Shell activated carbon as well as preparation method and application thereof

Abstract

The invention relates to the technical field of lithium ion battery materials, in particular to shell activated carbon and a preparation method and application thereof.The preparation method comprises the following steps that a shell raw material is washed and then dried, and the dried shell raw material is obtained; carbonizing the dried shell raw material to obtain shell carbon; crushing the shell carbon to obtain shell carbon powder; placing the shell carbon powder in a transfer activation furnace, heating in a nitrogen atmosphere and then preserving heat, heating in a water vapor atmosphere and then preserving heat, and then cooling to obtain a shell activated carbon crude product; pickling and drying the shell activated carbon crude product to obtain a dried shell activated carbon crude product; and crushing the dried shell activated carbon crude product, sieving, heating, preserving heat, and cooling to obtain a shell activated carbon finished product. The fruit shell raw material used in the invention has the advantages of wide source and low price; the method is convenient and simple, and is suitable for large-scale industrial production. The composite material shows good performance when applied to a silicon-carbon negative electrode material.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium-ion battery materials, and particularly to a fruit shell activated carbon and a preparation method and application thereof. Background Art

[0002] Whether in industrial production or daily life, a large amount of biomass waste will be generated. The rich reserves and low price of biomass enable biomass carbon materials to be widely used in the field of functional materials. Among them, fruit shell carbon materials have great prospects in the application research for preparing silicon-carbon anode materials for lithium-ion batteries due to their rich pore structure, high specific surface area, and appropriate mesopore ratio.

[0003] Among many biomass wastes, fruit shells have the largest cellulose content. In addition, their delicate structure and fine texture endow them with a certain tensile strength. Compared with other biomass carbons, fruit shell activated carbon has lower ash content and higher strength, and can effectively solve the volume expansion problem involved in the charge and discharge process of silicon during the preparation process of silicon-carbon anode materials, meeting the requirements of silicon-carbon materials for activated carbon.

[0004] In the prior art, a chemical activation method is used to prepare fruit shell activated carbon. By etching carbon with an activation reagent to modify the carbon structure, the use of some acidic and alkaline activation reagents (such as KOH, H3PO4, etc.) is often involved. These activation reagents will corrode the equipment, increasing the equipment maintenance cost. In addition, chemical activation will produce difficult-to-treat pollutants during the activation process and has a high production cost.

[0005] Therefore, there is an urgent need for a fruit shell activated carbon and a preparation method and application thereof to solve the above technical problems. Summary of the Invention

[0006] In view of the high preparation cost of silicon-carbon materials and the recyclability of biomass waste, the present invention provides a preparation method of fruit shell activated carbon. Using environmentally friendly and clean steam activation to assist simple three-stage heat treatment to obtain fruit shell activated carbon for preparing silicon-carbon anode materials. The method of the present invention has the characteristics of wide raw material sources, low production cost, high repeatability, simple process, clean and environmentally friendly, etc.

[0007] The present invention is implemented according to the following technical scheme:

[0008] A preparation method of fruit shell activated carbon, comprising the following steps:

[0009] S1, washing and drying the fruit shell raw material to obtain a dry fruit shell raw material;

[0010] S2, carbonizing the dry fruit shell raw material to obtain fruit shell carbon;

[0011] S3. Crush the nut shell charcoal to obtain nut shell charcoal powder.

[0012] S4. Place the nut shell charcoal powder in a transfer activation furnace, heat it up and keep it warm under a nitrogen atmosphere, then heat it up and keep it warm under a steam atmosphere, and then cool it to obtain the crude nut shell activated carbon.

[0013] S5. Acid wash and dry the crude nut shell activated carbon to obtain the dried crude nut shell activated carbon.

[0014] S6. Crush and sieve the dried crude nut shell activated carbon, and then obtain the finished nut shell activated carbon through heating, heat preservation and cooling.

[0015] Preferably, in step S1, the nut shell raw material is at least one of passion fruit shells, coconut shells, pecan shells, and peanut shells.

[0016] Specifically, step S1 includes the following steps: Wash the nut shell raw materials separately with ethanol and deionized water, and dry them at 120 °C for 24 h.

[0017] An appropriate specific surface area and mesopore ratio are helpful for the activated carbon to be used in the preparation of silicon-carbon anode materials, and the subsequent electrochemical data can better verify this view. According to the specific surface area, mesopore ratio of the nut shell activated carbon obtained by the present invention and the relevant electrochemical data measured after being used in the silicon-carbon anode material of lithium-ion batteries and other parameters, it is found that the coconut shell activated carbon has an advantage, so the preferred nut shell raw material is coconut shell.

[0018] Preferably, in step S2, the carbonization process is as follows: Place the dried nut shell raw material in an atmosphere furnace filled with nitrogen, raise the temperature to the carbonization temperature at a heating rate of 20 °C / min, keep it warm for 2 h, and then naturally cool it to obtain nut shell charcoal; the carbonization temperature is 500-700 °C.

[0019] Furthermore, the carbonization temperature in step S2 is preferably 600 °C.

[0020] Specifically, in step S3, the nut shell charcoal is crushed by ball milling; the rotation speed of the ball mill is 30 rpm, the ball milling time is 5 h; the ball-to-material ratio is 5:1, and the grinding balls used are zirconia balls with a diameter of φ20 mm and zirconia balls with a diameter of φ5 mm, and the mass ratio of the zirconia balls with a diameter of φ20 mm to the zirconia balls with a diameter of φ5 mm is 2:1.

[0021] Analyzed by a particle size tester, for the nut shell charcoal powder obtained by screening through a 140-mesh sieve in step S3, the carbonization temperature has almost no effect on the particle size distribution of the nut shell charcoal powder, and they are all about 5-6 μm. Considering that the yield of nut shell charcoal is the largest at 600 °C and the concept of energy conservation and consumption reduction, the preferred carbonization temperature in step S2 is 600 °C.

[0022] Preferably, in step S4, it is heated to 550 - 650 °C under a nitrogen atmosphere and held for 2 - 3 h, and then heated to 700 - 900 °C under a steam atmosphere and held for 3 - 4 h.

[0023] Specifically, step S4 includes the following steps: placing the shell charcoal powder in a transfer activation furnace with a rotation speed of 15 - 25 r / min, first heating it to 550 - 650 °C at a heating rate of 10 - 20 °C / min under a nitrogen atmosphere and holding for 2 - 3 h; then heating it to 700 - 900 °C at a heating rate of 5 - 10 °C / min under a steam atmosphere and holding for 3 - 4 h; waiting for natural cooling to obtain the crude product of shell activated carbon; the flow rate of steam per hour is 90 - 150% of the mass of the shell charcoal powder.

[0024] The preferred steps of step S4 are: the rotation speed of the transfer activation furnace is 25 r / min, first heating it to 600 °C at a heating rate of 20 °C / min under a nitrogen atmosphere and holding for 2 h; then heating it to 900 °C at a heating rate of 5 °C / min under a steam atmosphere and holding for 4 h, waiting for natural cooling to obtain the crude product of shell activated carbon, and the flow rate of steam per hour is 120% of the mass of the shell charcoal powder; the unit of the flow rate of steam is g / h.

[0025] Preferably, in step S5, the pickling process is to soak the crude product of shell activated carbon in a hydrochloric acid solution, and then wash it with deionized water until the pH value is neutral, and obtain the dried crude product of shell activated carbon after centrifugation and drying.

[0026] Specifically, step S5 includes the following steps: soaking the crude product of shell activated carbon in a 0.3 mol / L hydrochloric acid solution for 12 h, then placing it in a glass reaction kettle and stirring, washing it with deionized water until the pH value is neutral to obtain the pickled crude product of shell activated carbon; placing the pickled crude product of shell activated carbon in a centrifuge at 800 rpm for 3 h, taking it out and drying it in an oven at 120 °C for 48 h to obtain the dried crude product of shell activated carbon.

[0027] Preferably, in step S6, the dried crude product of shell activated carbon is pulverized by air flow and then sieved, placed in an atmosphere furnace, heated to 1200 - 1600 °C under a nitrogen atmosphere, held for 3 - 5 h, and cooled to obtain the finished product of shell activated carbon.

[0028] Specifically, step S6 includes the following steps: placing the dried crude product of shell activated carbon in an air flow crusher to complete pulverization, then sieving it with a 400 - mesh sieve and placing it in an atmosphere furnace, heating it to 1200 - 1600 °C at a heating rate of 10 - 30 °C / min under a nitrogen atmosphere, holding for 3 - 5 h, and waiting for natural cooling to obtain the finished product of shell activated carbon.

[0029] The present invention finds that in step S6, the difference in the heating rate and the holding time has little effect on the electrochemical performance of the activated carbon used for the lithium-ion silicon-carbon anode material. Considering production capacity, the preferred heating rate is 20 °C / min, and the preferred holding time is 3 h. Calcination at a higher temperature helps to remove the oxygen functional groups in the activated carbon. The oxygen content of the activated carbon used for the silicon-carbon anode material is generally below 1.5%. This is mainly because the absence of oxygen functional groups has a certain improvement in the stability of the lithium-ion silicon-carbon anode material, and the subsequent obtained electrochemical data can further verify this view. Using an X-ray photoelectron spectrometer to test the fruit shell activated carbon, it is found that there is almost no difference in the oxygen content of the activated carbon obtained at 1400 °C and 1600 °C. Considering energy conservation and consumption reduction in industrial production, the preferred high-temperature calcination temperature is set at 1400 °C.

[0030] A fruit shell activated carbon prepared by the above preparation method.

[0031] The fruit shell activated carbon prepared according to the method of the present invention has a specific surface area as high as 1200 - 1800, the median particle size ranges from 5 to 10 μm, and the pore volume is 0.5 - 0.8 cm 3 / g, and the mesopore proportion reaches 15 - 35% of the total pores.

[0032] An application of a fruit shell activated carbon in a lithium battery anode material.

[0033] The present invention provides a method for preparing fruit shell activated carbon by using fruit shell as raw material and assisted by steam activation and three-stage heat treatment, and applying the fruit shell activated carbon to the preparation of silicon-carbon anode material. Taking part of the fruit shell as raw material, the fruit shell activated carbon is prepared by three-stage heat treatment of pre-carbonization (step S2 of the present invention), steam activation for pore formation (step S4 of the present invention), and high-temperature calcination for oxygen removal (step S6 of the present invention). The median particle size of the fruit shell activated carbon obtained by this method is 5 - 10 μm, the specific surface area is as high as 1200 - 1800 m 2 / g, the pore volume is 0.5 - 0.8 cm 3 / / g, and the mesopore ratio accounts for 15 - 31%. The method of the present invention is novel, simple, inexpensive and environmentally friendly, and is suitable for large-scale industrial production. When it is used for the silicon-carbon anode material, it shows good performance.

[0034] Physical activation is cleaner and more environmentally friendly than chemical activation, and the reagents used are mainly oxygen, water vapor and carbon dioxide. Since the reaction rate of oxygen is too fast, in order to maintain a relatively considerable carbon yield, oxygen activation often presents the characteristics of low reaction temperature and short activation time. The reason for the too fast reaction rate is that most oxygen molecules react as soon as they come into contact with the surface of the carbon material, which also leads to different reaction rates inside and outside the carbon material, and uneven reaction. Since water molecules are smaller in size than carbon dioxide molecules, this leads to a faster diffusion rate of water molecules in the pore structure of the carbon material, so at the same activation temperature, the rate of water vapor activation is faster than that of carbon dioxide. Therefore, the present invention uses water vapor for physical activation.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] The present invention realizes the recycling and reuse of part of the fruit shells in the biomass waste. Fruit shell activated carbon that can be used for silicon-carbon negative electrode materials is prepared by a three-stage heat treatment method assisted by water vapor activation. The fruit shell raw materials used have the advantages of wide sources and low prices, and compared with traditional biomass waste, the texture of the fruit shell is more delicate and has a certain tensile strength. Compared with chemical activation, the fruit shell activated carbon prepared by the fruit shell can better highlight the environmental protection and green production concept of the physical activation method. In addition, in view of the "high temperature rotation" characteristics of the transfer activation furnace, it is easier to achieve the purpose of fully diffusing the activation agent in the material than the traditional static activation furnace. This full diffusion can speed up the activation speed, which is beneficial to energy saving and consumption reduction and promote production. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 The scanning electron microscope images of coconut shell activated carbon obtained in Example 2 of the present invention at different magnifications;

[0038] Figure 2 This is the nitrogen adsorption-desorption curve of coconut shell activated carbon obtained in Example 2 of the present invention;

[0039] Figure 3 This is a graph showing the specific capacitance of the coconut shell activated carbon obtained in Example 2 of the present invention when used as a lithium battery silicon-carbon negative electrode material under 50 cycles. DETAILED DESCRIPTION

[0040] The present invention is further described below with reference to specific embodiments. The illustrative embodiments and descriptions of the present invention are used to explain the present invention but are not intended to limit the present invention.

[0041] Example 1

[0042] A method for preparing fruit shell activated carbon comprises the following steps:

[0043] Step 1: Wash the passion fruit shell raw materials with ethanol and deionized water respectively, and dry them at 120 °C for 24 h;

[0044] Step 2: Place the dried passion fruit shell raw materials in an atmosphere furnace filled with nitrogen, and heat them to 600 °C at a heating rate of 20 °C / min. After holding for 2 h, cool them naturally to obtain passion fruit shell charcoal;

[0045] Step 3: Grind the passion fruit shell charcoal into powder and sieve it through a 140-mesh sieve to obtain passion fruit shell charcoal powder; the passion fruit shell charcoal is crushed by ball milling; the rotation speed of the ball mill is 30 rpm, the ball milling time is 5 h; the ball-to-material ratio is 5:1, and the grinding balls used are zirconia balls with a diameter of φ20 mm and zirconia balls with a diameter of φ5 mm. The mass ratio of the added zirconia balls with a diameter of φ20 mm to zirconia balls with a diameter of φ5 mm is 2 to 1.

[0046] Step 4: Place the passion fruit shell charcoal powder in a transfer activation furnace with a rotation speed of 25 r / min. First, heat it to 600 °C at a heating rate of 20 °C / min in a nitrogen atmosphere, hold for 1 h, and then heat it to 900 °C at a heating rate of 5 °C / min in a steam atmosphere, hold for 3 h. The flow rate of steam per hour is 120% of the mass of the fruit shell activated carbon. After natural cooling, obtain the crude product of passion fruit shell activated carbon;

[0047] Step 5: Immerse the crude product of passion fruit shell activated carbon in a 0.3 mol / L hydrochloric acid solution for 12 h, then place it in a glass reaction kettle and stir, and wash it with deionized water until the pH value is neutral. Then place the pickled crude product of passion fruit shell activated carbon in a centrifuge at 800 rpm for 3 h, take it out and dry it in an oven at 120 °C for 48 h.

[0048] Step 6: Place the dried crude product of passion fruit shell charcoal in a jet mill to complete the crushing, then sieve it through a 400-mesh screen and place it in an atmosphere furnace. Heat it to 1400 °C at a heating rate of 20 °C / min in a nitrogen atmosphere, hold for 3 h, and after natural cooling, obtain the finished product of passion fruit shell activated carbon.

[0049] Example 2

[0050] A method for preparing fruit shell activated carbon, where the fruit shell raw material is coconut shell, and other steps are the same as in Example 1 to obtain coconut shell activated carbon.

[0051] As Figure 1 shown, Figure 1 is the scanning electron microscope image of the coconut shell activated carbon obtained in Example 2 of the present invention at different magnifications; as Figure 1 (a) and Figure 1 (b) show that at a lower magnification, the morphological structure of the coconut shell activated carbon is relatively uniform, while at a higher magnification, the Figure 1 (c) andFigure 1 The electron micrograph of (d) shows that the coconut shell activated carbon has a relatively rich pore structure, which strongly indicates its suitability for preparing silicon-carbon anode materials.

[0052] As Figure 2 shown, Figure 2 The nitrogen adsorption-desorption isotherm curve of the coconut shell activated carbon obtained in Example 2 of the present invention is shown. It can be seen that the curve belongs to the obvious Type-IV isotherm. In the low relative pressure region, the curve has a distinct steep rise, and in the intermediate relative pressure region, a clear hysteresis loop appears, indicating that the coconut shell activated carbon has a considerable number of micropores and mesopores.

[0053] Example 3

[0054] A method for preparing a fruit shell activated carbon, wherein the fruit shell raw material is pecan shell, and the other steps are the same as those in Example 1, obtaining pecan shell activated carbon.

[0055] Example 4

[0056] A method for preparing a fruit shell activated carbon, wherein the fruit shell raw material is peanut shell, and the other steps are the same as those in Example 1, obtaining peanut shell activated carbon.

[0057] Example 5

[0058] A method for preparing a fruit shell activated carbon, wherein the fruit shell raw material is coconut shell, and in Step 2, the temperature rise end point in the nitrogen-purged atmosphere furnace is changed to 500 °C (i.e., the carbonization temperature is 500 °C), and the other steps are the same as those in Example 2.

[0059] Example 6

[0060] A method for preparing a fruit shell activated carbon, wherein the fruit shell raw material is coconut shell, and in Step 2, the temperature rise end point in the nitrogen-purged atmosphere furnace is changed to 700 °C (i.e., the carbonization temperature is 700 °C), and the other steps are the same as those in Example 2.

[0061] Example 7

[0062] A method for preparing a fruit shell activated carbon, wherein the fruit shell raw material is coconut shell, and in Step 6, the high-temperature roasting temperature is 1200 °C, and the other steps are the same as those in Example 2.

[0063] Example 8

[0064] A method for preparing a fruit shell activated carbon, wherein the fruit shell raw material is coconut shell, and in Step 6, the high-temperature roasting temperature is 1600 °C, and the other steps are the same as those in Example 2.

[0065] Comparative Example 1

[0066] Step 1: Wash the coconut shell raw material with ethanol and deionized water respectively, and dry it at 120 °C for 24 h;

[0067] Step 2: Place the dried coconut shell raw materials in an atmosphere furnace filled with nitrogen, heat it to 600 °C at a heating rate of 20 °C / min, keep it at this temperature for 2 h, and then cool it naturally to obtain coconut shell charcoal;

[0068] Step 3: Grind the coconut shell charcoal into powder and sieve it through a 140-mesh sieve to obtain coconut shell charcoal powder;

[0069] The activated carbon from fruit shells prepared using different fruit shells in Examples 1-4 and the coconut shell charcoal prepared in Comparative Example 1 were tested. The specific surface area, mesopore ratio, and data obtained from related electrochemical tests are shown in Table 1. Specifically, the specific surface area was tested using a specific surface area tester. The activated carbon from fruit shells prepared using different fruit shells in Examples 1-4 and the coconut shell charcoal prepared in Comparative Example 1 were used to prepare silicon-carbon anode materials and then assembled into button batteries for lithium batteries for electrochemical tests. The initial discharge specific capacity was tested, and the specific capacitance retention rate after 50 charge-discharge cycles was tested at a current density of 0.1 C and a voltage window of 0.005-2 V.

[0070] Table 1

[0071]

[0072] From the data in Table 1, it can be seen that all the characterization data of the coconut shell activated carbon are significantly better than those of the coconut shell charcoal without steam activation, indicating that steam activation plays an indispensable role in changing the structure of the fruit shell charcoal; from the data in Examples 1-4, it can be seen that the specific surface area of the coconut shell activated carbon is higher than that of the passion fruit shell activated carbon and the peanut shell activated carbon. Although its specific surface area is lower than that of the pecan shell activated carbon relative to the coconut shell activated carbon, its mesopore ratio is much higher than that of the other three samples. The data from the electrochemical tests of the button batteries assembled after using it to prepare silicon-carbon anode materials show that the initial charge-discharge specific capacity and the capacity retention rate after 50 cycles of the coconut shell activated carbon are better than those of the other three samples. Therefore, the present invention preferably uses coconut shells as the raw material for fruit shell activated carbon.

[0073] As Figure 3 shown, it is the specific capacitance diagram of the coconut shell activated carbon obtained in Example 2 of the present invention for use in a lithium battery silicon-carbon anode material under 50 cycles.

[0074] Considering the influence of particle size and yield on the subsequent production capacity and coconut shell activated carbon, the particle size and yield parameters of the corresponding coconut shell charcoal obtained in Steps 2 and 3 of Examples 1 and 5-6 and the related parameters of the electrochemical performance of the coconut shell activated carbon used for silicon-carbon anode materials were tested. The results are shown in Table 2.

[0075] Table 2

[0076]

[0077] As can be seen from the data obtained in Table 2, for the coconut shell charcoal obtained after Steps 2 and 3, the pre-carbonization temperature has little effect on the particle size of the coconut shell charcoal; when the temperature rises from 500 °C to 600 °C, the yield of the coconut shell charcoal shows an increasing trend, while when the temperature rises to 700 °C, the yield is almost unchanged compared with that at 600 °C. The electrochemical performance parameters of the coconut shell activated carbon obtained in Example 1 and Examples 5-6 show that the initial charge specific capacity of the sample obtained in Example 1 is between those of Examples 5 and 6, but its capacity retention rate after 50 cycles is significantly better than that of Examples 5-6. Based on the above, the preferred carbonization temperature of the coconut shell in the present invention is set at 600 °C.

[0078] Considering that the change of oxygen-containing functional groups in the activated carbon by high-temperature roasting may affect the electrochemical performance of the silicon-carbon anode material, Examples 7-8 and Example 2 were designed for comparison. The relative element contents of C and O obtained by X-ray photoelectron spectroscopy for the samples obtained in Example 2 and Examples 7-8 and the electrochemical performance test data for the silicon-carbon anode material are shown in Table 3.

[0079] Table 3

[0080]

[0081] As can be seen from the data obtained in Table 3, when the high-temperature roasting temperature is 1200 °C, the oxygen content of Example 7 is 5.6%. When the temperature is further raised to 1400 °C, the relative element content of oxygen in Example 7 decreases significantly. When the temperature rises to 1600 °C, the oxygen content in Example 8 is almost unchanged compared with that in Example 7, indicating that the oxygen content of the sample has decreased to the critical value at 1400 °C. Then, the three samples were used to prepare the silicon-carbon anode material and assembled into a lithium battery button cell for electrochemical testing. The results show that the initial discharge specific capacity of Example 2 is almost the same as that of the other two samples, while the capacity retention rate of Example 2 after 50 cycles is significantly better than that of the other two samples.

[0082] Considering the consumption of production capacity and the stability of the silicon-carbon anode material, the high-temperature roasting temperature is selected as 1400 °C.

[0083] The technical solution of the present invention is not limited to the limitations of the above specific embodiments. Any technical deformation made according to the technical solution of the present invention falls within the protection scope of the present invention.

Claims

1. A preparation method of shell activated carbon, characterized in that: It includes the following steps: S1. Wash the shell raw material and then dry it to obtain a dried shell raw material; S2. Carbonize the dried shell raw material to obtain shell charcoal; S3. Crush the shell charcoal to obtain shell charcoal powder; S4. Place the shell charcoal powder in a transfer activation furnace, heat it up and keep it warm under a nitrogen atmosphere, then heat it up and keep it warm under a steam atmosphere, and then cool it to obtain a crude shell activated carbon; S5. Pickle the crude shell activated carbon and then dry it to obtain the pickled and dried crude shell activated carbon; S6. Crush and sieve the pickled and dried crude shell activated carbon, and then heat, keep it warm and cool it to obtain the finished shell activated carbon.

2. The preparation method of a fruit shell activated carbon according to claim 1, characterized in that: In the step S1, the shell raw material is at least one of passion fruit shells, coconut shells, pecan shells, and peanut shells.

3. The preparation method of a fruit shell activated carbon according to claim 1, wherein: In the step S2, the carbonization process is as follows: place the dried shell raw material in an atmosphere furnace filled with nitrogen, heat it up to the carbonization temperature at a heating rate of 20°C / min, keep it warm for 2 h and then cool it naturally to obtain shell charcoal; the carbonization temperature is 500-700°C.

4. The preparation method of a fruit shell activated carbon according to claim 1, characterized in that: In the step S4, heat it up to 550-650°C and keep it warm for 2-3 h under a nitrogen atmosphere, then heat it up to 700-900°C and keep it warm for 3-4 h under a steam atmosphere.

5. The preparation method of a fruit shell activated carbon according to claim 1, characterized in that: In the step S5, the pickling process is as follows: soak the crude shell activated carbon in a hydrochloric acid solution, then wash it with deionized water until the pH value is neutral, and obtain the pickled and dried crude shell activated carbon through centrifugation and drying.

6. The preparation method of a fruit shell activated carbon according to claim 1, characterized in that: In the step S6, crush the pickled and dried crude shell activated carbon by air flow and sieve it, place it in an atmosphere furnace, heat it up to 1200-1600°C under a nitrogen atmosphere, keep it warm for 3-5 h, and cool it to obtain the finished shell activated carbon.

7. A fruit shell activated carbon, characterized in that: Prepared by the preparation method according to any one of claims 1-6.

8. Application of the shell activated carbon prepared by the preparation method according to any one of claims 1-6 in the anode material of a lithium battery.

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