阅读说明：本技术 低水分陶瓷隔膜、制备方法及锂电池 (Low-moisture ceramic diaphragm, preparation method and lithium battery ) 是由 许成伟 张凯 于 2021-01-30 设计创作，主要内容包括：一种低水分陶瓷隔膜、制备方法及锂电池,该制备方法,包括以下步骤：(1)制备CMC-g-AM/SiO-2：(2)制备低水分陶瓷浆料：(3)制备低水分陶瓷隔膜。本发明通过将有机无机复合材料CMC-g-AM/SiO-2来代替浆料中常用的增稠剂CMC,并与无机材料硅溶胶结合以制备低水分陶瓷隔膜,使得本发明制备的低水分陶瓷隔膜含水量可以做到500ppm以下,从而对于该低水分陶瓷隔膜的运输、包装、存储不需要控制极低的湿度；该低水分陶瓷隔膜可以通过控制合成的条件来控制最终产物的吸水率,使得CMC-g-AM/SiO-2相比CMC具有更低的吸水饱和度,同时具有吸水快,加热易脱水的特点；采用本发明低水分陶瓷隔膜做成的锂电池,可以减少锂电池中的水分,使得锂电池相比同类产品具有更高的容量和更好的循环稳定性。(A low-moisture ceramic diaphragm, a preparation method and a lithium battery are provided, wherein the preparation method comprises the following steps: (1) preparation of CMC-g-AM/SiO 2 : (2) preparing low-moisture ceramic slurry: (3) preparing the low-moisture ceramic diaphragm. The invention adopts the organic-inorganic composite material CMC-g-AM/SiO 2 The low-moisture ceramic diaphragm is prepared by replacing a thickener CMC commonly used in slurry and combining with an inorganic material silica sol, so that the water content of the low-moisture ceramic diaphragm prepared by the invention can be below 500ppm, and the extremely low humidity does not need to be controlled for transportation, packaging and storage of the low-moisture ceramic diaphragm; the low-moisture ceramic diaphragm can control the water absorption of the final product by controlling the synthesis conditions, so that the CMC-g-AM/SiO 2 Compared with CMC, the composite material has lower water absorption saturation, fast water absorption and easy heatingThe characteristic of dehydration; the lithium battery made of the low-moisture ceramic diaphragm can reduce moisture in the lithium battery, so that the lithium battery has higher capacity and better cycle stability compared with similar products.)

1. A low moisture ceramic separator for use in a lithium battery, comprising: comprises a base film and ceramic layers coated on the surfaces of two sides of the base film, wherein the ceramic layers are composed of inorganic ceramic particles and CMC-g-AM/SiO₂The adhesive comprises an adhesive, a dispersing agent, a wetting agent and deionized water.

2. The low moisture ceramic separator of claim 1, wherein the inorganic ceramic particles comprise one or more of alumina, boehmite, silica, titania.

3. The low moisture ceramic diaphragm of claim 1, wherein the adhesive comprises one or more of carboxyl neoprene latex, two-component acrylic copolymer emulsion and acrylic copolymer resin aqueous solution, styrene-butadiene latex, and silicone modified acrylate.

4. The low moisture ceramic separator of claim 1, wherein the dispersant comprises one or more of N, N-dimethylaminopropylamine, polyethylene polyamine, octadecylamidopropylamine, ethylene oxide and propylene oxide copolymer, hydroxyl-terminated polyacrylate, and carboxyl-terminated polyacrylate.

5. The low moisture ceramic separator of claim 1, wherein the wetting agent comprises one or more of sodium dodecyl benzene sulfonate, fatty acid glycerides, perfluorosulfonates, silane surfactants, and modified polyol surfactants.

6. A method of making a low moisture ceramic membrane according to any one of claims 1 to 5, comprising the steps of:

(1) preparation of CMC-g-AM/SiO₂: introducing nitrogen into distilled water dissolved with CMC and simultaneously adding an initiator, then adding AM monomer, cross-linking agent N, N-methylene-bisacrylamide and silica sol for mixing and stirring, and sequentially saponifying, washing, vacuum drying, crushing and grinding a product obtained after stirring reaction to obtain CMC-g-AM/SiO₂；

(2) Preparing low-moisture ceramic slurry: mixing and stirring inorganic ceramic particles, deionized water and a dispersing agent, putting the mixture into a grinding machine for grinding to obtain slurry of the inorganic ceramic particles, and then sequentially adding CMC-g-AM/SiO₂Stirring the aqueous solution, the adhesive and the surfactant to obtain low-moisture ceramic slurry;

(3) preparing a low-moisture ceramic diaphragm: and coating the low-moisture ceramic slurry on a polyolefin microporous membrane, and drying in an oven at the temperature of 50-80 ℃ to obtain the low-moisture ceramic diaphragm.

7. The preparation method of the low-moisture ceramic diaphragm according to claim 6, wherein the mass ratio of the CMC to the monomer AM is 1:2-1:5, the initiator accounts for 2% -8% of the amount of the monomer AM, the cross-linking agent N, N-methylenebisacrylamide accounts for 0.08% -0.2% of the amount of the monomer AM, and the silica sol accounts for 5% -20% of the amount of the monomer AM.

8. The method of claim 6, wherein the inorganic ceramic particles comprise 30-45% of the weight of the deionized water and the inorganic ceramic particles, and the CMC-g-AM/SiO is present in the inorganic ceramic particles₂The water solution accounts for 0.5-2% of the weight of the inorganic ceramic particles, the adhesive accounts for 4-6% of the weight of the inorganic ceramic particles, the dispersant accounts for 0.1-0.5% of the weight of the inorganic ceramic particles, and the wetting agent accounts for 0.2-0.5% of the weight of the deionized water.

9. The low moisture ceramic separator according to claim 6, wherein the polyolefin microporous membrane comprises a polyethylene separator or a polypropylene separator, the polyolefin microporous membrane has a thickness ranging from 5 to 40 μm, and the coated inorganic ceramic layer has a thickness ranging from 2 to 5 μm.

10. A lithium battery comprising the low-moisture ceramic separator according to any one of claims 1 to 5, and a positive electrode and a negative electrode provided on both sides of the low-moisture ceramic separator.

Technical Field

The invention relates to the technical field of lithium battery diaphragm production, in particular to a low-moisture ceramic diaphragm, a preparation method and a lithium battery.

Background

With the rapid development of the electric automobile industry, the demand of lithium batteries on the market is more and more. Among other things, lithium batteries generally include a positive electrode material, a negative electrode material, a separator, and an electrolyte. The separator is one of the key inner layer components of the lithium battery, and mainly has the functions of separating the positive electrode from the negative electrode of the battery, preventing the two electrodes from contacting and short-circuiting, and enabling electrolyte ions to pass through. At present, the conventional polyolefin microporous membrane is widely used as a lithium battery diaphragm due to excellent chemical stability and mechanical strength, however, the polyolefin microporous membrane has poor high-temperature stability, and the problem of poor wetting on a polar electrolyte causes larger battery impedance, low cycle performance and even internal short circuit of the battery, thereby greatly limiting the development space of the battery.

Aiming at the problems of poor high-temperature stability and poor wettability to a polar electrolyte of a polyolefin microporous membrane, people mainly solve the problems by the following modes: coating a ceramic particle material and a gel polymer on the surface of the microporous membrane; simultaneously coating ceramic particles and a gel polymer material on the surface of the microporous membrane; coating by using an aqueous system or an oily system. The problems of the oily system coating are mainly high production line cost, difficult solvent recovery, environmental pollution and the like; the aqueous coating has a problem in that the moisture content of the coated separator cannot be effectively controlled. Because the lithium battery is internally provided with a relatively complex chemical system, the reaction process and the result of the chemical system are closely related to moisture. The out-of-control or coarsening control of the moisture causes the over-standard existence of the moisture in the battery, which not only can cause the decomposition of electrolyte lithium salt, but also can cause the bad influence on the film formation and the stability of the anode and cathode materials, and cause the electrochemical characteristics of the lithium battery, such as capacity, internal resistance and product characteristics, to generate obvious deterioration. Thus, each industry has placed stringent requirements on the water content of the water-based coated membranes.

At present, the moisture control of a coating film is mainly controlled from three aspects of a coating slurry formula, a processing technology and environmental humidity. The most effective of these is the control of the coating slip formulation, which is commonly used in coating slip formulations including: aluminum oxide, CMC (sodium carboxymethylcellulose), adhesive, dispersant and wetting agent. CMC is a material with extremely strong water absorption property and can absorb water with the mass being hundreds of times or even thousands of times of the self weight. In order to prevent the final coating film from having high moisture content, current control means mainly use CMC having higher viscosity to reduce the amount thereof, or modify the polymer such as by grafting, copolymerization, crosslinking, etc. to introduce a hydrophobic functional group instead of CMC, thereby reducing the moisture content of the separator. The method only reduces the water absorption of a certain component in the ceramic layer so as to reduce the water content of the ceramic diaphragm, but has no effect on other components of the lithium battery, such as anode and cathode materials, electrolyte and the like.

Disclosure of Invention

Based on the above, the invention aims to provide a low-moisture ceramic diaphragm, a preparation method and a lithium battery, which can reduce the moisture content of the diaphragm and the moisture content of other components, so as to solve the problem of overhigh moisture content of internal components of the lithium battery.

In one aspect, the present invention provides a low moisture ceramic separator including a base film, and ceramic layers coated on both side surfaces of the base film, wherein the ceramic layers are made of inorganic ceramic particles, CMC-g-AM/SiO₂The adhesive comprises an adhesive, a dispersing agent, a wetting agent and deionized water.

Further, the inorganic ceramic particles comprise one or more of aluminum oxide, boehmite, silicon dioxide and titanium dioxide.

Further, the adhesive comprises one or more of carboxyl neoprene latex, double-component acrylic acid copolymer emulsion, acrylic acid copolymer resin aqueous solution, styrene-butadiene latex and organic silicon modified acrylate.

Further, the dispersant comprises one or more of N, N-dimethylaminopropylamine, polyethylene polyamine, octadecylamidopropylamine, a copolymer of ethylene oxide and propylene oxide, a hydroxyl-terminated polyacrylate and a carboxyl-terminated polyacrylate.

Further, the wetting agent comprises one or more of sodium dodecyl benzene sulfonate, fatty glyceride, perfluorosulfonate, silane surfactant and modified polyol surfactant.

On the other hand, the invention also provides a preparation method of the low-moisture ceramic diaphragm, which comprises the following steps:

(1) preparation of CMC-g-AM/SiO₂: introducing nitrogen into distilled water dissolved with CMC and simultaneously adding an initiator, then adding AM monomer, cross-linking agent N, N-methylene-bisacrylamide and silica sol for mixing and stirring, and sequentially saponifying, washing, vacuum drying, crushing and grinding a product obtained after stirring reaction to obtain CMC-g-AM/SiO₂；

(2) Preparing low-moisture ceramic slurry: mixing and stirring inorganic ceramic particles, deionized water and a dispersing agent, putting the mixture into a grinding machine for grinding to obtain slurry of the inorganic ceramic particles, and then sequentially adding CMC-g-AM/SiO₂Stirring the aqueous solution, the adhesive and the surfactant to obtain low-moisture ceramic slurry;

(3) preparing a low-moisture ceramic diaphragm: and coating the low-moisture ceramic slurry on a polyolefin microporous membrane, and drying in an oven at the temperature of 50-80 ℃ to obtain the low-moisture ceramic diaphragm.

Furthermore, the mass ratio of the CMC to the monomer AM is 1:2-1:5, the initiator accounts for 2% -8% of the amount of the monomer AM, the cross-linking agent N, N-methylene-bisacrylamide accounts for 0.08% -0.2% of the amount of the monomer AM, and the silica sol accounts for 5% -20% of the amount of the monomer AM.

Further, the inorganic ceramic particles account for 30 to 45 percent of the weight of the deionized water and the inorganic ceramic particles, and the inorganic ceramic particles are CMC-g-AM/SiO₂The water solution accounts for 0.5-2% of the weight of the inorganic ceramic particles, the adhesive accounts for 4-6% of the weight of the inorganic ceramic particles, the dispersant accounts for 0.1-0.5% of the weight of the inorganic ceramic particles, and the wetting agent accounts for 0.2-0.5% of the weight of the deionized water.

Further, the polyolefin microporous membrane comprises a polyethylene membrane or a polypropylene membrane, the thickness of the polyolefin microporous membrane ranges from 5 to 40 μm, and the thickness of the coated inorganic ceramic layer ranges from 2 to 5 μm.

In addition, the invention also provides a lithium battery which comprises the low-moisture ceramic diaphragm, and a positive electrode and a negative electrode which are arranged on two sides of the low-moisture ceramic diaphragm.

In conclusion, the invention has the following advantages:

firstly, the invention is prepared by mixing an organic-inorganic composite material CMC-g-AM/SiO₂The low-moisture ceramic diaphragm is prepared by replacing a thickener CMC commonly used in slurry and combining with an inorganic material silica sol, so that the water content of the low-moisture ceramic diaphragm prepared by the invention can be below 500ppm, and the extremely low humidity does not need to be controlled for transportation, packaging and storage of the low-moisture ceramic diaphragm;

secondly, the low-moisture ceramic diaphragm can control the water absorption rate of the final product by controlling the synthesis conditions, so that the CMC-g-AM/SiO₂Compared with CMC, the composite material has lower water absorption saturation, and has the characteristics of quick water absorption and easy dehydration by heating;

thirdly, because the low-moisture ceramic diaphragm has the characteristics of strong adsorption capacity and difficult dehydration, when the low-moisture ceramic diaphragm is used for manufacturing the lithium battery, the low-moisture ceramic diaphragm can absorb residual moisture in the positive electrode, the negative electrode and electrolyte of the lithium battery and is difficult to dissipate;

fourth, this low moisture ceramic diaphragm can toast the process before the encapsulation after assembling into the lithium cell usually, can toast out the moisture that the lithium cell absorbed like this through this process to reduce the moisture in the lithium cell, make the lithium cell compare like product have higher capacity and better cycle stability.

Drawings

FIG. 1 is a HORIBA diagram of a low moisture ceramic slurry in accordance with an embodiment of the present invention.

The following detailed description will further illustrate the invention in conjunction with the above-described figures.

Detailed Description

To facilitate an understanding of the invention, the invention will now be described more fully with reference to the accompanying drawings. Several embodiments of the invention are presented in the drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

It will be understood that when an element is referred to as being "secured to" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "left," "right," and the like as used herein are for illustrative purposes only.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

In one aspect, the invention provides a low-moisture ceramic diaphragm, which comprises a base film and ceramic layers coated on the two side surfaces of the base film, wherein the ceramic layers are made of inorganic ceramic particles and CMC-g-AM/SiO₂The adhesive comprises an adhesive, a dispersing agent, a wetting agent and deionized water.

In the present invention, the base film includes a polyethylene film or a polypropylene film.

In a preferred embodiment of the present invention, the inorganic ceramic particles include one or more of alumina, boehmite, silica, and titania. Specifically, in the embodiment, the ceramic particle main material can be selected from conventional aluminum trioxide with a large market ratio according to market demands, so that the product price is ensured to be stable; boehmite with excellent performance can be selected, and the method has the advantages of low impurity content, less magnetic foreign matters and stable electrical performance; silicon dioxide and titanium dioxide can also be properly added to increase the hardness of the ceramic membrane and improve the heat resistance of the membrane. Therefore, different product specifications can be prepared according to different market divisions so as to meet different demands.

In another preferred embodiment of the present invention, the adhesive comprises one or more of carboxyl neoprene latex, two-component acrylic copolymer emulsion, acrylic copolymer resin aqueous solution, styrene-butadiene latex and organic silicon modified acrylate. In the embodiment, the carboxyl neoprene latex and the bi-component acrylic acid polymer latex have the characteristics of stable emulsion and high viscosity, and can greatly improve the peeling resistance of the ceramic coating; the acrylic copolymer resin aqueous solution, the styrene-butadiene latex and the organic silicon modified acrylate have the advantages of narrow latex particle size distribution, good fluidity and proper viscosity, and meanwhile, the modified resin is suitable for the corrosivity of electrolyte and keeps good mechanical stability and chemical stability.

In a preferred embodiment of the present invention, the dispersant comprises one or more of N, N-dimethylaminopropylamine, polyethylene polyamine, octadecylaminopropylamine, a copolymer of ethylene oxide and propylene oxide, a hydroxyl-terminated polyacrylate and a carboxyl-terminated polyacrylate. It should be noted that, in this embodiment, the dispersant mainly functions to quickly and fully wet the particles, shorten the particle grinding time in the process of preparing the ceramic slurry, and they can provide anchoring groups to be tightly adsorbed on the solid surface through ionic bond, covalent bond, hydrogen bond, van der waals force and other interactions, so as to prevent the dispersant from being desorbed.

In another preferred embodiment of the present invention, the wetting agent comprises one or more of sodium dodecylbenzene sulfonate, fatty acid glyceride, perfluorosulfonate, silane surfactant and modified polyol surfactant. Specifically, in the embodiment, the wetting agent is added in a proper amount, so that the wettability of the slurry to the isolation can be improved, the surface tension of the diaphragm can be reduced, the stable film forming of the slurry can be realized, and the problems of missing coating, uneven coating and the like in the actual operation process can be reduced. Meanwhile, the selected active agent has lower ionic conductivity and low foam property, and meets the requirements of preventing and controlling environmental pollution.

On the other hand, the invention also provides a preparation method of the low-moisture ceramic diaphragm, which comprises the following steps:

(1) preparation of CMC-g-AM/SiO₂: introducing nitrogen into distilled water dissolved with CMC and simultaneously adding an initiator, then adding AM monomer (acrylamide), a cross-linking agent N, N-methylene-bisacrylamide and silica sol for mixing and stirring, and sequentially saponifying, washing, vacuum drying, and the like the product after stirring reaction,Crushing and grinding to obtain CMC-g-AM/SiO₂；

In the step, the inorganic material silica sol is a high-activity adsorption material with a porous structure and has the characteristics that the inorganic material silica sol is difficult to replace other similar materials, the silica sol has high adsorption performance and good thermal stability, so the silica sol absorbs water quickly and can absorb 40 percent of water by the weight of the silica sol, but the dehydration is usually carried out at the temperature of about 100 ℃, so the silica sol is adopted to prepare the CMC-g-AM/SiO₂。

Specifically, in the step, the mass ratio of the CMC to the monomer AM is 1:2-1:5, the initiator accounts for 2% -8% of the amount of the monomer AM, the cross-linking agent N, N-methylene-bisacrylamide accounts for 0.08% -0.2% of the amount of the monomer AM, and the silica sol accounts for 5% -20% of the amount of the monomer AM.

(2) Preparing low-moisture ceramic slurry: mixing and stirring inorganic ceramic particles, deionized water and a dispersing agent, putting the mixture into a grinding machine for grinding to obtain slurry of the inorganic ceramic particles, and then sequentially adding CMC-g-AM/SiO₂Stirring the aqueous solution, the adhesive and the surfactant to obtain low-moisture ceramic slurry;

specifically, in the step, the inorganic ceramic particles account for 30-45 percent of the weight of the deionized water and the inorganic ceramic particles, and the inorganic ceramic particles are CMC-g-AM/SiO₂The water solution accounts for 0.5-2% of the weight of the inorganic ceramic particles, the adhesive accounts for 4-6% of the weight of the inorganic ceramic particles, the dispersant accounts for 0.1-0.5% of the weight of the inorganic ceramic particles, and the wetting agent accounts for 0.2-0.5% of the weight of the deionized water.

Referring to fig. 1, preferably, the inorganic ceramic particles in this step are alumina ceramic particles D50, and it can be seen from the figure that the particle size of the alumina ceramic particles D50 is 0.6-1 μm.

(3) Preparing a low-moisture ceramic diaphragm: and coating the low-moisture ceramic slurry on a polyolefin microporous membrane, and drying in an oven at the temperature of 50-80 ℃ to obtain the low-moisture ceramic diaphragm.

In this step, the coating method used is one of spray coating, micro-gravure coating, electrophoretic coating, or flow coating.

Specifically, in this step, the polyolefin microporous membrane includes a polyethylene membrane or a polypropylene membrane.

Preferably, in this step, the polyolefin microporous membrane has a thickness ranging from 5 to 40 μm, and the inorganic ceramic layer is coated to have a thickness ranging from 2 to 5 μm.

In addition, the invention also provides a lithium battery which comprises the low-moisture ceramic diaphragm, and a positive electrode and a negative electrode which are arranged on two sides of the low-moisture ceramic diaphragm.

In conclusion, the invention has the following advantages:

firstly, the invention is prepared by mixing an organic-inorganic composite material CMC-g-AM/SiO₂The low-moisture ceramic diaphragm is prepared by replacing a thickener CMC commonly used in slurry and combining with an inorganic material silica sol, so that the water content of the low-moisture ceramic diaphragm prepared by the invention can be below 500ppm, and the extremely low humidity does not need to be controlled for transportation, packaging and storage of the low-moisture ceramic diaphragm;

secondly, the low-moisture ceramic diaphragm can control the water absorption rate of the final product by controlling the synthesis conditions, so that the CMC-g-AM/SiO₂Compared with CMC, the composite material has lower water absorption saturation, and has the characteristics of quick water absorption and easy dehydration by heating;

thirdly, because the low-moisture ceramic diaphragm has the characteristics of strong adsorption capacity and difficult dehydration, when the low-moisture ceramic diaphragm is used for manufacturing the lithium battery, the low-moisture ceramic diaphragm can absorb residual moisture in the positive electrode, the negative electrode and electrolyte of the lithium battery and is difficult to dissipate;

fourth, this low moisture ceramic diaphragm can toast the process before the encapsulation after assembling into the lithium cell usually, can toast out the moisture that the lithium cell absorbed like this through this process to reduce the moisture in the lithium cell, make the lithium cell compare like product have higher capacity and better cycle stability.

The following is a description of specific examples:

minimum Range values example 1

(1) Preparation of CMC-g-AM/SiO₂: adding 0.4kg into a three-mouth bottleAdding a proper amount of distilled water to dissolve the CMC, stirring in a water bath at 50 ℃ for 15min, introducing nitrogen and adding 40g of initiator; weighing 2kg of AM monomer, putting the AM monomer into a small beaker, adding a small amount of distilled water for dissolving, and then adding 1g of cross-linking agent N, N-methylene-bisacrylamide and 0.1kg of silica sol; stirring the mixture until the mixture is uniformly mixed and fully dissolved, then dropwise adding the mixture into the three-necked bottle for reaction, stirring, and reacting for 3 hours to obtain a product; aging the product, adding a proper amount of NaOH, saponifying at a proper water bath temperature, taking out after 30min, washing, vacuum drying, crushing, grinding and bagging for later use.

(2) Preparing low-moisture ceramic slurry: 19kg of deionized water was added to tank A, and 1kg of CMC-g-AM/SiO was added to tank A₂Stirring overnight to prepare 5% CMC-g-AM/SiO₂The aqueous solution is reserved; weighing 70kg of deionized water in a tank B, then respectively weighing 30kg of inorganic ceramic particles and 150g of dispersing agent in the tank B, stirring for 20min, circularly grinding the slurry in the tank B for 1h by a grinder, transferring the slurry to a tank C to obtain slurry of the inorganic ceramic particles D50 with the particle size of 0.6-1 mu m, respectively weighing 3kg of CMC-g-AM/SiO₂And respectively stirring the aqueous solution, 1.2kg of adhesive and 140g of wetting agent in a tank C for 30min to obtain the low-moisture ceramic slurry.

(3) Preparing a low-moisture ceramic diaphragm: the prepared low-moisture ceramic slurry was coated on a polyethylene separator of 5 μm by a micro-concave roller, and the coated film was dried by an oven set at a temperature of about 50 ℃ to obtain a low-moisture ceramic separator for a lithium battery having a coating layer thickness of 2 μm, and the moisture content of the low-moisture ceramic separator was measured to be 587 ppm.

(4) Preparing a lithium battery: the low-moisture ceramic diaphragm is made into an experimental lithium battery with the size of 42 multiplied by 34 multiplied by 50mm, and the anode and the cathode are respectively made of active substances (LiCoO)₂Graphite), conductive agent carbon black, binder CMC and SBR are formed according to a certain proportion; coating, drying, rolling, cutting the prepared slurry, winding the prepared slurry by using the low-moisture ceramic diaphragm to prepare a battery cell, vacuum drying, welding and injecting electrolyte; the mass fraction of water in the lithium battery made of the low-moisture ceramic diaphragm was measured to be 0.01%, and the battery capacity was measured to be 917mAhAfter 200 cycles at room temperature, the capacity decayed to 94.4%.

Maximum Range value example 2

(1) Preparation of CMC-g-AM/SiO₂: adding 1kg of CMC into a three-neck flask, adding a proper amount of distilled water for dissolving, stirring in a water bath at 70 ℃ for 15min, introducing nitrogen and adding 160g of initiator; weighing 2kg of AM monomer, putting the AM monomer into a small beaker, adding a small amount of distilled water for dissolving, and then adding 4g of cross-linking agent N, N-methylene-bisacrylamide and 0.4kg of silica sol; stirring the mixture until the mixture is uniformly mixed and fully dissolved, then dropwise adding the mixture into the three-necked bottle for reaction, stirring, and reacting for 3 hours to obtain a product; aging the product, adding a proper amount of NaOH, saponifying at a proper water bath temperature, taking out after 30min, washing, vacuum drying, crushing, grinding and bagging for later use.

(2) Preparing low-moisture ceramic slurry: 9kg of deionized water was added to tank A, and 1kg of CMC-g-AM/SiO was added to tank A₂Stirring overnight to prepare 10% CMC-g-AM/SiO₂The aqueous solution is reserved; weighing 55kg of deionized water in a tank B, then respectively weighing 45kg of inorganic ceramic particles and 675g of dispersing agent in the tank B, stirring for 20min, circularly grinding the slurry in the tank B for 1h by a grinder, transferring the slurry to a tank C to obtain slurry of the inorganic ceramic particles D50 with the particle size of 0.6-1 mu m, respectively weighing 9kg of CMC-g-AM/SiO₂Respectively stirring the aqueous solution, 2.7kg of adhesive and 275g of wetting agent in a tank C for 30min to obtain low-moisture ceramic slurry;

(3) preparing a low-moisture ceramic diaphragm: the prepared low-moisture ceramic slurry is coated on a polyethylene diaphragm with the thickness of 40 mu m by a micro-concave roller, and the coating film is dried by an oven with the temperature set to be about 80 ℃ to obtain the low-moisture ceramic diaphragm for the lithium battery with the coating thickness of 5 mu m, wherein the measured moisture content of the ceramic diaphragm is 636 ppm.

(4) Preparing a lithium battery: the low-moisture ceramic diaphragm is made into an experimental lithium battery with the size of 42 multiplied by 34 multiplied by 50mm, and the anode and the cathode are respectively made of active substances (LiCoO)₂Graphite), conductive agent carbon black, binder CMC and SBR are formed according to a certain proportion; the prepared slurry is coated, dried, rolled and cut, and then the invention is usedWinding the provided low-moisture ceramic diaphragm to prepare a battery core, vacuum drying, welding and injecting electrolyte; the mass fraction of water in the lithium battery made of the low-moisture ceramic diaphragm is measured to be 0.012%, the battery capacity is measured to be 912mAh, and after 200 times of room temperature circulation, the capacity is attenuated to 93.1%.

General example 3

(1) Preparation of CMC-g-AM/SiO₂: adding 0.4kg of CMC into a three-neck flask, adding a proper amount of distilled water for dissolving, stirring in a water bath at 50 ℃ for 15min, introducing nitrogen and adding 130g of initiator; weighing 2kg of AM monomer, putting the AM monomer into a small beaker, adding a small amount of distilled water for dissolving, and then adding 3.2g of cross-linking agent N, N-methylene-bisallylamine and 0.3kg of silica sol; stirring the mixture until the mixture is uniformly mixed and fully dissolved, then dropwise adding the mixture into the three-necked bottle for reaction, stirring, and reacting for 3 hours to obtain a product; aging the product, adding a proper amount of NaOH, saponifying at a proper water bath temperature, taking out after 30min, washing, vacuum drying, crushing, grinding and bagging for later use.

(2) Preparing low-moisture ceramic slurry: 19kg of deionized water was added to tank A, and 1kg of CMC-g-AM/SiO was added to tank A₂Stirring overnight to prepare 5% CMC-g-AM/SiO₂The aqueous solution is reserved; weighing 60kg of deionized water in a tank B, then respectively weighing 38kg of inorganic ceramic particles and 350g of dispersing agent in the tank B, stirring for 20min, circularly grinding the slurry in the tank B for 1h by a grinder, transferring the slurry to a tank C to obtain slurry of the inorganic ceramic particles D50 with the particle size of 0.6-1 mu m, respectively weighing 6.84kg of CMC-g-AM/SiO₂Respectively stirring the aqueous solution, 1.9kg of adhesive and 210g of wetting agent in a tank C for 30min to obtain low-moisture ceramic slurry;

(3) preparing a low-moisture ceramic diaphragm: the prepared low-moisture ceramic slurry is coated on a 16-micron polyethylene diaphragm through a micro-concave roller, the coating film is dried through an oven with the temperature set to be about 55 ℃, the low-moisture ceramic diaphragm for the lithium battery with the coating layer thickness of 4 microns is obtained, and the measured moisture content of the ceramic diaphragm is 487 ppm.

(4) Preparing a lithium battery: the low-moisture ceramic diaphragm is made into an experimental lithium battery with the size of 42 multiplied by 34 multiplied by 50mm, positive and negative electrodes are respectively made of active material (LiCoO)₂Graphite), conductive agent carbon black, binder CMC and SBR are formed according to a certain proportion; the prepared slurry is coated, dried, rolled and cut, and then is wound by the low-moisture ceramic diaphragm provided by the invention to prepare a battery core, and the battery core is vacuum-dried, welded and injected with electrolyte. The mass fraction of the water content of the lithium battery made of the low-moisture ceramic diaphragm is measured to be 0.008 percent, the battery capacity is measured to be 932mAh, and after 200 times of room temperature circulation, the capacity is attenuated to 95.6 percent.

Prior art example 4

(1) Preparing low-moisture ceramic slurry: 19kg of deionized water was added to tank A, and 1kg of CMC-g-AM/SiO was added to tank A₂Stirring overnight to prepare a 5% CMC aqueous solution for later use; weighing 60kg of deionized water in a tank B, then respectively weighing 38kg of inorganic ceramic particles and 350g of dispersing agent in the tank B, stirring for 20min, then circularly grinding the slurry in the tank B for 1h by a grinder, transferring the slurry to a tank C to obtain slurry of the inorganic ceramic particles D50 with the particle size of 0.6-1 mu m, respectively weighing 6.84kg of CMC aqueous solution, 1.9kg of adhesive and 210g of wetting agent in the tank C, and respectively stirring for 30min to obtain low-moisture ceramic slurry;

(2) preparing a low-moisture ceramic diaphragm: the prepared low-moisture ceramic slurry is coated on a 16-micron polyethylene diaphragm through a micro-concave roller, the coating film is dried through an oven with the temperature set to be about 55 ℃, the low-moisture ceramic diaphragm for the lithium battery with the coating layer thickness of 4 microns is obtained, and the measured moisture content of the ceramic diaphragm is 1346 ppm.

(3) Preparing a lithium battery: the low-moisture ceramic diaphragm is made into an experimental lithium battery with the size of 42 multiplied by 34 multiplied by 50mm, and the anode and the cathode are respectively made of active substances (LiCoO)₂Graphite), conductive agent carbon black, binder CMC and SBR are formed according to a certain proportion; coating, drying, rolling, cutting the prepared slurry, winding the slurry with a common ceramic diaphragm and the low-moisture ceramic diaphragm provided by the invention to prepare a battery core, vacuum drying, welding and injecting electrolyte; the mass fraction of water in the lithium battery made of the common ceramic diaphragm is measured to be 0.023%, the capacity of the battery is measured to be 896mAh, and the capacity is attenuated to 88.7% after 200 times of room temperature circulation.

The data pairs for the four examples above are shown in the following table:

as can be seen from the above table, the experimental lithium battery fabricated using the low-moisture ceramic separator of the present invention has a low moisture mass fraction, and has a higher capacity and better cycle stability than the lithium battery in the prior art.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.