CN113394516A - Lithium ion battery diaphragm, preparation method thereof and lithium ion battery - Google Patents
Lithium ion battery diaphragm, preparation method thereof and lithium ion battery Download PDFInfo
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- CN113394516A CN113394516A CN202110572379.3A CN202110572379A CN113394516A CN 113394516 A CN113394516 A CN 113394516A CN 202110572379 A CN202110572379 A CN 202110572379A CN 113394516 A CN113394516 A CN 113394516A
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- lithium ion
- ion battery
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- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/409—Separators, membranes or diaphragms characterised by the material
- H01M50/449—Separators, membranes or diaphragms characterised by the material having a layered structure
- H01M50/451—Separators, membranes or diaphragms characterised by the material having a layered structure comprising layers of only organic material and layers containing inorganic material
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- 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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- 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
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
Abstract
The invention belongs to the technical field of lithium ion batteries, and particularly relates to a lithium ion battery diaphragm and a preparation method thereof, wherein the lithium ion battery diaphragm comprises a base film layer and a ceramic composite layer, the ceramic composite layer is arranged on the surface of the base film layer, the porosity of the ceramic composite layer is 50% -80%, and the pore size is 0.1-0.5 um. According to the lithium ion battery diaphragm, the ceramic composite layer is coated on the base film layer, and has a large porosity and a large pore diameter, so that the overall mechanical strength of the diaphragm is improved, the liquid absorption rate is also improved, the lithium ion transmission rate is improved, and the conditions of insufficient electrolyte infiltration, interface black spots, lithium precipitation and low cycle retention rate after high-power high-rate output or multiple charge and discharge cycles are improved.
Description
Technical Field
The invention belongs to the technical field of lithium ion batteries, and particularly relates to a lithium ion battery diaphragm, a preparation method of the lithium ion battery diaphragm and a lithium ion battery.
Background
The lithium ion battery has the characteristics of high working voltage, large energy density, long cycle life, no memory effect and no pollution, has the advantages of safety, reliability, quick charge and discharge and the like, is a main power supply of various electronic products, is a green and environment-friendly secondary battery without pollution, meets the development requirements of energy and environment protection in various countries at present, and is rapidly increased in the use amount of various industries.
The four key materials of the lithium ion battery are a positive electrode material, a negative electrode material, electrolyte and a diaphragm. The diaphragm has the main functions of isolating the positive electrode and the negative electrode and preventing electrons from passing through, and can allow ions to pass through, so that the lithium ions are rapidly transmitted between the positive electrode and the negative electrode in the charging and discharging process. The size and uniformity of pores of the isolating membrane can influence the migration speed of lithium ions, so that the dynamic performance of the battery cell, such as circulation, rate performance, low-temperature lithium precipitation window and the like, is influenced.
The conventional isolating membrane coating is a single-layer or multi-layer ceramic, polymer or ceramic-polymer mixed material, a lithium ion channel is formed by stacked pores among dried particles, and because the material has smaller particle size and higher stacking density, the space for the pores of the coating to rise is very small, the capacity of the coating for absorbing electrolyte continuously rises to become a bottleneck, and the coating has some defects on the project with high dynamic performance: such as: the more the cycle times and the larger the multiplying power, the more easily the electrolyte soakage is insufficient, the interface black spot is generated, the lithium precipitation window is narrow, the cycle capacity retention rate is low, and the like.
Disclosure of Invention
The invention aims to: aiming at the defects of the prior art, the lithium ion battery diaphragm is provided with the ceramic composite layer with larger porosity and larger aperture, so that the overall mechanical strength of the diaphragm is improved, the liquid absorption rate is also improved, the lithium ion transmission rate is improved, and the conditions of insufficient electrolyte infiltration, interface black spots, lithium precipitation and low cycle retention rate after high-power high-rate output or multiple charge and discharge cycles are improved.
In order to achieve the purpose, the invention adopts the following technical scheme:
a lithium ion battery separator, characterized in that: the ceramic composite membrane comprises a base membrane layer and a ceramic composite layer, wherein the ceramic composite layer is arranged on the surface of the base membrane layer, the porosity of the ceramic composite layer is 50% -80%, and the pore size is 0.1-0.5 um.
As an improvement of the lithium ion battery diaphragm, the base film layer is made of PE, PP or a PE/PP/PE composite isolating film, the melting point of the base film layer is 130-160 ℃, the thickness of the base film layer is 3-20 mu m, the porosity of the base film layer is 20-50%, and the air permeability of the base film layer is 30-400sec/100 cc. The base film layer has certain porosity, can form certain lithium ion channels, has certain air permeability, and when the porosity is smaller, the overall porosity becomes smaller after the base film layer is compounded with the ceramic composite layer, which is not beneficial to lithium ion transmission.
As an improvement of the lithium ion battery separator of the present invention, the lithium ion battery separator further includes an adhesive layer for adhesion, and the adhesive layer is disposed on one surface of the base film layer away from the ceramic composite layer and on one surface of the ceramic composite layer away from the base film layer. The adhesive layer is used for adhering to the positive electrode or the negative electrode to form a diaphragm with a compact structure, and the positive electrode and the negative electrode can be separated at the same time. The adhesive layer comprises a first adhesive layer and a second adhesive layer, the first adhesive layer and the second adhesive layer are only used for distinguishing the positions of the first adhesive layer and the second adhesive layer, and the preparation raw materials, the preparation method and the size and the thickness of the first adhesive layer and the second adhesive layer are the same as below.
As an improvement of the lithium ion battery diaphragm, the thickness of the bonding layer is 0.2-10 um, and the coating gram weight is 0.05-5.0 g/m2The thermal shrinkage is less than or equal to 10 percent, and the peel strength is more than or equal to 20N/m. The adhesive layer has thermal stability, small thermal shrinkage, high peeling strength and low tendency to curl at high temperature.
The second purpose of the invention is: the preparation method of the lithium ion battery diaphragm is characterized in that a dispersing agent and a foaming agent are added into ceramic composite slurry, the dispersing agent can reduce the surface tension in the slurry, the slurry is mechanically stirred and mixed with air, double electronic layers are arranged on the surface of a base film layer to surround the air during coating, a large number of bubbles are generated, pores are formed after drying, and meanwhile, the foaming agent volatilizes to form pores during drying, so that the overall porosity and pore diameter are increased, the liquid absorption rate is increased, and the transmission rate of lithium ions is increased.
In order to achieve the purpose, the invention adopts the following technical scheme:
a preparation method of a lithium ion battery separator comprises the following steps:
step (A): ceramic particles, a thickening agent, a dispersing agent, a binder and a foaming agent are mixed according to the weight part ratio of 50-99: 0.1-1: 0.01-1: 2-6: 0.1-5, mixing and stirring to form ceramic composite slurry with solid content of 20-40%;
step (B): and coating the ceramic composite slurry on the surface of the base film layer, controlling the temperature, and drying to ensure that the foaming agent catalyzes and forms a ceramic composite layer to prepare the lithium ion battery diaphragm.
The porosity of conventional separator coatings is formed by the formation of pores between the packing of ceramic particles, with a porosity size of about 30-50%. According to the technical scheme, a certain amount of foaming agent is doped in the ceramic, the porosity of 30-50% is formed between the ceramic and the foaming agent stacked particles before drying, the pores of the particles are reserved after the foaming agent is volatilized after drying, and the pores among the particles are enlarged to be larger than 70%, so that the larger the pores are, the smaller the resistance of lithium ions transmitted among the diaphragms is, and the faster the transmission rate is.
As an improvement of the preparation method of the lithium ion battery diaphragm, the ceramic particles are SiO2、Al2O3、CaO、TiO2、MgO、ZnO、SnO2、ZrO2、AlOOH、Mg(OH)2、BaSO4One or a mixture of two or more of them. The ceramic particles not only have thermal stability and protect the base film layer from thermal contraction at high temperature, but also have certain mechanical strength and provide certain mechanical strength for the base film layer. Preferably, SiO is used2、Al2O3、CaO、TiO2、MgO。
As an improvement of the preparation method of the lithium ion battery diaphragm, the foaming agent is one or a mixture of more than two of n-pentane, n-hexane, n-heptane, petroleum ether, trichlorofluoromethane, dichlorofluoromethane and dichlorotetrafluoroethane. The foaming agent has a low boiling point and can be boiled and evaporated at a certain low temperature to form gas, so that the porosity and the pore diameter of the ceramic composite layer are increased. Preferably, n-pentane or n-hexane is used.
As an improvement of the preparation method of the lithium ion battery diaphragm, the dispersing agent is one or a mixture of more than two of dodecyl sulfuric acid, fatty alcohol-polyoxyethylene ether sulfuric acid, rosin soap, animal and vegetable protein dispersing agents and the like. The dispersing agent can reduce the surface tension of liquid, is uniformly dispersed by using ceramic particles, a thickening agent, a foaming agent and the like, and can improve the liquid absorption rate of the ceramic composite layer to electrolyte, thereby improving the wettability.
Preferably, the binder is one or a mixture of more than two of polyacrylate, polyacrylonitrile, polyvinyl alcohol, organic silicon, epoxy resin and polyurethane.
Preferably, the coating mode is one or more of micro gravure coating, rotary spraying, air gun spraying, spot coating and extrusion coating.
As an improvement of the preparation method of the lithium ion battery separator of the present invention, the preparation method of the lithium ion battery separator comprises the following steps:
step (A): ceramic particles, a thickening agent, a dispersing agent, a binder and a foaming agent are mixed according to the weight part ratio of 50-99: 0.1-1: 0.01-1: 2-6: 0.1-5, mixing and stirring to form ceramic composite slurry with solid content of 20-40%;
step (B): coating ceramic composite slurry on one surface of the base film layer, controlling the temperature, and drying to volatilize the foaming agent to form a ceramic composite layer;
step (C): the adhesive particles, the thickening agent, the dispersing agent and the binder are mixed according to the weight ratio of 80-95: 0.1-1.5: 0.01-1: 0.1-5, mixing and stirring to form bonding slurry with solid content of 2-6%;
step (D): and coating bonding slurry on one surface of the base film layer, which is far away from the ceramic composite layer, to form a bonding layer, and coating bonding slurry on one surface of the ceramic composite layer, which is far away from the base film layer, to form a bonding layer, so as to prepare the lithium ion battery diaphragm.
According to the preparation method of the lithium ion battery diaphragm, ceramic particles, a dispersing agent and a foaming agent are added into the ceramic composite slurry, so that the ceramic particles have good thermal stability and mechanical strength, the thermal shrinkage of a base film layer is avoided, and a certain mechanical strength is provided; the dispersing agent can reduce the surface tension in the slurry, is mechanically stirred and mixed with air, is arranged on the surface of the base film layer to form an electric double layer to surround the air during coating, generates a large amount of bubbles, and forms pores after drying, and meanwhile, the dispersing agent can improve the liquid absorption rate and storage efficiency of the electrolyte, so that the lithium ion transmission speed is improved; and preparing bonding slurry with a certain solid content, and coating the bonding slurry on two sides of the outermost surface of the whole body to form a bonding layer, so as to prepare the lithium ion battery diaphragm.
As an improvement of the preparation method of the lithium ion battery diaphragm, the dispersing agent is one or a mixture of more than two of dodecyl sulfuric acid, fatty alcohol-polyoxyethylene ether sulfuric acid, rosin soap, animal and vegetable protein dispersing agents and the like. The dispersing agent can reduce the surface tension of liquid, is uniformly dispersed by using ceramic particles, a thickening agent, a foaming agent and the like, and can improve the liquid absorption rate and the storage capacity of the ceramic composite layer to the electrolyte, thereby improving the wettability and reducing the resistance of lithium ions to pass through.
Preferably, the bonding particles are one or more of PVDF and PMMA. The glass transition temperature is 30-100 ℃. When the transition temperature is too low, the polymer is easy to soften and melt at a lower temperature, even permeates into pores of the isolation membrane substrate to block the pores, and can obstruct the transmission of lithium ions, when the transition temperature is too high, the polymer can soften to play a role in bonding the isolation membrane and the pole piece only when reaching a higher temperature, the normal battery formation enables the bonding temperature of the isolation membrane and the pole piece to be about 85 ℃, the transition temperature is too high, the bonding performance is poor, and the battery core is easy to soften and deform. Preferably, PMMA is used.
Preferably, the thickener is nanofiber, and is one or a mixture of more than two of methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose and hydroxypropyl methyl cellulose. The relative molecular weight of the thickener is preferably 10000-200000, the thickened slurry improves the stability of the slurry and simultaneously improves the wettability and the adhesiveness of the slurry and a matrix.
Preferably, the binder is one or a mixture of more than two of polyacrylate, polyacrylonitrile, polyvinyl alcohol, organic silicon, epoxy resin and polyurethane. Preferably, the binder is a polyacrylate binder.
Preferably, the coating mode is one or more of micro gravure coating, rotary spraying, air gun spraying, spot coating and extrusion coating.
The third purpose of the invention is that: aiming at the defects of the prior art, the lithium ion battery is provided, the lithium ion transmission speed is high, the wettability is good, the interface has no black spots, no lithium is separated, and the cycle capacity retention rate is low.
In order to achieve the purpose, the invention adopts the following technical scheme:
a lithium ion battery comprises a positive electrode, a negative electrode and the lithium ion battery diaphragm, wherein the lithium ion battery diaphragm is used for separating the positive electrode and the negative electrode.
Preferably, the thickener is one or a mixture of more than two of nano-fiber, sodium carboxymethyl cellulose, hydroxyethyl cellulose and hydroxypropyl methyl cellulose.
Compared with the prior art, the invention has the beneficial effects that:
1. a lithium ion battery diaphragm is characterized in that a base film layer is coated with a ceramic composite layer, the ceramic composite layer has large porosity and large pore diameter, the mechanical strength of the whole diaphragm is improved, the liquid absorption rate is also improved, and the lithium ion transmission rate is improved, so that the conditions of insufficient electrolyte infiltration, interface black spots, lithium precipitation and low cycle retention rate after high-power high-rate output or multiple charge and discharge cycles are improved.
2. A preparation method of a lithium ion battery diaphragm is characterized in that a dispersant and a foaming agent are added into ceramic composite slurry, the dispersant can reduce the surface tension in the slurry, the slurry is mechanically stirred and mixed with air, a double electronic layer is arranged on the surface of a base film layer to surround the air during coating, a large number of bubbles are generated, pores are formed after drying, and meanwhile, the foaming agent is volatilized to form pores during drying, thereby increasing the porosity and the aperture of the whole body, increasing the liquid absorption rate and further improving the transmission rate of lithium ions, preparing bonding slurry with certain solid content, coating the bonding slurry on two sides of the outermost surface of the whole body, thereby forming a bonding layer and preparing the lithium ion battery diaphragm, the prepared diaphragm has high lithium ion transmission rate, can be circularly charged and discharged for many times, has long service life, the situations of insufficient electrolyte infiltration, black spots on the interface, lithium precipitation and low cycle retention rate are avoided during high-power and high-rate output.
3. The lithium ion battery has the advantages of high lithium ion transmission speed, good wettability, no black spots on the interface, no lithium precipitation and low cycle capacity retention rate.
Drawings
Fig. 1 is one of the structural schematic diagrams of the lithium ion battery separator of the present invention.
Fig. 2 is a second schematic structural diagram of the lithium ion battery separator of the present invention.
Fig. 3 is a graph comparing results of the separator of comparative example 1 after 100, 500 and 700 charge and discharge cycles.
Fig. 4 is a graph comparing results of 20 charge and discharge cycles at 2C rate, 3C rate, and 4C rate in comparative example 1.
FIG. 5 is a graph comparing the results of wettability of comparative example 1 (left) and example 1 (right) of the present invention.
Wherein: 1. a base film layer; 2. a ceramic composite layer; 3. a first adhesive layer; 4. and a second adhesive layer.
Detailed Description
1. A lithium ion battery diaphragm comprises a first bonding layer 3, a base film layer 1, a ceramic composite layer 2 and a second bonding layer 4 which are sequentially arranged from bottom to top, wherein the porosity of the ceramic composite layer 2 is 20% -80%, and the pore size is 0.1-0.5 um. Or, the lithium ion battery diaphragm comprises a base film layer 1 and a ceramic composite layer 2, wherein the ceramic composite layer 2 is arranged on the surface of the base film layer 1, the porosity of the ceramic composite layer 2 is 50% -80%, and the pore size is 0.1-0.5 um. The adhesive layer comprises a first adhesive layer 3 and a second adhesive layer 4, wherein the first adhesive layer 3 and the second adhesive layer 4 are used only for distinguishing the positions of the two, and the preparation raw materials, the preparation method and the size and thickness of the two are the same, and the following is the same.
According to the lithium ion battery diaphragm, the ceramic composite layer 2 is coated on the base film layer 1, and the ceramic composite layer 2 has large porosity and large aperture, as shown in figure 1, the mechanical strength of the whole diaphragm is improved, the liquid absorption rate is also improved, and the lithium ion transmission rate is improved, so that the situations of insufficient electrolyte infiltration, interface black spots, lithium precipitation and low cycle retention rate after high-power high-rate output or multiple charge and discharge cycles are improved.
2. A preparation method of a lithium ion battery separator comprises the following steps:
step (A): preparing ceramic composite slurry: ceramic particles, a thickening agent, a dispersing agent, a binder and a foaming agent are mixed according to the weight part ratio of 50-99: 0.1-1: 0.01-1: 2-6: 0.1-5, mixing and stirring to form ceramic composite slurry with solid content of 20-40%;
step (B): preparing bonding slurry: the adhesive particles, the thickening agent, the dispersing agent and the binder are mixed according to the weight ratio of 80-95: 0.1-1.5: 0.01-1: 0.1-5, mixing and stirring to form bonding slurry with solid content of 2-6%;
step (C): coating ceramic composite slurry on one surface of the base film layer 1, drying to form a ceramic composite layer 2, coating bonding slurry on the surface of the ceramic composite layer 2, drying to form a first bonding layer 3, coating bonding slurry on the other surface of the base film layer 1, and drying to form a second bonding layer 4 to obtain the lithium ion battery diaphragm.
The preparation method of the lithium ion battery diaphragm of the invention adds dispersant and foaming agent in the ceramic composite slurry, the dispersant can reduce the surface tension in the slurry, mechanical stirring and air mixing are carried out, double electronic layers are arranged on the surface of the base film layer 1 to surround the air during coating, as shown in figure 2, the ceramic particles and the foaming agent in the ceramic slurry are uniformly arranged on the surface of the base film layer 1, a large amount of bubbles are generated during foaming of the foaming agent, pores are formed after drying, as shown in figure 1, meanwhile, the foaming agent volatilizes to form pores during drying, so that the porosity and pore diameter of the whole are increased, the liquid absorption rate is increased, the transmission rate of lithium ions is increased, and the bonding slurry with certain solid content is prepared and coated on two sides of the outermost surface of the whole to form bonding layers, so that the lithium ion battery diaphragm is prepared, the lithium ion transmission rate of the prepared diaphragm is high, the lithium ion battery can be charged and discharged repeatedly, has long service life, does not have the situations of insufficient electrolyte infiltration, interface black spots and lithium precipitation in high-power and high-rate output, and is easy to circulate with low retention rate.
Preferably, the base film layer 1 is made of PE, PP or a PE/PP/PE composite isolating film, the melting point of the base film layer 1 is 130-160 ℃, the thickness is 3-20um, the porosity is 20-50%, and the air permeability is 30-400sec/100 cc.
Preferably, the thickness of the first adhesive layer 3 and/or the second adhesive layer 4 is 0.2-10 um, and the coating gram weight is 0.05-5.0 g/m2The thermal shrinkage is less than or equal to 10 percent, and the peel strength is more than or equal to 20N/m.
Preferably, the ceramic particles are SiO2、Al2O3、CaO、TiO2、MgO、ZnO、SnO2、ZrO2、AlOOH、Mg(OH)2、BaSO4One or a mixture of two or more of them.
Preferably, the thickener is one or a mixture of more than two of nano-fiber, sodium carboxymethyl cellulose, hydroxyethyl cellulose and hydroxypropyl methyl cellulose.
Preferably, the dispersing agent is one or a mixture of more than two of dodecyl sulfuric acid, fatty alcohol polyoxyethylene ether sulfuric acid, rosin soap, animal and vegetable protein dispersing agents and the like.
Preferably, the binder is one or a mixture of more than two of polyacrylate, polyacrylonitrile, polyvinyl alcohol, organic silicon, epoxy resin and polyurethane.
Preferably, the foaming agent is one or a mixture of more than two of n-pentane, n-hexane, n-heptane, petroleum ether, trichlorofluoromethane, dichlorofluoromethane and dichlorotetrafluoroethane.
Preferably, the coating mode is one or more of micro gravure coating, rotary spraying, air gun spraying, spot coating and extrusion coating.
Preferably, the binder is one or a mixture of two or more of polyacrylates, polyacrylonitrile, polyvinyl alcohols, silicones, epoxies and polyurethanes.
3. A lithium ion battery comprises a positive plate, a negative plate and a diaphragm, wherein the positive plate and the negative plate are respectively arranged on two sides of the diaphragm, and the diaphragm is any one of the diaphragms provided by the invention.
The active material layer coated on the current collector of the positive plate can be, but is not limited to, an active material of a chemical formula such as LiaNixCoyMzO2-bNb(wherein a is more than or equal to 0.95 and less than or equal to 1.2, x>0, y is more than or equal to 0, z is more than or equal to 0, and x + y + z is 1,0 is more than or equal to b and 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), and the positive electrode active material can also be selected from one or more of LiCoO (lithium LiCoO), but not limited to2、LiNiO2、LiVO2、LiCrO2、LiMn2O4、LiCoMnO4、Li2NiMn3O8、LiNi0.5Mn1.5O4、LiCoPO4、LiMnPO4、LiFePO4、LiNiPO4、LiCoFSO4、CuS2、FeS2、MoS2、NiS、TiS2And the like. The positive electrode active material may be further modified, and the method of modifying the positive electrode active material is known to those skilled in the art, for example, the positive electrode active material may be modified by coating, doping, and the like, and the material used in the modification may be one or a combination of 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.
The active material layer coated on the current collector of the negative plate 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.
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 electrolyte6And/or LiBOB; or may be a low-temperature typeLiBF used in the decomposing liquid4、LiBOB、LiPF6At least one of; or LiBF used in anti-overcharge electrolyte4、LiBOB、LiPF6At least one of, LiTFSI; may also be LiClO4、LiAsF6、LiCF3SO3、LiN(CF3SO2)2At 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, control of H in the electrolyte2At least one of additives of O and HF content, additives for improving low temperature performance, and multifunctional additives.
The present invention will be described in further detail with reference to the following detailed description and the accompanying drawings, but the embodiments of the invention are not limited thereto.
Example 1
(1) Preparation of positive plate
Uniformly mixing NCM811 positive active material, conductive agent superconducting carbon, carbon tubes and adhesive polyvinylidene fluoride according to the mass ratio of 96:2.0:0.5:1.5 to prepare positive slurry, coating the positive slurry on one surface of a current collector aluminum foil, drying and rolling at 85 ℃, coating and drying the positive slurry on the other surface of the aluminum foil according to the method, and then carrying out cold pressing treatment on the prepared pole piece with the positive active material layers coated on the two surfaces of the aluminum foil; and (4) trimming, cutting into pieces, slitting, and slitting to obtain the lithium ion battery positive plate.
(2) Preparation of negative plate
Preparing a silicon-carbon negative electrode active substance, a conductive agent superconducting carbon, a thickening agent sodium carboxymethyl cellulose and a binder styrene butadiene rubber into negative electrode slurry according to the mass ratio of 96.5:1.0:1.0:1.5, coating the negative electrode slurry on a current collector copper foil, drying and rolling at 85 ℃, coating and drying positive electrode slurry on the other side of the copper foil according to the method, and then carrying out cold pressing treatment on a pole piece with a negative electrode active substance layer coated on the two sides of the prepared copper foil; and (4) trimming, cutting into pieces, slitting, and slitting to obtain the lithium ion battery positive plate.
(3) Preparation of the separator
A preparation method of a lithium ion battery separator comprises the following steps:
step (A): preparing ceramic composite slurry: ceramic particles, a thickening agent, a dispersing agent, a binder and a foaming agent are mixed according to the weight ratio of 90: 0.5: 0.5: 5: 3 mixing and stirring to form ceramic composite slurry with solid content of 20 percent;
step (B): preparing bonding slurry: the adhesive particles, the thickening agent, the dispersing agent and the adhesive are mixed according to the weight ratio of 90: 0.5: 0.5: 5 mixing and stirring to form bonding slurry with solid content of 2 percent;
step (C): coating ceramic composite slurry on one surface of the base film layer 1, drying to form a ceramic composite layer 2, coating adhesive slurry on the surface of the ceramic composite layer 2, drying to form an adhesive layer, coating adhesive slurry on the other surface of the base film layer 1, drying to form the adhesive layer, and preparing the lithium ion battery diaphragm.
Preferably, the base film layer 1 is made of a PE/PP/PE composite isolating film, the melting point of the base film layer 1 is 160 ℃, the thickness of the base film layer is 15um, the porosity of the base film layer is 30%, and the air permeability of the base film layer is 300sec/100 cc.
Preferably, the adhesive layer has a thickness of 8um and a coating grammage of 3.0g/m2The thermal shrinkage is less than or equal to 10 percent, and the peel strength is more than or equal to 20N/m.
Preferably, the ceramic particles are SiO2。
Preferably, the thickener is a nanofiber.
Preferably, the dispersant is sodium lauryl sulfate.
Preferably, the binder is a polyacrylate.
Preferably, the blowing agent is n-pentane.
Preferably, the coating mode is micro gravure coating.
Preferably, the binder is polyacrylonitrile.
The utility model provides a lithium ion battery diaphragm, includes from supreme first adhesive linkage 3, base rete 1, ceramic composite bed 2 and the second adhesive linkage 4 that sets gradually down, the porosity of ceramic composite bed 2 is 80%, and the aperture size is 0.5 um. Here, the first adhesive layer 3 and the second adhesive layer 4 are used only for distinguishing the positions of the two, and the raw materials, the methods, and the dimensions and thicknesses of the two are the same, as follows.
(4) Preparing an electrolyte:
mixing lithium hexafluorophosphate (LiPF)6) Dissolving in a mixed solvent of dimethyl carbonate (DEC), Ethylene Carbonate (EC), Ethyl Methyl Carbonate (EMC) and diethyl carbonate (DEC) (the mass ratio of the three is 3: 5: 2) and obtaining the electrolyte.
(5) Preparing a battery:
and winding the positive plate, the diaphragm and the negative plate into a battery cell, wherein the battery cell capacity is about 5 Ah. The diaphragm is positioned between the adjacent positive plate and negative plate, the positive electrode is led out by aluminum tab spot welding, and the negative electrode is led out by nickel tab spot welding; then the electric core is placed in an aluminum-plastic packaging bag, the electrolyte is injected after baking, and finally the polymer lithium ion battery is prepared after the processes of packaging, formation, capacity grading and the like.
In the preparation method of the lithium ion battery separator in embodiment 1, a dispersant and a foaming agent are added into a ceramic composite slurry, the dispersant can reduce the surface tension in the slurry, the slurry is mechanically stirred and mixed with air, and the two electronic layers surrounding the air are arranged on the surface of a base film layer 1 during coating, as shown in fig. 1, ceramic particles and the foaming agent in the ceramic slurry are uniformly arranged on the surface of the base film layer 1, a large amount of bubbles are generated during foaming of the foaming agent, pores are formed after drying, as shown in fig. 2, and meanwhile, the foaming agent volatilizes during drying to form pores, so that the porosity and pore diameter of the whole are increased, the liquid absorption rate is increased, the transmission rate of lithium ions is increased, and an adhesive slurry with a certain solid content is prepared and coated on two sides of the outermost surface of the whole to form an adhesive layer, so that the lithium ion battery separator is prepared, and the lithium ion transmission rate of the separator is high, the lithium ion battery can be charged and discharged repeatedly, has long service life, does not have the situations of insufficient electrolyte infiltration, interface black spots and lithium precipitation in high-power and high-rate output, and is easy to circulate with low retention rate.
Example 2
The difference from the embodiment 1 is that:
(3) preparation of the separator
A preparation method of a lithium ion battery separator comprises the following steps:
step (A): preparing ceramic composite slurry: ceramic particles, a thickening agent, a dispersing agent, a binder and a foaming agent are mixed according to the weight ratio of 90: 0.5: 0.5: 5: 0.8, mixing and stirring to form ceramic composite slurry with the solid content of 30 percent;
step (B): preparing bonding slurry: the adhesive particles, the thickening agent, the dispersing agent and the adhesive are mixed according to the weight ratio of 90: 0.5: 0.5: 4 mixing and stirring to form bonding slurry with solid content of 5 percent;
step (C): coating ceramic composite slurry on one surface of the base film layer 1, drying to form a ceramic composite layer 2, coating bonding slurry on the surface of the ceramic composite layer 2, drying to form a first bonding layer 3, coating bonding slurry on the other surface of the base film layer 1, and drying to form a second bonding layer 4 to obtain the lithium ion battery diaphragm.
Preferably, the base film layer 1 is made of a PE isolating film, the melting point of the base film layer 1 is 120 ℃, the thickness of the base film layer 1 is 8um, the porosity of the base film layer is 20%, and the air permeability of the base film layer is 200sec/100 cc.
Preferably, the thickness of the first adhesive layer 3 and the second adhesive layer 4 is 10um, and the coating gram weight is 0.1g/m2The thermal shrinkage is less than or equal to 10 percent, and the peel strength is more than or equal to 20N/m.
Preferably, the ceramic particles are Al2O3。
Preferably, the thickener is sodium carboxymethyl cellulose.
Preferably, the dispersing agent is fatty alcohol-polyoxyethylene ether sodium sulfate.
Preferably, the binder is polyacrylonitrile.
Preferably, the blowing agent is n-hexane.
Preferably, the coating mode is micro gravure coating.
The utility model provides a lithium ion battery diaphragm, includes from supreme first adhesive linkage 3, base rete 1, ceramic composite bed 2 and the second adhesive linkage 4 that sets gradually down, the porosity of ceramic composite bed 2 is 60%, and the aperture size is 0.4 um.
The rest is the same as embodiment 1, and the description is omitted here.
Example 3
The difference from the embodiment 1 is that:
(3) preparation of the separator
A preparation method of a lithium ion battery separator comprises the following steps:
step (A): preparing ceramic composite slurry: ceramic particles, a thickening agent, a dispersing agent, a binder and a foaming agent are mixed according to the weight ratio of 90: 0.5: 0.5: 5: 2 mixing and stirring to form ceramic composite slurry with solid content of 20 percent;
step (B): preparing bonding slurry: the adhesive particles, the thickening agent, the dispersing agent and the adhesive are mixed according to the weight ratio of 90: 0.5: 0.5: 2 mixing and stirring to form bonding slurry with solid content of 3 percent;
step (C): coating ceramic composite slurry on one surface of the base film layer 1, drying to form a ceramic composite layer 2, coating bonding slurry on the surface of the ceramic composite layer 2, drying to form a first bonding layer 3, coating bonding slurry on the other surface of the base film layer 1, and drying to form a second bonding layer 4 to obtain the lithium ion battery diaphragm.
Preferably, the base film layer 1 is made of a PP barrier film, the melting point of the base film layer 1 is 130 ℃, the thickness of the base film layer is 18um, the porosity of the base film layer is 40%, and the air permeability of the base film layer is 250sec/100 cc.
Preferably, the thickness of the first adhesive layer 3 and/or the second adhesive layer 4 is 8um, and the coating gram weight is 3.0g/m2The thermal shrinkage is less than or equal to 10 percent, and the peel strength is more than or equal to 20N/m.
Preferably, the ceramic particles are TiO2。
Preferably, the thickener is carboxymethyl cellulose.
Preferably, the dispersant is an animal and vegetable protein dispersant.
Preferably, the binder is one or a mixture of more than two of polyacrylate, polyacrylonitrile, polyvinyl alcohol, organic silicon, epoxy resin and polyurethane.
Preferably, the foaming agent is one or a mixture of more than two of n-pentane, n-hexane, n-heptane, petroleum ether, trichlorofluoromethane, dichlorofluoromethane and dichlorotetrafluoroethane.
Preferably, the coating mode is one or more of micro gravure coating, rotary spraying, air gun spraying, spot coating and extrusion coating.
A lithium ion battery diaphragm comprises a first bonding layer 3, a base film layer 1, a ceramic composite layer 2 and a second bonding layer 4 which are sequentially arranged from bottom to top, wherein the porosity of the ceramic composite layer 2 is 20% -80%, and the pore size is 0.1-0.5 um.
The rest is the same as embodiment 1, and the description is omitted here.
Example 4
The difference from the embodiment 1 is that:
(3) preparation of the separator
A preparation method of a lithium ion battery separator comprises the following steps:
step (A): preparing ceramic composite slurry: ceramic particles, a thickening agent, a dispersing agent, a binder and a foaming agent are mixed according to the weight ratio of 90: 0.5: 0.5: 5: 2.5 mixing and stirring to form ceramic composite slurry with solid content of 20 percent;
step (B): preparing bonding slurry: the adhesive particles, the thickening agent, the dispersing agent and the binder are mixed according to the weight ratio of 80-95: 0.1-1.5: 0.01-1: 0.1-5, mixing and stirring to form bonding slurry with solid content of 2-6%;
step (C): coating ceramic composite slurry on one surface of the base film layer 1, drying to form a ceramic composite layer 2, coating bonding slurry on the surface of the ceramic composite layer 2, drying to form a first bonding layer 3, coating bonding slurry on the other surface of the base film layer 1, and drying to form a second bonding layer 4 to obtain the lithium ion battery diaphragm.
Preferably, the base film layer 1 is made of a PE/PP/PE composite isolating film, the melting point of the base film layer 1 is 150 ℃, the thickness of the base film layer is 18um, the porosity of the base film layer is 40%, and the air permeability of the base film layer is 200sec/100 cc.
Preferably, of said first 3 and/or second 4 adhesive layerThe thickness is 6um, and the coating gram weight is 3.0g/m2The thermal shrinkage is less than or equal to 10 percent, and the peel strength is more than or equal to 20N/m.
Preferably, the ceramic particles are ZrO2。
Preferably, the thickener is hydroxypropyl methylcellulose.
Preferably, the dispersant is sodium lauryl sulfate.
Preferably, the binder is a polyacrylate binder.
Preferably, the blowing agent is petroleum ether.
Preferably, the coating is by spin coating.
The utility model provides a lithium ion battery diaphragm, includes from supreme first adhesive linkage 3, base rete 1, ceramic composite bed 2 and the second adhesive linkage 4 that sets gradually down, the porosity of ceramic composite bed 2 is 30%, and the aperture size is 0.2 um.
The rest is the same as embodiment 1, and the description is omitted here.
Example 5
The difference from the embodiment 1 is that:
(3) preparation of the separator
A preparation method of a lithium ion battery separator comprises the following steps:
step (A): preparing ceramic composite slurry: ceramic particles, a thickening agent, a dispersing agent, a binder and a foaming agent are mixed according to the weight ratio of 90: 0.5: 0.5: 5: 5 mixing and stirring to form ceramic composite slurry with solid content of 20%;
step (B): preparing bonding slurry: the adhesive particles, the thickening agent, the dispersing agent and the adhesive are mixed according to the weight ratio of 90: 0.5: 0.5: 4, mixing and stirring to form bonding slurry with solid content of 4 percent;
step (C): coating ceramic composite slurry on one surface of the base film layer 1, drying to form a ceramic composite layer 2, coating bonding slurry on the surface of the ceramic composite layer 2, drying to form a first bonding layer 3, coating bonding slurry on the other surface of the base film layer 1, and drying to form a second bonding layer 4 to obtain the lithium ion battery diaphragm.
Preferably, the base film layer 1 is made of a PP isolating film, the melting point of the base film layer 1 is 150 ℃, the thickness of the base film layer is 12um, the porosity of the base film layer is 20%, and the air permeability of the base film layer is 200sec/100 cc.
Preferably, the thickness of the first adhesive layer 3 and the second adhesive layer 4 is 6um, and the coating gram weight is 3.5g/m2The thermal shrinkage is less than or equal to 10 percent, and the peel strength is more than or equal to 20N/m.
Preferably, the ceramic particles are Mg (OH)2。
Preferably, the thickener is a nanofiber.
Preferably, the dispersant is a dodecyl sulfuric acid-based dispersant.
Preferably, the binder is a polyacrylate.
Preferably, the blowing agent is trichlorofluoromethane.
Preferably, the coating is by air gun spraying.
The utility model provides a lithium ion battery diaphragm, includes from supreme first adhesive linkage 3, base rete 1, ceramic composite bed 2 and the second adhesive linkage 4 that sets gradually down, the porosity of ceramic composite bed 2 is 20%, and the aperture size is 0.1 um.
The rest is the same as embodiment 1, and the description is omitted here.
Example 6
The difference from the embodiment 1 is that:
(3) preparation of the separator
A preparation method of a lithium ion battery separator comprises the following steps:
step (A): preparing ceramic composite slurry: ceramic particles, a thickening agent, a dispersing agent, a binder and a foaming agent are mixed according to the weight ratio of 90: 0.5: 0.5: 5:1.5 mixing and stirring to form ceramic composite slurry with solid content of 20 percent;
step (B): preparing bonding slurry: the adhesive particles, the thickening agent, the dispersing agent and the adhesive are mixed according to the weight ratio of 90: 0.5: 0.5: 4, mixing and stirring to form bonding slurry with solid content of 4 percent;
step (C): coating ceramic composite slurry on one surface of the base film layer 1, drying to form a ceramic composite layer 2, coating bonding slurry on the surface of the ceramic composite layer 2, drying to form a first bonding layer 3, coating bonding slurry on the other surface of the base film layer 1, and drying to form a second bonding layer 4 to obtain the lithium ion battery diaphragm.
Preferably, the base film layer 1 is made of a PE barrier film, the melting point of the base film layer 1 is 130 ℃, the thickness of the base film layer is 5um, the porosity of the base film layer is 40%, and the air permeability of the base film layer is 100sec/100 cc.
Preferably, the thickness of the first adhesive layer 3 and the second adhesive layer 4 is 6um, and the coating gram weight is 1.0g/m2The thermal shrinkage is less than or equal to 10 percent, and the peel strength is more than or equal to 20N/m.
Preferably, the ceramic particles are SiO2。
Preferably, the thickener is a nanofiber.
Preferably, the dispersant is a dodecyl sulphate.
Preferably, the binder is of the silicone type.
Preferably, the blowing agent is dichlorotetrafluoroethane.
Preferably, the coating is spot coating.
The utility model provides a lithium ion battery diaphragm, includes from supreme first adhesive linkage 3, base rete 1, ceramic composite bed 2 and the second adhesive linkage 4 that sets gradually down, the porosity of ceramic composite bed 2 is 30%, and the aperture size is 0.3 um.
The rest is the same as embodiment 1, and the description is omitted here.
Examples 7 to 18 were further prepared according to the preparation method of example 1, and the preparation of the separator was different from that of example 1, and the specific settings are shown in table 1. Wherein A represents the weight portion ratio of ceramic particles, a thickening agent, a dispersing agent, a binding agent and a foaming agent; and B represents the weight portion ratio of the bonding particles, the thickening agent, the dispersing agent and the binding agent.
TABLE 1
Comparative example 1
The difference from the embodiment 1 is that: a conventional PP separator was used.
Performance testing
The separators of examples 1 to 17 and comparative example 1 were subjected to a wettability test after 1500 charge and discharge cycles, and the presence of black spots or white spots at the interface of the separator, the presence of lithium deposition, and a cycle capacity retention rate test of the prepared battery were observed, and the results are shown in table 2.
Wherein, the diffusion performance test: 1. fixing the diaphragm on the fixing clamp for flattening; 2. taking a certain amount of electrolyte, and sucking the electrolyte into a dropping gun; 3. vertically aligning a liquid dropping gun to the center of the test sample, and dropping electrolyte; 4. after 1 minute, the areas of electrolyte diffusion were compared. The results are shown in FIG. 5.
TABLE 2
| Whether or not there is black spot | Whether or not there is white spot | Whether or not there is lithium precipitation | Retention rate of circulating capacity | |
| Example 1 | Is free of | Is free of | Is free of | 98 |
| Example 2 | Is free of | Is free of | Is free of | 96 |
| Example 3 | Is free of | Is free of | Is free of | 95 |
| Example 4 | Is free of | Is free of | Is free of | 96 |
| Example 5 | Is free of | Is free of | Is free of | 96 |
| Example 6 | Is free of | Is free of | Is free of | 97 |
| Example 7 | Is free of | Is free of | Is free of | 95 |
| Example 8 | Is free of | Is free of | Is free of | 95 |
| Example 9 | Is free of | Is free of | Is free of | 94 |
| Example 10 | Is free of | Is free of | Is free of | 96 |
| Example 11 | Is free of | Is free of | Is free of | 96 |
| Example 12 | Is free of | Is free of | Is free of | 96 |
| Example 13 | Is free of | Is free of | Is free of | 96 |
| Example 14 | Is free of | Is free of | Is free of | 96 |
| Example 15 | Is free of | Is free of | Is free of | 95 |
| Example 16 | Is free of | Is free of | Is free of | 95 |
| Example 17 | Is free of | Is free of | Is free of | 95 |
| Comparative example 1 | Is provided with | Is provided with | Is free of | 74 |
As can be seen from the above tables 1 and 2 and fig. 1 to 5, the separators of examples 1 to 17 of the present invention have better performance, better electrolyte wettability, no interface black spots and white spots, no lithium deposition, and better retention of cycle capacity up to 98%, compared to the separator of comparative example 1. The reason is that the ceramic composite layer 2 is coated on the base film layer 1, and the ceramic composite layer 2 has larger porosity and larger aperture, so that the mechanical strength of the whole diaphragm is improved, the liquid absorption rate is also improved, the lithium ion transmission rate is improved, and the conditions of insufficient electrolyte infiltration, interface black spots, lithium precipitation and low cycle retention rate after high-power high-rate output or multiple charge and discharge cycles are improved.
As shown in fig. 3 and 4, the separator of comparative example 1 showed black spots and white spots after many cycles, and when the separator was used in a continuous charge and discharge manner, it was liable to cause short circuit of the battery, and the battery was liable to generate heat and fire, resulting in poor safety.
As can be seen from FIG. 5, comparative example 1 had a wetted area of about 1cm in 1 minute2The wetting area of the diaphragm prepared by the invention is about 4cm in 1 minute2The wetted area was 4 times that of comparative example 1.
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 (10)
1. A lithium ion battery separator, characterized in that: the ceramic composite membrane comprises a base membrane layer and a ceramic composite layer, wherein the ceramic composite layer is arranged on the surface of the base membrane layer, the porosity of the ceramic composite layer is 50% -80%, and the pore size is 0.1-0.5 um.
2. The lithium ion battery separator according to claim 1, wherein: the base film layer is made of PE, PP or a PE/PP/PE composite isolating film, the melting point of the base film layer is 130-160 ℃, the thickness of the base film layer is 3-20 mu m, the porosity of the base film layer is 20-50%, and the air permeability of the base film layer is 30-400sec/100 cc.
3. The lithium ion battery separator according to claim 1, wherein: the lithium ion battery diaphragm further comprises an adhesive layer for bonding, wherein the adhesive layer is arranged on one surface, away from the ceramic composite layer, of the base film layer and on one surface, away from the base film layer, of the ceramic composite layer.
4. The lithium ion battery separator according to claim 3, wherein: the thickness of the bonding layer is 0.2-10 um, and the coating gram weight is 0.05-5.0 g/m2The thermal shrinkage is less than or equal to 10 percent, and the peel strength is more than or equal to 20N/m.
5. The preparation method of the lithium ion battery separator according to claim 1, characterized in that: the method comprises the following steps:
step (A): ceramic particles, a thickening agent, a dispersing agent, a binder and a foaming agent are mixed according to the weight part ratio of 50-99: 0.1-1: 0.01-1: 2-6: 0.1-5, mixing and stirring to form ceramic composite slurry with solid content of 20-40%;
step (B): and coating the ceramic composite slurry on the surface of the base film layer, controlling the temperature, and drying to ensure that the foaming agent catalyzes and forms a ceramic composite layer to prepare the lithium ion battery diaphragm.
6. The preparation method of the lithium ion battery separator according to claim 5, wherein the preparation method comprises the following steps: the method comprises the following steps:
step (A): ceramic particles, a thickening agent, a dispersing agent, a binder and a foaming agent are mixed according to the weight part ratio of 50-99: 0.1-1: 0.01-1: 2-6: 0.1-5, mixing and stirring to form ceramic composite slurry with solid content of 20-40%;
step (B): coating ceramic composite slurry on one surface of the base film layer, controlling the temperature, and drying to volatilize the foaming agent to form a ceramic composite layer;
step (C): the adhesive particles, the thickening agent, the dispersing agent and the binder are mixed according to the weight ratio of 80-95: 0.1-1.5: 0.01-1: 0.1-5, mixing and stirring to form bonding slurry with solid content of 2-6%;
step (D): and coating bonding slurry on one surface of the base film layer, which is far away from the ceramic composite layer, to form a bonding layer, and coating bonding slurry on one surface of the ceramic composite layer, which is far away from the base film layer, to form a bonding layer, so as to prepare the lithium ion battery diaphragm.
7. The preparation method of the lithium ion battery separator according to claim 5, wherein the preparation method comprises the following steps: the ceramic particles are SiO2、Al2O3、CaO、TiO2、MgO、ZnO、SnO2、ZrO2、AlOOH、Mg(OH)2、BaSO4One or a mixture of two or more of them.
8. The preparation method of the lithium ion battery separator according to claim 5, wherein the preparation method comprises the following steps: the foaming agent is one or a mixture of more than two of n-pentane, n-hexane, n-heptane, petroleum ether, trichlorofluoromethane, dichlorofluoromethane and dichlorotetrafluoroethane.
9. The preparation method of the lithium ion battery separator according to claim 5, wherein the preparation method comprises the following steps: the dispersing agent is one or a mixture of more than two of dodecyl sulfuric acid, fatty alcohol polyoxyethylene ether sulfuric acid, rosin soap, animal and vegetable protein dispersing agents and the like.
10. A lithium ion battery, characterized by: comprising a positive electrode, a negative electrode, and the lithium ion battery separator of any one of claims 1-4 for separating the positive electrode and the negative electrode.
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Application publication date: 20210914 |