CN117174876A - Positive electrode precursor material and preparation method and application thereof - Google Patents
Positive electrode precursor material and preparation method and application thereof Download PDFInfo
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- 239000000463 material Substances 0.000 title claims abstract description 82
- 239000002243 precursor Substances 0.000 title claims abstract description 71
- 238000002360 preparation method Methods 0.000 title abstract description 22
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims abstract description 72
- 229910052759 nickel Inorganic materials 0.000 claims abstract description 33
- 239000007774 positive electrode material Substances 0.000 claims abstract description 23
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 claims abstract description 20
- 239000000243 solution Substances 0.000 claims description 79
- 238000006243 chemical reaction Methods 0.000 claims description 63
- 238000000975 co-precipitation Methods 0.000 claims description 49
- 229910052751 metal Inorganic materials 0.000 claims description 43
- 239000002184 metal Substances 0.000 claims description 32
- 239000002245 particle Substances 0.000 claims description 27
- 239000012266 salt solution Substances 0.000 claims description 27
- 239000008139 complexing agent Substances 0.000 claims description 17
- 239000002585 base Substances 0.000 claims description 15
- 239000002019 doping agent Substances 0.000 claims description 13
- 239000000126 substance Substances 0.000 claims description 13
- 238000000034 method Methods 0.000 claims description 12
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims description 10
- 229910052782 aluminium Inorganic materials 0.000 claims description 10
- 235000011114 ammonium hydroxide Nutrition 0.000 claims description 10
- 238000005245 sintering Methods 0.000 claims description 8
- 238000002156 mixing Methods 0.000 claims description 7
- 239000012716 precipitator Substances 0.000 claims description 7
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims description 6
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 claims description 6
- 239000003513 alkali Substances 0.000 claims description 6
- 229910052744 lithium Inorganic materials 0.000 claims description 6
- 229910001416 lithium ion Inorganic materials 0.000 claims description 6
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- 239000007788 liquid Substances 0.000 claims description 5
- 229910052799 carbon Inorganic materials 0.000 claims description 4
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonium chloride Substances [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 claims description 2
- QGZKDVFQNNGYKY-UHFFFAOYSA-N ammonia Natural products N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims description 2
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- 239000010405 anode material Substances 0.000 description 13
- 239000011248 coating agent Substances 0.000 description 10
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- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 8
- 230000000052 comparative effect Effects 0.000 description 8
- 239000011572 manganese Substances 0.000 description 8
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 6
- VEQPNABPJHWNSG-UHFFFAOYSA-N Nickel(2+) Chemical compound [Ni+2] VEQPNABPJHWNSG-UHFFFAOYSA-N 0.000 description 6
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 6
- 229910001429 cobalt ion Inorganic materials 0.000 description 6
- XLJKHNWPARRRJB-UHFFFAOYSA-N cobalt(2+) Chemical compound [Co+2] XLJKHNWPARRRJB-UHFFFAOYSA-N 0.000 description 6
- 150000002500 ions Chemical class 0.000 description 6
- 229910001437 manganese ion Inorganic materials 0.000 description 6
- 229910001453 nickel ion Inorganic materials 0.000 description 6
- 239000013078 crystal Substances 0.000 description 5
- 238000001035 drying Methods 0.000 description 5
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 description 4
- 239000010406 cathode material Substances 0.000 description 4
- 238000009826 distribution Methods 0.000 description 4
- 238000003756 stirring Methods 0.000 description 4
- 229910052726 zirconium Inorganic materials 0.000 description 4
- WMFOQBRAJBCJND-UHFFFAOYSA-M Lithium hydroxide Chemical compound [Li+].[OH-] WMFOQBRAJBCJND-UHFFFAOYSA-M 0.000 description 3
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 3
- 238000001354 calcination Methods 0.000 description 3
- 238000005253 cladding Methods 0.000 description 3
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- 229910052749 magnesium Inorganic materials 0.000 description 3
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- 238000005406 washing Methods 0.000 description 3
- CSNNHWWHGAXBCP-UHFFFAOYSA-L Magnesium sulfate Chemical compound [Mg+2].[O-][S+2]([O-])([O-])[O-] CSNNHWWHGAXBCP-UHFFFAOYSA-L 0.000 description 2
- 229910016739 Ni0.5Co0.2Mn0.3(OH)2 Inorganic materials 0.000 description 2
- WNROFYMDJYEPJX-UHFFFAOYSA-K aluminium hydroxide Chemical group [OH-].[OH-].[OH-].[Al+3] WNROFYMDJYEPJX-UHFFFAOYSA-K 0.000 description 2
- DIZPMCHEQGEION-UHFFFAOYSA-H aluminium sulfate (anhydrous) Chemical compound [Al+3].[Al+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O DIZPMCHEQGEION-UHFFFAOYSA-H 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 229910017052 cobalt Inorganic materials 0.000 description 2
- 239000010941 cobalt Substances 0.000 description 2
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 2
- 230000001276 controlling effect Effects 0.000 description 2
- 239000011258 core-shell material Substances 0.000 description 2
- 239000011267 electrode slurry Substances 0.000 description 2
- 230000014759 maintenance of location Effects 0.000 description 2
- -1 nickel-cobalt-manganese-aluminum Chemical compound 0.000 description 2
- 238000007873 sieving Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- WQZGKKKJIJFFOK-GASJEMHNSA-N Glucose Natural products OC[C@H]1OC(O)[C@H](O)[C@@H](O)[C@@H]1O WQZGKKKJIJFFOK-GASJEMHNSA-N 0.000 description 1
- 229910013716 LiNi Inorganic materials 0.000 description 1
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 1
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- HFCVPDYCRZVZDF-UHFFFAOYSA-N [Li+].[Co+2].[Ni+2].[O-][Mn]([O-])(=O)=O Chemical compound [Li+].[Co+2].[Ni+2].[O-][Mn]([O-])(=O)=O HFCVPDYCRZVZDF-UHFFFAOYSA-N 0.000 description 1
- 239000006230 acetylene black Substances 0.000 description 1
- 230000003044 adaptive effect Effects 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 239000000306 component Substances 0.000 description 1
- 239000008358 core component Substances 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
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- 229910052943 magnesium sulfate Inorganic materials 0.000 description 1
- 235000019341 magnesium sulphate Nutrition 0.000 description 1
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- 238000012360 testing method Methods 0.000 description 1
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
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- Battery Electrode And Active Subsutance (AREA)
Abstract
The invention provides a positive electrode precursor material, and a preparation method and application thereof. The positive electrode precursor material sequentially coats the inner core, the middle layer and the outer shell layer from inside to outside; the inner core comprises a first hydroxide precursor material; the intermediate layer comprises a hydroxide material of a doping element, and the shell comprises a second hydroxide precursor; the molar content of nickel in the second hydroxide precursor material is less than the molar content of nickel in the first hydroxide precursor. According to the invention, the intermediate layer doped with elements is added into the precursor material, so that the transition effect of the inner core and the outer shell layer is achieved, the combination between the inner core and the outer shell is enhanced, the outer shell is effectively prevented from being separated, and the structural stability is improved, thereby improving the structural stability of the positive electrode material and obtaining the positive electrode material with excellent cycle performance and multiplying power performance.
Description
Technical Field
The invention belongs to the technical field of lithium ion batteries, and relates to a positive electrode precursor material, a preparation method and application thereof.
Background
Along with the increasing energy demand, lithium ion batteries have become the main power sources of electric vehicles, smart phones, notebook computers and the like, and are widely applied in the energy storage field. As a core component of the lithium ion battery, the performance of the positive electrode material directly influences key indexes such as energy density, cycle life, safety performance and the like of the battery.
In order to improve the capacity of the ternary nickel cobalt lithium manganate positive electrode material, the proportion of nickel element is continuously improved, the initial 33% of nickel element is increased to more than 80%, and the nickel element is increased to more than 90% in recent years, so that the ultrahigh nickel positive electrode material is formed. The ultra-high nickel anode material is considered as the anode material with the most development prospect, and researches show that the ultra-high nickel anode material has high capacity, but poor cycle stability and low material conductivity. At present, surface coating is one of the most effective modification methods for the lithium ion battery anode material, but the traditional coating process is complex, coating is uneven, the conductivity of the material is reduced, the coating effect is poor, the anode material is easy to contact with electrolyte to generate side reaction, the service life of the material is seriously influenced, and the conductivity of the material is reduced.
CN112310389a discloses a preparation method of an ultra-high nickel monocrystal positive electrode material, which comprises the following steps: s1, mixing a ternary precursor and lithium hydroxide according to a molar ratio of lithium to metal of 1.01-1.10:1, adding a doping agent, and calcining under an oxygen atmosphere to obtain a primary calcined material; s2, carrying out coarse crushing, fine crushing, sieving and demagnetizing on the primary calcined material to obtain a crushed material; s3, adding the crushed materials and water into a reaction kettle in a water-material ratio of 0.5:1-5:1, controlling the temperature of the reaction kettle, adding reagents for reaction, and drying after the reaction is finished to obtain a mixed material; s4, mixing the mixed material and the modified coating agent, placing the mixed material and the modified coating agent in an atmosphere furnace for secondary calcination, and performing coarse crushing, fine crushing, sieving and demagnetizing to obtain the ternary anode material. The conventional metal coating is adopted in the document, the coating effect is poor, and the ultra-high nickel anode material is a single crystal material.
CN113809320A quaternary polycrystalline positive electrode material, preparation method and application thereof, wherein chemical formula of quaternary polycrystalline positive electrode material is LiNi a Co b Mn c Al d Ta (1-a-b-c-d) O 2 Wherein a is more than or equal to 0.9 and less than 1, b is more than 0 and less than 0.07,0, c is more than 0.03,0 and d is more than or equal to 0.002, and the preparation method comprises the following steps: and mixing the nickel-cobalt-manganese-aluminum quaternary precursor, a lithium source, a tantalum source and a cobalt source to obtain a mixture, and calcining the mixture to obtain the quaternary polycrystalline anode material. The coating is not performed in this document, and is a single crystal cathode material.
Meanwhile, the core-shell type ultra-high nickel anode material obtained after cladding still has a plurality of problems in the aspects of cycle performance and the like at present, so that the commercialized application process is slower.
Therefore, how to improve the electrochemical performance of the positive electrode material with higher nickel content is a technical problem to be solved.
Disclosure of Invention
Aiming at the defects existing in the prior art, the invention aims to provide a positive electrode precursor material, and a preparation method and application thereof. According to the invention, the intermediate layer doped with elements is added into the precursor material, so that the transition effect of the inner core and the outer shell layer is achieved, the combination between the inner core and the outer shell is enhanced, the outer shell is effectively prevented from being separated, and the structural stability is improved, thereby improving the structural stability of the positive electrode material and obtaining the positive electrode material with excellent cycle performance and multiplying power performance.
To achieve the purpose, the invention adopts the following technical scheme:
in a first aspect, the present invention provides a positive electrode precursor material, where the positive electrode precursor material sequentially coats, from inside to outside, a core, an intermediate layer, and an outer shell layer; the inner core comprises a first hydroxide precursor material; the intermediate layer comprises a hydroxide material of a doping element, and the shell comprises a second hydroxide precursor; the molar content of nickel in the second hydroxide precursor material is less than the molar content of nickel in the first hydroxide precursor.
The precursor material provided by the invention can comprise cobalt and/or manganese besides nickel element, and can be adaptively adjusted according to actual requirements.
In the positive electrode material provided by the invention, the nickel content of the inner core is higher than that of the outer shell, so that gradient distribution of nickel is realized, and the effect of improving the battery capacity is achieved; meanwhile, the intermediate layer which is cooperatively matched with the doping element is tightly combined with the inner core and the outer shell, so that the transition effect of the inner core and the outer shell is achieved, the combination between the inner core and the outer shell is enhanced, the outer shell is effectively prevented from being separated, the structural stability is improved, the structural stability of the anode material is improved, and the anode material with excellent cycle performance and multiplying power performance is obtained.
In the invention, if the middle layer is not arranged, the corrosion of the crack of the circulating shell to the inside gradually along with the crack of the circulating shell cannot be isolated, and the circulating performance of the battery is affected; and if the nickel content remains consistent between the core and the shell, this results in a lower battery capacity.
Preferably, the chemical formula of the first hydroxide precursor material is Ni x Co y Mn 1-x-y (OH) 2 Wherein 0.8<x≤0.99，0≤y≤0.2。
For example, the x may be 0.8, 0.83, 0.85, 0.9, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, or 0.99, etc., and the y may be 0, 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.13, 0.15, 0.18, or 0.2, etc.
In the invention, the inner core is made of high nickel anode material, so that the battery capacity is improved.
Preferably, the molar amount of the doping element is 0.01 to 0.1%, for example, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, or 0.1% of the total molar amount of the total metal elements in the positive electrode precursor material, and the like.
In the invention, the molar quantity of the doping element is too small to realize the function of the intermediate layer, and too much doping element can influence the performance of the battery.
Preferably, the doping element comprises any one or a combination of at least two of Al, mg, zn, ti, na, li, sn or Nb.
Preferably, the second hydroxide precursor material has the chemical formula Ni a Co b Mn 1-a-b (OH) 2 Wherein 0.2<a≤0.6，0≤b≤0.2。
For example, a may be 0.21, 0.23, 0.25, 0.28, 0.3, 0.33, 0.35, 0.38, 0.4, 0.43, 0.45, 0.48, 0.5, 0.53, 0.55, 0.58, or 0.6, etc., and b may be 0, 0.03, 0.05, 0.08, 0.1, 0.13, 0.15, 0.18, or 0.2, etc.
In the invention, the inner core is made of a high-nickel precursor material, and the outer shell is made of a medium-low-nickel precursor material, so that the outer shell can keep high cycle performance, the inner core provides higher capacity, and the capacity and cycle performance are cooperatively improved.
In a second aspect, the present invention provides a method for preparing the positive electrode precursor material according to the first aspect, the method comprising the steps of:
the first main metal mixed salt solution, the precipitator solution and the complexing agent solvent are added into the base solution in parallel flow, the coprecipitation reaction of the first stage is carried out, and after the first target particle size is reached, the first main metal mixed salt solution is replaced by the doping agent solution, and the coprecipitation reaction of the second stage is carried out;
after the second-stage coprecipitation reaction is finished, replacing the dopant solution with a second main metal mixed salt solution, continuing to perform a third-stage coprecipitation reaction, and after the final target particle size is reached, finishing the reaction to obtain the anode precursor material;
the molar content of nickel in the second main metal mixed salt solution is less than the molar content in the first main metal mixed salt solution.
The preparation method provided by the invention is simple, easy to operate and suitable for large-scale production, and the positive electrode precursor material with stable structure is obtained through three-stage coprecipitation reaction.
Preferably, the molar concentration of the main metal element in the first main metal mixed salt solution and the molar concentration of the main metal element in the second main metal mixed salt solution are each independently 1.6 to 2.4mol/L, for example 1.6mol/L, 1.7mol/L, 1.8mol/L, 1.9mol/L, 2mol/L, 2.1mol/L, 2.2mol/L, 2.3mol/L, 2.4mol/L, or the like.
Preferably, the concentration of the precipitant solution is 9 to 12mol/L, for example 9mol/L, 10mol/L, 11mol/L, 12mol/L, or the like.
Preferably, the precipitant solution comprises an alkali solution.
Preferably, the concentration of the complexing agent solution is 7 to 10mol/L, for example 7mol/L, 8mol/L, 9mol/L, 10mol/L, etc.
Preferably, the complexing agent solution comprises an aqueous ammonia solution.
Preferably, the first target particle diameter is 3 to 9 μm, for example, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, 5.5 μm, 6 μm, 6.5 μm, 7 μm, 8 μm, 9 μm, etc.
In the invention, the first target particle size is too large, which is not beneficial to the cladding of the middle layer; too small can in turn affect the nickel content of the precursor material as a whole.
Preferably, the co-precipitation reaction in the second stage is ended when the molar amount of the doping element in the dopant is 0.05 to 0.1%, for example, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, or 0.1%, etc., of the total molar amount of the total metal elements in the positive electrode precursor material.
In the invention, in the coprecipitation process of the first stage, the doping amount of doping elements is excessive, and the battery capacity is influenced; the doping amount is too small, and the connection effect of the inner core and the outer shell cannot be realized.
Preferably, the final target particle size is 9 to 14 μm, for example 9 μm, 9.5 μm, 10 μm, 10.5 μm, 11 μm, 11.5 μm, 12 μm, 12.5 μm, 13 μm, 13.5 μm or 14 μm, etc.
Preferably, the pH during the coprecipitation reaction is 9 to 13, for example 9, 9.3, 9.5, 9.8, 10, 10.3, 10.5, 10.8, 11, 11.3, 11.5, 11.8, 12, 12.3, 12.5, 12.8 or 13, etc.
As a preferred technical scheme, the preparation method comprises the following steps:
adding a first main metal mixed salt solution, a liquid alkali solution and an ammonia water solution into a base solution in parallel, performing a first-stage coprecipitation reaction, replacing the first main metal mixed salt solution with a dopant solution after the first target particle diameter is 3-9 mu m, and performing a second-stage coprecipitation reaction, wherein the molar quantity of doping elements in the dopant is 0.05-0.1% of the total molar quantity of total metal elements in the positive electrode precursor material, and finishing the second-stage coprecipitation reaction;
after the second-stage coprecipitation reaction is finished, replacing the dopant solution with a second main metal mixed salt solution, continuing to perform a third-stage coprecipitation reaction, and after the final target particle size is 9-14 mu m, finishing the reaction to obtain the anode precursor material;
the molar content of nickel in the second main metal mixed salt solution is smaller than the molar content in the first main metal mixed salt solution; the pH value in the coprecipitation reaction process is 9-13.
It should be noted that the whole process of the coprecipitation reaction provided by the invention is carried out in a protective atmosphere, and the preparation of the base solution and parameters of the coprecipitation reaction process in each stage are all selected by conventional technology.
Optionally, regulating and controlling water, a precipitator solution and a complexing agent solution, and mixing to obtain a base solution, wherein the pH value in the base solution is controlled to be 9-13, the concentration of the complexing agent solution in the base solution is 1-8 g/L, and the temperature in the base solution is 30-80 ℃;
optionally, the reaction temperature in the coprecipitation reaction process is 30-80 ℃, and the stirring speed is 200-500 rpm; and the pH value of each stage is adaptively adjusted within a selectable range.
In a third aspect, the present invention provides a positive electrode material, wherein the positive electrode is obtained by mixing and sintering the positive electrode precursor material according to the first aspect and a lithium source.
In the invention, the selection of the lithium source, the sintering times, the sintering time and the sintering temperature are all routine choices of the technicians in the field; one skilled in the art can select one sintering or multiple sintering according to actual requirements, and simultaneously perform adaptive doping and cladding.
Preferably, the sintered material is carbon coated.
According to the invention, carbon coating is carried out on the surface of the positive electrode material obtained by sintering, so that the cycle performance and the multiplying power performance of the positive electrode material can be improved.
In a fourth aspect, the present invention also provides a lithium ion battery comprising the positive electrode material according to the third aspect.
Compared with the prior art, the invention has the following beneficial effects:
in the positive electrode material provided by the invention, the nickel content of the inner core is higher than that of the outer shell, the gradient distribution of nickel is realized, meanwhile, the intermediate layer doped with elements is cooperated, the intermediate layer is tightly combined with the inner core and the outer shell, the transition effect of the inner core and the outer shell is achieved, the combination between the inner core and the outer shell is enhanced, the outer shell is effectively prevented from being separated, the structural stability is improved, and the structural stability of the positive electrode material is improved, so that the positive electrode material with excellent cycle performance and multiplying power performance is obtained.
Detailed Description
The technical scheme of the invention is further described by the following specific examples. It will be apparent to those skilled in the art that the examples are merely to aid in understanding the invention and are not to be construed as a specific limitation thereof.
Example 1
The embodiment provides a positive electrode precursor material, which sequentially coats an inner core, an intermediate layer and an outer shell layer from inside to outside; the chemical formula of the inner core is Ni 0.96 Co 0.03 Mn 0.01 (OH) 2 The middle layer is aluminum hydroxide, and the shell has the chemical formula of Ni 0.5 Co 0.2 Mn 0.3 (OH) 2 The method comprises the steps of carrying out a first treatment on the surface of the Wherein the molar amount of aluminum is 0.05% of the total molar amount of the total metal elements in the positive electrode precursor material.
The preparation method of the positive electrode precursor material comprises the following steps:
step 1: preparing sulfate solution A with total ion concentration of 2mol/L, wherein the molar ratio of nickel ions to cobalt ions to manganese ions is 96:3:1, preparing sulfate solution B with total ion concentration of 2mol/L, wherein the molar ratio of nickel ions to cobalt ions to manganese ions is 5:2:3, adopting industrial liquid alkali with concentration of 10mol/L as precipitant solution C, adopting 9mol/L ammonia water as complexing agent solution D, and preparing aluminum sulfate solution E with concentration of 2mol/L;
step 2: preparing a base solution F containing a certain precipitant solution and a complexing agent solution in a reaction kettle, wherein the pH value of F is controlled to be 10, the concentration of ammonia water in F is 2g/L, and the temperature of F is 40 ℃; introducing nitrogen as a shielding gas, adding the mixed salt solution A, the precipitator solution B and the complexing agent solution C into the base solution F of the reaction kettle in parallel, ensuring that the pH value is 10, adopting a common stirring paddle to carry out a first-stage coprecipitation reaction at a rotating speed of 300rpm to obtain seed crystal particles with a first target particle diameter D50 of 7.5 mu m, and stopping injecting the mixed solution A; then adding the solution E to carry out the coprecipitation reaction of the second stage, and stopping adding the solution E when the molar quantity of aluminum is 0.05%; adding the solution B, performing a coprecipitation reaction in a third stage, and ending the coprecipitation reaction when the particle size D50 grows to 12 mu m;
step 3: and (3) centrifuging, washing, drying, removing magnetic foreign matters and the like the obtained product to obtain the anode precursor material.
Example 2
The embodiment provides a positive electrode precursor material, which sequentially coats an inner core, an intermediate layer and an outer shell layer from inside to outside; the chemical formula of the inner core is Ni 0.96 Co 0.03 Mn 0.01 (OH) 2 The middle layer is aluminum hydroxide, and the shell has the chemical formula of Ni 0.5 Co 0.2 Mn 0.3 (OH) 2 The method comprises the steps of carrying out a first treatment on the surface of the Wherein the molar amount of aluminum is 0.1% of the total molar amount of the total metal elements in the positive electrode precursor material.
The preparation method of the positive electrode precursor material comprises the following steps:
step 1: preparing sulfate solution A with total ion concentration of 2.4mol/L, wherein the molar ratio of nickel ions to cobalt ions to manganese ions is 96:3:1, preparing sulfate solution B with total ion concentration of 2.4mol/L, wherein the molar ratio of nickel ions to cobalt ions to manganese ions is 5:2:3, adopting industrial liquid alkali with concentration of 10mol/L as precipitant solution C, adopting 9mol/L ammonia water as complexing agent solution D, and preparing aluminum sulfate solution E with concentration of 2mol/L;
step 2: preparing a base solution F containing a certain precipitant solution and a complexing agent solution in a reaction kettle, wherein the pH value of F is controlled to be 10, the concentration of ammonia water in F is 2g/L, and the temperature of F is 40 ℃; introducing nitrogen as a shielding gas, adding the mixed salt solution A, the precipitator solution B and the complexing agent solution C into the base solution F of the reaction kettle in parallel, ensuring that the pH value is 10, adopting a common stirring paddle to carry out a first-stage coprecipitation reaction at a rotating speed of 300rpm to obtain seed crystal particles with a first target particle diameter D50 of 3 mu m, and stopping injecting the mixed solution A; then adding the solution E to carry out the coprecipitation reaction of the second stage, and stopping adding the solution E when the molar quantity of aluminum is 0.1%; adding the solution B, performing a coprecipitation reaction in a third stage, and ending the coprecipitation reaction when the particle size D50 grows to 9 mu m;
step 3: and (3) centrifuging, washing, drying, removing magnetic foreign matters and the like the obtained product to obtain the anode precursor material.
Example 3
The embodiment provides a positive electrode precursor material, which sequentially coats an inner core, an intermediate layer and an outer shell layer from inside to outside; the chemical formula of the inner core is Ni 0.91 Co 0.05 Mn 0.04 (OH) 2 The intermediate layer is hydroxide of magnesium and zirconium, and the shell has chemical formula of Ni 0.6 Co 0.2 Mn 0.2 (OH) 2 The method comprises the steps of carrying out a first treatment on the surface of the Wherein the sum of the molar amounts of magnesium and zirconium is 0.08% of the total molar amount of the total metal elements in the positive electrode precursor material.
The preparation method of the positive electrode precursor material comprises the following steps:
step 1: preparing sulfate solution A with the total ion concentration of 1.6mol/L, wherein the molar ratio of nickel ions to cobalt ions to manganese ions is 91:5:4, preparing sulfate solution B with the total ion concentration of 1.6mol/L, wherein the molar ratio of nickel ions to cobalt ions to manganese ions is 6:2:2, adopting industrial liquid alkali with the concentration of 9mol/L as precipitant solution C, adopting 7mol/L ammonia water as complexing agent solution D, and preparing solution E of magnesium sulfate and zirconium with the molar ratio of 1.6mol/L (magnesium to zirconium is 1:1);
step 2: preparing a base solution F containing a certain precipitator solution and a complexing agent solution in a reaction kettle, wherein the pH value of F is controlled to be 10.8, the concentration of ammonia water in F is 2g/L, and the temperature of F is 50 ℃; introducing nitrogen as a shielding gas, adding the mixed salt solution A, the precipitator solution B and the complexing agent solution C into the base solution F of the reaction kettle in parallel, ensuring that the pH value is 11, adopting a common stirring paddle to carry out a first-stage coprecipitation reaction at a rotating speed of 380rpm to obtain seed crystal particles with a first target particle diameter D50 of 8.5 mu m, and stopping injecting the mixed solution A; then adding the solution E to carry out the coprecipitation reaction of the second stage, and stopping adding the solution E when the molar quantity of aluminum is 0.08%; adding the solution B, performing a coprecipitation reaction in a third stage, and ending the coprecipitation reaction when the particle size D50 grows to 12 mu m;
step 3: and (3) centrifuging, washing, drying, removing magnetic foreign matters and the like the obtained product to obtain the anode precursor material.
Example 4
The difference between this example and example 1 is that the D50 of the first target particle diameter in step 2 of this example is 2. Mu.m.
The remaining preparation methods and parameters were consistent with example 1.
Example 5
The difference between this example and example 1 is that the first target particle diameter D50 in step 2 of this example is 10. Mu.m.
The remaining preparation methods and parameters were consistent with example 1.
Example 6
The difference between this example and example 1 is that the second-stage coprecipitation reaction is completed when the molar amount of aluminum in step 2 of this example is 1.5% of the total molar amount of the total metal elements in the positive electrode precursor material.
The remaining preparation methods and parameters were consistent with example 1.
Example 7
The difference between this example and example 1 is that the second-stage coprecipitation reaction is completed when the molar amount of aluminum in step 2 of this example is 0.03% of the total molar amount of the total metal elements in the positive electrode precursor material.
The remaining preparation methods and parameters were consistent with example 1.
Comparative example 1
The difference between this comparative example and example 1 is that the positive electrode precursor material provided in this comparative example does not contain an intermediate layer, i.e., the core is directly followed by the shell.
In the preparation method, the solution E is not prepared, the second-stage coprecipitation reaction is not carried out, and the third-stage coprecipitation reaction is directly carried out after the first-stage coprecipitation reaction is finished.
The remaining preparation methods and parameters were consistent with example 1.
Comparative example 2
The difference between this comparative example and example 1 is that the positive electrode precursor material of this comparative example has the chemical formula of Ni 0.96 Co 0.03 Mn 0.01 (OH) 2 (i.e., core material from inside to outside).
In the preparation method, the coprecipitation reaction of the second stage and the third stage is not carried out, and the coprecipitation reaction of the first stage is carried out until the target particle size of 12 mu m is reached.
The remaining preparation methods and parameters were consistent with example 1.
The positive electrode precursor materials provided in examples 1 to 7 and comparative examples 1 to 2 were mixed with Li 2 CO 3 The powder is uniformly mixed according to the element ratio (the molar ratio of Li to Me (metal element) is 1.05:1.0), the mixture is calcined in the air atmosphere at 800 ℃ to obtain a burned material, and then the burned material is mixed with glucose solution to be coated with liquid phase carbon, so that the anode material is obtained.
Mixing a positive electrode material, acetylene black and polyvinylidene fluoride according to the mass ratio of 8:1:1, adding NMP to obtain positive electrode slurry, uniformly coating the positive electrode slurry on an aluminum foil, drying, and stamping to obtain a sheet (positive electrode sheet). And assembling the battery pole piece, the metal lithium piece and the polyethylene diaphragm into the button battery.
Performing performance test on the obtained battery, wherein the test conditions are as follows: 25 ℃ C:: the voltage interval was 2.5V to 3.65V, the charge-discharge rate was 0.1C/0.1C, the capacity and cycle performance were measured, and the rate performance was also measured at 0.1C/1C, and the results are shown in Table 1.
TABLE 1
From table 1, it can be derived that:
from the data of examples 1 and 4 and 5, it is understood that too small a first target particle size affects battery capacity, while too large a first target particle size results in a low cycle retention rate.
From the data of examples 1 and 6 and 7, it is understood that the excessive molar amount of the doping element during the coprecipitation reaction in the second stage adversely affects the battery capacity, while the excessively small amount results in a low cycle retention rate.
From the data results of example 1 and comparative examples 1 and 2, the gradient distribution of nickel and the addition of the intermediate layer cooperate to jointly play a role in improving the stability of the core-shell structure, and the shell is not easy to separate, so that the cycle performance and the multiplying power performance are improved.
In summary, in the cathode material provided by the invention, the nickel content of the inner core is higher than that of the outer shell, so that gradient distribution of nickel is realized, meanwhile, the intermediate layer which is cooperatively doped with elements is tightly combined with the inner core and the outer shell, so that the transition effect of the inner core and the outer shell is achieved, the combination between the inner core and the outer shell is enhanced, the outer shell is effectively prevented from being separated, the structural stability is improved, and the structural stability of the cathode material is improved, so that the cathode material with excellent cycle performance and multiplying power performance is obtained.
The applicant states that the detailed method of the present invention is illustrated by the above examples, but the present invention is not limited to the detailed method described above, i.e. it does not mean that the present invention must be practiced in dependence upon the detailed method described above. It should be apparent to those skilled in the art that any modification of the present invention, equivalent substitution of raw materials for the product of the present invention, addition of auxiliary components, selection of specific modes, etc., falls within the scope of the present invention and the scope of disclosure.
Claims (10)
1. The positive electrode precursor material is characterized in that the positive electrode precursor material sequentially coats the inner core, the middle layer and the outer shell layer from inside to outside; the inner core comprises a first hydroxide precursor material; the intermediate layer comprises a hydroxide material of a doping element, and the shell comprises a second hydroxide precursor; the molar content of nickel in the second hydroxide precursor material is less than the molar content of nickel in the first hydroxide precursor.
2. The positive electrode precursor material of claim 1, wherein the first hydroxide precursor material has a chemical formula of Ni x Co y Mn 1-x-y (OH) 2 Wherein 0.8<x is more than or equal to 0.99,0, y is more than or equal to 0.2; preferably, the molar amount of the doping element is 0.01 to 0.1% of the total molar amount of the total metal elements in the positive electrode precursor material;
preferably, the doping element comprises any one or a combination of at least two of Al, mg, zn, ti, na, li, sn or Nb.
3. The positive electrode precursor material according to claim 1 or 2, wherein the second hydroxide precursor material has a chemical formula of Ni a Co b Mn 1-a-b (OH) 2 Wherein 0.2<a≤0.6，0≤b≤0.2。
4. A method of preparing the positive electrode precursor material according to any one of claims 1 to 3, comprising the steps of:
the first main metal mixed salt solution, the precipitator solution and the complexing agent solvent are added into the base solution in parallel flow, the coprecipitation reaction of the first stage is carried out, and after the first target particle size is reached, the first main metal mixed salt solution is replaced by the doping agent solution, and the coprecipitation reaction of the second stage is carried out;
after the second-stage coprecipitation reaction is finished, replacing the dopant solution with a second main metal mixed salt solution, continuing to perform a third-stage coprecipitation reaction, and after the final target particle size is reached, finishing the reaction to obtain the anode precursor material;
the molar content of nickel in the second main metal mixed salt solution is less than the molar content in the first main metal mixed salt solution.
5. The method for producing a positive electrode precursor material according to claim 4, wherein the molar concentration of the main metal element in the first main metal mixed salt solution and the molar concentration of the main metal element in the second main metal mixed salt solution are each independently 1.6 to 2.4mol/L;
preferably, the concentration of the precipitant solution is 9-12 mol/L;
preferably, the precipitant solution comprises an alkaline solution;
preferably, the concentration of the complexing agent solution is 7-10 mol/L;
preferably, the complexing agent solution comprises an aqueous ammonia solution.
6. The method for producing a positive electrode precursor material according to claim 4 or 5, wherein the first target particle diameter is 3 to 9 μm;
preferably, when the molar amount of the doping element in the dopant is 0.05-0.1% of the total molar amount of the total metal elements in the positive electrode precursor material, the coprecipitation reaction in the second stage is ended;
preferably, the final target particle size is 9 to 14 μm;
preferably, the pH value during the coprecipitation reaction is 9-13.
7. The method for producing a positive electrode precursor material according to any one of claims 4 to 6, characterized in that the method for producing comprises the steps of:
adding a first main metal mixed salt solution, a liquid alkali solution and an ammonia water solution into a base solution in parallel, performing a first-stage coprecipitation reaction, replacing the first main metal mixed salt solution with a dopant solution after the first target particle diameter is 3-9 mu m, and performing a second-stage coprecipitation reaction, wherein the molar quantity of doping elements in the dopant is 0.05-0.1% of the total molar quantity of total metal elements in the positive electrode precursor material, and finishing the second-stage coprecipitation reaction;
after the second-stage coprecipitation reaction is finished, replacing the dopant solution with a second main metal mixed salt solution, continuing to perform a third-stage coprecipitation reaction, and after the final target particle size is 9-14 mu m, finishing the reaction to obtain the anode precursor material;
the molar content of nickel in the second main metal mixed salt solution is smaller than the molar content in the first main metal mixed salt solution; the pH value in the coprecipitation reaction process is 9-13.
8. A positive electrode material, wherein the positive electrode is obtained by mixing and sintering the positive electrode precursor material according to any one of claims 1 to 3 and a lithium source.
9. The positive electrode material according to claim 8, wherein the sintered substance is carbon-coated.
10. A lithium ion battery, characterized in that it comprises the positive electrode material according to claim 8 or 9.
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