CN112151782B - 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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CN112151782B
CN112151782B CN202011022339.3A CN202011022339A CN112151782B CN 112151782 B CN112151782 B CN 112151782B CN 202011022339 A CN202011022339 A CN 202011022339A CN 112151782 B CN112151782 B CN 112151782B
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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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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 TiO 2 @C@MoS 2 Preparation of composite electrode and TiO 2 @C@MoS 2 And (4) testing the electrochemical performance of the composite electrode. The invention has the beneficial effects that: with TiO 2 The nanotube skeleton is used as substrate to improve electron transfer efficiency and prevent two-dimensional MoS during charge and discharge 2 Agglomerating the nanosheets; by using in MoS 2 Nanosheet and TiO 2 Modifying carbon layer between nanotubes, in TiO 2 And C, MoS 2 And 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 avoided 2 The nanosheets are derived from TiO due to volume expansion 2 The 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 aircrafts, electric automobiles and the like is more and more rapid, and the demand on lithium ion batteries with high energy density and rapid charge and discharge capacity is more and more increased. At present, graphite is mainly used as a negative electrode material of a 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 MoS 2 The 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 MoS 2 Has 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 a lithium ion battery. But MoS 2 The conductivity is poor, and the reaction rate of the material under high charge-discharge rate is limited; second, during charging and discharging, MoS 2 Easy agglomeration and reduced active sites; and MoS due to the large volume expansion (. apprxeq.103%) 2 Easily fall off from the carrier and the current collector, resulting in poor electrochemical performance.
Therefore, many researchers have conducted extensive research to address MoS 2 Poor conductivity, easy agglomeration in the battery charging and discharging process, large volume change and the like: 1) and (4) surface modification. In MoS 2 The 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 MoS 2 Loaded in a structurally stable substrate material, such as carbon nanotubes, graphene, MXene or TiO 2 Nanotubes, etc. to construct composite structures to stabilize MoS 2 The volume of (c) is changed. However, MoS 2 Low binding force with the substrate material, MoS after volume expansion 2 Easily fall off from the substrate material, resulting in poor electrochemical performance of the electrode.
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 method 2 In-situ sequential growth of carbon layer and MoS on nanotube surface 2 Nanosheets, carbon layer and TiO 2 Nanotube and MoS 2 Ti-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 prevented 2 From TiO by volume expansion 2 Dropping off the nanotube substrate; at the same time, the carbon layer can improve MoS 2 The 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 inhibited 2 Huge stress change caused by volume expansion of the nanosheets enables the nanosheets to be uniformly distributed on TiO 2 The nanotube surface. And ultralong TiO 2 The nanotube skeleton is used as a substrate to prevent two-dimensional MoS in the process of charging and discharging 2 Due to the agglomeration of the nano sheets, the three-dimensional network structure provides a channel for rapid transmission of electrons, and the transmission path of lithium ions is shortened. Through the unique structural design, MoS in the charging and discharging process is solved 2 Nanosheet agglomeration and MoS avoidance 2 Nanosheet from TiO 2 The 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 molybdenum source and sulfur source precursor to the outsideUniformly stirring and mixing the solution of the ultra-long titanate nanotube wrapped by the organic layer, and growing molybdenum disulfide on the surface of the solution by a hydrothermal method; then preparing a flexible self-supporting membrane by suction filtration or spin-coating; finally, the flexible self-supporting TiO can be prepared by a carbonization method 2 @C@MoS 2 A composite electrode material; or high-temperature carbonization to obtain TiO 2 @C@MoS 2 Adding conductive agent, adhesive and solvent into the composite material, grinding the mixture to prepare slurry, and preparing TiO by using a traditional scraper coating method 2 @C@MoS 2 And (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 and a sulfur source precursor into an ultra-long titanate nanotube solution externally wrapped with an organic layer, stirring and mixing uniformly, carrying out centrifugal cleaning after carrying out high-temperature pressurization for a period of time by a hydrothermal method, carrying out suction filtration or spin coating, and finally carrying out high-temperature carbonization to obtain TiO 2 @C@MoS 2 A composite electrode; or high-temperature carbonization to obtain TiO 2 @C@MoS 2 Adding conductive agent, adhesive and solvent into the composite material, grinding the mixture to prepare slurry, and preparing TiO by using a traditional scraper coating method 2 @C@MoS 2 And (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 0-1000m 3 /s/m 2 The suction filtration time is 1-24h, and the mass per unit area is 0.1-10mg/cm 2 。
Further, the spin coating rate was 100-10000rpm, and the time was 1-20s, mass per unit area of 0.1-10mg/cm 2 。
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 tubes, the binder is polyvinylidene fluoride and sodium hydroxymethyl cellulose, the solvent is N-methyl pyrrolidone or deionized water, and TiO is added 2 @C@MoS 2 The 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 TiO 2 Dispersing 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 TiO 2 The 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 purpose 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 mixture 2 Dispersing 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 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;
(3)TiO 2 @C@MoS 2 preparing 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 TiO 2 @C@MoS 2 A composite electrode; or high-temperature carbonization to obtain TiO 2 @C@MoS 2 Adding conductive agent, adhesive and solvent into the composite material, grinding the mixture to prepare slurry, and preparing TiO by using a traditional scraper coating method 2 @C@MoS 2 A composite electrode;
(4)TiO 2 @C@MoS 2 and (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) 2 The 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 more 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 0-1000m 3 /s/m 2 The suction filtration time is 1-24h, and the mass per unit area is 0.1-10mg/cm 2 。
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/cm 2 。
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 TiO 2 @C@MoS 2 The 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, TiO 2 The 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 convenient process, easy operation and good controllability, and is suitable for industrial production. At the same time, with ultra-long TiO 2 Nanotube framework as substrate for preventing MoS during charging and discharging 2 Due 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 TiO 2 @C@MoS 2 The composite electrode can also adopt a suction filtration/spin coating methodThe flexible self-supporting electrode film can be prepared without using a Cu foil current collector, and the energy density and the cycling stability are greatly improved.
(3) Carbon layer and TiO 2 Nanotube and MoS 2 Ti-O-C and C-S chemical bonds are formed between the nano sheets respectively, and like glue, the bonding force between the nano sheets is increased, and MoS in the charging and discharging process is prevented 2 From TiO by volume expansion 2 The nanotube substrate is peeled off. At the same time, the carbon layer can improve MoS 2 The 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 inhibited 2 The huge stress change caused by volume expansion is uniformly distributed on TiO 2 The nanotube surface.
(4) With TiO 2 The 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 solved 2 Nanosheet agglomeration and MoS avoidance 2 Nanosheet from TiO 2 The 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 invention 2 SEM (a) and TEM (b) images of nanotubes;
FIG. 3 shows TiO with core-shell structure prepared in example 1 of the present invention 2 SEM (a) and TEM (b) images of @ C;
FIG. 4 shows TiO prepared in example 1 of the present invention 2 @C@MoS 2 SEM (a) and TEM (b) images of a composite electrode;
FIG. 5 shows an embodiment of the present invention1 preparation of a single TiO radical 2 @C@MoS 2 SEM (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 invention 2 @C@MoS 2 Optical photographs of the thin film electrodes;
FIG. 7 shows TiO prepared in example 1 of the present invention 2 @C@MoS 2 Transmission 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 invention 2 Nanotube, TiO 2 @ C and TiO 2 @C@MoS 2 XRD spectrogram of the composite electrode;
FIG. 9 shows TiO prepared in example 1 of the present invention 2 Nanotubes and TiO 2 @C@MoS 2 BET spectra of the composite electrode;
FIG. 10 is a MoS prepared according to example 1 of the present invention 2 Ultralong TiO 2 Nanotube, TiO 2 @ C and TiO 2 @C@MoS 2 TGA profile of the composite electrode;
FIG. 11 shows an ultralong TiO prepared in example 1 of the present invention 2 Nanotube, TiO 2 @ C and TiO 2 @C@MoS 2 XPS spectra of the composite electrode;
FIG. 12 shows TiO prepared in example 1 of the present invention 2 @C@MoS 2 Narrow 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 invention 2 @C@MoS 2 Cyclic voltammetry 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 invention 2 @C@MoS 2 A 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 invention 2 Nanotube film and TiO 2 Hardness test spectrum of @ C film;
FIG. 16 shows TiO prepared in example 1 of the present invention 2 @C@MoS 2 SEM (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 invention 2 、TiO 2 @C、TiO 2 @MoS 2 、TiO 2 @C@MoS 2 Rate capability of the composite electrode half-cell (a), TiO 2 @MoS 2 And TiO 2 @C@MoS 2 Long cycling performance of the composite electrode (b).
FIG. 18 shows TiO prepared in example 1 of the present invention 2 @C@MoS 2 Rate 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 invention 2 SEM (a) and TEM (b) images of @ C;
FIG. 20 shows TiO prepared in example 3 of the present invention 2 @C@MoS 2 SEM 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 TiO 2 The 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 absolute ethyl alcohol, 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 200m 3 /s/m 2 The pumping filtration time is 30min, and the mass of the flexible self-supporting membrane is 8.5mg/cm 2 Finally obtaining TiO by carbonization 2 @C@MoS 2 The 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 TiO was likewise prepared by hydrothermal methods 2 @MoS 2 The composite material does not need to be added with dopamine. Simultaneously, MoS is prepared by a hydrothermal method 2 The 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 TiO 2 @ 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 TiO 2 The 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 invention 2 SEM and TEM images of @ C in TiO 2 Coating carbon layer on the surface of the nanotube, and then TiO 2 The surface of the nanotube is changed from smooth to rough, and the thickness of the carbon layer is 2.5 nm.
Flexible self-supporting TiO prepared in example 1 2 @C@MoS 2 And (3) analyzing by using the composite electrode:
wherein, FIG. 4 shows TiO prepared in example 1 of the present invention 2 @C@MoS 2 SEM topography of the composite electrode. Two-dimensional sheet MoS 2 T uniformly grown on the coated carbon layeriO 2 Nanotube surface, MoS 2 The thickness of the nanoplatelets is about 5 nm.
FIG. 5 shows a single TiO produced in example 1 of the present invention 2 @C@MoS 2 EDX spectra of the composite electrode. The atomic mass ratio of Mo and S elements is about 1:2, which proves that MoS is successfully synthesized 2 Nanosheets. Meanwhile, the content of Ti element is lower and is almost 0, which shows that TiO 2 The nanotubes are completely coated with the outer carbon layer and the MoS 2 And (4) covering the nano sheets.
FIG. 6 shows a flexible self-supporting TiO prepared according to example 1 of the invention 2 @C@MoS 2 Optical photographs of the composite electrode. As can be seen from FIG. 6, TiO can be produced by suction filtration 2 @C@MoS 2 A flexible self-supporting film.
FIG. 7 shows a flexible self-supporting TiO prepared in example 1 of the present invention 2 @C@MoS 2 TEM, 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-dimensional MoS 2 The nanosheets uniformly grown on the ultralong TiO 2 Nanotube @ carbon. As can be seen from FIGS. 6 and e, the lattice fringes with a spacing of 0.27nm and 0.61nm correspond to MoS 2 The (100) and (002) crystal planes of (A), the lattice fringes of 0.62nm and 0.35nm correspond to those of TiO 2 The (001) and (101) crystal planes of (A) indicate TiO 2 The nanotube is mainly composed of anatase phase and TiO 2 (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 MoS 2 The nano-sheets are uniformly wrapped on the TiO 2 The nanotube surface.
FIG. 8 shows TiO prepared in example 1 of the present invention 2 Nanotube and TiO coated with carbon layer 2 Nanotubes and flexible self-supporting TiO 2 @C@MoS 2 XRD pattern of the composite electrode. Calcining at 500 ℃ for 2h in nitrogen atmosphere, and then obtaining TiO 2 The nanotubes are composed mainly of anatase structure and TiO 2 (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, anddiffraction peaks at 15.6, 27.3 and 31.6 correspond to TiO 2 (B) The (100), (110) and (200) crystal planes of the phases. In TiO 2 Coating carbon layer on the surface of the nanotube, and then TiO 2 The characteristic peak intensity of the nanotubes decreased, indicating TiO 2 The nanotubes are completely covered by a carbon layer. Then, TiO is added in a core-shell structure 2 MoS grown on surface of nanotube @ carbon composite 2 After the nano-sheet, strong MoS appears at about 15 DEG 2 Characteristic peak of with TiO 2 (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 MoS 2 The (100), (103), (110) and (108) crystal planes of (A). These results all confirm the successful synthesis of TiO 2 @C@MoS 2 And (3) a composite electrode.
FIG. 9 shows TiO prepared in example 1 of the present invention 2 Nanotubes and TiO 2 @C@MoS 2 BET spectra of the composite electrode. Compared with TiO 2 Nanotubes coated with carbon layer and MoS 2 After nanosheet, TiO 2 @C@MoS 2 Specific surface area of the composite electrode (84.8 m) 2 Per g) and pore size (0.288 cm) 3 Both/g) are reduced, but still maintain a higher value, which favors the penetration of the electrolyte, accelerating the transfer of lithium ions and electrons.
FIG. 10 shows TiO prepared in example 1 of the present invention 2 Nanotube, MoS 2 Nanosheet and TiO coated with carbon layer outside 2 Nanotubes and TiO 2 @C@MoS 2 TGA profile of the composite electrode. When the temperature is raised to 700 deg.C, TiO 2 The structure of the nanotubes is very stable with hardly any weight loss. Pure MoS 2 The nano-sheet begins to be oxidized into MoO at about 380 DEG C 3 The structure tends to be stable around 540 ℃. 1.5 wt.% weight loss before 100 ℃ resulted from adsorption on TiO 2 @ C and TiO 2 @C@MoS 2 Evaporation of water on the composite. For TiO 2 @ 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 TiO 2 The weight ratio of the components is 27.1 percent to 72.9 percent. In view of TiO 2 @C@MoS 2 Products of composite materials oxidized at high temperaturesThe substance is TiO 2 And MoO 3 (TiO 2 And MoO 3 Total content of 70%), from which the TiO in the composite can be calculated 2 The content of (B) was 18.2%. Thus, TiO 2 @C@MoS 2 TiO in composite material 2 /C/MoS 2 The ratio of (A) to (B) is 18.2%/6.8%/75%.
FIG. 11 shows TiO prepared in example 1 of the present invention 2 Nanotube and TiO coated with carbon layer 2 Nanotubes and TiO 2 @C@MoS 2 XPS plot of composite electrode. For TiO 2 The characteristic peaks of the nanotubes, C1s, Ti 2p and O1, are located at 284.6, 458.9 and 532.4eV, respectively. When in TiO 2 After the carbon layer is coated on the surface of the nanotube, TiO is removed 2 The 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 added 2 A uniform carbon layer is formed on the nanotube surface. Continuously modifying MoS on the surface 2 After 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 invention 2 @C@MoS 2 High 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 3d 3/2 (232.1eV) and Mo 3d 5/2 (229.3eV), and S2S 1/2 (162.7eV) and S2S 3/2 The band gap widths between (161.8eV) were 7.2eV and 0.9eV, respectively, demonstrating that the valence states of Mo and S were +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 MoS 2 And C form a firm C-S chemical bond. Meanwhile, in the narrow O1 s spectrum, the diffraction peak at 530.9eV is derived from TiO 2 Stable Ti-O-C bonds formed between the nanotubes and the carbon layer (fig. 12 b). By reaction on TiO 2 C and MoS 2 Form stable Ti-O-C and C-S reactions between/CChemical bond, greatly improves TiO 2 Nanotubes and MoS 2 The interface binding force between the nano sheets prevents MoS in the charging and discharging process 2 Larger volume expansion from TiO 2 The nanotube matrix is exfoliated.
FIG. 13 is a view of TiO prepared in example 1 of the present invention 2 @C@MoS 2 The 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 discharge 2 Internally, reduction peaks at 1.22V and 1.79V occurred, resulting in 2H-MoS 2 Conversion to 1T Li x MoS 2 (1.79V), finally decomposed to Li 2 S and Mo (1.22V). In contrast, when charged, oxidation peaks occurred at 1.61 and 2.25V, resulting in Li x MoS 2 Desulfurization to MoS 2 Finally Li 2 S is oxidized to Li + And S. In addition to MoS 2 In addition to lithiation/delithiation, TiO is also generated at 1.58/1.72V in the charging and discharging process 2 Characteristic peak of (2). The cyclic voltammetry scan curves were substantially completely overlapped with no positional shift, indicating TiO 2 @C@MoS 2 The composite electrode has stable structure.
FIG. 14 shows TiO prepared in example 1 of the present invention 2 @C@MoS 2 Cyclic 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 av b (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. 14b 2 @C@MoS 2 The 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 TiO 2 @C@MoS 2 The composite electrode has excellent rapid charge and discharge performance.
FIG. 15 shows example 1TiO of the present invention 2 Nanotube film and TiO 2 Hardness test spectra of @ C films. At the same indentation depth, TiO 2 The @ C film exhibits a greater load pressure, sayThe structure is harder, and the carbon layer is proved to effectively relieve MoS 2 The huge strain caused by volume expansion is uniformly distributed on TiO 2 Of (2) is provided.
FIG. 16 shows TiO in example 1 of the present invention 2 @C@MoS 2 SEM 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 discharge 2 @C@MoS 2 The 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 length 2 The nano tube effectively improves MoS 2 And TiO 2 Interface binding force between the carbon layers, and the middle carbon layer effectively relieves MoS 2 Stress change caused by the volume expansion of the nanosheets is beneficial to forming a stable SEI film, and the MoS on the outermost layer 2 The nanoplatelets are surrounded by a thin SEI film, approximately 3.5 nm thick. And MoS 2 Not from TiO 2 The surface is peeled off and still keeps close contact, and the transfer of lithium ions and electrons is accelerated.
FIG. 17 shows MoS in example 1 of the present invention 2 、TiO 2 @C、TiO 2 @MoS 2 、TiO 2 @C@MoS 2 And (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 expansion 2 The electrode capacity decayed very rapidly, and after 50 charge-discharge cycles, the capacity dropped to substantially 0. Albeit TiO 2 Can relieve MoS to a certain extent 2 Is expanded in volume of (3) so that TiO is 2 @MoS 2 The rate capability of the electrode is superior to that of MoS 2 However, when the charge/discharge current was 5A/g, the capacity was substantially 0. By reaction on TiO 2 The carbon layer is introduced to the surface of the nanotube, and the carbon layer has excellent mechanical property, so that the stress change caused by volume expansion can be effectively relieved, and the MoS can be effectively improved 2 And TiO 2 The interfacial bonding force therebetween contributes to the formation of a stable SEI film. Thus, TiO 2 @C@MoS 2 The 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. And areAfter 1500 times of charge-discharge cycles, the capacity can still be maintained 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 invention 2 @C@MoS 2 The composite electrode is a negative electrode and LiCoO is used as a negative electrode 2 (LCO) is the anode, and the electrochemical performance test chart is obtained after the battery is assembled into a full battery, 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 capability, 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 times of charge-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 shows the ultra-long TiO coated carbon layer prepared in example 2 of the present invention 2 SEM 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 invention 2 @C@MoS 2 SEM image of composite electrode, TiO 2 MoS of nanotube surface 2 The 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 charge performance, the process is simple and easy to operate, and the ultralong TiO is subjected to simple self-assembly, hydrothermal method and carbonization method 2 The carbon layer and the MoS are grown on the surface of the nanotube in situ 2 Nanosheets. Carbon layer and TiO 2 Nanotube and MoS 2 Ti-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 prevented 2 From TiO by volume expansion 2 Dropping off the nanotube substrate; at the same time, the carbon layer can improve MoS 2 The conductivity of the electrode is increased, and the reaction rate of the electrode under high charge-discharge rate is increased; in addition, the carbon layer can also serve as a buffer layer, and MoS can be well inhibited 2 The huge stress change caused by the volume expansion makes the materials all the sameIs uniformly distributed in TiO 2 The nanotube surface. And ultralong TiO 2 Nanotube framework as substrate for preventing MoS during charging and discharging 2 The 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 solved 2 Agglomeration of nanosheets and avoidance from TiO 2 The composite electrode not only shows higher energy density, but also has quick charge and discharge performance. 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 TiO 2 The powder of P25 was dispersed in 80mL of 5M NaOH solution, stirred continuously at 800rpm for 40 minutes, then poured into a 100mL hydrothermal reaction kettle, stirred at 500rpm, kept at 140 ℃ for 36 hours, and after the reaction was completed, the resulting product was washed by centrifugation with 10L of deionized water until the pH was 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 many times until the pH value is 7, and obtaining the ultra-long titanate nanotube;
(2) by mixing 100mg TiO 2 Adding the nanotube into 40mL of 10mg/mL sucrose solution, pouring into a 100mL hydrothermal reaction kettle, keeping the temperature at 150 ℃ for 20h, and after the reaction is finished, respectively centrifugally cleaning the nanotube by 2L of deionized water and 2L of absolute ethyl alcohol for 3 times.
(3) 100mg of the ultralong titanate nanotubes externally wrapped with sucrose are poured into 200mL of deionized water and 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, adding 50g of the ultralong titanate nanotube externally wrapped with cane sugar into 2L of absolute ethyl alcohol, carrying out ultrasonic treatment at 25 ℃ for 30min, uniformly mixing, and carrying out spin coating at the speed of 1500rpm/min for 1500rpm for 30min to obtain a flexible self-supporting film20s, the mass of the flexible self-supporting film is 20mg/cm 2 Finally obtaining TiO by carbonization 2 @C@MoS 2 The 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 outside 2 The 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 TiO 2 The 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 centrifugation with 2L of deionized water until the pH was 8. 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 an oven at 100 ℃ for 48h, and then carbonizing the mixture in a tube furnace at high temperature in the atmosphere of argon at 700 ℃, at a heating and cooling rate of 4 ℃/min for 4h to obtain TiO 2 @C@MoS 2 A 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 outDrying at 120 deg.C for 24 hr to obtain powder with a mass of 4.5mg/cm 2 。
(4) TiO prepared by working example 3 of the invention 2 @C@MoS 2 The nanocomposite was analyzed and the results are shown in FIG. 20, TiO 2 MoS of nanotube surface 2 The 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. TiO2 2 Nanotube: a titanium dioxide nanotube; MoS 2 : molybdenum disulfide; TiO2 2 @C@MoS 2 : an ultralong titanium dioxide nanotube @ carbon @ molybdenum sulfide composite electrode; TiO2 2 @ C: titanium dioxide nanotubes @ carbon; TiO2 2 @MoS 2 : 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 (1)

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 mixture 2 Dispersing 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;
the weight ratio of the TiO 2P 25 powder to the NaOH solution in the first step 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-;
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;
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;
in the second step: the saccharide is one or a combination of more of glucose, sucrose, maltose or starch, the concentration of the solution of the saccharide and the solution of the resin organic matters are 1-20mg/ml respectively, the weight ratio of the titanate nanotubes to the saccharide to the resin organic matters 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;
step three, TiO 2 @C@MoS 2 Preparing 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 TiO 2 @C@MoS 2 A composite electrode; or high-temperature carbonization to obtain TiO 2 @C@MoS 2 Compounding the material, adding conducting agent, adhesive and solventGrinding to prepare slurry, and preparing TiO by using the traditional scraper coating method 2 @C@MoS 2 A composite electrode;
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;
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 0-1000m 3 /s/m 2 The suction filtration time is 1-24h, and the mass per unit area is 0.1-10mg/cm 2 ；
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/cm 2 ；
In the third step, the carbonization temperature is 400-;
in the third step, the conductive agent is acetylene black, conductive carbon black, graphene or carbon nano tubes, the binder is polyvinylidene fluoride and sodium hydroxymethyl cellulose, the solvent is N-methyl pyrrolidone or deionized water, the ratio of the TiO2@ C @ MoS2 nano composite material to the conductive agent to the binder is 8:1:1 or 9:0.5:0.5, the coating rate is 1-80m/min, the vacuum drying temperature is 80-150 ℃, and the time is 14-48 h;
step four, TiO 2 @C@MoS 2 And (3) testing the electrochemical performance of the composite electrode: assembling the lithium ion battery into a lithium ion battery, testing the cycle performance and the rate performance of the battery, calculating the energy density of the battery, and performing cyclic voltammetry to obtain the rapid charge-discharge performance;
in the fourth step, the test voltage range of the half cell 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, the cycle time is 5000-loop, the scanning rate of the cyclic voltammetry test is 0.1-100mV/s, and the voltage range is 0.01-3V.
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