CN115275168A - High-rate lithium ion battery negative electrode material and preparation method thereof - Google Patents

High-rate lithium ion battery negative electrode material and preparation method thereof Download PDF

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CN115275168A
CN115275168A CN202211063078.9A CN202211063078A CN115275168A CN 115275168 A CN115275168 A CN 115275168A CN 202211063078 A CN202211063078 A CN 202211063078A CN 115275168 A CN115275168 A CN 115275168A
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lithium salt
solution
graphite composite
composite material
ion battery
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王福寿
王福国
王福山
裴成勇
裴国军
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Xinjiang Tianhongji Technology Co ltd
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    • H—ELECTRICITY
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    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
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    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
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    • H—ELECTRICITY
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    • 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
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    • H01M4/0438—Processes of manufacture in general by electrochemical processing
    • H01M4/045—Electrochemical coating; Electrochemical impregnation
    • H01M4/0452—Electrochemical coating; Electrochemical impregnation from solutions
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
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    • 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
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
    • H—ELECTRICITY
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    • H—ELECTRICITY
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    • 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
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    • H—ELECTRICITY
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    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
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    • 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
    • H—ELECTRICITY
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    • 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
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/027—Negative electrodes
    • 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
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    • 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 high-rate lithium ion battery cathode material and a preparation method thereof. A preparation method of a high-rate lithium ion battery negative electrode material comprises the following steps: (1) Adding inorganic lithium salt, nitric acid compound, organic nitrogen compound and additive into water and mixing uniformly to obtain solution A; (2) Preparing a porous graphite composite material B doped with a rare earth compound; (3) Adding the porous graphite composite material B into the solution A, adding a graphene oxide solution, uniformly mixing, filtering, washing and vacuum drying to obtain an inorganic lithium salt-coated graphite complex; (4) Scanning, washing, drying, sintering at high temperature and crushing by adopting an electrochemical deposition method and taking the inorganic lithium salt coated graphite complex as a working electrode to obtain the lithium ion battery cathode material. According to the technical scheme, the first-time efficiency and the quick charging capacity of the graphite can be improved, and the energy density and the high-temperature performance of the graphite are considered.

Description

High-rate lithium ion battery negative electrode material and preparation method thereof
Technical Field
The invention belongs to the field of preparation of lithium ion battery materials, and particularly relates to a high-rate lithium ion battery cathode material and a preparation method thereof.
Background
At present, the marketable negative electrode material mainly uses artificial graphite, the resistance is reduced mainly by reducing the aggregate particle size and coating amorphous carbon on the surface of the artificial graphite, but the energy density is reduced by reducing the aggregate particle size of the material or increasing the carbon coating amount, so that the selection of the proper aggregate particle size or the control of the coating amount of the material is very necessary. At present, the main measures for improving the quick charging performance of the material are to coat the surface of the graphite core with a material with low electronic or ionic impedance, improve the interface impedance between the core and the shell, and improve the diffusion rate and the electronic conduction rate of the material.
At present, the marketized artificial graphite is mainly coated with amorphous carbon on the outer layer but can only meet the charging capacity of less than or equal to 4C, the specific capacity of less than or equal to 350mAh/g and the compaction density of less than or equal to 1.6g/cm 3 The preparation method is generally a solid phase or liquid phase method, and the consistency is poor, so that the charging capability and the energy density of the material can not meet the future requirements.
In view of the above, the invention provides a high-rate lithium ion battery negative electrode material and a preparation method thereof, and a novel material is coated on the surface of the material to improve the power performance and energy density of the material.
Disclosure of Invention
The invention aims to provide a preparation method of a high-rate lithium ion battery cathode material, which is characterized in that an inorganic lithium salt coated graphite complex with a blocky structure is prepared by a hydrothermal method, and lithium salt is deposited on the surface of the graphite complex by an electrochemical precipitation method, so that the first efficiency is improved; the prepared graphite composite material can improve the quick charging capacity of graphite and give consideration to energy density and high-temperature performance thereof.
In order to realize the purpose, the adopted technical scheme is as follows:
a preparation method of a high-rate lithium ion battery negative electrode material comprises the following steps:
(1) Adding inorganic lithium salt, nitric acid compound, organic nitrogen compound and additive into water, and uniformly mixing to obtain solution A;
(2) Preparing a porous graphite composite material B doped with a rare earth compound;
(3) Adding the porous graphite composite material B into the solution A, uniformly mixing, adding a graphene oxide solution, uniformly mixing, reacting at 100-200 ℃ for 1-6 h, filtering, washing and vacuum drying to obtain an inorganic lithium salt-coated graphite composite body with a blocky structure;
(4) Scanning the graphite composite coated with the inorganic lithium salt as a working electrode 27448by an electrochemical deposition method, taking saturated calomel as a counter electrode and 0.1mol/L dimethyl carbonate (DMC) solution of lithium difluoroborate as a solvent at-2V to 2V and 0.5 to 5mV/s for 10 to 100 weeks, washing with dilute hydrochloric acid, drying, sintering at the high temperature of 800 to 1200 ℃ for 1 to 6 hours, and crushing to obtain the lithium ion battery cathode material.
Further, in the step (1), the mass ratio of the inorganic lithium salt, the nitric acid compound, the organic nitrogen compound and the additive is 100: 80-100: 1 to 10:1 to 10
The mass ratio of solute (inorganic lithium salt, nitric acid compound, organic nitrogen compound and additive) to water in the solution A is 1-10: 100.
further, in the step (1), the inorganic lithium salt is LiCO 3 、LiOH、LiNO 3 、LiCl、LiBr、LiI、Li 2 S、LiF、Li 2 SO 4 、Li 2 SO 3 、LiClO 4 、LiMnO 4 、LiO 2 、Li 2 S 2 O 3 One of (1);
the nitric acid compound is one of magnesium nitrate, calcium nitrate, potassium nitrate and ferric nitrate;
the organic nitrogen compound is one of dimethylamine, dipropylamine, tripropylamine, n-butylamine, diethylamine, ethanolamine and triethylamine;
the additive is Li 2 B 4 O 7 、Li 3 PO 3 、Li 3 NbO 3 To (3) is provided.
Further, in the step (2), the step of preparing the porous graphite composite material B doped with the rare earth compound comprises: dissolving melamine, ammonium hydrogen phosphate and rare earth chloride in water, adding graphite, uniformly mixing, heating and stirring to be gelatinous, drying in vacuum, calcining, and washing to obtain the rare earth compound-doped porous graphite composite material B.
Still further, the rare earth chloride is one of cerium chloride, lanthanum chloride, europium chloride, neodymium chloride or yttrium chloride.
Further, the mass ratio of the melamine to the ammonium hydrogen phosphate to the rare earth chloride to the graphite is (0.5-2).
Further, in the step (2), the mixture is stirred at 50-120 ℃ until the mixture is in a gel state;
calcining for 1-6 h at 200-400 ℃ under inert atmosphere;
washing with dilute hydrochloric acid and deionized water.
Further, in the step (3), the concentration of the graphene oxide is 0.5 to 5wt%.
Further, in the step (3), the mass ratio of the solution a, the porous graphite composite material B and the graphene oxide is 100 to 200.
The invention also aims to provide a high-rate lithium ion battery cathode material which is prepared by the preparation method and has advantages in the aspects of energy density, high-temperature performance, low-temperature performance and the like.
Compared with the prior art, the invention has the beneficial effects that:
1. according to the invention, the inorganic lithium salt is deposited on the surface of the graphite by a chemical method, so that the irreversible capacity loss of the material in the charging and discharging process is reduced, and the first efficiency is improved; meanwhile, the transmission rate of lithium ions in the charge and discharge process of the negative electrode material is improved and the multiplying power performance is improved by means of the characteristic that the self lithium ion conductivity of the inorganic lithium salt of the coating layer is high.
2. According to the invention, the rare earth compound is doped in the core graphite, so that the electronic conductivity of the core is improved, meanwhile, the melamine carbon is sintered at a high temperature of 800-1200 ℃ to obtain the amorphous carbon containing nitrogen, and the combination of nitrogen atoms and carbon atoms has higher electronic conductivity, so that the electronic conductivity of the composite material is improved; the nanometer micron pores left after ammonium hydrogen phosphate carbonization improve the liquid retention capacity of the material, and the phosphorus has high specific capacity, so that the energy density of the material is further improved.
3. According to the invention, the organic lithium salt is deposited on the outer layer of the core graphite by an electrochemical deposition method, so that the compatibility of the material and an electrolyte is improved, the low-temperature performance is improved, and the organic lithium salt interacts with the inorganic lithium salt on the surface of the core graphite and the organic lithium salt on the shell to play a synergistic effect, so that the high-temperature performance and the low-temperature performance of the material are improved.
Drawings
Fig. 1 is an SEM image of the graphite composite material prepared in example 2.
Detailed Description
In order to further illustrate the high-rate lithium ion battery negative electrode material and the preparation method thereof according to the present invention, and achieve the intended purpose of the invention, the following detailed description is provided with reference to the preferred embodiments of the high-rate lithium ion battery negative electrode material and the preparation method thereof according to the present invention, and the specific implementation manner, structure, characteristics and efficacy thereof are described below. In the following description, different "one embodiment" or "an embodiment" refers to not necessarily the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.
The following will further describe in detail a high-rate lithium ion battery negative electrode material and a preparation method thereof in conjunction with specific embodiments:
example 1.
The specific operation steps are as follows:
(1) According to the following steps of 100: 80-100: 1 to 10: 1-10, adding inorganic lithium salt, nitric acid compound, organic nitrogen compound and additive into deionized water to prepare solution A.
Wherein the inorganic lithium salt is LiCO 3 、LiOH、LiNO 3 、LiCl、LiBr、LiI、Li 2 S、LiF、Li 2 SO 4 、Li 2 SO 3 、LiClO 4 、LiMnO 4 、LiO 2 、Li 2 S 2 O 3 One of (1);
the nitric acid compound is one of magnesium nitrate, calcium nitrate, potassium nitrate and ferric nitrate;
the organic nitrogen compound is one of dimethylamine, dipropylamine, tripropylamine, n-butylamine, diethylamine, ethanolamine and triethylamine;
the additive is Li 2 B 4 O 7 、Li 3 PO 3 、Li 3 NbO 3 One kind of (1).
The mass ratio of the solute to the solvent in the solution A is 1-10.
(2) Dissolving melamine, ammonium hydrogen phosphate and rare earth chloride in deionized water, carrying out ultrasonic treatment for 30min, then adding artificial graphite, uniformly mixing, heating and stirring at 50-120 ℃ to form gel, carrying out vacuum drying, calcining at 200-400 ℃ for 1-6 h under an inert atmosphere, and sequentially washing with dilute hydrochloric acid and deionized water for 10 times to obtain a porous graphite composite material B;
wherein the rare earth chloride is one of cerium chloride, lanthanum chloride, europium chloride, neodymium chloride or yttrium chloride.
The mass ratio of melamine, ammonium hydrogen phosphate, rare earth chloride and graphite is (0.5-2).
(3) And adding the porous graphite composite material B into the solution A, uniformly mixing, adding 0.5-5 wt% of graphene oxide solution, uniformly mixing, transferring into a high-pressure reaction kettle, carrying out hydrothermal reaction at 100-200 ℃ for 1-6 h, filtering, washing and drying in vacuum to obtain the inorganic lithium salt-coated graphite complex with the blocky structure.
Wherein the mass ratio of the solution A to the porous graphite composite material B to the graphene is 100-200.
(4) Adopting an electrochemical deposition method, taking an inorganic lithium salt coated graphite complex as a working electrode 27448and saturated calomel as a counter electrode, taking 0.1mol/L DMC solution of lithium difluoroborate as a solvent, adopting a cyclic voltammetry method, scanning for 10-100 weeks at-2V-2V and 0.5-5 mV/s, washing with dilute hydrochloric acid, drying, sintering at the high temperature of 800-1200 ℃ for 1-6 h, and crushing to obtain the graphite composite material.
According to the invention, through the process of depositing the inorganic lithium salt on the graphite surface by chemical deposition and electrochemically depositing the lithium salt, the lithium salt compound with high lithium ion conductivity is uniformly and densely coated on the graphite surface, the intercalation and deintercalation rate and the first efficiency of lithium ions in the charging and discharging processes are improved, and meanwhile, the rare earth compound is doped on the surface of the lithium salt compound, so that the structural stability of the material is improved, and the cycle performance is improved.
Example 2.
The specific operation steps are as follows:
(1) 100g of lithium carbonate, 90g of magnesium nitrate, 5g of dimethylamine and 5g of Li were weighed 2 B 4 O 7 And adding the mixture into 4000ml of deionized water to prepare a solution A.
(2) 1g of melamine, 3g of ammonium hydrogen phosphate and 3g of cerium chloride are dissolved in 500ml of deionized water, ultrasonic treatment is carried out for 30min, then 100g of artificial graphite is added and mixed uniformly, and the mixture is heated and stirred at the temperature of 80 ℃ until the mixture is gelatinous; and then vacuum drying at 80 ℃ for 24h, calcining at 300 ℃ for 3h under the inert atmosphere of argon, and sequentially washing with dilute hydrochloric acid and deionized water for 10 times respectively to obtain the porous graphite composite material B.
(3) And adding 150g of the porous graphite composite material B into 100ml of the solution A, uniformly mixing, adding 100g of 2wt% graphene oxide solution, uniformly mixing, transferring into a high-pressure reaction kettle, carrying out hydrothermal reaction at 150 ℃ for 3h, filtering, washing, and carrying out vacuum drying at 80 ℃ for 24h to obtain the inorganic lithium salt coated graphite complex with the blocky structure.
(4) The graphite composite material is prepared by adopting an electrochemical deposition method, taking an inorganic lithium salt coated graphite composite as a working electrode, taking saturated calomel as a counter electrode, taking 0.1mol/L dimethyl carbonate (DMC) solution of lithium difluoroborate as a solvent, scanning for 50 weeks at-2V-2V and 1mV/s by adopting a cyclic voltammetry method, washing for 10 times by using dilute hydrochloric acid, drying, sintering for 3 hours at the high temperature of 900 ℃, and crushing to obtain the graphite composite material.
Example 3.
The specific operation steps are as follows:
(1) Weighing 100g LiCl, 80g calcium nitrate, 1g dipropylamine and 1g Li thereof 3 PO 3 Added to 18200ml of deionized water to prepare solution A.
(2) 0.5g of melamine, 1g of ammonium hydrogen phosphate and 1g of lanthanum chloride are dissolved in 1000ml of deionized water, ultrasonic treatment is carried out for 30min, then 100g of artificial graphite is added and mixed evenly, and the mixture is heated and stirred at the temperature of 50 ℃ until the mixture is gelatinous. And then vacuum drying at 80 ℃ for 24h, calcining at 200 ℃ for 6h under the inert atmosphere of argon, and sequentially washing with dilute hydrochloric acid and deionized water for 10 times respectively to obtain the porous graphite composite material B.
(3) Adding 100g of the porous graphite composite material B into 200ml of the solution A, uniformly mixing, adding 200g of 0.5% graphene oxide solution, uniformly mixing, transferring into a high-pressure reaction kettle, carrying out hydrothermal reaction at 100 ℃ for 6 hours, filtering, washing, and carrying out vacuum drying at 80 ℃ for 24 hours to obtain the inorganic lithium salt coated graphite composite with the blocky structure.
(4) The graphite composite material is prepared by adopting an electrochemical deposition method, taking an inorganic lithium salt coated graphite composite as a working electrode, taking saturated calomel as a counter electrode, taking 0.1mol/L dimethyl carbonate (DMC) solution of lithium difluoroborate as a solvent, scanning for 10 weeks at-2V-2V and 0.5mV/s by adopting a cyclic voltammetry method, washing with dilute hydrochloric acid, drying, sintering at 800 ℃ for 6h, and crushing.
Example 4.
The specific operation steps are as follows:
(1) Weighing 100g of Li 2 SO 3 100g of potassium nitrate, 10g of tripropylamine and 10g of Li 3 NbO 3 Added to 2200ml of deionized water to obtain solution A.
(2) Dissolving 2g of melamine, 5g of ammonium hydrogen phosphate and 5g of neodymium chloride in 1000ml of deionized water, carrying out ultrasonic treatment for 30min, then adding 100g of artificial graphite, uniformly mixing, heating and stirring at 120 ℃ to form a gel, then carrying out vacuum drying at 80 ℃ for 24h, then calcining for 1h at 400 ℃ in an argon inert atmosphere, and sequentially washing for 10 times by using dilute hydrochloric acid and deionized water respectively to obtain the porous graphite composite material B.
(3) And adding 100g of the porous graphite composite material B into 100g of the solution A, uniformly mixing, adding 100g of 5wt% graphene oxide solution, uniformly mixing, transferring to a high-pressure reaction kettle, carrying out hydrothermal reaction at 200 ℃ for 1h, filtering, washing, and carrying out vacuum drying at 80 ℃ for 24h to obtain the inorganic lithium salt coated graphite complex with the blocky structure.
(4) The graphite composite material is prepared by adopting an electrochemical deposition method, taking an inorganic lithium salt coated graphite composite as a working electrode, taking saturated calomel as a counter electrode, taking 0.1mol/L dimethyl carbonate (DMC) solution of lithium difluoroborate as a solvent, scanning for 100 weeks at-2V-2V and 5mV/s by adopting a cyclic voltammetry method, washing with dilute hydrochloric acid, drying, sintering at the high temperature of 1200 ℃ for 1h in the argon atmosphere, and crushing.
Comparative example 1:
the graphite composite material was obtained by using the inorganic lithium salt-coated graphite composite having a block structure prepared in step (3) in example 2 and pulverizing the graphite composite.
Comparative example 2.
The preparation method comprises the steps of adopting an electrochemical deposition method, taking artificial graphite as a working electrode, saturated calomel as a counter electrode, 0.1mol/L dimethyl carbonate (DMC) solution of lithium difluoroborate as a solvent, adopting a cyclic voltammetry method, scanning for 50 weeks at-2V-2V and 1mV/s, washing with dilute hydrochloric acid, drying, sintering at 900 ℃ for 3 hours under an argon atmosphere, and crushing to obtain the graphite composite material.
1. Physical and chemical property test
1.1 SEM test
The graphite composite material prepared in example 2 was subjected to SEM test, and the test results are shown in fig. 1. As can be seen from FIG. 1, the graphite composite material obtained in example 2 was in the form of particles having a uniform size distribution and a particle diameter of 10 to 15 μm.
1.2 powder conductivity test:
pressing the powder into a blocky structure, and then testing the conductivity of the powder by adopting a four-probe tester. The test results are shown in table 1.
1.3 powder compaction Density test
The graphite composite materials of examples 2 to 4 and comparative examples 1 to 2 were subjected to a powder compaction density test. During testing, powder with a certain mass is weighed and placed in a mold, 2T pressure pressing is adopted (a powder compaction density instrument is adopted, 1g of powder is placed in a fixed kettle and then is pressed by 2T pressure, the kettle is kept still for 10S, the size of the pressed powder is calculated, and the compaction density is calculated), and the powder compaction density is calculated. Meanwhile, according to GB/T243358-2019 graphite cathode materials for lithium ion batteries, test results are shown in Table 1.
TABLE 1
Item Example 2 Example 3 Example 4 Comparative example 1 Comparative example 2
Resistivity of powder (. OMEGA. M) 8*10 -8 5*10 -8 6*10 -8 8*10 -7 7*10 -7
Powder compacted density (g/cm) 3 ) 1.69 1.66 1.64 1.51 1.53
Specific surface area (m) 2 /g) 1.82 1.77 1.68 1.21 1.38
As can be seen from Table 1, the powder resistivity of the artificial graphite composite material prepared by the invention is obviously lower than that of the comparative example, because the inner core and the outer shell of the negative electrode material are respectively doped with inorganic lithium salt, rare earth compound and organic lithium salt to reduce the electronic and ionic resistivity; and the electrochemical deposition method has the characteristic of high density, and the powder compaction density is improved.
2. Button cell test
The graphite composite materials in examples 2 to 4 and comparative examples 1 to 2 were assembled into button cells A1, A2, A3, B1, B2, respectively. The assembling method comprises the following steps: and adding a binder, a conductive agent and a solvent into the negative electrode material, stirring and pulping, coating the mixture on copper foil, and drying and rolling to obtain the negative electrode plate. The binder used was LA132 binder, the conductive agent was SP, the negative electrode materials were the graphite composite materials in examples 2 to 4 and comparative examples 1 to 2, respectively, and the solvent was secondary distilled water. The proportion of each component is as follows: and (3) anode material: SP: LA132: double distilled water =95g:1g:4g:220mL; the electrolyte is LiPF 6 /EC+DEC(LiPF 6 The concentration of (2) is 1.2mol/L, the volume ratio of EC to DEC is 1), the metal lithium sheet is a counter electrode, and the diaphragm adopts a Polyethylene (PE), polypropylene (PP) or polyethylene propylene (PEP) composite membrane. The button cell is assembled in a glove box filled with argon, electrochemical performance test is carried out on a Wuhan blue electricity CT2001A type battery tester, the charging and discharging voltage range is 0.005V-2.0V, and the charging and discharging multiplying power is 0.1C. The test results are shown in table 2.
And simultaneously taking the negative plate, and testing the liquid absorption and retention capacity of the pole piece.
TABLE 2
Figure BDA0003827070660000081
As can be seen from table 2, the first discharge capacity and the first charge-discharge efficiency of the lithium ion battery using the graphite composite negative electrode material obtained in examples 2 to 4 are significantly higher than those of comparative examples 1 to 2, because the organic lithium and the inorganic lithium salt provide sufficient lithium ions for the first charge-discharge of the battery, the specific capacity and the conductivity of the material are improved, the first efficiency is further improved, and meanwhile, the graphite composite material has a high specific surface area, and the liquid absorption capacity of the material can be improved.
3. Pouch cell testing
The graphite composite materials in examples 2 to 4 and comparative examples 1 to 2 were used as negative electrode materials to prepare negative electrode sheets. With ternary materials (LiNi) 1/3 Co 1/3 Mn 1/3 O 2 ) As the positive electrode, liPF 6 Solution (solvent EC + DEC, volume ratio 1,lipf 6 Concentration 1.3 mol/L) as electrolyte and celegard2400 as diaphragm, and 2Ah soft package batteries A10, A20, A30, B10 and B20 are prepared. And then testing the cycle performance (1C/1C, 25 ℃, 2.8-4.2V) and rate performance of the soft package battery.
Multiplying power performance test conditions: charging rate: 1C/2C/3C/5C, discharge multiplying power of 1C; voltage range: 2.8-4.2V.
The test results are shown in Table 3.
TABLE 3
Figure BDA0003827070660000091
As can be seen from table 3, the soft package battery prepared from the graphite composite material of the present invention has a better constant current ratio, and the reason is that the surface of the material in the embodiment is coated with inorganic lithium, which can provide sufficient lithium ions in the charging and discharging processes, improve the fast charging performance of the material, i.e., improve the constant current ratio of the material, and improve the cycle performance.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention in any way, and any simple modification, equivalent change and modification made to the above embodiments according to the technical spirit of the present invention are within the scope of the technical solution of the present invention.

Claims (10)

1. A preparation method of a high-rate lithium ion battery negative electrode material is characterized by comprising the following steps:
(1) Adding inorganic lithium salt, nitric acid compound, organic nitrogen compound and additive into water, and uniformly mixing to obtain solution A;
(2) Preparing a porous graphite composite material B doped with a rare earth compound;
(3) Adding the porous graphite composite material B into the solution A, uniformly mixing, adding a graphene oxide solution, uniformly mixing, reacting at 100-200 ℃ for 1-6 h, filtering, washing and vacuum drying to obtain an inorganic lithium salt-coated graphite composite body with a blocky structure;
(4) Scanning the graphite complex coated with the inorganic lithium salt as a working electrode, saturated calomel as a counter electrode and 0.1mol/L dimethyl carbonate solution of lithium difluoroborate as a solvent at-2V and 0.5-5 mV/s for 10-100 weeks by adopting an electrochemical deposition method, washing with dilute hydrochloric acid, drying, sintering at the high temperature of 800-1200 ℃ for 1-6 h, and crushing to obtain the lithium ion battery cathode material.
2. The method according to claim 1,
in the step (1), the mass ratio of the inorganic lithium salt, the nitric acid compound, the organic nitrogen compound and the additive is 100: 80-100: 1 to 10:1 to 10;
the mass ratio of inorganic lithium salt, nitric acid compound, organic nitrogen compound, additive and water in the solution A is 1-10: 100.
3. the method according to claim 1,
in the step (1), the inorganic lithium salt is LiCO 3 、LiOH、LiNO 3 、LiCl、LiBr、LiI、Li 2 S、LiF、Li 2 SO 4 、Li 2 SO 3 、LiClO 4 、LiMnO 4 、LiO 2 、Li 2 S 2 O 3 One of (1);
the nitric acid compound is one of magnesium nitrate, calcium nitrate, potassium nitrate and ferric nitrate;
the organic nitrogen compound is one of dimethylamine, dipropylamine, tripropylamine, n-butylamine, diethylamine, ethanolamine and triethylamine;
the additive is Li 2 B 4 O 7 、Li 3 PO 3 、Li 3 NbO 3 One kind of (1).
4. The method according to claim 1,
in the step (2), the step of preparing the porous graphite composite material B doped with the rare earth compound comprises the following steps: dissolving melamine, ammonium hydrogen phosphate and rare earth chloride in water, adding graphite, uniformly mixing, heating and stirring to be gelatinous, drying in vacuum, calcining, and washing to obtain the porous graphite composite material B doped with the rare earth compound.
5. The production method according to claim 4,
the rare earth chloride is one of cerium chloride, lanthanum chloride, europium chloride, neodymium chloride and yttrium chloride.
6. The production method according to claim 4,
the mass ratio of the melamine to the ammonium hydrogen phosphate to the rare earth chloride to the graphite is (0.5-2).
7. The method according to claim 4,
in the step (2), the mixture is stirred to be in a gel state at the temperature of 50-120 ℃;
calcining for 1-6 h at 200-400 ℃ in an inert atmosphere;
washing with dilute hydrochloric acid and deionized water.
8. The production method according to claim 1,
in the step (3), the concentration of the graphene oxide is 0.5-5 wt%.
9. The production method according to claim 1,
in the step (3), the mass ratio of the solution A to the porous graphite composite material B to the graphene oxide is (100-200).
10. The high-rate lithium ion battery negative electrode material is characterized by being prepared by the preparation method of any one of claims 1 to 9.
CN202211063078.9A 2022-09-01 2022-09-01 High-rate lithium ion battery negative electrode material and preparation method thereof Pending CN115275168A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115911306A (en) * 2022-11-07 2023-04-04 晖阳(贵州)新能源材料有限公司 High-energy-density graphite composite material and preparation method thereof

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115911306A (en) * 2022-11-07 2023-04-04 晖阳(贵州)新能源材料有限公司 High-energy-density graphite composite material and preparation method thereof
CN115911306B (en) * 2022-11-07 2023-08-22 晖阳(贵州)新能源材料有限公司 High-energy-density graphite composite material and preparation method thereof

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