CN112701287A - FeF3Base composite positive electrode material, preparation method thereof and lithium ion battery - Google Patents

FeF3Base composite positive electrode material, preparation method thereof and lithium ion battery Download PDF

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CN112701287A
CN112701287A CN202011597080.5A CN202011597080A CN112701287A CN 112701287 A CN112701287 A CN 112701287A CN 202011597080 A CN202011597080 A CN 202011597080A CN 112701287 A CN112701287 A CN 112701287A
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mixed solution
mxene
fef
source
precursor
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谭强强
夏青
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Institute of Process Engineering of CAS
Langfang Institute of Process Engineering of CAS
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Langfang Institute of Process Engineering of CAS
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    • 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
    • H01M4/628—Inhibitors, e.g. gassing inhibitors, corrosion inhibitors
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
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    • H01—ELECTRIC ELEMENTS
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    • 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
    • H01M4/58—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
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    • 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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    • H01M4/02—Electrodes composed of, or comprising, active material
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    • 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
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/028—Positive electrodes
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Abstract

The invention discloses a FeF3A composite cathode material, a preparation method thereof and a lithium ion battery are provided. The composite cathode material comprises FeF3Mxene and nitrogen doped carbon material. The method comprises the following steps: 1) preparing a mixed solution containing an iron source, a regulating agent, a nitrogen source and Mxene; 2) drying and calcining the mixed solution to obtain a precursor; 3) wrapping the precursor with a spacer, placing a fluorine source in a first container, respectively placing the precursor wrapped with the spacer and the first container in a closed reactor, and heating to obtain FeF3A base composite positive electrode material; wherein the regulator is used as a carbon source. The invention introduces Mxene and nitrogenThe doped carbon material improves the electronic conductance of the material and constructs the ferric fluoride composite anode material. The lithium ion battery anode material provided by the invention has the advantages of high reversible specific capacity, good rate capability and good cycling stability.

Description

FeF3Base composite positive electrode material, preparation method thereof and lithium ion battery
Technical Field
The invention belongs to the technical field of energy storage materials, relates to a lithium ion battery anode material, and particularly relates to FeF3A composite cathode material, a preparation method thereof and a lithium ion battery are provided.
Background
With the rapid development of new energy automobiles, the lithium ion battery industry has entered a rapid development stage. The key materials influencing the performance of the lithium ion battery mainly comprise a positive electrode material, a negative electrode material, electrolyte and the like. The positive electrode material is a main factor which currently limits the performance of the battery and also a main factor which accounts for the higher cost of the lithium ion battery, and is close to 40%.
Iron fluoride has advantages of high specific capacity, high voltage, and abundant natural resources, and has gradually become one of the most interesting positive electrode materials in recent years. However, the ionic bonding property of metal fluoride causes poor electronic conductivity and ionic diffusion, and the electrochemical performance still needs to be further improved.
CN202010820328.3 discloses a composite ferric trifluoride anode material, a preparation method and application thereof. The synthesis method comprises the following steps: formed of carbon nanohorns and Fe (NO)3)3·9H2FeF synthesized by liquid phase synthesis of O3·0.33H2O-carbon nanohorn composite material for improving FeF3The conductivity is not good.
CN202010443374.6 discloses an iron-based fluoride particle, its preparation method and application. The obtained material comprises a porous octahedral carbon skeleton and ferric fluoride dispersed in the porous octahedral carbon skeleton, and the preparation method comprises the following steps: 1) respectively dispersing ferric salt and terephthalic acid in a solvent, and carrying out solvothermal reaction to obtain Fe-MOF; 2) mixing Fe-MOF and NH4And F is uniformly mixed and then placed in a protective atmosphere to carry out co-pyrolysis reaction, or Fe-MOF is added into a reaction kettle containing HF solution and placed above the liquid level, and heating is carried out to carry out fluorination reaction, so that the iron-based fluoride particles are obtained. The iron-based fluoride particles are porous octahedral and FeF3The carbon nano-particles are uniformly distributed in highly graphitized three-dimensional porous carbon, and the conductivity is high.
Jea Li et al fluorinate Fe by Using HF2O3Method of preparing/C precursor to obtain carbon-coated FeF3A material. The obtained material has a particle size of about 60nm, is beneficial to the full infiltration of electrolyte, and when used as the anode material of a lithium ion battery, the particle size is 20mA g-1Current densityThe first discharge specific capacity is 166.4mAh g-1And the discharge capacity after 100 cycles was 126.3mAh g-1(Li J, Fu L, Xu Z, et al. Electrochimica Acta,2018,281: 88-98.).
However, the reversible specific capacity and the cycle performance of the electrode material obtained by the scheme are to be improved.
Therefore, the development of a lithium ion battery cathode material with better performance is of great significance to the field.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide FeF3A composite cathode material, a preparation method thereof and a lithium ion battery are provided.
In order to achieve the purpose, the invention adopts the following technical scheme:
in a first aspect, the present invention provides a FeF3A composite positive electrode material comprising FeF3Mxene and nitrogen doped carbon material.
The composite anode material is an Mxene/N-C composite ferric fluoride anode material which can be marked as FeF3@ Mxene/N-C composite cathode material, wherein Mxene is a few-layer MXene material (such as few-layer Ti)3C2TxMXene material) with less than 10 layers, and N-C is a nitrogen-doped carbon material, and the composite cathode material has the advantages of high reversible specific capacity, good rate capability, good cycle stability and the like. The technical principle is as follows: the synergy of the Mxene and the N-C in the anode material enables the anode material provided by the invention to have excellent performance, and specifically, the Mxene and the N-C play a role in stabilizing the material structure in the electrode material and improving the electronic conductance of the material, so that the specific capacity, the rate capability and the cycling stability of the material are improved.
Preferably, the mass ratio of the Mxene is 0.01% to 20%, such as 0.01%, 0.1%, 0.5%, 1%, 2%, 3%, 5%, 8%, 10%, 13%, 15%, 18%, 20%, or the like, based on 100% of the total mass of the composite positive electrode material.
Preferably, the mass ratio of the nitrogen-doped carbon material is 0.01% to 10%, for example, 0.01%, 0.1%, 0.5%, 1%, 2%, 3%, 5%, 8%, 10%, or the like, based on 100% of the total mass of the composite positive electrode material.
In a second aspect, the present invention provides a FeF according to the first aspect3A method of preparing a composite positive electrode material, the method comprising the steps of:
(1) preparing a mixed solution containing an iron source, a regulating agent, a nitrogen source and Mxene;
(2) drying and calcining the mixed solution to obtain a precursor;
(3) wrapping the precursor with a spacer, placing a fluorine source in a first container, respectively placing the precursor wrapped with the spacer and the first container in a closed reactor, and heating to obtain FeF3A base composite positive electrode material;
wherein the regulator is used as a carbon source. In the method, the regulating agent is used as a carbon source on one hand, and can regulate and control the size and the shape of particles on the other hand. In the heating treatment process in the step (3), the precursor is wrapped by the spacer, and the fluorine source is contained in the other container, so that the direct contact between the fluorine source with strong activity and the precursor is avoided, the appearance of the precursor is prevented from being damaged, and the generated fluorine-containing steam can be used for carrying out nitrogen doping on the carbon material obtained by converting the regulating agent in the calcining process in the step (2). As a preferable technical scheme of the method, the iron source in the step (1) comprises any one of ferric nitrate, ferric chloride or ferrous oxalate or a combination of at least two of the ferric nitrate, the ferric chloride and the ferrous oxalate.
Preferably, the regulating agent in step (1) is selected from polyvinylidene fluoride and/or polyvinylpyrrolidone, preferably polyvinylidene fluoride. On one hand, the polyvinylidene fluoride is used as a carbon source, on the other hand, the polyvinylidene fluoride has proper viscosity, the shape of the material is favorably regulated and controlled, and the electrochemical performance of the obtained composite anode material is further improved.
Preferably, the nitrogen source of step (1) comprises melamine.
Preferably, the Mxene of step (1) comprises Ti3C2Tx。
Preferably, the concentration of the metal ions in the mixed solution in the step (1) is 0.01mol/L to 2mol/L, such as 0.01mol/L, 0.05mol/L, 0.1mol/L, 0.3mol/L, 0.5mol/L, 1mol/L, 1.2mol/L, 1.5mol/L or 2 mol/L.
Preferably, the metal ions in the mixed solution in the step (1) are iron ions.
Preferably, the mixed solution of step (1) is prepared as follows: dissolving an iron source, a regulator and a nitrogen source in a solvent, and then adding a Mxene dispersion liquid to obtain a mixed solution. This mode can promote the homogeneity that the material mixes.
Preferably, the concentration of Mxene in the dispersion of Mxene is 0.1g/L to 2g/L, such as 0.1g/L, 0.3g/L, 0.5g/L, 0.8g/L, 1g/L, 1.5g/L, or 2g/L, etc.
Preferably, the number of layers of Mxene in the dispersion of Mxene is less than 10, such as 9, 8, 7, 6, 4, 2, etc.
Preferably, the drying manner in step (2) is as follows: the mixed solution is stirred at a certain temperature until dried. The optimized technical scheme can avoid the problem of uniformity reduction caused by material sedimentation and the like.
Preferably, the certain temperature is 60 ℃ to 130 ℃, such as 60 ℃, 70 ℃, 80 ℃, 90 ℃, 100 ℃, 110 ℃, 120 ℃ or 130 ℃ and the like.
Preferably, the calcining of step (2) is performed under an atmosphere of a protective gas, and the protective gas comprises any one of nitrogen, helium or argon or a combination of at least two of nitrogen, helium or argon.
Preferably, the temperature of the calcination in step (2) is 350 ℃ to 900 ℃, such as 350 ℃, 375 ℃, 400 ℃, 450 ℃, 500 ℃, 600 ℃, 700 ℃, 800 ℃, 900 ℃ or the like.
Preferably, the temperature rise rate of the calcination in the step (2) is 1 ℃/min-30 ℃/min, such as 1 ℃/min, 3 ℃/min, 5 ℃/min, 8 ℃/min, 10 ℃/min, 15 ℃/min, 20 ℃/min, 25 ℃/min or 30 ℃/min, and the like.
Preferably, the calcination of step (2) is carried out for a holding time of 1h to 10h, such as 1h, 3h, 5h, 6h, 8h, 9h or 10 h.
Preferably, the fluorine source in step (3) is hydrofluoric acid,
alternatively, the fluorine source is a mixture of lithium fluoride and/or sodium fluoride and hydrochloric acid.
The "lithium fluoride and/or sodium fluoride" means: the lithium fluoride or sodium fluoride may be used, or a mixture of lithium fluoride and sodium fluoride may be used.
Preferably, the mass fraction of hydrofluoric acid is 40% -50%, such as 40%, 42%, 43%, 45%, 47%, or 50%, etc.
Preferably, the molar ratio of the lithium fluoride and/or sodium fluoride to the hydrochloric acid is 1 (0.5-1.5), such as 1:0.5, 1:0.7, 1:0.8, 1:1, 1:1.2, 1:1.5, and the like.
Preferably, the molar ratio of F in the fluorine source to Fe in the iron source is (0.5-6):1, e.g., 0.5:1, 0.8:1, 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 4:1, 5:1, or 6:1, etc.
Preferably, the temperature of the heat treatment in step (3) is 95 ℃ to 130 ℃, such as 95 ℃, 100 ℃, 105 ℃, 110 ℃, 120 ℃, 125 ℃ or 130 ℃, etc.
Preferably, the time of the heat treatment in the step (3) is 6h to 12h, such as 6h, 8h, 9h, 10h, 11h or 12 h.
As a preferable technical scheme of the method, the method further comprises the step of washing and drying the reaction product after the heat treatment in the step (3). The reaction product is generally removed from the separator after step (3), and then washed and dried.
Preferably, the method further comprises subjecting the reaction product of step (3) to step (4) secondary calcination.
Preferably, the secondary calcination is performed under an atmosphere of a protective gas including any one of nitrogen, helium, or argon, or a combination of at least two thereof.
Preferably, the temperature of the secondary calcination in step (4) is 250 ℃ to 450 ℃, such as 250 ℃, 270 ℃, 300 ℃, 325 ℃, 350 ℃, 375 ℃, 400 ℃ or 450 ℃, and the like.
Preferably, the temperature rise rate of the secondary calcination in the step (4) is 1 ℃/min to 30 ℃/min, such as 1 ℃/min, 3 ℃/min, 5 ℃/min, 8 ℃/min, 10 ℃/min, 15 ℃/min, 20 ℃/min, 25 ℃/min or 30 ℃/min, and the like.
Preferably, the holding time of the secondary calcination in the step (4) is 1h to 10h, such as 1.5h, 2h, 3h, 4h, 5h, 6h, 8h, 9h or 10 h.
By introducing the secondary calcining step, residual substances on the surface can be removed, and the material performance is improved.
As a further preferred technical solution of the method of the present invention, the method comprises the steps of:
(1) mixing and dissolving an iron source, a regulator and a nitrogen source in a solvent to obtain a mixed solution A;
(2) adding the Mxene few-layer dispersion liquid with the concentration of 0.1-2 g/L into the mixed solution A to obtain a mixed solution B, wherein the concentration of metal ions in the mixed solution B is 0.01-2 mol/L;
(3) keeping the mixed solution B at 60-130 ℃ and stirring until the mixed solution B is completely dried, and collecting and grinding the obtained powder;
(4) heating the obtained powder to 350-900 ℃ at the speed of 1-30 ℃/min, carrying out heat preservation and calcination for 1-10 h, and cooling to room temperature along with the furnace to obtain a precursor;
(5) placing a small beaker filled with a fluorine source in a closed reaction container, wrapping the precursor with filter paper, placing the coated precursor at the bottom of the reaction container, heating the reactor at 95-130 ℃ for 6-12 h, taking out a reaction product from the filter paper after the reaction is finished, washing and drying;
(6) heating the dried powder to 250-450 ℃ at the speed of 1-30 ℃/min, calcining for 1-10 h, and cooling to obtain FeF3@ Mxene/N-C cathode material; wherein, the Mxene accounts for 0.01-20% of the total mass of the anode material, and the N-C accounts for 0.01-10% of the total mass of the anode.
In a third aspect, the present invention provides a lithium ion battery, which comprises the FeF of the first aspect3A base composite positive electrode material.
Compared with the prior art, the invention has the following beneficial effects:
(1) the FeF provided by the invention3The base composite anode material has high specific capacity, good rate capability,Good cycling stability and the like. Under the voltage window of 1.5-4.5V and the current density of 100mA/g, the first cycle discharge specific capacity is more than 220mAh/g, and the capacity retention rate of 200 cycles is more than 90%; the specific capacity of the cyclic discharge is more than 180mAh/g under the current density of 1000 mA/g.
(2) The lithium ion battery anode material provided by the invention solves the problems of nickel and cobalt element resource shortage, high price and the like in the lithium ion battery industry.
Detailed Description
The technical solution of the present invention is further explained by the following embodiments. The following examples are merely illustrative of the present invention and do not represent or limit the scope of the claims, which are defined by the claims.
Example 1
This example provides a FeF3The preparation method specifically comprises the following steps:
(1) mixing and dissolving ferric nitrate, polyvinylidene fluoride and melamine in deionized water to obtain a mixed solution A;
(2) ti with the concentration of 0.5g/L3C2TxAdding the Mxene few-layer dispersion liquid into the mixed solution A to obtain a mixed solution B, wherein the concentration of iron ions in the mixed solution B is 0.5 mol/L;
(3) keeping the mixed solution B at 80 ℃ and stirring until the mixed solution B is completely dried, and collecting and grinding the obtained powder;
(4) heating the obtained powder to 700 ℃ at the speed of 5 ℃/min, calcining for 4h, and cooling to room temperature along with the furnace to obtain a precursor;
(5) placing a small beaker filled with hydrofluoric acid (the mass fraction of the small beaker is 40%) in a closed reaction container, wrapping the obtained precursor with filter paper, placing the coated precursor at the bottom of the reaction container, heating the reactor at 120 ℃ for 10 hours, taking out a reaction product from the filter paper after the reaction is finished, washing and drying the reaction product;
wherein the molar ratio of F in hydrofluoric acid to Fe in ferric nitrate is 3: 1.
(6) Heating the obtained powder at a speed of 10 ℃/min toCalcining at 300 ℃ for 4h, and cooling to obtain FeF3@ Mxene/N-C positive electrode material, i.e. FeF3A base composite positive electrode material; wherein, FeF3The mass ratio of the Mxene to the composite anode material is 94%, the mass ratio of the Mxene to the composite anode material is 1%, and the mass ratio of the N-C to the composite anode material is 5%.
And (3) testing:
the obtained composite anode material is used as the anode material of the lithium ion battery for electrochemical performance test, and the pole piece ratio is that the anode material: acetylene black: PVDF (mass ratio) 90:5: 5. And preparing the CR2025 button cell by taking a lithium sheet as a reference electrode. Under the current density of 100mA/g, the first cycle specific discharge capacity is 225mAh/g, and the capacity retention rate of 200 cycles of the cycle is 94%; the specific capacity of the cyclic discharge is 183mAh/g under the current density of 1000 mA/g.
Example 2
This example provides a FeF3The preparation method specifically comprises the following steps:
(1) mixing and dissolving ferric chloride, polyvinylidene fluoride and melamine in deionized water to obtain a mixed solution A;
(2) ti with the concentration of 0.1g/L3C2TxAdding the Mxene few-layer dispersion liquid into the mixed solution A to obtain a mixed solution B, wherein the concentration of iron ions in the mixed solution B is 2 mol/L;
(3) keeping the mixed solution B at 130 ℃ and stirring until the mixed solution B is completely dried, and collecting and grinding the obtained powder;
(4) heating the obtained powder to 350 ℃ at the speed of 30 ℃/min, calcining for 10h, and cooling to room temperature along with the furnace to obtain a precursor;
(5) placing a small beaker filled with a mixture of lithium fluoride and hydrochloric acid in a closed reaction container, coating the obtained precursor with filter paper, placing the coated precursor at the bottom of the reaction container, heating the reactor at 95 ℃ for 12 hours, taking out a reaction product from the filter paper after the reaction is finished, washing and drying;
wherein the molar ratio of the lithium fluoride to the hydrochloric acid is 1:1.5, and the molar ratio of F in the lithium fluoride to the ferric nitrate is 0.5: 1.
(6) Heating the obtained powder to 450 ℃ at the speed of 1 ℃/min, calcining for 1h, and cooling to obtain FeF3@ Mxene/N-C positive electrode material, i.e. FeF3A base composite positive electrode material; wherein, FeF3The mass ratio of the mixed solution to the whole composite anode material is 89.99%, the mass ratio of the Mxene to the whole composite anode material is 0.01%, and the mass ratio of the N-C to the whole composite anode material is 10%.
The obtained composite anode material is used as the anode material of the lithium ion battery for electrochemical performance test, and the pole piece ratio is that the anode material: acetylene black: PVDF (mass ratio) 90:5: 5. And preparing the CR2025 button cell by taking a lithium sheet as a reference electrode. Under the current density of 100mA/g, the first cycle specific discharge capacity is 221mAh/g, and the capacity retention rate of 200 cycles of the cycle is 91%; the specific capacity of the cyclic discharge is 180mAh/g under the current density of 1000 mA/g.
Example 3
This example provides a FeF3The preparation method specifically comprises the following steps: (1) mixing and dissolving ferrous oxalate, polyvinylidene fluoride and melamine in deionized water to obtain a mixed solution A;
(2) ti with the concentration of 2g/L3C2TxAdding the Mxene few-layer dispersion liquid into the mixed solution A to obtain a mixed solution B, wherein the concentration of iron ions in the mixed solution B is 0.01 mol/L;
(3) keeping the mixed solution B at 60 ℃ and stirring until the mixed solution B is completely dried, and collecting and grinding the obtained powder;
(4) heating the obtained powder to 900 ℃ at the speed of 1 ℃/min, calcining for 1h, and cooling to room temperature along with the furnace to obtain a precursor;
(5) placing a small beaker filled with a mixture of sodium fluoride and hydrochloric acid in a closed reaction container, coating the obtained precursor with filter paper, placing the coated precursor at the bottom of the reaction container, heating the reactor at 130 ℃ for 6 hours, taking out a reaction product from the filter paper after the reaction is finished, washing and drying;
wherein the molar ratio of the sodium fluoride to the hydrochloric acid is 1:0.5, and the molar ratio of F in the sodium fluoride to the ferric nitrate is 6: 1.
(6) Will be describedHeating the obtained powder to 250 ℃ at the speed of 30 ℃/min, calcining for 10h, and cooling to obtain FeF3@ Mxene/N-C positive electrode material, i.e. FeF3A base composite positive electrode material; wherein, FeF3The mass ratio of the mixed solution to the whole composite anode material is 79.9%, the mass ratio of the Mxene to the whole composite anode material is 20%, and the mass ratio of the N-C to the whole composite anode material is 0.01%.
The obtained composite anode material is used as the anode material of the lithium ion battery for electrochemical performance test, and the pole piece ratio is that the anode material: acetylene black: PVDF (mass ratio) 90:5: 5. And preparing the CR2025 button cell by taking a lithium sheet as a reference electrode. Under the current density of 100mA/g, the first cycle discharge specific capacity is 222mAh/g, and the capacity retention rate of 200 cycles is 90%; the specific capacity of the cyclic discharge is 183mAh/g under the current density of 1000 mA/g.
Example 4
This example provides a FeF3The preparation method specifically comprises the following steps:
(1) mixing and dissolving ferric nitrate, polyvinylidene fluoride and melamine in deionized water to obtain a mixed solution A;
(2) adding the Mxene few-layer dispersion liquid with the concentration of 1.2g/L into the mixed solution A to obtain a mixed solution B, wherein the concentration of iron ions in the mixed solution B is 0.1 mol/L;
(3) keeping the mixed solution B at 100 ℃ and stirring until the mixed solution B is completely dried, and collecting and grinding the obtained powder;
(4) heating the obtained powder to 500 ℃ at the speed of 15 ℃/min, calcining for 4h, and cooling to room temperature along with the furnace to obtain a precursor;
(5) placing a small beaker filled with hydrofluoric acid (the mass fraction of the small beaker is 40%) in a closed reaction container, wrapping the obtained precursor with filter paper, placing the coated precursor at the bottom of the reaction container, heating the reactor at 100 ℃ for 8 hours, taking out a reaction product from the filter paper after the reaction is finished, washing and drying the reaction product;
wherein the molar ratio of F in hydrofluoric acid to Fe in ferric nitrate is 4: 1.
(6) Heating the obtained powder to 350 ℃ at the speed of 2 ℃/min and calcining for 4h,cooling to obtain FeF3@ Mxene/N-C positive electrode material, i.e. FeF3A base composite positive electrode material; wherein, FeF3The mass ratio of the mixed solution to the whole composite anode material is 98.4%, the mass ratio of the Mxene to the whole composite anode material is 0.1%, and the mass ratio of the N-C to the whole composite anode material is 1.5%.
The obtained composite anode material is used as the anode material of the lithium ion battery for electrochemical performance test, and the pole piece ratio is that the anode material: acetylene black: PVDF (mass ratio) 90:5: 5. And preparing the CR2025 button cell by taking a lithium sheet as a reference electrode. Under the current density of 100mA/g, the first cycle discharge specific capacity is 230mAh/g, and the capacity retention rate of 200 cycles is 91%; the specific cyclic discharge capacity is 188mAh/g under the current density of 1000 mA/g.
Example 5
This example provides a FeF3The preparation method specifically comprises the following steps:
(1) mixing and dissolving ferric chloride, polyvinylidene fluoride and melamine in deionized water to obtain a mixed solution A;
(2) ti with the concentration of 1.4g/L3C2TxAdding the Mxene few-layer dispersion liquid into the mixed solution A to obtain a mixed solution B, wherein the concentration of iron ions in the mixed solution B is 1 mol/L;
(3) keeping the mixed solution B at 75 ℃ and stirring until the mixed solution B is completely dried, and collecting and grinding the obtained powder;
(4) heating the obtained powder to 700 ℃ at the speed of 20 ℃/min, calcining for 5h, and cooling to room temperature along with the furnace to obtain a precursor;
(5) placing a small beaker filled with a mixture of lithium fluoride and hydrochloric acid in a closed reaction container, coating the obtained precursor with filter paper, placing the coated precursor at the bottom of the reaction container, heating the reactor at 110 ℃ for 9 hours, taking out a reaction product from the filter paper after the reaction is finished, washing and drying;
wherein the molar ratio of the lithium fluoride to the hydrochloric acid is 1:1, and the molar ratio of F in the lithium fluoride to the ferric nitrate is 5: 1.
(6) Heating the obtained powder to 400 deg.C at a speed of 12 deg.C/minCalcining for 4h, and cooling to obtain FeF3@ Mxene/N-C positive electrode material, i.e. FeF3A base composite positive electrode material; wherein, FeF3The mass ratio of the Mxene to the composite anode material is 81%, the mass ratio of the Mxene to the composite anode material is 15%, and the mass ratio of the N-C to the composite anode material is 4%.
The obtained composite anode material is used as the anode material of the lithium ion battery for electrochemical performance test, and the pole piece ratio is that the anode material: acetylene black: PVDF (mass ratio) 90:5: 5. And preparing the CR2025 button cell by taking a lithium sheet as a reference electrode. Under the current density of 100mA/g, the first cycle specific discharge capacity is 220mAh/g, and the capacity retention rate of 200 cycles is 92%; the specific capacity of the cyclic discharge is 183mAh/g under the current density of 1000 mA/g.
Comparative example 1
(1) Mixing and dissolving ferric nitrate and melamine in deionized water to obtain a mixed solution A;
(2) ti with the concentration of 0.5g/L3C2TxAdding the Mxene few-layer dispersion liquid into the mixed solution A to obtain a mixed solution B, wherein the concentration of iron ions in the mixed solution B is 0.5 mol/L;
(3) keeping the mixed solution B at 80 ℃ and stirring until the mixed solution B is completely dried, and collecting and grinding the obtained powder;
(4) heating the obtained powder to 700 ℃ at the speed of 5 ℃/min, calcining for 4h, and cooling to room temperature along with the furnace to obtain a precursor;
(5) placing a small beaker filled with hydrofluoric acid (the mass fraction of the small beaker is 40%) in a closed reaction container, wrapping the obtained precursor with filter paper, placing the coated precursor at the bottom of the reaction container, carrying out heat treatment on the reactor at 120 ℃ for 10 hours, taking out a reaction product from the filter paper after the reaction is finished, washing and drying the reaction product;
wherein the molar ratio of F in hydrofluoric acid to Fe in ferric nitrate is 3: 1.
(6) Heating the obtained powder to 300 ℃ at the speed of 10 ℃/min, calcining for 4h, and cooling to obtain FeF3@ Mxene cathode material; wherein, the Mxene accounts for 1 percent of the mass ratio of the whole positive electrode material.
The obtained anode material is used as the anode material of the lithium ion battery for electrochemical performance test, and the pole piece ratio is that the anode material: acetylene black: PVDF (mass ratio) 90:5: 5. And preparing the CR2025 button cell by taking a lithium sheet as a reference electrode. Under the current density of 100mA/g, the first cycle discharge specific capacity is 201mAh/g, and the capacity retention rate of 200 cycles of the cycle is 85%; under the current density of 1000mA/g, the specific capacity of cyclic discharge is 153mAh/g
Comparative example 2
(1) Mixing and dissolving ferric nitrate, polyvinylidene fluoride and melamine in deionized water to obtain a mixed solution A; the concentration of iron ions in the solution is 0.5 mol/L;
(2) keeping the mixed solution A at 80 ℃ and stirring until the mixed solution A is completely dried, and collecting and grinding the obtained powder;
(3) heating the obtained powder to 700 ℃ at the speed of 5 ℃/min, calcining for 4h, and cooling to room temperature along with the furnace to obtain a precursor;
(4) placing a small beaker filled with hydrofluoric acid (the mass fraction of the small beaker is 40%) in a closed reaction container, wrapping the obtained precursor with filter paper, placing the coated precursor at the bottom of the reaction container, carrying out heat treatment on the reactor at 120 ℃ for 10 hours, taking out a reaction product from the filter paper after the reaction is finished, washing and drying the reaction product;
wherein the molar ratio of F in hydrofluoric acid to Fe in ferric nitrate is 3: 1.
(5) Heating the obtained powder to 300 ℃ at the speed of 10 ℃/min, calcining for 4h, and cooling to obtain FeF3@ N-C positive electrode material; wherein the N-C accounts for 5 percent of the mass ratio of the whole positive electrode material.
The obtained anode material is used as the anode material of the lithium ion battery for electrochemical performance test, and the pole piece ratio is that the anode material: acetylene black: PVDF (mass ratio) 90:5: 5. And preparing the CR2025 button cell by taking a lithium sheet as a reference electrode. Under the current density of 100mA/g, the first cycle specific discharge capacity is 193mAh/g, and the capacity retention rate of 200 cycles of the cycle is 79%; the specific cyclic discharge capacity is 158mAh/g under the current density of 1000mA/g
Comparative example 3
(1) Mixing and dissolving ferric nitrate and melamine in deionized water to obtain a mixed solution A; the concentration of iron ions in the solution is 0.5 mol/L;
(2) keeping the mixed solution A at 80 ℃ and stirring until the mixed solution A is completely dried, and collecting and grinding the obtained powder;
(3) heating the obtained powder to 700 ℃ at the speed of 5 ℃/min, calcining for 4h, and cooling to room temperature along with the furnace to obtain a precursor;
(4) placing a small beaker filled with hydrofluoric acid in a closed reaction container, coating the obtained precursor with filter paper, placing the coated precursor at the bottom of the reaction container, carrying out heat treatment on the reactor at 120 ℃ for 10 hours, taking out a reaction product from the filter paper after the reaction is finished, washing and drying;
wherein the molar ratio of F in hydrofluoric acid to Fe in ferric nitrate is 3: 1.
(5) Heating the obtained powder to 300 ℃ at the speed of 10 ℃/min, calcining for 4h, and cooling to obtain FeF3And (3) a positive electrode material.
The obtained anode material is used as the anode material of the lithium ion battery for electrochemical performance test, and the pole piece ratio is that the anode material: acetylene black: PVDF (mass ratio) 90:5: 5. And preparing the CR2025 button cell by taking a lithium sheet as a reference electrode. Under the current density of 100mA/g, the first cycle specific discharge capacity is 153mAh/g, and the capacity retention rate of 200 cycles of the cycle is 43 percent; the specific cyclic discharge capacity is 103mAh/g under the current density of 1000mA/g
It can be known from the above embodiments and comparative examples that the Mxene/N-C composite ferric fluoride positive electrode material provided by the present invention has the advantages that the Mxene and N-C have the function of stabilizing the material structure in the electrode material and improving the electronic conductance of the material, thereby improving the specific capacity, rate capability and cycling stability of the material. The comparative example did not adopt the scheme of the present invention, and thus the effects of the present invention could not be obtained.
The applicant states that the present invention is illustrated in detail by the above examples, but the present invention is not limited to the above detailed methods, i.e. it is not meant that the present invention must rely on the above detailed methods for its implementation. It should be understood by those skilled in the art that any modification of the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.

Claims (10)

1. FeF3The composite positive electrode material is characterized by comprising FeF3Mxene and nitrogen doped carbon material.
2. FeF according to claim 13The composite cathode material is characterized in that the mass ratio of the Mxene is 0.01-20% based on 100% of the total mass of the composite cathode material;
preferably, the mass ratio of the nitrogen-doped carbon material is 0.01-10% based on 100% of the total mass of the composite cathode material.
3. FeF according to claim 1 or 23The preparation method of the base composite cathode material is characterized by comprising the following steps of:
(1) preparing a mixed solution containing an iron source, a regulating agent, a nitrogen source and Mxene;
(2) drying and calcining the mixed solution to obtain a precursor;
(3) wrapping the precursor with a spacer, placing a fluorine source in a first container, respectively placing the precursor wrapped with the spacer and the first container in a closed reactor, and heating to obtain FeF3A base composite positive electrode material;
wherein the regulator is used as a carbon source.
4. The method of claim 3, wherein the iron source of step (1) comprises any one of ferric nitrate, ferric chloride or ferrous oxalate or a combination of at least two thereof;
preferably, the regulating agent in the step (1) is selected from polyvinylidene fluoride and/or polyvinylpyrrolidone, preferably polyvinylidene fluoride;
preferably, the nitrogen source of step (1) comprises melamine;
preferably, the Mxene of step (1) comprises Ti3C2Tx。
5. The method according to claim 3 or 4, wherein the concentration of the metal ions in the mixed solution in the step (1) is 0.01mol/L-2 mol/L;
preferably, the metal ions in the mixed solution in the step (1) are iron ions;
preferably, the mixed solution of step (1) is prepared as follows: dissolving an iron source, a regulator and a nitrogen source in a solvent, and then adding a dispersion liquid of Mxene to obtain a mixed solution;
preferably, the concentration of the Mxene in the Mxene dispersion liquid is 0.1g/L-2 g/L;
preferably, the number of layers of Mxene in the dispersion of Mxene is less than 10.
6. The method according to any one of claims 3 to 5, wherein the drying in step (2) is performed by: stirring the mixed solution at a certain temperature until the mixed solution is dried;
preferably, the certain temperature is 60 ℃ to 130 ℃;
preferably, the calcining of step (2) is performed under an atmosphere of a protective gas, the protective gas comprising any one of nitrogen, helium or argon or a combination of at least two of nitrogen, helium or argon;
preferably, the temperature of the calcination in the step (2) is 350-900 ℃;
preferably, the temperature rise rate of the calcination in the step (2) is 1-30 ℃/min;
preferably, the calcination of the step (2) is carried out for 1h-10 h.
7. The method according to any one of claims 3 to 6, wherein the fluorine source in the step (3) is hydrofluoric acid,
or the fluorine source is a mixture of lithium fluoride and/or sodium fluoride and hydrochloric acid;
preferably, the mass fraction of the hydrofluoric acid is 40% -50%;
preferably, the molar ratio of the lithium fluoride and/or the sodium fluoride to the hydrochloric acid is 1 (0.5-1.5);
preferably, the molar ratio of F in the fluorine source to Fe in the iron source is (0.5-6): 1;
preferably, the temperature of the heating treatment in the step (3) is 95-130 ℃;
preferably, the time of the heat treatment in the step (3) is 6h-12 h.
8. The method according to any one of claims 3 to 7, further comprising a step of washing and drying the reaction product after the heat treatment of step (3);
preferably, the method further comprises subjecting the reaction product of step (3) to step (4) secondary calcination;
preferably, the secondary calcination is performed under an atmosphere of a protective gas including any one of nitrogen, helium, or argon, or a combination of at least two thereof;
preferably, the temperature of the secondary calcination in the step (4) is 250-450 ℃;
preferably, the temperature rise rate of the secondary calcination in the step (4) is 1-30 ℃/min;
preferably, the holding time of the secondary calcination in the step (4) is 1h-10 h.
9. Method according to any of claims 3-8, characterized in that the method comprises the steps of:
(1) mixing and dissolving an iron source, a regulator and a nitrogen source in a solvent to obtain a mixed solution A;
(2) adding the Mxene few-layer dispersion liquid with the concentration of 0.1-2 g/L into the mixed solution A to obtain a mixed solution B, wherein the concentration of metal ions in the mixed solution B is 0.01-2 mol/L;
(3) keeping the mixed solution B at 60-130 ℃ and stirring until the mixed solution B is completely dried, and collecting and grinding the obtained powder;
(4) heating the obtained powder to 350-900 ℃ at the speed of 1-30 ℃/min, carrying out heat preservation and calcination for 1-10 h, and cooling to room temperature along with the furnace to obtain a precursor;
(5) placing a small beaker filled with a fluorine source in a closed reaction container, wrapping the precursor with filter paper, placing the coated precursor at the bottom of the reaction container, heating the reactor at 95-130 ℃ for 6-12 h, taking out a reaction product from the filter paper after the reaction is finished, washing and drying;
(6) heating the dried powder to 250-450 ℃ at the speed of 1-30 ℃/min, calcining for 1-10 h, and cooling to obtain FeF3@ Mxene/N-C cathode material; wherein, the Mxene accounts for 0.01-20% of the total mass of the anode material, and the N-C accounts for 0.01-10% of the total mass of the anode.
10. A lithium ion battery comprising the FeF according to claim 1 or 23A base composite positive electrode material.
CN202011597080.5A 2020-12-28 2020-12-28 FeF3Base composite positive electrode material, preparation method thereof and lithium ion battery Pending CN112701287A (en)

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