Sodium-ion battery anode composite material and preparation method and application thereof

Abstract

The invention relates to a sodium ion battery anode composite material, the composite material comprises a biomass hard carbon material and a Bi-Sb-A ternary alloy material loaded on the hard carbon material, the structure of the ternary alloy material is represented by a general formula BixSbyAz, x: y: z = (0.1-1.5): 1: 1, the structure of the ternary alloy material is a Bi-Sb-A alloy phase or a split-phase mixture of a Bi-Sb phase, a Sb-A phase and a Bi phase, wherein the split-phase mixture is of a uniform microscopic dispersion structure. Wherein the A element is selected from at least one of tin (Sn), germanium (Ge) and lead (Pb). The ternary alloy material has a unique layered structure and wide interlayer spacing, so that rapid charge transfer is promoted, and the rate capability of the material is remarkably improved; in the charging and discharging process of the ternary alloy material, reversible alloying reaction is carried out on the ternary alloy material and sodium ions, and excellent gram capacity exertion is contributed.

Description

Technical Field

[0001] The present invention relates to the technical field of sodium ion batteries, and in particular to a sodium ion battery anode composite material, a preparation method thereof, and applications thereof. Background Art

[0002] Due to the increasingly serious environmental problems and energy crisis, there is an urgent need to develop renewable and sustainable energy sources such as wind and solar energy. In order to solve these intermittent energy conversion problems, the development of large-scale energy storage systems is crucial. Sodium-ion batteries are considered to be the most promising alternative to lithium-ion batteries for large-scale energy storage system applications due to their low cost and natural abundance of sodium resources, as well as a similar rocking-chair working mechanism. In the past decade, significant progress has been made in the practical application of sodium-ion battery cathodes, including polyanionic compounds, layered oxides, and Prussian analogs. On the anode side, various materials, such as carbonaceous materials, alloy metals, metal chalcogenides, etc., have been widely explored. However, due to their complex preparation processes and inherent electrochemical defects, most candidate materials exhibit serious defects in large-scale applications.

[0003] Carbonaceous materials are considered the most promising anode materials. This is because they are low-cost, easy to prepare, and have good reproducibility. Unlike the successful application of graphite in traditional lithium-ion batteries, the narrow carbon interlayer spacing (0.335nm) and thermodynamic instability of graphite intercalation compounds hinder the insertion of sodium ions. It is currently recognized that graphite cannot be directly used as an anode material for sodium-ion batteries. Hard carbon is composed of interlaced graphite microcrystalline layers, rich in micropores and defects. It has a relatively large interlayer spacing, can store a large amount of sodium ions, and has a large reversible capacity. However, when hard carbon is subjected to excessive pressure during roller pressing, the hard carbon particles will break, the specific surface area will increase, and the new interface with oxygen-containing substances will generate oxygen-containing functional groups, resulting in a decrease in the material's coulombic efficiency. Given the ever-increasing demands on batteries, in order to meet the requirements of full batteries in practical applications, there is an urgent need for sodium-ion battery anode composite materials with high structural stability and high reversible capacity. Summary of the Invention

[0004] In view of this, the present invention provides a sodium ion battery anode composite material and a preparation method and application thereof to solve at least one problem existing in the background technology.

[0005] In the first aspect, the present invention provides a sodium ion battery anode composite material, the composite material comprising a biomass hard carbon material and a Bi-Sb-A ternary alloy material supported on the biomass hard carbon material, the structure of the ternary alloy material is represented by the general formula Bi x Sb y A zIndicates that x:y:z = (0.1 to 1.5): 1:1; the structure of the ternary alloy material is a Bi-Sb-A alloy phase or a phase-separated mixture of a Bi-Sb phase, a Sb-A phase, and a Bi phase with a uniform microscopic dispersion structure; wherein the A element is selected from at least one of tin (Sn), germanium (Ge), and lead (Pb).

[0006] In conjunction with the first aspect of the present invention, in an optional embodiment, the composite material satisfies at least one of the following characteristics (1) to (6):

[0007] (1) The particle size of the ternary alloy material is 10 to 100 nm;

[0008] (2) The mass of the ternary alloy material accounts for 10 to 40% of the total mass of the composite material;

[0009] (3) The ternary alloy material has a layered structure;

[0010] (4) The composite material has a fibrous structure;

[0011] (5) The structure of the ternary alloy material is Bi x Sb y Sn z ;

[0012] (6) The x:y:z=(0.5-1.0):1:1.

[0013] In combination with the first aspect of the present invention, in an optional embodiment, doping elements are also distributed in the composite material; the doping elements include boron (B) element and nitrogen (N) element; the atomic proportion of boron (B) element in the composite material is 1 to 5%; the atomic proportion of nitrogen (N) element in the composite material is 1 to 5%.

[0014] In a second aspect, the present invention provides a method for preparing a sodium ion battery anode composite material, comprising the following steps:

[0015] S1: adding the biomass material to deionized water, and then adding a strong oxidant to obtain a mixed solution B, and performing a carboxylation reaction to obtain a modified biomass material;

[0016] S2: adding a bismuth (Bi) source, an antimony (Sb) source, and a source A to deionized water and mixing them to obtain a mixed solution C; immersing the modified biomass material prepared in step S1 in the mixed solution C and mixing them to obtain a mixture; freezing and drying the mixture to obtain a ternary metal salt modified biomass precursor; wherein the source A is selected from at least one of a tin (Sn) source, a germanium (Ge) source, and a lead (Pb) source;

[0017] S3: subjecting the ternary metal salt-modified biomass precursor prepared in step S2 to a first heat treatment to obtain a ternary alloyed hard carbon-based composite intermediate;

[0018] S4: mixing a boron source and a nitrogen source to obtain a N and B source mixture, and subjecting the ternary alloyed hard carbon-based composite intermediate prepared in step S3 and the N and B source mixture to a second heat treatment to obtain the sodium ion battery anode composite material.

[0019] In conjunction with the second aspect of the present invention, in an optional embodiment, step S1 satisfies at least one of the following features (1) to (6):

[0020] (1) The biomass material comprises one or more of cellulose, bamboo, coconut shell, macadamia shell, walnut shell, pine nut shell, peanut shell, rice straw, cotton stalk skin, sugarcane bagasse, reed, reed bamboo, straw, walnut shell, coconut shell or lignin;

[0021] (2) The solid-liquid ratio of the biomass material to the deionized water is 1 g: (10-30) mL;

[0022] (3) The strong oxidant is selected from one or more of ammonium persulfate, potassium persulfate, sodium persulfate, sodium hypochlorite, potassium permanganate and potassium dichromate;

[0023] (4) In the mixed solution B, the concentration of the strong oxidant is 0.1 to 0.5 mol / L;

[0024] (5) The carboxylation reaction time is 12 to 24 hours;

[0025] (6) After the carboxylation reaction is completed, a post-treatment step is further included; the post-treatment step includes: washing and drying; the drying temperature is 60 to 120° C. and the drying time is 8 to 18 hours.

[0026] In conjunction with the second aspect of the present invention, in an optional embodiment, step S2 satisfies at least one of the following features (1) to (7):

[0027] (1) The bismuth (Bi) source is selected from one or more of bismuth chloride, bismuth nitrate pentahydrate, bismuth acetate and bismuth subnitrate;

[0028] (2) The antimony (Sb) source is selected from one or more of antimony trichloride, antimony pentachloride, antimony bromide and antimony tartrate;

[0029] (3) The source A is selected from a tin (Sn) source; the source of tin (Sn) is selected from one or more of tin chloride, tin oxalate, tin sulfate and stannous sulfate;

[0030] (4) The molar concentration ratio of the bismuth (Bi) source, the antimony (Sb) source, and the A source is (0.1-1.5):1:1;

[0031] (5) The solid-liquid ratio of the modified biomass material to the mixed solution C is 1 g: (5-20) mL;

[0032] (6) The freezing includes liquid nitrogen freezing, and the liquid nitrogen freezing time is 1 to 2 hours;

[0033] (7) The drying includes freeze drying, and the freeze drying temperature is -40 to -60°C and the time is 24 to 48 hours.

[0034] In conjunction with the second aspect of the present invention, in an optional embodiment, step S3 satisfies at least one of the following features (1) to (3):

[0035] (1) The first heat treatment is performed in an inert gas atmosphere with a flow rate of 40 to 80 mL / min; the inert gas includes one or more of nitrogen, argon, and helium;

[0036] (2) The temperature of the first heat treatment is 600-900°C, the time is 2-4 hours, and the heating rate is 2-5°C / min;

[0037] (3) After the first heat treatment, a post-treatment step is also included; the post-treatment step includes: grinding, screening, washing, and drying; the particle size of the screened particles is 5 to 10 μm; the drying temperature is 60 to 120° C., and the drying time is 12 to 24 hours.

[0038] In conjunction with the second aspect of the present invention, in an optional embodiment, step S4 satisfies at least one of the following features (1) to (7):

[0039] (1) The boron source is selected from one or more of borax (Na2B4O7), boron oxide (B2O3) and boric acid;

[0040] (2) The nitrogen source is selected from one or more of melamine, urea, ammonium chloride and trinitrophenol;

[0041] (3) The molar ratio of the boron source to the nitrogen source is 1:(1-5);

[0042] (4) The mass ratio of the ternary alloyed hard carbon-based composite intermediate to the N and B source mixture is (1 to 5):1;

[0043] (5) The second heat treatment is carried out in an inert gas atmosphere with a flow rate of 40 to 80 mL / min; the inert gas includes one or more of nitrogen, argon, and helium;

[0044] (6) The temperature of the second heat treatment is 800-1000°C, the time is 2-5 hours, and the heating rate is 2-5°C / min;

[0045] (7) After the second heat treatment, a post-treatment step is further included; the post-treatment step includes: washing and drying; the drying temperature is 60 to 120° C. and the drying time is 12 to 24 hours.

[0046] In a third aspect, the present invention provides an anode pole piece, comprising the sodium ion battery anode composite material as described in any one of the first aspects or the sodium ion battery anode composite material prepared by the preparation method as described in any one of the second aspects.

[0047] In a fourth aspect, the present invention provides a sodium ion battery, comprising the anode electrode sheet as described in the third aspect.

[0048] Compared with the prior art, the present invention has the following beneficial effects:

[0049] First, Sn, Sb, and Bi have excellent ion diffusion rates. Nanoscale particles are obtained through design, which effectively shortens the sodium ion transmission path and accelerates ion transmission. At the same time, the ternary alloy material has a unique layered structure and wide interlayer spacing, which promotes rapid charge transfer and significantly improves the material's rate performance. During the charge and discharge process, the ternary alloy material undergoes a reversible alloying reaction with sodium ions, contributing to excellent specific capacity performance.

[0050] Second, through dual doping of N / B elements, the hardness of hard carbon materials is improved, which effectively alleviates the volume expansion problem of alloy materials during the cycle process, improves the overall structural stability of the material, extends the cycle life of the electrode material, and enhances the ion transfer kinetics.

[0051] Third, the dual-element doping and ternary alloy have a synergistic effect, giving the composite material high ionic conductivity. Combined with good mechanical properties and fibrous structure, it effectively shortens the transmission distance during ion / electron transmission, thereby ensuring that the battery has excellent cycle stability and overall electrochemical performance, providing high capacity and high conductivity, excellent rate performance and cycle stability.

[0052] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0054] Figure 1 This is a transmission electron microscope (TEM) image of the sodium ion battery anode composite material of Example 1 of the present invention;

[0055] Figure 2 This is a high-magnification transmission electron microscope (HRTEM) image of the sodium-ion battery anode composite material of Example 1 of the present invention.

[0056] Figure 3 This is an energy dispersive spectroscopy (EDS) diagram of the sodium ion battery anode composite material of Example 1 of the present invention. DETAILED DESCRIPTION

[0057] To make the technical solutions and beneficial effects of the present invention more clearly understood, the following detailed description is given by way of specific embodiments. It should be understood that these embodiments are intended only to illustrate the present invention and are not intended to limit the scope of the present invention. Any product identical or similar to the present invention that is derived by anyone under the guidance of the present invention or by combining the features of the present invention with those of other prior arts shall fall within the scope of protection of the present invention.

[0058] In the following description, numerous specific details are provided to provide a more thorough understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention can be practiced without one or more of these details. In other instances, certain technical features known in the art are not described to avoid confusion with the present invention; that is, not all features of actual embodiments are described herein, nor are well-known functions and steps described in detail.

[0059] The purpose of the terms used herein is only to describe specific embodiments and is not intended to limit the present invention. When used herein, the singular forms "a", "an", and "the" are intended to include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "comprising" and / or "comprising", when used in this specification, determine the presence of the features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups. When used herein, the term "and / or" includes any and all combinations of the relevant listed items.

[0060] In order to fully understand the present invention, detailed steps and detailed structures will be presented in the following description to illustrate the technical solution of the present invention. Preferred embodiments of the present invention are described in detail below, but in addition to these detailed descriptions, the present invention may also have other implementations.

[0061] Unless otherwise defined, technical and scientific terms used herein have the same meanings as those in the art to which this invention belongs.

[0062] In the following examples, if no specific techniques or conditions are specified, the methods are generally carried out according to conventional techniques or conditions described in the literature in the field, or according to the product instructions and the conditions recommended by the manufacturer. The numerical ranges in the following examples are all inclusive.

[0063] [Sodium-ion battery anode composite materials]

[0064] In the first aspect, the present invention provides a sodium ion battery anode composite material, wherein the composite material comprises a biomass hard carbon material and a Bi-Sb-A ternary alloy material supported on the hard carbon material, wherein the structure of the ternary alloy material is represented by the general formula Bi x Sb y A z Indicates that x:y:z = (0.1 to 1.5): 1:1; the structure of the ternary alloy material is a Bi-Sb-A alloy phase or a phase-separated mixture of a Bi-Sb phase, a Sb-A phase, and a Bi phase with a uniform microscopic dispersion structure; wherein the A element is selected from at least one of tin (Sn), germanium (Ge), and lead (Pb).

[0065] In certain embodiments, the particle size of the ternary alloy material is 10-100 nm.

[0066] In certain embodiments, the mass of the ternary alloy material accounts for 10-40% of the total mass of the composite material.

[0067] In certain embodiments, the ternary alloy material is a layered structure.

[0068] In certain embodiments, the interlayer spacing of the Bi-Sb phase is 0.2-0.5 nm.

[0069] In certain embodiments, the interlayer spacing of the Bi phase is 0.2 to 0.6 nm.

[0070] In certain embodiments, the composite material is a fibrous structure.

[0071] In certain embodiments, the structure of the ternary alloy material is Bi x Sb y Sn z .

[0072] In certain embodiments, the interlayer spacing of the Sb-Sn phase is 0.1 to 0.4 nm.

[0073] In certain embodiments, the x:y:z = (0.5-1.0):1:1, such as 0.5:1:1, 0.6:1:1, 0.7:1:1, 0.8:1:1, 0.9:1:1 or 1.0:1:1, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0074] In some embodiments, doping elements are further distributed in the composite material; the doping elements include boron (B) element and nitrogen (N) element; the atomic proportion of boron (B) element in the composite material is 1 to 5%; the atomic proportion of nitrogen (N) element in the composite material is 1 to 5%.

[0075] [Preparation method of sodium ion battery anode composite material]

[0076] In a second aspect, the present invention provides a method for preparing a sodium ion battery anode composite material, comprising the following steps:

[0077] S1: adding the biomass material to deionized water, and then adding a strong oxidant to obtain a mixed solution B, and performing a carboxylation reaction to obtain a modified biomass material;

[0078] S2: adding a bismuth (Bi) source, an antimony (Sb) source, and a source A to deionized water and mixing them to obtain a mixed solution C; immersing the modified biomass material prepared in step S1 in the mixed solution C and mixing them to obtain a mixture; freezing and drying the mixture to obtain a ternary metal salt modified biomass precursor; wherein the source A is selected from at least one of a tin (Sn) source, a germanium (Ge) source, and a lead (Pb) source;

[0079] S3: subjecting the ternary metal salt-modified biomass precursor prepared in step S2 to a first heat treatment to obtain a ternary alloyed hard carbon-based composite intermediate;

[0080] S4: mixing a boron source and a nitrogen source to obtain a N and B source mixture, and subjecting the ternary alloyed hard carbon-based composite intermediate prepared in step S3 and the N and B source mixture to a second heat treatment to obtain the sodium ion battery anode composite material.

[0081] In certain embodiments, in step S1, the biomass material includes one or more of cellulose, bamboo, coconut shell, macadamia shell, walnut shell, pine nut shell, peanut shell, rice straw, cotton stalk skin, sugarcane bagasse, reed, reed bamboo, straw, walnut shell, coconut skin or lignin.

[0082] In certain embodiments, in step S1, the solid-liquid ratio of the biomass material to the deionized water is 1 g:(10-30) mL, for example, 1 g:10 mL, 1 g:11 mL, 1 g:12 mL, 1 g:13 mL, 1 g:14 mL, 1 g:15 mL, 1 g:16 mL, 1 g:17 mL, 1 g:18 mL, 1 g:19 mL, 1 g:20 mL, 1 g:21 mL, 1 g:22 mL, 1 g:23 mL, 1 g:24 mL, 1 g:25 mL, 1 g:26 mL, 1 g:27 mL, 1 g:28 mL, 1 g:29 mL or 1 g:30 mL, but is not limited to the listed values, and other values ​​not listed within the numerical range are equally applicable.

[0083] In certain embodiments, in step S1, the solid-liquid ratio of the biomass material to the deionized water is 1 g: (10-20) mL.

[0084] In certain embodiments, in step S1, the strong oxidant is selected from one or more of ammonium persulfate, potassium persulfate, sodium persulfate, sodium hypochlorite, potassium permanganate and potassium dichromate.

[0085] In certain embodiments, in step S1, the strong oxidant is selected from potassium persulfate.

[0086] In certain embodiments, in step S1, the concentration of the strong oxidant in the mixed solution B is 0.1 to 0.5 mol / L, for example, 0.1 mol / L, 0.11 mol / L, 0.12 mol / L, 0.13 mol / L, 0.14 mol / L, 0.15 mol / L, 0.16 mol / L, 0.17 mol / L, 0.18 mol / L, 0.19 mol / L, 0.2 mol / L, 0.22 mol / L, 0.24 mol / L, 0.26 mol / L, 0.28 mol / L, 0.3 mol / L, 0.35 mol / L, 0.4 mol / L, 0.45 mol / L or 0.5 mol / L, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0087] In certain embodiments, in step S1, the concentration of the strong oxidant in the mixed solution B is 0.1-0.3 mol / L.

[0088] In certain embodiments, in step S1, the carboxylation reaction time is 12 to 24 hours, for example, 12 hours, 13 hours, 14 hours, 15 hours, 16 hours, 17 hours, 18 hours, 19 hours, 20 hours, 21 hours, 22 hours, 23 hours or 24 hours, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0089] In certain embodiments, in step S1, after the carboxylation reaction is completed, a post-treatment step is further included; the post-treatment step includes: washing and drying; the drying temperature is 60-120°C, for example, 60°C, 61°C, 62°C, 63°C, 64°C, 65°C, 66°C, 67°C, 68°C, 69°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C or 120°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable; the time is 8-18 hours, for example, 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, 15 hours, 16 hours, 17 hours or 18 hours, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0090] In certain embodiments, in step S2, the bismuth (Bi) source is selected from one or more of bismuth chloride, bismuth nitrate pentahydrate, bismuth acetate, and bismuth subnitrate.

[0091] In certain embodiments, in step S2, the bismuth (Bi) source is selected from bismuth acetate.

[0092] In certain embodiments, in step S2, the antimony (Sb) source is selected from one or more of antimony trichloride, antimony pentachloride, antimony bromide and antimony tartrate.

[0093] In certain embodiments, in step S2, the antimony (Sb) source is selected from antimony trichloride.

[0094] In certain embodiments, in step S2, the source A is selected from a tin (Sn) source; the tin (Sn) source is selected from one or more of tin chloride, tin oxalate, tin sulfate and stannous sulfate.

[0095] In certain embodiments, in step S2, the source A is selected from a tin (Sn) source; and the source of tin (Sn) is selected from tin sulfate.

[0096] In some embodiments, in step S2, the molar concentration ratio of the bismuth (Bi) source, the antimony (Sb) source and the A source is (0.1-1.5):1:1, for example, 0.1:1:1, 0.2:1:1, 0.3:1:1, 0.4:1:1, 0.5:1:1, 0.6:1:1, 0.7:1:1, 0.8:1:1, 0.9:1:1, 1.0:1:1, 1.1:1:1, 1.2:1:1, 1.3:1:1, 1.4:1:1 or 1.5:1:1, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0097] In certain embodiments, in step S2, the molar concentration ratio of the bismuth (Bi) source, the antimony (Sb) source, and the A source is (0.1-1.0):1:1.

[0098] In certain embodiments, in step S2 , the molar concentration ratio of the bismuth (Bi) source, the antimony (Sb) source, and the A source is 1:1:1.

[0099] In certain embodiments, in step S2, the solid-liquid ratio of the modified biomass material to the mixed solution C is 1 g:(5-20) mL, for example, 1 g:5 mL, 1 g:6 mL, 1 g:7 mL, 1 g:8 mL, 1 g:9 mL, 1 g:10 mL, 1 g:11 mL, 1 g:12 mL, 1 g:13 mL, 1 g:14 mL, 1 g:15 mL, 1 g:16 mL, 1 g:17 mL, 1 g:18 mL, 1 g:19 mL or 1 g:20 mL, but is not limited to the listed values, and other values ​​not listed within the numerical range are equally applicable.

[0100] In certain embodiments, in step S2, the freezing includes liquid nitrogen freezing, and the liquid nitrogen freezing time is 1 to 2 hours, for example, 1 hour, 1.1 hours, 1.2 hours, 1.3 hours, 1.4 hours, 1.5 hours, 1.6 hours, 1.7 hours, 1.8 hours, 1.9 hours or 2 hours, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0101] In certain embodiments, in step S2, the drying comprises freeze drying, and the freeze drying temperature is -40 to -60°C, for example, -40°C, -41°C, -42°C, -43°C, -44°C, -45°C, -46°C, -47°C, -48°C, -49°C, -50°C, -51°C, -52°C, -53°C, -54°C, -55°C, -56°C, -57°C, -58°C, -59°C or -60°C, but is not limited to the values ​​listed, and other values ​​not listed within the numerical range are also included. The numerical values ​​also apply; the time is 24 to 48 hours, for example, 24 hours, 25 hours, 26 hours, 27 hours, 28 hours, 29 hours, 30 hours, 31 hours, 32 hours, 33 hours, 34 hours, 35 hours, 36 hours, 37 hours, 38 hours, 39 hours, 40 hours, 41 hours, 42 hours, 43 hours, 44 hours, 45 hours, 46 hours, 47 hours or 48 hours, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0102] In certain embodiments, in step S3, the first heat treatment is performed in an inert gas atmosphere, and the inert gas flow rate is 40 to 80 mL / min, for example, 40 mL / min, 41 mL / min, 42 mL / min, 43 mL / min, 44 mL / min, 45 mL / min, 46 mL / min, 47 mL / min, 48 mL / min, 49 mL / min, 50 mL / min, 55 mL / min, 60 mL / min, 65 mL / min, 70 mL / min, 75 mL / min or 80 mL / min, but are not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable; the inert gas includes one or more of nitrogen, argon and helium.

[0103] In some embodiments, in step S3, the temperature of the first heat treatment is 600-900°C, for example, 600°C, 601°C, 602°C, 603°C, 604°C, 605°C, 606°C, 607°C, 608°C, 609°C, 610°C, 620°C, 630°C, 640°C, 650°C, 660°C, 670°C, 680°C, 690°C, 700°C, 710°C , 720℃, 730℃, 740℃, 750℃, 760℃, 770℃, 780℃, 790℃, 800℃, 850℃ or 900℃, but are not limited to the listed values, and other values ​​not listed within the numerical range are also applicable; the time is 2 to 4 hours, such as 2 hours, 2.1 hours, 2.2 hours, 2.3 hours, 2.4 hours, 2.5 hours, 2.6 hours, 2.7 hours, 2 .8 hours, 2.9 hours, 3 hours, 3.5 hours or 4 hours, but not limited to the listed values, other values ​​not listed in the numerical range are equally applicable; the heating rate is 2 to 5°C / min, for example, 2°C / min, 2.1°C / min, 2.2°C / min, 2.3°C / min, 2.4°C / min, 2.5°C / min, 2.6°C / min, 2.7°C / min, 2.8°C / min, 2.9°C / min, 3.0°C / min, 3.2°C / min, 3.4°C / min, 3.6°C / min, 3.8°C / min, 4.0°C / min, 4.2°C / min, 4.4°C / min, 4.6°C / min, 4.8°C / min or 5.0°C / min, but not limited to the listed values, other values ​​not listed in the numerical range are equally applicable.

[0104] In certain embodiments, in step S3, the first heat treatment further includes a post-treatment step; the post-treatment step includes: grinding, sieving, washing, and drying; the particle size of the sieved particles is 5 to 10 μm, for example, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm or 10 μm, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable; the drying temperature is 60 to 120°C, for example, 60°C, 61°C, 62°C, 63°C, 64°C, 65°C, 66°C, 67°C, 68°C, 69°C , 70℃, 75℃, 80℃, 85℃, 90℃, 95℃, 100℃, 105℃, 110℃, 115℃ or 120℃, but are not limited to the listed values, and other unlisted values ​​within the numerical range are equally applicable; the time is 12 to 24 hours, for example, 12 hours, 13 hours, 14 hours, 15 hours, 16 hours, 17 hours, 18 hours, 19 hours, 20 hours, 21 hours, 22 hours, 23 hours or 24 hours, but is not limited to the listed values, and other unlisted values ​​within the numerical range are equally applicable.

[0105] In certain embodiments, in step S4, the boron source is selected from one or more of borax (Na2B4O7), boron oxide (B2O3) and boric acid.

[0106] In certain embodiments, in step S4, the boron source is selected from boron oxide (B2O3).

[0107] In certain embodiments, in step S4, the nitrogen source is selected from one or more of melamine, urea, ammonium chloride and trinitrophenol.

[0108] In certain embodiments, in step S4, the nitrogen source is selected from melamine.

[0109] In certain embodiments, in step S4, the molar ratio of the boron source to the nitrogen source is 1:(1-5), for example, 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5 or 1:5, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0110] In certain embodiments, in step S4, the molar ratio of the boron source to the nitrogen source is 1:(1-3).

[0111] In some embodiments, in step S4, the mass ratio of the ternary alloyed hard carbon-based composite intermediate and the N and B source mixture is (1 to 5):1, for example, 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1 or 5:1, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0112] In certain embodiments, in step S4, the mass ratio of the ternary alloyed hard carbon-based composite intermediate to the N and B source mixture is (2-4):1.

[0113] In certain embodiments, in step S4, the second heat treatment is performed in an inert gas atmosphere, and the inert gas flow rate is 40 to 80 mL / min, for example, 40 mL / min, 41 mL / min, 42 mL / min, 43 mL / min, 44 mL / min, 45 mL / min, 46 mL / min, 47 mL / min, 48 mL / min, 49 mL / min, 50 mL / min, 55 mL / min, 60 mL / min, 65 mL / min, 70 mL / min, 75 mL / min or 80 mL / min, but are not limited to the listed values, and other values ​​not listed within the numerical range are also applicable; the inert gas includes one or more of nitrogen, argon and helium.

[0114] In some embodiments, in step S4, the temperature of the second heat treatment is 800-1000°C, for example, 800°C, 801°C, 802°C, 803°C, 804°C, 805°C, 806°C, 807°C, 808°C, 809°C, 810°C, 820°C, 830°C, 840°C, 850°C, 860°C, 870°C, 880°C, 890°C, 900°C, 910°C. , 920℃, 930℃, 940℃, 950℃, 960℃, 970℃, 980℃, 990℃ or 1000℃, but not limited to the listed values, other values ​​not listed in the numerical range are also applicable; the time is 2 to 5 hours, such as 2 hours, 2.1 hours, 2.2 hours, 2.3 hours, 2.4 hours, 2.5 hours, 2.6 hours, 2.7 hours, 2.8 hours, 2.9 hours 1 hour, 3 hours, 3.5 hours, 4 hours, 4.5 hours or 5 hours, but not limited to the listed values, other values ​​not listed in the numerical range are equally applicable; the heating rate is 2-5°C / min, for example, 2°C / min, 2.1°C / min, 2.2°C / min, 2.3°C / min, 2.4°C / min, 2.5°C / min, 2.6°C / min, 2.7°C / min, 2.8°C / min, 2.9°C / min, 3.0°C / min, 3.2°C / min, 3.4°C / min, 3.6°C / min, 3.8°C / min, 4.0°C / min, 4.2°C / min, 4.4°C / min, 4.6°C / min, 4.8°C / min or 5.0°C / min, but not limited to the listed values, other values ​​not listed in the numerical range are equally applicable.

[0115] In certain embodiments, in step S4, a post-treatment step is further included after the second heat treatment; the post-treatment step includes: washing and drying; the drying temperature is 60-120°C, for example, 60°C, 61°C, 62°C, 63°C, 64°C, 65°C, 66°C, 67°C, 68°C, 69°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C or 120°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable; the time is 12-24 hours, for example, 12 hours, 13 hours, 14 hours, 15 hours, 16 hours, 17 hours, 18 hours, 19 hours, 20 hours, 21 hours, 22 hours, 23 hours or 24 hours, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0116] [Anode plate]

[0117] In a third aspect, the present invention provides an anode pole piece, comprising the sodium ion battery anode composite material as described in any one of the first aspects or the sodium ion battery anode composite material prepared by the preparation method as described in any one of the second aspects.

[0118] In the present invention, the anode plate may further include a conductive agent and a binder. There is no particular limitation on the types of the conductive agent and binder in the anode plate, as long as the purpose of the present invention can be achieved. For example, the binder may include, but is not limited to, polyvinyl alcohol, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, a polymer containing ethylene oxide, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin, or nylon. For example, the conductive agent may include, but is not limited to, conductive carbon black, acetylene black, Ketjen black, carbon fiber, or any combination thereof.

[0119] There is no particular limitation on the method for preparing the anode electrode in the present invention, and any method known in the art may be used as long as the purpose of the present invention can be achieved.

[0120] It should be understood that since the anode plate provided by the present invention includes the sodium ion battery anode composite material described in the second aspect of the present invention, the beneficial effects of preparing the sodium ion battery anode composite material described in any of the above embodiments are applicable to the anode plate.

[0121] [Sodium-ion battery]

[0122] In a fourth aspect, the present invention provides a sodium ion battery, comprising the anode electrode sheet as described in the third aspect.

[0123] The battery structure of the present invention may also include but is not limited to button batteries, soft-pack batteries, cylindrical batteries, etc.

[0124] The sodium ion battery of the present invention may further include an anode electrode piece, a cathode electrode piece, a diaphragm and an electrolyte. There is no particular limitation on the cathode electrode piece, the diaphragm and the electrolyte in the sodium ion battery, and those skilled in the art can select according to actual needs, as long as the purpose of the present invention can be achieved. For example, the diaphragm is a polypropylene diaphragm (PP), a polyethylene diaphragm (PE), a polypropylene / polyethylene double-layer composite film (PP / PE), a polypropylene / polyethylene / polypropylene three-layer composite film (PP / PE / PP), a polyimide electrospun diaphragm (PI), a cellulose non-woven diaphragm, a polyethylene terephthalate non-woven diaphragm (PET) and a diaphragm with a ceramic coating.

[0125] The reagents, instruments and materials used in the present invention can be obtained through commercial channels.

[0126] The method of the present invention is described below by means of specific examples. It should be understood that these examples are used to illustrate the basic principles, main features and advantages of the present invention, and the present invention is not limited to the scope of the following examples. The implementation conditions adopted in the examples can be further adjusted according to specific requirements. The implementation conditions not specified are generally the conditions in routine experiments.

[0127] Example 1

[0128] The preparation of the sodium ion battery anode composite material in this embodiment includes the following steps:

[0129] S101: 200 g of cellulose and 162 g of potassium persulfate were placed in 3 L of deionized water and stirred for 1 hour. After stirring, the mixture was washed three times with deionized water and dried at 80° C. for 12 hours to obtain modified cellulose.

[0130] S102: 38.6 g of bismuth acetate, 22.8 g of antimony trichloride and 21.5 g of tin sulfate were added to 1000 ml of deionized water and stirred to obtain a mixed solution. Subsequently, 100 g of modified cellulose was immersed in the mixed solution and stirred for 1 hour. The mixture was placed in liquid nitrogen for freezing treatment, and the liquid nitrogen was frozen for 2 hours. Then, the mixture was placed in a freeze dryer at -60°C for freeze drying, and freeze dried for 24 hours to obtain a ternary metal salt modified biomass precursor.

[0131] S103: The ternary metal salt modified biomass precursor obtained in step S102 is placed in a tubular furnace, and carbonized under a nitrogen atmosphere at a gas flow rate of 80 mL / min, a heating rate of 2°C / min, a carbonization temperature of 700°C, and a holding time of 2 hours. After the carbonization, the material is ground and passed through a 400-mesh sieve. The material is then rinsed three times with deionized water and dried at 80°C for 12 hours to obtain a ternary alloyed hard carbon-based composite intermediate.

[0132] S104: Take 6.96g of boron oxide, 12.61g of melamine and 60g of the ternary alloyed hard carbon-based composite intermediate obtained in step S103, stir and mix them, place them in a tubular furnace, and carbonize them under an ammonia atmosphere with a gas flow rate of 80mL / min, a heating rate of 2℃ / min, a carbonization temperature of 800℃, and a holding time of 2 hours. Then, the material is immersed in deionized water three times and dried at 80℃ for 12 hours to obtain a sodium ion battery anode composite material.

[0133] Example 2

[0134] The preparation of the sodium ion battery anode composite material in this embodiment includes the following steps:

[0135] S101: 200 g of sugarcane bagasse (1 g: 10-30 ml) and 162 g of potassium persulfate were placed in 3 L of deionized water and stirred for 1 hour. After the stirring, the mixture was washed three times with deionized water and dried at 80 degrees for 12 hours to obtain modified sugarcane bagasse.

[0136] S102: 38.6 g of bismuth acetate, 22.8 g of antimony trichloride and 21.5 g of tin sulfate were added to 1000 ml of deionized water and stirred to obtain a mixed solution. Subsequently, 100 g of modified bagasse was immersed in the mixed solution and stirred for 1 hour. The mixture was placed in liquid nitrogen for freezing treatment, and the liquid nitrogen was frozen for 2 hours. Then, the mixture was placed in a freeze dryer at -60°C for freeze drying and freeze drying for 36 hours to obtain a ternary metal salt modified biomass precursor.

[0137] S103: The ternary metal salt modified biomass precursor obtained in step S102 is placed in a tubular furnace, and carbonized under a nitrogen atmosphere at a gas flow rate of 80 mL / min, a heating rate of 2°C / min, a carbonization temperature of 700°C, and a holding time of 2 hours. After the carbonization, the material is ground and passed through a 400-mesh sieve. The material is then rinsed three times with deionized water and dried at 80°C for 12 hours to obtain a ternary alloyed hard carbon-based composite intermediate.

[0138] S104: Take 6.96g of boron oxide, 12.61g of melamine and 60g of the ternary alloyed hard carbon-based composite intermediate obtained in step S103, stir and mix them, place them in a tubular furnace, and carbonize them under an ammonia atmosphere with a gas flow rate of 80mL / min, a heating rate of 2℃ / min, a carbonization temperature of 800℃, and a holding time of 2 hours. Then, the material is immersed in deionized water three times and dried at 80℃ for 12 hours to obtain a sodium ion battery anode composite material.

[0139] Example 3

[0140] The preparation of the sodium ion battery anode composite material in this embodiment includes the following steps:

[0141] S101: 200 g of bamboo fiber (1 g: 10-30 ml) and 162 g of potassium persulfate were placed in 3 L of deionized water, stirred for 1 hour, washed three times with deionized water after stirring, and dried at 80 degrees for 12 hours to obtain modified bamboo fiber.

[0142] S102: 38.6 g of bismuth acetate, 22.8 g of antimony trichloride and 21.5 g of tin sulfate were added to 1000 ml of deionized water and stirred to obtain a mixed solution. Subsequently, 100 g of modified bamboo fiber was immersed in the mixed solution and stirred for 1 hour. The mixture was placed in liquid nitrogen for freezing treatment, and the liquid nitrogen was frozen for 2 hours. Then, it was placed in a freeze dryer at -60°C for freeze drying and freeze drying for 24 hours to obtain a ternary metal salt modified biomass precursor.

[0143] S103: The ternary metal salt modified biomass precursor obtained in step S102 is placed in a tubular furnace, and carbonized under a nitrogen atmosphere at a gas flow rate of 80 mL / min, a heating rate of 2°C / min, a carbonization temperature of 700°C, and a holding time of 2 hours. After the carbonization, the material is ground and passed through a 400-mesh sieve. The material is then rinsed three times with deionized water and dried at 80°C for 12 hours to obtain a ternary alloyed hard carbon-based composite intermediate.

[0144] S104: Take 6.96g of boron oxide, 12.61g of melamine and 60g of the ternary alloyed hard carbon-based composite intermediate obtained in step S103, stir and mix them, place them in a tubular furnace, and carbonize them under an ammonia atmosphere with a gas flow rate of 80mL / min, a heating rate of 2℃ / min, a carbonization temperature of 800℃, and a holding time of 2 hours. Then, the material is immersed in deionized water three times and dried at 80℃ for 12 hours to obtain a sodium ion battery anode composite material.

[0145] Example 4

[0146] The preparation of the sodium ion battery anode composite material in this embodiment includes the following steps:

[0147] S101: 200 g of coconut shell (1 g: 10-30 ml) and 162 g of potassium persulfate were placed in 3 L of deionized water and stirred for 1 hour. After stirring, the mixture was washed three times with deionized water and dried at 80 degrees for 12 hours to obtain modified coconut shell.

[0148] S102: 38.6 g of bismuth acetate, 22.8 g of antimony trichloride and 21.5 g of tin sulfate were added to 1000 ml of deionized water and stirred to obtain a mixed solution. Subsequently, 100 g of modified coconut shell was immersed in the mixed solution and stirred for 1 hour. The mixture was placed in liquid nitrogen for freezing treatment, and the liquid nitrogen was frozen for 2 hours. Then, the mixture was placed in a freeze dryer at -60°C for freeze drying and freeze drying for 24 hours to obtain a ternary metal salt modified biomass precursor.

[0149] S103: The ternary metal salt modified biomass precursor obtained in step S102 is placed in a tubular furnace, and carbonized under a nitrogen atmosphere at a gas flow rate of 80 mL / min, a heating rate of 2°C / min, a carbonization temperature of 700°C, and a holding time of 2 hours. After the carbonization, the material is ground and passed through a 400-mesh sieve. The material is then rinsed three times with deionized water and dried at 80°C for 12 hours to obtain a ternary alloyed hard carbon-based composite intermediate.

[0150] S104: Take 6.96g of boron oxide, 12.61g of melamine and 60g of the ternary alloyed hard carbon-based composite intermediate obtained in step S103, stir and mix them, place them in a tubular furnace, and carbonize them under an ammonia atmosphere with a gas flow rate of 80mL / min, a heating rate of 2℃ / min, a carbonization temperature of 800℃, and a holding time of 2 hours. Then, the material is immersed in deionized water three times and dried at 80℃ for 12 hours to obtain a sodium ion battery anode composite material.

[0151] Comparative Example 1: Direct carbonization of cellulose

[0152] The preparation of the sodium ion battery anode material in this comparative example comprises the following steps:

[0153] S101: 50 g of cellulose material was placed in a porcelain boat and calcined in a nitrogen atmosphere at 700°C with a heating rate of 2°C / min. The mixture was kept warm for two hours, cooled to 500°C at a cooling rate of 5°C / min, and then naturally cooled to room temperature to obtain a sodium ion battery anode material.

[0154] Comparative Example 2: Cellulose-based hard carbon B, N doping

[0155] The preparation of the sodium ion battery anode material in this comparative example comprises the following steps:

[0156] S101: Place 100 g of cellulose material into a porcelain boat and calcine it in a nitrogen atmosphere at a temperature of 700°C and a heating rate of 2°C / min. Keep warm for two hours, cool it to 500°C at a cooling rate of 5°C / min, and then naturally cool it to room temperature to obtain material No. 1.

[0157] S102: Take 6.96g of boron oxide, 12.61g of melamine and 20g of material No. 1 prepared in step S101, stir and mix them, place them in a tube furnace, and carbonize them at a temperature of 900℃ under an ammonia atmosphere with a gas flow rate of 80mL / min, a heating rate of 2℃ / min, and a holding time of 2 hours. Then, the material is rinsed three times with deionized water to obtain a sodium ion battery anode material.

[0158] Comparative Example 3: Cellulose-based hard carbon composite ternary alloy

[0159] The preparation of the sodium ion battery anode material in this comparative example comprises the following steps:

[0160] S101: 38.6 g of bismuth acetate, 22.8 g of antimony trichloride and 21.5 g of tin sulfate were added to 1000 mL of deionized water and stirred to obtain a mixed solution. Subsequently, 100 g of modified cellulose was immersed in the mixed solution and stirred for 1 hour. The mixture was placed in liquid nitrogen for freezing treatment, and then placed in a freeze dryer at -60°C for freeze drying. After completion, material No. 2 was obtained.

[0161] S102: Material No. 2 prepared in step S101 is placed in a tubular furnace, and carbonized under a nitrogen atmosphere at a gas flow rate of 80 mL / min, a heating rate of 2°C / min, a carbonization temperature of 700°C, and a holding time of 2 hours. After the carbonization, the material is ground and passed through a 400-mesh sieve. The material is then rinsed three times with deionized water and dried to obtain a sodium ion battery anode material.

[0162] Test Case

[0163] 1. Preparation of batteries

[0164] The preparation of the battery includes the following steps:

[0165] (1) The anode composite materials prepared in the above examples and comparative examples were used as anode active materials, carbon black was used as a conductive agent, and CMC was used as a binder.

[0166] The anode active material, conductive agent and binder are mixed in a mass ratio of 8:1:1 to obtain a mixed material, and the mixed material is fully stirred in deionized water to obtain the corresponding anode slurry; the anode slurry is evenly coated on the negative electrode current collector copper foil, and after drying, pressing and other processes, the anode electrode sheet is obtained.

[0167] (2) Provide a metal sodium plate as the cathode electrode.

[0168] (3) A glass fiber diaphragm is provided as an isolation membrane.

[0169] (4) Providing an electrolyte solution, wherein the electrolyte solution is prepared by dissolving 1.0 mol / L NaPF6 in diethylene glycol dimethyl ether.

[0170] (5) Assemble the anode electrode, isolation membrane, and cathode electrode in the order of assembling and soaking them with electrolyte respectively, and assemble them into CR2032 button batteries in an argon glove box.

[0171] 2. Test the electrochemical performance of the battery

[0172] First charge and discharge capacity and coulombic efficiency: At 25 degrees, discharge at a constant current of 0.1C discharge rate to 0V, the discharge capacity at this time is recorded as the first discharge capacity; charge at a constant current of 0.1C charge rate to 2V, the charge capacity at this time is recorded as the first charge capacity; first coulombic efficiency = (first charge capacity / first discharge capacity) * 100%.

[0173] Capacity retention after 1000 cycles: At 25°C, discharge the battery to 0V at a 0.1C discharge rate and constant current. The discharge capacity at this point is recorded as the initial discharge capacity. Charge the battery to 2V at a 0.1C charge rate and constant current. The charge capacity at this point is recorded as the initial charge capacity. This constitutes one cycle and is recorded as cycle 1. Repeat the cycle for 1000 cycles. End the test and record the charge capacity at cycle 1000. Therefore, capacity retention after 1000 cycles = (charge capacity at cycle 1000 / charge capacity at cycle 1) * 100%.

[0174] Performance Test 1

[0175] The button cells prepared in Examples 1-4 and Comparative Examples 1-3 were sequentially subjected to constant current charge and discharge tests at a current density of 0.1C and a voltage range of 0-2V. The sodium ion battery anode composite button cells prepared in Examples 1-4 all had high initial charge capacities (all exceeding 900 mAh / g) and initial coulombic efficiency of 72.3%. Comparative Example 1, on the other hand, had an initial charge capacity of only 254.6 mAh / g and an initial coulombic efficiency of 67.8%. See Table 1 for specific values.

[0176] Table 1 Electrochemical performance data of button cells

[0177]

[0178] During the charge and discharge process, the ternary alloy material undergoes a reversible alloying reaction with sodium ions, thus contributing to excellent gram capacity performance.

[0179] Performance Test 2

[0180] The button batteries prepared in Examples 1 to 4 and Comparative Examples 1-3 were subjected to constant current charge and discharge tests and cycle tests. The test process was the same as above. After 1000 cycles, the button batteries of the sodium ion battery anode composite materials prepared in Examples 1 to 4 all had a high cycle capacity retention rate (all greater than 90%) and excellent cycle stability; while the capacity retention rate of Comparative Example 2 was only 72.4%. Although Comparative Example 1 showed a high capacity retention rate, this was because the material of Comparative Example 1 had an extremely low gram capacity under high current density, resulting in a "falsely high" capacity retention rate, which actually reflected the poor cycle performance of Comparative Example 1 under high current. Specific values ​​are shown in Table 2.

[0181] Table 2 Electrochemical performance data of button cell

[0182] Current density 1500mA / g First charge capacity mAh / g Capacity retention rate after 1000 cycles (%) Example 1 410.2 90.8 Example 2 415.6 90.2 Example 3 416.1 90.3 Example 4 413.5 90.6 Comparative Example 1 20.6 98.2 Comparative Example 2 100.7 72.4 Comparative Example 3 350.2 87.3

[0183] The dual-element doping and ternary alloy have a synergistic effect, which makes the material have high ionic conductivity. At the same time, the good mechanical properties and fibrous structure can effectively shorten the transmission distance during the ion and electron transmission process, making the battery have good cycle stability and improving the overall electrochemical performance of the electrode.

[0184] It should be noted that the sodium ion battery anode composite material embodiment, the sodium ion battery anode composite material preparation method embodiment, the anode pole piece embodiment and the battery embodiment provided by the present invention belong to the same concept; the various technical features in the technical solutions recorded in each embodiment can be arbitrarily combined without conflict.

[0185] It should be understood that the above embodiments are exemplary and are not intended to encompass all possible implementations of the claims. Various modifications and variations may be made to the above embodiments without departing from the scope of this disclosure. Similarly, the various technical features of the above embodiments may be arbitrarily combined to form additional embodiments of the present invention that may not be explicitly described. Therefore, the above embodiments merely illustrate several implementations of the present invention and do not limit the scope of protection of the patent of this invention.

Claims

1. A sodium ion battery anode composite material, characterized in that: The composite material comprises a biomass hard carbon material and a Bi-Sb-A ternary alloy material supported on the hard carbon material. The structure of the ternary alloy material is represented by the general formula Bi x Sb y A z Indicates that x:y:z = (0.1 to 1.5): 1:1; the structure of the ternary alloy material is a Bi-Sb-A alloy phase or a phase-separated mixture of a Bi-Sb phase, a Sb-A phase, and a Bi phase with a uniform microscopic dispersion structure; wherein the A element is selected from at least one of tin (Sn), germanium (Ge), and lead (Pb).

2. The composite material according to claim 1, characterized in that The composite material satisfies at least one of the following characteristics (1) to (6): (1) The particle size of the ternary alloy material is 10 to 100 nm; (2) The mass of the ternary alloy material accounts for 10 to 40% of the total mass of the composite material; (3) The ternary alloy material has a layered structure; (4) The composite material has a fibrous structure; (5) The structure of the ternary alloy material is Bi x Sb y Sn z ; (6) The x:y:z=(0.5-1.0):1:

1.

3. The composite material according to claim 1, characterized in that Doping elements are also distributed in the composite material; the doping elements include boron (B) and nitrogen (N); the atomic proportion of boron (B) in the composite material is 1 to 5%; the atomic proportion of nitrogen (N) in the composite material is 1 to 5%.

4. A method for preparing a sodium ion battery anode composite material, characterized in that: The following steps are involved: S1: adding the biomass material to deionized water, and then adding a strong oxidant to obtain a mixed solution B, and performing a carboxylation reaction to obtain a modified biomass material; S2: adding a bismuth (Bi) source, an antimony (Sb) source, and a source A to deionized water and mixing them to obtain a mixed solution C; immersing the modified biomass material prepared in step S1 in the mixed solution C and mixing them to obtain a mixture; freezing and drying the mixture to obtain a ternary metal salt modified biomass precursor; wherein the source A is selected from at least one of a tin (Sn) source, a germanium (Ge) source, and a lead (Pb) source; S3: subjecting the ternary metal salt-modified biomass precursor prepared in step S2 to a first heat treatment to obtain a ternary alloyed hard carbon-based composite intermediate; S4: mixing a boron source and a nitrogen source to obtain a N and B source mixture, and subjecting the ternary alloyed hard carbon-based composite intermediate prepared in step S3 and the N and B source mixture to a second heat treatment to obtain the sodium ion battery anode composite material.

5. The preparation method according to claim 4, characterized in that The step S1 satisfies at least one of the following characteristics (1) to (6): (1) The biomass material comprises one or more of cellulose, bamboo, coconut shell, macadamia shell, walnut shell, pine nut shell, peanut shell, rice straw, cotton stalk skin, sugarcane bagasse, reed, reed bamboo, straw, walnut shell, coconut shell or lignin; (2) The solid-liquid ratio of the biomass material to the deionized water is 1 g: (10-30) mL; (3) The strong oxidant is selected from one or more of ammonium persulfate, potassium persulfate, sodium persulfate, sodium hypochlorite, potassium permanganate and potassium dichromate; (4) In the mixed solution B, the concentration of the strong oxidant is 0.1 to 0.5 mol / L; (5) The carboxylation reaction time is 12 to 24 hours; (6) After the carboxylation reaction is completed, a post-treatment step is further included; the post-treatment step includes: washing and drying; the drying temperature is 60 to 120° C. and the drying time is 8 to 18 hours.

6. The preparation method according to claim 4, characterized in that The step S2 satisfies at least one of the following characteristics (1) to (7): (1) The bismuth (Bi) source is selected from one or more of bismuth chloride, bismuth nitrate pentahydrate, bismuth acetate and bismuth subnitrate; (2) The antimony (Sb) source is selected from one or more of antimony trichloride, antimony pentachloride, antimony bromide and antimony tartrate; (3) The source A is selected from a tin (Sn) source; the source of tin (Sn) is selected from one or more of tin chloride, tin oxalate, tin sulfate and stannous sulfate; (4) The molar concentration ratio of the bismuth (Bi) source, the antimony (Sb) source, and the A source is (0.1-1.5):1:1; (5) The solid-liquid ratio of the modified biomass material to the mixed solution C is 1 g: (5-20) mL; (6) The freezing includes liquid nitrogen freezing, and the liquid nitrogen freezing time is 1 to 2 hours; (7) The drying includes freeze drying, and the freeze drying temperature is -40 to -60°C and the time is 24 to 48 hours.

7. The preparation method according to claim 4, characterized in that The step S3 satisfies at least one of the following characteristics (1) to (3): (1) The first heat treatment is performed in an inert gas atmosphere with a flow rate of 40 to 80 mL / min; the inert gas includes one or more of nitrogen, argon, and helium; (2) The temperature of the first heat treatment is 600-900°C, the time is 2-4 hours, and the heating rate is 2-5°C / min; (3) After the first heat treatment, a post-processing step is also included; the post-processing step includes: grinding, screening, washing, and drying; the particle size of the screened particles is 5 to 10 μm; The drying temperature is 60-120° C. and the drying time is 12-24 hours.

8. The preparation method according to claim 4, characterized in that The step S4 satisfies at least one of the following characteristics (1) to (7): (1) The boron source is selected from one or more of borax (Na2B4O7), boron oxide (B2O3) and boric acid; (2) The nitrogen source is selected from one or more of melamine, urea, ammonium chloride and trinitrophenol; (3) The molar ratio of the boron source to the nitrogen source is 1:(1-5); (4) The mass ratio of the ternary alloyed hard carbon-based composite intermediate to the N and B source mixture is (1 to 5):1; (5) The second heat treatment is carried out in an inert gas atmosphere with a flow rate of 40 to 80 mL / min; the inert gas includes one or more of nitrogen, argon, and helium; (6) The temperature of the second heat treatment is 800-1000°C, the time is 2-5 hours, and the heating rate is 2-5°C / min; (7) After the second heat treatment, a post-treatment step is further included; the post-treatment step includes: washing and drying; the drying temperature is 60 to 120° C. and the drying time is 12 to 24 hours.

9. An anode pole piece, characterized in that: The anode pole piece comprises the sodium ion battery anode composite material according to any one of claims 1 to 3 or the sodium ion battery anode composite material prepared by the preparation method according to any one of claims 4 to 8.

10. A sodium ion battery, characterized in that: The sodium ion battery comprises the anode electrode sheet according to claim 9.

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