A plant carbon-supported metal compound nanocomposite, its preparation method and application

Abstract

The present invention relates to a plant carbon-supported metal compound nanocomposite, a preparation method thereof, and an application thereof. By selecting a plant substance and impregnating it in a transition metal oxysalt solution, a carbon-supported metal compound nanocomposite is obtained through freeze-drying pyrolysis carbonization. The present invention utilizes the capillary action and concentration difference action of plants to adsorb inorganic salts, and with the confinement and support action of inorganic additives, the natural ordered structure and elemental components of plants are retained during the freeze-drying carbonization process, providing a smooth insertion / extraction channel for metal ions during the cycling process and ensuring the rapid transmission of metal ions; the template, doping, and activation effects of the transition metal oxysalt additives are utilized to induce uniform doping of heteroatoms, forming a hierarchical porous carbon structure, providing a large number of active sites for ions, facilitating the uniform deposition of metals, and effectively improving the capacity; at the same time, the metal compound obtained by the reduction of the transition metal oxysalt during the carbonization process can induce the uniform nucleation of metal ions on its surface, further improving the capacity. Therefore, when the plant carbon-supported metal compound nanocomposite is used as the negative electrode material of a secondary battery, it exhibits excellent energy storage and fast charging performance.

Description

Technical Field

[0001] The present invention relates to the technical field of nanocomposites, and particularly relates to a plant carbon-supported metal compound nanocomposite and a preparation method and application thereof. Background Art

[0002] Facing the increasingly severe energy and environmental problems, promoting the use of clean energy has become one of the most effective ways to achieve sustainable development. As an energy storage device, secondary batteries can realize the storage and utilization of clean energy. However, their performance still needs to be further improved and the cost still needs to be further reduced. Therefore, developing high-performance and low-cost electrode materials is of great significance for the large-scale application of secondary batteries.

[0003] Carbon-based electrode materials have the advantages of good electrical conductivity, wide sources, stable chemical properties, and low cost. However, commercial graphite anode materials have disadvantages such as poor cycling performance and low specific capacity. Different from graphite anode materials, carbon nanomaterials loaded with metal compounds can be used as excellent secondary battery anode materials. With the confinement and support of additives, the original structure and components of carbon materials can be retained; the metal compounds and high specific surface area provide a large number of nucleation sites, making the carbon nanomaterials have high reversible capacity.

[0004] Plants are ideal precursors for preparing carbon nanomaterials loaded with metal compounds. Plants have natural morphological structures and chemical components. Through pyrolysis control, the natural one-dimensional, two-dimensional, and three-dimensional structures of plants are partially retained. At the same time, non-carbon elements such as oxygen, nitrogen, sulfur, and phosphorus contained in plants can directly realize in-situ doping of heteroatoms during the pyrolysis process. However, many problems still exist in the material preparation process. First, it is difficult to retain the natural micro-nano structure and chemical composition of plants. The large loss of organic components and carbonization reconstruction cause the original natural micro-nano structure of plants to lose stability and collapse. Second, due to the uneven distribution of additives in plants and most of them are distributed on the surface, the additives only create pores and dope on the surface of plants and the distribution is uneven, making it difficult to regulate the morphological structure and chemical composition of plant-based carbon materials. Therefore, how to design a simple and efficient scheme to precisely regulate the morphological structure and chemical components of carbon materials with plants as precursors and realize the preparation of low-cost and high-performance plant carbon-supported metal compound nanomaterials is of great significance for promoting the large-scale application of secondary batteries. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the technical problems existing in the negative electrode materials of secondary metal / ion batteries, such as limited capacity, rapid ion transport, uneven deposition of metal on the electrode surface, easy growth of dendrites, irreversible volume expansion, and poor safety, which cannot be effectively solved in the prior art. The present invention provides a plant carbon-supported metal compound nanomaterial, which is obtained by impregnating a plant substance in a transition metal oxyacid salt solution and then performing freeze-drying pyrolysis carbonization. The present invention utilizes the capillary action and concentration difference action of plants to adsorb inorganic salts, and with the confinement and support action of inorganic additives, retains the natural ordered structure and elemental composition of plants during the freeze-drying carbonization process, providing a smooth insertion and extraction channel for metal ions during the cycling process, ensuring the rapid transport of metal ions; utilizes the templating, doping, and activation effects of transition metal oxyacid salt additives to induce uniform doping of heteroatoms, forming a hierarchical porous carbon structure, providing a large number of active sites for ions, facilitating the uniform deposition of metals, and effectively improving the capacity; at the same time, the metal compound obtained by the reduction of the transition metal oxyacid salt during the carbonization process can induce the uniform nucleation of metal ions on its surface, further improving the capacity. Therefore, when the plant carbon-supported metal compound nanomaterial is used as the negative electrode material of a secondary battery, it exhibits excellent energy storage and fast charging performance.

[0006] To solve the above technical problems, the present invention adopts the following technical solution: A plant carbon-supported metal compound nanocomposite material, the nanocomposite material is uniformly loaded with a metal compound, and the metal compound includes: one or several of titanium carbide, titanium nitride, titanium oxide, titanium sulfide, vanadium oxide, vanadium sulfide, chromium oxide, chromium sulfide, manganese oxide, iron carbide, iron oxide, iron phosphide, iron sulfide, iron chloride, cobalt oxide, cobalt phosphide, cobalt sulfide, nickel nitride, nickel oxide, nickel sulfide, copper oxide, copper sulfide, zinc oxide, zinc sulfide, zinc chloride, and metal compounds of the same group.

[0007] Preferably, the structure of the plant carbon-supported metal compound nanocomposite material is a one-dimensional fiber structure, and the aspect ratio of the material is 100:1 - 10000:1;

[0008] Or, the structure of the plant carbon-supported metal compound nanocomposite material is a two-dimensional structure, and the aspect ratio of the material is 1:1 - 500:1; the thickness range of the material is 0.01 μm - 10 μm, and the aspect ratio of thickness to width is 1:10 - 1:1000;

[0009] Or, the structure of the plant carbon-supported metal compound nanocomposite material is a three-dimensional pipeline structure, and the aspect ratio of the material is 10:1 - 1000:1; the diameter range is 0.1 μm - 10 μm;

[0010] Or, the structure of the plant carbon-supported metal compound nanocomposite material is a three-dimensional spherical porous structure, and the diameter range of the material is 1 μm - 100 μm.

[0011] Preferably, in the plant carbon-supported metal compound nanocomposite, the atomic percentage of nitrogen is 0.1-10 at.%.

[0012] And / or, the atomic percentage of oxygen is 1-15 at.%.

[0013] And / or, the atomic percentage of sulfur is 1-20 at.%.

[0014] And / or, the atomic percentage of phosphorus is 0.1-10 at.%.

[0015] And / or, the atomic percentage of metal is 1-20 at.%.

[0016] Preferably, the pore size range of the plant carbon-supported metal compound nanocomposite is 0.001 μm - 10 μm;

[0017] And / or, the pore volume range is 0.01 cm 3 / g - 1 cm 3 / g;

[0018] And / or, the specific surface area is 5 m 2 / g - 5000 m 2 / g.

[0019] The present invention also protects a preparation method of a plant carbon-supported metal compound nanocomposite, which includes the following steps: impregnating plant substances in a transition metal oxysalt solution, and then successively drying, carbonizing, washing and drying the plant substances to obtain the plant carbon-supported metal compound nanomaterial.

[0020] Preferably, the plant substance precursors include at least one of legume roots, hemp stalks, pollen, laver, poplar catkins, cotton, soybeans, ginkgo leaves, pumpkin seeds, and corn cobs;

[0021] The transition metal oxysalts include at least one of titanium sulfate, manganese sulfate, iron sulfate, cobalt sulfate, nickel sulfate, copper sulfate, zinc sulfate, chromium nitrate, manganese nitrate, iron nitrate, cobalt nitrate, nickel nitrate, copper nitrate, zinc nitrate, copper chlorate, zinc chlorate, vanadium oxalate, and homologous metal oxysalts, etc.;

[0022] Preferably, the concentration range of the transition metal oxysalt impregnation solution is 0.001 g / cm 3 -1 g / cm 3 , the mass ratio range of the plant substance precursor to the transition metal oxysalt is 1:1 - 100:1, and the impregnation time is 3 h - 10 h.

[0023] Preferably, the process conditions for pre-carbonization drying include one or more of normal temperature drying, vacuum drying, heating drying, or freeze drying; more preferably, the process conditions for the freeze drying include: transferring the transition metal oxysalt impregnation solution to a plastic petri dish, placing the petri dish in a freeze dryer, pre-freezing for 12 h, and then freeze-drying for 48 h.

[0024] Preferably, the carbonization process includes: under an argon atmosphere, heating the dried sample at a heating rate of 1 - 20 °C / min to 100 - 250 °C in an inert atmosphere and holding for 0.5 - 2 h; then heating to 600 - 2800 °C at the same heating rate and holding for 1 - 3 h; when the sample temperature cools to room temperature, take out the sample. More preferably, place the dried sample in a porcelain boat. Place the porcelain boat in a tube furnace, under an inert atmosphere, heat to 150 °C at a heating rate of 2.5 °C / min and hold for 30 min; then heat to 600 °C at the same heating rate and hold for 1 h; when the sample temperature cools to room temperature, take out the sample in the porcelain boat.

[0025] And / or, the water washing process includes: placing the carbonized material in water and stirring evenly at a rotation speed of 300 r / min - 500 r / min for 8 - 12 h, then performing suction filtration to obtain a sample for subsequent drying;

[0026] And / or, the temperature of the drying treatment is 60 - 80 °C, and the drying time is 10 - 15 h.

[0027] The present invention also protects the application of the above-mentioned plant carbon-supported metal compound nanocomposite or the plant carbon-supported metal compound nanomaterial prepared by the above method in the negative electrode of a secondary metal / ion battery.

[0028] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0029] 1. The present invention selects natural plants as carbon-based precursors, utilizes the structural advantages of the plants themselves, uses transition metal oxysalts as additives, impregnates the plant bodies in inorganic salts, and the capillary adsorption effect of the plants themselves and the concentration difference effect of the system enable the inorganic salts to be evenly adsorbed in the plant bodies. With the help of the inorganic additives, a confinement support structure is formed, enabling the plant materials to effectively retain the original natural ordered structure during the subsequent freeze-drying and carbonization processes, providing a smooth transmission channel for ions, facilitating the insertion and extraction of ions, and at the same time, the non-carbon element components contained in the plant materials are retained, and the presence of heteroatoms provides additional active sites for the reaction.

[0030] 2. The plant carbon-supported metal compound nanomaterials provided by the present invention select transition metal oxysalts, which also have multiple functions as additives: transition metal oxysalts can effectively introduce heteroatoms such as phosphorus, sulfur, and chlorine as dopants, providing a large number of active sites. At the same time, as a template and activator, it can effectively introduce mesoporous and microporous structures, promoting the formation of a hierarchical porous carbon structure of the material, effectively increasing the specific surface area of the material, and enhancing the capacity.

[0031] 3. The transition metal oxysalts selected for the plant carbon-supported metal compound nanomaterials provided by the present invention can be reduced to form new transition metal compounds during the high-temperature carbonization process. Their outstanding metalophilic properties enable metal ions to preferentially deposit uniformly inside and on the surface of them, effectively inhibiting the possible growth of metal dendrites and providing additional capacity at the same time.

[0032] 4. The technical solution designed by the present invention can realize the regulation of the structure and morphology of carbon materials and the composite with metalophilic materials through one-step impregnation pyrolysis. The operation is simple and efficient, and has strong repeatability. Compared with the traditional step-by-step treatment method, it has obvious operational advantages and can effectively save time cost and economic cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to further illustrate the specific embodiments of the present invention, the following are some drawings for the specific embodiments.

[0034] Figure 1 It is a scanning electron microscope image of the plant carbon-supported metal compound nanomaterials prepared in Example 1 of the present invention.

[0035] Figure 2 、 3 It is an XRD pattern of the plant carbon-supported metal compound nanomaterials prepared in Example 1 of the present invention.

[0036] Figure 4 It is a Raman spectrum of the plant carbon-supported metal compound nanomaterials prepared in Example 1 of the present invention.

[0037] Figure 5 It is a total X-ray photoelectron spectroscopy pattern of the plant carbon-supported metal compound nanomaterials prepared in Example 1 of the present invention.

[0038] Figure 6 It is a high-resolution spectrum of N element of the plant carbon-supported metal compound nanomaterials prepared in Example 1 of the present invention.

[0039] Figure 7 It is a high-resolution spectrum of S element of the plant carbon-supported metal compound nanomaterials prepared in Example 1 of the present invention.

[0040] Figure 8 It is a high-resolution spectrum of Ni element of the plant carbon-supported metal compound nanomaterials prepared in Example 1 of the present invention.

[0041] Figure 9 It is the Coulomb efficiency test chart in a button-type half-cell when the plant carbon-supported metal compound nanomaterial prepared in Example 1 of the present invention is used as a modified material for a sodium metal negative electrode.

[0042] Figure 10 It is the cycle stability test chart in a symmetric cell when the plant carbon-supported metal compound nanomaterial prepared in Example 1 of the present invention is used as a modified material for a sodium metal battery.

[0043] Figure 11 It is the rate performance test chart in a full cell when the plant carbon-supported metal compound nanomaterial prepared in Example 1 of the present invention is used as a modified material for a sodium metal battery.

[0044] Figure 12 It is the cycle performance test chart in a full cell when the plant carbon-supported metal compound nanomaterial prepared in Example 1 of the present invention is used as a modified material for a sodium metal battery. Detailed implementation manners

[0045] The following embodiments are provided to better further understand the present invention. They are not limited to the best implementation manner, and do not constitute a limitation to the content and protection scope of the present invention. Any product that is the same as or similar to the present invention obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with those of other prior arts falls within the protection scope of the present invention.

[0046] For those embodiments in which specific experimental steps or conditions are not indicated, the operations or conditions of the conventional experimental steps described in the literature in this field can be followed. For the reagents or instruments whose manufacturers are not indicated, they are all conventional reagent products that can be obtained through commercial purchase.

[0047] Experimental Example 1:

[0048] A plant carbon-supported metal compound nanomaterial, and its preparation method is as follows:

[0049] Weigh 5.000 g of rape pollen, 0.267 g of nickel sulfate, and 30.000 g of deionized water respectively. First, mix nickel sulfate and deionized water in a beaker to prepare a solution, and then add pollen to the solution and soak for 3 h. Transfer the mixed sample to a plastic petri dish and place it in a freeze dryer for pre-freezing for 12 h and then freeze-drying for 48 h. After taking out the freeze-dried sample, place it in a porcelain boat and then transfer it to a tube furnace. Under an argon atmosphere, heat it to 150 °C at a heating rate of 2.5 °C / min and hold for 30 min; then heat it to 600 °C at the same heating rate and hold for 1 h. When the sample temperature cools to room temperature, take out the sample in the porcelain boat. Transfer the pyrolysis product to a beaker containing 200 ml of deionized water and stir at room temperature for 12 h. Filter the stirred solution by suction, and dry the solid sample obtained by suction filtration in an oven at 80 °C for 10 h to obtain the plant carbon-supported metal compound nanomaterial.

[0050] The scanning electron microscope image of the plant carbon-supported metal compound nanomaterial is as Figure 1 shown. As Figure 1 shown, the pollen carbon material obtained in this application has a regular ellipsoidal morphology; perform XRD and Raman characterizations on the plant carbon-supported metal compound nanomaterial, as Figure 2 and Figure 3 shown. By comparing with the PDF card, it can be seen that the characteristic peaks of NiO and Ni 3 S 2 indicate that during the pyrolysis process, NiSO 4 underwent a redox reaction in situ with the pollen carbon, and NiSO4 was converted into sodiumophilic NiO and Ni 3 S 2 . Perform XPS detection on the plant carbon-supported metal compound nanomaterial to obtain the full X-ray photoelectron spectrum and the high-resolution spectrum of the target element, as Figures 4 to 8 shown. The plant carbon-supported metal compound nanomaterial contains nitrogen, sulfur, oxygen, and nickel atoms. Among them, the percentage of nitrogen atoms is: 2.51 at.%, the percentage of sulfur atoms is: 6.69 at.%, the percentage of oxygen atoms is: 12.7 at.%, and the percentage of nickel atoms is: 5.83 at.%.

[0051] Example 2 (Replace rape pollen with flax)

[0052] Weigh 5.004 g of flax, 0.265 g of nickel sulfate and 30.003 g of deionized water respectively. First, mix nickel sulfate and deionized water in a beaker to prepare a solution, and then add flax to the solution and soak for 3 h. Transfer the mixed sample to a plastic petri dish, put it into a freeze dryer, pre-freeze for 12 h and then freeze-dry for 48 h. Take out the freeze-dried sample, place it in a porcelain boat and then transfer it to a tube furnace. Under an argon atmosphere, heat it to 150 °C at a heating rate of 2.5 °C / min and hold for 30 min; then heat it to 600 °C at the same heating rate and hold for 1 h. When the sample temperature cools to room temperature, take out the sample in the porcelain boat. Transfer the pyrolysis product to a beaker containing 200 ml of deionized water and stir at room temperature for 12 h. Filter the stirred solution by suction, and dry the solid sample obtained by suction filtration in an oven at 80 °C for 10 h to obtain the plant carbon-supported metal compound nanomaterial.

[0053] Example 3 (Replace rape pollen with corncob)

[0054] Weigh 5.003 g of corncob, 0.266 g of nickel sulfate and 30.001 g of deionized water respectively. First, mix nickel sulfate and deionized water in a beaker to prepare a solution, and then add corncob to the solution and soak for 3 h. Transfer the mixed sample to a plastic petri dish, put it into a freeze dryer, pre-freeze for 12 h and then freeze-dry for 48 h. Take out the freeze-dried sample, place it in a porcelain boat and then transfer it to a tube furnace. Under an argon atmosphere, heat it to 150 °C at a heating rate of 2.5 °C / min and hold for 30 min; then heat it to 600 °C at the same heating rate and hold for 1 h. When the sample temperature cools to room temperature, take out the sample in the porcelain boat. Transfer the pyrolysis product to a beaker containing 200 ml of deionized water and stir at room temperature for 12 h. Filter the stirred solution by suction, and dry the solid sample obtained by suction filtration in an oven at 80 °C for 10 h to obtain the plant carbon-supported metal compound nanomaterial.

[0055] Example 4 (Replace rape pollen with soybean root)

[0056] Weigh 5.005 g of sophora flavescens root, 0.269 g of nickel sulfate and 30.004 g of deionized water respectively. First, mix nickel sulfate and deionized water in a beaker to prepare a solution, and then add sophora flavescens root to the solution and impregnate for 3 h. Transfer the mixed sample to a plastic petri dish, put it into a freeze dryer for pre-freezing for 12 h and then freeze-drying for 48 h. After taking out the freeze-dried sample, place it in a porcelain boat and then transfer it to a tubular furnace. Under an argon atmosphere, heat it to 150 °C at a heating rate of 2.5 °C / min and keep it warm for 30 min; then heat it to 600 °C at the same heating rate and keep it warm for 1 h. When the sample temperature cools to room temperature, take out the sample in the porcelain boat. Transfer the pyrolysis product to a beaker containing 200 ml of deionized water and stir at room temperature for 12 h. Filter the stirred solution by suction, and dry the solid sample obtained by suction filtration in an oven at 80 °C for 10 h to obtain the plant carbon-supported metal compound nanomaterial.

[0057] Example 5 (nickel sulfate is replaced by cobalt sulfate)

[0058] Weigh 5.001 g of rape pollen, 0.266 g of cobalt sulfate and 30.001 g of deionized water respectively. First, mix cobalt sulfate and deionized water in a beaker to prepare a solution, and then add pollen to the solution and impregnate for 3 h. Transfer the mixed sample to a plastic petri dish, put it into a freeze dryer for pre-freezing for 12 h and then freeze-drying for 48 h. After taking out the freeze-dried sample, place it in a porcelain boat and then transfer it to a tubular furnace. Under an argon atmosphere, heat it to 150 °C at a heating rate of 2.5 °C / min and keep it warm for 30 min; then heat it to 600 °C at the same heating rate and keep it warm for 1 h. When the sample temperature cools to room temperature, take out the sample in the porcelain boat. Transfer the pyrolysis product to a beaker containing 200 ml of deionized water and stir at room temperature for 12 h. Filter the stirred solution by suction, and dry the solid sample obtained by suction filtration in an oven at 80 °C for 10 h to obtain the plant carbon-supported metal compound nanomaterial.

[0059] Example 6 (the mass ratio of rape pollen to nickel sulfate is adjusted to 5:1)

[0060] Weigh 5.002 g of rape pollen, 1.001 g of nickel sulfate, and 30.002 g of deionized water respectively. First, mix nickel sulfate and deionized water in a beaker to prepare a solution, and then add pollen to the solution and impregnate for 3 h. Transfer the mixed sample to a plastic petri dish and place it in a freeze dryer for pre-freezing for 12 h and then freeze-drying for 48 h. After taking out the freeze-dried sample, place it in a porcelain boat and then transfer it to a tubular furnace. Under an argon atmosphere, heat it to 150 °C at a heating rate of 2.5 °C / min and hold for 30 min; then heat it to 600 °C at the same heating rate and hold for 1 h. When the sample temperature cools to room temperature, take out the sample in the porcelain boat. Transfer the pyrolysis product to a beaker containing 200 ml of deionized water and stir at room temperature for 12 h. Filter the stirred solution by suction, and dry the solid sample obtained by suction filtration in an oven at 80 °C for 10 h to obtain the plant carbon-supported metal compound nanomaterial.

[0061] Example 7 (the concentration of the transition metal oxygen-containing salt solution is adjusted to 0.005 g / cm 3 )

[0062] Weigh 5.002 g of rape pollen, 0.267 g of nickel sulfate, and 53.403 g of deionized water respectively. First, mix nickel sulfate and deionized water in a beaker to prepare a solution, and then add pollen to the solution and impregnate for 3 h. Transfer the mixed sample to a plastic petri dish and place it in a freeze dryer for pre-freezing for 12 h and then freeze-drying for 48 h. After taking out the freeze-dried sample, place it in a porcelain boat and then transfer it to a tubular furnace. Under an argon atmosphere, heat it to 150 °C at a heating rate of 2.5 °C / min and hold for 30 min; then heat it to 600 °C at the same heating rate and hold for 1 h. When the sample temperature cools to room temperature, take out the sample in the porcelain boat. Transfer the pyrolysis product to a beaker containing 200 ml of deionized water and stir at room temperature for 12 h. Filter the stirred solution by suction, and dry the solid sample obtained by suction filtration in an oven at 80 °C for 10 h to obtain the plant carbon-supported metal compound nanomaterial.

[0063] Example 8 (the drying process is adjusted to vacuum drying)

[0064] Weigh 5.006 g of rape pollen, 0.267 g of nickel sulfate and 30.002 g of deionized water respectively. First, mix nickel sulfate and deionized water in a beaker to prepare a solution, and then add pollen to the solution and impregnate for 3 h. Transfer the mixed sample to a glass watch glass and then place it in a vacuum oven, and dry it at 80 °C for 24 h under vacuum. After taking out the dried sample, place it in a porcelain boat and then transfer it to a tubular furnace. Under an argon atmosphere, heat it to 150 °C at a heating rate of 2.5 °C / min and then hold for 30 min; then heat it to 600 °C at the same heating rate and hold for 1 h. When the sample temperature cools to room temperature, take out the sample in the porcelain boat. Transfer the pyrolysis product to a beaker containing 200 ml of deionized water and stir at room temperature for 12 h. Filter the stirred solution by suction, and dry the solid sample obtained by suction filtration in an oven at 80 °C for 10 h to obtain the plant carbon-supported metal compound nanomaterial.

[0065] Example 9 (pre-oxidation temperature adjusted to 250 °C)

[0066] Weigh 5.003 g of rape pollen, 0.265 g of nickel sulfate and 30.001 g of deionized water respectively. First, mix nickel sulfate and deionized water in a beaker to prepare a solution, and then add pollen to the solution and impregnate for 3 h. Transfer the mixed sample to a plastic petri dish and then place it in a freeze dryer for pre-freezing for 12 h and then freeze-drying for 48 h. After taking out the freeze-dried sample, place it in a porcelain boat and then transfer it to a tubular furnace. Under an argon atmosphere, heat it to 250 °C at a heating rate of 2.5 °C / min and then hold for 30 min; then heat it to 600 °C at the same heating rate and hold for 1 h. When the sample temperature cools to room temperature, take out the sample in the porcelain boat. Transfer the pyrolysis product to a beaker containing 200 ml of deionized water and stir at room temperature for 12 h. Filter the stirred solution by suction, and dry the solid sample obtained by suction filtration in an oven at 80 °C for 10 h to obtain the plant carbon-supported metal compound nanomaterial.

[0067] Example 10 (carbonization temperature adjusted to 2000 °C)

[0068] Weigh 5.002 g of rapeseed pollen, 0.268 g of nickel sulfate, and 30.002 g of deionized water respectively. First, mix nickel sulfate and deionized water in a beaker to prepare a solution, and then add pollen to the solution and impregnate for 3 h. Transfer the mixed sample to a plastic petri dish, place it in a freeze dryer, pre-freeze for 12 h, and then freeze-dry for 48 h. After taking out the freeze-dried sample, place it in a porcelain boat and transfer it to a tubular furnace. Under an argon atmosphere, heat it to 150 °C at a heating rate of 2.5 °C / min and hold for 30 min; then heat it to 2000 °C at the same heating rate and hold for 1 h. When the sample temperature cools to room temperature, take out the sample in the porcelain boat. Transfer the pyrolysis product to a beaker containing 200 ml of deionized water and stir at room temperature for 12 h. Filter the stirred solution by suction, and dry the solid sample obtained by suction filtration in an oven at 80 °C for 10 h to obtain the plant carbon-supported metal compound nanomaterial.

[0069] Example 11 (holding time adjusted to 3 h)

[0070] Weigh 5.007 g of rapeseed pollen, 0.269 g of nickel sulfate, and 30.001 g of deionized water respectively. First, mix nickel sulfate and deionized water in a beaker to prepare a solution, and then add pollen to the solution and impregnate for 3 h. Transfer the mixed sample to a plastic petri dish, place it in a freeze dryer, pre-freeze for 12 h, and then freeze-dry for 48 h. After taking out the freeze-dried sample, place it in a porcelain boat and transfer it to a tubular furnace. Under an argon atmosphere, heat it to 150 °C at a heating rate of 2.5 °C / min and hold for 30 min; then heat it to 600 °C at the same heating rate and hold for 3 h. When the sample temperature cools to room temperature, take out the sample in the porcelain boat. Transfer the pyrolysis product to a beaker containing 200 ml of deionized water and stir at room temperature for 12 h. Filter the stirred solution by suction, and dry the solid sample obtained by suction filtration in an oven at 80 °C for 10 h to obtain the plant carbon-supported metal compound nanomaterial.

[0071] Example 12 (impregnation time adjusted to 6 h)

[0072] Weigh 5.000 g of rapeseed pollen, 0.267 g of nickel sulfate and 30.005 g of deionized water respectively. First, mix nickel sulfate and deionized water in a beaker to prepare a solution, and then add pollen to the solution and impregnate for 6 h. Transfer the mixed sample to a plastic petri dish and place it in a freeze dryer for pre-freezing for 12 h and then freeze-drying for 48 h. After taking out the freeze-dried sample, place it in a porcelain boat and then transfer it to a tube furnace. Under an argon atmosphere, heat it to 150 °C at a heating rate of 2.5 °C / min and then hold for 30 min; then heat it to 600 °C at the same heating rate and hold for 1 h. When the sample temperature cools to room temperature, take out the sample in the porcelain boat. Transfer the pyrolysis product to a beaker containing 200 ml of deionized water and stir at room temperature for 12 h. Filter the stirred solution by suction, and dry the solid sample obtained by suction filtration in an oven at 80 °C for 10 h to obtain the plant carbon-supported metal compound nanomaterial.

[0073] Comparative Example 1 (using pure plants, without metal salt treatment)

[0074] Weigh 5.000 g of rapeseed pollen and 30.002 g of deionized water and mix them in a beaker. Transfer the mixed sample to a plastic petri dish and place it in a freeze dryer for pre-freezing for 12 h and then freeze-drying for 48 h. After taking out the freeze-dried sample, place it in a porcelain boat and then transfer it to a tube furnace. Under an argon atmosphere, heat it to 150 °C at a heating rate of 2.5 °C / min and then hold for 30 min; then heat it to 600 °C at the same heating rate and hold for 1 h. When the sample temperature cools to room temperature, take out the sample in the porcelain boat. Transfer the pyrolysis product to a beaker containing 200 ml of deionized water and stir at room temperature for 12 h. Filter the stirred solution by suction, and dry the solid sample obtained by suction filtration in an oven at 80 °C for 10 h to obtain the plant carbon material.

[0075] Perform SEM and TEM tests on the plant carbon-supported metal compound nanocomposites prepared in Examples 1 to 12 and the plant carbon material in Comparative Example 1. The experimental results are shown in Table 1:

[0076] Table 1 SEM and TEM characterization test results

[0077]

[0078]

[0079] Perform BET tests on the plant carbon-supported metal compound nanomaterials prepared in Examples 1 - 12 and the plant carbon material in Comparative Example 1. The experimental results are shown in Table 2:

[0080] Table 2 BET test results

[0081]

[0082]

[0083] The XPS spectra of the plant carbon-supported metal compound nanomaterials prepared in Examples 1-12 were analyzed to obtain the atomic percentages of heteroatoms. The experimental results are shown in Table 3.

[0084] Table 3 Results of XPS spectra analysis

[0085]

[0086]

[0087]

[0088] The plant-based plant carbon-supported metal compound nanomaterials of Examples 1-12 and the plant carbon material of Comparative Example 1 were mixed with a conductive agent and a binder at a mass ratio of 8:1:1. The conductive agent was acetylene black, and the binder was PVDF (polyvinylidene fluoride). NMP (N-methylpyrrolidone) was used as the solvent, and it was ground evenly in a mortar and then coated on a copper foil with a diameter of 14 mm and dried in a vacuum oven at 120 °C for 24 h to prepare electrode sheets under different treatment conditions.

[0089] Using the treated sodium sheet with a diameter of 12 mm as the negative electrode and the plant carbon-supported metal compound nanomaterial obtained in Example 1 as the positive electrode to assemble a button-type sodium metal half-cell, and its Coulomb efficiency was tested. The test diagram is as Figure 9 shown. Two identical half-cells with the electrode material obtained in Example 1 were taken. After depositing the same capacity of sodium, the battery was disassembled and the electrode sheets were taken out. These two electrode sheets were assembled into a symmetric cell to test the cycle stability. The test diagram is as Figure 10 shown. Two identical half-cells with the electrode material obtained in Example 1 were taken. After 3 charge-discharge pre-sodiation, it was discharged to 0.01 V and then taken out. The battery was disassembled and the electrode sheet was taken out as the negative electrode of the full cell. Using NVP as the positive electrode, the full cell was assembled to test the rate performance and cycle performance. The test diagram is as Figures 11 to 12 shown.

[0090] The rate and long cycle tests were carried out on the prepared sodium metal full cell. The voltage window was selected as 2.6 - 3.8 V. The rate test current densities were successively selected as: 0.2C, 0.5C, 1C, 2C, 5C. The long cycle test current density was selected as 1C. The test results are shown in Table 4.

[0091] The electrodes prepared from the plant-based plant carbon-supported metal compound nanomaterials of Examples 2-12 and the plant carbon material of Comparative Example 1 were assembled with sodium sheets into button-type sodium metal half-cells, and the test conditions were the same as above.

[0092] Comparative Example 2: A pure copper foil with a diameter of 14 mm was used as the electrode, and it was assembled with a sodium sheet into a button-type sodium metal half-cell for testing. The testing conditions were the same as those above.

[0093] Table 4 Rate and long cycle test results of button-type sodium metal full cells

[0094]

[0095] It can be seen that when the plant carbon-supported metal compound nanomaterials prepared in Examples 1-12 were used to modify the sodium metal negative electrode, the specific capacity of the battery was 90-130 mAh g at a current density of 0.2 C -1 , and when it increased to 5 C, the specific capacity was still 35-80 mAh g -1 , showing good rate performance. After 50 cycles of activation in the long cycle test, the specific capacity could reach 85-130 mAh g -1 , with excellent performance, and the performance was significantly better than that of the pure plant carbon material in Comparative Example 1 and the pure copper foil in Comparative Example 2.

[0096] When the plant carbon-supported metal compound nanomaterials prepared in Examples 1-12 were used as the modification materials for sodium metal batteries, the Coulomb efficiency was tested in a button-type half-cell under the test conditions of 1 mA cm -2 , 0.5 mAh cm -2 ; An electrode with 3 mAhcm -2 sodium deposited was assembled as the electrode of a symmetric cell, and the charge-discharge performance was tested under the test conditions of 1 mA cm -2 , 0.5 mAh cm -2 . The results are shown in Table 5.

[0097] Table 5 Test results of sodium deposition and stripping tests

[0098]

[0099]

[0100] Obviously, from the above results, it can be seen that the plant-based plant carbon-supported metal compound nanomaterials in Examples 1-12 could still maintain a Coulomb efficiency of 93.5-99.9% after 320 cycles under the conditions of 1 mA cm -2 , 0.5 mAh cm -2 . When this material was assembled into a symmetric cell, the voltage could still remain stable after 120 h of cycling, with good long cycle performance, and the performance was significantly better than that of the pure plant carbon material in Comparative Example 1 and the pure copper foil in Comparative Example 2.

[0101] The plant-based carbon-supported metal compound nanomaterials of Examples 1-12 were mixed with a conductive agent and a binder at a mass ratio of 8:1:1. The conductive agent was acetylene black, and the binder was PVDF (polyvinylidene fluoride). NMP (N-methylpyrrolidone) was used as the solvent, and it was ground evenly with a mortar and then coated on a copper foil with a diameter of 14 mm and dried in a vacuum oven at 120 °C for 24 h, thus preparing electrode sheets under different treatment conditions.

[0102] A button-type lithium metal half-cell was assembled with the treated lithium sheet with a diameter of 14 mm as the negative electrode and the carbon-supported metal compound nanomaterial obtained in Example 1 as the positive electrode to test its Coulombic efficiency. Two identical half-cells with the electrode material obtained in Example 1 were taken. After depositing the same capacity of lithium, the battery was disassembled and the electrode sheets were taken out. These two electrode sheets were assembled into a symmetric battery to test the cycle stability. Two identical half-cells with the electrode material obtained in Example 1 were taken. After 3 charge-discharge prelithiation, it was discharged to 0.01 V and then taken out. The battery was disassembled and the electrode sheet was taken out as the negative electrode of the full cell. Lithium iron phosphate was used as the positive electrode to assemble the full cell to test the rate performance and cycle performance.

[0103] The prepared sodium metal full cell was subjected to rate and long cycle tests. The voltage window was selected as 2.7 - 4.2 V. The current densities for the rate tests were successively selected as: 0.2C, 0.5C, 1C, 2C, 5C, 10C, 20C. The current density for the long cycle test was selected as 1C. The test results are shown in Table 6.

[0104] Table 6 Rate and long cycle test results of button-type lithium metal full cell

[0105]

[0106]

[0107] It can be seen that when the carbon-supported metal compound nanomaterials prepared in Examples 1-12 were used to modify the lithium metal negative electrode, the specific capacity of the battery was 100 - 145 mAh g at a current density of 0.2C -1 , and when it increased to 20C, the specific capacity was still 20 - 35 mAh g -1 , showing good rate performance. And after 50 cycles of activation in the long cycle test, the specific capacity could reach 90 - 135 mAh g -1 , with excellent performance, which was significantly better than the pure plant carbon material of Comparative Example 1 and the pure copper foil of Comparative Example 2.

[0108] When the carbon-supported metal compound nanomaterials prepared in Examples 1-12 were used as the modification materials for lithium metal batteries, at 1 mA cm -2 , 0.5 mAh cm -2The Coulomb efficiency was tested in a button-type half-cell under the test conditions; the electrode with 3 mAh cm of deposited lithium was assembled as the electrode of a symmetric cell, and the symmetric cell was tested for charge-discharge performance detection under the test conditions of 1 mA cm and 0.5 mAh cm. The results are shown in Table 7. -2 The electrode with deposited lithium was assembled as the electrode of a symmetric cell, and the symmetric cell was tested for charge-discharge performance detection under the test conditions of 1 mA cm -2 and 0.5 mAh cm -2 The results are shown in Table 7.

[0109] Table 7 Test results of lithium deposition and stripping

[0110]

[0111]

[0112] It can be clearly seen from the above results that the Coulomb efficiency can still be maintained at 94.7 - 99.9% after 320 cycles under the conditions of 1 mA cm -2 and 0.5 mAh cm -2 When the material is assembled into a symmetric cell, the voltage can still remain stable after 120 h of cycling, and the long-cycle performance is good, and the performance is significantly better than that of the pure plant carbon material in Comparative Example 1 and the pure copper foil in Comparative Example 2.

[0113] The plant-based plant carbon-supported metal compound nanomaterials of Examples 1 - 12 were mixed with a conductive agent and a binder in a mass ratio of 8:1:1. The conductive agent was acetylene black, and the binder was PVDF (polyvinylidene fluoride). NMP (N-methylpyrrolidone) was used as the solvent, and it was ground evenly with a mortar and then coated on a copper foil with a diameter of 14 mm and dried in a vacuum oven at 120 °C for 24 h to prepare electrode sheets under different treatment conditions.

[0114] A button-type lithium metal half-cell was assembled with a treated zinc sheet with a diameter of 10 mm as the negative electrode and the plant carbon-supported metal compound nanomaterial obtained in Example 1 as the positive electrode to test its Coulomb efficiency. Two identical half-cells with the electrode material obtained in Example 1 were taken, and after depositing the same capacity of zinc, the battery was disassembled and the electrode sheets were taken out. These two electrode sheets were assembled into a symmetric cell to test the cycle stability. Two identical half-cells with the electrode material obtained in Example 1 were taken. After 3 times of charge-discharge pre-zincification, it was discharged to 0.01 V and then taken out. The battery was disassembled and the electrode sheet was taken out as the negative electrode of the full cell, and manganese dioxide was used as the positive electrode to assemble the full cell to test the rate performance and cycle performance.

[0115] The prepared zinc metal full cell was tested for rate and long cycle. The voltage window was selected as 1.0 - 3.9 V, and the current densities for rate testing were sequentially selected as: 0.2C, 0.5C, 1C, 2C, 5C. The current density for long cycle testing was selected as 1C. The test results are shown in Table 8.

[0116] Table 8 Rate and long cycle test results of button-type zinc metal full battery

[0117]

[0118]

[0119] It can be seen that when the lithium metal anode is modified with the plant carbon-supported metal compound nanomaterials prepared in Examples 1-12, the specific capacity of the battery is 170-195 mAh g at a current density of 0.2 C -1 , and when it increases to 5 C, the specific capacity is still 115-155 mAh g -1 , showing good rate performance. After 50 cycles of activation in the long cycle test, the specific capacity can reach 160-185 mAh g -1 , with excellent performance, significantly better than the pure plant carbon material of Comparative Example 1 and the pure copper foil of Comparative Example 2

[0120] When the plant carbon-supported metal compound nanomaterials prepared in Examples 1-12 are used as the modification material for zinc metal batteries, the Coulomb efficiency is tested in a button-type half cell under the test conditions of 1 mA cm -2 , 0.5 mAh cm -2 ; the electrode with 3 mAh cm -2 of deposited zinc is used as the electrode of the symmetric battery to assemble the symmetric battery, and the charge-discharge performance is tested under the test conditions of 1 mA cm -2 , 0.5 mAh cm -2 . The results are shown in Table 9

[0121] Table 9 Test results of zinc deposition and stripping test

[0122] Coulomb efficiency % after 320 cycles Voltage after 120 h of cycling Example 1 99.5 Remain stable Example 2 99.8 Remain stable Example 3 99.7 Remain stable Example 4 97.6 Remain stable Example 5 99.2 Remain stable Example 6 93.2 Remain stable Example 7 99.6 Remain stable Example 8 91.5 Remain stable Example 9 98.8 Remain stable Example 10 95.2 Remain stable Example 11 99.5 Remain stable Example 12 99.0 Remain stable Comparative Example 1 51.8 Vibrate violently Comparative Example 2 17.7 Exceed the range, test stopped

[0123] It can be clearly seen from the above results that the Coulomb efficiency can still be maintained at 91.5-99.8% after 320 cycles under the conditions of 1 mA cm -2 , 0.5 mAh cm -2 . When the material is assembled into a symmetric battery, the voltage can still remain stable after 120 h of cycling, with good long cycle performance, significantly better than the pure plant carbon material of Comparative Example 1 and the pure copper foil of Comparative Example 2

[0124] Compared with the reported electrode materials at present, the materials prepared by this method show more excellent energy storage and fast charging performance

[0125] Obviously, the above embodiments are merely examples given for clear illustration and not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all the implementation manners here. And the obvious changes or modifications derived therefrom still fall within the protection scope of the present invention.

Claims

1. A plant carbon-supported metal compound nanocomposite, characterized in that The nano-composite material is uniformly loaded with a metal compound, and the metal compound includes: one or more of titanium carbide, titanium nitride, titanium oxide, titanium sulfide, vanadium oxide, vanadium sulfide, chromium oxide, chromium sulfide, manganese oxide, iron carbide, iron oxide, iron phosphide, iron sulfide, iron chloride, cobalt oxide, cobalt phosphide, cobalt sulfide, nickel nitride, nickel oxide, nickel sulfide, copper oxide, copper sulfide, zinc oxide, zinc sulfide, zinc chloride and metal compounds of the same group; in the plant carbon-supported metal compound nano-composite material, the atomic percentage of nitrogen is 0.1-10 at.%, the atomic percentage of oxygen is 1-15 at.%, the atomic percentage of sulfur is 1-20 at.%, the atomic percentage of phosphorus is 0.1-10 at.%, and the atomic percentage of metal is 1-20 at.%; the pore size range of the plant carbon-supported metal compound nano-composite material is 0.001 μm-10 μm, and the pore volume range is 0.01 cm 3 / g-1 cm 3 / g, and the specific surface area is 5 m 2 / g-5000 m 2 / g; its preparation method includes the following steps: the plant material is impregnated in a transition metal oxysalt solution, and then the plant material is successively dried, carbonized, washed with water and dried to obtain the plant carbon-supported metal compound nanomaterial; the precursor of the plant material includes at least one of legume roots, hemp stalks, pollen, laver, poplar catkins, cotton, soybeans, ginkgo leaves, pumpkin seeds, and corn cobs; the transition metal oxysalts include at least one of titanium sulfate, manganese sulfate, iron sulfate, cobalt sulfate, nickel sulfate, copper sulfate, zinc sulfate, chromium nitrate, manganese nitrate, iron nitrate, cobalt nitrate, nickel nitrate, copper nitrate, zinc nitrate, copper chlorate, zinc chlorate, vanadium oxalate and homologous metal oxysalts; The concentration range of the transition metal oxyacid salt impregnation solution is from 0.001 g / cm 3 -1 g / cm 3 , the mass ratio of the plant-derived precursor to the transition metal oxyacid salt ranges from 1:1 to 100:1, and the impregnation time is 3 h - 10 h; the carbonization process includes: heating the dried sample in an argon atmosphere at a heating rate of 1-20 °C / min to 100-250 °C in an inert atmosphere and holding for 0.5-2 h; then heating to 600-2800 °C at the same heating rate and holding for 1-3 h; when the sample temperature cools to room temperature, take out the sample; the structure of the plant carbon-supported metal compound nanocomposite is a one-dimensional fiber structure, and the aspect ratio of the material is 100:1-10000:1; or, the structure of the plant carbon-supported metal compound nanocomposite is a two-dimensional structure, and the aspect ratio of the material is 1:1-500:1; the thickness range of the material is 0.01 μm-10 μm, and the thickness-to-width ratio is 1:10-1:1000; or, the structure of the plant carbon-supported metal compound nanocomposite is a three-dimensional pipe structure, and the aspect ratio of the material is 10:1-1000:1; the diameter range is 0.1 μm-10 μm; or, the structure of the plant carbon-supported metal compound nanocomposite is a three-dimensional spherical porous structure, and the diameter range of the material is 1 μm-100 μm.

2. The nanocomposite according to claim 1, characterized in that the process conditions for drying before carbonization include one or more of normal temperature drying, vacuum drying, heating drying or freeze drying.

3. The nanocomposite according to claim 2, characterized in that the process conditions for freeze drying include: transferring the transition metal oxysalt impregnation solution to a plastic petri dish, placing the petri dish in a freeze dryer, pre-freezing for 12 h and then freeze drying for 48 h.

4. The nanocomposite according to claim 1, characterized in that the carbonization process includes: placing the dried sample in a porcelain boat, placing the porcelain boat in a tube furnace, heating to 150 °C at a heating rate of 2.5 °C / min in an inert atmosphere and holding for 30 min; then heating to 600 °C at the same heating rate and holding for 1 h; when the sample temperature cools to room temperature, take out the sample in the porcelain boat.

5. The nanocomposite according to claim 1, characterized in that the water washing process includes: placing the carbonized material in water and stirring evenly at a speed of 300 r / min-500 r / min for 8-12 h, then performing suction filtration to obtain a sample for subsequent drying; and / or, the temperature of the drying treatment is 60-80 °C, and the drying time is 10-15 h.

6. Use of the nanocomposite material according to any one of claims 1-5 in the negative electrode of a secondary metal / ion battery.

Images