CN113594628B - Nano-material-loaded aramid fiber coated battery diaphragm, preparation method and lithium-sulfur battery - Google Patents
Nano-material-loaded aramid fiber coated battery diaphragm, preparation method and lithium-sulfur battery Download PDFInfo
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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
- H01M50/411—Organic material
- H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
- H01M50/417—Polyolefins
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
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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
- H01M50/403—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
- H01M50/44—Fibrous material
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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
- H01M50/449—Separators, membranes or diaphragms characterised by the material having a layered structure
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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
- H01M50/489—Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
- H01M50/491—Porosity
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Abstract
The invention discloses a battery diaphragm coated with aramid fiber loaded with a nano material, which comprises a polyolefin porous diaphragm and an aramid fiber coating coated on one side of the polyolefin porous diaphragm, wherein the aramid fiber nanofiber of the aramid fiber coating is loaded with the nano material. The invention also discloses a preparation method of the diaphragm and a lithium-sulfur battery with the diaphragm. The aramid coating coated by the invention has good thermal stability and electrolyte affinity, and the loaded nano material can inhibit the shuttling of the high-grade lithium polysulfide chain and promote the interconversion of the high-grade lithium polysulfide chain; the preparation method adopted by the invention can ensure that the nano material is uniformly distributed and improve the specific surface area of the nano material. The diaphragm is assembled in the lithium-sulfur battery, so that the specific capacity and the cycling stability of the lithium-sulfur battery can be improved.
Description
Technical Field
The invention belongs to the technical field of battery diaphragms, and particularly relates to a nanomaterial-loaded aramid fiber coated battery diaphragm, a preparation method thereof and a lithium-sulfur battery.
Background
The conventional battery has gradually exited our sight because of problems of low capacity, low efficiency, environmental pollution, etc., and lithium ion batteries widely used in various electronic products also have problems such as low capacity, etc. In various new batteries, lithium sulfur is usedThe theoretical specific volume of the pool is up to 1675mAh g-1Theoretical energy density of 2600Wh kg-1[Journal of Materials Chemistry A,2017,5(7):3014-3038]In addition, the sulfur simple substance as the anode material is environment-friendly, cheap and abundant in storage. These advantages make it very promising for next generation electrochemical energy storage devices.
During the charging and discharging process of the lithium-sulfur battery, the sulfur simple substance S of the positive electrode8Can be sequentially converted into high-grade lithium polysulfide chain Li2Sx(6<x.ltoreq.8), and a lower lithium polysulfide Li2Sx(2<x is less than or equal to 6) to finally form insoluble and insulating lithium sulfide Li2And S. In this process, soluble higher lithium polysulfide chains can irreversibly diffuse toward the negative electrode of the battery, and eventually lead to loss of active material of the battery electrode, accumulation of insulating layers on the negative electrode, and capacity fade, affecting the practical application performance of the lithium sulfur battery.
The battery separator that is currently commercially more mature is a polyolefin porous separator such as: polypropylene microporous membrane, polyethylene microporous membrane or polypropylene/polyethylene/polypropylene three-layer composite membrane. Such commercial battery separators have a large pore size while allowing passage of lithium ions and soluble higher order lithium polysulfide chains without being able to confine the higher order lithium polysulfide chains on the positive electrode side.
As a high-performance polymer fiber easy to form a film, Aramid Nanofibers (ANFs) can be used for preparing composite slurry and coating the composite slurry on the surface of a polyolefin porous diaphragm to effectively limit the pore size of the diaphragm. For example, patent CN107359300A discloses a method for coating aramid composite slurry on a base film and preparing a lithium ion battery separator by steam preheating and hot air drying; patent CN111370625A discloses a method for coating a lithium ion battery separator with a slurry mixture of aramid fiber, a cosolvent, an oily auxiliary agent and a pore-forming agent. However, the aramid nano-fiber slurry is required to have a certain viscosity in the coating process, and the viscosity of the slurry is in a direct proportion relation with the proportion of the aramid polymer in the slurry, so that the existing coating method usually uses the aramid nano-fiber slurry with a high proportion (5% -13%) of the aramid polymer, and additional processes (steam, pore-forming agents and the like) are required to be added to avoid the phenomenon that the coating is too compact and the lithium ion migration rate is influenced. Furthermore, aramid nanofibers have smooth surfaces and lack reactive functional groups, which limits their functionality as battery separators.
Some polar inorganic materials, such as metal oxides, metal sulfides, metal carbides, metal nitrides, and the like, can prevent the dissolution and diffusion of the higher order lithium polysulfide chains by chemisorption of strong polarity, and are expected to provide a catalytic effect for the oxidation-reduction reaction of the higher order lithium polysulfide chains. Traditionally, coating methods for applying these materials to battery separator coatings include: the polar material coating is obtained by blade coating or vacuum filtration and other modes after the polar material coating and the adhesive are uniformly mixed. The former may cause extension or block of a migration path of lithium ions due to the presence of a large amount of binder components and a commonly occurring copolymerization problem, resulting in slow migration of lithium ions; the latter has the problems of over-thick coating, easy shedding of the coating and the like. Thus, there is a need to prepare aramid coated battery separators with the ability to absorb soluble higher lithium polysulfide chains or catalyze their conversion, as well as to devise coating methods that efficiently and stably support nanomaterials.
Disclosure of Invention
In view of one or more of the above drawbacks or needs for improvement in the prior art, the present invention provides a nanomaterial-loaded aramid coated battery separator, a method for preparing the same, and a lithium sulfur battery, wherein the loaded nanomaterial can provide an interaction force with a high-grade lithium polysulfide chain to inhibit shuttling of the high-grade lithium polysulfide chain, and can also promote conversion of the high-grade lithium polysulfide chain into a low-grade lithium sulfide insoluble substance through a catalytic effect, so as to reduce dissolution and shuttling of the high-grade lithium polysulfide chain during charging and discharging, thereby improving utilization rate and cycle stability of an active substance of the lithium sulfur battery.
In order to achieve the above object, according to one aspect of the present invention, there is provided a nanomaterial-loaded aramid fiber-coated battery separator comprising a polyolefin porous separator and an aramid fiber coating applied to one side thereof, wherein the aramid fiber nanofiber of the aramid fiber coating is loaded with a nanomaterial, and the aramid fiber nanofiber provides sites for in-situ growth of the nanomaterial.
As a further improvement of the invention, the polyolefin porous diaphragm is a polypropylene microporous diaphragm, a polyethylene microporous diaphragm or a polypropylene/polyethylene/polypropylene three-layer composite diaphragm; the nano material is one of ZnS, NiS, ZIF-8 or ZIF-67.
As a further improvement of the invention, the aramid nanofiber has the following para-chemical structure:
as a further improvement of the invention, the thickness of the aramid fiber coating is 1-4 μm.
According to a second aspect of the invention, a preparation method of a nanomaterial-loaded aramid fiber coated battery separator is provided, which is used for preparing the nanomaterial-loaded aramid fiber coated battery separator and comprises the following steps:
s1: adding potassium hydroxide, deionized water and an aramid polymer into dimethyl sulfoxide, stirring and dissolving at normal temperature, and dropwise adding absolute ethyl alcohol to prepare aramid nanofiber slurry;
s2: coating the aramid nano-fiber slurry obtained in the step S1 on the surface of the polyolefin porous diaphragm to obtain a coating film;
s3: respectively soaking the coating film obtained in the step S2 into a substitution solvent, a first precursor solution and a second precursor solution in sequence, and washing to obtain a coating film loaded with the nano material; the nano material is one of ZnS, NiS, ZIF-8 or ZIF-67;
s4: and (5) drying the coating film obtained in the step S3 in a vacuum oven to obtain the nano-material-loaded aramid fiber coating battery diaphragm.
As a further improvement of the invention, in step S1, the mass ratio of the components of the aramid nanofiber slurry is as follows: potassium hydroxide + aramid polymer: deionized water: dimethyl sulfoxide (1-4): 8: 220, wherein the ratio of potassium hydroxide: 3 of aramid polymer in mass ratio: 2; the stirring and dissolving time is preferably 3-5 h;
more preferably, in the step S1, the mass ratio of the absolute ethyl alcohol to the aramid polymer is (75-540): 4, and the dropping rate is 0.05ml/S to 0.1 ml/S.
And the addition sequence of the components in the step S1 is as follows: dissolving potassium hydroxide in deionized water under the assistance of stirring, adding the deionized water into dimethyl sulfoxide, and then adding an aramid polymer.
As a further improvement of the present invention, in step S2, the polyolefin porous membrane is one of a polypropylene microporous membrane, a polyethylene microporous membrane, or a polypropylene/polyethylene/polypropylene three-layer composite membrane.
As a further improvement of the invention, in step S2, specifically, a scraper is used to scrape the aramid nanofiber slurry on a diaphragm; the coating thickness of the aramid nano-fiber slurry is 30-120 mu m, the coating exists in a slurry form, the composite diaphragm is dried in step S4, and after the solvent is evaporated, the coating thickness is 1-4 mu m.
As a further improvement of the present invention, in step S3, the replacement solvent is one or more of ethanol, methanol, and deionized water; the first precursor and the second precursor are soluble inorganic matters and organic matters which react with each other in a solvent at normal temperature to generate nano particles, and the first precursor and the second precursor are determined according to the type of the nano material; the solvent is one or more of ethanol, methanol, deionized water and dimethylformamide.
As a further improvement of the present invention, in step S3, the soaking time in the substitution solvent is 3 to 15 min; the soaking time in the first precursor solution is 10-60 min; the soaking time in the second precursor solution is 3-60 min; more preferably, the washing times by using the absolute ethyl alcohol are at least 3 times, and each washing time is 3-5 min.
As a further improvement of the invention, in step S4, the drying time in the vacuum oven is 4-24 hours; the drying temperature is 60-100 ℃.
According to a third aspect of the invention, the lithium-sulfur battery is provided with the nano-material-loaded aramid fiber coated battery diaphragm, the lithium-sulfur battery is assembled according to the sequence of a positive electrode shell, a pole piece, the nano-material-loaded aramid fiber coated battery diaphragm dropwise added with electrolyte, a lithium piece, a steel sheet, a spring piece and a negative electrode shell, and the aramid fiber coating faces one side of the pole piece.
According to the invention, through the pretreatment of absolute ethyl alcohol, the aramid nano-fiber slurry with low aramid polymer content (0.17% -0.69%) has the capability of preparing a uniform coating, and the density of the fiber is controlled in a lower range without adding other processes; in the aspect of loading nano materials, the fiber structure of the aramid nano fibers which are mutually crosslinked provides excellent adhesion, and the nano materials generated in situ have the unique characteristics of large specific surface area, high porosity and adjustable particle size. The loaded nano material can provide interaction force with a high-grade lithium polysulfide chain to inhibit the shuttle of the high-grade lithium polysulfide chain, can promote the conversion of the high-grade lithium polysulfide chain to a low-grade lithium sulfide insoluble substance through a catalytic effect, and reduces the dissolution and shuttle of the high-grade lithium polysulfide chain in the charging and discharging process, so that the utilization rate and the cycling stability of an active substance of the lithium sulfur battery are improved.
In addition, compared with the method of synthesizing and further blending in a homogeneous solution, the method has the advantages that the nano material generated in situ in the state of hydrogel after blade coating has smaller particle size and better size uniformity, simultaneously the problem of easy copolymerization in the blending process is avoided, and the nano material has larger specific surface area in the processes of absorbing soluble high-grade lithium polysulfide chains or catalyzing the conversion of the soluble high-grade lithium polysulfide chains. The invention simultaneously achieves the purposes of improving the stability of the battery diaphragm coating and improving the specific capacitance and the cycle stability of the battery.
Generally, compared with the prior art, the technical scheme conceived by the invention has the following beneficial effects:
(1) the battery diaphragm coated with the aramid fiber loaded with the nano material comprises a polyolefin porous diaphragm and an aramid fiber coating coated on one side of a base film, wherein the aramid fiber nanofiber of the aramid fiber coating is loaded with the nano material. The aramid nano-fiber has excellent thermal stability and chemical stability, and the fiber structure cross-linked with each other in the coating provides excellent adhesion, film forming property and mechanical property. The nano material generated in situ has the unique characteristics of large specific surface area, high porosity and adjustable particle size.
(2) The battery diaphragm is coated with the nano-material-loaded aramid fiber, and the nano-material in-situ generation method endows the battery diaphragm with smaller particle size and better size uniformity, avoids the problem of copolymerization in the blending process, and has larger specific surface area in the aspects of absorbing soluble high-grade lithium polysulfide chains or catalyzing the conversion of the soluble high-grade lithium polysulfide chains.
(3) The battery diaphragm is coated with the nano-material-loaded aramid fiber, and the aramid fiber coating on one side of the diaphragm plays a remarkable physical barrier role in shuttling of a high-grade lithium polysulfide chain; the supported nano material can provide a large number of sites for adsorbing high-grade lithium polysulfide chains, the catalytic effect of metal ions can improve the utilization rate of active substance sulfur materials, and the conversion of the high-grade lithium polysulfide chains can be catalyzed through the activation of the interfaces between metal and electrolyte on the high-grade lithium polysulfide chains, especially the mutual conversion between long-chain compounds and short-chain compounds, so that the specific capacity retention rate and the coulombic efficiency of the battery can be improved.
(4) According to the preparation method of the battery diaphragm coated with the nano-material-loaded aramid fiber, the mass ratio of the aramid fiber nano-fiber to the nano-material is controllable, the thickness of the nano-material-loaded aramid fiber diaphragm coating is controllable, the particle size of the nano-material is controllable, and the preparation process of the diaphragm coating material is simple, so that the preparation method is more suitable for large-scale industrial production.
Drawings
FIG. 1 is a scanning electron microscope picture of an aramid coated battery separator according to an embodiment of the present invention;
FIG. 2 is a scanning electron microscope picture of a ZIF-67 loaded aramid coated battery separator of an embodiment of the invention;
fig. 3 is an EIS curve for the assembled battery of unmodified polyethylene microporous separator (PE) of comparative example 2, aramid coated battery separator (ANFs/PE) of comparative example 1, and aramid coated battery separator loaded with ZIF-67 (ANFs @ ZIF-67/PE), for fig. 3(a) before three battery charge-discharge cycles and fig. 3(b) after 100 cycles. The three curves in fig. 3(a) and 3(b) are, from top to bottom, a polyethylene microporous membrane (PE), an aramid coated battery membrane (ANFs/PE), and a ZIF-67 loaded aramid coated battery membrane (ANFs @ ZIF-67/PE) in that order.
Fig. 4 is a graph of the cycling performance at 0.5C for three groups of cells assembled from unmodified polyethylene microporous separator (PE) of comparative example 2, aramid coated battery separator (ANFs/PE) of comparative example 1, and aramid coated battery separator loaded with ZIF-67 (ANFs @ ZIF-67/PE). Three curves in the figure are an aramid fiber coated battery diaphragm (ANFs @ ZIF-67/PE) loaded with ZIF-67, an aramid fiber coated battery diaphragm (ANFs/PE) and a polyethylene microporous diaphragm (PE) from top to bottom in sequence.
FIG. 5 is a charge and discharge curve at 0.5C for a battery assembled from ZIF-67 loaded aramid coated battery separator (ANFs @ ZIF-67/PE).
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
The nano-material-loaded aramid fiber coating battery diaphragm provided by the invention comprises a polyolefin porous diaphragm and an aramid fiber coating coated on one side of a base film (the polyolefin porous diaphragm), wherein the nano-material is loaded on aramid fiber nano-fibers of the aramid fiber coating.
In the ANFs/PE and ANFs @ ZIF-67/PE, the '/' indicates the coating of the aramid fiber on the polyolefin membrane, and the '@' indicates the composite hybridization of the aramid fiber nanofiber and the nano material ZIF-67.
The type and size of the polyolefin porous membrane are the same as those of commercially available polyolefin porous membranes, and the polyolefin porous membrane can be obtained commercially or prepared by itself according to the method of the prior art, and is not particularly limited herein. In a preferred embodiment, the polyolefin porous membrane is a polypropylene microporous membrane, a polyethylene microporous membrane or a polypropylene/polyethylene/polypropylene three-layer composite membrane.
Further preferably, the thickness of the aramid fiber coating layer supporting the nanomaterial is 1 μm to 4 μm.
The preparation method of the battery diaphragm coated with the nano-material-loaded aramid fiber comprises the following steps:
(1) adding potassium hydroxide, deionized water and an aramid polymer into dimethyl sulfoxide, stirring and dissolving at normal temperature, and dropwise adding absolute ethyl alcohol to prepare aramid nanofiber slurry;
(2) coating the aramid nano-fiber slurry obtained in the step (1) on the surface of a polyolefin porous diaphragm to prepare a coating film;
(3) respectively soaking the coating film obtained in the step (2) into a substitution solvent, a first precursor solution and a second precursor solution in sequence, and washing to obtain a coating film loaded with a nano material;
(4) and (4) drying the coating film loaded with the nano material obtained in the step (3) in a vacuum oven to obtain the nano material loaded aramid fiber coating battery diaphragm.
The aramid nano-fiber slurry prepared in the step (1) comprises the following components in percentage by mass: potassium hydroxide + aramid polymer: deionized water: dimethyl sulfoxide (1-4): 8: 220, and potassium hydroxide: 3 of aramid polymer in mass ratio: 2; the stirring and dissolving time is preferably 3-5 h; the mass ratio of the absolute ethyl alcohol to the aramid polymer is (75-540): 4, and the dropping rate of the absolute ethyl alcohol is 0.05 ml/s-0.1 ml/s; in addition, the adding sequence of the components in the step (1) is as follows: dissolving potassium hydroxide in deionized water under the assistance of stirring, adding the deionized water into dimethyl sulfoxide, and then adding an aramid polymer.
In some embodiments, the polyolefin porous membrane of step (2) is a polypropylene microporous membrane, a polyethylene microporous membrane, or a polypropylene/polyethylene/polypropylene three-layer composite membrane.
In some embodiments, the coating operation in the step (2) is specifically to scrape the aramid nanofiber slurry on the diaphragm by using a scraper, and the thickness of the coating slurry can be controlled by adjusting the type of the scraper; the coating thickness of the aramid nano-fiber slurry is 30-120 mu m.
In some embodiments, the displacement solvent in step (3) is one or more of ethanol, methanol, and deionized water; the first precursor and the second precursor are soluble inorganic matters and organic matters which react with each other in a solvent at normal temperature to generate nano particles, and the solvent is one or more of ethanol, methanol, deionized water and dimethylformamide; the nanomaterial includes, but is not limited to, one of ZnS, NiS, ZIF-8 or ZIF-67.
The first precursor and the second precursor are specifically determined according to the kind of the nanomaterial. Taking nano materials such as ZnS, NiS, ZIF-8 or ZIF-67 as an example, a first precursor for generating ZnS nano particles is zinc sulfate, zinc nitrate or the like, and a second precursor is sodium sulfide; the first precursor for generating the NiS nano particles is nickel sulfate, and the second precursor is sodium sulfide; the first precursor to ZIF-8 is zinc nitrate hexahydrate, the second precursor is 2-methylimidazole; the first precursor to form ZIF-67 was cobalt nitrate hexahydrate, and the second precursor was 2-methylimidazole. The concentrations of the first precursor solution and the second precursor solution are preferably 0.10mol/l to 1 mol/l.
In some embodiments, the soaking time in the displacement solvent in the step (3) is 3-15 min; the soaking time in the first precursor solution is 10-60 min; the soaking time in the second precursor solution is 3-60 min; the washing times of absolute ethyl alcohol are at least 3 times, and each washing time is 3-5 min.
In some embodiments, the drying time in the vacuum oven in the step (4) is 4-24 hours; the drying temperature is 60-100 ℃.
The invention also provides a lithium-sulfur battery, which is assembled by coating the aramid fiber loaded with the nano material on a battery diaphragm, and the battery is assembled according to the sequence of coating the aramid fiber loaded with the nano material on a battery diaphragm, a lithium sheet, a steel sheet, an elastic sheet and a negative electrode shell of a positive electrode shell, a pole piece and (dropwise added with electrolyte). In the lithium-sulfur battery, the aramid coating on one side of the diaphragm faces one side of the pole piece.
The nano-material-loaded aramid fiber coated battery diaphragm provided by the invention comprises a polyolefin porous diaphragm, an aramid fiber coating coated on one side of a base film and a nano material loaded by aramid fiber nano-fibers. In some embodiments, the aramid nanofiber slurry is coated on one side of the polyolefin porous membrane, and is soaked in the substitution solvent, the first precursor solution and the second precursor solution in sequence, and the composite membrane for the lithium-sulfur battery is prepared after washing and drying. The polyolefin porous diaphragm used in the invention is a polypropylene microporous diaphragm, a polyethylene microporous diaphragm or a polypropylene/polyethylene/polypropylene composite film. According to the invention, through improving the key composition and structure of the nano-material loaded aramid fiber coated battery diaphragm, the whole flow process design of the preparation method and the conditions and parameters of each step, the finally formed nano-material loaded aramid fiber coated battery diaphragm can obviously improve the utilization rate and the cycling stability of active substances of the lithium-sulfur battery.
In order to make the technical personnel in the field understand the invention better, the aramid fiber coating battery diaphragm loaded with nano materials, the preparation method and the lithium sulfur battery with the diaphragm are explained in detail in the following by combining specific examples.
Example 1
The nano-material-loaded aramid fiber coated battery diaphragm comprises a polyolefin porous diaphragm, an aramid fiber coating coated on one side of a base film and a ZnS nano-material loaded by aramid fiber nano-fibers of the aramid fiber coating. Coating the aramid nano-fiber slurry on one side of a polyolefin porous diaphragm, soaking the polyolefin porous diaphragm in deionized water, a zinc salt solution and a sulfide solution in sequence, washing and drying to prepare the composite diaphragm for the lithium-sulfur battery. The aramid nano-fiber slurry comprises the following components in percentage by weight: potassium hydroxide: 0.09 g; deionized water: 1.2 g; aramid polymer: 0.06 g; dimethyl sulfoxide: 33g of a mixture; the mass of the absolute ethyl alcohol is as follows: 4.5g, the dropping speed is 0.05 ml/s; the polyolefin porous diaphragm is a polyethylene microporous diaphragm; the thickness of the coating slurry is 30 μm; the zinc salt is zinc sulfate; the sulfide salt is sodium sulfide; the solvent is deionized water; the concentration of the zinc salt solution is 1 mol/l; the concentration of the sulfide salt solution was 1 mol/l.
The preparation method of the battery diaphragm coated with the nano-material-loaded aramid fiber comprises the following steps:
(1) dissolving 0.09g of potassium hydroxide in 1.2g of deionized water under the stirring assistance, adding into 33g of dimethyl sulfoxide, then adding 0.06g of aramid polymer, continuously stirring for 4 hours for complete dissolution, and dropwise adding 4.5g of absolute ethyl alcohol at the speed of 0.05ml/s to prepare the aramid nanofiber slurry.
(2) Coating the aramid nano-fiber slurry obtained in the step (1) on the surface of a polyethylene porous diaphragm by using a 30-micron scraper to obtain a coating film;
(3) dissolving 8.07g of zinc sulfate in 50ml of deionized water under the assistance of ultrasound to prepare a zinc salt solution; dissolving 3.90g of sodium sulfide in 50ml of deionized water to prepare a sulfide solution;
(4) and (3) respectively soaking the coating film obtained in the step (2) into deionized water, the zinc salt solution obtained in the step (3) and a sulfide salt solution in sequence for the following time: 3min, 10min and 3 min; washing with absolute ethyl alcohol for three times, wherein the washing time is 3min each time, and obtaining a ZnS-loaded coating film;
(5) and (5) drying the coated film loaded with ZnS obtained in the step (4) in a vacuum oven for 4h at the drying temperature of 60 ℃ to obtain the ZnS-loaded aramid coated battery diaphragm.
And (4) applying the ZnS-loaded aramid coated battery diaphragm obtained in the step (5) to a lithium-sulfur battery.
Example 2
The nano-material-loaded aramid fiber coated battery diaphragm comprises a polyolefin porous diaphragm, an aramid fiber coating coated on one side of a base film and a ZnS nano-material loaded by aramid fiber nano-fibers of the aramid fiber coating. Coating aramid nano-fiber slurry on one side of a polyolefin porous diaphragm, soaking in deionized water, a zinc salt solution and a sulfide salt solution in sequence, washing and drying to prepare the composite diaphragm for the lithium-sulfur battery. The aramid nano-fiber slurry comprises the following components in percentage by weight: potassium hydroxide: 0.18 g; deionized water: 1.2 g; aramid polymer: 0.12 g; dimethyl sulfoxide: 33g of a mixture; the mass of the absolute ethyl alcohol is as follows: 8.1g, the dropping speed is 0.05 ml/s; the polyolefin porous diaphragm is a polyethylene microporous diaphragm; the thickness of the coating slurry is 120 mu m; the zinc salt is zinc sulfate; the sulfide salt is sodium sulfide; the solvent is deionized water; the concentration of the zinc salt solution is 1 mol/l; the concentration of the sulfide solution was 1 mol/l.
The preparation method of the battery diaphragm coated with the nano-material-loaded aramid fiber comprises the following steps:
(1) dissolving 0.18g of potassium hydroxide in 1.2g of deionized water under the stirring assistance, adding into 33g of dimethyl sulfoxide, then adding 0.12g of aramid polymer, continuously stirring for 4 hours for complete dissolution, and dropwise adding 8.1g of absolute ethyl alcohol at the speed of 0.05ml/s to prepare the aramid nanofiber slurry.
(2) Coating the aramid nano-fiber slurry obtained in the step (1) on the surface of a polyethylene porous diaphragm by using a 120-micron scraper to obtain a coating film;
(3) dissolving 8.07g of zinc sulfate in 50ml of deionized water under the assistance of ultrasound to prepare a zinc salt solution; dissolving 3.90g of sodium sulfide in 50ml of deionized water to prepare a sulfide solution;
(4) and (3) respectively soaking the coating film obtained in the step (2) into deionized water, the zinc salt solution obtained in the step (3) and a sulfide salt solution in sequence for the following time: 15min, 60min and 60 min; washing with absolute ethyl alcohol for three times, wherein the washing time is 5min each time, and obtaining a ZnS-loaded coating film;
(5) and (5) drying the coated film loaded with ZnS obtained in the step (4) in a vacuum oven for 24h at the drying temperature of 100 ℃ to obtain the ZnS-loaded aramid coated battery diaphragm.
And (4) applying the ZnS-loaded aramid coated battery diaphragm obtained in the step (5) to a lithium-sulfur battery.
Example 3
The nano-material-loaded aramid fiber coated battery diaphragm comprises a polyolefin porous diaphragm, an aramid fiber coating coated on one side of a base film and a NiS nano-material loaded by aramid fiber nano-fibers of the aramid fiber coating. The aramid nano-fiber slurry is coated on one side of a polyolefin porous diaphragm, and the polyolefin porous diaphragm is soaked in deionized water, a nickel salt solution and a sulfide salt solution in sequence, washed and dried to prepare the composite diaphragm for the lithium-sulfur battery. The aramid nano-fiber slurry comprises the following components in percentage by weight: potassium hydroxide: 0.27 g; deionized water: 1.2 g; aramid polymer: 0.18 g; dimethyl sulfoxide: 33g of a mixture; the mass of the absolute ethyl alcohol is as follows: 4.5g, the dropping speed is 0.05 ml/s; the polyolefin porous diaphragm is a polyethylene microporous diaphragm; the thickness of the coating slurry was 30 μm; the nickel salt is nickel sulfate; the sulfide salt is sodium sulfide; the solvent is deionized water; the concentration of the nickel salt solution is 1 mol/l; the concentration of the sulfide solution was 1 mol/l.
The preparation method of the battery diaphragm coated with the nano-material-loaded aramid fiber comprises the following steps:
(1) dissolving 0.27g of potassium hydroxide in 1.2g of deionized water under the stirring assistance, adding into 33g of dimethyl sulfoxide, then adding 0.18g of aramid polymer, continuously stirring for 4 hours for complete dissolution, and dropwise adding 4.5g of absolute ethyl alcohol at the speed of 0.05ml/s to prepare the aramid nanofiber slurry.
(2) Coating the aramid nano-fiber slurry obtained in the step (1) on the surface of a polyethylene porous diaphragm by using a 30-micron scraper to obtain a coating film;
(3) dissolving 13.14g of nickel sulfate in 50ml of deionized water under the assistance of ultrasound to prepare a nickel salt solution; dissolving 3.90g of sodium sulfide in 50ml of deionized water to prepare a sulfide solution;
(4) and (3) respectively soaking the coating film obtained in the step (2) into deionized water, the nickel salt solution obtained in the step (3) and a sulfide salt solution in sequence for the following time: 12min, 30min and 20 min; washing with absolute ethyl alcohol for three times, wherein the washing time is 3min each time, and obtaining a coating film loaded with NiS;
(5) and (5) drying the coating film loaded with NiS obtained in the step (4) in a vacuum oven for 4h at the drying temperature of 60 ℃ to obtain the NiS-loaded aramid fiber coated battery diaphragm.
And (4) applying the NiS-loaded aramid fiber coated battery diaphragm obtained in the step (5) to a lithium-sulfur battery.
Example 4
The nano-material-loaded aramid fiber coated battery diaphragm comprises a polyolefin porous diaphragm, an aramid fiber coating coated on one side of a base film and a NiS nano-material loaded by aramid fiber nano-fibers of the aramid fiber coating. The aramid nano-fiber slurry is coated on one side of a polyolefin porous diaphragm, and the polyolefin porous diaphragm is soaked in deionized water, a nickel salt solution and a sulfide salt solution in sequence, washed and dried to prepare the composite diaphragm for the lithium-sulfur battery. The aramid nano-fiber slurry comprises the following components in percentage by weight: potassium hydroxide: 0.36 g; deionized water: 1.2 g; aramid polymer: 0.24 g; dimethyl sulfoxide: 33g of a mixture; the mass of the absolute ethyl alcohol is as follows: 8.1g, the dropping speed is 0.05 ml/s; the polyolefin porous diaphragm is a polyethylene microporous diaphragm; the thickness of the coating slurry is 120 mu m; the nickel salt is nickel sulfate; the sulfide salt is sodium sulfide; the solvent is deionized water; the concentration of the nickel salt solution is 1 mol/l; the concentration of the sulfide salt solution was 1 mol/l.
The preparation method of the battery diaphragm coated with the nano-material-loaded aramid fiber comprises the following steps:
(1) dissolving 0.36g of potassium hydroxide in 1.2g of deionized water under the stirring assistance, adding into 33g of dimethyl sulfoxide, then adding 0.24g of aramid polymer, continuously stirring for 4 hours for complete dissolution, and dropwise adding 8.1g of absolute ethyl alcohol at the speed of 0.05ml/s to prepare the aramid nanofiber slurry.
(2) Coating the aramid nano-fiber slurry obtained in the step (1) on the surface of a polyethylene porous diaphragm by using a 120-micron scraper to obtain a coating film;
(3) dissolving 13.14g of nickel sulfate in 50ml of deionized water under the assistance of ultrasonic waves to prepare a nickel salt solution; dissolving 3.90g of sodium sulfide in 50ml of deionized water to prepare a sulfide solution;
(4) and (3) respectively soaking the coating film obtained in the step (2) into deionized water, the nickel salt solution obtained in the step (3) and a sulfide salt solution in sequence for the following time: 8min, 35min and 45 min; washing with absolute ethyl alcohol for three times, wherein the washing time is 5min each time, and obtaining a NiS-loaded coating film;
(5) and (5) drying the coating film loaded with the NiS obtained in the step (4) in a vacuum oven for 24 hours at the drying temperature of 100 ℃ to obtain the NiS-loaded aramid fiber coated battery diaphragm.
And (4) applying the NiS-loaded aramid fiber coated battery diaphragm obtained in the step (5) to a lithium-sulfur battery.
Example 5
The aramid fiber coated battery diaphragm loading the nano material comprises a polyolefin porous diaphragm, an aramid fiber coating coated on one side of a base film and a ZIF-8 nano material loaded by aramid fiber nano fibers of the aramid fiber coating. Coating the aramid nano-fiber slurry on one side of a polyolefin porous diaphragm, soaking the polyolefin porous diaphragm in absolute methanol, a zinc salt solution and a ligand solution in sequence, washing and drying to prepare the composite diaphragm for the lithium-sulfur battery. The aramid nano-fiber slurry comprises the following components in percentage by weight: potassium hydroxide: 0.09 g; deionized water: 1.2 g; aramid polymer: 0.06 g; dimethyl sulfoxide: 33 g; the volume of the absolute ethyl alcohol is as follows: 4.5g, the dropping speed is 0.05 ml/s; the polyolefin porous diaphragm is a polyethylene microporous diaphragm; the thickness of the coating slurry is 30 μm; the zinc salt is zinc nitrate hexahydrate; the ligand is 2-methylimidazole; the solvent is absolute methanol; the concentration of the zinc salt solution is 0.10 mol/l; the concentration of the ligand solution was 0.80 mol/l.
The preparation method of the battery diaphragm coated with the nano-material-loaded aramid fiber comprises the following steps:
(1) dissolving 0.09g of potassium hydroxide in 1.2g of deionized water under the stirring assistance, adding into 33g of dimethyl sulfoxide, then adding 0.06g of aramid polymer, continuously stirring for 4 hours for complete dissolution, and dropwise adding 8.1g of absolute ethyl alcohol at the speed of 0.05ml/s to prepare the aramid nanofiber slurry.
(2) Coating the aramid nano-fiber slurry obtained in the step (1) on the surface of a polyethylene porous diaphragm by using a 30-micron scraper to prepare a coating film;
(3) dissolving 1.50g of zinc nitrate hexahydrate in 50ml of anhydrous methanol under the assistance of ultrasound to prepare a zinc salt solution; dissolving 2-methylimidazole 3.29g in anhydrous methanol 50ml to prepare a ligand solution;
(4) and (3) respectively soaking the coating film obtained in the step (2) into anhydrous methanol, the zinc salt solution obtained in the step (3) and a ligand solution in sequence for the following time: 3min, 10min and 3 min; washing with absolute ethyl alcohol for three times, wherein the washing time is 3min each time, and obtaining a coating film loaded with ZIF-8;
(5) and (4) drying the coated film loaded with the ZIF-8 obtained in the step (4) in a vacuum oven for 4h at the drying temperature of 60 ℃ to obtain the aramid fiber coated battery diaphragm loaded with the ZIF-8.
And (4) applying the ZIF-8-loaded aramid fiber coated battery diaphragm obtained in the step (5) to a lithium-sulfur battery.
Example 6
The aramid fiber coated battery diaphragm loading the nano material comprises a polyolefin porous diaphragm, an aramid fiber coating coated on one side of a base film and a ZIF-8 nano material loaded by aramid fiber nano fibers of the aramid fiber coating. Coating the aramid nano-fiber slurry on one side of a polyolefin porous diaphragm, soaking in absolute methanol, a zinc salt solution and a ligand solution in sequence, washing and drying to prepare the composite diaphragm for the lithium-sulfur battery. The aramid nano-fiber slurry comprises the following components in percentage by weight: potassium hydroxide: 0.36 g; deionized water: 1.2 g; aramid polymer: 0.24 g; dimethyl sulfoxide: 33g of a mixture; the mass of the absolute ethyl alcohol is as follows: 8.1g, the dropping speed is 0.05 ml/s; the polyolefin porous diaphragm is a polyethylene microporous diaphragm; the thickness of the coating slurry is 120 mu m; the zinc salt is zinc nitrate hexahydrate; the ligand is 2-methylimidazole; the solvent is absolute methanol; the concentration of the zinc salt solution is 0.10 mol/l; the concentration of the ligand solution was 0.80 mol/l.
The preparation method of the battery diaphragm coated with the nano-material-loaded aramid fiber comprises the following steps:
(1) dissolving 0.36g of potassium hydroxide in 1.2g of deionized water under the assistance of stirring, adding the solution into 33g of dimethyl sulfoxide, adding 0.24g of aramid polymer, continuously stirring for 4 hours to completely dissolve, and dropwise adding 4.5g of absolute ethyl alcohol at the rate of 0.05ml/s to prepare the aramid nanofiber slurry.
(2) Coating the aramid nano-fiber slurry obtained in the step (1) on the surface of a polyethylene porous diaphragm by using a 120-micron scraper to obtain a coating film;
(3) dissolving 1.50g of zinc nitrate hexahydrate in 50ml of anhydrous methanol under the assistance of ultrasound to prepare a zinc salt solution; dissolving 2-methylimidazole 3.29g in 50ml of anhydrous methanol to prepare a ligand solution;
(4) and (3) respectively soaking the coating film obtained in the step (2) into anhydrous methanol, the zinc salt solution obtained in the step (3) and a ligand solution in sequence for the following time: 5min, 40min and 50 min; washing with absolute ethyl alcohol for three times, wherein the washing time is 5min each time, and obtaining a coating film loaded with ZIF-8;
(5) and (5) drying the coated film loaded with the ZIF-8 obtained in the step (4) in a vacuum oven for 24 hours at the drying temperature of 100 ℃ to obtain the aramid fiber coated battery diaphragm loaded with the ZIF-8.
And (4) applying the ZIF-8 loaded aramid fiber coated battery diaphragm obtained in the step (5) to a lithium-sulfur battery.
Example 7
The aramid fiber coated battery diaphragm loaded with the nano material comprises a polyolefin porous diaphragm, an aramid fiber coating coated on one side of a base film and a ZIF-67 nano material loaded with aramid fiber nano fibers of the aramid fiber coating. The aramid nano-fiber slurry is coated on one side of a polyolefin porous diaphragm, and the diaphragm is soaked in absolute ethyl alcohol, a cobalt salt solution and a ligand solution in sequence, washed and dried to prepare the composite diaphragm for the lithium-sulfur battery. The aramid nano-fiber slurry comprises the following components in percentage by weight: potassium hydroxide: 0.09 g; deionized water: 1.2 g; aramid polymer: 0.06 g; dimethyl sulfoxide: 33 g; the mass of the absolute ethyl alcohol is as follows: 4.5g, the dropping speed is 0.05 ml/s; the polyolefin porous diaphragm is a polyethylene microporous diaphragm; the thickness of the coating slurry is 30 μm; the cobalt salt is cobalt nitrate hexahydrate; the ligand is 2-methylimidazole; the solvent is absolute ethyl alcohol; the concentration of the cobalt salt solution is 0.10 mol/l; the concentration of the ligand solution was 0.80 mol/l.
The preparation method of the battery diaphragm coated with the nano-material-loaded aramid fiber comprises the following steps:
(1) dissolving 0.09g of potassium hydroxide in 1.2g of deionized water under the assistance of stirring, adding the deionized water into 33g of dimethyl sulfoxide, then adding 0.06g of aramid polymer, continuously stirring for 4 hours to completely dissolve, and dropwise adding 4.5g of absolute ethyl alcohol at the rate of 0.05ml/s to prepare the aramid nanofiber slurry.
(2) Coating the aramid nano-fiber slurry obtained in the step (1) on the surface of a polyethylene porous diaphragm by using a 30-micron scraper to obtain a coating film;
(3) dissolving 1.46g of cobalt nitrate hexahydrate in 50ml of absolute ethyl alcohol under the assistance of ultrasound to prepare a cobalt salt solution; dissolving 2-methylimidazole 3.29g in 50ml of absolute ethyl alcohol to prepare a ligand solution;
(4) and (3) respectively soaking the coating film obtained in the step (2) into absolute ethyl alcohol, the cobalt salt solution obtained in the step (3) and the ligand solution in sequence for the following time: 10min, 20min and 30 min; washing with absolute ethyl alcohol for three times, wherein the washing time is 3min each time, and obtaining a coating film loaded with ZIF-67;
(5) and (5) drying the coated film loaded with the ZIF-67 obtained in the step (4) in a vacuum oven for 4 hours at the drying temperature of 60 ℃ to obtain the aramid fiber coated battery diaphragm loaded with the ZIF-67.
And (4) applying the aramid fiber coated battery diaphragm loaded with the ZIF-67 obtained in the step (5) to a lithium-sulfur battery.
Example 8
The aramid fiber coated battery diaphragm loaded with the nano material comprises a polyolefin porous diaphragm, an aramid fiber coating coated on one side of a base film and a ZIF-67 nano material loaded with aramid fiber nano fibers of the aramid fiber coating. Coating the aramid nano-fiber slurry on one side of a polyolefin porous diaphragm, soaking the polyolefin porous diaphragm in absolute ethyl alcohol, a cobalt salt solution and a ligand solution in sequence, washing and drying to prepare the composite diaphragm for the lithium-sulfur battery. The aramid nano-fiber slurry comprises the following components in percentage by weight: potassium hydroxide: 0.36 g; deionized water: 1.2 g; aramid polymer: 0.24 g; dimethyl sulfoxide: 33g of a mixture; the volume of the absolute ethyl alcohol is as follows: 8.1g, the dropping speed is 0.05 ml/s; the polyolefin porous diaphragm is a polyethylene microporous diaphragm; the thickness of the coating slurry is 120 mu m; the cobalt salt is cobalt nitrate hexahydrate; the ligand is 2-methylimidazole; the solvent is absolute ethyl alcohol; the concentration of the cobalt salt solution is 0.10 mol/l; the concentration of the ligand solution was 0.80 mol/l.
The preparation method of the battery diaphragm coated with the nano-material-loaded aramid fiber comprises the following steps:
(1) dissolving 0.36g of potassium hydroxide in 1.2g of deionized water under the assistance of stirring, adding the solution into 33g of dimethyl sulfoxide, adding 0.24g of aramid polymer, continuously stirring for 4 hours to completely dissolve, and dropwise adding 8.1g of absolute ethyl alcohol at the rate of 0.05ml/s to prepare the aramid nanofiber slurry.
(2) Coating the aramid nano-fiber slurry obtained in the step (1) on the surface of a polyethylene porous diaphragm by using a 120-micron scraper to obtain a coating film;
(3) dissolving 1.46g of cobalt nitrate hexahydrate in 50ml of absolute ethyl alcohol under the assistance of ultrasound to prepare a cobalt salt solution; dissolving 2-methylimidazole 3.29g in 50ml of absolute ethyl alcohol to prepare a ligand solution;
(4) and (3) respectively soaking the coating film obtained in the step (2) into absolute ethyl alcohol, the cobalt salt solution obtained in the step (3) and the ligand solution in sequence for the following time: 7min, 30min and 40 min; washing with absolute ethyl alcohol for three times, wherein the washing time is 5min each time, and obtaining a coating film loaded with ZIF-67;
(5) and (4) drying the coated film loaded with the ZIF-67 obtained in the step (4) in a vacuum oven for 24 hours at the drying temperature of 100 ℃ to obtain the aramid fiber coated battery diaphragm loaded with the ZIF-67.
And (4) applying the ZIF-67-loaded aramid fiber coated battery diaphragm obtained in the step (5) to a lithium-sulfur battery.
Comparative example 1
Coating aramid nano-fiber slurry on one side of a polyolefin porous diaphragm, soaking in absolute ethyl alcohol, washing and drying. The aramid nano-fiber slurry comprises the following components in percentage by weight: potassium hydroxide: 0.09 g; deionized water: 1.2 g; aramid polymer: 0.06 g; dimethyl sulfoxide: 33g of a mixture; the polyolefin porous diaphragm is a polyethylene microporous diaphragm; the thickness of the coating slurry was 30 μm;
the preparation method of the aramid fiber coated battery separator in the comparative example comprises the following steps:
(1) dissolving 0.09g of potassium hydroxide in 1.2g of deionized water under the assistance of stirring, adding the deionized water into 33g of dimethyl sulfoxide, then adding 0.06g of aramid polymer, continuously stirring for 4 hours to completely dissolve, and dropwise adding 4.5g of absolute ethyl alcohol at the rate of 0.05ml/s to prepare the aramid nanofiber slurry.
(2) Coating the aramid nano-fiber slurry obtained in the step (1) on the surface of a polyethylene porous diaphragm by using a 30-micron scraper to obtain a coating film;
(3) soaking the coating film obtained in the step (2) into absolute ethyl alcohol for 3 min; washing with absolute ethyl alcohol for three times, wherein the washing time is 3min each time, so as to obtain a coating film of the aramid nanofibers;
(4) and (4) drying the aramid nano-fiber coating film obtained in the step (3) in a vacuum oven for 4 hours at the drying temperature of 60 ℃ to obtain the aramid coating battery diaphragm.
And (4) applying the aramid fiber coated battery diaphragm obtained in the step (4) to a lithium-sulfur battery.
Comparative example 2
Unmodified polyethylene microporous membranes. The unmodified polyethylene microporous separator was applied to a lithium sulfur battery.
By analyzing scanning electron microscope pictures of the aramid fiber coated battery diaphragm (figure 1) and the aramid fiber coated battery diaphragm (figure 2) loaded with the ZIF-67, the aramid fiber nano-particles are uniformly coated, the surface of the aramid fiber nano-particles presents the appearance of integrally crosslinked fibers, and after the aramid fiber nano-particles are soaked in a cobalt salt solution and a 2-methylimidazole solution in sequence, the crosslinked fiber surfaces form the ZIF-67 nano-particles with uniform particles and clear appearance. The liquid absorption property and surface groups of the aramid nano-fiber can obviously improve the affinity of the battery diaphragm and electrolyte; and the micro-porous structure of the ZIF-67 nano-particles and the surface groups thereof further improve the lyophilic rate of the coating and are beneficial to the transfer of lithium ions.
The EIS curves of the unmodified polyethylene microporous membrane (PE) in the comparative example 2, the aramid coated battery membrane (ANFs @ ZIF-67/PE) in the comparative example 1 and the aramid coated battery membrane (ANFs @ ZIF-67/PE) loaded with ZIF-67 in the example 7 in the three groups of batteries before the charge-discharge cycle and in the figure 3(a) after the charge-discharge cycle is 100 circles show that the impedance of the battery assembled by the aramid coated battery membrane (ANFs @ ZIF-67/PE) loaded with ZIF-67 is the smallest before and after the charge-discharge cycle is 100 circles.
Fig. 4 is a battery assembled from unmodified polyethylene microporous separator (PE) of comparative example 2, aramid coated battery separator (ANFs/PE) of comparative example 1, and aramid coated battery separator loaded with ZIF-67 (ANFs @ ZIF-67/PE) of example 7, three sets of cells having a cycling performance of 0.5C. The coulomb efficiency of 160 cycles of charge and discharge (fig. 4) was maintained above 98.5% at 0.5C, which is higher than that of the other two groups of cells. The discharge specific capacity is reduced by 22 percent and is lower than that of other two groups of batteries.
FIG. 5 is a charge-discharge curve of 200 charge-discharge cycles at 0.5C for an assembled battery of ZIF-67 loaded aramid coated battery separator (ANFs @ ZIF-67/PE). The data show that the battery assembled by the ZIF-67-loaded aramid fiber coated battery diaphragm (ANFs @ ZIF-67/PE) has higher initial specific capacity, and a better charging and discharging platform is still kept after 200 circles, so that the ZIF-67-loaded aramid fiber coated battery diaphragm (ANFs @ ZIF-67/PE) has better battery performance.
It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (8)
1. The battery diaphragm is characterized by comprising a polyolefin porous diaphragm and an aramid coating coated on one side of the polyolefin porous diaphragm, wherein the aramid nanofiber of the aramid coating is loaded with a nano material and provides a site for the in-situ growth of the nano material;
the preparation method of the battery diaphragm coated with the nano-material-loaded aramid fiber comprises the following steps:
s1: adding potassium hydroxide, deionized water and an aramid polymer into dimethyl sulfoxide, stirring and dissolving at normal temperature, and dropwise adding absolute ethyl alcohol to prepare aramid nanofiber slurry;
s2: coating the aramid nano-fiber slurry obtained in the step S1 on the surface of the polyolefin porous diaphragm to obtain a coating film;
s3: respectively soaking the coating film obtained in the step S2 into a substitution solvent, a first precursor solution and a second precursor solution in sequence, and washing to obtain a coating film loaded with the nano material; the nano material is one of ZnS, NiS, ZIF-8 or ZIF-67;
s4: drying the coating film obtained in the step S3 in a vacuum oven to obtain the nano-material-loaded aramid fiber coating battery diaphragm;
in the step S1, the aramid nano-fiber slurry comprises the following components in percentage by mass: potassium hydroxide + aramid polymer: deionized water: and (2) dimethylsulfoxide (1-4): 8: 220, wherein the ratio of potassium hydroxide: 3 of aramid polymer in mass ratio: 2; the mass ratio of the absolute ethyl alcohol to the aramid polymer is (75-540) to 4;
in step S3, the substitution solvent is one or more of ethanol, methanol, and deionized water; the first precursor and the second precursor are soluble inorganic matters and organic matters which react with each other in a solvent at normal temperature to generate nano particles, and the first precursor and the second precursor are determined according to the type of nano materials; the solvent is one or more of ethanol, methanol, deionized water and dimethylformamide.
2. The nanomaterial-loaded aramid coated battery separator according to claim 1, wherein the polyolefin porous separator is one of a polypropylene microporous separator, a polyethylene microporous separator, or a polypropylene/polyethylene/polypropylene three-layer composite separator.
3. The nanomaterial-loaded aramid-coated battery separator of claim 1, wherein the aramid nanofibers have the following para-chemical structure:
4. the nanomaterial-loaded aramid coated battery separator of claim 1, wherein the thickness of the aramid coating is 1-4 μ ι η.
5. A preparation method of a nanomaterial-loaded aramid coated battery separator, which is used for preparing the nanomaterial-loaded aramid coated battery separator as claimed in any one of claims 1 to 4, and is characterized by comprising the following steps:
s1: adding potassium hydroxide, deionized water and an aramid polymer into dimethyl sulfoxide, stirring and dissolving at normal temperature, and dropwise adding absolute ethyl alcohol to prepare aramid nanofiber slurry;
s2: coating the aramid nano-fiber slurry obtained in the step S1 on the surface of the polyolefin porous diaphragm to obtain a coating film;
s3: respectively soaking the coating film obtained in the step S2 into a substitution solvent, a first precursor solution and a second precursor solution in sequence, and washing to obtain a coating film loaded with the nano material; the nano material is one of ZnS, NiS, ZIF-8 or ZIF-67;
s4: drying the coating film obtained in the step S3 in a vacuum oven to obtain the nano-material-loaded aramid fiber coating battery diaphragm;
in the step S1, the mass ratio of the components of the aramid nano-fiber slurry is as follows: potassium hydroxide + aramid polymer: deionized water: dimethyl sulfoxide (1-4): 8: 220, wherein the ratio of potassium hydroxide: 3 of aramid polymer in mass ratio: 2; the mass ratio of the absolute ethyl alcohol to the aramid polymer is (75-540): 4;
in step S3, the substitution solvent is one or more of ethanol, methanol, and deionized water; the first precursor and the second precursor are soluble inorganic matters and organic matters which react with each other in a solvent at normal temperature to generate nano particles, and the first precursor and the second precursor are determined according to the type of nano materials; the solvent is one or more of ethanol, methanol, deionized water and dimethylformamide.
6. The method for preparing the nanomaterial-loaded aramid coated battery separator according to claim 5, wherein in step S2, the coating thickness of the aramid nanofiber slurry is 30 to 120 μm.
7. The preparation method of the nanomaterial-loaded aramid coated battery separator according to claim 5, wherein in step S3, the soaking time in the substitution solvent is 3-15 min; the soaking time in the first precursor solution is 10-60 min; the soaking time in the second precursor solution is 3-60 min.
8. A lithium-sulfur battery having the nanomaterial-loaded aramid coated battery separator of any of claims 1-4, wherein the lithium-sulfur battery is assembled in the order of a positive electrode can, a pole piece, the nanomaterial-loaded aramid coated battery separator dripped with electrolyte, a lithium piece, a steel piece, a spring piece, and a negative electrode can, and the aramid coating faces one side of the pole piece.
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