Carbon-based negative electrode material for flexible lithium battery and preparation method and application thereof

Abstract

The application discloses a carbon-based negative electrode material for flexible lithium batteries and a preparation method and application thereof, and belongs to the technical field of lithium batteries. The preparation method comprises the following steps: (1) treating eucalyptus sawdust with a treatment liquid I, drying and crushing to obtain eucalyptus wood powder, wherein the treatment liquid I is prepared from urea, potassium formate and water; (2) mixing the eucalyptus wood powder with magnesium chloride and then carbonizing to obtain a carbide; (3) treating the carbide with a treatment liquid II, wherein the treatment liquid II is prepared from 2-methyltetrahydrofuran, chlorobenzylamine, triethanolamine oleic acid soap and water; and (4) heat-treating the treated carbide to obtain the carbon-based negative electrode material for flexible lithium batteries. The application can effectively recycle eucalyptus sawdust resources, reduce the preparation cost of the negative electrode material, and the prepared carbon-based negative electrode material has good performance, high specific capacity and good cycle performance.

Description

Technical Field

[0001] This invention relates to the field of lithium battery technology, specifically to a carbon-based anode material for flexible lithium batteries, its preparation method, and its application. Background Technology

[0002] With the increasing global demand for clean energy, lithium batteries have been widely adopted. In recent years, with the rapid development of mobile communications, lithium-ion batteries have quickly replaced nickel-metal hydride and nickel-cadmium batteries, becoming the most popular high-energy batteries, and showing significant development prospects in fields such as electric vehicles and energy storage.

[0003] Graphite is a commonly used anode material in flexible lithium-ion batteries, mainly including artificial graphite and natural graphite. Natural graphite has advantages such as superior performance, low cost and availability, and mature technology. However, it also has disadvantages such as numerous surface defects, poor compatibility with electrolytes, poor cycle performance, and low rate capability. Therefore, research on artificial graphite anode materials remains a hot topic. Currently, the use of artificial graphite as an anode material in flexible lithium batteries still faces some problems, such as poor compatibility with electrolytes, poor charge-discharge performance, low specific capacity, and low battery cycle performance.

[0004] Eucalyptus is a fast-growing tree, characterized by rapid growth, strong adaptability, and wide range of uses. In recent years, eucalyptus plantations in my country have developed rapidly, gradually becoming one of the representative tree species in southern my country. Currently, eucalyptus is mainly used in furniture and building materials in my country, while also producing a large amount of eucalyptus sawdust and other waste. Eucalyptus sawdust is typically used as biomass fuel, supplied to power plants, factories, and other enterprises that require fuel, or returned to the fields or composted, indicating relatively low application value and a narrow scope. Summary of the Invention

[0005] The purpose of this invention is to address the aforementioned problems in the prior art and provide a method for preparing and applying a carbon-based anode material for flexible lithium batteries. This invention not only effectively recycles eucalyptus wood chips, reducing the preparation cost of the anode material, but also produces a carbon-based anode material with excellent performance, including high specific capacity and good cycle performance.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows:

[0007] A method for preparing a carbon-based anode material for flexible lithium batteries includes the following steps:

[0008] (1) Add eucalyptus wood chips to treatment solution I and soak for 1-3 hours. After drying, crush them to obtain eucalyptus wood powder. Treatment solution I is prepared by mixing the following components in parts by weight: 3-8 parts urea, 10-20 parts potassium formate, and 50-100 parts water.

[0009] (2) The eucalyptus wood powder obtained in step (1) is mixed with magnesium chloride at a mass ratio of 1:0.1-0.2. Under a nitrogen atmosphere, the temperature is first raised to 300-400℃ at a rate of 1-3℃ / min and held for 40-60min. Then, the temperature is raised to 400-600℃ at a rate of 5-10℃ / min and carbonized for 1-5h to obtain carbides.

[0010] (3) Add the carbide obtained in step (2) to treatment liquid II and stir. Treatment liquid II is prepared by mixing the following components in parts by weight: 10-30 parts of 2-methyltetrahydrofuran, 1-5 parts of chlorinated benzyl amine, 1-5 parts of triethanolamine oleic acid soap, and 50-60 parts of water. After treatment, separate to obtain the treated carbide.

[0011] (4) The processed carbide obtained in step (3) is subjected to heat treatment to obtain a carbon-based anode material for flexible lithium batteries.

[0012] Furthermore, in step (1), the mass ratio of the eucalyptus wood chips to the treatment liquid I is 1:10-20.

[0013] Furthermore, in step (3), the stirring conditions are controlled as follows: temperature 50-80℃, time 1-2h, and rotation speed 100-300r / min.

[0014] Furthermore, in step (3), the mass ratio of the carbide to the treatment liquid II is 1:5-30.

[0015] Furthermore, in step (4), the heat treatment temperature is 700-1000℃ and the time is 1-5h.

[0016] The present invention also provides a carbon-based anode material for flexible lithium batteries prepared by the above preparation method.

[0017] The present invention also provides the application of the carbon-based anode material for flexible lithium batteries prepared by the above preparation method, specifically applied to the anode sheet of flexible lithium batteries, wherein the anode material in the anode sheet is made of 85% to 95% by mass of the carbon-based anode material for flexible lithium batteries, 2% to 5% by mass of a conductive agent and 2% to 5% by mass of a binder.

[0018] The beneficial effects of this invention are as follows:

[0019] 1. This invention uses eucalyptus wood chips as the main raw material to prepare carbon-based anode materials, which can not only effectively recycle and utilize waste resources after eucalyptus processing and reduce preparation costs, but also broaden the application fields of eucalyptus wood chips and enhance their application value.

[0020] 2. The present invention prepares treatment solution I to treat eucalyptus wood chips and treatment solution II to treat carbides, so that the surface of the carbon-based negative electrode material has uniform reaction activity, stable surface crystal structure during charge and discharge, and uniform SEI film coverage. It has the characteristics of high specific capacity, good rate performance, high initial coulombic efficiency, and good cycle performance. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0022] Example 1

[0023] A method for preparing a carbon-based anode material for flexible lithium batteries includes the following steps:

[0024] (1) Add eucalyptus wood chips to treatment solution I and soak for 2 hours. After drying, crush them to obtain eucalyptus wood powder. The treatment solution I is prepared by mixing the following components in parts by weight: 5 parts urea, 15 parts potassium formate, and 70 parts water. The mass ratio of the eucalyptus wood chips to the treatment solution I is 1:15.

[0025] (2) The eucalyptus wood powder obtained in step (1) is mixed with magnesium chloride at a mass ratio of 1:0.1. Under a nitrogen atmosphere, the temperature is first raised to 350°C at a rate of 2°C / min and held for 50 min. Then, the temperature is raised to 500°C at a rate of 8°C / min and carbonized for 3 h to obtain carbides.

[0026] (3) The carbide obtained in step (2) is added to treatment liquid II and stirred. The mass ratio of the carbide to the treatment liquid II is 1:15. The stirring conditions are controlled as follows: temperature 70℃, time 1.5h, rotation speed 200r / min. The treatment liquid II is prepared by mixing the following components in parts by weight: 20 parts of 2-methyltetrahydrofuran, 3 parts of chlorinated benzyl amine, 3 parts of triethanolamine oleic acid soap, and 55 parts of water. The treated carbide is obtained by separation after treatment.

[0027] (4) The processed carbide obtained in step (3) is subjected to heat treatment at a temperature of 950°C for 2 hours to obtain a carbon-based anode material for flexible lithium batteries.

[0028] Example 2

[0029] A method for preparing a carbon-based anode material for flexible lithium batteries includes the following steps:

[0030] (1) Add eucalyptus wood chips to treatment solution I and soak for 1 hour. After drying, crush them to obtain eucalyptus wood powder. The treatment solution I is prepared by mixing the following components in parts by weight: 3 parts urea, 10 parts potassium formate, and 50 parts water. The mass ratio of the eucalyptus wood chips to the treatment solution I is 1:20.

[0031] (2) The eucalyptus wood powder obtained in step (1) is mixed with magnesium chloride at a mass ratio of 1:0.1. Under a nitrogen atmosphere, the temperature is first raised to 300°C at a rate of 1°C / min and held for 60 min. Then, the temperature is raised to 400°C at a rate of 5°C / min and carbonized for 5 h to obtain carbides.

[0032] (3) The carbide obtained in step (2) is added to treatment liquid II and stirred. The mass ratio of the carbide to the treatment liquid II is 1:5. The stirring conditions are controlled as follows: temperature 50℃, time 2h, speed 300r / min. The treatment liquid II is prepared by mixing the following components in parts by weight: 10 parts of 2-methyltetrahydrofuran, 1 part of chlorinated benzyl amine, 1 part of triethanolamine oleic acid soap, and 50 parts of water. The treated carbide is obtained by separation after treatment.

[0033] (4) The processed carbide obtained in step (3) is subjected to heat treatment at a temperature of 800°C for 5 hours to obtain a carbon-based anode material for flexible lithium batteries.

[0034] Example 3

[0035] A method for preparing a carbon-based anode material for flexible lithium batteries includes the following steps:

[0036] (1) Add eucalyptus wood chips to treatment solution I and soak for 3 hours. After drying, crush them to obtain eucalyptus wood powder. The treatment solution I is prepared by mixing the following components in parts by weight: 8 parts urea, 20 parts potassium formate, and 100 parts water. The mass ratio of the eucalyptus wood chips to the treatment solution I is 1:10.

[0037] (2) The eucalyptus wood powder obtained in step (1) is mixed with magnesium chloride at a mass ratio of 1:0.2. Under a nitrogen atmosphere, the temperature is first raised to 400°C at a rate of 3°C / min and held for 40 min. Then, the temperature is raised to 600°C at a rate of 10°C / min and carbonized for 1 h to obtain carbides.

[0038] (3) The carbide obtained in step (2) is added to treatment liquid II and stirred. The mass ratio of the carbide to treatment liquid II is 1:530. The stirring conditions are controlled as follows: temperature 80℃, time 1h, speed 100r / min. Treatment liquid II is prepared by mixing the following components in parts by weight: 30 parts of 2-methyltetrahydrofuran, 5 parts of chlorinated benzyl amine, 5 parts of triethanolamine oleic acid soap, and 60 parts of water. The treated carbide is obtained by separation after treatment.

[0039] (4) The processed carbide obtained in step (3) is subjected to heat treatment at a temperature of 1000°C for 1 hour to obtain a carbon-based anode material for flexible lithium batteries.

[0040] Example 4

[0041] A method for preparing a carbon-based anode material for flexible lithium batteries includes the following steps:

[0042] (1) Add eucalyptus wood chips to treatment solution I and soak for 2 hours. After drying, crush them to obtain eucalyptus wood powder. The treatment solution I is prepared by mixing the following components in parts by weight: 6 parts urea, 18 parts potassium formate, and 80 parts water. The mass ratio of the eucalyptus wood chips to the treatment solution I is 1:16.

[0043] (2) The eucalyptus wood powder obtained in step (1) is mixed with magnesium chloride at a mass ratio of 1:0.1. Under a nitrogen atmosphere, the temperature is first raised to 350°C at a rate of 3°C / min and held for 55 min. Then, the temperature is raised to 550°C at a rate of 6°C / min and carbonized for 2 h to obtain carbides.

[0044] (3) The carbide obtained in step (2) is added to treatment liquid II and stirred. The mass ratio of the carbide to treatment liquid II is 1:20. The stirring conditions are controlled as follows: temperature 60℃, time 2h, speed 300r / min. Treatment liquid II is prepared by mixing the following components in parts by weight: 25 parts of 2-methyltetrahydrofuran, 4 parts of chlorinated benzyl amine, 2 parts of triethanolamine oleic acid soap, and 55 parts of water. The treated carbide is obtained by separation after treatment.

[0045] (4) The processed carbide obtained in step (3) is subjected to heat treatment at a temperature of 800°C for 4 hours to obtain a carbon-based anode material for flexible lithium batteries.

[0046] Comparative Example 1

[0047] A method for preparing a carbon-based anode material for flexible lithium batteries includes the following steps:

[0048] (1) Dry the eucalyptus wood chips and then crush them to obtain eucalyptus wood powder.

[0049] (2) The eucalyptus wood powder obtained in step (1) is mixed with magnesium chloride at a mass ratio of 1:0.1. Under a nitrogen atmosphere, the temperature is first raised to 350°C at a rate of 2°C / min and held for 50 min. Then, the temperature is raised to 500°C at a rate of 8°C / min and carbonized for 3 h to obtain carbides.

[0050] (3) The carbide obtained in step (2) is added to treatment liquid II and stirred. The mass ratio of the carbide to the treatment liquid II is 1:15. The stirring conditions are controlled as follows: temperature 70℃, time 1.5h, rotation speed 200r / min. The treatment liquid II is prepared by mixing the following components in parts by weight: 20 parts of 2-methyltetrahydrofuran, 3 parts of chlorinated benzyl amine, 3 parts of triethanolamine oleic acid soap, and 55 parts of water. The treated carbide is obtained by separation after treatment.

[0051] (4) The processed carbide obtained in step (3) is subjected to heat treatment at a temperature of 950°C for 2 hours to obtain a carbon-based anode material for flexible lithium batteries.

[0052] Comparative Example 2

[0053] A method for preparing a carbon-based anode material for flexible lithium batteries includes the following steps:

[0054] (1) Add eucalyptus wood chips to treatment solution I and soak for 2 hours. After drying, crush the chips to obtain eucalyptus wood powder. Treatment solution I is prepared by mixing the following components in parts by weight: 5 parts urea, 15 parts potassium carbonate, and 70 parts water. The mass ratio of eucalyptus wood chips to treatment solution I is 1:15.

[0055] (2) The eucalyptus wood powder obtained in step (1) is mixed with magnesium chloride at a mass ratio of 1:0.1. Under a nitrogen atmosphere, the temperature is first raised to 350°C at a rate of 2°C / min and held for 50 min. Then, the temperature is raised to 500°C at a rate of 8°C / min and carbonized for 3 h to obtain carbides.

[0056] (3) The carbide obtained in step (2) is added to treatment liquid II and stirred. The mass ratio of the carbide to the treatment liquid II is 1:15. The stirring conditions are controlled as follows: temperature 70℃, time 1.5h, rotation speed 200r / min. The treatment liquid II is prepared by mixing the following components in parts by weight: 20 parts of 2-methyltetrahydrofuran, 3 parts of chlorinated benzyl amine, 3 parts of triethanolamine oleic acid soap, and 55 parts of water. The treated carbide is obtained by separation after treatment.

[0057] (4) The processed carbide obtained in step (3) is subjected to heat treatment at a temperature of 950°C for 2 hours to obtain a carbon-based anode material for flexible lithium batteries.

[0058] Comparative Example 3

[0059] A method for preparing a carbon-based anode material for flexible lithium batteries includes the following steps:

[0060] (1) Add eucalyptus wood chips to treatment solution I and soak for 2 hours. After drying, crush them to obtain eucalyptus wood powder. The treatment solution I is prepared by mixing the following components in parts by weight: 5 parts urea, 15 parts potassium formate, and 70 parts water. The mass ratio of the eucalyptus wood chips to the treatment solution I is 1:15.

[0061] (2) The eucalyptus wood powder obtained in step (1) is mixed with magnesium chloride at a mass ratio of 1:0.1. Under a nitrogen atmosphere, the temperature is first raised to 350°C at a rate of 2°C / min and held for 50 min. Then, the temperature is raised to 500°C at a rate of 8°C / min and carbonized for 3 h to obtain carbides.

[0062] (3) The carbide obtained in step (2) is subjected to heat treatment at a temperature of 950°C for 2 hours to obtain a carbon-based anode material for flexible lithium batteries.

[0063] Comparative Example 4

[0064] A method for preparing a carbon-based anode material for flexible lithium batteries includes the following steps:

[0065] (1) Add eucalyptus wood chips to treatment solution I and soak for 2 hours. After drying, crush them to obtain eucalyptus wood powder. The treatment solution I is prepared by mixing the following components in parts by weight: 5 parts urea, 15 parts potassium formate, and 70 parts water. The mass ratio of the eucalyptus wood chips to the treatment solution I is 1:15.

[0066] (2) The eucalyptus wood powder obtained in step (1) is mixed with magnesium chloride at a mass ratio of 1:0.1. Under a nitrogen atmosphere, the temperature is first raised to 350°C at a rate of 2°C / min and held for 50 min. Then, the temperature is raised to 500°C at a rate of 8°C / min and carbonized for 3 h to obtain carbides.

[0067] (3) The carbide obtained in step (2) is added to treatment liquid II and stirred. The mass ratio of the carbide to the treatment liquid II is 1:15. The stirring conditions are controlled as follows: temperature 70℃, time 1.5h, rotation speed 200r / min. The treatment liquid II is prepared by mixing the following components in parts by weight: 3 parts of chlorinated benzyl amine, 3 parts of triethanolamine oleic acid soap, and 55 parts of water. The treated carbide is separated after treatment.

[0068] (4) The processed carbide obtained in step (3) is subjected to heat treatment at a temperature of 950°C for 2 hours to obtain a carbon-based anode material for flexible lithium batteries.

[0069] Comparative Example 5

[0070] A method for preparing a carbon-based anode material for flexible lithium batteries includes the following steps:

[0071] (1) Add eucalyptus wood chips to treatment solution I and soak for 2 hours. After drying, crush them to obtain eucalyptus wood powder. The treatment solution I is prepared by mixing the following components in parts by weight: 5 parts urea, 15 parts potassium formate, and 70 parts water. The mass ratio of the eucalyptus wood chips to the treatment solution I is 1:15.

[0072] (2) The eucalyptus wood powder obtained in step (1) is mixed with magnesium chloride at a mass ratio of 1:0.1. Under a nitrogen atmosphere, the temperature is first raised to 350°C at a rate of 2°C / min and held for 50 min. Then, the temperature is raised to 500°C at a rate of 8°C / min and carbonized for 3 h to obtain carbides.

[0073] (3) The carbide obtained in step (2) is added to treatment liquid II and stirred. The mass ratio of the carbide to treatment liquid II is 1:15. The stirring conditions are controlled as follows: temperature 70℃, time 1.5h, rotation speed 200r / min. Treatment liquid II is prepared by mixing the following components in parts by weight: 20 parts of 2-methyltetrahydrofuran, 3 parts of triethanolamine oleic acid soap, and 55 parts of water. The treated carbide is separated after treatment.

[0074] (4) The processed carbide obtained in step (3) is subjected to heat treatment at a temperature of 950°C for 2 hours to obtain a carbon-based anode material for flexible lithium batteries.

[0075] Comparative Example 6

[0076] A method for preparing a carbon-based anode material for flexible lithium batteries includes the following steps:

[0077] (1) Add eucalyptus wood chips to treatment solution I and soak for 2 hours. After drying, crush them to obtain eucalyptus wood powder. The treatment solution I is prepared by mixing the following components in parts by weight: 5 parts urea, 15 parts potassium formate, and 70 parts water. The mass ratio of the eucalyptus wood chips to the treatment solution I is 1:15.

[0078] (2) The eucalyptus wood powder obtained in step (1) is mixed with magnesium chloride at a mass ratio of 1:0.1. Under a nitrogen atmosphere, the temperature is first raised to 350°C at a rate of 2°C / min and held for 50 min. Then, the temperature is raised to 500°C at a rate of 8°C / min and carbonized for 3 h to obtain carbides.

[0079] (3) The carbide obtained in step (2) is added to treatment liquid II and stirred. The mass ratio of the carbide to the treatment liquid II is 1:15. The stirring conditions are controlled as follows: temperature 70℃, time 1.5h, rotation speed 200r / min. The treatment liquid II is prepared by mixing the following components in parts by weight: 20 parts of 2-methyltetrahydrofuran, 3 parts of chlorinated benzyl amine, and 55 parts of water. The treated carbide is obtained by separation after treatment.

[0080] (4) The processed carbide obtained in step (3) is subjected to heat treatment at a temperature of 950°C for 2 hours to obtain a carbon-based anode material for flexible lithium batteries.

[0081] Comparative Example 7

[0082] A method for preparing a carbon-based anode material for flexible lithium batteries includes the following steps:

[0083] (1) Add coconut shell fragments to treatment solution I and soak for 2 hours. After drying, crush them to obtain coconut shell powder. The treatment solution I is prepared by mixing the following components in parts by weight: 5 parts urea, 15 parts potassium formate, and 70 parts water. The mass ratio of the coconut shell fragments to the treatment solution I is 1:15.

[0084] (2) Mix the coconut shell powder obtained in step (1) with magnesium chloride at a mass ratio of 1:0.1, and then heat it to 350°C at a rate of 2°C / min under a nitrogen atmosphere, hold it for 50 min, and then heat it to 500°C at a rate of 8°C / min for 3 h to obtain carbides.

[0085] (3) The carbide obtained in step (2) is added to treatment liquid II and stirred. The mass ratio of the carbide to the treatment liquid II is 1:15. The stirring conditions are controlled as follows: temperature 70℃, time 1.5h, rotation speed 200r / min. The treatment liquid II is prepared by mixing the following components in parts by weight: 20 parts of 2-methyltetrahydrofuran, 3 parts of chlorinated benzyl amine, 3 parts of triethanolamine oleic acid soap, and 55 parts of water. The treated carbide is obtained by separation after treatment.

[0086] (4) The processed carbide obtained in step (3) is subjected to heat treatment at a temperature of 950°C for 2 hours to obtain a carbon-based anode material for flexible lithium batteries.

[0087] The carbon-based anode materials obtained in Example 1 and Comparative Examples 1-7 were subjected to physicochemical property tests, and then fabricated into flexible batteries according to the following process, followed by electrical performance tests:

[0088] I. Preparation of the positive electrode sheet

[0089] The formulation (mass fraction) of the positive electrode active material is as follows: 94% lithium cobalt oxide, 3% conductive agent, and 3% PVDF binder; aluminum foil is used as the current collector for the positive electrode sheet. The lithium cobalt oxide, conductive agent, PVDF, and N-methylpyrrolidone are stirred to form a slurry. The slurry is then uniformly coated onto the aluminum foil and dried in an oven at 80℃~120℃. The slurry is then cut into electrode sheets with a length of 385mm, a width of 41mm, and a thickness of 0.10mm~0.15mm.

[0090] II. Preparation of the negative electrode sheet

[0091] The formulation (mass fraction) of the negative electrode material is as follows: 92% carbon-based negative electrode material for flexible lithium batteries, 4% conductive agent, and 4% LA133 binder. The carbon-based negative electrode material, conductive agent, LA133, and pure water are stirred to form a slurry. The slurry is then uniformly coated onto copper foil and dried in an oven at 80℃~120℃. The slurry is then cut into electrode sheets with a length of 350mm, a width of 42mm, and a thickness of 0.10mm~0.15mm.

[0092] III. Battery Assembly

[0093] Place the positive electrode, separator, and negative electrode into the aluminum-plastic film in that order. Then seal three sides of the aluminum-plastic film with a sealing machine. Place the aluminum-plastic film into a glove box and inject electrolyte into the unsealed side. Use 1 mol / L LiPF6 / (EC+DEC) (mass ratio 1:1) as the electrolyte. After the electrolyte is injected, seal the unsealed side of the aluminum-plastic film to complete the assembly of the flexible lithium battery.

[0094] IV. Battery Formation

[0095] The flexible lithium battery was formed at 20℃~25℃ according to the mass and specific capacity of the lithium cobalt oxide contained in the battery. The formation steps were as follows: rest for 5 min, constant current charging at 0.02C for 60 min, constant current and constant voltage charging at 0.05C and 3.75V for 240 min, constant current and constant voltage charging at 0.05C and 3.90V for 330 min, rest for 10 min, constant current and constant voltage charging at 0.10C and 3.95V for 120 min, rest for 10 min, constant current and constant voltage charging at 0.10C and 3.95V for 90 min, rest for 5 min, and then stop to complete the formation.

[0096] V. Battery Testing

[0097] The formed flexible lithium battery was tested using a lithium-ion battery performance tester, and the charge / discharge regime was as follows:

[0098] a) Charging limit voltage: 4.20V;

[0099] b) Discharge termination voltage: 2.75V;

[0100] c) Charge and discharge cycle: Charge-discharge cycle shall be performed in accordance with the provisions of 5.3.2.8 in GB / T 18287-2013.

[0101] The relevant test results are shown in Table 1 below.

[0102] Table 1. Test results of physicochemical and electrical properties of carbon-based anode materials in Examples 1 and Comparative Examples 1-7

[0103] Group <![CDATA[Tap density (g / cm 3 )]]> <![CDATA[Specific surface area (m 2 / g)]]> 1.0C capacity (mAh / g) First coulomb efficiency (%) Example 1 1.01 1.23 358.4 93.1 Comparative Example 1 0.86 3.05 222.6 78.2 Comparative Example 2 0.97 1.87 340.3 90.6 Comparative Example 3 0.84 3.34 186.3 71.5 Comparative Example 4 0.89 2.46 301.2 82.3 Comparative Example 5 0.93 2.18 330.5 90.0 Comparative Example 6 0.95 2.00 337.0 89.4 Comparative Example 7 0.90 2.37 315.3 86.3

[0104] As can be seen from the data in Example 1 in Table 1, the carbon-based anode material of the present invention has a suitable specific surface area and, as a flexible lithium battery electrode material, has excellent properties such as high specific capacity, good rate performance, and high initial coulombic efficiency.

[0105] Comparison of the data from Comparative Examples 1-7 and Example 1 shows that each component in Treatment Solution I and Treatment Solution II of the present invention has a significant impact on the performance of the carbon-based anode material. Through treatment with Treatment Solution I and Treatment Solution II, the various properties of the carbon-based anode material prepared from eucalyptus wood chips can be significantly improved.

[0106] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications and improvements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be defined by the claims.

Claims

1. A method for preparing a carbon-based anode material for flexible lithium batteries, characterized in that, Includes the following steps: (1) Add eucalyptus wood chips to treatment solution I and soak for 1-3 hours. After drying, crush them to obtain eucalyptus wood powder. Treatment solution I is prepared by mixing the following components in parts by weight: 3-8 parts urea, 10-20 parts potassium formate, and 50-100 parts water. (2) After mixing the eucalyptus wood powder obtained in step (1) with magnesium chloride at a mass ratio of 1:0.1-0.2, under a nitrogen atmosphere, first heat the mixture to 300-400℃ at a rate of 1-3℃ / min, hold it at that temperature for 40-60min, and then heat it to 400-600℃ at a rate of 5-10℃ / min for 1-5h to obtain carbides; (3) Add the carbide obtained in step (2) into treatment liquid II and stir. Treatment liquid II is prepared by mixing the following components in parts by weight: 10-30 parts of 2-methyltetrahydrofuran, 1-5 parts of chlorinated benzyl amine, 1-5 parts of triethanolamine oleic acid soap, and 50-60 parts of water. After treatment, separate to obtain the treated carbide. (4) The processed carbide obtained in step (3) is subjected to heat treatment at a temperature of 700-1000℃ for 1-5h to obtain a carbon-based anode material for flexible lithium batteries.

2. The method for preparing a carbon-based anode material for flexible lithium batteries according to claim 1, characterized in that: In step (1), the mass ratio of the eucalyptus wood chips to the treatment liquid I is 1:10-20.

3. The method for preparing a carbon-based anode material for flexible lithium batteries according to claim 1, characterized in that: In step (3), the stirring conditions are controlled as follows: temperature 50-80℃, time 1-2h, and rotation speed 100-300r / min.

4. The method for preparing a carbon-based anode material for flexible lithium batteries according to claim 1, characterized in that: In step (3), the mass ratio of the carbide to the treatment liquid II is 1:5-30.

5. A carbon-based anode material for flexible lithium batteries, characterized in that: It is prepared by any one of the preparation methods of claims 1-4.

6. The application of the carbon-based anode material for flexible lithium batteries according to claim 5, characterized in that: In the negative electrode sheet used in flexible lithium batteries, the negative electrode material in the negative electrode sheet is made of 92% to 95% by mass of the carbon-based negative electrode material for flexible lithium batteries of claim 5, 2% to 5% by mass of the conductive agent, and 2% to 5% by mass of the binder.