WO2017124714A1

WO2017124714A1 - Method for preparing mfi zeolite coated lithium ion battery separator

Info

Publication number: WO2017124714A1
Application number: PCT/CN2016/090620
Authority: WO
Inventors: 林跃生; 董学良; 金翼; 张遥骋; 傅凯; 刘曙光; 闫雪生; 褚永金
Original assignee: 中国电力科学研究; 亚利桑那州立大学; 国家电网公司; 华北电网有限公司
Priority date: 2016-01-19
Filing date: 2016-07-20
Publication date: 2017-07-27
Also published as: CN106981606A; CN106981606B

Abstract

A method for preparing an MFI zeolite coated lithium ion battery separator, the preparation method comprising preparing a prepared MFI zeolite, a binder and butanone in a mass ratio of 1-10 : 1-100 : 1-1000 as a mixed solution, and subjecting the mixed solution to an ultrasonic treatment to obtain a coating suspension; impregnating a macromolecular separator with the MFI zeolite coating suspension to obtain an MFI zeolite coated separator a uniform coating mass; and drying the resulting MFI zeolite coated separator at 30-90°C. The technical solution is simple in preparation process and convenient in operation, has a capability of continuous production in a production line, a strong practicality and a low production cost, and improves the safety performance, the charge-discharge cycle life and the heat resistance of a battery; there is a very strong wettability between the MFI zeolite coated lithium ion battery separator and an electrolyte; and the MFI zeolite coated lithium ion battery separator has a high anti-puncture strength as much as twice or more the anti-puncture strength of a polyolefin separator.

Description

Preparation method of MFI zeolite coated lithium ion battery separator

Technical field

The invention relates to a preparation method of a lithium ion battery separator, in particular to a preparation method of a MFI zeolite coated lithium ion battery separator.

Background technique

Lithium-ion batteries have become the main power source for all kinds of portable electronic products due to their high working voltage, high energy density, no memory effect, long cycle life and low self-discharge. The “Energy Conservation and New Energy Vehicle Industry Development Plan” formulated by the state has played a powerful role in promoting the rapid development of lithium-ion batteries and related materials.

The lithium ion battery is mainly composed of a positive electrode, a negative electrode, an electrolyte and a diaphragm. The separator is a key material for lithium-ion batteries. Currently, commercial lithium-ion membranes are mainly made of polyethylene and polypropylene microporous membranes, but they cannot be used in the field of power lithium-ion batteries due to the limitations of the nature of the membrane materials.

The membrane must absorb and retain a certain amount of liquid electrolyte to achieve low internal resistance, high ionic conductivity. The rapid absorption of the electrolyte by the diaphragm greatly affects the filling of the diaphragm electrolyte during battery assembly. Commercially available polyolefin separators with commonly used electrolytes such as ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC) and dimethyl carbonate due to low surface energy and non-polarity ( DMC) has poor wettability. Poor wetting results in high internal impedance and poor electrochemical performance, which greatly inhibits the transport of lithium ions. This has become a major obstacle to energy storage equipment, high-energy electric vehicles and smart grid applications.

In addition, the diaphragm must be able to withstand sufficient tension during assembly and winding of the battery and have high puncture resistance. Polyolefin separators generally have high tensile strength but low puncture strength. In the case of large current charging or multiple cycles, lithium metal inevitably forms dendrites at the anode. Lithium dendrites can penetrate the polyolefin membrane causing a short circuit. This converts all stored chemical energy into heat, which causes smoke and further causes a fire.

Therefore, there is a need to provide an improved technical solution to the above-described deficiencies of the prior art.

Summary of the invention

The object of the present invention is to overcome the problems of poor wettability, low puncture resistance and poor safety of the lithium ion battery separator and the electrolyte in the prior art described above, and to provide a strong wettability, high puncture strength and good safety performance. A method for preparing a lithium ion battery separator coated with a MFI zeolite having a long charge and discharge cycle life and good heat resistance.

To achieve the above object, the present invention adopts the following technical solutions:

A method for preparing a MFI-type zeolite coated lithium ion battery separator, the preparation method comprising the following steps:

1) Preparation of MFI zeolite: preparing a silica-alumina composite precursor or a pure silica precursor, and washing the prepared precursor with deionized water through a centrifuge, drying at room temperature, and then calcining at a high temperature;

2) Preparation of binder: Polyvinylidene fluoride powder, nitrogen-nitrodimethylformamide and methyl ethyl ketone are prepared in a ratio of 1:1 to 50:1 to 50 by mass ratio, and the mixture is stirred for 5 to 10 minutes. mixture;

3) Preparation of MFI zeolite coating suspension: mixing the MFI zeolite of step 1), the binder of step 2) and methyl ethyl ketone in a ratio of 1 to 10:1 to 100:1 to 1000 by mass. The liquid is dispersed by ultrasonic wave for 1 to 1000 minutes, and then stirred for 1 to 100 hours to obtain a uniform and stable MFI zeolite coating suspension;

4) Preparation of MFI zeolite coated membrane: after step 3) MFI zeolite coating suspension impregnation polymer membrane for 5 ~ 100s, cooling for 1 ~ 1000min; repeat the above operation 1 ~ 1000 times, the coating quality is uniform MFI zeolite coated membrane;

5) Treatment of MFI zeolite-coated membrane: The MFI zeolite-coated membrane of step 4) was dried at 30-90 ° C for 10 to 100 h, and the membrane was smoothed during the drying process without wrinkles and bending.

Further, the preparation of the silicon-aluminum composite precursor in the step 1) comprises: deionized water, sodium hydroxide, tetrabutylammonium bromide, Al ₂ (SO ₄ ) ₃ ·18H ₂ O and tetraethyl silicate The mixture is prepared according to the ratio of mass ratio of 60:0.27:1.77:0 to 0.4:6.2, stirred for 5-20 min, and maintained at 160-180 ° C for 10-12 h to obtain a silicon-aluminum composite precursor.

Further, the preparation of the pure silica precursor in the step 1) comprises: ratio of the silica powder, the sodium hydroxide and the tetrapropylamine hydroxide in a mass ratio of 90 to 110:5 to 10:20 to 30. The mixture is prepared, stirred for 5-20 min, and kept at 100-150 ° C for 10-15 h to obtain a pure silica precursor.

Further, the preparation of the pure silica precursor is: preparing a mixture of silica powder, sodium hydroxide and tetrapropylammonium hydroxide at a mass ratio of 100:7:30, stirring for 10 min, 120 ° C After holding for 12 h, a pure silica precursor was obtained.

Further, the optimal conditions for the high temperature calcination in the step 1) are: calcination at 550 ° C for 8 h.

Further, the silica has a particle size of 5 nm to 1 μm; the MFI zeolite has a silicon-aluminum content ratio of not less than 1:1; and the MFI-type zeolite coating has a thickness of 0.1 μm to 300 μm; The prepared MFI-type zeolite-coated lithium ion battery separator has a thickness of from 10 μm to 500 μm.

Further, the polymer separator is polyethylene, polypropylene or polyimide.

Compared with the closest prior art, the technical solution provided by the present invention has the following excellent effects:

1. The technical solution provided by the invention has simple preparation process, convenient operation, continuous production on the production line, strong practicability and low production cost.

2. The MFI zeolite coated lithium ion battery separator prepared by the technical solution provided by the invention is applied to a lithium battery, so that the battery can significantly improve its safety performance, charge and discharge cycle life and heat resistance.

3. The MFI zeolite coating can better fill the pores of the membrane in the technical solution provided by the invention, so that the MFI zeolite coated lithium ion battery separator has strong wettability with the electrolyte.

4. The MFI zeolite-coated lithium ion battery separator prepared by the technical solution provided by the invention has high puncture resistance and is more than twice of the puncture strength of the commercial polyolefin separator.

DRAWINGS

In order to more clearly illustrate the technical solutions in the present invention, the drawings to be used in the embodiments will be briefly described below. It is obvious that the drawings in the following description are only some embodiments of the present invention. For the ordinary technicians, other drawings can be obtained based on these drawings without any creative work.

Figure 1 (a1) ZCPP25 surface (silicon-aluminum content ratio 25:1), (a2) ZCPP25 cross-section (silicon-aluminum content ratio 25:1), (b1) ZCPP50 surface (silicon-aluminum content ratio 50:1), (b2) ZCPP50 cross section (silicon-aluminum content ratio 50:1), (c1) ZCPP100 surface (silicon-aluminum content ratio 100:1), (c2) ZCPP100 cross-section (silicon-aluminum content ratio 100:1), (d1 ZCPP200 surface (silicon-aluminum content ratio 200:1), (d2) ZCPP200 cross-section (silicon-aluminum content ratio 200:1), (e1) SCPP surface (excluding aluminum element) and (e2) SCPP cross section (excluding Scanning electron micrograph of aluminum element) MFI zeolite coated membrane;

Figure 2 (a) ZCPP25 (silicon-aluminum content ratio of 25:1), ZCPP50 (silicon-aluminum content ratio of 50:1), ZCPP100 (silicon-aluminum content ratio of 100:1), ZCPP200 (silicon-aluminum content ratio of 200: 1) a graph of the contact angle of the MFI zeolite coated membrane with the electrolyte as a function of time;

(b) SCPP (without aluminum) MFI zeolite coated separator and PP (polypropylene) commercial polymer membrane contact angle comparison;

Figure 3 ZCPP25 (aluminum-aluminum content ratio of 25:1) MFI zeolite coated membrane and PP (poly Comparison of propylene) commercial polymer membrane infiltration.

detailed description

The technical solutions in the embodiments of the present invention are clearly and completely described in the following with reference to the accompanying drawings in the embodiments of the present invention. It is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention are within the scope of the present invention.

Example 1

A preparation method of a MFI zeolite coated lithium ion battery separator, the preparation method comprising the following steps:

1) Preparation of MFI zeolite: Preparation of silica-alumina composite precursor, deionized water, sodium hydroxide, tetrabutylammonium bromide, Al ₂ (SO ₄ ) ₃ ·18H ₂ O and tetraethyl silicate The mixture was prepared by mixing the mixture at a mass ratio of 60:0.27:1.77:0.4:6.2, stirring for 10 min, and holding at 175 ° C for 12 h to obtain a silica-alumina composite precursor.

The precursor prepared above was washed with deionized water in a centrifuge to wash the prepared precursor, dried at room temperature, and then calcined at 550 ° C for 8 h.

2) Preparation of binder: Polyvinylidene fluoride powder, nitrogen-nitrodimethylformamide and methyl ethyl ketone were prepared in a ratio of 1:16:16 by mass ratio, and stirred for 10 minutes to obtain a binder;

3) Preparation of MFI zeolite coating suspension: The mixture of the MFI zeolite of step 1), the binder of step 2) and methyl ethyl ketone is prepared at a mass ratio of 1:4:30, and dispersed by ultrasonic for 30 min. After stirring for 5 h, a uniformly stable MFI zeolite coating suspension is obtained;

4) Preparation of MFI zeolite-coated membrane: after step 3) MFI zeolite coating suspension impregnation of polymer membrane for 5 s, cooling for 180 min; repeating the above operation 5 times to obtain MFI zeolite coated with uniform coating quality Diaphragm

5) Treatment of MFI zeolite coated membrane: The MFI zeolite coated membrane of step 4) was dried for 12 h at 60 ° C, and the membrane was smoothed during the drying process without wrinkles and buckling.

Commercially available polypropylene separator (Celgard 2500) was used as a comparative example for performance measurement.

Example 2

1) Preparation of MFI zeolite: Preparation of silica-alumina composite precursor, deionized water, sodium hydroxide, tetrabutylammonium bromide, Al ₂ (SO ₄ ) ₃ ·18H ₂ O and tetraethyl silicate The mixture was prepared in a mass ratio of 60:0.27:1.77:0.2:6.2, stirred for 5 min, and kept at 180 ° C for 12 h to obtain a silica-alumina composite precursor.

2) Preparation of binder: Polyvinylidene fluoride powder, nitrogen-nitrodimethylformamide and methyl ethyl ketone were prepared in a ratio of 1:30:25 by mass ratio, and the binder was obtained after stirring for 8 minutes;

3) Preparation of MFI zeolite coating suspension: The MFI zeolite of step 1), the binder of step 2) and methyl ethyl ketone are prepared in a ratio of 3:15:20 by mass, and dispersed by ultrasonic wave for 25 min. After stirring for 4 h, a uniformly stable MFI zeolite coating suspension is obtained;

4) Preparation of MFI zeolite-coated membrane: after step 3) MFI zeolite coating suspension impregnation of polymer membrane for 20 s, cooling for 380 min; repeating the above operation 100 times to obtain a uniform coating of MFI zeolite coated Diaphragm

5) Treatment of MFI zeolite coated membrane: The MFI zeolite coated membrane of step 4) was dried at 90 ° C for 15 h, and the membrane was smoothed during the drying process without wrinkles and buckling.

Example 3

1) Preparation of MFI zeolite: Preparation of silica-alumina composite precursor, deionized water, sodium hydroxide, tetrabutylammonium bromide, Al ₂ (SO ₄ ) ₃ ·18H ₂ O and tetraethyl silicate The mixture was prepared in a mass ratio of 60:0.27:1.77:0.1:6.2, stirred for 10 min, and kept at 160 ° C for 10 h to obtain a silica-alumina composite precursor.

2) Preparation of binder: Polyvinylidene fluoride powder, nitrogen-nitrodimethylformamide and methyl ethyl ketone were prepared in a ratio of 1:25:20 by mass ratio, and stirred for 8 minutes to obtain a binder;

3) Preparation of MFI zeolite coating suspension: The MFI zeolite of step 1), the binder of step 2) and methyl ethyl ketone are prepared in a ratio of 10:30:20 by mass, and dispersed by ultrasonic for 300 min. After stirring for 60 h, a uniformly stable MFI zeolite coating suspension is obtained;

4) Preparation of MFI zeolite-coated membrane: after step 3) MFI zeolite coating suspension impregnation of polymer membrane for 30 s, cooling for 260 min; repeating the above operation 40 times to obtain uniform coating of MFI zeolite coated Diaphragm

5) Treatment of MFI zeolite coated membrane: The MFI zeolite coated membrane of step 4) was dried at 50 ° C for 20 h, and the membrane was flattened during the drying process without wrinkles and buckling.

Example 4

1) Preparation of MFI zeolite: Preparation of silica-alumina composite precursor, deionized water, sodium hydroxide, tetrabutylammonium bromide, Al ₂ (SO ₄ ) ₃ ·18H ₂ O and tetraethyl silicate The mixture was prepared in a mass ratio of 60:0.27:1.77:0.05:6.2, stirred for 14 min, and kept at 170 ° C for 12 h to obtain a silica-alumina composite precursor.

2) Preparation of binder: Polyvinylidene fluoride powder, nitrogen-nitrodimethylformamide and methyl ethyl ketone are prepared in a ratio of 1:50:50 by mass ratio, and stirred for 10 minutes to obtain a binder;

3) Preparation of MFI zeolite coating suspension: The mixture of the MFI zeolite of step 1), the binder of step 2) and methyl ethyl ketone is prepared at a mass ratio of 8:20:40, and dispersed by ultrasonic for 500 min. After stirring for 3 h, a uniform and stable MFI zeolite coating suspension is obtained;

4) Preparation of MFI zeolite-coated membrane: after step 3) MFI zeolite coating suspension impregnation of polymer membrane for 15 s, cooling for 200 min; repeating the above operation 12 times to obtain a uniform coating of MFI zeolite coated Diaphragm

5) Treatment of MFI zeolite coated membrane: The MFI zeolite coated membrane of step 4) was dried at 40 ° C for 25 h, and the membrane was smoothed during the drying process without wrinkles and buckling.

Example 5

1) Preparation of MFI-type zeolite: preparing a pure silica precursor, preparing a mixture of silica powder, sodium hydroxide and tetrapropylamine at a mass ratio of 100:7:30, and stirring for 15 minutes. The mixture was kept at 120 ° C for 12 h to obtain a pure silica precursor.

2) Preparation of binder: Polyvinylidene fluoride powder, nitrogen-nitrodimethylformamide and methyl ethyl ketone were prepared in a ratio of 1:20:15 by mass ratio, and stirred for 7 minutes to obtain a binder;

3) Preparation of MFI zeolite coating suspension: The MFI zeolite of step 1), the binder of step 2) and methyl ethyl ketone are prepared in a ratio of 4:8:20 by mass, and dispersed by ultrasonic for 400 min. After stirring for 10 h, a uniform and stable MFI zeolite coating suspension is obtained;

4) Preparation of MFI zeolite coated membrane: using step 3) MFI zeolite coating suspension infiltration high score After the sub-membrane is 20 s, it is cooled for 350 min; the above operation is repeated 15 times to obtain a MFI zeolite-coated separator having a uniform coating quality;

5) Treatment of MFI zeolite coated membrane: The MFI zeolite coated membrane of step 4) was dried at 70 ° C for 18 h, and the membrane was smoothed during the drying process without wrinkles and buckling.

The raw material type ratios and performance test data used in the above respective examples are shown in Table 1.

Table 1

The above is only the preferred embodiment of the present invention, and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention are subject to the present invention. Within the scope of protection required.

Claims

A method for preparing a MFI-type zeolite coated lithium ion battery separator, characterized in that the preparation method comprises the following steps:

1) Preparation of MFI-type zeolite: preparing a silica-alumina composite precursor or a pure silica precursor, and washing the prepared precursor with deionized water through a centrifuge, drying at room temperature, and then calcining at a high temperature;

2) preparing a binder: mixing polyvinylidene fluoride powder, nitrogen nitride dimethylformamide and methyl ethyl ketone in a ratio of 1:1 to 50:1 to 50 by mass ratio for 5 to 10 minutes;

3) Preparation of MFI zeolite coating suspension: mixing the MFI zeolite of step 1), the binder of step 2) and methyl ethyl ketone in a mass ratio of from 1 to 10:1 to 100:1 to 1000. After the solution is treated by ultrasonic for 1 to 1000 minutes, the solution is stirred for 1 to 100 hours;

4) Preparation of MFI zeolite coated membrane: the polymer membrane is impregnated with step 3) MFI zeolite coating suspension for 5 to 100 s, and then cooled for 1 to 1000 min; the operation is repeated 1 to 1000 times to obtain uniform coating quality. MFI zeolite coated membrane;

5) Treatment of MFI zeolite coated membrane: The MFI zeolite coated membrane of step 4) is dried for 10 to 100 h at 30 to 90 °C.
The method for preparing a MFI-type zeolite-coated lithium ion battery separator according to claim 1, wherein the preparing the silicon-aluminum composite precursor in the step 1) comprises: deionizing water, sodium hydroxide, and fourth Mixture of butyl ammonium bromide, Al 2 (SO 4 ) 3 · 18H 2 O and tetraethyl silicate in a ratio of 60:0.27:1.77:0 to 0.4:6.2 by mass ratio for 5-20 min, 160 Keep at ~180 °C for 10~12h.
The method for preparing a MFI-type zeolite-coated lithium ion battery separator according to claim 1, wherein the preparing the pure silica precursor in the step 1) comprises: dissolving silicon dioxide powder, sodium hydroxide and The mixture prepared by the ratio of the mass ratio of 90-110:5 to 10:20-30 is stirred for 5-20 min, and the temperature is kept at 100-150 °C for 10-15 h.
The method for preparing a MFI-type zeolite-coated lithium ion battery separator according to claim 3, wherein the silica powder, sodium hydroxide and tetrapropylammonium hydroxide are in a mass ratio of 100:7: The mixture prepared in a ratio of 30 was stirred for 10 min and kept at 120 ° C for 12 h.
The method for preparing a MFI-type zeolite-coated lithium ion battery separator according to claim 1, wherein the high-temperature calcination in the step 1) comprises: calcining at 550 ° C for 8 h.
The method for producing a MFI-type zeolite-coated lithium ion battery separator according to claim 1, wherein the silica has a particle diameter of 5 nm to 1 μm.
The method for preparing a MFI-type zeolite-coated lithium ion battery separator according to claim 1, wherein the content of the silicon-aluminum element in the MFI-type zeolite is not less than 1:1.
The method for preparing a MFI-type zeolite-coated lithium ion battery separator according to claim 1, wherein the MFI-type zeolite coating layer has a thickness of from 0.1 μm to 300 μm.
A method of preparing a MFI-type zeolite-coated lithium ion battery separator according to claim 1, wherein the prepared MFI-type zeolite-coated lithium ion battery separator has a thickness of from 10 μm to 500 μm.
The method for preparing a MFI-type zeolite-coated lithium ion battery separator according to claim 1, wherein the polymer separator is polyethylene, polypropylene or polyimide.