A composite negative electrode material and its preparation method and application

Abstract

The present invention relates to the field of battery technology, and more specifically, to a composite negative electrode material, its preparation method, and its application. A composite negative electrode material comprises a core substrate and a composite layer disposed on at least a portion of the surface of the core substrate; the core substrate comprises graphite; and the composite layer comprises a composite of porous titanium oxide, a conductive carbon material, and a lithium phenylsulfonate compound. The composite negative electrode material of the present invention, through coating with the composite layer, can improve the cycle performance and rate performance of the composite negative electrode material, provide good fast charging performance, and enhance safety performance.

Description

Technical Field

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

[0002] Currently, the fast-charging negative electrode material used in lithium-ion batteries is mainly artificial graphite, which is mainly composed of graphite and amorphous carbon coated on its surface. However, due to the low specific capacity of the coated amorphous carbon itself, low initial efficiency and small material interlayer spacing, the initial efficiency of the material is low and the improvement in the fast-charging performance of the material is limited. Some researchers have improved the fast-charging performance of the material by measures such as coating the surface of the material with fast ion conductors. Although the ionic conductivity of the resulting material is improved, the improvement in the initial efficiency of the material is not significant. In addition, due to the low interlayer spacing and low ionic conductivity of the coating layer material, it expands significantly during the charge and discharge process, resulting in a limited improvement in the fast-charging performance of the material.

[0003] Therefore, how to optimize the coating material and its structure to enhance the electron and ion transmission rate of the material and improve the rate performance of the material is crucial to the development of batteries.

[0004] In view of this, the present invention is proposed. Summary of the Invention

[0005] An object of the present invention is to provide a composite negative electrode material with high electron and ion transmission rate, good cycle performance and rate performance, and high safety performance.

[0006] Another object of the present invention is to provide a method for preparing a composite negative electrode material, which is simple, easy to implement and environmentally friendly.

[0007] Another object of the present invention is to provide a negative electrode sheet.

[0008] Another object of the present invention is to provide a battery.

[0009] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are adopted:

[0010] A composite negative electrode material comprises a core matrix and a composite layer arranged on at least a portion of the surface of the core matrix; the core matrix comprises graphite; the composite layer comprises a composite of porous titanium oxide, a conductive carbon material and a lithium phenylsulfonate compound.

[0011] In some embodiments, in the composite negative electrode material, the mass fraction of the composite layer is 2% to 8%.

[0012] In some embodiments, the conductive carbon material includes one or more of carbon nanotubes, graphene, and conductive carbon black.

[0013] In some embodiments, the lithium phenylsulfonate includes one or more of lithium 3-aminobenzenesulfonate, lithium m-aminobenzenesulfonate, lithium isopropylbenzenesulfonate, lithium cumenesulfonate, and lithium p-toluenesulfonate.

[0014] In some embodiments, the specific surface area of ​​the composite negative electrode material is 3 to 4.5 m 2 / g.

[0015] In some embodiments, the interlayer spacing of the composite negative electrode material is 0.3730-0.3810 nm.

[0016] In some embodiments, the ionic conductivity of the composite negative electrode material is 1×10 -9 ~9×10 -9 S / cm.

[0017] The method for preparing the composite negative electrode material as described above comprises the following steps:

[0018] A first mixed system of a titanium source, a dispersant, a conductive agent solution, graphite, an alkali solution and a first solvent is subjected to a hydrothermal reaction treatment, and the solid matter after the reaction is collected and sintered to obtain a first material; the first material, lithium phenylsulfonate and an organic solvent are mixed and dried to obtain a composite negative electrode material.

[0019] In some embodiments, the titanium source includes titanium chloride.

[0020] In some embodiments, the dispersant includes at least one of sodium lauryl sulfate, polyvinyl alcohol, and polyacetylpyrrolidone.

[0021] In some embodiments, the conductive agent solution includes at least one of a carbon nanotube conductive liquid, a graphene conductive liquid, and a carbon black conductive liquid; and the concentration of the conductive agent solution is 1% to 5%.

[0022] In some embodiments, the alkali solution includes at least one of n,n-dimethylethanolamine, diethylaminoethanol, dimethylaminopropylamine, dimethylamine, and diethylamine.

[0023] In some embodiments, the mass ratio of the titanium source, the dispersant, the conductive agent solution, the graphite, and the alkaline solution is (50-100):(10-50):(10-50):1000:(100-300).

[0024] In some embodiments, the mass ratio of the titanium source to the first solvent is (50-100):(600-1500).

[0025] In some embodiments, the preparation method of the mixed system specifically includes: dispersing the titanium source and the dispersant in the first solvent, wherein the total mass content of the titanium source and the dispersant is 8% to 12%, and then adding the conductive agent solution, the graphite and the alkali solution.

[0026] In some embodiments, the temperature of the hydrothermal reaction treatment is 100-200° C., and the time of the hydrothermal reaction treatment is 1-6 hours.

[0027] In some embodiments, the sintering temperature is 500-800° C., and the sintering time is 1-6 hours.

[0028] In some embodiments, a drying treatment is further included between the hydrothermal reaction treatment and the sintering treatment; the temperature of the drying treatment is 60 to 90° C., and the time of the drying treatment is 15 to 25 hours.

[0029] In some embodiments, the lithium phenylsulfonate includes at least one of lithium 3-aminobenzenesulfonate, lithium m-aminobenzenesulfonate, lithium isopropylbenzenesulfonate, lithium cumenesulfonate, and lithium p-toluenesulfonate.

[0030] In some embodiments, the organic solvent comprises at least one of ethanol, ether, carbon tetrachloride and tetrahydrofuran.

[0031] In some embodiments, the mass ratio of the lithium phenylsulfonate to the first material is (5-10):1000.

[0032] In some embodiments, the mass ratio of the lithium phenylsulfonate to the organic solvent is (5-10):100.

[0033] In some embodiments, the drying comprises spray drying, the inlet temperature of the spray drying is 200-240°C, the outlet temperature of the spray drying is 100-130°C, the flow rate of the spray drying is 0.1-0.5 kg / h, and the time of the spray drying is 1-5 hours.

[0034] A negative electrode sheet comprises the composite negative electrode material, or the composite negative electrode material prepared by the method for preparing the composite negative electrode material.

[0035] A battery comprises the negative electrode sheet.

[0036] An electrical device comprises the battery.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] (1) The composite negative electrode material of the present invention is a composite of porous titanium oxide, carbon nanotubes and lithium phenylsulfonate compounds coated on the surface of graphite. The fast charging performance and cycle performance of the material are improved by utilizing the large interlayer spacing, high voltage platform and low expansion characteristics of titanium oxide itself; the strong solvation ability of lithium phenylsulfonate itself is utilized to increase the diffusion rate of lithium ions during charging and discharging, and improve the rate performance; at the same time, the lithium phenylsulfonate coating on the surface reduces defects, reduces irreversible capacity loss, and improves the initial efficiency; through the coating of the composite layer, the cycle performance and rate performance of the composite negative electrode material can be improved, and the fast charging performance and safety performance are good.

[0039] (2) The preparation method of the composite negative electrode material of the present invention is simple and easy. The titanium source, dispersant, conductive agent solution, graphite and alkali solution are mixed and then subjected to hydrothermal reaction treatment. The titanium source and OH in the solution are - The first material, lithium phenylsulfonate, and an organic solvent are further mixed and dried to form a composite of lithium phenylsulfonate, porous titanium oxide, and conductive carbon material. Lithium phenylsulfonate contains sulfonate groups and has strong solvation ability, which is beneficial for increasing the lithium ion insertion and extraction rate and improving the rate. Through the coordination of various steps, the resulting composite negative electrode material has a suitable specific surface area and interlayer spacing, good conductivity, good cycle stability, and good fast charging performance.

[0040] (3) The battery of the present invention has excellent cycle performance, rate performance, good fast charging performance and high safety performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0042] Figure 1 This is a scanning electron microscope (SEM) image of the composite negative electrode material in Example 1. DETAILED DESCRIPTION

[0043] The embodiments of the present invention will be described in detail below with reference to the examples, but it will be understood by those skilled in the art that the following examples are merely illustrative of the present invention and should not be construed as limiting the scope of the invention. Where specific conditions are not specified in the examples, the methods were performed according to conventional conditions or the conditions recommended by the manufacturer. Where the manufacturers of the reagents or instruments are not specified, they are all commercially available conventional products.

[0044] According to one aspect of the present invention, the present invention relates to a composite negative electrode material, comprising a core matrix and a composite layer arranged on at least a portion of the surface of the core matrix; the core matrix comprises graphite; the composite layer comprises a composite of porous titanium oxide, conductive carbon material and lithium phenylsulfonate compound.

[0045] The composite negative electrode material of the present invention is a composite of porous titanium oxide, carbon nanotubes and lithium phenylsulfonate compounds coated on the surface of graphite. The fast charging performance and cycle performance of the material are improved by utilizing the large interlayer spacing, high voltage platform and low expansion of titanium oxide itself; the strong solvation ability of lithium phenylsulfonate itself is utilized to increase the diffusion rate of lithium ions during charging and discharging, and improve the rate performance; at the same time, the lithium phenylsulfonate coating on the surface reduces defects, reduces irreversible capacity loss, and improves the initial efficiency; through the coating of the composite layer, the cycle performance and rate performance of the composite negative electrode material can be improved, and the fast charging performance and safety performance are good.

[0046] In some embodiments, in the composite negative electrode material, the mass fraction of the composite layer is 2% to 8%, including but not limited to 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 7%, 8%, etc., or any range therebetween. In the composite negative electrode material of the present invention, an appropriate mass fraction of the composite layer is more conducive to improving the overall electrochemical performance of the material.

[0047] In some embodiments, the conductive carbon material includes one or more of carbon nanotubes, graphene, and conductive carbon black, such as a combination of carbon nanotubes and graphene, a combination of graphene and conductive carbon black, and the like.

[0048] In some embodiments, the lithium phenylsulfonate includes one or more of lithium 3-aminobenzenesulfonate, lithium m-aminobenzenesulfonate, lithium isopropylbenzenesulfonate, lithium cumenesulfonate and lithium p-toluenesulfonate, for example, a combination of lithium 3-aminobenzenesulfonate and lithium m-aminobenzenesulfonate, a combination of lithium isopropylbenzenesulfonate and lithium cumenesulfonate, a combination of lithium isopropylbenzenesulfonate, lithium cumenesulfonate and lithium p-toluenesulfonate, etc.

[0049] In some embodiments, the composite negative electrode material of the present invention has a suitable specific surface area of ​​3 to 4.5 m 2 / g, including but not limited to 3m 2 / g, 3.5m 2 / g、4m 2 / g, 4.2m 2 / g, 4.5m 2 / g, etc., or any range between the two.

[0050] In some embodiments, the composite negative electrode material of the present invention has a suitable interlayer spacing of 0.3730 to 0.3810 nm, including but not limited to 0.3730 nm, 0.3740 nm, 0.3750 nm, 0.3760 nm, 0.3800 nm, 0.3810 nm, etc., or any range between the two.

[0051] In some embodiments, the ionic conductivity of the composite negative electrode material of the present invention is 1×10 -9 ~9×10 -9 S / cm, for example 1×10 -9 S / cm, 3×10 -9 S / cm, 5×10 -9 S / cm, 8×10 -9 S / cm, etc., or any range between the two. The composite negative electrode material of the present invention has excellent ion conductivity.

[0052] According to another aspect of the present invention, the present invention also relates to a method for preparing the composite negative electrode material as described above, comprising the following steps:

[0053] A first mixed system consisting of a titanium source, a dispersant, a conductive agent solution, graphite, and an alkaline solution is subjected to a hydrothermal reaction, and the solid product after the reaction is collected and sintered to obtain a first material. The first material, lithium phenylsulfonate, and an organic solvent are mixed and dried to obtain a composite negative electrode material.

[0054] The preparation method of the composite negative electrode material of the present invention is simple and easy. The titanium source, dispersant, conductive agent solution, graphite and alkali solution are mixed and then subjected to hydrothermal reaction treatment. The titanium source and OH in the solution are mixed and then subjected to hydrothermal reaction treatment. - The first material, lithium phenylsulfonate, and an organic solvent are further mixed and dried to form a composite of lithium phenylsulfonate, porous titanium oxide, and conductive carbon material. Lithium phenylsulfonate contains sulfonate groups and has strong solvation ability, which is beneficial for increasing the lithium ion insertion and extraction rate and improving the rate. Through the coordination of various steps, the resulting composite negative electrode material has a suitable specific surface area and interlayer spacing, good conductivity, good cycle stability, and good fast charging performance.

[0055] In some embodiments, the titanium source comprises titanium chloride.

[0056] In some embodiments, the dispersant includes one or more of sodium lauryl sulfate, polyvinyl alcohol, and polyacetyl pyrrolidone, such as sodium lauryl sulfate and polyvinyl alcohol, polyvinyl alcohol and polyacetyl pyrrolidone, and the like.

[0057] In some embodiments, the conductive agent solution includes at least one of a carbon nanotube conductive liquid, a graphene conductive liquid, and a carbon black conductive liquid; the concentration of the conductive agent solution is 1% to 5%, for example, 1%, 2%, 3%, 5%, etc.

[0058] In some embodiments, the alkali solution includes one or more of n,n-dimethylethanolamine, diethylaminoethanol, dimethylaminopropylamine, dimethylamine and diethylamine, such as a combination of n,n-dimethylethanolamine and diethylaminoethanol, a combination of dimethylamine and diethylamine, a combination of diethylaminoethanol, dimethylaminopropylamine and dimethylamine, and the like.

[0059] In some embodiments, the mass ratio of the titanium source, dispersant, conductive agent solution, graphite and alkali solution is (50-100):(10-50):(10-50):1000:(100-300), including but not limited to 50:10:10:1000:100, 60:15:15:1000:200, 60:25:25:1000:200, 70:30:30:1000:250, 100:50:50:1000:300, etc. The present invention adopts a suitable mass ratio of titanium source, dispersant, conductive agent solution, graphite and alkali solution, which is more conducive to the performance of the mixed system and improves the electrochemical performance of the final composite negative electrode material.

[0060] In some embodiments, the mass ratio of the titanium source to the first solvent is (50-100):(600-1500), for example, 50:600, 60:700, 70:1000, 80:1200, 100:1500, etc. The first solvent of the present invention is used in an appropriate amount ratio to facilitate sufficient mixing of the materials and facilitate the subsequent hydrothermal reaction. The first solvent includes water, for example, deionized water.

[0061] In some embodiments, the preparation method of the mixed system specifically includes: dispersing the titanium source and the dispersant in water, the total mass content of the titanium source and the dispersant is 8% to 12% (8%, 8.5%, 9%, 9.5%, 10%, 12%, etc.), and then adding a conductive agent solution, graphite and alkali solution.

[0062] In some embodiments, the hydrothermal reaction is carried out in an autoclave at a temperature of 100 to 200° C., including but not limited to 100° C., 110° C., 120° C., 130° C., 150° C., 170° C., 180° C., 200° C., or any range therebetween. The hydrothermal reaction is carried out for a time of 1 to 6 hours, such as 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, or 6 hours, or any range therebetween. The appropriate hydrothermal reaction temperature is used to obtain TI(OH) 3, which is coated on the surface of the graphite.

[0063] In some embodiments, the sintering temperature is 500-800°C, including but not limited to 500°C, 550°C, 600°C, 650°C, 700°C, 750°C or 800°C, or any range therebetween. The sintering time is 1-6 hours, including but not limited to 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, or any range therebetween. The present invention generates porous titanium oxide through suitable sintering conditions, and the conductive agent is uniformly doped in the porous titanium oxide, forming a porous titanium oxide / conductive agent coating layer on the surface of the graphite.

[0064] In some embodiments, a drying process is further performed between the hydrothermal reaction process and the sintering process. The drying process temperature is 60-90°C, including but not limited to 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, or any range therebetween. The drying process time is 15-25 hours, including but not limited to 15 hours, 18 hours, 20 hours, 24 hours, 25 hours, etc. Appropriate drying process can further remove moisture.

[0065] In some embodiments, the lithium phenylsulfonate includes at least one of lithium 3-aminobenzenesulfonate, lithium m-aminobenzenesulfonate, lithium isopropylbenzenesulfonate, lithium cumenesulfonate and lithium p-toluenesulfonate, for example, a combination of lithium 3-aminobenzenesulfonate and lithium m-aminobenzenesulfonate, a combination of lithium isopropylbenzenesulfonate and lithium cumenesulfonate, a combination of lithium isopropylbenzenesulfonate, lithium cumenesulfonate and lithium p-toluenesulfonate, and the like.

[0066] In some embodiments, the organic solvent includes one or more of ethanol, diethyl ether, carbon tetrachloride, and tetrahydrofuran, such as a combination of ethanol and diethyl ether, a combination of diethyl ether, carbon tetrachloride, and tetrahydrofuran, and the like.

[0067] In some embodiments, the mass ratio of lithium phenylsulfonate to the first material is (5-10):1000, for example, 5:1000, 5.5:1000, 6:1000, 7:1000, 8:1000, 9:1000, or 10:1000. The use of an appropriate mass ratio of lithium phenylsulfonate to the first material of the present invention is more conducive to ensuring an appropriate content of lithium phenylsulfonate in the composite particles and better compounding with the conductive agent and porous titanium oxide.

[0068] In some embodiments, the mass ratio of lithium phenylsulfonate to the organic solvent is (5-10):100, 5:1000, 5.5:1000, 6:1000, 7:1000, 9:1000, or 10:1000, etc. The present invention uses a suitable organic solvent to ensure sufficient dispersion and mixing of the materials, thereby improving the electrochemical performance of the final composite negative electrode material.

[0069] In some embodiments, drying includes spray drying, the inlet temperature of the spray drying is 200-240°C, for example, 200°C, 210°C, 220°C, or 240°C, etc., the outlet temperature of the spray drying is 100-130°C, for example, 100°C, 120°C, or 130°C, etc., the flow rate of the spray drying is 0.1-0.5 kg / h, for example, 0.1 kg / h, 0.2 kg / h, 0.3 kg / h, 0.5 kg / h, etc., and the spray drying time is 1-5 hours, for example, 1 hour, 2 hours, 3 hours, 4 hours, or 5 hours, etc. The present invention adopts appropriate spray drying conditions to obtain a composite negative electrode material with better performance.

[0070] According to another aspect of the present invention, the present invention also relates to a negative electrode sheet, comprising the above-mentioned composite negative electrode material, or the composite negative electrode material prepared by the above-mentioned method for preparing the composite negative electrode material.

[0071] The negative electrode sheet of the present invention comprises a negative electrode current collector and a negative electrode layer located on at least one side surface of the negative electrode current collector. The negative electrode layer comprises the composite negative electrode material, a conductive agent and a binder.

[0072] According to another aspect of the present invention, the present invention also relates to a battery comprising the above-mentioned negative electrode sheet.

[0073] The battery of the present invention has excellent cycle performance, rate performance, good fast charging performance and high safety.

[0074] In some embodiments, a battery includes the aforementioned negative electrode sheet, positive electrode sheet, separator, and electrolyte.

[0075] According to another aspect of the present invention, the present invention also relates to an electric device comprising the above-mentioned battery. The electric device includes a laptop computer, an electric car, an electric tool, etc.

[0076] The following is further explained with reference to specific embodiments and comparative examples.

[0077] Example 1

[0078] A method for preparing a composite negative electrode material comprises the following steps:

[0079] (1) 80 g of titanium chloride and 30 g of sodium lauryl sulfate were dispersed in 1100 g of deionized water to prepare a 10 wt% solution, and then 30 g of a 3 wt% carbon nanotube conductive agent solution was added, and then 1000 g of artificial graphite was added and dispersed evenly, and then 200 g of n-dimethylethanolamine was added dropwise and mixed evenly, and then transferred to a high-pressure reactor, and a hydrothermal reaction was carried out at a temperature of 150 ° C for 3 h, filtered, and vacuum dried at 80 ° C for 24 h. Then, the obtained material was sintered at a temperature of 650 ° C for 3 h to obtain a first material.

[0080] (2) 8 g of lithium 3-aminobenzenesulfonate was added to 100 g of dimethyl carbonate organic solvent and dispersed evenly, and then 100 g of the first material was added and dispersed evenly, and spray dried (inlet temperature of 220° C., outlet temperature of 120° C., flow rate of 0.3 kg / h, time of 3 h) to obtain a composite negative electrode material.

[0081] Example 2

[0082] A method for preparing a composite negative electrode material comprises the following steps:

[0083] (1) 50 g of titanium chloride and 10 g of polyvinyl alcohol were dispersed in 600 g of deionized water to prepare a 10 wt% solution, and then 10 g of a 5 wt% graphene conductive agent solution was added, and then 1000 g of artificial graphite was added and dispersed evenly, and then 100 g of diethylaminoethanol was added dropwise and mixed evenly, and then transferred to a high-pressure reactor, and a hydrothermal reaction was carried out at a temperature of 100 ° C. for 6 h, filtered, and vacuum dried at 80 ° C. for 24 h. The resulting material was then sintered at a temperature of 500 ° C. for 6 h to obtain a first material.

[0084] (2) 5 g of lithium isopropylbenzenesulfonate was added to 100 g of dimethyl carbonate organic solvent and dispersed evenly, and then 100 g of the first material was added and dispersed evenly, and spray dried (inlet temperature was 220 ° C, outlet temperature was 120 ° C, flow rate was 0.1 kg / h, time was 5 h) to obtain a composite negative electrode material.

[0085] Example 3

[0086] A method for preparing a composite negative electrode material comprises the following steps:

[0087] (1) 100 g of titanium chloride and 50 g of polyacetyl pyrrolidone were dispersed in 1500 g of deionized water to prepare a 10 wt% solution, and then 50 g of a 5 wt% superconducting carbon black conductive agent solution was added, and then 1000 g of artificial graphite was added and dispersed evenly, and then 300 g of dimethylaminopropylamine was added dropwise and mixed evenly, and then transferred to a high-pressure reactor, and a hydrothermal reaction was carried out at a temperature of 200 ° C for 1 hour, filtered, and vacuum dried at 80 ° C for 24 hours. Then, the obtained material was sintered at a temperature of 800 ° C for 1 hour to obtain a first material.

[0088] (2) 10 g of lithium m-aminobenzenesulfonate was added to 100 g of dimethyl carbonate organic solvent and dispersed evenly, and then 100 g of the first material was added and dispersed evenly, and spray dried (inlet temperature of 220 ° C, outlet temperature of 120 ° C, flow rate of 0.5 kg / h, time of 1 h) to obtain a composite negative electrode material.

[0089] Example 4

[0090] A method for preparing a composite negative electrode material comprises the following steps:

[0091] (1) 75 g of titanium chloride and 45 g of polyacetyl pyrrolidone were dispersed in 1200 g of deionized water to prepare a 10 wt% solution, and then 15 g of a 5 wt% superconducting carbon black conductive agent solution and 20 g of a 5 wt% carbon nanotube were added, and then 1000 g of artificial graphite was added and dispersed evenly, and then 260 g of dimethylaminopropylamine was added dropwise and mixed evenly, and then transferred to a high-pressure reactor, and a hydrothermal reaction was carried out at a temperature of 160 ° C for 2 h, filtered, and vacuum dried at 70 ° C for 24 h. The resulting material was then sintered at a temperature of 670 ° C for 2.5 h to obtain a first material.

[0092] (2) 3.5 g of lithium m-aminobenzenesulfonate and 4 g of lithium p-toluenesulfonate were added to 100 g of dimethyl carbonate organic solvent and dispersed evenly, and then 100 g of the first material was added and dispersed evenly, and spray dried (inlet temperature of 220°C, outlet temperature of 120°C, flow rate of 0.3 kg / h, time of 3 h) to obtain a composite negative electrode material.

[0093] Example 5

[0094] A method for preparing a composite negative electrode material, which differs from Example 4 in that:

[0095] In step (2), 1.5 g of lithium m-aminobenzenesulfonate, 1.5 g of lithium p-toluenesulfonate and 3.5 g of lithium 3-aminobenzenesulfonate were added to 100 g of dimethyl carbonate organic solvent and dispersed evenly, then 100 g of the first material was added and dispersed evenly, and spray dried (inlet temperature of 220 ° C, outlet temperature of 120 ° C, flow rate of 0.3 kg / h, time of 3 h) to obtain a composite negative electrode material.

[0096] Comparative Example 1

[0097] A method for preparing a composite negative electrode material, which differs from Example 1 in that:

[0098] In step (1), titanium chloride and n-dimethylethanolamine are not added, that is, titanium oxide is not prepared.

[0099] Comparative Example 2

[0100] A method for preparing a composite negative electrode material, which differs from Example 1 in that:

[0101] The operation was carried out according to step (1) of Example 1 to obtain a first material as a negative electrode material.

[0102] Experimental example

[0103] 1. SEM test

[0104] The composite negative electrode material prepared in Example 1 was subjected to SEM testing, and the results were as follows: Figure 1As shown. Figure 1 It can be seen that the composite negative electrode material has a granular structure with slight adhesion, a particle size between 10 and 15 μm, and a uniform size distribution.

[0105] 2. Performance test of composite negative electrode materials

[0106] The specific surface area of ​​the aforementioned negative electrode materials was tested according to the standard GB / T-24533-2019, "Graphite-Based Anode Materials for Lithium-Ion Batteries." Ionic conductivity was measured using the AC impedance spectroscopy method. XRD was used to measure the interlayer spacing of the powdered materials. The test results are shown in Table 1.

[0107] Table 1 Test results of composite negative electrode materials

[0108]

[0109]

[0110] 3. Button Battery Test

[0111] The composite negative electrode materials prepared in the Examples and Comparative Examples were assembled into button-type batteries according to the following methods:

[0112] A binder, conductive agent, and solvent were added to the composite anode material and stirred to form anode slurry. The binder was polyvinylidene fluoride, the conductive agent was SP, and the solvent was NMP. The weight ratio of the anode material, SP, polyvinylidene fluoride, and NMP was 95:1:4:220. The slurry was coated onto copper foil, dried, roll-pressed, and cut to produce anode sheets. A lithium metal sheet served as the counter electrode; a polyethylene (PE) film served as the separator; the electrolyte was a LiPF6 solution with a LiPF6 concentration of 1.3 mol / L; and the solvents were EC and DEC in a 1:1 volume ratio. The battery was assembled in an argon-filled glove box.

[0113] The prepared button cells were installed in a Wuhan Blue Power CT2001A battery tester and charged and discharged at a 0.1C rate over a voltage range of 0.005V-2.0V. The initial discharge capacity and initial discharge efficiency were measured. The 1C rate discharge capacity was tested, and the rate performance (1C / 0.1C), cycle performance (0.1C / 0.1C, 100 cycles), and low-temperature charge DCR (-20°C, 50% SOC) were calculated.

[0114] The performance test results of the button battery are shown in Table 2.

[0115] Table 2 Performance test results of button batteries

[0116]

[0117]

[0118] 4. Soft pack battery test

[0119] The negative electrode was prepared using the composite negative electrode materials prepared in each embodiment and comparative example, the positive electrode was prepared using NCM111 as the positive electrode material, a 2Ah soft-pack battery was prepared using LiPF6 solution as the electrolyte (the solvent was EC and DEC, the volume ratio was 1:1, the concentration was 1.3 mol / L), and celegard2400 as the separator.

[0120] When preparing the negative electrode, a binder, a conductive agent, and a solvent are added to the negative electrode material, the binder is LA132 binder, the conductive agent is SP conductive agent, and the solvent is double distilled water. The weight ratio of the negative electrode material, SP conductive agent, LA132 binder and double distilled water is 95:1:4:220. The mixture is stirred and mixed evenly to form a negative electrode slurry. The negative electrode slurry is coated on a copper foil, dried, rolled, and cut to obtain a negative electrode sheet.

[0121] During cathode preparation, a binder, conductive agent, and solvent (PVDF, SP, and N-methylpyrrolidone) are added to the cathode material. The weight ratio of the cathode material, conductive agent, binder, and solvent is 93:3:4:140. The mixture is stirred and mixed to form a cathode slurry. The slurry is then coated onto aluminum foil, dried, rolled, and cut to form the cathode sheet.

[0122] 1. Rate performance test

[0123] The charge and discharge voltage range is 2.8~4.35V, the test temperature is 25±3.0℃, and the charging is performed at 1.0C, 2.0C, 3.0C, and 5.0C, and the discharge is performed at 1.0C. The constant current ratio and temperature of the battery under different charging modes are tested. The results are shown in Table 3:

[0124] Table 3 Rate performance

[0125]

[0126] 2. Cyclic performance test

[0127] The soft-pack batteries made of the composite negative electrode materials in each embodiment and comparative example were subjected to the following experiment: at a charge and discharge rate of 2C / 2C and a voltage range of 2.8-4.35V, 100, 300, and 500 charge and discharge cycles were performed in sequence to test their capacity retention rate. The results are shown in Table 4.

[0128] Table 4 Cyclic performance test

[0129]

[0130] As can be seen from the above, the composite negative electrode materials prepared in each embodiment of the present invention have suitable specific surface areas, interlayer spacings, and high ionic conductivity. The resulting button-type batteries exhibit excellent initial efficiency and rate performance, surpassing those of Comparative Examples 1-2. This is due to the fact that the graphite materials in each embodiment are coated with porous titanium oxide, which leverages its inherent large interlayer spacing. Combined with conductive carbon and lithium phenylsulfonate, this increases the interlayer spacing and diffusion coefficient of the material, reduces material defects, and improves initial efficiency and lithium ion diffusion rate.

[0131] The composite negative electrode materials of each embodiment of the present invention produce soft-pack batteries with good rate performance and cycle performance. Good rate performance means that the composite negative electrode materials have good fast-charging performance. The reasons include: the porous titanium oxide coated on the surface of the material has a large interlayer spacing, which, combined with other materials in the composite layer, can increase the insertion and extraction rate of lithium ions during the charge and discharge process and improve the constant current ratio of the material. The cycle performance of the soft-pack batteries produced by the composite negative electrode materials of each embodiment of the present invention is significantly better than that of the comparative example at all stages.

[0132] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A composite negative electrode material, characterized in that It includes a core matrix and a composite layer provided on at least a portion of the surface of the core matrix; The core matrix includes graphite; The composite layer includes a composite of porous titanium oxide, conductive carbon material and lithium phenylsulfonate compound; The method for preparing the composite negative electrode material comprises the following steps: subjecting a first mixed system of a titanium source, a dispersant, a conductive carbon solution, graphite, an alkali solution, and a first solvent to a hydrothermal reaction, collecting a solid product after the reaction and sintering the solid product to obtain a first material; The first material, lithium phenylsulfonate and an organic solvent are mixed and dried to obtain a composite negative electrode material.

2. The composite negative electrode material according to claim 1, characterized in that Contains at least one of the following features (1) to (3): (1) In the composite negative electrode material, the mass fraction of the composite layer is 2% to 8%; (2) The conductive carbon material includes one or more of carbon nanotubes, graphene and conductive carbon black; (3) Lithium phenylsulfonate includes one or more of lithium 3-aminobenzenesulfonate, lithium isopropylbenzenesulfonate and lithium p-toluenesulfonate.

3. The composite negative electrode material according to claim 1, characterized in that Contains at least one of the following features (1) to (3): (1) The specific surface area of ​​the composite negative electrode material is 3~4.5m 2 / g; (2) The interlayer spacing of the composite negative electrode material is 0.3730~0.3810nm; (3) The ionic conductivity of the composite negative electrode material is 1×10 -9 ~9×10 -9 S / cm.

4. The method for preparing a composite negative electrode material according to any one of claims 1 to 3, wherein: The following steps are involved: subjecting a first mixed system of a titanium source, a dispersant, a conductive carbon solution, graphite, an alkali solution, and a first solvent to a hydrothermal reaction, collecting a solid product after the reaction and sintering the solid product to obtain a first material; The first material, lithium phenylsulfonate and an organic solvent are mixed and dried to obtain a composite negative electrode material.

5. The method for preparing a composite negative electrode material according to claim 4, wherein: Contains at least one of the following features (1) to (6): (1) The titanium source includes titanium chloride; (2) The dispersant includes at least one of sodium lauryl sulfate, polyvinyl alcohol and polyvinyl pyrrolidone; (3) The conductive carbon solution includes at least one of a carbon nanotube conductive solution, a graphene conductive solution, and a carbon black conductive solution; the mass concentration of the conductive carbon solution is 1% to 5%; (4) the alkali solution comprises at least one of N,N-dimethylethanolamine, diethylaminoethanol, dimethylaminopropylamine, dimethylamine and diethylamine; (5) The mass ratio of the titanium source, the dispersant, the conductive carbon solution, the graphite and the alkali solution is (50-100): (10-50): (10-50): 1000: (100-300); (6) The mass ratio of the titanium source to the first solvent is (50-100): (600-1500).

6. The method for preparing a composite negative electrode material according to claim 4 or 5, characterized in that: Contains at least one of the following features (1) to (4): (1) The preparation method of the mixed system specifically comprises: dispersing the titanium source and the dispersant in the first solvent, wherein the total mass of the titanium source and the dispersant accounts for 8% to 12% of the mass content of the first solvent, and then adding the conductive carbon solution, the graphite and the alkali solution; (2) The temperature of the hydrothermal reaction treatment is 100-200°C, and the time of the hydrothermal reaction treatment is 1-6 hours; (3) The sintering temperature is 500-800°C, and the sintering time is 1-6 hours; (4) A drying treatment is further performed between the hydrothermal reaction treatment and the sintering treatment; the temperature of the drying treatment is 60-90°C, and the time of the drying treatment is 15-25 hours.

7. The method for preparing a composite negative electrode material according to claim 4, wherein: Contains at least one of the following features (1) to (5): (1) The lithium phenylsulfonate includes at least one of lithium 3-aminobenzenesulfonate, lithium isopropylbenzenesulfonate and lithium p-toluenesulfonate; (2) The organic solvent includes at least one of ethanol, ether, carbon tetrachloride and tetrahydrofuran; (3) The mass ratio of the lithium phenylsulfonate to the first material is (5-10):1000; (4) The mass ratio of the lithium phenylsulfonate to the organic solvent is (5-10):100; (5) The drying includes spray drying, the inlet temperature of the spray drying is 200~240℃, the outlet temperature of the spray drying is 100~130℃, the flow rate of the spray drying is 0.1~0.5kg / h, and the time of the spray drying is 1~5h.

8. A negative electrode sheet, characterized in that: The invention comprises the composite negative electrode material according to any one of claims 1 to 3, or the composite negative electrode material prepared by the preparation method of the composite negative electrode material according to any one of claims 4 to 7.

9. A battery, characterized in that: Including the negative electrode sheet according to claim 8.

10. An electrical device, characterized in that: A battery comprising the battery of claim 9.

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