Zinc-ion battery electrode material, electrode sheet, preparation method thereof and battery

Abstract

The application discloses a zinc ion battery electrode material, an electrode sheet, a preparation method of the electrode material and a battery, and the preparation steps of the zinc ion battery electrode material include: reacting raw materials with a chalcogen hydride at a predetermined temperature to obtain the zinc ion battery electrode material; the chalcogen hydride includes one or more of H2S, H2Se or H2Te; the raw materials are selected from at least one of a MAX phase material, a MXene material or a transition metal chalcogen compound MY2, M in the MY2 represents a transition metal element, and Y represents one of sulfur, selenium or tellurium.

Description

[0001] This application is a divisional application, the parent application of which is an invention patent application with the application date of April 18, 2022, the application number of "202210404234.7", and the invention name of "a transition metal chalcogenide compound and its preparation method, use and energy storage device". TECHNICAL FIELD

[0002] The present application belongs to the field of new materials and batteries, in particular to a zinc ion battery electrode material, an electrode sheet, a preparation method thereof and a battery. BACKGROUND

[0003] Two-dimensional nanocrystals such as graphene, hexagonal boron nitride (h-BN) and transition metal chalcogenide (TMC) have attracted extensive attention due to their extremely high anisotropy. In particular, 2D TMCs have multiple chemical functions, consisting of transition metals (M = V, Nb, Ta, Mo, W, etc.) and chalcogen elements (X = S, Se, Te), showing tunable electrical properties from semiconductors to semimetals and metals, with great prospects in the fields of electronics, optoelectronics, energy storage and conversion. Currently, the most widely studied 2D TMC nanocrystals are usually van der Waals (vdW) layers, such as MoS2 and WS2, which can be easily prepared by mechanical, liquid phase and electrochemical exfoliation of the corresponding bulk counterparts based on a top-down approach. During the exfoliation process, bulk layered TMC compounds with weak interlayer van der Waals forces can be cut by external forces (such as adhesion, shear force and ultrasonic action), thereby forming single layers and a small amount of 2D TMC nanocrystals. Compared with van der Waals TMC layers, 2D non-van der Waals TMCs are more difficult to prepare, because these compounds exist in a three-dimensional bonding network without interlayer van der Waals forces, making them difficult to be cut by common exfoliation methods and greatly hindering their further development and wide application.

[0004] Non-van der Waals TMCs can exist in various crystal structures, such as cubic pyrite and NiAs-type structures, which are composed of metal atoms surrounded by six octahedrally coordinated sulfur atoms. These unique structural features have anisotropic in-plane and out-of-plane bonding related to the tunable d-orbital electrons of specific transition metals, making non-van der Waals TMC nanocrystals have good electrical properties. For example, non-van der Waals vanadium sulfide, such as V5S8, is composed of VS2 layers, with V atoms embedded in VS6 octahedral coordination, which have localized and delocalized 3d electrons for embedded V atoms and other V atoms, respectively, making it have an electrical conductivity of about 500 S cm -1More strikingly, by isolating a large number of non-van der Waals TMCs to the 2D limit, fully exposed metals, abundant dangling bonds and unsaturated coordination are emerging, which are absent in 2D van der Waals TMCs, and 2D non-van der Waals TMCs can provide many electrochemically active sites. Unfortunately, so far, due to the three-dimensional bonding structure of two-dimensional non-van der Waals TMC nanocrystals, its preparation is still a great challenge. SUMMARY

[0005] The present application provides a new type of electrochemically active electrode material for zinc ion batteries, namely a class of 2D non-van der Waals transition metal chalcogenide compounds, which is a transition metal chalcogenide compound represented by the chemical formula M a Y 2a-2 , 3≤a≤5, and a preparation method thereof includes: reacting raw materials with a chalcogen hydride at a predetermined temperature to obtain; the chalcogen hydride includes one or more of H2S, H2Se or H2Te; the raw materials are selected from at least one of a MAX phase material, a MXene material or a transition metal chalcogenide MY2, M in MY2 represents one or more transition metal elements; and Y represents one of sulfur, selenium or tellurium elements.

[0006] In some embodiments, the above-mentioned zinc ion battery electrode material has an expanded body morphology of two-dimensional sheet layer stacking.

[0007] In some embodiments, the above-mentioned zinc ion battery electrode material has a two-dimensional sheet layer morphology.

[0008] In some embodiments, the above-mentioned two-dimensional sheet layer has a thickness of 2nm to 10nm.

[0009] In some embodiments, the above-mentioned two-dimensional sheet layer has metal M vacancies.

[0010] In some embodiments, the above-mentioned two-dimensional sheet layer has a monoclinic crystal structure, or a hexagonal crystal structure.

[0011] In some embodiments, the above-mentioned zinc ion battery electrode material is represented by the chemical formula M a Y 2a-2 , 3≤ a ≤5, and M represents one or more transition metal elements.

[0012] In some embodiments, the above-mentioned M is selected from one or more of vanadium, titanium, chromium, molybdenum, tungsten or niobium elements.

[0013] In some embodiments, the above-mentioned predetermined temperature in the preparation method is 600°C to 800°C.

[0014] In some embodiments, the predetermined temperature is preferably 700°C.

[0015] The present invention also provides a zinc-ion battery positive electrode sheet, comprising the above-mentioned zinc-ion battery positive electrode material; and a conductive agent and a current collector.

[0016] In some embodiments, the conductive agent described above includes Ketjen black;

[0017] In some embodiments, the current collector is a titanium foil.

[0018] The present invention also provides a method for preparing the above-mentioned zinc-ion battery positive electrode sheet, the steps of which include: mixing the above-mentioned zinc-ion battery positive electrode material and the above-mentioned conductive agent to form a slurry; coating the slurry onto the above-mentioned current collector and drying it to obtain the final product.

[0019] The present invention also provides a zinc-ion battery comprising the zinc-ion battery electrode material described above, or the zinc-ion battery electrode sheet described above.

[0020] This invention provides a novel technical route for the preparation of 2D non-van der Waals transition metal chalcogenides and yields a novel class of transition metal chalcogenide materials with two-dimensional ultrathin characteristics, highly exposed surfaces, high conductivity, and a unique vacancy structure. Based on these structural features, this invention also provides applications for their use in ion storage, serving as electrode materials for batteries or supercapacitors. In particular, the 2D non-van der Waals transition metal chalcogenides of this invention provide novel electrode materials for the development of non-lithium ion energy storage devices, particularly for ions with larger ionic radii such as zinc, sodium, and aluminum ions. Attached Figure Description

[0021] Figure 1 This is a schematic diagram (a) of the process of converting MAX-V2GeC into 2D Non-vdWV3S4 during heat treatment in Embodiment 1 of the present invention; the XRD pattern (b) and XPS measurement spectrum (c) of the obtained 2D Non-vdWV3S4.

[0022] Figure 2 This is a SEM image of 2D Non-vdW V3S4 in Embodiment 1 of the present invention;

[0023] Figure 3 The morphological characterization of 2D Non-vdW V3S4 in Embodiment 1 of the present invention includes: cross-sectional TEM images (a) and (b) of 2D Non-vdW V3S4; cross-sectional HRTEM image (cd) of 2D Non-vdW V3S4; AFM image (e) of 2D Non-vdW V3S4 and corresponding thickness analysis (f);

[0024] Figure 4 SEM image of precursor MAX-V2GeC in Example 1 of the present application;

[0025] Figure 5 For 2D Non-vdW V3S4 in Example 1 of the present application, the structure and electrical properties, including: SEM image of 2D Non-vdW V3S4 (a), showing ultrathin transparent nanosheets; HRTEM image of 2D Non-vdW V3S4 and (inset) the corresponding FFT pattern, showing hexagonal regular atomic arrangement and single-crystalline feature (b); HRTEM image of 2D Non-vdW V3S4 (c), where many V vacancies are circled; atomic model of monoclinic V3S4 in top view, where V vacancies are highlighted with dashed circles (d); Raman spectrum of 2D Non-vdW V3S4 (e), showing typical peaks of V-S bond vibration modes; current-voltage curves of 2D Non-vdW V3S4 and MXene V2C (f), revealing metallic feature of V3S4 nanocrystals; x

[0026] Figure 6 For 2D Non-vdW V3S4 nanocrystals in Example 1 of the present application, high-resolution V 2p XPS spectrum (a) and high-resolution S 2p XPS spectrum (b), indicating the presence of V-S bond and V-O bond therein;

[0027] Figure 7 For 2D Non-vdW V3S4 nanocrystals in Example 1 of the present application, VK-edge X-ray absorption near-edge structure (XANES) spectrum (a) and Fourier transform of EXAFS spectrum of V3S4, V2O5 and V foil (b);

[0028] Figure 8 For vdW VS2 and Non-vdW V3S4 at high temperature of 600℃ in Example 2 of the present application, XRD patterns (a) showing significantly different diffraction peaks, and indicating that vdW VS2 will be converted to Non-vdW V3S4 after heat treatment, SEM image of converted Non-vdW V3S4 (b) does not show obvious layered morphology;

[0029] Figure 9 For the electrochemical performance of 2D Non-vdW V3S4 for zinc storage in aqueous electrolyte in Example 4 of the present application, including: specific capacity of 2D Non-vdW V3S4 for zinc storage in aqueous electrolyte at 50 mA g -1 ​The constant current discharge-charge curve (a) shows the high reversible capacity during the discharge-charge process; Non-vdW V3S4-600, Non-vdW V3S4-700 and Non-vdW V3S4-800 at 50 mA g -1 Cyclic performance (b) and rate performance (c); Non-vdW V3S4-7000 at 5000 mA g -1 Cyclic performance (d) under the following conditions;

[0030] Figure 10 In Example 4 of this invention, the precursor V2GeC is at 50 mA g -1 Cyclic performance at current density;

[0031] Figure 11 The material characterization of 2D Non-vdW V3S4 nanocrystals during zinc storage discharge-charge cycles in Embodiment 4 of the present invention includes: 2D contour plots (a) of 2D Non-vdW V3S4 nanocrystals obtained by in-situ XRD measurement during the discharge-charge process, and 50 mA g... -1 The corresponding discharge-charge curve (b) is shown; Zn is stored using V vacancies on the 2D Non-vdW V3S4 substrate. 2+ Schematic diagram (c); HRTEM image (d) of 2D Non-vdW V3S4 nanocrystals after discharge, showing good crystallinity; elemental mapping images of V (e), S (f) and Zn (g) species of 2D Non-vdW V3S4 nanocrystals in the discharge state;

[0032] Figure 12 The electrochemical impedance spectroscopy (EIS) spectrum of the zinc-ion battery in Example 4 of this invention is shown.

[0033] Figure 13 In Example 4 of this invention, the assembled battery exhibits the following cycling performance in a 0.05 M potassium hydrogen phthalate electrolyte: a voltage range of 0.3 to 1.6 V and a current density of 50 mA g. -1 ;

[0034] Figure 14 In Embodiment 4 of the present invention, the 2D Non-vdW V3S4 is used at scan rates ranging from 0.01 to 50 mV / s. -1 The CV curve (a) and the logarithmic relationship curves of peak current and scan rate for anode and cathode (b) show the hybrid pseudocapacitive behavior during the discharge-charge cycle;

[0035] Figure 15For the electrochemical performance of 2D Non-vdW V3S4 in Example 5 of the present application, including: the galvanostatic charge-discharge curves of 2D Non-vdW V3S4 at 50 mA g -1 current density (a); the cycle performance of Non-vdW V3S4 nanocrystals at 2 A g -1 current density (b); the rate performance of Non-vdW V3S4 nanocrystals (c); the cycle performance of Non-vdW V3S4-700 at 2 A g -1 current density (d);

[0036] Figure 16 For the XRD patterns of 2D Non-vdW Ti5S8 and its precursor Ti2SnC in Example 6 of the present application;

[0037] Figure 17 For the SEM (a), TEM (b), HRTEM (c) and FFT patterns (d) of 2D Non-vdW Ti5S8 in Example 6 of the present application;

[0038] Figure 18 For the STEM (a), element distribution maps of Ti (b) and S (c) of 2D Non-vdW Ti5S8 in Example 6 of the present application. DETAILED DESCRIPTION

[0039] The technical solutions of the present application are described below through specific examples. It should be understood that the one or more steps mentioned in the present application do not exclude the existence of other methods and steps before and after the combination steps, or other methods and steps can be inserted between these explicitly mentioned steps. It should also be understood that these examples are only used to illustrate the present application and not to limit the scope of the present application. Unless otherwise specified, the numbering of each method step is only for the purpose of identifying each method step, and not to limit the arrangement order of each method or to limit the scope of the implementation of the present application. Changes or adjustments of the relative relationship, without substantial technical content changes, can also be considered as the scope of the implementation of the present application.

[0040] The raw materials and instruments used in the examples are not specifically limited in source, and can be purchased on the market or prepared according to the conventional methods well known to those skilled in the art.

[0041] The technical solution of the present application includes: using MAX phase material as a precursor, high-temperature heat treatment in a sulfur hydride atmosphere, and we find that in this heat treatment process, on the one hand, the sulfur hydride can etch the A component therein; on the other hand, the sulfur element can replace the X element to form MS2; and on the other hand, the vanadium atoms in the van der Waals gap of the MS2 layer are self-intercalated to form M 1+x S2 layer, and finally form 2D non-van der Waals M3S4 or M5S8 nanocrystals. The 2D non-van der Waals transition metal chalcogenide compound has a unique two-dimensional layer-stacked swelling body structure, and the 2D non-van der Waals transition metal chalcogenide super-thin sheet layer can be obtained through simple processing (such as ultrasonic).

[0042] In the present application, the MAX phase material is replaced by MXene material, that is, the A component in the MAX phase material is etched in advance, and then the product MXene material is reacted with a sulfur hydride at a certain temperature, and the 2D non-van der Waals transition metal chalcogenide sheet layer can also be obtained.

[0043] It is also found in the present application that the raw material is replaced by a van der Waals transition metal chalcogenide MY2, which is reacted with a sulfur hydride at a certain temperature, and the transition metal chalcogenide MY2 can be converted to produce a non-van der Waals transition metal chalcogenide.

[0044] It should be noted that in the present application, the sulfur element includes sulfur (S), selenium (Se) and tellurium (Te) elements, and the above examples take the sulfur element in the sulfur element as an example for description. Since Se and Te elements are in the same group as S element, they have similar chemical and physical properties, and by adjusting the experimental conditions, 2D non-van der Waals transition metal chalcogenide (such as V3Se4, V3Te4, Ti5Se8, Ti5Te8, etc.) nanocrystals can also be obtained.

[0045] Example 1

[0046] In order to better illustrate the technical features of the present application, the present embodiment provides a two-dimensional non-van der Waals vanadium-based chalcogenide V3S4 and a preparation method thereof, and the steps include:

[0047] 1) Preparation of MAX phase material: Vanadium powder (V, 99.9%, 100-200 mesh, Aldrich Reagent), germanium powder (Ge, 99.999%, 100 mesh, Alpha Aesar), and graphite (C, 99.9%, 10 mesh, Alpha Aesar) are sealed in a agate container with agate balls and ground at 600 rpm for 20 h. The molar ratio of V / Ge / C is 2:1.05:1. Then the powder mixture is transferred to a tube furnace and heated at a heating rate of 3℃ min -1 -1400℃. The mixture is kept at this temperature for 4 hours to obtain the MAX phase material, marked as MAX-V2GeC;

[0048] 2) Preparation of 2D non-van der Waals V3S4 nanocrystals: The V2GeC prepared in step 1 (300 mg) was heated under Ar flow at a heating rate of 10 °C min -1 -1, then a H2S / Ar (10 vol.% H2S) mixture was introduced when the temperature reached different temperatures (600, 700 and 800 °C). The temperature was kept for 2 h to obtain the product 2D non-van der Waals V3S4 nanocrystals, which were then ultrasonically treated in an IPA solvent. The obtained product was labeled as non-vdW V3S4-X (X represents the reaction temperature).

[0049] Figure 1 a shows the schematic diagram of the process of converting MAX phase material (MAX-V2GeC) to 2D non-van der Waals vanadium-based chalcogenide (V3S4). At high temperature (600 to 800 °C), the germanium layer in MAX-V2GeC first reacts with hydrogen sulfide to form germanium sulfide (GeS) at a temperature higher than 600 °C. Since the GeS intermediate is gaseous at this temperature range, it can be easily removed from the reaction system to obtain high-purity V3S4. At the same time, the vanadium atoms in the van der Waals gap of the VS2 layer are self-intercalated to form V 1+x S2 layer, and finally gradually form a 2D non-van der Waals V3S4 layer.

[0050] Figure 1 b shows the XRD pattern of the obtained non-van der Waals V3S4. It can be seen that the non-van der Waals V3S4 detects a series of strong peaks at 15.3°, 17.0°, 28.0°, 31.0°, 34.6°, 44.5° and 45.1° on the (002), (101), (011), (110), (1-12), (1-14) and (204) faces, respectively, while the main peak at 41.1° of MAX-V2GeC is not visible; it can also be seen that there is no other impurity in the non-van der Waals V3S4, indicating that MAX-V2GeC has completely converted in our synthesis process. X-ray photoelectron spectroscopy (XPS) measurement spectrum Figure 1 c and the insert) further shows that the obtained product shows S and V species without any germanium element, indicating that the germanium layer is completely removed from V2GeC in our conversion reaction.

[0051] The morphology and microstructure of the 2D non-van der Waals TMC-V3S4 were characterized by scanning electron microscopy (SEM), as shown in Figure 2 The prepared sample has an expanded accordion-like layered structure, similar to the morphology of the accordion-like MXenes reported; the morphology and microstructure of the 2D non-van der Waals TMC-V3S4 were characterized by transmission electron microscopy (TEM), as shown in Figure 3a and b, the prepared sample has a highly expanded structure, similar to an accordion-like MXene, with a significantly different morphology from the precursor V2GeC bulk (as shown in Figure 4 Fig. 1). After simple sonication, the 2D non-van der Waals TMC-V3S4 with highly expanded structure can be exfoliated into ultrathin layered two-dimensional sheets. To further evaluate the thickness of the generated 2D layers, ultrathin sectioning experiments were performed, and cross-sectional HRTEM images are shown in Figure 3 c and d, there are many thin nanosheets with a thickness between 2.0 and 4.0 nm. Atomic force microscopy (AFM) images (Fig. 2) Figure 3 e) further reveal the existence of ultrathin nanosheets with an average thickness of 3.2 nm (Fig. 2) Figure 3 f), which is fully consistent with the cross-sectional HRTEM observation (Fig. 2) Figure 3 d and e). Of course, in some embodiments, the thickness of the ultrathin nanosheets of the present application can be between 2 nm and 10 nm.

[0052] The crystal structure of the prepared 2D non-van der Waals V3S4 layers can be further investigated by scanning electron microscopy (SEM) and high-resolution TEM (HRTEM) measurements. As shown in Figure 5 a and b, the atoms are regularly arranged in a hexagonal system in the ultrathin layers, showing high crystallinity. Figure 5 c measurements clearly show a spacing of 0.29 nm between the lattice fringes, which is related to the interplanar spacing between the monoclinic V3S4 (200) planes (Fig. 3) Figure 5 d). The good crystallinity of these 2D V3S4 nanocrystals can also be evidenced by the hexagonal diffraction spots in the fast Fourier transform (FFT) pattern (inset in Fig. 3) Figure 5 b). In the above HRTEM analysis, the calculated spacing of the (2-02) and (202-) points matches well with the interplanar spacing of the (2-02) plane. More notably, a large number of V vacancies are observed in the HRTEM image (Fig. 3) Figure 5 c), which should be the result of the migration of V atoms during the intercalation process at high temperature. This can be further evidenced by the relatively low V / S atomic ratio of 0.7:1 in the non-van der Waals TMC-V3S4 plane in the electron dispersive spectroscopy (EDS) analysis.

[0053] To determine the chemical structure of the prepared 2D non-van der Waals V3S4 nanocrystals, Raman measurements were performed. As shown in Figure 5 e, there are four main peaks at 276.2, 401.1, 682.5, and 984.5 cm -1 , corresponding to the rocking and stretching vibration modes of V-S bonds. The high-resolution XPS spectrum (Fig. 4) Figure 6a and b) and V K-edge extended X-ray absorption fine structure spectroscopy (EXAFS, Figure 7 a and b) further prove the existence of V-S bonds. In Figure 5 It can be seen that the 2D non-van der Waals TMC-V3S4 nanocrystals of the present application show a linear current-voltage relationship, and the low resistance is 3.2 kΩ□ -1 , which is only one fifth of MXene V2CT x (16.6 kΩ□ -1 ) far lower than metal 1T TMD, proving the high conductivity of 2D non-van der Waals V3S4 nanocrystals.

[0054] Example 2

[0055] This embodiment provides another preparation method of a two-dimensional non-van der Waals vanadium-based chalcogenide compound, i.e., the implementation of the transformation from VS2 to V3S4, and the specific implementation steps include:

[0056] 1) Synthesis of VS2 by hydrothermal method: two-dimensional van der Waals VS2 (vdW VS2) is synthesized by a simple hydrothermal method using NH4VO3 and TAA as precursors; for more specific implementation, please refer to Nature 2020, 577, 647.;

[0057] 2) Thermal treatment to convert vdW VS2 to non-van der Waals V3S4 nanocrystals (Non-vdW V3S4): prepared by thermal annealing at 600°C for 1h under H2S / Ar (10vol% H2S) flow to obtain two-dimensional Non-vdW V3S4.

[0058] Figure 8 a shows the XRD patterns of vdW VS2 and Non-vdW V3S4, and it can be seen that the characteristic peaks of Non-vdW V3S4 after heat treatment are significantly different from those of vdW VS2, indicating that the thermal treatment of vdW VS2 in a hydrogen sulfide-containing atmosphere can promote the conversion of vdW VS2 to Non-vdW V3S4. However, the Non-vdW V3S4 prepared in the comparative example obviously does not have the characteristics of layered expansion body and two-dimensional morphology, as shown in Figure 8 b, it can be seen that the 2D TMC prepared by using MAX phase material as a precursor has significantly different structural morphology characteristics.

[0059] Example 3

[0060] This embodiment provides another preparation method of a two-dimensional non-van der Waals vanadium-based chalcogenide compound, which uses MXenes material containing V element as a precursor and carries out high-temperature conversion reaction in a chalcogen hydride atmosphere.

[0061] For example, the preparation of 2D non-van der Waals V3S4 nanocrystals, the specific implementation steps include: placing MXenes material V2CT x powder in a high-temperature reaction furnace, heating at a heating rate of 10 ℃ min -1 under Ar flow, and passing in a H2S / Ar (10 vol.% H2S) mixture at different temperatures (600-1200 ℃). The temperature is maintained for 2 hours to obtain the product 2D non-van der Waals V3S4 nanocrystals.

[0062] wherein the MXenes material V2CT x is obtained by etching Al in the MAX phase material V2AlC. Different etchants can be selected, such as hydrofluoric acid solution, halogen metal salt and acid solution mixture, or molten metal salt, etc. In this embodiment, more specifically, V2AlC is placed in an HF acid solution and etched at 80 ℃ for 24 h.

[0063] Example 4

[0064] From the above examples, it can be seen that the 2D non-van der Waals vanadium-based chalcogenide compound prepared by the present application has the characteristics of two-dimensional ultra-thin, highly exposed surface, high conductivity and unique vacancy structure, and we believe that it can be used for ion storage (such as lithium ion, sodium ion, zinc ion, aluminum ion, etc.), as a battery electrode material or an electrode material for supercapacitors.

[0065] In this embodiment, we provide a method for applying the 2D non-van der Waals vanadium-based chalcogenide compound of the present application to zinc ions with a larger ionic radius in an aqueous electrolyte, i.e., providing a zinc ion battery, wherein the 2D non-van der Waals vanadium-based chalcogenide compound of the present application is used as an electrode material to prepare a working electrode, and then a zinc foil is used as a counter electrode, a glass fiber is used as a separator, and an electrolyte is 3 mol L -1 Zinc trifluoromethanesulfonate (Zn(CF3SO3)2) is assembled to obtain a button-type zinc ion battery to test the electrochemical performance; wherein the working electrode is prepared by mixing 80wt.% 2D V3S4, 10wt.% Ketjen black and 10wt.% PVDF in NMP, uniformly coating on a Ti foil, and vacuum drying at 120 ℃ for 12 h; the constant current discharge / charge test is carried out on a blue electric system (CT2001A), and the voltage range is 0.3-1.6 V (relative to Zn / Zn 2+ ).

[0066] As shown in Figure 9 a and b, 2D non-van der Waals V3S4 (Non-vdW V3S4-700) converted from V2GeC at 700 ℃ can achieve 341 mAh g -1 at a current density of 50 mA g -1, which is much higher than that of the V2GeC precursor (18 mAh g -1 . Figure 10 ), 2D TMC-V3S4 (200~300 mAh g -1 ) produced at other temperatures, and currently reported transition metal chalcogenides. More importantly, 2D Non-vdW V3S4-700 exhibits high rate performance (Fig. Figure 9 c) at different current densities from 50 to 10000 mA g -1 . Even at a high current density of 10000 mA g -1 , the reversible capacity of 2D Non-vdW V3S4-700 remains at 162 mAh g -1 , which should be attributed to the fast diffusion of zinc ions in the vacancy-rich 2D V3S4 nanocrystals. Moreover, after 1200 cycles at 5000 mA g -1 , a stable capacity of 152 mA g -1 is maintained at a capacity retention of 71% (Fig. Figure 9 d), indicating that 2D Non-vdW V3S4 is a very promising ion storage electrode material.

[0067] To elucidate the discharge-charge mechanism of Zn 2+ in 2D Non-vdW V3S4 nanocrystals, in-situ XRD and TEM measurements were further performed during the galvanostatic discharge-charge process. In the two-dimensional contour plot of the in-situ XRD patterns (Fig. Figure 11 a), the characteristic peaks of (002), (101), (011), (110), (1-12), (1-14), (204) planes of 2D Non-vdW V3S4 at 15.3°, 17.0°, 28.0°, 31.0°, 34.6°, 44.5°, 45.1° remain unchanged during the discharge and charge processes (Fig. Figure 11 b). This indicates that 2D Non-vdW V3S4 nanocrystals have good structural stability after Zn 2+ intercalation and delamination, which is in good agreement with the ex-situ XRD measurement results. This can be attributed to the large number of V vacancies in the highly exposed surface and basal plane, which not only facilitates the access of electrolyte, but also helps the fast transfer of Zn 2+ during the discharge-charge process (Fig. Figure 11 c). This can be further verified by the reduced semicircle diameter in the electrochemical impedance spectroscopy (EIS) spectra (Fig. Figure 12 ). Therefore, the 2D Non-vdW V3S4 nanocrystals still maintain their original structure and good crystallinity after repeated cycles, as shown in the HRTEM images (Fig. Figure 11d). Elemental mapping image of the 2D Non-vdW V3S4 layer under discharge state ( Figure 11 e~g) shows the uniform distribution of V, S and Zn species.

[0068] To verify the source of the electrochemical performance of the 2D Non-vdW V3S4 electrode material of the present invention, a coin cell was assembled in this comparative example using a method similar to that in Example 3, except that the electrolyte was replaced with a Zn-free electrolyte. 2+ A 0.05 M potassium hydrogen phthalate buffer solution (pH=4) was used. During charging and discharging, the capacity of the 2D Non-vdW V3S4 nanocrystals was negligible, at 6 mAh g⁻¹. -1 ( Figure 13 This confirms that the electrochemical behavior of 2D Non-vdW V3S4 is entirely derived from Zn. 2+ Reversible insertion, rather than proton intercalation. Furthermore, the hybrid pseudocapacitive behavior of the 2D Non-vdW V3S4 nanocrystals can be demonstrated by cyclic voltammograms (CV) from 0.3 to 1.6 V in the range of 0.1 to 50 mV s. -1 Proof at the scan rate ( Figure 14 a). The fitting results for the b values ​​(based on the relationship: i=aνb) show that the b values ​​for the anode peak and the cathode peak are 0.88 and 0.85, respectively. Figure 14 (b) corresponds to the hybrid pseudocapacitive behavior of zinc storage, which can be attributed to the presence of highly exposed surfaces in 2D Non-vdW V3S4.

[0069] Example 5

[0070] This embodiment provides an implementation method for using the 2D non-van der Waals vanadium-based chalcogenide compound prepared according to the present invention for sodium-ion storage. More specifically, 2D Non-vdW V3S4 is used as the working electrode material of the sodium-ion battery, with metallic sodium as the counter electrode, a polypropylene porous membrane, and a 1M NaPF6 organic solution as the electrolyte, to assemble a coin-type sodium-ion battery for testing electrochemical performance. The working electrode is prepared by mixing 80 wt.% 2D V3S4, 10 wt.% Ketjen Black, and 10 wt.% PVDF in NMP, uniformly coating it on a Cu foil, and vacuum drying at 120°C for 12 h. The constant current discharge / charge test is conducted on a Blue Electric system (CT2001A) with a voltage range of 0.05-3.0V (relative to Na / Na). + ).

[0071] like Figure 15 As shown in a and b, 2D non-van der Waals V3S4 (Non-vdW V3S4-700) converted from V2GeC at 700℃ at 50 mA g -1of 500 mAh g -1 -1 at 50 to 5000 mA g -1 of 230 to 350 mAh g -1 Figure 15 c). Even at a high current density of 2 A g -1 -1 Figure 15 d), which can also be attributed to the fast diffusion of sodium ions in the vacancy-rich 2D V3S4nanocrystals. It is further demonstrated that 2D Non-vdW V3S4is a promising ion storage electrode material.

[0072] Example 6

[0073] This example provides a two-dimensional non-van der Waals titanium-based chalcogenide compound Ti5S8 and a preparation method thereof, the steps comprising:

[0074] 1) Preparation of MAX phase material: titanium powder (Ti, 99.99%, 300 mesh, Aldrich), tin powder (Sn, 99.95%, 100 mesh, Aldrich), graphite (C, 99.9%, 10 mesh, Alpha Aesar) were sealed in a agate container with agate balls and ball-milled at 600 rpm for 20 h. The molar ratio of Ti / Sn / C was 2:1.5:1. Then the powder mixture was transferred to a tube furnace and heated at 1300 °C with a heating rate of 3 °C min -1 -1. The mixture was kept at this temperature for 2 hours to obtain the MAX phase material, labeled as MAX-Ti2SnC;

[0075] 2) Preparation of 2D non-van der Waals Ti5S8nanocrystals: The MAX-Ti2SnC was heated at 10 °C min -1 ​​​​The Ti₂SnC (300 mg) prepared in step 1 was heated at a heating rate, and then an H₂S / Ar (10 vol.% H₂S) mixture was introduced at different temperatures (800, 900, and 1000 °C). This temperature was maintained for 2 hours to obtain 2D non-van der Waals Ti₅S₈ nanocrystals, which were then ultrasonically treated in IPA solvent. The resulting product was labeled non-vdWTi₅S₈-X (X represents the reaction temperature). At high temperatures (800 to 1200 °C), the tin layer in MAX-Ti₂SnC first reacts with hydrogen sulfide to form tin sulfide (SnS) at temperatures above 700 °C. Since the SnS intermediate is gaseous at this temperature range, it can be easily removed from the reaction system to obtain high-purity Ti₅S₈. Simultaneously, vanadium atoms self-intercalate through the van der Waals interstices of the TiS₂ layer to form Ti. 1+x The S2 layer eventually formed a 2D non-van der Waals Ti5S8 layer.

[0076] Figure 16 The XRD pattern of the obtained non-van der Waals Ti5S8 is given. It can be seen that the non-van der Waals Ti5S8 has diffraction peaks at 15.5°, 31.1°, 34.0°, 38.4°, 43.9°, 47.6°, 50.3°, 53.5°, 56.0°, 57.4°, 64.9° and 65.1° corresponding to the (002), (101), (102), (103), (104), (006), (105), (110), (112), (106), (202) and (008) crystal planes, while the main diffraction peaks of MAX-Ti2SnC have disappeared. It can also be seen that there are no other impurities in the XRD diffraction pattern of the non-van der Waals Ti5S8, indicating that MAX-Ti2SnC underwent a complete transformation during our synthesis process.

[0077] The morphology and microstructure of 2D non-van der Waals TMC-Ti5S8 were characterized using scanning electron microscopy (SEM) and transmission electron microscopy (TEM), such as... Figure 17 As shown in a, the prepared sample has a highly expanded structure, similar to accordion-shaped MXenes, which is significantly different from the bulk morphology of the MAX phase. After simple sonication, the 2D non-van der Waals TMC-Ti5S8 of this highly expanded structure can be peeled off to obtain ultrathin two-dimensional sheets. Figure 17 b). In high-resolution TEM (HRTEM) images ( Figure 17 In c), atoms are regularly arranged in a hexagonal system within the ultrathin layer, exhibiting high crystallinity, with an interplanar spacing of 0.28 nm corresponding to the (100) crystal plane. The hexagonal diffraction spots in the Fast Fourier Transform (FFT) pattern ( Figure 17d) to further demonstrate the good Ti5S8 single crystal structure prepared. The results of the element mapping analysis of TEM (Fig. 6) show the uniform presence of Ti and S elements, indicating that the non-van der Waals two-dimensional material Ti5S8 is prepared by converting Ti2SnC. Figure 18

[0078] In summary, the present application provides a new technical path for the preparation of 2D non-van der Waals transition metal sulfide, and obtains a new type of transition metal chalcogenide material with a two-dimensional ultra-thin feature, a highly exposed surface, high conductivity and a unique vacancy structure. Based on these structural characteristics, the present application also provides the use of the material as an ion storage, which can be used as an electrode material for batteries or supercapacitors. In particular, the 2D non-van der Waals transition metal chalcogenide of the present application provides a new electrode material for the development of non-lithium ion-based new energy storage devices for ions with larger ion radius such as zinc ions, sodium ions, aluminum ions, etc.

[0079] The foregoing description of specific exemplary embodiments of the application is intended to be illustrative only and is not intended to limit the application to the precise forms described. Many modifications and variations are possible in light of the above teachings without departing from the spirit or essential characteristics of the present application. The particular exemplary embodiments were chosen and described in order to explain the principles of the application and its practical application to thereby enable others skilled in the art to best utilize the application and various embodiments with various modifications as are suited to the particular use contemplated. It is intended that the scope of the application be defined by the claims and their equivalents.​

Claims

1. A zinc-ion battery electrode material, characterized in that, The zinc-ion battery electrode material is a two-dimensional non-van der Waals transition metal dichalcogenide compound, with the chemical formula M. a Y 2a-2 3≤a≤5; The preparation steps of the zinc-ion battery electrode material include: reacting the raw material with a sulfide hydride at a predetermined temperature; the sulfide hydride includes one or more of H2S, H2Se or H2Te; the raw material is selected from at least one of MAX phase material, MXene material or transition metal sulfide compound MY2, where M in MY2 represents a transition metal element; Y represents one of sulfur, selenium or tellurium; the zinc-ion battery electrode material has a two-dimensional sheet-like morphology of an expanded body; or, the zinc-ion battery electrode material has a two-dimensional sheet morphology; the two-dimensional sheet contains metal M vacancies.

2. The zinc-ion battery electrode material as described in claim 1, characterized in that, The thickness of the two-dimensional sheet is between 2 nm and 10 nm.

3. The zinc-ion battery electrode material as described in claim 1, characterized in that, The two-dimensional sheet has a monoclinic crystal structure or a hexagonal crystal structure.

4. The zinc-ion battery electrode material as described in claim 1, characterized in that, M is selected from one or more of the elements vanadium, titanium, chromium, molybdenum, tungsten, or niobium.

5. The zinc-ion battery electrode material according to any one of claims 1 to 4, characterized in that, The predetermined temperature is between 600°C and 800°C.

6. The zinc-ion battery electrode material as described in claim 5, characterized in that, The predetermined temperature is 700℃.

7. A zinc-ion battery electrode sheet, characterized in that, include: Zinc-ion battery electrode material as described in any one of claims 1 to 6; In addition, conductive agents and current collectors.

8. The zinc-ion battery electrode sheet as described in claim 7, characterized in that, The conductive agent includes Ketjen Black; And / or, the current collector is a titanium foil.

9. A method for preparing a zinc-ion battery electrode sheet as described in claim 7 or 8, characterized in that, step... include: The zinc-ion battery electrode material and the conductive agent are mixed and then prepared into a slurry. The slurry is coated onto the current collector and then dried.

10. A zinc-ion battery, characterized in that, include: Zinc-ion battery electrode material as described in any one of claims 1 to 6; Or, the zinc-ion battery electrode sheet as described in claim 7 or 8; Alternatively, the zinc-ion battery electrode sheet obtained by the preparation method as described in claim 9.

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