CN116770611A

CN116770611A - Method for extracting cellulose from biomass, method for preparing hard carbon material by using cellulose, battery cathode and sodium ion battery

Info

Publication number: CN116770611A
Application number: CN202310720879.6A
Authority: CN
Inventors: 赵天宝; 刘琥瑜; 冯宁博
Original assignee: Chengdu Lithium Energy Technology Co ltd
Current assignee: Chengdu Lithium Energy Technology Co ltd
Priority date: 2023-06-16
Filing date: 2023-06-16
Publication date: 2023-09-19

Abstract

The invention relates to the technical field of hard carbon materials and provides a method for extracting cellulose from biomass, which includes the following steps: after crushing the biomass raw material, heating and ultrasonicating it in an alkaline solution to obtain mixture A; After washing to neutrality and drying, it is put into an acidic solution and heated and stirred to obtain mixture B; S3. After washing mixture B to neutrality and drying, precursor C is obtained; the invention also provides a preparation of hard carbon materials The method includes the following steps: carbonizing precursor C at high temperature for a certain period of time under protective gas to obtain a hard carbon material, which has excellent conductivity; a sodium ion battery negative electrode including the carbon material, and a sodium ion battery including the negative electrode are also provided Batteries with excellent electrochemical properties.

Description

Method for extracting cellulose from biomass, method for preparing hard carbon material by using cellulose, battery cathode and sodium ion battery

Technical Field

The invention relates to the technical field of biomass treatment, in particular to a method for extracting cellulose from biomass, a method for preparing a hard carbon material by using the cellulose, a battery cathode and a sodium ion battery.

Background

Along with the increasing aggravation of energy crisis and the continuous enhancement of environmental protection consciousness of people, the development of clean energy and efficient and low-cost energy storage modes becomes a research hot spot in recent years. Sodium ion batteries are becoming a research direction for new generation energy storage materials by virtue of similar performance as lithium ion batteries and cost advantages. At present, many positive electrode materials for sodium ion batteries have been developed, but development of a negative electrode material suitable for practical application of sodium ion batteries still faces many challenges. Therefore, research into high-performance electrode materials is important for development of various sodium ion batteries.

The currently commercialized negative electrode materials are mainly hard carbon materials, have a macroscopic non-graphite structure, and contain graphite interlayers in the microstructure, and are considered to be the most practical negative electrode materials of sodium ion batteries at present. The biomass base is used as one of the precursors of the hard carbon material, and has the advantages of wide source, sustainable development, low price and the like. However, a large amount of biomass waste is generated each year, most of the biomass waste is discarded or burned, resources are wasted and the environment is polluted, and the preparation of the carbon material by taking the biomass waste as the raw material can save the cost and can also relieve the environmental problem caused by the mass burning of the waste.

Among these biomass wastes, lignocellulose waste occupies a large part, and cellulose is widely used in various fields because of its low cost and easy processing as a biomass which is widely available, in large quantities, green, and degradable and renewable. However, the special structure formed by lignin and hemicellulose is wrapped, so that the cellulose is difficult to directly use and can be applied only by being exposed through pretreatment.

Disclosure of Invention

In view of the above, the invention provides a method for extracting cellulose from biomass and preparing a hard carbon material with high performance by using a physical method to assist an acid-base solution from the viewpoints of low cost and good sustainability.

A method for extracting cellulose from biomass, comprising the steps of:

s1, after crushing and screening biomass raw materials, putting the biomass raw materials into an alkaline solution (comprising a mixture of sodium hydroxide and sodium percarbonate with a mass ratio of 1:1-1.2), and heating and ultrasonic treatment in ultrasonic equipment at a temperature of 30-70 ℃ for 3-5 hours to obtain a mixture A; wherein the mass ratio of the biomass raw material to the alkaline solution is 1:3-8, and the mass fraction of the alkaline solution is 4-6%;

s2, washing the mixture A to be neutral, drying, putting the mixture A into an acidic solution (comprising one of hydrochloric acid, sulfuric acid, formic acid acetic acid and the like), and heating and stirring the mixture A for 2 to 4 hours at the temperature of 20 to 40 ℃ to obtain a mixture B;

s3, washing the mixture B with deionized water to be neutral and drying to obtain a precursor C.

Further, biomass feedstocks include, but are not limited to, bamboo, peanut hulls, waste straw, waste wood, coconut shells.

The invention adopts the ultrasonic and heating physical method to assist the acid-base solution to treat the biomass, firstly, the precursor can be loosened more easily, the alkali solution is immersed, the precursor and the alkali solution are promoted to be fully mixed, secondly, the hydrogen bond network structure among cellulose molecules is destroyed under the actions of ultrasonic cavitation, machinery and the like, the order degree of the cellulose molecules is reduced, and the removal of lignin, hemicellulose and other components is facilitated.

Firstly, an alkaline solution is used for treating a biomass raw material, hydrogen bonds in lignocellulose are weakened or destroyed by utilizing-OH, lignin is dissolved, part of hemicellulose can be dissolved, cellulose is swelled, a carbon network plane structure is formed by the cellulose at a high temperature, and C=O functional groups contained in the cellulose pyrolytic carbon provide more active sites, so that the rate capability is improved; then washing to neutrality, then adopting acid solution to treat, breaking internal structure of lignocellulose by splitting glycosidic bond to make cellulose be better extracted, and forming larger interlayer spacing to facilitate intercalation of sodium ions during high-temperature pyrolysis; in addition, sodium percarbonate generates sodium carbonate and hydrogen peroxide in aqueous solution, and under alkaline condition, the decomposition rate of hydrogen peroxide increases, thereby synergistically exerting the cellulose extraction effect

A preparation method of a hard carbon material comprises the following steps: and heating the precursor C prepared by the preparation method to 1100-1600 ℃ at a heating rate of 1-5 ℃/min under the condition of protective gas (such as nitrogen), and carbonizing for 2-5 hours to obtain the hard carbon material.

The biomass-based hard carbon material is prepared according to the preparation method.

A sodium ion battery negative electrode comprising the biomass-based hard carbon material;

and/or, further comprising a conductive agent and a binder;

and/or the mass ratio of the biomass-based hard carbon material, the conductive agent and the binder is 80-95: 2-10: 1 to 3.5:2 to 6.5; preferably 92:3:1.5:3.5;

a sodium ion battery comprises the sodium ion battery cathode.

The technical scheme of the embodiment of the invention has at least the following advantages and beneficial effects:

1. the invention adopts the ultrasonic and heating physical method to assist the acid-base solution to treat the biomass, firstly, the precursor can be loosened more easily, the alkali solution is immersed, the precursor and the alkali solution are promoted to be fully mixed, secondly, the hydrogen bond network structure among cellulose molecules is destroyed under the actions of ultrasonic cavitation, machinery and the like, the order degree of the cellulose molecules is reduced, and the removal of lignin, hemicellulose and other components is facilitated. The treatment method of the invention can effectively remove impurities in biomass, and can retain the original natural structure of biomass; and a larger interlayer spacing can be formed during pyrolysis at high temperature, so that sodium ions can be conveniently embedded, and C=O functional groups contained in the cellulose pyrolytic carbon provide more active sites, so that the rate capability is improved.

2. The sodium ion battery has excellent capacity and multiplying power, and improves the electrochemical performance of the battery.

Drawings

FIG. 1 is an XRD schematic of a biomass-based hard carbon material prepared in example 1 of the present invention;

FIG. 2 is a charge-discharge curve of the sodium ion battery prepared in example 1 of the present invention;

fig. 3 is a scanning electron microscope image of the biomass-based hard carbon material prepared in example 1 of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below. The specific conditions are not noted in the examples and are carried out according to conventional conditions or conditions recommended by the manufacturer. The reagents or apparatus used were conventional products commercially available without the manufacturer's attention.

Example 1

The preparation method of the biomass-based hard carbon material comprises the following steps:

s1, crushing 10g of biomass raw material bamboo, sieving with a 400-mesh sieve, putting into 50ml of alkaline solution (comprising an equal proportion mixture of sodium hydroxide and sodium percarbonate), and heating and ultrasonic for 4 hours at the temperature of 30-70 ℃ in ultrasonic equipment to obtain a mixture A; the mass fraction of the alkaline solution is 5%;

s2, washing the mixture A to be neutral, drying, and then putting the mixture A into 100ml of 4mol/L hydrochloric acid, heating and stirring the mixture A for 3 hours at 30 ℃ to obtain a mixture B;

s3, washing the mixture B with deionized water to neutrality and drying to obtain a precursor C;

s4, placing the precursor C into a carbonization furnace to carry out high-temperature carbonization under the protection of nitrogen, wherein the carbonization temperature is 1300 ℃, and the carbonization time is 3 hours; gradient heating is carried out during high-temperature carbonization, and the heating rate is 3 ℃/min; obtaining a biomass-based hard carbon material;

s5, refining the obtained hard carbon material, wherein the diameter range is 1-10 mu m; then uniformly mixing a hard carbon material, a conductive agent (SP) and a binder (CMC, SBR) with a certain amount of deionized water according to a mass ratio of 85:6:5:4, and coating the mixture on a current collector to prepare a sodium ion battery negative electrode plate; the negative electrode plate of the sodium ion battery can be applied to the sodium ion battery.

Example 2

This embodiment differs from embodiment 1 in that: the biomass raw material is peanut shells; the feed-to-liquid ratio of the biomass raw material to the alkaline solution is 1:3.

Example 3

This embodiment differs from embodiment 1 in that: the biomass raw material is waste straw; the feed-to-liquid ratio of the biomass raw material to the alkaline solution is 1:8.

Example 4

This embodiment differs from embodiment 1 in that: the biomass raw material is waste wood; the carbonization temperature is 1500 ℃, and the carbonization time is 2 hours.

Comparative example 1

The difference between this comparative example and example 1 is that: and (3) crushing and screening the biomass raw material bamboo, and then directly placing the crushed and screened biomass raw material bamboo into a carbonization furnace to be carbonized at a high temperature of 1300 ℃ for 3 hours in a nitrogen atmosphere, so as to obtain the hard carbon material.

Comparative example 2

The difference between this comparative example and example 1 is that: no physical operations such as ultrasound and heating are performed.

Comparative example 3

The difference between this comparative example and example 1 is that: the alkaline solution treatment in S1 is not performed.

Comparative example 4

The difference between this comparative example and example 1 is that: the acidic solution treatment in S2 is not performed.

Experimental example

The hard carbon materials of examples 1 to 4 and comparative examples 1 to 4 were subjected to the relevant performance test, and the test results are shown in table 1;

the assembled sodium-ion batteries of examples 1 to 4 and comparative examples 1 to 4 were subjected to electrochemical performance test under a current density of 20mA g ^-1 The voltage range was 0-3V and the test results are shown in table 2.

TABLE 1 hard carbon material Properties of examples 1-4 and comparative examples 1-4

Table 2 electrochemical properties of assembled sodium-ion batteries of examples 1 to 4 and comparative examples 1 to 4

As can be seen from the data in tables 1 and 2:

from the results of example 1 and comparative examples 1 to 4, the hard carbon material prepared from cellulose extracted by the physical auxiliary acid-base solution method has excellent electrochemical properties. The physical assistance is adopted to completely remove impurities, lignin and hemicellulose, and the acid treatment is adopted to extract cellulose, so that impurities in raw materials can be removed cleanly, the spacing between hard carbon layers can be increased, the original natural structure is reserved by adopting the alkali solution treatment, the effects of activation and impurity removal are achieved, the transmission of ions and electrolyte is further enhanced, and the electrochemical performance is improved.

The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention, but various modifications and variations can be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for extracting cellulose from biomass, characterized by: the method comprises the following steps:

s1, crushing and screening a biomass raw material, putting the biomass raw material into an alkaline solution, and heating and ultrasonic for a period of time at a certain temperature to obtain a mixture A;

s2, washing the mixture A to be neutral, drying, and then putting the mixture A into an acid solution, heating and stirring for a period of time at a certain temperature to obtain a mixture B;

s3, washing the mixture B to be neutral and drying to obtain a precursor C.

2. The method of extracting cellulose from biomass as claimed in claim 1, wherein in S1, the ratio of the biomass raw material to the alkaline solution is 1:3-8.

3. The method of extracting cellulose from biomass as claimed in claim 2 wherein in S1 the alkaline solution comprises a mixture of sodium hydroxide and sodium percarbonate; the mass fraction of the alkaline solution is 4-6%.

4. The method for extracting cellulose from biomass as claimed in claim 1, wherein in S1, the heating temperature is 30-70 ℃; the ultrasonic time is 3-5h.

5. The method of claim 1, wherein in S2, the ratio of the mixture a to the acidic solution is 1:3-8.

6. The method of claim 1, wherein in S2, the acidic solution comprises one or more of hydrochloric acid, sulfuric acid, formic acid, acetic acid, and the like.

7. The method for extracting cellulose from biomass as claimed in claim 1, wherein in S2, the heating temperature is 20-40 ℃; and/or heating and stirring for 2-4h.

8. The preparation method of the hard carbon material is characterized by comprising the following steps of: heating the precursor C prepared by the preparation method of any one of claims 1-7 to 1100-1600 ℃ at a heating rate of 1-5 ℃/min under the atmosphere of protective gas, and carbonizing for 2-5h to obtain the hard carbon material.

9. A negative electrode of a sodium ion battery, which is characterized by comprising the hard carbon material prepared by the preparation method of claim 8, and further comprising a conductive agent and a binder;

the mass ratio of the hard carbon material to the conductive agent to the binder is 80-92: 3-10: 1.5 to 3.5:3.5 to 6.5.

10. A sodium ion battery comprising the negative electrode of claim 9.