reduced, and the electrochemical performance of the ternary material is improvedThe chemical properties.
6. Tantalum-doped titanium dioxide and Li of the invention 2 SnO 3 The double-layer coated modified ternary anode material also has the advantages of high electronic conductivity, high ion mobility, low attenuation rate in long-cycle test and the like.
Drawings
FIG. 1 shows tantalum doped titanium dioxide and Li of the invention 2 SnO 3 A flow chart of a preparation method of the double-layer coated modified ternary cathode material.
Fig. 2 is an SEM image. In the drawings, (a) is an SEM image of the material obtained by the preparation of example 1, and (b) is an SEM image of the material obtained by the preparation of example 2.
Fig. 3 is an XRD pattern of the material obtained by the preparation of example 1.
Fig. 4 is a charge-discharge curve under 0.1C discharge conditions at a voltage interval of 3.0V-4.4V. In the figure, (a) is the charge-discharge curve of the material obtained by the preparation of example 1, and (b) is the charge-discharge curve of the material obtained by the preparation of comparative example 1.
FIG. 5 is a graph showing the cycle performance of the materials prepared in example 1 and comparative example 1 under the discharge condition of 0.1C at a voltage interval of 3.0V to 4.4V.
Fig. 6 is a charge-discharge curve under 0.1C discharge conditions at a voltage interval of 3.0V-4.4V. In the figure, (a) is the charge-discharge curve of the material prepared in example 2, and (b) is the charge-discharge curve of the material prepared in comparative example 2.
Detailed Description
The invention provides tantalum doped titanium dioxide and Li 2 SnO 3 The general formula of the double-layer coating modified ternary anode material is as follows: li (Li) 2 SnO 3 @Ta-TiO 2-x @LiNi x Co y Mn z Al a Zr b Ta c Sr d O 2 Wherein x+y+z+a+b+c+d=1.
Wherein, the values of x, y and z are preferably as follows: x is more than or equal to 0.5 and less than or equal to 1.0, y is more than or equal to 0 and less than or equal to 0.5, and z is more than or equal to 0 and less than or equal to (1-x-y).
Wherein the sum of the amounts of the substances of the transition metal elements Ni, co and Mn is represented by TM, and the molar ratio of Li to TM is preferably (0.9-1.2) to 1.
The invention provides tantalum doped titanium dioxide and Li 2 SnO 3 The preparation method of the double-layer coated modified ternary cathode material, as shown in fig. 1, mainly comprises the following steps:
(1) The ternary material precursor nickel cobalt manganese hydroxide Ni x Co y Mn z (OH) 2 Uniformly mixing a lithium source and an additive, and then performing primary sintering solid phase reaction to obtain a sintered doped semi-finished product ternary material matrix LiNi x Co y Mn z Al a Zr b Ta c Sr d O 2 。
Specifically, ternary material precursor Ni, co, mn and hydroxide Ni x Co y Mn z (OH) 2 Lithium source (with Li contained + Uniformly mixing the metal element and the additive (counted by the mole number) according to the mole ratio of 1:0.9-1.2:0.0001-0.01 by adopting mixing equipment, then carrying out primary sintering solid phase reaction by adopting sintering equipment, and adopting a gradient heating sintering mode, namely heating to 400-550 ℃ for the first time, wherein the heat preservation time is 4-8 h, and the heating rate is 1-20 ℃/min; heating to 600-1000 ℃ for the second time, wherein the heat preservation time is 6-14 h, and the heating rate is 1-20 ℃/min; finally obtaining the one-bake doped semi-finished product ternary material matrix LiNi x Co y Mn z Al a Zr b Ta c Sr d O 2 Crushing by air flow mill (particle size D50 is controlled to be 3.7+/-0.8 μm), and sieving by a sieving screen for later use.
In the invention, ternary material precursor Ni-Co-Mn hydroxide Ni x Co y Mn z (OH) 2 The particle size D50 of (2) is 3.7.+ -. 1.2. Mu.m.
In the present invention, the lithium source includes, but is not limited to, one or more of lithium carbonate, lithium hydroxide, lithium oxalate, and the purity of lithium carbonate is 99.5% or more and the purity of lithium hydroxide is 56.5% or more.
In the present invention, in order to stabilize the layered structure of ternary materials deeply delithiated at high cut-off voltage and to suppress the conversion of the layered structure into spinel structure and the precipitation of lattice oxygen, the present invention is typically usedZr is introduced into the ternary material based on the ternary material of nickel, cobalt and manganese 4+ 、Al 3+ 、Sr 2+ 、Ta 5+ Bulk doping is performed with isodoping additives including, but not limited to, al 2 O 3 、ZrO 2 、Ta 2 O 5 One or more mixtures of SrO, and Al 2 O 3 、ZrO 2 、Ta 2 O 5 And the purity of SrO is greater than 99.9%.
In the invention, ternary material precursor Ni-Co-Mn hydroxide Ni x Co y Mn z (OH) 2 Lithium source (with Li contained + The molar ratio of the metal element to the additive (in terms of the number of moles of the metal element included) is preferably 1: (1.0-1.05): (0.0005-0.02).
In the present invention, the mixing equipment used includes, but is not limited to, high-speed blendors, ball mills, coulter mixers, and the like, preferably ball mills; the equipment is adopted to carry out gradient mixing at different rotation speeds, and the materials are transferred into a sagger after being mixed and homogenized.
In the present invention, the sintering equipment used includes, but is not limited to, atmosphere muffle furnace, tube furnace, atmosphere track kiln, etc.; preferably an atmospheric muffle furnace.
In the present invention, when the primary sintering solid phase reaction is performed, the sintering atmosphere is preferably an oxygen atmosphere, the oxygen concentration is preferably more than 90%, and the oxygen concentration is more preferably 99.9%.
Preferably, the temperature is raised to 470 ℃ for the first time, the heat preservation time is 5 hours, and the temperature raising rate is 2 ℃/min; the temperature is raised to 905 ℃ for the second time, the heat preservation time is 12h, and the temperature raising rate is 2 ℃/min.
In the present invention, the number of the sieving screens used is preferably 300 mesh.
The primary sintering is carried out under the condition of high temperature and lithium enrichment, crystal particles grow circularly, the subsequent water washing and wet coating are carried out within a certain residence time, the metal element manganese is less dissolved, the tantalum doped titanium dioxide coating layer introduced by the wet coating is adopted to improve the electrolyte corrosion resistance, and the side reaction of the ternary material and the electrolyte is inhibited.
(2) Doping a semi-finished product ternary material matrix LiNi by one-step sintering x Co y Mn z Al a Zr b Ta c Sr d O 2 After water washing, dispersing in a solvent to obtain a dispersion liquid A; dispersing tantalum salt in a solvent, and dropwise adding a titanium salt solution to obtain a dispersion liquid B; transferring the dispersion liquid B into the dispersion liquid A for wet coating, stirring, evaporating, drying and grinding, and then carrying out secondary sintering coating to obtain a semi-finished product Ta-TiO 2-x @LiNi x Co y Mn z Al a Zr b Ta c Sr d O 2 。
Specifically, a sintered and doped semi-finished ternary material matrix LiNi x Co y Mn z Al a Zr b Ta c Sr d O 2 After washing, dispersing in a solvent, and recording as a dispersion liquid A; dispersing tantalum salt in a solvent, and dropwise adding a titanium salt solution according to the molar ratio of the tantalum salt to the titanium salt (0.001-0.1) to 1, and marking as a dispersion liquid B; transferring the dispersion liquid B into the dispersion liquid A for wet coating, wherein titanium salt and a one-bake doped semi-finished product ternary material matrix LiNi x Co y Mn z Al a Zr b Ta c Sr d O 2 The mass ratio of the powder is 200ppm-100000ppm, and the powder is subjected to stirring, evaporation, drying and grinding, and then is subjected to secondary sintering coating by adopting sintering coating equipment, wherein the secondary sintering coating temperature is 300 ℃ to 500 ℃, the heat preservation time is 4 hours to 8 hours, and the heating rate is 1 ℃/min to 20 ℃/min, so that the semi-finished product Ta-TiO is obtained 2-x @LiNi x Co y Mn z Al a Zr b Ta c Sr d O 2 。
In the invention, a semi-finished product ternary material matrix LiNi is doped by one sintering x Co y Mn z Al a Zr b Ta c Sr d O 2 Dispersing in solvent after washing, and sintering to dope semi-finished ternary material matrix LiNi during washing x Co y Mn z Al a Zr b Ta c Sr d O 2 The mass ratio of the water-washing solvent to the water-washing solvent is 0.5-1 (preferably 0.675), and the water-washing solvent includes but is not limited to ultrapure water and organic solventAgents (e.g., ethanol, methanol), etc., preferably ultrapure water. In the invention, the surface residual LiOH and Li of the high-nickel ternary material can be further reduced by carrying out water washing dispersion operation after primary sintering solid phase reaction 2 CO 3 The cycle performance and the safety performance of the battery are further improved.
In the invention, a semi-finished product ternary material matrix LiNi is doped by one sintering x Co y Mn z Al a Zr b Ta c Sr d O 2 After washing with water, the mixture is dispersed in a solvent, wherein the solvent is an organic solvent or an inorganic salt solution, preferably an ethanol solution.
In the invention, in order to prevent electrolyte from corroding materials to damage a layered crystal structure and prevent lattice oxygen from precipitating in the electrochemical test process, a tantalum doped titanium dioxide coating layer is designed, and titanium dioxide electron coordination is unsaturated to generate oxygen vacancies by doping tantalum, so that the conductivity of the materials is improved. Specifically, tantalum salt can be dispersed in a solvent, and the adopted solvent is preferably ethanol solution; then, a titanium salt solution was added dropwise in a molar ratio of tantalum salt to titanium salt of (0.001-0.1) to 1, and this was designated as dispersion B. In addition, the dispersion liquid B is transferred into the dispersion liquid A for wet coating, wherein the coating effect of the wet coating is more uniform and better, and the coating effect can reach the nano level.
In the present invention, the molar ratio of tantalum salt to titanium salt is preferably 0.0125:1. Tantalum salts include, but are not limited to, tantalum oxide, tantalum chloride, tantalum oxalate, and the like, with tantalum chloride being preferred. Titanium salts include, but are not limited to, organic or inorganic salts such as titanium sulfate, titanium chloride, titanium oxalate, sodium citrate titanium salt, and tetrabutyl titanate, with tetrabutyl titanate being preferred.
In the invention, the ternary material matrix of titanium salt and one-bake doped semi-finished product
LiNi x Co y Mn z Al a Zr b Ta c Sr d O 2 Preferably 1000ppm to 95000ppm by mass.
In the present invention, the stirring speed is 300rpm to 2000rpm, preferably 600rpm; the evaporation temperature is 80-120 ℃, preferably 90 ℃; the drying temperature is 90℃to 150℃and preferably 120 ℃.
In the present invention, drying equipment used in drying includes, but is not limited to, equipment such as vacuum ovens.
In the present invention, the sintering cladding equipment used includes, but is not limited to, atmosphere muffle furnace, tube furnace, atmosphere track kiln, etc.; preferably an atmospheric muffle furnace.
Preferably, the secondary sintering coating temperature is 410 ℃, the heat preservation time is 6 hours, and the heating rate is 2 ℃/min.
In the present invention, in the case of performing the secondary sintering coating, the sintering atmosphere is an oxygen atmosphere or a compressed air atmosphere, preferably an oxygen atmosphere, the oxygen concentration is preferably more than 90%, and the oxygen concentration is more preferably 99.9%.
(3) Synthesis of rapid lithium ion conductor Li by hydrothermal synthesis method 2 SnO 3 Then Li is taken 2 SnO 3 With semi-finished Ta-TiO 2-x @LiNi x Co y Mn z Al a Zr b Ta c Sr d O 2 Mixing uniformly, and then carrying out three times of sintering coating to obtain tantalum doped titanium dioxide and Li 2 SnO 3 Double-layer coating modified ternary anode material. By introducing a rapid lithium ion conductor Li after the secondary sintering coating and before the tertiary sintering coating 2 SnO 3 The three-dimensional lithium ion diffusion channel can be provided stably, the diffusion rate of lithium ions is improved, the polarization of the electrode is reduced, and the electrochemical performance of the ternary material is further improved.
Specifically, first, a rapid lithium ion conductor Li is prepared 2 SnO 3 : dissolving lithium salt (counted by the mole number of the contained lithium element) and tin salt (counted by the mole number of the contained tin element) in a molar ratio of (2-3) to 1 into a solvent for hydrothermal synthesis reaction, wherein the hydrothermal reaction temperature is 140-180 ℃ and the reaction time is 10-20 h; collecting reaction products, washing, drying at 60-90 deg.C for 6-12 hr, and grinding to obtain Li 2 SnO 3 The method comprises the steps of carrying out a first treatment on the surface of the The prepared rapid lithium ion conductor Li 2 SnO 3 And a semi-finished Ta-TiO 2-x @LiNi x Co y Mn z Al a Zr b Ta c Sr d O 2 Mixing uniformly by adopting mixing equipment according to the mass ratio of 200ppm-90000ppm, then carrying out dry coating, and then carrying out three-time sintering coating by adopting sintering coating equipment, wherein the three-time sintering coating temperature is 300-600 ℃, and the heat preservation time is 3-10 h, so as to obtain tantalum doped titanium dioxide and Li 2 SnO 3 Double-layer coating modified ternary anode material.
In the present invention, lithium salts include, but are not limited to, lithium carbonate, lithium hydroxide, lithium oxalate, lithium methoxide, and the like; lithium methoxide is preferred.
In the present invention, tin salts include, but are not limited to, tin chloride, tin methane sulfonate, stannates, and the like; tin chloride is preferred.
In the present invention, the molar ratio of the lithium salt (in terms of moles of the contained lithium element) to the tin salt (in terms of moles of the contained tin element) is preferably 2.02:1.
In the present invention, the lithium salt and the tin salt are dissolved in a solvent, and the solvent used is preferably an ethanol solution.
In the present invention, when the hydrothermal synthesis reaction is carried out, the hydrothermal reaction temperature is preferably 150℃and the reaction time is preferably 15 hours.
In the present invention, when the reaction product is collected for washing, the washing means includes, but is not limited to, filtration and centrifugation, and the like, preferably centrifugal washing; the washing rotating speed ranges from 500rpm to 8000rpm; washing solvents include, but are not limited to, deionized water, absolute ethanol, and the like; the washing times are 3-5 times.
In the present invention, the drying is preferably vacuum drying when the washing is followed by drying.
In the present invention, li 2 SnO 3 And a semi-finished Ta-TiO 2-x @LiNi x Co y Mn z Al a Zr b Ta c Sr d O 2 The mass ratio of (2) is preferably 200ppm to 20000ppm.
In the present invention, mixing equipment used includes, but is not limited to, equipment such as high-speed blendors, ball mills, and coulter mixers, and preferably ball mills.
In the present invention, the sintering cladding equipment used includes, but is not limited to, atmosphere muffle furnace, tube furnace, atmosphere track kiln, etc.; preferably an atmospheric muffle furnace.
In the invention, the temperature of the three-time sintering coating is preferably 450 ℃, and the heat preservation time is preferably 9h.
In the present invention, when the three-time sintering coating is performed, the sintering atmosphere is an oxygen atmosphere or a compressed air atmosphere, preferably an oxygen atmosphere, the oxygen concentration is preferably more than 90%, and the oxygen concentration is more preferably 99.9%.
According to the invention, bulk doping is firstly carried out, elements Al, zr and the like capable of forming strong chemical bonds by oxygen are introduced to inhibit precipitation of lattice oxygen, a tantalum-doped titanium dioxide coating layer is introduced by wet coating to inhibit side reaction of ternary materials and electrolyte, and finally a lithium ion rapid conductor layer is introduced by dry coating to improve multiplying power charge-discharge capability of the materials.
The invention provides tantalum doped titanium dioxide and Li 2 SnO 3 The double-layer coating modified ternary positive electrode material can be applied to preparation of a secondary battery positive electrode plate or a secondary battery, and the prepared secondary battery has higher cycle performance and safety performance.
The technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention, and it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
EXAMPLE 1 tantalum doped titanium dioxide and Li 2 SnO 3 Preparation of double-layer coated modified ternary positive electrode material
Tantalum-doped titanium dioxide and Li obtained in this example 2 SnO 3 The general formula of the double-layer coated modified ternary positive electrode material is Li 2 SnO 3 @Ta-TiO 2-x @LiNi 0.72 Co 0.05 Mn 0.23 Al a Zr b Ta c Sr d O 2 。
(1) Preparing ternary material precursor Ni-Co-Mn hydroxide Ni 0.72 Co 0.05 Mn 0.23 (OH) 2 、Li 2 CO 3 And additives (Al) 2 O 3 、ZrO 2 、Ta 2 O 5 And SrO). In this embodiment, the mass and index of each material weighed are as follows:
ternary material precursor nickel cobalt manganese hydroxide Ni 0.72 Co 0.05 Mn 0.23 (OH) 2 65.00g of ternary material precursor Ni-Co-Mn hydroxide x Co y Mn z (OH) 2 The particle size D50 of (2) is 3.7+ -1.2 μm;
Li 2 CO 3 25.07g, the purity is more than or equal to 99.9%;
Al 2 O 3 0.1804g, purity > 99.9%;
ZrO 2 0.1212g, purity > 99.9%;
Ta 2 O 5 0.0977g, purity > 99.9%;
SrO,0.0330g and purity > 99.9%.
Transferring the weighed materials into a ball mill for mixing, wherein mixing parameters are as follows: the rotating speed is 250rpm, the time is 60min, zirconium beads are separated through 30 meshes after the mixing, the materials are transferred into a sagger after being mixed and homogenized, then transferred into an atmosphere muffle furnace, the micro-positive pressure oxygen atmosphere is carried out, the oxygen concentration is 99.9%, the oxygen flow is 5L/min, the temperature is increased to 470 ℃ at the heating rate of 2 ℃/min for 5h, the temperature is increased to 905 ℃ at the heating rate of 2 ℃/min for 12h, and the sintered doped semi-finished product ternary material matrix LiNi is obtained 0.72 Co 0.05 Mn 0.23 Al a Zr b Ta c Sr d O 2 Cooling, pulverizing with air flow mill (particle size D50 is controlled to 3.7+ -0.8 μm), sieving with sieve (300 mesh) for use.
(2) Preparing the one-bake doped semi-finished product ternary material matrix LiNi 0.90 Co 0.05 Mn 0.05 Al a Zr b Ta c Sr d O 2 In the process of (2) is Ni7205 with high nickel contentSintering doped semi-finished ternary material matrix LiNi 0.72 Co 0.05 Mn 0.23 Al a Zr b Ta c Sr d O 2 After being washed by ultrapure water, the mixture is dispersed in ethanol solution, and when washed, the mixture is burned to dope semi-finished ternary material matrix LiNi x Co y Mn z Al a Zr b Ta c Sr d O 2 The mass ratio to ultrapure water was 0.675, which was designated as dispersion A; 0.0082g of tantalum chloride was dispersed in 10ml of ethanol solution, and 0.6231g of tetrabutyl titanate was added dropwise, which was designated as dispersion B; transferring the dispersion liquid B into the dispersion liquid A, stirring (600 rpm,60 min), evaporating (90 ℃), drying (vacuum oven, 120 ℃ for 7 h) and grinding, then loading into a sagger, transferring into an atmosphere muffle furnace, slightly positive pressure oxygen atmosphere, oxygen concentration of 99.9%, oxygen flow of 5L/min, heating to 410 ℃ at a heating rate of 2 ℃/min, and preserving heat for 6h to obtain a semi-finished product Ta-TiO 2-x @LiNi 0.72 Co 0.05 Mn 0.23 Al a Zr b Ta c Sr d O 2 。
(3) Quick lithium ion conductor Li 2 SnO 3 The synthesis is carried out by a hydrothermal reaction method: dissolving 0.0492g of lithium methoxide and 0.1671g of tin chloride in 30ml of ethanol solution, transferring the solution into a hydrothermal reaction kettle after the solution is completely dissolved, wherein the hydrothermal reaction temperature is 150 ℃, the reaction time is 15 hours, naturally cooling after the hydrothermal reaction is finished, collecting a reaction product, centrifugally washing for 5 minutes at 8000rpm, washing the reaction product for 4 times by using absolute ethanol, and performing vacuum drying after the washing is finished, wherein the drying temperature is 90 ℃, and the drying time is 12 hours; grinding into fine powder after drying to obtain the rapid lithium ion conductor Li 2 SnO 3 。
0.1158g of rapid lithium ion conductor Li is weighed accurately 2 SnO 3 And 60.0g of semi-finished Ta-TiO 2-x @LiNi 0.72 Co 0.0 5 Mn 0.23 Al a Zr b Ta c Sr d O 2 Mixing materials by adopting a ball mill, wherein mixing parameters are as follows: the rotating speed is 210rpm, the time is 40min, the mixture is transferred into a sagger after being uniformly mixed, and the sagger is transferred into an atmosphere muffle furnace for third sintering coating and micro-grinding after being uniformly filledThe positive pressure oxygen atmosphere, the oxygen concentration of 99.9 percent, the oxygen flow of 5L/min, the temperature rise rate of 2 ℃/min to 450 ℃, the heat preservation for 9 hours, and finally the tantalum doped titanium dioxide and Li are prepared by sieving 2 SnO 3 Double-layer coating modified ternary positive electrode material Li 2 SnO 3 @Ta-TiO 2-x @LiNi 0.7 2 Co 0.05 Mn 0.23 Al a Zr b Ta c Sr d O 2 。
Comparative example 1 ternary cathode material LiNi 0.72 Co 0.05 Mn 0.23 Al a Zr b Ta c Sr d O 2 Is prepared from
(1) Preparing ternary material precursor Ni-Co-Mn hydroxide Ni 0.72 Co 0.05 Mn 0.23 (OH) 2 、Li 2 CO 3 And additives (Al) 2 O 3 、ZrO 2 、Ta 2 O 5 And SrO; in this embodiment, the mass and index of each material weighed are as follows:
ternary material precursor nickel cobalt manganese hydroxide Ni 0.72 Co 0.05 Mn 0.23 (OH) 2 65.00g of ternary material precursor Ni-Co-Mn hydroxide x Co y Mn z (OH) 2 The particle size D50 of (2) is 3.7+ -1.2 μm;
Li 2 CO 3 25.07g, the purity is more than or equal to 99.9%;
Al 2 O 3 0.1804g, purity > 99.9%;
ZrO 2 0.1212g, purity > 99.9%;
Ta 2 O 5 0.0977g, purity > 99.9%;
SrO,0.0330g and purity > 99.9%.
Transferring the weighed materials into a ball mill for mixing, wherein mixing parameters are as follows: the rotating speed is 250rpm, the time is 60min, zirconium beads are separated through 30-mesh sieve after the mixing, the materials are transferred into a sagger after being mixed and homogenized, and then transferred into an atmosphere muffle furnace, the micro-positive pressure oxygen atmosphere is adopted, the oxygen concentration is 99.9%, the oxygen flow is 5L/min, and the temperature is increased by 2 ℃/minHeating to 470 ℃ at a rate, preserving heat for 5 hours, and then heating to 905 ℃ at a heating rate of 2 ℃/min, preserving heat for 12 hours to obtain the ternary cathode material LiNi 0.72 Co 0.05 Mn 0.23 Al a Zr b Ta c Sr d O 2 Cooling, pulverizing with air flow mill (particle size D50 is controlled to 3.7+ -0.8 μm), sieving with sieve (300 mesh) for use.
EXAMPLE 2 tantalum doped titanium dioxide and Li 2 SnO 3 Preparation of double-layer coated modified ternary positive electrode material
Tantalum-doped titanium dioxide and Li obtained in this example 2 SnO 3 The general formula of the double-layer coated modified ternary positive electrode material is Li 2 SnO 3 @Ta-TiO 2-x @LiNi 0.90 Co 0.05 Mn 0.05 Al a Zr b Ta c Sr d O 2 。
(1) Preparing ternary material precursor Ni-Co-Mn hydroxide Ni 0.90 Co 0.05 Mn 0.05 (OH) 2 LiOH and additives (Al 2 O 3 、ZrO 2 、Ta 2 O 5 And SrO; in this embodiment, the mass and index of each material weighed are as follows:
ternary material precursor nickel cobalt manganese hydroxide Ni 0.72 Co 0.05 Mn 0.23 (OH) 2 65.00g of ternary material precursor Ni-Co-Mn hydroxide x Co y Mn z (OH) 2 The particle size D50 of (2) is 3.7+ -1.2 μm;
LiOH,25.30g, purity not less than 56.5%;
Al 2 O 3 0.1709g, purity > 99.9%;
ZrO 2 0.1203g, purity > 99.9%;
Ta 2 O 5 0.0970g, purity > 99.9%;
SrO,0.0327g, purity > 99.9%.
Transferring the weighed materials into a ball mill for mixing, wherein mixing parameters are as follows: rotating at 250rpm for 40min, sieving with 30 mesh sieve to separate zirconium beads after mixingThe materials are mixed and homogenized, transferred into a sagger, then transferred into an atmosphere muffle furnace, the micro-positive pressure oxygen atmosphere is adopted, the oxygen concentration is 99.9%, the oxygen flow is 5L/min, the temperature is increased to 420 ℃ at the heating rate of 2 ℃/min for 6h, the temperature is increased to 860 ℃ at the heating rate of 2 ℃/min for 10h, and the sintered doped semi-finished product ternary material matrix LiNi is obtained 0.90 Co 0.05 Mn 0.05 Al a Zr b Ta c Sr d O 2 Cooling, pulverizing with air flow mill (particle size D50 is controlled to 3.7+ -0.8 μm), sieving with sieve (300 mesh) for use.
(2) Preparing the one-bake doped semi-finished product ternary material matrix LiNi 0.90 Co 0.05 Mn 0.05 Al a Zr b Ta c Sr d O 2 In the process of (1) is high nickel Ni9005, a sintered doped semi-finished product ternary material matrix LiNi 0.72 Co 0.05 Mn 0.23 Al a Zr b Ta c Sr d O 2 After being washed by ultrapure water, the mixture is dispersed in ethanol solution, and when washed, the mixture is burned to dope semi-finished ternary material matrix LiNi x Co y Mn z Al a Zr b Ta c Sr d O 2 The mass ratio to ultrapure water was 0.67, which was designated as dispersion A; 0.0082g of tantalum chloride was dispersed in 10ml of ethanol solution, and 0.6231g of tetrabutyl titanate was added dropwise, which was designated as dispersion B; transferring the dispersion liquid B into the dispersion liquid A, stirring (900 rpm,40 min), evaporating (80 ℃), drying (vacuum oven, 90 ℃ for 7 h) and grinding, then loading into a sagger, transferring into an atmosphere muffle furnace, slightly positive pressure oxygen atmosphere, oxygen concentration of 99.9%, oxygen flow of 5L/min, heating to 360 ℃ at a heating rate of 2 ℃/min, and preserving heat for 6h to obtain a semi-finished product Ta-TiO 2-x @LiNi 0.90 Co 0.05 Mn 0.05 Al a Zr b Ta c Sr d O 2 。
(3) Quick lithium ion conductor Li 2 SnO 3 The synthesis is carried out by a hydrothermal reaction method: dissolving 0.0492g of lithium methoxide and 0.1671g of tin chloride in 30ml of ethanol solution, transferring to a hydrothermal reaction kettle after complete dissolution, wherein the hydrothermal reaction temperature is 150 ℃, the reaction time is 15h, and the hydrothermal reaction is completedAfter the reaction product is finished, naturally cooling, collecting the reaction product, centrifugally washing for 5min at 8000rpm, washing for 4 times by using absolute ethyl alcohol as a washing solvent, and performing vacuum drying after the washing is finished, wherein the drying temperature is 90 ℃ and the drying time is 12h; grinding into fine powder after drying to obtain the rapid lithium ion conductor Li 2 SnO 3 。
0.1158g of rapid lithium ion conductor Li is weighed accurately 2 SnO 3 And 60.0g of semi-finished Ta-TiO 2-x @LiNi 0.72 Co 0.0 5 Mn 0.23 Al a Zr b Ta c Sr d O 2 Mixing materials by adopting a ball mill, wherein mixing parameters are as follows: the rotating speed is 210rpm, the time is 40min, the mixture is transferred to a sagger after being uniformly mixed, after being uniformly filled, the mixture is transferred to an atmosphere muffle furnace for carrying out third sintering cladding, the micro-positive pressure oxygen atmosphere with the oxygen concentration of 99.9 percent and the oxygen flow of 5L/min is heated to 380 ℃ at the heating rate of 2 ℃/min, the temperature is kept for 9h, and finally the mixture is sieved to prepare the tantalum doped titanium dioxide and Li 2 SnO 3 Double-layer coating modified ternary positive electrode material Li 2 SnO 3 @Ta-TiO 2-x @LiNi 0.9 0 Co 0.05 Mn 0.05 Al a Zr b Ta c Sr d O 2 。
Comparative example 2 ternary cathode material LiNi 0.90 Co 0.05 Mn 0.05 Al a Zr b Ta c Sr d O 2 Is prepared from
(1) Preparing ternary material precursor Ni-Co-Mn hydroxide Ni 0.90 Co 0.05 Mn 0.05 (OH) 2 LiOH and additives (Al 2 O 3 、ZrO 2 、Ta 2 O 5 And SrO; in this embodiment, the mass and index of each material weighed are as follows:
ternary material precursor nickel cobalt manganese hydroxide Ni 0.72 Co 0.05 Mn 0.23 (OH) 2 65.00g of ternary material precursor Ni-Co-Mn hydroxide x Co y Mn z (OH) 2 The particle size D50 of (2) is 3.7+ -1.2 μm;
LiOH,25.30g, purity not less than 56.5%;
Al 2 O 3 0.1709g, purity > 99.9%;
ZrO 2 0.1203g, purity > 99.9%;
Ta 2 O 5 0.0970g, purity > 99.9%;
SrO,0.0327g, purity > 99.9%.
Transferring the weighed materials into a ball mill for mixing, wherein mixing parameters are as follows: the rotating speed is 250rpm, the time is 40min, zirconium beads are separated through 30 meshes after the mixing, the materials are mixed and homogenized, then transferred into a sagger, transferred into an atmosphere muffle furnace, heated to 420 ℃ at a heating rate of 2 ℃/min for 6h, heated to 860 ℃ at a heating rate of 2 ℃/min for 10h, and finally the ternary anode material LiNi is obtained 0.90 Co 0.05 Mn 0.05 Al a Zr b Ta c Sr d O 2 Cooling, pulverizing with air flow mill (particle size D50 is controlled to 3.7+ -0.8 μm), sieving with sieve (300 mesh) for use.
Experimental example 1SEM characterization analysis
Tantalum-doped titanium dioxide and Li prepared in example 1 and example 2 2 SnO 3 The double-layer coating modified ternary cathode material is subjected to scanning electron microscope test, and an SEM (scanning electron microscope) diagram of the test is shown in FIG. 2. Analysis of SEM characterization results revealed that the tantalum-doped titanium dioxide and Li prepared in example 1 and example 2 2 SnO 3 The double-layer coating modified ternary cathode material is a typical single crystal particle, the microscopic size is between 2 micrometers and 4 micrometers, and the surface of the single crystal particle is roughened, so that the existence of a coating layer is also proved.
XRD tests were also performed on example 1, and the XRD patterns of the tests are shown in fig. 3. Tantalum-doped titanium dioxide and Li obtained in example 1 2 SnO 3 The double-layer coating modified ternary positive electrode material belongs to a typical alpha-NaFeO with R3m space group 2 The distinct division of the hexagonal structure, in which (006)/(102) and (108)/(110) are bimodal, shows that the material has a typical layered structure,this also demonstrates that trace element doping and double cladding do not significantly alter the crystal structure of the ternary material. Wherein, the value of I (003)/I (004) is 2.4 & gt 1.2, and the modification method has lower lithium nickel mixing ratio.
Test example 2 physical and chemical index test of Total alkali
Examples 1-2 and comparative examples 1-2 electrochemical titration of residual lithium carbonate, lithium hydroxide and total alkali concentration on the surface of the test materials was performed with HCl standard solution, and the results are shown in table 1.
TABLE 1 results of the physical and chemical index test of the Total alkali of examples 1-2 and comparative examples 1-2
Material Total alkali (ppm) Li 2 CO 3 (ppm) LiOH(ppm)
Example 1 4263 2317 1261
Example 2 6553 4128 1572
Comparative example 1 10286 5400 3167
Comparative example 2 13459 7016 4645
Examples 1-2 compared to comparative examples 1-2 total alkali, residual Li 2 CO 3 And LiOH is obviously reduced, and due to a water washing process after one-step firing, the water washing process obviously improves the reduction of residual alkali of middle-high nickel and high nickel materials, and the subsequent wet coating is directly carried out, so that the electrochemical performance of the materials can be effectively improved.
Test example 3 electric-buckling assembly and electrochemical Performance test
The materials prepared in examples 1-2 and comparative examples 1-2 were assembled by buckling, and tested for electrochemical performance, the buckling type was CR2032, the slurry of the positive electrode sheet was a mixture of active material, binder (PVDF) and conductive agent (SP), the slurry was prepared by mixing the active material, binder (PVDF) and conductive agent (SP) =97.5:1.25:1.25, and then dropping an appropriate amount of NMP to prepare a slurry, coating the slurry on an aluminum foil, vacuum-drying and punching the slurry to a sheet with a diameter of 10mm, the negative electrode was a metallic lithium sheet, the electrolyte was LiPF6 solution with a concentration of 1mol/L, the solvent was a mixture of dimethyl carbonate, methyl ethyl carbonate and ethylene carbonate, and the volume ratio of dimethyl carbonate, methyl ethyl carbonate and ethylene carbonate was 1:1:1.
Example 1 and comparative example 1 the first-turn test results under 0.1C discharge current conditions at a voltage interval of 3.0V-4.4V are shown in table 2.
Table 2 example 1 and comparative example 1 buckling test results
The efficiency of the discharge gram specific capacity of the first circle is compared and analyzed, the example 1 after coating doping is obviously superior to the example 1, the improvement of the discharge gram specific capacity is attributed to the rapid lithium ion conductor coated by the outer layer, the first effect improvement can prove that the coating layer can effectively reduce the loss of active lithium, the platform appears in the same potential in the charge-discharge curve of fig. 4 in both the example 1 and the example 1, and no new platform exists in the example 1, which also shows that the electrochemical process is not changed by the double-layer coating.
To verify the improvement of the cycle performance by the double-layer coating, the cycle performance test voltage interval was 3.0V-4.4V, and the current was 1C, and the result is shown in fig. 5. The capacity retention rate of example 1 with double-layer coating after 100 charge and discharge tests is 93.5%, the capacity retention rate of comparative example 1 is 86.2%, and the improvement of the retention rate also proves that the inner-layer tantalum-doped titanium dioxide adopts wet coating, the coating effect is more uniform, the corrosion of electrolyte in the circulation process can be effectively prevented, and the outer-layer rapid lithium ion conductor forms a stable lithium ion migration channel, so that the gram capacity of example 1 is higher.
Example 2 and comparative example 2 the first-turn test results under 0.1C discharge current conditions at a voltage interval of 3.0V-4.4V are shown in table 3.
TABLE 3 buckling test results for example 2 and comparative example 2
Example 2 increases in first-turn efficiency and specific discharge capacity compared to comparative example 2 demonstrate tantalum doped titanium dioxide and Li 2 SnO 3 The double-layer coating of the (C) can effectively improve the electrochemical performance of the ternary material, and as shown in figure 6, a charge-discharge curve also maintains a consistent electrochemical platform, and the double-layer coating is proved to not change the electrochemical process.
The invention discloses tantalum doped titanium dioxide and Li 2 SnO 3 The double-layer coating modified ternary cathode material, the preparation method and the application thereof can be realized by appropriately improving the technological parameters by a person skilled in the art by referring to the content of the text. It is especially pointed out that all similar substitutions and modifications will be apparent to those skilled in the art, all of which are regarded as packagesThe invention is covered. While the invention has been described with reference to preferred embodiments, it will be apparent to those skilled in the relevant art that variations and modifications can be made in the invention described herein without departing from the spirit or scope of the invention.

Claims (10)

1. Tantalum doped titanium dioxide and Li 2 SnO 3 The double-layer coating modified ternary positive electrode material is characterized by having the following general formula: li (Li) 2 SnO 3 @Ta-TiO 2-x @LiNi x Co y Mn z Al a Zr b Ta c Sr d O 2 ，x+y+z+a+b+c+d＝1。
2. Tantalum doped titanium dioxide and Li according to claim 1 2 SnO 3 The double-layer coating modified ternary anode material is characterized in that x is more than or equal to 0.5 and less than or equal to 1.0, y is more than or equal to 0 and less than or equal to 0.5, and z is more than or equal to 0 and less than or equal to (1-x-y).
3. Tantalum doped titanium dioxide and Li according to claim 1 2 SnO 3 The double-layer coating modified ternary positive electrode material is characterized in that the sum of the amounts of substances of transition metal elements Ni, co and Mn is expressed by TM, and the molar ratio of Li to TM is (0.9-1.2) to 1.
4. The tantalum-doped titanium dioxide and Li of any of claims 1-3 2 SnO 3 The preparation method of the double-layer coated modified ternary positive electrode material is characterized by comprising the following steps of:
(1) The ternary material precursor nickel cobalt manganese hydroxide Ni x Co y Mn z (OH) 2 Uniformly mixing a lithium source and an additive according to the molar ratio of 1:0.9-1.2:0.0001-0.01, and then carrying out primary sintering solid phase reaction, wherein a gradient heating sintering mode is adopted: heating to 400-550 ℃ for the first time, wherein the heat preservation time is 4-8 h, and the heating rate is 1-20 ℃/min; heating to 600-1000 ℃ for the second time, wherein the heat preservation time is 6-14 h, and the heating rate is 1-20 ℃/min; obtaining a sintered doped semi-finished productTernary material matrix LiNi x Co y Mn z Al a Zr b Ta c Sr d O 2 ；
(2) Doping a semi-finished product ternary material matrix LiNi by one-step sintering x Co y Mn z Al a Zr b Ta c Sr d O 2 After washing, dispersing in a solvent, and recording as a dispersion liquid A; dispersing tantalum salt in a solvent, and dropwise adding a titanium salt solution according to the molar ratio of the tantalum salt to the titanium salt (0.001-0.1) to 1, and marking as a dispersion liquid B; transferring the dispersion liquid B into the dispersion liquid A for wet coating, wherein the titanium salt and the one-bake doped semi-finished product ternary material matrix LiNi x Co y Mn z Al a Zr b Ta c Sr d O 2 The mass ratio of the powder is 200ppm-100000ppm, and the powder is subjected to secondary sintering coating after stirring, evaporation, drying and grinding, wherein the secondary sintering coating temperature is 300 ℃ to 500 ℃, the heat preservation time is 4 hours to 8 hours, and the heating rate is 1 ℃/min to 20 ℃/min, thus obtaining the semi-finished product Ta-TiO 2-x @LiNi x Co y Mn z Al a Zr b Ta c Sr d O 2 ；
(3) Li is mixed with 2 SnO 3 And a semi-finished Ta-TiO 2-x @LiNi x Co y Mn z Al a Zr b Ta c Sr d O 2 Uniformly mixing 200ppm to 90000ppm by mass ratio, then carrying out dry coating, and then carrying out three times of sintering coating, wherein the temperature of the three times of sintering coating is 300 ℃ to 600 ℃, and the heat preservation time is 3h to 10h, so as to obtain tantalum doped titanium dioxide and Li 2 SnO 3 Double-layer coating modified ternary anode material.
5. The tantalum doped titanium dioxide and Li of claim 4 2 SnO 3 The preparation method of the double-layer coated modified ternary cathode material is characterized in that in the step (1), the lithium source is one or more selected from lithium carbonate, lithium hydroxide and lithium oxalate; the additive is selected from Al 2 O 3 、ZrO 2 、Ta 2 O 5 One or more of SrO.
6. The tantalum doped titanium dioxide and Li of claim 4 2 SnO 3 The preparation method of the double-layer coated modified ternary cathode material is characterized in that in the step (2), the tantalum salt is tantalum oxide, tantalum chloride or tantalum oxalate; the titanium salt is titanium sulfate, titanium chloride, titanium oxalate, sodium citrate titanium salt or tetrabutyl titanate.
7. The tantalum doped titanium dioxide and Li of claim 4 2 SnO 3 The preparation method of the double-layer coated modified ternary cathode material is characterized in that in the step (2), the stirring speed is 300rpm-2000rpm, the evaporating temperature is 80-120 ℃, and the drying temperature is 90-150 ℃.
8. The tantalum doped titanium dioxide and Li of claim 4 2 SnO 3 The preparation method of the double-layer coated modified ternary positive electrode material is characterized in that in the step (3), the Li is 2 SnO 3 The preparation process of (2) is as follows:
dissolving lithium salt and tin salt in a molar ratio of (2-3) to 1 in a solvent for hydrothermal synthesis reaction, wherein the reaction temperature is 140-180 ℃ and the reaction time is 10-20 h; collecting reaction products, washing, drying at 60-90 deg.C for 6-12 hr, and grinding to obtain Li 2 SnO 3 。
9. The tantalum doped titanium dioxide and Li of claim 8 2 SnO 3 The preparation method of the double-layer coated modified ternary positive electrode material is characterized in that the lithium salt is lithium carbonate, lithium hydroxide, lithium oxalate or lithium methoxide; the tin salt is tin chloride, tin methane sulfonate or stannate.
10. The tantalum-doped titanium dioxide and Li of any of claims 1-3 2 SnO 3 The double-layer coating modified ternary positive electrode material is applied to preparation of a secondary battery positive electrode plate and a secondary battery.
CN202311415520.4A 2023-10-27 2023-10-27 Tantalum doped titanium dioxide and Li 2 SnO 3 Double-layer coated modified ternary positive electrode material, and preparation method and application thereof Pending CN117457868A (en)

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