CN110429249B - Preparation method of rubber-stripped graphene composite electrode material - Google Patents

Preparation method of rubber-stripped graphene composite electrode material Download PDF

Info

Publication number
CN110429249B
CN110429249B CN201910640273.5A CN201910640273A CN110429249B CN 110429249 B CN110429249 B CN 110429249B CN 201910640273 A CN201910640273 A CN 201910640273A CN 110429249 B CN110429249 B CN 110429249B
Authority
CN
China
Prior art keywords
graphene
rubber
energy storage
graphite
storage active
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
CN201910640273.5A
Other languages
Chinese (zh)
Other versions
CN110429249A (en
Inventor
汤庆国
黄彬
王丽
王菲
梁金生
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Hebei University of Technology
Original Assignee
Hebei University of Technology
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hebei University of Technology filed Critical Hebei University of Technology
Priority to CN201910640273.5A priority Critical patent/CN110429249B/en
Publication of CN110429249A publication Critical patent/CN110429249A/en
Application granted granted Critical
Publication of CN110429249B publication Critical patent/CN110429249B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • 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
    • H01M4/362—Composites
    • H01M4/364—Composites as mixtures
    • 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
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
    • H01M4/505—Selection 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
    • 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
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection 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
    • 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
    • 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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/621—Binders
    • H01M4/622—Binders being polymers
    • 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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/624—Electric conductive fillers
    • H01M4/625—Carbon or graphite
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Abstract

The invention relates to a preparation method of a rubber-stripped graphene composite electrode material. The method comprises the steps of driving rubber to strip crystalline flake graphite, expandable graphite or expanded graphite by mechanical force, enabling the layers of the rubber to be separated gradually, forming a single-layer or few-layer graphene or oxidized graphene composite rubber block, adding energy storage active substances such as lithium iron phosphate into composite rubber, and mixing, pouring and packaging to form the energy storage active substance-rubber composite rubber block in which graphene or graphene energy storage active substances are uniformly dispersed; and (3) obtaining the energy storage active substance-graphene mixed foam gel through high-temperature roasting, and finally preparing the anode material and the cathode material of the lithium ion battery. The invention can greatly improve the high-rate charge and discharge performance of the conventional lithium ion battery and improve the charge speed.

Description

Preparation method of rubber-stripped graphene composite electrode material
Technical Field
The invention relates to a method for preparing a high-performance electrode material by using graphene as a raw material, wherein the graphene is formed by driving rubber molecules to strip crystalline flake graphite by using mechanical force, and belongs to the preparation of graphene and application in the field of energy storage.
Background
The lithium ion battery is a battery which uses lithium metal or lithium alloy as a negative electrode material and uses a non-aqueous electrolyte solution, has the advantages of higher specific energy, lower self-discharge, long cycle life, stable battery structure, no memory effect and the like, and is widely applied to various fields such as communication, computers, transportation, aerospace and the like as a mobile power supply. Pore structure and surface features of electrode materialThe optimization can change the performance of the lithium ion battery, and researches show that the electrochemical performance of the lithium ion battery can be improved by improving the specific surface area, the pore structure and the conductivity of the electrode material. The composition and structure of the anode material of the lithium ion battery have great influence on the battery capacity, cycle times, charge and discharge multiplying power and the like, and the commonly used anode material is LiMO2(M ═ Ni, Co, etc.), lithium iron phosphate (LPF), ternary material (LiNi)xCoyMnO2) And the like. Albeit of a layered structure of LiCoO2The lithium ion battery is a cathode material which is firstly applied in commercialization, but the lithium ion battery is not widely used due to the defects of scarce cobalt resource, high price, poor thermal stability and the like. The ternary material integrates the advantages of various materials, but the production process has severe conditions, higher cost and poor safety, and the preparation technology still needs to be further broken through. The lithium iron phosphate with the olivine structure has high specific capacity, no toxicity, low price and good safety performance, and becomes one of the hottest power battery anode materials in recent years, but the lithium iron phosphate has low conductivity and low lithium ion migration, so that conductive agent active substances such as conductive carbon black, a carbon nanotube, graphene and the like must be added to improve the conductivity of the anode.
Researches show that the graphene has excellent conductivity, so that the graphene has a good application prospect in the lithium ion battery anode material. If the graphene and the lithium iron phosphate material are mixed, the conductivity of the lithium iron phosphate can be theoretically improved, and the rate capability of the battery is improved. The reason for this is that: the graphene can obviously improve the dispersibility of the lithium iron phosphate particles, form a three-dimensional conductive network, improve the conductivity of the material and improve the rate capability, thereby improving the capacity of the material to the maximum extent. Patents on graphene as a material for lithium ion batteries include not only cathode (negative electrode) materials but also a large number of anode (positive electrode) materials.
The lithium ion battery is a 2-time battery system in which 2 different lithium intercalation compounds capable of reversibly intercalating and deintercalating lithium ions are used as a positive electrode and a negative electrode of the battery, respectively. The positive electrode and the negative electrode of the lithium ion battery comprise the following components: the electrode active material carbon material or non-carbon material, adhesive and additive are mixed to make paste adhesive, and then uniformly coated on two sides of aluminium foil and copper foil respectively, and then dried and rolled to obtain the positive electrode material and negative electrode material, and its performance depends on that the positive electrode material and negative electrode material which can reversibly remove/insert lithium ion can be prepared. Patents as cathode materials such as CN109585849A, CN109546083A, CN106159245A, CN107507967A, CN107394185A, CN108807932A, and the like; the positive electrode material occupies a large proportion in the lithium ion battery, the performance of the positive electrode material directly influences the performance of the lithium ion battery, and the cost of the positive electrode material also directly influences the price of the battery. Relating to the preparation patents of positive electrode materials of graphene lithium batteries, ZL 201310459260, CN105206799A, CN106711447A, CN107331845A, CN108807992A,
CN109037560A, CN109037666A, CN109119616A, CN108493397A, CN109290155A, CN108878842A, CN 108807897A; the negative electrode or the positive electrode material is prepared by oxidizing the graphene sold in the market or crystalline flake graphite in a strong acid environment to form graphene oxide, and reducing the graphene oxide or doping metal in conductive graphite to improve the specific capacity and the conductivity of the electrode material. The commercial graphene used by the method has high preparation cost and large wastewater discharge amount, not only brings environmental problems, but also has extremely high surface energy and surface activity due to the huge specific surface area of the graphene, and is extremely easy to agglomerate and graphitize again in the preparation, dispersion, drying, storage and transportation processes; by using a conventional stirring and mixing method, the graphene is difficult to be uniformly dispersed into a matrix of energy storage active materials such as lithium iron phosphate, lithium cobaltate, lithium manganate and the like in a single-layer or few-layer graphene state to form a three-dimensional conductive network structure.
Disclosure of Invention
The invention aims to provide a preparation method of a rubber-stripped graphene composite electrode material aiming at the defects in the prior art. The method comprises the steps of driving rubber to strip crystalline flake graphite (corresponding to stripping of graphene), or expandable graphite and expandable graphite (corresponding to stripping of graphene oxide) by mechanical force, separating the sheets gradually to form a single-layer or few-layer graphene or graphene oxide composite rubber block, adding energy storage active substances such as lithium iron phosphate and the like into the graphene or graphene oxide composite rubber, and mixing, inverting and packaging to form a graphene-energy storage active substance-rubber composite rubber block or a graphene oxide-energy storage active substance-rubber composite rubber block in which graphene and energy storage active substances are uniformly dispersed; the energy storage active substance-graphene composite foam gel is obtained by decomposing and carbonizing organic substances and reducing graphene oxide through high-temperature roasting, is used as a raw material of a conductive active substance, is ground, added with an adhesive and a solvent, is uniformly mixed, and is coated, dried and pressed to prepare a positive electrode material and a negative electrode material of a lithium ion battery, so that the high-rate charge and discharge performance of the conventional lithium ion battery is greatly improved, and the charging speed is improved.
The technical scheme of the invention is as follows:
a preparation method of a rubber-stripped graphene composite electrode material comprises the following steps:
step 1: exfoliation of graphite platelets
Adding a rubber matrix and graphite raw materials into an internal mixer, carrying out internal mixing for 3-20min, and then transferring into a double-rod open mill for mixing for 10-60min to obtain a composite rubber block containing 4-45% of graphene or graphene oxide;
wherein the mass ratio of the rubber matrix to the graphite raw material is 100: 5-70;
step 2: incorporation of energy storage active substances
Adding the composite rubber block obtained in the previous step into a running roll pair, rolling and wrapping the roll, adding 5-30ml of energy storage active material powder and dioctyl phthalate, and mixing for 10-30 minutes to form a graphene-energy storage active material-rubber composite film or a graphene oxide-energy storage active material-rubber composite film;
wherein the mass of the energy storage active substance is 3-9 times of that of graphene or graphene oxide contained in the composite rubber block;
and step 3: carbonization of compounded rubber
Placing the graphene or graphene oxide-energy storage active material-composite rubber sheet obtained in the previous step into a crucible, covering, placing into heating equipment, and roasting at 500-1000 ℃ for 10-50 min to obtain an energy storage active material-graphene carbonized foam;
and 4, step 4: grinding dispersion of energy storage active material-graphene carbonized foam
Grinding the energy storage active material-graphene carbonized foam, and then sieving the ground material with a 200-350-mesh sieve to obtain energy storage active material-graphene conductive agent active powder;
the grinding of the energy storage active material-graphene carbonized foam in the step 4 is manual grinding in a mortar, or grinding by a ball mill in a ball milling tank, wherein the rotating speed of the ball mill is 400-1000 rpm, the grinding is carried out for 15-60 min, the mass ratio of material balls is 1:2-4, and the grinding balls are zirconium oxide with the diameter of 2 mm.
The application of the rubber-stripped graphene composite electrode material is used for assembling the graphene button lithium ion battery.
The method comprises the following steps:
(1) preparation of positive pole piece of graphene lithium ion battery
Adding an adhesive into the energy storage active material-graphene conductive agent active powder, magnetically stirring for 3-10 h, dripping a solvent, and continuously stirring for 3-6 h to form a sticky paste mixture; uniformly coating the pasty mixture on an aluminum foil, putting the aluminum foil into a vacuum drying oven for drying, pressing the aluminum foil into a film on a double-rod film pressing machine, and cutting the film into pole pieces with the diameter of 14mm to obtain working electrodes;
wherein, the mass of the adhesive is 5-10% of the energy storage active substance-graphene conductive agent active powder; the ratio of the volume (ml) of the added solvent to the mass (g) of the energy storage active material-graphene conductive agent active powder is 1-4: 1; the coating amount per unit area of the aluminum foil was 5mg/cm based on the amount of the viscous paste-like mixture2-20mg/cm2After drying, pressing the mixture by a roller film to form a uniform conductive coating film with the thickness of 50-120 mu m;
(2) in a vacuum glove box filled with argon, the prepared corresponding anode material membrane is taken as an anode, a metal lithium sheet is taken as a cathode, 1M LiPF 6/dimethyl carbonate (DMC) + Ethylene Carbonate (EC) + Ethyl Methyl Carbonate (EMC) (volume ratio of 1: 1: 1) is taken as electrolyte, a Celgard2400 microporous polypropylene membrane is taken as a membrane to assemble button cells of different models, the assembled cells are put into a copper mold and screwed down by a pliers, and the lithium ion battery taking the roasted rubber-stripped graphene as the anode conductive material is obtained;
the charge and discharge performance test adopts a Land test system to carry out cycle and rate performance test on the battery at room temperature (25 +/-1 ℃), and the test voltage is between 3.5V and 4.95V.
The graphite raw materials in the step 1 are crystalline flake graphite, expanded graphite and expandable graphite;
the rubber matrix comprises: natural rubber, styrene-butadiene rubber, ethylene propylene diene monomer, chloroprene rubber or nitrile rubber;
and 2, the energy storage active matter is lithium iron phosphate, lithium cobaltate or lithium manganate.
Step 3 the heating apparatus comprises: carbonizing and roasting in a microwave oven, a tubular furnace, a muffle furnace, a vacuum sintering furnace or the like;
the roasting in the step 3 is carried out in a nitrogen or hydrogen atmosphere with a certain flow rate; when the graphite raw material is flake graphite, the atmosphere is nitrogen; when the graphite starting material is expanded graphite or expandable graphite, the atmosphere is hydrogen; the gas flow is 0.005L/min-5L/min, and the pressure of the vacuum furnace is 0.1pa-100 pa;
the adhesive in the step 5 is one of polyvinylidene fluoride, polyacrylic acid, polyvinyl alcohol, gelatin, carboxymethyl cellulose and the like;
the solvent in the step 5 is one or a mixture of N, N-dimethylformamide, phthalic acid alkyl amide, N-methylpyrrolidone and dimethylacetamide;
the invention has the substantive characteristics that:
the patent proposes that rubber is driven by mechanical force to peel off crystalline flake graphite, expandable graphite or expanded graphite and the like to form a uniform graphene and graphene oxide composite rubber block with high graphene or graphene oxide content; then adding energy storage active substances such as lithium iron phosphate, lithium cobaltate, lithium manganate and the like, continuously utilizing the mechanical force of a roll-to-roll machine to uniformly disperse the energy storage active substances into a graphene and graphene oxide composite rubber block, roasting at high temperature to decompose and carbonize a rubber matrix, reducing the graphene oxide in the rubber matrix into graphene in a reducing atmosphere or in formed carbon monoxide gas, thereby forming energy storage active substance-graphene composite foam block particles, and grinding and sieving to obtain a uniform energy storage active substance-graphene energy storage conductive agent active substance; mixing with adhesive and solvent to form paste, coating adhesive, drying, pressing film, cutting and assembling to obtain the invented lithium ion battery with excellent high-rate charge and discharge performance. The method is a method for efficiently and cheaply obtaining the high-performance energy storage active substance-graphene conductive material raw material in batches, and the graphene conductive material raw material can be used as a positive electrode material, a negative electrode material or a capacitor material of a lithium ion battery, so that the high-rate charge and discharge performance of the conventional lithium ion battery can be greatly improved, and the charge speed, the capacity and the energy density are improved.
The invention has the beneficial effects that:
the rubber is driven by mechanical force to peel off the crystalline flake graphite, the expandable graphite or the expanded graphite, so that graphite flake layers are gradually separated to form a single-layer or few-layer graphene and graphene oxide composite rubber block with the graphene content of up to 40%; then adding energy storage active substances such as lithium iron phosphate, lithium cobaltate, lithium manganate and the like, continuously and uniformly dispersing the energy storage active substances into the graphene and graphene oxide composite rubber block by using mechanical force, roasting the mixture by using a microwave oven, a tube furnace and a vacuum furnace to decompose and carbonize a rubber matrix, reducing the graphene oxide into graphene, forming composite foam block particles which are uniformly mixed with the energy storage active substances and have a three-dimensional conductive network structure and are mutually interpenetrated, and grinding and sieving the composite foam block particles to obtain a uniform energy storage active substance-graphene energy storage conductive agent active substance; and the material is taken as the raw material of the energy storage and conductive material to prepare the anode material or the cathode material of the lithium ion battery. Therefore, as compared with the lithium ion battery made of the commercial graphene cathode material, the charging and discharging curve of the commercial graphene battery in example 1 has a fast attenuation of the 5C charging and discharging curve, and the 5C charging performance is only 65.1% of that of the sample in example 1, while the discharging performance is 66.9%; the method can be used for stripping the graphene from the rubber, fully dispersing the energy storage active substance into the matrix of the graphene composite rubber by combining with mechanical force, and then forming uniform energy storage active substance-graphene mixed powder through roasting decomposition, so that the ion transmission distance can be shortened after the film is prepared, and the high-rate charge and discharge performance of the lithium ion battery can be greatly improved.
Drawings
FIG. 1 shows the X-ray diffraction patterns of the chloroprene rubber mixed flake graphite, the commercially available graphene and the chloroprene rubber exfoliated flake graphite in example 1.
FIG. 2 is a charge-discharge curve of a button cell assembled by using the lithium ion battery anode material of the sample in example 1;
fig. 3 is a charge and discharge curve of a button cell assembled by adding commercially available graphene with the same proportion as that of example 1 to lithium iron phosphate as a positive electrode material of a lithium ion battery; it can be seen that the large-rate charging and discharging curves, particularly the 5C charging and discharging curves, decay rapidly, the 5C charging curve is 65.1% of that of the sample in example 1, and the discharging performance is 66.9%;
FIG. 4 is a charge-discharge curve of a button cell assembled by using the sample of example 2 as a positive electrode material of a lithium ion battery;
Detailed Description
The material is specifically a composite rubber block of graphene and graphene oxide stripped by different types of rubber, and graphene carbonized foam formed after roasting and graphene formed after grinding; the commercially available graphene used in the control sample is a product of new graphene materials of heptatai hetailong.
The experimental crystalline flake graphite is high-purity crystalline flake graphite produced by commercial crystalline flake graphite mineral powder manufacturers in Lingshou county Shuolong mineral product processing factories; expandable graphite is available from Qingdao morning positive graphite, Inc.; the expanded graphite is prepared by placing expandable graphite of QINGDAOYANG graphite GmbH in a muffle furnace at 1000 deg.C, maintaining the temperature for 100s, and taking out the product on the sieve which passes through a standard sieve of 40 meshes.
The lithium iron phosphate is industrial grade powder produced by Tianjin Stelan energy science and technology GmbH, is pure-phase lithium iron phosphate, and has a particle size D after ultrasonic dispersion97＝2.15μm。
Example 1
Step 1 exfoliation of graphite sheet
Adding 100g of chloroprene rubber into a 0.2L internal mixer, adding 30g of crystalline flake graphite, starting up, carrying out internal mixing for 15min, taking out, transferring into a double-roller open mill, and continuously mixing for 30min to obtain a chloroprene rubber-peeled graphene composite block with the mass percent of graphene being 23%. (the rotation speed of the internal mixer is 40 rpm; the differential speed of two rollers of the double-roller mill is 1:1.3, the rotation speed of the front roller is 18.6 rpm.)
Step 2 mechanical mixing of lithium iron phosphate
Weighing 100g of chloroprene rubber stripped graphene composite block with the graphene content of 23% prepared in the step 1, putting the block into a running roller of a double-roller machine, rolling and wrapping the roller (within 1 min), gradually adding 140g of lithium iron phosphate powder and 30ml of dioctyl phthalate, mixing and rolling for 30min, returning all the lithium iron phosphate powder sprayed out of the roller to the double roller, mixing the lithium iron phosphate powder and the colloid, performing triangular wrapping for 10 times, and thinly discharging the block to form a uniform graphene-lithium iron phosphate-rubber composite block;
step 3 carbonization of composite rubber block
Placing the chloroprene rubber stripped graphene-lithium iron phosphate-rubber composite block prepared in the step 2 into a porcelain boat, placing the porcelain boat into a 800W microwave oven, introducing nitrogen and heating for 20min, and controlling the flow rate of the nitrogen to be 1L/min so as to fully carbonize the graphene-lithium iron phosphate-rubber composite block prepared in the step 2 and form a lithium iron phosphate-graphene carbonized foam;
step 4, grinding and dispersing the lithium iron phosphate-graphene carbonized foam
Putting the lithium iron phosphate-graphene carbonized foam prepared in the step 3 into a ball milling tank, adding zirconium oxide grinding balls with the diameter of 2mm according to the mass ratio of the material balls to be 1:4, grinding for 15min when the ball milling machine rotates at 1000rpm, and sieving by a 325-mesh sieve, wherein the part below the sieve is lithium iron phosphate-graphene conductive agent active powder, namely a composite electrode material;
step 5, preparing the positive pole piece of the graphene lithium ion battery
Adding polyvinylidene fluoride adhesive with the mass of 7.5% of that of the powder into the lithium iron phosphate-graphene conductive agent active powder prepared in the step 4, magnetically stirring for 6 hours, adding N-methyl pyrrolidone solvent with the same volume as the powder in mass, continuously stirring for 5 hours to form a uniform paste mixture, and mixing the paste mixture material according to the ratio of 20mg/cm2Uniformly coating on 16 μm thick aluminum foil, drying in vacuum drying oven at 120 deg.C for 12 hr, and pressing on a double-roller film pressing machine to obtain uniform coatingCutting the membrane into a pole piece with the diameter of 14mm to obtain a working electrode, and putting the working electrode into a vacuum glove box filled with argon for circulation for 4 hours for later use;
step 6, assembling the graphene button type lithium ion battery
In a vacuum glove box filled with argon, the prepared corresponding anode material membrane is taken as an anode, a metal lithium sheet is taken as a cathode, 1MLiPF 6/dimethyl carbonate (DMC) + Ethylene Carbonate (EC) + Ethyl Methyl Carbonate (EMC) (volume ratio of 1: 1: 1) is taken as electrolyte, a Celgard2400 microporous polypropylene membrane is taken as a diaphragm to assemble a CR2032 type button cell, the assembled cell is put into a copper mold and is tightened by a pliers, and the lithium ion battery taking the rubber stripping graphene as the anode conductive material is obtained;
the charge and discharge performance of the samples in the examples is tested by adopting a Land test system to carry out cycle and rate performance tests on the battery at room temperature (25 +/-1 ℃), the test voltage is between 3.5V and 4.95V, and the samples in the examples 2 to 6 are the same.
The charge and discharge test curve of the lithium ion battery is shown in figure 2, the charge and discharge curve of a control sample prepared by mixing and stirring commercially available graphene and conductive active substances in the same proportion is shown in figure 3, and the test results of the charge and discharge performance with different multiplying powers are shown in the attached table 1
X-ray diffraction analysis is performed on three samples of graphene composite latex blocks formed by stripping chloroprene rubber from crystalline flake graphite in the embodiment and mixed latex blocks of crystalline flake graphite mixed with chloroprene rubber before stripping, and the obtained results are shown in fig. 1, and the comparison of diffraction patterns of the samples shows that the diffraction peak intensity of the mixed latex blocks (an upper curve) of crystalline flake graphite and chloroprene rubber at a 2 theta angle of 26.56 degrees is 147466, the diffraction peak intensity of the graphene composite latex blocks (a lower curve) formed by stripping is only 1151, the diffraction peak intensity is only 0.78% of that of rubber mixed crystalline flake graphite, and the half width of the peak is greatly increased, which indicates that crystalline flake graphite is stripped by rubber to form graphene latex blocks;
the diffraction peak intensity (middle curve) of the commercially available graphene in fig. 1 is 17190, which is much higher than 1151 of the graphene composite gel block formed by peeling, and it is illustrated that a part of graphene re-agglomerates to a certain extent during storage and transportation, has a tendency of secondary "graphitization", is difficult to be uniformly dispersed into lithium iron phosphate by simple mechanical stirring to form a three-dimensional conductive network structure, and the electron mobility is hindered to lower the charge and discharge performance, which is a key to influence the high-rate charge and discharge performance, especially the 5C charge and discharge performance of the battery anode material.
In fig. 2, chloroprene rubber is peeled off from graphene to be used as a conductive active material raw material, the conductive active material raw material is mechanically mixed with lithium iron phosphate, the mixture is roasted to form lithium iron phosphate-graphene carbonized foam, and the lithium iron phosphate-graphene carbonized foam is ground, added with an adhesive, modulated by a solvent, coated, dried and pressed into a film to be used as the positive electrode of a lithium ion battery to assemble a charge-discharge curve of a button cell;
fig. 3 is a charge and discharge curve of a button cell assembled by adding commercially available graphene in the same proportion as that in example 1 to lithium iron phosphate, fully grinding, adding an adhesive, a solvent for modulation, coating, drying, and pressing a film, and then using the graphene as the positive electrode of a lithium ion battery; it can be seen that the large-rate charging and discharging curves, particularly the 5C charging and discharging curves, decay rapidly, the 5C charging curve is 65.1% of that of the sample in example 1, and the discharging performance is 66.9%;
example 2
Step 1 exfoliation of graphite sheet
Adding 100g of nitrile rubber into a 0.2L internal mixer, adding 40g of crystalline flake graphite, starting the internal mixer, carrying out internal mixing for 15min, taking out the mixture, transferring the mixture into a double-roll open mill, and continuously mixing for 50min to obtain the nitrile rubber-peeled graphene composite rubber block with the graphene mass percentage content of 28.6%.
Step 2 mechanical mixing of lithium iron phosphate
Weighing 100g of nitrile rubber stripped graphene composite rubber block with the graphene content of 28.6% prepared in the step 1, putting the nitrile rubber stripped graphene composite rubber block into a running roller of a double-roller machine, mixing and wrapping the nitrile rubber stripped graphene composite rubber block, gradually adding 114g of lithium iron phosphate powder and 15ml of dioctyl phthalate, mixing and rolling for 15min, returning all the lithium iron phosphate powder sprayed out of the nitrile rubber stripped graphene composite rubber block to the double roller, mixing the lithium iron phosphate powder and the dioctyl phthalate into the double roller, wrapping the mixture by using a triangular bag for 10 times, and thinly discharging the mixture to form a uniform graphene-lithium iron phosphate-rubber composite rubber block;
step 3 carbonization of composite rubber block
Putting the nitrile rubber peeled graphene-lithium iron phosphate-rubber composite block prepared in the step 2 into a porcelain boat, putting the ceramic boat into a tubular furnace, introducing nitrogen and heating, controlling the flow rate of the nitrogen to be 2L/min, heating the temperature to 700 ℃ at a heating rate of 20 ℃/min, and keeping the temperature at 700 ℃ for 20min to fully carbonize the nitrile rubber peeled graphene-lithium iron phosphate-rubber composite block prepared in the step 2 to form a lithium iron phosphate-graphene carbonized foam;
step 4, grinding and dispersing the lithium iron phosphate-graphene carbonized foam
Putting the lithium iron phosphate-graphene carbonized foam prepared in the step 3 into a ball milling tank, adding zirconium oxide grinding balls with the diameter of 2mm according to the mass ratio of the material balls to the material balls of 1:2, grinding for 50min at the rotating speed of 700rpm of the ball mill, and sieving by a 300-mesh sieve, wherein the part below the sieve is lithium iron phosphate-graphene conductive agent active powder, namely a composite electrode material;
step 5, preparing the positive pole piece of the graphene lithium ion battery
Adding gelatin with the mass of 10% of the powder into the lithium iron phosphate-graphene conductive agent active powder prepared in the step 4, magnetically stirring for 8 hours, adding N-methyl pyrrolidone solvent with the mass of 7.5% of the powder, continuously stirring for 6 hours to form a uniform paste mixture, and mixing the paste mixture material according to the ratio of 10mg/cm2Uniformly coating on an aluminum foil with the thickness of 16 mu m, drying for 12h at 120 ℃ in a vacuum drying oven, pressing to form a film on a double-rod film pressing machine, cutting into a pole piece with the diameter of 14mm to obtain a working electrode, and putting the electrode into a vacuum glove box filled with argon for circulation for 4h for later use;
step 6, assembling the graphene button type lithium ion battery
In a vacuum glove box filled with argon, the prepared corresponding anode material membrane is taken as an anode, a metal lithium sheet is taken as a cathode, 1MLiPF 6/dimethyl carbonate (DMC) + Ethylene Carbonate (EC) + Ethyl Methyl Carbonate (EMC) (volume ratio of 1: 1: 1) is taken as electrolyte, a Celgard2400 microporous polypropylene membrane is taken as a diaphragm to assemble a CR2032 type button cell, the assembled cell is put into a copper mold and is tightened by a pliers, and the lithium ion battery taking the rubber stripping graphene as the anode conductive material is obtained;
the charge and discharge test curves of the lithium ion battery of the embodiment are shown in FIG. 4, and the test results of the charge and discharge performance with different multiplying powers are shown in the attached Table 1
Example 3
Step 1 exfoliation of graphite sheet
Adding 100g of natural rubber into a 0.2L internal mixer, adding 20g of expandable graphite crystals, starting up, carrying out internal mixing for 10min, taking out, transferring into a double-roll open mill, and continuously mixing for 50min to obtain the natural rubber exfoliated graphene oxide composite rubber block with the graphene oxide mass percentage content of 16.8%.
Step 2 mechanical mixing of lithium manganate
Weighing 100g of the natural rubber exfoliated expandable graphite composite block with the graphene oxide content of 16.8% prepared in the step 1, putting the block into a roller of a running roll-to-roll machine, rolling and wrapping the roller, gradually adding 84g of lithium manganate powder and 5ml of dioctyl phthalate, mixing and rolling for 10min, returning all the lithium iron phosphate powder sprayed outside the roller to the roller in the process, mixing the lithium iron phosphate powder with the colloid, performing triangular wrapping for 10 times, and thinly discharging the mixture to form the graphene oxide-lithium manganate-rubber composite block;
step 3 carbonization of composite rubber block
Placing the natural rubber peeled graphene oxide-lithium manganate-rubber composite rubber block prepared in the step 2 into a porcelain boat, placing the porcelain boat into a vacuum sintering furnace, closing the porcelain boat, vacuumizing, heating, controlling the pressure in the furnace to be 0.05-10 pa, raising the temperature at a rate of 20 ℃/min to 600 ℃, and keeping the temperature for 50min, so that the graphene oxide-lithium manganate-rubber composite rubber block prepared in the step 2 is decomposed and fully carbonized, and the graphene oxide is reduced to form a lithium manganate-graphene carbonized foam;
step 4, grinding and dispersing the lithium manganate-graphene carbonized foam
Putting the lithium manganate-graphene carbonized foam prepared in the step 3 into a ball milling tank, adding zirconium oxide grinding balls with the diameter of 2mm according to the mass ratio of the material balls to the material balls of 1:2, grinding for 45min at the rotating speed of 800rpm of the ball mill, and sieving by a 250-mesh sieve, wherein the part under the sieve is lithium manganate-graphene conductive agent active powder, namely a composite electrode material;
step 5, preparing the positive pole piece of the graphene lithium ion battery
Adding carboxymethyl cellulose with the powder mass being 5% into the lithium manganate-graphene conductive agent active powder prepared in the step 4, magnetically stirring for 10 hours, dripping phthalic acid alkyl amide solvent with the powder mass being 5%, continuously stirring for 3 hours to form uniform sticky paste-like mixture, and mixing the sticky paste-like mixture material according to the ratio of 5mg/cm2Uniformly coating on an aluminum foil with the thickness of 16 mu m, drying for 12h at 120 ℃ in a vacuum drying oven, pressing to form a film on a double-rod film pressing machine, cutting into a pole piece with the diameter of 14mm to obtain a working electrode, and putting the electrode into a vacuum glove box filled with argon for circulation for 4h for later use;
step 6, assembling the graphene button type lithium ion battery
In a vacuum glove box filled with argon, the prepared corresponding anode material membrane is taken as an anode, a metal lithium sheet is taken as a cathode, 1MLiPF 6/dimethyl carbonate (DMC) + Ethylene Carbonate (EC) + Ethyl Methyl Carbonate (EMC) (volume ratio of 1: 1: 1) is taken as electrolyte, a Celgard2400 microporous polypropylene membrane is taken as a diaphragm to assemble a CR2032 type button cell, the assembled cell is put into a copper mold and is tightened by a pliers, and the lithium ion battery taking the rubber stripping graphene as the anode conductive material is obtained;
the test results of the charging and discharging performance of the battery with different multiplying powers are shown in the attached table 1
Example 4
Step 1 exfoliation of graphite sheet
Adding 100g of ethylene propylene diene monomer into a 0.2L internal mixer, adding 70g of crystalline flake graphite, starting up, internally mixing for 20min, taking out, transferring into a double-roller open mill, and continuously mixing for 60min to obtain an ethylene propylene diene monomer composite rubber block with the graphene mass percentage content of 41.1%.
Step 2 mechanical mixing of lithium iron phosphate
Weighing 100g of the ethylene propylene diene monomer composite rubber block with the graphene content of 41.1% prepared in the step 1, putting the ethylene propylene diene monomer composite rubber block into a running roller of a double-roller machine, rolling and wrapping the roller, gradually adding 123.3g of lithium iron phosphate powder and 20ml of dioctyl phthalate, mixing and rolling for 25min, returning all the lithium iron phosphate powder sprayed out of the roller to the double roller during the rolling process, mixing the lithium iron phosphate powder and the colloid, performing triangular wrapping for 10 times, and thinly discharging the sheet to form the graphene-lithium iron phosphate-rubber composite rubber block;
step 3 carbonization of composite rubber block
Putting the ethylene propylene diene monomer rubber-stripped graphene-lithium iron phosphate-rubber composite block prepared in the step 2 into a porcelain boat, putting the porcelain boat into a tubular furnace, introducing nitrogen and heating, controlling the hydrogen flow to be 0.2L/min, heating the temperature to 1000 ℃ at the heating rate of 15 ℃/min, and keeping the temperature for 10min, so that the ethylene propylene diene monomer rubber-stripped graphene-lithium iron phosphate-rubber composite block prepared in the step 2 is fully carbonized to form a lithium iron phosphate-graphene carbonized foam body;
step 4, grinding and dispersing the lithium iron phosphate-graphene carbonized foam
Putting the lithium iron phosphate-graphene carbonized foam prepared in the step 3 into a ball milling tank, adding zirconium oxide grinding balls with the diameter of 2mm according to the mass ratio of the material balls to be 1:4, grinding for 60min when the ball milling machine rotates at 400rpm, and sieving by a 200-mesh sieve, wherein the part below the sieve is lithium iron phosphate-graphene conductive agent active powder, namely a composite electrode material;
step 5, preparing the positive pole piece of the graphene lithium ion battery
Adding polyvinylidene fluoride with the powder mass of 6% into the lithium iron phosphate-graphene conductive agent active powder prepared in the step 4, magnetically stirring for 10 hours, adding N-methyl pyrrolidone solvent with the powder mass of 10%, continuously stirring for 4 hours to form a uniform paste mixture, and mixing the paste mixture material according to the ratio of 15mg/cm2Uniformly coating on an aluminum foil with the thickness of 16 mu m, drying for 12h at 120 ℃ in a vacuum drying oven, pressing to form a film on a double-rod film pressing machine, cutting into a pole piece with the diameter of 14mm to obtain a working electrode, and putting the electrode into a vacuum glove box filled with argon for circulation for 4h for later use;
step 5, assembling of graphene button type lithium ion battery
In a vacuum glove box filled with argon, the prepared corresponding anode material membrane is taken as an anode, a metal lithium sheet is taken as a cathode, 1MLiPF 6/dimethyl carbonate (DMC) + Ethylene Carbonate (EC) + Ethyl Methyl Carbonate (EMC) (volume ratio of 1: 1: 1) is taken as electrolyte, a Celgard2400 microporous polypropylene membrane is taken as a diaphragm to assemble a CR2032 type button cell, the assembled cell is put into a copper mold and is tightened by a pliers, and the lithium ion battery taking the rubber stripping graphene as the anode conductive material is obtained;
the test results of the charging and discharging performance of the battery with different multiplying powers are shown in the attached table 1
Example 5
Step 1 exfoliation of graphite sheet
Adding 100g of styrene-butadiene rubber into a 0.2L internal mixer, adding 5.0g of expanded graphite crystals, starting up, carrying out internal mixing for 3min, taking out, transferring into a double-roll open mill, and continuously mixing for 10min to obtain the styrene-butadiene rubber composite block with the graphene oxide mass percentage content of 4.76%.
Step 2 mechanical mixing of lithium cobaltate
Weighing 100g of the styrene-butadiene rubber composite rubber block with the graphene oxide content of 4.76% prepared in the step 1, putting the block into a running roller of a double-roller machine, rolling and wrapping the roller, gradually adding 42.84g of lithium manganate powder and 5ml of dioctyl phthalate, mixing and rolling for 12min, returning all the lithium iron phosphate powder sprayed out of the roller to the double roller during the rolling process, mixing the lithium iron phosphate powder into the rubber, performing triangular wrapping for 10 times, and thinly discharging the rubber block to form the graphene oxide-lithium cobaltate-rubber composite rubber block;
step 3 carbonization of composite rubber block
Placing the styrene butadiene rubber stripped graphene oxide-lithium cobaltate-rubber composite rubber block prepared in the step 2 into a porcelain boat, placing the porcelain boat into a muffle furnace, introducing hydrogen and heating, controlling the hydrogen flow to be 0.005L/min, raising the temperature to 500 ℃ at the temperature raising rate of 20 ℃/min, and keeping the temperature for 50min, so that the ethylene propylene diene monomer stripped graphene oxide-lithium cobaltate-rubber composite rubber block prepared in the step 2 is fully carbonized, and the graphene oxide is reduced to form a lithium cobaltate-graphene carbonized foam body;
step 4, grinding and dispersing the lithium cobaltate-graphene carbonized foam
Putting the lithium cobaltate-graphene carbonized foam prepared in the step 3 into a ball milling tank, adding zirconium oxide grinding balls with the diameter of 2mm according to the mass ratio of the material balls to the material balls being 1:3, grinding for 50min at the rotating speed of 800rpm of the ball mill, and sieving with a 350-mesh sieve, wherein the part below the sieve is lithium cobaltate-graphene conductive agent active powder, namely a composite electrode material;
step 5, preparing the positive pole piece of the graphene lithium ion battery
Adding polyacrylic acid with the powder mass of 9% into the lithium cobaltate-graphene conductive agent active powder prepared in the step 4, magnetically stirring for 3 hours, adding N, N-dimethylformamide solvent with the powder mass of 6%, continuously stirring for 5 hours to form a uniform paste mixture, and mixing the paste mixture material according to the proportion of 12mg/cm2Uniformly coating on an aluminum foil with the thickness of 16 mu m, drying for 12h at 120 ℃ in a vacuum drying oven, pressing to form a film on a double-rod film pressing machine, cutting into a pole piece with the diameter of 14mm to obtain a working electrode, and putting the electrode into a vacuum glove box filled with argon for circulation for 4h for later use;
step 6, assembling the graphene button type lithium ion battery
In a vacuum glove box filled with argon, the prepared corresponding anode material membrane is taken as an anode, a metal lithium sheet is taken as a cathode, 1MLiPF 6/dimethyl carbonate (DMC) + Ethylene Carbonate (EC) + Ethyl Methyl Carbonate (EMC) (volume ratio of 1: 1: 1) is taken as electrolyte, a Celgard2400 microporous polypropylene membrane is taken as a diaphragm to assemble a CR2032 type button cell, the assembled cell is put into a copper mold and is tightened by a pliers, and the lithium ion battery taking the rubber stripping graphene as the anode conductive material is obtained;
the test results of the charging and discharging performance of the battery with different multiplying powers are shown in the attached table 1
Example 6
Step 1 exfoliation of graphite sheet
Adding 20g of styrene-butadiene rubber and 80g of natural rubber into a 0.2L internal mixer, adding 25g of expanded graphite crystals, carrying out internal mixing for 5min, taking out, transferring into a double-roll open mill, and continuously mixing for 40min to obtain the mixed rubber composite block with the graphene oxide content of 20% by mass.
Step 2 mechanical mixing of lithium iron phosphate
Weighing 100g of the mixed rubber composite block prepared in the step 1 and containing 20% of graphene oxide, putting the mixed rubber composite block into a running roller of a double-roller machine, rolling and wrapping the roller, gradually adding 140g of lithium iron phosphate powder and 30ml of dioctyl phthalate, mixing and rolling for 20min, returning all the lithium iron phosphate powder sprayed out of the roller to the double roller during the period, mixing the lithium iron phosphate powder into the rubber, performing triangular wrapping for 10 times, and thinly discharging the rubber composite block to form the graphene oxide-lithium iron phosphate-rubber composite block;
step 3 carbonization of composite rubber block
Putting the mixed rubber-stripped graphene oxide-lithium iron phosphate-rubber composite block prepared in the step 2 into a porcelain boat, putting the porcelain boat into a muffle furnace, introducing hydrogen and heating, controlling the hydrogen flow to be 0.5L/min, heating the mixed rubber-stripped graphene oxide-lithium iron phosphate-rubber composite block to 600 ℃ at the heating rate of 15 ℃/min, and keeping the temperature for 20min, so that the mixed rubber-stripped graphene oxide-lithium iron phosphate-rubber composite block prepared in the step 2 is fully carbonized, and the graphene oxide is reduced to form a lithium iron phosphate-graphene carbonized foam body;
step 4, grinding and dispersing the lithium iron phosphate-graphene carbonized foam
Putting the lithium iron phosphate-graphene carbonized foam prepared in the step 3 into a ball milling tank, adding zirconium oxide grinding balls with the diameter of 2mm according to the mass ratio of the material balls to be 1:3, grinding for 40min at the rotating speed of 600rpm of the ball mill, and sieving by a 300-mesh sieve, wherein the part below the sieve is lithium iron phosphate-graphene conductive agent active powder, namely a composite electrode material;
step 5, preparing the positive pole piece of the graphene lithium ion battery
Adding polyvinyl alcohol with the powder mass being 10% into the lithium iron phosphate-graphene conductive agent active powder prepared in the step 4, magnetically stirring for 8 hours, adding N-methyl pyrrolidone solvent with the powder mass being 8% into the mixture, continuously stirring for 4 hours to form a uniform paste mixture, and mixing the paste mixture material according to the proportion of 15mg/cm2Uniformly coating on an aluminum foil with the thickness of 16 mu m, drying for 12h at 120 ℃ in a vacuum drying oven, pressing to form a film on a double-rod film pressing machine, cutting into a pole piece with the diameter of 14mm to obtain a working electrode, and putting the electrode into a vacuum glove box filled with argon for circulation for 4h for later use;
step 5, assembling of graphene button type lithium ion battery
In a vacuum glove box filled with argon, the prepared corresponding anode material membrane is taken as an anode, a metal lithium sheet is taken as a cathode, 1MLiPF 6/dimethyl carbonate (DMC) + Ethylene Carbonate (EC) + Ethyl Methyl Carbonate (EMC) (volume ratio of 1: 1: 1) is taken as electrolyte, a Celgard2400 microporous polypropylene membrane is taken as a diaphragm to assemble a CR2032 type button cell, the assembled cell is put into a copper mold and is tightened by a pliers, and the lithium ion battery taking the rubber stripping graphene as the anode conductive material is obtained;
the test results of the charging and discharging performance of the battery with different multiplying powers are shown in the attached table 1
TABLE 1 specific charge-discharge capacity test results of battery samples
Figure BDA0002131613700000101
Adding commercially available graphene with the same proportion in the embodiment 1 into lithium iron phosphate, grinding and mixing, adding an adhesive, fully grinding, adding a solvent, uniformly mixing, coating, drying, pressing a film, assembling a button cell as the positive electrode of the lithium ion battery, and detecting the charging and discharging performance to obtain charging and discharging curves under different multiplying power conditions; comparing the charging and discharging data under different multiplying power conditions of example 1, example 2, example 4 and example 6 in table 1, in which lithium iron phosphate is used as the energy storage active material, it can be seen that the charging and discharging curve of the commercially available positive electrode material obtained by directly mixing graphene and lithium iron phosphate is higher than that of 1C, particularly the charging and discharging curve at 5C is fast attenuated, the charging curve at 5C is 65.1% of that of the sample in example 1, and the discharging performance is 66.9%, compared with the positive electrode material obtained by mixing the powder obtained by pulverizing the lithium iron phosphate-graphene carbonized foam formed by calcining at high temperature after using the graphene composite rubber block obtained by stripping graphite as the dispersing medium through mechanical strong mixing.
After the graphene composite rubber block obtained by stripping graphite from rubber is subjected to strong mixing operation by a double-roller machine, the energy storage active material lithium iron phosphate is uniformly mixed into the graphene composite rubber block to form composite foam block particles which are mutually interpenetrated and have a three-dimensional conductive network structure, and the composite foam block particles are roasted, ground and sieved to obtain a very uniform lithium iron phosphate-graphene energy storage conductive agent active substance; the phenomenon that the radiation intensity of the commercially available graphene is 14.9 times higher than the diffraction intensity of rubber-stripped graphene in fig. 1 fully proves that the commercially available graphene forms the agglomerated graphene with a graphite-like state, the agglomerated graphene is difficult to be uniformly dispersed into conductive active substances such as lithium iron phosphate and the like through simple mechanical mixing to form a three-dimensional conductive network structure, and the performance is reduced due to the hindered electron mobility, so that the agglomerated graphene is the key for influencing the high-rate charge and discharge performance of the battery anode material, particularly the 5C charge and discharge performance.
In the same method, the energy storage active substance is mixed with the carbonized graphene conductive agent active powder prepared in the step 3, an adhesive is added for magnetic stirring, and a solvent is dripped to form a uniform and sticky mixture. Uniformly coating the paste mixture on a copper foil, performing vacuum drying, pressing the paste mixture on a double-rod film pressing machine to form a film, cutting the film into a pole piece with the diameter of 14mm to obtain a working electrode, and putting the working electrode into a vacuum glove box filled with argon for circulation to obtain a negative electrode material;
besides the CR2032 button cell, the anode material can be made into CR2025, CR2020, CR2016, CR2450, CR2430 and the like according to the diameter and thickness difference of the cell;
the invention is not the best known technology.

Claims (9)

1. A preparation method of a rubber-stripped graphene composite electrode material is characterized by comprising the following steps:
step 1: exfoliation of graphite platelets
Adding a rubber matrix and graphite raw materials into an internal mixer, carrying out internal mixing for 3-20min, and then transferring into a double-rod open mill for mixing for 10-60min to obtain a composite rubber block containing 4-45% of graphene or graphene oxide;
wherein the mass ratio is that the rubber matrix: graphite raw material =100: 5-70;
step 2: incorporation of energy storage active substances
Adding the composite rubber block obtained in the previous step into a running roll pair, rolling and wrapping the roll, adding 5-30ml of energy storage active substance powder and dioctyl phthalate, and mixing for 10-30 minutes to form a graphene-energy storage active substance-rubber composite film or a graphene oxide-energy storage active substance-rubber composite film;
wherein the mass of the energy storage active substance is 3-9 times of that of graphene or graphene oxide contained in the composite rubber block;
and step 3: carbonization of compounded rubber
Placing the graphene or graphene oxide-energy storage active material-composite rubber sheet obtained in the previous step into a crucible, covering, placing into heating equipment, and roasting at 500-1000 ℃ for 10-50 min to obtain an energy storage active material-graphene carbonized foam;
and 4, step 4: grinding dispersion of energy storage active material-graphene carbonized foam
Grinding the energy storage active material-graphene carbonized foam, and then sieving the ground material with a 200-350-mesh sieve to obtain energy storage active material-graphene conductive agent active powder, namely the composite electrode material.
2. The method for preparing a rubber-exfoliated graphene composite electrode material according to claim 1, wherein the grinding of the energy storage active material-graphene carbonized foam in the step 4 is manual grinding in a mortar or ball mill grinding in a ball mill pot, the rotation speed of the ball mill is 400-1000 rpm, the grinding is 15-60 min, the mass ratio of material balls is 1:2-4, and the grinding balls are zirconium oxide with the diameter of 2 mm.
3. The method for preparing a rubber-exfoliated graphene composite electrode material as claimed in claim 1, wherein the graphite raw materials in step 1 are flake graphite, expanded graphite and expandable graphite.
4. The method for preparing a rubber-exfoliated graphene composite electrode material as claimed in claim 1, wherein the rubber matrix includes: natural rubber, styrene-butadiene rubber, ethylene propylene diene monomer, chloroprene rubber or nitrile rubber.
5. The method according to claim 1, wherein the energy storage active material in step 2 is lithium iron phosphate, lithium cobaltate, or lithium manganate.
6. The method for preparing a rubber-exfoliated graphene composite electrode material as claimed in claim 1, wherein the heating apparatus in step 3 includes: a microwave oven, a tube furnace, a muffle furnace, or a vacuum sintering furnace.
7. The method for preparing a rubber-exfoliated graphene composite electrode material as claimed in claim 1, wherein the baking in step 3 is performed in a nitrogen or hydrogen atmosphere; when the graphite raw material is flake graphite, the atmosphere is nitrogen; when the graphite starting material is expanded graphite or expandable graphite, the atmosphere is hydrogen; the gas flow is 0.005L/min-5L/min, and the pressure of the vacuum furnace is 0.1Pa-100 Pa.
8. Use of the rubber-exfoliated graphene composite electrode material prepared by the method of claim 1, characterized in that it is used for the assembly of graphene button lithium ion batteries.
9. The use of a rubber-exfoliated graphene composite electrode material as claimed in claim 8, including the steps of:
(1) adding an adhesive into the energy storage active material-graphene conductive agent active powder, magnetically stirring for 3-10 h, dripping a solvent, and continuously stirring for 3-6 h to form a sticky paste mixture; uniformly coating the pasty mixture on an aluminum foil, putting the aluminum foil into a vacuum drying oven for drying, pressing the aluminum foil into a film on a double-rod film pressing machine, and cutting the film into pole pieces to obtain working electrodes;
wherein, the mass of the adhesive is 5-10% of the energy storage active substance-graphene conductive agent active powder; the ratio of the volume (ml) of the added solvent to the mass (g) of the energy storage active material-graphene conductive agent active powder is 1-4: 1; every 1cm2The amount of the aluminum foil coated with the paste mixture is 5mg-20 mg;
(2) in a vacuum glove box filled with argon, assembling button cells of different types by using the prepared corresponding anode material membrane as an anode, a metal lithium sheet as a cathode, 1M LiPF 6/dimethyl carbonate (DMC) + Ethylene Carbonate (EC) + Ethyl Methyl Carbonate (EMC) as electrolyte and a Celgard2400 microporous polypropylene membrane as a diaphragm, putting the assembled cells into a copper mold, and screwing the assembled cells by using a pliers to obtain a lithium ion battery taking roasted rubber-stripped graphene as an anode conductive material;
the volume ratio is dimethyl carbonate: ethylene carbonate: ethyl methyl carbonate = 1: 1: 1;
the adhesive is one of polyvinylidene fluoride, polyacrylic acid, polyvinyl alcohol, gelatin and carboxymethyl cellulose;
the solvent is one or a mixture of N, N-dimethylformamide, phthalic acid alkyl amide, N-methylpyrrolidone and dimethylacetamide.
CN201910640273.5A 2019-07-16 2019-07-16 Preparation method of rubber-stripped graphene composite electrode material Active CN110429249B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN201910640273.5A CN110429249B (en) 2019-07-16 2019-07-16 Preparation method of rubber-stripped graphene composite electrode material

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN201910640273.5A CN110429249B (en) 2019-07-16 2019-07-16 Preparation method of rubber-stripped graphene composite electrode material

Publications (2)

Publication Number Publication Date
CN110429249A CN110429249A (en) 2019-11-08
CN110429249B true CN110429249B (en) 2022-01-28

Family

ID=68410675

Family Applications (1)

Application Number Title Priority Date Filing Date
CN201910640273.5A Active CN110429249B (en) 2019-07-16 2019-07-16 Preparation method of rubber-stripped graphene composite electrode material

Country Status (1)

Country Link
CN (1) CN110429249B (en)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104852021A (en) * 2015-03-24 2015-08-19 天津师范大学 Preparation method of graphene/carbon nanotube composite material
CN106496712A (en) * 2016-09-30 2017-03-15 北京化工大学 A kind of reaction in-situ peels off the method that expanded graphite prepares rubber nano composite material
CN108137343A (en) * 2015-10-08 2018-06-08 曼彻斯特大学 Aeroge
CN108602046A (en) * 2015-12-28 2018-09-28 纳米技术仪器公司 Graphene-Carbon Hybrid Foam
CN110010869A (en) * 2019-04-03 2019-07-12 山东星火科学技术研究院 A kind of three-dimensional grapheme conductive network is for cathode of lithium battery and preparation method thereof

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2016152869A1 (en) * 2015-03-24 2016-09-29 積水化学工業株式会社 Active material/flaked graphite composite, negative electrode material for lithium-ion secondary cell, and lithium-ion secondary cell

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104852021A (en) * 2015-03-24 2015-08-19 天津师范大学 Preparation method of graphene/carbon nanotube composite material
CN108137343A (en) * 2015-10-08 2018-06-08 曼彻斯特大学 Aeroge
CN108602046A (en) * 2015-12-28 2018-09-28 纳米技术仪器公司 Graphene-Carbon Hybrid Foam
CN106496712A (en) * 2016-09-30 2017-03-15 北京化工大学 A kind of reaction in-situ peels off the method that expanded graphite prepares rubber nano composite material
CN110010869A (en) * 2019-04-03 2019-07-12 山东星火科学技术研究院 A kind of three-dimensional grapheme conductive network is for cathode of lithium battery and preparation method thereof

Also Published As

Publication number Publication date
CN110429249A (en) 2019-11-08

Similar Documents

Publication Publication Date Title
Bi et al. Recent advances in LiFePO 4 nanoparticles with different morphology for high-performance lithium-ion batteries
JP5864687B2 (en) Method for producing graphene-based composite negative electrode material, and manufactured negative electrode material and lithium ion secondary battery
Qiao et al. One-pot synthesis of CoO/C hybrid microspheres as anode materials for lithium-ion batteries
CN107845797B (en) Nano silicon-carbon composite negative electrode material for lithium ion battery and preparation method thereof
JP2017526118A (en) Multi-component composite negative electrode material, method for producing the same, and lithium ion battery including the same
JP6354895B2 (en) Electrode material, method for producing the electrode material, electrode, and lithium ion battery
CN103199247B (en) Preparation method of composite positive material with multi-level conductive network of lithium ion battery
CN109319757B (en) Method for preparing hollow open onion carbon lithium ion battery cathode material
Huang et al. LiMgxMn2− xO4 (x≤ 0.10) cathode materials with high rate performance prepared by molten-salt combustion at low temperature
CN103560232A (en) Preparation method of S-C positive pole composite material of high cycle performance lithium sulfur battery
CN111333063B (en) Natural graphite-based silicon-carbon composite negative electrode material and preparation method and application thereof
Liu et al. SnO2 nanorods grown on graphite as a high-capacity anode material for lithium ion batteries
CN104638242A (en) Method for synthesizing lithium ion battery cathode material lithium iron phosphate through in situ polymerizing and cladding
Wang et al. Synthesis and electrochemical performance of three-dimensional ordered hierarchically porous Li4Ti5O12 for high performance lithium ion batteries
CN112661163B (en) Silica-based composite anode material, preparation method thereof and lithium ion battery
CN112290022B (en) Lithium ion battery anode lithium supplement additive and preparation method and application thereof
CN111342031A (en) Multi-element gradient composite high-first-efficiency lithium battery negative electrode material and preparation method thereof
WO2023173772A1 (en) Preparation method for and use of hard carbon negative electrode material
CN111048754B (en) Tin-doped rutile TiO2Preparation method and application of composite material
CN113451570A (en) MOF-derived core-shell-structured lithium ion battery negative electrode material and preparation method thereof
Hu et al. Synthesis of α-LiFeO2/Graphene nanocomposite via layer by layer self-assembly strategy for lithium-ion batteries with excellent electrochemical performance
Qiao et al. Solvothermal preparation and lithium storage properties of Fe2O3/C hybrid microspheres
Ran et al. Grinding aid-assisted preparation of high-performance carbon-LiMnPO4
CN104143637A (en) A high-energy-density power battery
CN110429249B (en) Preparation method of rubber-stripped graphene composite electrode material

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant