Composite electrode material and preparation method and application thereof

Abstract

The application relates to the technical field of batteries, in particular to a composite electrode material and a preparation method and application thereof. A preparation method of a composite electrode material comprises the following steps: first heat treatment of a graphite material and potassium manganate to obtain mesoporous graphite, deposition of a gaseous silicon source on the mesoporous graphite to obtain a porous silicon-carbon material; second heat treatment of the porous silicon-carbon material and a mixed system of a titanium source alcohol solution to obtain the composite electrode material. The mesoporous graphite with a suitable mesoporosity is prepared by etching graphite with potassium manganate, space is reserved for the expansion of silicon, the material is prevented from being broken in the charging lithium intercalation process, and lithium ion diffusion is facilitated; a titanium nitride coating layer can prevent fluorine ions in an electrolyte from penetrating into the material interior to cause a side reaction, has good lithium ion diffusion, reduces an interface side reaction, and the material surface still has good lithium ion diffusion capacity after circulation.

Description

Technical Field

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

[0002] With the rapid development and continuous expansion of the new energy vehicle industry, the development of high-power, high-capacity, and high-safety battery systems is urgently needed. Silicon-carbon anode materials have gained widespread attention and extensive research due to their advantages such as high theoretical specific capacity, low lithium intercalation potential, abundant raw materials, non-toxicity, and environmental friendliness, and are expected to replace carbon anode materials as the next generation of high-performance lithium battery anode materials.

[0003] Silicon, as a semiconductor, has poor conductivity. Furthermore, the massive volume expansion of silicon-carbon anode materials during lithium insertion / extraction leads to the breakage and pulverization of active particles, and the unstable and continuously growing SEI film structure, further increasing interfacial impedance. This results in a rapid decline in the electrochemical performance of silicon anodes and a low cycle life. Therefore, preparing silicon-carbon materials with a stable structure that can accommodate silicon expansion is crucial for reducing material fragmentation during the expansion process and enhancing cycle performance.

[0004] Traditionally, silicon-carbon materials are coated with carbon, but the carbon layer lacks selective permeability to the electrolyte, leading to reactions between the internal silicon and lithium ions in the electrolyte, resulting in increased side reactions. Therefore, it is necessary to develop novel coating layers that prevent lithium ions from the electrolyte from passing through, thereby reducing side reactions, while ensuring good conductivity and lithium ion diffusion performance.

[0005] In view of this, the present invention is hereby proposed. Summary of the Invention

[0006] One objective of this invention is to provide a method for preparing a composite electrode material to solve the technical problems of rapid electrochemical performance degradation and low cycle life of existing silicon-carbon materials.

[0007] Another objective of this invention is to provide a composite electrode material that has low expansion, high lithium-ion diffusion capacity, few interfacial side reactions, and good cycle performance.

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

[0009] Another object of the present invention is to provide a battery.

[0010] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted:

[0011] A method for preparing a composite electrode material includes the following steps:

[0012] Graphite material and potassium manganate are subjected to a first heat treatment to obtain mesoporous graphite. A gaseous silicon source is deposited on the mesoporous graphite to obtain a porous silicon-carbon material. The mixture of the porous silicon-carbon material and a titanium source alcohol solution is subjected to a second heat treatment to obtain a composite electrode material.

[0013] In some embodiments, the mass ratio of the graphite material to potassium manganate is 2:(4-7).

[0014] In some embodiments, the temperature of the first heat treatment is 1000–1200°C, and the duration of the first heat treatment is 3–6 hours.

[0015] In some embodiments, the mesoporous graphite has a mesoporous ratio of 50% to 70%.

[0016] In some embodiments, after the first heat treatment, the process further includes washing and drying to obtain the mesoporous graphite.

[0017] In some embodiments, during the deposition of the gaseous silicon source on the mesoporous graphite, the deposition temperature is 400–800°C, the deposition time is 1–15 h, the pressure is 0.01–10 kPa, and the flow rate of the gaseous silicon source is 0.5–2 L / min.

[0018] In some embodiments, the titanium source alcohol solution includes a titanium tetrachloride ethanol solution.

[0019] In some embodiments, the mass fraction of the titanium source alcohol solution is 8% to 12%.

[0020] In some embodiments, the mass ratio of the titanium source alcohol solution to the porous silicon-carbon material is (2-4):1.

[0021] In some embodiments, the second heat treatment includes preheating and calcination.

[0022] In some embodiments, the preheating temperature is 400–550°C, and the preheating time is 1–5 hours.

[0023] In some embodiments, the calcination temperature is 1400–1600°C, and the holding time is 3–7 hours.

[0024] In some embodiments, the calcination is carried out under a protective gas atmosphere at a pressure of 0.08–0.12 MPa.

[0025] A composite electrode material is prepared by the method described above.

[0026] An electrode sheet comprising a composite electrode material prepared by the method described above, or the composite electrode material itself.

[0027] A battery comprising the aforementioned electrode plates.

[0028] An electrical device, including the battery.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0030] (1) The method for preparing the composite electrode material of the present invention involves preparing mesoporous graphite with a suitable mesoporous ratio by etching graphite with potassium manganate, which reserves space for the expansion of silicon and prevents the material from breaking during the charging and lithium intercalation process. At the same time, the mesoporous structure is conducive to the diffusion of lithium ions. The titanium source alcohol solution is mixed with porous silicon carbon material for coating, and the resulting titanium nitride coating layer can prevent fluoride ions in the electrolyte from entering the material through the coating layer to carry out side reactions. At the same time, the coating layer has good lithium ion diffusion. Due to the reduction of interfacial side reactions, the interfacial impedance does not change much, and the material surface still has good lithium ion diffusion ability after cycling.

[0031] (2) The composite electrode material of the present invention has a core of silicon-carbon material and mesoporous graphite as a space reserved for the expansion of silicon to prevent the material from breaking during the charging and lithium intercalation process. At the same time, the appropriate mesoporous ratio is conducive to lithium ion diffusion. The titanium nitride coating layer on the surface of the silicon-carbon material can improve lithium ion diffusion, has good conductivity, reduces interfacial side reactions, and has good cycle stability.

[0032] (3) The battery of the present invention has excellent lithium-ion diffusion capability, low full-charge expansion, good cycle performance and high safety. Detailed Implementation

[0033] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0034] According to one aspect of the present invention, the present invention relates to a method for preparing a composite electrode material, comprising the following steps:

[0035] The graphite material and potassium manganate (K2MnO4) are subjected to a first heat treatment to obtain mesoporous graphite. A gaseous silicon source is deposited on the mesoporous graphite to obtain a porous silicon-carbon material. The mixture of the porous silicon-carbon material and a titanium source alcohol solution is subjected to a second heat treatment to obtain a composite electrode material.

[0036] The method of this invention prepares mesoporous graphite with suitable mesopority by etching graphite with potassium manganate, and deposits silicon within the mesoporous graphite pores. The mesopores pre-reserve space for silicon expansion, preventing material breakage during charging and lithium intercalation, while also facilitating lithium-ion diffusion. The reaction principles include: K₂MnO₄ + C → K₂CO₃ + MnO; 2MnO₂ + C → 2MnO + CO₂. A titanium-based alcohol solution is mixed with porous silicon-carbon material for coating. Through carbothermic reduction nitridation, a titanium nitride (TiN) coating layer is obtained. This layer prevents fluoride ions in the electrolyte from penetrating the coating layer and entering the material interior to undergo side reactions. Simultaneously, the coating layer exhibits good lithium-ion diffusion. Due to the reduction of interfacial side reactions, the interfacial impedance changes little, and the material surface still possesses good lithium-ion diffusion capabilities after cycling.

[0037] In some embodiments, the mass ratio of graphite material to potassium manganate is 2:(4-7), for example, 2:4, 2:4.5, 2:5, 2:6, or 2:7. The present invention uses a suitable mass ratio of graphite material and potassium manganate to obtain graphite with a suitable mesoporous ratio. If the amount of potassium manganate is too low or too high, the resulting graphite will have a mesoporous ratio that is either too low or too high, which will be detrimental to the performance of the composite electrode material.

[0038] In some embodiments, the temperature of the first heat treatment is 1000–1200°C, including but not limited to 1000°C, 1050°C, 1080°C, 1100°C, 1120°C, 1150°C, 1180°C, 1200°C, or any value within a range of both. The duration of the first heat treatment is 3–6 hours, for example, 3 hours, 3.5 hours, 4 hours, 4.5 hours, 5 hours, 5.5 hours, or 6 hours, or any value within a range of both. Suitable first heat treatment conditions can ensure the physicochemical properties of mesoporous graphite.

[0039] In some embodiments, the mesoporous graphite has a mesoporosity of 50% to 70%, including but not limited to 50%, 52%, 55%, 56%, 58%, 60%, or 70%, or any value between the two. The mesoporous graphite of the present invention has a suitable mesoporosity to ensure silicon loading effect, ensure the electrical properties of silicon-carbon materials, facilitate the subsequent carbon nitride coating effect, and improve the overall electrical properties of composite electrode materials.

[0040] In some embodiments, after the first heat treatment, washing and drying are further included to obtain mesoporous graphite. Washing is performed by acid washing, such as with a hydrochloric acid solution, followed by filtration to neutrality and vacuum drying to obtain mesoporous graphite.

[0041] In some embodiments, during the deposition of a gaseous silicon source on mesoporous graphite, the deposition temperature is 400–800°C, including but not limited to 400°C, 450°C, 480°C, 500°C, 550°C, 600°C, 700°C, or 800°C, or any range between two values. The deposition time is 1–15 h, for example, 1 h, 2 h, 4 h, 8 h, 9 h, 10 h, 11 h, 12 h, 13 h, 14 h, or 15 h, or any range between two values. The pressure is 0.01–10 kPa, for example, 0.01 kPa, 0.05 kPa, 0.1 kPa, 1 kPa, 5 kPa, or 10 kPa. The flow rate of the gaseous silicon source is 0.5–2 L / min, for example, 0.5 L / min, 0.8 L / min, 1 L / min, 1.5 L / min, or 2 L / min. In some embodiments, the gaseous silicon source includes at least one of trichloromethylsilane, dichlorodimethylsilane, tetraethoxysilane, methyltriethoxysilane, methylsilane, silane, ethylsilane, and trichlorosilane. The suitable deposition conditions of this invention ensure effective silicon deposition and superior electrical properties of the silicon-carbon material.

[0042] In some embodiments, the titanium source alcohol solution comprises a titanium tetrachloride ethanol solution. The mass fraction of the titanium source alcohol solution is 8% to 12%, for example, 8%, 9%, 10%, 11%, or 12%, or any value in between. A suitable concentration of the titanium source alcohol solution is beneficial to its coating effect, forming a more uniform coating layer.

[0043] In some embodiments, the mass ratio of the titanium source alcohol solution to the porous silicon-carbon material is (2–4):1, for example, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, etc. Using an appropriate mass ratio of the titanium source alcohol solution and the porous silicon-carbon material ensures the formation of a uniform titanium nitride coating layer of suitable thickness. If the mass of the titanium source alcohol solution is too high, the coating layer will be too thick; if the mass of the titanium source alcohol solution is too low, the coating layer will be too thin, both of which will reduce the electrochemical performance of the final composite electrode material.

[0044] In some embodiments, the second heat treatment includes preheating and calcination. The preheating temperature is 400–550°C, for example, 400°C, 420°C, 450°C, 480°C, 500°C, 520°C, 550°C, or any range between two values, and the preheating time is 1–5 hours, for example, 1 hour, 2 hours, 3 hours, 4 hours, or 5 hours. The calcination temperature is 1400–1600°C, for example, 1400°C, 1420°C, 1450°C, 1480°C, 1500°C, 1520°C, 1550°C, 1580°C, 1600°C, or any range between two values. The holding time is 3–7 hours, for example, 3 hours, 3.5 hours, 4 hours, 5 hours, 6 hours, or 7 hours. Calcination is carried out under a protective gas environment, such as nitrogen, at a pressure of 0.08–0.12 MPa, for example 0.09 MPa, 0.1 MPa, 0.12 MPa, etc.

[0045] In a preferred embodiment, the method for preparing the composite electrode material includes the following steps:

[0046] (a) Artificial graphite and potassium manganate were mixed and placed in a reaction vessel at a mass ratio of 2:(4-7). The mixture was heated to 1000-1200°C for 3-7 hours. The reactants were washed with hydrochloric acid solution, then filtered until neutral and dried under vacuum to obtain mesoporous graphite.

[0047] (b) Mesoporous graphite is added to a fluidized bed reactor, a silane / nitrogen mixed gas is introduced, the pressure inside the reactor is 0.01-10 kPa, the flow rate of the gaseous silicon source is 0.5-2 L / min, and the reaction is carried out at 400-800℃ for 1-15 h to obtain porous silicon-carbon material.

[0048] (c) A titanium tetrachloride ethanol solution (mass fraction of 8%–15%) and porous silicon carbon material are mixed and stirred at a mass ratio of (2–4):1. The resulting slurry is pre-calcined at 400–550°C to remove moisture and other volatile substances. Then, under a nitrogen atmosphere, the pre-calcined mixture is heated to 1400–1600°C and held at that temperature for 3–7 hours at a pressure of 0.08–0.12 MPa. After the reaction is complete, the mixture is allowed to cool naturally to obtain the composite electrode material, namely titanium nitride-coated porous silicon carbon material.

[0049] According to another aspect of the present invention, the present invention also relates to a composite electrode material, which is prepared by the method for preparing the composite electrode material.

[0050] The composite electrode material of the present invention has a silicon-carbon core, and mesoporous graphite provides space for the expansion of silicon, preventing the material from breaking during charging and lithium intercalation. At the same time, the appropriate mesoporous ratio is conducive to lithium-ion diffusion. The surface of the silicon-carbon material is coated with a titanium nitride coating layer, which has good lithium-ion diffusion, few interfacial side reactions, and little change in interfacial impedance. After cycling, the material surface still has good lithium-ion diffusion capability.

[0051] According to another aspect of the present invention, the present invention also relates to an electrode sheet comprising a composite electrode material prepared by the method for preparing the composite electrode material, or the composite electrode material described above.

[0052] In some embodiments, the electrode sheet includes a negative current collector and a negative active layer located on the surface of the negative current collector, the negative active layer containing the aforementioned composite electrode material, conductive agent and binder.

[0053] According to another aspect of the invention, the invention also relates to a battery comprising the electrode sheets described above.

[0054] The battery of this invention has excellent lithium-ion diffusion capability, low full-charge expansion, and good cycle performance.

[0055] According to another aspect of the invention, the invention also relates to an electrical device comprising the battery described above. The electrical device includes electric vehicles, etc.

[0056] The following explanation, combined with specific embodiments and comparative examples, further illustrates the point.

[0057] Example 1

[0058] A method for preparing a composite electrode material includes the following steps:

[0059] (1) Artificial graphite and K2MnO4 were mixed and placed in a reaction vessel (mass ratio 2:5), and heated to 1100℃ for 5 hours. The reactants were washed with hydrochloric acid solution, then filtered until neutral and dried under vacuum to obtain mesoporous graphite.

[0060] (2) Mesoporous graphite was added to a fluidized bed reactor and a mixture of silane and nitrogen was introduced. The flow rate of silane was 2 L / min, the volume ratio of silane to nitrogen was 1:1, the pressure inside the reactor was 5 kPa, and the reaction was carried out at 500℃ for 12 h to obtain porous silicon-carbon material.

[0061] (3) A titanium tetrachloride ethanol solution (mass fraction of 10%) and porous silicon carbon material were mixed and stirred at a mass ratio of 3:1. The mixture was then pre-calcined at 500°C to remove moisture and other volatile substances. Then, under a nitrogen atmosphere, the pre-calcined mixture was heated to 1500°C and held at that temperature for 5 hours at a pressure of 0.1 MPa. After the reaction was completed, it was allowed to cool naturally to obtain the composite electrode material, namely titanium nitride coated porous silicon carbon material.

[0062] Example 2

[0063] A method for preparing a composite electrode material includes the following steps:

[0064] (1) Artificial graphite and K2MnO4 were mixed and placed in a reaction vessel (mass ratio 2:6), and heated to 1150℃ for 4 hours. The reactants were washed with hydrochloric acid solution, then filtered until neutral and dried under vacuum to obtain mesoporous graphite.

[0065] (2) Mesoporous graphite was added to a fluidized bed reactor and a mixture of silane and nitrogen was introduced. The flow rate of silane was 2 L / min, the volume ratio of silane to nitrogen was 1:1, the pressure inside the reactor was 5 kPa, and the reaction was carried out at 550℃ for 10 h to obtain porous silicon-carbon material.

[0066] (3) A titanium tetrachloride ethanol solution (mass fraction of 10%) and porous silicon carbon material were mixed and stirred at a mass ratio of 3.5:1. The mixture was then pre-calcined at 470°C to remove moisture and other volatile substances. Then, under a nitrogen atmosphere, the pre-calcined mixture was heated to 1540°C and held at that temperature for 4 hours at a pressure of 0.1 MPa. After the reaction was completed, it was allowed to cool naturally to obtain the composite electrode material, namely titanium nitride coated porous silicon carbon material.

[0067] Example 3

[0068] A method for preparing a composite electrode material includes the following steps:

[0069] (1) Artificial graphite and K2MnO4 were mixed and placed in a reaction vessel (mass ratio 2:4), and heated to 1200℃ for 3 hours. The reactants were washed with hydrochloric acid solution, then filtered until neutral and dried under vacuum to obtain mesoporous graphite.

[0070] (2) Mesoporous graphite was added to a fluidized bed reactor and a mixture of silane and nitrogen was introduced. The flow rate of silane was 1.5 L / min, the volume ratio of silane to nitrogen was 1:1, the pressure inside the reactor was 0.01 Kpa, and the reaction was carried out at 400℃ for 15 h to obtain porous silicon-carbon material.

[0071] (3) A titanium tetrachloride ethanol solution (mass fraction of 10%) and porous silicon carbon material were mixed and stirred at a mass ratio of 4:1. The mixture was then pre-calcined at 550°C to remove moisture and other volatile substances. Then, under a nitrogen atmosphere, the pre-calcined mixture was heated to 1400°C and held at that temperature for 7 hours at a pressure of 0.08 MPa. After the reaction was completed, it was naturally cooled to obtain the composite electrode material, namely titanium nitride coated porous silicon carbon material.

[0072] Example 4

[0073] A method for preparing a composite electrode material includes the following steps:

[0074] (1) Artificial graphite and K2MnO4 were mixed and placed in a reaction vessel (mass ratio 2:7), and heated to 1000℃ for 6 hours. The reactants were washed with hydrochloric acid solution, then filtered until neutral and dried under vacuum to obtain mesoporous graphite.

[0075] (2) Mesoporous graphite was added to a fluidized bed reactor and a mixture of silane and nitrogen was introduced. The flow rate of silane was 2 L / min, the volume ratio of silane to nitrogen was 1:1, the pressure inside the reactor was 10 kPa, and the reaction was carried out at 600 °C for 8 h to obtain porous silicon-carbon material.

[0076] (3) A titanium tetrachloride ethanol solution (mass fraction of 10%) and porous silicon carbon material were mixed and stirred at a mass ratio of 2:1. The mixture was then pre-calcined at 400°C to remove moisture and other volatile substances. Then, under a nitrogen atmosphere, the pre-calcined mixture was heated to 1600°C and held at that temperature for 3 hours at a pressure of 0.12 MPa. After the reaction was completed, it was allowed to cool naturally to obtain the composite electrode material, namely titanium nitride coated porous silicon carbon material.

[0077] Example 5

[0078] A method for preparing a composite electrode material differs from that in Example 1 in that:

[0079] The mass ratio of artificial graphite to K2MnO4 is 1:6.

[0080] Example 6

[0081] A method for preparing a composite electrode material differs from that in Example 1 in that:

[0082] The mass ratio of artificial graphite to K2MnO4 is 6:5.

[0083] Example 7

[0084] A method for preparing a composite electrode material differs from that in Example 1 in that:

[0085] The mass ratio of titanium tetrachloride ethanol solution to porous silicon carbide material is 6:1.

[0086] Comparative Example 1

[0087] A method for preparing a composite electrode material includes the following steps:

[0088] Following steps (1) and (2) of Example 1, a porous silicon-carbon material was obtained.

[0089] Comparative Example 2

[0090] A method for preparing a composite electrode material differs from that in Example 1 in that:

[0091] Following steps (1) and (2) of Example 1, porous silicon-carbon material was obtained. The porous silicon-carbon material was then left in the fluidized bed reactor, and acetylene gas was introduced. The mixture was then subjected to high-temperature pyrolysis at 600°C for 5 hours to obtain carbon-coated porous silicon-carbon material.

[0092] Experimental Example

[0093] The composite electrode materials prepared in the above embodiments and comparative examples were mixed and stirred evenly with binder polyacrylic acid, conductive carbon black, and dispersant sodium carboxymethyl cellulose. The mass ratio of the composite electrode material, polyacrylic acid, conductive carbon black, and sodium carboxymethyl cellulose was 95:1:2:2. After mixing the materials with water, a negative electrode slurry was obtained. The negative electrode slurry was then coated onto copper foil, dried, and cut to obtain a negative electrode sheet. LiPF6 was used as the electrolyte with a concentration of 1.5 mol / L, and the solvent was a mixture of EC and DEC with a volume ratio of 1:1. A lithium metal sheet was used as the counter electrode, and a polypropylene (PP) membrane was used as the separator. Button cells were assembled in an argon-filled glove box. The performance of the battery was tested as follows:

[0094] 1. Diffusion coefficient test

[0095] Assemble the negative electrode and lithium sheet into a coin cell and discharge it at 0.1C for 2 minutes per step. Let it stand for 30 minutes. Repeat the above steps until the voltage is less than 0.005V. Record the voltage at each step and calculate the lithium-ion diffusion coefficient.

[0096] 2. Fully charged expansion

[0097] The initial negative electrode thickness D0 was tested. The negative electrode and lithium sheet were assembled into a coin cell and discharged at 0.1C until the voltage was <0.005V. After standing for 30 minutes, it was discharged at 0.02C until the voltage was <0.005V. The negative electrode thickness D1 was then tested after disassembly. The expansion rate was calculated as (D1-D0) / (D0-D0). 铜箔 ).

[0098] 3. Cyclic performance test

[0099] The prepared coin cells were subjected to cyclic charging and discharging at a rate of 0.1C, with a voltage range of 0.005-1.5V, and the capacity retention rate was recorded after 600 cycles.

[0100] The test results are shown in Table 1.

[0101] Table 1 Test Results

[0102]

[0103] As shown in Table 1, the batteries prepared from the composite electrode materials obtained by the methods in Examples 1 to 4 of this invention have suitable diffusion coefficients, low expansion coefficients, high initial efficiency, and high capacity retention.

[0104] Comparing Examples 1 and 5-6, it can be seen that Example 1 of the present invention uses K2MnO4 to etch artificial graphite. A suitable ratio can result in a material with a lower expansion rate, a suitable mesoporous ratio, and better lithium-ion diffusion capability. If the ratio of K2MnO4 is too low, the resulting material has fewer mesopores, making silicon deposition difficult and unable to effectively buffer the volume expansion of silicon; if the ratio of K2MnO4 is too high, the resulting material has a lower first-efficiency.

[0105] Comparing Examples 1, 7, and 1, it is evident that the material in Comparative Example 1, without TiN coating, cannot prevent side reactions between the electrolyte and the material, resulting in rapid capacity decay and poor cycle performance. Furthermore, due to the high interfacial impedance after cycling, the lithium-ion diffusion coefficient decreases significantly. Similarly, the excessive TiN coating in Example 7 also reduces lithium-ion transport performance.

[0106] Comparing Example 1 and Comparative Example 2, it can be seen that the TiN-coated porous silicon-carbon material in Example 1 has a significant effect on reducing material side reactions and maintaining lithium-ion diffusion after cycling compared to the carbon-coated material in Comparative Example 2.

[0107] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions 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 method for preparing a composite electrode material, characterized in that, Includes the following steps: Graphite material and potassium manganate are subjected to a first heat treatment to obtain mesoporous graphite, and a gaseous silicon source is deposited on the mesoporous graphite to obtain porous silicon-carbon material. The mixture of the porous silicon-carbon material and the titanium-source alcohol solution is subjected to a second heat treatment to obtain a composite electrode material. The mass ratio of the graphite material to potassium manganate is 2:(4~7). The titanium source alcohol solution includes titanium tetrachloride ethanol solution; the mass fraction of the titanium source alcohol solution is 8%~12%; the mass ratio of the titanium source alcohol solution to the porous silicon carbide material is (2~4):1; The temperature of the first heat treatment is 1000~1200℃; The second heat treatment includes preheating and calcination; the preheating temperature is 400~550℃; the calcination temperature is 1400~1600℃.

2. The method for preparing the composite electrode material according to claim 1, characterized in that, The first heat treatment lasts for 3 to 6 hours; And / or, the mesoporous graphite has a mesoporous ratio of 50% to 70%; And / or, after the first heat treatment, washing and drying are also included to obtain the mesoporous graphite.

3. The method for preparing the composite electrode material according to claim 1, characterized in that, During the deposition of gaseous silicon source on the mesoporous graphite, the deposition temperature is 400~800℃, the deposition time is 1~15h, the pressure is 0.01~10Kpa, and the flow rate of gaseous silicon source is 0.5~2L / min.

4. The method for preparing the composite electrode material according to claim 1, characterized in that, The preheating time is 1-5 hours; And / or, the calcination holding time is 3~7h; And / or, the calcination is carried out under a protective gas condition at a pressure of 0.08~0.12 MPa.

5. A composite electrode material, characterized in that, The composite electrode material is prepared by any one of claims 1 to 4.

6. An electrode sheet, characterized in that, The composite electrode material prepared by the method described in any one of claims 1 to 4, or the composite electrode material described in claim 5.

7. A battery, characterized in that, Includes the electrode sheet as described in claim 6.

8. An electrical appliance, characterized in that, Includes the battery as described in claim 7.

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