CN107644988B - Cellulose in-situ carbon-based lithium battery aerogel and preparation method thereof - Google Patents

Abstract

The invention provides cellulose in-situ carbon-based lithium battery aerogel and a preparation method thereof, wherein the preparation method comprises the following steps: (1) dispersing a tin source in water to form a homogeneously dispersed tin solution system; (2) adding 4-10 parts by weight of hydroxyethyl cellulose into a tin solution system, stirring at normal temperature (3) adding an alkali solution into the viscous liquid, continuously stirring uniformly, adding a cross-linking agent, stirring uniformly at normal temperature, and finally polymerizing at normal temperature to form transparent or semitransparent blocky gel; (4) the prepared aerogel has excellent performance, has good gram capacity in a lithium battery cathode material, ensures that the aerogel has better preparation process and excellent specific surface area, has wide sources of preparation raw materials, simple preparation method and low preparation cost, and is expected to realize industrial large-scale production.

Description

Cellulose in-situ carbon-based lithium battery aerogel and preparation method thereof

technical field

The invention relates to the technical field of solid-state lithium batteries, in particular to a cellulose in-situ carbon-based lithium battery aerogel and a preparation method thereof.

Background technique

After decades of development, lithium batteries have become the most widely used energy storage units in daily life, mainly used in mobile phone batteries, notebook batteries and other digital products and battery vehicles. With the gradual lightweight, miniaturization and high integration of electronic products, the requirements for batteries are also getting higher and higher. The specific energy, shape and safety of batteries have greatly limited the development of current electronic products including mobile phones, notebook computers and drones. Therefore, the most urgent problem at present is to find a new type of high specific energy electrode material to improve the battery. In order to keep up with the development progress of related industries.

At present, the anode materials of new lithium batteries mainly include graphene materials, silicon carbon materials and tin carbon materials. Due to the high production cost of graphene materials, it is difficult to realize the industrial production of battery materials, and the volume expansion of silicon carbon materials during the charging and discharging process is too high. Da also limits its commercialization progress. Compared with the first two materials, tin-carbon materials are cheap and belong to one of the five major metals of gold, silver, copper, iron and tin. The production technology is mature and the commercialization prospect is good.

Elemental tin has good lithium storage performance, but it also faces the problem of volume expansion, so it is necessary to use carbon materials for treatment processes such as doping modification or coating. The doping currently used is mainly ball-milling compounding. The carbon source and the tin material are fully mixed in the environment of ball-milling to prepare particulate materials with a particle size of micro-nano level to improve the performance of the tin-carbon material. However, because the ball milling time is too long and the energy consumption is too large, it is difficult to industrialize large-scale production, which limits its application. Another method is the template method. First, some other substances are used to form a microscopic composite structure with the carbon source, and some special solvents are used to dissolve other substances to leave the porous carbon source microstructure, and then fill the tin source to form a carbon package. The structure of tin enables high-capacity anode materials. Compared with the previous method, the performance obtained by this method is better, but the preparation process is more complicated, the consistency of the product is difficult to be guaranteed, and there are some uncertain factors affecting the performance of the battery.

The performance of the negative electrode material of the battery plays a crucial role in the overall performance of the battery, and plays an indispensable role in the four major components of the lithium battery. The existing technology is mainly due to the limitation of production technology and production cost, and it is difficult to realize large-scale industrial production. In order to make up for the blank of the existing technology, the present invention provides a cellulose in-situ carbon-based lithium battery tin-carbon aerogel negative electrode material machine. Preparation.

SUMMARY OF THE INVENTION

In view of the above-mentioned problems existing in the current lithium battery negative electrode materials, the purpose of the present invention is to provide a cellulose in-situ carbon-based lithium battery aerogel and a preparation method thereof, using biomass raw material hydroxyethyl cellulose as the skeleton material of the negative electrode material , using epichlorohydrin and other chemical cross-linking agents for aerogels, adding tin source and alkaline solution to provide an alkaline environment, and completing the polymerization reaction of aerogels at room temperature or low temperature to form a gel material with a uniform surface and smooth surface , and then the gel material is dried, and finally carbonized to form a lithium battery aerogel negative electrode material.

In order to realize the above-mentioned purpose of the invention, the technical scheme of the present invention is as follows:

A preparation method of cellulose in-situ carbon-based lithium battery aerogel, comprising the following steps:

(1) at least one of nano-tin, tin tetrachloride, stannous chloride is dispersed in 60-100 weight portion water as tin source to form homogeneous dispersion tin solution system; The total amount of tin contained in the tin source is 2- 8 parts by weight;

(2) adding 4-10 parts by weight of hydroxyethyl cellulose to the tin solution system, stirring at room temperature to fully dissolve it to form a transparent or translucent viscous liquid;

(3) Add alkali solution to the viscous liquid and continue to stir evenly, then add 5-150 parts by weight of cross-linking agent and stir evenly at normal temperature, and finally polymerize at normal temperature to form a transparent or translucent bulk gel;

(4) drying the obtained gel, and then carbonizing, ball milling and washing the dried gel to obtain a cellulose in-situ carbon-based lithium battery aerogel.

As a preferred way, in the preparation method, nano-tin is prepared by reduction method, the raw material of nano-tin is one or more of tin chloride, stannous chloride or tin powder, and the reducing agent used is sodium borohydride or Potassium borohydride, the total amount of tin contained in the raw material is 2-8 parts by weight, and the amount of sodium borohydride or potassium borohydride is 2-15 parts by weight.

As a preferred mode, in the preparation method, the alkaline solution in step (3) is prepared by 10-50 parts by weight of sodium hydroxide or 15-60 parts by weight of potassium hydroxide and water according to the ratio of 1g:4ml.

As a preferred way, in the preparation method, the crosslinking agent in step (3) is selected from epichlorohydrin, succinic anhydride, succinyl chloride, divinyl sulfone, polybasic acid, N,N-methylenebis One or more of acrylamides.

As a preferred mode, in the preparation method, the molecular weight of the hydroxyethyl cellulose is 90,000-720,000. This ensures that the polymer is cross-linked to form a gel.

As a preferred mode, in the preparation method, the mixing and stirring time of the hydroxyethyl cellulose and the tin solution system in step (2) is 0.5-2 hours. This allows for even mixing.

As a preferred way, in the preparation method, in step (3), the gel cross-linking temperature is controlled at 20-50 degrees, and the cross-linking time is 3-10 hours, so that the cross-linking can be sufficient within such a time.

As a preferred mode, in the preparation method, the drying method of the gel in step (4) is one of supercritical drying, freeze drying, vacuum drying and blast drying, the gel drying time is 0.5-4 days, and the drying time is 0.5-4 days. The temperature is -50-70 degrees for full drying.

As a preferred way, in the preparation method, in step (4), the gel carbonization temperature is 800-1600 degrees, and the holding time is 1-4 hours, so that the carbonization can be sufficient.

In order to achieve the above purpose of the invention, the present invention also provides a cellulose in-situ carbon-based lithium battery aerogel prepared by the above preparation method.

Compared with the existing tin-carbon lithium battery negative electrode technology, the preparation method of the cellulose in-situ carbon-based lithium battery aerogel of the present invention has outstanding features and excellent effects as follows:

1. The present invention uses hydroxyethyl cellulose, a biomass raw material with the most abundant reserves in nature, to obtain this cellulose in-situ carbon-based lithium battery aerogel with excellent performance and good gram capacity in the negative electrode material of lithium batteries. At the same time, it ensures that it has a good preparation process and an excellent specific surface area, which makes it of great significance to promote the application and development of lithium battery anode materials, and makes up for the shortcomings of existing lithium battery anode materials.

2. The preparation of the present invention has wide sources of raw materials, simple preparation method, and low preparation cost. The raw materials used are all from industrialized products, the preparation is highly feasible, and the difficulty of industrialization is small, and it is expected to realize large-scale industrialized production.

Description of drawings

Fig. 1 is a schematic diagram of the chemical cross-linking process of preparing a cross-linked gel according to the present invention.

Fig. 2 is the SEM image of the gel prepared by the present invention after chemical cross-linking.

Detailed ways

The embodiments of the present invention are described below through specific specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

Fig. 2 is the SEM image of the gel prepared by the present invention after chemical cross-linking. It can be seen from Figure 2 that the cross-linked gel has a continuous and uniform structure.

Example 1

A preparation method of cellulose in-situ carbon-based lithium battery aerogel, comprising the following steps:

(1) prepare nano-tin with reduction method, the raw material of nano-tin is one or more in tin chloride, stannous chloride or tin powder, and the reducing agent adopted is sodium borohydride, and the tin contained in the raw material The total amount is 2-8 parts by weight, and the sodium borohydride is 2 parts by weight.

The nano-tin is dispersed in 60 parts by weight of water as a tin source to form a homogeneous dispersion tin solution system; the total amount of tin contained in the tin source is 2-8 parts by weight;

(2) adding 4 parts by weight of hydroxyethyl cellulose to the tin solution system, stirring at room temperature for 0.5 hour to fully dissolve it to form a transparent or translucent viscous liquid; the molecular weight of the hydroxyethyl cellulose is 90,000-720,000 .

(3) Add alkaline solution to the viscous liquid and continue to stir evenly, then add 5 parts by weight of cross-linking agent epichlorohydrin and stir evenly at room temperature, and finally polymerize at room temperature to form a transparent or translucent bulk gel; the alkaline solution 10 parts by weight of sodium hydroxide and water are prepared according to the ratio of 1 g: 4 ml. The gel crosslinking temperature was controlled at 20 degrees, and the crosslinking time was 3 hours.

(4) drying the obtained gel, the drying method is supercritical drying, the gel drying time is 0.5 days, and the drying temperature is -50 degrees. The dried gel is then carbonized, the carbonization temperature is 800 degrees, and the holding time is 1 hour, and then ball milling and washing are performed to obtain a cellulose in-situ carbon-based lithium battery aerogel.

Example 2

A preparation method of cellulose in-situ carbon-based lithium battery aerogel, comprising the following steps:

(1) tin tetrachloride is dispersed in 100 parts by weight of water as tin source to form a homogeneous dispersion tin solution system; the total amount of tin contained in the tin source is 2-8 parts by weight;

(2) Add 10 parts by weight of hydroxyethyl cellulose to the tin solution system, the molecular weight of the hydroxyethyl cellulose is 90,000-720,000, stir at room temperature for 2 hours, and fully dissolve it to form a transparent or translucent sticky shape liquid;

(3) Add alkaline solution to the viscous liquid and continue to stir, the alkaline solution is 15 parts by weight of potassium hydroxide and water to prepare according to the ratio of 1g: 4ml, then add 150 parts by weight of cross-linking agent succinic anhydride and stir at normal temperature , the gel crosslinking temperature is controlled at 50 degrees, and the crosslinking time is 10 hours. Finally, it is polymerized at room temperature to form a transparent or translucent bulk gel;

(4) drying the obtained gel, the drying method is vacuum drying, the gel drying time is 4 days, and the drying temperature is 70 degrees. The dried gel is then carbonized, the carbonization temperature of the gel is 1600 degrees, and the holding time is 4 hours, and then ball milling and washing are performed to obtain a cellulose in-situ carbon-based lithium battery aerogel.

Example 3

A preparation method of cellulose in-situ carbon-based lithium battery aerogel, comprising the following steps:

(1) stannous chloride is dispersed in 70 parts by weight of water as tin source to form a homogeneous dispersion tin solution system; the total amount of tin contained in the tin source is 2-8 parts by weight;

(2) Add 6 parts by weight of hydroxyethyl cellulose to the tin solution system, and the molecular weight of hydroxyethyl cellulose is 90,000-720,000. Stir at room temperature to fully dissolve to form a transparent or translucent viscous liquid;

(3) Add the alkaline solution to the viscous liquid and continue stirring for 1 hour. The alkaline solution is 30 parts by weight of sodium hydroxide and water and is prepared according to the ratio of 1g:4ml. Then add 50 parts by weight of cross-linking agent divinyl sulfone and stir evenly at room temperature, the gel cross-linking temperature is controlled at 30 degrees, the cross-linking time is 5 hours, and finally polymerized at room temperature to form a transparent or translucent bulk gel;

(4) drying the obtained gel, the drying method is freeze-drying, the gel drying time is 1 day, the drying temperature is -20 degrees, and then the dried gel is carbonized, and the gel carbonization temperature is 1200 degrees, and the temperature is kept at 1200 degrees. The time was 2 hours, and then ball milling and washing were performed to obtain cellulose in-situ carbon-based lithium battery aerogels.

Example 4

A preparation method of cellulose in-situ carbon-based lithium battery aerogel, comprising the following steps:

(1) prepare nano-tin with reduction method, the raw material of nano-tin is tin chloride and tin powder, and the reducing agent that adopts is potassium borohydride, and potassium borohydride is 15 parts by weight.

Disperse nano-tin and tin tetrachloride in 80 parts by weight of water as a tin source to form a homogeneous dispersion tin solution system; the total amount of tin contained in the tin source is 2-8 parts by weight;

(2) Add 8 parts by weight of hydroxyethyl cellulose to the tin solution system, and the molecular weight of the hydroxyethyl cellulose is 90,000-720,000. Stir at room temperature for 1.5 hours to fully dissolve to form a transparent or translucent viscous liquid;

(3) Add alkaline solution to the viscous liquid and continue to stir evenly. The alkaline solution is 35 parts by weight of potassium hydroxide and water and is prepared in the ratio of 1g:4ml. Add 120 parts by weight of cross-linking agent and stir evenly at room temperature. The cross-linking agent includes divinyl sulfone, polybasic acid, N,N-methylenebisacrylamide. The gel cross-linking temperature is controlled at 40 degrees, and the cross-linking time is For 6 hours, sufficient crosslinking can be achieved during such time. Finally, it is polymerized at room temperature to form a transparent or translucent bulk gel;

(4) drying the obtained gel by blasting, the drying time is 3 days, the drying temperature is 40 degrees, and then the dried gel is carbonized, the gel carbonization temperature is 1400 degrees, and the holding time is 3 hours, so that Fully carbonized. Then ball-milling and washing process to obtain cellulose in-situ carbon-based lithium battery aerogel.

The above-mentioned embodiments merely illustrate the principles and effects of the present invention, but are not intended to limit the present invention. Anyone skilled in the art can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical idea disclosed in the present invention should still be covered by the claims of the present invention.

Claims (10)

1. The preparation method of the cellulose in-situ carbon-based lithium battery aerogel is characterized by comprising the following steps of:

(1) dispersing at least one of nano tin, stannic chloride and stannous chloride as a tin source in 60-100 parts by weight of water to form a homogeneously dispersed tin solution system; the total amount of tin contained in the tin source is 2-8 parts by weight;

(2) adding 4-10 parts by weight of hydroxyethyl cellulose into a tin solution system, and stirring at normal temperature to fully dissolve the hydroxyethyl cellulose to form transparent or semitransparent sticky liquid;

(3) adding an alkali solution into the viscous liquid, continuously stirring uniformly, adding 5-150 parts by weight of a cross-linking agent, stirring uniformly at normal temperature, and finally polymerizing at normal temperature to form transparent or semitransparent blocky gel;

(4) and drying the obtained gel, and then carbonizing, ball-milling and washing the dried gel to obtain the cellulose in-situ carbon-based lithium battery aerogel.

2. The method for preparing the cellulose in-situ carbon-based lithium battery aerogel according to claim 1, wherein the method comprises the following steps: the nano tin is prepared by a reduction method, the raw material of the nano tin is one or more of tin chloride, stannous chloride or tin powder, the adopted reducing agent is sodium borohydride or potassium borohydride, the total weight of tin contained in the raw material is 2-8 parts by weight, and the weight of the sodium borohydride or the potassium borohydride is 2-15 parts by weight.

3. The method for preparing the cellulose in-situ carbon-based lithium battery aerogel according to claim 1, wherein the method comprises the following steps: in the step (3), the alkali solution is 10-50 parts by weight of sodium hydroxide or 15-60 parts by weight of potassium hydroxide and water according to the weight ratio of 1 g: 4ml of the mixture.

4. The method for preparing the cellulose in-situ carbon-based lithium battery aerogel according to claim 1, wherein the method comprises the following steps: the cross-linking agent in the step (3) is selected from one or more of epichlorohydrin, succinic anhydride, succinyl chloride, divinyl sulfone, polybasic acid and N, N-methylene-bisacrylamide.

5. The method for preparing the cellulose in-situ carbon-based lithium battery aerogel according to claim 1, wherein the method comprises the following steps: the molecular weight of the hydroxyethyl cellulose is 9-72 ten thousand.

6. The method for preparing the cellulose in-situ carbon-based lithium battery aerogel according to claim 1, wherein the method comprises the following steps: in the step (2), the mixing and stirring time of the hydroxyethyl cellulose and the tin solution system is 0.5 to 2 hours.

7. The method for preparing the cellulose in-situ carbon-based lithium battery aerogel according to claim 1, wherein the method comprises the following steps: in the step (3), the gel crosslinking temperature is controlled to be 20-50 ℃, and the crosslinking time is 3-10 hours.

8. The method for preparing the cellulose in-situ carbon-based lithium battery aerogel according to claim 1, wherein the method comprises the following steps: the drying mode of the gel in the step (4) is one of supercritical drying, freeze drying, vacuum drying and forced air drying, the drying time of the gel is 0.5-4 days, and the drying temperature is-50-70 ℃.

9. The method for preparing the cellulose in-situ carbon-based lithium battery aerogel according to claim 1, wherein the method comprises the following steps: in the step (4), the gel carbonization temperature is 800-1600 ℃, and the heat preservation time is 1-4 hours.

10. The cellulose in-situ carbon-based lithium battery aerogel prepared by the preparation method according to any one of claims 1 to 9.

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