Composite material and preparation method thereof, electrode material and lithium ion battery

Abstract

The invention relates to a composite material and a preparation method thereof, an electrode material and a lithium ion battery. The composite material comprises a core material and a shell wrapping the core material, the material of the core material comprises tin disulfide and a detonation nano-diamond compound, and the material of the shell comprises graphene; wherein the mass percentage of tin disulfide in the composite material is 3%-13%, the mass percentage of the detonation nano-diamond is 75%-81%, and the mass percentage of the graphene is 10%-20%. The composite material with a core-shell structure is formed by coating detonation nano-diamond and tin disulfide with graphene, the composite material has a stable structure, volume expansion of SnS2 in a traditional charging and discharging process is effectively inhibited, and an efficient three-dimensional conductive network is constructed while the composite material is prevented from being pulverized; the rate capability and charge transfer dynamics of the composite material as an electrode are improved, and the cycling stability is improved.

Description

Technical Field

[0001] This application relates to the field of electrode material technology, specifically to a composite material and its preparation method, electrode material and lithium-ion battery. Background Technology

[0002] Lithium-ion batteries are widely used in portable electronic devices and electric vehicles due to their high energy density and long cycle life. Currently, commercially available graphite anode materials have a relatively low theoretical specific capacity (372 mAh•g). -1 However, this makes it difficult to meet the high energy density requirements. Tin disulfide (SnS2) has a layered structure and a high theoretical specific capacity (782 mAh•g), which is insufficient to meet the high energy density requirements. -1 SnS2 exhibits a CdI2-type crystal structure, belonging to a layered hexagonal structure. It is a sandwich structure consisting of two layers of sulfur atoms sandwiching a layer of tin atoms. The interlayer spacing of each layer is larger than the diameter of a lithium ion, which facilitates lithium ion movement. SnS2 is an n-type semiconductor material, and its relatively narrow bandgap of approximately 2.2 eV gives it excellent electrical properties. SnS2 also possesses significantly higher electrical properties than graphite (372 mAh / g) due to its unique lithium insertion / extraction reaction. -1 The theoretical specific capacity is 782 mAh•g. -1 It is a promising anode material.

[0003] However, SnS2 also has some drawbacks as an electrode material: for example, when lithium ions are embedded in the SnS2 lattice, they undergo a volume expansion of about 200%, leading to pulverization of the material; and SnS2 has very poor conductivity, with a conductivity of about 10. -12 ~10 -2 S•cm -1 Meanwhile, Li2S is generated during charging and discharging, which leads to a decrease in the initial coulombic efficiency and a reduction in battery capacity. Summary of the Invention

[0004] Therefore, it is necessary to provide a composite material that can effectively avoid the problem of material pulverization and has good conductivity, as well as its preparation method, electrode material, and lithium-ion battery.

[0005] This application provides a composite material, including a core material and a shell covering the core material, wherein the core material comprises tin disulfide and detonated nanodiamond, and the shell material comprises graphene.

[0006] The composite material comprises, by mass percentage, 3% to 13% of the tin disulfide, 75% to 81% of the detonated nanodiamond, and 10% to 20% of the graphene.

[0007] In one embodiment, one or both of the following conditions are met:

[0008] (1) The particle size of the detonation nanodiamond is 5nm~50nm;

[0009] (2) The thickness of the outer shell is 1nm~10nm.

[0010] In one embodiment, the particle size of the composite material is 50 nm to 500 nm.

[0011] This application also provides a method for preparing a composite material, comprising the following steps:

[0012] A core material precursor is provided, wherein the material of the core material precursor comprises tin disulfide supported on detonation nanodiamond;

[0013] The core material precursor is placed in a reducing metal salt solution with a pH of 10-12. The reducing metal salt solution includes a reducing agent and a metal salt in a mass ratio of 0.5:1 to 2:1. The metal salt includes one of nickel salt, cobalt salt, and copper salt to form a core material template.

[0014] The core template is placed in a carbon source solution with a pH of 12-14 for carbonization and annealing. A shell is then coated on the surface of the core template. The shell material includes graphene to prepare a composite material precursor.

[0015] The composite material precursor is placed in an etching solution to prepare the composite material, wherein the composite material comprises, by mass percentage, 3% to 13% tin disulfide, 75% to 81% detonated nanodiamond, and 10% to 20% graphene.

[0016] In one embodiment, the preparation method of the core material precursor includes a solvothermal method.

[0017] In one embodiment, the method for preparing the core precursor includes the following steps:

[0018] Detonation nanodiamond, tin source, sulfur source and solvent are mixed in a mass ratio of 100:(1~20):(0.5~10):(5000~8000) and reacted at a temperature of 150℃~200℃ for 4 to 8 hours. The solid is then separated to prepare the core material precursor.

[0019] In one embodiment, one or more of the following conditions are met:

[0020] (1) The tin source includes one or both of tin tetrachloride and tin sulfate;

[0021] (2) The sulfur source includes thiourea, L - One or more of cysteine ​​and thioacetamide;

[0022] (3) The solvent includes one or more of ethanol, ethylene glycol and water.

[0023] In one embodiment, one or more of the following conditions are met:

[0024] (1) The reducing agent includes one or more of dimethylamine borane, sodium borohydride and sodium hypophosphite;

[0025] (2) The core material precursor is placed in the reducing metal salt solution for 20 min to 60 min;

[0026] (3) The carbonization temperature is 150℃~200℃;

[0027] (4) The carbonization treatment time is 6h~10h;

[0028] (5) The annealing temperature is 400℃~500℃;

[0029] (6) The annealing time is 0.5h~2h;

[0030] (7) The etching solution includes one or more of ferric chloride, hydrochloric acid and nitric acid.

[0031] This application provides an electrode material, including the composite material as described above or the composite material prepared by the preparation method described above.

[0032] This application also provides a lithium-ion battery, including a positive electrode, a negative electrode, a separator, and an electrolyte. The separator is disposed between the positive electrode and the negative electrode. The positive electrode, the negative electrode, and the separator are immersed in the electrolyte. The material of the negative electrode includes the electrode material described above.

[0033] This application utilizes a composite material of graphene-coated detonation nanodiamonds and tin disulfide to form a core-like structure. - The shell-structured composite material, with its amorphous carbon surface rich in active sites, possesses abundant shell-structured nanodiamonds that can be effectively combined with tin disulfide. Compared to graphite, diamond exhibits better conductivity and a stable structure, effectively suppressing the volume expansion of SnS2 during traditional charge and discharge processes. This prevents the composite material from pulverizing while simultaneously constructing a highly efficient three-dimensional conductive network, improving the rate performance and charge transport dynamics of the composite material as an electrode, and enhancing cycle stability. Attached Figure Description

[0034] Figure 1 The images are scanning electron microscope images of the composite materials of Examples 1 to Comparative Examples 1; (a) is the composite material of Comparative Example 1, (b) is the composite material of Example 1, (c) is the composite material of Example 2, and (d) is the composite material of Example 3.

[0035] Figure 2 The X-ray diffraction patterns of the composite materials of Examples 1, 2, 3 and Comparative Example 1 are shown, with intensity on the vertical axis.

[0036] Figure 3 The graphs are thermogravimetric analysis and differential scanning calorimetry curves of the composite materials of Example 2 and Comparative Example 1. Temperature is the temperature, mass is the mass, TG is the thermogravimetric analysis, DSC is the differential scanning calorimetry, and endothermic is the endothermic analysis.

[0037] Figure 4 The image shows the Raman spectrum of the composite material in Example 2, with wavelength on the horizontal axis and intensity on the vertical axis.

[0038] Figure 5 The constant current charge-discharge specific capacity curves of lithium-ion batteries using the composite materials of Examples 1, 2, 3, and Comparative Example 1 as negative electrodes, and the coulombic efficiency curve of lithium-ion batteries using the composite material of Example 2 as negative electrodes are shown. The cycle number is the number of cycles, the specific capacity is the specific capacity, and the coulombic efficiency is the coulombic efficiency.

[0039] Figure 6 The graphs show the rate performance curves of lithium-ion batteries using the composite materials of Example 1, Example 2, Example 3, and Comparative Example 1 as negative electrodes. The cycle number represents the number of cycles, and the specific capacity represents the specific capacity. Detailed Implementation

[0040] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings. Preferred embodiments of this application are shown in the drawings. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of this application.

[0041] Unless otherwise stated or in case of contradiction, the terms or phrases used herein shall have the following meanings:

[0042] In this application, the selection range of "and / or", "or / and", and "and / or" includes any one of two or more related listed items, as well as any and all combinations of the related listed items. These arbitrary and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items. It should be noted that when at least three items are connected using at least two conjunctions selected from "and / or", "or / and", and "and / or", it should be understood that the technical solution undoubtedly includes technical solutions connected by "logical AND", and also undoubtedly includes technical solutions connected by "logical OR". For example, "A and / or B" includes three parallel solutions: A, B, and A+B. For example, the technical solution of "A, and / or, B, and / or, C, and / or, D" includes any one of A, B, C, and D (that is, a technical solution that is connected by "logical OR"), as well as any and all combinations of A, B, C, and D, that is, combinations of any two or three of A, B, C, and D, and also combinations of all four of A, B, C, and D (that is, a technical solution that is connected by "logical AND").

[0043] In this application, the terms "multiple", "various", "multiple times", "multi-dimensional", etc., unless otherwise specified, refer to a quantity greater than or equal to 2. For example, "one or more" means one or more than or equal to two.

[0044] In this application, the terms "combinations thereof", "any combination thereof", and "any combination thereof" include all suitable combinations of any two or more of the listed items.

[0045] In this application, the term "suitable" as used in phrases such as "suitable combination," "suitable method," and "any suitable method" refers to the ability to implement the technical solution of this application, solve the technical problem of this application, and achieve the expected technical effect of this application.

[0046] In this application, terms such as "preferred," "better," "more suitable," and "ideal" are used only to describe implementation methods or embodiments with better effects, and should be understood not to constitute a limitation on the scope of protection of this application.

[0047] In this application, terms such as "further," "even further," and "particularly" are used for descriptive purposes to indicate differences in content, but should not be construed as limiting the scope of protection of this application.

[0048] In this application, the terms "optionally," "optionally," and "optional" refer to options that are optional, meaning they can be selected from either "with" or "without." If multiple "optional" options appear in a technical solution, unless otherwise specified and there are no contradictions or mutual constraints, each "optional" option is independent.

[0049] In this application, the terms "first aspect," "second aspect," "third aspect," and "fourth aspect," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first," "second," "third," and "fourth," etc., serve only a non-exhaustive enumeration purpose and should be understood not to constitute a closed limitation on quantity.

[0050] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0051] In this application, numerical intervals (i.e., numerical ranges) are involved. Unless otherwise specified, the selected numerical distributions within the aforementioned numerical intervals are considered continuous and include the two endpoints (i.e., the minimum and maximum values) of the numerical range, as well as every value between these two endpoints. Unless otherwise specified, when a numerical interval refers only to integers within that interval, it includes the two endpoint integers of the numerical range, as well as every integer between the two endpoints. In this document, this is equivalent to directly listing every integer. For example, if t is an integer selected from 1 to 10, it means that t is any integer selected from the group of integers consisting of 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10. Furthermore, when multiple ranges are provided to describe features or characteristics, these ranges can be merged. In other words, unless otherwise specified, the ranges disclosed herein should be understood to include any and all subranges to which they are included.

[0052] Unless otherwise specified, the temperature parameters in this application are permitted to be either constant-temperature treatment or variations within a certain temperature range. It should be understood that the constant-temperature treatment allows temperature fluctuations within the precision range of the instrument control, such as ±5℃, ±4℃, ±3℃, ±2℃, or ±1℃.

[0053] In this application, unless otherwise specified, percentage contents refer to solid-liquid mixtures and solid phases. - Solid-phase mixing refers to mass percentage; for liquid phases... - Liquid phase mixing refers to volume percentage.

[0054] In this application, unless otherwise specified, percentage concentrations refer to final concentrations. Final concentration refers to the percentage of the added component in the system after its addition.

[0055] In this application, %(w / w) and wt% both represent weight percentage, %(v / v) refers to volume percentage, and %(w / v) refers to mass-volume percentage.

[0056] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0057] Furthermore, the accompanying drawings are not drawn to a 1:1 scale, and the relative dimensions of the elements are shown in the drawings only as examples to facilitate understanding of this application, but are not necessarily drawn to actual scale. The scales in the drawings do not constitute a limitation on this application.

[0058] This application provides a composite material, including a core material and a shell covering the core material. The core material is a composite of tin disulfide and detonated nanodiamond, and the shell material is graphene.

[0059] The composite material comprises, by mass percentage, 3% to 13% tin disulfide, 75% to 81% detonated nanodiamond, and 10% to 20% graphene.

[0060] The term "detonation" in detonation nanodiamonds specifically refers to the detonation method, a technique that uses the high temperature (above 3000℃) and high pressure (above 20 GPa) generated during the explosion of explosives to directly synthesize carbon elements from the explosives into nanodiamond particles. This method is one of the most traditional preparation methods for nanodiamonds and is commonly used in industrial-scale production. It typically uses explosives as precursors (using TNT and RDX explosives as raw materials). Under the high temperature and high pressure conditions of detonation, carbon atoms in the negative oxygen balance explosive that are not oxidized during detonation undergo a series of physicochemical processes, including aggregation and crystallization, to form nanoscale carbon particle clusters, which include diamond phase, graphite phase, and amorphous carbon. The non-diamond carbon phase is removed using an oxidant to obtain nanodiamonds, with a recovery rate of approximately 8-10% of the explosive mass used. After chemical purification, a purity of approximately 95-97% can be obtained.

[0061] Furthermore, the mass percentage of tin disulfide in the composite material may be, but is not limited to, 3%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, or 13%. The mass fraction of detonated nanodiamond in the composite material may be, but is not limited to, 75%, 76%, 77%, 78%, 79%, 80%, or 81%. The mass fraction of graphene in the composite material may be, but is not limited to, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, or 20%.

[0062] In a specific example, the particle size of the detonation nanodiamond is 5nm to 50nm. Specifically, the particle size of the detonation nanodiamond can be, but is not limited to, 5nm, 10nm, 15nm, 20nm, 25nm, 30nm, 35nm, 40nm, 45nm, or 50nm.

[0063] In a specific example, the thickness of the casing is 1nm to 10nm. Specifically, the thickness of the casing can be, but is not limited to, 1nm, 2nm, 3nm, 4nm, 5nm, 6nm, 7nm, 8nm, 9nm or 10nm.

[0064] In a specific example, the particle size of the composite material is 50 nm to 500 nm. The particle size of the composite material can be, but is not limited to, 50 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm or 500 nm.

[0065] This application utilizes graphene-coated detonation nanodiamonds and tin disulfide to form a core-like structure. - The shell-structured composite material has a stable structure that effectively suppresses the volume expansion of SnS2 during traditional charge and discharge processes, prevents the composite material from pulverizing, and constructs an efficient three-dimensional conductive network. This improves the rate performance and charge transport dynamics of the composite material as an electrode, and enhances cycle stability.

[0066] This application also provides a method for preparing a composite material, comprising the following steps:

[0067] Provide core material precursors, the materials of which include a composite of tin disulfide and detonation nanodiamond;

[0068] The core material precursor is placed in a reducing metal salt solution with a pH of 10-12. The reducing metal salt solution includes a reducing agent and a metal salt in a mass ratio of (0.5-2):1. The metal salt includes one of nickel salt, cobalt salt, and copper salt to form a core material template.

[0069] The core template is placed in a carbon source solution with a pH of 12-14 for carbonization and annealing. A shell is then coated on the surface of the core template. The shell material includes graphene to prepare a precursor for the composite material.

[0070] The composite material precursor was placed in an etching solution to prepare the composite material, wherein the mass percentage of tin disulfide in the composite material was 3%~13%, the mass percentage of detonated nanodiamond was 75%~81%, and the mass percentage of graphene was 10%~20%.

[0071] Understandably, the graphene coating here maintains the structural integrity of the composite particles on a macroscopic level and provides a conductive network and buffer layer in subsequent electrode fabrication; at the same time, its microscopic pores are sufficient to allow the etchant to "hollow out" the internal nickel template.

[0072] In one specific example, the preparation method of the core material precursor includes the solvothermal method.

[0073] In a specific example, the preparation method of the core material precursor includes the following steps:

[0074] Detonation nanodiamonds, tin source, sulfur source and solvent were mixed in a mass ratio of 100:(1~20):(0.5~10):(5000~8000) and reacted for 4 to 8 hours at a pressure of 1 atm~2 atm and a temperature of 150℃~200℃. The solid was separated to prepare the core material precursor.

[0075] Specifically, the reaction temperature may be, but is not limited to, 150°C, 160°C, 170°C, 180°C, 190°C, or 200°C. The reaction time may be, but is not limited to, 4 hours, 4.5 hours, 5 hours, 5.5 hours, 6 hours, 6.5 hours, 7 hours, 7.5 hours, or 8 hours.

[0076] In one specific example, the tin source includes one or both of tin tetrachloride and tin sulfate.

[0077] In a specific example, the sulfur source includes thiourea, L... - One or more of cysteine ​​and thioacetamide.

[0078] In one specific example, the solvent includes one or more of ethanol, ethylene glycol, and deionized water.

[0079] In one specific example, the reducing agent includes one or more of dimethylamine borane, sodium borohydride, and sodium hypophosphite.

[0080] In a specific example, the core material precursor is placed in the reducing metal salt solution for 20 min to 60 min. Specifically, the time the core material precursor is placed in the reducing metal salt solution can be, but is not limited to, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, or 60 min.

[0081] In one specific example, the carbonization temperature is 150°C to 200°C. The carbonization temperature can be, but is not limited to, 150°C, 160°C, 170°C, 180°C, 190°C, or 200°C.

[0082] In a specific example, the carbonization process takes 6 to 10 hours. The carbonization time can be, but is not limited to, 6 hours, 7 hours, 8 hours, 9 hours, or 10 hours.

[0083] In a specific example, the annealing temperature is 400℃~500℃. The annealing temperature may be, but is not limited to, 400℃, 410℃, 420℃, 430℃, 440℃, 450℃, 460℃, 470℃, 480℃, 490℃ or 500℃.

[0084] In a specific example, the annealing time is 0.5h to 2h. The annealing time can be, but is not limited to, 0.5h, 0.6h, 0.7h, 0.8h, 0.9h, 1h, 1.1h, 1.2h, 1.3h, 1.4h, 1.5h, 1.6h, 1.7h, 1.8h, 1.9h, or 2h.

[0085] In one specific example, the etching solution includes one or more of ferric chloride, hydrochloric acid, and nitric acid.

[0086] This application provides an electrode material, including the composite material as described above or the composite material prepared by the preparation method described above.

[0087] This application also provides a lithium-ion battery, including a positive electrode, a negative electrode, a separator, and an electrolyte. The separator is disposed between the positive electrode and the negative electrode. The positive electrode, the negative electrode, and the separator are immersed in the electrolyte. The material of the negative electrode includes the electrode materials described above.

[0088] To make the objectives, technical solutions, and advantages of this application clearer and more concise, the following specific embodiments are used for illustration, but this application is by no means limited to these embodiments. The embodiments described below are merely preferred embodiments of this application and can be used to describe this application, but should not be construed as limiting the scope of this application. It should be noted that any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

[0089] To better illustrate this application, the following description, in conjunction with specific embodiments, further explains its content. The following are specific embodiments.

[0090] The detonation nanodiamond BP powder was supplied by Guangzhou Quanta Electromechanical Co., Ltd. This detonation nanodiamond BP powder uses 2, 4, 6... - Trinitrotoluene was used as the carbon source and generated via detonation. The mixture obtained from the explosion chamber was dissolved in hydrochloric acid solution to remove metallic impurities, yielding a high-purity black-gray powder. The black-gray powder was then analyzed by inductively coupled plasma mass spectrometry (ICP-MS). -The microstructure was characterized by MS to investigate the trace elements. The results showed that apart from a small amount of residual ferrous iron (~200 µg / g), there were basically no other impurities.

[0091] Example 1

[0092] This embodiment provides a composite material including a core material and a shell covering the core material. The core material is made of tin disulfide loaded with detonated nanodiamond BP, and the shell material is made of graphene. The tin disulfide accounts for 4% of the mass of the composite material.

[0093] The preparation method of the above composite material includes the following steps:

[0094] (1) Preparation of detonation nanodiamond BP-SnS2 precursor by solvothermal method

[0095] The raw materials were weighed according to the mass ratio of detonated nanodiamond BP:SnCl4•5H2O:thiourea = 0.5g:0.048g:0.021g, dispersed in 40mL of anhydrous ethanol, and sonicated for 15min to ensure thorough dispersion. Then, the three solutions were mixed and stirred until a homogeneous mixture was formed. The mixture was transferred to a high-pressure reactor and reacted at 180℃ for 6 hours. After the reaction, the mixture was allowed to cool naturally, and the resulting product was centrifuged at 8000r / min for 6min. The supernatant was discarded, and the precipitate was washed three times with ethanol. Finally, the precipitate was dried in a vacuum oven at 80℃ to obtain the precursor of detonated nanodiamond BP-SnS2 composite particles.

[0096] (2) Electrodeposition and graphene coating

[0097] a. Nickel template deposition: The above-mentioned detonation nanodiamond BP-SnS2 composite particles were sequentially immersed in a primary nickel plating solution (containing 20 g / L NiSO4•6H2O, 10 g / L trisodium citrate dihydrate, and 5 g / L lactic acid) and a secondary nickel plating solution (concentration twice that of the primary solution, i.e., containing 40 g / L NiSO4•6H2O, 20 g / L trisodium citrate dihydrate, and 10 g / L lactic acid). In the primary nickel plating solution, a reducing agent dimethylamine borane (DMAB) (i.e., 1 g DMAB) was added at a concentration of approximately 5.56 g / L, and a pH adjuster ammonia water (28% concentration, i.e., 2 mL) was added at a concentration of approximately 11.11 mL / L. The mixture was gently stirred for 30 min. After centrifugation, the precipitate was transferred to a secondary nickel plating solution. DMAB (2 g) was added at a concentration of approximately 11.11 g / L, and ammonia (28% concentration, 3 mL) was added at a concentration of approximately 16.67 mL / L. The mixture was gently stirred for 30 min. The particles were collected by centrifugation, washed twice with ethanol, and dried in a vacuum oven at 60 °C to obtain detonation nanodiamond BP-SnS2@Ni particles.

[0098] b. Graphene layer formation: Detonation nanodiamond BP-SnS2@Ni particles were dispersed in a mixed solution of NaOH and triethylene glycol at a volume ratio of 0.0033:1, and carbonized at 185°C with stirring for 8 hours. Subsequently, the carbonized particles were annealed under an inert atmosphere, with the temperature increased to 100°C at 2°C / min, and then rapidly increased to 450°C at 20°C / min and held for 1 hour to catalyze the formation of a graphene layer.

[0099] c. Template Removal: The annealed composite precursor was immersed in a 1 mol / L FeCl3 solution for 2 hours to etch away the internal nickel template. The solid product was collected by centrifugation, washed three times with ethanol, and dried in a vacuum oven at 60°C for 6 hours to finally obtain a detonation nanodiamond BP / SnS2@GR composite material with a hollow graphene-coated structure, wherein the mass percentage of SnS2 was approximately 4%.

[0100] Example 2

[0101] The difference from Example 1 is that tin disulfide accounts for 8% of the mass of the composite material.

[0102] (1) Preparation of detonation nanodiamond BP-SnS2 precursor by solvothermal method

[0103] Using detonated nanodiamond BP, tin tetrachloride (SnCl4•5H2O), and thiourea as raw materials, the raw materials were weighed according to the mass ratio of detonated nanodiamond BP:SnCl4•5H2O:thiourea = 0.5 g:0.096 g:0.042 g. The above raw materials were dispersed separately in 40 mL of anhydrous ethanol and sonicated for 15 min to ensure thorough dispersion. Subsequently, the three solutions were mixed and stirred until a homogeneous mixture was formed. The mixture was transferred to a high-pressure reactor and reacted at 180 °C for 6 hours. After the reaction was completed, the mixture was allowed to cool naturally, and the resulting product was centrifuged at 8000 r / min for 6 min. The supernatant was discarded, and the resulting precipitate was washed three times with ethanol. Finally, the precipitate was dried in a vacuum oven at 80 °C to obtain the precursor of detonated nanodiamond BP-SnS2 composite particles.

[0104] (2) Electrodeposition and graphene coating

[0105] a. Nickel template deposition: The above-mentioned detonation nanodiamond BP-SnS2 composite particles were sequentially immersed in a primary nickel plating solution (containing 20 g / L NiSO4•6H2O, 10 g / L trisodium citrate dihydrate, and 5 g / L lactic acid) and a secondary nickel plating solution (concentration twice that of the primary solution, i.e., containing 40 g / L NiSO4•6H2O, 20 g / L trisodium citrate dihydrate, and 10 g / L lactic acid). In the primary nickel plating solution, a reducing agent dimethylamine borane (DMAB) (i.e., 1 g DMAB) was added at a concentration of approximately 5.56 g / L, and a pH adjuster ammonia water (28% concentration, i.e., 2 mL) was added at a concentration of approximately 11.11 mL / L. The mixture was gently stirred for 30 min. After centrifugation, the precipitate was transferred to a secondary nickel plating solution. DMAB (2 g) was added at a concentration of approximately 11.11 g / L, and ammonia (28% concentration, 3 mL) was added at a concentration of approximately 16.67 mL / L. The mixture was gently stirred for 30 min. The particles were collected by centrifugation, washed twice with ethanol, and dried in a vacuum oven at 60 °C to obtain detonation nanodiamond BP-SnS2@Ni particles.

[0106] b. Graphene layer formation: Dry detonation nanodiamond BP-SnS2@Ni particles were dispersed in a mixed solution of 150 mL triethylene glycol and 0.5 mL 50% NaOH solution (i.e., the volume ratio of NaOH solution to triethylene glycol was approximately 0.0033:1). The mixture was heated and stirred at 185 °C for 8 hours to perform carbonization. Subsequently, the carbonized particles were placed in a tube furnace and annealed under an inert atmosphere: the temperature was first increased to 100 °C at a rate of 2 °C / min, then rapidly increased to 450 °C at a rate of 20 °C / min, and held at this temperature for 1 hour to catalyze the formation of a graphene layer, thus obtaining the composite material precursor.

[0107] c. Template Removal: The annealed composite precursor was immersed in a 1 mol / L FeCl3 solution for 2 hours to etch away the internal nickel template. The solid product was collected by centrifugation, washed three times with ethanol, and dried in a vacuum oven at 60°C for 6 hours to finally obtain a detonation nanodiamond BP / SnS2@GR composite material with a hollow graphene-coated structure, wherein the mass percentage of SnS2 was approximately 8%.

[0108] Example 3

[0109] The difference from Example 1 is that tin disulfide accounts for 12% of the mass of the composite material.

[0110] (1) Preparation of detonation nanodiamond BP-SnS2 precursor by solvothermal method: Detonation nanodiamond BP, tin tetrachloride (SnCl4•5H2O) and thiourea were weighed according to the mass ratio of detonation nanodiamond BP:SnCl4•5H2O:thiourea = 0.48g:0.14g:0.063g and dispersed in 40mL of anhydrous ethanol. The mixture was ultrasonically treated for 15min to ensure thorough dispersion. Subsequently, the three solutions were mixed and stirred until a homogeneous mixture was formed. The mixture was placed in a high-pressure reactor and reacted at 170℃ for 7 hours. After the reaction was completed, the mixture was naturally cooled, and the resulting product was centrifuged at 8000r / min for 6min. The supernatant was discarded, and the precipitate was washed three times with ethanol. Finally, the precipitate was dried in a vacuum oven at 80℃ to obtain the detonation nanodiamond BP-SnS2 composite particle precursor.

[0111] (2) Electroless deposition and graphene coating: a. Nickel template deposition: The above-mentioned detonation nanodiamond BP-SnS2 composite particles were sequentially immersed in a primary nickel plating solution (containing 20 g / L NiSO4•6H2O, 10 g / L trisodium citrate dihydrate, and 5 g / L lactic acid) and a secondary nickel plating solution (the concentration was twice that of the primary solution, i.e., containing 40 g / L NiSO4•6H2O, 20 g / L trisodium citrate dihydrate, and 10 g / L lactic acid). In the primary nickel plating solution, a reducing agent dimethylamine borane (DMAB) (i.e., 1 g DMAB) was added at a concentration of approximately 5.56 g / L, and a pH adjusting agent ammonia water (28% concentration, i.e., 2 mL) was added at a concentration of approximately 11.11 mL / L, and the solution was gently stirred for 25 min. After centrifugation, the precipitate was transferred to a secondary nickel plating solution. DMAB (approximately 2 g) was added at a concentration of approximately 11.11 g / L, and ammonia solution (28% concentration, approximately 3 mL) was added at a concentration of approximately 16.67 mL / L. The mixture was gently stirred for 25 min. The particles were collected by centrifugation, washed twice with ethanol, and dried in a vacuum oven at 60 °C to obtain detonation nanodiamond BP-SnS2@Ni particles.

[0112] b. Graphene layer formation: Detonation nanodiamond BP-SnS2@Ni particles were dispersed in a mixed solution of NaOH (50% concentration) and triethylene glycol at a volume ratio of 0.005:1. The mixture was heated and stirred at 185°C for 7 hours for carbonization. Subsequently, the carbonized particles were annealed under an argon atmosphere, with the temperature increased to 100°C at a rate of 2°C / min, and then rapidly increased to 450°C at a rate of 20°C / min and held at that temperature for 1.5 hours to catalyze the formation of a graphene layer.

[0113] c. Template removal: The annealed particles were immersed in 1 mol / L FeCl3 etching solution for 2 h to remove the internal nickel template. They were then washed with deionized water and ethanol, and vacuum dried to finally obtain the detonation nanodiamond BP / SnS2@GR composite material with a hollow graphene-coated structure.

[0114] Example 4

[0115] This embodiment provides a composite material, including a core material and a shell covering the core material. The core material is a composite of tin disulfide and detonated nanodiamond (BP), and the shell material is graphene. Tin disulfide accounts for 8% of the mass of the composite material.

[0116] The preparation method of the above composite material includes the following steps:

[0117] (1) Preparation of detonation nanodiamond BP-SnS2 precursor by solvothermal method: The raw materials were weighed at a mass ratio of BP:SnCl4•5H2O:thiourea = 0.5g:0.096g:0.042g and dispersed in 40mL of anhydrous ethanol. The mixture was ultrasonicated, mixed, and stirred to form a homogeneous solution. The mixed solution was placed in a high-pressure reactor and reacted at 160℃ for 8 hours. After the reaction was completed, the precursor of detonation nanodiamond BP-SnS2 composite particles was obtained by centrifugation, washing with ethanol, and vacuum drying.

[0118] (2) Direct mixing - Preparation of graphene coatings by thermal reduction method (template-free method):

[0119] a. Graphene precursor loading: The above-mentioned detonation nanodiamond BP-SnS2 precursor particles were dispersed in an aqueous solution of graphene oxide (GO) (concentration of 2 mg / mL), wherein the mass ratio of detonation nanodiamond BP-SnS2 to GO was 10:1. The mixture was ultrasonically treated for 1 h to ensure uniform mixing, and then stirred and evaporated to dryness at 60 °C to obtain GO-coated detonation nanodiamond BP-SnS2@GO composite particles.

[0120] b. Thermal reduction treatment: The detonated nanodiamond BP-SnS2@GO composite particles were placed in a tube furnace and heated to 700℃ at 5℃ / min under an argon atmosphere and held for 2h to thermally reduce graphene oxide to graphene, thus obtaining the detonated nanodiamond BP / SnS2@GR composite material.

[0121] Comparative Example 1

[0122] This comparative example provides a pure detonation nanodiamond BP@GR composite material, which includes only a detonation nanodiamond BP core and a graphene shell covering the core, and the composite material does not contain tin disulfide (SnS2).

[0123] The preparation method of the above-mentioned pure detonation nanodiamond BP@GR composite material includes the following steps:

[0124] (1) Pretreatment of detonation nanodiamond BP precursor

[0125] Weigh 0.5 g of detonated nanodiamond (BP) and add it to 40 mL of anhydrous ethanol. Disperse the mixture ultrasonically for 15 min to obtain a uniform suspension of detonated nanodiamond (BP). This suspension is not mixed with other raw materials and is directly used for subsequent coating treatment. These detonated nanodiamond (BP) particles serve as the core material precursor.

[0126] (2) Electrodeposition and graphene coating

[0127] a. Nickel template deposition: The above-mentioned detonated nanodiamond BP particles were sequentially immersed in a primary nickel plating solution (containing 20 g / L NiSO4•6H2O, 10 g / L trisodium citrate dihydrate, and 5 g / L lactic acid) and a secondary nickel plating solution (with a concentration twice that of the primary solution). During each immersion, dimethylamine borane (DMAB), a reducing agent, was added to the nickel plating solution at a concentration of 5 g / L to 15 g / L, and ammonia water (28% concentration), a pH adjuster, was added at a concentration of 10 mL / L to 20 mL / L. The mixture was gently stirred for 30 min to reduce nickel ions to metallic nickel and uniformly coat the surface of the detonated nanodiamond BP particles. After centrifugation, washing, and drying, detonated nanodiamond BP@Ni particles were obtained.

[0128] b. Graphene layer formation: Detonation nanodiamond BP@Ni particles were dispersed in a mixed solution of NaOH (50% concentration) and triethylene glycol at a volume ratio of (0.001~0.01):1 (total volume 150 mL). The mixture was heated and stirred at 185 °C for 8 h for carbonization. Subsequently, the carbonized particles were placed in a tube furnace and annealed under an inert atmosphere: the temperature was increased to 100 °C at 2 °C / min, then rapidly increased to 450 °C at 20 °C / min and held for 1 h to catalyze the formation of a graphene layer.

[0129] c. Template removal: The annealed particles were immersed in a 1 mol / L FeCl3 solution for 2 h to etch and remove the internal nickel template. They were then washed with deionized water and ethanol and dried under vacuum at 60 °C to finally obtain pure detonation nanodiamond BP@GR composite material.

[0130] Comparative Example 2

[0131] This comparative example provides a composite material whose core material comprises cobalt tetroxide (Co3O4) supported on detonated nanodiamond BP, and whose shell material is graphene. The mass percentage of Co3O4 in the composite material is 8%.

[0132] The preparation method of the above composite material includes the following steps:

[0133] (1) Preparation of detonation nanodiamond BP by solvothermal method - The Co3O4 precursor was prepared using detonated nanodiamond BP and cobalt chloride hexahydrate (CoCl2•6H2O) in a mass ratio. 0.5 g of detonated nanodiamond BP and a corresponding mass (based on a theoretical Co3O4 loading of 8 wt%) of CoCl2•6H2O were weighed and dispersed separately in a mixed solvent of 40 mL anhydrous ethanol and a small amount of deionized water. After mixing the two solutions, an appropriate amount of urea was added as a precipitant, and the mixture was stirred until homogeneous. The mixed solution was placed in a high-pressure reactor and reacted at 180 °C for 6 hours. After the reaction, the mixture was centrifuged, washed with ethanol, and vacuum dried to obtain detonated nanodiamond BP. - Co3O4 composite particle precursor.

[0134] (2) Electrodeposition and graphene coating

[0135] a. Nickel template deposition: This step is exactly the same as in Example 2. The above-mentioned detonation nanodiamond BP... - Co3O4 composite particles were sequentially immersed in a primary nickel plating solution and a secondary nickel plating solution (concentrations the same as in Example 2). During each immersion, dimethylamine borane (DMAB) as a reducing agent and ammonia as a pH adjuster were added at the same concentration, and the mixture was gently stirred for 30 minutes to form detonation nanodiamond BP. - Co3O4@Ni particles.

[0136] b. Graphene layer formation: The steps are exactly the same as in Example 2. Detonation nanodiamond BP... - Co3O4@Ni particles were dispersed in a mixed solution of triethylene glycol and NaOH and carbonized at 185°C for 8 hours, followed by annealing under an inert atmosphere (450°C, 1 hour) to catalyze the formation of a graphene layer.

[0137] c. Template removal: The procedure is exactly the same as in Example 2. The annealed particles were immersed in a 1 mol / L FeCl3 solution for 2 hours to etch and remove the nickel template, finally obtaining the detonation nanodiamond BP / Co3O4@GR composite material.

[0138] Performance Comparison and Conclusion Analysis

[0139] Figure 1The images show scanning electron microscope (SEM) images of the composite materials from Examples 1 to Comparative Examples 1; (a) is the composite material of Comparative Example 1, (b) is the composite material of Example 1, (c) is the composite material of Example 2, and (d) is the composite material of Example 3. The SEM images show that when the SnS2 doping content in Example 2 is 8 wt%, the composite material exhibits the most porous yet compact aggregate structure, with the best graphene sheet coating effect, effectively buffering volume expansion. Figure 2 The images show the X-ray diffraction patterns of the composite materials from Examples 1 to Comparative Examples 1. XRD analysis confirmed that SnS2 was successfully doped without disrupting the crystal structure of the detonation nanodiamond BP. Figure 3 Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) curves of the composite materials of Example 2 and Comparative Example 1 are shown. (Thermogravimetric analysis and differential scanning calorimetry (DSC)...) - The DSC curve indicates that the composite material has suitable thermal stability and carbon content. Figure 4 The image shows the Raman spectrum of the composite material from Example 2. The Raman spectroscopy (I_D / I_G=0.75) confirms that the formed carbon layer is graphene with a high degree of order.

[0140] The composite materials from the above embodiments and comparative examples were assembled into half-cells, specifically CR2025 coin cells. The prepared composite material was used as the working electrode, a lithium sheet as the counter electrode, and Celgard 2400 as the separator. The electrolyte solute was 1 mol / L LiPF6, and the solvent was 89 vol% DEC / EC (1:1), 1 vol% VC, and 10% FEC. Electrical performance tests were performed; the results are shown in Table 1 below. Figure 5 The constant current charge-discharge specific capacity curves of lithium-ion batteries using the composite materials of Examples 1 to Comparative Examples 1 as negative electrodes, and the coulombic efficiency curve of lithium-ion batteries using the composite material of Example 2 as negative electrodes are shown in the figure. Figure 6 The rate performance curves of lithium-ion batteries using the composite materials of Examples 1 to Comparative Examples 1 as negative electrodes are shown.

[0141] Table 1

[0142]

[0143] It is evident that the composite material provided in this application, when used as the negative electrode of a lithium-ion battery, achieves a first-cycle charge-discharge specific capacity of up to 1293 mAh•g. -1 (The composite material of Example 2) is far superior to that of pure detonation nanodiamond BP@GR in Comparative Example 1 (474 ​​mAh•g). -1 Excellent cycling stability: The composite material of Example 2 exhibits excellent cycling stability at 0.1 A•g. -1 After 50 cycles at the current density, it still maintains 80 mAh•g. -1The specific capacity and capacity retention of this sample are significantly better than those of other samples, and the coulombic efficiency remains stable at over 99%. Furthermore, although Example 4 also uses graphene as a coating layer, the coating effect is not as good as the coating layer prepared using the template method.

[0144] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0145] The embodiments described above merely illustrate several implementation methods of this application to facilitate a detailed understanding of the technical solutions of this application, but should not be construed as limiting the scope of protection of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the scope of protection of this application. It should be understood that technical solutions obtained by those skilled in the art based on the technical solutions provided in this application through logical analysis, reasoning, or limited experimentation are all within the scope of protection of the appended claims. Therefore, the scope of protection of this patent application should be determined by the content of the appended claims, and the specification and drawings can be used to interpret the content of the claims.

Claims

1. A composite material, characterized in that, The device includes a core material and a shell covering the core material. The core material is a composite of tin disulfide and detonated nanodiamond, and the shell material is graphene. The composite material comprises, by mass percentage, 3% to 13% tin disulfide, 75% to 81% detonated nanodiamond, and 10% to 20% graphene.

2. The composite material as described in claim 1, characterized in that, One or two of the following conditions must be met: (1) The particle size of the detonation nanodiamond is 5nm~50nm; (2) The thickness of the outer shell is 1nm~10nm.

3. The composite material as described in claim 1 or 2, characterized in that, The particle size of the composite material is 50nm~500nm.

4. A method for preparing a composite material, characterized in that, Includes the following steps: A core material precursor is provided, wherein the material of the core material precursor comprises a composite of tin disulfide and detonated nanodiamond. The core material precursor is placed in a reducing metal salt solution with a pH of 10-12. The reducing metal salt solution includes a reducing agent and a metal salt in a mass ratio of (0.5-2):

1. The metal salt includes one of a nickel salt, a cobalt salt, and a copper salt to form a metal template for the core material. The metal template of the core material is placed in a carbon source solution with a pH of 12-14 for carbonization and annealing. A shell is then coated on the surface of the core material template. The shell material includes graphene to prepare a composite material precursor. The composite material precursor is placed in an etching solution to remove the metal template and prepare the composite material, wherein the composite material comprises, by mass percentage, 3% to 13% tin disulfide, 75% to 81% detonated nanodiamond, and 10% to 20% graphene.

5. The method for preparing the composite material as described in claim 4, characterized in that, The preparation method of the core material precursor includes the solvothermal method.

6. The method for preparing the composite material as described in claim 5, characterized in that, The preparation method of the core material precursor includes the following steps: The detonation nanodiamond, tin source, sulfur source and solvent are mixed in a mass ratio of 100:(1~20):(0.5~10):(5000~8000) and reacted at a temperature of 150℃~200℃ for 4 to 8 hours. The solid is then separated to prepare the core material precursor.

7. The method for preparing the composite material as described in claim 6, characterized in that, One or more of the following conditions must be met: (1) The tin source includes one or both of tin tetrachloride and tin sulfate; (2) The sulfur source includes thiourea, L - One or more of cysteine ​​and thioacetamide; (3) The solvent includes one or more of ethanol, ethylene glycol and water.

8. The method for preparing the composite material according to any one of claims 4 to 7, characterized in that, One or more of the following conditions must be met: (1) The reducing agent includes one or more of dimethylamine borane, sodium borohydride and sodium hypophosphite; (2) The core material precursor is placed in the reducing metal salt solution for 20 min to 60 min; (3) The carbonization temperature is 150℃~200℃; (4) The carbonization treatment time is 6h~10h; (5) The annealing temperature is 400℃~500℃; (6) The annealing time is 0.5h~2h; (7) The etching solution includes one or more of ferric chloride, hydrochloric acid and nitric acid.

9. An electrode material, characterized in that, This includes the composite material as described in any one of claims 1 to 3 or the composite material prepared by the preparation method as described in any one of claims 4 to 8.

10. A lithium-ion battery, characterized in that, The device includes a positive electrode, a negative electrode, a separator, and an electrolyte. The separator is disposed between the positive electrode and the negative electrode. The positive electrode, the negative electrode, and the separator are immersed in the electrolyte. The negative electrode includes the electrode material as described in claim 9.

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