CN117534130A - Porous gridding precursor, preparation method thereof and positive electrode material - Google Patents

Porous gridding precursor, preparation method thereof and positive electrode material Download PDF

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CN117534130A
CN117534130A CN202311470554.3A CN202311470554A CN117534130A CN 117534130 A CN117534130 A CN 117534130A CN 202311470554 A CN202311470554 A CN 202311470554A CN 117534130 A CN117534130 A CN 117534130A
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precursor
porous
gridding
polyhydroxy
carbon material
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王城隆
徐健
方刚
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Gaodian Shenzhen Technology Co ltd
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Gaodian Shenzhen Technology Co ltd
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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B25/00—Phosphorus; Compounds thereof
    • C01B25/16—Oxyacids of phosphorus; Salts thereof
    • C01B25/26—Phosphates
    • C01B25/37—Phosphates of heavy metals
    • C01B25/375—Phosphates of heavy metals of iron
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B25/00—Phosphorus; Compounds thereof
    • C01B25/16—Oxyacids of phosphorus; Salts thereof
    • C01B25/26—Phosphates
    • C01B25/45—Phosphates containing plural metal, or metal and ammonium
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G53/00—Compounds of nickel
    • C01G53/006—Compounds containing, besides nickel, two or more other elements, with the exception of oxygen or hydrogen
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G53/00—Compounds of nickel
    • C01G53/40—Nickelates
    • C01G53/42—Nickelates containing alkali metals, e.g. LiNiO2
    • C01G53/44—Nickelates containing alkali metals, e.g. LiNiO2 containing manganese
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/5825—Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/01—Particle morphology depicted by an image
    • C01P2004/03—Particle morphology depicted by an image obtained by SEM
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/40—Electric properties

Abstract

The invention belongs to the technical field of secondary batteries, and particularly relates to a porous gridding precursor, a preparation method thereof and a positive electrode material, wherein the preparation method of the porous gridding precursor comprises the following steps: s1, dispersing a polyhydroxy carbon material in a solution to obtain a dispersion liquid; s2, adding transition metal into the dispersion liquid, and stirring to obtain a mixed liquid; s3, preparing an anionic group solution; s4, adding a solvent, a complexing agent, a surfactant, a mixed solution and an anionic group solution into a reactor, regulating pH value for reaction, aging, centrifuging, washing and filtering to obtain a precursor; and S5, sintering the precursor to form the porous gridding precursor. According to the preparation method of the porous gridding precursor, the insoluble polyhydroxy carbon material is used as a template, oxide, hydroxide, carbonic acid system and phosphoric acid system precursors are deposited on the template in situ, and the precursor is prepared through liquid, so that the elements are more uniformly mixed, and the mass transfer efficiency in the later stage is improved.

Description

Porous gridding precursor, preparation method thereof and positive electrode material
Technical Field
The invention belongs to the technical field of secondary batteries, and particularly relates to a porous gridding precursor, a preparation method thereof and a positive electrode material.
Background
In recent years, with the development of the battery industry, there is an increasing demand for the preparation and quality uniformity of the cathode material, and particularly, the development of the sintering process to the present stage has become difficult as an advantageous means for improving the key performance of the material. Further optimization of the precursor is further related to the performance of the positive electrode material.
Chinese patent CN 107359318A discloses a method for synthesizing a spherical porous structure ferric phosphate precursor and a lithium iron phosphate positive electrode material, which mainly comprises continuously growing a mixture of ferric phosphate and ferric hydroxide on original micron-sized ferric phosphate precursor particles, and then dissolving ferric hydroxide by reducing pH to form a spherical porous structure ferric phosphate precursor, wherein the precursor is subjected to carbon-coated lithium mixing calcination to obtain the lithium iron phosphate positive electrode material. The material has the characteristics of multiple pores, improves the specific surface area and increases the contact area between the electrolyte and the positive electrode material. However, the material has a micron-sized inner core, the problems of poor conductivity and poor power in the material can not be solved, the preparation process is complex, and the consistency of the morphology of the precursor can not be maintained by adjusting the pH value to dissolve ferric hydroxide.
Chinese patent CN 116199274A discloses a porous hollow ternary precursor and a preparation method thereof, wherein a nickel-cobalt-manganese ternary mixed solution, an inorganic aluminum alkali solution, a complexing agent and a precipitator are subjected to coprecipitation through a reaction kettle to prepare a nickel-cobalt-manganese-aluminum quaternary core structure, when the core reaches a target particle size, the inorganic aluminum alkali solution is stopped being fed, the coprecipitation is continued to prepare a nickel-cobalt-manganese ternary shell structure, after the whole particle size reaches the target particle size, the reacted material is placed in a strong alkali solution to be stirred, so that aluminum hydroxide in the core is dissolved out to form a porous hollow structure, and the porous hollow ternary precursor is obtained after washing, separation and drying. The porous precursor prepared by the method has complex process and more required control variables, is only suitable for hydroxide precursor materials, and has certain limitation.
In view of the above-mentioned drawbacks of the current porous precursor material preparation, it is necessary to provide a solution to the above-mentioned problems.
Disclosure of Invention
One of the objects of the present invention is: aiming at the defects of the prior art, a preparation method of a porous gridding precursor is provided.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
a method of preparing a porous gridded precursor comprising the steps of:
s1, dispersing a polyhydroxy carbon material in a solution to obtain a dispersion liquid;
s2, adding transition metal into the dispersion liquid, and stirring to obtain a mixed liquid;
s3, preparing carbonate, hydroxide or phosphate into an anionic group solution;
s4, adding a solvent, a complexing agent and a surfactant into a reactor, stirring, adding a mixed solution and an anionic group solution, regulating pH value for reaction, aging, centrifuging, washing and filtering to obtain a precursor taking a polyhydroxy carbon material as a carrier;
and S5, sintering the precursor taking the polyhydroxy carbon material as a carrier to remove the polyhydroxy carbon material to form a porous gridding precursor.
The preparation method of the porous gridding precursor uses an insoluble polyhydroxy carbon material as a template, transition metal materials are uniformly deposited on the surface of the polyhydroxy carbon material in situ to form a mother nucleus due to the action of hydrogen bonds, then anionic group solution, complexing agent and surfactant are added for reaction, in situ deposition is carried out by once regulating the pH value, the precursor material with the specified particle size is formed for the mother nucleus, and after washing, separation and drying, the insoluble polyhydroxy carbon material is oxidized and decomposed into carbon dioxide and water through high-temperature calcination in an air atmosphere, so that the porous gridding precursor is formed. The hydroxyl groups in the polyhydroxy material can be chelated with metal ions, and anions, precipitants and the like can be added to form precipitates to be attached to the polyhydroxy material under the action of the charges of the metal ions again. The polyhydroxy groups are ionically bound to metal ions.
The preparation method provided by the invention can obtain the precursor material with uniform internal and external porosity only by one-time pH value adjustment, and improves the stability of the material. The surface and the inside of the positive electrode material prepared by the precursor are provided with porous structures, and the porous structures greatly improve the specific surface area of the material, so that the contact area between the positive electrode material and electrolyte is increased, and the electrochemical performance of the material is improved. Wherein the transition metal is a soluble transition metal. The surfactant can regulate the particle size to form spherical or spheroidal particles. Preferably, the size of the core is 1 to 20 microns. The solution in step S1 is water. In step S4, the solvent is water. In the step S4, the pH value is regulated to enable the precursor to be settled within a certain pH range, the phosphoric acid precursor is settled under an acidic condition, the pH value is 1.0-3.0, the hydroxyl and carbonate precursor is settled under an alkaline condition, the pH value is 8.0-12.0, and the reaction time is 3-5 hours. The reactor in step S4 may be a reaction vessel.
Wherein the complexing agent comprises one or more of oxalic acid, citric acid, tartaric acid, gluconic acid or diethanolamine; the surfactant is one or more of fatty acid polyoxyethylene ester, alkylphenol polyoxyethylene, alkyl alcohol amide and sucrose fatty acid ester. Different carbonate, hydroxide or phosphate are used for preparing anionic group solutions, so that different precursors can be obtained, and when the carbonate solution is added, the carbonate precursor can be prepared; when hydroxide is added, a hydroxide precursor can be prepared; when phosphate solution is added, a phosphate precursor can be prepared.
Through intermolecular hydrogen bonding, an anionic group solution such as oxide or hydroxide, phosphoric acid and the like is combined with transition metal deposited on the polyhydroxy carbon material to form a precursor taking the polyhydroxy carbon material as a carrier, and the polyhydroxy carbon material is oxidized into carbon dioxide and water through sintering under an air atmosphere to form a porous gridding precursor.
Wherein the feeding speed of the mixed solution in the step S4 is 1-5 mL/min, and the feeding speed of the anionic group solution is 0.5-2 mL/min. The feed rate of the mixed solution is 1mL/min, 1.2mL/min, 1.5mL/min, 1.8mL/min, 2mL/min, 2.5mL/min, 3mL/min, 3.5mL/min, 4mL/min, 4.5mL/min, 5mL/min, and the feed rate of the anionic group solution is 0.5mL/min, 0.8mL/min, 1mL/min, 1.3mL/min, 1.5mL/min, 1.8mL/min, 2mL/min. And a certain feeding speed is controlled, so that the reaction is more complete, and the generated precursor material has a uniform and stable porous network structure, so that the performance of the positive electrode material is better.
Wherein the sintering temperature in the step S5 is 400-800 ℃, and the sintering time is 2-4 h. The sintering temperature is 400 ℃, 450 ℃, 500 ℃, 550 ℃, 600 ℃, 650 ℃, 700 ℃, 750 ℃, 800 ℃ and the sintering time is 2 hours, 2.5 hours, 3 hours, 3.5 hours and 4 hours. The porous cavity structure is firmer by controlling certain sintering temperature and sintering time, the precursor material with good dispersibility and uniformity is formed, and the performance of the anode material is better.
Wherein, the value of the polymerization degree N of the polyhydroxy carbon material is as follows: 100000 ～ 10000000 the carbon content of the polyhydroxy carbon material is 30% -80% and the hydroxyl content is 30% -50%. The carbon content of the polyhydroxy carbon material was 30%, 40%, 50%, 60%, 70%, 80%. The hydroxyl content is 30%, 35%, 40%, 45%, 50%. Wherein, the value of the polymerization degree N of the polyhydroxy carbon material is as follows: 100000 ～ 10000000. The polymerization degree N of the polyhydroxy carbon material was 100000, 500000, 800000, 1000000, 5000000, 8000000, 10000000. The polyhydroxy carbon material is in a solid state when the polymerization degree is in the range, has a certain supporting effect, and can meet the required quantity of hydroxyl and carboxyl.
Wherein the polyhydroxy carbon material comprises one or more of polyhydroxy polyethylene resin, polyhydroxy epoxy resin, polyhydroxy polypropylene base resin, polyhydroxy phenolic resin, polyvinyl alcohol acrylonitrile copolymer, glycerol alkyd resin, polyvinyl alcohol and polyvinyl alcohol pyrrolidone copolymer. Precursors for the polyhydroxy carbon materials include, but are not limited to, cobalt-based precursors, phosphoric acid-based precursors, binary-based precursors, ternary-based precursors, and quaternary-based precursors. The cobalt-based precursor comprises cobalt carbonate, cobalt hydroxide, cobalt oxide and the like, the phosphoric acid-based precursor comprises ferric phosphate, ferromanganese phosphate and the like, the binary-based precursor comprises nickel-manganese hydroxide or oxide, nickel-cobalt hydroxide or oxide, nickel-iron hydroxide or oxide, manganese-cobalt hydroxide or oxide and the like, the ternary-based precursor comprises nickel-cobalt-manganese hydroxide, nickel-iron-manganese hydroxide and the like, and the quaternary-based precursor comprises nickel-cobalt-iron-manganese hydroxide or oxide and the like.
Wherein the diameter of the polyhydroxy carbon material is 0.1-5 micrometers, and the length is 2-50 micrometers. The diameter of the polyhydroxy carbon material was 0.1 micron, 0.3 micron, 0.5 micron, 0.7 micron, 0.9 micron, 1 micron, 1.5 micron, 2 micron, 2.5 micron, 3 micron, 3.5 micron, 4 micron, 4.5 micron, 5 micron. The polyhydroxy carbon material is provided with a certain diameter and length so as to be used as a precursor for crystal nucleus deposition, and holes can be formed after sintering to obtain a porous structure.
Wherein, the carbon content of the polyhydroxy carbon material is 30% -80%, and the hydroxyl content is 30% -50%. Specifically, the carbon content of the polyhydroxy carbon material was 30%, 40%, 50%, 60%, 70%, 80%, and the hydroxyl content was 30%, 40%, 50%, respectively (which can be measured according to the chinese standard SN/T2823-2011). Meanwhile, the carboxyl content is 10% -20%. The carboxyl content is set in a certain range, so that the material can be characterized.
Wherein the polyhydroxy carbon material accounts for 0.1% -5% of the precursor by mass. The polyhydroxy carbon material accounts for 0.1%, 0.5%, 0.8%, 1%, 1.5%, 2%, 3%, 4% and 5% of the precursor by mass. The polyhydroxy carbon material cannot be used too much or too little, and the polyhydroxy carbon material is used too much to increase the carbon content in the later-stage material, so that the material performance is affected.
Wherein the complexing agent in the step S4 is one or more of oxalic acid, citric acid, tartaric acid, gluconic acid or diethanolamine.
The surfactant in the step S4 is one or more of fatty acid polyoxyethylene ester, alkylphenol polyoxyethylene, alkyl alcohol amide and sucrose fatty acid ester. The particle size can be regulated and controlled by adding the surfactant into the reaction liquid, so that spherical or spheroidic particles are formed.
Wherein the reaction temperature in the step S4 is 60-90 ℃, the pH in the step S3 is 1.0-3.0 or 8.0-12.0, and the reaction time is 3-5 hours. The reaction temperature in step S3 was 60 ℃, 70 ℃, 80 ℃, 90 ℃, and the pH in step S3 was 1.0, 2.0, 3.0 or 8.0, 9.0, 10.0, 11.0, 12.0. The reaction time was 3 hours, 4 hours, 5 hours. The pH is adjusted to enable the precursor to be settled within a certain range, the phosphoric acid precursor is settled under an acidic condition, and the hydroxyl and carbonate precursors are settled under an alkaline condition.
The second object of the present invention is: aiming at the defects of the prior art, the porous gridding precursor has uniformity and porosity, has good consistency and can improve the mass transfer efficiency of materials.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
a porous gridding precursor is prepared by the preparation method of the porous gridding precursor.
The porous gridding precursor prepared by the preparation method disclosed by the invention is calcined to obtain the positive electrode material with a three-dimensional network-shaped cavity structure, so that the positive electrode material has stronger liquid retention property, the multiplying power performance is improved to a certain extent, the inside of the porous structure is supported to a certain extent, and the morphology is not easy to damage in the compaction process. Adding a proper amount of lithium source or sodium source into the precursor, and performing high-temperature sintering under certain conditions to obtain the positive electrode material with the three-dimensional network-shaped cavities. For calcination in the precursor, since the insoluble polyhydroxycarbon source is decomposed at high temperature to produce water and carbon dioxide, the produced gas and the consumed carbon source can give the precursor having a porous gridding structure.
The third object of the present invention is to: aiming at the defects of the prior art, the anode material is provided with a three-dimensional network-shaped cavity structure, has better liquid retention and rate capability, has a certain support in the porous interior, and is not easy to damage in the compaction process.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
the positive electrode material is prepared by adding a lithium source or a sodium source into the porous gridding precursor, heating and sintering.
Adding a proper amount of lithium source or sodium source into the precursor, and performing high-temperature sintering under certain conditions to obtain the positive electrode material with the three-dimensional network-shaped cavities; the lithium iron phosphate positive electrode material with the three-dimensional network-shaped cavity structure, which is obtained by the preparation method, has larger surface area, larger contact area with electrolyte, stronger liquid retention and better rate capability, and the porous interior has a certain support, so that the morphology is not easy to be damaged in the compaction process.
Compared with the prior art, the invention has the beneficial effects that:
1. the preparation method of the porous gridding precursor uses an insoluble polyhydroxy carbon material as a template, transition metal materials are uniformly deposited on the surface of the polyhydroxy carbon material in situ to form a mother nucleus due to the action of hydrogen bonds, then anionic group solution, complexing agent and surfactant are added for reaction, in situ deposition is carried out by once regulating the pH value, the precursor material with the specified particle size is formed for the mother nucleus, and after washing, separation and drying, the insoluble polyhydroxy carbon material is oxidized and decomposed into carbon dioxide and water through high-temperature calcination in an air atmosphere, so that the porous gridding precursor is formed. The preparation method provided by the invention can obtain the precursor material with uniform internal and external porosity only by one-time pH value adjustment, and improves the stability of the material.
2. When the lithium source or the sodium source is added into the precursor for calcination, the anode material with a porous structure can be obtained, and the porous structure greatly improves the specific surface area of the material, so that the contact area between the anode material and electrolyte is increased, and the electrochemical performance of the material is improved.
Drawings
Fig. 1 is an SEM image of the precursor material prepared in comparative example 1.
Fig. 2 is an SEM image of the precursor material prepared in comparative example 1 after slicing.
Fig. 3 is an SEM image of the precursor material prepared in example 1.
Fig. 4 is an SEM image of the precursor material prepared in example 1 after slicing.
Detailed Description
The invention will be described in further detail with reference to the following detailed description and the accompanying drawings, but the embodiments of the invention are not limited thereto.
Example 1
Preparation of iron phosphate precursor:
s1, target synthesis of a polyhydroxy carbon material-containing ferric phosphate precursor, namely weighing 1g of glycerol alkyd resin with the weight ratio of 1% as a polyhydroxy carbon material, and uniformly dispersing the glycerol alkyd resin into 100g of water through the action of strong shearing to form a dispersion liquid; wherein the polyhydroxy carbon material had a diameter of 3 microns and a length of 35 microns.
S2, weighing 169.7g of ferric sulfate to prepare 1L of aqueous solution serving as a transition metal solution, wherein the concentration of metal ions is 0.63mol/L, adding the transition metal solution into the dispersion liquid, and stirring to obtain a mixed liquid;
step S3, weighing monoammonium phosphate (NH) 4 H 2 PO 4 ) 73.6g, prepared into 0.5L monoammonium phosphate aqueous solution as anionic group solution, with concentration of 1.27mol/L;
s4, adding 10mL of complexing agent and 2g of surfactant of fatty acid polyoxyethylene ester into a reactor, stirring at 500rpm, and adding the mixed solution and the anionic group solution, wherein the feeding speed of the mixed solution is 2mL/min, and the feeding speed of monoammonium phosphate aqueous solution is 1.5mL/min; adjusting pH to 4.2, aging for 4 hours, transferring the slurry to a centrifuge for washing and filtering, placing the washed slurry in a baking oven for baking at 80 ℃ for 5 hours to obtain a ferric phosphate precursor with a polyhydroxy carbon material as a carrier; wherein, the preparation of the pH value regulating reagent uses an ammonia water solution, and the ammonia water solution is 700g of 25% ammonia water solutionConstant volume to 2L; complexing agent preparation, namely preparing 5L of 10M oxalic acid solution, namely weighing 1260.7g of H 2 C 2 O 4 ·2H 2 O, after being dissolved by 4000g of deionized water at about 50 ℃, the volume is fixed to 5L;
and S5, calcining the precursor for 3 hours at 500 ℃, removing the polyhydroxy carbon material and the crystallization water to obtain a porous gridding precursor A2, wherein a scanning electron microscope is shown in fig. 3 and 4, and a porous gridding structure is formed.
Example 2
A method of preparing a porous gridded precursor comprising the steps of:
step S1, weighing 20g of glycerol alkyd resin with the weight ratio of 1%, adding the glycerol alkyd resin and 3L of deionized water into a reaction kettle, uniformly dispersing the glycerol alkyd resin under the action of strong shearing, and stirring the glycerol alkyd resin at the stirring speed of 800rpm for 40min; obtaining a dispersion liquid;
step S2, preparing 5M Nickel sulfate (NiSO 4 ) 2M cobalt sulfate (CoSO) 4 ) 3M manganese sulfate (MnSO 4 ) Mixing the aqueous solution 5L, weighing 1320.1g NiSO 4 ·6H 2 O, 566.1g CoSO 4 ·7H 2 O and 508.7g of MnSO 4 ·H 2 O, after being dissolved by 3000g of deionized water at about 50 ℃, the volume is fixed to 5L; as a transition metal solution, adding the transition metal solution into the dispersion liquid, and stirring to obtain a mixed liquid;
step S3, 138.206g of carbonate solvent is dissolved in 1L of water to obtain 1mol/L carbonate solution which is used as an anionic group solution;
s4, adding 10ml of complexing agent and 2g of polyethylene glycol surfactant into a reactor, stirring, adding the mixed solution and the anionic group solution, regulating pH value for reaction, aging, press-filtering the slurry by using a centrifuge (model is YLT-1200) to obtain a filter cake, placing the filter cake into an electrothermal blowing dryer (model is 101-0 ABS), drying at the constant temperature of 80 ℃ for 3 hours, and taking out to obtain the Ni with a single crystal phase structure 0.5 Co 0.2 Mn 0.3 C 2 O 4 A precursor; wherein, the preparation of the pH value regulating reagent uses 10M and 2L ammonia water solution, the ammonia water solution is 700g of 25% ammonia water solution, and the volume is fixed to 2L; complexing agentIs prepared by preparing 5L of 10M oxalic acid solution, namely weighing 1260.7g of H 2 C 2 O 4 ·2H 2 O, after being dissolved by 4000g of deionized water at about 50 ℃, the volume is fixed to 5L;
and S5, sintering the precursor taking the polyhydroxy carbon material as a carrier at 500 ℃ for 3 hours to remove the polyhydroxy carbon material and form the porous gridding precursor.
Example 3
The difference from example 1 is that: the feeding speed of the mixed solution in the step S4 is 3mL/min, and the feeding speed of the anionic group solution is 0.5mL/min.
The remainder is the same as in example 1 and will not be described again here.
Example 4
The difference from example 1 is that: the feeding speed of the mixed solution in the step S4 is 4mL/min, and the feeding speed of the anionic group solution is 1.5mL/min.
The remainder is the same as in example 1 and will not be described again here.
Example 5
The difference from example 1 is that: the feeding speed of the mixed solution in the step S4 is 5mL/min, and the feeding speed of the anionic group solution is 2mL/min.
The remainder is the same as in example 1 and will not be described again here.
Example 6
The difference from example 1 is that: the sintering temperature in the step S5 is 400 ℃, and the sintering time is 4 hours.
The remainder is the same as in example 1 and will not be described again here.
Example 7
The difference from example 1 is that: the sintering temperature in the step S5 is 500 ℃, and the sintering time is 4 hours.
The remainder is the same as in example 1 and will not be described again here.
Example 8
The difference from example 1 is that: the sintering temperature in the step S5 is 800 ℃, and the sintering time is 2 hours.
The remainder is the same as in example 1 and will not be described again here.
Example 9
The difference from example 1 is that: the polyhydroxy carbon material in step S1 had a diameter of 0.8 microns and a length of 30 microns.
The remainder is the same as in example 1 and will not be described again here.
Example 10
The difference from example 1 is that: the polyhydroxy carbon material in step S1 had a diameter of 2 micrometers and a length of 40 micrometers.
The remainder is the same as in example 1 and will not be described again here.
Example 11
The difference from example 1 is that: the polyhydroxy carbon material in step S1 has a diameter of 5 micrometers and a length of 50 micrometers.
The remainder is the same as in example 1 and will not be described again here.
Comparative example 1
Step S1: 169.7g of ferric sulfate is weighed to prepare 1L of aqueous solution as transition metal, wherein the concentration of metal ions is 0.63mol/L;
step S2: weighing monoammonium phosphate (NH) 4 H 2 PO 4 ) 73.6g, prepared into 0.5L monoammonium phosphate aqueous solution with the concentration of 1.27mol/L;
step S3: adding 0.1L of deionized water, tartaric acid complexing agent and fatty acid polyoxyethylene ester surfactant into a reaction kettle, wherein the stirring speed is 500rpm, and simultaneously pumping the transition metal in S1 and the monoammonium phosphate aqueous solution in S2 by using a metering pump, wherein the feeding speed of the transition metal in S1 is 3mL/min, and the feeding speed of the monoammonium phosphate aqueous solution is 1.5mL/min;
step S4: after the feeding is finished, adjusting the pH=4.2, aging for 4 hours, and transferring the slurry to a centrifugal machine for washing and filtering;
step S5: and (3) placing the washed slurry in an oven for drying, wherein the drying temperature is 80 ℃, and drying is carried out for 5 hours to obtain the polyhydroxy carbon material-containing ferric phosphate precursor.
And S6, calcining the precursor at 500 ℃ for 3 hours, removing the polyhydroxy carbon material and the crystallization water to obtain the precursor, wherein a scanning electron microscope is shown in fig. 1 and 2, and a porous structure does not appear.
The porous gridding precursors prepared in examples 1 to 11 and comparative example 1 were applied to a positive electrode material, a positive electrode sheet and a secondary battery, and cycle performance test was performed, and test results were recorded in table 1.
And (3) testing the cycle performance: at 25 ℃, the lithium ion secondary battery is charged to 4.25V at a constant current of 1C, then is charged to 0.05C at a constant voltage of 4.25V, is kept stand for 5min, and is discharged to 2.8V at a constant current of 1C, wherein the discharge capacity is the discharge capacity of the first cycle in a charge-discharge cycle process. The lithium ion secondary battery was subjected to 1000-cycle charge-discharge test according to the above method, and the discharge capacity per cycle was recorded. Cycle capacity retention (%) =discharge capacity of 1000 th cycle/discharge capacity of first cycle×100%.
TABLE 1
Project Capacity retention (%) Project Capacity retention (%)
Example 1 89 Example 2 86
Example 3 86 Example 4 85
Example 5 87 Example 6 85
Example 7 86 Example 8 86
Example 9 86 Example 10 87
Example 11 86 Comparative example 1 72
According to the table 1, it can be obtained that the porous gridding precursor prepared by the method has better electrochemical performance when being applied to the secondary battery, and the capacity retention rate is still maintained above 85% after 1000 charge and discharge cycles. Whereas comparative example 1 had a capacity retention of only 72% and was inferior in performance.
According to comparison of examples 1 and 3-5, when the feeding speed of the mixed solution in the step S4 is set to be 2mL/min and the feeding speed of the anionic group solution is set to be 1.5mL/min, the prepared porous gridding precursor has a better pore gridding structure, so that the prepared positive electrode material has stronger liquid retention on electrolyte, and further has better multiplying power performance and cyclic charge-discharge performance.
According to comparison of examples 1 and 6-8, when the sintering temperature in the step S5 is 500 ℃ and the sintering time is 3 hours, the prepared porous gridding precursor has a firmer porous gridding structure, the inside of the porous has a certain supporting effect, and the morphology is not easy to damage in the compacting process.
As shown by comparison of examples 1 and 9-11, when the polyhydroxy carbon material is 3 microns in diameter and 35 microns in length, the prepared precursor and the cathode material have better porous cavity structures, and the structure is firm and not easy to break.
As shown in fig. 1, the surface of the precursor material prepared in comparative example 1 is relatively flat and smooth, and no holes are formed, and a screenshot obtained by slicing the precursor material is shown in fig. 2, wherein the solid mass of the precursor material in comparative example 1 is sliced into flat and no-hole solid mass. The surface of the precursor material prepared by the method is shown in fig. 3, the surface is uneven, the cross section obtained by slicing the precursor material is shown in fig. 4, the inside of the precursor is provided with a plurality of irregular holes, the whole body of the precursor is in a porous structure, and the surface area of the precursor is larger.
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 method for preparing a porous gridded precursor, comprising the steps of:
s1, dispersing a polyhydroxy carbon material in a solution to obtain a dispersion liquid;
s2, adding transition metal into the dispersion liquid, and stirring to obtain a mixed liquid;
s3, preparing carbonate, hydroxide or phosphate into an anionic group solution;
s4, adding a solvent, a complexing agent and a surfactant into a reactor, stirring, adding a mixed solution and an anionic group solution, regulating pH value for reaction, aging, centrifuging, washing and drying to obtain a precursor taking a polyhydroxy carbon material as a carrier;
and S5, sintering the precursor taking the polyhydroxy carbon material as a carrier to remove the polyhydroxy carbon material to form a porous gridding precursor.
2. The method for preparing a porous gridding precursor according to claim 1, wherein the feeding speed of the mixed solution in the step S4 is 1-5 mL/min, and the feeding speed of the anionic group solution is 0.5-2 mL/min.
3. The method for preparing a porous gridding precursor according to claim 1, wherein the sintering temperature in the step S5 is 400-800 ℃ and the sintering time is 2-4 hours.
4. The method for preparing a porous gridding precursor according to claim 1, wherein the polyhydroxy carbon material has a polymerization degree N of: 100000 ～ 10000000 the carbon content of the polyhydroxy carbon material is 30% -80% and the hydroxyl content is 30% -50%.
5. The method of preparing a porous gridded precursor according to claim 1, wherein the polyhydroxy carbon material comprises one or more of polyhydroxy polyvinyl resins, polyhydroxy epoxy resins, polyhydroxy polypropylene based resins, polyhydroxy phenolic resins, polyvinyl alcohol acrylonitrile copolymers, glycerol alkyd resins, polyvinyl alcohol vinyl pyrrolidone copolymers.
6. The method of preparing a porous gridded precursor according to claim 1, wherein the polyhydroxylated carbon material has a diameter of 0.1 to 5 microns and a length of 2 to 50 microns.
7. The method for preparing a porous gridding precursor according to claim 1, wherein the polyhydroxycarbon material accounts for 0.1% -5% of the mass of the precursor material.
8. The method for preparing a porous gridding precursor according to claim 1, wherein the reaction temperature in the step S3 is 60 to 90 ℃, the pH in the step S3 is 1.0 to 3.0 or 8.0 to 12.0, and the reaction time is 3 to 5 hours.
9. A porous gridding precursor obtained by the method of preparing a porous gridding precursor according to any one of claims 1 to 8.
10. A positive electrode material, characterized in that the porous gridding precursor according to any one of claims 1 to 8 is added with a lithium source or a sodium source, and is obtained by heating and sintering.
CN202311470554.3A 2023-11-07 2023-11-07 Porous gridding precursor, preparation method thereof and positive electrode material Pending CN117534130A (en)

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