Potassium ion battery negative electrode material and preparation method thereof

Abstract

The application belongs to the technical field of battery materials, and particularly relates to a potassium ion battery negative electrode material and a preparation method thereof. The preparation method of the potassium ion battery negative electrode material has the advantages of simple process, short production period, low cost, strong repeatability, important reference for synthesis and control of carbon nanomaterials, unique pea pod morphology, small volume expansion, stable structure, high volume energy density, realization of oxygen and nitrogen double-doped carbon, enhanced electronic conductivity, short-range disordered hard carbon structure accompanied by nanocrystalline domains, less ion intercalation in the battery cycle process, high capacitance contribution, excellent cycle and rate performance, and wide application prospect in energy storage and catalysis and the like.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of battery materials, in particular to a potassium ion battery negative electrode material and a preparation method thereof, more particularly to a potassium ion battery negative electrode material of nitrogen and oxygen double-doped carbon nanotubes derived from sugarcane residue and a preparation method thereof. BACKGROUND

[0002] With the increasing demand for environmental protection and sustainable energy storage systems, there is an urgent need to develop promising rechargeable battery technologies to meet the needs of large-scale power grids and electric vehicles. Since 1991, although lithium-ion batteries have been successfully commercialized, the limited lithium reserves and high cost still limit the large-scale application of lithium-ion batteries. Sodium-ion batteries and potassium-ion batteries have attracted more and more attention due to the abundant natural resources of sodium and potassium and the low cost of raw materials. Compared with sodium-ion batteries, potassium-ion batteries are more attractive because of their lower standard redox potential, higher operating voltage and energy density. However, the large potassium ion radius causes slow kinetics during repeated charge / discharge processes, and the electrode material also suffers from huge volume expansion. Therefore, there is an urgent need to develop a potassium-ion negative electrode material with excellent performance.

[0003] Carbonaceous materials have always played a crucial role in the development of potassium-ion anodes. Potassium ions can be intercalated into graphite anodes to form graphite intercalation compounds (KC8), with a theoretical specific capacity of 279 mAh g -1 . However, the large interlayer spacing expansion causes poor rate performance and cycle stability. Therefore, various disordered or amorphous carbon-based materials, including nitrogen-doped carbon nanofibers, nanotubes, hollow carbon nanospheres, mesoporous carbon octahedra, carbon nanofiber foams, and other carbon composites have been extensively studied, considering that such materials are beneficial to potassium ion intercalation and exhibit excellent performance. However, there is still a huge space for the energy density and stability of potassium-ion batteries. Energy density and cycle performance are jointly determined by the ion / electron migration rate and interlayer spacing change in the electrode. Nanostructure engineering as an effective strategy has received extensive attention in recent years. The hollow structure of hard carbon can buffer the large volume change during potassium ion intercalation and deintercalation, increase the contact area between the electrode and the liquid electrolyte, and shorten the diffusion length of K + migration. In addition, heteroatom (N, O, S and P) doping strategies have also been proven to be effective in improving the electronic conductivity of hard carbon, in addition to the intercalation process, which helps fast and efficient potassium ion adsorption storage. The synergistic storage mechanism of intercalated / adsorbed potassium is beneficial to improving the rate performance through improved reaction kinetics. However, most of the synthesized carbon nanotubes have good crystalline phase with obvious lattice stripes, and often dominate the potassium ion intercalation mechanism, which brings about large volume expansion and structure collapse, resulting in poor rate performance and low energy density. SUMMARY

[0004] To solve the problems in the prior art, the main purpose of the present application is to provide a potassium ion battery negative electrode material and a preparation method thereof, which has important significance for the development of carbon-based materials applied to potassium ion batteries, and also provides a new method and new idea for the low-cost preparation of carbon-based materials.

[0005] To solve the above technical problems, according to one aspect of the present application, the present application provides the following technical solution:

[0006] A potassium ion battery negative electrode material, which is nitrogen and oxygen double-doped carbon nanotubes derived from sugarcane residue.

[0007] As a preferred scheme of the potassium ion battery negative electrode material according to the present application, the nitrogen and oxygen double-doped carbon nanotubes derived from sugarcane residue have a pea pod shell-shaped morphology and an amorphous structure with heteroatom doping, and a diameter of 15-30 nm.

[0008] To solve the above technical problems, according to one aspect of the present application, the present application provides the following technical solution:

[0009] A preparation method of the potassium ion battery negative electrode material described above, comprising the following steps:

[0010] S1. Sugarcane residue is added to a container containing anhydrous ethanol and then placed in an ultrasonic device for ultrasonic treatment, and after ultrasonic treatment, dried in an oven;

[0011] S2. The dried sugarcane residue and ferric chloride hexahydrate are added to a container containing deionized water and stirred;

[0012] S3. After stirring is completed, the container is placed in a heating device and heated to a target temperature and kept at the target temperature;

[0013] S4. After the solution in the container is cooled to room temperature, it is washed, centrifuged, and dried to obtain a yellow turbid substance;

[0014] S5. The yellow turbid substance is placed in a crucible, and then the crucible is placed in a tube furnace and sintered in an inert protective atmosphere. After the tube furnace is cooled to room temperature, the black product is collected;

[0015] S6. The black product is added to a centrifuge tube containing hydrochloric acid and ultrasonically dispersed;

[0016] S7. After ultrasonic dispersion, washing, centrifuging, and vacuum drying, the potassium ion battery negative electrode material is obtained.

[0017] As a preferred scheme of the preparation method of the potassium ion battery negative electrode material, in the step S1, the ultrasonic treatment time is 30-60 min, the drying temperature is 70-75 DEG C, and the drying time is 10-15 h.

[0018] As a preferred scheme of the preparation method of the potassium ion battery negative electrode material, in the step S2, the stirring time is 14-18 h, the mass ratio of the bagasse to the ferric chloride hexahydrate is 1:4-12, and the solid-liquid ratio of the bagasse to the deionized water is 1 g:(100-120) mL.

[0019] As a preferred scheme of the preparation method of the potassium ion battery negative electrode material, in the step S3, the heating is performed at a heating rate of 5-7 DEG C / min to 90-120 DEG C, and the temperature is kept for 24-36 h.

[0020] As a preferred scheme of the preparation method of the potassium ion battery negative electrode material, in the step S4, the drying temperature is 65-70 DEG C, and the drying time is 10-15 h.

[0021] As a preferred scheme of the preparation method of the potassium ion battery negative electrode material, in the step S5, the sintering is performed at a heating rate of 3-5 DEG C / min to 800-900 DEG C, and the temperature is kept for 2-3 h; the inert protective atmosphere is high-purity nitrogen or high-purity argon.

[0022] As a preferred scheme of the preparation method of the potassium ion battery negative electrode material, in the step S6, the hydrochloric acid concentration is 4.0-8.0 wt%, the ultrasonic dispersion time is 10-30 min, and the solid-liquid ratio of the black product to the hydrochloric acid is (1-2) g:1 L.

[0023] As a preferred scheme of the preparation method of the potassium ion battery negative electrode material, in the step S7, the centrifugal rotation speed is 9000-12000 r / min, the centrifugal time is 3-5 min, the vacuum drying temperature is 70-75 DEG C, and the vacuum drying time is 10-15 h.

[0024] To solve the above technical problems, according to another aspect of the present application, the present application provides the following technical scheme:

[0025] A potassium ion battery negative electrode comprises the potassium ion battery negative electrode material.

[0026] A preparation method of a potassium ion battery negative electrode comprises mixing and grinding a certain amount of potassium ion battery negative electrode material and polyvinylidene fluoride, adding a certain amount of N-methylpyrrolidone to liquid which can just completely wet the powder, stirring, and uniformly coating the slurry on a copper foil, and vacuum drying to obtain the potassium ion battery negative electrode.

[0027] A potassium ion battery comprising the potassium ion battery anode described above.

[0028] The beneficial effects of the present application are as follows:

[0029] The present application provides a potassium ion battery anode material and a preparation method thereof, and has the advantages that the preparation method of the potassium ion battery anode material is simple, the production cycle is short, the cost is low, the repeatability is strong, the synthesis and control of carbon nanomaterials have important reference value, the unique pea pod morphology, small volume expansion, stable structure, and high volume energy density are achieved, oxygen and nitrogen doped carbon is realized, the electronic conductivity is enhanced, the short-range disordered hard carbon structure is accompanied by nanocrystalline domains, the ion intercalation in the battery cycle is small, the capacitance contribution is high, excellent cycle and rate performance are achieved, and the potassium ion battery anode material has wide application prospects in the fields of energy storage and catalysis. BRIEF DESCRIPTION OF DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained according to the structures shown in the drawings without creative labor for those skilled in the art.

[0031] Figure 1 The XRD graph of the potassium ion battery anode material of the present application embodiment 1;

[0032] Figure 2 The FESEM graph of the potassium ion battery anode material of the present application embodiment 1;

[0033] Figure 3 The TEM graph of the potassium ion battery anode material of the present application embodiment 1;

[0034] Figure 4 The XPS-N1s graph of the potassium ion battery anode material of the present application embodiment 1;

[0035] Figure 5 The XPS-O1s graph of the potassium ion battery anode material of the present application embodiment 1;

[0036] Figure 6 The cycle curve of the potassium ion battery anode prepared from the potassium ion battery anode material of the present application embodiment 1;

[0037] Figure 7 The rate performance of the potassium ion battery anode prepared from the potassium ion battery anode material of the present application embodiment 1.

[0038] The objectives, functional characteristics and advantages of the present application will be further described with reference to the embodiments and the accompanying drawings. DETAILED DESCRIPTION

[0039] The technical solutions in the embodiments will be clearly and completely described below, obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative work belong to the protection scope of the present application.

[0040] The present application provides a kind of potassium ion battery negative material and its preparation method, potassium ion battery negative material structure is stable, volume expansion is small, capacity is large, with high volume energy density, short-range disordered hard carbon structure, also has the following advantages:

[0041] 1) method is simple and easy to operate, low cost, realizes the circulation of biomass carbon, sugarcane residue derived nitrogen and oxygen double-doped carbon nanotube potassium ion battery negative material morphology keeps well, has guiding significance to the synthesis control of other related carbon materials.

[0042] 2) using the element attribute of sugarcane residue, in situ realizes oxygen and nitrogen double-doped carbon, enhances electronic conductivity, so that the battery has fast transfer kinetics.

[0043] 3) the carbon nanotube prepared has pea pod morphology, volume expansion is small, structure is stable, and has high volume energy density.

[0044] 4) the carbon nanotube has short-range disordered hard carbon structure, accompanied by nanocrystalline domain, ion insertion is less in the battery cycle process, and the capacity contribution is high, so it is used for the negative electrode of potassium ion battery and has high capacity, excellent cycle and rate performance.

[0045] According to one aspect of the present application, the present application provides the following technical solutions:

[0046] A kind of potassium ion battery negative material, the potassium ion battery negative material is derived from nitrogen and oxygen double-doped carbon nanotube using sugarcane residue;The nitrogen and oxygen double-doped carbon nanotube derived from sugarcane residue has pea pod shell morphology and heteroatom doped amorphous structure, and the diameter is 15-30nm.Specifically, the diameter of carbon nanotube can be, for example, but not limited to, any one of 15nm, 20nm, 25nm, 30nm or a range between any two of them;

[0047] According to one aspect of the present application, the present application provides the following technical solutions:

[0048] A kind of preparation method of the above-mentioned potassium ion battery negative material, comprising the following steps:

[0049] S1. Put the bagasse into a container containing anhydrous ethanol, and then place the container in an ultrasonic device for ultrasonic treatment, and then dry the bagasse in an oven;

[0050] S2. Put the dried bagasse and ferric chloride hexahydrate into a container containing deionized water, and then stir the mixture;

[0051] S3. After the stirring is completed, place the container in a heating device, heat the container to a target temperature, and then keep the container at the target temperature;

[0052] S4. After the solution in the container is cooled to room temperature, wash, centrifuge, and dry the solution to obtain a yellow turbid substance;

[0053] S5. Put the yellow turbid substance into a crucible, and then place the crucible in a tube furnace to sinter the yellow turbid substance in an inert protective atmosphere, and then collect a black product after the tube furnace is cooled to room temperature;

[0054] S6. Put the black product into a centrifuge tube containing hydrochloric acid, and then ultrasonically disperse the black product;

[0055] S7. After the ultrasonic dispersion is completed, wash, centrifuge, and vacuum dry the black product to obtain a potassium ion battery anode material.

[0056] Preferably, in the step S1, the ultrasonic treatment time is 30-60 min, the drying temperature is 70-75℃, and the drying time is 10-15 h. Specifically, the ultrasonic treatment time can be, for example but not limited to, any one of 30 min, 40 min, 50 min, 60 min, or a range between any two of them; the drying temperature can be, for example but not limited to, any one of 70℃, 71℃, 72℃, 73℃, 74℃, 75℃, or a range between any two of them; and the drying time can be, for example but not limited to, any one of 10 h, 11 h, 12 h, 13 h, 14 h, 15 h, or a range between any two of them.

[0057] Preferably, in the step S2, the stirring adopts an electromagnetic stirring process, the stirring time is 14-18 h, the mass ratio of the bagasse to the ferric chloride hexahydrate is 1:4-12, and the solid-liquid ratio of the bagasse to the deionized water is 1 g:(100-120) mL. Specifically, the stirring time can be, for example but not limited to, any one of 14 h, 15 h, 16 h, 17 h, 18 h, or a range between any two of them; the mass ratio of the bagasse to the ferric chloride hexahydrate can be, for example but not limited to, any one of 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 1:11, 1:12, or a range between any two of them; and the solid-liquid ratio of the bagasse to the deionized water can be, for example but not limited to, any one of 1 g:100 mL, 1 g:105 mL, 1 g:110 mL, 1 g:115 mL, 1 g:120 mL, or a range between any two of them.

[0058] Preferably, in the step S3, the heating device is a heating jacket with electromagnetic stirring function; heating is performed at a heating rate of 5-7°C / min to 90-120°C, and holding for 24-36h. Specifically, the heating rate can be, for example but not limited to, any one of 5°C / min, 6°C / min, 7°C / min, or a range between any two of them; the heating temperature can be, for example but not limited to, any one of 90°C, 100°C, 110°C, 120°C, or a range between any two of them; the holding time can be, for example but not limited to, any one of 24h, 28h, 32h, 36h, or a range between any two of them;

[0059] Preferably, in the step S4, the drying temperature is 65-70°C, and the drying time is 10-15h. The drying temperature can be, for example but not limited to, any one of 65°C, 66°C, 67°C, 68°C, 69°C, 70°C, or a range between any two of them; the drying time can be, for example but not limited to, any one of 10h, 11h, 12h, 13h, 14h, 15h, or a range between any two of them;

[0060] Preferably, in the step S5, sintering is performed at a heating rate of 3-5°C / min to 800-900°C, and holding for 2-3h; the inert protective atmosphere is high-purity nitrogen or high-purity argon. Specifically, the heating rate can be, for example but not limited to, any one of 3°C / min, 4°C / min, 5°C / min, or a range between any two of them; the sintering temperature can be, for example but not limited to, any one of 800°C, 810°C, 820°C, 830°C, 840°C, 850°C, 860°C, 870°C, 880°C, 890°C, 900°C, or a range between any two of them; the holding time can be, for example but not limited to, any one of 2h, 2h15min, 2h30min, 2h45min, 3h, or a range between any two of them;

[0061] Preferably, in the step S6, the concentration of hydrochloric acid is 4.0-8.0wt%, the ultrasonic dispersion time is 10-30min, and the solid-liquid ratio of the black product to hydrochloric acid is (1-2)g:1L. The concentration of hydrochloric acid can be, for example but not limited to, any one of 4.0wt%, 5.0wt%, 6.0wt%, 7.0wt%, 8.0wt%, or a range between any two of them; the ultrasonic dispersion time can be, for example but not limited to, any one of 10min, 15min, 20min, 25min, 30min, or a range between any two of them; the solid-liquid ratio of the black product to hydrochloric acid can be, for example but not limited to, any one of 1g:1L, 1.1g:1L, 1.2g:1L, 1.3g:1L, 1.4g:1L, 1.5g:1L, 1.6g:1L, 1.7g:1L, 1.8g:1L, 1.9g:1L, 2g:1L, or a range between any two of them;

[0062] Preferably, in the step S7, the centrifugal rotation speed is 9000-12000r / min, the centrifugal time is 3-5min, the vacuum drying temperature is 70-75℃, and the vacuum drying time is 10-15h. Specifically, the centrifugal rotation speed can be, for example but not limited to, any one of 9000r / min, 9500r / min, 10000r / min, 10500r / min, 11000r / min, 11500r / min, 12000r / min, or a range between any two of them; the centrifugal time can be, for example but not limited to, any one of 3min, 4min, 5min, or a range between any two of them; the vacuum drying temperature can be, for example but not limited to, any one of 70℃, 71℃, 72℃, 73℃, 74℃, 75℃, or a range between any two of them; the vacuum drying time can be, for example but not limited to, any one of 10h, 11h, 12h, 13h, 14h, 15h, or a range between any two of them;

[0063] According to another aspect of the present application, the present application provides the following technical solutions:

[0064] A potassium ion battery cathode material, comprising the potassium ion battery cathode material described above.

[0065] A preparation method of a potassium ion battery cathode, comprising the following steps: mixing and grinding a certain amount of potassium ion battery cathode material and polyvinylidene fluoride to be uniform, adding a certain amount of N-methyl pyrrolidone to liquid to just completely wet the powder, uniformly coating the slurry on a copper foil after stirring, and vacuum drying to obtain the potassium ion battery cathode.

[0066] A potassium ion battery, comprising the potassium ion battery cathode described above.

[0067] The technical solutions of the present application are further described below in combination with specific embodiments.

[0068] Example 1

[0069] A preparation method of a potassium ion battery negative electrode material, comprising the following steps:

[0070] S1. Sugarcane residue is added into a container containing anhydrous ethanol and then placed in an ultrasonic device for ultrasonic treatment for 30 min, and then dried in an oven; the drying temperature is 70℃, and the drying time is 12h;

[0071] S2. 1g of the dried sugarcane residue and 12g of iron chloride hexahydrate are added into a container containing 100mL of deionized water for electromagnetic stirring for 14h;

[0072] S3. After stirring is completed, the container is placed in a heating jacket with electromagnetic stirring function, heated to 90℃ at a heating rate of 5℃ / min, and kept for 24h;

[0073] S4. After the solution in the container is cooled to room temperature, it is washed with anhydrous ethanol and centrifuged 4 times, and then dried at 70℃ for 12h to obtain a yellow turbid substance;

[0074] S5. The yellow turbid substance is placed in a crucible, and then the crucible is placed in a tube furnace and sintered at a heating rate of 5℃ / min to 800℃ in a high-purity argon atmosphere, kept for 2h, and then the black product is collected after the tube furnace is cooled to room temperature;

[0075] S6. 30mg of the black product is added into a centrifuge tube containing 30mL of 5.0wt% hydrochloric acid for ultrasonic dispersion for 10min;

[0076] S7. After ultrasonic dispersion, it is washed with anhydrous ethanol and centrifuged 5 times at a speed of 10000r / min for 4min, and then vacuum dried at 70℃ for 12h to obtain a nitrogen and oxygen double-doped carbon nanotube potassium ion battery negative electrode material, the XRD pattern of the potassium ion battery negative electrode material is shown in Figure 1 , two broad and weak characteristic diffraction peaks can be observed, centered at 22.5°(002) and 43°(101), which means that the negative electrode material has a highly disordered defective carbon structure; the FESEM and TEM images of the potassium ion battery negative electrode material are shown in Figures 2-3 , which are uniformly arranged with small carbon nanotubes with openings upward, having a clear pea pod morphology, and the diameter is 15-30nm; the XPS-N1s and XPS-O1s images of the potassium ion battery negative electrode material are shown in Figures 4-5 , the existence of peaks in the figure indicates that N and O atoms are successfully doped in the carbon nanotube matrix.

[0077] Example 2

[0078] A preparation method of a potassium ion battery negative electrode material, comprising the following steps:

[0079] S1. The bagasse is added to a container containing anhydrous ethanol and then placed in an ultrasonic device for ultrasonic treatment for 60 min. After ultrasonic treatment, the bagasse is dried in an oven; the drying temperature is 75 DEG C, and the drying time is 10 h;

[0080] S2. 1 g of the dried bagasse and 4 g of ferric chloride hexahydrate are added to a container containing 120 mL of deionized water and subjected to electromagnetic stirring for 18 h;

[0081] S3. After stirring is completed, the container is placed in a heating jacket with electromagnetic stirring function, heated to 120 DEG C at a heating rate of 7 DEG C / min, and kept for 36 h;

[0082] S4. After the solution in the container is cooled to room temperature, it is washed with anhydrous ethanol and centrifuged 3 times, and then dried at 65 DEG C for 15 h to obtain a yellow turbid substance;

[0083] S5. The yellow turbid substance is placed in a crucible, which is then placed in a tube furnace and sintered at a heating rate of 3 DEG C / min to 900 DEG C in a high-purity nitrogen atmosphere, and kept for 3 h. After the tube furnace is cooled to room temperature, a black product is collected;

[0084] S6. 30 mg of the black product is added to a centrifuge tube containing 60 mL of 8.0 wt% hydrochloric acid and subjected to ultrasonic dispersion for 30 min;

[0085] After ultrasonic dispersion, the product is washed with anhydrous ethanol and centrifuged 5 times at a speed of 9000 r / min for 5 min, and then vacuum dried at 75 DEG C for 15 h to obtain a nitrogen-oxygen co-doped carbon nanotube potassium ion battery negative electrode material.

[0086] Example 3

[0087] A preparation method of a potassium ion battery negative electrode material, comprising the following steps:

[0088] S1. The bagasse is added to a container containing anhydrous ethanol and then placed in an ultrasonic device for ultrasonic treatment for 60 min. After ultrasonic treatment, the bagasse is dried in an oven; the drying temperature is 75 DEG C, and the drying time is 10 h;

[0089] S2. 1 g of the dried bagasse and 4 g of ferric chloride hexahydrate are added to a container containing 120 mL of deionized water and subjected to electromagnetic stirring for 18 h;

[0090] S3. After stirring is completed, the container is placed in a heating jacket with electromagnetic stirring function, heated to 120 DEG C at a heating rate of 7 DEG C / min, and kept for 36 h;

[0091] S4. After the solution in the container is cooled to room temperature, it is washed with anhydrous ethanol and centrifuged 4 times, and then dried at 70°C for 12h to obtain a yellow turbid substance;

[0092] S5. The yellow turbid substance is placed in a crucible, and then the crucible is placed in a tube furnace and sintered at 800°C at a heating rate of 5°C / min in a high-purity argon atmosphere, and then kept for 2h. After the tube furnace is cooled to room temperature, the black product is collected;

[0093] S6. 30mg of the black product is added to a centrifuge tube containing 30mL of hydrochloric acid with a concentration of 5.0wt% and ultrasonically dispersed for 10min;

[0094] S7. After ultrasonic dispersion, it is washed with anhydrous ethanol and centrifuged 5 times at a speed of 12000r / min for 3min, and then dried at 70°C under vacuum for 12h to obtain a nitrogen-oxygen co-doped carbon nanotube potassium ion battery negative electrode material.

[0095] Example 4

[0096] A method for preparing a potassium ion battery negative electrode material, comprising the following steps:

[0097] S1. Sugarcane residue is added to a container containing anhydrous ethanol and then placed in an ultrasonic device for ultrasonic treatment for 30min. After ultrasonic treatment, it is dried in an oven; the drying temperature is 70°C, and the drying time is 12h;

[0098] S2. 1g of the dried sugarcane residue and 12g of iron chloride hexahydrate are added to a container containing 100mL of deionized water and subjected to electromagnetic stirring for 14h;

[0099] S3. After stirring is completed, the container is placed in a heating jacket with electromagnetic stirring function and heated to 90°C at a heating rate of 5°C / min, and then kept for 24h;

[0100] S4. After the solution in the container is cooled to room temperature, it is washed with anhydrous ethanol and centrifuged 4 times, and then dried at 70°C for 12h to obtain a yellow turbid substance;

[0101] S5. The yellow turbid substance is placed in a crucible, and then the crucible is placed in a tube furnace and sintered at 800°C at a heating rate of 5°C / min in a high-purity argon atmosphere, and then kept for 2h. After the tube furnace is cooled to room temperature, the black product is collected;

[0102] S6. 30mg of the black product is added to a centrifuge tube containing 30mL of hydrochloric acid with a concentration of 4.0wt% and ultrasonically dispersed for 10min;

[0103] S7. After ultrasonic dispersion, the potassium ion battery negative electrode material doped with nitrogen and oxygen was obtained by washing with anhydrous ethanol, centrifugation for 5 times at a speed of 10,000 r / min for 4 min, and vacuum drying at 70 DEG C for 12 h.

[0104] 90wt% of the potassium ion battery negative electrode material prepared in the example and 10wt% of polyvinylidene fluoride binder were mixed and ground uniformly, a certain amount of N-methyl pyrrolidone was added to the liquid to just completely wet the powder, the slurry was uniformly coated on the copper foil after stirring for 10 h, vacuum drying at 80 DEG C for 15 h, and the negative electrode sheet with a diameter of 10 mm was prepared by the punching machine. In the glove box filled with argon, the negative electrode sheet, the carbonate electrolyte, the potassium sheet positive electrode, the CR2032 button cell shell and the glass fiber type separator material were assembled into a button cell. Finally, the electrochemical performance test of the negative electrode material was carried out in the voltage range of 0.01-2.5 V. The cycle curve of the potassium ion battery negative electrode at a current density of 50 mAg -1 Figure 6 -1 The coulombic efficiency was close to 100%. The rate performance under different current densities was shown in Figure 7 The high specific capacity of 768, 627, 517, 443, 383 and 288 mAh g -1 was shown under the current densities of 50, 100, 200, 500, 1000 and 2000 mAg -1 , respectively. Even under a high current density of 3000 mAg -1 , a high specific capacity of 241 mAh g -1 was still obtained, and when the current density returned to 50 mAg -1 from 3000 mAg -1 , a high specific capacity of 734 mAh g -1 was obtained.

[0105] The potassium ion battery negative electrode material prepared by the method has the advantages of simple process, short production cycle, low cost and strong repeatability, and has an important reference role in the synthesis and control of carbon nanomaterials. It has a unique pea pod shape, small volume expansion, stable structure and high volume energy density. The oxygen and nitrogen doped carbon enhances the electronic conductivity, and the short-range ordered hard carbon structure is accompanied by nanocrystalline domains, so that the ion insertion is small during the battery cycle, the capacitance contribution is high, excellent cycle and rate performance are obtained, and the method also has a wide application prospect in the fields of energy storage and catalysis.

[0106] ​​The above merely describes the preferred embodiments of the present application, and is not intended to limit the patent scope of the present application. Any equivalent structural variations or direct / indirect applications in other related technical fields based on the content of the present application description are included in the patent protection scope of the present application.

Claims

1. A potassium-ion battery anode material, characterized in that, The potassium ion battery negative electrode material is nitrogen and oxygen double-doped carbon nanotubes derived from sugarcane residue; the nitrogen and oxygen double-doped carbon nanotubes derived from sugarcane residue have a pea pod shell shape and an amorphous structure doped with nitrogen and oxygen, and a diameter of 15-30 nm. The preparation method of the potassium ion battery negative electrode material is characterized in that it comprises the following steps: S1. Sugarcane residue is added to a container containing anhydrous ethanol, and then placed in an ultrasonic device for ultrasonic treatment, and dried in an oven after ultrasonic treatment; S2. The dried sugarcane residue and ferric chloride hexahydrate are added to a container containing deionized water for stirring; S3. After stirring is completed, the container is placed in a heating device and heated to a target temperature and kept at the target temperature; S4. After the solution in the container is cooled to room temperature, it is washed, centrifuged, and dried to obtain a yellow turbid substance; S5. The yellow turbid substance is placed in a crucible, and then the crucible is placed in a tube furnace for sintering in an inert protective atmosphere; after the tube furnace is cooled to room temperature, the black product is collected; S6. The black product is added to a centrifuge tube containing hydrochloric acid for ultrasonic dispersion; S7. After ultrasonic dispersion, washing, centrifugation, and vacuum drying, the potassium ion battery negative electrode material is obtained.

2. A method of producing the potassium-ion battery anode material of claim 1, characterized in that, The preparation method comprises the following steps: S1. Sugarcane residue is added to a container containing anhydrous ethanol, and then placed in an ultrasonic device for ultrasonic treatment, and dried in an oven after ultrasonic treatment; S2. The dried sugarcane residue and ferric chloride hexahydrate are added to a container containing deionized water for stirring; S3. After stirring is completed, the container is placed in a heating device and heated to a target temperature and kept at the target temperature; S4. After the solution in the container is cooled to room temperature, it is washed, centrifuged, and dried to obtain a yellow turbid substance; S5. The yellow turbid substance is placed in a crucible, and then the crucible is placed in a tube furnace for sintering in an inert protective atmosphere; after the tube furnace is cooled to room temperature, the black product is collected; S6. The black product is added to a centrifuge tube containing hydrochloric acid for ultrasonic dispersion; S7. After ultrasonic dispersion, washing, centrifugation, and vacuum drying, the potassium ion battery negative electrode material is obtained.

3. The method for preparing the potassium-ion battery anode material according to claim 2, characterized in that, In step S2, the mass ratio of sugarcane residue to ferric chloride hexahydrate is 1:4-12.

4. The method for preparing the potassium-ion battery anode material according to claim 2, characterized in that, In step S3, heating is performed at a heating rate of 5-7 ℃ / min to 90-120 ℃, and the temperature is kept for 24-36 h.

5. The method of claim 2, wherein the method further comprises the step of: In step S5, sintering is performed at a heating rate of 3-5 ℃ / min to 800-900 ℃, and the temperature is kept for 2-3 h; the inert protective atmosphere is high-purity nitrogen or high-purity argon. ​ 6. The method of claim 2, wherein the method further comprises: In step S6, the concentration of hydrochloric acid is 4.0-8.0 wt%, the ultrasonic dispersion time is 10-30 min, and the solid-liquid ratio of black product to hydrochloric acid is (1-2) g:1 L.

7. The method of claim 2, wherein the method further comprises the step of: In step S7, the centrifugal speed is 9000-12000 r / min, the centrifugal time is 3-5 min, the vacuum drying temperature is 70-75 ℃, and the vacuum drying time is 10-15 h.

8. A potassium-ion battery anode, characterized in that, The potassium ion battery negative electrode material comprises the potassium ion battery negative electrode material of claim 1 or the potassium ion battery negative electrode material prepared by the preparation method of any one of claims 2-7.

9. A potassium-ion battery, characterized in that, The potassium ion battery negative electrode comprises the potassium ion battery negative electrode of claim 8.

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