CN110416472B - Mesoporous silica microsphere lithium ion battery diaphragm and lithium ion battery - Google Patents
Mesoporous silica microsphere lithium ion battery diaphragm and lithium ion battery Download PDFInfo
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- CN110416472B CN110416472B CN201910575648.4A CN201910575648A CN110416472B CN 110416472 B CN110416472 B CN 110416472B CN 201910575648 A CN201910575648 A CN 201910575648A CN 110416472 B CN110416472 B CN 110416472B
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- H01—ELECTRIC ELEMENTS
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- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
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- H01M10/0587—Construction or manufacture of accumulators having only wound construction elements, i.e. wound positive electrodes, wound negative electrodes and wound separators
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- H—ELECTRICITY
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- 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
- H01M50/403—Manufacturing processes of separators, membranes or diaphragms
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- 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
- H01M50/446—Composite material consisting of a mixture of organic and inorganic materials
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- H—ELECTRICITY
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- 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
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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
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Abstract
The invention belongs to the technical field of battery materials, and particularly relates to a mesoporous silica microsphere lithium ion battery diaphragm which comprises a diaphragm substrate and a mesoporous silica microsphere layer coated on at least one surface of the diaphragm substrate, wherein the mesoporous silica microsphere layer comprises mesoporous silica microspheres, an aqueous binder, a dispersing agent, a thickening agent and water, and the mass of the mesoporous silica microspheres accounts for 30-50% of the total mass of the mesoporous silica microsphere layer. Compared with the prior art, the lithium ion battery diaphragm has larger electrolyte loading capacity and better wettability to the electrolyte. In addition, the invention also provides a lithium ion battery containing the mesoporous silica microsphere lithium ion battery diaphragm, which has good safety performance and cycle performance.
Description
Technical Field
The invention belongs to the technical field of battery materials, and particularly relates to a mesoporous silica microsphere lithium ion battery diaphragm and a lithium ion battery.
Background
Lithium ion batteries have been developed rapidly in recent years as a new star in new energy industries. Lithium ion batteries mainly comprise four major classes of materials: electrodes, electrolyte, separator and encapsulating material. The diaphragm is always produced by developed countries such as America and the like in an early stage due to higher technical requirements of the production process. In recent years, the rapid development of the new energy industry in China has promoted a large number of diaphragm production enterprises owned by China, and the capacity and the quality increasingly approach high-end international manufacturers.
At present, polyolefin materials such as polypropylene (PP), Polyethylene (PE) and the like are main matrix materials of lithium ion battery separators, but polypropylene (PP), Polyethylene (PE) and other thermoplastic high polymer materials are shrunk and deformed due to melting when the melting points of the materials are close to the melting points, so that potential hazards are brought to the safety of lithium ion batteries. If the requirements of future high-power lithium ion batteries are to be met, the lithium ion battery diaphragm needs to consider the limitation range of further improving the thermal stability temperature. Therefore, on the basis of the existing matrix material system, the thermal stability of the diaphragm is improved by coating the matrix material with a ceramic coating. Although the ceramic coating can improve the thermal stability of the separator to a certain extent, the liquid absorption and retention capability of the ceramic coating is not ideal, and the cycle performance of the battery performance is affected to a certain extent.
Disclosure of Invention
One of the objects of the present invention is: aiming at the defects of the prior art, the mesoporous silica microsphere lithium ion battery diaphragm has larger electrolyte loading capacity and better wettability to the electrolyte.
In order to achieve the purpose, the invention adopts the following technical scheme:
the mesoporous silica microsphere lithium ion battery diaphragm comprises a diaphragm substrate and a mesoporous silica microsphere layer coated on at least one surface of the diaphragm substrate, wherein the mesoporous silica microsphere layer comprises mesoporous silica microspheres, an aqueous binder, a dispersing agent, a thickening agent and water, and the mass of the mesoporous silica microspheres accounts for 30-50% of the total mass of the mesoporous silica microsphere layer. It should be noted that the mesoporous silica microspheres are not suitable for being too low in quality, otherwise, the liquid absorption and retention performance of the diaphragm cannot be improved.
As an improvement of the mesoporous silica microsphere lithium ion battery diaphragm, the thickness of the mesoporous silica microsphere layer is 1-4 μm. The thickness of the mesoporous silica microsphere layer is too small, so that the liquid absorption and retention performance of the diaphragm cannot be well improved, and the energy density of the whole battery system can be reduced due to the fact that the thickness of the mesoporous silica microsphere layer is too large.
As an improvement of the mesoporous silica microsphere lithium ion battery diaphragm, the surface density of the mesoporous silica microsphere layer is 12-15 g/m2. The surface density of the mesoporous silica microsphere layer is composed of mesoporous silicaThe quality of the silicon dioxide microspheres and the thickness of the mesoporous silicon dioxide microsphere layer are jointly determined, the surface density is proper, and the diaphragm can be ensured to have better liquid absorption and retention performances.
As an improvement of the mesoporous silica microsphere lithium ion battery diaphragm, the preparation method of the mesoporous silica microsphere layer comprises the following steps:
mixing 30-50 parts of silica mesoporous microspheres, 2-10 parts of aqueous binder, 0.3-1 part of dispersant, 0.2-1 part of thickener and 40-50 parts of water, ball-milling, adding 3-10 parts of aqueous binder, and continuing ball-milling and dispersing to obtain silica mesoporous microsphere slurry;
and uniformly coating the mesoporous silica microsphere slurry on a diaphragm substrate, and drying to obtain the lithium ion battery diaphragm.
As an improvement of the mesoporous silica microsphere lithium ion battery diaphragm, the coating speed is 20-50 m/min, the drying temperature is 60-80 ℃, and the drying time is 1-3 min.
As an improvement of the mesoporous silica microsphere lithium ion battery diaphragm, the specific surface area of the mesoporous silica microsphere is 420-430 m2The pore volume of the mesoporous silica microspheres is 0.2-0.25 cm3The pore diameter of the mesoporous silica microspheres is 1-4 nm.
The mesoporous silica microsphere lithium ion battery diaphragm is an improvement, wherein tetraethoxysilane is used as a silicon source, hexadecyl trimethyl ammonium bromide is used as a structural template agent, PVP is used as a dispersing agent, acetone is used as a solvent, and a hydrothermal synthesis method is used for synthesizing the mesoporous silica microsphere. Specifically, under the condition of rapid magnetic stirring, 1.5g of hexadecyl trimethyl ammonium bromide (CTAB) is added into a mixed solution of 132mL of acetone, 36mL of deionized water, 1.5g of PVP and 2mol/L of sodium hydroxide, 8mL of Tetraethoxysilane (TEOS) is rapidly added, slow stirring is continuously carried out, a solution system presents milky turbidity after 15min of feeding is finished, and a reaction solution is kept still for 2-3h at the temperature of 30 ℃. And then, centrifuging the reaction solution, ultrasonically dispersing and cleaning, repeating for multiple times to obtain wet silicon dioxide microspheres, freeze-drying the powder for 6-8 hours, roasting the dried powder in a high-temperature furnace at 550 ℃ for 5 hours, and removing the CTAB template to obtain the mesoporous silicon dioxide microspheres. It should be noted that the invention uses acetone as solvent instead of conventional ethanol, and overcomes the esterification reaction that ethanol hinders the formation of silica gel.
As an improvement of the mesoporous silica microsphere lithium ion battery diaphragm, the porosity of the diaphragm substrate is 42-52%, and the aperture of the diaphragm substrate is 0.5-1.5 μm. The porosity and the pore diameter of the diaphragm base material are reasonably arranged, so that the liquid absorption and retention capacity of the diaphragm can be improved, and the wettability of the diaphragm to electrolyte can be improved.
As an improvement of the mesoporous silica microsphere lithium ion battery diaphragm, the diaphragm substrate is a PP microporous film or a PE microporous film.
The second purpose of the invention is: providing a lithium ion battery, which comprises the mesoporous silica microsphere lithium ion battery diaphragm in any section above.
Compared with the prior art, the invention has the beneficial effects that: according to the invention, the mesoporous silica microsphere layer is arranged on the surface of the diaphragm base material, wherein the mesoporous silica microsphere has larger specific surface area, pore volume and pore diameter and has stronger absorption and retention capacity on electrolyte, so that the diaphragm has larger loading capacity and better wettability on the electrolyte, namely the diaphragm has better liquid retention and absorption capacity. In addition, the diaphragm has better liquid retention and absorption capacity, so that the safety performance and the cycle performance of the lithium ion battery adopting the diaphragm are correspondingly improved.
Drawings
FIG. 1 is an SEM image of mesoporous silica microspheres of the present invention.
FIG. 2 is a TEM image of the mesoporous silica microsphere according to the present invention.
FIG. 3 is a second TEM image of the mesoporous silica microspheres of the present invention.
FIG. 4 is a third TEM image of the mesoporous silica microsphere of the present invention.
Fig. 5 is a graph of the magnification of example 1, comparative example 1 and comparative example 2 in the present invention.
FIG. 6 is a graph showing the cycle chart of example 1 of the present invention.
Detailed Description
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
Preparing mesoporous silica microspheres:
under the condition of rapid magnetic stirring, 1.5g of hexadecyl trimethyl ammonium bromide (CTAB) is added into a mixed solution of 132mL of acetone, 36mL of deionized water, 1.5g of PVP and 2mol/L of sodium hydroxide, 8mL of Tetraethoxysilane (TEOS) is rapidly added, slow stirring is continuously kept, a solution system presents milky turbidity after 15min of feeding is finished, and a reaction solution is kept stand for 2-3h at the temperature of 30 ℃. Then, centrifuging and ultrasonically dispersing and cleaning the reaction liquid, repeating the steps for multiple times to obtain wet silicon dioxide microsphere powder, freeze-drying the powder for 6-8 hours, finally roasting the dried powder in a high-temperature furnace at 550 ℃ for 5 hours, removing a CTAB template, and obtaining the silica microsphere powder with the specific surface area of 420-430 m2Per g, pore volume of 0.2-0.25 cm3The mesoporous silica microspheres have the pore diameter of 1-4 nm.
Preparing a diaphragm:
1) firstly, mixing 40 parts of silicon dioxide mesoporous microspheres, 8 parts of aqueous binder, 0.5 part of dispersing agent, 0.5 part of thickening agent and 45 parts of water, carrying out ball milling, then adding 6 parts of aqueous binder, and continuing ball milling and dispersing to obtain silicon dioxide mesoporous microsphere slurry;
2) uniformly coating a PP microporous membrane with the porosity of 45% and the pore diameter of 0.5-1.5 mu m on a diaphragm substrate at a coating speed of 30m/min, baking at 70 ℃ for 2min, and drying to obtain a coating with the thickness of 2 mu m and the surface density of 14g/m2The lithium ion battery diaphragm with the mesoporous silica microsphere layer.
Preparing a positive plate:
lithium iron phosphate, 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 a vacuum condition after slitting, and welding the tabs to prepare the lithium ion battery 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 the lithium ion battery negative plate.
Preparing a lithium ion battery:
winding the positive plate, the diaphragm and the negative plate into a battery cell, wherein the diaphragm is positioned between the positive plate and the negative plate, the positive electrode is led out by aluminum tab spot welding, the negative electrode is led out by nickel tab spot welding, and the lithium plate is used as a counter electrode; then the cell is placed in an aluminum-plastic packaging bag, and electrolyte (1mol/L LiPF) is injected6EC and DMC are 1: 1), and the 2032 button lithium ion battery is prepared through the processes of packaging, formation, capacity and the like.
Example 2
The difference from example 1 is:
preparing a diaphragm:
1) mixing 30 parts of silicon dioxide mesoporous microspheres, 10 parts of aqueous binder, 1 part of dispersing agent, 1 part of thickening agent and 50 parts of water, performing ball milling, adding 8 parts of aqueous binder, and continuing ball milling and dispersing to obtain silicon dioxide mesoporous microsphere slurry;
2) uniformly coating mesoporous silica microsphere slurry on a diaphragm substrate at a coating speed of 20m/min by taking a PE microporous membrane with porosity of 42% and pore diameter of 0.5-1.5 mu m as the diaphragm substrate, baking for 3min at a temperature of 60 ℃, and drying to obtain a coating with thickness of 1 mu m and surface density of 12g/m2The lithium ion battery diaphragm with the mesoporous silica microsphere layer.
The rest is the same as embodiment 1, and the description is omitted here.
Example 3
The difference from example 1 is:
preparing a diaphragm:
1) firstly, mixing 50 parts of silicon dioxide mesoporous microspheres, 5 parts of aqueous binder, 0.3 part of dispersant, 0.2 part of thickener and 40 parts of water, carrying out ball milling, then adding 4.5 parts of aqueous binder, and continuing ball milling and dispersing to obtain silicon dioxide mesoporous microsphere slurry;
2) uniformly coating mesoporous silica microsphere slurry on a diaphragm substrate at a coating speed of 50m/min by taking a PE microporous membrane with porosity of 52% and pore diameter of 0.5-1.5 mu m as the diaphragm substrate, baking for 1min at a temperature of 80 ℃, and drying to obtain a coating with thickness of 3 mu m and surface density of 13g/m2The lithium ion battery diaphragm with the mesoporous silica microsphere layer.
The rest is the same as embodiment 1, and the description is omitted here.
Example 4
The difference from example 1 is:
preparing a diaphragm:
1) firstly, mixing 45 parts of silicon dioxide mesoporous microspheres, 10 parts of aqueous binder, 0.5 part of dispersing agent, 0.5 part of thickening agent and 40 parts of water, carrying out ball milling, adding 4 parts of aqueous binder, and continuing ball milling and dispersing to obtain silicon dioxide mesoporous microsphere slurry;
2) taking a PP microporous membrane with the porosity of 48% and the pore diameter of 0.5-1.5 mu m as a diaphragm substrate, uniformly coating mesoporous silica microsphere slurry on the diaphragm substrate at the coating speed of 45m/min, baking for 1min at the temperature of 75 ℃, and drying to obtain a coating with the thickness of 2 mu m and the surface density of 12g/m2The lithium ion battery diaphragm with the mesoporous silica microsphere layer.
The rest is the same as embodiment 1, and the description is omitted here.
Example 5
The difference from example 1 is:
preparing a diaphragm:
1) mixing 42 parts of silicon dioxide mesoporous microspheres, 5.5 parts of aqueous binder, 1 part of dispersing agent, 0.5 part of thickening agent and 45 parts of water, performing ball milling, adding 6 parts of aqueous binder, and continuing ball milling and dispersing to obtain silicon dioxide mesoporous microsphere slurry;
2) taking a PP microporous membrane with the porosity of 50% and the pore diameter of 0.5-1.5 mu m as a diaphragm substrate, uniformly coating mesoporous silica microsphere slurry on the diaphragm substrate at the coating speed of 35m/min, baking for 3min at the temperature of 60 ℃, and drying to obtain a coating with the thickness of 4 mu m and the surface density of 15g/m2The lithium ion battery diaphragm with the mesoporous silica microsphere layer.
The rest is the same as embodiment 1, and the description is omitted here.
Comparative example 1
Preparing a diaphragm:
the PP microporous membrane with the porosity of 45% and the pore diameter of 0.5-1.5 mu m is used as the diaphragm.
Preparing a positive plate:
lithium iron phosphate, 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 a vacuum condition after slitting, and welding the tabs to prepare the lithium ion battery 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 the lithium ion battery negative plate.
Preparing a lithium ion battery:
winding the positive plate, the diaphragm and the negative plate into a battery cell, wherein the diaphragm is positioned between the positive plate and the negative plate, the positive electrode is led out by aluminum tab spot welding, the negative electrode is led out by nickel tab spot welding, and the lithium plate is used as a counter electrode; then the cell is placed in an aluminum-plastic packaging bag, and electrolyte (1mol/L LiPF) is injected6，EC∶DMC＝1∶1)，The lithium ion battery is prepared by the procedures of packaging, formation, capacity and the like.
Comparative example 2
Preparing a diaphragm:
1) firstly, mixing 40 parts of ceramic particles, 8 parts of aqueous binder, 0.5 part of dispersant, 0.5 part of thickener and 45 parts of water, carrying out ball milling, then adding 6 parts of aqueous binder, and continuing ball milling and dispersing to obtain ceramic slurry;
2) uniformly coating a ceramic slurry on a diaphragm substrate at a coating speed of 30m/min by taking a PP (polypropylene) microporous membrane with the porosity of 45% and the pore diameter of 0.5-1.5 mu m as the diaphragm substrate, baking for 2min at the temperature of 70 ℃, and drying to obtain a coating with the thickness of 2 mu m and the surface density of 14g/m2The lithium ion battery diaphragm of the ceramic layer.
Preparing a positive plate:
lithium iron phosphate, 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 a vacuum condition after slitting, and welding the tabs to prepare the lithium ion battery 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 the lithium ion battery negative plate.
Preparing a lithium ion battery:
winding the positive plate, the diaphragm and the negative plate into a battery cell, wherein the diaphragm is positioned between the positive plate and the negative plate, the positive electrode is led out by aluminum tab spot welding, the negative electrode is led out by nickel tab spot welding, and the lithium plate is used as a counter electrode; then the cell is placed in an aluminum-plastic packaging bag, and electrolyte (1mol/L LiPF) is injected6EC and DMC are 1: 1), and are processed by the procedures of packaging, formation, capacity and the likeAnd preparing the lithium ion battery.
Performance testing
1) The mesoporous silica microspheres prepared in the invention are observed under a scanning electron microscope to obtain an SEM image shown in figure 1.
2) The mesoporous silica microspheres prepared in the invention are observed under a transmission electron microscope to obtain TEM images shown in figures 2-4.
3) Electrolyte LiPF (lithium ion particle Filter) measurement by using contact angle tester6Contact angle and liquid absorption rate with the separator in example 1 and comparative example 1, respectively.
4) The batteries of example 1 and comparative examples 1-2 were subjected to rate performance tests, as shown in fig. 4.
5) The cycle performance of the battery prepared in example 1 was measured after 200 cycles at 2C, as shown in fig. 5.
Analysis of test results
1) As can be seen from the SEM images of FIG. 1 and the TEM images of FIGS. 2 to 4, the mesoporous silica is spherical, and the specific surface area of the mesoporous silica microspheres is 420 to 430m2Per gram, pore volume 0.2-0.25 cm3The pore diameter is about 2nm, and compared with the traditional ceramic material, the mesoporous silica microsphere has the advantages of larger specific surface area, pore volume and pore diameter, thereby having better liquid absorption and retention capacity.
2) The test result shows that: the contact angle of the electrolyte on the surface of the PP diaphragm is 40.032 degrees, the contact angles of the electrolyte on the PP/mesoporous silica microsphere composite diaphragm approach to 0 degree, the liquid absorption rate of the PP diaphragm is 120 percent, and the liquid absorption rate of the PP/mesoporous silica microsphere composite diaphragm is 211 percent, which shows that the liquid retention capacity of the PP/mesoporous silica microsphere composite diaphragm is better than that of the PP diaphragm, and the mesoporous silica microspheres are more beneficial to the absorption and retention of the electrolyte. This is because the surface functional groups of the PP separator are less, the surface energy is lower, and the spreading of the electrolyte droplet on the surface is relatively large; the mesoporous silica microspheres have developed pore channel structures, meanwhile, the surfaces of the mesoporous silica microspheres contain rich hydroxyl groups, the spreading of electrolyte on the surfaces of the mesoporous silica microspheres is accelerated by the unique structures and surface properties, and almost instant liquid drops disappear.
3) As can be seen from FIG. 4, under the multiplying power of 0.5C-5C, the specific discharge capacity of the PP diaphragm, the PP/ceramic composite diaphragm and the PP/mesoporous silica microsphere composite diaphragm is not greatly different; along with the increase of the discharge rate, the discharge specific capacity of the PP diaphragm and the PP/mesoporous silica microsphere composite diaphragm is reduced, the capacity is reduced to 120mAh/g at 5C, and the capacity attenuation of the PP diaphragm and the PP/mesoporous silica microsphere composite diaphragm is accelerated at 8C. In addition, compared with a PP/mesoporous silica microsphere composite diaphragm, the PP/mesoporous silica microsphere composite diaphragm has better capacity attenuation at 0.5-8 ℃, which indicates that the PP/mesoporous silica microsphere composite diaphragm can better improve multiplying power performance, and the mesoporous silica microsphere can better improve ion conductivity.
5) As can be seen from fig. 5, the PP/mesoporous silica composite membrane is further subjected to a cycle performance test for 200 times at 2C, and as the cycle progresses, the battery capacity of the PP/mesoporous silica microsphere composite membrane is continuously attenuated, and the battery capacity of the PP/mesoporous silica microsphere composite membrane is reduced to 100mAh/g after 200 cycles, so that the capacity retention rate is high, which indicates that the mesoporous silica microsphere has good wettability with the electrolyte, thereby facilitating the absorption and maintenance of the electrolyte and maintaining the cycle stability of the lithium ion battery.
Variations and modifications to the above-described embodiments may become apparent to those skilled in the art to which the invention pertains based upon the disclosure and teachings of the above specification. 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 (6)
1. A mesoporous silica microsphere lithium ion battery diaphragm is characterized in that: comprises a diaphragm substrate and a mesoporous silica microsphere layer coated on at least one surface of the diaphragm substrate, wherein the mesoporous silica microsphere layer comprises mesoporesThe composite material comprises silica microspheres, an aqueous binder, a dispersing agent, a thickening agent and water, wherein the mass of the mesoporous silica microspheres accounts for 30-50% of the total mass of a mesoporous silica microsphere layer; the specific surface area of the mesoporous silica microspheres is 420-430 m2The pore volume of the mesoporous silica microspheres is 0.2-0.25 cm3The pore diameter of the mesoporous silica microspheres is 1-4 nm; synthesizing the mesoporous silica microspheres by a hydrothermal synthesis method by taking tetraethoxysilane as a silicon source, cetyl trimethyl ammonium bromide as a structural template agent, PVP as a dispersing agent and acetone as a solvent; the thickness of the mesoporous silica microsphere layer is 1-4 mu m; the surface density of the mesoporous silica microsphere layer is 12-15 g/m2。
2. The mesoporous silica microsphere lithium ion battery separator according to claim 1, wherein the preparation method of the mesoporous silica microsphere layer comprises the following steps: mixing 30-50 parts of silica mesoporous microspheres, 2-10 parts of aqueous binder, 0.3-1 part of dispersant, 0.2-1 part of thickener and 40-50 parts of water, ball-milling, adding 3-10 parts of aqueous binder, and continuing ball-milling and dispersing to obtain silica mesoporous microsphere slurry; and uniformly coating the mesoporous silica microsphere slurry on a diaphragm substrate, and drying to obtain the lithium ion battery diaphragm.
3. The mesoporous silica microsphere lithium ion battery separator according to claim 2, characterized in that: the coating speed is 20-50 m/min, the drying temperature is 60-80 ℃, and the drying time is 1-3 min.
4. The mesoporous silica microsphere lithium ion battery separator according to claim 1, characterized in that: the porosity of the diaphragm base material is 42-52%, and the aperture of the diaphragm base material is 0.5-1.5 μm.
5. The mesoporous silica microsphere lithium ion battery separator according to claim 1, characterized in that: the diaphragm substrate is a PP microporous film or a PE microporous film.
6. A lithium ion battery, characterized by: the lithium ion battery separator comprises the mesoporous silica microsphere lithium ion battery separator as claimed in any one of claims 1 to 5.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910575648.4A CN110416472B (en) | 2019-06-28 | 2019-06-28 | Mesoporous silica microsphere lithium ion battery diaphragm and lithium ion battery |
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| CN201910575648.4A CN110416472B (en) | 2019-06-28 | 2019-06-28 | Mesoporous silica microsphere lithium ion battery diaphragm and lithium ion battery |
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| CN110416472A CN110416472A (en) | 2019-11-05 |
| CN110416472B true CN110416472B (en) | 2022-06-10 |
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| CN115241598A (en) * | 2021-04-23 | 2022-10-25 | 四川大学 | Coating composite diaphragm and preparation method thereof |
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| CN115441123B (en) * | 2022-10-14 | 2024-03-08 | 贺州学院 | High-liquid-absorption and high-flame-retardance battery diaphragm and preparation method thereof |
| CN115483501A (en) * | 2022-11-01 | 2022-12-16 | 上海电气国轩新能源科技(南通)有限公司 | Sodium ion battery diaphragm preparation method and sodium ion battery |
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