CN112909425A - High-efficiency long-life lithium-sulfur battery diaphragm and preparation method thereof - Google Patents
High-efficiency long-life lithium-sulfur battery diaphragm and preparation method thereof Download PDFInfo
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- JDZCKJOXGCMJGS-UHFFFAOYSA-N [Li].[S] Chemical compound [Li].[S] JDZCKJOXGCMJGS-UHFFFAOYSA-N 0.000 title claims abstract description 62
- 238000002360 preparation method Methods 0.000 title claims abstract description 17
- 239000002002 slurry Substances 0.000 claims abstract description 49
- 229920006231 aramid fiber Polymers 0.000 claims abstract description 21
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 18
- 238000000034 method Methods 0.000 claims abstract description 16
- 229910021389 graphene Inorganic materials 0.000 claims abstract description 14
- FXHOOIRPVKKKFG-UHFFFAOYSA-N N,N-Dimethylacetamide Chemical compound CN(C)C(C)=O FXHOOIRPVKKKFG-UHFFFAOYSA-N 0.000 claims description 60
- 238000003756 stirring Methods 0.000 claims description 42
- 238000000605 extraction Methods 0.000 claims description 41
- 238000000576 coating method Methods 0.000 claims description 35
- 239000002033 PVDF binder Substances 0.000 claims description 33
- 239000004760 aramid Substances 0.000 claims description 33
- 229920002981 polyvinylidene fluoride Polymers 0.000 claims description 33
- 239000011248 coating agent Substances 0.000 claims description 31
- 229920003235 aromatic polyamide Polymers 0.000 claims description 27
- 239000008367 deionised water Substances 0.000 claims description 25
- 229910021641 deionized water Inorganic materials 0.000 claims description 25
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 25
- KWGKDLIKAYFUFQ-UHFFFAOYSA-M lithium chloride Chemical compound [Li+].[Cl-] KWGKDLIKAYFUFQ-UHFFFAOYSA-M 0.000 claims description 24
- IEJIGPNLZYLLBP-UHFFFAOYSA-N dimethyl carbonate Chemical compound COC(=O)OC IEJIGPNLZYLLBP-UHFFFAOYSA-N 0.000 claims description 22
- 238000002156 mixing Methods 0.000 claims description 21
- 239000000843 powder Substances 0.000 claims description 16
- JRPBQTZRNDNNOP-UHFFFAOYSA-N barium titanate Chemical compound [Ba+2].[Ba+2].[O-][Ti]([O-])([O-])[O-] JRPBQTZRNDNNOP-UHFFFAOYSA-N 0.000 claims description 13
- 229910002113 barium titanate Inorganic materials 0.000 claims description 13
- LCZVSXRMYJUNFX-UHFFFAOYSA-N 2-[2-(2-hydroxypropoxy)propoxy]propan-1-ol Chemical compound CC(O)COC(C)COC(C)CO LCZVSXRMYJUNFX-UHFFFAOYSA-N 0.000 claims description 12
- 238000005345 coagulation Methods 0.000 claims description 12
- 230000015271 coagulation Effects 0.000 claims description 12
- 239000002202 Polyethylene glycol Substances 0.000 claims description 10
- 229920001223 polyethylene glycol Polymers 0.000 claims description 10
- 238000004519 manufacturing process Methods 0.000 claims description 9
- -1 polyethylene Polymers 0.000 claims description 9
- 238000007774 anilox coating Methods 0.000 claims description 8
- 239000004576 sand Substances 0.000 claims description 7
- 239000004698 Polyethylene Substances 0.000 claims description 6
- 239000007788 liquid Substances 0.000 claims description 6
- 229920000573 polyethylene Polymers 0.000 claims description 6
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 abstract description 7
- 229910052717 sulfur Inorganic materials 0.000 abstract description 6
- 239000011593 sulfur Substances 0.000 abstract description 6
- 229920001021 polysulfide Polymers 0.000 abstract description 5
- 239000005077 polysulfide Substances 0.000 abstract description 5
- 150000008117 polysulfides Polymers 0.000 abstract description 5
- 238000007599 discharging Methods 0.000 abstract description 4
- 150000001875 compounds Chemical class 0.000 abstract description 3
- 230000000052 comparative effect Effects 0.000 description 5
- 238000001035 drying Methods 0.000 description 5
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 4
- GLNWILHOFOBOFD-UHFFFAOYSA-N lithium sulfide Chemical compound [Li+].[Li+].[S-2] GLNWILHOFOBOFD-UHFFFAOYSA-N 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 238000004804 winding Methods 0.000 description 4
- 239000004114 Ammonium polyphosphate Substances 0.000 description 2
- 235000019826 ammonium polyphosphate Nutrition 0.000 description 2
- 229920001276 ammonium polyphosphate Polymers 0.000 description 2
- 230000002238 attenuated effect Effects 0.000 description 2
- 239000011230 binding agent Substances 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 238000000635 electron micrograph Methods 0.000 description 2
- 229910007552 Li2Sn Inorganic materials 0.000 description 1
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000003792 electrolyte Substances 0.000 description 1
- 229910052744 lithium Inorganic materials 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000002105 nanoparticle Substances 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 238000012827 research and development Methods 0.000 description 1
- 230000002441 reversible effect Effects 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
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- Manufacturing & Machinery (AREA)
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Cell Separators (AREA)
- Battery Electrode And Active Subsutance (AREA)
Abstract
The invention discloses a high-efficiency long-life lithium-sulfur battery diaphragm and a preparation method thereof, wherein the preparation method of the high-efficiency long-life lithium-sulfur battery diaphragm comprises the following steps: the lithium-sulfur battery diaphragm with high efficiency and long service life can improve the service life of the battery, and mainly utilizes meta-position aramid fiber as a net framework, and graphene is added into the aramid fiber slurry to enable the net structure to generate electric conduction to contain polysulfide compounds, and the aramid fiber has high mechanical strength to prevent sulfur from being damaged due to expansion and reduction of volume in the charging and discharging process.
Description
Technical Field
The invention belongs to the technical field of lithium-sulfur battery diaphragms, and particularly relates to a high-efficiency and long-service-life lithium-sulfur battery diaphragm and a preparation method thereof.
Background
The lithium-sulfur battery is always in a higher research and development direction due to the advantages of high specific capacity, low cost, low pollution and the like, the problem that the lithium-sulfur battery is exposed at present is that the service life is short, the capacity is attenuated particularly quickly in about 10-20 times of general cycle, and the main reason is that the final discharge product Li2Sn (n is 1-2) of the lithium-sulfur battery is electronically insulated and insoluble in electrolyte and is deposited on the surface of a conductive framework; part of the lithium sulfide is separated from the conductive framework and can not be converted into sulfur or high-order polysulfide through a reversible charging process reaction, so that the capacity is greatly attenuated.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide a preparation method of a lithium-sulfur battery diaphragm with high efficiency and long service life.
Another object of the present invention is to provide a high efficiency and long life lithium-sulfur battery separator obtained by the above preparation method, wherein the high efficiency and long life lithium-sulfur battery separator cuts the discharge product on the surface of the separator, so that the surface of the separator forms a conductive network structure capable of containing polysulfide compounds, and the elemental sulfur anode is tightly bonded to the network coating on the surface of the separator, thereby greatly reducing the separation of lithium sulfide from the conductive framework space, and fully converting the lithium sulfide into sulfur or polysulfide in high stage during charging and discharging, and prolonging the battery life while increasing the battery generation efficiency.
The purpose of the invention is realized by the following technical scheme.
A preparation method of a high-efficiency long-life lithium-sulfur battery diaphragm comprises the following steps:
coating the lithium-sulfur aramid pulp on a base film to form a lithium-sulfur aramid coating on the base film, carrying out first extraction, coating the oily PVDF pulp on the lithium-sulfur aramid coating, carrying out second extraction to obtain the high-efficiency and long-service-life lithium-sulfur battery diaphragm, wherein,
the method for preparing the lithium-sulfur aramid pulp comprises the following steps:
1) in a closed environment, uniformly mixing lithium chloride, first dimethylacetamide and meta-aramid fibers at 80-100 ℃ so as to dissolve the meta-aramid fibers in the first dimethylacetamide to obtain a first slurry, wherein the ratio of the lithium chloride to the first dimethylacetamide to the meta-aramid fibers is (2-4) in parts by mass: (78-82): (18-22);
in the step 1), the uniform mixing is realized by stirring for 4-6 h.
2) Adding second dimethylacetamide into the first slurry, stirring for 20-30 min, adding first dimethyl carbonate, stirring for 20-30 min, adding second slurry, and stirring for 20-30 min, wherein the ratio of the first slurry to the second dimethylacetamide to the first dimethyl carbonate to the second slurry is (22-25): (30-35): (5-10): (30-43), the method of preparing the second slurry includes: uniformly mixing gaseous barium titanate, graphene and tripropylene glycol, sanding for 10-15 min by using a sand mill, wherein the ratio of the gaseous barium titanate to the graphene to the tripropylene glycol is (5-10) in parts by mass: (10-15): (75-85).
In the above technical scheme, the method for preparing the oily PVDF slurry comprises the following steps: stirring PVDF powder and third dimethylacetamide for 40-50 min to dissolve the PVDF powder in the third dimethylacetamide, adding second dimethyl carbonate, stirring for 20-30 min, adding polyethylene glycol, and stirring for 30-40 min to obtain the oily PVDF slurry, wherein the ratio of the PVDF powder, the third dimethylacetamide, the second dimethyl carbonate and the polyethylene glycol is (2-5) in parts by weight: (55-60): (5-12): (25-30).
In the technical scheme, the extraction tank adopted for the first extraction is 10 small tanks, the extraction liquid obtained by mixing deionized water and fourth dimethylacetamide according to different mass ratios is arranged in the first 3 small tanks to form a coagulation bath, and the deionized water is arranged in the rest small tanks, wherein the mass ratios of the deionized water and the fourth dimethylacetamide in the coagulation bath in the first 3 small tanks are 3:2, 1:1 and 2:3 in sequence.
In the above technical scheme, the second extraction is performed by using deionized water.
In the above technical scheme, the base film is a polyethylene base film.
In the above technical solution, the coating uses an anilox roller.
The lithium-sulfur battery diaphragm with high efficiency and long service life is obtained by the preparation method.
The lithium-sulfur battery diaphragm with high efficiency and long service life can improve the service life of the battery, and the lithium-sulfur battery diaphragm mainly utilizes meta-aramid as a net-shaped framework, and graphene is added into aramid slurry, so that a net-shaped structure generates electric conduction to contain polysulfide compounds, and the aramid has high mechanical strength to prevent sulfur from being damaged due to expansion and reduction of volume in the charging and discharging processes. And gas-phase barium titanate nano particles are added into the coating, and sulfur is cut off by utilizing gaps among fine powder particles, so that the normal operation of the lithium-sulfur battery is ensured. In order to reduce the space that lithium sulfide is separated from a conductive framework, the outermost layer of the diaphragm is bonded with the anode by using an oily PVDF net, so that the distance between the anode and the diaphragm is shortened, and the conversion during charging and discharging is more sufficient.
Drawings
FIG. 1 is an electron micrograph of a high efficiency long life separator for a lithium sulfur battery obtained in example 1;
FIG. 2 is an electron micrograph of the separator obtained in comparative example 1.
Detailed Description
The technical scheme of the invention is further explained by combining specific examples.
The base film specification is 1000mm multiplied by 12 mu m; the specification of the anilox roll was 1150mm × 100mm × 4 μm.
The first dimethylacetamide to the fourth dimethylacetamide are dimethylacetamide.
Example 1
A preparation method of a high-efficiency long-life lithium-sulfur battery diaphragm comprises the following steps:
coating lithium sulfur aramid pulp on the base film, forming lithium sulfur aramid coating on the base film, the base film is the polyethylene base film, carries out extraction for the first time, coats oily PVDF pulp on lithium sulfur aramid coating again, carries out extraction for the second time, obtains high efficiency high life lithium sulfur battery diaphragm, wherein, the reticulation roller is adopted in the coating, and the parameter setting of coating process is: the unwinding tension is 32N, the winding tension is 4N, the speed ratio of an anilox roller is 140%, the tension of a drying tunnel is 18N, and the extraction tension is 10N;
the method for preparing the lithium-sulfur aramid pulp comprises the following steps:
1) in a closed environment, mixing and stirring lithium chloride, first dimethylacetamide and meta-aramid fiber for 4 hours at 80 ℃ until the mixture is uniform, so that the meta-aramid fiber is dissolved in the first dimethylacetamide to obtain a first slurry, wherein the ratio of the lithium chloride to the first dimethylacetamide to the meta-aramid fiber is 2: 80: 18;
2) adding second dimethylacetamide into the first slurry, stirring for 20min, adding first dimethyl carbonate, stirring for 20min, adding second slurry, and stirring for 20min, wherein the ratio of the first slurry to the second dimethylacetamide to the first dimethyl carbonate to the second slurry is 22: 30: 5: 43, a method of making a second slurry comprising: uniformly mixing gaseous barium titanate, graphene and tripropylene glycol, sanding for 10min by using a sand mill, wherein the ratio of the gaseous barium titanate to the graphene to the tripropylene glycol is 5: 10: 85.
a process for preparing an oily PVDF slurry comprising the steps of: stirring the PVDF powder and third dimethylacetamide for 40min to dissolve the PVDF powder in the third dimethylacetamide, adding second dimethyl carbonate, stirring for 20min, adding polyethylene glycol, and stirring for 30min to obtain oily PVDF slurry, wherein the weight ratio of the PVDF powder to the third dimethylacetamide to the second dimethyl carbonate to the polyethylene glycol is 2: 60: 12: 26.
the extraction tank adopted in the first extraction is 10 small tanks, the depth of each small tank is 1m, the extraction liquid obtained by mixing deionized water and fourth dimethylacetamide according to different mass ratios is arranged in the first 3 small tanks to form a coagulation bath, and the deionized water is arranged in the remaining 7 small tanks, wherein the mass ratio of the deionized water to the fourth dimethylacetamide in the coagulation bath in the first 3 small tanks is 3:2 (1 st small tank), 1:1 (2 nd small tank) and 2:3 (3 rd small tank) in sequence, and a diaphragm sequentially passes through the 10 small tanks during extraction.
The second extraction is carried out by using deionized water.
Example 2
A preparation method of a high-efficiency long-life lithium-sulfur battery diaphragm comprises the following steps:
coating lithium sulfur aramid pulp on the base film, forming lithium sulfur aramid coating on the base film, the base film is the polyethylene base film, carries out extraction for the first time, coats oily PVDF pulp on lithium sulfur aramid coating again, carries out extraction for the second time, obtains high efficiency high life lithium sulfur battery diaphragm, wherein, the reticulation roller is adopted in the coating, and the parameter setting of coating process is: the unwinding tension is 32N, the winding tension is 4N, the speed ratio of an anilox roller is 140%, the tension of a drying tunnel is 18N, and the extraction tension is 10N;
the method for preparing the lithium-sulfur aramid pulp comprises the following steps:
1) in a closed environment, mixing and stirring lithium chloride, first dimethylacetamide and meta-aramid fiber for 5 hours at 90 ℃ until the mixture is uniform, so that the meta-aramid fiber is dissolved in the first dimethylacetamide to obtain a first slurry, wherein the ratio of the lithium chloride to the first dimethylacetamide to the meta-aramid fiber is 3: 79: 18;
2) adding second dimethylacetamide into the first slurry, stirring for 25min, adding first dimethyl carbonate, stirring for 25min, adding second slurry, and stirring for 25min, wherein the ratio of the first slurry to the second dimethylacetamide to the first dimethyl carbonate to the second slurry is 23: 31: 8: 38, a method of making a second slurry comprising: uniformly mixing gaseous barium titanate, graphene and tripropylene glycol, sanding for 13min by using a sand mill, wherein the ratio of the gaseous barium titanate to the graphene to the tripropylene glycol is 8: 12: 80.
a process for preparing an oily PVDF slurry comprising the steps of: stirring the PVDF powder and third dimethylacetamide for 45min to dissolve the PVDF powder in the third dimethylacetamide, adding second dimethyl carbonate, stirring for 25min, adding polyethylene glycol, and stirring for 35min to obtain oily PVDF slurry, wherein the weight ratio of the PVDF powder to the third dimethylacetamide to the second dimethyl carbonate to the polyethylene glycol is 3: 59: 8: 30.
the extraction tank adopted in the first extraction is 10 small tanks, the depth of each small tank is 1m, the extraction liquid obtained by mixing deionized water and fourth dimethylacetamide according to different mass ratios is arranged in the first 3 small tanks to form a coagulation bath, and the deionized water is arranged in the remaining 7 small tanks, wherein the mass ratio of the deionized water to the fourth dimethylacetamide in the coagulation bath in the first 3 small tanks is 3:2 (1 st small tank), 1:1 (2 nd small tank) and 2:3 (3 rd small tank) in sequence, and a diaphragm sequentially passes through the 10 small tanks during extraction.
The second extraction is carried out by using deionized water.
Example 3
A preparation method of a high-efficiency long-life lithium-sulfur battery diaphragm comprises the following steps:
coating lithium sulfur aramid pulp on the base film, forming lithium sulfur aramid coating on the base film, the base film is the polyethylene base film, carries out extraction for the first time, coats oily PVDF pulp on lithium sulfur aramid coating again, carries out extraction for the second time, obtains high efficiency high life lithium sulfur battery diaphragm, wherein, the reticulation roller is adopted in the coating, and the parameter setting of coating process is: the unwinding tension is 32N, the winding tension is 4N, the speed ratio of an anilox roller is 140%, the tension of a drying tunnel is 18N, and the extraction tension is 10N;
the method for preparing the lithium-sulfur aramid pulp comprises the following steps:
1) in a closed environment, mixing and stirring lithium chloride, first dimethylacetamide and meta-aramid fiber for 6 hours at 100 ℃ until the mixture is uniform, so that the meta-aramid fiber is dissolved in the first dimethylacetamide to obtain a first slurry, wherein the ratio of the lithium chloride to the first dimethylacetamide to the meta-aramid fiber is 4: 78: 18;
2) adding second dimethylacetamide into the first slurry, stirring for 30min, adding first dimethyl carbonate, stirring for 30min, adding second slurry, and stirring for 30min, wherein the ratio of the first slurry to the second dimethylacetamide to the first dimethyl carbonate to the second slurry is 25: 35: 10: 30, a method of making a second slurry comprising: uniformly mixing gaseous barium titanate, graphene and tripropylene glycol, sanding for 15min by using a sand mill, wherein the ratio of the gaseous barium titanate to the graphene to the tripropylene glycol is 10: 15: 75.
a process for preparing an oily PVDF slurry comprising the steps of: stirring PVDF powder and third dimethylacetamide for 50min to dissolve the PVDF powder in the third dimethylacetamide, adding second dimethyl carbonate, stirring for 30min, adding polyethylene glycol, and stirring for 40min to obtain oily PVDF slurry, wherein the weight ratio of the PVDF powder to the third dimethylacetamide to the second dimethyl carbonate to the polyethylene glycol is 5: 60: 5: 30.
the extraction tank adopted in the first extraction is 10 small tanks, the depth of each small tank is 1m, the extraction liquid obtained by mixing deionized water and fourth dimethylacetamide according to different mass ratios is arranged in the first 3 small tanks to form a coagulation bath, and the deionized water is arranged in the remaining 7 small tanks, wherein the mass ratio of the deionized water to the fourth dimethylacetamide in the coagulation bath in the first 3 small tanks is 3:2 (1 st small tank), 1:1 (2 nd small tank) and 2:3 (3 rd small tank) in sequence, and a diaphragm sequentially passes through the 10 small tanks during extraction.
The second extraction is carried out by using deionized water.
Comparative example 1
A preparation method of a lithium-sulfur separator comprises the following steps:
mixing deionized water and ethanol according to the mass ratio of 1:1, stirring for 10min, adding ammonium polyphosphate, stirring for 30min, adding activated carbon, stirring for 30min, sanding for 15min by using a sand mill, finally adding acrylic ester serving as a binder, coating the base film by using a reticulate roller, drying and rolling to obtain the lithium-sulfur diaphragm, wherein the ratio of the deionized water to the ethanol to the ammonium polyphosphate to the activated carbon to the acrylic ester is 10: 10: 3: 3: 1.
comparative example 2
A method of making a separator comprising the steps of:
coating lithium sulfur aramid pulp on the base film, forming a lithium sulfur aramid coating on the base film, extracting the base film which is a polyethylene base film to obtain a diaphragm, wherein the coating adopts an anilox roller, and the parameters of the coating process are set as: the unwinding tension is 32N, the winding tension is 4N, the speed ratio of an anilox roller is 140%, the tension of a drying tunnel is 18N, and the extraction tension is 10N;
the method for preparing the lithium-sulfur aramid pulp comprises the following steps:
1) in a closed environment, mixing and stirring lithium chloride, first dimethylacetamide and meta-aramid fiber for 4 hours at 80 ℃ until the mixture is uniform, so that the meta-aramid fiber is dissolved in the first dimethylacetamide to obtain a first slurry, wherein the ratio of the lithium chloride to the first dimethylacetamide to the meta-aramid fiber is 2: 80: 18;
2) adding second dimethylacetamide into the first slurry, stirring for 20min, adding first dimethyl carbonate, stirring for 20min, adding second slurry, and stirring for 20min, wherein the ratio of the first slurry to the second dimethylacetamide to the first dimethyl carbonate to the second slurry is 22: 30: 5: 43, a method of making a second slurry comprising: uniformly mixing gaseous barium titanate, graphene and tripropylene glycol, sanding for 10min by using a sand mill, wherein the ratio of the gaseous barium titanate to the graphene to the tripropylene glycol is 5: 10: 85.
the extraction method comprises the following steps that 10 small grooves are adopted for extraction, the depth of each small groove is 1m, extraction liquid obtained by mixing deionized water and fourth dimethylacetamide according to different mass ratios is arranged in the first 3 small grooves to form a coagulation bath, deionized water is arranged in the remaining 7 small grooves, the mass ratio of the deionized water to the fourth dimethylacetamide in the coagulation bath in the first 3 small grooves is 3:2 (1 st small groove), 1:1 (2 nd small groove) and 2:3 (3 rd small groove), and a diaphragm sequentially passes through the 10 small grooves during extraction.
The high-efficiency and long-life lithium-sulfur battery separators obtained in examples 1 to 3, the lithium-sulfur separator obtained in comparative example 1, and the separator obtained in comparative example 2 were tested, and the test results are shown in table 1.
TABLE 1
As can be seen from Table 1, the cycle life of the high-efficiency and long-life lithium-sulfur battery diaphragm in the lithium-sulfur battery is improved to more than 600 times, and the service life of the battery is greatly prolonged. And the lithium-sulfur battery diaphragm also has strong advantages in safety performance and has stronger high-temperature resistance than the common lithium-sulfur battery diaphragm. Because the outermost layer of the battery diaphragm adopts the oily PVDF coating, the battery pole piece can be tightly stuck, and the whole battery is more stable and safer. .
The three-dimensional oily reticular structure fully covers the surface of the lithium-sulfur aramid coating, the reticular structure is obvious, the oily reticular structure is more close to a pole piece, and the distance between a diaphragm and the pole piece is reduced;
fig. 2 is a schematic diagram showing that the coating is disordered due to the non-supported network structure, which is not beneficial to the cycle performance of the lithium-sulfur battery, and the acrylic ester binder has the phenomenon of pore blocking, and the shuttling between lithium and sulfur affects the battery performance.
The invention has been described in an illustrative manner, and it is to be understood that any simple variations, modifications or other equivalent changes which can be made by one skilled in the art without departing from the spirit of the invention fall within the scope of the invention.
Claims (8)
1. A preparation method of a high-efficiency long-life lithium-sulfur battery diaphragm is characterized by comprising the following steps:
coating the lithium-sulfur aramid pulp on a base film to form a lithium-sulfur aramid coating on the base film, carrying out first extraction, coating the oily PVDF pulp on the lithium-sulfur aramid coating, carrying out second extraction to obtain the high-efficiency and long-service-life lithium-sulfur battery diaphragm, wherein,
the method for preparing the lithium-sulfur aramid pulp comprises the following steps:
1) in a closed environment, uniformly mixing lithium chloride, first dimethylacetamide and meta-aramid fibers at 80-100 ℃ so as to dissolve the meta-aramid fibers in the first dimethylacetamide to obtain a first slurry, wherein the ratio of the lithium chloride to the first dimethylacetamide to the meta-aramid fibers is (2-4) in parts by mass: (78-82): (18-22);
2) adding second dimethylacetamide into the first slurry, stirring for 20-30 min, adding first dimethyl carbonate, stirring for 20-30 min, adding second slurry, and stirring for 20-30 min, wherein the ratio of the first slurry to the second dimethylacetamide to the first dimethyl carbonate to the second slurry is (22-25): (30-35): (5-10): (30-43), the method of preparing the second slurry includes: uniformly mixing gaseous barium titanate, graphene and tripropylene glycol, sanding for 10-15 min by using a sand mill, wherein the ratio of the gaseous barium titanate to the graphene to the tripropylene glycol is (5-10) in parts by mass: (10-15): (75-85).
2. The preparation method according to claim 1, wherein in the step 1), the mixing is performed for 4-6 hours by stirring.
3. The method for preparing the PVDF slurry according to claim 1, wherein the method for preparing the oily PVDF slurry comprises the steps of: stirring PVDF powder and third dimethylacetamide for 40-50 min to dissolve the PVDF powder in the third dimethylacetamide, adding second dimethyl carbonate, stirring for 20-30 min, adding polyethylene glycol, and stirring for 30-40 min to obtain the oily PVDF slurry, wherein the ratio of the PVDF powder, the third dimethylacetamide, the second dimethyl carbonate and the polyethylene glycol is (2-5) in parts by weight: (55-60): (5-12): (25-30).
4. The preparation method of claim 1, wherein the extraction tank adopted in the first extraction is 10 small tanks, the first 3 small tanks are filled with extraction liquid obtained by mixing deionized water and fourth dimethylacetamide according to different mass ratios and form coagulation baths, and the rest small tanks are filled with deionized water, wherein the mass ratios of the deionized water to the fourth dimethylacetamide in the coagulation baths in the first 3 small tanks are 3:2, 1:1 and 2:3 in sequence.
5. The method of claim 1, wherein the second extraction is performed with deionized water.
6. The production method according to claim 1, wherein the base film is a polyethylene base film.
7. The method of claim 1, wherein the coating is performed using an anilox roll.
8. The high-efficiency long-life lithium-sulfur battery separator obtained by the preparation method according to any one of claims 1 to 7.
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