CN112151782A - Preparation method of ultralong titanium dioxide nanotube @ carbon @ molybdenum sulfide composite electrode with high energy density and quick charging performance - Google Patents

Preparation method of ultralong titanium dioxide nanotube @ carbon @ molybdenum sulfide composite electrode with high energy density and quick charging performance Download PDF

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CN112151782A
CN112151782A CN202011022339.3A CN202011022339A CN112151782A CN 112151782 A CN112151782 A CN 112151782A CN 202011022339 A CN202011022339 A CN 202011022339A CN 112151782 A CN112151782 A CN 112151782A
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composite electrode
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CN112151782B (en
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葛明政
梁芳华
曹春艳
张海峰
张伟
张瑜
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Nantong University
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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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    • H01M4/362—Composites
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y40/00—Manufacture or treatment of nanostructures
    • 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
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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
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H01M4/1397—Processes of manufacture of electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy
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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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    • H01M4/36—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
    • H01M4/581—Chalcogenides or intercalation compounds thereof
    • H01M4/5815—Sulfides
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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
    • 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
    • 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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/628—Inhibitors, e.g. gassing inhibitors, corrosion inhibitors
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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 provides a preparation method of an ultralong titanium dioxide nanotube @ carbon @ molybdenum sulfide composite electrode with high energy density and quick charging performance, which comprises the steps of preparing an ultralong titanate nanotube, preparing a titanate nanotube externally wrapped with an organic layer, and preparing TiO2@C@MoS2Preparation of composite electrode and TiO2@C@MoS2And (4) testing the electrochemical performance of the composite electrode. Advantageous effects of the inventionThe fruit is as follows: with TiO2The nanotube skeleton is used as substrate to improve electron transfer efficiency and prevent two-dimensional MoS during charge and discharge2Agglomerating the nanosheets; by using in MoS2Nanosheet and TiO2Carbon layer is modified between nanotubes, in TiO2And C, MoS2And C form Ti-O-C and C-S chemical bonds simultaneously, so that the bonding force between the Ti-O-C and the C-S is increased, and MoS is avoided2The nanosheets are derived from TiO due to volume expansion2The substrate is peeled off.

Description

Preparation method of ultralong titanium dioxide nanotube @ carbon @ molybdenum sulfide composite electrode with high energy density and quick charging performance
Technical Field
The invention relates to the technical field of materials, in particular to a preparation method of an ultralong titanium dioxide nanotube @ carbon @ molybdenum sulfide composite electrode with high energy density and quick charging performance.
Background
With the rapid development of economy, the development in the fields of wearable electronic equipment, unmanned aerial vehicles, electric vehicles and the like is more rapid, and the demand on lithium ion batteries with high energy density and rapid charge and discharge capacity is greater and greater. Graphite is mainly used as a negative electrode material of the current commercial lithium ion battery, and although the cost of the graphite is low, the graphite has relatively low theoretical capacity (372mAh/g) and poor dynamic performance, and cannot meet the requirement of a high-capacity battery in the future. In recent years, transition metal oxides and sulfides have been widely studied as active materials for storing lithium due to their advantages of relatively high energy density, long cycle life, and the like.
Transition metal sulfide MoS2The sandwich structure is formed by two layers of S atoms and a single layer of Mo sandwiched between the S atoms, has a graphite-like lamellar structure, and is mutually combined by weak van der Waals force with large interlayer spacing (0.615nm), and MoS2Has high theoretical specific capacity (670mAh/g), abundant storage capacity in the earth crust and low price, and is widely researched as an ideal negative electrode material of the lithium ion battery. But MoS2The conductivity is poor, and the reaction rate of the material under high charge-discharge rate is limited; second, during charging and discharging, MoS2Easy agglomeration and reduced active sites; and MoS due to the large volume expansion (. apprxeq.103%)2Easily detachable from a support and a current collectorAnd the electrochemical performance is poor due to the falling off.
Therefore, many researchers have conducted extensive research to address MoS2Poor conductivity, easy agglomeration in the battery charging and discharging process, large volume change and the like: 1) and (4) surface modification. In MoS2The surface is coated with a carbon material or other material to inhibit its volume expansion. However, the carbon layer material has poor mechanical properties and is easily damaged in the process of volume expansion, thereby causing the stability of the electrode to be reduced; 2) and (4) designing a composite structure. Mixing MoS2Loaded in a structurally stable base material, such as carbon nanotubes, graphene, MXene or TiO2Nanotubes, etc. to construct composite structures to stabilize MoS2The volume of (c) is changed. However, MoS2Low binding force with the substrate material, MoS after volume expansion2Is easy to fall off from the substrate material, so that the electrochemical performance of the electrode is poor.
How to solve the above technical problems is the subject of the present invention.
Disclosure of Invention
The invention aims to provide a preparation method of an ultralong titanium dioxide nanotube @ carbon @ molybdenum sulfide composite electrode with high energy density and quick charging performance, the preparation method is simple and easy to operate, and ultralong TiO is subjected to simple self-assembly, hydrothermal method and carbonization method2In-situ sequential growth of carbon layer and MoS on nanotube surface2Nanosheets, carbon layer and TiO2Nanotube and MoS2Ti-O-C and C-S chemical bonds are formed between the nano sheets simultaneously, and like glue, the interface bonding force between the nano sheets is increased, and MoS in the charging and discharging process is prevented2From TiO by volume expansion2Dropping off the nanotube substrate; at the same time, the carbon layer can improve MoS2The conductivity of the nano-sheet increases the reaction rate of the electrode under high charge-discharge rate; in addition, the carbon layer can also serve as a buffer layer, and MoS can be well inhibited2Huge stress change caused by volume expansion of the nanosheets enables the nanosheets to be uniformly distributed on TiO2The nanotube surface. And ultralong TiO2The nanotube skeleton is used as a substrate to prevent two-dimensional MoS in the process of charging and discharging2Nano meterDue to the agglomeration of the sheets, the three-dimensional network structure provides a channel for rapid transmission of electrons, and simultaneously shortens the transmission path of lithium ions. Through the unique structural design, MoS in the charging and discharging process is solved2Nanosheet agglomeration and MoS avoidance2Nanosheet from TiO2The composite electrode not only shows higher energy density, but also has quick charge and discharge performance, can realize low-cost and large-scale industrial application, and the lithium ion battery has higher energy density (426Wh/kg), can drive a hygrothermograph to work for a long time, and is expected to be commercially applied.
The idea of the invention is as follows: the invention provides a preparation method of an ultralong titanium dioxide nanotube @ carbon @ molybdenum sulfide composite electrode with high energy density and quick charging performance, which comprises the following specific steps: firstly, preparing an ultra-long titanate nanotube by a stirring hydrothermal method; forming a uniform organic matter polymerization layer, which is usually dopamine, carbohydrate or resin organic matter, on the surface of the ultra-long titanate nanotube by self-assembly; adding a molybdenum source and a sulfur source precursor into a solution of an ultra-long titanate nanotube externally wrapped with an organic layer, stirring and mixing uniformly, and growing molybdenum disulfide on the surface of the solution by a hydrothermal method; then preparing a flexible self-supporting film by suction filtration or a spin-coating method; finally, the flexible self-supporting TiO can be prepared by a carbonization method2@C@MoS2A composite electrode material; or high-temperature carbonization to obtain TiO2@C@MoS2Adding conductive agent, adhesive and solvent into the composite material, grinding the mixture to prepare slurry, and preparing TiO by using a traditional scraper coating method2@C@MoS2And (3) a composite electrode.
The invention is realized by the following measures: a preparation method of an ultralong titanium dioxide nanotube @ carbon @ molybdenum sulfide composite electrode with high energy density and quick charging performance comprises the following specific contents: adding a molybdenum source precursor and a sulfur source precursor into an ultralong titanate nanotube solution externally coated with an organic matter layer, stirring and mixing uniformly, carrying out centrifugal cleaning after carrying out high-temperature pressurization for a period of time by a hydrothermal method, then carrying out suction filtration or spin coating, and finally carrying out high-temperature carbonization to obtain TiO2@C@MoS2A composite electrode; or by high-temperature carbonizationTo TiO2@C@MoS2Adding conductive agent, adhesive and solvent into the composite material, grinding the mixture to prepare slurry, and preparing TiO by using a traditional scraper coating method2@C@MoS2And (3) a composite electrode.
Further, the molybdenum source precursor is sodium molybdate or ammonium molybdate, the sulfur source precursor is thiourea or thioacetamide, the two substances are in different combinations, and the weight ratio of the molybdenum source precursor to the sulfur source precursor is as follows: 1:1-5.
Further, the stirring speed is 0-2500rpm, and the stirring time is 1-60 min.
Furthermore, the molybdenum source and the sulfur source precursor respectively account for 0-100 wt% of the total mass, the hydrothermal reaction temperature is 50-250 ℃, and the hydrothermal reaction time is 5-64 h. .
Further, the suction filtration speed is 0-1000m3/s/m2The suction filtration time is 1-24h, and the mass per unit area is 0.1-10mg/cm2。
Further, the speed of the spin coating is 100-10000rpm, the time is 1-20s, and the mass per unit area is 0.1-10mg/cm2。
Further, the carbonization temperature is 400-800 ℃, the temperature rise and decrease speed is 2-10 ℃/min, and the high-temperature carbonization time is 1-6 h.
Further, the conductive agent is acetylene black, conductive carbon black, graphene or carbon nano tube, the binder is polyvinylidene fluoride and sodium hydroxymethyl cellulose, the solvent is N-methyl pyrrolidone or deionized water, and TiO is2@C@MoS2The proportion of the nano composite material, the conductive agent and the binder is 8:1:1 or 9:0.5:0.5, the coating speed is 1-80m/min, the vacuum drying temperature is 80-150 ℃, and the time is 14-48 h.
Further, adding TiO2Dispersing P25 powder in NaOH solution, continuously stirring for a period of time, pouring into a hydrothermal reaction kettle, continuously stirring at high temperature, taking out after a period of time, and respectively centrifugally cleaning with nitric acid and deionized water until the pH value is 7-8;
further, the TiO2The weight ratio of the P25 powder to the NaOH solution is 1:10-100, and the stirring speed is 0-2500 rpm.
Furthermore, the capacity of the hydrothermal reaction kettle is 25-500ml, the temperature of the hydrothermal reaction is 100-.
Further, adding titanate nanotubes into a dopamine solution, continuously stirring for a period of time, taking out, and respectively centrifugally cleaning with deionized water and absolute ethyl alcohol; or adding titanate nanotubes into a sugar or resin organic solution, taking out after a period of hydrothermal reaction, respectively centrifugally cleaning with deionized water and absolute ethyl alcohol, and forming an organic polymer layer on the surface of the titanate nanotubes by self-assembly;
further, the concentration of the titanate nanotube solution is 1-10mg/ml, the concentration of the dopamine solution is 1-25mg/ml, the weight ratio of the titanate nanotube solution to the dopamine is 1:1-10, the reaction time is 10-36h, and the stirring speed is 0-2500 rpm.
Furthermore, the saccharide is one or a combination of more of glucose, sucrose, maltose or starch, the concentration of the saccharide and the resin organic matter solution is 1-20mg/ml, the weight ratio of the titanate nanotubes to the saccharide to the resin organic matter is 1:1-10:1-10, the hydrothermal reaction temperature is 50-200 ℃, and the hydrothermal reaction time is 5-36 h.
Further, the weight ratio of the absolute ethyl alcohol to the deionized water in the centrifugal cleaning is 1:1, and the use amounts are 0.5-10L respectively.
In order to better realize the aim of the invention, the invention also provides a preparation method of the ultralong titanium dioxide nanotube @ carbon @ molybdenum sulfide composite electrode with high energy density and quick charging performance, which specifically comprises the following steps:
(1) preparing an ultra-long titanate nanotube: adding TiO into the mixture2Dispersing P25 powder in NaOH solution, continuously stirring for a period of time, pouring into a hydrothermal reaction kettle, continuously stirring at high temperature, taking out after a period of time, and respectively centrifugally cleaning with nitric acid and deionized water until the pH value is 7-8;
(2) preparing titanate nanotubes externally wrapped with an organic layer: adding titanate nanotubes into a dopamine solution, continuously stirring for a period of time, taking out, and respectively centrifugally cleaning with deionized water and absolute ethyl alcohol; or adding titanate nano-tubes into a sugar or resin organic solution, taking out after a period of hydrothermal reaction, respectively centrifugally cleaning with deionized water and absolute ethyl alcohol, and forming an organic polymer layer on the surfaces of the titanate nano-tubes through self-assembly;
(3)TiO2@C@MoS2preparing a composite electrode: adding a molybdenum source and a sulfur source precursor into a titanate nanotube solution externally wrapped with an organic layer, stirring and mixing uniformly, carrying out high-temperature pressurization for a period of time by a hydrothermal method, and carrying out centrifugal cleaning. Then carrying out suction filtration or spin coating, and finally carrying out high-temperature carbonization to obtain TiO2@C@MoS2A composite electrode; or high-temperature carbonization to obtain TiO2@C@MoS2Adding conductive agent, adhesive and solvent into the composite material, grinding the mixture to prepare slurry, and preparing TiO by using a traditional scraper coating method2@C@MoS2A composite electrode;
(4)TiO2@C@MoS2and (3) testing the electrochemical performance of the composite electrode: the lithium ion battery is assembled, the cycle performance and the rate performance of the battery are tested, and the energy density of the battery is calculated. And performing cyclic voltammetry to obtain rapid charge and discharge performance.
Wherein, the TiO in the step (1)2The weight ratio of the P25 powder to the NaOH solution is 1:10-100, and the stirring speed is 0-2500 rpm.
Wherein the capacity of the hydrothermal reaction kettle in the step (1) is 25-500ml, the temperature of the hydrothermal reaction is 100-200 ℃, the time is 12-36h, the stirring speed is 0-2500rpm, the concentration of the nitric acid is 0.1-10M, the weight ratio of the nitric acid to the water is 1:1, and the dosage is 0.5-10L respectively.
Wherein the concentration of the titanate nanotube solution in the step (2) is 1-10mg/ml, the concentration of the dopamine solution is 1-25mg/ml, the weight ratio of the titanate nanotube solution to the dopamine is 1:1-10, the reaction time is 10-36h, and the stirring speed is 0-2500 rpm.
Wherein the saccharide in the step (2) is one or a combination of glucose, sucrose, maltose or starch, the concentration of the saccharide and the resin organic solution is 1-20mg/ml, the weight ratio of the titanate nanotubes to the saccharide to the resin organic solution is 1:1-10:1-10, the hydrothermal reaction temperature is 50-200 ℃, and the hydrothermal reaction time is 5-36 h.
Wherein the weight ratio of the absolute ethyl alcohol to the deionized water in the centrifugal cleaning in the step (2) is 1:1, and the dosage is 0.5-10L respectively.
Wherein the molybdenum source precursor in the step (3) is sodium molybdate or ammonium molybdate, the sulfur source precursor is thiourea or thioacetamide, the two substances are combined differently, and the weight ratio of the molybdenum source precursor to the sulfur source precursor is as follows: 1:1-5.
Wherein the stirring speed in the step (3) is 0-2500rpm, and the stirring time is 1-60 min.
Wherein the molybdenum source and the sulfur source precursor in the step (3) respectively account for 0-100 wt% of the total mass, the hydrothermal reaction temperature is 50-250 ℃, and the hydrothermal reaction time is 5-64 h.
Wherein the suction filtration speed in the step (3) is 0-1000m3/s/m2The suction filtration time is 1-24h, and the mass per unit area is 0.1-10mg/cm2。
Wherein the spin coating speed in the step (3) is 100-10000rpm, the time is 1-20s, and the mass per unit area is 0.1-10mg/cm2。
Wherein the carbonization temperature in the step (3) is 400-.
Wherein the conductive agent in the step (3) is acetylene black, conductive carbon black, graphene or carbon nano tube, the binder is polyvinylidene fluoride and sodium hydroxymethyl cellulose, the solvent is N-methyl pyrrolidone or deionized water, and TiO2@C@MoS2The proportion of the nano composite material, the conductive agent and the binder is 8:1:1 or 9:0.5:0.5, the coating speed is 1-80m/min, the vacuum drying temperature is 80-150 ℃, and the time is 14-48 h.
Wherein the test voltage range of the half cell in the step (4) is 0.01-3V, the charge and discharge current is 0.05-10A/g, the test voltage range of the full cell is 2.5-4.3V, the charge and discharge current is 0.1-5C, and the cycle number is 100-5000 circles. The sweep rate of cyclic voltammetry is 0.1-100mV/s, and the voltage range is 0.01-3V.
Compared with the prior art, the invention has the beneficial effects that:
(1) compared with the prior art, TiO2The nanotube has the advantages of gel and higher conductivity, can be used as a conductive agent and a binder, does not need to add the binder and the conductive agent to prepare slurry by using a traditional method, has simple and easy process, good controllability and is suitable for industrial production. At the same time, with ultra-long TiO2Nanotube framework as substrate for preventing MoS during charge and discharge2Due to the agglomeration and falling of the nanosheets, the three-dimensional network structure provides a channel for rapid electron transmission, and meanwhile, the transmission path of lithium ions is shortened.
(2) Except that the conventional doctor blade coating method is used to prepare TiO2@C@MoS2The composite electrode can also be prepared into a flexible self-supporting electrode film by adopting a suction filtration/spin coating method, a Cu foil current collector is not needed, and the energy density and the cycling stability are greatly improved.
(3) Carbon layer and TiO2Nanotube and MoS2Ti-O-C and C-S chemical bonds are formed between the nano sheets respectively, and like glue, the binding force between the nano sheets is increased, and MoS in the charging and discharging process is prevented2From TiO by volume expansion2The nanotube substrate is peeled off. At the same time, the carbon layer can improve MoS2The conductivity of the electrode is improved, and the reaction rate of the electrode under high charge-discharge rate is improved. In addition, the carbon layer can also serve as a buffer layer, and MoS can be well inhibited2The huge stress change caused by volume expansion is uniformly distributed on TiO2The nanotube surface.
(4) With TiO2The nanotube skeleton is used as a substrate, so that the electron transfer efficiency is improved, and the lithium ion transfer path is shortened. Through the unique structural design, MoS in the charging and discharging process is solved2Nanosheet agglomeration and MoS avoidance2Nanosheet from TiO2The composite electrode not only shows higher energy density, but also has quick charge and discharge performance.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention.
FIG. 1 is a schematic diagram (a) and an atomic structural diagram (b) of a preparation method of an ultralong titanium dioxide nanotube @ carbon @ molybdenum sulfide composite electrode with high energy density and quick charging performance;
FIG. 2 shows the ultralong TiO prepared in example 1 of the present invention2SEM (a) and TEM (b) images of nanotubes;
FIG. 3 shows core-shell TiO prepared in example 1 of the present invention2SEM (a) and TEM (b) images of @ C;
FIG. 4 shows TiO prepared in example 1 of the present invention2@C@MoS2SEM (a) and TEM (b) images of a composite electrode;
FIG. 5 shows a single TiO produced in example 1 of the present invention2@C@MoS2SEM (a) of the nanotube, a linear scanning EDX spectrogram (b) and an element content chart (c);
FIG. 6 shows TiO prepared in example 1 of the present invention2@C@MoS2Optical photographs of the thin film electrodes;
FIG. 7 shows TiO prepared in example 1 of the present invention2@C@MoS2Transmission electron microscopy (a, b), selective area diffraction (c), high resolution (d, e) and mapping (f) spectra of the composite electrode;
FIG. 8 shows TiO prepared in example 1 of the present invention2Nanotube, TiO2@ C and TiO2@C@MoS2XRD spectrogram of the composite electrode;
FIG. 9 shows TiO prepared in example 1 of the present invention2Nanotubes and TiO2@C@MoS2BET spectra of the composite electrode;
FIG. 10 is a MoS prepared according to example 1 of the present invention2Ultralong TiO2Nanotube, TiO2@ C and TiO2@C@MoS2CompoundingTGA profile of the electrode;
FIG. 11 shows an ultralong TiO prepared in example 1 of the present invention2Nanotube, TiO2@ C and TiO2@C@MoS2XPS spectra of composite electrodes;
FIG. 12 shows TiO prepared in example 1 of the present invention2@C@MoS2Narrow spectra of C1S (a), O1S (b), Mo 3d (C), and S2 p (d) for the composite electrode;
FIG. 13 shows TiO prepared in example 1 of the present invention2@C@MoS2A circulating volt-ampere scanning curve of the composite electrode at a scanning speed of 0.1 mV/s;
FIG. 14 shows TiO prepared in example 1 of the present invention2@C@MoS2A relation map (b) of cyclic voltammetry scanning curves (a), Log (peak current) and Log (scanning rate) of the composite electrode at different rates;
FIG. 15 shows an ultralong TiO according to example 1 of the present invention2Nanotube film and TiO2Hardness test spectrum of @ C film;
FIG. 16 shows TiO prepared in example 1 of the present invention2@C@MoS2SEM (a) and TEM (b-e) images of the composite electrode after 50 cycles;
FIG. 17 is a MoS prepared according to example 1 of the present invention2、TiO2@C、TiO2@MoS2、TiO2@C@MoS2Rate capability of the composite electrode half-cell (a), TiO2@MoS2And TiO2@C@MoS2Long cycling performance of the composite electrode (b).
FIG. 18 shows TiO prepared in example 1 of the present invention2@C@MoS2Rate capability (a) and long cycle capability (b) of a composite electrode full cell;
FIG. 19 shows core-shell TiO prepared in example 2 of the present invention2SEM (a) and TEM (b) images of @ C;
FIG. 20 shows TiO prepared in example 3 of the present invention2@C@MoS2SEM image of the composite electrode.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. Of course, the specific embodiments described herein are merely illustrative of the invention and are not intended to be limiting.
Example 1
0.2g of TiO2The powder of P25 was dispersed in 30mL of 10M NaOH solution, stirred continuously at 1000rpm for 30 minutes, then poured into a 50mL hydrothermal reaction kettle, stirred at 500rpm, kept at 130 ℃ for 24 hours, and after the reaction was completed, the resulting product was washed by centrifugation with 10L of deionized water until the pH was 8. Then soaked in 0.1M nitric acid solution (10L) for 24h and further washed with 10L deionized water by centrifugation until pH 7. Repeating the steps for many times until the pH value is 7, and obtaining the ultra-long titanate nanotube;
the obtained ultra-long titanate nanotubes were examined, and the results are shown in fig. 2, and fig. 2 is SEM and TEM images of the ultra-long titanate nanotubes prepared in example 1 of the present invention, the titanate nanotubes having a diameter of about 70-120nm and a length of 10-50 μm.
40mg of titanate nanotubes are added into 100mL of dopamine solution with the concentration of 2mg/mL, stirring is continued for 24 hours, and centrifugal washing is carried out for 3 times by using 1L of deionized water and 1L of absolute ethyl alcohol respectively.
Pouring 40mg of ultra-long titanate nano-tubes externally wrapped with a polydopamine layer into 40mL of deionized water for stirring; then adding 0.15g of glucose, stirring for 20-30min, continuously adding 0.15g of sodium molybdate and 0.3g of thiourea, stirring for 60min, pouring the mixed solution into a 50mL hydrothermal reaction kettle, and reacting for 24h at 220 ℃ in an oven. Then centrifuged three times with deionized water and absolute ethanol, respectively. Finally, adding 10g of ultra-long titanate nanotube externally wrapped with polydopamine layer into 2L of anhydrous ethanol, performing ultrasonic treatment at 20 ℃ for 10min, mixing uniformly, and performing suction filtration to obtain a flexible self-supporting membrane at the suction filtration speed of 200m3/s/m2The pumping filtration time is 30min, and the mass of the flexible self-supporting membrane is 8.5mg/cm2Finally obtaining TiO by carbonization2@C@MoS2The composite electrode is prepared in the atmosphere of argon, the carbonization temperature is 500 ℃, the temperature rise and reduction rate is 5 ℃/min, and the high-temperature carbonization time is 2 h.
By way of comparison, core-shell structures were likewise produced by hydrothermal methodsTiO2@MoS2The composite material does not need to add dopamine. Simultaneously, MoS is prepared by a hydrothermal method2The hydrothermal reaction temperature of the nano-sheets is 220 ℃, and the reaction time is 24 h. And carrying out high-temperature carbonization on the ultra-long titanate nanotube externally wrapped with the poly dopamine layer in an argon atmosphere to obtain TiO2@ C composite electrode, carbonization temperature 500 ℃, temperature rising and falling speed of 5 ℃/min, and high-temperature carbonization time of 2 h.
For the obtained core-shell structure TiO2The results of the detection of the @ C composite material are shown in FIG. 3, and FIG. 3 shows the core-shell TiO prepared in example 1 of the present invention2SEM and TEM images of @ C in TiO2Coating carbon layer on the surface of the nanotube, and then TiO2The surface of the nano tube becomes rough from smooth, and the thickness of the carbon layer is 2.5 nm.
Flexible self-supporting TiO prepared in example 12@C@MoS2And (3) analyzing by using the composite electrode:
wherein, FIG. 4 shows TiO prepared in example 1 of the present invention2@C@MoS2SEM topography of the composite electrode. Two-dimensional sheet MoS2TiO uniformly grown on the coated carbon layer2Nanotube surface, MoS2The thickness of the nanoplatelets is about 5 nm.
FIG. 5 shows a single TiO produced in example 1 of the present invention2@C@MoS2EDX spectra of the composite electrode. The atomic mass ratio of Mo and S elements is about 1:2, which proves that MoS is successfully synthesized2Nanosheets. Meanwhile, the content of Ti element is lower and is almost 0, which shows that TiO2The nanotubes are completely coated with the outer carbon layer and the MoS2And (4) covering the nano sheets.
FIG. 6 shows a flexible self-supporting TiO prepared according to example 1 of the invention2@C@MoS2Optical photographs of the composite electrode. As can be seen from FIG. 6, TiO can be produced by suction filtration2@C@MoS2A flexible self-supporting film.
FIG. 7 shows a flexible self-supporting TiO prepared in example 1 of the present invention2@C@MoS2TEM, HRTEM, SEAD and Mapping images of the composite electrode. From the TEM (picture a) and HRTEM (picture b) in FIG. 7, it can be seen that the few layers ((A))<6 layers) two-dimensionalMoS2The nanosheets uniformly grown on the ultralong TiO2Nanotube @ carbon. As can be seen from FIGS. 6 and e, the lattice fringes with a spacing of 0.27nm and 0.61nm correspond to MoS2The (100) and (002) crystal planes of (A), the lattice fringes of 0.62nm and 0.35nm correspond to those of TiO2The (001) and (101) crystal planes of (A) indicate TiO2The nanotube is mainly composed of anatase phase and TiO2(B) Phase composition, consistent with the electron diffraction pattern of the selected areas (fig. 7 c). In addition, as can be seen from the Mapping graph of fig. 7f, the Ti, O, C, Mo, S elements are uniformly dispersed in the composite material, indicating the carbon layer and the layered MoS2The nano-sheet is evenly wrapped on the TiO2The nanotube surface.
FIG. 8 shows TiO prepared in example 1 of the present invention2Nanotube and TiO coated with carbon layer2Nanotubes and flexible self-supporting TiO2@C@MoS2XRD pattern of the composite electrode. Calcining at 500 ℃ for 2h in nitrogen atmosphere, and then obtaining TiO2The nanotubes are composed mainly of anatase structure and TiO2(B) Two crystal structures are composed: diffraction peaks at 25.2 °, 37.7 °, 47.9 °, 53.8 ° and 62.5 ° correspond to the (101), (004), (200), (105) and (204) crystal planes of the anatase phase, and diffraction peaks at 15.6, 27.3 and 31.6 correspond to TiO2(B) The (100), (110) and (200) crystal planes of the phases. In TiO2Coating carbon layer on the surface of the nanotube, and then TiO2The characteristic peak intensity of the nanotubes decreased, indicating TiO2The nanotubes are completely covered by a carbon layer. Then, TiO is added in a core-shell structure2MoS grown on surface of nanotube @ carbon composite2After the nano-sheet, strong MoS appears at about 15 DEG2Characteristic peak of with TiO2(100) The characteristic peaks of the crystal planes overlap. Furthermore, the diffraction peaks at 32.7, 39.5, 58.3 and 70.1 correspond to MoS2The (100), (103), (110) and (108) crystal planes of (A). These results all confirm the successful synthesis of TiO2@C@MoS2And (3) a composite electrode.
FIG. 9 shows TiO prepared in example 1 of the present invention2Nanotubes and TiO2@C@MoS2BET spectra of the composite electrode. Compared with TiO2Nanotubes coated with carbon layer and MoS2After nanosheet, TiO2@C@MoS2Specific surface area of the composite electrode (84.8 m)2Per g) and pore size (0.288 cm)3The/g) is reduced, but a higher value is still kept, which is beneficial to the penetration of the electrolyte and accelerates the transfer of lithium ions and electrons.
FIG. 10 shows TiO prepared in example 1 of the present invention2Nanotube, MoS2Nanosheet and TiO coated with carbon layer outside2Nanotubes and TiO2@C@MoS2TGA profile of the composite electrode. When the temperature is raised to 700 deg.C, TiO2The structure of the nanotubes is very stable with hardly any weight loss. Pure MoS2The nano-sheet begins to be oxidized into MoO at about 380 DEG C3The structure tends to be stable around 540 ℃. 1.5 wt.% weight loss before 100 ℃ resulted from adsorption on TiO2@ C and TiO2@C@MoS2Evaporation of water on the composite. For TiO2@ C composite, the 26.7 wt% weight loss is primarily due to the loss of the surface carbon layer in the temperature interval of 380 deg.C to 550 deg.C. Thus, carbon and TiO2The weight ratio of the components is 27.1 percent to 72.9 percent. In view of TiO2@C@MoS2The product of the composite material after being oxidized at high temperature is TiO2And MoO3 (TiO2And MoO3Total content of 70%) from which the TiO in the composite material can be calculated2The content of (B) was 18.2%. Thus, TiO2@C@MoS2TiO in composite material2/C/MoS2The ratio of (A) to (B) is 18.2%/6.8%/75%.
FIG. 11 shows TiO prepared in example 1 of the present invention2Nanotube and TiO coated with carbon layer2Nanotubes and TiO2@C@MoS2XPS plot of composite electrode. For TiO2The characteristic peaks of the nanotubes, C1s, Ti 2p and O1, are located at 284.6, 458.9 and 532.4eV, respectively. When in TiO2After the carbon layer is coated on the surface of the nanotube, TiO is removed2The characteristic peak of N1s appears at 398.6eV, the intensity of the characteristic peak of C1s is obviously enhanced, and the intensity of the characteristic peak of Ti 2p is reduced due to the fact that polydopamine is carbonized and then TiO is added2A uniform carbon layer is formed on the nanotube surface. On the surface of the ringContinuous modification of MoS2After the nano-sheet is prepared, diffraction peaks of Mo 3d and S2 p appear at 230.1 eV and 162.3eV, characteristic peaks of Ti 2p disappear, and the strength of characteristic peaks of C1S is reduced, so that the ultralong titanium dioxide nanotube @ carbon @ molybdenum disulfide composite electrode is successfully prepared.
FIG. 12 shows TiO prepared in example 1 of the present invention2@C@MoS2High resolution XPS spectra of C1S (a), O1S (b), Mo 3d (C), and S2 p (d) for the composite electrode. As can be seen from FIGS. (c) and (d), Mo 3d3/2(232.1eV) and Mo 3d5/2(229.3eV), and S2S1/2(162.7eV) and S2S3/2The band gap widths between (161.8eV) were 7.2eV and 0.9eV, respectively, demonstrating that the valence states of Mo and S are +4 and-2, respectively. In the narrow spectra of C1S and S2S, characteristic peaks for the C-S bond appear at the 285.2eV and 163.5eV positions. And in the narrow spectrum of Mo 3d, a C-O-Mo bond appears at the 235.1eV position, demonstrating that at MoS2And C form a firm C-S chemical bond. Meanwhile, in the narrow O1 s spectrum, the diffraction peak at 530.9eV is derived from TiO2Stable Ti-O-C chemical bonds formed between the nanotubes and the carbon layer (fig. 12 b). By reaction on TiO2C and MoS2Stable Ti-O-C and C-S chemical bonds are formed between/C, greatly improving TiO2Nanotubes and MoS2The interface binding force between the nano sheets prevents MoS in the charging and discharging process2Larger volume expansion from TiO2The nanotube matrix is exfoliated.
FIG. 13 shows TiO prepared in example 1 of the present invention2@C@MoS2The cyclic voltammetry scan curve of the first 4 cycles of the composite electrode at a scan rate of 0.1 mV/s. When discharged for the first time, reduction peaks occurred at 1.05V and 0.49V, which resulted from the decomposition of the electrolyte to form an SEI layer. In subsequent charge-discharge cycles, lithium ions are intercalated into the MoS upon discharge2Internally, reduction peaks at 1.22V and 1.79V occurred, resulting in 2H-MoS2Conversion to 1T LixMoS2(1.79V), finally decomposed to Li2S and Mo (1.22V). In contrast, when charged, oxidation peaks occurred at 1.61 and 2.25V, resulting in LixMoS2Desulfurization to MoS2Finally Li2S is oxidized to Li+And S. Except for MoS2In addition to lithiation/delithiation, TiO is also generated at 1.58/1.72V during charging and discharging2Characteristic peak of (2). The cyclic voltammetry scan curves were substantially completely overlapped with no positional shift, indicating TiO2@C@MoS2The composite electrode has stable structure.
FIG. 14 shows TiO prepared in example 1 of the present invention2@C@MoS2Cyclic voltammetry scan curves of the composite electrode at different scan rates. The relationship between peak current density (i) and scan rate (v) is described by the power law, where i is avb(a and b are constants). Thus, the value of b can be calculated from log (i) to log (v). Thus, by calculation, TiO as shown in FIG. 14b2@C@MoS2The values of b at the oxidation peak and the reduction peak of the composite electrode are 0.78 and 0.93, respectively, which are close to 1, indicating that TiO2@C@MoS2The composite electrode has excellent rapid charge and discharge performance.
FIG. 15 shows example 1TiO of the present invention2Nanotube film and TiO2Hardness test spectra of @ C films. At the same indentation depth, TiO2The @ C film shows higher load pressure, which indicates that the structure is harder, and proves that the carbon layer effectively relieves MoS2The huge strain caused by volume expansion is uniformly distributed on TiO2Of (2) is provided.
FIG. 16 shows TiO in example 1 of the present invention2@C@MoS2SEM and TEM images of the composite electrode after 500 cycles of charging and discharging. As can be seen in FIG. 16a, TiO was present after 500 cycles of charge and discharge2@C@MoS2The surface of the composite electrode can still keep a better appearance. Meanwhile, it can be seen from the TEM image that TiO is due to the ultra-long length2The nano tube effectively improves MoS2And TiO2The interface binding force between the carbon layers and the middle carbon layer effectively relieves the MoS2Stress change caused by the volume expansion of the nanosheets is beneficial to forming a stable SEI film, and the MoS on the outermost layer2The nanoplatelets are surrounded by a thin SEI film, approximately 3.5 nm thick. And MoS2Not from TiO2The surface is peeled off and still kept in close contact, accelerating lithiumThe transfer of ions and electrons.
FIG. 17 shows MoS in example 1 of the present invention2、TiO2@C、TiO2@MoS2、TiO2@C@MoS2And (3) testing the electrochemical performance of the composite electrode half cell. From a comparison of the rate capability of FIG. 17a, it can be seen that pure MoS is due to structural failure by volume expansion2The electrode capacity decayed very rapidly, and after 50 charge-discharge cycles, the capacity dropped to substantially 0. Albeit TiO2Can relieve MoS to a certain extent2Is expanded in volume of (3) so that TiO is2@MoS2The rate capability of the electrode is superior to that of MoS2However, when the charge/discharge current was 5A/g, the capacity was substantially 0. By reaction on TiO2The carbon layer is introduced to the surface of the nanotube, so that the carbon layer has excellent mechanical property, the stress change caused by volume expansion can be effectively relieved, and the MoS can be effectively improved2And TiO2The interfacial bonding force therebetween contributes to the formation of a stable SEI film. Thus, TiO2@C@MoS2The composite electrode shows excellent rate performance and cycle performance, and when the charge and discharge current is 0.1,0.2,0.5, 1.0, 2.0 and 5.0A/g, the capacity reaches 1117,1066,937,792,609 and 379 mAh/g. After 1500 times of charge-discharge cycles, the capacity can still be kept above 90%, which reaches above 720mAh/g, and is 2 times of the capacity of the traditional graphite cathode (fig. 17 b).
FIG. 18 shows TiO in example 1 of the present invention2@C@MoS2The composite electrode is a negative electrode and LiCoO is used as a negative electrode2(LCO) is the anode, and the electrochemical performance test chart is obtained after the battery is assembled into a full cell, the test voltage is 2.5-4.3V, the charge-discharge current is 0.1-1C, and the long-cycle charge-discharge current is 1C. As can be seen from the graph, the full cell has better rate performance, and the capacity reaches 180,148,105 and 80mAh/g when the charging and discharging current is 0.1,0.2,0.5 and 1.0C. And after 100 charge and discharge cycles, the capacity can still be kept at 82 mAh/g. Through calculation, the energy density of the full battery reaches 426Wh/kg, and the full battery can drive the hygrothermograph to continuously work for two days.
FIG. 19 is a super-coated carbon layer prepared in example 2 of the present inventionLong TiO22SEM and TEM images of the nanotubes, the carbon layer thickness was about 9.8 nm.
FIG. 20 shows TiO prepared in example 3 of the present invention2@C@MoS2SEM image of composite electrode, TiO2MoS of nanotube surface2The number of nano sheets is less and is not uniform.
In conclusion, the test results show that the preparation method provided by the invention successfully prepares the ultralong titanium dioxide nanotube @ carbon @ molybdenum sulfide composite electrode with high energy density and quick charging performance, the process is simple and easy to operate, and the ultralong TiO is subjected to simple self-assembly, hydrothermal method and carbonization method2The carbon layer and the MoS are grown on the surface of the nanotube in situ2Nanosheets. Carbon layer and TiO2Nanotube and MoS2Ti-O-C and C-S chemical bonds are formed between the nano sheets respectively, so that the interface bonding force between the two is increased, and MoS in the charging and discharging process is prevented2From TiO by volume expansion2Dropping off the nanotube substrate; at the same time, the carbon layer can improve MoS2The conductivity of the electrode increases the reaction rate of the electrode under high charge-discharge rate; in addition, the carbon layer can also serve as a buffer layer, and MoS can be well inhibited2The huge stress change caused by volume expansion is uniformly distributed on TiO2The nanotube surface. And ultralong TiO2Nanotube framework as substrate for preventing MoS during charging and discharging2The nanometer sheets are agglomerated and fall off, and the three-dimensional network structure provides a channel for rapid transmission of electrons and shortens the transmission path of lithium ions. Through the unique structural design, MoS in the charging and discharging process is solved2Agglomeration of nanosheets and avoidance from TiO2The composite electrode not only shows higher energy density but also has quick charge and discharge performance due to the problems of falling off on the substrate and the like. The lithium ion battery has high energy density (426Wh/kg), can drive the hygrothermograph to work for a long time (2 days), and is expected to be commercially applied.
Example 2
(1) 0.5g of TiO2The P25 powder was dispersed in 80mL of 5M NaOH solution, stirred continuously at 800rpm for 40 minutes, and then poured into 1After completion of the reaction, the obtained product was washed with 10L of deionized water by centrifugation until pH 8. After soaking in 0.1M nitric acid solution (10L) for 24h, it was washed centrifugally with 12L deionized water until pH 7. Repeating the steps for multiple times until the pH value is 7, and obtaining the ultra-long titanate nanotube;
(2) by mixing 100mg TiO2Adding the nanotube into 40mL of 10mg/mL sucrose solution, then pouring into a 100mL hydrothermal reaction kettle, keeping the temperature at 150 ℃ for 20h, and after the reaction is finished, respectively centrifugally cleaning 3 times by using 2L deionized water and 2L absolute ethyl alcohol.
(3) 100mg of the ultralong titanate nano-tube externally wrapped with cane sugar is poured into 200mL of deionized water to be stirred. Then 0.5g of glucose is added and stirred for 20min, 0.3g of ammonium molybdate and 1.2g of thioacetamide are added and stirred for 30min, and then the mixed solution is poured into a 50mL hydrothermal reaction kettle and reacts for 36h at 200 ℃ in an oven. Then centrifuged three times with deionized water and absolute ethanol, respectively. Finally, 50g of the ultralong titanate nanotube externally wrapped with cane sugar is added into 2L of absolute ethyl alcohol, ultrasonic treatment is carried out for 30min at the temperature of 25 ℃, the mixture is uniformly mixed, and then the flexible self-supporting membrane is obtained through spin coating, wherein the spin coating speed is 1500rpm/min, the spin coating time is 20s, and the mass of the flexible self-supporting membrane is 20mg/cm2Finally obtaining TiO by carbonization2@C@MoS2The composite electrode is prepared in the atmosphere of argon, the carbonization temperature is 600 ℃, the temperature rise and fall speed is 3 ℃/min, and the high-temperature carbonization time is 1 h.
(4) The overlength TiO prepared by the invention in the embodiment 2 and coated with the carbon layer outside2The nanotubes were analyzed and the results are shown in FIG. 19, with a carbon layer thickness of about 9.8 nm.
Example 3
(1) 1.5g of TiO2The powder of P25 was dispersed in 40mL of 15M NaOH solution, stirred continuously at 900rpm for 20 minutes, then poured into a 500mL hydrothermal reaction kettle, stirred at 800rpm, kept at 160 ℃ for 28 hours, and after the reaction was completed, the resulting product was washed by 2L of deionized water by centrifugation until the pH was 8. Then after soaking in 0.8M nitric acid solution (8L) for 36h, it was washed centrifugally with 8L deionized water until pH-7. Repeating the steps for many times until the pH value is 7, and obtaining the ultra-long titanate nanotube;
(2) 30mg of titanate nanotube is added into 20mL of melamine formaldehyde resin solution with the concentration of 30mg/mL, then the solution is poured into a 50mL hydrothermal reaction kettle, the solution is kept at 180 ℃ for 36h, and after the reaction is finished, 6L of deionized water and 6L of absolute ethyl alcohol are respectively used for centrifugal cleaning for 3 times.
(3) 30mg of the ultra-long titanate nanotubes externally wrapped with the polyorgano resin were poured into 100mL of deionized water and stirred. Then 2.5g of glucose is added and stirred for 35min, 0.05g of ammonium molybdate and 0.1g of thioacetamide are added and stirred for 10min, and then the mixed solution is poured into a 50mL hydrothermal reaction kettle and reacts for 20h at 180 ℃ in an oven. Then centrifugal washing is carried out for three times by using deionized water and absolute ethyl alcohol respectively. Drying the mixture in a drying oven at 100 ℃ for 48h, and then carrying out high-temperature carbonization in a tubular furnace in the atmosphere of argon at the carbonization temperature of 700 ℃, at the heating and cooling rate of 4 ℃/min and at the high-temperature carbonization time of 4h to obtain TiO2@C@MoS2A nanocomposite. Then adding conductive carbon black and polyvinylidene fluoride in a weight ratio of 8:1: 1. Adding N-methyl pyrrolidone for grinding to prepare slurry. Then uniformly coated on a copper foil at a coating rate of 40 m/min. Finally, vacuum drying is carried out, the drying temperature is 120 ℃, the drying time is 24 hours, and the mass is 4.5mg/cm2。
(4) TiO prepared by working example 3 of the invention2@C@MoS2The nanocomposite was analyzed and the results are shown in FIG. 20, TiO2MoS of nanotube surface2The number of nano sheets is less and is not uniform.
The short names of letters in the invention are all fixed short names in the field, wherein part of the letters are explained as follows: SEM image: electronic scanning and image display; TEM image: scanning and developing an image by transmission electron; HRTEM image: high resolution transmission electron scanning image display; EDX chart: an energy spectrum; mapping graph: an element distribution map; SAED graph: a selected area electron diffraction pattern; XRD pattern: an X-ray diffraction pattern; BET spectrum: a specific surface area map; TGA spectrum: thermogravimetric analysis spectrogram; XPS spectrum: analyzing a spectrogram by X-ray photoelectron spectroscopy; SEI: a solid electrolyte interface film. TiO22Nanotube: a titanium dioxide nanotube; MoS2: molybdenum disulfide; TiO22@C@MoS2: an ultralong titanium dioxide nanotube @ carbon @ molybdenum sulfide composite electrode; TiO22@ C: titanium dioxide nanotubes @ carbon; TiO22@MoS2: titanium dioxide nanotubes @ molybdenum disulfide.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Claims (8)

1. A preparation method of an ultralong titanium dioxide nanotube @ carbon @ molybdenum sulfide composite electrode with high energy density and quick charging performance is characterized by comprising the following steps:
step one, preparation of an ultra-long titanate nanotube: adding TiO into the mixture2Dispersing P25 powder in NaOH solution, continuously stirring for a period of time, pouring into a hydrothermal reaction kettle, continuously stirring at high temperature, taking out after a period of time, and respectively centrifugally cleaning with nitric acid and deionized water until the pH value is 7-8;
step two, preparing titanate nanotubes externally wrapped by an organic layer: adding titanate nanotubes into a dopamine solution, continuously stirring for a period of time, taking out, and respectively centrifugally cleaning with deionized water and absolute ethyl alcohol; or adding titanate nanotubes into a sugar or resin organic solution, taking out after a period of hydrothermal reaction, respectively centrifugally cleaning with deionized water and absolute ethyl alcohol, and forming an organic polymer layer on the surface of the titanate nanotubes by self-assembly;
step three, TiO2@C@MoS2Preparing a composite electrode: adding a molybdenum source and a sulfur source precursor into a titanate nanotube solution externally wrapped with an organic layer, stirring and mixing uniformly, carrying out high-temperature pressurization for a period of time by a hydrothermal method, and carrying out centrifugal cleaning. Then carrying out suction filtration or spin coating, and finally carrying out high-temperature carbonization to obtain TiO2@C@MoS2A composite electrode; or high-temperature carbonization to obtain TiO2@C@MoS2CompoundingAdding conductive agent, adhesive and solvent, grinding to obtain slurry, and preparing TiO by conventional doctor blade coating method2@C@MoS2A composite electrode;
step four, TiO2@C@MoS2And (3) testing the electrochemical performance of the composite electrode: the lithium ion battery is assembled, the cycle performance and the rate performance of the battery are tested, the energy density of the battery is calculated, and the rapid charge and discharge performance is obtained by performing cyclic voltammetry testing.
2. The production method according to claim 1,
TiO in the first step2The weight ratio of the P25 powder to the NaOH solution is 1:10-100, and the stirring speed is 0-2500 rpm;
the capacity of the hydrothermal reaction kettle in the first step is 25-500ml, the temperature of the hydrothermal reaction is 100-.
3. The production method according to claim 1 or 2,
in the second step, the concentration of the titanate nanotube solution is 1-10mg/ml, the concentration of the dopamine solution is 1-25mg/ml, the weight ratio of the titanate nanotube solution to the dopamine is 1:1-10, the reaction time is 10-36h, and the stirring speed is 0-2500 rpm.
4. The production method according to any one of claims 1 to 3,
in the second step: the sugar substance is one or a combination of more of glucose, sucrose, maltose or starch, the concentration of the solution of the sugar substance and the solution of the resin organic matter are respectively 1-20mg/ml, the weight ratio of the titanate nanotube to the sugar substance to the resin organic matter is 1:1-10:1-10, the hydrothermal reaction temperature is 50-200 ℃, and the hydrothermal reaction time is 5-36 h;
in the second step: the weight ratio of the absolute ethyl alcohol to the deionized water is 1:1 during centrifugal cleaning, and the dosage is 0.5-10L respectively.
5. The production method according to any one of claims 1 to 4,
in the third step: the molybdenum source precursor is sodium molybdate or ammonium molybdate, the sulfur source precursor is thiourea or thioacetamide, and the weight ratio of the molybdenum source precursor to the sulfur source precursor is as follows: 1:1-5.
6. The production method according to any one of claims 1 to 5,
in the third step: stirring speed is 0-2500rpm, and stirring time is 1-60 min;
in the third step: the molybdenum source and the sulfur source precursor respectively account for 0-100 wt% of the total mass, the hydrothermal reaction temperature is 50-250 ℃, and the hydrothermal reaction time is 5-64 h;
in the third step, the suction filtration speed is 0-1000m3/s/m2The suction filtration time is 1-24h, and the mass per unit area is 0.1-10mg/cm2；
In the third step, the spin coating speed is 100-10000rpm/min, the time is 1-20s, and the mass per unit area is 0.1-10mg/cm2；
In the third step, the carbonization temperature is 400-800 ℃, the temperature rise and fall speed is 2-10 ℃/min, and the high-temperature carbonization time is 1-6 h.
7. The preparation method of any one of claims 1 to 6, wherein in the third step, the conductive agent is acetylene black, conductive carbon black, graphene or carbon nanotubes, the binder is polyvinylidene fluoride or sodium hydroxymethyl cellulose, the solvent is N-methylpyrrolidone or deionized water, the ratio of the TiO2@ C @ MoS2 nanocomposite to the conductive agent to the binder is 8:1:1 or 9:0.5:0.5, the coating rate is 1 to 80m/min, the vacuum drying temperature is 80 to 150 ℃, and the time is 14 to 48 hours.
8. The method as set forth in any one of claims 1 to 7, wherein in the fourth step, the test voltage of the half cell is in the range of 0.01 to 3V, the charge and discharge current is in the range of 0.05 to 10A/g, the test voltage of the full cell is in the range of 2.5 to 4.3V, the charge and discharge current is in the range of 0.1 to 5C, the number of cycles is 5000-.
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