Nanocarbon intercalated niobium pentoxide negative electrode material as well as preparation method and application thereof

Abstract

The invention relates to a nanocarbon intercalated niobium pentoxide negative electrode material as well as a preparation method and application thereof. The preparation method of the nanocarbon intercalated niobium pentoxide negative electrode material comprises the following steps: (1) dispersing layered H4Nb6O17 powder in deionized water, then adding an alkaline organic intercalator, and stirring for 3-7 days at the temperature of 50-70 DEG C to obtain organic monomer intercalated H4Nb6O17; and (2) dispersing the obtained organic monomer intercalated H4Nb6O17 in a solution containing a polymerization initiator, stirring for 3-7 days at the temperature of 20-30 DEG C, washing, centrifuging, drying and carrying out heat treatment to obtain the nanocarbon intercalated niobium pentoxide negative electrode material.

Description

Technical Field

[0001] The present invention belongs to the field of lithium-ion battery energy storage, and particularly relates to a niobium pentoxide negative electrode material intercalated with nano-carbon, a preparation method thereof, and an application thereof. Background Art

[0002] In recent years, lithium-ion batteries have gradually dominated the energy storage fields such as portable electronic devices and electric vehicles. However, currently commercial lithium-ion batteries are gradually difficult to meet the performance requirements of large-scale and high-power energy storage. Especially for the rapidly developing electric vehicle industry at the present stage, the fast charging technology for quickly restoring the charging state in a short time is crucial for the development of lithium-ion batteries.

[0003] Currently, traditional lithium-ion batteries usually use graphite or lithium titanate as negative electrode materials. However, at high current densities, the specific capacity and cycle life of these two negative electrode materials will rapidly decay. Therefore, finding a negative electrode material with excellent fast charge and discharge performance and durability is an important prerequisite for lithium-ion batteries to achieve fast charging technology.

[0004] Orthorhombic niobium pentoxide (T-Nb2O5) is a very promising fast-charging negative electrode material due to its unique intercalation pseudocapacitance effect. Even without special nanostructure design, it can achieve ultrafast storage of a large number of lithium ions in a short time. The lithium storage process is highly reversible and there is no significant volume change.

[0005] However, T-Nb2O5 also has the disadvantage of insufficient conductivity of transition metal oxides, which greatly limits its full play of electrochemical activity during lithium storage. A large amount of research work is dedicated to improving the conductivity of T-Nb2O5. The main modification methods include constructing an oxygen defect structure (changing the valence to increase conductivity), constructing a binary composite phase of transition metal oxides, and composite conductive matrix, etc. For micron-sized niobium pentoxide particles with high tap density, surface carbon layer coating is a commonly used and effective measure. However, there is a lack of a highly conductive and uniform electron pathway inside the particles, resulting in the still hindered kinetics of its electrochemical reaction. Summary of the Invention

[0006] Aiming at the limitations of the prior art, the present invention aims to provide a niobium pentoxide negative electrode material intercalated with nano-carbon having fast charge and discharge performance, a preparation method thereof, and an application thereof.

[0007] In the first aspect, the present invention provides a preparation method of a niobium pentoxide negative electrode material intercalated with nano-carbon, including: (1) Dispersing layered H4Nb6O 17 powder in deionized water, then adding a basic organic intercalating agent, and first stirring at a temperature of 50 - 70 °C for 3 - 7 days (ensuring H +Perform sufficient ion exchange with an alkaline organic intercalating agent) to obtain H4Nb6O intercalated with organic monomers 17 ; (2) Disperse the obtained H4Nb6O intercalated with organic monomers 17 in a solution containing a polymerization initiator, stir at a temperature of 20 - 30 °C for 3 - 7 days first, and then obtain the niobium pentoxide negative electrode material intercalated with nano-carbon through washing, centrifugation, drying, and heat treatment. To obtain a continuous nano-carbon network, disperse the powder of H4Nb6O intercalated with organic monomers 17 in a solution containing a polymerization initiator, stir vigorously for 3 - 7 days to ensure complete polymerization of the organic monomers, and then obtain niobium pentoxide intercalated with nano-carbon after washing, centrifugation, drying, and heat treatment.

[0008] Preferably, in step (1), the preparation process of the layered H4Nb6O 17 powder includes; 1) Mix and sinter an alkali metal carbonate M2CO3 and Nb2O5 to obtain a layered M4Nb6O 17 powder, where M is at least one of K, Rb, and Cs; 2) Uniformly disperse the obtained layered M4Nb6O 17 powder in hydrochloric acid and stir vigorously, then collect by centrifugation to obtain a product; 3) Repeat step 2) for the obtained product multiple times and replace the hydrochloric acid each time, and then obtain the layered H4Nb6O 17 powder after washing, centrifugation, and drying. Among them, replace the hydrochloric acid and repeat stirring and centrifugation multiple times to ensure sufficient ion exchange between M + and H + .

[0009] Preferably, the alkali metal carbonate is selected from at least one of potassium carbonate, rubidium carbonate, and cesium carbonate; the mixing method is ball milling, and the ball milling is preferably carried out at a rotational speed of 200 - 500 revolutions per minute for 24 - 36 hours.

[0010] In the preparation method of niobium pentoxide intercalated with nano-carbon provided by the present invention, introduce an M4Nb6O 17 intermediate and adopt an ion exchange method, based on Nb6O 17 4-The electrostatic interaction between polyanions and cationic intercalants effectively solves the problem that it is difficult to directly intercalate intercalants into orthorhombic niobium pentoxide due to strong covalent bonds between layers, and finally realizes the porous laminated particle morphology constructed by the insertion of nano-carbon layers into niobium pentoxide and the exfoliation and assembly of microscale lamellar layers. The porous laminated micro-particle morphology with nano-carbon layer insertion is not only beneficial to the rapid electrochemical reaction of the electrode, but also can avoid the problem of reduced tap density of the electrode and battery energy density caused by using conventional particle nano-sizing methods.

[0011] Preferably, the molar ratio of the alkali metal carbonate M2CO3 to Nb2O5 is (2 - 3):3.

[0012] Preferably, the sintering temperature is 800 - 1100 °C and the sintering time is 8 - 12 hours.

[0013] Preferably, the concentration of the hydrochloric acid is 1.0 - 3.0 mol / L; the stirring time is 12 - 24 hours, the centrifugation speed is 5000 - 8000 revolutions per minute; to ensure sufficient ion exchange, the number of times of repeating stirring and centrifugation with the replacement of hydrochloric acid is 3 - 5 times.

[0014] Preferably, in step (1), the basic organic intercalant is at least one of aniline, pyrrole, and other organic amine compounds; the ratio of the layered H4Nb6O 17 powder to the basic organic intercalant is 100 - 200 mg:200 - 300 μL.

[0015] Preferably, in step (1), when the intercalating organic monomer is at least one of aniline and pyrrole, the polymerization initiator is ammonium persulfate; the concentration of the solution containing the polymerization initiator is 0.1 - 1.0 mol / L; preferably, when the polymerization initiator is ammonium persulfate, the solution containing the polymerization initiator also contains hydrochloric acid, and the concentration of hydrochloric acid is 0.1 - 1.0 mol / L.

[0016] Preferably, in step (2), the atmosphere for heat treatment is a nitrogen atmosphere; the heat treatment temperature is 500 - 1100 °C; the heat treatment time is 2 - 5 hours.

[0017] In a second aspect, the present invention provides a nano-carbon intercalated niobium pentoxide negative electrode material prepared by the above preparation method.

[0018] Preferably, the nano-carbon intercalated niobium pentoxide negative electrode material is a porous laminated particle composed of multi-layer thin microscale sheets; wherein, the thickness of the thin microscale sheets is less than 20 nm.

[0019] Preferably, in the niobium pentoxide negative electrode material intercalated with nano-carbon, the mass percentage of the nano-carbon layer is 5-15 wt%; the nano-carbon layer has a nano-carbon network morphology and is an amorphous structure.

[0020] Thirdly, the present invention provides an application of a niobium pentoxide negative electrode material intercalated with nano-carbon in the preparation of a negative electrode material for a lithium-ion battery.

[0021] Fourthly, the present invention provides a lithium-ion battery, comprising: a niobium pentoxide negative electrode material intercalated with nano-carbon as a negative electrode active material.

[0022] Advantages of the present invention: (1) The preparation method based on ion exchange provided by the present invention can achieve nano-carbon intercalation of niobium pentoxide. The introduced nano-carbon layer can serve as an internal conductive network to promote and homogenize electron transfer inside niobium pentoxide micro-particles; (2) The preparation method based on ion exchange provided by the present invention can also achieve peeling and self-assembly of niobium pentoxide micro-particle flakes, and the formed porous laminated morphology can effectively increase the contact area between the electrode active material and the electrolyte, enhance the lithium-ion diffusion rate on the electrode surface and increase the active sites of the electrochemical reaction, and improve the kinetic performance of the electrode reaction; (3) Combining the nano-carbon interlayer and the porous laminated morphology can significantly improve the electron and ion transport efficiency of the electrode, realize rapid and efficient charge and discharge of niobium pentoxide at an ultra-high current density, and provide a reliable negative electrode material for the fast charging technology of lithium-ion batteries; (4) The preparation method based on ion exchange provided by the present invention can achieve the introduction of an internal conductive network and the customization of a porous morphology for micron-sized large particles, and provide a promising development approach for laminated electrode materials with a high tap density. Description of the drawings

[0023] Figure 1 XRD diffraction pattern of PANI-NbO synthesized in Example 1 of the present invention; Figure 2 SEM images of P-NbO synthesized in Comparative Example 1 (a and b) and PANI-NbO synthesized in Example 1 (c and d) of the present invention; Figure 3 TEM image of PANI-NbO synthesized in Example 1 of the present invention; Figure 4 (a and b) Constant current charge and discharge curves and (c) rate performance of lithium batteries assembled with PANI-NbO synthesized in Example 1 of the present invention and P-NbO synthesized in Comparative Example 1 as electrode materials at different current densities; Figure 5The (a) galvanostatic charge-discharge curves and (b) long-term cycling performance of a lithium battery assembled with the PANI-NbO synthesized in Example 1 of the present invention and the P-NbO synthesized in Comparative Example 1 as electrode materials at a current density of 0.1 A / g. Figure 6 The comparative diagram of the long-term cycling performance of a lithium battery assembled with the PANI-NbO synthesized in Example 1 of the present invention and the P-NbO synthesized in Comparative Example 1 as electrode materials at a current density of 1 A / g. Detailed implementation manners

[0024] The present invention will be further described below through the following implementation manners. It should be understood that the following implementation manners are only used to illustrate the present invention, rather than limiting the present invention.

[0025] In the art, different from two-dimensional metal oxides such as TiO2, MnO2, and V2O5, the orthorhombic T-Nb2O5 is difficult to directly intercalate an intercalating agent due to the strong covalent bonds between layers. In the present disclosure, by introducing an intermediate of layered niobate M4Nb6O 17 (where M is K, Rb, or Cs), and based on an ion-exchange synthesis strategy, while introducing an organic carbon source interlayer between its layers, micron particle sheet exfoliation and assembly are induced, and then through a simple heat treatment method, niobium pentoxide intercalated with nano-carbon can be obtained, and it has a porous morphology assembled from sheet layers.

[0026] In the present invention, by introducing the H4Nb6O 17 intermediate and adopting an ion-exchange method, based on the electrostatic interaction between the Nb6O 17 4- poly-anion and the cationic intercalating agent, not only the insertion of the nano-carbon layer of T-Nb2O5 is finally realized, but also a porous morphology is constructed through the exfoliation and assembly of micron sheets during the ion-exchange process, effectively increasing the contact area between the electrode active material and the electrolyte, and further enhancing the reaction kinetics of the electrode. The preparation method of carbon nano-intercalated niobium pentoxide is exemplarily described below.

[0027] Mix an alkali metal carbonate M2CO3 (where M is K, Rb, or Cs) and Nb2O5 in a certain molar ratio (2:3), ball-mill at a rotation speed of 200 to 500 revolutions per minute for 24 to 36 hours, and then calcine in a muffle furnace at a temperature of 800 to 1100 °C for 8 to 12 hours to obtain a layered-structured M4Nb6O 17 powder. Among them, the alkali metal carbonate is selected from at least one of potassium carbonate, rubidium carbonate, and cesium carbonate.

[0028] Take 50 to 100 mg of M4Nb6O 17The powder was uniformly dispersed in hydrochloric acid with a concentration of 1.0 - 3.0 mol / L and stirred vigorously for 12 - 24 hours. After centrifugation, the powder was collected, the hydrochloric acid was replaced, and the process was repeated multiple times. Then, the product was washed and centrifuged with deionized water, and vacuum dried at 60 °C for 12 hours to obtain layered H4Nb6O 17 powder. To ensure full ion exchange between M + and H + , the number of times of repeating the stirring and centrifugation after replacing the hydrochloric acid is preferably 3 - 5 times.

[0029] Take 100 - 200 mg of H4Nb6O 17 powder and uniformly disperse it in deionized water. Slowly add 200 - 300 μL of a basic organic intercalating agent and stir at a temperature of 50 - 70 °C for 3 - 7 days to ensure full ion exchange between H + and the basic organic intercalating agent. Subsequently, the reacted powder was vacuum filtered and then vacuum dried at 60 °C for 12 hours to obtain H4Nb6O 17 intercalated with organic monomers. The basic organic intercalating agent is selected from at least one of aniline, pyrrole, and other organic amine compounds.

[0030] To obtain a continuous nano-carbon network, 50 - 100 mg of H4Nb6O 17 powder intercalated with organic monomers was dispersed in a solution containing a polymerization initiator and stirred vigorously for 3 - 7 days to ensure complete polymerization of the organic monomers. Subsequently, it was washed and centrifuged with deionized water multiple times and then vacuum dried at 60 °C for 12 hours to obtain H4Nb6O 17 powder intercalated with polymers. When the intercalated organic monomer is at least one of aniline and pyrrole, the polymerization initiator is preferably ammonium persulfate.

[0031] The dried H4Nb6O 17 powder intercalated with polymers was placed in a quartz crucible and transferred to a tube furnace for heat treatment. In a nitrogen atmosphere, it was heated to 600 °C at a heating rate of 3 °C per minute and held for 3 hours, and then naturally cooled to obtain niobium pentoxide intercalated with nano-carbon.

[0032] In the niobium pentoxide intercalated with nano-carbon prepared by the present invention, the niobium pentoxide is a porous laminated particle composed of thin-layered micron sheets, and the thickness of the thin-layered micron sheets is less than 20 nm. The mass percentage of the nano-carbon layer is 5 - 15%.

[0033] In the present disclosure, an application of niobium pentoxide intercalated with nano-carbon in the anode material of a lithium-ion battery is also provided. For example, the niobium pentoxide intercalated with nano-carbon prepared by the above preparation method is used as the anode active material, and is mixed with a binder (such as polyvinylidene fluoride PVDF, polytetrafluoroethylene PTFE, etc.) and a conductive agent (such as Super-P, acetylene black, etc.) according to a certain mass ratio (such as 7:2:1) to prepare the anode material of the lithium-ion battery with niobium pentoxide intercalated with nano-carbon.

[0034] In the preparation method of the nano-carbon intercalated niobium pentoxide provided by the present invention, M4Nb6O 17 intermediate is introduced and the ion exchange method is adopted. Based on the electrostatic interaction between polyanions and cationic intercalating agents, the problem that it is difficult to directly embed intercalating agents into orthorhombic niobium pentoxide due to strong covalent bonds between layers is effectively solved, and finally the nano-carbon layer insertion of niobium pentoxide and the exfoliation and self-assembly of micron-scale lamellae are realized to construct a porous laminated particle morphology. The porous laminated micron-particle morphology with nano-carbon layer insertion is not only beneficial to the rapid electrochemical reaction of the electrode, but also can avoid the problem of reducing the tap density of the electrode and the energy density of the battery caused by using conventional particle nanosizing methods. 17 4- The preparation method based on ion exchange provided by the present invention can realize the nano-carbon intercalation of niobium pentoxide. The introduced nano-carbon layer can serve as an internal conductive network to promote and homogenize the electron transfer inside the niobium pentoxide micron particles.

[0035] The preparation method based on ion exchange provided by the present invention can also realize the exfoliation and self-assembly of niobium pentoxide micron particle flakes. The formed porous laminated morphology can effectively increase the contact area between the electrode active material and the electrolyte, enhance the lithium ion diffusion rate on the electrode surface and increase the active sites of the electrochemical reaction, and improve the kinetic performance of the electrode reaction.

[0036] The niobium pentoxide intercalated with nano-carbon prepared by the present invention combines the nano-carbon interlayer and the porous laminated morphology, which can significantly improve the electron and ion transport efficiency of the electrode, realize the rapid and efficient charge and discharge of niobium pentoxide at an ultra-high current density, and provide a reliable anode material for the fast charging technology of lithium-ion batteries.

[0037] The preparation method based on ion exchange provided by the present invention can realize the introduction of an internal conductive network and the customization of a porous morphology for micron-scale large particles, providing a promising development route for laminated electrode materials with high tap density.

[0038] The preparation method based on ion exchange provided by the present invention can realize the introduction of an internal conductive network and the customization of a porous morphology for micron-scale large particles, providing a promising development route for laminated electrode materials with high tap density.

[0039] The following are further examples to illustrate the present invention in detail. It should also be understood that the following examples are only used to further illustrate the present invention and should not be construed as limiting the protection scope of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above content of the present invention fall within the protection scope of the present invention. The specific process parameters and the like in the following examples are also only an example within a suitable range, that is, those skilled in the art can make selections within a suitable range through the description herein, rather than being limited to the specific values in the following examples.

[0040] Example 1: Preparation of niobium pentoxide intercalated with nano-carbon: (1) Weigh 2.90 g of potassium carbonate and 7.97 g of niobium pentoxide. After mixing the two, ball-mill them at a speed of 230 revolutions per minute for 24 hours, and then place them in a muffle furnace and sinter at 1000 °C for 10 hours to obtain K4Nb6O 17 powder; (2) Weigh 50 mg of K4Nb6O 17 and disperse it evenly in 3.0 mol / L hydrochloric acid. After vigorously stirring for 24 hours, centrifuge to collect the precipitate at a speed of 6000 revolutions per minute. Repeat this process three times with hydrochloric acid of the same concentration. Wash the precipitate three times with deionized water and then place it in a vacuum oven and dry at 60 °C for 12 hours to obtain H4Nb6O 17 powder; (3) Weigh 200 mg of H4Nb6O 17 and disperse it evenly in 3.0 mL of deionized water. Then, take 300 μL of aniline (ANI) and drop it into the dispersion drop by drop. Stir vigorously at 60 °C for 7 days. Then, separate the product by vacuum filtration and dry at 60 °C for 12 hours to obtain aniline-intercalated H4Nb6O 17 ; (4) Weigh 100 mg of aniline-intercalated H4Nb6O 17 and disperse it evenly in a mixed solution of 1.0 mol / L ammonium persulfate and 0.1 mol / L hydrochloric acid. Stir vigorously at room temperature for 7 days. Wash the polymerized product three times with deionized water and then dry at 60 °C for 12 hours to obtain polyaniline (PANI)-intercalated H4Nb6O 17 ; (5) Under a nitrogen atmosphere, heat the PANI-intercalated H4Nb6O 17 to 600 °C at a heating rate of 3 °C per minute and hold for 3 hours. After natural cooling, nano-carbon-intercalated niobium pentoxide can be obtained, denoted as PANI-NbO.

[0041] Comparative Example 1: Preparation of niobium pentoxide: (1) Weigh 2.90 g of potassium carbonate and 7.97 g of niobium pentoxide. After mixing the two, ball-mill them at a speed of 230 revolutions per minute for 24 hours, and then place them in a muffle furnace and sinter at 1000 °C for 10 hours to obtain K4Nb6O 17 powder; (2) Weigh 50 mg of K4Nb6O 17 and disperse it evenly in 3.0 mol / L hydrochloric acid. After vigorously stirring for 24 hours, centrifuge to collect the precipitate at a speed of 6000 revolutions per minute. Repeat this process three times with hydrochloric acid of the same concentration. Wash the precipitate three times with deionized water and then place it in a vacuum oven and dry at 60 °C for 12 hours to obtain H4Nb6O 17 powder; (3) Under a nitrogen atmosphere, heat H4Nb6O 17 to 600 °C at a heating rate of 3 °C per minute and hold for 3 hours. After natural cooling, the original niobium pentoxide can be obtained, denoted as P-NbO.

[0042] The XRD pattern of PANI-NbO prepared in Example 1 of the present invention is as shown in the appendix Figure 1 . In the figure, the diffraction peaks of PANI-NbO belong to orthorhombic Nb2O5 (PDF#30-0873, space group is Pbam).

[0043] The SEM images of P-NbO prepared in Comparative Example 1 of the present invention are as shown in a and b in the appendix Figure 2 . It can be observed that the morphology of the original niobium pentoxide particles is a micron-scale sheet-like compact structure, stacked by Nb2O5 layers with a thickness exceeding 100 nm, and the overall size of the particles exceeds 5 μm. The SEM images of PANI-NbO prepared in Example 1 are as shown in c and d in the appendix Figure 2 . The particles exhibit a porous morphology assembled from micron-scale thin sheets. This is because during the preparation process, when aniline inserts into H4Nb6O 17 , the stacked structure is sliced and peeled off and self-assembled to form porous and interconnected secondary particles, which results from the peeling and self-assembly of micron-scale sheet layers during the ion exchange process.

[0044] The TEM image of PANI-NbO prepared in Example 1 of the present invention is as shown in the appendix Figure 3 . It can be observed that particles are stacked by three layers of Nb2O5 layers and carbon layers with different light and dark contrasts. The thickness of a single sheet layer is less than 20 nm, the nano-carbon layer presents an amorphous structure, and the mass percentage of the nano-carbon layer is 11 wt%.

[0045] Example 2: Preparation, battery assembly and testing of the niobium pentoxide negative electrode material: 1) Preparation of electrodes: PANI-NbO prepared in Example 1 and P-NbO prepared in Comparative Example 1 were respectively mixed with the conductive agent Super-P and the binder polyvinylidene fluoride (PVDF) in a mass ratio of 7:2:1, and uniformly mixed by grinding. An appropriate amount of N-methylpyrrolidone (NMP) was added dropwise to form a uniform slurry, which was then coated on a clean copper foil current collector. After natural drying, it was transferred to a vacuum oven at 60 °C and dried for 12 hours. The copper foil loaded with PANI-NbO or P-NbO after drying was punched into a round piece with a diameter of 10 mm, which was used as the niobium pentoxide electrode material; 2) Preparation of electrolyte: In an argon atmosphere glove box with a water content and an oxygen content both less than 0.1 ppm, 303.8 mg of lithium hexafluorophosphate (LiPF6) was weighed and added to a mixed solvent containing 1 mL of ethylene carbonate (EC) and 1 mL of diethyl carbonate (DEC) (the corresponding concentration of the solute was 1.0 mol / L). It was continuously stirred at room temperature for 24 hours to completely dissolve the white powder, and a carbonate-based electrolyte (LiPF6 / EC-DEC) was obtained; 3) Assembly of batteries: In an argon atmosphere glove box with a water content and an oxygen content both less than 0.1 ppm, CR2032 coin-type batteries were assembled for electrochemical performance testing. Among them, the above-prepared PANI-NbO or P-NbO electrode sheet and the lithium metal sheet were used as the working electrode and the counter electrode respectively, the electrolyte was the above-prepared electrolyte, and the separator was Glass fiber; 4) Charge and discharge testing of batteries: To test the electrochemical performance of PANI-NbO and P-NbO prepared in Example 1 and Comparative Example 1, the batteries assembled with PANI-NbO or P-NbO as the electrode material and LiPF6 / EC-DEC as the electrolyte were placed on a BlueTEC CT2001A for constant current charge and discharge testing. The current density was between 0.1 and 10 A / g, and the charge and discharge voltage range was 0.4 to 3.0 V. The obtained electrochemical performance is as shown in the appendix Figures 4 - 6 shown.

[0046] The rate performance of PANI-NbO and P-NbO at a current density of 0.1 to 10 A / g is as Figure 4As shown, the specific capacities of the PANI-NbO anode at current densities of 0.1, 0.2, 0.5, 1.0, 2.0, 5.0, and 10.0 A / g are 299.5, 251.9, 214.3, 188.6, 163.2, 136.2, and 108.4 mAh / g, respectively, which are much higher than those of the corresponding P-NbO electrode at the same current densities (148.0, 114.4, 89.3, 74.2, 64.3, 54.7, and 52.1 mAh / g, respectively). When the current density gradually returns to 0.1 A / g, the reversible capacity of PANI-NbO is still as high as 266.3 mAh / g, while the capacity of P-NbO is only 118.8 mAh / g. The long-term cycling performance of PANI-NbO and P-NbO at current densities of 0.1 A / g and 1 A / g is shown as Figure 5 and Figure 6 shown. At a current density of 0.1 A / g, the PANI-NbO electrode can still provide a reversible specific capacity of 175 mAh / g after 500 cycles, while the corresponding specific capacity of P-NbO is only 86 mAh / g. The voltage polarization between the charge-discharge curves of the PANI-NbO electrode is only 0.428 V, which is significantly smaller than the polarization value of the P-NbO electrode (0.614 V), indicating that the PANI-NbO electrode has better reaction kinetics. At a high current density of 1.0 A / g, the PANI-NbO electrode also shows a higher reversible specific capacity than the P-NbO electrode (the specific capacities after 2000 cycles are 155.1 mAh / g and 68.1 mAh / g, respectively). Even after 8000 ultra-long cycles, PANI-NbO can still provide a reversible specific capacity of approximately 138 mAh / g, with an average capacity decay rate as low as 0.043‰. The above electrochemical performance test results show that the built-in conductive carbon layer and porous morphology have significantly improved the reversible specific capacity, cycling stability, and high-current charge-discharge performance of the niobium pentoxide anode.

[0047] Finally, it is necessary to note here that the above embodiments are only used to further illustrate the technical solutions of the present invention and should not be construed as limiting the protection scope of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above content of the present invention fall within the protection scope of the present invention.

Claims

1. A preparation method of a niobium pentoxide negative electrode material intercalated with nano-carbon, characterized in that, Comprising: (1)Disperse the layered H4Nb6O 17 powder in deionized water, then add an alkaline organic intercalating agent, and stir at a temperature of 50-70 °C for 3-7 days to obtain H4Nb6O 17 intercalated with organic monomers; (2)Disperse the obtained organically monomer-intercalated H4Nb6O 17 in a solution containing a polymerization initiator, stir at a temperature of 20-30 °C for 3-7 days, then wash by centrifugation, dry, and perform heat treatment to obtain the niobium pentoxide negative electrode material intercalated with nano-carbon.

2. The preparation method according to claim 1, wherein In step (1), the preparation process of the layered H4Nb6O 17 powder includes; 1) After mixing and sintering an alkali metal carbonate M2CO3 and Nb2O5, a layered M4Nb6O 17 powder is obtained, where M is at least one of K, Rb, and Cs; 2) Disperse the obtained layered M4Nb6O 17 powder uniformly in hydrochloric acid, stir vigorously, and then collect by centrifugation to obtain the product; 3) Repeat step 2) for the obtained product multiple times and replace the hydrochloric acid each time, and then wash, centrifuge, and dry to obtain the layered H4Nb6O 17 powder.

3. The preparation method according to claim 2, wherein, The alkali metal carbonate is selected from at least one of potassium carbonate, rubidium carbonate and cesium carbonate; the molar ratio of the alkali metal carbonate M2CO3 to Nb2O5 is (2 - 3):

3. The sintering temperature is 800 - 1100 °C, and the sintering time is 8 - 12 hours.

4. The preparation method according to claim 2 or 3, characterized in that, The concentration of the hydrochloric acid is 1.0 - 3.0 mol / L; the stirring time is 12 - 24 hours, the centrifugation speed is 5000 - 8000 revolutions per minute; to ensure sufficient ion exchange, the number of times of replacing the hydrochloric acid for repeated stirring and centrifugation is 3 - 5 times.

5. The preparation method according to claim 1, characterized in that, In step (1), the basic organic intercalating agent is an organic amine compound, preferably at least one of aniline, pyrrole and other organic amine compounds; the ratio of the layered H4Nb6O 17 powder to the basic organic intercalating agent is 100-200 mg: 200-300 μL.

6. The preparation method according to any one of claims 1-5, characterized in that, In step (1), when the intercalated organic monomer is at least one of aniline and pyrrole, the polymerization initiator is ammonium persulfate; the concentration of the solution containing the polymerization initiator is 0.1 - 1.0 mol / L; preferably, when the polymerization initiator is ammonium persulfate, the solution containing the polymerization initiator further contains hydrochloric acid, and the concentration of the hydrochloric acid is 0.1 - 1.0 mol / L.

7. The preparation method according to any one of claims 1-6, characterized in that, In step (2), the atmosphere for the heat treatment is a nitrogen atmosphere; the heat treatment temperature is 500 - 1100 °C; the heat treatment time is 2 - 5 hours.

8. A niobium pentoxide negative electrode material intercalated with nano-carbon prepared by the preparation method according to any one of claims 1 - 7.

9. The niobium pentoxide negative electrode material intercalated with nano-carbon according to claim 8, characterized in that The niobium pentoxide negative electrode material intercalated with nano-carbon is a porous laminated particle composed of multi-layer thin-layer micro-sheets; wherein, the thickness of the thin-layer micro-sheets is less than 20 nm.

10. The niobium pentoxide intercalated with carbon nanotubes according to claim 8 or 9, characterized in that, In the niobium pentoxide negative electrode material intercalated with nano-carbon, the mass percentage of the nano-carbon layer is 5 - 15 wt%; the nano-carbon layer has a nano-carbon network morphology and is an amorphous structure.

11. Use of the niobium pentoxide negative electrode material intercalated with nano-carbon according to any one of claims 8 - 10 in the preparation of a negative electrode material for a lithium-ion battery.

12. A lithium-ion battery, characterized in that, Comprising: The niobium pentoxide negative electrode material intercalated with nano-carbon according to any one of claims 8 - 10 as a negative electrode active material.

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