High-performance saccharide biomass hard carbon negative electrode material as well as preparation method and application thereof

Abstract

The invention relates to the technical field of sodium ion batteries, in particular to a high-performance saccharide biomass hard carbon negative electrode material, a preparation method and application thereof. A preparation method of a high-performance carbohydrate biomass hard carbon negative electrode material comprises the following steps: S1, uniformly mixing sucrose and starch according to a certain mass ratio, adding zinc gluconate powder, uniformly mixing, and performing anaerobic treatment on the mixed powder to obtain brown powder; s2, sequentially calcining, cooling, crushing and sieving the brown powder to obtain an intermediate product; and S3, calcining the intermediate product in an inert gas atmosphere, cooling, and screening to obtain the high-performance saccharide biomass hard carbon negative electrode material. According to the preparation method, conventional saccharide biomass is adopted as a precursor, raw materials are wide in source and low in price, no solvent or cross-linking agent or the like is used, and the preparation method has the obvious advantage of being low in production cost.

Description

Technical Field

[0001] The present invention relates to the technical field of sodium-ion batteries, and particularly to a high-performance carbohydrate biomass hard carbon negative electrode material, a preparation method thereof, and an application thereof. Background Art

[0002] With the rapid development of the new energy vehicle industry, the demand for lithium-ion batteries has increased sharply. However, due to resource limitations, their cost remains high. Against this background, sodium-ion batteries with both low cost and high safety have become a research hotspot. However, the commercialization process of sodium-ion batteries still faces many challenges, and one of the most critical issues is the lack of high-performance and low-cost negative electrode materials.

[0003] Hard carbon materials are considered to be one of the most promising negative electrode materials for sodium-ion batteries in practical applications due to their excellent structural stability, good electrical conductivity, and high capacity. Biomass, as a renewable resource with a wide range of sources and low prices, is the first choice for preparing hard carbon materials. Among them, carbohydrate biomass (such as glucose, sucrose, starch, etc.) as a hard carbon precursor not only has rich resources and low costs, but also belongs to extracts, with many outstanding advantages such as low ash content, few impurities, and good consistency, which has attracted great attention. However, it should be noted that carbohydrate biomass is prone to gas evolution and violent volume expansion when heated, which not only results in a low carbon yield, but also often makes the physicochemical properties of the material less than ideal, leading to the electrochemical performance being difficult to meet the requirements of practical applications. On the other hand, the hard carbon negative electrode materials directly obtained by carbonizing carbohydrate biomass usually have fewer closed pores and poor sodium storage capacity on the plateau, and the overall reversible specific capacity is generally at a relatively low level of 200-250 mAh / g. Therefore, developing high-performance carbohydrate biomass hard carbon materials with low cost, rich closed pores, good physicochemical properties, and outstanding sodium storage capacity and the corresponding preparation processes is of great significance for the large-scale promotion of sodium-ion batteries. Summary of the Invention

[0004] Aiming at the problems existing in the prior art, the present invention provides a high-performance carbohydrate biomass hard carbon negative electrode material, a preparation method thereof, and an application thereof. This method selects carbohydrate biomass with easily available raw materials and good consistency as the precursor, and based on the dehydration cross-linking effect between sucrose and starch under optimized conditions, overcomes the problem that carbohydrate biomass is prone to expansion when heated without using any solvents and cross-linking agents. And by adding a small amount of zinc gluconate, rich closed pores are successfully constructed inside the material, and finally a hard carbon negative electrode material with excellent physicochemical properties and electrochemical performance is obtained. The preparation method disclosed in the present invention has the advantages of simple process, low cost, environmental friendliness, etc. The prepared hard carbon material has a high yield and combines high specific capacity, high initial efficiency, and excellent rate and cycle performance, and has broad application prospects in the field of sodium-ion batteries.

[0005] The present invention provides a method for preparing a high-performance carbohydrate biomass hard carbon negative electrode material, comprising the following steps: S1. After uniformly mixing sucrose and starch according to a certain mass ratio, zinc gluconate powder is added and uniformly mixed. After subjecting the mixed powder to an anaerobic treatment, a brown powder is obtained; S2. After successively subjecting the brown powder to calcination, cooling, pulverization, and sieving treatments, an intermediate product is obtained; S3. After subjecting the intermediate product to a calcination treatment in an inert gas atmosphere, it is cooled and sieved to obtain a high-performance carbohydrate biomass hard carbon negative electrode material.

[0006] Further, in step S1, the starch is one or more of corn starch, wheat starch, and rice starch.

[0007] Further, in step S1, based on the mass ratio, sucrose:starch = 10:1 to 1:10; The addition amount of zinc gluconate powder is 1% to 30% of the total mass of sucrose and starch.

[0008] Further, in step S1, the anaerobic treatment step is: subjecting the mixed powder to an anaerobic treatment in an inert gas atmosphere; wherein, the inert gas is nitrogen or argon; The temperature condition for the anaerobic treatment is 160 to 280 °C, and the time condition is 1 to 10 h.

[0009] Further, in step S2, the calcination is carried out in an inert gas atmosphere, the inert gas is nitrogen or argon, the calcination temperature is 600 to 1000 °C, the heating rate is 3 °C / min, and the calcination time is 0.5 to 2 h.

[0010] Further, in step S2, after pulverization, it is sieved through a 100 to 600 mesh sieve.

[0011] Further, in step S3, the inert gas is nitrogen or argon, the calcination temperature is 1000 to 1800 °C, the heating rate is 3 °C / min, and the calcination time is 2 to 5 h.

[0012] Further, in step S3, after cooling, it is sieved through a 100 to 900 mesh sieve.

[0013] The high-performance carbohydrate biomass hard carbon negative electrode material obtained by the above preparation method.

[0014] The application of the above high-performance carbohydrate biomass hard carbon negative electrode material as a negative electrode material for a sodium ion battery.

[0015] The present invention discloses a high-performance carbohydrate biomass hard carbon negative electrode material, a preparation method thereof, and an application thereof, having the following beneficial effects: (1) Low production cost: Using conventional sugar-based biomass as a precursor, the raw materials are widely sourced and relatively inexpensive. Moreover, no solvents, cross-linking agents, etc. are used, resulting in an obvious advantage of low production cost.

[0016] (2) Simple process: The material preparation process is simple and controllable, which is beneficial for actual production. The sample pretreatment process does not require complex operating conditions, and the subsequent pyrolysis process is also relatively conventional, making it suitable for large-scale application and promotion.

[0017] (3) Excellent electrochemical performance: By utilizing the dehydration cross-linking effect between sucrose and starch under optimized conditions and the characteristics of in-situ formation of closed pores, a hard carbon material with excellent physical and chemical properties and abundant closed pores can be obtained, thereby simultaneously achieving high specific capacity, high initial efficiency, and excellent rate performance and cycling performance in terms of electrochemistry.

[0018] (4) Rational microstructure: By using the principle of thermal decomposition, reduction, and sublimation of zinc gluconate, a rich closed pore structure can be constructed inside the material, thereby optimizing the microstructure of the material. Description of the Drawings

[0019] Figure 1 It is the scanning electron microscope image of the high-performance sugar-based biomass hard carbon negative electrode material obtained in Example 1 of the present invention; Figure 2 It is the transmission electron microscope image of the high-performance sugar-based biomass hard carbon negative electrode material obtained in Example 1 of the present invention; Figure 3 It is the cycling performance graph of the sodium-ion battery prepared from the high-performance sugar-based biomass hard carbon negative electrode material in Example 1 of the present invention; Figure 4 It is the rate performance graph of the sodium-ion battery prepared from the high-performance sugar-based biomass hard carbon negative electrode material in Example 1 of the present invention; Figure 5 It is the cyclic voltammetry (CV) graph of the sodium-ion battery prepared from the high-performance sugar-based biomass hard carbon negative electrode material in Example 1 of the present invention; Figure 6 It is the charge-discharge curve graph of the sodium-ion battery prepared from the high-performance sugar-based biomass hard carbon negative electrode material in Example 1 of the present invention. Detailed Embodiments

[0020] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below with reference to the drawings. For those not specified in the examples regarding specific technologies or conditions, they shall be carried out according to the technologies or conditions described in the literature in this field or according to the product specifications. For the reagents or instruments not specified for the manufacturers, they are all conventional products that can be obtained through commercial purchases.

[0021] The first thing to be protected in the present invention is to provide a method for preparing a high-performance carbohydrate biomass hard carbon negative electrode material, comprising the following steps: S1, sucrose and starch are mixed evenly in a certain mass ratio, and then a small amount of zinc gluconate powder is added, and after mixing evenly, the mixture is transferred to a ceramic crucible, and placed in a box furnace with an inert gas for a period of time under oxygen-free conditions to obtain brown powder A1; Wherein, the starch is one or more of corn starch, wheat starch and rice starch; In terms of mass ratio, sucrose: starch = 10:1~1:10; The amount of zinc gluconate powder added is 1% to 30% of the total mass of sucrose and starch; The inert gas is nitrogen or argon; The temperature condition of anaerobic treatment is 160~280 ℃, and the time condition is 1~10 h.

[0022] S2, brown powder A1 is placed in a high-temperature box furnace and calcined for a period of time under the protection of inert gas; after natural cooling, the black block material is taken out and crushed with a crusher, and after sieving, a black powder intermediate product A2 is obtained; The inert gas is nitrogen or argon, the calcination temperature is 600~1000 ℃, the heating rate is 3 ℃ / min, and the calcination time is 0.5~4 h; After crushing, pass through a 100-600 mesh sieve; S3, calcining the black powder intermediate product A2 in a box furnace into which inert gas is introduced, the first calcination temperature platform is 1000-1600 ° C, the holding time is 2-5 h; the second platform is 1200-2000 ° C, the holding time is 2-5 h; the heating rate is 3 ° C / min; after natural cooling, take out the black powder and sieve it through a 100-900 mesh sieve to obtain a black powder product, that is, a high-performance sugar biomass hard carbon negative electrode material; Wherein, the inert gas is nitrogen or argon.

[0023] The present invention secondly aims to protect the high-performance carbohydrate biomass hard carbon negative electrode material obtained by the above-mentioned preparation method.

[0024] The third purpose of the present invention is to protect the application of the above-mentioned high-performance carbohydrate biomass hard carbon negative electrode material as a negative electrode material for sodium ion batteries.

[0025] Example 1 A method for preparing a high-performance carbohydrate biomass hard carbon negative electrode material comprises the following preparation steps: S1. Mix sucrose and starch evenly at a mass ratio of 3:2, then add zinc gluconate powder accounting for 20% of the total mass of sucrose and starch. After mixing evenly, transfer it to a ceramic crucible, and then place it in a box furnace with nitrogen gas introduced for anaerobic treatment at 220 °C for 6 h to obtain brown powder A1; S2. Place brown powder A1 in a high-temperature box furnace and calcine it at 900 °C for 3 h under nitrogen protection; after natural cooling, take it out, crush the black block material with a pulverizer, and obtain intermediate black powder A2 after sieving; S3. Calcinate intermediate black powder A2 in a box furnace with nitrogen gas introduced. The first platform temperature of the calcination treatment is 1100 °C, keep the temperature for 3 h, the second platform temperature is 1400 °C, keep the temperature for 3 h, and the heating rate is 3 °C / min; after natural cooling, take it out and sieve the black powder through an 800-mesh sieve to obtain a high-performance carbohydrate-based biomass hard carbon anode material.

[0026] Obtain the scanning electron microscope image of the high-performance carbohydrate-based biomass hard carbon anode material prepared in this example, and the result is as Figure 1 shown. It can be Figure 1 seen that the material shows a massive dense morphology, visible pore structures, and no loose structures.

[0027] Obtain the transmission electron microscope image of the high-performance carbohydrate-based biomass hard carbon anode material prepared in this example, and the result is as Figure 2 shown. It can be Figure 2 seen that the material shows non-orientation, is randomly stacked by single-layer or several-layer graphite sheets, shows a disordered arrangement, and has rich internal closed pore structures.

[0028] Figure 3 This is the cycle performance graph of the sodium-ion battery prepared with the high-performance carbohydrate-based biomass hard carbon anode material of this example; it can be Figure 3 seen that the capacity retention rate of the sodium-ion battery prepared with the high-performance carbohydrate-based biomass hard carbon anode material of Example 1 is 83% after cycling 500 times at a current density of 500 mA / g.

[0029] Figure 4 This is the rate performance graph of the sodium-ion battery prepared with the high-performance carbohydrate-based biomass hard carbon anode material of Example 1 of the present invention; it can be Figure 4 seen that the specific capacities at current densities of 0.03 A / g, 0.05 A / g, 0.10 A / g, 0.20 A / g, 0.50 A / g, 1.00 A / g, and 2.00 A / g are 332 mAh / g, 325 mAh / g, 316 mAh / g, 303 mAh / g, 287 mAh / g, 272 mAh / g, and 250 mAh / g respectively. After experiencing a large current and then returning to a small current, the specific capacity is 330 mAh / g.

[0030] Figure 5 The cyclic voltammetry (CV) diagram of the sodium ion battery prepared from the high-performance carbohydrate biomass hard carbon negative electrode material of Example 1 of the present invention; Figure 5 It can be seen that with the increase of the scan rate, the peak current on the electrode also increases, with peaks at 0.1 V and near 0.4 V. The sharp peak shape shows good diffusion dynamics.

[0031] Figure 6 This is a charge and discharge curve diagram of a sodium ion battery prepared with the high-performance carbohydrate biomass hard carbon negative electrode material of Example 1 of the present invention. Figure 6 It can be seen that the initial Coulomb efficiency is 91.3%.

[0032] Example 2 A method for preparing a high-performance carbohydrate biomass hard carbon negative electrode material comprises the following preparation steps: S1, sucrose and starch were mixed evenly in a mass ratio of 3:2, and then zinc gluconate powder was added at 10% of the total mass of sucrose and starch, and the mixture was transferred to a ceramic crucible, and then placed in a box furnace with nitrogen gas at 220° C. for 6 h to obtain brown powder A1; S2, place the brown powder A1 in a high-temperature box furnace and calcine at 900°C for 3 h under nitrogen protection. After natural cooling, take out the black block material and crush it with a crusher, and then sieve it to obtain the black powder semi-finished product A2; S3. Calcine the black semi-finished product A2 in a box furnace with nitrogen. The first platform temperature of the calcination treatment is 1100°C, and the temperature is kept for 3 hours. The second platform temperature is 1400°C, and the temperature is kept for 3 hours. After natural cooling, take out the black powder, sieve it through an 800-mesh sieve, and obtain a high-performance carbohydrate biomass hard carbon negative electrode material.

[0033] Example 3 A method for preparing a high-performance carbohydrate biomass hard carbon negative electrode material comprises the following preparation steps: S1, sucrose and starch were mixed evenly in a mass ratio of 3:2, and then 30% of the total mass of sucrose and starch was added with zinc gluconate powder, and the mixture was transferred to a ceramic crucible, and then placed in a box furnace with nitrogen gas at 220°C for 6 h to obtain brown powder A1; S2, place the brown powder A1 in a high-temperature box furnace and calcine at 900°C for 3 h under nitrogen protection. After natural cooling, take out the black block material and crush it with a crusher, and then sieve it to obtain the black powder semi-finished product A2; S3. Calcinate the black semi-finished product A2 in a box furnace with nitrogen introduced. The temperature of the first plateau for calcination treatment is 1100 °C, hold for 3 h, the temperature of the second plateau is 1400 °C, hold for 3 h; after natural cooling, take out and screen the black powder, pass through an 800-mesh sieve to obtain a high-performance sugar-based biomass hard carbon negative electrode material.

[0034] Comparative Example 1 A preparation method of a hard carbon negative electrode material for a sodium-ion battery, comprising the following preparation steps: S1. Slowly add 2 g of corn starch to 40 ml of deionized water under magnetic stirring, and pre-hold for 30 min under the conditions of an open container, air atmosphere, normal pressure, a temperature of 80 °C, and stirring at 600 - 800 r / min to obtain product A system.

[0035] S2. Transfer the product A system to a 100-ml autoclave, seal the container and heat it to 200 °C for pressure reaction for 12 h; after the heat preservation ends, relieve the pressure, separate the solid and liquid, and wash alternately with deionized water and ethanol for 2 - 3 times, and then dry in a vacuum drying oven at 80 °C for 12 h to obtain product B.

[0036] S3. Grind and weigh product B and disperse it in deionized water (the liquid-solid ratio is 40 - 45 ml / g), add an auxiliary agent (KOH, where the mass ratio of product B to the auxiliary agent is 1:3) while stirring magnetically, stir and modify at 80 °C for 1 h, and put the stirred mixed solution into a drying oven at 100 °C for drying for 14 - 18 h.

[0037] S4. Grind the dried solid into powder, put it into a porcelain boat, wrap and protect it with carbon cloth, then put it into a tube furnace, introduce argon for protection, carbonize at 850 °C for 2 h, the heating rate is 1 °C / min, and cool naturally to room temperature after carbonization.

[0038] S5. Prepare a sufficient amount of 1M HCl solution, put the carbonized product into the HCl solution and stir magnetically for 30 min to fully react to remove KOH, then filter by suction and repeatedly filter by suction with deionized water (the filtrate is neutral during washing) and ethanol, and dry in a vacuum at 80 °C for 12 h to finally obtain product C (starch-based hard carbon negative electrode material).

[0039] Comparative Example 2 A preparation method of a hard carbon negative electrode material for a sodium-ion battery, comprising the following preparation steps: S1. Dissolve 15 g of sucrose in 37.5 ml of deionized water, add 37.5 ml of acetic acid solution, and stir for 1 hour; S2. Pour 75 ml of the mixed solution into a hydrothermal reactor, heat it in a forced-air oven at 160 °C for 12 hours, and then cool it naturally to room temperature. Filter the solid-liquid mixture by suction, wash it until neutral, and dry it in a forced-air oven at 90 °C for 12 h to obtain hydrothermal carbon.

[0040] S3. Place the hydrothermal carbon in a tubular furnace. First, introduce air with a gas flow rate of 200 ml / min, heat it at a heating rate of 5 °C / min to a carbonization temperature of 250 °C, and keep it at this temperature for 1 h. Then, change to a nitrogen atmosphere with a gas flow rate of 100 ml / min, heat it at a heating rate of 10 °C / min to 1000 °C, and then heat it at a rate of 5 °C / min to 1400 °C and keep it at this temperature for 3 h to obtain a mesoporous spherical hard carbon anode material.

[0041] Respectively, use the hard carbon anode materials obtained in Examples 1-3 and Comparative Examples 1-2 as the active materials. After fully drying the required active materials, prepare a slurry according to the ratio of active material: Super P: binder of 91:3:6. The binder is a mixture of sodium carboxymethyl cellulose (CMC): polyacrylic acid (PAA) = 1:2. Weigh 4.5500 g of the active material, 0.1500 g of Super P, and 0.1000 g of CMC powder and add them to a ball mill jar. Weigh 0.5263 g of PAA emulsion with a solid content of 38%, rinse it into the ball mill jar with deionized water, add 10 large balls, 20 small balls, and an appropriate amount of water, and ball mill and mix at 400 rpm for 3 h to obtain the anode slurry. Coat the prepared slurry on the current collector copper foil with a coating thickness of 60 μm. First, place the coated aluminum foil in an 80 °C forced-air drying oven and dry it for 6 h, then place it in a 120 °C vacuum drying oven and dry it for 10 h. Finally, use a slicing machine to slice it to obtain a positive electrode sheet with a diameter of 14 mm for subsequent battery assembly.

[0042] Use a CR2430 coin cell for testing. When assembling the battery, start from the negative electrode case, place the negative electrode case upward, sequentially place the shrapnel and the gasket, then place the sodium sheet on the gasket, place the glass fiber separator, add 230 μL of electrolyte, then place the electrode sheet, put on the positive electrode case, press it into shape with a press, and let it stand for 30 min for subsequent performance testing.

[0043] Cyclic voltammetry (CV) test: Use a CHI600F to test the coin cell with scanning speeds of 0.1, 0.2, 0.5, 1.0, and 2.0 mV / s respectively, and set the voltage window to 0-3.0 V. Compare the peak shape, peak area, and oxidation-reduction peak polarization voltage difference of the cyclic voltammetry curves of the anode materials.

[0044] Galvanostatic charge-discharge (GCD) test: The coin cells were subjected to cycling and rate tests using a Neware electrochemical test device, and the voltage window was set to 0 - 3.0 V. The initial capacities of different samples and the capacity retention after 500 cycles at a current density of 0.5 A / g were mainly tested under low rate cycling.

[0045] Table 1: Electrochemical performance test results

[0046] From the data in Table 1, it can be seen that the sodium-ion batteries prepared using the high-performance carbohydrate biomass hard carbon anode materials described in Examples 1 - 3 of the present invention all have relatively high specific capacities. At the same time, after 500 cycles, their capacity retention rates are above 80%. And the first-cycle coulombic efficiencies are all around 90%, showing good reversible capacities. Compared with the comparative examples, there is no need to use special solvents and high-pressure reaction conditions, and the volume expansion of the precursor is effectively inhibited, which is suitable for large-scale production.

[0047] For the parts not covered above, the prior art applies.

[0048] Although some specific embodiments of the present invention have been described in detail by way of examples, those skilled in the art should understand that the above examples are only for illustration purposes and not for limiting the scope of the present invention. Those skilled in the technical field to which the present invention pertains can make various modifications or supplements to the described specific embodiments or use similar methods for substitution, but will not deviate from the direction of the present invention or exceed the scope defined by the appended claims. Those skilled in the art should understand that any modifications, equivalent substitutions, improvements, etc. made based on the technical essence of the present invention to the above embodiments should be included within the protection scope of the present invention.

Claims

1. A preparation method of a high-performance carbohydrate biomass hard carbon anode material, characterized in that, It includes the following steps: S1. After mixing sucrose and starch evenly according to a certain mass ratio, add zinc gluconate powder and mix evenly. After anaerobic treatment of the mixed powder, a brown powder is obtained; S2. After subjecting the brown powder to calcination, cooling, pulverization and sieving in sequence, an intermediate product is obtained; S3. After calcination treatment of the intermediate product in an inert gas atmosphere, it is cooled and screened to prepare a high-performance carbohydrate biomass hard carbon anode material.

2. The preparation method of a high-performance sugar-based biomass hard carbon anode material according to claim 1, characterized in that, In step S1, the starch is one or more of corn starch, wheat starch, and rice starch.

3. The preparation method of a high-performance carbohydrate biomass hard carbon anode material according to claim 1, characterized in that, In step S1, taking the mass ratio as, sucrose:starch = 10:1~1:10; The addition amount of zinc gluconate powder is 1%~30% of the total mass of sucrose and starch.

4. The preparation method of a high-performance sugar-based biomass hard carbon anode material according to claim 2, wherein, In step S1, the steps of anaerobic treatment are: performing anaerobic treatment on the mixed powder in an inert gas atmosphere; Among them, the inert gas is nitrogen or argon; The temperature condition of anaerobic treatment is 160~280 °C, and the time condition is 1~10 h.

5. The preparation method of a high-performance carbohydrate biomass hard carbon anode material according to claim 1, characterized in that, In step S2, the calcination is carried out in an inert gas atmosphere, the inert gas is nitrogen or argon, the calcination temperature is 600~1000 °C, the heating rate is 3 °C / min, and the calcination time is 0.5~2 h.

6. The preparation method of a high-performance carbohydrate biomass hard carbon anode material according to claim 5, characterized in that, In step S2, after pulverization, it is sieved through a 100~600 mesh sieve.

7. The preparation method of a high-performance sugar-based biomass hard carbon anode material according to claim 1, characterized in that, In step S3, the inert gas is nitrogen or argon, the calcination temperature is 1000~1800 °C, the heating rate is 3 °C / min, and the calcination time is 2~5 h.

8. The preparation method of a high-performance saccharide biomass hard carbon anode material according to claim 1, characterized in that, In step S3, after cooling, it is sieved through a 100~900 mesh sieve.

9. The high-performance carbohydrate biomass hard carbon anode material obtained by the preparation method according to any one of claims 1-8.

10. Application of the high-performance carbohydrate biomass hard carbon anode material according to claim 9 as an anode material for a sodium-ion battery.

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