Hard carbon negative electrode of high-capacity alkali metal ion battery as well as preparation method and application of hard carbon negative electrode

Abstract

The invention discloses a high-capacity alkali metal ion battery hard carbon negative electrode and a preparation method and application thereof, and belongs to the technical field of preparation of negative electrode materials. The negative electrode material is prepared from recycled polyester-cotton fabric waste protective clothing as a raw material, and the preparation process comprises the following steps: pretreating in an acid environment by using a solvothermal method, and cleaning a pretreated precursor to be neutral by adopting vacuum filtration, centrifugal separation, pressure filtration and sedimentation / decantation methods; the preparation method comprises the following steps: drying the raw materials in one or more modes of normal-pressure drying, freeze drying, vacuum drying, convection drying and conduction drying, and then carbonizing at medium and low temperature in a nitrogen or argon atmosphere at the carbonization temperature of 500-700 DEG C for 1-3 hours; compared with similar materials, the high-capacity alkali metal ion battery hard carbon negative electrode has an obvious capacity advantage in the aspects of potassium ion, sodium ion and lithium ion battery negative electrode materials, and in addition, the raw materials are mainly based on recycled waste, so that the high-capacity alkali metal ion battery hard carbon negative electrode has a price advantage and conforms to the environmental protection concept.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of negative electrode material preparation, in particular to a high-capacity alkali metal ion battery hard carbon negative electrode and a preparation method and application thereof. BACKGROUND

[0002] The discarded protective clothing mainly includes a main body part fabric made of polyester-cotton laboratory protective clothing, medical protective clothing, labor protection clothing or dust-free clothing and the like.

[0003] The polyester-cotton is a kind of composite material fabric woven by polyester fiber (polyester) and cotton fiber after blending spinning. The polyester fiber has high strength and high wear resistance, and has strong resistance to acid, alkali and part of common organic solvents (such as acetone, methanol and the like) at normal temperature, can accept high-temperature cleaning and disinfection. In addition, the cotton fiber also has excellent moisture absorption capacity, which can alleviate the poor moisture permeability of polyester after blending, and the cotton fiber after moisture absorption also has the function of antistatic. In addition, the cotton fiber will carbonize in the flame to form a loose carbon structure, which can absorb the molten polyester fiber at high temperature, thereby ensuring the flame retardant performance of the fabric and avoiding the secondary damage caused by the dripping high-temperature liquid polyester fiber.

[0004] The polyester provides basic safety protection, basic flame retardant performance, ensures wearing comfort and has high durability (compared with traditional textiles such as cotton, hemp, silk and wool). The polyester-cotton is not only widely used in personal protective products such as laboratory protective clothing, medical protective clothing, dust-free clothing, white gowns and labor protection clothing, but also has a large application market in daily consumer goods such as shirts, school uniforms, bed sheets and special fabrics. The polyester-cotton is an important, large-yield and widely used blended variety in the global market, and has a high proportion in the fabric market, which makes the polyester fiber account for a high proportion in the global synthetic fiber, and the polyester fiber output gradually increases. Cotton has become a natural fiber leading material due to its long history and excellent performance.

[0005] However, the recycling rate of blended fabrics represented by polyester-cotton fabric is very low. The market share of recycled polyester fiber decreases, most of which comes from PET plastic bottles. The output of recycled cotton accounts for a very low proportion of the total cotton output, and the market share is extremely low, which is mainly used for dustproof cloth, filling material and insulating material. The application provides a new idea for recycling polyester-cotton, which converts the discarded polyester-cotton clothing into high-performance negative electrode material of alkali metal battery, and has a high capacity.

[0006] Through hydrothermal pretreatment in a concentrated sulfuric acid environment, the polyester fibers in the polyester-cotton material undergo rapid hydrolysis under high temperature and pressure, hydrolyzing into terephthalic acid (TPA) and ethylene glycol (EG), thus exfoliating the cotton fiber portion. The cotton fibers then undergo carbonization under the dehydration effect of concentrated sulfuric acid, forming a needle-like carbon-oxygen composite structure with abundant oxygen-containing functional groups on its surface. As the hydrothermal reaction with concentrated sulfuric acid continues, the hydrolysis and carbonization processes persist, and a large amount of hydrolyzed terephthalic acid (TPA) and ethylene glycol (EG) undergo intermolecular dehydration and condensation reactions, re-coating onto the carbonized needle-like cotton fibers. Subsequently, during the carbonization process of this product, the coated organic polymer components, without disrupting the porous structure and oxygen-deficient environment of the internal cotton fibers, form a regular and dense carbon structure on the surface. This significantly reduces the specific surface area without compromising the high specific capacity of the hard carbon in the cotton fibers, thereby improving the cycle performance as a negative electrode material for lithium, sodium, and potassium-ion batteries.

[0007] Through this beneficial process, this application transforms waste polyester-cotton fabric clothing into a battery anode material with low specific surface area and high capacity, providing a new approach to low-cost, high-performance anodes. Summary of the Invention

[0008] Technical problems to be solved:

[0009] This application proposes a high-capacity hard carbon anode for alkali metal ion batteries, its preparation method, and its application. This addresses the problem in existing technologies where the proportion of recycled cotton production to total cotton production is very low. The hard carbon anode material for alkali metal ion batteries, prepared from recycled polyester-cotton protective clothing, exhibits a significant capacity advantage compared to similar materials. Since its raw materials are mainly based on recycled waste, it not only provides a new approach to polyester-cotton waste recycling but also offers price advantages and aligns with environmental protection principles.

[0010] Technical solution:

[0011] A method for preparing a high-capacity hard carbon anode for alkali metal ion batteries, the specific steps of which are as follows:

[0012] Step 1: Use an acidic solution to perform solvent heat treatment on the recycled waste polyester-cotton fabric and waste protective clothing. The volume-to-mass ratio of the acidic solution to the recycled waste polyester-cotton fabric and waste protective clothing is 20-100mL:20g.

[0013] Step 2: Separate the pretreated solids from the heat-treated material by one or more of the following methods: vacuum filtration, centrifugation, pressure filtration, sedimentation, and decantation.

[0014] Step 3: Clean the pretreated solid and then dry it using one or more of the following methods: atmospheric pressure drying, freeze drying, vacuum drying, convection drying, and conduction drying to obtain the pretreated precursor.

[0015] Step 4: The dried pretreated precursor is carbonized at low and medium temperatures under an inert atmosphere, and after natural cooling, a high-capacity hard carbon anode for alkali metal ion batteries is obtained.

[0016] As a preferred technical solution of this application, the acidic solution in the first step is 95%-98% concentrated sulfuric acid, and the recovered waste polyester-cotton fabric waste protective clothing is one or more of laboratory protective clothing, medical protective clothing, and cleanroom clothing.

[0017] As a preferred technical solution of this application, the solvent heat treatment in the first step is performed at a temperature of 110-150°C for 1-2 hours.

[0018] As a preferred technical solution of this application, the cleaning method in the third step is to clean with deionized water 3-5 times.

[0019] As a preferred technical solution of this application, in the fourth step, the inert atmosphere is argon or nitrogen, the medium-low temperature carbonization equipment is an atmosphere furnace, a tube furnace or PE-CVD, the medium-low temperature carbonization temperature is 500-1000℃, and the medium-low temperature carbonization time is 1-3 hours.

[0020] A high-capacity alkali metal ion battery hard carbon anode prepared by any of the above preparation methods.

[0021] This application also discloses the application of high-capacity alkali metal ion battery hard carbon anodes prepared by any of the above-mentioned methods in lithium-ion, sodium-ion, or potassium-ion batteries.

[0022] As a preferred technical solution of this application, the lithium-ion battery assembly process involves mixing a high-capacity alkali metal ion battery hard carbon negative electrode, acetylene black, and PVDF polyvinylidene fluoride in a mass ratio of 7:2:1, and then mixing and stirring 1g of the mixture in 10ml of N-methylpyrrolidone (NMP) for 6 hours. The mixture is then uniformly coated onto copper foil using a casting method with a thickness of 50-200μm using a spatula. Button batteries are then assembled in an argon atmosphere glove box, with lithium foil as the counter electrode, PP material as the separator, and the electrolyte prepared by mixing 1mol of LiPF6 in a solution of EC:DMC:EMC = 1:1:1.

[0023] As a preferred technical solution of this application, the sodium-ion battery assembly process involves mixing a high-capacity alkali metal ion battery hard carbon negative electrode, acetylene black, and PVDF polyvinylidene fluoride in a mass ratio of 7:2:1, and then mixing and stirring 1g of the mixture in 10ml of N-methylpyrrolidone (NMP) for 6 hours. The mixture is then uniformly coated onto copper foil using a casting method with a thickness of 50-200μm using a spatula. Button batteries are then assembled in an argon atmosphere glove box, with a sodium sheet as the counter electrode, a glass fiber separator, and an electrolyte prepared by mixing 1mol of NaPF6 in a solution of EC:PC = 1:1.

[0024] As a preferred technical solution of this application, the potassium-ion battery assembly process involves mixing a high-capacity alkali metal-ion battery hard carbon negative electrode, acetylene black, and PVDF polyvinylidene fluoride in a mass ratio of 7:2:1, and then mixing and stirring 1g of the mixture in 10ml of N-methylpyrrolidone (NMP) for 6 hours. The mixture is then uniformly coated onto copper foil using a casting method with a thickness of 50-200μm using a spatula. Button batteries are then assembled in an argon atmosphere glove box. The counter electrode is a potassium sheet, the separator is made of glass fiber, and the electrolyte is prepared by mixing 5mol of KFSI in a solution of DIGLYME.

[0025] Beneficial effects:

[0026] 1. This invention provides a method for preparing a high-capacity hard carbon anode for alkali metal ion batteries, and for the first time attempts to recycle polyester-cotton based materials as carbon-based anode materials for alkali metal ion batteries, represented by lithium, sodium, and potassium ion batteries;

[0027] 2. The raw materials used in this invention are widely available and can be stably supplied based on the existing industrial system, making them suitable for large-scale industrial production;

[0028] 3. This invention provides a high-capacity hard carbon anode for alkali metal ion batteries with excellent capacity and outstanding rate performance, offering a cost-effective solution for lithium, sodium, and potassium ion battery anodes;

[0029] 4. This application prepares a battery negative electrode material with low specific surface area and high capacity from waste clothing made of polyester-cotton fabric, providing a new approach for recycling polyester-cotton blended materials. Attached Figure Description

[0030] Figure 1 The images shown are SEM images of the high-capacity alkali metal ion battery hard carbon anode prepared in Example 3 of this application. The upper image is a SEM image at 11K magnification, and the lower image is a SEM image at 30K magnification.

[0031] Figure 2Charge-discharge curves of the high-capacity alkali metal ion battery hard carbon anode prepared in Example 3 of this application as the anode of a sodium ion battery.

[0032] Figure 3 Long-cycle performance of the high-capacity alkali metal ion battery hard carbon anode prepared in Example 3 of this application as a sodium ion battery anode;

[0033] Figure 4 The rate performance diagram of the high-capacity alkali metal ion battery hard carbon anode prepared in Example 3 of this application as a sodium ion battery anode. Detailed Implementation

[0034] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments. These embodiments are only for illustrating the present invention, and the present invention is not limited to the following embodiments. Any modifications or equivalent substitutions to the technical solution of the present invention that do not depart from the spirit and scope of the technical solution of the present invention should be covered within the protection scope of the present invention.

[0035] Example 1:

[0036] A method for preparing a high-capacity hard carbon anode for alkali metal ion batteries, comprising the following steps:

[0037] Step 1: Use 60mL of 95% concentrated sulfuric acid to perform solvent heat treatment on 20g of recycled waste polyester-cotton fabric waste laboratory protective clothing. The treatment temperature in the hydrothermal reactor is 110℃ and the treatment time is 1 hour.

[0038] Step 2: Put the heat-treated material into 500ml of water and filter it using microporous filter paper to separate the pretreated solids;

[0039] Step 3: Wash the pretreated solid with deionized water three times, and dry the solid phase in a hot air oven to obtain the pretreated precursor.

[0040] Step 4: The dried pretreated precursor is carbonized at a medium-low temperature in a tube furnace under a nitrogen atmosphere at 5°C for 1 minute. -1 The heating rate was set at 500℃ for 2 hours, and the carbonization time was medium to low temperature. After natural cooling, a high-capacity hard carbon anode for alkali metal ion batteries was obtained.

[0041] Example 2:

[0042] A method for preparing a high-capacity hard carbon anode for alkali metal ion batteries, comprising the following steps:

[0043] Step 1: Use 60mL of 98% concentrated sulfuric acid to perform solvent heat treatment on 20g of recycled waste polyester-cotton fabric and waste laboratory protective clothing. The treatment temperature in the hydrothermal reactor is 120℃ and the treatment time is 1 hour.

[0044] Step 2: Put the heat-treated material into 500ml of water and use centrifugation to separate the solid and liquid components, thus separating the pretreated solid.

[0045] Step 3: Wash the pretreated solid with deionized water 3-5 times until the solution is neutral. Place the solid phase in a vacuum oven to dry it to obtain the pretreated precursor.

[0046] Step 4: The dried pretreated precursor is placed in a tube furnace under a nitrogen atmosphere for medium-low temperature carbonization at 5°C for 1 minute. -1 The heating rate was set at 700℃ for a medium-low temperature carbonization process, which took 2 hours. After natural cooling, a high-capacity hard carbon anode for alkali metal ion batteries was obtained.

[0047] Example 3:

[0048] A method for preparing a high-capacity hard carbon anode for alkali metal ion batteries, comprising the following steps:

[0049] Step 1: Use 30 mL of 98% concentrated sulfuric acid to perform solvent heat treatment on 20 g of recycled waste polyester-cotton fabric waste laboratory protective clothing. The treatment temperature in the hydrothermal reactor is 120℃ and the treatment time is 2 hours.

[0050] Step 2: Add the heat-treated material to 500ml of water and use sedimentation to separate the solid-phase precursor and separate the pretreated solid.

[0051] Step 3: Wash the pretreated solid with deionized water 5 times, and dry the solid phase using freeze drying to obtain the pretreated precursor;

[0052] Step 4: The dried pretreated precursor is placed in a tube furnace under an argon atmosphere for medium-low temperature carbonization at 5°C for 1 minute. -1 The heating rate was set at 500℃ for 1.5 hours, and the carbonization time was medium to low temperature. After natural cooling, a high-capacity hard carbon anode for alkali metal ion batteries was obtained.

[0053] Sodium-ion batteries were assembled using the high-capacity alkali metal ion battery hard carbon anode prepared in this embodiment as raw materials, and the battery performance was tested.

[0054] The sodium-ion battery assembly process involves mixing a high-capacity alkali metal ion battery hard carbon negative electrode, acetylene black, and PVDF polyvinylidene fluoride in a mass ratio of 7:2:1. 1g of this mixture is then mixed and stirred in 10ml of N-methylpyrrolidone (NMP) for 6 hours. The mixture is then uniformly coated onto copper foil using a casting method to a thickness of 50-200μm. Button cells are assembled in an argon-atmospheric glove box. The counter electrode is a sodium sheet, the separator is made of glass fiber, and the electrolyte is prepared by mixing 1mol of NaPF6 in a solution where EC:PC = 1:1.

[0055] The assembled sodium-ion battery underwent performance testing, and the test results are as follows: Figures 1-4 As shown, it can be observed that at 50mAg -1 At the specified current density, the battery's first-cycle discharge specific capacity is 431.94 mAh g. -1 The charging specific capacity is 254.78mAh g. -1 At 1000mA g -1 At a current density of [value missing], the capacity can reach 161.11 mAh g. -1 When the current density returns to 50 mAg -1 The capacity can reach 331.39mAh g. -1 .

[0056] Example 4:

[0057] A method for preparing a high-capacity hard carbon anode for alkali metal ion batteries, comprising the following steps:

[0058] Step 1: Use 30 mL of 98% concentrated sulfuric acid to perform solvent heat treatment on 20 g of recycled waste polyester-cotton fabric waste laboratory protective clothing. The treatment temperature in the hydrothermal reactor is 150℃ and the treatment time is 1 hour.

[0059] Step 2: Put the heat-treated material into 500ml of water and centrifuge it using a high-speed centrifuge to separate the pretreated solids;

[0060] Step 3: Wash the pretreated solid with deionized water three times, and put the solid phase into a hot air oven for drying to obtain the pretreated precursor.

[0061] Step 4: The dried pretreated precursor is placed in a tube furnace under an argon atmosphere for medium-low temperature carbonization at 5°C for 1 minute. -1 The heating rate was set at 700℃ for a medium-low temperature carbonization process, which took 2 hours. After natural cooling, a high-capacity hard carbon anode for alkali metal ion batteries was obtained.

[0062] Example 5:

[0063] A method for preparing a high-capacity hard carbon anode for alkali metal ion batteries, comprising the following steps:

[0064] Step 1: Use 50 mL of 98% concentrated sulfuric acid to perform solvent heat treatment on 20 g of recycled waste polyester-cotton fabric and waste laboratory protective clothing. The treatment temperature in the hydrothermal reactor is 130℃ and the treatment time is 1 hour.

[0065] Step 2: Put the heat-treated material into 500ml of water and filter it using a vacuum filtration flask with an aqueous microporous membrane to separate the pretreated solids.

[0066] Step 3: Wash the pretreated solid with deionized water 3 times. After the solution is washed to neutral, put the solid phase into a hot air oven for drying to obtain the pretreated precursor.

[0067] Step 4: The dried pretreated precursor is placed in a PE-CVD furnace under an argon atmosphere for medium-low temperature carbonization at 5℃ for 1 minute. -1 The heating rate was set at 700℃ for a medium-low temperature carbonization process, which took 2 hours. After natural cooling, a high-capacity hard carbon anode for alkali metal ion batteries was obtained.

[0068] Example 6:

[0069] A method for preparing a high-capacity hard carbon anode for alkali metal ion batteries, comprising the following steps:

[0070] Step 1: Use 60mL of 98% concentrated sulfuric acid to perform solvent heat treatment on 20g of recycled waste polyester-cotton fabric and waste laboratory protective clothing. The treatment temperature in the hydrothermal reactor is 120℃ and the treatment time is 1 hour.

[0071] Step 2: Put the heat-treated material into 500ml of water and centrifuge it using a high-speed centrifuge to separate the pretreated solids;

[0072] Step 3: Wash the pretreated solid with deionized water three times, and put the solid phase into a vacuum drying oven to dry it, to obtain the pretreated precursor.

[0073] Step 4: The dried pretreated precursor is placed in a tube furnace under an argon atmosphere for medium-low temperature carbonization at 5°C for 1 minute. -1 The heating rate was set at 1000℃ for 2 hours, and the carbonization time was 2 hours. After natural cooling, a high-capacity hard carbon anode for alkali metal ion batteries was obtained.

[0074] Example 7:

[0075] A method for preparing a high-capacity hard carbon anode for alkali metal ion batteries, comprising the following steps:

[0076] Step 1: Use 60mL of 98% concentrated sulfuric acid to perform solvent heat treatment on 20g of recycled waste polyester-cotton fabric and waste laboratory protective clothing. The treatment temperature in the hydrothermal reactor is 120℃ and the treatment time is 1 hour.

[0077] Step 2: Put the heat-treated material into 500ml of water and centrifuge it using a high-speed centrifuge to separate the pretreated solids;

[0078] Step 3: Wash the pretreated solid with deionized water three times, and put the solid phase into a freeze dryer to dry it to obtain the pretreated precursor.

[0079] Step 4: The dried pretreated precursor is placed in a tube furnace under an argon atmosphere for medium-low temperature carbonization at 5°C for 1 minute. -1 The heating rate was set at 700℃ for 3 hours, and the carbonization time was medium to low temperature. After natural cooling, a high-capacity hard carbon anode for alkali metal ion batteries was obtained.

[0080] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of protection claimed by the present invention. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a hard carbon anode for a high-capacity alkali metal ion battery, characterized in that, The specific steps are as follows: Step 1: Use an acidic solution to perform solvent heat treatment on the recycled waste polyester-cotton fabric and waste protective clothing. The volume-to-mass ratio of the acidic solution to the recycled waste polyester-cotton fabric and waste protective clothing is 20-100mL:20g. Step 2: Separate the pretreated solids from the heat-treated material by one or more of the following methods: vacuum filtration, centrifugation, pressure filtration, sedimentation, and decantation. Step 3: Clean the pretreated solid and then dry it using one or more of the following methods: atmospheric pressure drying, freeze drying, vacuum drying, convection drying, and conduction drying to obtain the pretreated precursor. Step 4: The dried pretreated precursor is carbonized at low and medium temperatures under an inert atmosphere, and after natural cooling, a high-capacity hard carbon anode for alkali metal ion batteries is obtained.

2. The method for preparing a high-capacity alkali metal ion battery hard carbon anode according to claim 1, characterized in that: The acidic solution in the first step is 95%-98% concentrated sulfuric acid, and the recycled waste polyester-cotton fabric and waste protective clothing are one or more of laboratory protective clothing, medical protective clothing, and cleanroom clothing.

3. The method for preparing a high-capacity alkali metal ion battery hard carbon anode according to claim 1, characterized in that: The solvent heat treatment in the first step is carried out at a temperature of 110-150℃ for 1-2 hours.

4. The method for preparing a high-capacity alkali metal ion battery hard carbon anode according to claim 1, characterized in that: The cleaning method in the third step is to rinse with deionized water 3-5 times.

5. The method for preparing a high-capacity alkali metal ion battery hard carbon anode according to claim 1, characterized in that: In the fourth step, the inert atmosphere is argon or nitrogen, and the medium-low temperature carbonization equipment is an atmosphere furnace, a tube furnace, or PE-CVD. The medium-low temperature carbonization temperature is 500-1000℃, and the heating rate is approximately 5℃ / min. -1 The carbonization time at medium and low temperatures is 1-3 hours.

6. A high-capacity alkali metal ion battery hard carbon anode prepared by any one of the preparation methods described in claims 1-5.

7. The application of a high-capacity alkali metal ion battery hard carbon anode prepared by any one of claims 1-5 in lithium-ion, sodium-ion or potassium-ion batteries.

8. The application according to claim 7, characterized in that: The lithium-ion battery assembly process involves mixing a high-capacity alkali metal ion battery hard carbon negative electrode, acetylene black, and PVDF polyvinylidene fluoride in a mass ratio of 7:2:1, and then mixing 1g of the mixture in 10ml of N-methylpyrrolidone (NMP) for 6 hours. The mixture is then uniformly coated onto copper foil using a casting method with a thickness of 50-200μm using a spatula. Button batteries are assembled in an argon atmosphere glove box. The counter electrode is a lithium sheet, the separator is made of PP material, and the electrolyte is prepared by mixing 1mol of LiPF6 in a solution of EC:DMC:EMC = 1:1:

1.

9. The application according to claim 7, characterized in that: The sodium-ion battery assembly process involves mixing a high-capacity alkali metal ion battery hard carbon negative electrode, acetylene black, and PVDF polyvinylidene fluoride in a mass ratio of 7:2:1, and then mixing 1g of the mixture in 10ml of N-methylpyrrolidone (NMP) for 6 hours. The mixture is then uniformly coated onto copper foil using a casting method with a thickness of 50-200μm using a spatula. Button batteries are assembled in an argon atmosphere glove box. The counter electrode is a sodium sheet, the separator is made of glass fiber, and the electrolyte is prepared by mixing 1mol of NaPF6 in a solution of EC:PC = 1:

1.

10. The application according to claim 7, characterized in that: The potassium-ion battery assembly process involves mixing a high-capacity alkali metal ion battery hard carbon negative electrode, acetylene black, and PVDF polyvinylidene fluoride in a mass ratio of 7:2:1, and then mixing 1g of the mixture in 10ml of N-methylpyrrolidone (NMP) for 6 hours. The mixture is then uniformly coated onto copper foil using a casting method with a thickness of 50-200μm using a spatula. Button batteries are then assembled in an argon atmosphere glove box. The counter electrode is a potassium sheet, the separator is made of glass fiber, and the electrolyte is prepared by mixing 5mol of KFSI in a solution of DIGLYME.

Images