CN105006539A - Cellulose-composite polyethylene diaphragm for lithium ion battery and preparation method thereof - Google Patents

Abstract

The invention relates to the technical field of a lithium ion battery diaphragm technology and discloses a cellulose-composite polyethylene diaphragm for a lithium ion battery and a preparation method thereof. The diaphragm comprises a diaphragm base and a coating. The diaphragm base is prepared from 65-75 parts by weight of polyethylene, 5-10 parts by weight of vinyl acrylate, 5-10 parts by weight of natural cellulose slurry, 3-5 parts by weight of keratin, 1-3 parts by weight of ethylene glycol diglycidyl ether and 8-10 parts by weight of brown algae extract. The coating is prepared by coating the surface of the diaphragm base with coating slurry and is prepared from 1-5 parts by weight of a nanometer inorganic filler, 3-5 parts by weight of a binder, 20-30 parts by weight of vinyl acrylate, 1-5 parts by weight of mussel shell powder, 1-5 parts by weight of halloysite nanotubes and 57-67 parts by weight of an organic solvent. The cellulose-composite polyethylene diaphragm can resist a high temperature, keeps size stability after heating, has good moisture absorption and retention capability and good wellability with electrolyte, and has good stabbing strength.

Description

A kind of polyethylene separator compounded with cellulose for lithium ion battery and preparation method thereof

technical field

The invention relates to the technical field of preparation of lithium-ion battery separators, in particular to a polyethylene separator compounded with cellulose for lithium-ion batteries and a preparation method thereof.

Background technique

The diaphragm is a very important part of the lithium-ion battery. The main function of the diaphragm is to separate the positive and negative electrodes of the battery and prevent the short circuit caused by the contact between the positive and negative electrodes. The separator itself is a non-conductive material with certain micropores and porosity, allowing electrolyte ions to pass through. The performance of the separator determines the interface structure and internal resistance of the battery, which directly affects the capacity, cycle performance, and safety performance of the battery. In the prior art, most lithium-ion batteries use polyolefin porous membranes as their diaphragm materials.

However, the separator made of polyolefin is not ideal in terms of thermal stability, wettability to electrolyte, and moisture absorption and liquid retention capacity. The infiltration performance of the electrolyte and the lack of moisture absorption and liquid retention capacity limit the rate performance of the lithium-ion battery; and when the internal temperature of the lithium-ion battery rises sharply, the polyolefin separator is easy to be heated and melted, and the size of the separator is easy to shrink, which directly leads to a short circuit of the battery . In order to solve this problem, a common solution is to coat a layer of ceramic slurry on the surface of the diaphragm. The ceramic slurry has high temperature resistance and greatly improves the dimensional stability of the diaphragm. But on the other hand, the setting of the ceramic slurry blocks the micropores on the original diaphragm to a certain extent, and reduces the wettability and gas permeability of the diaphragm to a certain extent. In addition, the ceramic slurry is generally bonded by an adhesive. Attached to the base film of the diaphragm, the adhesive force is not strong enough, and it is easy to fall off after a long time.

Contents of the invention

In order to solve the above technical problems, the present invention provides a polyethylene separator compounded with cellulose for lithium ion batteries and a preparation method thereof. The separator of the present invention can withstand high temperature, and can maintain dimensional stability after being heated, and at the same time, it also has strong moisture absorption and liquid retention capacity and good wettability to electrolyte; in addition, the separator of the present invention also has better anti-spike strength.

The specific technical scheme of the present invention is: a kind of polyethylene diaphragm that is compounded with cellulose for lithium ion battery, comprises diaphragm base material and the coating that is arranged on the surface of described diaphragm base material, and described diaphragm base material consists of the following total parts by weight Prepared for 100 parts of substance: 75-75 parts by weight of polyethylene, 5-10 parts by weight of vinyl acrylate, 5-10 parts by weight of natural cellulose pulp, 3-5 parts by weight of keratin, 1 -3 parts by weight of ethylene glycol diglycidyl ether, 8-10 parts by weight of brown algae extract; the coating is formed by coating the coating slurry on the surface of the diaphragm substrate, and the coating slurry is formed by the following Prepared from 100 parts by weight of substances: 1-5 parts by weight of nano inorganic filler, 3-5 parts by weight of binder, 20-30 parts by weight of vinyl acrylate, 1-5 parts by weight of mussel shell powder , 1-5 parts by weight of halloysite nanotubes, 57-67 parts by weight of organic solvent; the nano-inorganic filler is selected from one or more of nano-alumina, nano-titanium oxide or nano-zirconia.

Natural cellulose pulp contains a large amount of natural cellulose and a small amount of pectin. Both natural cellulose and pectin have good hygroscopicity and thermal stability. After they are combined with polyethylene to form a film, they can make up for the hygroscopicity of polyethylene. , poor thermal stability, but cellulose also has certain defects, that is, its wet strength is poor. The present invention uses ethylene glycol diglycidyl ether to cross-link keratin with natural cellulose, and natural The cross-linking of cellulose and keratin is thick, and its wet strength can be greatly improved. In addition, keratin and brown algae extract also have good hygroscopicity, which can further improve the liquid absorption and moisturizing ability of the diaphragm. The nano-inorganic fillers in the coating slurry can improve the high temperature resistance and mechanical strength of the coating. Both mussel shell powder and halloysite nanotubes have a pore structure, which can improve the hygroscopicity and mechanical strength of the coating, and at the same time provide additional To enhance the flame retardant performance of the coating, the vinyl acrylate in the diaphragm substrate and the coating slurry is a self-initiating UV-curable substance. When the coating slurry is coated on the diaphragm substrate, it can be cured after ultraviolet light irradiation. The vinyl acrylate in the coating slurry and the vinyl acrylate in the diaphragm substrate can be quickly cured and cross-linked, coupled with the bonding of ordinary adhesives, compared with a single adhesive, the coating is firmly bonded The strength is stronger, and the nano-inorganic fillers, mussel shell powder and halloysite nanotubes in the coating are not easy to fall off, and the dimensional stability of the separator substrate is also more obvious.

As preferably, the preparation method of described natural cellulose slurry is as follows:

(1) take by weighing the short-staple cotton of 100 parts by weight and the bamboo residue of 100 parts by weight respectively, and add described short-staple cotton and bamboo residue into 600 parts by weight of concentration together in the sodium hydroxide solution of 15wt%, to containing The sodium hydroxide solution of short cotton linters and bamboo residues is vacuum-cooked, the cooking temperature is 220°C, and the cooking time is 4h.

(2) take out and wash the short cotton linters and bamboo dregs after cooking, add the short linters and bamboo dregs together to 2000 parts by weight of ethanol solution with a concentration of 40wt%, and then carry out microwave treatment to ethanol solution, wherein The microwave frequency is 2450MHZ, the microwave power is 800W, the temperature is 150°C, and the time is 45min; after the microwave treatment is completed, the ethanol solution is filtered, and the solid filtrate is taken.

Natural cellulose is difficult to dissolve in water and organic solvents. Microwave treatment is performed on short lint and bamboo residue after cooking, and the solid filter is taken after filtration, which can remove lignin and pectin impurities in short lint and bamboo residue. Improves the purity of natural cellulose.

(3) After the solid filtrate is washed, it is beaten by a beater, and after beating, the obtained product is successively chlorinated, alkalized, bleached, impurity removed, and concentrated to obtain a natural cellulose fiber slurry.

Preferably, the solid content of the natural cellulose fiber slurry is 75-85wt%.

As preferably, the preparation method of described keratin is as follows:

(1) Take 500 parts by weight of defatted duck feathers, add it into water and perform high-pressure cooking, wherein the temperature is 160°C, the pressure is 1.8-2.0Mpa, and the cooking time is 1h. Cooking the defatted duck feathers can hydrolyze and soften the defatted duck feathers, which is more conducive to subsequent extraction.

(2) Take 5000 parts by weight of water, add sodium dodecylbenzenesulfonate, sodium sulfide, and urea to the water successively to prepare an extract, in which dodecylbenzenesulfonic acid The concentration of sodium is 0.1 mol/L, the concentration of sodium sulfide is 1 mol/L, and the concentration of urea is 6 mol/L.

(3) adding the above-mentioned steamed defatted duck feathers to the above-mentioned extract solution for keratin extraction, wherein the temperature of the extract solution is 90-95° C., and the extraction time is 12 hours;

(4) After the keratin has been extracted, the extract is filtered, the filtrate is packed into a dialysis bag and sealed, and the dialysis bag is placed in deionized water for dialysis. 100 times, the dialysis time is 24 hours, and the deionized water is replaced every 8 hours, and the specification of the dialysis bag is 25000 molecular weight cut off. Dialysis of keratin can obtain keratin in a specific molecular weight range, which is beneficial to improve the mechanical strength of natural cellulose.

(5) After the dialysis is completed, the liquid in the dialysis bag is concentrated using a rotary evaporator. When the concentrated liquid is 10-15% of the original volume, the concentrated liquid is vacuum-dried and pulverized to obtain keratin.

As preferably, the preparation method of the brown algae extract is as follows:

(1) Weighing 100 parts by weight of brown algae, chopping the brown algae into brown algae granules, adding the brown algae granules to 2000 parts by weight of boiling water for cooking for 30 minutes;

(2) Filter out the cooked brown algae particles from water, add it to 50 parts by weight of a 5 wt% sodium pyrophosphate solution, and stir for 45 minutes to obtain a viscous liquid.

(3) The viscous liquid obtained above is neutralized to neutral with a sodium hydroxide solution having a concentration of 5 wt%, and finally the viscous liquid is vacuum-dried and pulverized to obtain a brown algae extract.

The brown algae extract prepared by the above method has a relatively high content of active ingredients, good hygroscopicity, and good dispersibility after compounding with polyethylene.

As preferably, the mussel shell powder and the halloysite nanotubes are all modified, and the specific method is as follows:

(1) Weigh 100 parts by weight of halloysite nanotubes or mussel shell powder, immerse it in 1000 parts by weight of hydrochloric acid solution with a concentration of 10 wt%, and take it out after acid treatment for 3 hours.

(2) Place the acid-treated halloysite nanotubes or mussel shell powder in a water bath for ultrasonic treatment. The temperature of the water bath is 40° C. for 30 minutes.

(3) Dry the halloysite nanotube or mussel shell powder after ultrasonic treatment under vacuum condition, the temperature is 50 ℃, and the time is 3 hours; then the halloysite nanotube or mussel shell powder are calcined, the calcining temperature 600-650°C for 5 hours.

(4) Disperse the calcined halloysite nanotubes or mussel shell powder and silane coupling agent successively in toluene for ultrasonic treatment for 30 minutes, wherein the halloysite nanotubes or mussel shell powder and silane coupling agent, toluene The mass dosage ratio is 50:(1-5):(450-550); then the toluene is stirred and heated to 70°C, and the halloysite nanotube or mussel shell powder is taken out after 6 hours, and finally washed to obtain a modified sexually processed halloysite nanotubes or mussel shell powder.

Halloysite nanotubes or mussel shell powder are modified by the above method to remove the internal crystal water and have better adsorption capacity. At the same time, after the modification of silane coupling agent, the hydrophobic performance is enhanced and it is easier to absorb electrolyte Organic solvents.

Preferably, the particle size of the mussel shell powder and halloysite nanotubes is 150-250 nanometers.

A kind of preparation method of above-mentioned lithium-ion battery is compounded with the polyethylene separator of cellulose, carries out as follows:

(1) Weigh the raw materials of the diaphragm base material respectively according to the proportioning ratio, add the keratin and ethylene glycol diglycidyl ether successively to the natural cellulose slurry, stir evenly and let stand for 1-2 hours, then Add the brown algae extract into the natural cellulose slurry and stir evenly to obtain a mixed slurry.

(2) Mix the mixed slurry prepared above with polyethylene and perform melt kneading to obtain a first kneaded product; dry and remove water from the first kneaded product, and then add Vinyl acrylate is then melt-kneaded to obtain a second kneaded product.

(3) Extruding, stretching for the first time, stretching for the second time, and heat setting are performed successively on the second kneaded product to obtain a diaphragm base material.

(4) Take each raw material of the coating slurry according to the proportioning ratio, add nano-inorganic fillers, binders, vinyl acrylate, mussel shell powder, and halloysite nanotubes into organic solvents and grind evenly to obtain Coating slurry.

(5) Heat the above-prepared coating slurry to 50-60°C, and then apply it on the surface of the above-prepared diaphragm base material, and after standing for 15-20 minutes, apply The ultraviolet light is irradiated for 4-6 minutes, and finally dried to prepare a polyethylene separator compounded with cellulose for lithium ion batteries.

Preferably, the stretching temperature for the first stretching of the second kneading material is 60-70°C, and the stretching ratio is 35-55%; the stretching temperature for the second stretching of the second kneading material is 90°C. -100°C, the elongation rate is 140-180%.

Preferably, the coating amount of the coating slurry on the diaphragm substrate is 2-4 grams per square meter.

Compared with the prior art, the beneficial effects of the present invention are: the diaphragm of the present invention has better high temperature resistance, dimensional stability, and anti-spike strength, and has better wettability to the electrolyte, and the coating and the diaphragm The adhesion of the substrate is better, and the coating is not easy to fall off.

Detailed ways

The present invention will be further described below in conjunction with embodiment. Raw materials used in the present invention, equipment, if not specified, are commonly used raw materials, equipment in this area; Method used in the present invention, if not specified, are conventional methods in this area.

Example 1

A polyethylene separator compounded with cellulose for a lithium ion battery comprises a separator substrate and a coating on the surface of the separator substrate. Wherein the thickness of the base material of the diaphragm is 18-22 microns, and the thickness of a single coating is 1-1.5 microns.

The separator substrate is prepared from the following materials: 70 parts by weight of polyethylene, 7.5 parts by weight of vinyl acrylate, 7.5 parts by weight of natural cellulose pulp, 4 parts by weight of keratin, 2 parts by weight of ethylene glycol Alcohol diglycidyl ether, the brown algae extract of 9 parts by weight.

The coating is formed by coating the coating slurry on the surface of the diaphragm substrate, and the coating slurry is prepared from the following materials: 1 part by weight of nano-alumina, 1 part by weight of nano-titanium oxide, 1 part by weight 4 parts by weight of polyvinylidene fluoride, 25 parts by weight of vinyl acrylate, 3 parts by weight of mussel shell powder, 3 parts by weight of halloysite nanotubes, and 62 parts by weight of carbon tetrachloride.

The preparation method of the polyethylene separator that is compounded with cellulose for lithium ion battery is carried out as follows:

(1) Weigh the raw materials of the diaphragm base material respectively according to the proportioning ratio, add the keratin and ethylene glycol diglycidyl ether successively to the natural cellulose slurry, stir and let stand for 1.5 hours, and then add the The brown algae extract is added to the natural cellulose slurry and stirred evenly to obtain a mixed slurry.

(2) Mix the mixed slurry prepared above with polyethylene and perform melt kneading to obtain a first kneaded product; dry and remove water from the first kneaded product, and then add Vinyl acrylate is then melt-kneaded to obtain a second kneaded product.

(3) Extruding, stretching for the first time, stretching for the second time, and heat setting are performed successively on the second kneaded product to obtain a diaphragm base material. The stretching temperature for the first stretching is 65° C., and the stretching ratio is 45%; the stretching temperature for the second stretching of the second kneaded product is 95° C., and the stretching ratio is 160%.

(4) Take each raw material of the coating slurry according to the proportioning ratio, add nano inorganic filler, polyvinylidene fluoride, vinyl acrylate, mussel shell powder, halloysite nanotubes into carbon tetrachloride and grind evenly , to prepare coating slurry.

(5) The coating slurry prepared above was heated to 55° C., and then coated on the surface of the separator substrate prepared above, and the coating amount of the coating slurry was 3 grams per square meter. Stand still for 18 minutes after coating, irradiate the coated surface of the separator base material with ultraviolet light for 5 minutes, and finally dry to obtain a polyethylene separator compounded with cellulose for lithium ion batteries.

The preparation method of above-mentioned natural cellulose slurry is as follows:

(1) take by weighing the short-staple cotton of 100 parts by weight and the bamboo residue of 100 parts by weight respectively, and add described short-staple cotton and bamboo residue into 600 parts by weight of concentration together in the sodium hydroxide solution of 15wt%, to containing The sodium hydroxide solution of short cotton linters and bamboo residues is vacuum-cooked, the cooking temperature is 220°C, and the cooking time is 4h.

(2) take out and wash the short cotton linters and bamboo dregs after cooking, add the short linters and bamboo dregs together to 2000 parts by weight of ethanol solution with a concentration of 40wt%, and then carry out microwave treatment to ethanol solution, wherein The microwave frequency is 2450MHZ, the microwave power is 800W, the temperature is 150°C, and the time is 45min; after the microwave treatment is completed, the ethanol solution is filtered, and the solid filtrate is taken.

(3) After the solid filtrate is washed, it is beaten with a beater, and after the beating, the resulting product is successively chlorinated, alkalized, bleached, impurity removed, and concentrated to obtain a natural cellulose fiber slurry with a solid content of 80wt%. .

The preparation method of above-mentioned keratin is as follows:

(1) Take 500 parts by weight of defatted duck feathers, add it into water and perform high-pressure cooking, wherein the temperature is 160°C, the pressure is 1.8-2.0Mpa, and the cooking time is 1h.

(2) Take 5000 parts by weight of water, add sodium dodecylbenzenesulfonate, sodium sulfide, and urea to the water successively to prepare an extract, in which dodecylbenzenesulfonic acid The concentration of sodium is 0.1 mol/L, the concentration of sodium sulfide is 1 mol/L, and the concentration of urea is 6 mol/L.

(3) adding the boiled defatted duck feathers to the above-mentioned extract solution to extract keratin, wherein the temperature of the extract solution is 93° C., and the extraction time is 12 hours.

(4) After the keratin has been extracted, the extract is filtered, the filtrate is packed into a dialysis bag and sealed, and the dialysis bag is placed in deionized water for dialysis. 100 times, the dialysis time is 24 hours, and the deionized water is replaced every 8 hours, and the specification of the dialysis bag is 25000 molecular weight cut off.

(5) After the dialysis is completed, the liquid in the dialysis bag is concentrated using a rotary evaporator. When the concentrated liquid is 13% of the original volume, the concentrated liquid is vacuum-dried and pulverized to obtain keratin.

The preparation method of the above-mentioned brown algae extract is as follows:

(1) Weigh 100 parts by weight of brown algae, chop the brown algae into brown algae granules, add the brown algae granules to 2000 parts by weight of boiling water and cook for 30 minutes.

(2) Filter out the cooked brown algae particles from water, add it to 50 parts by weight of a 5 wt% sodium pyrophosphate solution, and stir for 45 minutes to obtain a viscous liquid.

(3) The viscous liquid obtained above is neutralized to neutral with a sodium hydroxide solution having a concentration of 5 wt%, and finally the viscous liquid is vacuum-dried and pulverized to obtain a brown algae extract.

The above-mentioned mussel shell powder and halloysite nanotubes have been modified, and the specific methods are as follows:

(1) Weighing 100 parts by weight of halloysite nanotubes or mussel shell powder, the particle diameter of the mussel shell powder and halloysite nanotubes is 150-250 nanometers. The mussel shell powder and the halloysite nanotubes were soaked in 1000 parts by weight of a hydrochloric acid solution with a concentration of 10 wt% for 3 hours and then taken out.

(2) Place the acid-treated halloysite nanotubes or mussel shell powder in a water bath for ultrasonic treatment. The temperature of the water bath is 40° C. for 30 minutes.

(3) Dry the halloysite nanotube or mussel shell powder after ultrasonic treatment under vacuum condition, the temperature is 50 ℃, and the time is 3 hours; then the halloysite nanotube or mussel shell powder are calcined, the calcining temperature to 625°C for 5 hours.

(4) Disperse the calcined halloysite nanotubes or mussel shell powder and silane coupling agent successively in toluene for ultrasonic treatment for 30 minutes, wherein the halloysite nanotubes or mussel shell powder and silane coupling agent, toluene The mass dosage ratio is 50:3:500; then the toluene is stirred and heated to 70°C, after 6 hours, the halloysite nanotubes or mussel shell powder are taken out, and the modified halloysite nanotubes are obtained after final washing Or mussel shell powder.

Example 2

A polyethylene separator compounded with cellulose for a lithium ion battery comprises a separator substrate and a coating on the surface of the separator substrate. Wherein the thickness of the base material of the diaphragm is 10-14 microns, and the thickness of a single coating is 0.5-1 microns.

The separator substrate is prepared from the following materials: 60 parts by weight of polyethylene, 10 parts by weight of vinyl acrylate, 10 parts by weight of natural cellulose pulp, 4 parts by weight of keratin, 3 parts by weight of ethylene glycol Alcohol diglycidyl ether, the brown algae extract of 8 weight parts.

The coating is formed by coating the coating slurry on the surface of the diaphragm substrate, and the coating slurry is prepared from the following materials: 1 part by weight of nano-alumina, 3 parts by weight of polyvinylidene fluoride, 30 parts by weight Vinyl acrylate in parts by weight, mussel shell powder in 4 parts by weight, halloysite nanotubes in 5 parts by weight, and carbon tetrachloride in 57 parts by weight.

The preparation method of the polyethylene separator that is compounded with cellulose for lithium ion battery is carried out as follows:

(1) Weigh the raw materials of the diaphragm base material respectively according to the proportioning ratio, add the keratin and ethylene glycol diglycidyl ether successively to the natural cellulose slurry, stir and let stand for 1 hour, and then add the keratin and ethylene glycol diglycidyl ether to the natural cellulose slurry The brown algae extract is added to the natural cellulose slurry and stirred evenly to obtain a mixed slurry.

(2) Mix the mixed slurry prepared above with polyethylene and perform melt kneading to obtain a first kneaded product; dry and remove water from the first kneaded product, and then add Vinyl acrylate is then melt-kneaded to obtain a second kneaded product.

(3) Extruding, stretching for the first time, stretching for the second time, and heat setting are performed successively on the second kneaded product to obtain a diaphragm base material. The stretching temperature for the first stretching is 60° C., and the stretching ratio is 35%; the stretching temperature for the second stretching of the second kneaded product is 90° C., and the stretching ratio is 140%.

(4) Take each raw material of the coating slurry according to the proportioning ratio, add nano inorganic filler, polyvinylidene fluoride, vinyl acrylate, mussel shell powder, halloysite nanotubes into carbon tetrachloride and grind evenly , to prepare coating slurry.

(5) The coating slurry prepared above was heated to 50°C, and then coated on the surface of the separator substrate prepared above, and the coating amount of the coating slurry was 2 grams per square meter. Stand still for 15 minutes after coating, irradiate the coated surface of the separator base material with ultraviolet light for 4 minutes, and finally dry to obtain a polyethylene separator compounded with cellulose for lithium ion batteries.

The preparation method of above-mentioned natural cellulose slurry is as follows:

(1) take by weighing the short-staple cotton of 100 parts by weight and the bamboo residue of 100 parts by weight respectively, and add described short-staple cotton and bamboo residue into 600 parts by weight of concentration together in the sodium hydroxide solution of 15wt%, to containing The sodium hydroxide solution of short cotton linters and bamboo residues is vacuum-cooked, the cooking temperature is 220°C, and the cooking time is 4h.

(2) take out and wash the short cotton linters and bamboo dregs after cooking, add the short linters and bamboo dregs together to 2000 parts by weight of ethanol solution with a concentration of 40wt%, and then carry out microwave treatment to ethanol solution, wherein The microwave frequency is 2450MHZ, the microwave power is 800W, the temperature is 150°C, and the time is 45min; after the microwave treatment is completed, the ethanol solution is filtered, and the solid filtrate is taken.

(3) After the solid filtrate is washed, it is beaten with a beater, and after the beating, the resulting product is successively chlorinated, alkalized, bleached, impurity-removed, and concentrated to obtain a natural fiber with a solid content of 75-85wt%. slurry.

The preparation method of above-mentioned keratin is as follows:

(1) Take 500 parts by weight of defatted duck feathers, add it into water and perform high-pressure cooking, wherein the temperature is 160°C, the pressure is 1.8-2.0Mpa, and the cooking time is 1h.

(2) Take 5000 parts by weight of water, add sodium dodecylbenzenesulfonate, sodium sulfide, and urea to the water successively to prepare an extract, in which dodecylbenzenesulfonic acid The concentration of sodium is 0.1 mol/L, the concentration of sodium sulfide is 1 mol/L, and the concentration of urea is 6 mol/L.

(3) adding the boiled defatted duck feathers to the extract solution to extract keratin, wherein the temperature of the extract solution is 90° C., and the extraction time is 12 hours.

(4) After the keratin has been extracted, the extract is filtered, the filtrate is packed into a dialysis bag and sealed, and the dialysis bag is placed in deionized water for dialysis. 100 times, the dialysis time is 24 hours, and the deionized water is replaced every 8 hours, and the specification of the dialysis bag is 25000 molecular weight cut off.

(5) After the dialysis is completed, the liquid in the dialysis bag is concentrated using a rotary evaporator. When the concentrated liquid is 10% of the original volume, the concentrated liquid is vacuum-dried and pulverized to obtain keratin.

The preparation method of the above-mentioned brown algae extract is as follows:

(1) Weigh 100 parts by weight of brown algae, chop the brown algae into brown algae granules, add the brown algae granules to 2000 parts by weight of boiling water and cook for 30 minutes.

(2) Filter out the cooked brown algae particles from water, add it to 50 parts by weight of a 5 wt% sodium pyrophosphate solution, and stir for 45 minutes to obtain a viscous liquid.

(3) The viscous liquid obtained above is neutralized to neutral with a sodium hydroxide solution having a concentration of 5 wt%, and finally the viscous liquid is vacuum-dried and pulverized to obtain a brown algae extract.

The above-mentioned mussel shell powder and halloysite nanotubes have been modified, and the specific methods are as follows:

(1) Weighing 100 parts by weight of halloysite nanotubes or mussel shell powder, the particle diameter of the mussel shell powder and halloysite nanotubes is 150-250 nanometers. The mussel shell powder and the halloysite nanotubes were soaked in 1000 parts by weight of a hydrochloric acid solution with a concentration of 10 wt% for 3 hours and then taken out.

(2) Place the acid-treated halloysite nanotubes or mussel shell powder in a water bath for ultrasonic treatment. The temperature of the water bath is 40° C. for 30 minutes.

(3) Dry the halloysite nanotube or mussel shell powder after ultrasonic treatment under vacuum condition, the temperature is 50 ℃, and the time is 3 hours; then the halloysite nanotube or mussel shell powder are calcined, the calcining temperature 600°C for 5 hours.

(4) Disperse the calcined halloysite nanotubes or mussel shell powder and silane coupling agent successively in toluene for ultrasonic treatment for 30 minutes, wherein the halloysite nanotubes or mussel shell powder and silane coupling agent, toluene The mass dosage ratio is 50:1:450; then the toluene is stirred and heated to 70°C, after 6 hours, halloysite nanotubes or mussel shell powder are taken out, and finally modified halloysite nanotubes are obtained after washing Or mussel shell powder.

Example 3

A polyethylene separator compounded with cellulose for a lithium ion battery comprises a separator substrate and a coating on the surface of the separator substrate. Wherein the thickness of the base material of the diaphragm is 26-30 microns, and the thickness of a single coating is 1.5-2 microns.

The separator substrate is prepared from the following materials: 75 parts by weight of polyethylene, 5 parts by weight of vinyl acrylate, 6 parts by weight of natural cellulose pulp, 3 parts by weight of keratin, 1 part by weight of ethylene glycol Alcohol diglycidyl ether, the brown algae extract of 10 parts by weight.

The coating is formed by coating the coating slurry on the surface of the diaphragm substrate, and the coating slurry is prepared from the following materials: 2 parts by weight of nano-alumina, 3 parts by weight of nano-titanium oxide, 5 parts by weight parts of polyvinylidene fluoride, 20 parts by weight of vinyl acrylate, 1 part by weight of mussel shell powder, 2 parts by weight of halloysite nanotubes, and 67 parts by weight of carbon tetrachloride.

The preparation method of the polyethylene separator that is compounded with cellulose for lithium ion battery is carried out as follows:

(1) Weigh the raw materials of the diaphragm base material respectively according to the proportioning ratio, add the keratin and ethylene glycol diglycidyl ether successively to the natural cellulose slurry, stir and let stand for 2 hours, and then add the keratin and ethylene glycol diglycidyl ether to the natural cellulose slurry The brown algae extract is added to the natural cellulose slurry and stirred evenly to obtain a mixed slurry.

(2) Mix the mixed slurry prepared above with polyethylene and perform melt kneading to obtain a first kneaded product; dry and remove water from the first kneaded product, and then add Vinyl acrylate is then melt-kneaded to obtain a second kneaded product.

(3) Extruding, stretching for the first time, stretching for the second time, and heat setting are performed successively on the second kneaded product to obtain a diaphragm base material. Wherein the stretching temperature for the first stretching is 70° C., and the stretching rate is 55%; the stretching temperature for the second stretching of the second kneaded product is 100° C., and the stretching rate is 180%.

(4) Take each raw material of the coating slurry according to the proportioning ratio, add nano inorganic filler, polyvinylidene fluoride, vinyl acrylate, mussel shell powder, halloysite nanotubes into carbon tetrachloride and grind evenly , to prepare coating slurry.

(5) The coating slurry prepared above was heated to 60° C., and then coated on the surface of the separator substrate prepared above, and the coating amount of the coating slurry was 4 grams per square meter. Stand still for 20 minutes after coating, irradiate the coated surface of the separator base material with ultraviolet light for 6 minutes, and finally dry to obtain a polyethylene separator compounded with cellulose for lithium ion batteries.

The preparation method of above-mentioned natural cellulose slurry is as follows:

(1) take by weighing the short-staple cotton of 100 parts by weight and the bamboo residue of 100 parts by weight respectively, and add described short-staple cotton and bamboo residue into 600 parts by weight of concentration together in the sodium hydroxide solution of 15wt%, to containing The sodium hydroxide solution of short cotton linters and bamboo residues is vacuum-cooked, the cooking temperature is 220°C, and the cooking time is 4h.

(2) take out and wash the short cotton linters and bamboo dregs after cooking, add the short linters and bamboo dregs together to 2000 parts by weight of ethanol solution with a concentration of 40wt%, and then carry out microwave treatment to ethanol solution, wherein The microwave frequency is 2450MHZ, the microwave power is 800W, the temperature is 150°C, and the time is 45min; after the microwave treatment is completed, the ethanol solution is filtered, and the solid filtrate is taken.

(3) After the solid filtrate is washed, it is beaten with a beater, and after the beating, the resulting product is successively chlorinated, alkalized, bleached, impurity-removed, and concentrated to obtain a natural cellulose fiber slurry with a solid content of 85wt%. .

The preparation method of above-mentioned keratin is as follows:

(1) Take 500 parts by weight of defatted duck feathers, add it into water and perform high-pressure cooking, wherein the temperature is 160°C, the pressure is 1.8-2.0Mpa, and the cooking time is 1h.

(2) Take 5000 parts by weight of water, add sodium dodecylbenzenesulfonate, sodium sulfide, and urea to the water successively to prepare an extract, in which dodecylbenzenesulfonic acid The concentration of sodium is 0.1 mol/L, the concentration of sodium sulfide is 1 mol/L, and the concentration of urea is 6 mol/L.

(3) adding the boiled defatted duck feathers to the above-mentioned extract solution to extract keratin, wherein the temperature of the extract solution is 95° C., and the extraction time is 12 hours.

(4) After the keratin has been extracted, the extract is filtered, the filtrate is packed into a dialysis bag and sealed, and the dialysis bag is placed in deionized water for dialysis. 100 times, the dialysis time is 24 hours, and the deionized water is replaced every 8 hours, and the specification of the dialysis bag is 25000 molecular weight cut off.

(5) After the dialysis is completed, the liquid in the dialysis bag is concentrated using a rotary evaporator. When the concentrated liquid is 15% of the original volume, the concentrated liquid is vacuum-dried and pulverized to obtain keratin.

The preparation method of the above-mentioned brown algae extract is as follows:

(1) Weigh 100 parts by weight of brown algae, chop the brown algae into brown algae granules, add the brown algae granules to 2000 parts by weight of boiling water and cook for 30 minutes.

(2) Filter out the cooked brown algae particles from water, add it to 50 parts by weight of a 5 wt% sodium pyrophosphate solution, and stir for 45 minutes to obtain a viscous liquid.

(3) The viscous liquid obtained above is neutralized to neutral with a sodium hydroxide solution having a concentration of 5 wt%, and finally the viscous liquid is vacuum-dried and pulverized to obtain a brown algae extract.

The above-mentioned mussel shell powder and halloysite nanotubes have been modified, and the specific methods are as follows:

(1) Weighing 100 parts by weight of halloysite nanotubes or mussel shell powder, the particle diameter of the mussel shell powder and halloysite nanotubes is 150-250 nanometers. The mussel shell powder and the halloysite nanotubes were soaked in 1000 parts by weight of a hydrochloric acid solution with a concentration of 10 wt% for 3 hours and then taken out.

(2) Place the acid-treated halloysite nanotubes or mussel shell powder in a water bath for ultrasonic treatment. The temperature of the water bath is 40° C. for 30 minutes.

(3) Dry the halloysite nanotube or mussel shell powder after ultrasonic treatment under vacuum condition, the temperature is 50 ℃, and the time is 3 hours; then the halloysite nanotube or mussel shell powder are calcined, the calcining temperature 650°C for 5 hours.

(4) Disperse the calcined halloysite nanotubes or mussel shell powder and silane coupling agent successively in toluene for ultrasonic treatment for 30 minutes, wherein the halloysite nanotubes or mussel shell powder and silane coupling agent, toluene The mass dosage ratio is 50:5:550; then the toluene is stirred and heated to 70°C, after 6 hours, halloysite nanotubes or mussel shell powder are taken out, and finally modified halloysite nanotubes are obtained after washing Or mussel shell powder.

Various performance tests were carried out on the diaphragm prepared in the above examples, and the results were as follows:

group Porosity/% Electrolyte absorption rate/% Tensile strength/MPa Heat shrinkage/% Example 1 54 323 54 0 Example 2 49 275 49 3 Example 3 56 341 59 3

Among them, the test methods of porosity, electrolyte absorption rate, tensile strength and thermal shrinkage rate are all standard test methods commonly used in this industry.

The above are only preferred embodiments of the present invention, and do not limit the present invention in any way. All simple modifications, changes and equivalent transformations made to the above embodiments according to the technical essence of the present invention still belong to the technical solution of the present invention. scope of protection.

Claims (10)

1. a lithium ion battery is with being compounded with cellulosic polyethylene diagrams, comprise barrier film base material and the coating being located at described barrier film substrate surface, it is characterized in that: the material that described barrier film base material is 100 parts by following total weight parts is prepared from: the polyethylene of 65-75 weight portion, the vinyl acrylate of 5-10 weight portion, the native cellulose slurry of 5-10 weight portion, the keratin of 3-5 weight portion, the ethylene glycol diglycidylether of 1-3 weight portion, the brown alga extract of 8-10 weight portion; Described coating is coated barrier film substrate surface by coating paste and is formed, the material that described coating paste is 100 parts by following weight portion is prepared from: the nanometer inorganic filler of 1-5 weight portion, the binding agent of 3-5 weight portion, the vinyl acrylate of 20-30 weight portion, the mussel shell powder of 1-5 weight portion, the halloysite nanotubes of 1-5 weight portion, the organic solvent of 57-67 weight portion; Described nanometer inorganic filler be selected from nano aluminium oxide, nano-titanium oxide or nano zircite one or more.

2. lithium ion battery as claimed in claim 1 is with being compounded with cellulosic polyethylene diagrams, and it is characterized in that, the preparation method of described native cellulose slurry is as follows:

(1) cotton of short staple of 100 weight portions and the bamboo slag of 100 weight portions is taken respectively, and described cotton of short staple to be added together with bamboo slag to 600 weight portion concentration be in the sodium hydroxide solution of 15wt%, boiling is vacuumized to the sodium hydroxide solution containing short velveteen and bamboo slag, boiling temperature is 220 DEG C, and digestion time is 4h;

(2) the short velveteen after boiling and bamboo slag are taken out and washed, short velveteen being joined together with bamboo slag 2000 weight portion concentration is in the ethanolic solution of 40wt%, then Microwave Treatment is carried out to ethanolic solution, wherein microwave frequency is 2450MHZ, microwave power is 800W, temperature is 150 DEG C, and the time is 45min; After Microwave Treatment, ethanolic solution is filtered, get solid-state filtrate;

(3) adopt beater to pull an oar to it by after solid-state filtrate washing, after successively chlorination, alkalization, bleaching, removal of impurities, concentration being carried out to gains after making beating, obtain natural cellulose fiber slurry.

3. lithium ion battery as claimed in claim 2 is with being compounded with cellulosic polyethylene diagrams, and it is characterized in that, the solid content of described natural cellulose fiber slurry is 75-85wt%.

4. lithium ion battery as claimed in claim 1 is with being compounded with cellulosic polyethylene diagrams, and it is characterized in that, described keratic preparation method is as follows:

(1) get the degreasing drake feather of 500 weight portions, added in water to horizontal high voltage boiling of going forward side by side, wherein, temperature is 160 DEG C, and pressure is 1.8-2.0Mpa, and digestion time is 1h;

(2) water of 5000 weight portions is separately taken, Xiang Shuizhong successively adds neopelex, vulcanized sodium and urea, and be mixed with leaching liquor, in described leaching liquor, the concentration of neopelex is 0.1mol/L, the concentration of vulcanized sodium is the concentration 6mol/L of 1 mol/L, urea;

(3) added in above-mentioned leaching liquor by the degreasing drake feather after above-mentioned boiling and carry out keratin extraction, wherein the temperature of leaching liquor is 90-95 DEG C, and extraction time is 12 hours;

(4) after keratin extracts, leaching liquor is filtered, filtered fluid is loaded in bag filter and seals, described bag filter is positioned in deionized water and dialyses, wherein, the volumetric usage of deionized water is 100 times of filtered fluid, and dialysis time is 24 hours, and every 8 hours change a deionized water, the specification of bag filter is the molecular cut off of 25000;

(5), after dialysis, use Rotary Evaporators to carry out concentration to liquid in bag filter, after concentrate is the 10-15% of original volume, after vacuumize and pulverization process are carried out to concentrate, obtain keratin.

5. lithium ion battery as claimed in claim 1 is with being compounded with cellulosic polyethylene diagrams, and it is characterized in that, the preparation method of described brown alga extract is as follows:

(1) take the brown alga of 100 weight portions, described brown alga is minced into brown alga particle, described brown alga particle is added in the boiling water of 2000 weight portions and carries out boiling 30 minutes;

(2) the brown alga particle after boiling is leached from water, and to be added to 50 weight portion concentration be in the sodium pyrophosphate solution of 5wt%, stir and obtain thick liquid after 45 minutes;

(3) be that the thick liquid of above-mentioned gained is neutralized to neutrality by the sodium hydroxide solution of 5wt% by concentration, finally vacuumize carried out to thick liquid, pulverize after obtained brown alga extract.

6. lithium ion battery as claimed in claim 1 is with being compounded with cellulosic polyethylene diagrams, and it is characterized in that, described mussel shell powder and halloysite nanotubes are all through modification, and concrete grammar is as follows:

(1) take halloysite nanotubes or the mussel shell powder of 100 weight portions, being impregnated in 1000 weight portion concentration is that in the hydrochloric acid solution of 10wt%, acid treatment was taken out after 3 hours;

(2) be positioned in water-bath the halloysite nanotubes after acid treatment or mussel shell powder and carry out ultrasonic wave process, bath temperature is 40 DEG C, and the time is 30 minutes;

(3) halloysite nanotubes after ultrasonic wave process or mussel shell powder are carried out drying under vacuum, temperature is 50 DEG C, and the time is 3 hours; Then calcine halloysite nanotubes or mussel shell powder, calcining heat is 600-650 DEG C, and the time is 5 hours;

(4) halloysite nanotubes after calcining or mussel shell powder and silane coupler priority are distributed in toluene and carry out ultrasonic wave process 30 minutes, wherein the quality amount ratio of halloysite nanotubes or mussel shell powder and silane coupler, toluene is 50:(1-5): (450-550); Then toluene stirred and be heated to 70 DEG C, after 6 hours, taking out halloysite nanotubes or mussel shell powder, finally after washing, obtaining halloysite nanotubes or the mussel shell powder of modification.

7. lithium ion battery as claimed in claim 6 is with being compounded with cellulosic polyethylene diagrams, and it is characterized in that, the particle diameter of described mussel shell powder and halloysite nanotubes is 150-250 nanometer.

8. the preparation method being compounded with cellulosic polyethylene diagrams of the lithium ion battery as described in one of claim 1-7, is characterized in that carrying out as follows:

(1) each raw material of barrier film base material is taken respectively by proportioning, described keratin and ethylene glycol diglycidylether are successively added in native cellulose slurry, 1-2 hour is left standstill after stirring, and then described brown alga extract to be added in native cellulose slurry and to stir, obtain mixed slurry;

(2) above-mentioned obtained mixed slurry mixed with polyethylene and carry out melting mixing, obtaining the first mixing thing; Carry out drying to described first mixing thing to dewater, carry out melting mixing again after then adding vinyl acrylate in the first mixing thing, obtain the second mixing thing;

(3) obtained barrier film base material after extrusion molding, for the first time stretching, for the second time stretching, thermal finalization successively being carried out to described second mixing thing;

(4) each raw material of coating paste is taken respectively by proportioning, by nanometer inorganic filler, binding agent, vinyl acrylate, mussel shell powder, halloysite nanotubes to add in organic solvent and after grinding evenly, obtained coating paste;

(5) above-mentioned obtained coating paste is heated to 50-60 DEG C, then the surface of above-mentioned obtained barrier film base material is coated, leave standstill after 15-20 minute, carry out UV-irradiation 4-6 minute to the surface after the coating of barrier film base material, after finally drying, obtained lithium ion battery is with being compounded with cellulosic polyethylene diagrams.

9. the lithium ion battery preparation method being compounded with cellulosic polyethylene diagrams as claimed in claim 8, is characterized in that, the draft temperature that described second mixing thing first time stretches is 60-70 DEG C, and extensibility is 35-55%; The draft temperature that second mixing thing second time stretches is 90-100 DEG C, and extensibility is 140-180%.

10. the lithium ion battery preparation method being compounded with cellulosic polyethylene diagrams as claimed in claim 8, it is characterized in that, the coating weight of described coating paste on barrier film base material is 2-4 gram every square metre.