CN114604909B - Grafted positive electrode material precursor and preparation method and application thereof - Google Patents

Grafted positive electrode material precursor and preparation method and application thereof Download PDF

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CN114604909B
CN114604909B CN202210330355.1A CN202210330355A CN114604909B CN 114604909 B CN114604909 B CN 114604909B CN 202210330355 A CN202210330355 A CN 202210330355A CN 114604909 B CN114604909 B CN 114604909B
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electrode material
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CN114604909A (en
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赵孝连
方刚
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Guizhou Gaodian Technology Co ltd
Gaodian Shenzhen Technology Co ltd
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    • C01GCOMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
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    • C01G53/006Compounds containing, besides nickel, two or more other elements, with the exception of oxygen or hydrogen
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    • C01G53/50Nickelates containing alkali metals, e.g. LiNiO2 containing manganese of the type [MnO2]n-, e.g. Li(NixMn1-x)O2, Li(MyNixMn1-x-y)O2
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00Secondary cells; Manufacture thereof
    • H01M10/05Accumulators with non-aqueous electrolyte
    • H01M10/052Li-accumulators
    • H01M10/0525Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
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    • H01M4/02Electrodes composed of, or comprising, active material
    • H01M4/36Selection of substances as active materials, active masses, active liquids
    • H01M4/48Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/485Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy
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    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00Electrodes
    • H01M4/02Electrodes composed of, or comprising, active material
    • H01M4/36Selection of substances as active materials, active masses, active liquids
    • H01M4/48Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/50Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
    • H01M4/505Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00Electrodes
    • H01M4/02Electrodes composed of, or comprising, active material
    • H01M4/36Selection of substances as active materials, active masses, active liquids
    • H01M4/48Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
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Abstract

The invention provides a grafted positive electrode material precursor and a preparation method thereof, wherein the structural formula of the precursor is A (OH) 2 ‑R‑B(OH) 2 A and B are Ni 1‑a‑b Co a Mn b Z c Wherein a is more than or equal to 0 and less than or equal to 1; b is more than or equal to 0 and less than or equal to 1; a+b is more than 0 and less than or equal to 1; c is more than or equal to 0 and less than or equal to 1, the molar ratio of nickel, cobalt and manganese in A is different from the molar ratio of nickel, cobalt and manganese in B, and Z is at least one of Al, mg, ti, B, zr, bi, mo, P, F and rare earth elements; r is a grafting agent comprising at least one element of Ni, co, mn, al, mg, si, ti, B, zr, bi, mo, P and rare earth elements. Compared with the prior art, the precursor is grafted at the precursor end, so that the aim of uniformly mixing different types of materials is fulfilled, and the problems of uneven slurry dispersion, poor pole piece uniformity and inconsistent electrochemical performance of the materials existing in the existing mixed anode material are solved.

Description

Grafted positive electrode material precursor and preparation method and application thereof
Technical Field
The invention relates to the field of lithium batteries, in particular to a grafted positive electrode material precursor, a preparation method and application thereof.
Background
Lithium ion batteries are increasingly used in everyday life. Currently, the positive electrode materials of lithium ion batteries mainly comprise lithium cobaltate, lithium manganate, lithium iron phosphate, lithium nickel cobalt manganate and the like. Different types of positive electrode materials have different electrochemical performances and are matched with different application scenes.
Along with the continuous expansion of application scenes of lithium ion batteries, the lithium ion batteries manufactured by a single positive electrode material have difficulty in meeting the requirements of various subdivision fields in terms of performance and cost. The mixing of multiple positive electrode materials (typically two) generally achieves a balance of cost control and performance requirements. The current common method is to directly mix several positive electrode materials according to different proportions according to the requirements. However, this method still has the following problems: 1) A slurry mixing process problem of the mixed material; 2) The dispersion uniformity of the anode material in the pole piece is improved; 3) The lithium removal and insertion behaviors of different materials under the same voltage in the charge and discharge process have the influence on the stability of the pole piece structure and the consistency of macroscopic electrical performance of the battery.
In view of the foregoing, it is necessary to provide a solution to the above-mentioned problems.
Disclosure of Invention
One of the objects of the present invention is: the precursor of the grafted positive electrode material is provided to solve the problems of uneven slurry dispersion, poor uniformity of a pole piece and inconsistent electrochemical performance of the material existing in the mixed use of various positive electrode materials in the current application process of the lithium ion battery.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
A grafted positive electrode material precursor has a structural formula of A (OH) 2 -R-B(OH) 2 A and B are Ni 1-a- b Co a Mn b Z c Wherein a is more than or equal to 0 and less than or equal to 1; b is more than or equal to 0 and less than or equal to 1; a+b is more than 0 and less than or equal to 1; c is more than or equal to 0 and less than or equal to 1, the molar ratio of nickel, cobalt and manganese in A is different from the molar ratio of nickel, cobalt and manganese in B, and Z is at least one of Al, mg, ti, B, zr, bi, mo, P, F and rare earth elements; r is a grafting agent comprising at least one element of Ni, co, mn, al, mg, si, ti, B, zr, bi, mo, P and rare earth elements.
Preferably, the mass of R is A (OH) 2 And B (OH) 2 1 to 10 percent of the sum of the mass.
Preferably, A (OH) 2 And B (OH) 2 The mass ratio of (2) is 1:99-99:1.
Preferably, R is (M x N y )CO 3 Or (M) x N y )(OH) 2 X is more than 0 and less than 1; y is more than 0 and less than 1; x+y is more than 0 and less than or equal to 1; m and N are selected from different elements, and are at least one element of Ni, co, mn, al, mg, si, ti, B, zr, bi, mo, P and rare earth elements.
The second object of the present invention is: the preparation method of the grafted positive electrode material precursor comprises the following steps:
s1, mixing an aqueous solution containing nickel salt, cobalt salt, manganese salt and Z salt with an aqueous hydroxide solution for reactionControlling the pH of the solution in the reaction process to be 10-13, aging, and suction-filtering to obtain a first hydroxide salt A (OH) 2
S2, mixing an aqueous solution containing nickel salt, cobalt salt, manganese salt and Z salt with an aqueous solution of hydroxide for reaction, controlling the pH of the solution in the reaction process to be 10-13, aging, and suction-filtering to obtain a second hydroxide type salt B (OH) 2
S3, subjecting the first hydroxide form salt A (OH) 2 And a salt of the second hydroxide form B (OH) 2 Mixing at 25-70 deg.c to prepare slurry; adding a solution for liquid phase reaction to form a grafting agent R into the slurry, stirring and reacting for 30-90 min, washing and drying to obtain a grafted positive electrode material precursor A (OH) 2 -R-B(OH) 2
Preferably, in step S1, the first hydroxide form salt A (OH) 2 The preparation method of (2) comprises the following steps: adding aqueous solution containing nickel salt, cobalt salt, manganese salt and Z salt and hydroxide aqueous solution into a reactor containing water at a speed of 1-2 mL/min respectively, continuously stirring and reacting at 30-80 ℃ in an inert atmosphere, controlling the pH of the solution in the reaction process to be 10-13, continuously stirring and aging for 10-36 h after the addition, and vacuum-filtering to obtain first hydroxide salt A (OH) 2
Preferably, in step S2, the salt of the second hydroxide form B (OH) 2 The preparation method of (2) comprises the following steps: adding aqueous solution containing nickel salt, cobalt salt, manganese salt and Z salt and hydroxide aqueous solution into a reactor containing water at a speed of 1-2 mL/min respectively, continuously stirring and reacting at 30-80 ℃ in an inert atmosphere, controlling the pH of the solution in the reaction process to be 10-13, continuously stirring and aging for 10-36 h after the addition, and vacuum filtering to obtain second hydroxide salt B (OH) 2
Preferably, in step S3, the solution for the liquid phase reaction to form the grafting agent R comprises a first solution and a second solution, the first solution is a mixed solution of cobalt salt and manganese salt, the second solution is sodium bicarbonate solution or sodium hydroxide solution, and the first solution and the second solution form the grafting agent R by the liquid phase reaction to form the first hydroxide-type salt A (OH) 2 And a salt of the second hydroxide form B (OH) 2 Grafting is performed.
Preferably, in step S3, the first solution and the second solution are pumped into the slurry at the rates of 0.5mL/min and 3.5mL/min respectively for pre-reaction, and then the remaining first solution and second solution are pumped into the slurry for continuous stirring reaction, and washed and dried to obtain the grafted positive electrode material precursor a (OH) 2 -R-B(OH) 2
The third object of the present invention is to provide a preparation method of the grafted positive electrode material, which comprises mixing the precursor of the grafted positive electrode material with lithium salt, sintering at 750-950 ℃ for 6-24 hours, cooling, and grinding to obtain the grafted positive electrode material.
Preferably, the sintering conditions are: firstly, heating to 750-800 ℃ at the speed of 5-7 ℃/min, and preserving heat for 2-6 h; then heating to 900-950 ℃ at the speed of 2-6 ℃/min, and preserving heat for 10-24 h.
The fourth object of the present invention is to provide a grafted positive electrode material prepared by the above-mentioned preparation method of a grafted positive electrode material.
The fifth object of the present invention is to provide a positive electrode sheet comprising the above-mentioned graft type positive electrode material.
The invention aims at providing a lithium ion battery, which comprises a positive plate, a negative plate and a diaphragm which is arranged between the positive plate and the negative plate, wherein the positive plate is the positive plate.
Compared with the prior art, the invention has the beneficial effects that: the hydroxide type salt grafted hydroxide type salt positive electrode material precursor provided by the invention achieves the aim of uniformly mixing different types of materials through a precursor end grafting mode, namely, two hydroxide type positive electrode material precursors are coupled together through a chemical method under the action of a grafting agent to form a brand new and stable positive electrode material precursor. The novel grafting type precursor is used for preparing the cathode material, and two different types of cathode materials are fused and grown into a whole to form the grafting type cathode material, so that the problem of uneven dispersion of mixed components in the process of preparing slurry by the grafting type cathode material is avoided, the problem of segregation of the mixed components in a pole piece does not exist, the same potential exists in electrochemistry, and the problems of uneven dispersion of slurry, poor uniformity of the pole piece and inconsistent electrochemical performance of the material existing in the mixed use of various cathode materials in the current lithium ion battery application are solved. Meanwhile, as different types of positive electrode materials have different electrochemical properties, the preparation method of the grafted precursor can design and prepare the positive electrode material with specific properties.
Drawings
Fig. 1 is an SEM image of a grafted cathode material precursor according to example 1 of the present invention.
Fig. 2 is an XRD pattern of a grafted positive electrode material precursor of example 1 of the present invention.
Fig. 3 is an SEM image of the graft type cathode material of example 1 of the present invention.
Fig. 4 is an XRD pattern of the graft type cathode material of example 1 of the present invention.
Fig. 5 is an SEM image of a grafted positive electrode material precursor of example 4 of the present invention.
Fig. 6 is an XRD pattern of the grafted positive electrode material precursor of example 4 of the present invention.
Fig. 7 is an SEM image of the graft type cathode material of example 4 of the present invention.
Fig. 8 is an XRD pattern of the graft type cathode material of example 4 of the present invention.
Detailed Description
1. Grafted positive electrode material precursor
The first aspect of the present invention is directed to a grafted positive electrode material precursor having the structural formula A (OH) 2 -R-B(OH) 2 A and B are Ni 1-a-b Co a Mn b Z c Wherein a is more than or equal to 0 and less than or equal to 1; b is more than or equal to 0 and less than or equal to 1; a+b is more than 0 and less than or equal to 1; c is more than or equal to 0 and less than or equal to 1, the molar ratio of nickel, cobalt and manganese in A is different from the molar ratio of nickel, cobalt and manganese in B, and Z is at least one of Al, mg, ti, B, zr, bi, mo, P, F and rare earth elements; r is a grafting agent comprising at least one element of Ni, co, mn, al, mg, si, ti, B, zr, bi, mo, P and rare earth elements.
Wherein, the mole ratio of nickel, cobalt and manganese in A includes but is not limited to 1:1: 1. 5:2: 3. 6:2: 2. 8:1: 1. 6:1:3, the specific adjustment can also be carried out according to the requirement, such as 55:15:30. the doping amount of the element Z in the A can be adjusted according to the weight ratio of the A by selecting at least one of Al, mg, ti, B, zr, bi, mo, P, F and rare earth elements according to the requirement, and is preferably less than 1% of the weight of the A, and more preferably 0.05-0.5% of the weight of the A.
Likewise, the molar ratio of nickel, cobalt, manganese in B includes, but is not limited to, 1:1: 1. 5:2: 3. 6:2: 2. 8:1: 1. 6:1:3, the specific adjustment can also be carried out according to the requirement, such as 55:15:30. the doping amount of the element Z in the B can be adjusted according to the weight ratio of the B by selecting at least one of Al, mg, ti, B, zr, bi, mo, P, F and rare earth elements according to the requirement, and is preferably less than 1% of the weight of the B, and more preferably 0.05-0.5% of the weight of the B.
Specifically, the grafted positive electrode material precursor includes, but is not limited to (Ni 0.5 Co 0.2 Mn 0.3 )(OH) 2 -R-(Ni 1/ 3 Co 1/3 Mn 1/3 )(OH) 2 、(Ni 0.5 Co 0.2 Mn 0.3 )(OH) 2 -R-Co(OH) 2 、((i 0.5 Co 0.2 Mn 0.3 )(OH) 2 -R-Ni 0.6 Co 0.4 (OH) 2 、(Ni 0.5 Co 0.2 Mn 0.3 )(OH) 2 -R-Ni 0.6 Mn 0.4 (OH) 2 、(Ni 1/3 Co 1/3 Mn 1/3 )(OH) 2 -R-Co(OH) 2 、(Ni 0.5 Co 0.2 Mn 0.3 )(OH) 2 -R-Co 0.8 Mn 0.2 (OH) 2 、(Ni 0.6 Co 0.2 Mn 0.2 )(OH) 2 -R-(Ni 1/3 Co 1/3 Mn 1/3 )(OH) 2 、(Ni 0.5 Co 0.2 Mn 0.3 )(OH) 2 -R-(Ni 0.6 Co 0.2 Mn 0.2 )(OH) 2 Any one of the following.
The grafting agent R can be at least one of hydroxide, carbonate, oxide and phosphate. I.e. at least one of the hydroxide, carbonate, oxide, phosphate should be comprised of Ni, co, mn, al, mg, ti, B, zr, bi, mo, P, rare earth elements, such as CoCO 3 、MnPO 4 、Co(OH) 2 Etc.
Preferably, the grafting agent R is (M x N y )CO 3 Or (M) x N y )(OH) 2 X is more than 0 and less than 1; y is more than 0 and less than 1; x+y is more than 0 and less than or equal to 1; m and N are selected from different elements, and are at least one element of Ni, co, mn, al, mg, si, ti, B, zr, bi, mo, P and rare earth elements. Specifically included but not limited to (Co 0.5 Mn 0.5 )CO 3 、(Ni 0.5 Mn 0.5 )CO 3 、(Co 0.5 Mn 0.5 )(OH) 2 And (Ni) 0.5 Mn 0.5 )(OH) 2 . With grafting agent (Co) 0.5 Mn 0.5 )CO 3 And (Ni) 0.5 Mn 0.5 )CO 3 For example, the corresponding grafted positive electrode material precursor may be (Ni 0.5 Co 0.2 Mn 0.3 )(OH) 2 -(Co 0.5 Mn 0.5 )CO 3 -(Ni 1/3 Co 1/3 Mn 1/3 )(OH) 2 、(Ni 0.5 Co 0.2 Mn 0.3 )(OH) 2 -(Co 0.5 Mn 0.5 )CO 3 -Co(OH) 2 、(Ni 0.5 Co 0.2 Mn 0.3 )(OH) 2 -(Co 0.5 Mn 0.5 )CO 3 -Ni 0.6 Co 0.4 (OH) 2 、(Ni 0.5 Co 0.2 Mn 0.3 )(OH) 2 -(Ni 0.5 Mn 0.5 )CO 3 -Ni 0.6 Mn 0.4 (OH) 2 、(Ni 1/3 Co 1/3 Mn 1/3 )(OH) 2 -(Ni 0.5 Mn 0.5 )CO 3 -Co(OH) 2 、(Ni 0.5 Co 0.2 Mn 0.3 )(OH) 2 -(Ni 0.5 Mn 0.5 )CO 3 -Co 0.8 Mn 0.2 (OH) 2 、(Ni 0.6 Co 0.2 Mn 0.2 )(OH) 2 -(Co 0.5 Mn 0.5 )CO 3 -(Ni 1/3 Co 1/3 Mn 1/3 )(OH) 2 、(Ni 0.5 Co 0.2 Mn 0.3 )(OH) 2 -(Co 0.5 Mn 0.5 )CO 3 -(Ni 0.6 Co 0.2 Mn 0.2 )(OH) 2 Any one of the following.
The invention preferentially achieves the aim of uniformly mixing different types of positive electrode material precursors in a mode of grafting at a precursor end, adopts the grafted precursor to prepare the positive electrode material for fusion growth of different types of positive electrode materials, ensures the consistency of the positive electrode material particles in electrochemical performance, such as the same potential and the like, and ensures the excellent effects of the subsequently obtained lithium ion battery in polarization resistance, cycle stability, high temperature performance and safety performance.
The grafting agent adopted by the invention is a component part of the positive electrode material, and can be used as a functional doping agent, so that the grafting agent with proper dosage does not negatively influence the structure and the performance of the final positive electrode material.
The grafted positive electrode material precursor provided by the invention is easier to realize the secondary ball grafted single-crystal positive electrode material.
In some embodiments, the R has a mass of A (OH) 2 And B (OH) 2 1 to 10 percent of the sum of the mass. The quality of the grafting agent R is controlled within the range, so that on one hand, the reduction of the content of effective active substances (the reduction of the mass specific capacity after the grafting agent R is prepared into the positive electrode material) caused by the excessive content of the grafting agent R is avoided, and on the other hand, the coupling fusion of the grafting material A and the grafting material B which cannot be ensured due to the insufficient content of the grafting agent R is avoided. Preferably, the mass of R is A (OH) 2 And B (OH) 2 The sum of the mass is 2 to 5%, and specifically may be any of 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5% and 2 to 5%. The grafting agent with 2-5% can couple the grafting material A and the grafting material B together well through chemical method, so as to obtain the positive electrode material precursor with stable structure, which can be shown in figures 1-2 and 5-6.
In some embodiments, A (OH) 2 And B (OH) 2 Mass ratio of (2)Is 1:99-99:1, and can be specifically adjusted according to actual requirements. Preferably, the first hydroxide form salt A (OH) 2 And a salt of the second hydroxide form B (OH) 2 The mass ratio of (2) can be 20:80-80:20. Specifically, the first hydroxide form salt A (OH) 2 And a salt of the second hydroxide form B (OH) 2 The mass ratio of (c) may be 20:80, 30:70, 40:60, 50:50, 60:40, 70:30 or 80:20, such as in 100g mass of the first hydroxide form salt a (OH) 2 80g of a salt of the second hydroxide form B (OH) 2 Is 20g; or a salt of the first hydroxide form A (OH) 2 Is 60g, the second hydroxide form salt B (OH) 2 Mass of 40g, etc.
The second aspect of the present invention is directed to a method for preparing the grafted positive electrode material precursor, comprising the steps of:
s1, mixing an aqueous solution containing nickel salt, cobalt salt, manganese salt and Z salt with an aqueous solution of hydroxide for reaction, controlling the pH of the solution in the reaction process to be 10-13, aging, and suction-filtering to obtain a first hydroxide type salt A (OH) 2
S2, mixing an aqueous solution containing nickel salt, cobalt salt, manganese salt and Z salt with an aqueous solution of hydroxide for reaction, controlling the pH of the solution in the reaction process to be 10-13, aging, and suction-filtering to obtain a second hydroxide type salt B (OH) 2
S3, subjecting the first hydroxide form salt A (OH) 2 And a salt of the second hydroxide form B (OH) 2 Mixing at 25-70 deg.c to prepare slurry; adding a solution for liquid phase reaction to form a grafting agent R into the slurry, stirring the mixture to react for 30 to 90 minutes, washing and drying the mixture to obtain a grafted positive electrode material precursor A (OH) 2 -R-B(OH) 2
According to the preparation method provided by the invention, hydroxide type salt particles are prepared respectively, then two hydroxide type salt particles are mixed to prepare slurry, and the mixture is carried out at the temperature of 25-70 ℃ so as to be more beneficial to subsequent grafting reaction; then adding a solution for liquid phase reaction to form grafting agent R to the slurry (the added solution can be used for forming grafting agent R by liquid phase reaction), and controlling the reaction time so that two hydroxide type salt particles are arranged in the grafting agentAre linked together by action to form A (OH) 2 -R-B(OH) 2 The structure is a novel positive electrode material precursor with a grafted structure.
In some embodiments, in step S1, the first hydroxide form salt A (OH) 2 The preparation method of (2) comprises the following steps: adding aqueous solution containing nickel salt, cobalt salt, manganese salt and Z salt and hydroxide aqueous solution into a reactor containing water at a speed of 1-2 mL/min respectively, continuously stirring and reacting at 30-80 ℃ in an inert atmosphere, controlling the pH of the solution in the reaction process to be 10-13, continuously stirring and aging for 10-36 h after the addition, and vacuum-filtering to obtain first hydroxide salt A (OH) 2
In some embodiments, in step S2, the second hydroxide form salt B (OH) 2 The preparation method of (2) comprises the following steps: adding aqueous solution containing nickel salt, cobalt salt, manganese salt and Z salt and hydroxide aqueous solution into a reactor containing water at a speed of 1-2 mL/min respectively, continuously stirring and reacting at 30-80 ℃ in an inert atmosphere, controlling the pH of the solution in the reaction process to be 10-13, continuously stirring and aging for 10-36 h after the addition, and vacuum filtering to obtain second hydroxide salt B (OH) 2
In some embodiments, in step S3, the solution for the liquid phase reaction to form grafting agent R comprises a first solution that is a mixed solution of cobalt salt and manganese salt and a second solution that is a sodium bicarbonate solution or sodium hydroxide solution, the first and second solutions forming grafting agent R by the liquid phase reaction to form the first hydroxide form salt A (OH) 2 And a salt of the second hydroxide form B (OH) 2 Grafting is performed. The second solution mainly enables cobalt and manganese in the first solution to perform coprecipitation reaction, so that a product grafting agent R is obtained through the reaction, and the grafting material A and the grafting material B are coupled together through bridging action of the grafting agent R. Preferably, the molar ratio of cobalt salt to manganese salt in the first solution is 1:1, and the grafting is performed by adopting a mixed solution, so that the experiment proves that the grafting material A and the grafting material B have better bonding effect.
In some embodiments, in step S3, the first solvent is first dissolvedPumping the liquid and the second solution into the slurry at the rates of 0.5mL/min and 3.5mL/min respectively for pre-reaction, pumping the rest of the first solution and the second solution into the slurry for continuous stirring and reaction, and washing and drying to obtain a grafted positive electrode material precursor A (OH) 2 -R-B(OH) 2 . Firstly, pumping a part of solution into the slurry by controlling the flow rate to perform a pre-grafting reaction, and then pumping the rest of grafted solution into the slurry to stir and react, so that the grafting effect of two hydroxide salts can be further ensured, and the consistency of the electrochemical performance of the subsequent positive electrode material is ensured.
2. Grafted positive electrode material
The third aspect of the invention aims to provide a preparation method of a grafted positive electrode material, which comprises the steps of mixing a precursor of the grafted positive electrode material with lithium salt, sintering for 6-24 hours at 750-950 ℃, cooling and grinding to obtain the grafted positive electrode material.
In some embodiments, the sintering conditions are: firstly, heating to 750-800 ℃ at the speed of 5-7 ℃/min, and preserving heat for 2-6 h; then heating to 900-950 ℃ at the speed of 2-6 ℃/min, and preserving heat for 10-24 h. Preferably, the sintering conditions are: firstly, heating to 760 ℃ at the speed of 6 ℃/min, and preserving heat for 4 hours; then heating to 920 ℃ at the speed of 3 ℃/min, and preserving heat for 12 hours.
A fourth aspect of the present invention is directed to providing a grafted positive electrode material, such as LiNi, prepared by the method for preparing a grafted positive electrode material 0.5 Co 0.2 Mn 0.3 O 2 -LiNi 1/3 Co 1/3 Mn 1/3 O 2 、LiNi 0.5 Co 0.2 Mn 0.3 O 2 -LiCoO 2
3. Positive plate
A fifth aspect of the present invention is directed to a positive electrode sheet comprising the above-described graft type positive electrode material.
The positive plate comprises a positive current collector and a positive active layer coated on at least one surface of the positive current collector, wherein the positive active material in the positive active layer is the grafted positive material. The grafted positive electrode material is mixed with a binder and a conductive agent to prepare slurry, and then the slurry is coated on a positive electrode current collector, and the positive electrode plate is obtained after drying.
4. Lithium ion battery
The sixth aspect of the present invention is directed to a lithium ion battery, which includes a positive electrode sheet, a negative electrode sheet, and a separator spaced between the positive electrode sheet and the negative electrode sheet, where the positive electrode sheet is the positive electrode sheet described above.
The active material coated on the negative electrode sheet can be one or more of graphite, soft carbon, hard carbon, carbon fiber, mesophase carbon microsphere, silicon-based material, tin-based material, lithium titanate or other metals capable of forming alloy with lithium. Wherein, the graphite can be selected from one or more of artificial graphite, natural graphite and modified graphite; the silicon-based material can be one or more selected from simple substance silicon, silicon oxygen compound, silicon carbon compound and silicon alloy; the tin-based material can be selected from one or more of elemental tin, tin oxide and tin alloy. While the negative current collector used for the negative electrode sheet is generally a structure or a part for collecting current, the negative current collector may be various materials suitable for use as a negative current collector of a lithium ion battery in the field, for example, the negative current collector may be a metal foil, etc., and more specifically may include a copper foil, etc.
And the separator may be a variety of materials suitable for lithium ion battery separators in the art, for example, may be a combination of one or more of polyethylene, polypropylene, polyvinylidene fluoride, aramid, polyethylene terephthalate, polytetrafluoroethylene, polyacrylonitrile, polyimide, polyamide, polyester, natural fibers, and the like.
The lithium ion battery also includes an electrolyte comprising an organic solvent, an electrolyte lithium salt, and an additive. Wherein the electrolyte lithium salt can be LiPF used in high-temperature electrolyte 6 And/or LiBOB; liBF used in the low-temperature electrolyte may be used 4 、LiBOB、LiPF 6 At least one of (a) and (b); liBF used in the overcharge-preventing electrolyte may also be used 4 、LiBOB、LiPF 6 At least one of LiTFSI; liClO may also be 4 、LiAsF 6 、LiCF 3 SO 3 、LiN(CF 3 SO 2 ) 2 At least one of them. And the organic solvent may be a cyclic carbonate, including PC, EC; chain carbonates, including DFC, DMC, or EMC; carboxylic esters, including MF, MA, EA, MP, and the like, are also contemplated. And additives include, but are not limited to, film forming additives, conductive additives, flame retardant additives, overcharge prevention additives, and control of H in electrolytes 2 At least one of an additive for O and HF content, an additive for improving low temperature performance, and a multifunctional additive.
In order to make the technical scheme and advantages of the present invention more apparent, the present invention and its advantageous effects will be described in further detail below with reference to the detailed description and the accompanying drawings, but the embodiments of the present invention are not limited thereto.
Example 1
Preparation method of grafted positive electrode material with structural formula LiNi 0.5 Co 0.2 Mn 0.3 O 2 -LiNi 1/3 Co 1/3 Mn 1/ 3 O 2 . Wherein the structural formula of the precursor is (Ni 0.5 Co 0.2 Mn 0.3 )(OH) 2 -(Co 0.5 Mn 0.5 )CO 3 -(Ni 1/3 Co 1/3 Mn 1/3 )(OH) 2
The preparation method of the grafted positive electrode material precursor comprises the following steps:
S1、(Ni 0.5 Co 0.2 Mn 0.3 )(OH) 2 (i.e., NCM 523-OH) precursor preparation: preparing NiSO according to a molar ratio of 5:2:3 4 、CoSO 4 、MnSO 4 Is (Ni) 2+ 、Co 2+ 、Mn 2+ Is 2 mol.L -1 ) 500mL, labeled solution 1; formulation of 4mol L -1 Is marked as solution 2; solution 1 and solution 2 were fed into a five-neck flask reactor with 100mL of deionized water at a rate of about 1mL/min by a peristaltic pump and reacted with stirring, and N was introduced during the reaction 2 Protecting and keeping the reaction temperature at 30-80 ℃ and stirring at 500rpm/min; simultaneously controlling the pH value of the solution in the reaction process to be 10-13 by dropwise adding ammonia water; at the position ofContinuously stirring for 24 hours after the addition of the solution 1 and the solution 2 is finished so as to age; after the aging is finished, carrying out vacuum suction filtration on the obtained precipitate to obtain a first hydroxide type salt NCM523-OH;
S2、(Ni 1/3 Co 1/3 Mn 1/3 )(OH) 2 (i.e., NCM 111-OH) precursor preparation: preparing NiSO according to a molar ratio of 1:1:1 4 、CoSO 4 、MnSO 4 Is (Ni) 2+ 、Co 2+ 、Mn 2+ Is 2 mol.L -1 ) 500mL, labeled solution 1; formulation of 4mol L -1 Is marked as solution 2; solution 1 and solution 2 were fed into a five-neck flask reactor with 100mL of deionized water at a rate of about 1mL/min by a peristaltic pump and reacted with stirring, and N was introduced during the reaction 2 Protecting and keeping the reaction temperature at 30-80 ℃ and stirring at 500rpm/min; simultaneously controlling the pH value of the solution in the reaction process to be 10-13 by dropwise adding ammonia water; continuing stirring for 24 hours after the addition of the solution 1 and the solution 2 is finished so as to age; after the aging is finished, carrying out vacuum suction filtration on the obtained precipitate to obtain a second hydroxide type salt NCM111-OH;
s3, preparing a grafted positive electrode material precursor: 16g of NCM523-OH and 4g of NCM111-OH are weighed, dispersed in 50g of deionized water and stirred at 60 ℃ to prepare a slurry; preparing a solution (for generating grafting agent R by liquid phase reaction): comprises a first solution (CoSO 4 :MnSO 4 Molar ratio 1: 1) At a concentration of 2mol/L, where CoSO 4 And MnSO 4 The sum of the mass of the precursor of the positive electrode material is 5 percent, and the second solution NaHCO 3 The concentration is 1mol/L; pumping the first solution and the second solution into the slurry at the rates of 0.5mL/min and 3.5mL/min respectively, reacting for 30min, pumping the rest of the first solution and the second solution into the slurry, continuously stirring and reacting for 30min, washing, filtering and drying the slurry to obtain a grafted positive electrode material precursor NCM523-OH, namely grafted NCM111-OH, denoted as NCM523-OH- (Co0.5Mn0.5) CO 3 -NCM111-OH(4:1)。
The obtained grafted positive electrode material precursor is used for preparing a positive electrode material, and the preparation steps are as follows:
s4, obtaining NCM523-OH- (Co0.5Mn0.5) CO 3 -NCM111-OH(41) and Li 2 CO 3 According to a metal/Li molar ratio of 1:1.05, mechanically mixing, loading the obtained mixture into a sagger, putting the sagger into a muffle furnace, heating to 760 ℃ at a speed of 6 ℃/min under the air atmosphere, and preserving heat for 2 hours; heating to 920 ℃ at a speed of 3 ℃/min, and preserving heat for 12 hours; cooling to room temperature along with a furnace after solid-phase sintering, and grinding to obtain a grafted anode material LiNi 0.5 Co 0.2 Mn 0.3 O 2 -LiNi 1/3 Co 1/3 Mn 1/3 O 2
Example 2
Unlike example 1, the preparation step S3 of the grafted positive electrode material precursor.
S3, preparing a grafted positive electrode material precursor: 16g of NCM523-OH and 8g of NCM111-OH are weighed, dispersed in 50g of deionized water and stirred at 60 ℃ to prepare a slurry; other solutions were formulated (for the production of grafting agent R by liquid phase reaction): comprises a first solution (CoSO 4 :MnSO 4 Molar ratio 1: 1) At a concentration of 2mol/L, where CoSO 4 And MnSO 4 The sum of the mass of the precursor of the positive electrode material is 5 percent, and the second solution NaHCO 3 The concentration is 1mol/L; pumping the first solution and the second solution into the slurry at the rates of 0.5mL/min and 3.5mL/min respectively, reacting for 30min, pumping the rest of the first solution and the second solution into the slurry, continuously stirring and reacting for 30min, washing, filtering and drying the slurry to obtain a grafted positive electrode material precursor NCM523-OH, namely grafted NCM111-OH, which is marked as NCM523-OH- (Co) 0.5 Mn 0.5 )CO 3 -NCM111-OH(2:1)。
The remainder is the same as embodiment 1 and will not be described here again.
Example 3
Unlike example 1, the preparation step S3 of the grafted positive electrode material precursor.
S3, preparing a grafted positive electrode material precursor: 24g of NCM523-OH and 4g of NCM111-OH are weighed, dispersed in 50g of deionized water and stirred at 60 ℃ to prepare a slurry; other solutions were formulated (for the production of grafting agent R by liquid phase reaction): comprises a first solution (CoSO 4 :MnSO 4 Molar ratio 1: 1) At a concentration of 2mol/L, where CoSO 4 And MnSO 4 The sum of the mass of the precursor of the positive electrode material is 3 percent, and the second solution NaHCO 3 The concentration is 1mol/L; pumping the first solution and the second solution into the slurry at the rates of 0.5mL/min and 3.5mL/min respectively, reacting for 30min, pumping the rest of the first solution and the second solution into the slurry, continuously stirring and reacting for 30min, washing, filtering and drying the slurry to obtain a grafted positive electrode material precursor NCM523-OH, namely grafted NCM111-OH, which is marked as NCM523-OH- (Co) 0.5 Mn 0.5 )CO 3 -NCM111-OH(6:1)。
The remainder is the same as embodiment 1 and will not be described here again.
Example 4
Preparation method of grafted positive electrode material with structural formula LiNi 0.5 Co 0.2 Mn 0.3 O 2 -LiCoO 2 Wherein the structural formula of the precursor is (Ni 0.5 Co 0.2 Mn 0.3 )(OH) 2 -(Co 0.5 Mn 0.5 )CO 3 -Co(OH) 2
The preparation method of the grafted positive electrode material precursor comprises the following steps:
S1、(Ni 0.5 Co 0.2 Mn 0.3 )(OH) 2 (i.e., NCM 523-OH) precursor preparation: preparing NiSO according to a molar ratio of 5:2:3 4 、CoSO 4 、MnSO 4 Is (Ni) 2+ 、Co 2+ 、Mn 2+ Is 2 mol.L -1 ) 500mL, labeled solution 1; formulation of 4mol L -1 Is marked as solution 2; solution 1 and solution 2 were fed into a five-neck flask reactor with 100mL of deionized water at a rate of about 1mL/min by a peristaltic pump and reacted with stirring, and N was introduced during the reaction 2 Protecting and keeping the reaction temperature at 30-80 ℃ and stirring at 500rpm/min; simultaneously controlling the pH value of the solution in the reaction process to be 10-13 by dropwise adding ammonia water; continuing stirring for 24 hours after the addition of the solution 1 and the solution 2 is finished so as to age; after the aging is finished, carrying out vacuum suction filtration on the obtained precipitate to obtain a first hydroxide type salt NCM523-OH;
S2、Co(OH) 2 precursor preparation: preparation of 2mol x L -1 CoSO of (2) 4 500mL of aqueous solution, labeled solution 1; formulation of 4mol L -1 Is marked as solution 2; solution 1 and solution 2 were fed into a five-neck flask reactor with 100mL of deionized water at a rate of about 1mL/min by a peristaltic pump and reacted with stirring, and N was introduced during the reaction 2 Protecting and keeping the reaction temperature at 30-80 ℃ and stirring at 500rpm/min; simultaneously controlling the pH value of the solution in the reaction process to be 10-13 by dropwise adding ammonia water; continuing stirring for 24 hours after the addition of the solution 1 and the solution 2 is finished so as to age; after the aging is completed, the obtained precipitate is filtered in vacuum to obtain a second hydroxide type salt Co (OH) 2
S3, preparing a grafted positive electrode material precursor: 16g of NCM523-OH and 4g of Co (OH) were weighed out 2 Dispersing in 50g deionized water, and stirring at 60 ℃ to prepare slurry; other solutions were formulated (for the production of grafting agent R by liquid phase reaction): comprises a first solution (CoSO 4 :MnSO 4 Molar ratio 1: 1) At a concentration of 2mol/L, where CoSO 4 And MnSO 4 The sum of the mass of the precursor of the positive electrode material is 5 percent, and the second solution NaHCO 3 The concentration is 1mol/L; pumping the first solution and the second solution into the slurry at the rates of 0.5mL/min and 3.5mL/min respectively, reacting for 30min, pumping the rest first solution and the second solution into the slurry, continuously stirring and reacting for 30min, washing, filtering and drying the slurry to obtain a grafted positive electrode material precursor NCM523-OH grafted Co (OH) 2 Is marked as NCM523-OH- (Co) 0.5 Mn 0.5 )CO 3 -Co(OH) 2 (4:1)。
The obtained grafted positive electrode material precursor is used for preparing a positive electrode material, and the preparation steps are as follows:
s4, obtaining NCM523-OH- (Co) 0.5 Mn 0.5 )CO 3 -Co(OH) 2 (4:1) and Li 2 CO 3 According to a metal/Li molar ratio of 1:1.05, mechanically mixing, loading the obtained mixture into a sagger, putting the sagger into a muffle furnace, heating to 760 ℃ at a speed of 6 ℃/min under the air atmosphere, and preserving heat for 2 hours; heating to 920 ℃ at a speed of 3 ℃/min, and preserving heat for 12 hours; cooling to room temperature along with a furnace after solid-phase sintering, and grinding to obtain a grafted anode material LiNi 0.5 Co 0.2 Mn 0.3 O 2 -LiCoO 2
Example 5
Unlike example 4, the preparation step S3 of the grafted positive electrode material precursor.
S3, preparing a grafted positive electrode material precursor: 16g of NCM523-OH and 8g of Co (OH) were weighed out 2 Dispersing in 50g deionized water, and stirring at 60 ℃ to prepare slurry; preparing a solution (for generating grafting agent R by liquid phase reaction): comprises a first solution (CoSO 4 :MnSO 4 Molar ratio 1: 1) At a concentration of 2mol/L, where CoSO 4 And MnSO 4 The sum of the mass of the precursor of the positive electrode material is 5 percent, and the second solution NaHCO 3 The concentration is 1mol/L; pumping the first solution and the second solution into the slurry at the rates of 0.5mL/min and 3.5mL/min respectively, reacting for 30min, pumping the rest first solution and the second solution into the slurry, continuously stirring and reacting for 30min, washing, filtering and drying the slurry to obtain a grafted positive electrode material precursor NCM523-OH grafted Co (OH) 2 Is marked as NCM523-OH- (Co) 0.5 Mn 0.5 )CO 3 -Co(OH) 2 (2:1)。
The remainder is the same as embodiment 4 and will not be described here again.
Example 6
Unlike example 4, the preparation step S3 of the grafted positive electrode material precursor.
S3, preparing a grafted positive electrode material precursor: 24g of NCM523-OH and 4g of Co (OH) were weighed out 2 Dispersing in 100g deionized water, and stirring at 60 ℃ to prepare slurry; preparing a solution (for generating grafting agent R by liquid phase reaction): comprises a first solution (NiSO 4 :MnSO 4 Molar ratio 1: 1) The concentration is 2mol/L, wherein, niSO 4 And MnSO 4 The sum of the mass of the precursor of the positive electrode material is 5 percent, and the second solution NaHCO 3 The concentration is 1mol/L; pumping the first solution and the second solution into the slurry at the rates of 0.5mL/min and 3.5mL/min respectively, reacting for 30min, pumping the rest first solution and the second solution into the slurry, continuously stirring and reacting for 30min, washing, filtering and drying the slurry to obtain a grafted positive electrode material precursor NCM523-OHGrafted Co (OH) 2 Is marked as NCM523-OH- (Ni) 0.5 Mn 0.5 )CO 3 -Co(OH) 2 (6:1)。
The remainder is the same as embodiment 4 and will not be described here again.
Example 7
Preparation method of grafted positive electrode material with structural formula LiNi 0.5 Co 0.2 Mn 0.3 O 2 -LiNi 0.6 Co 0.2 Mn 0.2 O 2 . Wherein the structural formula of the precursor is (Ni 0.5 Co 0.2 Mn 0.3 )(OH) 2 -(Co 0.5 Mn 0.5 )CO 3 -(Ni 0.6 Co 0.2 Mn 0.2 )(OH) 2
The preparation method of the grafted positive electrode material precursor comprises the following steps:
S1、(Ni 0.5 Co 0.2 Mn 0.3 )(OH) 2 (i.e., NCM 523-OH) precursor preparation: preparing NiSO according to a molar ratio of 5:2:3 4 、CoSO 4 、MnSO 4 Is (Ni) 2+ 、Co 2+ 、Mn 2+ Is 2 mol.L -1 ) 500mL, labeled solution 1; formulation of 4mol L -1 Is marked as solution 2; solution 1 and solution 2 were fed into a five-neck flask reactor with 100mL of deionized water at a rate of about 1mL/min by a peristaltic pump and reacted with stirring, and N was introduced during the reaction 2 Protecting and keeping the reaction temperature at 30-80 ℃ and stirring at 500rpm/min; simultaneously controlling the pH value of the solution in the reaction process to be 10-13 by dropwise adding ammonia water; continuing stirring for 24 hours after the addition of the solution 1 and the solution 2 is finished so as to age; after the aging is finished, carrying out vacuum suction filtration on the obtained precipitate to obtain a first hydroxide type salt NCM523-OH;
S2、(Ni 0.6 Co 0.2 Mn 0.2 )(OH) 2 (i.e., NCM 622-OH) precursor preparation: preparing NiSO according to a molar ratio of 6:2:2 4 、CoSO 4 、MnSO 4 Is (Ni) 2+ 、Co 2+ 、Mn 2+ Is 2 mol.L -1 ) 500mL, labeled solution 1; formulation of 4mol L -1 Is marked by NaOH solution 500mLIs solution 2; solution 1 and solution 2 were fed into a five-neck flask reactor with 100mL of deionized water at a rate of about 1mL/min by a peristaltic pump and reacted with stirring, and N was introduced during the reaction 2 Protecting and keeping the reaction temperature at 30-80 ℃ and stirring at 500rpm/min; simultaneously controlling the pH value of the solution in the reaction process to be 10-13 by dropwise adding ammonia water; continuing stirring for 24 hours after the addition of the solution 1 and the solution 2 is finished so as to age; after the aging is completed, the obtained precipitate is vacuum filtered to obtain a second hydroxide type salt NCM622-OH.
S3, preparing a grafted positive electrode material precursor: 16g of NCM523-OH and 4g of NCM622-OH are weighed, dispersed in 50g of deionized water and stirred at 60 ℃ to prepare a slurry; preparing a solution (for generating grafting agent R by liquid phase reaction): comprises a first solution (CoSO 4 :MnSO 4 Molar ratio 1: 1) At a concentration of 2mol/L, where CoSO 4 And MnSO 4 The sum of the mass of the precursor of the positive electrode material is 5 percent, and the second solution NaHCO 3 The concentration is 1mol/L; pumping the first solution and the second solution into the slurry at the rates of 0.5mL/min and 3.5mL/min respectively, reacting for 30min, pumping the rest of the first solution and the second solution into the slurry, continuously stirring and reacting for 30min, washing, filtering and drying the slurry to obtain a grafted positive electrode material precursor NCM523-OH grafted with NCM622-OH, namely NCM523-OH- (Co0.5Mn0.5) CO 3 -NCM622-OH(4:1)。
The obtained grafted positive electrode material precursor is used for preparing a positive electrode material, and the preparation steps are as follows:
s4, obtaining NCM523-OH- (Co0.5Mn0.5) CO 3 NCM622-OH (4:1) with Li 2 CO 3 According to a metal/Li molar ratio of 1:1.05, mechanically mixing, loading the obtained mixture into a sagger, putting the sagger into a muffle furnace, heating to 760 ℃ at a speed of 6 ℃/min under the air atmosphere, and preserving heat for 2 hours; heating to 920 ℃ at a speed of 3 ℃/min, and preserving heat for 12 hours; cooling to room temperature along with a furnace after solid-phase sintering, and grinding to obtain a grafted anode material LiNi 0.5 Co 0.2 Mn 0.3 O 2 -LiNi 0.6 Co 0.2 Mn 0.2 O 2
Example 8
Preparation method of grafted positive electrode material with structural formula LiNi 0.6 Co 0.2 Mn 0.2 O 2 -LiNi 1/3 Co 1/3 Mn 1/ 3 O 2 . Wherein the structural formula of the precursor is (Ni 0.6 Co 0.2 Mn 0.6 )(OH) 2 -(Co 0.5 Mn 0.5 )CO 3 -(Ni 1/3 Co 1/3 Mn 1/3 )(OH) 2
The preparation method of the grafted positive electrode material precursor comprises the following steps:
S1、S1、(Ni 0.6 Co 0.2 Mn 0.2 )(OH) 2 (i.e., NCM 622-OH) precursor preparation: preparing NiSO according to a molar ratio of 6:2:2 4 、CoSO 4 、MnSO 4 Is (Ni) 2+ 、Co 2+ 、Mn 2+ Is 2 mol.L -1 ) 500mL, labeled solution 1; formulation of 4mol L -1 Is marked as solution 2; solution 1 and solution 2 were fed into a five-neck flask reactor with 100mL of deionized water at a rate of about 1mL/min by a peristaltic pump and reacted with stirring, and N was introduced during the reaction 2 Protecting and keeping the reaction temperature at 30-80 ℃ and stirring at 500rpm/min; simultaneously controlling the pH value of the solution in the reaction process to be 10-13 by dropwise adding ammonia water; continuing stirring for 24 hours after the addition of the solution 1 and the solution 2 is finished so as to age; after the aging is finished, carrying out vacuum suction filtration on the obtained precipitate to obtain a first hydroxide type salt NCM622-OH;
S2、(Ni 1/3 Co 1/3 Mn 1/3 )(OH) 2 (i.e., NCM 111-OH) precursor preparation: preparing NiSO according to a molar ratio of 1:1:1 4 、CoSO 4 、MnSO 4 Is (Ni) 2+ 、Co 2+ 、Mn 2+ Is 2 mol.L -1 ) 500mL, labeled solution 1; formulation of 4mol L -1 Is marked as solution 2; solution 1 and solution 2 were fed into a five-neck flask reactor with 100mL of deionized water at a rate of about 1mL/min by a peristaltic pump and reacted with stirring, and N was introduced during the reaction 2 Protecting and keeping the reaction temperature at 30-80 ℃ and stirring at 500rpm/min; at the same time by drippingAmmonia water is added to control the pH value of the solution in the reaction process to be 10-13; continuing stirring for 24 hours after the addition of the solution 1 and the solution 2 is finished so as to age; after the aging is finished, carrying out vacuum suction filtration on the obtained precipitate to obtain a second hydroxide type salt NCM111-OH;
s3, preparing a grafted positive electrode material precursor: 4g of NCM622-OH and 16g of NCM111-OH are weighed, dispersed in 50g of deionized water and stirred at 60 ℃ to prepare a slurry; preparing a solution (for generating grafting agent R by liquid phase reaction): comprises a first solution (CoSO 4 :MnSO 4 Molar ratio 1: 1) At a concentration of 2mol/L, where CoSO 4 And MnSO 4 The sum of the mass of the precursor of the positive electrode material is 5 percent, and the second solution NaHCO 3 The concentration is 1mol/L; pumping the first solution and the second solution into the slurry at the rates of 0.5mL/min and 3.5mL/min respectively, reacting for 30min, pumping the rest of the first solution and the second solution into the slurry, continuously stirring and reacting for 30min, washing, filtering and drying the slurry to obtain a grafted positive electrode material precursor NCM622-OH grafted NCM111-OH, namely NCM622-OH- (Co0.5Mn0.5) CO 3 -NCM111-OH(1:4)。
The obtained grafted positive electrode material precursor is used for preparing a positive electrode material, and the preparation steps are as follows:
s4, obtaining NCM622-OH- (Co0.5Mn0.5) CO 3 NCM111-OH (1:4) with Li 2 CO 3 According to a metal/Li molar ratio of 1:1.05, mechanically mixing, loading the obtained mixture into a sagger, putting the sagger into a muffle furnace, heating to 760 ℃ at a speed of 6 ℃/min under the air atmosphere, and preserving heat for 2 hours; heating to 920 ℃ at a speed of 3 ℃/min, and preserving heat for 12 hours; cooling to room temperature along with a furnace after solid-phase sintering, and grinding to obtain a grafted anode material LiNi 0.6 Co 0.2 Mn 0.6 O 2 -LiNi 1/3 Co 1/3 Mn 1/3 O 2
Example 9
Preparation method of grafted positive electrode material with structural formula LiNi 0.5 Co 0.2 Mn 0.3 O 2 -LiNi 0.6 Co 0.4 O 2 . Wherein the structural formula of the precursor is (Ni 0.5 Co 0.2 Mn 0.3 )(OH) 2 -(Co 0.5 Mn 0.5 )CO 3 -(Ni 0.6 Co 0.4 )(OH) 2
The preparation method of the grafted positive electrode material precursor comprises the following steps:
S1、(Ni 0.5 Co 0.2 Mn 0.3 )(OH) 2 (i.e., NCM 523-OH) precursor preparation: preparing NiSO according to a molar ratio of 5:2:3 4 、CoSO 4 、MnSO 4 Is (Ni) 2+ 、Co 2+ 、Mn 2+ Is 2 mol.L -1 ) 500mL, labeled solution 1; formulation of 4mol L -1 Is marked as solution 2; solution 1 and solution 2 were fed into a five-neck flask reactor with 100mL of deionized water at a rate of about 1mL/min by a peristaltic pump and reacted with stirring, and N was introduced during the reaction 2 Protecting and keeping the reaction temperature at 30-80 ℃ and stirring at 500rpm/min; simultaneously controlling the pH value of the solution in the reaction process to be 10-13 by dropwise adding ammonia water; continuing stirring for 24 hours after the addition of the solution 1 and the solution 2 is finished so as to age; after the aging is finished, carrying out vacuum suction filtration on the obtained precipitate to obtain a first hydroxide type salt NCM523-OH;
S2、Ni 0.6 Co 0.4 (OH) 2 (i.e., niCo-OH) precursor preparation: preparing NiSO according to a molar ratio of 6:4 4 、CoSO 4 Is (Ni) 2+ 、Co 2+ Is 2 mol.L -1 ) 500mL, labeled solution 1; formulation of 4mol L -1 Is marked as solution 2; solution 1 and solution 2 were fed into a five-neck flask reactor with 100mL of deionized water at a rate of about 1mL/min by a peristaltic pump and reacted with stirring, and N was introduced during the reaction 2 Protecting and keeping the reaction temperature at 30-80 ℃ and stirring at 500rpm/min; simultaneously controlling the pH value of the solution in the reaction process to be 10-13 by dropwise adding ammonia water; continuing stirring for 24 hours after the addition of the solution 1 and the solution 2 is finished so as to age; after the aging is finished, carrying out vacuum suction filtration on the obtained precipitate to obtain a second hydroxide type salt NiCo-OH;
s3, preparing a grafted positive electrode material precursor: 16g of NCM523-OH and 4g of NiCo-OH were weighed, dispersed in 50g of deionized water and stirred at 60 ℃Stirring to prepare slurry; other solutions were formulated (for the production of grafting agent R by liquid phase reaction): comprises a first solution (CoSO 4 :MnSO 4 Molar ratio 1: 1) At a concentration of 2mol/L, where CoSO 4 And MnSO 4 The sum of the mass of the precursor of the positive electrode material is 5 percent, and the second solution NaHCO 3 The concentration is 1mol/L; pumping the first solution and the second solution into the slurry at the rates of 0.5mL/min and 3.5mL/min respectively, reacting for 30min, pumping the rest of the first solution and the second solution into the slurry, continuously stirring and reacting for 30min, washing, filtering and drying the slurry to obtain a grafted cathode material precursor NCM523-OH grafted NiCo-OH, namely NCM523-OH- (Co0.5Mn0.5) CO 3 -NiCo-OH(4:1)。
The obtained grafted positive electrode material precursor is used for preparing a positive electrode material, and the preparation steps are as follows:
s4, obtaining NCM523-OH- (Co0.5Mn0.5) CO 3 -NiCo-OH (4:1) with Li 2 CO 3 According to a metal/Li molar ratio of 1:1.05, mechanically mixing, loading the obtained mixture into a sagger, putting the sagger into a muffle furnace, heating to 760 ℃ at a speed of 6 ℃/min under the air atmosphere, and preserving heat for 2 hours; heating to 920 ℃ at a speed of 3 ℃/min, and preserving heat for 12 hours; cooling to room temperature along with a furnace after solid-phase sintering, and grinding to obtain a grafted anode material LiNi 0.5 Co 0.2 Mn 0.3 O 2 -LiNi 0.6 Co 0.4 O 2
Example 10
Preparation method of grafted positive electrode material with structural formula LiNi 0.5 Co 0.2 Mn 0.3 O 2 -LiNi 0.6 Mn 0.4 O 2 . Wherein the structural formula of the precursor is (Ni 0.5 Co 0.2 Mn 0.3 )(OH) 2 -(Co 0.5 Mn 0.5 )CO 3 -(Ni 0.6 Mn 0.4 )(OH) 2
The preparation method of the grafted positive electrode material precursor comprises the following steps:
S1、(Ni 0.5 Co 0.2 Mn 0.3 )(OH) 2 (i.e., NCM 523-OH) precursor preparation: is prepared according to the mol ratio of 5:2:3NiSO 4 、CoSO 4 、MnSO 4 Is (Ni) 2+ 、Co 2+ 、Mn 2+ Is 2 mol.L -1 ) 500mL, labeled solution 1; formulation of 4mol L -1 Is marked as solution 2; solution 1 and solution 2 were fed into a five-neck flask reactor with 100mL of deionized water at a rate of about 1mL/min by a peristaltic pump and reacted with stirring, and N was introduced during the reaction 2 Protecting and keeping the reaction temperature at 30-80 ℃ and stirring at 500rpm/min; simultaneously controlling the pH value of the solution in the reaction process to be 10-13 by dropwise adding ammonia water; continuing stirring for 24 hours after the addition of the solution 1 and the solution 2 is finished so as to age; after the aging is finished, carrying out vacuum suction filtration on the obtained precipitate to obtain a first hydroxide type salt NCM523-OH;
S2、Ni 0.6 Mn 0.4 (OH) 2 (i.e., niMn-OH) precursor preparation: preparing NiSO according to a molar ratio of 6:4 4 、CoSO 4 Is (Ni) 2+ 、Co 2+ Is 2 mol.L -1 ) 500mL, labeled solution 1; formulation of 4mol L -1 Is marked as solution 2; solution 1 and solution 2 were fed into a five-neck flask reactor with 100mL of deionized water at a rate of about 1mL/min by a peristaltic pump and reacted with stirring, and N was introduced during the reaction 2 Protecting and keeping the reaction temperature at 30-80 ℃ and stirring at 500rpm/min; simultaneously controlling the pH value of the solution in the reaction process to be 10-13 by dropwise adding ammonia water; continuing stirring for 24 hours after the addition of the solution 1 and the solution 2 is finished so as to age; after the aging is finished, carrying out vacuum suction filtration on the obtained precipitate to obtain a second hydroxide type salt NiMn-OH;
s3, preparing a grafted positive electrode material precursor: 16g of NCM523-OH and 4g of NiMn-OH are weighed, dispersed in 50g of deionized water and stirred at 60 ℃ to prepare slurry; other solutions were formulated (for the production of grafting agent R by liquid phase reaction): comprises a first solution (CoSO 4 :MnSO 4 Molar ratio 1: 1) At a concentration of 2mol/L, where CoSO 4 And MnSO 4 The sum of the mass of the precursor of the positive electrode material is 5 percent, and the second solution NaHCO 3 The concentration is 1mol/L; the first solution and the second solution are respectively processed at the rates of 0.5mL/min and 3.5mL/min Pumping into the slurry for reaction for 30min, pumping the rest first solution and the second solution into the slurry for continuous stirring reaction for 30min, washing, filtering and drying the slurry to obtain a grafted cathode material precursor NCM523-OH grafted NiMn-OH, namely NCM523-OH- (Co0.5Mn0.5) CO 3 -NiMn-OH-OH(4:1)。
The obtained grafted positive electrode material precursor is used for preparing a positive electrode material, and the preparation steps are as follows:
s4, obtaining NCM523-OH- (Co0.5Mn0.5) CO 3 -NiMn-OH-OH (4:1) with Li 2 CO 3 According to a metal/Li molar ratio of 1:1.05, mechanically mixing, loading the obtained mixture into a sagger, putting the sagger into a muffle furnace, heating to 760 ℃ at a speed of 6 ℃/min under the air atmosphere, and preserving heat for 2 hours; heating to 920 ℃ at a speed of 3 ℃/min, and preserving heat for 12 hours; cooling to room temperature along with a furnace after solid-phase sintering, and grinding to obtain a grafted anode material LiNi 0.5 Co 0.2 Mn 0.3 O 2 -LiNi 0.6 Mn 0.4 O 2
Examples 11 to 14 were prepared by referring to the above preparation method, except that the first hydroxide-type salt and the second hydroxide-type salt were different in composition and content, and the grafting agent was (Ni 0.5 Mn 0.5 )CO 3 The relevant compositions of the hydroxide form salts in examples 1 to 14 are shown in Table 1 below.
TABLE 1
Salt of the first hydroxide form Second hydroxide salt
Example 1 16g NCM523-OH 4g NCM111-OH
Example 2 16g NCM523-OH 8g NCM111-OH
Example 3 24g NCM523-OH 4g NCM111-OH
Example 4 16g NCM523-OH 4g Co(OH) 2
Example 5 16g NCM523-OH 8g Co(OH) 2
Example 6 24g NCM523-OH 4g Co(OH) 2
Example 7 16g NCM523-OH 4g NCM622-OH
Example 8 16g NCM111-OH 4g NCM622-OH
Example 9 16g NCM523-OH 4g Ni 0.6 Co 0.4 -OH
Example 10 16g NCM523-OH 4g Ni 0.6 Mn 0.4 -OH
Example 11 16g Ni 0.6 Co 0.4 -OH 4g NCM111-OH
Example 12 18g Ni 0.6 Co 0.4 -OH 2g NCM111-OH
Example 13 16g Ni 0.6 Mn 0.4 -OH 4g NCM523-OH
Example 14 18g Ni 0.6 Mn 0.4 -OH 2g NCM523-OH
Comparative example 1
The preparation method of the positive electrode material comprises the following steps:
S1、(Ni 0.5 Co 0.2 Mn 0.3 )(OH) 2 (i.e., NCM 523-OH) precursor preparation: preparing NiSO according to a molar ratio of 5:2:3 4 、CoSO 4 、MnSO 4 Is (Ni) 2+ 、Co 2+ 、Mn 2+ Is 2 mol.L -1 ) 500mL, labeled solution 1; formulation of 4mol L -1 Is marked as solution 2; solution 1 and solution 2 were added to a five-neck flask reactor with 100mL of deionized water at a rate of about 1mL/min by a peristaltic pump and reacted with stirringWhen N is introduced 2 Protecting and keeping the reaction temperature at 30-80 ℃ and stirring at 500rpm/min; simultaneously controlling the pH value of the solution in the reaction process to be 10-13 by dropwise adding ammonia water; continuing stirring for 24 hours after the addition of the solution 1 and the solution 2 is finished so as to age; after the aging is finished, carrying out vacuum suction filtration on the obtained precipitate to obtain a first hydroxide type salt NCM523-OH;
s2, NCM523-OH and Li 2 CO 3 According to a metal/Li molar ratio of 1:1.05, mechanically mixing, loading the obtained mixture into a sagger, putting the sagger into a muffle furnace, heating to 760 ℃ at a speed of 6 ℃/min under the air atmosphere, and preserving heat for 2 hours; heating to 920 ℃ at a speed of 3 ℃/min, and preserving heat for 12 hours; cooling to room temperature along with a furnace after solid-phase sintering, and grinding to obtain a first anode material;
S3、(Ni 1/3 Co 1/3 Mn 1/3 )(OH) 2 (i.e., NCM 111-OH) precursor preparation: preparing NiSO according to a molar ratio of 1:1:1 4 、CoSO 4 、MnSO 4 Is (Ni) 2+ 、Co 2+ 、Mn 2+ Is 2 mol.L -1 ) 500mL, labeled solution 1; formulation of 4mol L -1 Is marked as solution 2; solution 1 and solution 2 were fed into a five-neck flask reactor with 100mL of deionized water at a rate of about 1mL/min by a peristaltic pump and reacted with stirring, and N was introduced during the reaction 2 Protecting and keeping the reaction temperature at 30-80 ℃ and stirring at 500rpm/min; simultaneously controlling the pH value of the solution in the reaction process to be 10-13 by dropwise adding ammonia water; continuing stirring for 24 hours after the addition of the solution 1 and the solution 2 is finished so as to age; after the aging is finished, carrying out vacuum suction filtration on the obtained precipitate to obtain a second hydroxide type salt NCM111-OH;
s4, combining NCM111-OH with Li 2 CO 3 According to a metal/Li molar ratio of 1:1.05, mechanically mixing, loading the obtained mixture into a sagger, putting the sagger into a muffle furnace, heating to 760 ℃ at a speed of 6 ℃/min under the air atmosphere, and preserving heat for 2 hours; heating to 920 ℃ at a speed of 3 ℃/min, and preserving heat for 12 hours; cooling to room temperature along with a furnace after solid-phase sintering, and grinding to obtain a second anode material;
s5, mixing the first positive electrode material and the second positive electrode material according to a mass ratio of 16:4, mechanically mixing uniformly to obtain the composite anode material.
Comparative example 2
The second positive electrode material was prepared differently from comparative example 1,
S3、Co(OH) 2 precursor preparation: preparation of 2mol x L -1 CoSO of (2) 4 500mL of aqueous solution, labeled solution 1; formulation of 4mol L -1 Is marked as solution 2; solution 1 and solution 2 were fed into a five-neck flask reactor with 100mL of deionized water at a rate of about 1mL/min by a peristaltic pump and reacted with stirring, and N was introduced during the reaction 2 Protecting and keeping the reaction temperature at 30-80 ℃ and stirring at 500rpm/min; simultaneously controlling the pH value of the solution in the reaction process to be 10-13 by dropwise adding ammonia water; continuing stirring for 24 hours after the addition of the solution 1 and the solution 2 is finished so as to age; after the aging is completed, the obtained precipitate is filtered in vacuum to obtain a second hydroxide type salt Co (OH) 2
S4, co (OH) 2 With Li 2 CO 3 According to a metal/Li molar ratio of 1:1.05, mechanically mixing, loading the obtained mixture into a sagger, putting the sagger into a muffle furnace, heating to 760 ℃ at a speed of 6 ℃/min under the air atmosphere, and preserving heat for 2 hours; heating to 940 ℃ at a speed of 3 ℃/min, and preserving heat for 12 hours; and cooling to room temperature along with the furnace after solid-phase sintering, and grinding to obtain the second anode material.
The remainder is the same as comparative example 1 and will not be described again here.
The grafted positive electrode material precursors obtained in examples 1 and 4 above were subjected to electron microscopic examination and X-ray diffraction analysis, see SEM and XRD patterns shown in fig. 1 to 2 and 5 to 6. As can be seen from the figure, the grafted positive electrode material precursor provided by the invention successfully completes grafting of two hydroxide salts, and the grafted precursor structure is not destroyed, so that the grafting effect is good.
In addition, electron microscopic examination and X-ray diffraction analysis were also performed on the graft type cathode materials obtained in examples 1 and 4. As can be seen from the SEM and XRD patterns of fig. 3 to 4 and fig. 7 to 8, the grafted cathode material obtained by the present invention is converted into a cathode material by sintering the precursor, and has a layered structure.
The grafted positive electrode materials obtained in examples 1 to 14 and comparative examples 1 to 2 were used in positive electrode sheets, and the preparation method was as follows: and mixing the grafted positive electrode material with super P and PVDF binder according to the mass ratio of 95:2:3 to prepare slurry, so as to obtain the positive electrode plate, wherein the mass of the grafted positive electrode material is 500g, and the specific preparation method can be seen in the preparation of the existing positive electrode plate.
Preparing the obtained positive plate into a full battery, testing the cycle performance, taking natural graphite as a negative electrode material, and taking 1mol/L LiPF as electrolyte 6 EC, DMC, EMC (volume ratio 1:1:1) of (with additives), the separator was a celgard2400 polypropylene film, and a soft-pack full cell (404050) was made. The additives in the electrolyte can be referred to as conventional electrolyte additive settings, and will not be described herein.
Performance test:
1) Capacity exertion test a: (4.2-2.75V, RT, 0.2C/0.2C): charging the formed 0.2C constant current to a cut-off voltage of 4.2V, and stopping constant voltage until the current is less than 0.05C; the 0.2C constant current discharges to a cut-off voltage of 2.75V. And multiplying the constant current discharge time by the discharge current and dividing the discharge current by the mass of the positive electrode material to obtain the capacity exertion.
Capacity exertion test B: (4.35-2.75V, RT, 0.2C/0.2C): charging the formed 0.2C constant current to a cut-off voltage of 4.35V, and stopping constant voltage until the current is less than 0.05C; the 0.2C constant current discharges to a cut-off voltage of 2.75V. And multiplying the constant current discharge time by the discharge current and dividing the discharge current by the mass of the positive electrode material to obtain the capacity exertion.
2) Cycle performance test a: at 25+ -2deg.C, the lithium ion secondary battery is charged to 4.2V at a constant current of 1C, then charged to 0.05C at a constant voltage of 4.2V, left for 5min, and then discharged to 2.75V at a constant current of 1C, which is a charge-discharge cycle process, and the discharge capacity at this time is the discharge capacity of the first cycle. The battery was subjected to a cyclic charge-discharge test according to the above method, and the discharge capacity per cycle was recorded.
Cycle performance test B: at 55+ -2deg.C, the lithium ion secondary battery is charged to 4.35V at a constant current of 1C, then charged to 0.05C at a constant voltage of 4.35V, left for 5min, and then discharged to 2.75V at a constant current of 1C, which is a charge-discharge cycle process, and the discharge capacity at this time is the discharge capacity of the first cycle. The battery was subjected to a cyclic charge-discharge test according to the above method, and the discharge capacity per cycle was recorded.
3) Overcharge resistance test: at room temperature, each group of 10 cells was discharged to 3.0V at 0.5C, and then subjected to a 1C/10V overcharge test. A thermocouple and a temperature acquisition instrument (HIOKI, LR 8501) are added on the battery core, the positive electrode and the negative electrode of the battery core are connected with a constant current and constant voltage source (Agilent, 34410A), the current is regulated to 1C, the voltage is 10V until the current is reduced to 0A, and the temperature change and the swelling condition of the battery core are monitored in the overcharging process.
The test results are shown in Table 2 below.
TABLE 2
From the test results, the positive electrode material of the hydroxide type salt grafted hydroxide type salt provided by the invention is applied to a battery, and the capacity exertion, the cycle performance and the overcharge resistance of the battery are effectively improved. The method is mainly characterized in that two hydroxide type salts are coupled together by a chemical grafting method through a precursor end grafting mode, so that the aim of uniformly mixing different types of materials is fulfilled, the problems of uneven slurry dispersion and poor pole piece uniformity in the application process of the conventional direct-mixed positive electrode material in a lithium ion battery are effectively solved, more importantly, the problem of unbalanced local potential of different types of materials in the charging and discharging processes is solved, the electrochemical performance of the positive electrode material in the battery is improved, and the final grafted positive electrode material realizes larger overall performance improvement.
It can be further seen from the comparison of examples 1 to 14 that the use of different hydroxide species and different contents also has different effects on the capacity exertion, cycle performance and overcharge resistance of the lithium ion battery, for example, when the mass ratio of the two hydroxides is 4: the precursor is prepared in the step 1, so that the excellent battery cycle performance can be obtained, and the capacity retention rate of 80% can be maintained after the battery is cycled for 750 circles at the high temperature of 4.35V.
In summary, the positive electrode material precursor of hydroxide type salt grafted hydroxide type salt solves the problems of uneven slurry dispersion, poor pole piece uniformity and inconsistent electrochemical performance of the material in the application process of the lithium ion battery of the current mixed positive electrode material, and effectively improves the cycle performance of the battery.
Variations and modifications of the above embodiments will occur to those skilled in the art to which the invention pertains from the foregoing disclosure and teachings. Therefore, the present invention is not limited to the above-described embodiments, but is intended to be capable of modification, substitution or variation in light thereof, which will be apparent to those skilled in the art in light of the present teachings. In addition, although specific terms are used in the present specification, these terms are for convenience of description only and do not limit the present invention in any way.

Claims (10)

1. A grafted positive electrode material precursor is characterized in that the structural formula is A (OH) 2 -R-B(OH) 2 A and B are Ni 1-a-b Co a Mn b Z c Wherein a is more than or equal to 0 and less than or equal to 1; b is more than or equal to 0 and less than or equal to 1; a+b is more than 0 and less than or equal to 1; c is more than or equal to 0 and less than or equal to 1, the molar ratio of nickel, cobalt and manganese in A is different from the molar ratio of nickel, cobalt and manganese in B, and Z is at least one of Al, mg, ti, B, zr, bi, mo, P, F and rare earth elements; r is a grafting agent comprising Ni, co, mn, al, mg, si, ti, B, zr, bi, mo, P and at least one element of rare earth elements;
Wherein R is (M) x N y )CO 3 Or (M) x N y )(OH) 2 X is more than 0 and less than 1; y is more than 0 and less than 1; x+y is more than 0 and less than or equal to 1; m and N are selected from different elements, and are at least one element of Ni, co, mn, al, mg, si, ti, B, zr, bi, mo, P and rare earth elements;
wherein the mass of R is 1-10% of the sum of the mass of A (OH) 2 and the mass of B (OH) 2.
2. According to claimThe grafted positive electrode material precursor according to claim 1, wherein A (OH) 2 And B (OH) 2 The mass ratio of (2) is 1:99-99:1.
3. A method for preparing the grafted positive electrode material precursor according to any of claims 1 to 2, comprising the steps of:
s1, mixing an aqueous solution containing nickel salt, cobalt salt, manganese salt and Z salt with an aqueous solution of hydroxide for reaction, controlling the pH of the solution in the reaction process to be 10-13, aging, and suction-filtering to obtain a first hydroxide type salt A (OH) 2
S2, mixing an aqueous solution containing nickel salt, cobalt salt, manganese salt and Z salt with an aqueous solution of hydroxide for reaction, controlling the pH of the solution in the reaction process to be 10-13, aging, and suction-filtering to obtain a second hydroxide type salt B (OH) 2
S3, subjecting the first hydroxide form salt A (OH) 2 And a salt of the second hydroxide form B (OH) 2 Mixing at 25-70 deg.c to prepare slurry; adding a solution for liquid phase reaction to form a grafting agent R into the slurry, stirring and reacting for 30-90 min, washing and drying to obtain a grafted positive electrode material precursor A (OH) 2 -R-B(OH) 2
4. The method of preparing a grafted positive electrode material precursor according to claim 3, wherein in step S1, the first hydroxide salt a (OH) 2 The preparation method of (2) comprises the following steps: adding aqueous solution containing nickel salt, cobalt salt, manganese salt and Z salt and hydroxide aqueous solution into a reactor containing water at a speed of 1-2 mL/min respectively, continuously stirring and reacting at 30-80 ℃ in an inert atmosphere, controlling the pH of the solution in the reaction process to be 10-13, continuously stirring and aging for 10-36 h after the addition, and vacuum-filtering to obtain first hydroxide salt A (OH) 2
5. The method for preparing a grafted positive electrode material precursor according to claim 3, wherein in step S2, the second hydroxide salt B (OH) 2 The preparation method of (2) comprises the following steps: a nickel salt is added,Adding aqueous solutions of cobalt salt, manganese salt and Z salt and aqueous solution of hydroxide into a reactor containing water at a speed of 1-2 mL/min respectively, continuously stirring and reacting at 30-80 ℃ in an inert atmosphere, controlling the pH of the solution in the reaction process to be 10-13, continuously stirring and aging for 10-36 h after the addition is finished, and vacuum filtering to obtain a second hydroxide salt B (OH) 2
6. The method of preparing a grafted positive electrode material precursor according to claim 3, wherein in step S3, the solution for forming the grafting agent R by liquid phase reaction comprises a first solution and a second solution, the first solution is a mixed solution of cobalt salt and manganese salt, the second solution is sodium bicarbonate solution or sodium hydroxide solution, and the first solution and the second solution form the grafting agent R by liquid phase reaction to form the first hydroxide salt a (OH) 2 And a salt of the second hydroxide form B (OH) 2 Grafting is performed.
7. A preparation method of a grafted positive electrode material, which is characterized in that the grafted positive electrode material precursor according to any one of claims 1-2 is mixed with lithium salt, sintered for 6-24 hours at 750-950 ℃, cooled and ground to obtain the grafted positive electrode material.
8. A grafted positive electrode material prepared by the method for preparing a grafted positive electrode material according to claim 7.
9. A positive electrode sheet comprising the grafted positive electrode material of claim 8.
10. A lithium ion battery comprising a positive plate, a negative plate and a diaphragm spaced between the positive plate and the negative plate, wherein the positive plate is the positive plate of claim 9.
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