CN112002870A - Vanadium-doped carbon-coated lithium titanium phosphate composite material and preparation method and application thereof - Google Patents

Vanadium-doped carbon-coated lithium titanium phosphate composite material and preparation method and application thereof Download PDF

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CN112002870A
CN112002870A CN202010906504.5A CN202010906504A CN112002870A CN 112002870 A CN112002870 A CN 112002870A CN 202010906504 A CN202010906504 A CN 202010906504A CN 112002870 A CN112002870 A CN 112002870A
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lithium
vanadium
source
carbon
composite material
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吴志连
张旭锋
李忆非
王耀国
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Ningbo Fengcheng Advanced Energy Materials Research Institute Co Ltd
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Ningbo Fengcheng Advanced Energy Materials Research Institute Co Ltd
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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
    • H01M4/04—Processes of manufacture in general
    • H01M4/0402—Methods of deposition of the material
    • H01M4/0416—Methods of deposition of the material involving impregnation with a solution, dispersion, paste or dry powder
    • 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
    • H01M4/04—Processes of manufacture in general
    • H01M4/0471—Processes of manufacture in general involving thermal treatment, e.g. firing, sintering, backing particulate active material, thermal decomposition, pyrolysis
    • 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
    • H01M4/58—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
    • H01M4/624—Electric conductive fillers
    • H01M4/625—Carbon or graphite
    • 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
    • H01M2004/027—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
    • 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 application discloses a vanadium-doped carbon-coated lithium titanium phosphate composite material and a preparation method and application thereof, wherein the vanadium-doped carbon-coated lithium titanium phosphate composite material is selected from at least one of substances with a chemical general formula shown in formula I, and in the formula I, x is greater than 0 and less than or equal to 0.5. The lithium titanium phosphate anode material is prepared in batches by adopting a solid-phase sintering process, has a simple process and excellent product performance, and is suitable for large-scale production of the lithium titanium phosphate anode material.

Description

Vanadium-doped carbon-coated lithium titanium phosphate composite material and preparation method and application thereof
Technical Field
The application relates to a vanadium-doped carbon-coated titanium lithium phosphate composite material and a preparation method and application thereof, belonging to the field of lithium ion batteries.
Background
The aqueous lithium ion secondary battery adopts aqueous solution to replace organic electrolyte, has the advantages of high safety, low cost, environmental friendliness and the like, and compared with organic solution, the ionic conductivity of lithium ions in the aqueous solution is two orders of magnitude higher, so that the aqueous lithium ion secondary battery has higher power density. The above advantages make aqueous lithium ion secondary batteries popular in academia, and among them, lithium titanium phosphate negative electrode materials are gaining more and more attention in industry due to their advantages in cost and performance. However, the lithium intercalation potential is close to the hydrogen precipitation potential in the aqueous solution, so that side reaction is easy to occur, and the cycling stability of the battery is further reduced. Meanwhile, polyanionic lithium titanium phosphate has poor intrinsic conductivity, and the release of specific capacity of the polyanionic lithium titanium phosphate is limited. Therefore, the method has important significance for improving the lithium insertion potential of the titanium lithium phosphate, improving the electronic and ionic conductivity of the material, improving the specific capacity of the material and reducing the hydrogen evolution side reaction.
Disclosure of Invention
According to one aspect of the application, the vanadium-doped carbon-coated lithium titanium phosphate composite material is prepared in batch by adopting a solid-phase sintering process, is simple in process and excellent in product performance, and is suitable for large-scale production of lithium titanium phosphate cathode materials.
According to a first aspect of the present application, there is provided a vanadium-doped carbon-coated lithium titanium phosphate composite selected from at least one of the substances having the general chemical formula shown in formula I:
Li1.1Ti(2-x)Vx(PO4)3c formula I
In the formula I, x is more than 0 and less than or equal to 0.5.
Alternatively, in formula I, 0.01 ≦ x ≦ 0.10.
Optionally, the mass content of carbon in the vanadium-doped carbon-coated lithium titanium phosphate composite material is 8-16%.
Optionally, the upper limit of the mass content of carbon in the vanadium-doped carbon-coated lithium titanium phosphate composite material is independently selected from 16%, 14%, 11.8%, 9.8%, 9.3%, and the lower limit is independently selected from 8%, 14%, 11.8%, 9.8%, 9.3%.
According to a second aspect of the present application, there is also provided a method for preparing the vanadium-doped carbon-coated lithium titanium phosphate composite material, the method at least comprising:
(1) mixing materials containing a lithium source, a titanium source, a vanadium source, a phosphorus source and a carbon source with water, and reacting to obtain a precursor;
(2) and ball-milling and sintering the precursor to obtain the vanadium-doped carbon-coated lithium titanium phosphate composite material.
Optionally, the obtaining of the material containing the lithium source, the titanium source, the vanadium source, the phosphorus source and the carbon source at least comprises: after the lithium source, the titanium source, the vanadium source, the phosphorus source and the carbon source are weighed according to the proportion, the lithium source, the titanium source, the vanadium source, the phosphorus source and the carbon source are dissolved or dispersed in the organic solvent, the stirring, the dissolving and the dispersing time is 0.5-24 h, and the rotating speed is 200-600 r/min.
Optionally, the precursor is a jelly-like gel.
Optionally, in the step (1), the addition amounts of the lithium source, the titanium source, the vanadium source and the phosphorus source satisfy the molar ratio of each element in the formula I;
the molar ratio of the carbon source to the lithium source is 1: 1-5: 1.
alternatively, the upper limit of the molar ratio of the carbon source to the lithium source is independently selected from 5: 1. 4: 1. 3: 1. 2:1, the lower limit is independently selected from 1: 1. 4: 1. 3: 1. 2: 1.
optionally, the preparation method provided by the invention comprises the following steps: preparing a powder material by a sol-gel method by taking a lithium source, a titanium source, a vanadium source, a phosphorus source and a carbon source in a stoichiometric ratio as raw materials; ball-milling the obtained powder material to obtain vanadium-doped lithium titanium phosphate precursor mixed powder; and sintering the precursor mixed powder by adopting a solid-phase synthesis method to obtain the vanadium-doped lithium titanium phosphate cathode material.
Optionally, in the material, an organic solvent is also included;
preferably, the organic solvent is selected from alcohol compounds.
Preferably, the alcohol compound is at least one selected from methanol, ethanol, ethylene glycol, propanol, propylene glycol and butanol.
Optionally, the volume ratio of water to organic solvent is 1: 5-1: 45.
optionally, the upper limit of the volume ratio of water to organic solvent is independently selected from 1: 45. 1: 40. 1: 35. 1: 30. 1: 25. 1: 20. 1: 15. 1: 10, the lower limit is independently selected from 1: 40. 1: 35. 1: 30. 1: 25. 1: 20. 1: 15. 1: 10. 1: 5.
optionally, the reaction conditions are: the reaction temperature is 10-60 ℃; the reaction time is 5-15 min.
Alternatively, the reaction conditions have an upper temperature limit independently selected from 60 ℃, 50 ℃, 40 ℃, 30 ℃, 20 ℃ and a lower temperature limit independently selected from 10 ℃, 50 ℃, 40 ℃, 30 ℃, 20 ℃.
Optionally, the method comprises at least:
(1) mixing a suspension containing a lithium source, a titanium source, a vanadium source, a phosphorus source, a carbon source and an organic solvent with water, and reacting to obtain a precursor;
(2) and drying, ball-milling and sintering the precursor to obtain the vanadium-doped carbon-coated lithium titanium phosphate composite material.
Optionally, in the step (2), the sintering conditions are: the reaction is carried out in an inactive atmosphere, and the temperature is kept between 350 ℃ and 450 ℃ for 0.5h to 6 h; keeping the temperature of 450-650 ℃ for 0.5-6 h; keeping the temperature of 650-1000 ℃ for 2-10 h; the heating rate is 2-15 ℃/min;
the inert atmosphere is selected from at least one of nitrogen and inert gas.
Optionally, the upper limit of the temperature rise rate is independently selected from 15 ℃/min, 12 ℃/min, 9 ℃/min, 6 ℃/min, 3 ℃/min, and the lower limit is independently selected from 2 ℃/min, 12 ℃/min, 9 ℃/min, 6 ℃/min, 3 ℃/min.
Optionally, in the step (2), the ball milling time is 0.5-5 h; the rotation speed is 200 to 600 r/min.
Optionally, the upper limit of the ball milling time is independently selected from 5h, 4h, 3h, 2h, 1h, and the lower limit is independently selected from 0.5h, 4h, 3h, 2h, 1 h.
Optionally, before the ball milling step, drying the precursor; the drying conditions are as follows: the temperature is 80-120 ℃; the time is 6-24 h.
Preferably, the sintering kiln is a tube furnace.
Optionally, the lithium source is selected from at least one of lithium carbonate, lithium hydroxide, lithium nitrate, lithium oxalate, lithium dihydrogen phosphate;
the titanium source is at least one selected from metatitanic acid, tetrabutyl titanate and titanium isopropoxide;
the vanadium source is at least one of vanadium pentoxide, vanadium acetylacetonate, vanadyl acetylacetonate, ammonium metavanadate and triisopropoxyl vanadium oxide;
the phosphorus source is selected from at least one of ammonium dihydrogen phosphate, diammonium hydrogen phosphate, lithium dihydrogen phosphate, phosphoric acid and phytic acid;
the carbon source is at least one selected from glucose, sucrose, oxalic acid, citric acid, phytic acid, sucrose, tartaric acid, malic acid, ascorbic acid, poloxamer (F127), polyvinylpyrrolidone (PVP) and polyethylene glycol.
According to a third aspect of the present application, there is also provided a negative electrode material comprising any one of the vanadium-doped carbon-coated lithium titanium phosphate composite material and the vanadium-doped carbon-coated lithium titanium phosphate composite material prepared according to the above method.
According to a fourth aspect of the present application, there is also provided an aqueous lithium ion battery comprising: and the anode material of the anode is selected from at least one of the anode materials.
Optionally, the method further comprises: the battery comprises a positive electrode, a positive current collector, a diaphragm, a negative current collector and an aqueous electrolyte;
the anode material of the anode is selected from at least one of lithium manganate, lithium iron phosphate, lithium cobaltate, a nickel-manganese-cobalt ternary anode and a nickel-manganese-aluminum ternary anode;
the water system electrolyte contains at least one of lithium chlorate, lithium sulfate, lithium nitrate, lithium formate and lithium phosphate;
the positive electrode current collector and the negative electrode current collector are independently selected from at least one of a carbon-based material or a metal.
Optionally, the carbon-based material is selected from at least one of glassy carbon, graphite foil, graphite sheet, carbon cloth, carbon felt and carbon fiber;
the metal is at least one of Ni, Cu, Ag, Pb, Sn, Fe and Al.
Preferably, the metal is used after passivation.
Alternatively, the concentration of the aqueous electrolyte is 2.0M.
Optionally, the membrane is selected from glass fiber filter paper (porosity below 1 micron, thickness around 260 micron).
Optionally, the negative electrode manufacturing process: the method comprises the following steps of (1) mixing a negative electrode material, a conductive agent and a binder according to a mass ratio of 6-8: 1-3: 0.5-1.5, mixing and stirring the components in an ethanol solution to form slurry, coating the slurry on a stainless steel net, and then drying the stainless steel net in vacuum; the electrode area is about 1.5cm2The surface density of the negative electrode material is about 10-20 mg cm-2。
Optionally, the cathode manufacturing process includes: the method comprises the following steps of mixing a positive electrode material, a conductive agent and a binder according to a mass ratio of 7-9: 0.5-1.5: 0.5-1.5, mixing and stirring the mixture in an ethanol solution to form slurry, coating the slurry on a stainless steel net, and then drying the stainless steel net in vacuum, wherein the area of an electrode is about 1.5cm2The surface density of the active substance is about 10-20 mg cm-2。
Optionally, the battery used is a CR2032 coin cell battery.
The application provides an efficient and simple synthesis method, and the vanadium-doped carbon-coated titanium lithium phosphate composite material prepared by the method can be used as a negative electrode for a water-based lithium ion battery. The synthesized cathode material covers various vanadium-doped carbon-coated titanium lithium phosphate composite materials. The obtained cathode material and the positive lithium manganate are assembled into the aqueous lithium ion full battery, and the aqueous lithium ion full battery has good energy density and cycling stability.
The beneficial effects that this application can produce include:
1) through the synthesis by a sol-gel method and an inactive atmosphere sintering process, the obtained vanadium-doped lithium titanium phosphate material greatly improves the conductivity, improves the lithium intercalation potential of the negative electrode material, increases the potential difference between the lithium intercalation reaction and the hydrogen evolution reaction of the negative electrode, and reduces the hydrogen evolution side reaction of the negative electrode;
2) by providing an additional way for ion conduction, the vacancy caused by vanadium doping improves the kinetics of lithium ion conduction, and the structural change of the material in the lithium ion deintercalation process is effectively inhibited;
3) the obtained negative electrode material and the positive lithium manganate are assembled into a water-based lithium ion full battery, so that the water-based lithium ion full battery has good cycling stability;
4) the preparation process is simple, the operation is easy, the cost is low, and the cathode product has good stability and good industrialization prospect.
Drawings
FIG. 1 shows a vanadium-doped carbon-coated lithium titanium phosphate composite material Li in example 1 of the present application1.1Ti1.99V0.01(PO4)3XRD pattern of/C;
FIG. 2 shows a vanadium-doped carbon-coated lithium titanium phosphate composite material Li in example 1 of the present application1.1Ti1.99V0.01(PO4)3SEM picture of/C;
FIG. 3 shows a carbon-coated lithium titanium phosphate composite material Li in comparative example 1 of the present application1.1Ti2(PO4)3SEM picture of/C;
FIG. 4 shows a vanadium-doped carbon-coated lithium titanium phosphate composite material Li in example 1 of the present application1.1Ti1.99V0.01(PO4)3A charge-discharge curve of a water system full battery assembled by taking the/C as a negative electrode active material at room temperature;
FIG. 5 is a schematic view showing a carbon-coated lithium titanium phosphate composite material Li according to comparative example 1 of the present application1.1Ti2(PO4)3and/C is a charge-discharge curve at room temperature of an aqueous full cell assembled by using the negative electrode active material.
Detailed Description
The present application will be described in detail with reference to examples, but the present application is not limited to these examples.
The raw materials in the examples of the present application were all purchased commercially, unless otherwise specified.
The instruments and models used in the embodiment of the application are:
the instrument model of XRD is: d8 ADVANCE;
the instrument model of the SEM is: MONO CL 4;
the model of the battery tester is as follows: BTS-4008-5V20 mA-164.
Example 1
Step A: 13.6g of lithium carbonate, 248.8g of tetrabutyl titanate, 1.3g of vanadium acetylacetonate, 98.5g of phosphoric acid and 64.4g of citric acid; at room temperature, the raw materials are added into 500mL of ethanol, stirred, dissolved and dispersed for 0.5h at the rotating speed of 400 r/min.
And B: adding deionized water into the suspension, wherein the volume ratio of the deionized water to the ethanol is 1: and 15, stirring for reaction for 5min, and stopping stirring to enable the suspension to become a jelly gel.
And C: and (3) after the gel material is preliminarily air-dried, placing the gel material in a forced air drying oven for drying, wherein the temperature of the oven is set to be 105 ℃, and the time is 15 hours, so that the dried lithium titanium phosphate precursor material is obtained.
Step D: ball-milling the dried material to obtain a powder material; the ball milling time is 1h, and the rotating speed is 400 r/min.
Step E: sintering the material at high temperature in a tube furnace in argon atmosphere, wherein the sintering procedure is 350 ℃/2h, 550 ℃/2h, 800 ℃/8h, and the heating rate is 5 ℃/min, thus obtaining the vanadium-doped carbon-coated lithium titanium phosphate composite material Li1.1Ti1.99V0.01(PO4)3And C, the mass content of carbon in the composite material is 9.8 percent.
Example 2
Step A: 13.6g of lithium carbonate, 203.8g of titanium isopropoxide, 1.7g of vanadium pentoxide, 98.5g of phosphoric acid and 77.3g of citric acid; adding the raw materials into 500mL of mixed solvent of ethanol and butanol at the temperature of 30 ℃, stirring, dissolving and dispersing, wherein the volume ratio of the ethanol to the butanol is 1:1, the time is 0.5h, and the rotating speed is 400 r/min.
And B: adding deionized water into the suspension, wherein the volume ratio of the deionized water to the ethanol is 1: 30, reacting for 10min, then the suspension becomes jelly-like gel, and stopping stirring.
And C: and (3) after the gel material is preliminarily air-dried, placing the gel material in a forced air drying oven for drying, wherein the temperature of the oven is set to be 105 ℃, and the time is 15 hours, so that the dried lithium titanium phosphate precursor material is obtained.
Step D: ball-milling the dried material to obtain a powder material; the ball milling time is 3h, and the rotating speed is 600 r/min.
Step E: sintering the material at high temperature in a tube furnace in argon atmosphere, wherein the sintering procedure is 400 ℃/4h, 650 ℃/6h, 850 ℃/10h, and the heating rate is 2 ℃/min, thus obtaining the vanadium-doped carbon-coated lithium titanium phosphate composite material Li1.1Ti1.95V0.05(PO4)3And C, the mass content of carbon in the composite material is 11.8 percent.
Example 3
Step A: 13.6g of lithium carbonate, 237.5g of tetrabutyl titanate, 13.0g of vanadium acetylacetonate, 115.6g of ammonium dihydrogen phosphate and 41.1g of poloxamer; adding the raw materials into 500mL of ethanol at 60 ℃, stirring, dissolving and dispersing for 1h at the rotating speed of 500 r/min.
And B: adding deionized water into the suspension, wherein the volume ratio of the deionized water to the ethanol is 1: 40, reacting for 15min, then the suspension becomes jelly-like gel, and stopping stirring.
And C: and (3) after the gel material is preliminarily air-dried, placing the gel material in a forced air drying oven for drying, wherein the temperature of the oven is set to be 105 ℃, and the time is 15 hours, so that the dried lithium titanium phosphate precursor material is obtained.
Step D: ball-milling the dried material to obtain a powder material; the ball milling time is 5h, and the rotating speed is 300 r/min.
Step E: sintering the material at high temperature in a tubular furnace in argon atmosphere, wherein the sintering procedure is 375 ℃/2h, 600 ℃/4h, 800 ℃/10h, and the heating rate is 10 ℃/min, thus obtaining the vanadium-doped carbon-coated lithium titanium phosphate composite material Li1.1Ti1.9V0.1(PO4)3And C, the mass content of carbon in the composite material is 9.3 percent.
Comparative example 1
Step A: 13.6g of lithium carbonate, 250.0g of tetrabutyl titanate, 98.5g of phosphoric acid and 64.4g of citric acid; adding the raw materials into 500mL of ethanol at room temperature, stirring, dissolving and dispersing for 0.5h at the rotating speed of 400 r/min.
And B: adding deionized water into the suspension, wherein the volume ratio of the deionized water to the ethanol is 1: 15, stopping stirring after the suspension becomes a jelly-like gel.
And C: and (3) after the gel material is preliminarily air-dried, placing the gel material in a forced air drying oven for drying, wherein the temperature of the oven is set to be 105 ℃, and the time is 15 hours, so that the dried lithium titanium phosphate precursor material is obtained.
Step D: ball-milling the dried material to obtain a powder material; the ball milling time is 1h, and the rotating speed is 400 r/min.
Step E: sintering the material at high temperature in a tubular furnace in argon atmosphere, wherein the sintering procedure is 350 ℃/2h, 550 ℃/2h, 800 ℃/8h, and the heating rate is 5 ℃/min, so that the carbon-coated lithium titanium phosphate composite material Li can be obtained1.1Ti2(PO4)3/C。
Example 4 structural characterization of vanadium doped carbon coated lithium titanium phosphate composite
The samples of examples 1 to 3 were tested by an X-ray powder diffractometer (XRD), typically as in example 1, and the test results are shown in FIG. 1, where FIG. 1 corresponds to sample Li1.1Ti1.99V0.01(PO4)3and/C, it can be seen from FIG. 1 that the crystal structure of the lithium titanium phosphate is not significantly changed by vanadium doping.
The samples of examples 1 to 3 and comparative example 1 were tested by Scanning Electron Microscopy (SEM), and the results are shown in fig. 2 and 3, with example 1 and comparative example 1 being representative. FIG. 2 corresponds to sample Li1.1Ti1.99V0.01(PO4)3C, FIG. 3 corresponds to sample Li1.1Ti2(PO4)3and/C, as can be seen from the figures 2 and 3, the surface morphology of the carbon-coated lithium titanium phosphate is not significantly changed by vanadium doping.
Elemental tests were performed on the samples of examples 1 to 3 using an inductively coupled plasma emission spectrometer (ICP-OES) to give example 1 (Li)1.1Ti1.99V0.01(PO4)3/C) isTypically, the test results are shown in Table 1, corresponding to sample Li in Table 11.1Ti1.99V0.01(PO4)3and/C. From Table 1, it can be seen that Li1.1Ti1.99V0.01(PO4)3The mol ratio of Li, Ti, V and P in the/C is basically consistent with the theoretical value.
TABLE 1
Element(s) Li Ti V P
Molar ratio of 1.105 1.989 0.009 3.003
Example 5
Assembling the whole battery:
structural assembly
Electrolyte solution: 2M aqueous lithium sulfate solution
A diaphragm: glass fiber filter paper (porosity below 1 micron, thickness 260 micron)
Negative electrode active material: vanadium-doped carbon-coated lithium titanium phosphate composite Li obtained in example 11.1Ti1.99V0.01(PO4)3/C
Positive electrode active material: lithium manganate
The negative pole piece manufacturing process comprises the following steps: 70mg of active substance, 20mg of conductive carbon black (SP) and 10mg of Polytetrafluoroethylene (PTFE) are mixed and stirred in an ethanol solution according to the mass ratio of 7:2:1 to form slurry, and the slurry is coated on a stainless steel net and then dried in vacuum. The electrode area is about 1.5cm2The areal density of the active substance is approximately 18mg cm-2。
The manufacturing process of the positive pole piece comprises the following steps: 80mg of active substance, 10mg of conductive carbon black (SP) and 10mg of Polytetrafluoroethylene (PTFE) are mixed and stirred in an ethanol solution according to the mass ratio of 8:1:1 to form slurry, and the slurry is coated on a stainless steel net and then dried in vacuum. The electrode area is about 1.5cm2The areal density of the active substance is approximately 16mg cm-2。
The used battery is a CR2032 button battery.
Example 6
Assembling the whole battery:
structural assembly
Electrolyte solution: 2M aqueous lithium sulfate solution
A diaphragm: glass fiber filter paper (porosity below 1 micron, thickness 260 micron)
Negative electrode active material: vanadium-doped carbon-coated lithium titanium phosphate composite Li prepared in example 21.1Ti1.95V0.05(PO4)3/C
Positive electrode active material: lithium manganate
The negative pole piece manufacturing process comprises the following steps: 70mg of active substance, 20mg of conductive carbon black (SP) and 10mg of Polytetrafluoroethylene (PTFE) are mixed and stirred in an ethanol solution according to the mass ratio of 7:2:1 to form slurry, and the slurry is coated on a stainless steel net and then dried in vacuum. The electrode area is about 1.5cm2The areal density of the active substance is approximately 18mg cm-2。
The manufacturing process of the positive pole piece comprises the following steps: 80mg of active substance, 10mg of conductive carbon black (SP) and 10mg of Polytetrafluoroethylene (PTFE) are mixed and stirred in an ethanol solution according to the mass ratio of 8:1:1 to form slurry, and the slurry is coated on a stainless steel net and then dried in vacuum. The electrode area is about 1.5cm2Of active substancesThe areal density was about 16mg cm-2。
The used battery is a CR2032 button battery.
Example 7
Assembling the whole battery:
structural assembly
Electrolyte solution: 2M aqueous lithium sulfate solution
A diaphragm: glass fiber filter paper (porosity below 1 micron, thickness 260 micron)
Negative electrode active material: example 3 vanadium-doped carbon-coated lithium titanium phosphate composite Li1.1Ti1.9V0.1(PO4)3/C
Positive electrode active material: lithium manganate
The negative pole piece manufacturing process comprises the following steps: 70mg of active substance, 20mg of conductive carbon black (SP) and 10mg of Polytetrafluoroethylene (PTFE) are mixed and stirred in an ethanol solution according to the mass ratio of 7:2:1 to form slurry, and the slurry is coated on a stainless steel net and then dried in vacuum. The electrode area is about 1.5cm2The areal density of the active substance is approximately 18mg cm-2。
The manufacturing process of the positive pole piece comprises the following steps: 80mg of active substance, 10mg of conductive carbon black (SP) and 10mg of Polytetrafluoroethylene (PTFE) are mixed and stirred in an ethanol solution according to the mass ratio of 8:1:1 to form slurry, and the slurry is coated on a stainless steel net and then dried in vacuum. The electrode area is about 1.5cm2The areal density of the active substance is approximately 16mg cm-2。
The used battery is a CR2032 button battery.
Example 8
Assembling the whole battery:
structural assembly
Electrolyte solution: 2M aqueous lithium sulfate solution
A diaphragm: glass fiber filter paper (porosity below 1 micron, thickness 260 micron)
Negative electrode active material: carbon-coated lithium titanium phosphate composite Li prepared in comparative example 11.1Ti2(PO4)3/C
Positive electrode active material: lithium manganate
The negative pole piece manufacturing process comprises the following steps: 70mg of active substance, 20mg of conductive carbon black (SP) and 10mg of Polytetrafluoroethylene (PTFE) are mixed and stirred in an ethanol solution according to the mass ratio of 7:2:1 to form slurry, and the slurry is coated on a stainless steel net and then dried in vacuum. The electrode area is about 1.5cm2The areal density of the active substance is approximately 18mg cm-2。
The manufacturing process of the positive pole piece comprises the following steps: 80mg of active substance, 10mg of conductive carbon black (SP) and 10mg of Polytetrafluoroethylene (PTFE) are mixed and stirred in an ethanol solution according to the mass ratio of 8:1:1 to form slurry, and the slurry is coated on a stainless steel net and then dried in vacuum. The electrode area is about 1.5cm2The areal density of the active substance is approximately 16mg cm-2。
The used battery is a CR2032 button battery.
Example 9 electrochemical characterization of full cells
The full cells provided in examples 5, 6, 7 and 8 were subjected to charge and discharge tests and cycle performance tests.
The electrochemical performance characterization contains specific capacity and cycling stability.
The charge and discharge test conditions include: the test temperature is room temperature, and the battery charging and discharging multiplying power is 1C.
The first-turn specific capacities of the negative electrode active materials in example 5, example 6, example 7, and example 8 are shown in table 2. From table 2, we can see that the specific capacity of the first ring of the carbon-coated lithium titanium phosphate composite material is not significantly changed by doping with a proper amount of vanadium.
TABLE 2
Sample (I) Specific capacity (mAh/g)
Li1.1Ti1.99V0.01(PO4)3/C 102
Li1.1Ti1.95V0.05(PO4)3/C 105
Li1.1Ti1.9V0.1(PO4)3/C 103
Li1.1Ti2(PO4)3/C 108
Vanadium-doped carbon-coated lithium titanium phosphate composite material Li in example 1 of the present application1.1Ti1.99V0.01(PO4)3After the/C was assembled into a water-based full cell as a negative active material, electrochemical properties of the water-based full cell at room temperature were respectively tested, and the test results are shown in fig. 4. FIG. 4 shows a vanadium-doped carbon-coated lithium titanium phosphate composite material Li in example 1 of the present application1.1Ti1.99V0.01(PO4)3Charge and discharge curves of the/C assembled water system full cell at room temperature.
Carbon-coated lithium titanium phosphate composite material Li in comparative example 1 of the present application1.1Ti2(PO4)3After the/C was assembled into a water-based full cell as a negative active material, electrochemical properties of the water-based full cell at room temperature were respectively tested, and the test results are shown in fig. 5. FIG. 5 is a schematic view showing a carbon-coated lithium titanium phosphate composite material Li according to comparative example 1 of the present application1.1Ti2(PO4)3Charge and discharge curves of the/C assembled water system full cell at room temperature.
The curve in FIG. 4 shows that Li, a vanadium-doped carbon-coated lithium titanium phosphate composite material1.1Ti1.99V0.01(PO4)3First time of/CThe charge-discharge specific capacity is 102 mAh/g. FIG. 4 shows Li as a vanadium-doped carbon-coated lithium titanium phosphate composite material1.1Ti1.99V0.01(PO4)3the/C has better cycle performance, and the capacity retention rate after 100 cycles reaches 94 percent. The carbon-coated lithium titanium phosphate composite material Li can be obtained from the curve in FIG. 51.1Ti2(PO4)3The low-temperature first charge-discharge specific capacity of the/C is 108 mAh/g. From FIG. 5, it can be seen that the carbon-coated lithium titanium phosphate composite material Li1.1Ti2(PO4)3The performance of the/C cycle is poor, and the capacity retention rate after 100 cycles is only 78%. The above results show that: compared with the undoped carbon-coated titanium phosphate lithium composite cathode material, the full battery assembled by taking the vanadium-doped carbon-coated titanium phosphate lithium composite cathode material as the cathode active material has basically equivalent specific capacity and more excellent cycle performance.
In summary, the present invention is only illustrated by the embodiments and not limited in any way, and although the present invention has been disclosed by the preferred embodiments and not limited in any way, those skilled in the art can make many variations and modifications without departing from the scope of the present invention.

Claims (10)

1. A vanadium-doped carbon-coated lithium titanium phosphate composite material is characterized in that the vanadium-doped carbon-coated lithium titanium phosphate composite material is selected from at least one of substances with a chemical general formula shown in formula I:
Li1.1Ti(2-x)Vx(PO4)3c formula I
In the formula I, x is more than 0 and less than or equal to 0.5.
2. The vanadium-doped carbon-coated lithium titanium phosphate composite material according to claim 1, wherein in formula I, x is 0.01. ltoreq. x.ltoreq.0.10.
3. The vanadium-doped carbon-coated lithium titanium phosphate composite material according to claim 1, wherein the mass content of carbon in the vanadium-doped carbon-coated lithium titanium phosphate composite material is 8 to 16%.
4. The method of preparing a vanadium-doped carbon-coated lithium titanium phosphate composite material according to any one of claims 1 to 3, wherein the method comprises at least:
(1) mixing materials containing a lithium source, a titanium source, a vanadium source, a phosphorus source and a carbon source with water, and reacting to obtain a precursor;
(2) and ball-milling and sintering the precursor to obtain the vanadium-doped carbon-coated lithium titanium phosphate composite material.
5. The preparation method according to claim 4, wherein in the step (1), the lithium source, the titanium source, the vanadium source and the phosphorus source are added in amounts which satisfy the molar ratio of each element in the formula I;
the molar ratio of the carbon source to the lithium source is 1: 1-5: 1.
6. the method according to claim 4, wherein an organic solvent is further included in the material;
preferably, the organic solvent is selected from alcohol compounds.
7. The method according to claim 6, wherein the volume ratio of the water to the organic solvent is 1: 5-1: 45, a first step of;
preferably, the reaction conditions are: the reaction temperature is 10-60 ℃; the reaction time is 5-15 min;
preferably, the method comprises at least:
(1) mixing a suspension containing a lithium source, a titanium source, a vanadium source, a phosphorus source, a carbon source and an organic solvent with water, and reacting to obtain a precursor;
(2) drying, ball-milling and sintering the precursor to obtain the vanadium-doped carbon-coated lithium titanium phosphate composite material;
preferably, in the step (2), the sintering conditions are: the reaction is carried out in an inactive atmosphere, and the temperature is kept between 350 ℃ and 450 ℃ for 0.5h to 6 h; keeping the temperature of 450-650 ℃ for 0.5-6 h; keeping the temperature of 650-1000 ℃ for 2-10 h; the heating rate is 2-15 ℃/min;
preferably, in the step (2), the ball milling time is 0.5-5 h; the rotating speed is 200-600 r/min;
preferably, the lithium source is selected from at least one of lithium carbonate, lithium hydroxide, lithium nitrate, lithium oxalate, lithium dihydrogen phosphate;
the titanium source is at least one selected from metatitanic acid, tetrabutyl titanate and titanium isopropoxide;
the vanadium source is at least one of vanadium pentoxide, vanadium acetylacetonate, vanadyl acetylacetonate, ammonium metavanadate and triisopropoxyl vanadium oxide;
the phosphorus source is selected from at least one of ammonium dihydrogen phosphate, diammonium hydrogen phosphate, lithium dihydrogen phosphate, phosphoric acid and phytic acid;
the carbon source is at least one selected from glucose, sucrose, oxalic acid, citric acid, phytic acid, sucrose, tartaric acid, malic acid, ascorbic acid, poloxamer, polyvinylpyrrolidone and polyethylene glycol.
8. An anode material, wherein the anode material is selected from any one of the vanadium-doped carbon-coated lithium titanium phosphate composite material according to any one of claims 1 to 3 and the vanadium-doped carbon-coated lithium titanium phosphate composite material prepared by the method according to any one of claims 4 to 7.
9. An aqueous lithium ion battery, comprising: a negative electrode, a negative electrode material of which is selected from at least one of the negative electrode materials described in claim 8.
10. The aqueous lithium ion battery of claim 9, further comprising: the battery comprises a positive electrode, a positive current collector, a diaphragm, a negative current collector and an aqueous electrolyte;
the anode material of the anode is selected from at least one of lithium manganate, lithium iron phosphate, lithium cobaltate, a nickel-manganese-cobalt ternary anode and a nickel-manganese-aluminum ternary anode;
the water system electrolyte contains at least one of lithium chlorate, lithium sulfate, lithium nitrate, lithium formate and lithium phosphate;
the positive electrode current collector and the negative electrode current collector are independently selected from at least one of carbon-based materials or metals;
preferably, the carbon-based material is selected from at least one of glassy carbon, graphite foil, graphite sheet, carbon cloth, carbon felt and carbon fiber;
the metal is selected from at least one of Ni, Cu, Ag, Pb, Sn, Fe and Al;
preferably, the metal is used after passivation.
CN202010906504.5A 2020-09-01 2020-09-01 Vanadium-doped carbon-coated lithium titanium phosphate composite material and preparation method and application thereof Pending CN112002870A (en)

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