WO2022134747A1

WO2022134747A1 - Preparation method for and application of composite material containing graphite and mof

Info

Publication number: WO2022134747A1
Application number: PCT/CN2021/123393
Authority: WO
Inventors: 余海军; 彭挺; 谢英豪; 朱红梅; 刘述敏
Original assignee: 广东邦普循环科技有限公司; 湖南邦普循环科技有限公司; 湖南邦普汽车循环有限公司
Priority date: 2020-12-23
Filing date: 2021-10-13
Publication date: 2022-06-30
Also published as: GB202310070D0; CN112679966B; GB2616800A; CN112679966A

Abstract

A preparation method for and application of a composite material containing graphite and MOF. The preparation method comprises: adding an amino-containing organic substance into a mixed solution, performing stirring, adding a titanium-containing coupling agent, and continuing stirring to obtain a suspension; performing solvothermal reaction on the suspension, performing filtering, taking filter residues, alternately cleaning the filter residues by using organic solvents in sequence, and performing extraction to obtain MOF; and grinding graphite into powder, mixing the powder with alcohol, performing oscillating, then adding MOF, continuing oscillating, performing refluxing, standing, and centrifuging, taking precipitate, and performing drying to obtain the composite material containing graphite and MOF. The composite material containing graphite and MOF is good in structural stability, can be used as a basic framework of a negative electrode material, and can eliminate the volume expansion effect of a battery in a charging/discharging process when being applied to a negative electrode of the lithium battery, thereby improving capacity.

Description

A kind of preparation method and application of composite material containing graphite and MOF

technical field

The present disclosure belongs to the field of battery materials, and in particular relates to a preparation method and application of a composite material containing graphite and MOF.

Background technique

With the advancement of Internet technology, more and more technical applications rely on electronic devices to be used. The use of electronic equipment requires high-capacity, easy-to-use lithium batteries to provide battery life. In addition, with the increasing use of electric vehicles and other power tools by various policies in recent years, lithium batteries have become an indispensable device for social development, from all walks of life to daily life. At present, the anode materials in lithium-ion batteries are mainly carbons, such as graphite, soft and hard carbon, etc., or new electrode materials, such as silicon carbon anodes or transition metal oxides. Under the development trend of the market's gradual increase in battery capacity requirements, traditional lithium-ion batteries with negative electrodes can no longer be satisfied with the status quo. In this case, the preparation and application of new materials in lithium-ion batteries has become a research hotspot.

Metal-organic frameworks (MOFs) are crystal framework materials with intramolecular pores formed by self-assembly of metal ions or clusters and organic ligands through coordination bonds under certain conditions. Such materials have large specific surface area, adjustable pore size and shape, and are easy to be modified. The proton-conducting and electronic-conducting MOFs show potential application value in the fields of fuel cells, electrocatalysis, lithium-ion batteries, and supercapacitors. MOF has attracted wide attention due to its unique pore structure and the characteristics of containing transition metal elements. MOFs have been successfully prepared as active materials or electrodes as active material carriers, and MOFs have also been prepared as precursors to form active materials or active materials. The electrode of the material carrier, but MOF as an electrode is slightly less conductive than other electrode materials. Secondly, the preparation process of MOF itself is relatively complicated, which affects the controllability of its morphology, making it less stable, and limiting the wide application of MOF in electrode materials.

So far, various MOFs have been reported for anodes in lithium batteries. However, most of the MOFs have the disadvantage of low capacity when used as the negative electrode of lithium batteries. Therefore, it is of great significance to find a composite material with stable structure, large specific surface area, wider application range, and greatly improved charge-discharge Coulombic efficiency and cyclability.

SUMMARY OF THE INVENTION

Embodiments of the present disclosure provide a preparation method and application of a composite material containing graphite and MOF. The composite material prepared by the preparation method of the embodiment of the present disclosure has good structural stability, because the application of the composite material in the negative electrode of a lithium battery can eliminate the structural collapse of the negative electrode material caused by the cycle of delithiation and intercalation during the charging and discharging process of the lithium battery. The volume expansion effect of the battery during charging and discharging, thereby improving the capacity and other electrochemical properties.

In order to achieve the above purpose, an embodiment of the present disclosure provides a method for preparing a composite material containing graphite and MOF, comprising the following steps:

(1) adding an amino-containing organic matter to the mixed solution, stirring, increasing the stirring speed, adding a titanium-containing coupling agent, and continuing to stir to obtain a suspension;

(2) suspension is carried out solvothermal reaction, filter, get filter residue and use organic solvent alternately to wash successively, extraction, obtains MOF;

(3) grinding graphite into powder and mixing with alcohol, shaking, then adding the MOF, continuing shaking, refluxing, standing, centrifuging, taking the precipitate and drying to obtain the composite material containing graphite and MOF.

In some embodiments, the mixed solution is obtained by mixing N,N-dimethylamide and methanol; the mass ratio of the N,N-dimethylamide and methanol is 1:(6-9).

In some embodiments, the N,N-dimethylamide and methanol are both in an anhydrous state.

In some embodiments, the temperature of the N,N-dimethylamide distillation is 50-60°C; the temperature of the methanol distillation is 55-65°C.

In some embodiments, in step (1), the amino-containing organic is 2-amino-terephthalic acid; in step (1), the mass ratio of the amino-containing organic to the mixed solution is 1:( 3 to 6).

In some embodiments, in step (1), the temperature of the stirring is 15°C to 35°C, the rotational speed of the stirring is 500-800 r/min, and the stirring time is 10-30 min.

In some embodiments, in step (1), the increasing stirring speed is 1000-1500 r/min, and the stirring time is 10-30 min.

In some embodiments, in step (1), the titanium-containing coupling agent is tetrabutyl titanate.

In some embodiments, in step (1), the mass ratio of the mixed solution and the titanium-containing coupling agent is 1:(15-35).

In some embodiments, in step (1), the mass ratio of the mixed solution and the titanium-containing coupling agent is 1:(20-30).

In some embodiments, in step (2), the organic solvent is N,N-dimethylamide and methanol.

In some embodiments, in step (2), the sequential washing with organic solvents is washing with N,N-dimethylamide and methanol alternately for 3-5 times.

In some embodiments, in step (2), the temperature of the solvothermal reaction is 130°C to 150°C, and the time of the solvothermal reaction is 24 to 72 h.

In some embodiments, in step (2), the extraction is performed using a Soxhlet extractor.

In some embodiments, in step (3), the grinding of graphite into powder is to grind the graphite to 100-200 mesh.

In some embodiments, in step (3), the alcohol is anhydrous methanol.

In some embodiments, in step (3), the mass ratio of the graphite and alcohol is 1:(10-20).

In some embodiments, in step (3), the mass ratio of graphite and alcohol is 1:(15-20).

In some embodiments, in step (3), the mass ratio of the MOF and alcohol is 1:(10-20).

In some embodiments, in step (3), the mass ratio of the MOF and alcohol is 1:(15-20).

In some embodiments, in step (3), the oscillation is ultrasonic oscillation, the time of the ultrasonic oscillation is 20-40 min, and the time of the continuous oscillation is 20-40 min.

In some embodiments, in step (3), the temperature of the reflux is 60°C to 70°C, the reflux time is 12 to 18 hours, and the standing time is 12 to 18 hours.

The embodiment of the present disclosure provides a composite material containing graphite and MOF, which is prepared by the above preparation method; the specific capacity of the graphite-coated MOF material is 460-495 mAh/g, the porosity is 32-37%, and the specific surface area is 32-37%. 2.7-3.5m ² /g.

An embodiment of the present disclosure provides a negative electrode sheet, which includes the graphite- and MOF-containing composite material of the foregoing embodiments.

Embodiments of the present disclosure also provide a method for preparing a negative electrode sheet, comprising the following steps:

mixing the graphite and MOF-containing composite material with acetylene black, and then ball milling to obtain a mixture; then mixing the mixture, PVDF and N-methylpyrrolidone to prepare a slurry; coating and drying the slurry Made of negative electrode.

In some embodiments, the weight ratio of the composite material containing graphite and MOF to acetylene black is 1:(0.1˜0.3).

In some embodiments, the rotational speed of the ball milling is 3000-6000 r/min, and the time of the ball milling is 10-20 min.

In some embodiments, the mass ratio of the mixture, PVDF and N-methylpyrrolidone is 1:(0.1-0.15):(0.1-0.5).

An embodiment of the present disclosure also provides a battery, which includes the negative electrode sheet of the above-mentioned embodiment.

Advantages of embodiments of the present disclosure:

1. In the embodiment of the present disclosure, the obtained composite material containing graphite and MOF (graphite-coated MOF) is used as the basic structure of the negative electrode material. The volume expansion effect of the battery during the charging and discharging process caused by the structure collapse of the negative electrode material caused by the cycle of delithiation and intercalation of lithium during the battery charge and discharge process (volume expansion will cause the material structure to collapse and weaken the electrochemical performance), thereby improving the capacity and other electrochemical performance.

2. The composite materials designed in the embodiments of the present disclosure have both superior charge-discharge capacity and electrical conductivity than graphite materials, and excellent structural stability of MOF materials.

3. By introducing NH ₂ ^- into the MOF material in the embodiment of the present disclosure, it not only enhances the electron density of the material, but also leads to a certain increase in the electrical conductivity of the material, and more importantly, provides a lithium intercalation site, which significantly increases its charge. Discharge capacity; the first discharge specific capacity can reach 492.3mAh/g, and the capacity retention rate is 96.6%.

Description of drawings

Fig. 1 is the XRD pattern of the composite material containing graphite and MOF prepared in Example 1;

FIG. 2 is a TEM image of the composite material containing graphite and MOF prepared in Example 1. FIG.

Detailed ways

In order to have an in-depth understanding of the present disclosure, some experimental schemes of the present disclosure will be described below in conjunction with the embodiments to better illustrate the features and advantages of the present disclosure. Any changes or changes that do not deviate from the gist of the present disclosure can be understood by those skilled in the art , the protection scope of the present disclosure is determined by the scope of the appended claims.

If the specific conditions are not indicated in the embodiments of the present disclosure, the conventional conditions or the conditions suggested by the manufacturer are used. The raw materials, reagents, etc., which are not specified by the manufacturer, are all conventional products that can be purchased from the market.

Example 1

The preparation method of the composite material containing graphite and MOF of the present embodiment comprises the following steps:

(1) Distill anhydrous N,N-dimethylamide and anhydrous methanol at 50°C and 55°C respectively, and then distill the anhydrous N,N-dimethylamide and anhydrous methanol obtained by distillation according to 1 : 6 ratios are mixed to obtain a mixed solution;

(2) Add 2-amino-terephthalic acid in a mass-to-volume ratio of 1:3, stir for 10 minutes at a rotational speed of 500 r/min at 15°C, increase the rotational speed to 1000 r/min, and then add titanium in a volume ratio of 1:15 Tetrabutyl acid was continuously stirred for 10min to obtain a suspension;

(3) Transfer the obtained suspension to a dry hydrothermal kettle, carry out a solvothermal reaction at 130° C. for 24 hours, filter the product of the solvothermal reaction, and sequentially use anhydrous N,N-dimethylamide, anhydrous After alternately washing with water and methanol for 3 times, extract with a Soxhlet extractor to obtain a white solid MOF material;

(4) Grind graphite into powder (pass through a 100-mesh sieve), mix with anhydrous methanol at a mass-to-volume ratio of 1:10, ultrasonicate for 20 minutes, add white solid MOF material at a mass-to-volume ratio of 1:10, and continue to ultrasonically vibrate for 20 minutes After refluxing at 60° C. for 12 hours, it was left to stand for 12 hours, centrifuged, and dried to obtain a composite material containing graphite and MOF (graphite-coated MOF).

The preparation method of the negative electrode sheet of this embodiment includes the following steps: mixing the composite material containing graphite and MOF with acetylene black at a weight ratio of 1:0.1, and then ball milling at a rotational speed of 3000 r/min for 10 minutes, and the obtained mixture powder is mixed with a ratio of 1 :0.1:0.1 with PVDF and N-methyl pyrrolidone to prepare slurry, coating and drying to make negative electrode sheet.

Example 2

(1) Distill anhydrous N,N-dimethylamide and anhydrous methanol at 50°C and 60°C respectively, and then distill the anhydrous N,N-dimethylamide and anhydrous methanol obtained by distillation according to 1 : 7 ratios are mixed to obtain a mixed solution;

(2) 2-amino-terephthalic acid will be added in a mass-to-volume ratio of 1:5, and after stirring for 20 min at a rotating speed of 700 r/min at 20°C, the rotating speed will be increased to 1200 r/min, and then titanium will be added at a volume ratio of 1:25. Tetrabutyl acid was continuously stirred for 20min to obtain a suspension;

(3) Transfer the obtained suspension to a dry hydrothermal kettle, carry out a solvothermal reaction at 140° C. for 48 hours, filter the product of the solvothermal reaction, and sequentially use anhydrous N,N-dimethylamide, anhydrous After alternately washing with water and methanol for 3 times, extract with a Soxhlet extractor to obtain a white solid MOF material;

(4) Grind the graphite into powder (pass through a 150 mesh sieve), mix it with anhydrous methanol at a mass-to-volume ratio of 1:15, ultrasonicate for 30 minutes, then add a white solid MOF material at a mass-to-volume ratio of 1:15, and continue to ultrasonically vibrate for 30 minutes After 15 hours of reflux at 65° C., it was left to stand for 15 hours, centrifuged, and dried to obtain a composite material containing graphite and MOF (graphite-coated MOF).

The preparation method of the negative electrode sheet of the present embodiment includes the following steps: mixing a composite material containing graphite and MOF (graphite-coated MOF) and acetylene black at a weight ratio of 1:0.2, and then ball-milling at a rotational speed of 4500 r/min for 15 min to obtain the mixture. The powder is then mixed with PVDF and N-methylpyrrolidone in a ratio of 1:0.12:0.3 to prepare a slurry, which is coated and dried to form a negative electrode sheet.

Example 3

(1) Distill anhydrous N,N-dimethylamide and anhydrous methanol at 60°C and 65°C respectively, and then distill the anhydrous N,N-dimethylamide and anhydrous methanol obtained by distillation according to 1 : 9 ratios are mixed to obtain a mixed solution;

(2) Add 2-amino-terephthalic acid in a mass-to-volume ratio of 1:6, stir for 30 min at a rotational speed of 800 r/min at 35°C, increase the rotational speed to 1500 r/min, and then add titanium in a volume ratio of 1:35 Tetrabutyl acid was continuously stirred for 30min to obtain a suspension;

(3) Transfer the obtained suspension to a dry hydrothermal kettle, carry out a solvothermal reaction at 150° C. for 72 h, filter the product of the solvothermal reaction, and sequentially use anhydrous N,N-dimethylamide, anhydrous After alternately washing with water and methanol for 3 times, extract with a Soxhlet extractor to obtain a white solid MOF material;

(4) Grind the commercial graphite into powder (pass through a 200-mesh sieve), mix it with anhydrous methanol at a mass-to-volume ratio of 1:20, and after ultrasonication for 40 minutes, add a white solid MOF material at a mass-to-volume ratio of 1:20, and continue to ultrasonically vibrate After 40 min, and after refluxing at 70° C. for 18 hours, stand for 18 hours, centrifuge, and dry to obtain a composite material containing graphite and MOF (graphite-coated MOF).

The preparation method of the negative electrode sheet of the present embodiment includes the following steps: mixing the composite material containing graphite and MOF with acetylene black at a weight ratio of 1:0.3, and then ball milling at a rotational speed of 6000 r/min for 20 minutes, and the obtained mixture powder is mixed with a ratio of 1 : 0.15:0.5 with PVDF and N-methyl pyrrolidone to prepare slurry, coating and drying to make negative electrode sheet.

Comparative Example 1

A preparation method of a titanium-based MOF lithium ion battery negative electrode material, comprising the following steps: dispersing 2,5-dihydroxyterephthalic acid in an isopropanol solution, and adding the solution dropwise to a titanium tetraisopropoxide-containing solution In the acetonitrile solution, at room temperature, an orange-brown slurry was obtained and stirred for 30 minutes; moved to a Teflon autoclave, heated to 120 °C for 24 hours, and formed into dark red crystals, and then filtered in an air atmosphere, using DMF (N,N-dimethylformamide) and ethanol were washed three times, and the electrode material was obtained by vacuum drying.

Comparative Example 2

A preparation method of a material containing graphite and MOF, comprising the following steps: grinding commercial graphite into powder, mixing with anhydrous methanol at a mass-volume ratio of 1:20, ultrasonicating for 40 minutes, and then adding carbon dioxide at a mass-volume ratio of 1:20. The MOF material obtained in the ratio 1 was subjected to ultrasonic vibration for 40 minutes, refluxed at 70° C. for 18 hours, left standing for 18 hours, centrifuged, and dried to obtain a graphite-coated MOF material.

Performance check:

The negative electrode material containing graphite and MOF composite material and the negative electrode material obtained by Comparative Example 1-2 were respectively obtained from the above-mentioned Examples 1-3, and the negative electrode sheet was obtained, and the lithium sheet was used as the positive electrode to assemble into a button battery. 1C rate for the first discharge test, the results are shown in Table 1 and Table 2. According to Table 1, at a rate of 1C, the first discharge specific capacity of the negative electrode material of the graphite and MOF-containing composite material prepared in the embodiment of the present disclosure is higher than that of the MOF materials of Comparative Examples 1 and 2, and the first discharge ratio of Example 2 The capacity is 492.3mAh/g, while the first discharge specific capacity of Comparative Example 1 is only 333.1mAh/g, and the first discharge specific capacity of Comparative Example 2 is only 367.2mAh/g. According to Table 2, at 1C rate, the cycle life of the negative electrode material of the graphite and MOF-containing composite material prepared in the embodiment of the present disclosure is higher than that of the MOF material of the comparative example. After 1600 cycles of 1C, the capacity of Example 2 is maintained. The capacity retention rate is 96.6%, while the capacity retention rates of Comparative Examples 1-2 are only 92.8% and 90.2%, respectively.

Table 1 Coin cell performance of composites containing graphite and MOF

Table 2 Full-cell cycling performance of composites containing graphite and MOF

FIG. 1 is the XRD pattern of the composite material containing graphite and MOF, which reflects the characteristic peaks of the composite material. Figure 2 is a TEM image of the composite containing graphite and MOF, showing the bulk morphology.

The preparation method and application of a composite material containing graphite and MOF provided by the embodiments of the present disclosure have been described above in detail. The principles and implementations of the present disclosure are described with specific examples herein. The descriptions are provided only to aid in understanding the methods and core ideas of the present disclosure, including better modes, and also to enable any person skilled in the art to practice the embodiments of the present disclosure, including making and using any devices or systems, and implementing any combination. It should be pointed out that for those skilled in the art, without departing from the principles of the present disclosure, several improvements and modifications can also be made to the embodiments of the present disclosure, and these improvements and modifications also fall within the protection of the claims of the present disclosure within the range. The scope of patent protection of the present disclosure is defined by the claims, and may include other examples that occur to those skilled in the art. Such other embodiments are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.

Claims

A preparation method of a composite material containing graphite and MOF, comprising the following steps:

(1) adding an amino-containing organic matter to the mixed solution, stirring, increasing the stirring speed, adding a titanium-containing coupling agent, and continuing to stir to obtain a suspension;

(2) suspension is carried out solvothermal reaction, filter, get filter residue and use organic solvent alternately to wash successively, extraction, obtains MOF;

(3) grinding graphite into powder and mixing with alcohol, shaking, then adding the MOF, continuing shaking, refluxing, standing, centrifuging, taking the precipitate and drying to obtain the composite material containing graphite and MOF.
The preparation method according to claim 1, wherein, in step (1), the mixed solution is obtained by mixing N,N-dimethylamide and methanol; The mass ratio is 1:(6～9).
The preparation method according to claim 1, wherein, in step (1), the amino-containing organic substance is 2-amino-terephthalic acid; in step (1), the amino-containing organic substance and the mixed solution are The mass ratio is 1:(3～6).
The preparation method according to claim 1, wherein, in step (1), the temperature of the stirring is 15°C to 35°C, the rotational speed of the stirring is 500-800 r/min, and the stirring time is 10- 30min; in step (1), the increasing stirring speed is 1000-1500r/min, and the time for continuing stirring is 10-30min.
The preparation method according to claim 1, wherein, in step (1), the titanium-containing coupling agent is tetrabutyl titanate; in step (1), the quality of the mixed solution and the titanium-containing coupling agent is The ratio is 1:(15～35).
The preparation method according to claim 1, wherein, in step (2), the organic solvent is N,N-dimethylamide and methanol.
The preparation method according to claim 1, wherein, in step (3), the alcohol is anhydrous methanol; the mass ratio of the graphite and the alcohol is 1:(10-20); in step (3), the alcohol is The mass ratio of MOF and alcohol is 1:(10～20).
The preparation method according to claim 1, wherein, in step (2), the temperature of the solvothermal reaction is 130°C to 150°C, and the time of the solvothermal reaction is 24 to 72h; in step (3), the The reflux temperature is 60°C to 70°C, the reflux time is 12 to 18 hours, and the standing time is 12 to 18 hours.
A composite material containing graphite and MOF, prepared by the preparation method according to any one of claims 1-8; the specific capacity of the composite material containing graphite and MOF is 460-495mAh/g, and the porosity is 32-37%, the specific surface area is 2.7-3.5m 2 /g.
A negative electrode sheet, comprising the composite material containing graphite and MOF according to claim 9.