CN115986316A - Battery diaphragm, preparation method thereof and secondary battery - Google Patents
Battery diaphragm, preparation method thereof and secondary battery Download PDFInfo
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- CN115986316A CN115986316A CN202211624858.6A CN202211624858A CN115986316A CN 115986316 A CN115986316 A CN 115986316A CN 202211624858 A CN202211624858 A CN 202211624858A CN 115986316 A CN115986316 A CN 115986316A
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Abstract
The invention belongs to the technical field of secondary batteries, and particularly relates to a battery diaphragm which comprises a glass cloth base film and a ceramic coating arranged on at least one surface of the glass cloth base film. The battery diaphragm uses the glass cloth as the base film, the glass cloth is composed of the glass fiber, has high heat-resistant temperature, can bear the high temperature of 600-800 ℃, greatly improves the heat-resistant capability of the base film, and has excellent size stability, thereby improving the safety of the diaphragm and the battery core.
Description
Technical Field
The invention belongs to the technical field of secondary batteries, and particularly relates to a battery diaphragm, a preparation method of the battery diaphragm and a secondary battery.
Background
The polyolefin diaphragm is one of the most widely used lithium battery diaphragms at present, but the polyolefin diaphragm in the market has the problems of poor electrophilic electrolyte performance, poor heat resistance and the like. In order to improve the above-mentioned poor performance of the polyolefin separator, a conventional solution is to coat a ceramic composite coating layer on one or both sides of the polyolefin separator. However, when the battery is at a higher temperature, the heat resistance of the coating layer is insufficient, thereby causing a safety accident. Because the surface energy of the base film PE/PP is high and the chemical property is stable, the surface physical and chemical modification is difficult. Therefore, how to find a substrate capable of replacing the polyolefin separator is the current research focus.
Disclosure of Invention
One of the objects of the present invention is: aiming at the defects of the prior art, the battery diaphragm is provided and has excellent heat resistance and chemical stability.
In order to achieve the purpose, the invention adopts the following technical scheme:
a battery diaphragm comprises a glass cloth base film and a ceramic coating arranged on at least one surface of the glass cloth base film.
Wherein the porosity of the glass cloth base film is 60-90%.
Wherein the glass cloth base film comprises glass fibers, and the diameter of the glass fibers is 1-50 mu m.
The ceramic coating comprises the following raw materials in parts by weight: 90 to 95 parts of ceramic material, 0.5 to 2 parts of thickening agent, 0.5 to 2 parts of dispersing agent, 5 to 10 parts of curing resin and 0.5 to 2 parts of photoinitiator.
Wherein the photoinitiator is one or more of aryl ketone derivatives, benzophenone derivatives, thioxanthone derivatives, alkyl aryl ketone derivatives and benzil derivatives.
The curing resin is one or more of epoxy acrylate, polyurethane acrylate, polyester acrylate, polyether acrylate, amino acrylate and acrylate.
Wherein, the glass cloth basement membrane includes at least one of silica, aluminium oxide, calcium oxide, boron oxide, magnesium oxide, sodium oxide.
The second purpose of the invention is: aiming at the defects of the prior art, the preparation method of the battery diaphragm is provided, and has simple steps and high controllability.
In order to achieve the purpose, the invention adopts the following technical scheme:
a preparation method of a battery separator comprises the following steps:
s1, adding the photoinitiator in parts by weight into a solvent, and stirring and dissolving to obtain a first solution;
s2, mixing the ceramic particles, the thickening agent, the dispersing agent, the curing resin and the first solution in parts by weight to obtain coating slurry;
and S3, coating the coating slurry on at least one surface of the glass cloth base film, and performing illumination curing to obtain the battery diaphragm.
Wherein the solid content of the coating slurry in the step S2 is 20-40%.
Wherein the solid content of the first solution in the step S1 is 0.5-3%.
The third purpose of the invention is that: in order to overcome the defects of the prior art, the secondary battery has good chemical stability and cycle performance.
In order to achieve the purpose, the invention adopts the following technical scheme:
a secondary battery comprises the battery diaphragm.
Compared with the prior art, the invention has the beneficial effects that: the battery diaphragm of the invention uses the glass cloth as the base film, the glass cloth is composed of glass fiber, has high heat-resisting temperature, can bear the high temperature of 600-800 ℃, greatly improves the heat-resisting capability of the base film, and has excellent size stability, thereby improving the safety of the diaphragm and the battery core.
The preparation method of the battery diaphragm is simple to operate, good in controllability and capable of realizing batch production, the prepared battery diaphragm has high heat-resistant temperature and excellent size stability, and ceramic particles are added, so that the battery diaphragm has good electrolyte wettability and provides more channels for lithium ion transmission.
Drawings
FIG. 1 is a comparative chart of wettability tests of example 1 of the present invention and comparative example 1.
Fig. 2 is a comparison of electrochemical stability tests of example 1 of the present invention and comparative example 1.
Detailed Description
The present invention will be described in further detail with reference to the following detailed description and the accompanying drawings, but the present invention is not limited thereto.
The invention relates to a battery diaphragm, which comprises a glass cloth base film and a ceramic coating arranged on at least one surface of the glass cloth base film.
The traditional diaphragm adopts polyolefin as a base film, and the polyolefin has poor electrolyte affinity, low heat-resistant temperature, easy occurrence of melting shrinkage and poor safety. The invention uses the glass cloth as the base film, the melting point of the glass cloth is 600-800 ℃, the glass cloth has excellent heat resistance, thereby greatly improving the heat-resistant temperature of the diaphragm, the surface of the glass cloth is coated with coating slurry with ceramic particles and cured resin, the cured resin can improve the heat resistance and the adhesion of the diaphragm, the cured resin can fill the gaps among the glass fibers of the glass cloth, prevent the sliding among the fibers, and increase the strength of the diaphragm. The ceramic particles can improve the electrolyte wettability of the diaphragm, and provide more channels for lithium ion transmission, so that the prepared battery diaphragm has good electrochemical performance. The glass cloth is prepared by melting, drawing and drying glass raw materials, the main components of the glass raw materials are silicon dioxide, aluminum oxide, calcium oxide, boron oxide, magnesium oxide, sodium oxide and the like, wherein the diameter of a single glass fiber is 1-50 mu m, the whole glass cloth is formed by interweaving the single glass fibers, the total thickness of the whole glass cloth is 5-100 mu m, and the glass cloth has excellent heat resistance. Preferably, the thickness of the battery separator is 5 μm, 10 μm, 15 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm. Wherein, the ceramic coating can be arranged on the surface of one side of the glass cloth base film and also can be arranged on the surfaces of two sides of the glass cloth base film. The light curing time is 0.5-4 h.
In some embodiments, the glass cloth-based film has a porosity of 60% to 90%. The glass cloth-based membrane has a large porosity and can provide a large electrolyte throughput. Preferably, the porosity of the glass cloth base film is 60% to 70%, 70% to 80%, 80% to 90%, specifically, the porosity of the glass cloth base film is 60%, 70%, 80%, 90%.
In some embodiments, the glass cloth-based film comprises glass fibers having a diameter of 1 to 50 μm. The glass cloth is formed by interweaving single glass fibers, the total thickness of the glass cloth is 5-100 mu m, and the glass cloth has excellent heat resistance.
In some embodiments, the ceramic coating comprises the following raw materials in parts by weight: 90 to 95 parts of ceramic material, 0.5 to 2 parts of thickening agent, 0.5 to 2 parts of dispersing agent, 5 to 10 parts of curing resin and 0.5 to 2 parts of photoinitiator. Preferably, the ceramic material is 90 parts, 91 parts, 92 parts, 93 parts, 94 parts, 95 parts by weight, the thickener is 0.5 part, 0.8 part, 1 part, 1.2 parts, 1.5 parts, 2 parts by weight, the dispersant is 0.5 part, 0.8 part, 1 part, 1.2 parts, 1.5 parts, 2 parts by weight, the curing resin is 5 parts, 7 parts, 9 parts, 10 parts by weight, and the photoinitiator is 0.5 part, 0.8 part, 1 part, 1.2 parts, 1.5 parts, 2 parts by weight.
In some embodiments, the photoinitiator is one or more of an aryl ketone derivative, a benzophenone derivative, a thioxanthone derivative, an alkyl aryl ketone derivative, a benzil derivative. The photoinitiator is capable of being cured by illumination at a specific wavelength, preferably ultraviolet light. Specifically, one of a high-pressure mercury lamp and a UVLED lamp having a wavelength of 365nm, 395 nm. Preferably, the photoinitiator is 2-hydroxy-2, 2-dimethylacetophenone.
In some embodiments, the curable resin is one or more of an epoxy acrylate, a urethane acrylate, a polyester acrylate, a polyether acrylate, an amino acrylate, an acrylate. The curing resin can bond and cure the ceramic material and the glass fiber to form a cured coating.
In some embodiments, the glass cloth-based film comprises at least one of silica, alumina, calcia, boria, magnesia, sodia. The glass cloth base film is formed by interweaving a plurality of glass fibers, the total thickness of the glass cloth base film is 5-100 mu m, and during preparation, the raw materials are subjected to melt drawing and drying to obtain the glass fibers, and the diameter of each glass fiber is 1-50 mu m. The diameter of the glass fiber is set to be 1-50 mu m, so that the obtained glass cloth base film has good heat resistance, certain porosity and certain mechanical strength.
The preparation method of the battery diaphragm is simple in steps and high in controllability.
A preparation method of a battery separator comprises the following steps:
s1, adding the photoinitiator in parts by weight into a solvent, and stirring and dissolving to obtain a first solution;
s2, mixing the ceramic particles, the thickening agent, the dispersing agent, the curing resin and the first solution in parts by weight to obtain coating slurry;
and S3, coating the coating slurry on at least one surface of the glass cloth base film, and performing illumination curing to obtain the battery diaphragm.
The glass cloth is used as the base diaphragm to replace the traditional polyolefin base film, so that the heat resistance and the heat stability of the diaphragm are greatly improved; the invention uses the curing resin and the photoinitiator for matching use, can be cured at the interweaving position of the glass fibers, prevents the glass fibers from sliding, enhances the tensile property and the strength of the glass fibers, simultaneously increases the cohesiveness of the ceramic particles and the glass cloth basement membrane, and the ceramic particles can improve the mechanical property and the wettability of the basement membrane and provide more transmission channels for lithium ions. Wherein the thickener is carboxymethyl cellulose CMC, and the dispersant is polyacrylamide or fatty alcohol ether sodium sulfate. The ceramic particles have a particle size D90 of less than 2 microns. The coating mode is one or more of micro-gravure coating, rotary spraying, air gun spraying, spot coating, extrusion coating and blade coating.
In some embodiments, the solid content of the coating slurry in step S2 is 20% to 40%. Preferably, the coating slurry has a solids content of 20%, 30%, 40%.
In some embodiments, the first solution in step S1 has a solids content of 0.5 to 3%. Preferably, the solids content of the first solution is 0.5%, 1%, 1.5%, 2%, 2.5%, 3%.
A secondary battery having good chemical stability and cycle performance.
A secondary battery comprises the battery diaphragm. The secondary battery may be a lithium ion battery, a sodium ion battery, a magnesium ion battery, a calcium ion battery, a potassium ion battery, or the like. Preferably, the following secondary battery is exemplified by a lithium ion battery, and the lithium ion battery includes a positive plate, a negative plate, a diaphragm, an electrolyte and a casing, wherein the positive plate and the negative plate are separated by the diaphragm, and the casing is used for installing the positive plate, the negative plate, the diaphragm and the electrolyte. The diaphragm is the battery diaphragm.
Positive electrode
The positive plate comprises a positive current collector and a positive active material layer arranged on at least one surface of the positive current collector, the positive active material layer comprises a positive active material, and the positive active material can be a chemical formula including but not limited to Li a Ni x Co y M z O 2-b N b (wherein 0.95. Ltoreq. A. Ltoreq.1.2. X>0,y is more than or equal to 0, z is more than or equal to 0, and x + y + z =1,0 is more than or equal to b is less than or equal to 1, M is selected from one or more of Mn and Al, N is selected from one or more of F, P and S), the positive active material can also be selected from one or more of LiCoO 2 、LiNiO 2 、LiVO 2 、LiCrO 2 、LiMn 2 O 4 、LiCoMnO 4 、Li 2 NiMn 3 O 8 、LiNi 0.5 Mn 1.5 O 4 、LiCoPO 4 、LiMnPO 4 、LiFePO 4 、LiNiPO 4 、LiCoFSO 4 、CuS 2 、FeS 2 、MoS 2 、NiS、TiS 2 And the like. The positive electrode active material may be further modified, and the method for modifying the positive electrode active material is known to those skilled in the art, and for example, the positive electrode active material may be modified by coating, doping, or the likeThe materials used for processing may be combinations including, but not limited to, one or more of Al, B, P, zr, si, ti, ge, sn, mg, ce, W, and the like. And the positive electrode current collector is generally a structure or a part for collecting current, and the positive electrode current collector may be any material suitable for being used as a positive electrode current collector of a lithium ion battery in the field, for example, the positive electrode current collector may include, but is not limited to, a metal foil and the like, and more specifically, may include, but is not limited to, an aluminum foil and the like.
Negative electrode
The negative plate comprises a negative current collector and a negative active material layer arranged on the surface of the negative current collector, wherein the negative active material layer comprises a negative active material, and the negative active material can be one or more of graphite, soft carbon, hard carbon, carbon fiber, mesocarbon microbeads, silicon-based materials, tin-based materials, lithium titanate or other metals capable of forming an alloy with lithium. Wherein, the graphite can be selected from one or more of artificial graphite, natural graphite and modified graphite; the silicon-based material can be one or more selected from simple substance silicon, silicon-oxygen compound, silicon-carbon compound and silicon alloy; the tin-based material can be one or more selected from simple substance tin, tin oxide compound and tin alloy. The negative electrode current collector is generally a structure or a part for collecting current, and the negative electrode current collector may be any material suitable for use as a negative electrode current collector of a lithium ion battery in the art, for example, the negative electrode current collector may include, but is not limited to, a metal foil, and the like, and more specifically, may include, but is not limited to, a copper foil, and the like.
Electrolyte solution
The lithium ion battery also comprises electrolyte, and the electrolyte comprises an organic solvent, electrolyte lithium salt and an additive. Wherein the electrolyte lithium salt may be LiPF used in a high-temperature electrolyte 6 And/or LiBOB; or LiBF used in low-temperature electrolyte 4 、LiBOB、LiPF 6 At least one of; or LiBF used in anti-overcharge electrolyte 4 、LiBOB、LiPF 6 At least one of, liTFSI; may also be LiClO 4 、LiAsF 6 、LiCF 3 SO 3 、LiN(CF 3 SO 2 ) 2 At least one of (1). And the organic solvent may be a cyclic carbonate including PC, EC; or chain carbonates including DFC, DMC, or EMC; and also carboxylic acid esters including MF, MA, EA, MP, etc. And additives include, but are not limited to, film forming additives, conductive additives, flame retardant additives, overcharge prevention additives, controlling H in electrolytes 2 At least one of additives of O and HF content, additives for improving low temperature performance, and multifunctional additives.
The shell is made of one of stainless steel and aluminum plastic films.
Example 1
Preparing a battery diaphragm:
a preparation method of a battery separator comprises the following steps:
step S1, adding 10g of 2-hydroxy-2, 2-dimethyl acetophenone powder into 100ml of water, stirring in dark until the powder is completely dissolved, and preparing a solution with the solid content of 1%, namely a first solution;
step S2, mixing alumina, a CMC thickener, a polyacrylamide dispersant, epoxy resin and a first solution according to the following ratio of (1);
and S3, coating the coating slurry on the surface of the glass fiber by blade coating, drying for 2 hours at 90 ℃ by using an oven, and irradiating by using a UVLED365nm light source to cure the coating so as to obtain the battery diaphragm with the thickness of 15 microns, wherein the porosity of the glass cloth base film is 75%, and the diameter of the glass fiber is 45 microns.
Preparing a positive plate:
lithium cobaltate, conductive agent superconducting carbon (Super-P) and binder polyvinylidene fluoride (PVDF) are mixed according to the mass ratio of 97:1.5:1.5, uniformly mixing to prepare lithium ion battery anode slurry with certain viscosity, coating the slurry on a current collector aluminum foil, drying at 85 ℃, and then carrying out cold pressing; then trimming, cutting into pieces, slitting, drying for 4 hours at 110 ℃ under the vacuum condition after slitting, and welding the tabs to prepare the positive plate.
Preparing a negative plate:
graphite, conductive agent superconducting carbon (Super-P), thickening agent carboxymethyl cellulose sodium (CMC) and binder Styrene Butadiene Rubber (SBR) are mixed according to a mass ratio of 96:2.0:1.0:1.0, preparing slurry, coating the slurry on a current collector copper foil, drying at 85 ℃, cutting edges, cutting pieces, dividing strips, drying for 4 hours at 110 ℃ under a vacuum condition after dividing the strips, and welding tabs to prepare a negative plate.
Preparing an electrolyte:
lithium hexafluorophosphate (LiPF) 6 ) Dissolved in a mixed solvent composed of Ethylene Carbonate (EC), dimethyl carbonate (DMC) and Ethyl Methyl Carbonate (EMC) (the mass ratio of the three is 1:2: 1) To obtain the electrolyte with the concentration of 1 mol/L.
Preparing a lithium ion battery:
winding the positive plate, the prepared battery diaphragm and the negative plate into a battery cell, wherein the battery diaphragm is positioned between the positive plate and the negative plate, the positive electrode is led out by spot welding of an aluminum tab, and the negative electrode is led out by spot welding of a nickel tab; and then placing the battery core in an aluminum-plastic packaging bag, injecting the electrolyte, and carrying out processes such as packaging, formation, capacity and the like to prepare the lithium ion battery.
Example 2
The difference from example 1 is that: in the step S2, the weight part ratio of the ceramic particles, the thickening agent, the dispersing agent, the curing resin and the first solution is (80).
The rest is the same as embodiment 1, and the description is omitted here.
Example 3
The difference from example 1 is that: in the step S2, the weight part ratio of the ceramic particles, the thickening agent, the dispersing agent, the curing resin and the first solution is 85.
The rest is the same as embodiment 1, and the description is omitted here.
Example 4
The difference from example 1 is that: in the step S2, the weight part ratio of the ceramic particles, the thickening agent, the dispersing agent, the curing resin and the first solution is 90.
The rest is the same as embodiment 1, and the description is omitted here.
Example 5
The difference from example 1 is that: in the step S2, the weight part ratio of the ceramic particles, the thickening agent, the dispersing agent, the curing resin and the first solution is 100.
The rest is the same as embodiment 1, and the description is omitted here.
Example 6
The difference from example 1 is that: the solid content of the coating slurry in step S2 was 20%.
The rest is the same as embodiment 1, and the description is omitted here.
Example 7
The difference from example 1 is that: the solid content of the coating slurry in step S2 was 25%.
The rest is the same as embodiment 1, and the description is omitted here.
Example 8
The difference from example 1 is that: the solid content of the coating slurry in step S2 was 28%.
The rest is the same as embodiment 1, and the description is omitted here.
Example 9
The difference from example 1 is that: the solid content of the coating slurry in step S2 was 35%.
The rest is the same as embodiment 1, and the description is omitted here.
Example 10
The difference from example 1 is that: the solid content of the coating slurry in step S2 was 40%.
The rest is the same as embodiment 1, and the description is omitted here.
Example 11
The difference from example 1 is that: the porosity of the glass cloth-based film is 60%, and the diameter of the glass fiber is 50 μm.
The rest is the same as embodiment 1, and the description is omitted here.
Example 12
The difference from example 1 is that: the porosity of the glass cloth-based film is 70%, and the diameter of the glass fiber is 46 μm.
The rest is the same as embodiment 1, and the description is omitted here.
Example 13
The difference from example 1 is that: the porosity of the glass cloth-based film is 80%, and the diameter of the glass fiber is 42 μm.
The rest is the same as embodiment 1, and the description is omitted here.
Example 14
The difference from example 1 is that: the porosity of the glass cloth-based film is 85%, and the diameter of the glass fiber is 35 μm.
The rest is the same as embodiment 1, and the description is omitted here.
Example 15
The difference from example 1 is that: the porosity of the glass cloth basement membrane is 90%, and the diameter of the glass fiber is 20 microns.
The rest is the same as embodiment 1, and the description is omitted here.
Comparative example 1
The film was a PE separator having a thickness of 15 μm.
The separators prepared in examples 1 to 10 and comparative example 1 were subjected to an electrolyte wettability test, an electric heat shrinkage test and a closed-cell rupture temperature test, and the test results are shown in table 1.
1) And (3) electrolyte infiltration test: the specific test method comprises the following steps: and (3) dropping a certain amount of electrolyte on the surface of the diaphragm by using a contact angle tester, testing the contact angle of the electrolyte when the electrolyte just contacts the diaphragm surface, and testing the size of the contact angle again after 30 min. As shown in fig. 1, the contact angle of the PE separator at the beginning and after 30min is significantly larger than that of the example, which indicates that the addition of the ceramic particles can significantly improve the absorption of the separator to the electrolyte, and more electrolyte can provide more channels for the transmission of lithium ions.
2) Electrochemical stability: the specific test method comprises the following steps: the diaphragm is assembled into a button cell, an electrochemical workstation is adopted to carry out LSV (linear sweep voltammetry) test, the voltage range is 0-6V, the sweep rate is 1mV/S, the current polarization peaks of the two are basically consistent by comparing the embodiment with the comparative example, as shown in figure 2, and the addition of the UV curing component can not influence the electrochemical stability of the diaphragm.
3) Thermal shrinkage test: the specific test method comprises the following steps: the membrane was cut into 5 x 15cm films, placed in an oven at 130 ℃ for 0.5h, and then the dimensions a x b cm after the change in the test were taken out, so the MD shrinkage was calculated as b/15 x 100% and the TD shrinkage was calculated as a/5 x 100%. Table 1 is a receipt for heat shrinkage of example 1 and comparative example 1, wherein the average MD shrinkage of the examples was about 0.16% and TD shrinkage was about 0.13%, which are much less than MD =20.5% and TD =19.3% of the comparative examples, indicating better heat resistance on glass fiber substrate.
4) And (3) closing and breaking temperatures, namely, assembling the battery diaphragms of the batteries of the examples 1-10 and the comparative example 1 into the steel sheet battery, wherein the temperature range is 20-200 ℃, the heating rate is 5 ℃/min, and the battery internal resistance instrument is adopted to continuously monitor the temperature. The data are shown below, in which example 1 has no closed cell temperature, while comparative example 1 has closed cells at around 130 c, and rupture of the membrane occurs at around 150 c, which is attributed to the fact that the glass fiber-based separator does not melt and decompose at high temperature, and can stably maintain dimensional stability. While PE membranes cannot maintain dimensional stability at higher temperatures due to material properties. In conclusion, the novel diaphragm has higher safety performance.
5) Capacity retention ratio: charging the lithium ion secondary battery to 4.25V at a constant current of 1C at 25 ℃, then charging to 0.05C at a constant voltage of 4.25V, standing for 5min, and then discharging to 2.8V at a constant current of 1C, wherein the process is a charge-discharge cycle process, and the discharge capacity at this time is the discharge capacity of the first cycle. The lithium ion secondary battery was subjected to 600 cycles of charge and discharge tests in accordance with the above-described method, and the discharge capacity per cycle was recorded. Cycle capacity retention (%) = discharge capacity at 600 th cycle/discharge capacity at first cycle × 100%.
TABLE 1
As can be seen from table 1, the prepared battery diaphragm of the present invention has a small wetting angle to the electrolyte, has good wettability to the electrolyte, can be absorbed in a relatively fast time, and has good wettability, as shown in fig. 1, after 30min, the battery diaphragm of the present invention can completely absorb the electrolyte, and has good wettability. The battery diaphragm has good dimensional stability, the rate is kept below 0.4% after the battery diaphragm is taken out to test change after being baked for 0.5h in an oven at the temperature of 130 ℃, and the dimensional stability is good. The battery diaphragm also has good heat resistance, the battery diaphragm is assembled into a steel sheet battery, the steel sheet battery is heated at the temperature of 20-200 ℃ at the heating rate of 5 ℃/min, and the battery internal resistance meter is adopted to continuously monitor the steel sheet battery, so that the battery diaphragm does not melt or disperse, and the dimensional stability can be stably kept. Moreover, as shown by comparison of examples 1-10 of the present invention and comparative example 1, the separator of the present invention has no closed pores and no rupture in the oven test at 130 ℃, because the separator of the present invention has very good heat resistance and high heat resistance temperature, and the closed pore temperature and the rupture temperature are far higher than the test temperature, the rupture temperature does not occur even if the separator is not shrunk and ruptured at 130 ℃.
From comparison of examples 1 to 5, when the weight ratio of the ceramic particles, the thickener, the dispersant, the curing resin and the first solution in the step S2 is set to 90.
From comparison of examples 1, 6 to 10, when the solid content of the coating paste in step S2 was set to 30%, the prepared battery separator had better performance.
From comparison of examples 1 and 11-15, when the porosity of the glass cloth base separator is set to be 75%, and the diameter of the glass fiber is 45 μm, the prepared battery separator has better performance and better strength, and the corresponding secondary battery has better capacity retention rate. The reason is that when the glass fibers with certain lengths and diameters are arranged to be interwoven with each other, the larger diameter is beneficial to forming larger porosity, meanwhile, the longer diameter can also increase the interweaving degree among the glass fibers, so that the firmness is improved, but the mechanical property is easily deteriorated due to the overlong diameter, so that the glass fiber diameter and the porosity are arranged within a certain range, so that the prepared diaphragm has good mechanical property and can also provide good electrolyte permeability.
Variations and modifications to the above-described embodiments may also occur to those skilled in the art, which fall within the scope of the invention as disclosed and taught herein. Therefore, the present invention is not limited to the above-mentioned embodiments, and any obvious improvement, replacement or modification made by those skilled in the art based on the present invention is within the protection scope of the present invention. Furthermore, although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.
Claims (11)
1. A battery diaphragm is characterized by comprising a glass cloth base film and a ceramic coating arranged on at least one surface of the glass cloth base film.
2. The battery separator according to claim 1, wherein the glass cloth-based film has a porosity of 60% to 90%.
3. The battery separator according to claim 1 or 2, wherein the glass cloth-based film comprises glass fibers having a diameter of 1 to 50 μm.
4. The battery separator of claim 1, wherein the ceramic coating comprises the following raw materials in parts by weight: 90 to 95 parts of ceramic material, 0.5 to 2 parts of thickening agent, 0.5 to 2 parts of dispersing agent, 5 to 10 parts of curing resin and 0.5 to 2 parts of photoinitiator.
5. The battery separator according to claim 1, wherein the photoinitiator is one or more of an aryl ketone derivative, a benzophenone derivative, a thioxanthone derivative, an alkyl aryl ketone derivative, and a benzil derivative.
6. The battery separator of claim 1, wherein the cured resin is one or more of an epoxy acrylate, a urethane acrylate, a polyester acrylate, a polyether acrylate, an amino acrylate, and an acrylate.
7. The battery separator of claim 1, wherein the glass cloth-based film comprises at least one of silica, alumina, calcia, boria, magnesia, sodium oxide.
8. A method of preparing a battery separator as claimed in any one of claims 1 to 5, comprising the steps of:
s1, adding the photoinitiator in parts by weight into a solvent, and stirring and dissolving to obtain a first solution;
s2, mixing the ceramic particles, the thickening agent, the dispersing agent, the curing resin and the first solution in parts by weight to obtain coating slurry;
and S3, coating the coating slurry on at least one surface of the glass cloth base film, and performing illumination curing to obtain the battery diaphragm.
9. The method for preparing a battery separator according to claim 8, wherein the solid content of the coating slurry in the step S2 is 20-40%.
10. The method for preparing a battery separator according to claim 8, wherein the solid content of the first solution in step S1 is 0.5 to 3%.
11. A secondary battery comprising the battery separator according to claims 1 to 7.
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| CN202211624858.6A CN115986316A (en) | 2022-12-16 | 2022-12-16 | Battery diaphragm, preparation method thereof and secondary battery |
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| CN202211624858.6A CN115986316A (en) | 2022-12-16 | 2022-12-16 | Battery diaphragm, preparation method thereof and secondary battery |
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