CN117658239A - Nickel-rich positive electrode precursor and preparation method and application thereof - Google Patents
Nickel-rich positive electrode precursor and preparation method and application thereof Download PDFInfo
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- CN117658239A CN117658239A CN202311660198.1A CN202311660198A CN117658239A CN 117658239 A CN117658239 A CN 117658239A CN 202311660198 A CN202311660198 A CN 202311660198A CN 117658239 A CN117658239 A CN 117658239A
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- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 title claims abstract description 148
- 239000002243 precursor Substances 0.000 title claims abstract description 94
- 229910052759 nickel Inorganic materials 0.000 title claims abstract description 68
- 238000002360 preparation method Methods 0.000 title abstract description 27
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 claims abstract description 64
- 229910052726 zirconium Inorganic materials 0.000 claims abstract description 64
- 239000000463 material Substances 0.000 claims abstract description 47
- 238000005253 cladding Methods 0.000 claims abstract description 30
- 229910052810 boron oxide Inorganic materials 0.000 claims abstract description 22
- JKWMSGQKBLHBQQ-UHFFFAOYSA-N diboron trioxide Chemical compound O=BOB=O JKWMSGQKBLHBQQ-UHFFFAOYSA-N 0.000 claims abstract description 22
- 239000011159 matrix material Substances 0.000 claims abstract description 21
- 239000011247 coating layer Substances 0.000 claims abstract description 7
- 239000010410 layer Substances 0.000 claims abstract description 6
- 239000000243 solution Substances 0.000 claims description 56
- 238000006243 chemical reaction Methods 0.000 claims description 44
- 238000000975 co-precipitation Methods 0.000 claims description 27
- KFDQGLPGKXUTMZ-UHFFFAOYSA-N [Mn].[Co].[Ni] Chemical compound [Mn].[Co].[Ni] KFDQGLPGKXUTMZ-UHFFFAOYSA-N 0.000 claims description 22
- 239000012266 salt solution Substances 0.000 claims description 20
- 238000000034 method Methods 0.000 claims description 17
- 229910052796 boron Inorganic materials 0.000 claims description 16
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 claims description 14
- KGBXLFKZBHKPEV-UHFFFAOYSA-N boric acid Chemical compound OB(O)O KGBXLFKZBHKPEV-UHFFFAOYSA-N 0.000 claims description 14
- 239000004327 boric acid Substances 0.000 claims description 14
- 239000011572 manganese Substances 0.000 claims description 13
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims description 12
- 235000011114 ammonium hydroxide Nutrition 0.000 claims description 12
- 239000002245 particle Substances 0.000 claims description 12
- 239000007774 positive electrode material Substances 0.000 claims description 12
- 238000003756 stirring Methods 0.000 claims description 11
- 239000003513 alkali Substances 0.000 claims description 9
- 239000008139 complexing agent Substances 0.000 claims description 8
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims description 7
- 239000002585 base Substances 0.000 claims description 7
- 238000004519 manufacturing process Methods 0.000 claims description 7
- 239000000126 substance Substances 0.000 claims description 7
- QGZKDVFQNNGYKY-UHFFFAOYSA-N ammonia Natural products N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims description 6
- 150000003754 zirconium Chemical class 0.000 claims description 6
- 239000010406 cathode material Substances 0.000 claims description 5
- 229910052744 lithium Inorganic materials 0.000 claims description 5
- 238000002156 mixing Methods 0.000 claims description 5
- 238000005245 sintering Methods 0.000 claims description 5
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonium chloride Substances [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 claims description 4
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 claims description 4
- 239000007788 liquid Substances 0.000 claims description 4
- 229910001416 lithium ion Inorganic materials 0.000 claims description 4
- 239000012716 precipitator Substances 0.000 claims description 2
- 239000010405 anode material Substances 0.000 abstract description 9
- 238000009826 distribution Methods 0.000 abstract description 9
- 239000011248 coating agent Substances 0.000 description 15
- 238000000576 coating method Methods 0.000 description 13
- 230000000052 comparative effect Effects 0.000 description 13
- ZXAUZSQITFJWPS-UHFFFAOYSA-J zirconium(4+);disulfate Chemical compound [Zr+4].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O ZXAUZSQITFJWPS-UHFFFAOYSA-J 0.000 description 8
- 239000003792 electrolyte Substances 0.000 description 7
- WMFOQBRAJBCJND-UHFFFAOYSA-M Lithium hydroxide Chemical compound [Li+].[OH-] WMFOQBRAJBCJND-UHFFFAOYSA-M 0.000 description 5
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 5
- 239000000843 powder Substances 0.000 description 5
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 4
- -1 boron metal oxide Chemical class 0.000 description 4
- 229910017052 cobalt Inorganic materials 0.000 description 4
- 239000010941 cobalt Substances 0.000 description 4
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 4
- 239000013078 crystal Substances 0.000 description 4
- 229910052748 manganese Inorganic materials 0.000 description 4
- 230000001351 cycling effect Effects 0.000 description 3
- 229910021645 metal ion Inorganic materials 0.000 description 3
- 229910044991 metal oxide Inorganic materials 0.000 description 3
- 239000002562 thickening agent Substances 0.000 description 3
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 238000005336 cracking Methods 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000011267 electrode slurry Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012544 monitoring process Methods 0.000 description 2
- 238000001878 scanning electron micrograph Methods 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 229910013716 LiNi Inorganic materials 0.000 description 1
- 229910017071 Ni0.6Co0.2Mn0.2(OH)2 Inorganic materials 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- 239000002033 PVDF binder Substances 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 230000003213 activating effect Effects 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000002238 attenuated effect Effects 0.000 description 1
- BRTALTYTFFNPAC-UHFFFAOYSA-N boroxin Chemical compound B1OBOBO1 BRTALTYTFFNPAC-UHFFFAOYSA-N 0.000 description 1
- 238000001354 calcination Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000011888 foil Substances 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 230000002427 irreversible effect Effects 0.000 description 1
- 238000002955 isolation Methods 0.000 description 1
- RSNHXDVSISOZOB-UHFFFAOYSA-N lithium nickel Chemical compound [Li].[Ni] RSNHXDVSISOZOB-UHFFFAOYSA-N 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 150000002736 metal compounds Chemical class 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000008188 pellet Substances 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 238000007086 side reaction Methods 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
- 230000006641 stabilisation Effects 0.000 description 1
- 238000011105 stabilization Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
- 230000002195 synergetic effect Effects 0.000 description 1
- 239000011885 synergistic combination Substances 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 nickel-rich positive electrode precursor, and a preparation method and application thereof. The nickel-rich positive electrode precursor comprises a core and a coating layer coated on the surface of the core; the inner core comprises a positive electrode precursor matrix material, boron oxide and zirconium doped in the positive electrode precursor matrix material; the doping amount of zirconium is gradually increased along the direction from the core center to the surface of the positive electrode precursor matrix material; the cladding element in the cladding layer comprises zirconium. According to the invention, boron oxide is directly doped in the precursor, and meanwhile, gradient doping and cladding of zirconium are cooperatively carried out, so that the condition of uneven surface stress distribution of the anode material prepared later is obviously reduced, microcrack generation is reduced, the structure of the material is stabilized, and the safety performance and the electrochemical performance are improved.
Description
Technical Field
The invention belongs to the technical field of lithium ion batteries, and relates to a nickel-rich positive electrode precursor, and a preparation method and application thereof.
Background
In order to meet the high energy requirement of the electric automobile, nickel-rich layered material LiNi 1-x-y Mn x Co y O 2 (x+y is less than or equal to 0.3) (NMC) is considered as the most promising anode candidate material, has the characteristics of high energy, low cost, good safety and the like, shows excellent electrochemical performance, and is expected to become the power battery anode material leading in the future market.
The layered nickel-rich positive electrode material has inherent defects to change the structure along with the increase of the nickel content although the specific capacity is increased, and has great difficulty in industrialized application. In the circulating process of the layered nickel-rich positive electrode material, particularly under special conditions of high pressure, high temperature and the like, oxidized Ni 4+ Can generate side reaction with electrolyte, so that the structure is collapsed and irreversible, and the self impedance of the material is increased, thereby bringing serious safety problem, which is a key for restricting the large-scale application of the material. In addition, the nickel-rich positive electrode material generates lithium-nickel mixed discharge in the reaction process, so that active oxygen is removed to generate a large amount of lithium residues Li on the surface of the material 2 O or LiOH, absorbs a large amount of H when contacting air 2 O/CO 2 A large amount of lithium residues and water are accumulated on the surface of the material, so that the processing performance of the material is greatly influenced, the problem of gas expansion of the material is generated, the cycle performance is attenuated, and finally the electrochemical performance of the whole material is deteriorated to be invalid.
The element doping and the surface coating are effective methods, so that the stability of the material structure and the interface can be improved, but the nickel-rich material obtained by simultaneously modifying the element doping and the surface coating in general industry needs to be implemented by a two-step method, for example, CN111244426A discloses a nickel-rich ternary positive electrode material, a preparation method and a lithium ion battery. The method comprises the following steps: mixing a nickel-rich ternary positive electrode material precursor, a first nano metal compound and lithium source powder and performing first sintering treatment to obtain first powder; mixing the first powder with a first coating agent to obtain a first coating material; performing second sintering treatment on the first cladding material to obtain second powder; mixing the second powder with a second coating agent to obtain a second coating material; performing third sintering treatment on the second coating material to obtain a nickel-rich ternary anode material; the reference uses a multi-step process to prepare the positive electrode material. The preparation process is complicated, and the characteristics of easy water absorption and the like of the nickel-rich material are combined, so that the manufacturing cost of the material is greatly increased, and the performance improvement effect on the nickel-rich positive electrode material is limited.
Therefore, how to improve the safety performance and electrochemical performance of the nickel-rich cathode material, reduce the cost and simplify the preparation process is a technical problem to be solved urgently.
Disclosure of Invention
Aiming at the defects existing in the prior art, the invention aims to provide a nickel-rich positive electrode precursor, and a preparation method and application thereof. According to the invention, boron oxide is directly doped in the precursor, and meanwhile, gradient doping and cladding of zirconium are cooperatively carried out, so that the condition of uneven surface stress distribution of the anode material prepared later is obviously reduced, microcrack generation is reduced, the structure of the material is stabilized, and the safety performance and the electrochemical performance are improved.
In order to achieve the aim of the invention, the invention adopts the following technical scheme:
in a first aspect, the invention provides a nickel-rich positive electrode precursor, which comprises a core and a coating layer coated on the surface of the core; the inner core comprises a positive electrode precursor matrix material, boron oxide and zirconium doped in the positive electrode precursor matrix material; the doping amount of zirconium is gradually increased along the direction from the core center to the surface of the positive electrode precursor matrix material; the cladding element in the cladding layer comprises zirconium.
According to the invention, the boron oxide is directly doped in the precursor, and meanwhile, gradient doping and cladding of zirconium are cooperatively matched, so that the anode material prepared later reacts with metal ions in the precursor to obtain boron metal oxide, the condition of uneven stress distribution on the surface of the material is reduced, microcrack generation is reduced, gradient increasing doping of zirconium improves the stability of atoms in a material lattice, and zirconium cladding avoids direct contact between a ternary precursor and electrolyte, thus improving the cycling stability of the material and improving the safety performance and electrochemical performance.
In the invention, boron oxide is doped in the precursor stage instead of pure boron atoms, so that the stability of atoms in the crystal lattice of the material is improved; if the doping of zirconium is not gradually increased, the problem of cracking and cycle drop of the anode ball can not be solved; the invention realizes the internal stabilization of atoms in crystal lattice by double doping of boron oxide and zirconium, and the zirconium is doped in gradient and cooperates with the cladding of zirconium, and the external isolation of electrolyte realizes the long circulation of the battery; in either case, the positive electrode pellet is cracked and the cycle is lowered.
Preferably, the chemical formula of the positive electrode precursor matrix material is Ni a Co b Mn c (OH) 2 ，0.8≤a<1, b > 0, c > 0, the a may be 0.8, 0.81, 0.82, 0.83, 0.84, 0.85, 0.86, 0.87, 0.88, 0.89, 0.9, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99, or the like; the b may be 0.01, 0.03, 0.5, 0.08, 0.1, 0.13, 0.15, 0.18, 0.19, etc.; the c may be 0.01, 0.03, 0.5, 0.08, 0.1, 0.13, 0.15, 0.18, 0.19, or the like.
Preferably, the total mass of the zirconium is 0.5 to 1% of the mass of the positive electrode precursor base material, for example, 0.5%, 0.55%, 0.6%, 0.65%, 0.7%, 0.75%, 0.8%, 0.85%, 0.9%, 0.95% or 1% or the like.
In the present invention, the total mass of zirconium includes the sum of the doping amount of zirconium and the cladding amount of zirconium.
Preferably, the boron oxide is doped in an amount of 500 to 5000ppm, for example 500ppm, 1000ppm, 1500ppm, 2000ppm, 2500ppm, 3000ppm, 3500ppm, 4000ppm, 4500ppm or 5000ppm, etc.
In the nickel-rich positive electrode precursor material provided by the invention, the doping amount of boron oxide is matched with the total mass of zirconium in a synergistic way; the structure stability and the interface modification are realized together.
In a second aspect, the present invention provides a method for preparing the nickel-rich positive electrode precursor according to the first aspect, the preparation repeatedly comprising the steps of:
adding a nickel-cobalt-manganese mixed salt solution, a boron source solution, a zirconium source solution, a precipitator solution and a complexing agent solution in parallel, performing a first-stage coprecipitation reaction, stopping adding the nickel-cobalt-manganese mixed salt solution and the boron source solution after the target particle size is reached, and continuing performing a second-stage coprecipitation reaction to obtain the nickel-rich anode precursor;
wherein, during the coprecipitation reaction of the first stage, the adding amount of the zirconium source is gradually increased.
The preparation method provided by the invention can realize the doping and coating of the positive electrode precursor by a one-step method, and is bulk doping and coating, thus preparing the nickel-rich material with the structure and the interface modified simultaneously, simplifying the production process and being suitable for mass production.
Preferably, the concentration of the nickel cobalt manganese mixed salt solution is 50-150 g/L, such as 50g/L, 60g/L, 70g/L, 80g/L, 90g/L, 100g/L, 110g/L, 120g/L, 130g/L, 140g/L or 150g/L, etc.
Preferably, the boron source has a concentration of 1 to 10g/L, for example 1g/L, 2g/L, 3g/L, 4g/L, 5g/L, 6g/L, 7g/L, 8g/L, 9g/L, 10g/L, etc.
In the present invention, the nickel cobalt manganese mixed salt solution may be a plurality of salts including, but not limited to, at least one of a nickel cobalt manganese ternary mixed sulfuric acid solution, a nickel cobalt manganese ternary mixed hydrochloric acid solution, a nickel cobalt manganese ternary mixed nitric acid solution, or a combination of at least two thereof.
Preferably, the boron source comprises boric acid.
In the invention, boric acid is used as a reaction raw material, so that uniform doping of boron can be better realized.
Preferably, the concentration of the zirconium source is 1 to 10g/L, for example 1g/L, 2g/L, 3g/L, 4g/L, 5g/L, 6g/L, 7g/L, 8g/L, 9g/L, 10g/L, etc.
Preferably, the zirconium source comprises a zirconium salt.
Preferably, the mass concentration of the precipitant solution is 20-50%, for example 20%, 30%, 40% or 50%, etc.
Preferably, the precipitant solution comprises a liquid alkali solution.
Preferably, the complexing agent solution has a mass concentration of 10-30%, such as 10%, 15%, 20%, 25% or 30%, etc.
Preferably, the complexing agent solution comprises an aqueous ammonia solution.
Preferably, the feeding speed of the nickel cobalt manganese mixed salt solution is 6-10L/h, for example 6L/h, 7L/h, 8L/h, 9L/h or 10L/h, etc.
Preferably, the feed rate of the boron source solution is 1 to 3L/h, for example 1L/h, 2L/h, 3L/h, or the like.
Preferably, the zirconium source solution is fed at a rate of 0.3 to 1L/h, such as 0.3L/h, 0.4L/h, 0.5L/h, 0.6L/h, 0.7L/h, 0.8L/h, 0.9L/h, 1L/h, or the like.
Preferably, the feed rate of the precipitant solution is 2 to 3L/h, for example 2L/h, 2.3L/h, 2.5L/h, 2.8L/h or 3L/h, etc.
Preferably, the complexing agent solution is fed at a rate of 0.6 to 1L/h, for example 0.6L/h, 0.7L/h, 0.8L/h, 0.9L/h or 1L/h, etc.
Preferably, the D50 of the target particle diameter is 9 to 10 μm, for example 9 μm, 9.1 μm, 9.2 μm, 9.3 μm, 9.4 μm, 9.5 μm, 9.6 μm, 9.7 μm, 9.8 μm or 10 μm, etc.
Preferably, the temperature of the first stage coprecipitation reaction and the temperature of the second stage coprecipitation reaction are each independently 30 to 80 ℃, for example 30 ℃, 40 ℃, 50 ℃, 60 ℃, 70 ℃, 80 ℃, or the like.
Preferably, the pH of the first stage coprecipitation reaction and the pH of the second stage coprecipitation reaction are each independently 10 to 12, e.g. 10, 10.3, 10.5, 10.8, 11, 11.3, 11.5, 11.8 or 12, etc.
Preferably, the stirring rate of the first-stage coprecipitation reaction and the stirring rate of the second-stage coprecipitation reaction are each independently 100 to 500r/min, for example 100r/min, 150r/min, 200r/min, 250r/min, 300r/min, 350r/min, 400r/min, 450r/min, 500r/min or the like.
As a preferred technical scheme, the preparation method comprises the following steps:
adding a nickel-cobalt-manganese mixed salt solution with a feeding speed of 6-10L/h, a boric acid solution with a feeding speed of 1-3L/h, a zirconium salt solution with a feeding speed of 0.3-1L/h, a liquid alkali solution with a feeding speed of 2-3L/h and an ammonia water solution with a feeding speed of 0.6-1L/h in parallel, keeping a pH value of 10-12 at 30-80 ℃, carrying out a first-stage coprecipitation reaction at a stirring rate of 100-500 r/min, stopping adding the nickel-cobalt-manganese mixed salt solution and the boron source solution after reaching a target particle size D50 of 9-10 mu m, keeping a pH value of 10-12 at 30-80 ℃, and continuing the second-stage coprecipitation reaction at a stirring rate of 100-500 r/min to obtain the nickel-rich positive electrode precursor;
wherein, in the coprecipitation reaction process of the first stage, the adding amount of the zirconium source is gradually increased; the concentration of the nickel-cobalt-manganese mixed salt solution is 50-150 g/L; the concentration of boric acid is 1-10 g/L; the concentration of the zirconium salt is 1-10 g/L; the mass concentration of the aqueous alkali solution is 20-50%; the mass concentration of the ammonia water solution is 10-30%.
According to the preparation method provided by the invention, the nickel-rich positive electrode precursor material with stable structure and good interface modification is obtained through multi-parameter cooperative matching.
In a third aspect, the present invention provides a nickel-rich cathode material, which is obtained by mixing and sintering the nickel-rich cathode precursor according to the first aspect and a lithium source.
When the nickel-rich precursor material provided by the invention is used for preparing the anode material, the preparation process and specific parameters are conventional technical means.
In a fourth aspect, the present invention also provides a lithium ion battery comprising the nickel-rich cathode material according to the third aspect.
Compared with the prior art, the invention has the following beneficial effects:
(1) According to the invention, the boron oxide is directly doped in the precursor, and meanwhile, gradient doping and cladding of zirconium are cooperatively matched, so that the anode material prepared later reacts with metal ions in the precursor to obtain boron metal oxide, the condition of uneven stress distribution on the surface of the material is reduced, microcrack generation is reduced, gradient increasing doping of zirconium improves the stability of atoms in a material lattice, and zirconium cladding avoids direct contact between a ternary precursor and electrolyte, thus improving the cycling stability of the material and improving the safety performance and electrochemical performance.
(2) The preparation method provided by the invention can realize the doping and coating of the positive electrode precursor by a one-step method, and is bulk doping and coating, thus preparing the nickel-rich material with the structure and the interface modified simultaneously, simplifying the production process and being suitable for mass production.
Drawings
Fig. 1 is an SEM image of the nickel-rich positive electrode precursor provided in example 1.
Fig. 2 is an elemental distribution of Zr in the nickel-rich positive electrode precursor provided in example 1.
Fig. 3 is an elemental distribution profile of B in the nickel-rich positive electrode precursor provided in example 1.
Detailed Description
The technical scheme of the invention is further described by the following specific embodiments. 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 nickel-rich positive electrode precursor, which comprises a core and a coating layer coated on the surface of the core; the inner core comprises a positive electrode precursor matrix material, boron oxide (the doping amount of the boron oxide is 1000 ppm) doped in the positive electrode precursor matrix material and zirconium; doping of zirconium in the direction from the core center to the surface of the positive electrode precursor base materialThe chemical formula of the positive electrode precursor matrix material is Ni 0.83 Co 0.11 Mn 0.06 (OH) 2 The method comprises the steps of carrying out a first treatment on the surface of the The cladding element in the cladding layer comprises zirconium.
The preparation method of the nickel-rich positive electrode precursor comprises the following steps:
(1) Adding a nickel-cobalt-manganese ternary mixed sulfate solution (Ni: co: mn molar ratio is 0.83:0.11:0.06), a liquid-alkali solution with a mass concentration of 30%, 5g/L zirconium sulfate, 5g/L boric acid and an ammonia water solution with a mass concentration of 15% into a reaction kettle with a base solution (the temperature is 50 ℃ C., the ammonia water concentration is 5g/L, pH and 11) at the same time and in parallel at a feed rate of 8L/h, 2.5L/h, 0.3L/h, 2L/h and 0.8L/h respectively;
the method comprises the steps of keeping the pH value at 50 ℃ to be 11, carrying out the coprecipitation reaction of the first stage at the stirring rate of 300r/min, wherein the flow of zirconium sulfate is continuously increased along with the growth of the granularity of a precursor, the doping amount of zirconium is continuously increased from inside to outside, continuously monitoring the granularity, collecting all particles to return to a reaction kettle for continuous reaction and growth by using a high-efficiency thickener in the reaction process before the granularity does not reach the requirement, stopping adding the ternary mixed salt solution of nickel, cobalt and manganese and the boric acid solution when the granularity D50 reaches 9.5 mu m (target granularity), and stopping other normal feeding until the adding amount (the total mass of the doping amount and the cladding amount) of zirconium reaches 1% of the ternary mass, stopping feeding, and continuing the reaction until the material reaction is complete, thereby obtaining the doped cladding ternary precursor.
Fig. 1 shows an SEM image of the nickel-rich positive electrode precursor provided in example 1, and as can be seen from fig. 1, the precursor material provided in the invention has uniform size and good sphericity.
Fig. 2 shows the elemental distribution diagram of Zr in the nickel-rich positive electrode precursor provided in example 1, and it can be seen from fig. 2 that Zr is uniformly doped in the precursor, the doping amount is continuously increased from inside to outside, and a Zr shell of several micrometers is coated on the outside (i.e. the surface layer also has a zirconium coating layer).
Fig. 3 shows an element distribution energy spectrum of B in the nickel-rich positive electrode precursor provided in example 1, and it can be seen from table fig. 3 that boron oxide is uniformly doped in the precursor.
Example 2
The embodiment provides a nickel-rich positive electrode precursor, which comprises a core and a coating layer coated on the surface of the core; the inner core comprises a positive electrode precursor matrix material, boron oxide (the doping amount of the boron oxide is 1500 ppm) doped in the positive electrode precursor matrix material and zirconium; the doping amount of zirconium is gradually increased along the direction from the core center to the surface of the positive electrode precursor matrix material, and the chemical formula of the positive electrode precursor matrix material is Ni 0.83 Co 0.11 Mn 0.06 (OH) 2 The method comprises the steps of carrying out a first treatment on the surface of the The cladding element in the cladding layer comprises zirconium.
The preparation method of the nickel-rich positive electrode precursor comprises the following steps:
(1) Adding 150g/L nickel-cobalt-manganese ternary mixed sulfate solution (Ni: co: mn molar ratio is 0.83:0.11:0.06), 50% aqueous alkali solution, 10g/L zirconium sulfate, 10g/L boric acid and 30% aqueous ammonia solution into a reaction kettle with feed rates of 10L/h, 3L/h, 0.5L/h, 2.5L/h and 1L/h simultaneously and concurrently (at a temperature of 40 ℃ C., aqueous ammonia concentration of 10g/L, pH of 12);
and (3) keeping the pH value at 40 ℃ to be 12, and carrying out the coprecipitation reaction of the first stage at the stirring rate of 200r/min, wherein the flow of zirconium sulfate is continuously increased along with the growth of the granularity of the precursor, the doping amount of zirconium is continuously increased from inside to outside, the particle size is continuously monitored, a high-efficiency thickener is used in the reaction process before the particle size does not reach the requirement, all particles are collected and returned to a reaction kettle to continuously react and grow, when the particle size D50 reaches 9 mu m, the addition of the ternary mixed salt solution of nickel, cobalt and manganese and the boric acid solution is stopped, and other normal feeds are stopped until the addition amount (the total mass of the doping amount and the cladding amount) of zirconium reaches 1% of the ternary mass, and the feeding is stopped, and the reaction is continued until the material is completely reacted, so that the doped cladding ternary precursor is obtained.
Example 3
The embodiment provides a nickel-rich positive electrode precursor, which comprises a core and a coating layer coated on the surface of the core; the core comprises a positive electrode precursor matrix materialAnd boron oxide (the doping amount of boron oxide is 5000 ppm) and zirconium doped in the positive electrode precursor matrix material; the doping amount of zirconium is gradually increased along the direction from the core center to the surface of the positive electrode precursor matrix material, and the chemical formula of the positive electrode precursor matrix material is Ni 0.83 Co 0.11 Mn 0.06 (OH) 2 The method comprises the steps of carrying out a first treatment on the surface of the The cladding element in the cladding layer comprises zirconium.
The preparation method of the nickel-rich positive electrode precursor comprises the following steps:
(1) Adding 50g/L nickel-cobalt-manganese ternary mixed sulfate solution (Ni: co: mn molar ratio is 0.83:0.11:0.06), 20% aqueous alkali solution, 1g/L zirconium sulfate, 1g/L boric acid and 10% aqueous ammonia solution into a reaction kettle at the feed rates of 6L/h, 1L/h, 0.3L/h, 1L/h and 0.6L/h simultaneously and concurrently (at the temperature of 60 ℃ C., the aqueous ammonia concentration of 1g/L, pH of 10);
the method comprises the steps of keeping the pH value at 60 ℃ to be 10, carrying out the coprecipitation reaction of the first stage at the stirring rate of 100r/min, wherein the flow of zirconium sulfate is continuously increased along with the growth of the granularity of a precursor, the doping amount of zirconium is continuously increased from inside to outside, continuously monitoring the granularity, collecting all particles to return to a reaction kettle for continuous reaction growth by using a high-efficiency thickener in the reaction process before the granularity does not reach the requirement, stopping adding a nickel-cobalt-manganese ternary mixed salt solution and a boric acid solution when the granularity D50 reaches 9 mu m, and stopping other normal feeds until the doping amount (the total mass of the doping amount and the cladding amount) of zirconium reaches 1% of the ternary mass, and stopping feeding, and continuing the reaction until the material is completely reacted to obtain the doped cladding ternary precursor.
Example 4
The difference between this example and example 1 is that the chemical formula of the positive electrode precursor base material in this example is Ni 0.9 Co 0.05 Mn 0.05 (OH) 2 。
In the preparation method, the ternary mixed sulfate solution of nickel, cobalt and manganese is prepared, wherein the molar ratio of Ni to Co to Mn is 0.9 to 0.05.
The remaining preparation methods and parameters were consistent with example 1.
Example 5
The difference between this example and example 1 is that the chemical formula of the positive electrode precursor base material in this example is Ni 0.6 Co 0.2 Mn 0.2 (OH) 2 。
In the preparation method, the ternary mixed sulfate solution of nickel, cobalt and manganese is prepared, wherein the molar ratio of Ni to Co to Mn is 0.6:0.2:0.2.
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 this comparative example provides a nickel-rich positive electrode precursor that is undoped with boroxine.
In the preparation method, boric acid is not added.
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 zirconium in the nickel-rich positive electrode precursor provided in this comparative example was not gradient doped.
In the preparation method, the feeding flow rate of the zirconium sulfate is kept unchanged.
The remaining preparation methods and parameters were consistent with example 1.
Comparative example 3
The difference between this comparative example and example 1 is that the nickel-rich positive electrode precursor provided in this comparative example is not doped with zirconium, nor is it coated with zirconium.
In the preparation method, zirconium sulfate is not added.
The remaining preparation methods and parameters were consistent with example 1.
The nickel-rich positive electrode precursors provided in examples 1 to 5 and comparative examples 1 to 3 were mixed with lithium hydroxide in a molar ratio of Li: M (M is a metal element) =1.05, and calcined at a calcination temperature of 800 ℃ for 13 hours in an air atmosphere, to obtain a positive electrode material.
And taking the positive electrode materials provided in the examples 1-5 and the comparative examples 1-3 as positive electrode active materials, adding NMP into the positive electrode active materials, wherein the mass ratio of PVDF to SP is 95:3:2, so as to obtain positive electrode slurry, and coating the positive electrode slurry on the surface of an aluminum foil so as to obtain the positive electrode plate.
And (3) taking the lithium sheet as a counter electrode, and assembling the lithium sheet with the positive electrode sheet to obtain the button cell.
Electrochemical performance tests were performed on the button cells provided in examples 1-5 and comparative examples 1-3 under the following conditions: after the battery is assembled and aged for 12 hours, the charge and discharge tests with different potentials are carried out. Activating for 3 circles under the voltage of 3-4.3V and the multiplying power of 0.1C, and then circulating for 200 circles under the condition of 2C to obtain the circulating specific capacity and the capacity retention rate. The test results are shown in table 1.
TABLE 1
From the data results of examples 1, 4 and 5, the synergistic combination of doping and cladding is more beneficial to improving the cycle stability of the nickel-rich material, and the performance improvement is not obvious under the medium-low nickel condition.
From the data results of examples and comparative examples 1-3, it can be seen that the nickel-rich positive electrode precursor material provided by the invention ensures the stability of atoms in the crystal lattice of the material if boron oxide is not doped; if the gradient increasing doping of zirconium is not carried out, the problem of cracking and cycle drop of the anode ball cannot be solved; if zirconium doping and coating are not carried out, the effect of isolating electrolyte and protecting anode materials cannot be achieved; namely, the atoms in the internal stable crystal lattice can be commonly realized only by the cooperative coordination of the boron oxide and the zirconium, and the electrolyte is isolated from the outside, so that the purpose of long circulation of the battery is realized.
In summary, the doping and coating of the positive electrode precursor can be realized only by a one-step method, and the nickel-rich material with simultaneously modified structure and interface is prepared for bulk doping and coating; the boron oxide is directly doped in the precursor, and meanwhile, gradient doping and cladding of zirconium are cooperatively matched, so that the anode material prepared later reacts with metal ions in the precursor to obtain boron metal oxide, the condition of uneven stress distribution on the surface of the material is reduced, microcrack generation is reduced, the gradient increasing doping of zirconium improves the stability of atoms in a material lattice, and the zirconium cladding avoids direct contact between a ternary precursor and electrolyte, improves the cycling stability of the material, and improves the safety performance and the electrochemical performance.
The applicant declares that the above is only a specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and it should be apparent to those skilled in the art that any changes or substitutions that are easily conceivable within the technical scope of the present invention disclosed by the present invention fall within the scope of the present invention and the disclosure.
Claims (10)
1. The nickel-rich positive electrode precursor is characterized by comprising a core and a coating layer coated on the surface of the core; the inner core comprises a positive electrode precursor matrix material, boron oxide and zirconium doped in the positive electrode precursor matrix material; the doping amount of zirconium is gradually increased along the direction from the core center to the surface of the positive electrode precursor matrix material; the cladding element in the cladding layer comprises zirconium.
2. The nickel-rich positive electrode precursor according to claim 1, wherein the positive electrode precursor base material has a chemical formula of Ni a Co b Mn c (OH) 2 ，0.8≤a<1，b＞0，c＞0。
3. The nickel-rich positive electrode precursor according to claim 1 or 2, wherein the total mass of zirconium is 0.5 to 1% of the mass of the positive electrode precursor base material;
preferably, the doping amount of the boron oxide is 500-5000 ppm.
4. A method of preparing a nickel-rich positive electrode precursor according to any one of claims 1-3, wherein the preparing repeatedly comprises the steps of:
adding a nickel-cobalt-manganese mixed salt solution, a boron source solution, a zirconium source solution, a precipitator solution and a complexing agent solution in parallel, performing a first-stage coprecipitation reaction, stopping adding the nickel-cobalt-manganese mixed salt solution and the boron source solution after the target particle size is reached, and continuing performing a second-stage coprecipitation reaction to obtain the nickel-rich anode precursor;
wherein, during the coprecipitation reaction of the first stage, the adding amount of the zirconium source is gradually increased.
5. The method for preparing a nickel-rich positive electrode precursor according to claim 4, wherein the concentration of the nickel-cobalt-manganese mixed salt solution is 50-150 g/L;
preferably, the concentration of the boron source is 1-10 g/L;
preferably, the boron source comprises boric acid;
preferably, the concentration of the zirconium source is 1-10 g/L;
preferably, the zirconium source comprises a zirconium salt;
preferably, the mass concentration of the precipitant solution is 20-50%;
preferably, the precipitant solution comprises a liquid alkali solution;
preferably, the mass concentration of the complexing agent solution is 10-30%;
preferably, the complexing agent solution comprises an aqueous ammonia solution.
6. The method for preparing a nickel-rich positive electrode precursor according to claim 4 or 5, wherein the feeding speed of the nickel-cobalt-manganese mixed salt solution is 6-10L/h;
preferably, the feeding speed of the boron source solution is 1-3L/h;
preferably, the feeding speed of the zirconium source solution is 0.3-1L/h;
preferably, the feeding speed of the precipitant solution is 2-3L/h;
preferably, the complexing agent solution is fed at a rate of 0.6 to 1L/h.
7. The method for producing a nickel-rich positive electrode precursor according to any one of claims 4 to 6, wherein the D50 of the target particle diameter is 9 to 10 μm;
preferably, the temperature of the first-stage coprecipitation reaction and the temperature of the second-stage coprecipitation reaction are each independently 30 to 80 ℃;
preferably, the pH value of the first-stage coprecipitation reaction and the pH value of the second-stage coprecipitation reaction are each independently 10 to 12;
preferably, the stirring rate of the coprecipitation reaction in the first stage and the stirring rate of the coprecipitation reaction in the second stage are each independently 100 to 500r/min.
8. The method for producing a nickel-rich positive electrode precursor according to any one of claims 4 to 7, comprising the steps of:
adding a nickel-cobalt-manganese mixed salt solution with a feeding speed of 6-10L/h, a boric acid solution with a feeding speed of 1-3L/h, a zirconium salt solution with a feeding speed of 0.3-1L/h, a liquid alkali solution with a feeding speed of 2-3L/h and an ammonia water solution with a feeding speed of 0.6-1L/h in parallel, keeping a pH value of 10-12 at 30-80 ℃, carrying out a first-stage coprecipitation reaction at a stirring rate of 100-500 r/min, stopping adding the nickel-cobalt-manganese mixed salt solution and the boron source solution after reaching a target particle size D50 of 9-10 mu m, keeping a pH value of 10-12 at 30-80 ℃, and continuing the second-stage coprecipitation reaction at a stirring rate of 100-500 r/min to obtain the nickel-rich positive electrode precursor;
wherein, in the coprecipitation reaction process of the first stage, the adding amount of the zirconium source is gradually increased; the concentration of the nickel-cobalt-manganese mixed salt solution is 50-150 g/L; the concentration of boric acid is 1-10 g/L; the concentration of the zirconium salt is 1-10 g/L; the mass concentration of the aqueous alkali solution is 20-50%; the mass concentration of the ammonia water solution is 10-30%.
9. A nickel-rich cathode material, wherein the nickel-rich cathode material is obtained by mixing and sintering the nickel-rich cathode precursor according to any one of claims 1-3 and a lithium source.
10. A lithium ion battery comprising the nickel-rich positive electrode material of claim 9.
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