Nb2C-coated Zn composite material and preparation method and application thereof

Abstract

The invention discloses an Nb2C-Zn composite material as well as a preparation method and application thereof, and belongs to the technical field of aqueous zinc ion batteries. The preparation method of the Nb2C-coated Zn composite material comprises the following steps: dispersing Nb2C in water, uniformly mixing to obtain a Nb2C solution, performing ultrasonic treatment on the Nb2C solution in an inert gas atmosphere to strip the Nb2C, and obtaining supernate after the treatment is completed; and adding zinc powder into the supernate, adsorbing the Nb2C on the surface of the zinc powder, and filtering to obtain the Nb2C-coated Zn composite material. The Nb2C-Zn composite material prepared by the invention can solve the problem of hydrogen precipitation of a zinc negative electrode, and the aqueous zinc ion battery has excellent coulombic efficiency and cycling stability.

Description

Technical Field

[0001] The present invention relates to the technical field of aqueous zinc ion batteries, and more specifically to a Nb 2 C@Zn composite material and its preparation method and application. Background Art

[0002] Aqueous zinc-ion batteries (AZIBs) are an important energy storage technology with broad application prospects in renewable energy scale energy storage, building energy storage and other fields. However, the zinc metal negative electrode of AZIBs is accompanied by the occurrence of hydrogen evolution reaction (HER) during the stripping / deposition process, which not only reduces the output power and capacity of the battery, but also leads to a series of serious problems such as electrode corrosion, dendrites, and passivation. Therefore, inhibiting hydrogen evolution and gas production at the zinc negative electrode has become a hot topic in current research.

[0003] The hydrogen evolution reaction of zinc metal anode is one of the important factors restricting the performance and stability of aqueous zinc-ion batteries. In order to solve this problem, researchers have proposed a variety of strategies, including zinc anode regulation, solvation structure regulation and interface protection technology.

[0004] (1) Zinc negative electrode regulation: zinc negative electrode regulation is carried out through alloying strategies or composite materials. Adding some alloying elements or composite materials to the zinc negative electrode can change the electrochemical behavior and corrosion resistance of the zinc negative electrode, thereby inhibiting the occurrence of hydrogen evolution reaction. Zhou Jiang and others from Central South University used a smelting-rolling method to prepare a zinc-indium alloy negative electrode containing trace indium elements, or added a small amount of Ti, Cu and other elements to the zinc negative electrode to form a Zn-based alloy. The alloying strategy is used to preferentially distribute intermetallic compounds on the grain boundaries, which can effectively inhibit intergranular corrosion; at the same time, the mixed nucleation and growth mode caused by the reduction of Gibbs free energy helps to uniformly distribute Zn nuclei in space, promotes dense Zn deposition, and thus improves the efficiency and stability of the battery.

[0005] (2) Solvation structure regulation: In AZIBs, H 2 Hydrogen bonds can be formed between O molecules and other components (anions, cations and other additive molecules). 2 The influence of O molecule activity is closely related to various side reactions on the zinc negative electrode. 2 The hydrogen bonding network between O molecules can prevent the diffusion process and H + The reduction of ZnCl 2As an electrolyte to broaden the operating temperature window of AZIBs, the designed electrolyte is dominated by weak hydrogen bonding interactions, which reduces the H 2 O solidification point, so that ZnCl 2 The AZIBs full battery with electrolyte can work stably at low temperature. Professor Xia Yongyao of Fudan University and others studied the HER inhibition ability of dimethyl ether molecules and observed that the hydrogen evolution overpotential increased with the increase of dimethyl ether content. By optimizing the composition of the electrolyte and changing the interaction between the zinc negative electrode and the electrolyte, the occurrence of hydrogen evolution can be suppressed.

[0006] (3) Interface protection technology: The interface protection technology between the zinc negative electrode and the electrolyte will directly determine the stability of the zinc negative electrode. 2+ Move from the bulk electrolyte to the negative electrode surface, through the double electrical layer migration, the desolvated Zn 2+ Adsorbed on the zinc negative electrode, it obtains electrons and is reduced to metallic zinc. In addition, the active H 2 O molecules usually lead to side reactions such as HER. Constructing a water-poor EDL to inhibit side reactions on the surface of the zinc anode is a feasible method. Professor Huang Yunhui of Huazhong University of Science and Technology and others introduced glutamate anions into the traditional ZnSO 4 In the electrolyte, glutamate anions are preferentially adsorbed on the zinc anode, occupying the active sites for corrosion and HER, which largely inhibits the occurrence of hydrogen evolution reaction. Professor Guoxiu Wang and others from the University of Technology Sydney have found that glutamate anions are preferentially adsorbed on the zinc anode, occupying the active sites for corrosion and HER, and inhibiting the occurrence of hydrogen evolution reaction to a large extent. 4 The in-situ SEI was constructed by adding silk protein additives to the electrolyte. This protective film can inhibit side reactions and realize Zn 2+ Professor Zhang Jingping of Northeast Normal University and others added fluoroethylene carbonate (FEC) as an additive to ZnSO 4 In the electrolyte, a ZnF-rich layer was constructed on the surface of the zinc anode via an in situ chemical formation mechanism. 2 The inorganic / organic hybrid SEI layer reduces the current density and electrochemical reaction intensity on the electrode surface, thereby inhibiting the occurrence of hydrogen evolution side reaction.

[0007] Although these strategies reduce the polarization potential of reversible deposition of zinc ions to a certain extent and improve the stability of the battery, they cannot fundamentally solve the problem of hydrogen evolution and gas production at the zinc negative electrode, especially under high capacity, high current and long-term use conditions. These problems are more prominent, which is also one of the reasons restricting the commercialization of aqueous zinc-ion batteries. Summary of the invention

[0008] In view of the above problems, the present invention provides a Nb 2 C@Zn composite material and preparation method and application thereof, Nb prepared by the present invention2 C@Zn composite materials can solve the problem of hydrogen evolution at the zinc negative electrode, and aqueous zinc-ion batteries have excellent Coulombic efficiency and cycle stability.

[0009] The first object of the present invention is to provide a Nb 2 The preparation method of the C@Zn composite material comprises the following steps:

[0010] Nb 2 C is dispersed in water and mixed evenly to obtain Nb 2 C solution, under an inert gas atmosphere, Nb 2 C solution was treated with ultrasound to remove Nb 2 C was stripped and the supernatant was obtained after the treatment. It should be noted that in order to obtain the concentration of the supernatant, a known volume of the supernatant was filtered and the mass of the dried film was measured to calculate the stratified Nb 2 C is the concentration of the colloidal suspension.

[0011] Add zinc powder to the supernatant to make Nb 2 C is adsorbed on the surface of zinc powder and Nb is obtained after filtration. 2 C@Zn composites.

[0012] In one embodiment of the present invention, Nb in the supernatant is 2 The mass ratio of C to zinc powder is 1:9-16. For example, Nb 2 The mass ratio of C to zinc powder is 1:9, 1:9.5, 1:10, 1:10.5, 1:11, 1:11.5, 1:12, 1:12.5, 1:13, 1:13.5, 1:14, 1:14.5, 1:15, 1:15.5, 1:16, etc., but is not limited to the listed values, and other unlisted values ​​within the above numerical range are also applicable.

[0013] In one embodiment of the present invention, the adsorption time is 3s to 5s, for example, the adsorption time is 3s, 4s, 5s, etc., but is not limited to the listed values, and other unlisted values ​​within the above numerical range are also applicable.

[0014] In one embodiment of the present invention, the ultrasonic treatment time is 1h to 1.5h, for example, the ultrasonic treatment time is 1h, 70min, 80min, 1.5h, etc., but is not limited to the listed values, and other unlisted values ​​within the above numerical range are also applicable.

[0015] In one embodiment of the present invention, Nb 2 The concentration of C solution is 5mg / mL to 6mg / mL. For example, Nb 2The concentration of solution C is 5 mg / mL, 5.2 mg / mL, 5.4 mg / mL, 5.6 mg / mL, 5.8 mg / mL, 6 mg / mL, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0016] In one embodiment of the present invention, the speed of the centrifugal treatment is 3500 rpm to 4000 rpm, and the time is 40 min to 60 min. For example, the speed of the centrifugal treatment is 3500 rpm, 3600 rpm, 3700 rpm, 3800 rpm, 3900 rpm, 4000 rpm, etc. The time is 40 min, 45 min, 50 min, 55 min, 60 min, etc., but is not limited to the listed values, and other values ​​not listed in the above numerical range are also applicable.

[0017] In one embodiment of the present invention, the inert gas is argon.

[0018] The second object of the present invention is to provide the Nb prepared above 2 C@Zn composites.

[0019] The third object of the present invention is to provide the above-mentioned Nb 2 Application of C@Zn composites in aqueous zinc-ion batteries.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] In the present invention, Nb 2 C was peeled off to obtain a single layer of Nb 2 C, single layer Nb 2 C is adsorbed on the zinc powder to form an anti-catalytic hydrogen evolution inhibition layer Nb with high energy density and capable of inhibiting H* adsorption. 2 C@Zn composites, in Nb 2 Under the protection of C@Zn composite materials, the formation of adsorbed hydrogen atoms can be inhibited, thereby inhibiting the evolution of hydrogen, which can improve the Coulombic efficiency of aqueous zinc-ion batteries and enhance the cycle stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The scanning images of different materials, among which (a) is the SEM image of Zn powder nanoparticles; (b) is the SEM image of a single layer of Nb 2 SEM image of CMXene; (c) Nb 2 SEM image of C@Zn, (d) is Nb 2 TEM image of C@Zn.

[0023] Figure 2 Zn nanoparticles, Nb2 C MXene and Nb 2 XRD pattern of C@Zn.

[0024] Figure 3 The XPS diagrams of different materials, where (a) is Nb 2 C, Zn and Nb 2 O1s narrow spectrum of C@Zn, (b) Nb 2 C and Nb 2 Nb 3d narrow spectrum of C@Zn, (c) Nb 2 C, Zn and Nb 2 Full spectrum of C@Zn.

[0025] Figure 4 For Zn / / Zn symmetric cells and Nb 2 C@Zn / / Nb 2 The C@Zn symmetric battery has a current density of 10 mA cm -2 The capacity is 10 mAh cm -2 Cycle performance diagram under conditions of . DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] Catalytic steps in hydrogen evolution and gas production at zinc anode: The hydrogen evolution process at zinc metal anode is H + Obtaining e at the zinc anode - The process of being reduced to a hydrogen intermediate (H*) and precipitated as hydrogen bubbles. The key catalytic steps in hydrogen evolution and gas production at the zinc anode are the electrochemical reaction step and the conversion step. 3 O + It is transported to the liquid layer near the electrode surface and receives electrons at the zinc negative electrode. - A reduction reaction occurs, generating adsorbed hydrogen atoms (M (Zn) H), called the Volmer reaction: H 3 O + +e→M (Zn) H+H 3 O + ; M generated on the surface of the zinc negative electrode (Zn) H, may generate hydrogen by Tafel or Heyrovsky reaction and desorb from the surface of zinc negative electrode; Tafel reaction: M (Zn) H+M(Zn) H→H 2 ; Heyrovsky reaction: M (Zn) H+H 3 O + +e→H 2 +H 2 O.

[0028] The present invention provides a Nb 2 C@Zn composites, electron donor-modified Nb based on MH* bond regulation 2 The anti-catalytic inhibition layer of C@Zn inhibits the hydrogen evolution mechanism, such as Figure 1 As shown: By regulating the MH* bond strength and changing the bond strength between the H* intermediate and the electrode, the occurrence of the hydrogen evolution reaction can be slowed down or even blocked by blocking the rate-controlling step of the Volmer reaction in the hydrogen evolution process. A microscopic electrocatalytic hydrogen evolution interface is formed between the zinc negative electrode and the electrolyte, and the zinc negative electrode is analogous to the electrocatalyst electrode. The electrochemical overpotential of the hydrogen evolution reaction is related to two steps: the adsorption of the H* intermediate on the electrode and the H 2 Gas desorption, these two steps are related to the binding energy between the hydrogen intermediate and the electrode surface, that is, the strength of the MH* bond. Therefore, the anti-catalytic strategy of regulating the strength of the MH* bond is an effective strategy to control the hydrogen evolution reaction of aqueous zinc.

[0029] The present invention is based on Nb 2 C@Zn composites proposed an anti-catalytic strategy for MH* bond regulation, which can finely control the strength of MH* bonds and regulate the H * The adsorption energy and reaction energy barrier on the zinc surface inhibit the generation of adsorbed hydrogen atoms, hinder the occurrence of Volmer reaction, and thus inhibit the precipitation of hydrogen. Finally, a high-voltage halogen positive electrode is matched to build a high-performance aqueous zinc-ion full battery. This provides a theoretical basis and practical guidance for the design and optimization of zinc negative electrodes, and provides reference and reference for the performance optimization of other metal negative electrode materials.

[0030] The present invention uses first-principles calculation to screen under-coordinated MXene materials with low H* intermediate adsorption energy and stable structure. Nb atoms are selected as metal active centers with relatively low H* adsorption energy. 2 CMXene, by adjusting Nb 2 The number of C MXene sheets further tunes the strength of the MH* bond, and the results show that the monolayer Nb 2 C MXene has a weaker MH* bond, which can more effectively hinder the adsorption of H*. 2 C MXene is combined with zinc powder particles with high energy density to obtain an anti-catalytic hydrogen evolution inhibition layer Nb with high energy density and ability to inhibit H* adsorption. 2C@Zn. Compared with the original zinc anode, the reverse catalytic hydrogen evolution inhibition layer Nb 2 The C@Zn-protected zinc anode has the advantages of lower energy barrier, higher antibonding orbital filling, and deeper d-band center shift.

[0031] Therefore, in the anti-catalytic hydrogen evolution inhibition layer Nb 2 Under the protection of C@Zn, the bonding strength between the H* intermediate in the electrolyte and the Zn metal anode is significantly weakened, thereby inhibiting the formation of adsorbed hydrogen atoms and blocking the occurrence of the rate-limiting electrochemical adsorption (Volmer) step in the hydrogen evolution process, thereby inhibiting the subsequent steps of Tafel reaction and electrochemical desorption step (Heyrovsky reaction), and then inhibiting the evolution of hydrogen, achieving the purpose of inhibiting hydrogen evolution, improving the Coulomb efficiency of aqueous zinc-ion batteries, and enhancing cycle stability. These improvements provide new insights and methods for the development of aqueous zinc-ion batteries.

[0032] Example 1

[0033] 1g multilayer Nb 2 C powder was mixed with 200 mL of deionized water, and Ar gas was introduced. The mixture was ultrasonically treated at room temperature for 1 h. After centrifugation at 3500 rpm for 60 min, the dark green supernatant was collected, which was the layered Nb 2 C colloidal suspension.

[0034] 20 mL of 1.6 mg mL -1 Layered Nb 2 C colloidal suspension was added to a 50 mL glass vial, and then 0.3 g of metallic zinc powder was added to the colloidal suspension and shaken vigorously for 3 s at room temperature. 2 Nb in C colloidal suspension 2 The C monolayer was immediately adsorbed and assembled on the surface of the zinc powder and quickly settled to the bottom of the vial. Finally, the precipitate was vacuum filtered through a polypropylene porous membrane (thickness 25±1μm, porosity 55%) and freeze-dried to obtain Nb 2 C@Zn nanocomposite material, denoted as Nb 2 C@Zn.

[0035] Example 2

[0036] 2g multilayer Nb 2 C powder was mixed with 400 mL of deionized water and treated with ultrasound under Ar flow for 1 h. After centrifugation at 3500 rpm for 60 min, the dark green supernatant was collected, which was the layered Nb 2 C colloidal suspension.

[0037] 20 mL of 1.6 mg mL -1 Layered Nb 2C colloidal suspension was added to a 50 mL glass vial, and then 0.5 g of metallic zinc powder was added to the colloidal suspension and shaken vigorously for 3 s at room temperature. 2 Nb in C colloidal suspension 2 The C monolayer was immediately adsorbed and assembled on the surface of the zinc powder and quickly settled to the bottom of the vial. Finally, the precipitate was vacuum filtered through a polypropylene porous membrane (thickness 25±1μm, porosity 55%) and freeze-dried to obtain Nb 2 C@Zn nanocomposite material, denoted as Nb 2 C@Zn.

[0038] Example 3

[0039] 2.2g multilayer Nb 2 C powder was mixed with 400 mL of deionized water and ultrasonically treated for 1.5 h under Ar flow. After centrifugation at 3800 rpm for 50 min, the dark green supernatant was collected, which was the layered Nb 2 C colloidal suspension.

[0040] 20 mL of 1.7 mg mL -1 Layered Nb 2 C colloidal suspension was added to a 50 mL glass vial, and then 0.29 g of metallic zinc powder was added to the colloidal suspension and shaken vigorously for 5 seconds at room temperature. 2 Nb in C colloidal suspension 2 The C monolayer was immediately adsorbed and assembled on the surface of the zinc powder and quickly settled to the bottom of the vial. Finally, the precipitate was vacuum filtered through a polypropylene porous membrane (thickness 25±1μm, porosity 55%) and freeze-dried to obtain Nb 2 C@Zn nanocomposite material, denoted as Nb 2 C@Zn.

[0041] Example 4

[0042] 2.4g multilayer Nb 2 C powder was mixed with 400 mL of deionized water and ultrasonically treated for 80 min under Ar flow. After centrifugation at 4000 rpm for 40 min, the dark green supernatant was collected, which was the layered Nb 2 C colloidal suspension.

[0043] 20 mL of 1.8 mg mL -1 Layered Nb 2 C colloidal suspension was added to a 50 mL glass vial, and then 0.32 g of metallic zinc powder was added to the colloidal suspension and shaken vigorously for 4 seconds at room temperature. 2 Nb in C colloidal suspension 2The C monolayer was immediately adsorbed and assembled on the surface of the zinc powder and quickly settled to the bottom of the vial. Finally, the precipitate was vacuum filtered through a polypropylene porous membrane (thickness 25±1μm, porosity 55%) and freeze-dried to obtain Nb 2 C@Zn nanocomposite material, denoted as Nb 2 C@Zn.

[0044] The following is a characterization using Example 1 as an example. The results are as follows Figure 1 to Figure 4 shown.

[0045] Figure 1 As can be seen in (a), the zinc powder (Zn) screened through a 1000-mesh sieve has a particle size of about 2 microns. Figure 1 (b) is a single layer Nb 2 SEM image of C MXene, from Figure 1 As can be seen from (c) and (d) in Example 1, Nb 2 In C@Zn, single-layer Nb 2 C MXene wraps the zinc powder like gauze and forms a good coating on the surface of the zinc powder. This coating effectively hinders the H + The formation of intermediates lays a solid foundation for inhibiting the hydrogen evolution reaction, indicating that the monolayer Nb 2 C MXene has been successfully encapsulated with zinc powder particles.

[0046] Figure 2 Given Nb 2 C MXene, Zn and Nb prepared in Example 1 2 X-ray diffraction (XRD) pattern of C@Zn. The XRD pattern of zinc powder particles is consistent with PDF card 04-0831. Moreover, Nb 2 The characteristic peak (002) near 8° in the XRD pattern of C MXene indicates that the monolayer Nb 2 C MXene has been successfully prepared. 2 In C@Zn, Nb 2 The characteristic peaks of C MXene and zinc powder particles indicate that Nb 2 C@Zn was successfully prepared without the generation of impurity phases, a result that echoes the findings of high-resolution transmission electron microscopy (HRTEM).

[0047] Figure 3 a~c in the figure are Zn, single layer Nb 2 C MXene and Nb prepared in Example 1 2 X-ray photoelectron spectroscopy (XPS) spectrum of C@Zn material. Due to direct exposure to air, the surface of the nano zinc powder will inevitably be slightly oxidized, which leads to a trace amount of oxygen.2 C MXene presents a distinct peak because Nb 2 C MXene contains -OH or -O- groups. The peak at 529.8 eV corresponds to oxygen bound to the Nb-OC bond, the peak at 531.8 eV corresponds to oxygen in the hydroxyl (-OH) group or water molecules, and the peak at 533.3 eV may be related to oxygen associated with adsorbed water molecules or hydroxide ions. 2 C MXene and Nb 2 The O1s spectrum of C@Zn material can clearly observe that Nb 2 The peak intensity of adsorbed water molecules or hydroxide ions in C@Zn material is obviously weaker. This indicates that after the addition of single-layer Nb 2 After CMXene, Nb 2 The ability of C@Zn materials to bind to water molecules or hydroxide ions is significantly reduced, which can play a key role in the hydrogen evolution inhibition strategy of aqueous zinc-ion batteries.

[0048] In addition, the Nb 3d spectrum shows a peak at 207.5 eV, which indicates that the oxidation state of niobium (Nb) may change from Nb 3+ Transformed to Nb 4+ . Nb 4+ The Nb 3d peak usually appears around 207.5 eV, while the peak at 210.2 eV may be due to the Nb 2 When C MXene is exposed to air, oxides (such as Nb 2 O 5 ) or hydroxides (such as Nb(OH) 4 ). This causes the Nb 3d peak to shift to higher binding energies (about 208 eV and above). Meanwhile, the peaks at 206.9 eV and 203.4 eV may be attributed to adsorbed water, oxygen or other impurities, which appear as additional oxides or surface adsorbates in X-ray photoelectron spectroscopy (XPS).

[0049] Figure 3 (c) shows zinc powder (Zn), Nb 2 C MXene and Nb 2 XPS spectrum of C@Zn. In the spectrum, it is found that when the analysis angle changes from shallow angle to large angle, the peak intensity of zinc element decreases rapidly, while the peak intensity of niobium element decreases relatively slowly. This may mean that zinc is mainly concentrated on the outermost surface of the sample, while niobium element is distributed deeper in the near-surface area, which is consistent with the adsorption of zinc nanoparticles on Nb 2 This is consistent with the research results on the surface of C MXene.

[0050] Nb 2 C@Zn / / Nb 2C@Zn and Zn / / Zn symmetric cells at 10 mA cm -2 、10mAh·cm -2 The long-term cycling stability was measured under the conditions of Figure 4 After initial activation, Nb 2 C@Zn / / Nb 2 The C@Zn symmetric battery can maintain stable charge and discharge cycles for 700 hours under the harsh conditions of 10 mA cm2. In contrast, the Zn / / Zn symmetric battery -2 At a current density of 2.5 Å, the Zn / / Zn symmetric battery failed rapidly after 100 hours. This indicates that the pure zinc anode has serious problems such as hydrogen evolution and zinc dendrite growth during cycling, resulting in a short battery life. In contrast, the Nb 2 The C@Zn electrode benefits from a protective anti-catalytic inhibitory layer that slows down the formation of hydrogen intermediates. This makes it difficult for hydrogen intermediates to adsorb on the electrode surface, suppressing the gas evolution problem and thus extending the battery life.

[0051] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0052] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for preparing a Nb2C@Zn composite material, characterized in that: The following steps are involved: Nb2C is dispersed in water and mixed evenly to obtain a Nb2C solution. Under an inert gas atmosphere, the Nb2C solution is ultrasonically treated to peel off Nb2C, and a supernatant is obtained after the treatment is completed. Zinc powder was added to the supernatant to adsorb Nb2C on the surface of zinc powder, and the Nb2C@Zn composite material was obtained after filtration.

2. The method for preparing a Nb2C@Zn composite material according to claim 1, characterized in that: The mass ratio of Nb2C to zinc powder in the supernatant is 1:9-16.

3. The method for preparing a Nb2C@Zn composite material according to claim 1, characterized in that: The adsorption time is 3s to 5s.

4. The method for preparing a Nb2C@Zn composite material according to claim 1, characterized in that: The ultrasonic treatment time is 1h to 1.5h.

5. The method for preparing a Nb2C@Zn composite material according to claim 1, characterized in that: The concentration of the Nb2C solution is 5 mg / mL to 6 mg / mL.

6. The method for preparing a Nb2C@Zn composite material according to claim 1, characterized in that: The rotation speed of the centrifugal treatment is 3500 rpm to 4000 rpm, and the time is 40 min to 60 min.

7. The method for preparing a Nb2C@Zn composite material according to claim 1, characterized in that: The inert gas is argon.

8. A Nb2C@Zn composite material prepared by the preparation method according to any one of claims 1 to 7.

9. Use of the Nb2C@Zn composite material according to claim 8 in an aqueous zinc ion battery.

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