A bamboo charcoal-based active material, a bamboo charcoal-based silicon-carbon composite active material, and its preparation and application

Abstract

This invention belongs to the technical field of biomass waste recycling for electrode materials. It specifically discloses a method for preparing bamboo charcoal-based active materials. Bamboo powder is pretreated, and then a raw material solution containing the pretreated bamboo powder and an alkaline substance A is heated to a subcritical state. The solution is then liquefied under heat and pressure, followed by solid-liquid separation to obtain a treated liquid. The alkaline substance A is a compound of a Group I metal element. The pretreatment process includes an acid treatment followed by an oxidation treatment. The treated liquid is then combined with an additive B, and the solvent is removed to obtain a precursor. The precursor is then heat-treated, washed, and dried to obtain the bamboo charcoal-based active material. The additive B is a water-insoluble compound of a Group II metal element. The heat treatment temperature is 600-950°C. The invention also includes materials produced by the preparation method and their use in capacitors. The process described in the present invention can improve the electrochemical properties of the prepared material.

Description

Technical Field

[0001] The present invention belongs to the field of energy storage devices, and in particular relates to the technical field of electrode materials for energy storage devices. Background Art

[0002] In recent years, with the rapid growth of population and rapid development of social economy, the demand for energy in countries around the world has also increased. The over-exploitation of traditional energy (coal, oil, natural gas, etc.) and the inefficient use of energy have become severe challenges facing human society today. Therefore, the development and utilization of new energy has become an important issue facing the world today. How to efficiently develop and utilize clean, sustainable, green energy is the most urgent task at present. Lithium-ion capacitors are electrochemical hybrid capacitors. In terms of energy storage mechanism, they are hybrid capacitors. They are a new type of energy storage device between double-layer capacitors and lithium-ion batteries. They have higher energy density than double-layer capacitors and higher power density and cycle life than lithium-ion batteries. They are one of the best choices for power sources for electric vehicles. By definition, a lithium-ion capacitor refers to an electrochemical hybrid capacitor with activated carbon or other carbonaceous materials as the positive electrode, lithium-intercalated compound materials as the negative electrode, and lithium-ion battery electrolyte. However, the pore structure of commonly used commercial activated carbon materials is not well developed, and they exhibit a low specific capacity of about 35 mAh g -1 , the energy density of the device is limited. Therefore, the development of porous carbon materials with high specific capacity is crucial. Commonly used carbon materials include graphene, carbon nanotubes, polymer carbon, and biochar. However, graphene, carbon nanotubes, and polymer carbon are difficult to mass produce due to high preparation costs and complex processes.

[0003] Biomass-derived carbons are currently the most promising precursors for producing activated carbon as electrode materials, offering numerous advantages, including low cost, tunable chemical and physical properties, eco-friendly properties, abundant resources, high economic value, and suitability for industrial mass production. Natural bamboo powder, as a biomass material, is widely distributed, rapidly growing, and renewable, making it particularly suitable as an activated carbon precursor. Currently, commercially available lithium-ion capacitor anode materials are primarily commercial graphite, which exhibits a low and stable discharge plateau. However, its poor rate performance limits the device's power density. Silicon anodes offer the highest theoretical specific capacity, but suffer from severe volume expansion, pulverization, and poor cycling stability. These anodes require composites with materials such as graphene, carbon nanotubes, and pyrolytic carbon to improve their electronic conductivity and cycling stability. The development of novel anode materials with high rate performance is crucial for increasing the power density of lithium-ion capacitors. Therefore, developing a novel process for preparing lamellar hierarchical porous carbon electrode materials from natural bamboo powder could enable the low-cost fabrication of high-capacitance lithium-ion capacitors. Summary of the Invention

[0004] In response to the problem that the performance of existing bamboo charcoal-based electrode materials is not ideal, the first purpose of the present invention is to provide a method for preparing bamboo charcoal-based active materials, aiming to prepare positive electrode active materials with high electrochemical performance based on bamboo raw materials.

[0005] The second purpose of the present invention is to provide a bamboo charcoal-based active material prepared by the preparation method and its application in energy storage devices.

[0006] The third object of the present invention is to provide a method for preparing a bamboo charcoal-based silicon-carbon composite active material based on the bamboo charcoal-based active material prepared by the method, aiming to further prepare a high-performance negative electrode active material.

[0007] The fourth object of the present invention is to provide a bamboo charcoal-based silicon-carbon composite active material prepared by the preparation method and its application in energy storage devices.

[0008] A fifth object of the present invention is to provide a lithium ion capacitor comprising the bamboo charcoal-based active material and / or the bamboo charcoal-based silicon-carbon composite active material.

[0009] Bamboo raw materials have complex components, hard texture, and uneven texture, making it difficult to prepare active materials suitable for lithium-ion capacitors. To address this problem, the present invention provides the following solutions:

[0010] A method for preparing a bamboo charcoal-based active material, comprising the following steps:

[0011] Step (1):

[0012] The bamboo powder is pretreated, and then a raw material solution containing the pretreated bamboo powder and the alkaline substance A is heated to a subcritical state, kept at a temperature and pressure for liquefaction, and then solid-liquid separation is performed to obtain a treated liquid;

[0013] The alkaline substance A is a compound of a first main group metal element; the pretreatment process includes acid treatment and subsequent oxidation treatment;

[0014] Step (2):

[0015] The treatment liquid and the additive B are combined and the solvent is removed to obtain a precursor, which is then heat-treated; then washed and dried to obtain a bamboo charcoal-based active material;

[0016] The additive B is a water-insoluble compound of a second main group metal element;

[0017] The temperature of the heat treatment is 600-950°C.

[0018] In response to the problem that it is difficult to prepare active materials suitable for high-performance lithium-ion capacitors from bamboo raw materials, the innovative research of the present invention shows that pre-treating the bamboo raw materials in advance, then liquefying the pretreated bamboo raw materials under a subcritical fluid containing an alkaline component, and then supplementing it with an auxiliary heat treatment of additive B can achieve synergy and produce high-performance bamboo charcoal-based active materials with special physical, chemical and structural characteristics that can adapt to the applicable requirements of lithium-ion capacitors.

[0019] In the present invention, the raw material of bamboo powder can be any kind of bamboo, for example, it can be at least one of moso bamboo, laminaria, arrow bamboo, spotted bamboo, water bamboo and the like.

[0020] In the present invention, the acid solution used in the acid treatment process is an aqueous solution of an inorganic acid, and can further be an aqueous solution of one or more of sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, and hydrofluoric acid. The concentration can be 1 to 4 mol / L, and can further be 2 to 3 mol / L.

[0021] Preferably, the acid pretreatment time is 2 to 20 hours; more preferably, it is 6 to 18 hours.

[0022] In the present invention, the acid pretreatment process can be carried out at room temperature, for example, the temperature can be 10-40°C.

[0023] In the present invention, in the pretreatment stage, the oxidation step is, for example, to mix the acid-treated bamboo powder with a hydrogen peroxide solution for oxidation treatment, the concentration of which may be 2-6 mol / L, or further 4-5 mol / L.

[0024] Preferably, the oxidation pretreatment time is 1 to 6 hours, more preferably 3 to 5 hours.

[0025] In the present invention, the pretreatment step further comprises a sulfonation step: mixing the oxidized bamboo powder with a sulfite solution such as sodium sulfite for sulfonation treatment, wherein the concentration of the sulfite solution may be 1-4 mol / L; further, 1-2 mol / L.

[0026] Preferably, the sulfonation pretreatment time is 1 to 5 hours, more preferably 2 to 4 hours.

[0027] In the present invention, the acid-oxidation-sulfonation pretreatment process is used to further adjust the physicochemical characteristics of the bamboo raw material, which is conducive to coordinating the occurrence state of organic matter in the treatment liquid with the subsequent subcritical state, thereby further facilitating the acquisition of active materials that meet the performance requirements of lithium-ion capacitors.

[0028] In the present invention, the alkaline substance A can be any substance that can exhibit alkalinity, for example, it can be at least one of sodium hydroxide, potassium hydroxide, sodium carbonate, and potassium carbonate; preferably, it is a mixture of sodium hydroxide and sodium carbonate; more preferably, it is a mixture of sodium hydroxide and sodium carbonate in a molar ratio of 1 to 3:1. In the raw material solution, there is no special requirement for the solute concentration of the alkaline substance, for example, it can be 1 to 6 mol / L, and the liquid-solid ratio can be adjusted as needed, for example, it can be 4 to 8 mL / g. The research of the present invention unexpectedly found that the use of the preferred alkaline substance A can further unexpectedly achieve synergy, and can further synergize with other operations of the process to improve the performance of the obtained material, especially to improve the performance of lithium ion capacitors.

[0029] In the present invention, the raw material solution can be loaded into a subcritical processing device in air or a protective atmosphere, preferably under a protective atmosphere. The protective gas can be, for example, at least one of nitrogen and argon. The present inventors unexpectedly discovered that loading the raw material solution into the device under a protective atmosphere creates a three-phase gas-solid-liquid system within the subcritical processing device, comprising the raw material solution and the protective atmosphere. This can further complement subcritical processing, better addressing the challenges of bamboo powder preparation and unexpectedly further improving the performance of the resulting material in lithium-ion capacitors.

[0030] Preferably, the filling volume of the raw material solution in the subcritical processing equipment is 60-80%;

[0031] Preferably, the temperature during the subcritical treatment phase is 140-280°C, the pressure is 10-20 MPa, and the shielding gas is at least one of nitrogen and argon. Further preferably, the temperature during the subcritical treatment phase is 180-260°C, the pressure is 14-19 MPa, and the shielding gas is argon. The present invention has discovered that under the preferred subcritical state, the organic matter in the bamboo powder treatment solution can be regulated, which unexpectedly facilitates the preparation of active materials suitable for lithium-ion capacitors.

[0032] In the present invention, the time of heat preservation and pressure preservation in the subcritical state is 0.5 to 8 hours, and more preferably 2 to 6 hours.

[0033] In the present invention, after subcritical treatment, the pressure is released and the temperature is lowered, and solid-liquid separation can be performed as needed to obtain the treated liquid. The treated liquid is innovatively combined with additive B for heat treatment, thereby synergistically improving the performance of the resulting bamboo charcoal-based active material, particularly the performance of lithium-ion capacitors.

[0034] In the present invention, the additive B is at least one water-insoluble component selected from calcium, magnesium, strontium and barium, preferably at least one selected from calcium oxide, calcium carbonate, magnesium oxide, magnesium carbonate and magnesium hydroxide.

[0035] In the present invention, the additive B may be a material of any desired shape, for example, a sheet material.

[0036] In the present invention, the particle size of Additive B is less than or equal to 500 nm. Further preferably, Additive B comprises a small-particle Additive B1 with a particle size of 100 to 300 nm and a large-particle Additive B2 with a particle size of 350 to 500 nm. The present invention also unexpectedly discovered that, under the described process, further adjusting the particle size gradation of Additive B can further synergistically improve the performance of the resulting active material in lithium-ion capacitors.

[0037] Preferably, in the additive B, the weight ratio of the small-particle additive B1 to the large-particle additive B2 may be 1:0.1-10.

[0038] Preferably, the weight ratio of bamboo powder to additive B required for the treatment liquid is 1:0.5 to 2. Taking into account the treatment cost and effect, it can be further 1:1 to 1.5.

[0039] In the present invention, after the treatment liquid and the additive B are mixed, desolvation can be performed based on existing methods to obtain a precursor. For example, the desolvation method is evaporation under normal pressure or reduced pressure;

[0040] Preferably, the heat treatment atmosphere is a protective gas or a mixed atmosphere of a reducing gas and a protective gas. The protective gas may be, for example, at least one of nitrogen and argon. The reducing gas may be at least one of hydrogen, CO, and CH4, with hydrogen being more preferred. Research in the present invention has found that the combination of the subcritical atmosphere and the additive B, combined with heat treatment in a reducing gas atmosphere, can further synergistically improve the behavior and physicochemical structural characteristics of the resulting bamboo-based material, making it more suitable for lithium-ion capacitor applications and exhibiting superior performance.

[0041] In the present invention, the content of reducing gas in the reducing gas-protective gas mixed atmosphere can be above 2% by volume, and further can be 3-10% by volume.

[0042] Preferably, the heat treatment temperature is 600-950°C, more preferably 650-750°C, and further preferably 700-750°C;

[0043] Preferably, the heat treatment time is 0.5 to 3 hours, more preferably 1 to 2 hours;

[0044] In the present invention, the heat treatment is followed by cooling, followed by washing and drying. The washing process may include pickling and water washing processes. The acid solution used in the pickling stage is, for example, an inorganic strong acid solution, such as hydrochloric acid, nitric acid, sulfuric acid and the like. In addition, there is no special requirement for the concentration of the acid solution, for example, it can be 0.1 to 3 mol / L. The pickling method is, for example, beating or rinsing. In the present invention, the water washing method may be a beating-filtration method in water, or a rinsing method. In the present invention, water washing is performed until the filtrate is close to neutral, for example, the pH is 6.5 to 7.1.

[0045] In the present invention, the drying method can be conventional drying, vacuum drying, etc.

[0046] The invention also provides a bamboo charcoal-based active material prepared by the preparation method.

[0047] The present invention has found that, thanks to the combined control of the preparation process, the product can be endowed with special physical, chemical and structural characteristics. In addition, the material prepared by the preparation method can exhibit excellent performance in lithium ion capacitors.

[0048] As the same inventive concept, the present invention also provides a method for preparing a bamboo charcoal-based silicon-carbon composite active material. The bamboo charcoal-based active material is prepared by the preparation method, and then the bamboo charcoal-based active material is compounded with a silicon source to form a composite precursor, which is then subjected to reduction roasting treatment, and then washed and dried to obtain the bamboo charcoal-based silicon-carbon composite active material.

[0049] The present invention has found that, thanks to the preparation method of the bamboo charcoal-based active material, further compounding it with silicon material can achieve synergistic improvement, so that the prepared composite material is adapted to the use requirements of lithium ion capacitors and can also exhibit excellent performance.

[0050] In the present invention, the composite precursor can be obtained by hydrolysis and condensation, and the steps are, for example, to hydrolyze and condense the bamboo charcoal-based active material and the organic silicate under alkaline conditions.

[0051] In the present invention, the organosilicate may be a silicate formed from silicic acid and a C1-C6 alcohol. The alkaline conditions are established using an alkaline component such as an ammonia source, sodium hydroxide, or potassium hydroxide. The ammonia source may be, for example, one or more of aqueous ammonia, urea, thiourea, ethylenediamine, melamine, methylurea, ethylurea, hydroxyurea, and semicarbazide, preferably aqueous ammonia.

[0052] The amount of silicon source can be adjusted according to the needs of silicon-carbon composite. For example, the weight ratio of silicon source to bamboo charcoal-based active material can be 1-100:1, further 5-50:1, and further 10-40:1.

[0053] In the present invention, the reduction roasting treatment may be a metal heat treatment, and the steps thereof include, for example, mixing and heating the composite precursor, the reducing metal, and the chloride salt of the metal, and performing the reduction roasting treatment.

[0054] In the present invention, the reducing agent is a reducing metal element or magnesium silicide;

[0055] In the present invention, the amount of the reducing agent is not less than the theoretical reaction amount. For example, the weight ratio of the reducing agent to the precursor is 0.5 to 5:1, and can further be 0.5 to 2:1.

[0056] The metal chloride is, for example, at least one of sodium chloride, potassium chloride, ammonium chloride, and lithium chloride.

[0057] In the present invention, there is no particular requirement for the amount of the metal chloride. Considering the cost, the amount of the metal chloride can be 5 to 50:1, and further can be 5 to 15:1, based on the weight of the precursor.

[0058] Preferably, the temperature of the reduction roasting stage is 500-800°C, preferably 650-750°C;

[0059] Preferably, the reduction roasting time is 2 to 12 hours, preferably 4 to 8 hours;

[0060] Preferably, the washing process includes pickling and water washing, which can be equivalent to the pickling and water washing steps of the bamboo charcoal-based active material.

[0061] The invention also provides a bamboo charcoal-based silicon-carbon composite active material prepared by the preparation method.

[0062] The present invention has shown that, thanks to the control of the preparation method, the prepared composite material can be endowed with special physical, chemical and structural characteristics, and can exhibit excellent performance when applied to lithium ion capacitors.

[0063] The present invention also provides an application of a bamboo charcoal-based active material or a bamboo charcoal-based silicon-carbon composite active material, which is used as an electrode active material to prepare an energy storage device;

[0064] Preferably, the bamboo charcoal-based active material is used as a positive electrode active material, and / or the bamboo charcoal-based silicon-carbon composite active material is used as a negative electrode active material to prepare an energy storage device.

[0065] Further preferably, the bamboo charcoal-based active material is used as the positive electrode active material, and the bamboo charcoal-based silicon-carbon composite active material is used as the negative electrode active material to prepare an energy storage device. Studies have shown that the use of the bamboo charcoal-based positive electrode active material in combination with the bamboo charcoal-based silicon-carbon negative electrode material can further achieve synergistic adaptation, further improving the performance of the energy storage device.

[0066] Preferably, the energy storage device is a lithium ion capacitor.

[0067] In the present invention, the active material of the present invention can be prepared to obtain the required lithium ion capacitor based on existing equipment, means and principles.

[0068] The present invention also provides a lithium ion capacitor, whose positive electrode active material is the bamboo charcoal-based active material of the present invention, and / or whose negative electrode active material is the bamboo charcoal-based silicon-carbon composite active material of the present invention.

[0069] Preferably, the bamboo charcoal-based active material of the present invention is innovatively used as the positive electrode active material, and the bamboo charcoal-based silicon-carbon composite active material is used as the negative electrode active material, so as to obtain a better synergistic effect of positive and negative electrode matching, and unexpectedly further synergistically improve the electrochemical performance of the obtained lithium ion capacitor.

[0070] The beneficial effects of the technical solution of the present invention are:

[0071] (1) The present invention innovatively liquefies the bamboo raw material under a subcritical fluid containing an alkaline component, and then uses an auxiliary heat treatment with additive B to achieve synergy and obtain a bamboo charcoal-based active material with special layers that can significantly improve the performance of lithium ion capacitors.

[0072] (2) In the present invention, the preferred pretreatment of bamboo powder, and / or the preferred subcritical treatment atmosphere, and / or the preferred control of additive B, and / or the preferred combined control of the heat treatment atmosphere can further synergistically improve the physicochemical and microstructural characteristics of the prepared material, further make it compatible with the application requirements of lithium ion capacitors, and further improve the electrochemical performance of lithium ion capacitors.

[0073] (3) By using the positive electrode active material and the negative electrode active material described in the present invention to match and form a lithium ion capacitor, a better positive and negative electrode matching effect can be obtained, which can further improve the performance of the lithium ion capacitor.

[0074] The raw materials of the present invention are widely available, low in cost, and easy to achieve mass production. Positive and negative electrode materials with excellent performance can be obtained through simple processes, while high-value utilization of bamboo powder is achieved, which has great development prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0075] Attachment Figure 1 This is the SEM image of the lamellar magnesium hydroxide in Example 1.

[0076] Attachment Figure 2 This is the SEM image of the lamellar hierarchical porous carbon material prepared from natural bamboo powder in Example 1.

[0077] Attachment Figure 3 This is the SEM image of the nano-silicon oxide / lamellar hierarchical porous carbon composite material in Example 1.

[0078] Attachment Figure 4 This is the SEM image of the nano-silicon / lamellar hierarchical porous carbon composite material in Example 1. DETAILED DESCRIPTION

[0079] The specific steps of the present invention are described below by way of examples. It should be understood that these examples are merely provided to further illustrate the present invention, but the present invention is not limited to the following examples.

[0080] The present invention provides a specific method for preparing positive electrode active materials and negative electrode active materials using natural bamboo powder, comprising the following steps:

[0081] Step (1): The natural bamboo powder is subjected to acid washing, oxidation and sulfonation pretreatment, and then the natural bamboo powder and a solution of alkaline substance A are mixed and added to a subcritical reactor, and treated under subcritical conditions of a reaction temperature of 140 to 280° C., a reaction pressure of 10 to 20 MPa, and a protective gas of at least one of nitrogen and argon, followed by solid-liquid separation to obtain bamboo liquid; the liquid-to-solid ratio is 4 to 8 mL / g based on the dry weight of the natural bamboo powder;

[0082] Step (2): mixing the bamboo sap and the additive B and heat-treating them in a protective atmosphere containing a reducing gas; the heat-treating temperature is 600 to 950° C., the heat-treating time is 0.5 to 3 hours, and the heating rate during the heat-treating process is 2 to 10° C. / min;

[0083] Step (3): acid-washing, water-washing, and drying the heat-treated product of step (2) to obtain the lamellar graded porous carbon positive electrode material (positive electrode active material);

[0084] Step (4): dispersing the positive electrode active material, silicon source, and ammonia source in a solvent, stirring and mixing, and then performing a hydrolysis and polycondensation reaction under set conditions. After the reaction is completed, filtering, washing, and drying to obtain a composite precursor;

[0085] Step (5): After uniformly mixing the composite precursor, reducing agent and metal chloride prepared in step (4), heat-treating the mixture under an inert atmosphere, cooling the mixture to room temperature, and then acid-washing, water-washing and drying the mixture to obtain a silicon-carbon composite negative electrode material (negative electrode active material);

[0086] Step (6): Assemble the positive electrode material obtained in step (3) and the negative electrode material pre-embedded with lithium in step (5) to form a lithium ion capacitor.

[0087] In the present invention, the liquid silicon source is one or more of methyl orthosilicate, ethyl orthosilicate, sodium silicate, and potassium silicate, preferably ethyl orthosilicate.

[0088] In the present invention, the ammonia source is one or more of ammonia water, urea, thiourea, ethylenediamine, melamine, methylurea, ethylurea, hydroxyurea, and semicarbazide, preferably ammonia water.

[0089] In the present invention, the solvent is a mixed solvent of water and alcohol, and the volume ratio of water to alcohol is 1:1-10.

[0090] In the present invention, the mass ratio of the liquid silicon source, the porous carbon in step (3), the ammonia source and the mixed solvent is 1: (0.01-0.1): (0.2-5): (10-25).

[0091] In the present invention, the reaction temperature is 10-50° C.; the reaction time is 1-24 h.

[0092] Example 1

[0093] Step (1): Preprocessing:

[0094] 50g bamboo powder was poured into a mixed solution of 2mol / L hydrochloric acid and 2mol / L hydrofluoric acid of 500mL, stirred for 12h, and then washed to neutrality and dried to obtain acid-treated bamboo powder. Acid-treated bamboo powder was poured into a 3mol / L hydrogen peroxide solution of 500mL, stirred for 3h, and then washed to neutrality and dried to obtain oxidative pretreated bamboo powder. Oxidatively treated bamboo powder was poured into a 1mol / L sodium sulfite solution of 500mL, stirred for 2h, and then washed to neutrality and dried to obtain sulfonated pretreated bamboo powder.

[0095] Take 10g of nano-magnesium oxide and put it into 300mL of water, transfer it into a polytetrafluoroethylene hydrothermal tank, and keep it at 120-160℃ for 2h to obtain flaky magnesium hydroxide (SEM shows Figure 1 ).

[0096] Step (2): Subcritical liquefaction:

[0097] 10g of pretreated bamboo powder was placed in a 3mol / L mixed solution of potassium carbonate and sodium carbonate (alkaline substance A) at a 1:1 molar ratio and a liquid-to-solid ratio of 6mL / g. After stirring for 1 hour, the mixture was filled into a subcritical reactor under air atmosphere to a volume of 60%. The reactor was then heated to a subcritical state of 190°C (denoted as T0) and 14 MPa, where it was maintained at this pressure for 6 hours. After cooling, the solid-liquid separation was performed to obtain bamboo liquid.

[0098] Step (3): Preparation of positive electrode active material:

[0099] After adding 15 g of large-particle flaky magnesium hydroxide (additive B) with a particle size range of 400-450 nm to the bamboo sap of step (2), the mixture was evaporated to dryness under reduced pressure in a vacuum drying oven at 100° C. and then transferred to a tube furnace with a methane-argon mixed atmosphere (methane 5%), heated to 650° C. and kept warm (marked as T1) for 2 h at a heating rate of 5° C. / min. The mixture was cooled to room temperature and then taken out. The heat-treated product was acid-washed with 2 mol / L hydrochloric acid, washed with water until neutral, and dried at 80° C. to obtain a lamellar hierarchical porous carbon material (positive electrode active material, SEM shows Figure 2 ). Pore structure characteristics of porous carbon materials: specific surface area is 1500m 2 / g, pore volume 1.8cm 3 / g, the pore size distribution is mainly mesopores, with the mesopore volume accounting for 74% and the micropore volume accounting for 20%, and it has a hierarchical porous structure.

[0100] Step (4): Preparation of negative electrode active material:

[0101] Disperse 10 mL of tetraethyl orthosilicate in 78 mL of ethanol to obtain mixed solution A. Add 0.5 g of lamellar hierarchical porous carbon (prepared in step (3)) and 1.6 g of hexadecyltrimethylammonium bromide thereto and stir thoroughly. Disperse 10 mL of ammonia water in a solvent consisting of 182 mL of ethanol and water (volume ratio is 1:1.5) to obtain mixed solution B. Pour mixed solution B quickly into mixed solution A and stir at room temperature at 600 r / min for 6 hours to obtain a colloidal precipitate, filter it, wash it with water to make it neutral, and dry it at 60°C to obtain a composite precursor (SEM see Figure 3 ). Take 2.5g of composite precursor powder, mix it with 25g of sodium chloride and 2.3g of metal magnesium powder (reducing agent), and heat it to 750℃ (calcination temperature, marked as T2) at 5℃ / min under argon atmosphere for 6h. After cooling to room temperature, take it out and pickle it in 2mol / L hydrochloric acid for 6h, filter it, wash it with water until it is neutral, and vacuum dry it at 60℃ to obtain a nano-silicon / sheet-level hierarchical porous carbon composite material (negative electrode active material, SEM see Figure 4 ).

[0102] The above-mentioned positive electrode active material (the material prepared in step 3), Super-P and PVDF were mixed in a mass ratio of 8:1:1, and an appropriate amount of NMP was added and stirred evenly to prepare a positive electrode sheet.

[0103] The above-mentioned negative electrode active material (prepared in step 4), Super-P and sodium alginate were mixed in a mass ratio of 6:2:2, and an appropriate amount of ethanol and water mixture was added and stirred evenly to prepare a negative electrode sheet.

[0104] A CR2025 button-type lithium-ion capacitor was assembled in an argon-filled glove box using positive and negative electrode sheets, an electrolyte consisting of 1 mol / L LiPF6 in EC / DMC / DEC (volume ratio 1:1:1), and a polypropylene porous membrane, Celgard 2400, as a separator. The negative electrode was pre-lithium-coated by evenly applying an appropriate amount of stable metallic lithium powder to the negative electrode. Electrochemical performance tests were conducted at room temperature in the voltage range of 2.0-4.0V. The maximum energy density and power density of the lithium-ion capacitor (calculated using the same method in all subsequent cases, unless otherwise stated), calculated based on the total mass of the positive and negative active materials, were 105Wh / kg and 14.1kW / kg, respectively.

[0105] Example 2

[0106] Compared with Example 1, the only difference is that the pretreatment step of step (1) is changed, and the experimental groups are:

[0107] Group A: 50g of bamboo powder was poured into 500mL of a mixed solution of 2mol / L hydrochloric acid and 2mol / L hydrofluoric acid, stirred for 10 hours, washed with water until neutral, and dried to obtain acid-treated bamboo powder. The acid-treated bamboo powder was poured into 500mL of a 6mol / L hydrogen peroxide solution, stirred for 4 hours, washed with water until neutral, and dried to obtain oxidatively pretreated bamboo powder. The oxidatively pretreated bamboo powder was poured into 500mL of a 1mol / L sodium sulfite solution, stirred for 2 hours, washed with water until neutral, and dried to obtain sulfonated bamboo powder.

[0108] Group B: 50g of bamboo powder was poured into 500mL of a mixed solution of 2mol / L hydrochloric acid and 2mol / L hydrofluoric acid, stirred for 16 hours, washed with water until neutral, and dried to obtain acid-treated bamboo powder. The acid-treated bamboo powder was poured into 500mL of a 3mol / L hydrogen peroxide solution, stirred for 3 hours, washed with water until neutral, and dried to obtain oxidatively pretreated bamboo powder. The oxidatively pretreated bamboo powder was poured into 500mL of a 2mol / L sodium sulfite solution, stirred for 3 hours, washed with water until neutral, and dried to obtain sulfonated bamboo powder.

[0109] Group C: Acid-oxidation pretreatment:

[0110] 50g bamboo powder is poured into 2mol / L hydrochloric acid and 2mol / L hydrofluoric acid mixed solution of 500mL, after stirring 12h, washed to neutrality, dry bamboo powder that obtains acid treatment.Acid treatment bamboo powder is poured into 3mol / L hydrogen peroxide solution of 500mL, after stirring 3h, washed to neutrality, dry bamboo powder that obtains oxidation pretreatment.The bamboo powder obtained is that pretreatment bamboo powder carries out subsequent step.

[0111] The performance test of lithium ion capacitor was carried out according to the scheme of Example 1, and the results were as follows:

[0112] Group A: This lithium-ion capacitor has the highest energy density and power density, at 110Wh / kg and 14.8kW / kg, respectively.

[0113] Group B: This lithium-ion capacitor has the highest energy density and power density, at 117Wh / kg and 15.7kW / kg, respectively.

[0114] Group C: This lithium-ion capacitor has the highest energy density and power density, at 98Wh / kg and 13.2kW / kg, respectively.

[0115] Comparison of Examples 1 and 2 shows that acid treatment, combined with oxidation-sulfonation treatment, can synergistically improve the performance of bamboo charcoal-based materials.

[0116] Example 3

[0117] Compared with Example 1, the only difference is that the subcritical treatment conditions in step (2) are changed. The experimental groups are:

[0118] Group A: Changes in subcritical temperature and pressure:

[0119] 10g of pretreated bamboo powder was placed in a 3mol / L mixed solution of potassium carbonate and sodium carbonate (alkaline substance A) at a molar ratio of 2:1 and a liquid-to-solid ratio of 6mL / g. After stirring for 1 hour, the mixture was filled into a subcritical reactor under air atmosphere to a volume of 60%. The reactor was then heated to a subcritical state of 250°C and 18 MPa, and maintained at this pressure for 6 hours. After cooling, the solid-liquid separation was performed to obtain bamboo liquid.

[0120] Group B: Change the combination of alkaline substances A:

[0121] The alkaline substance A is sodium hydroxide and sodium carbonate in a molar ratio of 1:1. Other operations and parameters are the same as those in Example 1.

[0122] Group C: Alkaline substance A is changed:

[0123] The alkaline substance is sodium carbonate alone, and the total amount of alkaline substance A used is the same as that in Example 1.

[0124] Group D: (Change in filling volume):

[0125] The filling volume was 70%, and other operations and parameters were the same as in Example 1.

[0126] Group E: Filling under argon atmosphere

[0127] The mixture was loaded into a subcritical reactor under an argon atmosphere (argon was introduced into the reactor in advance, and then the mixed solution was introduced. After the loading was completed, argon was introduced again to replace the atmosphere therein). Other operations and parameters were the same as in Example 1.

[0128] The performance test of lithium ion capacitor was carried out according to the scheme of Example 1, and the results were as follows:

[0129] Group A: Li-ion capacitors have the highest energy density and power density, at 112Wh / kg and 15.1kW / kg respectively.

[0130] Group B: Li-ion capacitors have the highest energy density and power density, at 135Wh / kg and 18.1kW / kg respectively.

[0131] Group C: Li-ion capacitors have the highest energy density and power density, at 101Wh / kg and 13.6kW / kg respectively.

[0132] Group D: Li-ion capacitors have the highest energy density and power density, at 106Wh / kg and 14.3kW / kg respectively.

[0133] Group E: Li-ion capacitors have the highest energy density and power density, at 118Wh / kg and 15.9kW / kg respectively.

[0134] It can be seen from Examples 1 and 3 that the alkaline substance A composed of hydroxide and carbonate, combined with subcritical conditions and a protective atmosphere filling method, can further synergistically improve the performance of the prepared material.

[0135] Example 4

[0136] Compared with Example 1, the only difference is that the conditions of step (3) are changed. The experimental groups are:

[0137] Group A:

[0138] The amount of additive B used was 10 g, and other operations and parameters were the same as in Example 1.

[0139] Group B:

[0140] Additive B is small-particle flaky magnesium hydroxide (additive B) with a particle size range of 100 to 150 nm. Other operations and parameters are the same as those in Example 1.

[0141] C:

[0142] The methane-argon mixed atmosphere was replaced with a hydrogen-argon mixed atmosphere (3% hydrogen). Other operations and parameters were the same as those in Example 1.

[0143] D:

[0144] Additive B includes additive B1 (same as additive B in Example 1) and additive B2 (same as group B in Example 4) in a weight ratio of 1:1.

[0145] E:

[0146] The calcination temperature (T1) was 750° C. Other operations and parameters were the same as those in Example 1.

[0147] The performance test of lithium ion capacitor was carried out according to the scheme of Example 1, and the results were as follows:

[0148] Group A: Lithium-ion capacitors have the highest energy density and power density, at 113Wh / kg and 15.3kW / kg respectively.

[0149] Group B: Li-ion capacitors have the highest energy density and power density, at 126Wh / kg and 17.0kW / kg, respectively.

[0150] Group C: Li-ion capacitors have the highest energy density and power density, at 131Wh / kg and 17.7kW / kg respectively.

[0151] Group D: Li-ion capacitors have the highest energy density and power density, at 137Wh / kg and 18.5kW / kg respectively.

[0152] Group E: Li-ion capacitors have the highest energy density and power density, at 123Wh / kg and 16.5kW / kg respectively.

[0153] It can be seen from Examples 1 and 4 that the use of graded additive B can further synergistically improve the performance.

[0154] Example 5

[0155] Compared with Example 1, the only difference is that the conditions of step (4) are changed. The experimental groups are:

[0156] A:

[0157] Disperse 10 mL of tetraethyl orthosilicate in 78 mL of ethanol to obtain mixed solution A. Add 0.3 g of lamellar hierarchical porous carbon (prepared in step (3)) and 1.6 g of hexadecyltrimethylammonium bromide to the mixture and stir thoroughly. Disperse 10 mL of aqueous ammonia in 182 mL of a solvent consisting of ethanol and water (volume ratio of 1:1.5) to obtain mixed solution B. Pour mixed solution B rapidly into mixed solution A and stir at room temperature at 600 rpm for 6 h to obtain a colloidal precipitate. Filter, wash with water to neutrality, and dry at 60°C to obtain a composite precursor. Take 2.5g of composite precursor powder, mix it with 25g of sodium chloride and 2.3g of metallic magnesium powder, heat it to 750℃ at 5℃ / min under argon atmosphere and keep it for 6h. After cooling to room temperature, take it out and pickle it in 2mol / L hydrochloric acid for 6h, filter it, wash it with water until it is neutral, and vacuum dry it at 60℃ to obtain a nanosilicon / lamellar hierarchical porous carbon composite material (negative electrode active material).

[0158] B:

[0159] In step (4), the reducing agent is changed to magnesium silicide, and the other operations and parameters are the same as those in Example 1.

[0160] C:

[0161] In step (4), the calcination temperature T2 is changed to 650° C., and the other operations and parameters are the same as those in Example 1.

[0162] The performance test of lithium ion capacitor was carried out according to the scheme of Example 1, and the results were as follows:

[0163] Group A: Li-ion capacitors have the highest energy density and power density, at 109Wh / kg and 14.7kW / kg respectively.

[0164] Group B: Li-ion capacitors have the highest energy density and power density, at 127Wh / kg and 16.9kW / kg respectively.

[0165] Group C: Li-ion capacitors have the highest energy density and power density, at 107Wh / kg and 14.4kW / kg respectively.

[0166] Example 6

[0167] Compared with Example 1, the only difference is that during the assembly of the lithium ion capacitor, only the negative electrode of the present invention is used, and a conventional commercial activated carbon positive electrode is used (the commercial activated carbon replaces the positive electrode active material prepared in step 3 of the present invention). The conventional commercial activated carbon positive electrode active material, Super-P, and PVDF are mixed in a mass ratio of 8:1:1, and an appropriate amount of NMP is added and stirred evenly to form a positive electrode sheet.

[0168] The performance test of the lithium ion capacitor was carried out according to the scheme of Example 1, and the results were:

[0169] The maximum energy density and power density of this lithium-ion capacitor are 95Wh / kg and 12.9kW / kg respectively.

[0170] Example 7

[0171] Step (1): Preprocessing:

[0172] 50g bamboo powder was poured into a mixed solution of 2mol / L hydrochloric acid and 2mol / L hydrofluoric acid of 500mL, stirred for 12h, and then washed to neutrality and dried to obtain acid-treated bamboo powder. Acid-treated bamboo powder was poured into a 6mol / L hydrogen peroxide solution of 500mL, stirred for 4h, and then washed to neutrality and dried to obtain oxidative pretreated bamboo powder. Oxidative-treated bamboo powder was poured into a 2mol / L sodium sulfite solution of 500mL, stirred for 3h, and then washed to neutrality and dried to obtain sulfonated pretreated bamboo powder.

[0173] Take 10g of nano-magnesium oxide and put it into 300mL of water, transfer it into a polytetrafluoroethylene hydrothermal tank, and maintain it at 120℃ for 2h to obtain flaky magnesium hydroxide.

[0174] Step (2): Subcritical liquefaction:

[0175] 10g of pretreated bamboo powder was placed in a 3mol / L mixed solution of sodium hydroxide and sodium carbonate (alkaline substance A) at a 2:1 molar ratio and a liquid-to-solid ratio of 6mL / g. After stirring for 1 hour, the mixture was filled into a subcritical reactor under a nitrogen atmosphere to 70% of its volume. The reactor was then heated to a subcritical state of 250°C and 18 MPa, where it was maintained at this pressure for 6 hours. After cooling, the solid-liquid separation was performed to obtain bamboo liquid.

[0176] Step (3): Preparation of positive electrode active material:

[0177] After adding 10 g of additive B (same as Group D in Example 4) to the bamboo sap from step (2), the mixture was evaporated to dryness under reduced pressure in a vacuum drying oven at 100°C. The mixture was then transferred to a tube furnace in a hydrogen-argon mixed atmosphere (5% hydrogen) and heated to 750°C for 2 h at a heating rate of 5°C / min. The mixture was cooled to room temperature and then removed. The heat-treated product was acid-washed with 2 mol / L hydrochloric acid, washed with water until neutral, and dried at 80°C to obtain a lamellar hierarchical porous carbon material (positive electrode active material).

[0178] Step (4): Preparation of negative electrode active material:

[0179] Disperse 10 mL of tetraethyl orthosilicate in 78 mL of ethanol to obtain mixed solution A. Add 0.3 g of lamellar hierarchical porous carbon (prepared in step (3)) and 1.6 g of hexadecyltrimethylammonium bromide to the mixture and stir thoroughly. Disperse 10 mL of aqueous ammonia in 182 mL of a solvent consisting of ethanol and water (volume ratio of 1:1.5) to obtain mixed solution B. Pour mixed solution B rapidly into mixed solution A and stir at room temperature at 600 rpm for 6 h to obtain a colloidal precipitate. Filter, wash with water to neutrality, and dry at 60°C to obtain a composite precursor. Take 2.5g of composite precursor powder, mix it with 25g of sodium chloride and 2.3g of magnesium silicide, heat it to 650℃ at 5℃ / min under argon atmosphere and keep it for 6h. After cooling to room temperature, take it out and pickle it in 2mol / L hydrochloric acid for 6h, filter it, wash it with water until it is neutral, and vacuum dry it at 60℃ to obtain a nanosilicon / lamellar hierarchical porous carbon composite material (negative electrode active material).

[0180] The performance test of the lithium ion capacitor was carried out according to the scheme of Example 1, and the results were:

[0181] The maximum energy density and power density of this lithium-ion capacitor are 180Wh / kg and 25kW / kg respectively.

[0182] Comparative Example 1:

[0183] Compared with Example 1, the only difference is that there is no oxidation pretreatment operation during the pretreatment process of step (1), specifically:

[0184] 50 g of bamboo powder was poured into 500 mL of a mixed solution of 2 mol / L hydrochloric acid and 2 mol / L hydrofluoric acid, stirred for 12 h, washed with water until neutral, and dried to obtain acid-treated bamboo powder. The acid-treated bamboo powder was poured into 500 mL of a 1 mol / L sodium sulfite solution, stirred for 2 h, washed with water until neutral, and dried to obtain sulfonated pretreated bamboo powder.

[0185] The performance test of the lithium ion capacitor was carried out according to the scheme of Example 1, and the results were:

[0186] The maximum energy density and power density of this lithium-ion capacitor are 92Wh / kg and 12.4kW / kg respectively.

[0187] Comparative Example 2:

[0188] Compared with Example 1, the only difference is that no alkaline substance A is used in the subcritical process of step (2). Other operations and parameters are the same as those in Example 1.

[0189] The performance test of the lithium ion capacitor was carried out according to the scheme of Example 1, and the results were:

[0190] The maximum energy density and power density of this lithium-ion capacitor are 55Wh / kg and 7.4kW / kg respectively.

[0191] Comparative Example 3:

[0192] Compared with Example 1, the only difference is that in step (2), the temperature T0 is 100° C. and the system pressure is 3 MPa: other operations and parameters are the same as in Example 1.

[0193] The performance test of the lithium ion capacitor was carried out according to the scheme of Example 1, and the results were:

[0194] The maximum energy density and power density of this lithium-ion capacitor are 93Wh / kg and 12.6kW / kg respectively.

[0195] Comparative Example 4:

[0196] Compared with Example 1, the only difference is that no additive B is added in step (3), specifically:

[0197] The bamboo sap from step (2) was evaporated to dryness under reduced pressure in a vacuum drying oven at 100°C and then transferred to a tube furnace in a methane-argon mixed atmosphere (5% methane). The temperature was raised to 650°C and maintained for 2 hours at a heating rate of 5°C / min. The mixture was cooled to room temperature and then removed. The heat-treated product was acid-washed with 2 mol / L hydrochloric acid, washed with water until neutral, and dried at 80°C to obtain a lamellar hierarchical porous carbon material (positive electrode active material). Other operations and parameters were the same as in Example 1.

[0198] The performance test of the lithium ion capacitor was carried out according to the scheme of Example 1, and the results were:

[0199] The maximum energy density and power density of this lithium-ion capacitor are 61Wh / kg and 8.2kW / kg respectively.

[0200] Comparative Example 5:

[0201] Compared with Example 1, the only difference is that in step (3), the roasting temperature T1 is 1000° C., and the other operations and parameters are the same as Example 1.

[0202] The performance test of the lithium ion capacitor was carried out according to the scheme of Example 1, and the results were:

[0203] The maximum energy density and power density of this lithium-ion capacitor are 88Wh / kg and 11.8kW / kg respectively.

Claims

1. A method for preparing a bamboo charcoal-based active material, characterized in that the steps include: Step (1): The bamboo powder is pretreated, and then a raw material solution containing the pretreated bamboo powder and alkaline substance A is heated to a subcritical state, kept at a temperature and pressure for liquefaction, and then solid-liquid separation is performed to obtain a treated solution; The alkaline substance A is a compound of a first main group metal element; the pretreatment process includes acid treatment and subsequent oxidation treatment; the acid solution in the acid treatment process is an inorganic acid aqueous solution; The oxidation step comprises: mixing the acid-treated bamboo powder with a hydrogen peroxide solution for oxidation treatment; The temperature in the subcritical treatment stage is 140~280℃ and the pressure is 10~20MPa; Step (2): The treatment liquid and the additive B are combined and the solvent is removed to obtain a precursor, which is then heat-treated; then washed and dried to obtain a bamboo charcoal-based active material; The additive B is at least one water-insoluble component selected from calcium, magnesium, strontium and barium; The heat treatment temperature is 600~950℃.

2. The method for preparing the bamboo charcoal-based active material according to claim 1, wherein: The concentration of hydrogen peroxide solution is 2~6mol / L.

3. The method for preparing the bamboo charcoal-based active material according to claim 1, wherein: The pretreatment stage also includes a sulfonation step: mixing the oxidized bamboo powder with a sulfite solution for sulfonation.

4. The method for preparing the bamboo charcoal-based active material according to claim 1, wherein: The alkaline substance A is at least one of sodium hydroxide, potassium hydroxide, sodium carbonate and potassium carbonate.

5. The method for preparing the bamboo charcoal-based active material according to claim 4, wherein: The alkaline substance A is a mixture of sodium hydroxide and sodium carbonate.

6. The method for preparing the bamboo charcoal-based active material according to claim 5, wherein: The alkaline substance A is a mixture of sodium hydroxide and sodium carbonate in a molar ratio of 1 to 3:

1.

7. The method for preparing a bamboo charcoal-based active material according to claim 1, wherein: In the raw material solution, the solute concentration of the alkaline substance A is 1~6 mol / L, and the liquid-solid ratio is 4~8 mL / g.

8. The method for preparing a bamboo charcoal-based active material according to claim 1, wherein: The raw material solution is loaded into a subcritical processing device under air or protective atmosphere.

9. The method for preparing a bamboo charcoal-based active material according to claim 8, wherein: The filling volume of the raw material solution in the subcritical processing equipment is 60-80%.

10. The method for preparing a bamboo charcoal-based active material according to claim 1, wherein: The additive B is at least one of calcium oxide, calcium carbonate, magnesium oxide, magnesium carbonate and magnesium hydroxide.

11. The method for preparing a bamboo charcoal-based active material according to claim 1, wherein: The particle size of the additive B is less than or equal to 500 nm.

12. The method for preparing a bamboo charcoal-based active material according to claim 11, wherein: The additive B includes a small-particle additive B1 with a particle size of 100-300 nm and a large-particle additive B2 with a particle size of 350-500 nm.

13. The method for preparing a bamboo charcoal-based active material according to claim 1, wherein: The weight ratio of bamboo powder to additive B required for the treatment solution is 1:0.5~2.

14. The method for preparing a bamboo charcoal-based active material according to claim 1, wherein: The method for removing the solvent is evaporation under normal pressure or reduced pressure.

15. The method for preparing a bamboo charcoal-based active material according to claim 1, wherein: The heat treatment atmosphere is a protective atmosphere, or a mixed atmosphere of reducing gas and protective gas.

16. The method for preparing a bamboo charcoal-based active material according to claim 15, wherein: The reducing gas is at least one of hydrogen, CO and CH4.

17. The method for preparing a bamboo charcoal-based active material according to claim 1, wherein: The temperature of the heat treatment is 650-750°C.

18. The method for preparing a bamboo charcoal-based active material according to claim 1, wherein: The heat treatment time is 0.5~3h.

19. The method for preparing a bamboo charcoal-based active material according to claim 1, wherein: The washing process includes pickling and water washing processes.

20. A bamboo charcoal-based active material prepared by the preparation method according to any one of claims 1 to 19.

21. A method for preparing a bamboo charcoal-based silicon-carbon composite active material, characterized in that: The bamboo charcoal-based active material is prepared by the preparation method according to any one of claims 1 to 19, and then compounded with a silicon source to form a composite precursor, which is then subjected to reduction roasting treatment, and then washed and dried to obtain the bamboo charcoal-based silicon-carbon composite active material.

22. The method for preparing the bamboo charcoal-based silicon-carbon composite active material according to claim 21, wherein: The composite precursor can be obtained by hydrolysis and polycondensation, and the steps are: hydrolysis and polycondensation of bamboo charcoal-based active materials and organic silicate under alkaline conditions.

23. The method for preparing the bamboo charcoal-based silicon-carbon composite active material according to claim 22, wherein: The organic silicate is a silicate formed by silicic acid and C1-C6 alcohol.

24. The method for preparing the bamboo charcoal-based silicon-carbon composite active material according to claim 22, wherein: The alkaline condition can be created by at least one alkaline component selected from the group consisting of an ammonia source, sodium hydroxide, and potassium hydroxide.

25. The method for preparing the bamboo charcoal-based silicon-carbon composite active material according to claim 24, wherein: The ammonia source is one or more of ammonia water, urea, thiourea, ethylenediamine, melamine, methylurea, ethylurea, hydroxyurea and semicarbazide.

26. The method for preparing the bamboo charcoal-based silicon-carbon composite active material according to claim 21, wherein: The reduction roasting treatment is a metal heat treatment, and the steps are: mixing the composite precursor, the reducing metal and the metal chloride, heating them, and performing the reduction roasting treatment.

27. The method for preparing the bamboo charcoal-based silicon-carbon composite active material according to claim 26, wherein: The reducing agent is a reducing metal element or magnesium silicide.

28. The method for preparing the bamboo charcoal-based silicon-carbon composite active material according to claim 26, wherein: The temperature of the reduction roasting stage is 500~800℃.

29. The method for preparing the bamboo charcoal-based silicon-carbon composite active material according to claim 28, wherein: The reduction roasting time is 2~12h.

30. The method for preparing the bamboo charcoal-based silicon-carbon composite active material according to claim 21, wherein: The washing process includes pickling and water washing processes.

31. A bamboo charcoal-based silicon-carbon composite active material prepared by the preparation method according to any one of claims 21 to 30.

32. Use of a bamboo charcoal-based active material prepared by the preparation method according to any one of claims 1 to 19 or a bamboo charcoal-based silicon-carbon composite active material prepared by the preparation method according to any one of claims 21 to 30, characterized in that: It is used as an electrode active material to prepare energy storage devices.

33. The use according to claim 32, characterized in that The bamboo charcoal-based active material is used as a positive electrode active material, and / or the bamboo charcoal-based silicon-carbon composite active material is used as a negative electrode active material to prepare an energy storage device.

34. The use according to claim 33, wherein The energy storage device is a lithium ion capacitor.

35. A lithium ion capacitor, characterized in that The positive electrode active material is a bamboo charcoal-based active material prepared by the preparation method according to any one of claims 1 to 19, and / or the negative electrode active material is a bamboo charcoal-based silicon-carbon composite active material prepared by the preparation method according to any one of claims 21 to 30.

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