CN114649516B - Lignin carbon/nickel oxide nano composite material and preparation method and application thereof - Google Patents

Abstract

The invention discloses a lignin carbon/nickel oxide nanocomposite material, a preparation method and application thereof. In the present invention, firstly, lignosulfonate is purified by low-concentration sulfuric acid, and then the concentration of carbonate solution is adjusted to provide an alkaline solution environment, and then p-aminobenzenesulfonate solution, nickel salt solution and aldehyde compound solution are slowly added, High-pressure hydrothermal reaction, and finally carbonization to obtain lignin carbon/nickel oxide nanocomposites. Both lignin carbon and nickel oxide in the material of the present invention exist in nanoscale, which effectively solves the problems of severe volume expansion and poor conductivity when nickel oxide is used as the negative electrode material of lithium ion batteries, and improves the specific capacity, cycle stability and rate performance.

Description

A kind of lignin carbon/nickel oxide nanocomposite material and its preparation method and application

technical field

The invention belongs to the technical field of negative electrode materials for lithium ion batteries, and in particular relates to a lignin carbon/nickel oxide nanocomposite material and a preparation method and application thereof.

Background technique

Due to the advantages of high energy density, long cycle life, no memory effect, and low self-discharge rate, lithium-ion batteries have been widely used in many fields such as new energy vehicles, portable electronic equipment, and aerospace equipment. As one of the main components of lithium-ion batteries, negative electrode materials directly affect the electrochemical performance of lithium-ion batteries.

Lithium-ion battery anode materials mainly include carbon materials, silicon-based materials, tin-based materials, alloy materials, transition metals and their oxides, etc. Among them, graphite-based carbon materials have the advantages of low cost, abundant raw material reserves, excellent electrical conductivity, and good lithium ion intercalation/extraction performance. They have become the first choice for commercial lithium-ion battery anode materials and occupy a dominant position in the market. However, graphite-based anode materials have disadvantages such as low theoretical capacity (372mAh/g), low ion diffusion coefficient caused by too narrow carbon layer spacing, and easy formation of lithium dendrites during high-rate charge and discharge, which cause safety hazards and other shortcomings. performance Li-ion battery demands. Therefore, there is an urgent need to develop a safe and efficient new anode material for Li-ion batteries to replace commercial graphite.

In recent years, transition metal oxides have received extensive attention as anode materials for lithium-ion batteries. Among them, the theoretical capacity of nickel oxide is as high as 718mAh/g, which is rich in reserves, cheap and easy to obtain, and has good corrosion resistance. It has a good application prospect as a negative electrode material for lithium-ion batteries. However, nickel oxide has the following two main problems, which seriously restrict its application and development in lithium ion battery negative electrode materials: (1) in the process of charging and discharging, the volume expansion rate of nickel oxide exceeds 90%, which is prone to agglomeration, rupture and Pulverization causes the electrode material to lose electrochemical activity, the battery capacity is reduced, and the cycle stability is poor; (2) the electronic conductivity of nickel oxide itself is low, and the rate performance is poor.

In response to these two problems of nickel oxide, researchers have proposed many methods to improve the lithium storage performance of nickel oxide. The main ideas can be divided into the following two types:

(1) Starting from the microstructure of nickel oxide, reduce its size and design nano-nickel oxide with good dispersion. Nanoscale nickel oxide can effectively alleviate the volume expansion effect, improve cycle stability, effectively shorten the diffusion path of lithium ions and electrons, and improve the rate performance of nickel oxide. Good dispersion can reduce the voltage polarization of nickel oxide and improve cycle performance. Varghese et al. (Chem. Mater. (2008) 20 (10): 3361) used a radio frequency plasma generator to assist oxidation, and used chemical vapor deposition to prepare nickel oxide nanowalls. The material was cycled at a current density of 448mA/g when storing lithium After 40 cycles, the specific capacity remained at about 700mAh/g. However, the high specific surface area provided by nanotechnology will aggravate the agglomeration of materials, so that the specific capacity will still decrease after a certain number of charge-discharge cycles. At the same time, the preparation process is complicated and it is difficult to mass-produce. Chinese patent application CN103151182A discloses a nano-nickel oxide electrode material, using lignosulfonate as a template, introducing nickel ions and alkaline substances into a solution to form a precipitate, and removing the lignosulfonate template after filtration and air calcination , obtained nano-nickel oxide, which has certain electrochemical properties as a supercapacitor electrode, but due to the lack of effective control and treatment of the template agent lignosulfonate and precipitation, the obtained nano-nickel oxide is a large block with serious agglomeration shape, it cannot be used as a high-performance lithium-ion battery anode material. Liu et al. (Journal of Materials Chemistry (2011) 21:3046) synthesized mesoporous nano-nickel oxide material by template method, and when it was applied to the negative electrode of lithium-ion battery, the discharge ratio was improved after 50 cycles at a current density of 71.8mA/g. The capacity is 680mAh/g, but due to its large average particle size (>20nm), severe agglomeration and volume expansion still occur in the subsequent charge and discharge process, which leads to capacity fading. Hu et al. (Energy & Environmental Science (2016) 9:595-603) found that when the particle size was smaller than 10 nm, its reversible performance was significantly improved when studying the lithium storage performance of nano-tin oxide. This conclusion also has guiding significance for the structure design of nano-nickel oxide. Sun et al. (Advanced Energy Materials (2014) 4(4): 1300912), Elizabeth et al. (Electrochimica Acta (2017) 230:98-105) and Feng et al. (Journal of Power Sources (2016) 301: 78-86) Research reports can strongly support this conclusion. However, it should be pointed out that the process of preparing pure-phase nano-nickel oxide with a particle size of less than 10 nm is often too complicated and difficult to realize.

(2) Combining nano-nickel oxide with carbon materials with good conductivity and structural strength is the main strategy to improve the lithium storage performance of nickel oxide. The composite of nickel oxide and carbon not only alleviates the volume expansion effect of nano-nickel oxide but also improves material electronic conductivity, thereby significantly improving the electrochemical performance. Tian et al. (Electrochimica Acta (2018) 261:236-245) first prepared hollow nickel oxide microspheres using yeast as a template, then coated a layer of glucose on the surface by hydrothermal, and carbonized to obtain carbon-coated nickel oxide hollow microspheres. Composite material, the material has a discharge specific capacity of 628mAh/g after 100 cycles at a current density of 100mA/g, and has good cycle performance. Its good performance is mainly due to the carbon-coated hollow sphere structure, which effectively inhibits the expansion of nickel oxide. Feng et al. (J.Mater.Chem.A, (2016) 4:3267-3277) first hydrothermally prepared nickel hydroxide, then coated glucose on the surface of nickel hydroxide, and obtained nickel oxide after carbonization reduction and air oxidation calcination / carbon composite material, which is used as a lithium-ion battery negative electrode material and has a discharge specific capacity of 1168mAh/g after 200 cycles at a current density of 500mA/g. Zou et al. (Nanoscale (2011) 3: 2615) and Han et al. (Journal of Alloys and Compounds (2020) 848: 156477) used graphene oxide and mushrooms as carbon sources respectively, and prepared two-step hydrothermal carbonization method with good Cyclically stable nickel oxide/carbon composites. Generally speaking, the process difficulty of compounding nano-nickel oxide and carbon materials is relatively low, which is an effective way to improve the electrochemical performance of nickel oxide. However, the carbon sources commonly used for compounding with nickel oxide are mostly graphene, graphene oxide, organic polymer compounds such as glucose and other chemicals, or biomass such as plant straw and plant rhizome. The former is expensive, some are toxic, and difficult to mass-produce, while the latter is limited by its natural structure and lacks structural designability. The size of the composite material is often large, which is not conducive to the uniform dispersion of nano-nickel oxide.

Lignin is a polymer with an amorphous three-dimensional network structure formed by three phenylpropane structural units linked by carbon-carbon bonds and ether bonds. It has high carbon content, high thermal stability, good mechanical strength and structural design, etc. Advantages, it is an ideal precursor for the preparation of carbon-based materials in nickel oxide/carbon composites. At present, composite materials using lignin carbon as a carbon source have made some progress as anode materials for lithium-ion batteries. The relevant literature and analysis are as follows:

Li Changqing et al. (Chemical Journal of Chinese Universities (2018) 39 (12): 2725-2733) used nano-silica as a template to prepare lignin carbon/silica composite materials by hydrothermal, carbonization, and pickling. The discharge specific capacity is 820mA/g after 100 cycles at a current density of g, and the cycle performance is good. The lignin carbon can buffer the volume expansion of silica, but because it directly uses commercial silica, the particle size To prevent its expansion, the amount of silica in the composite is less than 10%. Chinese patent application CN112072085A uses enzymatic lignin and zinc acetate for hydrothermal compounding, and uses the generated nano-zinc oxide as a template to prepare a lignin nano-carbon/zinc oxide composite material by carbonization and pickling. The material stores lithium at 200mA The discharge specific capacity is 705mAh/g after 200 cycles at a current density of 1/g, and the cycle performance is excellent, but the discharge specific capacity at 1000mA/g is only 360mAh/g, which is mainly due to the lignin coated on the outside of the composite material. The thick nano-carbon limits the lithium storage of the internal zinc oxide, and the ion transport is hindered at high current densities, resulting in poor rate performance. Xi et al. (Industrial Crops & Products (2021) 161:113179) prepared lignin charcoal with zinc carbonate as an activator, and then prepared lignin charcoal/tin oxide composite material by ball milling. The material was cycled at a current density of 100mA/g for 100 The discharge specific capacity after one cycle is 620mA/g, and the electrochemical performance has been improved compared with lignin carbon. Among them, the particle size of tin oxide is 20-30nm, and there is still a certain agglomeration phenomenon.

The above-mentioned composite materials with lignin carbon as the carbon skeleton can relieve the volume expansion of active components such as silicon dioxide, tin oxide or zinc oxide to a certain extent when used as the negative electrode material of lithium-ion batteries, and improve the electrochemical performance. However, these The literature reports did not significantly improve the dispersion of lignin carbon and active components or reduce the size of the two. Therefore, there is still room for further improvement in the lithium storage performance of related composite materials.

In terms of lignin carbon and nickel oxide composite materials as lithium-ion battery negative electrode materials, there are few relevant literature reports, mainly as follows: Chen et al. (Green Chemistry (2013) 15:3057-3063) first added sodium lignosulfonate to nickel nitrate Then add crosslinking agent formaldehyde and glutaraldehyde, polymerize at 80°C at low temperature, and finally carbonize in argon atmosphere at 600°C to obtain a lignin carbon/nickel oxide composite material, which is used as a supercapacitor electrode It has a high specific capacitance of 880.2F/g at a current density of 1000mA/g. However, because the lignin char in this composite material is formed by cross-linked macromolecule sodium lignosulfonate, the dispersion is poor, the agglomeration is serious, and it lacks good structural toughness, mainly in a disordered stacking structure, resulting in large Part of the nickel oxide is confined inside the lignin carbon or completely covered in the disordered carbon layer, and there is a phenomenon of large particle size and serious agglomeration, so this material cannot effectively solve the volume expansion effect and conductivity of nickel oxide. The poor problem is not conducive to improving the lithium storage capacity. Chinese patent application CN112928233A discloses a preparation method of a nickel oxide-lignin carbon composite material with a core-shell structure and its application in a negative electrode of a lithium-ion battery. In this method, alkali lignin is used as a carbon source, and polyethyleneimine-grafted lignin microspheres are prepared first, and then the lignin microspheres are used to absorb inorganic nickel to obtain nickel-based lignin microspheres, and then the nickel-based lignin microspheres are The balls were carbonized in a tube furnace to obtain a core-shell structure nitrogen-doped carbon-coated nickel oxide composite, and finally the composite was mixed with potassium hydroxide for secondary carbonization to obtain a core-shell structure nickel oxide-wood Plain carbon composite material, when the composite material stores lithium, after 200 cycles at a current density of 100mA/g, the charging specific capacity is 854.2mAh/g. By preparing a porous core-shell composite structure and using the coating effect of porous carbon spheres, the method alleviates the volume expansion problem of nickel oxide to a certain extent, avoids the rapid capacity decay of nickel oxide negative electrode materials, and improves the capacity retention rate. and cycle stability. However, the preparation method of this material is too complicated, the process is long, and the process includes two carbonization processes, which has high energy consumption and is not conducive to industrial application. Zhou et al. (Electrochimica Acta (2018) 274:288-297) adopted a two-step carbonization method, using sodium lignosulfonate as a carbon source, mixing with isopropanol to form lignin nanospheres, and then carbonizing them in an argon atmosphere at 800 °C. Lignin-based hierarchical porous carbon spheres were obtained by medium carbonization, followed by hydrothermal loading of inorganic nickel, and low-temperature carbonization at 450 °C to obtain lignin carbon spheres/nickel oxide composites. When the material is used as a lithium ion battery negative electrode, the discharge specific capacity can still be maintained at about 500mAh/g at a high current density of 1000mA/g, and the rate performance is excellent, but the cycle performance is poor. This is mainly because the size of lignin carbon spheres in the composite material is still larger than 100nm, its own structural strength is poor and there is a certain agglomeration phenomenon, which will reduce the cycle stability of the composite material to a certain extent.

In summary, when the lignin carbon/nickel oxide composite material prepared by the existing technology or process is applied to the anode material of lithium ion battery, there are generally problems of low lithium storage capacity and poor cycle stability. The main reason is that (1) The size of lignin carbon and nickel oxide in the composite material is relatively large, most of which are micron-scale, and the agglomeration phenomenon is still serious, which cannot effectively alleviate the problems of volume expansion, low conductivity and poor dispersion of nickel oxide; (2 ) Lignin charcoal has poor structural strength, and it is prone to collapse or fragmentation during the cycle, resulting in the inability of the composite material to maintain a good structure and causing a series of problems such as poor cycle stability.

Contents of the invention

In order to solve the shortcomings and deficiencies of the prior art, the primary purpose of the present invention is to provide a preparation method of lignin carbon/nickel oxide nanocomposite material.

Aiming at the problem of large size of lignin char and nickel oxide, according to the physical and chemical properties of lignin, the method of the present invention first further purifies lignosulfonate with low-concentration sulfuric acid, and collects high-solubility groups with a sulfonation degree greater than 2.0mmol/g. Then, by adjusting the concentration of carbonate solution to provide an alkaline solution environment, the carboxyl and phenolic hydroxyl groups in the lignosulfonate are ionized, the electrostatic repulsion is strengthened, the three-dimensional network structure is further expanded, and the dispersion is improved, and then Slowly add low-concentration nickel salt solution, so that nano-nickel carbonate grows uniformly in the three-dimensional network skeleton of lignin, effectively reducing the agglomeration of lignin carbon and nickel oxide particles during carbonization, and finally obtaining lignin carbon/nickel oxide nano composite material.

Aiming at the problem of poor structural strength of lignin charcoal, on the one hand, the method of the present invention proceeds from the physical and chemical properties of lignin, and obtains lignosulfonate with high sulfonation degree through dilute acid purification, which relieves the lignin charcoal itself from being damaged by electricity. The agglomeration phenomenon in the chemical reaction process further improves the structural stability of lignin charcoal. The three-dimensional network skeleton is conducive to the effective coating, dispersion and stabilization of lignin carbon on nickel oxide particles, which significantly improves the cycle stability of lithium-ion batteries.

Another object of the present invention is to provide a lignin carbon/nickel oxide nanocomposite material prepared by the above method. Both lignin carbon and nickel oxide exist in nanoscale, which effectively solves the problem of the volume of nickel oxide as the negative electrode material of lithium ion batteries. The problems of severe expansion and poor conductivity improve the specific capacity, cycle stability and rate performance of lithium-ion batteries.

In the present invention, the size of the nano-lignin carbon is less than 10 nm, and the size of the nano-nickel oxide is less than 5 nm.

Another object of the present invention is to provide the application of the above-mentioned lignin carbon/nickel oxide nanocomposite material in lithium-ion battery negative electrode materials.

The object of the invention is achieved through the following technical solutions:

A preparation method of lignin carbon/nickel oxide nanocomposite material, comprising the following steps:

(1) Use a sulfuric acid solution with a mass concentration of 4 to 20% to carry out acid treatment on the lignosulfonate, collect the filtrate, then add an ethanol solution with a mass concentration ≥ 50% to precipitate, centrifuge, and dry to obtain a sulfonation degree greater than 2.0 Purified lignosulfonate of mmol/g;

(2) Dissolve the purified lignosulfonate in step (1) in water, and then add carbonate solution, p-aminobenzenesulfonate solution, nickel salt solution and aldehyde compounds in sequence at a rate of 1 to 10 mL/min After the solution is mixed evenly, the hydrothermal reaction is carried out in a hydrothermal kettle at 100-200°C for 1-6 hours, filtered, and dried to obtain a lignin/nickel carbonate composite;

(3) Carbonize the lignin/nickel carbonate composite, then centrifugally wash and dry to obtain the lignin carbon/nickel oxide nanocomposite material.

Preferably, in step (2), the mass ratio of purified lignosulfonate, carbonate, p-aminobenzenesulfonate, nickel salt and aldehyde compound is 10g: 1-10g: 0.5-10g: 1-10g : 0.5 ~ 10g.

More preferably, the mass ratio of the purified lignosulfonate, carbonate, p-aminobenzenesulfonate, nickel salt and aldehyde compound in step (2) is 10g: 1～5g: 0.5～2g: 1～ 5g: 0.5 ~ 2g.

Preferably, the lignosulfonate in step (1) can be sodium lignosulfonate, calcium lignosulfonate and magnesium lignosulfonate extracted from acid pulping red liquor and black liquor from alkaline pulping. At least one of sulfonated alkali lignin and sulfomethylated alkali lignin obtained from the sulfonation/sulfomethylation reaction.

Preferably, the mass ratio of lignosulfonate, sulfuric acid solution and ethanol solution in step (1) is 1:2.5-12.5:2.5-5.

Preferably, the mass concentration of the sulfuric acid solution in step (1) is 5-10%.

Preferably, the rotational speed of the centrifugation in step (1) is ≥ 10000 rpm, and the time is ≥ 10 min.

Preferably, the inorganic nickel salt in step (2) is at least one of nickel chloride, nickel nitrate, nickel sulfate and nickel acetate.

Preferably, the carbonate in step (2) is at least one of potassium carbonate, sodium carbonate, ammonium carbonate, potassium bicarbonate, sodium bicarbonate and ammonium bicarbonate.

Preferably, the mass concentration of the solution obtained by dissolving the purified lignosulfonate in step (2) in water is 10-40%; more preferably 10-30%.

Preferably, the mass concentration of the nickel salt solution in step (2) is 5-20%; more preferably 5-10%.

Preferably, the mass concentration of the carbonate solution in step (2) is 5-20%; more preferably 5-10%.

Preferably, the mass concentration of the p-aminobenzenesulfonate solution in step (2) is 10-40%; more preferably 20-30%.

Preferably, the aldehyde compound in step (2) is at least one of formaldehyde, acetaldehyde and propionaldehyde.

Preferably, the mass concentration of the aldehyde compound solution in step (2) is 20-50%; more preferably 30-40%.

Preferably, the adding speed in step (2) is 2-6 mL/min.

Preferably, the temperature of the hydrothermal treatment in step (2) is 110-180° C., and the time is 1-4 hours.

Preferably, the carbonization in step (3) is carried out under nitrogen or an inert gas atmosphere, and the inert gas is at least one of argon and helium.

Preferably, the carbonization procedure in step (3) is as follows: heat up to 120-350°C at 5°C/min, keep warm for 20-60min, then heat up to 500-700°C at 5-10°C/min, keep warm for 0.5-5h , cool down to room temperature; more preferably: heat up to 250°C at 5°C/min, keep warm for 30-40min, then heat up to 600°C at 5°C/min, keep warm for 2-3h, and cool down to room temperature.

Preferably, the centrifugal washing in step (3) refers to immersing the carbonized product in water, washing to remove residual pyrolysis products, and then centrifuging at a speed ≥ 6000 rpm for a time ≥ 10 min.

Preferably, the drying described in this method is at least one of blast drying, vacuum drying and infrared drying, the drying temperature is higher than 50° C., and the drying time is ≥4 hours.

A lignin carbon/nickel oxide nanocomposite material prepared by the above method.

The application of the above-mentioned lignin carbon/nickel oxide nanocomposite material in the fields of lithium-ion battery negative electrode materials, supercapacitors and photoelectric catalysis.

The invention patent will be described in more detail below.

(1) Using a sulfuric acid solution with a mass concentration of 1 to 20% to carry out acid treatment and purification of lignosulfonate, collect the filtrate, then add an ethanol solution with a mass concentration ≥ 50% to precipitate, and centrifuge the precipitate to obtain sulfonate after drying. Purified lignosulfonate with a degree of oxidation greater than 2.0 mmol/g.

This step is based on the physical and chemical properties of lignin, using low-concentration sulfuric acid to purify lignosulfonate, remove components with a sulfonation degree lower than 2.0mmol/g, collect the filtrate, and then add an ethanol solution with a mass concentration ≥ 50% Precipitating lignosulfonate precipitates, removing water-soluble inorganic salts, etc., and drying the precipitates to obtain a solid product is purified lignosulfonate with a sulfonation degree greater than 2.0 mmol/g.

The concentration of sulfuric acid solution needs to be controlled in this step, if mass concentration is less than 5%, then purification effect is poor, and the lignosulfonate that sulfonation degree is less than 2.0mmol/g is difficult to remove, and the purified lignosulfonate obtained has high Insufficient water solubility makes it impossible to disperse uniformly with nickel carbonate in the solution, and then it is difficult to form small-sized nano-lignin carbon and nano-nickel oxide during the carbonization process; if the mass concentration is greater than 10%, the cost is high.

(2) Prepare the purified lignosulfonate, carbonate, nickel salt, p-aminobenzenesulfonate and aldehyde compound aqueous solution of a certain mass concentration, and carbonate solution, p-sulfanilate solution, nickel salt The solution and the aldehyde compound solution were slowly added to the purified lignosulfonate solution in sequence, stirred for more than 20 minutes, then placed at 100-200°C for hydrothermal reaction for 1-6 hours, filtered and dried to obtain the lignin/nickel carbonate compound;

This step is to provide an alkaline environment through carbonate hydrolysis to further promote the extension of the three-dimensional network structure of the purified lignosulfonate, and then add p-aminobenzenesulfonate to further promote the dispersion of nickel carbonate in the hydrothermal process. reaction, p-aminobenzenesulfonate can also produce cross-linking with aldehyde compounds and purified lignosulfonate, further stabilizing the structural strength of the three-dimensional network skeleton of lignin, and finally obtaining a small-sized lignin/nickel carbonate composite.

In this step, the carbonate solution needs to be slowly added to the purified lignosulfonate solution to fully hydrolyze and provide an alkaline environment, then slowly add the p-aminobenzenesulfonate solution, and finally slowly introduce nickel ions to generate well-dispersed Small size nickel carbonate. If the nickel ions are introduced first, and then the carbonate solution is added, an alkaline environment cannot be provided for the growth of the nickel carbonate crystal nuclei, which makes it difficult for the three-dimensional network skeleton of the lignosulfonate to unfold and cause agglomeration. Stirring during this period is to make the lignin/nickel carbonate complex disperse evenly in the mixed solution.

Need to strictly control the concentration of nickel salt solution and carbonate solution in this step, also can not directly use nickel carbonate. If the concentration of nickel salt and carbonate solution is too high, a large number of agglomerated nickel carbonate solids will be generated in the solution, and lignosulfonate cannot coat nickel carbonate, which will lead to unstable structure of the composite material. The performance is poor; and the direct use of nickel carbonate will also cause uneven dispersion of nickel carbonate and lignin, and good electrochemical performance cannot be obtained.

In this step, the mass concentration of p-aminobenzenesulfonate solution and aldehyde compounds also needs to be strictly controlled. If the mass concentration is too high, it will cause excessive condensation of lignosulfonate in the hydrothermal process and destroy lignosulfonate. /Nickel carbonate composite structure stability, resulting in local agglomeration or exposure; if the mass concentration is too low, the condensation of lignosulfonate in the hydrothermal process is not complete, which is not conducive to improving the structural strength of lignin.

In this step, the hydrothermal reaction can further nucleate the grains of the initially grown nickel carbonate and recombine with lignosulfonate, and at the same time further cross-link p-aminobenzenesulfonate and lignosulfonate to improve lignin The strength of the 3D network skeleton. This step needs to control the temperature and time of the hydrothermal reaction. If the temperature is too high and the time is too long, the nickel carbonate crystals will grow excessively, causing severe agglomeration, and consume a lot of energy, which will increase the production cost; if the temperature is too low and the time is too short, the carbonic acid The nickel nuclei cannot grow to be stable, and the cross-linking of lignin is not complete, which makes the structural strength of the composite material poor, and it is easy to collapse or break during the carbonization process.

(3) Carbonize the lignin/nickel carbonate composite obtained in step (2), wash, centrifuge, and dry to obtain the lignin carbon/nickel oxide nanocomposite material.

The carbonization atmosphere in this step is a nitrogen atmosphere, which can be replaced by other inert gases such as argon and helium. The carbonization temperature is required to be within 500-700 ° C, and the time is within 0.5-5 hours. If the temperature is too low and the time is too short, it will lead to incomplete carbonization of lignin, and there are a large number of oxygen-containing functional groups on the surface, which is easy to occur during charging and discharging. side reactions, thereby reducing the lithium storage performance of the composite material; if the temperature is too high and the time is too long, on the one hand, the energy consumption will be too high, which will significantly increase the production cost; stability.

In the present invention, the size of the lignin carbon/nickel oxide nanocomposite material is less than 10nm, and can be applied in the fields of lithium ion battery negative electrode materials, supercapacitors, and photoelectric catalysis.

Compared with the prior art, the present invention has the following advantages and beneficial effects:

(1) The particle size of the lignin carbon/nickel oxide nanocomposite material prepared by the present invention is less than 10nm, and the structure is relatively regular and orderly. The distribution of the lignin nano-carbon is relatively uniform, and the lignin nano-carbon can effectively coat the nickel oxide to suppress its volume expansion effect, and the higher conductivity of the lignin carbon than the nickel oxide can also effectively improve the overall electron diffusion rate of the composite material, and then Excellent cycle performance and rate performance are obtained. In addition, the lignin carbon in the composite material has higher structural strength, which is not easy to be broken and collapsed in the electrochemical reaction, which is beneficial to the cycle stability of the composite material. As a negative electrode material for lithium-ion batteries, compared with pure nano-nickel oxide, it has better cycle performance and rate performance, and has a good application prospect.

(2) In the preparation process of the lignin carbon/nickel oxide nanocomposite, the present invention uses lignosulfonate as the carbon source and nickel salt as the nickel source to achieve good coating of lignin nano-carbon to nano-nickel oxide , the raw material is a renewable resource with abundant reserves, cheap and easy to obtain, the preparation process is green, simple and environmentally friendly, and can realize the resource utilization of papermaking black liquor or biorefinery waste, which not only saves resources but also protects the environment, and has broad application prospects.

Description of drawings

Figure 1 is a constant current charge and discharge diagram of the lignin carbon/nickel oxide nanocomposite material prepared in Example 1 of the present invention.

Fig. 2 is a graph of the rate performance of the lignin carbon/nickel oxide nanocomposite material prepared in Example 1 of the present invention.

Fig. 3 is a SEM image of the lignin carbon/nickel oxide nanocomposite material prepared in Example 1 of the present invention, wherein the small image in the upper left corner is the particle size distribution diagram of the composite material.

Fig. 4 is a TEM image of the lignin carbon/nickel oxide nanocomposite material prepared in Example 1 of the present invention.

Detailed ways

The present invention will be further described in detail below with reference to the examples and drawings, but the implementation of the present invention is not limited thereto.

In the embodiment of the present invention, if no specific conditions are indicated, it is carried out according to the conventional conditions or the conditions suggested by the manufacturer. The raw materials, reagents, etc. of manufacturers not indicated are all conventional products that can be purchased from the market.

Example 1

Take 500 g of sulfuric acid solution with a mass concentration of 10%, add 100 g of sodium lignosulfonate powder, stir while adding, and then filter to obtain the filtrate. Take 500g of ethanol solution with a mass concentration of 50%, add it to the obtained filtrate, stir while adding, then centrifuge at a speed of 10000rpm for 10min, pour off the supernatant, and transfer the centrifugal precipitate to a 50°C infrared drying oven Dry in medium for 24 hours to obtain purified sodium lignosulfonate with a sulfonation degree greater than 2.0 mmol/g.

Preparation 100g mass concentration is 10% above-mentioned purified sodium lignosulfonate solution, 30g mass concentration is 10% nickel chloride solution, 30g mass concentration is 10% sodium carbonate solution, 3g mass concentration is 30% p-aminobenzene Sodium sulfonate solution and 3g of formaldehyde solution with a mass concentration of 40%, using a peristaltic pump, slowly add sodium carbonate solution, sodium p-aminobenzenesulfonate solution, nickel chloride solution, and formaldehyde solution to the purification process at a rate of 2mL/min. Sodium lignosulfonate solution, stirring while adding dropwise. After stirring for more than 20 minutes, the mixed solution was transferred to a hydrothermal kettle, placed in an air atmosphere of 120°C and heated for 2 hours, filtered and dried to obtain a lignin/nickel carbonate composite.

Transfer the above-prepared lignin/nickel carbonate composite to a carbonization furnace, in a nitrogen atmosphere, raise the temperature to 250°C at a rate of 5°C/min, keep it for 30min, and then raise it to 250°C at a rate of 5°C/min. Keep at 600°C for 2 hours. When it drops to room temperature, soak the charred product in deionized water and wash it, then centrifuge it at 10,000 rpm for 10 minutes, pour off the supernatant, and transfer the centrifuged sediment to an infrared oven at 50°C for 24 hours. , to prepare lignin carbon/nickel oxide nanocomposites.

Example 2

Take 250g of sulfuric acid solution with a mass concentration of 20%, add 100g of sodium lignosulfonate powder, stir while adding, and then filter to obtain the filtrate. Take 416.7g of ethanol solution with a mass concentration of 60%, add it to the obtained filtrate, stir while adding, then centrifuge at a speed of 10000rpm for 15min, pour off the supernatant, and transfer the centrifugal precipitate to 50°C for infrared drying Dry in an oven for 24 hours to obtain purified sodium lignosulfonate with a sulfonation degree greater than 2.0 mmol/g.

Preparation 25g mass concentration is that the above-mentioned purified sodium lignosulfonate solution of 40%, 25g mass concentration is the 20% nickel nitrate solution, 25g mass concentration is the 20% sodium bicarbonate solution, 5g mass concentration is 40% p-aminobenzene Sodium sulfonate solution and 4g of formaldehyde solution with a mass concentration of 50%, using a peristaltic pump, sodium bicarbonate solution, sodium sulfanilate solution, nickel nitrate solution, and formaldehyde solution were slowly added dropwise at a rate of 10mL/min to the purification Sodium lignosulfonate solution, stirring while adding dropwise. After stirring for more than 20 minutes, the mixed solution was transferred to a hydrothermal kettle, placed in an air atmosphere at 200°C and heated for 6 hours, filtered and dried to obtain a lignin/nickel carbonate composite.

Transfer the above-prepared lignin/nickel carbonate composite to a carbonization furnace, in a nitrogen atmosphere, raise the temperature to 350°C at a rate of 5°C/min, keep it for 60 minutes, and then raise the rate of temperature to 350°C at a rate of 10°C/min. 700°C, keep it for 5h, wait for it to cool down to room temperature, soak the charred product in deionized water and wash, then centrifuge at 10000rpm for 10min, pour off the supernatant, and transfer the centrifuged sediment to an infrared oven at 50°C for 24h , to prepare lignin carbon/nickel oxide nanocomposites.

Example 3

Take 1250g of sulfuric acid solution with a mass concentration of 4%, add 100g of magnesium lignosulfonate powder, stir while adding, and then filter to obtain the filtrate. Then take 357.1g of ethanol solution with a mass concentration of 70%, add it to the obtained filtrate, stir while adding, then centrifuge at a speed of 12000rpm for 10min, pour off the supernatant, and transfer the centrifugal precipitate to 50°C for infrared drying Dry in an oven for 24 hours to obtain purified magnesium lignosulfonate with a sulfonation degree greater than 2.0 mmol/g.

Preparation 100g mass concentration is 10% above-mentioned purified magnesium lignosulfonate solution, 20g mass concentration is 5% nickel sulfate solution, 20g mass concentration is 5% potassium carbonate solution, 5g mass concentration is 10% p-aminobenzenesulfonate Sodium bicarbonate solution and 2.5g of acetaldehyde solution with a mass concentration of 20%, using a peristaltic pump, potassium carbonate solution, sodium sulfanilate solution, nickel sulfate solution, and acetaldehyde solution were slowly added dropwise at a rate of 2mL/min. In the purified magnesium lignosulfonate solution, stir while adding dropwise. After stirring for more than 20 minutes, the mixed solution was transferred to a hydrothermal kettle, placed in an air atmosphere at 100°C and heated for 1 hour, filtered and dried to obtain a lignin/nickel carbonate composite.

Transfer the above-prepared lignin/nickel carbonate composite to a carbonization furnace, in a nitrogen atmosphere, raise the temperature to 120°C at a rate of 5°C/min, keep it for 20min, and then increase the rate of temperature to 120°C at a rate of 5°C/min. 500°C, keep it for 0.5h, wait for it to cool down to room temperature, soak the charred product in deionized water and wash, then centrifuge at 10000rpm for 10min, pour off the supernatant, and transfer the centrifuged sediment to an infrared oven at 50°C for drying After 24 hours, the lignin carbon/nickel oxide nanocomposite material was prepared.

Example 4

Take 500g of sulfuric acid solution with a mass concentration of 10%, add 100g of calcium lignosulfonate powder, stir while adding, then filter to obtain the filtrate. Then take 357.1g of ethanol solution with a mass concentration of 70%, add it to the obtained filtrate, stir while adding, then centrifuge at a speed of 11000rpm for 10min, pour off the supernatant, and transfer the centrifugal precipitate to 50°C for infrared drying Dry in an oven for 24 hours to obtain purified calcium lignosulfonate with a sulfonation degree greater than 2.0 mmol/g.

Preparation of 33.3g mass concentration is that the above-mentioned purified calcium lignosulfonate solution of 30%, 50g mass concentration are 10% nickel acetate solution, 50g mass concentration are 10% potassium bicarbonate solution, 6.7g mass concentration are 30% para Sodium sulfanilate solution and 5 g of propionaldehyde solution with a mass concentration of 40% were slowly mixed with potassium bicarbonate solution, sodium sulfanilate solution, nickel acetate solution, and propionaldehyde solution at a rate of 6 mL/min using a peristaltic pump. Add it dropwise to the purified calcium lignosulfonate solution, and stir while adding it. After stirring for more than 20 minutes, the mixed solution was transferred to a hydrothermal kettle, placed in an air atmosphere at 180°C and heated for 4 hours, filtered and dried to obtain a lignin/nickel carbonate composite.

Transfer the above-prepared lignin/nickel carbonate composite to a carbonization furnace, in a nitrogen atmosphere, raise the temperature to 250°C at a rate of 5°C/min, keep it for 40 minutes, and then increase the rate of temperature to 250°C at a rate of 10°C/min. Keep at 650°C for 1 hour, and when it drops to room temperature, soak the carbonized product in deionized water and wash it, then centrifuge it at 10,000rpm for 10 minutes, pour off the supernatant, and transfer the centrifuged sediment to an infrared oven at 50°C to dry for 24 hours , to prepare lignin carbon/nickel oxide nanocomposites.

Example 5

Take 625g of sulfuric acid solution with a mass concentration of 8%, add 100g of sulfonated alkali lignin powder, stir while adding, and then filter to obtain a filtrate. Take 500g of ethanol solution with a mass concentration of 70%, add it to the obtained filtrate, stir while adding, then centrifuge at a speed of 10000rpm for 20min, pour off the supernatant, and transfer the centrifugal precipitate to a 50°C infrared drying oven Dry in medium for 24 hours to obtain purified sulfonated alkali lignin with a sulfonation degree greater than 2.0 mmol/g.

Preparation of 100g mass concentration is 10% of the above purified sulfonated alkali lignin solution, 10g mass concentration is 10% nickel chloride solution, 10g mass concentration is 10% ammonium carbonate solution, 2.5g mass concentration is 20% p-amino Sodium benzenesulfonate solution and 1.67g of formaldehyde solution with a mass concentration of 30% were slowly added dropwise to ammonium carbonate solution, ammonium p-sulfanilate solution, nickel chloride solution, and formaldehyde solution at a rate of 5mL/min using a peristaltic pump Add it to the purified sulfonated alkali lignin solution, and stir while adding it dropwise. After stirring for more than 20 minutes, the mixed solution was transferred to a hydrothermal kettle, placed in an air atmosphere at 110°C and heated for 3 hours, filtered and dried to obtain a lignin/nickel carbonate composite.

Transfer the above-prepared lignin/nickel carbonate composite to a carbonization furnace, in a nitrogen atmosphere, raise the temperature to 300°C at a rate of 5°C/min, keep it for 30min, and then raise the rate of temperature to 300°C at a rate of 5°C/min. Keep at 550°C for 3h, when it drops to room temperature, soak the charred product in deionized water and wash it, then centrifuge at 10,000rpm for 10min, pour off the supernatant, and transfer the centrifuged sediment to an infrared oven at 50°C for 24h , to prepare lignin carbon/nickel oxide nanocomposites.

Example 6

Take 500 g of sulfuric acid solution with a mass concentration of 10%, add 100 g of sulfomethylated alkali lignin powder, stir while adding, and then filter to obtain a filtrate. Take 500g of ethanol solution with a mass concentration of 50%, add it to the obtained filtrate, stir while adding, then centrifuge at a speed of 10000rpm for 10min, pour off the supernatant, and transfer the centrifugal precipitate to a 50°C infrared drying oven Dry in medium for 24 hours to obtain purified sulfomethylated alkali lignin with a sulfonation degree greater than 2.0 mmol/g.

Preparation 50g mass concentration is the above-mentioned purified sulfomethylated alkali lignin solution of 20%, 13.3g mass concentration is 15% nickel chloride solution, 13.3g mass concentration is 15% ammonium bicarbonate solution, 5g mass concentration is 25% % sodium sulfanil solution and 3.57g mass concentration of 35% formaldehyde solution, ammonium bicarbonate solution, ammonium sulfanil solution, nickel chloride solution, formaldehyde solution at 3mL/min The rate is slowly added dropwise to the purified sulfomethylated alkali lignin solution, and stirred while dropping. After stirring for more than 20 minutes, the mixed solution was transferred to a hydrothermal kettle, placed in an air atmosphere at 150°C and heated for 2 hours, filtered and dried to obtain a lignin/nickel carbonate composite.

Transfer the above-prepared lignin/nickel carbonate composite to a carbonization furnace, in a nitrogen atmosphere, raise the temperature to 250°C at a rate of 5°C/min, keep it for 35min, and then rise to 250°C at a rate of 5°C/min. Keep at 600°C for 2 hours. When it drops to room temperature, soak the charred product in deionized water and wash it, then centrifuge it at 10,000 rpm for 10 minutes, pour off the supernatant, and transfer the centrifuged sediment to an infrared oven at 50°C for 24 hours. , to prepare lignin carbon/nickel oxide nanocomposites.

Comparative example 1 (direct use of pure nickel oxide) proves that there is no effective coating of lignin carbon, and pure phase nano-nickel oxide is easy to agglomerate.

Prepare 30g mass concentration of 10% nickel chloride solution and 30g mass concentration of 10% sodium carbonate solution, use a peristaltic pump to slowly drop the nickel chloride solution into the sodium carbonate solution successively at a rate of 2mL/min, dripping Add and stir. After stirring for more than 20 minutes, the mixed solution was transferred to a hydrothermal kettle, placed in an air atmosphere of 120° C. and heated for 2 hours, filtered and dried to obtain nickel carbonate.

Transfer the nickel carbonate prepared above to a carbonization furnace, in a nitrogen atmosphere, raise the temperature to 250°C at a rate of 5°C/min, keep it for 30 minutes, then raise it to 600°C at a rate of 5°C/min, and keep it for 2h , when it dropped to room temperature, soak the carbonized product in deionized water and wash it, then centrifuge it at 10000rpm for 10min, pour off the supernatant liquid, and transfer the centrifuged precipitate to an infrared oven at 50°C for drying for 24h to obtain nano-oxidized nickel material.

Comparative example 2 (direct use of nickel carbonate) proves that the preparation process of dissolving and then precipitating the nickel salt is lacking, the dispersion of nickel carbonate is uneven, the lignin cannot be effectively coated, and the nickel oxide particles generated after carbonization are relatively large and easy to agglomerate.

Take 500 g of sulfuric acid solution with a mass concentration of 10%, add 100 g of sodium lignosulfonate powder, stir while adding, and then filter to obtain the filtrate. Take 500g of ethanol solution with a mass concentration of 50%, add it to the obtained filtrate, stir while adding, then centrifuge at a speed of 10000rpm for 10min, pour off the supernatant, and transfer the centrifugal precipitate to a 50°C infrared drying oven Dry in medium for 24 hours to obtain purified sodium lignosulfonate with a sulfonation degree greater than 2.0 mmol/g.

Preparation 100g mass concentration is 10% above-mentioned purified sodium lignosulfonate solution, 30g mass concentration is 10% nickel carbonate suspension, 3g mass concentration is 30% sodium p-aminobenzenesulfonate solution and 3g mass concentration is 40% For the formaldehyde solution, use a peristaltic pump to slowly add the nickel carbonate suspension, sodium p-aminobenzenesulfonate solution, and formaldehyde solution into the purified sodium lignosulfonate solution successively at a rate of 2 mL/min, and stir while adding. After stirring for more than 20 minutes, the mixed solution was transferred to a hydrothermal kettle, placed in an air atmosphere of 120°C and heated for 2 hours, filtered and dried to obtain a lignin/nickel carbonate composite.

Transfer the above-prepared lignin/nickel carbonate composite to a carbonization furnace, in a nitrogen atmosphere, raise the temperature to 250°C at a rate of 5°C/min, keep it for 30min, and then raise it to 250°C at a rate of 5°C/min. Keep at 600°C for 2 hours. When it drops to room temperature, soak the charred product in deionized water and wash it, then centrifuge it at 10,000 rpm for 10 minutes, pour off the supernatant, and transfer the centrifuged sediment to an infrared oven at 50°C for 24 hours. , to prepare lignin carbon/nickel oxide nanocomposites.

Comparative example 3 (remove all nickel oxide, only lignin charcoal) proves that only lignin charcoal is difficult to obtain excellent electrochemical performance.

Take 500 g of sulfuric acid solution with a mass concentration of 10%, add 100 g of sodium lignosulfonate powder, stir while adding, and then filter to obtain the filtrate. Take 500g of ethanol solution with a mass concentration of 50%, add it to the obtained filtrate, stir while adding, then centrifuge at a speed of 10000rpm for 10min, pour off the supernatant, and transfer the centrifugal precipitate to a 50°C infrared drying oven Dry in medium for 24 hours to obtain purified sodium lignosulfonate with a sulfonation degree greater than 2.0 mmol/g.

Preparation 100g mass concentration is 10% above-mentioned purified sodium lignosulfonate solution, 30g mass concentration is 10% nickel chloride solution, 30g mass concentration is 10% sodium carbonate solution, 3g mass concentration is 30% p-aminobenzene Sodium sulfonate solution and 3g of formaldehyde solution with a mass concentration of 40%, using a peristaltic pump, slowly add sodium carbonate solution, sodium p-aminobenzenesulfonate solution, nickel chloride solution, and formaldehyde solution to the purification process at a rate of 2mL/min. Sodium lignosulfonate solution, stirring while adding dropwise. After stirring for more than 20 minutes, the mixed solution was transferred to a hydrothermal kettle, placed in an air atmosphere of 120°C and heated for 2 hours, filtered and dried to obtain a lignin/nickel carbonate composite.

Transfer the above-prepared lignin/nickel carbonate composite to a carbonization furnace, in a nitrogen atmosphere, raise the temperature to 250°C at a rate of 5°C/min, keep it for 30min, and then raise it to 250°C at a rate of 5°C/min. 600°C, keep it for 2 hours, wait until it drops to room temperature, soak the carbonized product in 50% sulfuric acid solution for washing, then centrifuge at 10000rpm for 10min, pour off the supernatant, and transfer the centrifuged sediment to 50°C infrared Dry in an oven for 24 hours to prepare nano lignin carbon materials.

Comparative example 4 (unpurified sodium lignosulfonate, using sodium p-aminobenzenesulfonate and aldehyde compounds), proves the importance of sulfonation degree greater than 2.0mmol/g, proves that unpurified sodium lignosulfonate cannot be dissolved in solution Good dispersion in the medium, so that the generated nickel carbonate and lignin are unevenly dispersed, and the lignin char and nickel oxide particles formed after carbonization are larger and agglomerated seriously.

Preparation 100g mass concentration is 10% unpurified sodium lignosulfonate solution, 30g mass concentration is 10% nickel chloride solution, 30g mass concentration is 10% sodium carbonate solution, 3g mass concentration is 30% p-aminobenzene Sodium sulfonate solution and 3g of formaldehyde solution with a mass concentration of 40%, using a peristaltic pump, slowly add sodium carbonate solution, sodium p-aminobenzenesulfonate solution, nickel chloride solution, and formaldehyde solution to the untreated area at a rate of 2mL/min. To purify the sodium lignosulfonate solution, add it dropwise while stirring. After stirring for more than 20 minutes, the mixed solution was transferred to a hydrothermal kettle, placed in an air atmosphere of 120°C and heated for 2 hours, filtered and dried to obtain a lignin/nickel carbonate composite.

Transfer the above-prepared lignin/nickel carbonate composite to a carbonization furnace, in a nitrogen atmosphere, raise the temperature to 250°C at a rate of 5°C/min, keep it for 30min, and then raise it to 250°C at a rate of 5°C/min. Keep at 600°C for 2 hours. When it drops to room temperature, soak the charred product in deionized water and wash it, then centrifuge it at 10,000 rpm for 10 minutes, pour off the supernatant, and transfer the centrifuged sediment to an infrared oven at 50°C for 24 hours. , to prepare lignin carbon/nickel oxide nanocomposites.

Comparative example 5 (purification of sodium lignosulfonate, without using sodium p-aminobenzenesulfonate and aldehydes), proves that the cross-linking of sodium p-aminobenzenesulfonate and lignin can improve the structural strength, and can form lignin charcoal after carbonization /Nickel oxide nanocomposites, but the structural strength is insufficient.

Take 500 g of sulfuric acid solution with a mass concentration of 10%, add 100 g of sodium lignosulfonate powder, stir while adding, and then filter to obtain the filtrate. Take 500g of ethanol solution with a mass concentration of 50%, add it to the obtained filtrate, stir while adding, then centrifuge at a speed of 10000rpm for 10min, pour off the supernatant, and transfer the centrifugal precipitate to a 50°C infrared drying oven Dry in medium for 24 hours to obtain purified sodium lignosulfonate with a sulfonation degree greater than 2.0 mmol/g.

Preparation 100g mass concentration is that the above-mentioned purified sodium lignosulfonate solution of 10%, 30g mass concentration are 10% nickel chloride solution and 30g mass concentration are 10% sodium carbonate solution, use peristaltic pump to mix sodium carbonate solution, chloride The nickel solution was slowly added dropwise to the purified sodium lignosulfonate solution successively at a rate of 2 mL/min, and stirred while dropping. After stirring for more than 20 minutes, the mixed solution was transferred to a hydrothermal kettle, placed in an air atmosphere of 120°C and heated for 2 hours, filtered and dried to obtain a lignin/nickel carbonate composite.

Transfer the above-prepared lignin/nickel carbonate composite to a carbonization furnace, in a nitrogen atmosphere, raise the temperature to 250°C at a rate of 5°C/min, keep it for 30min, and then raise it to 250°C at a rate of 5°C/min. Keep at 600°C for 2 hours. When it drops to room temperature, soak the charred product in deionized water and wash it, then centrifuge it at 10,000 rpm for 10 minutes, pour off the supernatant, and transfer the centrifuged sediment to an infrared oven at 50°C for 24 hours. , to prepare lignin carbon/nickel oxide nanocomposites.

Comparative example 6 (purification of sodium lignosulfonate, using sodium p-aminobenzenesulfonate, condensation under normal pressure using aldehyde compounds), proves that the compound obtained by conventional crosslinking can increase the molecular weight of lignin, but cannot effectively coat Nickel carbonate, leading to agglomeration of nickel carbonate.

Take 500 g of sulfuric acid solution with a mass concentration of 10%, add 100 g of sodium lignosulfonate powder, stir while adding, and then filter to obtain the filtrate. Take 500g of ethanol solution with a mass concentration of 50%, add it to the obtained filtrate, stir while adding, then centrifuge at a speed of 10000rpm for 10min, pour off the supernatant, and transfer the centrifugal precipitate to a 50°C infrared drying oven Dry in medium for 24 hours to obtain purified sodium lignosulfonate with a sulfonation degree greater than 2.0 mmol/g.

Preparation 100g mass concentration is 10% above-mentioned purified sodium lignosulfonate solution, 30g mass concentration is 10% nickel chloride solution, 30g mass concentration is 10% sodium carbonate solution, 3g mass concentration is 30% p-aminobenzene Sodium sulfonate solution and 3g of formaldehyde solution with a mass concentration of 40%, using a peristaltic pump, slowly add sodium carbonate solution, sodium p-aminobenzenesulfonate solution, nickel chloride solution, and formaldehyde solution to the purification process at a rate of 2mL/min. Sodium lignosulfonate solution, stirring while adding dropwise. After stirring for more than 20 minutes, the mixed solution was transferred to a three-necked flask, heated and stirred in an oil bath at 120° C. for 2 hours, filtered and dried to obtain a lignin/nickel carbonate composite.

Transfer the above-prepared lignin/nickel carbonate composite to a carbonization furnace, in a nitrogen atmosphere, raise the temperature to 250°C at a rate of 5°C/min, keep it for 30min, and then raise it to 250°C at a rate of 5°C/min. Keep at 600°C for 2 hours. When it drops to room temperature, soak the charred product in deionized water and wash it, then centrifuge it at 10,000 rpm for 10 minutes, pour off the supernatant, and transfer the centrifuged sediment to an infrared oven at 50°C for 24 hours. , to prepare lignin carbon/nickel oxide nanocomposites.

Comparative example 7 (purification of sodium lignosulfonate, using sodium p-aminobenzenesulfonate, no aldehyde compounds), illustrates that only using sodium p-aminobenzenesulfonate can not improve the structural strength.

Take 500 g of sulfuric acid solution with a mass concentration of 10%, add 100 g of sodium lignosulfonate powder, stir while adding, and then filter to obtain the filtrate. Take 500g of ethanol solution with a mass concentration of 50%, add it to the obtained filtrate, stir while adding, then centrifuge at a speed of 10000rpm for 10min, pour off the supernatant, and transfer the centrifugal precipitate to a 50°C infrared drying oven Dry in medium for 24 hours to obtain purified sodium lignosulfonate with a sulfonation degree greater than 2.0 mmol/g.

Preparation 100g mass concentration is 10% above-mentioned purified sodium lignosulfonate solution, 30g mass concentration is 10% nickel chloride solution, 30g mass concentration is 10% sodium carbonate solution and 3g mass concentration is 30% p-aminobenzene For sodium sulfonate solution, use a peristaltic pump to slowly add sodium carbonate solution, sodium p-aminobenzenesulfonate solution, and nickel chloride solution into the purified sodium lignosulfonate solution successively at a rate of 2 mL/min, and stir while adding . After stirring for more than 20 minutes, the mixed solution was transferred to a hydrothermal kettle, placed in an air atmosphere of 120°C and heated for 2 hours, filtered and dried to obtain a lignin/nickel carbonate composite.

Transfer the above-prepared lignin/nickel carbonate composite to a carbonization furnace, in a nitrogen atmosphere, raise the temperature to 250°C at a rate of 5°C/min, keep it for 30min, and then raise it to 250°C at a rate of 5°C/min. Keep at 600°C for 2 hours. When it drops to room temperature, soak the charred product in deionized water and wash it, then centrifuge it at 10,000 rpm for 10 minutes, pour off the supernatant, and transfer the centrifuged sediment to an infrared oven at 50°C for 24 hours. , to prepare lignin carbon/nickel oxide nanocomposites.

Comparative example 8: changing the order of addition, it is proved that the correct order of addition is beneficial to the nucleation of nickel carbonate, and sodium carbonate must be added first to provide an alkaline environment.

Take 500 g of sulfuric acid solution with a mass concentration of 10%, add 100 g of sodium lignosulfonate powder, stir while adding, and then filter to obtain the filtrate. Take 500g of ethanol solution with a mass concentration of 50%, add it to the obtained filtrate, stir while adding, then centrifuge at a speed of 10000rpm for 10min, pour off the supernatant, and transfer the centrifugal precipitate to a 50°C infrared drying oven Dry in medium for 24 hours to obtain purified sodium lignosulfonate with a sulfonation degree greater than 2.0 mmol/g.

Preparation 100g mass concentration is 10% above-mentioned purified sodium lignosulfonate solution, 30g mass concentration is 10% nickel chloride solution, 30g mass concentration is 10% sodium carbonate solution, 3g mass concentration is 30% p-aminobenzene Sodium sulfonate solution and 3g of formaldehyde solution with a mass concentration of 40% were slowly added dropwise to the purification solution at a rate of 2mL/min in sequence using a peristaltic pump to Sodium lignosulfonate solution, stirring while adding dropwise. After stirring for more than 20 minutes, the mixed solution was transferred to a hydrothermal kettle, placed in an air atmosphere of 120°C and heated for 2 hours, filtered and dried to obtain a lignin/nickel carbonate composite.

Transfer the above-prepared lignin/nickel carbonate composite to a carbonization furnace, in a nitrogen atmosphere, raise the temperature to 250°C at a rate of 5°C/min, keep it for 30min, and then raise it to 250°C at a rate of 5°C/min. Keep at 600°C for 2 hours. When it drops to room temperature, soak the charred product in deionized water and wash it, then centrifuge it at 10,000 rpm for 10 minutes, pour off the supernatant, and transfer the centrifuged sediment to an infrared oven at 50°C for 24 hours. , to prepare lignin carbon/nickel oxide nanocomposites.

Comparative example 9 (purification of sodium lignosulfonate, without using sodium p-aminobenzenesulfonate, using aldehyde compounds), proves that only using aldehyde compounds will produce certain crosslinking, accompanied by certain agglomeration, and the structural strength cannot be effectively improved .

Take 500 g of sulfuric acid solution with a mass concentration of 10%, add 100 g of sodium lignosulfonate powder, stir while adding, and then filter to obtain the filtrate. Take 500g of ethanol solution with a mass concentration of 50%, add it to the obtained filtrate, stir while adding, then centrifuge at a speed of 10000rpm for 10min, pour off the supernatant, and transfer the centrifugal precipitate to a 50°C infrared drying oven Dry in medium for 24 hours to obtain purified sodium lignosulfonate with a sulfonation degree greater than 2.0 mmol/g.

Preparation 100g mass concentration is that the above-mentioned purified lignosulfonate sodium solution of 10%, 30g mass concentration are 10% nickel chloride solution, 30g mass concentration are 10% sodium carbonate solution and 3g mass concentration are 40% formaldehyde solution, After fully stirring, use a peristaltic pump to slowly add sodium carbonate solution, nickel chloride solution, and formaldehyde solution into the purified sodium lignosulfonate solution successively at a rate of 2 mL/min, and stir while adding. After stirring for more than 20 minutes, the mixed solution was transferred to a hydrothermal kettle, placed in an air atmosphere of 120°C and heated for 2 hours, filtered and dried to obtain a lignin/nickel carbonate composite.

Transfer the above-prepared lignin/nickel carbonate composite to a carbonization furnace, in a nitrogen atmosphere, raise the temperature to 250°C at a rate of 5°C/min, keep it for 30min, and then raise it to 250°C at a rate of 5°C/min. Keep at 600°C for 2 hours. When it drops to room temperature, soak the charred product in deionized water and wash it, then centrifuge it at 10,000 rpm for 10 minutes, pour off the supernatant, and transfer the centrifuged sediment to an infrared oven at 50°C for 24 hours. , to prepare lignin carbon/nickel oxide nanocomposites.

Comparative Example 10 (using sodium hydroxide to provide an alkaline environment) proves that the use of alkaline substances such as sodium hydroxide or ammonia can improve the dispersibility of lignosulfonate, but the nickel hydroxide it generates in combination with nickel ions acts as The water vapor released by the template agent during the carbonization process cannot achieve a good pore-forming effect and inhibit the agglomeration of lignin charcoal. Uneven thickness.

Take 500 g of sulfuric acid solution with a mass concentration of 10%, add 100 g of sodium lignosulfonate powder, stir while adding, and then filter to obtain the filtrate. Take 500g of ethanol solution with a mass concentration of 50%, add it to the obtained filtrate, stir while adding, then centrifuge at a speed of 10000rpm for 10min, pour off the supernatant, and transfer the centrifugal precipitate to a 50°C infrared drying oven Dry in medium for 24 hours to obtain purified sodium lignosulfonate with a sulfonation degree greater than 2.0 mmol/g.

Preparation 100g mass concentration is that the above-mentioned purified sodium lignosulfonate solution of 10%, 30g mass concentration are 10% nickel chloride solution, 30g mass concentration are 10% sodium hydroxide solution, 3g mass concentration are 30% p-amino Sodium benzenesulfonate solution and 3g of formaldehyde solution with a mass concentration of 40%, use a peristaltic pump to slowly add sodium hydroxide solution, nickel chloride solution, sodium p-aminobenzenesulfonate solution, and formaldehyde solution at a rate of 2mL/min Add it to the purified sodium lignosulfonate solution, and stir while adding it dropwise. After stirring for more than 20 minutes, the mixed solution was transferred to a hydrothermal kettle, placed in an air atmosphere at 120°C and heated for 2 hours, filtered and dried to obtain a lignin/nickel hydroxide composite.

Transfer the above-prepared lignin/nickel hydroxide composite to a carbonization furnace, raise the temperature to 250°C at a rate of 5°C/min in a nitrogen atmosphere, keep it for 30 minutes, and then raise the temperature to 250°C at a rate of 5°C/min. Keep at 600°C for 2 hours, wait for it to cool down to room temperature, soak the charred product in deionized water and wash, then centrifuge at 10,000rpm for 10min, pour off the supernatant, and transfer the centrifuged sediment to an infrared oven at 50°C for drying After 24 hours, the lignin carbon/nickel oxide nanocomposite material was prepared.

Comparative Example 11 (using potassium oxalate to provide an alkaline environment) proves that the hydrolysis of oxalate is relatively weak in alkalinity, and may not be as effective as carbonate for the three-dimensional network structure of lignosulfonate. Combined with nickel ions to form nickel oxalate as a template in A large amount of carbon monoxide and carbon dioxide released during the carbonization process will destroy the material structure, resulting in a decrease in structural strength.

Take 500 g of sulfuric acid solution with a mass concentration of 10%, add 100 g of sodium lignosulfonate powder, stir while adding, and then filter to obtain the filtrate. Take 500g of ethanol solution with a mass concentration of 50%, add it to the obtained filtrate, stir while adding, then centrifuge at a speed of 10000rpm for 10min, pour off the supernatant, and transfer the centrifugal precipitate to a 50°C infrared drying oven Dry in medium for 24 hours to obtain purified sodium lignosulfonate with a sulfonation degree greater than 2.0 mmol/g.

Preparation 100g mass concentration is 10% above-mentioned purified sodium lignosulfonate solution, 30g mass concentration is 10% nickel chloride solution, 30g mass concentration is 10% potassium oxalate solution, 3g mass concentration is 30% p-aminobenzene Sodium sulfonate solution and 3g of formaldehyde solution with a mass concentration of 40%, after fully stirring, use a peristaltic pump to slowly transfer the potassium oxalate solution, nickel chloride solution, sodium p-aminobenzenesulfonate solution, and formaldehyde solution at a rate of 2mL/min. Add it dropwise to the purified sodium lignosulfonate solution, and stir while adding it. After stirring for more than 20 minutes, the mixed solution was transferred to a hydrothermal kettle, placed in an air atmosphere at 120°C and heated for 2 hours, filtered and dried to obtain a lignin/nickel hydroxide composite.

Transfer the above-prepared lignin/nickel hydroxide composite to a carbonization furnace, raise the temperature to 250°C at a rate of 5°C/min in a nitrogen atmosphere, keep it for 30 minutes, and then raise the temperature to 250°C at a rate of 5°C/min. Keep at 600°C for 2 hours, wait for it to cool down to room temperature, soak the charred product in deionized water and wash, then centrifuge at 10,000rpm for 10min, pour off the supernatant, and transfer the centrifuged sediment to an infrared oven at 50°C for drying After 24 hours, the lignin carbon/nickel oxide nanocomposite material was prepared.

The morphology and size of the samples of the present invention are determined by a field emission scanning electron microscope (SEM, HitachiSU8220) and a high resolution field emission transmission electron microscope (HRTEM, JEOL JEM-2100F, 200kV equipped with an energy spectrometer (ThermoFisher Scientific, NORAN System 7) )test.

The battery assembly adopts half-cell assembly, the model is CR2032. The composition of the positive electrode material is 80wt% of active material, 10wt% of conductive carbon black, 10wt% of polyvinylidene fluoride (PVDF), and is coated with N-methyl-2-pyrrolidone (NMP) as a solvent, wherein the active material is the above-mentioned Examples and Comparative Examples Prepared lignin carbon/nickel oxide nanocomposite material. The lithium sheet is used as the counter electrode, the electrolyte is 1mol/L LiPF ₆ as the solute, and ethylene carbonate (EC), ethyl methyl carbonate (EMC) and dimethyl carbonate (DMC) are used as the solvent at a volume ratio of 1:1:1. formulated. The entire assembly process of the lithium-ion half-cell was performed in an argon-protected glove box (Super 1220/750, MIKROUNA). Use the Neware battery performance test system to test the constant current charge/discharge performance of the battery at a current density of 200mA/g in the voltage range of 0.01 ~ 3V, and the rate performance test is at 50mA/g, 100mA/g, 250mA/g, 500mA/g And 1000mA/g current density is completed.

The lignin carbon/nickel oxide nanocomposite material prepared in Example 1 was applied to the negative electrode material of lithium-ion battery and subjected to material characterization and electrochemical testing. The results are shown in Table 1 and Figures 1-4.

Table 1 is a comparison of the cycle performance of the lignin carbon/nickel oxide nanocomposites prepared in the above examples and the samples prepared in the following comparative examples.

Table 1 Cyclic performance of lignin carbon/nickel oxide nanocomposites and comparative examples 1-11

Table 1 explains:

The lignin carbon/nickel oxide nanocomposite material prepared in Example 1 has a discharge specific capacity of 1065mAh/g after 100 cycles at a current density of 200mA/g, and has good cycle stability, which is significantly better than similar materials, and all The cycle performance of the samples in the examples is better than that of other comparative samples, which is mainly due to the small particle size of the lignin carbon/nickel oxide nanocomposite material, the good coating of the nano-nickel oxide by the nano-lignin carbon and the nano-lignin carbon skeleton. Excellent structural strength, lignin charcoal and nickel oxide play a synergistic effect.

The cycle performance data of the comparative sample in Table 1 shows that after 100 cycles at 200mA/g, the pure nickel oxide of comparative example 1 is still easy to swell and agglomerate because it is not coated with lignin carbon, and its discharge ratio The capacity is only 101mAh/g; in Comparative Example 2, due to the direct use of nickel carbonate, the dispersion of nickel carbonate and lignin was uneven, and the lignin could not be effectively coated. Only 673mAh/g; comparative example 3 removed all the nickel oxide by acid etching, only lignin carbon was retained, lacking the capacity contribution of nickel oxide, and its discharge specific capacity was only 582mAh/g; comparative example 4 was due to the use of unpurified Sodium lignosulfonate, whose sulfonation degree is less than 2.0mmol/g, cannot be well dispersed in the solution, resulting in uneven dispersion of nickel carbonate and lignin, and lignin charcoal and nickel oxide generated by carbonization have larger particle sizes , the agglomeration is serious, and its discharge specific capacity is only 747mAh/g; Comparative Example 5 does not use sodium p-aminobenzenesulfonate and aldehyde compounds to cross-link with sodium lignosulfonate, and the lignin carbon/nickel oxide formed after carbonization The structural strength of the nanocomposite material is insufficient, and its specific discharge capacity is 822mAh/g; Comparative Example 6, because sodium lignosulfonate and sodium p-aminobenzenesulfonate carry out condensation cross-linking under normal pressure, only increased the molecular weight of lignin, cannot Stabilizing the three-dimensional network skeleton of lignin makes it difficult to effectively coat, disperse and stabilize nickel carbonate, resulting in the agglomeration of nickel carbonate, and its discharge specific capacity is only 709mAh/g; since comparative example 7 does not use aldehyde compounds, only amino Sodium benzenesulfonate can't carry out condensation cross-linking with sodium lignosulfonate, and then can't improve the structural strength of lignin carbon/nickel oxide nanocomposite material, and its specific discharge capacity is 834mAh/g; Sodium carbonate is not added first to provide an alkaline environment, so that the three-dimensional network skeleton of sodium lignosulfonate is not expanded, the dispersion is poor, and the generated nickel carbonate is limited in it. The average particle size of lignin carbon and nickel oxide obtained after carbonization Larger, serious agglomeration, and its specific discharge capacity is only 692mAh/g. In comparative example 9, because sodium p-aminobenzenesulfonate is not used, only aldehydes and sodium lignosulfonate are incompletely condensed and cross-linked, and the structural strength of lignin carbon/nickel oxide nanocomposites is less improved. In addition, due to Without the dispersion and stabilization effect of sodium p-aminobenzenesulfonate, the lignin was agglomerated to a certain extent, and its specific discharge capacity was 837mAh/g. Comparative example 10 is owing to use sodium hydroxide to provide alkaline environment, though can improve the dispersibility of sodium lignosulfonate, but this moment is combined with nickel ion and what generates is nickel hydroxide, and it is formed in the carbonization process as templating agent The released water vapor cannot effectively form pores and inhibit the agglomeration of lignin carbon, resulting in certain agglomeration of the obtained lignin carbon/nickel oxide nanocomposite structure, too little surface pore structure, lack of active sites for lithium storage, and its discharge specific capacity Only 498mAh/g. Comparative Example 11 uses potassium oxalate to provide an alkaline environment, and the solution obtained by its hydrolysis is relatively weak in alkalinity, which is not conducive to the effective development of the three-dimensional network skeleton structure of sodium lignosulfonate. In addition, the oxalic acid produced by combining with nickel ions Nickel as a template will release excess carbon monoxide and carbon dioxide gas during the carbonization process, destroying the structure of lignin carbon, resulting in a decrease in the structural strength of lignin carbon/nickel oxide nanocomposites, and its specific discharge capacity is 616mAh/g.

Fig. 1 is the constant current charge and discharge diagram of the lignin carbon/nickel oxide nanocomposite material that the embodiment of the present invention 1 makes, and the charge and discharge specific capacity of lignin carbon/nickel oxide nanocomposite under the current density of 200mA/g for the first time is respectively 912mAh/g and 1688mAh/g, after 100 cycles, the reversible specific capacity is 1065mAh/g, and the capacity is basically stable in the subsequent cycle process, which is mainly due to the good dispersion of nano-nickel oxide and the effect of lignin carbon on nano-oxidation The good coating of nickel and the synergistic effect of nano-nickel oxide and nano-lignin carbon on electrochemical performance.

Fig. 2 is the rate performance figure of the lignin carbon/nickel oxide nanocomposite material that the embodiment 1 of the present invention makes, under the current density of 50mA/g, 100mA/g, 250mA/g, 500mA/g and 1000mA/g, wood The specific discharge capacities of plain carbon/nickel oxide nanocomposites are 1066mAh/g, 930mAh/g, 720mAh/g, 585mAh/g and 446mAh/g, respectively. In addition, after the current density dropped from 1000mA/g to 50mA/g, it remained stable quickly, and the discharge specific capacity was 1125mAh/g, which indicated that the lignin carbon/nickel oxide nanocomposite had excellent rate performance and reversible performance, and could be applied to different working conditions.

Fig. 3 is an SEM image of the lignin carbon/nickel oxide nanocomposite material prepared in Example 1 of the present invention. It can be seen from the figure that the particle size of the lignin carbon/nickel oxide nanocomposite material is less than 10nm. The particle size distribution diagram can be obtained by statistical analysis of the particle size of the composite material particles in the figure. The average particle size of the composite material is 6.27nm, and the particle size of most particles is less than 7nm.

Fig. 4 is a TEM image of the lignin carbon/nickel oxide nanocomposite material prepared in Example 1 of the present invention. It can be observed from the figure that the nano-nickel oxide particles are well dispersed, and the particle size of most nickel oxides is less than 5nm.

The above-mentioned embodiment is a preferred embodiment of the present invention, but the embodiment of the present invention is not limited by the above-mentioned embodiment, and any other changes, modifications, substitutions, combinations, Simplifications should be equivalent replacement methods, and all are included in the protection scope of the present invention.

Claims (10)

1. A preparation method of a lignin carbon/nickel oxide nano composite material is characterized by comprising the following steps:

(1) Carrying out acid treatment on lignosulfonate by using a sulfuric acid solution with the mass concentration of 4-20%, collecting filtrate, adding an ethanol solution with the mass concentration of more than or equal to 50% to separate out precipitate, centrifuging and drying to obtain purified lignosulfonate with the sulfonation degree of more than 2.0 mmol/g;

(2) Dissolving the purified lignosulfonate obtained in the step (1) in water, then sequentially adding a carbonate solution, a sulfanilate solution, a nickel salt solution and an aldehyde compound solution at the speed of 1-10 mL/min, uniformly mixing, carrying out hydrothermal reaction in a hydrothermal kettle at the temperature of 100-200 ℃ for 1-6 h, filtering, and drying to obtain a lignin/nickel carbonate compound;

(3) Carbonizing the lignin/nickel carbonate compound, then centrifugally washing and drying to obtain a lignin carbon/nickel oxide nano composite material;

in the step (2), the mass ratio of the purified lignosulfonate, carbonate, sulfanilate, nickel salt and aldehyde compound is 10g: 1-10 g: 0.5-10 g: 1-10 g:0.5 to 10g.

2. The method for preparing the lignin carbon/nickel oxide nanocomposite material according to claim 1, wherein the mass concentration of the solution obtained by dissolving the purified lignosulfonate in water in the step (2) is 10-40%; the mass concentration of the nickel salt solution is 5-20%; the mass concentration of the carbonate solution is 5-20%; the mass concentration of the sulfanilic acid salt solution is 10-40%; the mass concentration of the aldehyde compound solution is 20-50%.

3. The method for preparing the ligno-char/nickel oxide nanocomposite material according to claim 1, wherein the mass ratio of the purified lignosulfonate, carbonate, sulfanilate, nickel salt and aldehyde compound in the step (2) is 10g: 1-5 g: 0.5-2 g: 1-5 g: 0.5-2 g; the mass concentration of the sulfuric acid solution in the step (1) is 5-10%.

4. The preparation method of the lignin carbon/nickel oxide nanocomposite material according to claim 1, wherein the carbonization procedure in the step (3) is as follows: heating to 120-350 deg.c at 5 deg.c/min, maintaining for 20-60 min, heating to 500-700 deg.c at 5-10 deg.c/min, maintaining for 0.5-5 hr, and cooling to room temperature.

5. The method for preparing the lignin carbon/nickel oxide nanocomposite material according to claim 1, wherein the inorganic nickel salt in the step (2) is at least one of nickel chloride, nickel nitrate, nickel sulfate and nickel acetate; the carbonate is at least one of potassium carbonate, sodium carbonate, ammonium carbonate, potassium bicarbonate, sodium bicarbonate and ammonium bicarbonate; the aldehyde compound is at least one of formaldehyde, acetaldehyde and propionaldehyde.

6. The method for preparing the lignin carbon/nickel oxide nanocomposite as claimed in claim 1, wherein the addition rates of the carbonate solution, the sulfanilate solution, the nickel salt solution and the aldehyde compound solution in the step (2) are all 2-6 mL/min; the temperature of the hydrothermal treatment is 110-180 ℃, and the time is 1-4 h.

7. The method for preparing the lignin-carbon/nickel oxide nanocomposite according to claim 1, wherein the lignosulfonate in the step (1) is at least one of sodium lignosulfonate, calcium lignosulfonate and magnesium lignosulfonate extracted from red liquor of acid pulping and sulfonated alkali lignin and sulfomethylated alkali lignin obtained by sulfonating/sulfomethylating black liquor of alkaline pulping; the mass ratio of the lignosulfonate to the sulfuric acid solution to the ethanol solution is 1: 2.5-12.5: 2.5 to 5;

and (4) carbonizing in the step (3) under the atmosphere of nitrogen or inert gas.

8. The method for preparing the lignin carbon/nickel oxide nanocomposite material according to claim 2, wherein the mass concentration of the solution obtained by dissolving the purified lignosulfonate in water in the step (2) is 10-30%; the mass concentration of the nickel salt solution is 5-10%; the mass concentration of the carbonate solution is 5-10%; the mass concentration of the sulfanilic acid salt solution is 20-30%; the mass concentration of the aldehyde compound solution is 30-40%.

9. A lignin char/nickel oxide nanocomposite produced by the method of any one of claims 1 to 8.

10. The application of the lignin carbon/nickel oxide nanocomposite of claim 9 in the fields of lithium ion battery negative electrode materials, supercapacitors and photoelectrocatalysis.

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