Method for rapidly preparing hard carbon negative electrode material from waste wind power blade, obtained product and application

Abstract

The invention discloses a method for rapidly preparing a hard carbon negative electrode material from a waste wind turbine blade, an obtained product and application, and the method comprises the following steps: putting the waste wind turbine blade into a mixed solution of acetic acid and hydrogen peroxide, heating for reaction, filtering after the reaction, and distilling filtrate to obtain degraded resin; and carrying out heating curing on the degraded resin to obtain cured resin, carrying out pre-carbonization on the cured resin, and then carrying out Joule heat high-temperature carbonization to obtain the hard carbon negative electrode material. According to the method, fibers and resin in the waste wind turbine blades are separated through one-step reaction by adopting a chemical recovery method, and the hard carbon negative electrode material is prepared by utilizing a Joule heating technology, so that the preparation period of the hard carbon negative electrode material is shortened, the energy consumption is reduced, and the application of the hard carbon negative electrode material in the sodium-ion battery has good application prospects. And the initial coulombic efficiency, platform capacity and total capacity of the prepared sodium ion battery can be simultaneously improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of solid waste resource utilization, and specifically relates to a method for quickly preparing hard carbon negative electrode materials from discarded wind turbine blades, and the resulting products and applications. Background Art

[0002] Fiber-reinforced composite materials are the main components of wind turbine blades, including fibers (glass fibers and carbon fibers) and epoxy resins. In fiber-reinforced composite materials, the complex three-dimensional cross-linked structure between fibers and resins makes them difficult to degrade. Therefore, there are huge challenges in the harmless and resource-based recycling of fiber-reinforced composite materials. Researchers have proposed many feasible recycling methods, mainly including mechanical recycling, thermal recycling and chemical recycling. Among them, the chemical recycling method has a strong processing capacity and can simultaneously recover fibers and degraded resin products under relatively mild reaction conditions.

[0003] Patent CN118003515A discloses a chemical recovery method for fan blades, wherein composite waste with glass fiber or carbon fiber is placed in an acidic degradation solution (including acetic acid, hydrogen peroxide, etc.) for reaction, and a fiber cloth without resin residue and a resin in the degradation solution are obtained, and the recovered resin can be recycled or refined for use by the manufacturer. Patent CN102391543A discloses a method for recovering carbon fiber reinforced epoxy resin composite materials, wherein green oxidants and organic solvents are used as reaction reagents (including acetic acid, hydrogen peroxide, etc.), and fibers without resin residue are obtained under mild reaction conditions, and by controlling the reaction conditions, the degraded resin is produced with phenol and its homologues, which can be used as chemical raw materials, etc., for reuse. However, the above method requires a two-step degradation procedure, and the recovery process is complicated. Although the patent points out the possible use method of the recovered resin product, it is not specifically implemented. At present, the recovery of waste resin is used to prepare many products, such as regenerated fiber reinforced composite materials, polyurethane, oil absorbent, etc., but it still belongs to low-value applications, and the research on high-value utilization of recovered resin is less.

[0004] Patent CN111825072A uses the FRP particles of discarded fans as raw materials, and uses the heat recovery method to directly carbonize the resin components in the FRP to obtain pre-carbonized resin particles, which are then placed in a strong alkaline solution to dissolve the glass fiber, and the insoluble matter is washed and dried and mixed with starch, and then placed in a heating furnace for carbonization treatment to obtain a hard carbon material for use as a negative electrode for lithium-ion batteries. However, the preparation process is complicated and the glass fiber is not recycled. Patent CN115490223A mixes waste phenolic resin with epoxy resin, and dopes it with metal and non-metallic elements, and then performs high-temperature carbonization treatment in a tubular furnace to prepare a multi-element doped hard carbon negative electrode material for use as a negative electrode for sodium-ion batteries. These two prior arts use traditional carbonization technology, and the carbonization is carried out in a heating furnace, which has problems such as long calcination time and high energy consumption. Summary of the invention

[0005] In view of the problems of complex recycling process, high energy consumption and low utilization value of recycled resin in the current waste wind turbine blades, the present invention provides a high-value recycling method for waste wind turbine blades. The waste wind turbine blades are decomposed by chemical recycling method to obtain two main products: resin and fiber. Among them, the fiber product can be directly recycled and reused, while the resin product is prepared into hard carbon negative electrode material through Joule heating technology. Compared with traditional tubular furnace heating, this method is fast, short in process and low in energy consumption, and can convert the waste resin in the wind turbine blades into high-value hard carbon negative electrode materials, turning waste into treasure.

[0006] The specific technical solutions of the present invention are as follows:

[0007] A method for rapidly preparing hard carbon negative electrode materials from discarded wind turbine blades comprises the following steps:

[0008] (1) Resin recovery: the discarded wind turbine blades are placed in a mixture of acetic acid and hydrogen peroxide, heated for reaction, filtered after the reaction, and the filtrate is distilled to obtain degraded resin;

[0009] (2) Carbonized resin: The degraded resin is heated and cured to obtain a cured resin, and the cured resin is first pre-carbonized and then carbonized at high temperature using Joule heat to obtain a resin-based hard carbon negative electrode material.

[0010] Furthermore, in step (1), the discarded wind turbine blade is a wind turbine blade with metal components removed, and the wind turbine blade is made of a fiber reinforced composite material, and the fiber reinforced composite material is made of fiber and resin, the fiber is glass fiber or carbon fiber, and the resin is epoxy resin.

[0011] Furthermore, in step (1), acetic acid is used as a swelling agent and hydrogen peroxide is used as a green oxidant. When the two are mixed, they can effectively break the CN bonds in the fiber-reinforced composite material of the discarded wind turbine blades. The resin after the bond breaking is dissolved in the acetic acid and hydrogen peroxide mixture, thereby achieving a one-step separation of the fiber and the resin.

[0012] Furthermore, in step (1), the mixed solution of acetic acid and hydrogen peroxide consists of acetic acid, hydrogen peroxide and water. There is no particular requirement for the mixing order of the three. The three can be mixed at the same time, or the acetic acid can be prepared into an aqueous solution, the hydrogen peroxide can be prepared into an aqueous solution, and then the acetic acid aqueous solution and the hydrogen peroxide aqueous solution are mixed.

[0013] Furthermore, in step (1), the mixed solution of acetic acid and hydrogen peroxide is prepared by mixing an aqueous solution of acetic acid and hydrogen peroxide. When the concentration of the aqueous solution of acetic acid is 12-15 mol / L and the concentration of the hydrogen peroxide is 6-10 wt %, the volume ratio of the aqueous solution of acetic acid to the hydrogen peroxide is 4-10:1, for example, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1.

[0014] Furthermore, in step (1), the ratio of the fiber-reinforced composite material of the discarded wind turbine blades to the mixed solution of acetic acid and hydrogen peroxide is 1g:20-60ml, for example, 1g:20ml, 1g:30ml, 1g:40ml, 1g:50ml, 1g:60ml.

[0015] Furthermore, in step (1), the reaction is carried out in a reactor. After adding the materials, the reactor is sealed and allowed to stand without stirring to react, which can also be called a static reaction.

[0016] Furthermore, in step (1), in order to degrade the fiber reinforced composite material faster, the discarded wind turbine blades may be crushed and cut into small pieces or fragments.

[0017] Furthermore, in step (1), the fiber reinforced composite material is heated to react and the resin therein is recovered. The reaction temperature is 100-200°C, such as 100°C, 120°C, 150°C, 180°C, 200°C, and the reaction time is 4-10h, such as 4h, 5h, 6h, 7h, 8h, 9h, 10h.

[0018] Furthermore, in step (1), after the reaction, the reaction is filtered, and the resulting filter cake is the recovered fiber. The liquid contains degraded resin, and the filtrate is distilled until no liquid remains to obtain the degraded resin product. The distillation can be carried out under normal pressure or reduced pressure.

[0019] Furthermore, in step (2), the obtained degraded resin is heated and cured, which can not only remove the liquid residue but also enhance the crosslinking property of the degraded resin product. The curing temperature is 100-180°C, such as 100°C, 120°C, 150°C, 180°C, and the curing time is 4-12h, such as 4h, 5h, 6h, 7h, 8h, 9h, 10h, 11h, 12h.

[0020] Furthermore, in step (2), the heat-cured resin is subjected to low-temperature pre-carbonization and high-temperature carbonization using Joule heat in a protective atmosphere or vacuum environment. The protective atmosphere is an inert atmosphere such as nitrogen and argon.

[0021] Furthermore, in step (2), low-temperature pre-carbonization is a heating decomposition process of the resin to remove gas and liquid to obtain a solid product. The pre-carbonization temperature is 500-800°C, such as 500°C, 550°C, 600°C, 650°C, 700°C, 750°C, 800°C, and the holding time is 1-3h, such as 1h, 2h, 3h.

[0022] Furthermore, in step (2), the heating rate is 1-5°C / min, for example, 1°C / min, 2°C / min, 3°C / min, 4°C / min, 5°C / min.

[0023] Furthermore, in step (2), the high-temperature carbonization treatment using Joule heat can effectively improve the graphitization degree of the hard carbon, enhance its conductivity, and reduce the specific surface area of ​​the hard carbon. A large number of micropores in the hard carbon disappear to form closed pores, thereby providing more sodium storage space and improving the performance of the sodium ion battery. The temperature of the Joule heat high temperature carbonization is 1200-2800°C, for example, 1200°C, 1300°C, 1400°C, 1500°C, 1600°C, 1700°C, 1800°C, 1900°C, 2000°C, 2100°C, 2200°C, 2300°C, 2400°C, 2500°C, 2600°C, 2700°C, 2800°C, and the insulation time is 1-60s, for example, 1s, 3s, 5s, 8s, 10s, 15s, 20s, 25s, 30s, 35s, 40s, 45s, 50s, 55s, 60s.

[0026] Furthermore, in step (2), Joule heat high temperature carbonization can achieve rapid high temperature carbonization and instantaneous cooling, and can quickly reach the carbonization high temperature in 1-2 seconds, and can quickly cool to room temperature in 1-5 seconds after carbonization is completed.

[0027] The hard carbon negative electrode material obtained by the invention has a small specific surface area and a large sodium storage space, and can be used in the battery field as a negative electrode material of a battery, especially as a negative electrode of a sodium ion battery.

[0028] The beneficial effects of the present invention are:

[0029] 1. The present invention utilizes a chemical recovery method to place a mixed solution of acetic acid and hydrogen peroxide and waste wind turbine blade fiber-reinforced composite materials into a reactor for static reaction, thereby achieving one-step separation of fibers and resins, and the separation process is simple.

[0030] 2. The present invention uses the recycled resin as a precursor and prepares the hard carbon negative electrode material through carbonization treatment, which saves the cost of preparing hard carbon and also realizes the high-value resource utilization of the waste resin.

[0031] 3. The present invention utilizes Joule heating technology to achieve rapid high-temperature carbonization and instant cooling of the material by applying high voltage and high current between two electrodes, which significantly shortens the carbonization time and reduces energy consumption. At the same time, the Joule heat high-temperature carbonization treatment reduces the specific surface area of ​​hard carbon, increases the degree of graphitization, and enhances conductivity, which can provide more sodium storage space and improve the performance of sodium ion batteries.

[0032] 4. The resin-based hard carbon negative electrode material prepared by the present invention can be used as the negative electrode material of sodium ion batteries. The assembled sodium ion batteries have higher initial coulombic efficiency and better cycle stability, and the platform capacity and total capacity are also significantly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is a SEM image of the hard carbon negative electrode material prepared in Example 1;

[0034] Figure 2 XRD comparison diagram of the hard carbon negative electrode materials prepared in Example 1 and Comparative Example 1;

[0035] Figure 3 A comparison diagram of nitrogen adsorption and desorption curves of the hard carbon negative electrode materials prepared in Example 1 and Comparative Example 1;

[0036] Figure 4 A comparison diagram of the first cycle charge and discharge curves of the sodium ion battery hard carbon negative electrode material assembled in Example 1 and Comparative Example 1 at a current density of 0.1C;

[0037] Figure 5 It is a comparison chart of the platform capacity of Example 1 and Comparative Example 1 during the discharge and charge processes at a current density of 0.1C. DETAILED DESCRIPTION

[0038] The following is a description of exemplary embodiments of the present invention, including various details of the embodiments of the present invention to aid understanding, which should be considered as merely exemplary. Therefore, it should be appreciated by those of ordinary skill in the art that various changes and modifications may be made to the embodiments described herein without departing from the scope and spirit of the present invention. Likewise, for clarity and simplicity, descriptions of well-known functions, operations, and structures are omitted in the following description.

[0039] Unless otherwise defined, the technical and scientific terms in this specification have the same meaning as those commonly understood by those skilled in the art. Although similar or identical methods and materials as those described herein may be used in experiments or practical applications, the present invention still describes the materials and methods below. In the event of a conflict, the present specification, including definitions, shall prevail.

[0040] Unless otherwise specified, the following concentrations are all mass percentage concentrations, and all reagents used are commercially available products.

[0041] Example 1

[0042] (1) Resin recovery: Remove the metal components from the discarded wind turbine blades and cut them into small pieces for later use. Mix 36.00 ml of acetic acid aqueous solution (concentration of 14 mol / l) and 4.00 ml of hydrogen peroxide aqueous solution (concentration of 8 wt%) and stir evenly, add them into the reactor together with 1.00 g of the discarded wind turbine blade fiber reinforced composite material block, seal the reactor, and react statically at 120°C for 6 hours. After the reaction, filter the reaction product, distill the filtrate until there is no liquid residue, and obtain a viscous liquid, which is the degraded resin product.

[0043] (2) Carbonized resin: The above resin product was heated and cured at 180°C in an oven for 12 hours, and then the cured resin was placed in a tubular furnace, heated to 800°C at a heating rate of 5°C / min in an argon atmosphere and kept warm for 3 hours to obtain a pre-carbonized material. The pre-carbonized material was ground into powder and placed in a Joule heating device, heated to 1500°C in 1 second in an argon atmosphere, kept warm for 20 seconds, and then quickly cooled to room temperature in about 3 seconds to obtain a resin-based hard carbon negative electrode material.

[0044] Example 2

[0045] (1) Resin recovery: Remove the metal components from the discarded wind turbine blades and cut them into small pieces for later use. Mix 33.12 ml of acetic acid aqueous solution (concentration of 14 mol / l) and 3.68 ml of hydrogen peroxide aqueous solution (concentration of 8%) and stir evenly, add them into the reactor together with 0.92 g of the discarded wind turbine blade fiber reinforced composite material block, seal the reactor, and react statically at 120°C for 6 hours. After the reaction, filter the reaction product, distill the filtrate until there is no liquid residue, and obtain the degraded resin product.

[0046] (2) Carbonized resin: The above resin product is placed in an oven and heated at 180°C for 12 hours. The cured resin is placed in a tubular furnace, heated to 800°C at a heating rate of 5°C / min under an argon atmosphere and kept warm for 3 hours to obtain a pre-carbonized material. The pre-carbonized material is ground into powder and placed in a Joule heating device, heated to 1500°C within 1 second under an argon atmosphere, kept warm for 5 seconds, and then quickly cooled to room temperature in about 3 seconds to obtain a resin-based hard carbon negative electrode material.

[0047] Example 3

[0048] (1) Resin recovery: Remove the metal components from the discarded wind turbine blades and cut them into small pieces for later use. Mix 38.88 ml of acetic acid aqueous solution (concentration of 14 mol / l) and 4.32 ml of hydrogen peroxide aqueous solution (concentration of 8%) and stir evenly, add them into the reactor together with 1.08 g of the discarded wind turbine blade fiber reinforced composite material block, seal the reactor, and react statically at 120°C for 6 hours. After the reaction, filter the reaction product, distill the filtrate until there is no liquid residue, and obtain the degraded resin product.

[0049] (2) Carbonized resin: The above resin product is placed in an oven and heated at 180°C for 12 hours. The cured resin is placed in a tubular furnace, heated to 800°C at a heating rate of 5°C / min in an argon atmosphere and kept warm for 3 hours to obtain a pre-carbonized material. The pre-carbonized material is ground into powder and placed in a Joule heating device, heated to 1500°C within 1 second in an argon atmosphere, kept warm for 10 seconds, and then quickly cooled to room temperature in about 3 seconds to obtain a resin-based hard carbon negative electrode material.

[0050] Example 4

[0051] (1) Resin recovery: Remove the metal components from the discarded wind turbine blades and cut them into small pieces for later use. Mix 44.64 ml of acetic acid aqueous solution (concentration of 14 mol / l) and 4.96 ml of hydrogen peroxide aqueous solution (concentration of 8%) and stir evenly, add them into the reactor together with 1.24 g of the discarded wind turbine blade fiber reinforced composite material block, seal the reactor, and react statically at 120°C for 6 hours. After the reaction, filter the reaction product, distill the filtrate until there is no liquid residue, and obtain the degraded resin product.

[0052] (2) Carbonized resin: The above resin product is placed in an oven and heated at 180°C for 12 hours. The cured resin is placed in a tubular furnace, heated to 800°C at a heating rate of 5°C / min in an argon atmosphere and kept warm for 3 hours to obtain a pre-carbonized material. The pre-carbonized material is ground into powder and placed in a Joule heating device, heated to 1700°C within 1 second in an argon atmosphere, kept warm for 20 seconds, and then quickly cooled to room temperature in about 3 seconds to obtain a resin-based hard carbon negative electrode material.

[0053] Example 5

[0054] (1) Resin recovery: Remove the metal components from the discarded wind turbine blades and cut them into small pieces for later use. Mix 42.48 ml of acetic acid aqueous solution (concentration of 14 mol / l) and 4.72 ml of hydrogen peroxide aqueous solution (concentration of 8%) and stir evenly, add them into the reactor together with 1.18 g of the discarded wind turbine blade fiber reinforced composite material block, seal the reactor, and react statically at 120°C for 6 hours. After the reaction, filter the reaction product, distill the filtrate until there is no liquid residue, and obtain the degraded resin product.

[0055] (2) Carbonized resin: The above resin product is placed in an oven and heated at 180°C for 12 hours. The cured resin is placed in a tubular furnace, heated to 800°C at a heating rate of 5°C / min in an argon atmosphere and kept warm for 3 hours to obtain a pre-carbonized material. The pre-carbonized material is ground into powder and placed in a Joule heating device, heated to 1300°C within 1 second in an argon atmosphere, kept warm for 20 seconds, and then quickly cooled to room temperature in about 3 seconds to obtain a resin-based hard carbon negative electrode material.

[0056] Example 6

[0057] (1) Resin recovery: Remove the metal components from the discarded wind turbine blades and cut them into small pieces for later use. Mix 59.52 ml of acetic acid aqueous solution (concentration of 12 mol / l) and 14.88 ml of hydrogen peroxide aqueous solution (concentration of 10%) and stir evenly, add them into the reactor together with 1.24 g of the discarded wind turbine blade fiber reinforced composite material block, seal the reactor, and react statically at 160°C for 4 hours. After the reaction, filter the reaction product, distill the filtrate until there is no liquid residue, and obtain the degraded resin product.

[0058] (2) Carbonized resin: The above resin product is placed in an oven and heated at 120°C for 8 hours. The cured resin is placed in a tubular furnace, heated to 500°C at a heating rate of 3°C / min under an argon atmosphere and kept warm for 1 hour to obtain a pre-carbonized material. The pre-carbonized material is ground into powder and placed in a Joule heating device, heated to 1500°C within 1 second under an argon atmosphere, kept warm for 20 seconds, and then quickly cooled to room temperature in about 3 seconds to obtain a resin-based hard carbon negative electrode material.

[0059] Example 7

[0060] (1) Resin recovery: Remove the metal components from the discarded wind turbine blades and cut them into small pieces for later use. Mix 17.34 ml of acetic acid aqueous solution (concentration of 12 mol / l) and 3.06 ml of hydrogen peroxide aqueous solution (concentration of 10%) and stir evenly, add them into the reactor together with 1.02 g of the discarded wind turbine blade fiber reinforced composite material block, seal the reactor, and react statically at 100°C for 8 hours. After the reaction, filter the reaction product, distill the filtrate until there is no liquid residue, and obtain the degraded resin product.

[0061] (2) Carbonized resin: The above resin product is placed in an oven and heated at 160°C for 10 hours. The cured resin is placed in a tubular furnace, heated to 600°C at a heating rate of 5°C / min under an argon atmosphere and kept warm for 1 hour to obtain a pre-carbonized material. The pre-carbonized material is ground into powder and placed in a Joule heating device, heated to 1500°C within 1 second under an argon atmosphere, kept warm for 20 seconds, and then quickly cooled to room temperature in about 3 seconds to obtain a resin-based hard carbon negative electrode material.

[0062] Comparative Example 1

[0063] (1) Resin recovery: Remove the metal components from the discarded wind turbine blades and cut them into small pieces for later use. Mix 30.24 ml of acetic acid aqueous solution (concentration of 14 mol / l) and 3.36 ml of hydrogen peroxide aqueous solution (concentration of 8%) and stir evenly, add them into the reactor together with 0.84 g of the discarded wind turbine blade fiber reinforced composite material block, seal the reactor, and react statically at 120°C for 6 hours. After the reaction, filter the reaction product, distill the filtrate until there is no liquid residue, and obtain the degraded resin product.

[0064] (2) Carbonized resin: The above resin product is placed in an oven and heated at 180°C for 12 hours. The cured resin is placed in a tubular furnace, heated to 800°C at a heating rate of 5°C / min in an argon atmosphere and kept warm for 3 hours to obtain a pre-carbonized material. The pre-carbonized material is ground into powder and placed in a graphite furnace, kept warm at 1500°C for 1 hour in an argon atmosphere, and slowly cooled to room temperature after the reaction is completed to obtain a resin-based hard carbon negative electrode material.

[0065] Performance Testing

[0066] The hard carbon negative electrode materials obtained in the examples and comparative examples were assembled into button-type sodium ion batteries. The specific steps were as follows: the obtained hard carbon negative electrode materials, conductive agent (conductive carbon black) and binder (PVDF) were mixed in a mass ratio of 7:2:1, NMP was added as a dispersant, and after being fully mixed, they were coated on copper foil and dried in an oven at 100°C for 12 hours, and then a circular electrode sheet with a diameter of 14 mm was punched out with a tablet press for use. The weighed electrode sheet was placed in a glove box filled with argon gas, GF / B glass fiber was used as the diaphragm of the button-type sodium ion battery, a sodium sheet with a diameter of 14 mm was used as the counter electrode, and the electrolyte was 1.0M sodium perchlorate solution, and a CR2032 button-type sodium ion battery was assembled. After standing for 8 hours, the electrochemical performance of the battery was tested after the electrolyte completely infiltrated the diaphragm.

[0067] The assembled button-type sodium ion battery is subjected to constant current charge and discharge test, which is mainly used to test the coulombic efficiency, charge and discharge specific capacity, cycle stability (i.e. capacity retention rate) of the battery. The charge and discharge test of the present invention is completed in the blue battery test system. The voltage range of the constant current charge and discharge test is 0.01-3.0V, the nominal capacity is 350mAh / g, and the current density is 0.1C.

[0068] The performance test results of button-type sodium ion batteries prepared from the hard carbon negative electrode materials obtained in Examples 1-7 and Comparative Example 1 are shown in Table 1 below:

[0069] Table 1

[0070]

[0071] It can be seen from Table 1 that the initial charging capacity of each embodiment is greater than that of the comparative example. The battery prepared by using the hard carbon negative electrode material obtained in the embodiments of the present invention has good initial charging capacity, high initial coulombic efficiency, charge and discharge platform capacity and cycle stability. Comparative Example 1 is a hard carbon negative electrode material prepared by traditional tubular furnace heating. Compared with the traditional preparation method, the initial charging capacity, initial coulombic efficiency and charge and discharge platform capacity of the hard carbon negative electrode material obtained by the embodiment of the present invention using Joule heating carbonization technology are significantly improved.

[0072] It is also worth noting that Figure 1This is a SEM image of the hard carbon negative electrode material prepared in Example 1. As can be seen from the figure, the prepared hard carbon material is irregular in shape and has a smooth surface, which can prevent the formation of SEI film during the initial discharge process and is beneficial to Na + of the deintercalation, thereby improving the initial Coulombic efficiency.

[0073] Figure 2 The XRD comparison diagram of the hard carbon negative electrode materials prepared in Example 1 and Comparative Example 1. It can be seen from the figure that both samples have broad carbon peaks near 23.5° and 44.3°, with similar peak intensities, and no other impurity peaks.

[0074] Figure 3 The nitrogen adsorption and desorption curves of the hard carbon negative electrode materials prepared in Example 1 and Comparative Example 1 are compared. It can be seen from the figure that the specific surface areas of the samples prepared in Example 1 and Comparative Example 1 are 21.9 m 2 / g and 37.89m 2 / g, and the decrease in specific surface area is mainly attributed to the directional rearrangement of the carbon structure caused by high current density, forming a highly ordered pseudographite structure.

[0075] Figure 4 The first cycle charge and discharge curve comparison diagram of button-type sodium ion batteries assembled in Example 1 and Comparative Example 1 at a current density of 0.1C is shown in the figure. As can be seen from the figure, the battery assembled with the hard carbon negative electrode material of Example 1 has a reversible capacity of 264.75mAh g-1, which is 47.4mAh g-1 higher than that of the battery assembled with the hard carbon negative electrode material of Comparative Example 1, and the initial coulombic efficiency is as high as 91.79%, reflecting good electrochemical performance.

[0076] Figure 5 The following is a comparison chart of the platform capacities of button-type sodium ion batteries assembled in Example 1 and Comparative Example 1 during discharge and charge at a current density of 0.1C. Compared with Comparative Example 1, the battery charge and discharge platform capacities of Example 1 increased from 42.81mAh g-1 and 69.77mAh g-1 to 112.81mAh g-1 and 146.35mAh g-1, respectively, with growth rates of 163.51% and 109.76%, respectively, which improved the overall stability and service life of the battery.

[0077] The above are only preferred exemplary embodiments of the present invention, but the present invention is not limited to these embodiments. Any changes, modifications, substitutions, combinations, simplifications, etc. made under the spirit and principle of the present invention are equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A method for rapidly preparing hard carbon negative electrode materials from discarded wind turbine blades, characterized in that: The following steps are involved: (1) placing the discarded wind turbine blades into a mixture of acetic acid and hydrogen peroxide, heating to react, filtering after the reaction, and distilling the filtrate to obtain a degraded resin; (2) The degraded resin is heated and cured to obtain a cured resin, the cured resin is pre-carbonized, and then carbonized at high temperature using Joule heat to obtain a hard carbon negative electrode material.

2. The method according to claim 1, characterized in that The material of the discarded wind turbine blades is a fiber-reinforced composite material formed by fibers and resin.

3. The method according to claim 1, characterized in that In step (1), the mixed solution of acetic acid and hydrogen peroxide is prepared by mixing an aqueous solution of acetic acid and hydrogen peroxide. The concentration of the aqueous solution of acetic acid is 12-15 mol / L, the concentration of the hydrogen peroxide is 6-10 wt %, and the volume ratio of the aqueous solution of acetic acid to the hydrogen peroxide is 4-10:

1.

4. The method according to claim 1, 2 or 3, characterized in that: In step (1), the ratio of the discarded wind turbine blades to the mixed solution of acetic acid and hydrogen peroxide is 1g:20-60ml.

5. The method according to claim 1, 2 or 3, characterized in that: In step (1), the reaction is carried out in a reactor while standing.

6. The method according to claim 1, 2 or 3, characterized in that: In step (1), the reaction is carried out by heating to 100-200° C., and preferably, the reaction time is 4-10 h.

7. The method according to claim 1, characterized in that In step (2), the curing temperature is 100-180° C., and preferably, the curing time is 4-12 hours.

8. The method according to claim 1, characterized in that In step (2), pre-carbonization and Joule heat high-temperature carbonization are carried out under gas protection or vacuum environment.

9. The method according to claim 1, characterized in that: In step (2), the pre-carbonization temperature is 500-800°C, and the insulation time is 1-3h; preferably, the Joule heating high-temperature carbonization temperature is 1200-2800°C, and the insulation time is 1-60s.

10. A hard carbon negative electrode material prepared by the method for rapidly preparing a hard carbon negative electrode material from discarded wind turbine blades according to any one of claims 1 to 9, and use of the hard carbon negative electrode material in a battery.

Images