CN116040697A - Low-gas-yield long-cycle ternary positive electrode material and preparation method thereof - Google Patents

Low-gas-yield long-cycle ternary positive electrode material and preparation method thereof Download PDF

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CN116040697A
CN116040697A CN202310074052.2A CN202310074052A CN116040697A CN 116040697 A CN116040697 A CN 116040697A CN 202310074052 A CN202310074052 A CN 202310074052A CN 116040697 A CN116040697 A CN 116040697A
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positive electrode
electrode material
ternary
ternary positive
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周涛
李德祥
洪明子
刘平
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Ningxia Zhonghua Lithium Battery Material Co ltd
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Ningxia Zhonghua Lithium Battery Material Co ltd
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Abstract

The invention provides a kind of deviceA method of preparing a ternary positive electrode material, the method comprising the steps of: (1) The Ni salt, co salt, mn salt and M element are sourced from water to carry out coprecipitation reaction under the action of NaOH and ammonia water, thus obtaining ternary positive electrode material precursor Ni x Co y Mn z M (1‑x‑y‑z) (OH) 2 The method comprises the steps of carrying out a first treatment on the surface of the (2) Mixing the ternary cathode material precursor, the Sr source and the lithium salt, and performing primary sintering to obtain a primary sintered material; (3) And coating a W source and one or two selected from an Al source and a Ti source on the surface of the primary sintered material, and performing secondary sintering to obtain the ternary anode material. The doping element M is directly added in the process of preparing the positive electrode material precursor, so that the uniformity of the distribution of the doping element in the material lattice is improved, and the effect of coating and blocking is fully exerted by adopting various coating element materials.

Description

Low-gas-yield long-cycle ternary positive electrode material and preparation method thereof
Technical Field
The invention belongs to the field of lithium ion battery materials, and relates to a low-gas-yield long-cycle ternary positive electrode material and a preparation method thereof.
Background
The ternary positive electrode material has higher specific capacity and lower material cost compared with materials such as lithium cobaltate and the like, and gradually replaces some positive electrode materials which are low in capacity and higher in cost and cannot be widely applied, but the ternary positive electrode material also has a plurality of problems of more side reactions of a battery, gas production bulge, rapid reduction of cycle performance under high voltage and the like in the use process, so that the battery is invalid.
In order to solve the problems, the prior art mainly adopts dry method multi-element doping and cladding at the same time, and the method has the following problems: the mixing uniformity and the internal doping and external adhesion stability of the material can not reach ideal states, the nanoscale coating agent can easily form self aggregation in the material mixing stage, the obtained ternary positive electrode material has large difference, the coating element can not be firmly attached to the surface of a single crystal, the occurrence of side reaction can not be effectively blocked, and the coating agent is easy to fall off, so that a battery manufactured by the positive electrode material is very fast failed.
Disclosure of Invention
Aiming at the problems in the prior art, the doping element M is directly added in the process of preparing the precursor of the positive electrode material, so that the uniformity of the distribution of the doping element M in the material lattice can be improved, the coating element material adopts a core-shell structure and a large particle and small particle matched coating technology, the coating element material with small particles fills gaps of the coating element material with large particles to form a core-shell structure with large particles as cores and small particles as shells, the effect of uniform coating is achieved, and the coating blocking effect is fully exerted.
Specifically, one aspect of the present invention provides a method of preparing a ternary cathode material, the method comprising the steps of:
(1) The Ni salt, co salt, mn salt and M element are sourced from water to carry out coprecipitation reaction under the action of NaOH and ammonia water, thus obtaining ternary positive electrode material precursor Ni x Co y Mn z M (1-x-y-z) (OH) 2 Wherein x is more than or equal to 0.4 and less than or equal to 0.95, y is more than or equal to 0 and less than 0.4, z is more than or equal to 0 and less than 0.4, x+y+z is less than 1, and M is one or more doping elements selected from Zr, ti, mg, B and Ba;
(2) Mixing the ternary cathode material precursor, the Sr source and the lithium salt, and performing primary sintering to obtain a primary sintered material;
(3) And coating a W source on the surface of the primary sintered material to obtain a material coated with the W source, coating one or two of an Al source and a Ti source, and performing secondary sintering to obtain the ternary anode material.
In one or more embodiments, the doping element M comprises Zr, and the source of M element comprises a water-soluble Zr-containing compound, preferably selected from Li 2 ZrF 6 And Zr (HPO) 4 ) 2 ·H 2 One or two of O.
In one or more embodiments, the ternary positive electrode material precursor has the formula Ni x Co y Mn z M (1-x-y-z) (OH) 2 Wherein x is more than or equal to 0.6 and less than or equal to 0.7,0, y is more than or equal to 0.1, z is more than or equal to 0.2 and less than 0.3, and x+y+z is less than or equal to 0.98.
In one or more embodiments, the ternary positive electrode material precursor has a particle size D50 of 2-15 μm.
In one or more embodiments, the ternary positive electrode material precursor has a specific surface area of 5-15cm 2 /g。
In one or more embodiments, the pH of the coprecipitation reaction is 9-12, the reaction temperature is 60-80 ℃, and the reaction time is 5-12 hours.
In one or more embodiments, the Sr source comprises a compound selected from SrCO 3 And one or both of SrO.
In one or more embodiments, the ratio of the amount of the ternary positive electrode material precursor to the amount of the substance of the Sr element in the Sr source is 1 (0.0001-0.001).
In one or more embodiments, the lithium salt includes one or more selected from the group consisting of lithium carbonate, lithium hydroxide, and lithium hydroxide monohydrate.
In one or more embodiments, the ratio of the amount of lithium element in the lithium salt to the amount of material of the ternary positive electrode material precursor is (1.02-1.08): 1.
In one or more embodiments, the ternary positive electrode material precursor, sr source, and lithium salt are mixed using dry mixing or ball milling.
In one or more embodiments, the primary sintering is performed at a soak temperature of 750-980 ℃ for a soak time of 6-12 hours.
In one or more embodiments, the method includes, after one sintering, comminuting the green compact to a D50 particle size of 2-14 μm.
In one or more embodiments, the W source comprises a member selected from W 2 O 3 、WO 2 And (NH) 4 ) 10 W 12 O 41 ～xH 2 One or more of O.
In one or more embodiments, the particle size of the W source is 100-200nm.
In one or more embodiments, the ratio of the amount of the one-shot material to the amount of the substance of the W element in the W source is 1 (0.001-0.01).
In one or more embodiments, the W source is coated onto the surface of the burned material by wet mixing; preferably, the wet mixing comprises: firstly preparing a W source suspension by using a W source, a surfactant, a dispersing agent and water, mixing the primary combustion material and the suspension, filtering and drying to coat the W source on the surface of the primary combustion material, and obtaining a material coated with the W source; wherein the surfactant is preferably cetyl trimethyl ammonium bromide, the dispersing agent is preferably polyethylene glycol-10000, the concentration of the W source in the suspension is preferably 0.5-2g/L, the concentration of the surfactant is preferably 1-2g/L, and the concentration of the dispersing agent is preferably 0.5-1.5g/L.
In one or more embodiments, the average density of W atoms on the surface of the material coating the W source is 1-800 atoms/cm 2 。
In one or more embodiments, the Al source comprises a material selected from the group consisting of Al 2 O 3 、Al(OH) 3 、AlO 9 P 3 And AlPO 4 One or more of the following.
In one or more embodiments, the Al source has a particle size of 30-60nm.
In one or more embodiments, when the cladding element comprises Al, the ratio of the material of the cladding W source to the amount of the material of the Al element in the Al source is 1 (0.001-0.01).
In one or more embodiments, the Ti source comprises a material selected from the group consisting of TiO, tiO 2 And Ti is 2 O 3 One or more of the following.
In one or more embodiments, the Ti source has a particle size of 30-60nm.
In one or more embodiments, when the coating element comprises Ti, the ratio of the material of the coating W source to the amount of material of the Ti element in the Ti source is 1 (0.001-0.01).
In one or more embodiments, one or both selected from the Al source and the Ti source are coated onto the surface of the coated W source material using dry mixing.
In one or more embodiments, the average density of Al atoms or Ti atoms on the surface of the material coated with one or both of the Al source and the Ti source is 100-3000 pieces/cm 2 。
In one or more embodiments, the secondary sintering is performed at a soak temperature of 300-700 ℃ for a soak time of 6-12 hours.
The invention also comprises a ternary positive electrode material prepared by adopting the method of any embodiment of the text.
Another aspect of the present invention provides a ternary positive electrode material that is Sr-doped and is coated with W and Li of one or two elements selected from Al and Ti n Ni x Co y Mn z M (1-x-y-z) O 2 Wherein n is 1.02-1.08,0.4, x is less than or equal to 0.95, y is more than 0 and less than 0.4, z is more than 0 and less than 0.4, x+y+z is less than 1, and M is one or more doping elements selected from Zr, ti, mg, B and Ba.
In one or more embodiments, the doping element M comprises Zr, and the source of M element comprises a water-soluble Zr-containing compound, preferably selected from Li 2 ZrF 6 And Zr (HPO) 4 ) 2 ·H 2 One or two of O.
In one or more embodiments, the doping element M is doped into a precursor of the ternary cathode material.
In one or more embodiments, the Li n Ni x Co y Mn z M (1-x-y-z) O 2 Wherein x is more than or equal to 0.6 and less than or equal to 0.7,0, y is more than or equal to 0.1, z is more than or equal to 0.2 and less than 0.3, and x+y+z is less than or equal to 0.98.
In one or more embodiments, in the ternary positive electrode material, li n Ni x Co y Mn z M (1-x-y-z) O 2 The ratio of the amount of the element(s) to the amount of the element(s) of Sr is 1 (0.0001-0.001).
In one or more embodiments, in the ternary positive electrode material, li n Ni x Co y Mn z M (1-x-y-z) O 2 The ratio of the amount of the substance to the W element is 1 (0.001-0.01).
In one or more embodiments, the ternary positive electrode material has an average density of W atoms on the surface of 1 to 800 atoms/cm 2 。
In one or more embodiments, when the coating element includes Al, li in the ternary positive electrode material n Ni x Co y Mn z M (1-x-y-z) O 2 Amount of substance with Al elementThe ratio is 1 (0.001-0.01).
In one or more embodiments, when the coating element comprises Ti, li in the ternary positive electrode material n Ni x Co y Mn z M (1-x-y-z) O 2 The ratio of the amount of the Ti element to the amount of the substance is 1 (0.001-0.01).
In one or more embodiments, the ternary positive electrode material has an average density of Al or Ti atoms of 100 to 3000 atoms/cm 2 。
The ternary positive electrode material can be prepared by adopting the method described in any embodiment of the text.
Another aspect of the invention provides a positive electrode sheet comprising a ternary positive electrode material as described in any of the embodiments herein.
Another aspect of the invention provides a lithium ion battery comprising the positive electrode sheet of any of the embodiments described herein.
Drawings
FIG. 1 is a schematic diagram of a sintered material coated with a W source, an Al source and a Ti source according to the present invention. In fig. 1, 1 is a burned material, 2 is a W source, 3 is an Al source, and 4 is a Ti source.
Fig. 2 is a Scanning Electron Microscope (SEM) image of the positive electrode material prepared in example 1 of the present invention.
Fig. 3 is an SEM image of the positive electrode material prepared in example 2 of the present invention.
Fig. 4 is an SEM image of the positive electrode material prepared in comparative example 1 of the present invention.
Fig. 5 is a graph showing the cycle capacity retention rate at 2.8 to 4.25V of lithium secondary batteries using the positive electrode materials prepared in example 1, example 2 and comparative example 1 according to the present invention.
Detailed Description
So that those skilled in the art can appreciate the features and effects of the present invention, a general description and definition of the terms and expressions set forth in the specification and claims follows. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs, and in the event of a conflict, the present specification shall control.
The theory or mechanism described and disclosed herein, whether right or wrong, is not meant to limit the scope of the invention in any way, i.e., the present disclosure may be practiced without limitation to any particular theory or mechanism.
Herein, "comprising," "including," "containing," and similar terms are intended to cover the meaning of "consisting essentially of … …" and "consisting of … …," e.g., "a consisting essentially of B and C" and "a consisting of B and C" should be considered to have been disclosed herein when "a comprises B and C" is disclosed herein.
In this document, all features such as values, amounts, and concentrations that are defined as ranges of values or percentages are for brevity and convenience only. Accordingly, the description of a numerical range or percentage range should be considered to cover and specifically disclose all possible sub-ranges and individual values (including integers and fractions) within the range.
Herein, unless otherwise specified, percentages refer to mass percentages, and proportions refer to mass ratios.
Herein, when embodiments or examples are described, it should be understood that they are not intended to limit the invention to these embodiments or examples. On the contrary, all alternatives, modifications, and equivalents of the methods and materials described herein are intended to be included within the scope of the invention as defined by the appended claims.
In this context, not all possible combinations of the individual technical features in the individual embodiments or examples are described in order to simplify the description. Accordingly, as long as there is no contradiction between the combinations of these technical features, any combination of the technical features in the respective embodiments or examples is possible, and all possible combinations should be considered as being within the scope of the present specification.
The method adopts a multi-way method to carry out element doping, so that a stable internal lattice structure of the ternary positive electrode material is formed, and the cycle stability of the ternary positive electrode material under high voltage is improved; the electrolyte and the electrolyte are achieved by using a multi-layer element coating meansThe surface of the ternary positive electrode material is effectively blocked, the side reaction of the electrolyte and the material surface substances is reduced, and the gas production is reduced. The invention can effectively improve the LiNi x Co y Mn z O 2 (x is more than or equal to 0.4 and less than or equal to 0.95, y is more than or equal to 0 and less than 0.4, z is more than or equal to 0 and less than 0.4, and x+y+z=1) the gas production performance and the circulation stability performance under high voltage of the ternary positive electrode material are improved, so that the use performance of the ternary single crystal positive electrode material is improved integrally, and the ternary single crystal positive electrode material has wide application fields.
Ternary positive electrode material precursor
The chemical formula of the ternary positive electrode material precursor of the invention is Ni x Co y Mn z M (1-x-y-z) (OH) 2 Wherein x is more than or equal to 0.4 and less than or equal to 0.95, y is more than or equal to 0 and less than 0.4, z is more than or equal to 0 and less than 0.4, x+y+z is less than 1, and M is a doping element. In some embodiments, formula Ni x Co y Mn z M (1-x-y-z) (OH) 2 In which 0.9.ltoreq.x+y+z < 1, for example x+y+z may be 0.92, 0.94, 0.96, 0.98. Chemical Ni x Co y Mn z M (1-x-y-z) (OH) 2 Where x may be 0.5, 0.6, 0.63, 0.65, 0.7, 0.8, 0.9, y may be 0.02, 0.04, 0.06, 0.08, 0.1, 0.2, and z may be 0.1, 0.2, 0.24, 0.26, 0.28, 0.3. In some embodiments, formula Ni x Co y Mn z M (1-x-y-z) (OH) 2 Wherein x is more than or equal to 0.6 and less than or equal to 0.7,0, y is more than or equal to 0.1, z is more than or equal to 0.2 and less than 0.3, and x+y+z is less than or equal to 0.98.
The doping element M suitable for the present invention may be selected from one or more of Zr, ti, mg, B, ba and the like. In some embodiments, the doping element M is Zr. The M element plays a role in stabilizing the structure of the material in the positive electrode material.
In some embodiments, the ternary positive electrode material precursor of the present invention has the chemical formula Ni x Co y Mn z Zr (1-x-y-z) (OH) 2 Wherein 0.4.ltoreq.x.ltoreq.0.95, 0 < y < 0.4,0 < z < 0.4, x+y+z < 1, the chemical formula of the ternary positive electrode material precursor may be Ni 0.63 Co 0.06 Mn 0.26 Zr 0.05 (OH) 2 。
The particle size D50 of the ternary positive electrode material precursor of the present invention may be 2-10 microns, e.g., 4 microns, 4.5 microns, 5 microns, 6 microns, 8 microns.
The specific surface area of the ternary positive electrode material precursor of the invention can be 5-15cm 2 /g, e.g. 8cm 2 /g、10cm 2 /g、11cm 2 /g、12cm 2 /g、12.5cm 2 /g、13cm 2 /g、14cm 2 /g。
According to the invention, the M element is added in the precursor preparation process, so that the M element is ensured to be uniformly distributed in the material, and the effect on stabilizing the structure is greater than the effect of adding the M element in the dry mixed material after the precursor preparation is completed.
The ternary positive electrode material precursor is prepared by the following method: the Ni salt, co salt, mn salt and M element source are subjected to coprecipitation reaction in water under the action of NaOH and ammonia water, and ternary positive electrode material precursor Ni is obtained x Co y Mn z M (1-x-y-z) (OH) 2 。
The Ni, co, mn salts suitable for use in the present invention may be water soluble salts of Ni, co, mn, such as sulphates.
In the present invention, the M element source means a substance for introducing M element into the precursor. The M element source suitable for the present invention may be a water-soluble M-containing compound including, but not limited to, a water-soluble Zr-containing compound, a water-soluble Ti-containing compound, a water-soluble Mg-containing compound, a water-soluble B-containing compound, a water-soluble Ba-containing compound, and the like. Examples of the water-soluble Zr-containing compound include Li 2 ZrF 6 、Zr(HPO 4 ) 2 ·H 2 O. Examples of the water-soluble Ti-containing compound include Li 2 TiF 6 。
The pH of the coprecipitation reaction system is preferably 9 to 12, for example 9.5, 10, 11, the reaction temperature is preferably 60 to 80 ℃, for example 65 ℃, 70 ℃, 75 ℃, and the reaction time can be 5 to 12 hours, for example 8 hours, 10 hours.
The dosage ratio of Ni salt, co salt, mn salt, M element source and NaOH can be determined according to the chemical formula of the ternary positive electrode material precursor.
In some embodiments, a mixed solution of nickel salt, cobalt salt, manganese salt is mixedControlling pH and temperature of a system, performing coprecipitation reaction, filtering, washing and drying to obtain ternary positive electrode material precursor Ni x Co y Mn z M (1-x-y-z) (OH) 2 . In the present invention, unless otherwise specified, the solvent of the solution or suspension is water.
Ternary positive electrode material
The ternary positive electrode material is prepared by mixing the ternary positive electrode material precursor, a Sr source and lithium salt, coating a W source and one or two selected from an Al source and a Ti source after primary sintering, and performing secondary sintering. The ternary positive electrode material is Li doped with Sr and coated with W and one or two elements selected from Al and Ti n Ni x Co y Mn z M (1-x-y-z) O 2 Wherein n is 1.02-1.08,0.4, x is less than or equal to 0.95, y is more than 0 and less than 0.4, z is more than 0 and less than 0.4, x+y+z is less than 1, and M is one or more doping elements selected from Zr, ti, mg, B and Ba. In some embodiments, li n Ni x Co y Mn z M (1-x-y-z) O 2 Wherein x is more than or equal to 0.6 and less than or equal to 0.7,0, y is more than or equal to 0.1, z is more than or equal to 0.2 and less than 0.3, and x+y+z is less than or equal to 0.98.
In the present invention, the Sr source refers to a substance for doping Sr element into the positive electrode material. The Sr source suitable for the present invention may be a Sr-containing compound including, but not limited to, srCO 3 、SrO。
In the present invention, the ratio of the amount of the ternary positive electrode material precursor to the amount of the substance of the Sr element in the Sr source may be 1 (0.0001-0.001), for example, 1:0.0002, 1:0.0004, 1:0.0005, 1:0.0006, 1:0.0008.
Lithium salts suitable for use in the present invention are conventional in the art and may be, for example, lithium carbonate, lithium hydroxide monohydrate.
In the present invention, the ratio of the amount of lithium element in the lithium salt to the amount of the substance of the ternary positive electrode material precursor may be (1.02 to 1.08): 1, for example, 1.04:1, 1.06:1.
In the invention, the ternary cathode material precursor, the Sr source and the lithium salt can be mixed in a dry mixing or ball milling mixing mode. In the present invention, dry mixing means stirring and mixing under the condition that no solvent is added. In the mixing, the dry mixing process may be carried out by first mixing at 200-1000rpm, for example 500rpm, for 2-10min, for example 5min, and then mixing at 2000-5000rpm for 10-30min, for example 20min. The ball milling parameter can be 1 ball to 2 balls with a mass ratio of 5:1-10:1, the rotating speed is 500-800rpm, the forward rotation is 4-6min, such as 5min, the reverse rotation is 4-6min, such as 5min, and the ball milling time is 2-4h.
After uniformly mixing the ternary positive electrode material precursor, the Sr source and the lithium salt, the ternary positive electrode material precursor, the Sr source and the lithium salt can be sintered in air, oxygen or mixed gas of air and oxygen for one time. When the mixed gas is used, the volume fraction of the oxygen can be 40% -95%. The temperature of the primary sintering may be 750-980 ℃, such as 800 ℃, 850 ℃, 900 ℃, 950 ℃, and the temperature of the primary sintering may be 6-12 hours, such as 8 hours, 10 hours.
The ternary positive electrode material precursor, the Sr source, and the sintered product of lithium salt (hereinafter referred to as a primary combustion material) may be pulverized to control the particle diameter D50 to 2 to 10 micrometers, for example, 4 micrometers, 4.5 micrometers, 5 micrometers, 6 micrometers, 8 micrometers. Crushing can be performed by adopting a roller mill and a colloid mill.
In the present invention, the W source is a substance for coating the surface of the positive electrode material with W element. W sources suitable for use in the present invention may be W-containing compounds including, but not limited to W 2 O 3 、WO 2 、(NH 4 ) 10 W 12 O 41 ～xH 2 O, etc. The particle size D50 of the W source is preferably 100-200nm, for example 150nm.
In the present invention, the ratio of the amount of a burned material to the amount of W element in the W source may be 1 (0.001-0.01), such as 1:0.0015, 1:0.002, 1:0.003, 1:0.005.
Preferably, a wet mixing mode is adopted to mix a burned material and a W source, the W source, a surfactant, a dispersing agent and water are firstly prepared into a stable W source suspension, then the burned material and the suspension are mixed, and the material for coating the W source is obtained through filtering and drying, so that the coating of the W source on the burned material is realized. The radius of the W atoms is large, and the coating effect by adopting the dry coating is not uniform by adopting the wet coating, so that a wet coating mode is preferable.
The surfactant is preferably cetyltrimethylammonium bromide. The dispersing agent is preferably polyethylene glycol-10000. The concentration of the W source in the suspension may be 0.5-2g/L, e.g. 0.6g/L, 0.8g/L, 1g/L; the concentration of the surfactant can be 1-2g/L; the concentration of the dispersant may be from 0.5 to 1.5g/L, for example 0.6g/L, 0.8g/L, 1g/L. When preparing the suspension, it is preferable to dissolve the surfactant and the dispersant in water, then add the W source, and stir at 100 to 400rpm for 8 to 16 hours, for example, 12 hours, for example, it is possible to stir at 100 to 200rpm, for example, 150rpm for 2 to 6 hours, for example, 4 hours, and then disperse at 200 to 400rpm, for example, 250rpm for 6 to 10 hours, for example, 8 hours, to obtain a uniformly dispersed suspension. When mixing the burned material and the suspension, it is preferable to add the burned material to the suspension, stir it at 100 to 200rpm, for example 150rpm, for 0.5 to 2 hours, for example 1.5 hours, and then filter and dry the mixture to complete the coating.
In the invention, the average density of W atoms on the surface of the material coated with the W source is preferably 1-800/cm 2 For example 10/cm 2 50 pieces/cm 2 100 pieces/cm 2 200 pieces/cm 2 500 pieces/cm 2 . In some embodiments, the average density of W atoms on the surface of the material coating the W source is 100-200 atoms/cm 2 For example 140-160 pieces/cm 2 。
In the present invention, the W source and one or more selected from the Al source and the Ti source may be coated on the surface of the positive electrode material simultaneously or in a distributed manner, but it is preferable that the W source is coated on the surface of the positive electrode material first and then the one or more selected from the Al source and the Ti source is coated on the surface of the positive electrode material, and it is preferable that the W source is coated by wet coating and the Al source and the Ti source are coated by dry mixing.
In the present invention, the Al source is a substance for coating the surface of the positive electrode material with Al element. Al sources suitable for use in the present invention may be Al-containing compounds including, but not limited to, al 2 O 3 、Al(OH) 3 、AlO 9 P 3 、AlPO 4 Etc. The particle diameter D50 of the Al source is preferably 30 to 60nm, for example 45nm.
In the present invention, the ratio of the amount of a burned material to the amount of the Al element in the Al source may be 1 (0.001-0.01), for example, 1:0.002, 1:0.003, 1:0.004, 1:0.005.
In the present invention, the Ti source is a substance for coating the surface of the positive electrode material with Ti element. Ti sources suitable for use in the present invention may be Ti-containing compounds including, but not limited to, tiO 2 、Ti 2 O 3 Etc. The particle diameter D50 of the Ti source is preferably 30 to 60nm, for example 45nm.
In the present invention, the ratio of the amount of a burned material to the amount of Ti element in the Ti source may be 1 (0.001-0.01), for example, 1:0.002, 1:0.004, 1:0.005, 1:0.006.
In the present invention, the Al source and the Ti source may be coated only with the Al source or may be coated with both the Al source and the Ti source. Coating is performed using both an Al source and a Ti source, and coating of the Al source and coating of the Ti source are preferably performed simultaneously.
In the present invention, the coating of the Al source and the Ti source may be performed by dry mixing. The coating may be carried out by mixing at 200-1000rpm, for example 500rpm, for 2-10min, for example 5min, and then mixing at 2000-5000rpm, for example 3000rpm, for 5-20min, for example 10min.
In the invention, the average density of Al atoms or Ti atoms on the surface of the material coated with the Al source or the Ti source is preferably 100-3000/cm 2 For example 200/cm 2 500 pieces/cm 2 1000 pieces/cm 2 1500 pieces/cm 2 2000 pieces/cm 2 . In some embodiments, the average density of Al atoms or Ti atoms on the surface of the Al source or Ti source-coated material is 500-1500 atoms/cm 2 For example 800-1200 pieces/cm 2 。
And coating a W source and one or two selected from an Al source and a Ti source on the surface of the primary sintered material, and performing secondary sintering to obtain the ternary anode material. The secondary sintering may be performed in air, oxygen or a mixture of air and oxygen. When the mixed gas is used, the volume fraction of the oxygen can be 40% -95%. The temperature of the secondary sintering can be 300-700 ℃, such as 400 ℃, 500 ℃, 600 ℃, and the temperature of the secondary sintering can be 6-12h, such as 8h and 10h.
In some embodiments, the method of preparing a ternary positive electrode material of the present invention comprises the steps of:
(a) Adopting a dry mixing mode to lead ternary positive electrode material precursor Ni x Co y Mn z M (1-x-y-z) (OH) 2 Mixing lithium salt and Sr source uniformly, sintering for one time, and crushing to obtain a sintered material;
(b) Preparing a W source into a suspension with uniform dispersion, adding the crushed primary combustion material into the suspension, uniformly stirring to uniformly coat the W source on the surface of the primary combustion material, and filtering and drying to obtain a coated material A;
(c) Coating one or two of an Al source and a Ti source on the coating material A in a dry mixing mode to obtain a coating material B;
(d) And (3) carrying out secondary sintering on the coating material B to obtain the ternary anode material.
Lithium ion battery
The lithium ion battery comprises a positive pole piece, a negative pole piece, a diaphragm and electrolyte. The positive electrode plate of the lithium ion battery comprises the ternary positive electrode material. And laminating the positive pole piece, the negative pole piece and the diaphragm according to design requirements (such as Z-shaped lamination or winding lamination), injecting electrolyte, aging, pumping air and heat-sealing to prepare the lithium ion battery.
The positive electrode sheet includes a positive electrode collector and a positive electrode material layer formed on a surface of the positive electrode collector. The positive electrode material layer includes a positive electrode material, a conductive agent, and a binder. The positive electrode material layer is obtained by coating positive electrode slurry containing positive electrode material, conductive agent, binder and solvent on a positive electrode current collector, rolling, die cutting and drying. The solvent of the positive electrode slurry may be N-methyl-2-pyrrolidone (NMP). The positive electrode current collector may be copper foil, aluminum foil, titanium foil, nickel foil, iron foil, zinc foil, or the like. The positive electrode material comprises one or more selected from lithium iron phosphate, binary positive electrode material, ternary positive electrode material, quaternary positive electrode material and the like. Preferably, the positive electrode material is a ternary positive electrode material of the present invention. The conductive agent of the positive electrode may be one or more selected from conductive carbon black, carbon fiber, acetylene black, conductive graphite, graphene, carbon nanotube and carbon microsphere. The binder of the positive electrode may be one or more selected from polyvinylidene fluoride (PVDF), polytetrafluoroethylene, polyvinyl alcohol, polyolefin, styrene-butadiene rubber, fluorinated rubber, polyurethane, and sodium alginate. In some embodiments, the conductive agent in the positive electrode material layer is carbon black and carbon nanotubes, and the binder is PVDF. The content ratio of each component in the positive electrode material layer may be conventional, for example, the mass fraction of the positive electrode material may be 90% -98%, for example 92%, 94%, 96%, 97%, the mass fraction of the conductive agent may be 1% -5%, for example 1.5%, 2%, 3%, 3.5%, 4%, and the mass fraction of the binder may be 1% -5%, for example 1.5%, 2%, 2.5%, 3%, 4%.
The negative electrode plate comprises a negative electrode current collector and a negative electrode material layer arranged on the surface of the negative electrode current collector. The negative electrode current collector may be copper foil. The anode material layer includes an anode material, a conductive agent, and a binder. The negative electrode material layer is prepared by coating a negative electrode slurry containing a negative electrode material, a conductive agent, a binder and a solvent on a negative electrode current collector, and then rolling, die-cutting and drying. The solvent of the anode slurry may be water. The negative electrode material may be lithiated TiO of spinel structure selected from carbon powder, graphite, lithium metal, mesophase carbon spheres, hard carbon, soft carbon, silicon-carbon composite, li-Sn alloy, li-Sn-O alloy 2 -Li 4 Ti 5 O 12 And one or more of Li-Al alloys. The negative electrode conductive agent may be one or more selected from conductive carbon black (SP), acetylene black, carbon nanotubes, carbon nanowires, carbon microspheres, carbon fibers, and graphene. The negative electrode binder may be one or more selected from polyvinylidene fluoride, polytetrafluoroethylene, acrylonitrile copolymer, polybutyl acrylate, polyacrylonitrile, and Styrene Butadiene Rubber (SBR). The anode material layer and the anode slurry may further contain a thickener such as carboxymethyl cellulose (CMC). In some embodiments, the negative electrode material in the negative electrode material layer is carbon powder, the conductive agent is conductive carbon black, the binder is styrene-butadiene rubber, and the thickener is carboxymethyl cellulose. The mass ratio of each component in the anode material layer can be conventional, for example, the mass fraction of the anode material can be 90% -98%, such as 93%, 95%, 96%, 97%, and the lead The mass fraction of the electrical agent may be 0.5% -5%, e.g. 1%, 1.5%, 2%, the mass fraction of the binder may be 0.5% -5%, e.g. 1%, 1.5%, 2%, 2.5%, 3%, and the mass fraction of the thickener may be 0-5%, e.g. 1%, 1.5%, 1.8%, 2%, 3%.
The membrane may be a polymer membrane, a ceramic membrane or a polymer/ceramic composite membrane. The polymer separator includes a single layer polymer separator and a multi-layer polymer separator. The single layer polymer separator includes a Polyethylene (PE) separator and a polypropylene (PP) separator. The composite polymer separator includes a polyethylene and polystyrene hybrid separator.
The electrolyte may be a nonaqueous electrolyte comprising an organic solvent and a lithium salt. The organic solvent may be a carbonate-based solvent commonly used in the art for electrolytes, including, but not limited to, one or more, preferably two or more selected from the group consisting of Ethylene Carbonate (EC), propylene Carbonate (PC), butylene carbonate, γ -butyrolactone, dimethyl carbonate (DMC), diethyl carbonate (DEC), and ethylmethyl carbonate (EMC). Preferably, the carbonate-based solvent comprises at least one cyclic carbonate and at least one chain carbonate. Examples of the cyclic carbonates include ethylene carbonate, propylene carbonate, butylene carbonate and γ -butyrolactone. Examples of the chain carbonates include dimethyl carbonate, diethyl carbonate and methylethyl carbonate. The volume ratio of cyclic carbonate to chain carbonate may be 1:4 to 2:3, e.g. 2:7, 1:3, 3:7, 1:2. The lithium salt may be a lithium salt commonly used in the art including, but not limited to, lithium bis (trifluoromethanesulfonyl) imide (LiTFSI), lithium bis (pentafluoroethylsulfonyl) imide (LiFSI), lithium bis (oxalato) borate (LiBOB), lithium acetate, lithium trifluoroacetate, lithium fluoroalkylphosphate, lithium hexafluorophosphate (LiPF) 6 ) Lithium difluorooxalato borate (LiODFB), lithium tetrafluoroborate (LiBF) 4 ) Lithium perchlorate, lithium hexafluoroarsenate, lithium fluoride, and the like. In some embodiments, the lithium salt is LiPF 6 . The concentration of the lithium salt in the electrolyte may be 0.5 to 2mol/L, for example 1mol/L, 1.5mol/L.
The invention has the following beneficial effects:
1. the doping element M of the ternary positive electrode material is directly added when preparing the ternary positive electrode material precursor, and the doping element M is distributed more uniformly in the material, so that the effect of better synergistically stabilizing the material structure is achieved;
2. the doping agent Sr source is added when materials are mixed before primary sintering, so that the reaction temperature of material sintering can be reduced, the materials can fully react, the formation of a lattice structure is facilitated, the ternary positive electrode material with a firm layered structure is obtained, lattice collapse in the material reaction process is reduced, a lithium ion transmission channel is improved, the inherent internal resistance of the material is reduced, and the long-acting cycle performance of the material under high voltage is improved;
3. the W source with larger atomic radius is coated on the surface of a burning material in a suspension manner, so that the uniformity of the coating material is improved, and the coating effect is improved;
4. as shown in fig. 1, an Al source and a Ti source with smaller atomic radius are coated on the outermost layer in a dry coating mode, so that the effect of filling gaps of particles (W source) of an inner coating layer is achieved, secondary coating can be formed on the surface of the inner coating layer (the surface of the W source), side reactions of electrolyte in direct contact with a material are effectively blocked, and the gas production performance of the material is improved;
5. The firm inner layer material structure and the reduction of side reaction of the outer layer coating layer play a role in synergy of the inner layer material and the outer layer material, and the high-voltage cycle performance and the high-temperature gas production performance of the material are improved;
6. the preparation method of the invention can also be applied to the preparation of ternary anode materials with similar components, and has wide application range;
7. the doping element M plays a good role in stabilizing the material structure of the ternary positive electrode material and improving the material circulation performance, so that the element M is preferably added in the preparation of the precursor, the uniformity of the doping element M in the precursor nucleation process is improved, the uniform distribution in the material can be ensured, the uniformity of the internal stress of the material is facilitated, and the better supporting effect on the exertion of the positive electrode material circulation performance is achieved;
8. the Sr source has the function of reducing the sintering reaction temperature, is added in the mixing process of the precursor and the lithium salt, is uniformly distributed on the surface of the material, plays a good role in reducing the reaction activation energy, and can effectively reduce the optimal sintering temperature of the material by 5-20 ℃ due to the addition of the doping element Sr, thereby being beneficial to reducing the single ton energy consumption of the product;
9. the coating material adopts a mode of using the materials with large particle size and small particle size simultaneously, and small particles can effectively fill gaps of the large particles and surfaces of the large particles to form a compact coating layer, so that side reactions of electrolyte and the materials are reduced;
10. The W source has good capacity improving effect, has certain activity relative to the Al source and the Ti source, and is easy to generate side reaction with a battery system, so the invention preferably coats the W source on the innermost layer of the material firstly, then coats the Al source and the Ti source on the surfaces of the material and the W source, plays a role in avoiding side reaction on the surfaces of the material and the W source, and increases the circulation stability of the product;
11. the coating material adopts a mode of water phase coating and solid phase coating to cooperatively coat, so that the coating uniformity of the coating material on the surface of the material is improved.
The invention will be illustrated by way of specific examples. It should be understood that these examples are illustrative only and are not intended to limit the scope of the invention. The methods, reagents and materials used in the examples are those conventional in the art unless otherwise indicated. The starting compounds in the examples are all commercially available.
Example 1
The present example prepares a ternary positive electrode material:
(1) Synthesizing a precursor of the positive electrode material by adopting a coprecipitation method: mixing 2mol/L of nickel sulfate, cobalt sulfate and manganese sulfate mixed solution (the molar ratio of nickel, cobalt and manganese elements is 65:7:28, and the valence of the elements is +2), 2mol/L of NaOH solution, 3mol/L of ammonia water solution and 0.05mol/L of Li 2 ZrF 6 Adding the solution into a reactor together, controlling the pH value of a solution system to be 9.5, and heating in a water bath to be kept at 65 ℃; after 10 hours of reaction, the mixture was filtered, washed and dried in vacuo to give a composition (Ni) 0.63 Co 0.06 Mn 0.26 Zr 0.05 )(OH) 2 The precursor of (C) has a particle diameter D50 of about 4.5 μm and a specific surface area of about 12.5cm 2 /g。
(2) 500g of the precursor of step (1), 238.9g of lithium hydroxide monohydrate and 0.4212gSr are weighed 2 CO 3 Pouring into a high-speed mixer, mixing at 500rpm for 5min, mixing at 3000rpm for 20min, transferring into a sagger, programming in oxygen atmosphere to 950 ℃, maintaining the temperature for 12h, and cooling to room temperature.
(3) Taking out the first-fired material in the step (2), using a twin-roll machine to carry out twin-roll, and using a colloid mill to carry out fine crushing, wherein the particle size D50 is controlled to be 4.5 microns.
(4) Adding 1.5L deionized water into a water washing tank, adding 1.5g cetyl trimethyl ammonium bromide and 1.2g polyethylene glycol-10000, stirring thoroughly, adding 1.26. 1.26g W 2 O 3 (particle size D50=150nm), stirring and dispersing for 4 hours at 150rpm, dispersing for 8 hours at 250rpm, to obtain uniformly dispersed W 2 O 3 And (3) suspending liquid.
(5) 400g of the finely crushed primary burned material in the step (3) is weighed and added into the suspension evenly dispersed in the step (4), and primary coating is carried out: stirring at 150rpm for 1 hr, filtering, drying, and sieving to obtain coated material A with average density of 147/cm 2 。
(6) 350g of the coating material A from step (5) and 0.99g of Al are weighed out 2 O 3 (particle size d50=45 nm), poured into a high-speed mixer, and subjected to secondary coating: mixing at 500rpm for 5min, and mixing at 3000rpm for 10min to obtain coated material B with average density of Al atoms coated on the surface of material B of 1138/cm 2 。
(7) Transferring the coating material B in the step (6) into a sagger, programming to 450 ℃ in an oxygen atmosphere, preserving heat for 10 hours, cooling to room temperature, crushing and sieving to obtain a finished ternary positive electrode material, wherein the morphology of the ternary positive electrode material is shown in figure 2.
Example 2
This example prepared a ternary positive electrode material according to the method of example 1, except that: in step (6), 350g of the coating material A in step (5) and 0.99g of Al are added into a high-speed mixer 2 O 3 In addition to, add0.876g of TiO 2 (particle diameter D50=45 nm), performing secondary coating, and testing and analyzing the average density of W, al and Ti atoms coated on the surface of the coating material to be 153 atoms/cm 2 1185 pieces/cm 2 874/cm 2 The morphology of the finally obtained ternary positive electrode material is shown in figure 3.
Comparative example 1
This comparative example prepares a ternary positive electrode material:
(1) Synthesizing a precursor of the positive electrode material by adopting a coprecipitation method: adding 2mol/L of nickel sulfate, mixed solution of cobalt sulfate and manganese sulfate (the molar ratio of nickel, cobalt and manganese elements is 65:7:28, and the valence of the elements is +2), 2mol/L of NaOH solution and 3mol/L of ammonia water solution into a reactor together, controlling the pH value of a solution system to be 9.5, and heating in a water bath to be kept at 65 ℃; after 10 hours of reaction, the mixture was filtered, washed and dried in vacuo to give a composition (Ni) 0.65 Co 0.07 Mn 0.28 )(OH) 2 The precursor of (C) has a particle diameter D50 of about 4.5 μm and a specific surface area of about 12.5cm 2 /g。
(2) 500g of the precursor of step (1), 238.9g of lithium hydroxide monohydrate, 1.35g of zirconia and 0.4212g of Sr are weighed 2 CO 3 Pouring into a high-speed mixer, mixing at 500rpm for 5min, mixing at 3000rpm for 20min, transferring into a sagger, programming in oxygen atmosphere to 950 ℃, maintaining the temperature for 12h, and cooling to room temperature.
(3) Taking out the first-fired material in the step (2), using a twin-roll machine to carry out twin-roll, and using a colloid mill to carry out fine crushing, wherein the particle size D50 is controlled to be 4.5 microns.
(4) Weighing 350g of finely crushed primary combustion material obtained in the step (3) and 0.99g of Al 2 O 3 (particle size d50=45 nm) and 0.876g of TiO 2 (particle size d50=45 nm), poured into a high-speed mixer, and coated: mixing at 500rpm for 5min, and mixing at 3000rpm for 10min to obtain coating material C.
(5) Transferring the coating material C in the step (6) into a sagger, programming to 450 ℃ in an oxygen atmosphere, preserving heat for 10 hours, cooling to room temperature, crushing and sieving to obtain a finished ternary positive electrode material, wherein the morphology of the ternary positive electrode material is shown in figure 4.
Comparative example 2
This comparative example a ternary positive electrode material was prepared according to the method of comparative example 1, except that: in the step (4), 350g of finely crushed primary combustion material in the step (3) and 0.99g of Al are added into a high-speed mixer 2 O 3 And 0.876g of TiO 2 In addition, 1.1g of W was added 2 O 3 (particle size d50=150 nm) and secondary coating was performed. The morphology of the final positive electrode material is shown in figure 3.
The preparation and test of the pouch cell of comparative example 2 were exactly the same as comparative example 1, and the cell performance is shown in fig. 5 and table 1.
In the invention, the average density of the surface coating atoms of the ternary positive electrode material is obtained by testing and calculating according to the following method:
(1) Ternary cathode material specific surface area test
A standard sample 2#1g (1.93 m was weighed 2 /g) (accurate to 0.0001 g) and 5g (accurate to 0.0001 g) of the sample was weighed. A3H-2000 BET specific surface area tester was used. Ensuring the smooth air flow in the pipeline. When the measurement is carried out, the peak area of the sample is basically consistent with the peak area of the standard sample, the steel cylinder main valve is opened, the pressure reducing valve output valve is slowly opened, the output pressure of the valve is regulated to be 0.4MPa, the heating furnace is sleeved on the sample tube, the heating furnace is connected with an instrument, the temperature is regulated to be 150 ℃, and the heating time is 30min. And after the purging is finished, closing a purging power supply and a total power supply, removing the heating furnace, weighing the mass again, calculating the mass m of the sample at the moment, and installing the sample tube.
Checking the inlet and outlet air flow meter at 60-100mL/min, the main checking signal at 0-600, the voltage at 11-13V and the current at 90-110mA. Liquid nitrogen is added into each liquid nitrogen cup to a position 2/3 of the depth of the cup, the liquid nitrogen cups are respectively placed on cup holders, the liquid nitrogen is poured into a cold trap thermostatic cup to a depth of 2-5cm, and a side drawing plate of an instrument is placed. Selecting a 3H-2000BET reference method specific surface test system to test, hearing a 'drop' to indicate that communication is normal, and clicking a storage setting file name and a storage position; the sample name, number of samples and mass m are entered and saved (typically the first pass is a standard sample). After the full-automatic start of the point, the instrument enters an analysis stage, a buzzer sounds, and the test is finished to obtain a ternary anode Specific surface area of material X (m 2 /g)。
(2) Ternary positive electrode material element content test
Weighing 0.5g of sample (accurate to 0.0001 g) into a Teflon beaker, adding 4mL of hydrochloric acid, placing on a constant-temperature heating plate, digesting until the sample is completely dissolved at 200 ℃, adding a small amount of water to clean the wall of the cup, digesting until the sample is nearly dry, completely transferring the sample into a 100mL volumetric flask, and fixing the volume to a scale with water. The content Y (g/g) of each element in the sample was measured using an inductively coupled plasma atomic emission spectrometry/plasma emission spectrometer.
(3) Average density calculation of surface cladding atoms of ternary positive electrode material
The average density of atoms is calculated according to the following formula
Figure BDA0004065661100000181
Wherein: ρ: average density of cladding atoms (units/cm) on ternary material surface 2 )；
Y: the ternary material coating element mass percent (%, g/g);
z: the ternary material coats the atomic number of the element in the element molecule;
x: ternary material specific surface area (m 2 /g)；
M: the ternary material coats the amount of elemental species (g/mol).
Test case
The ternary cathode materials of examples 1-2 and comparative examples 1-2 were fabricated into 3.2Ah soft pack batteries according to the following lithium secondary battery fabrication process, and battery test performances were performed according to the following test methods, and the results are shown in fig. 5 and table 1.
The manufacturing process of the lithium secondary battery comprises the following steps:
(1) Preparation of the Positive electrode
To N-methyl-2-pyrrolidone (NMP) as a solvent were added 97% by weight of a ternary positive electrode material, 1% by weight of carbon black as a conductive agent, 1.5% by weight of polyvinylidene fluoride (PVDF) as a binder, and 0.5% by weight of a conductive-enhancing agentCarbon Nanotubes (CNT) with properties were prepared as a positive electrode mixture slurry with a solids content of 68%. Then the positive electrode mixture slurry is coated on an aluminum film with the thickness of 20 micrometers serving as a positive electrode current collector, so as to ensure that the coating surface density is 380g/m on both sides 2 And drying and rolling to obtain the positive electrode.
(2) Preparation of negative electrode
To NMP as a solvent, carbon powder as 95% by weight of a negative electrode active material, 1.0% by weight of conductive carbon black super-p as a conductive material, and 2.5% by weight of styrene-butadiene rubber (SBR) and 1.5% by weight of carboxymethyl cellulose (CMC) as a pre-mixed binder were added to prepare a negative electrode active material slurry having a solid content of 48%. Then the anode active material slurry is coated on a copper film with the thickness of 10 micrometers serving as an anode current collector, and the coating surface density is ensured to be 220g/m on both sides 2 And drying and rolling to obtain the cathode.
(3) Preparation of non-aqueous electrolyte
The volume ratio of the water to the water is 30:70 and diethyl carbonate to prepare 1M LiPF6 nonaqueous electrolyte.
(4) Preparation of lithium secondary battery
And placing a polyethylene and polypropylene mixed diaphragm between the positive electrode and the negative electrode, winding, injecting a non-aqueous electrolyte, aging, pumping air, and performing heat sealing to prepare the lithium secondary battery.
The battery performance test method comprises the following steps:
(1) Charge-discharge capacity and cycle characteristics
After charging the fabricated lithium secondary battery at 4.25V at 0.2C under constant current/constant voltage (CC/CV) conditions at 25 ℃, discharging to 2.8V at 0.33C under Constant Current (CC) conditions, and measuring the capacity; the lithium secondary battery thus produced was charged at 25℃with 4.25V and 1.0C, and discharged at 1.0C to 2.8V, and the cycle was repeatedly repeated for 1 to 1500 weeks, whereby the relative capacity retention rate at the 1500 th cycle relative to the first cycle was measured.
(2) Rate of increase in gas production volume
And (3) placing the lithium secondary battery in heat conduction oil at 70 ℃ for 60 days, testing the volume of the battery placed on the 1 st day and the 60 th day by using a fries volume tester, and dividing the battery volume difference by 3.2Ah to obtain the volume increase rate of the battery.
Table 1: performance of lithium secondary batteries corresponding to examples 1-2 and comparative examples 1-2
Figure BDA0004065661100000201
From the test results of example 1 and example 2, it is understood that the coating agent TiO was used 2 Capacity, cycle capacity retention and gas production performance can be improved. As can be seen from the test results of comparative examples 1 and 2, the coating agent W was used 2 O 3 Capacity, cycle capacity retention and gas production performance can be improved. As is clear from the experimental results of example 2 and comparative example 2, zr was doped and W was coated with a suspension during the preparation of the precursor 2 O 3 Can obviously improve capacity, circulation capacity retention rate and gas production performance.

Claims (10)

1. A method of preparing a ternary positive electrode material, the method comprising the steps of:
(1) The Ni salt, co salt, mn salt and M element are sourced from water to carry out coprecipitation reaction under the action of NaOH and ammonia water, thus obtaining ternary positive electrode material precursor Ni x Co y Mn z M (1-x-y-z) (OH) 2 Wherein x is more than or equal to 0.4 and less than or equal to 0.95, y is more than or equal to 0 and less than 0.4, z is more than or equal to 0 and less than 0.4, x+y+z is less than 1, and M is one or more doping elements selected from Zr, ti, mg, B and Ba;
(2) Mixing the ternary cathode material precursor, the Sr source and the lithium salt, and performing primary sintering to obtain a primary sintered material;
(3) And coating a W source on the surface of the primary sintered material to obtain a material coated with the W source, coating one or two of an Al source and a Ti source, and performing secondary sintering to obtain the ternary anode material.
2. The method of claim 1, wherein the method has one or more of the following features:
the doping element M comprises Zr, and the M element source comprises a water-soluble Zr-containing compound, preferably a water-soluble Zr-containing compound selected from Li 2 ZrF 6 And Zr (HPO) 4 ) 2 ·H 2 One or two of O;
chemical formula Ni of ternary positive electrode material precursor x Co y Mn z M (1-x-y-z) (OH) 2 Wherein x is more than or equal to 0.6 and less than or equal to 0.7,0, y is more than or equal to 0.1, z is more than or equal to 0.2 and less than 0.3, and x+y+z is less than 0.98;
the particle size D50 of the ternary positive electrode material precursor is 2-10 mu m;
the specific surface area of the ternary positive electrode material precursor is 5-15cm 2 /g；
The pH value of the coprecipitation reaction is 9-12, the reaction temperature is 60-80 ℃, and the reaction time is 5-12h.
3. The method of claim 1, wherein the method has one or more of the following features:
the Sr source comprises a source selected from SrCO 3 And one or both of SrO;
the ratio of the amount of the ternary positive electrode material precursor to the amount of the substances of Sr element in the Sr source is 1 (0.0001-0.001);
the lithium salt comprises one or more selected from lithium carbonate, lithium hydroxide and lithium hydroxide monohydrate;
the ratio of the amount of lithium element in the lithium salt to the amount of the substance of the ternary positive electrode material precursor is (1.02-1.08): 1;
mixing the ternary cathode material precursor, the Sr source and the lithium salt in a dry mixing or ball milling mixing mode;
The heat preservation temperature of the primary sintering is 750-980 ℃ and the heat preservation time is 6-12h;
the method comprises the steps of crushing the primary sintered material to the D50 particle size of 2-15 mu m after primary sintering.
4. The method of claim 1, wherein the method has one or more of the following features:
the W source comprises a source selected from W 2 O 3 、WO 2 And (NH) 4 ) 10 W 12 O 41 ～xH 2 One or more of O;
the particle size of the W source is 100-200nm;
the ratio of the amount of the burned material to the amount of the substance of the W element in the W source is 1 (0.001-0.01);
coating the W source on the surface of the primary combustion material in a wet mixing mode; preferably, the wet mixing comprises: firstly preparing a W source suspension by using a W source, a surfactant, a dispersing agent and water, mixing the primary-combustion crushed material and the suspension, filtering and drying to coat the W source on the surface of the primary-combustion material, and obtaining a material coated with the W source; wherein the surfactant is preferably cetyl trimethyl ammonium bromide, the dispersing agent is preferably polyethylene glycol-10000, the concentration of the W source in the suspension is preferably 0.5-2g/L, the concentration of the surfactant is preferably 1-2g/L, and the concentration of the dispersing agent is preferably 0.5-1.5g/L;
The average density of W atoms on the surface of the material coated with the W source is 1-800/cm 2 。
5. The method of claim 1, wherein the method has one or more of the following features:
the Al source comprises a material selected from the group consisting of Al 2 O 3 、Al(OH) 3 、AlO 9 P 3 And AlPO 4 One or more of the following;
the grain diameter of the Al source is 30-60nm;
when the cladding element comprises Al, the ratio of the material of the cladding W source to the material of the Al element in the Al source is 1 (0.001-0.01);
the Ti source comprises a metal selected from TiO, tiO 2 And Ti is 2 O 3 One or more of the following;
the grain diameter of the Ti source is 30-60nm;
when the coating element comprises Ti, the ratio of the material coating the W source to the amount of the Ti element in the Ti source is 1 (0.001-0.01);
coating one or two selected from the Al source and the Ti source on the surface of the material coated with the W source in a dry mixing mode;
the average density of Al atoms or Ti atoms coated on the surface of the material selected from one or two of the Al source and the Ti source is 100-3000 pieces/cm 2 ；
The heat preservation temperature of the secondary sintering is 300-700 ℃ and the heat preservation time is 6-12h.
6. A ternary cathode material prepared by the method of any one of claims 1-5.
7. A ternary positive electrode material is characterized in that the ternary positive electrode material is Li doped with Sr and coated with W and one or two elements selected from Al and Ti n Ni x Co y Mn z M (1-x-y-z) O 2 Wherein n is 1.02-1.08,0.4, x is less than or equal to 0.95, y is more than 0 and less than 0.4, z is more than 0 and less than 0.4, x+y+z is less than 1, and M is one or more doping elements selected from Zr, ti, mg, B and Ba.
8. The ternary cathode material of claim 7, wherein the ternary cathode material has one or more of the following characteristics:
the doping element M comprises Zr, and the M element source comprises a water-soluble Zr-containing compound, preferably a water-soluble Zr-containing compound selected from Li 2 ZrF 6 And Zr (HPO) 4 ) 2 ·H 2 One or two of O;
the doping element M is doped into a precursor of the ternary positive electrode material;
the Li is n Ni x Co y Mn z M (1-x-y-z) O 2 Wherein x is more than or equal to 0.6 and less than or equal to 0.7,0, y is more than or equal to 0.1, z is more than or equal to 0.2 and less than 0.3, and x+y+z is less than 0.98;
in the ternary positive electrode material, li n Ni x Co y Mn z M (1-x-y-z) O 2 The ratio of the amount of the Sr element to the amount of the Sr element is 1 (0.0001-0.001);
in the ternary positive electrode material, li n Ni x Co y Mn z M (1-x-y-z) O 2 The ratio of the amount of the substance to the W element is 1 (0.001-0.01);
the average density of W atoms on the surface of the ternary positive electrode material is 1-800/cm 2 ；
When the coating element comprises Al, li in the ternary positive electrode material n Ni x Co y Mn z M (1-x-y-z) O 2 The ratio of the Al element to the Al element is 1 (0.001-0.01);
when the coating element comprises Ti, li in the ternary positive electrode material n Ni x Co y Mn z M (1-x-y-z) O 2 The ratio of the Ti element to the Ti element is 1 (0.001-0.01);
The average density of Al atoms or Ti atoms on the surface of the ternary positive electrode material is 100-3000 pieces/cm 2 ；
The ternary positive electrode material is prepared by adopting the method of any one of claims 1-5.
9. A positive electrode sheet, characterized in that it contains the ternary positive electrode material according to any one of claims 6 to 8.
10. A lithium ion battery comprising the positive electrode sheet of claim 9.
CN202310074052.2A 2023-01-18 2023-01-18 Low-gas-yield long-cycle ternary positive electrode material and preparation method thereof Pending CN116040697A (en)

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