Composite material, preparation method thereof, negative electrode material, negative electrode sheet and battery

Abstract

The application provides a composite material and a preparation method thereof, a negative electrode material, a negative electrode sheet and a battery. The composite material comprises a silicon oxide / carbon / tin sulfide composite. The silicon oxide / carbon / tin sulfide composite comprises a silicon oxide / carbon material and tin sulfide particles, and the tin sulfide particles are dispersed in the silicon oxide / carbon material. The composite material has the characteristics of high capacity, small volume effect, good electronic conductivity and good rate performance.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a composite material and a preparation method thereof, a negative electrode material, a negative electrode sheet and a battery. Background Art

[0002] Currently, the primary negative electrode material for commercial lithium-ion batteries is graphite, which offers advantages such as low cost, low charge-discharge plateau, and good stability. However, graphite has a theoretical capacity of only 372 mA·h / g. This low theoretical capacity limits its application in power batteries and large-scale energy storage applications where high energy density, power density, and fast charging are required. Compared to graphite, tin-based sulfides have a higher theoretical capacity and are expected to become the negative electrode material for the next generation of lithium-ion batteries. However, tin-based sulfide materials, such as tin sulfide, experience a severe volume effect during the charge-discharge process. These materials continuously expand and contract, leading to pulverization and the rupture and reformation of the SEI film. This results in a continuous decrease in the capacity of the tin-based sulfide materials, as well as poor conductivity and unsatisfactory rate performance.

[0003] Currently, the preparation of low-cost modified tin-based sulfide materials is gaining increasing attention for use as negative electrode materials in lithium-ion batteries. Currently, the main methods for modifying tin-based negative electrode materials include morphology control and carbon coating. However, simply manipulating the morphology results in difficult-to-control particle size distribution and large particle sizes. Furthermore, common carbon coatings or carbon composites reduce the overall material capacity and poor conductivity. Summary of the Invention

[0004] In view of this, the purpose of this application is to provide a composite material with high capacity, small volume effect, good electronic conductivity and good rate performance, and its preparation method, negative electrode material, negative electrode sheet and battery.

[0005] To achieve the above objectives, this application provides the following technical solutions:

[0006] A composite material includes a silicon oxycarbide / tin sulfide compound. The silicon oxycarbide / tin sulfide compound includes silicon oxycarbide material and tin sulfide particles. The tin sulfide particles are dispersed inside the silicon oxycarbide material.

[0007] In some embodiments, the tin sulfide particles account for 15 wt% to 60 wt% of the composite material, and the silicon oxycarbide material accounts for 40 wt% to 85 wt% of the composite material.

[0008] In some embodiments, the silicon oxycarbide / tin sulfide composite has a particle size of 2 μm to 6 μm.

[0009] In some embodiments, the particle size of the tin sulfide particles is 10 nm to 50 nm.

[0010] In some embodiments, the tin sulfide particles are uniformly distributed in the silicon oxycarbide material.

[0011] The application also provides a method for preparing a composite material, comprising:

[0012] mixing raw materials including a siloxane polymer, an organic solvent and a sulfur-containing organotin source to obtain a precursor polymer gel;

[0013] subjecting the precursor polymer gel to heat treatment in a protective atmosphere or a vacuum environment to obtain a silicon oxycarbide / tin sulfide composite.

[0014] In some embodiments, the process of mixing raw materials including a siloxane polymer, an organic solvent and a sulfur-containing organotin source comprises:

[0015] mixing and reacting a siloxane polymer, an organic solvent and a catalyst to obtain a modified siloxane polymer;

[0016] mixing the modified siloxane polymer with the sulfur-containing organotin source.

[0017] In some embodiments, the catalyst includes at least one of chloroplatinic acid, 1,3 divinyl 1,1,3,3 tetramethyldisiloxane platinum complex, dicyclopentadiene platinum complex, palladium chloride, palladium tris-triphenylphosphine, rhodium trisphenylphosphine, dicobalt octacarbonyl, nickel tetracarbonyl and chromium hexacarbonyl.

[0018] In some embodiments, the time for mixing and reacting the siloxane polymer, the organic solvent and the catalyst is 0.5h-2h.

[0019] In some embodiments, the ratio of the amount of the siloxane polymer to the amount of the catalyst is (1-3)g / (5-15)μl.

[0020] In some embodiments, after mixing and reacting the modified siloxane polymer with the sulfur-containing organotin source, a step of standing is further included; preferably, the time for standing is 3h-6h.

[0021] In some embodiments, the siloxane polymer includes at least one of polysiloxane, polymethylsiloxane and polydimethylsiloxane.

[0022] In some embodiments, the organic solvent includes at least one of dimethylbenzene, tetrahydrofuran, cyclohexanone, ethylene glycol dimethyl ether and dimethyl phthalate.

[0023] In some embodiments, the sulfur-containing organotin source is selected from sulfur-containing organotin sources with carbon-carbon chain ≥6.

[0024] In some embodiments, the sulfur-containing organotin source includes at least one of isooctyl dimethyl tin dithioacetate, bis(dodecylthio)dimethyl tin, bis(dodecylthio) dibutyl tin, and diisooctyl 2,2'-[(dimethyltin)bis(thio)]dibenzoate.

[0025] In some embodiments, the protective atmosphere includes at least one of helium, neon, argon, and nitrogen.

[0026] In some embodiments, the mass ratio of the organic solvent to the siloxane polymer is (2-5):1.

[0027] In some embodiments, the mass ratio of the sulfur-containing organotin source to the siloxane polymer is (0.5-2):1.

[0028] In some embodiments, the method further includes, before the heat treatment, activating the precursor polymer gel.

[0029] In some embodiments, the activation is performed at a temperature of 80-120℃ for 24-48 hours.

[0030] In some embodiments, the heat treatment is performed at a temperature of 800-1200℃ for 1-6 hours.

[0031] The application also provides a negative electrode material, which includes the composite material described above or the composite material prepared by the method described above.

[0032] The application also provides a battery negative electrode sheet, which includes the negative electrode material described above.

[0033] The application also provides a battery, which includes the battery negative electrode sheet described above.

[0034] In some embodiments, the battery is a lithium ion battery.

[0035] The application has the following advantages:

[0036] (1) The composite material of the application includes a silicon oxycarbide / tin sulfide composite, which includes a silicon oxycarbide material and tin sulfide particles, and the tin sulfide particles are dispersed in the silicon oxycarbide material, and the composite material has the characteristics of high capacity, small volume effect, good electronic conductivity, and good rate performance.

[0037] (2) The preparation method of the composite material of the present application, by mixing raw materials including siloxane polymer, organic solvent and sulfur-containing organotin source, a precursor polymer gel is obtained; then the precursor polymer gel is heat treated in a protective atmosphere or a vacuum environment to form pores, while the tin sulfide particles grow in these pores, the pores limit the growth space of the tin sulfide particles, control the particle size and particle size distribution range of the tin sulfide particles; there is no chemical reaction between the sulfur-containing organotin source and the siloxane polymer, so that the tin sulfide particles can be uniformly dispersed in the carbon-silicon oxide material; the carbon-silicon oxide material contains a large amount of amorphous carbon, which does not reduce the capacity of the composite material; moreover, the carbon-silicon oxide material itself has small volume effect in the charging and discharging process, which helps to buffer the volume expansion change of the tin sulfide particles, thereby avoiding the pulverization failure of the tin sulfide particles in the charging and discharging process, so that the capacity performance of the tin sulfide particles can be stably played, at the same time, the agglomeration of the tin sulfide particles in the process of lithium extraction is prevented, and the carbon-silicon oxide material has high electronic conductivity, so that the obtained composite material has the characteristics of high capacity, small volume effect, good electronic conductivity and good rate performance;

[0038] In addition, the preparation method of the present application is simple, green and pollution-free, suitable for large-scale production, and has a broad market application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0039] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope of the present application.

[0040] Figure 1 The preparation method flow chart of the composite negative electrode material provided by the embodiments of the present application;

[0041] Figure 2 The XRD spectrum of the carbon-silicon oxide / tin sulfide composite material obtained in Example 1;

[0042] Figure 3a The SEM morphology diagram of the carbon-silicon oxide / tin sulfide composite material obtained in Example 1;

[0043] Figure 3b The TEM morphology diagram of the carbon-silicon oxide / tin sulfide composite material obtained in Example 1;

[0044] Figure 4 The Raman spectrum of the carbon-silicon oxide / tin sulfide composite material obtained in Example 1;

[0045] Figure 5 The different rate performance diagram of the battery corresponding to the carbon-silicon oxide / tin sulfide composite material obtained in Example 1;

[0046] Figure 6 The cycle performance of the assembled battery for the silicon oxide / tin sulfide composite material obtained in Example 1 was measured at a current density of 3 A / g. DETAILED DESCRIPTION

[0047] For the purpose of understanding the present application, the technical solutions of the present application are described in detail below in the manner of examples, and numerous specific details are set forth in the following description in order to provide a thorough understanding of the present application.

[0048] However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of the present application, and therefore the present application is not limited to the specific implementation disclosed below.

[0049] 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. If there is a conflict between the definitions in the specification and those in the patent specification, the definitions in the specification are intended to prevail.

[0050] As used herein the terms "about" or "approximately" mean ±10% of the value being described.

[0051] "Made from" is synonymous with "comprising". The terms "comprising", "including", "having" or "with" or any other variation thereof, as used herein, are intended to cover a non-exclusive inclusion. For example, a composition, step, method, article, or apparatus that comprises a list of elements is not necessarily limited to those elements but can include other elements not expressly listed or inherent to such composition, step, method, article, or apparatus.

[0052] The transitional phrase "consisting of" excludes any element, step, or ingredient not specified. If used in the claims, this phrase shall not be construed to bring within the scope of the claims any element not specified in the claim's body. The phrase "consisting of" is closed, whereas the phrase "consisting essentially of" is open-ended. The phrase "consisting essentially of" excludes from the scope of any succeeding claim any element not specified in the claim's body, but does not exclude materials or steps that affect the basic and novel characteristics of the composition, method, or article.

[0053] When equivalent, concentration, or other value or parameter is expressed in a range, a preferred range, or a range having an upper preferred value and a lower preferred value, it is understood that all ranges formed by any pair of an upper range limit or a preferred value and a lower range limit or a preferred value, regardless of whether the range is expressly disclosed, are specifically disclosed. For example, when a range "1-5" is disclosed, the described range should be interpreted to include ranges "1-4", "1-3", "1-2", "1-2 and 4-5", "1-3 and 5", etc. When numerical ranges are described herein, unless otherwise stated, the range is intended to include the endpoints and all integers and fractions within that range.

[0054] In these examples, the parts and percentages are by mass unless otherwise indicated.

[0055] "Parts by mass" refers to a basic unit of measurement that represents the mass ratio relationship of multiple components, 1 part can represent any unit mass, such as 1 g, 2.689 g, etc. If we say that the mass of component A is a parts, and the mass of component B is b parts, it means that the ratio of the mass of component A to the mass of component B is a:b. Alternatively, it means that the mass of component A is aK, and the mass of component B is bK (K is an arbitrary number, indicating a multiple factor). It should not be misunderstood that, unlike parts by mass, the sum of the parts by mass of all components is not limited to 100 parts.

[0056] "And / or" is used to indicate that one or both of the described situations can occur, for example, A and / or B includes (A and B) and (A or B).

[0057] The present application provides a composite material, comprising a silicon oxycarbide / tin sulfide (i.e. SiOC / SnS) composite; the silicon oxycarbide / tin sulfide composite comprises a silicon oxycarbide material and tin sulfide particles, the tin sulfide particles are dispersed in the silicon oxycarbide material, i.e. the silicon oxycarbide material coats the tin sulfide particles.

[0058] In some embodiments, the above-mentioned tin sulfide particles account for 15wt%-60wt% of the composite material, and the silicon oxycarbide material accounts for 40wt%-85wt% of the composite material.

[0059] In some embodiments, the above-mentioned silicon oxycarbide / tin sulfide composite has a particle size of 2-6 μm.

[0060] In some embodiments, the above-mentioned tin sulfide particles have a particle size of 10-50 nm.

[0061] In some embodiments, the above-mentioned tin sulfide particles are uniformly distributed in the silicon oxycarbide material.

[0062] Since the silicon oxycarbide material contains a large amount of amorphous carbon, it itself has a capacity of up to 600 mA·h / g, which does not reduce the capacity of the composite material; moreover, the silicon oxycarbide material itself has a small volume effect in the charging and discharging process, and has a high electronic conductivity, which helps to buffer the volume expansion change of the tin sulfide particles, thereby avoiding the pulverization failure of the tin sulfide particles in the charging and discharging process, and the capacity performance can be stably played. At the same time, it prevents the agglomeration of tin sulfide particles in the process of deintercalating lithium, so that the composite material has the characteristics of high capacity, small volume effect, good electronic conductivity and good rate performance.

[0063] The present application also provides a preparation method of the above-mentioned composite material, such as Figure 1As shown, comprising:

[0064] S10, raw materials including siloxane polymer, organic solvent and sulfur-containing organotin source are mixed to obtain a precursor polymer gel.

[0065] In some embodiments, the process of mixing raw materials including siloxane polymer, organic solvent and sulfur-containing organotin source specifically comprises:

[0066] S101, the siloxane polymer, organic solvent and catalyst are mixed and stirred to obtain a modified siloxane polymer; the siloxane polymer includes but is not limited to at least one of polysiloxane, polymethylsiloxane and polydimethylsiloxane; the organic solvent includes but is not limited to at least one of dimethylbenzene, tetrahydrofuran, cyclohexanone, ethylene glycol dimethyl ether and dimethyl phthalate; the catalyst includes but is not limited to at least one of chloroplatinic acid H2PtCl6, 1,3 divinyl 1,1,3,3 tetramethyldisiloxane platinum Pt(dvs), dicyclopentadiene platinum Pt(dcp), palladium chloride PdCl2, tetraphenylphosphine palladium Pd(Ph3P)4, triphenylphosphine rhodium chloride RhCl(Ph3P)3, octacarbonyl dicobalt Co2(CO)8, tetracarbonylnickel Ni(CO)4 and hexacarbonyl chromium Cr(CO)6.

[0067] In some embodiments, the temperature of the above-mentioned siloxane polymer, organic solvent and catalyst mixing reaction is 25-35°C, and the time is 0.5-2h.

[0068] In some embodiments, the amount ratio of siloxane polymer to catalyst is (1-3)g / (5-15)μl; the mass ratio of organic solvent to siloxane polymer is (2-5):1.

[0069] The above-mentioned modified siloxane polymer is prepared by adding siloxane polymer and catalyst to organic solvent, stirring at room temperature 25-35°C for 0.5-2h. In this process, the polarity of the side chain of the siloxane polymer is improved by hydrosilylation reaction, which is more conducive to the subsequent uniform mixing of the sulfur-containing organotin source, and makes the final tin sulfide particle distribution more uniform.

[0070] S102, the modified siloxane polymer is mixed with a sulfur-containing organotin source with a carbon-carbon chain ≥6; the longer the carbon-carbon chain of the sulfur-containing organotin source, the smaller the polarity, the more conducive to mutual solubility with the modified siloxane polymer, making the tin sulfide particle distribution in the final product more uniform; the sulfur-containing organotin source with a carbon-carbon chain ≥6 includes but is not limited to at least one of diisooctyl dimethyl tin dithioacetate, bis(dodecylthio)dimethyl tin, bis(dodecylthio)dibutyl tin and 2,2'-[(dimethyltin)bis(thio)]diisooctyl acetate.

[0071] Further, the modified siloxane polymer is mixed with the sulfur-containing organotin source and then a step of standing is further included; preferably, the standing time is 3-6 hours.

[0072] In some embodiments, the mass ratio of the sulfur-containing organotin source to the siloxane polymer is (0.5-2):1.

[0073] It should be noted that in the preparation of the precursor polymer gel, the mass ratio of the sulfur-containing organotin source to the siloxane polymer needs to be controlled within the above range (i.e. (0.5-2):1). If the mass ratio is higher than the above range, the content of the tin sulfide particles in the composite material is too high, which can result in poor cycle performance of the composite material. If the mass ratio is lower than the above range, the content of the tin sulfide particles in the composite material is too low, which can result in low capacity of the composite material.

[0074] S20, heat-treating the precursor polymer gel in a protective atmosphere or a vacuum environment to obtain a silicon oxycarbide / tin sulfide composite.

[0075] Further, the above heat-treatment further includes activating the precursor polymer gel.

[0076] In some embodiments, the temperature of the above activation treatment is 80-120°C, and the time is 24-48 hours. The activation treatment is beneficial to improving the pore structure and surface morphology of the carbon oxycarbide coating layer, and is also beneficial to uniform distribution of the particle size of the tin sulfide particles after high-temperature pyrolysis.

[0077] In some embodiments, the protective atmosphere includes at least one of helium, neon, argon and nitrogen.

[0078] In some embodiments, the temperature of the above heat-treatment is 800-1200°C, and the time is 1-6 hours.

[0079] It should be noted that in the above heat-treatment, the heat-treatment temperature needs to be controlled within the above range. If the temperature of the heat-treatment is lower than 800°C, the carbonization effect is poor, which can result in low capacity of the composite material. If the temperature of the heat-treatment is higher than 1200°C, the amorphous carbon of the obtained silicon oxycarbide material is reduced, which is not beneficial to the rate performance of the composite material.

[0080] The present application obtains a precursor polymer gel by mixing raw materials including a siloxane polymer, an organic solvent and a sulfur-containing organotin source; then the precursor polymer gel is heat treated in a protective atmosphere or a vacuum environment to form pores, which not only limits the growth space of the tin sulfide particles, but also controls the particle size distribution of the tin sulfide particles; there is no reaction between the sulfur-containing organotin source and the siloxane polymer, so that the tin sulfide particles can be uniformly dispersed in the silicon oxycarbide; the silicon oxycarbide material contains a large amount of amorphous carbon, so that it itself has a capacity as high as 600 mA·h / g, which will not reduce the capacity of the composite material; moreover, the silicon oxycarbide itself has a small volume effect in the charging and discharging process, which helps to buffer the volume expansion change of the tin sulfide particles, thereby avoiding the pulverization failure of the tin sulfide particles in the charging and discharging process, so that the capacity performance of the tin sulfide particles can be stably played, and at the same time, the agglomeration of the tin sulfide particles in the process of deintercalating lithium is prevented, and the silicon oxycarbide material has high electronic conductivity, so that the obtained composite material has the characteristics of high capacity, small volume effect, good electronic conductivity and good rate performance.

[0081] The present application also provides a negative electrode material comprising the composite material or the composite material prepared by the preparation method described above.

[0082] The present application also provides a battery negative electrode sheet comprising the negative electrode material described above.

[0083] The present application also provides a battery comprising the battery negative electrode sheet described above; preferably, the battery can be listed as a lithium ion battery, a sodium ion battery or a potassium ion battery, preferably a lithium ion battery.

[0084] The embodiments of the present application will be described in detail below with specific examples, but those skilled in the art will understand that the following examples are only for illustration of the present application and should not be regarded as limiting the scope of the present application. If the specific conditions are not specified in the examples, the conventional conditions or the conditions recommended by the manufacturer are used. If the reagents or instruments used are not specified by the manufacturer, they are all conventional products that can be purchased on the market.

[0085] Example 1

[0086] (1) 1.5 g of polymethylsiloxane, 3 g of dimethylbenzene and 7.5 μl of chloroplatinic acid catalyst were weighed and placed in a flask, and after stirring at room temperature for 1 h, a modified polymethylsiloxane was obtained.

[0087] (2) 3 g of diisooctyltin dithioacetate was weighed and added to the modified polymethylsiloxane, and stirred at room temperature for 1 h to form a precursor polymer; the precursor polymer was then left to stand for 4 h to obtain a precursor polymer gel.

[0088] (3) The precursor polymer gel is dried at a temperature of 100°C for 36h to activate; then the activated precursor polymer gel is heat treated under argon protection at a temperature of 1000°C for 3h; and then cooled to obtain the silicon oxycarbide / tin sulfide composite material.

[0089] The silicon oxycarbide / tin sulfide composite material prepared in this example comprises a silicon oxycarbide material and tin sulfide particles, the silicon oxycarbide material has the tin sulfide particles dispersed therein, the tin sulfide particles have a particle size of 20nm-40nm, and the silicon oxycarbide / tin sulfide composite material has a particle size of 2.5μm-5.5μm.

[0090] Example 2

[0091] (1) 1g of polydimethylsiloxane, 3.5g of cyclohexanone, and 5μl of palladium chloride catalyst are weighed into a flask, stirred at room temperature of 25°C for 0.5h to obtain modified polydimethylsiloxane.

[0092] (2) 0.5g of bis(dodecylthio) dibutyl tin is weighed into the modified polydimethylsiloxane, stirred at room temperature for 0.5h to form a precursor polymer; the precursor polymer is then left to stand for 3h to obtain a precursor polymer gel.

[0093] (3) The precursor polymer gel is activated at a temperature of 80°C for 36h; then the activated precursor polymer gel is heat treated under argon protection at a temperature of 800°C for 6h; and then cooled to obtain the silicon oxycarbide / tin sulfide composite material.

[0094] The silicon oxycarbide / tin sulfide composite material prepared in this example comprises a silicon oxycarbide material and tin sulfide particles, the silicon oxycarbide material has the tin sulfide particles dispersed therein, the tin sulfide particles have a particle size of 25nm-50nm, and the silicon oxycarbide / tin sulfide composite material has a particle size of 3.0μm-6.0μm.

[0095] Example 3

[0096] (1) 3g of polymethylsiloxane, 12g of dimethylbenzene, and 15μl of chloroplatinic acid catalyst are weighed into a flask, stirred at room temperature of 25°C for 2h to obtain modified polymethylsiloxane.

[0097] (2) 6g of isooctyl dimethyl tin dithioacetate is weighed into the modified polymethylsiloxane, stirred at room temperature for 2h to form a precursor polymer; the precursor polymer is then left to stand for 6h to obtain a precursor polymer gel.

[0098] (3) The precursor polymer gel is dried at 120°C for 24h to activate; then the activated precursor polymer gel is heat treated at 1200°C for 1h under argon protection; and then cooled to obtain the silicon oxycarbide / tin sulfide composite material.

[0099] The silicon oxycarbide / tin sulfide composite material prepared in this example comprises a silicon oxycarbide material and tin sulfide particles, the silicon oxycarbide material has the tin sulfide particles dispersed therein, the tin sulfide particles have a particle size of 10-50nm, and the silicon oxycarbide / tin sulfide composite material has a particle size of 2.0-6.0μm.

[0100] Example 4

[0101] (1) 2.3g of polysiloxane, 7g of dimethyl phthalate and 12μl of chloroplatinic acid catalyst are weighed into a flask, and stirred at room temperature for 1.5h to obtain modified polysiloxane.

[0102] (2) 3g of bis(dodecylthio)dimethyl tin is weighed into the modified polysiloxane, and stirred at room temperature for 1.5h to form a precursor polymer; the precursor polymer is then left to stand for 5h to obtain a precursor polymer gel.

[0103] (3) The precursor polymer gel is dried at 110°C for 28h to activate; then the activated precursor polymer gel is heat treated at 1100°C for 2h under argon protection; and then cooled to obtain the silicon oxycarbide / tin sulfide composite material.

[0104] The silicon oxycarbide / tin sulfide composite material prepared in this example comprises a silicon oxycarbide material and tin sulfide particles, the silicon oxycarbide material has the tin sulfide particles dispersed therein, the tin sulfide particles have a particle size of 10-50nm, and the silicon oxycarbide / tin sulfide composite material has a particle size of 2.0-6.0μm.

[0105] Example 5

[0106] The difference between this example 5 and example 1 is that step (1) is removed, and the modified polymethylsiloxane in step (2) is replaced by polymethylsiloxane; the rest is the same as example 1.

[0107] The silicon oxycarbide / tin sulfide composite material prepared in this example comprises a silicon oxycarbide material and tin sulfide particles, the silicon oxycarbide material has the tin sulfide particles dispersed therein, the tin sulfide particles have a particle size of 10-50nm, and the silicon oxycarbide / tin sulfide composite material has a particle size of 2.0-6.0μm.

[0108] Example 6

[0109] The difference between this example 6 and example 1 is that in step (3), the "precursor polymer gel is dried at a temperature of 100°C for 36h for activation; and then the activated precursor polymer gel is heat treated at a temperature of 1000°C for 3h under argon protection" is replaced by "the precursor polymer gel is heat treated at a temperature of 1000°C for 3h under argon protection"; the others are the same as example 1.

[0110] The carbon-silicon oxide / stannic sulfide composite material prepared in this example comprises carbon-silicon oxide material and stannic sulfide particles, the carbon-silicon oxide material has the stannic sulfide particles dispersed therein, the particle size of the stannic sulfide particles is 10nm-50nm, and the particle size of the carbon-silicon oxide / stannic sulfide composite material is 2.0μm-6.0μm.

[0111] Example 7

[0112] The difference between this example 6 and example 2 is that in step (3), the "precursor polymer gel is activated at a temperature of 80°C for 36h; and then the activated precursor polymer gel is heat treated at a temperature of 800°C for 6h under argon protection" is replaced by "the precursor polymer gel is heat treated at a temperature of 800°C for 6h under argon protection"; the others are the same as example 2.

[0113] The carbon-silicon oxide / stannic sulfide composite material prepared in this example comprises carbon-silicon oxide material and stannic sulfide particles, the carbon-silicon oxide material has the stannic sulfide particles dispersed therein, the particle size of the stannic sulfide particles is 10nm-50nm, and the particle size of the carbon-silicon oxide / stannic sulfide composite material is 2.0μm-6.0μm.

[0114] Example 8

[0115] The difference between this example 8 and example 3 is that in step (3), the "precursor polymer gel is dried at a temperature of 120°C for 24h for activation; and then the activated precursor polymer gel is heat treated at a temperature of 1200°C for 1h under argon protection" is replaced by "the precursor polymer gel is heat treated at a temperature of 1200°C for 1h under argon protection"; the others are the same as example 3.

[0116] The carbon-silicon oxide / stannic sulfide composite material prepared in this example comprises carbon-silicon oxide material and stannic sulfide particles, the carbon-silicon oxide material has the stannic sulfide particles dispersed therein, the particle size of the stannic sulfide particles is 10nm-50nm, and the particle size of the carbon-silicon oxide / stannic sulfide composite material is 2.0μm-6.0μm.

[0117] Example 9

[0118] The difference between this example and example 1 is that the amount of diisooctyltin bis(thioacetate) in step (2) is changed from 3 g to 4 g; and the rest is the same as example 1.

[0119] The carbon-silicon oxide / stannic sulfide composite material prepared in this example comprises carbon-silicon oxide material and stannic sulfide particles, the carbon-silicon oxide material has the stannic sulfide particles dispersed therein, the particle size of the stannic sulfide particles is 20-40 nm, and the particle size of the carbon-silicon oxide / stannic sulfide composite material is 2.5-5.5 μm.

[0120] Example 10

[0121] The difference between this example and example 1 is that the amount of diisooctyltin bis(thioacetate) in step (2) is changed from 3 g to 0.5 g; and the rest is the same as example 1.

[0122] The carbon-silicon oxide / stannic sulfide composite material prepared in this example comprises carbon-silicon oxide material and stannic sulfide particles, the carbon-silicon oxide material has the stannic sulfide particles dispersed therein, the particle size of the stannic sulfide particles is 20-40 nm, and the particle size of the carbon-silicon oxide / stannic sulfide composite material is 2.5-5.5 μm.

[0123] Example 11

[0124] The difference between this example and example 6 is that the heat treatment of the precursor polymer gel in step (3) is changed from 3 h at 1000 °C under argon protection to 0.5 h at 700 °C under argon protection; and the rest is the same as example 6.

[0125] The carbon-silicon oxide / stannic sulfide composite material prepared in this example comprises carbon-silicon oxide material and stannic sulfide particles, the carbon-silicon oxide material has the stannic sulfide particles dispersed therein, the particle size of the stannic sulfide particles is 10-50 nm, and the particle size of the carbon-silicon oxide / stannic sulfide composite material is 2.0-6.0 μm.

[0126] Example 12

[0127] The difference between this example and example 6 is that the heat treatment of the precursor polymer gel in step (3) is changed from 3 h at 1000 °C under argon protection to 7 h at 1300 °C under argon protection; and the rest is the same as example 6.

[0128] The carbon-silicon oxide / stannic sulfide composite material prepared in this example comprises carbon-silicon oxide material and stannic sulfide particles, the carbon-silicon oxide material has the stannic sulfide particles dispersed therein, the particle size of the stannic sulfide particles is 10-50 nm, and the particle size of the carbon-silicon oxide / stannic sulfide composite material is 2.0-6.0 μm.

[0129] Comparative Example 1

[0130] The difference between the present comparative example and Example 1 is that the present comparative example directly weighed 3 g of isooctyl dimethyl tin dithioacetate, and then heat treated the same at 1000°C for 3 h under argon protection.

[0131] The tin sulfide particles in the composite material prepared in the present comparative example have a particle size of 5-100 nm.

[0132] Material structure and performance analysis

[0133] I. Analysis of the morphology and structure of the silicon oxycarbide / tin sulfide composite material obtained in Example 1 above:

[0134] Figure 2 The XRD spectrum of the silicon oxycarbide / tin sulfide composite material, the diffraction peaks in the spectrum correspond to JCPDS card No. 39-0354, indicating that the tin sulfide generated has high purity.

[0135] Figure 3a and Figure 3b are respectively the SEM and TEM morphology diagrams of the silicon oxycarbide / tin sulfide composite material. From the SEM and TEM diagrams, it can be seen that the 10 nm-50 nm tin sulfide particles are uniformly dispersed in the silicon oxycarbide material, and the overall composite material size is in the micron level.

[0136] Figure 4 is the Raman spectrum of the silicon oxycarbide / tin sulfide composite material. In the diagram, I D / I G is less than 1, but it is located at the D+G peak of 2940 cm -1 , indicating that there is a large amount of amorphous carbon in the silicon oxycarbide, which is beneficial to improve the overall capacity of the composite material.

[0137] It should be noted that the morphology and structure of the silicon oxycarbide / tin sulfide composite material obtained in Examples 2-5 are basically the same as those of the silicon oxycarbide / tin sulfide composite material obtained in Example 1 above. The morphology and structure of the silicon oxycarbide / tin sulfide composite material obtained in Examples 6-8 are basically the same as those of the silicon oxycarbide / tin sulfide composite material obtained in Example 1 above, but because there is no activation before heat treatment, the uniformity of tin sulfide particles in the silicon oxycarbide is slightly worse.

[0138] II. Electrochemical performance test of the composite materials obtained in Examples 1-12 and Comparative Example 1 above:

[0139] 1) Battery assembly

[0140] The composite material obtained from Example 1-12 and Comparative Example 1 was used as an active material, which was mixed with acetylene black and carboxymethyl cellulose (CMC) at a ratio of 80wt%:10wt%:10wt% by weight, and then the obtained mixture was uniformly coated on a copper foil, and after drying, the electrode sheet was cut into a diameter of 14 cm as a negative electrode sheet. A lithium sheet was used as a positive electrode sheet, a PE film was used as a separator, and a 1M LiPF6 solution (in which the solvent was a mixture of ethylene carbonate EC and dimethyl carbonate DMC at a volume ratio of 1:1) was used as an electrolyte to assemble a coin-type lithium ion half battery.

[0141] 3) Battery test

[0142] After the above assembled coin-type battery was left for 5h, the charge and discharge test was carried out, and the charge and discharge current density was 0.1A / g, 0.5A / g, 1A / g, 2A / g, 3A / g and 0.1A / g in turn, and the charge and discharge voltage window was 0.005V-3.0V. The test results are shown in Tables 1 and 2 and Figure 5 and Figure 6 .

[0143] Table 1 is the rate performance data of the battery assembled by the composite material obtained from Example 1-12 and Comparative Example 1, and Table 2 is the cycle performance data of the battery assembled by the composite material obtained from Example 1-12 and Comparative Example 1 at a charge and discharge current density of 3A / g.

[0144] Table 1

[0145]

[0146]

[0147] Table 2

[0148]

[0149] Figure 5 Figure is the different rate performance of the battery assembled by the carbon silicon oxide / tin sulfide composite material obtained from Example 1; Figure 6 Figure is the cycle performance of the battery assembled by the carbon silicon oxide / tin sulfide composite material obtained from Example 1 at a current density of 3A / g.

[0150] From Tables 1, 2, Figure 5 and Figure 6 , it can be seen that the battery assembled by the carbon silicon oxide / tin sulfide composite material prepared by Example 1-12 has good rate performance and cycle performance.

[0151] The rate capability and cycle performance of the carbon-silicon oxide / tin sulfide composite material prepared in Examples 1-5 are better than those of the carbon-silicon oxide / tin sulfide composite material prepared in Examples 6-8, because the activation step is added before the heat treatment of the precursor polymer gel in Examples 1-5.

[0152] In Example 9, the mass ratio of the sulfur-containing organotin source to the siloxane polymer is higher than 2:1, so that the content of the tin sulfide particles in the composite material is too high, resulting in the cycle performance of the composite material being worse than that of Example 1; in Example 10, the mass ratio of the sulfur-containing organotin source to the siloxane polymer is lower than 0.5:1, so that the content of the tin sulfide particles in the composite material is too low, resulting in the capacity of the composite material being lower than that of Example 1.

[0153] In Example 11, the temperature of the heat treatment is lower than 800℃, so that the carbonization effect is poor, resulting in the capacity of the composite material being lower than that of Example 6; in Example 12, the temperature of the heat treatment is higher than 1200℃, so that the amorphous carbon in the carbon-silicon oxide material is reduced, resulting in the rate capability of the composite material being worse than that of Example 6.

[0154] In Comparative Example 1, the diisooctyltin dimethyl dithioacetate is simply pyrolyzed, so that the particle size distribution of the tin sulfide particles in the obtained composite material is wide, ranging from 5nm to 100nm, and the rate capability and cycle performance are poor.

[0155] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application, and are not intended to limit the present application; although the present application has been described in detail with reference to the above examples, those skilled in the art should understand that they can still modify the technical solutions described in the above examples, or make equivalent substitutions for some or all of the technical features; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the examples of the present application.

[0156] In addition, those skilled in the art will appreciate that although some of the examples herein include certain features that are not included in other examples, the combination of features of different examples means that they are within the scope of the present application and form different examples. For example, in the above claims, any one of the claimed examples can be used in any combination. The information disclosed in the BACKGROUND section is only intended to deepen the understanding of the overall background of the present application, and should not be regarded as acknowledging or implying in any form that the information constitutes prior art known to those skilled in the art.

Claims

1. A composite material, characterized in that The composite material includes a silicon oxycarbide / stannous sulfide composite; the silicon oxycarbide / stannous sulfide composite includes a silicon oxycarbide material and stannous sulfide particles, and the stannous sulfide particles are dispersed inside the silicon oxycarbide material; The stannous sulfide particles account for 15wt%-60wt% of the composite material, and the silicon oxycarbide material accounts for 40wt%-85wt% of the composite material; The particle size of the silicon oxycarbide / stannous sulfide composite is 2 μm-6 μm; The particle size of the stannous sulfide particles is 10nm-50nm; The stannous sulfide particles are uniformly distributed in the silicon oxycarbide material; The silicon oxycarbide contains amorphous carbon; The silicon oxycarbide has a porous structure; The method for preparing the composite material comprises: mixing raw materials including a siloxane polymer, an organic solvent, and a sulfur-containing organotin source to obtain a precursor polymer gel; heat-treating the precursor polymer gel in a protective atmosphere or a vacuum environment to obtain a silicon oxycarbide / stannous sulfide composite; The mass ratio of the sulfur-containing organic tin source to the siloxane polymer (0.5-2): 1; Before the heat treatment, the precursor polymer gel is further activated at a temperature of 80° C. to 120° C. for a time of 24 hours to 48 hours. The heat treatment temperature is 800° C.-1200° C., and the heat treatment time is 1 hour-6 hours.

2. The composite material according to claim 1, characterized in that The process of combining the raw materials including the siloxane polymer, the organic solvent, and the sulfur-containing organotin source includes: Mixing and reacting a siloxane polymer, an organic solvent, and a catalyst to obtain a modified siloxane polymer; The modified silicone polymer is mixed with the sulfur-containing organotin source.

3. The composite material according to claim 2, characterized in that The catalyst comprises at least one of chloroplatinic acid, 1,3-divinyl-1,1,3,3-tetramethyldisiloxane platinum, dicyclopentadiene platinum, palladium chloride, tetrakistriphenylphosphine palladium, triphenylphosphine rhodium chloride, octacarbonyl dicobalt, tetracarbonyl nickel and hexacarbonyl chromium; and / or, the mixing reaction time of the siloxane polymer, the organic solvent and the catalyst is 0.5 h to 2 h; and / or, the ratio of the amount of the siloxane polymer to the amount of the catalyst is (1-3) g / (5-15) μl; And / or, the method further comprises a step of standing after the modified siloxane polymer and the sulfur-containing organic tin source are mixed and reacted.

4. The composite material according to claim 1, characterized in that The silicone polymer includes at least one of polysiloxane, polymethylsiloxane and polydimethylsiloxane; and / or, the organic solvent comprises at least one of dimethylbenzene, tetrahydrofuran, cyclohexanone, ethylene glycol dimethyl ether and dimethyl phthalate; And / or, the sulfur-containing organic tin source is selected from sulfur-containing organic tin sources with a carbon-carbon chain ≥ 6; and / or, the sulfur-containing organic tin source comprises at least one of dimethyl tin dithioacetate, bis(dodecylthio)dimethyltin, didodecylthio)dibutyltin and diisooctyl 2,2'-[(dimethyltin)bis(thio)]diacetate; and / or, the protective atmosphere comprises at least one of helium, neon, argon and nitrogen; And / or, the mass ratio of the organic solvent to the siloxane polymer is (2-5):

1.

5. A negative electrode material, characterized in that The composite material comprises the composite material according to any one of claims 1 to 4.

6. A negative electrode sheet, characterized in that: Comprising the negative electrode material according to claim 5.

7. A battery, characterized in that: Including the negative electrode sheet according to claim 6.

8. The battery according to claim 7, characterized in that The battery is a lithium-ion battery.

Images