CN106876634A - Composite diaphragm and preparation method thereof, and lithium ion battery - Google Patents
Composite diaphragm and preparation method thereof, and lithium ion battery Download PDFInfo
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- CN106876634A CN106876634A CN201710137732.9A CN201710137732A CN106876634A CN 106876634 A CN106876634 A CN 106876634A CN 201710137732 A CN201710137732 A CN 201710137732A CN 106876634 A CN106876634 A CN 106876634A
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- 239000002131 composite material Substances 0.000 title claims abstract description 67
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 title claims abstract description 28
- 229910001416 lithium ion Inorganic materials 0.000 title claims abstract description 28
- 238000002360 preparation method Methods 0.000 title abstract description 6
- 239000002121 nanofiber Substances 0.000 claims abstract description 150
- 239000000835 fiber Substances 0.000 claims abstract description 129
- 238000009413 insulation Methods 0.000 claims abstract description 5
- 229920002239 polyacrylonitrile Polymers 0.000 claims description 60
- 239000012528 membrane Substances 0.000 claims description 50
- 229920000642 polymer Polymers 0.000 claims description 48
- 239000002052 molecular layer Substances 0.000 claims description 35
- 239000002245 particle Substances 0.000 claims description 35
- 239000000919 ceramic Substances 0.000 claims description 31
- 239000004642 Polyimide Substances 0.000 claims description 26
- 229920001721 polyimide Polymers 0.000 claims description 26
- 238000000034 method Methods 0.000 claims description 23
- 239000002033 PVDF binder Substances 0.000 claims description 22
- 229920002981 polyvinylidene fluoride Polymers 0.000 claims description 22
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 18
- 238000010041 electrostatic spinning Methods 0.000 claims description 14
- MCMNRKCIXSYSNV-UHFFFAOYSA-N ZrO2 Inorganic materials O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 claims description 13
- RVTZCBVAJQQJTK-UHFFFAOYSA-N oxygen(2-);zirconium(4+) Chemical compound [O-2].[O-2].[Zr+4] RVTZCBVAJQQJTK-UHFFFAOYSA-N 0.000 claims description 13
- 239000011148 porous material Substances 0.000 claims description 13
- 238000010000 carbonizing Methods 0.000 claims description 10
- 229920003171 Poly (ethylene oxide) Polymers 0.000 claims description 9
- 239000000377 silicon dioxide Substances 0.000 claims description 9
- 235000012239 silicon dioxide Nutrition 0.000 claims description 7
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 claims description 6
- 238000004519 manufacturing process Methods 0.000 claims description 6
- 239000007788 liquid Substances 0.000 claims description 5
- 239000000463 material Substances 0.000 claims description 5
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 claims description 5
- 238000001523 electrospinning Methods 0.000 claims description 4
- 238000010521 absorption reaction Methods 0.000 claims description 3
- 239000000395 magnesium oxide Substances 0.000 claims description 3
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 claims description 3
- AXZKOIWUVFPNLO-UHFFFAOYSA-N magnesium;oxygen(2-) Chemical compound [O-2].[Mg+2] AXZKOIWUVFPNLO-UHFFFAOYSA-N 0.000 claims description 3
- 239000004408 titanium dioxide Substances 0.000 claims description 3
- 239000000243 solution Substances 0.000 description 70
- 229920005575 poly(amic acid) Polymers 0.000 description 32
- 238000010292 electrical insulation Methods 0.000 description 30
- 238000002347 injection Methods 0.000 description 27
- 239000007924 injection Substances 0.000 description 27
- 238000009987 spinning Methods 0.000 description 26
- ZMXDDKWLCZADIW-UHFFFAOYSA-N N,N-Dimethylformamide Chemical compound CN(C)C=O ZMXDDKWLCZADIW-UHFFFAOYSA-N 0.000 description 24
- 210000001787 dendrite Anatomy 0.000 description 23
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical class C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 21
- 239000002904 solvent Substances 0.000 description 17
- 229920000049 Carbon (fiber) Polymers 0.000 description 14
- 239000004917 carbon fiber Substances 0.000 description 14
- 239000002134 carbon nanofiber Substances 0.000 description 14
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 10
- 229910052744 lithium Inorganic materials 0.000 description 10
- 239000000853 adhesive Substances 0.000 description 9
- 230000001070 adhesive effect Effects 0.000 description 9
- 238000003763 carbonization Methods 0.000 description 9
- 230000007613 environmental effect Effects 0.000 description 9
- 229910021392 nanocarbon Inorganic materials 0.000 description 9
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 8
- WYURNTSHIVDZCO-UHFFFAOYSA-N Tetrahydrofuran Chemical compound C1CCOC1 WYURNTSHIVDZCO-UHFFFAOYSA-N 0.000 description 8
- VLDPXPPHXDGHEW-UHFFFAOYSA-N 1-chloro-2-dichlorophosphoryloxybenzene Chemical compound ClC1=CC=CC=C1OP(Cl)(Cl)=O VLDPXPPHXDGHEW-UHFFFAOYSA-N 0.000 description 7
- GTDPSWPPOUPBNX-UHFFFAOYSA-N ac1mqpva Chemical compound CC12C(=O)OC(=O)C1(C)C1(C)C2(C)C(=O)OC1=O GTDPSWPPOUPBNX-UHFFFAOYSA-N 0.000 description 7
- 239000003792 electrolyte Substances 0.000 description 7
- CBCKQZAAMUWICA-UHFFFAOYSA-N 1,4-phenylenediamine Chemical compound NC1=CC=C(N)C=C1 CBCKQZAAMUWICA-UHFFFAOYSA-N 0.000 description 6
- UDQLIWBWHVOIIF-UHFFFAOYSA-N 3-phenylbenzene-1,2-diamine Chemical compound NC1=CC=CC(C=2C=CC=CC=2)=C1N UDQLIWBWHVOIIF-UHFFFAOYSA-N 0.000 description 6
- HLBLWEWZXPIGSM-UHFFFAOYSA-N 4-Aminophenyl ether Chemical compound C1=CC(N)=CC=C1OC1=CC=C(N)C=C1 HLBLWEWZXPIGSM-UHFFFAOYSA-N 0.000 description 6
- FXHOOIRPVKKKFG-UHFFFAOYSA-N N,N-Dimethylacetamide Chemical compound CN(C)C(C)=O FXHOOIRPVKKKFG-UHFFFAOYSA-N 0.000 description 6
- 230000005611 electricity Effects 0.000 description 6
- 239000000126 substance Substances 0.000 description 6
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 5
- 239000011248 coating agent Substances 0.000 description 5
- 238000000576 coating method Methods 0.000 description 5
- 230000002194 synthesizing effect Effects 0.000 description 5
- IAZDPXIOMUYVGZ-UHFFFAOYSA-N Dimethylsulphoxide Chemical compound CS(C)=O IAZDPXIOMUYVGZ-UHFFFAOYSA-N 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 4
- 150000004985 diamines Chemical class 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 4
- 230000003647 oxidation Effects 0.000 description 4
- 238000007254 oxidation reaction Methods 0.000 description 4
- 238000003756 stirring Methods 0.000 description 4
- YLQBMQCUIZJEEH-UHFFFAOYSA-N tetrahydrofuran Natural products C=1C=COC=1 YLQBMQCUIZJEEH-UHFFFAOYSA-N 0.000 description 4
- 238000001132 ultrasonic dispersion Methods 0.000 description 4
- JVERADGGGBYHNP-UHFFFAOYSA-N 5-phenylbenzene-1,2,3,4-tetracarboxylic acid Chemical compound OC(=O)C1=C(C(O)=O)C(C(=O)O)=CC(C=2C=CC=CC=2)=C1C(O)=O JVERADGGGBYHNP-UHFFFAOYSA-N 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 3
- 229910002804 graphite Inorganic materials 0.000 description 3
- 239000010439 graphite Substances 0.000 description 3
- 238000002156 mixing Methods 0.000 description 3
- 239000007921 spray Substances 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- PNEYBMLMFCGWSK-UHFFFAOYSA-N Alumina Chemical compound [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 2
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 239000004952 Polyamide Substances 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 239000012298 atmosphere Substances 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 229910052734 helium Inorganic materials 0.000 description 2
- 239000001307 helium Substances 0.000 description 2
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 2
- 239000011261 inert gas Substances 0.000 description 2
- 238000010030 laminating Methods 0.000 description 2
- 230000014759 maintenance of location Effects 0.000 description 2
- 239000000178 monomer Substances 0.000 description 2
- 239000012299 nitrogen atmosphere Substances 0.000 description 2
- 230000001590 oxidative effect Effects 0.000 description 2
- 229910052574 oxide ceramic Inorganic materials 0.000 description 2
- 239000011224 oxide ceramic Substances 0.000 description 2
- 229920002647 polyamide Polymers 0.000 description 2
- 229920005594 polymer fiber Polymers 0.000 description 2
- -1 polyoxyethylene Polymers 0.000 description 2
- VQVIHDPBMFABCQ-UHFFFAOYSA-N 5-(1,3-dioxo-2-benzofuran-5-carbonyl)-2-benzofuran-1,3-dione Chemical compound C1=C2C(=O)OC(=O)C2=CC(C(C=2C=C3C(=O)OC(=O)C3=CC=2)=O)=C1 VQVIHDPBMFABCQ-UHFFFAOYSA-N 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 239000012300 argon atmosphere Substances 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 238000006356 dehydrogenation reaction Methods 0.000 description 1
- 238000007598 dipping method Methods 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 238000004146 energy storage Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000004880 explosion Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- 229920002521 macromolecule Polymers 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 230000003446 memory effect Effects 0.000 description 1
- 239000013081 microcrystal Substances 0.000 description 1
- 239000011259 mixed solution Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 238000013021 overheating Methods 0.000 description 1
- 229920006112 polar polymer Polymers 0.000 description 1
- 230000010287 polarization Effects 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000007363 ring formation reaction Methods 0.000 description 1
Classifications
-
- 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
-
- 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
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
-
- 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
-
- 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
- H01M50/431—Inorganic material
-
- 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
-
- 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
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Inorganic Chemistry (AREA)
- Cell Separators (AREA)
- Nonwoven Fabrics (AREA)
Abstract
The present invention relates to a kind of composite diaphragm, including the conductive fiber layer and electric insulation layers of nanofibers that are stacked, the conductive fiber layer includes multiple nano-conductive fibers, the multiple nano-conductive fiber intersects to form network structure, and the conductive fiber layer has multiple micropores formed by the nano-conductive fiber.A kind of lithium ion battery, including composite diaphragm, positive pole and negative pole, the conductive fiber layer are arranged on the negative pole side, and are electrically connected with the negative pole.The invention further relates to a kind of preparation method of composite diaphragm.
Description
Technical Field
The invention relates to the field of batteries, in particular to a composite diaphragm, a preparation method thereof and a lithium ion battery using the composite diaphragm.
Background
The lithium ion battery has the characteristics of high energy density, high output power, small self-discharge, no memory effect, long cycle life, environmental friendliness and the like, and is widely applied to the aspects of power and energy storage. The diaphragm is an important component of the lithium ion battery and is used for separating the positive electrode and the negative electrode and preventing the two electrodes from being in direct contact with each other to cause short circuit. The diaphragm allows lithium ions to pass through and prevents electrons from flowing through, and the lithium ions are transmitted between the positive electrode and the negative electrode in the charging and discharging process. The diaphragm determines the interface structure, internal resistance, battery capacity and the like of the lithium ion battery, and the performance of the diaphragm can influence the charge-discharge cycle performance, the service life, the safety performance and the like of the battery.
In addition, because lithium ions are unevenly removed and deposited in the circulation process, a preferential growth phenomenon exists on the surface of the lithium metal negative electrode, and dendritic lithium metal dendrites are generated. Lithium ion batteries using graphite as the negative electrode are prone to have lithium dendrites on the surface of the graphite negative electrode even under low-temperature or fast-charge conditions. In the circulation process, the lithium dendrite continuously growing on the negative electrode can pierce through the diaphragm and reach the positive electrode to cause short circuit of the positive electrode and the negative electrode in the battery, so that local overheating is caused to cause fire and even explosion, and great potential safety hazard is realized.
Disclosure of Invention
Based on the above, there is a need for a composite separator capable of inhibiting growth of lithium dendrites on a negative electrode, a method for preparing the same, and a lithium ion battery using the composite separator.
A composite diaphragm comprises a conductive fiber layer and an electric insulation nanofiber layer which are arranged in a stacked mode, wherein the conductive fiber layer comprises a plurality of nano conductive fibers, the nano conductive fibers are mutually crossed to form a net-shaped structure, and the conductive fiber layer is provided with a plurality of micropores formed by the nano conductive fibers.
In one embodiment, the electrically insulating nanofiber layer comprises nanofibers that cross each other to form a network, and the electrically insulating nanofiber layer has a plurality of micropores formed by the nanofibers.
In one embodiment, the material of the nano conductive fiber is at least one of carbonized polyimide and carbonized polyacrylonitrile.
In one embodiment, the material of the nanofiber is at least one of polyimide, polyvinylidene fluoride, and polyacrylonitrile.
In one embodiment, the method further comprises an inorganic nano-layer arranged in a stack, wherein the electrically insulating nano-fiber layer is positioned between the inorganic nano-layer and the electrically conductive fiber layer.
In one embodiment, the electric insulation nanometer fiber layer is positioned between the two inorganic nanometer layers, and the conductive fiber layer is laminated on the other side of any one of the inorganic nanometer layers.
In one embodiment, the inorganic nano-layer includes a high molecular polymer and inorganic nano-ceramic particles, the high molecular polymer is at least one of polyvinylidene fluoride and polyethylene oxide, and the inorganic nano-ceramic particles are one or two of silicon dioxide, titanium dioxide, zirconium dioxide, aluminum oxide and magnesium oxide.
In one embodiment, the composite separator has a porosity of 60% to 96% and an average pore size of 4.0 μm to 5.5 μm.
In one embodiment, the liquid absorption rate of the composite diaphragm is 400-900%.
In one embodiment, the composite membrane has a mass per unit area of 6g/m2To 20g/m2And the thickness is 15 to 70 μm.
A lithium ion battery comprises the foregoing any one of the composite diaphragm, the positive electrode and the negative electrode, wherein the composite diaphragm is arranged between the positive electrode and the negative electrode, and the conductive fiber layer is arranged on one side of the negative electrode and is electrically connected with the negative electrode.
A method of making a composite separator, comprising:
preparing a conductive fiber layer, wherein the conductive fiber layer comprises a plurality of nano conductive fibers, the nano conductive fibers are mutually crossed to form a net structure, and the conductive fiber layer is provided with a plurality of micropores formed by the nano conductive fibers; and
forming an electrically insulating nanofiber layer on the conductive fiber layer.
In one embodiment, the method further comprises the following steps:
forming an inorganic nano-layer on the electrically insulating nanofiber layer.
In one embodiment, the preparing the conductive fiber layer comprises:
providing a first polymer solution;
preparing the first polymer solution into a nanofiber membrane by an electrostatic spinning method; and
and carbonizing the nanofiber membrane to obtain the conductive fiber layer.
In one embodiment, the forming of the electrically insulating nanofiber layer on the electrically conductive fiber layer comprises:
providing a second polymer solution; and
forming the electrically insulating nanofiber layer from the second polymer solution on the conductive fiber layer by an electrospinning method.
In one embodiment, before the step of carbonizing the nanofiber membrane to obtain the conductive fiber layer, the step of preparing a conductive fiber layer further comprises: and (3) pretreating the nanofiber membrane to cyclize the internal components in the nanofiber membrane, so that the stability of the nanofiber membrane is improved.
The composite diaphragm and the lithium ion battery comprise a conductive fiber layer and an electric insulation nanofiber layer which are arranged in a stacked mode. The conductive fiber layer includes a plurality of nano conductive fibers crossing each other to form a network structure, and has a plurality of micro pores formed by the conductive fibers. In the battery, the conductive fiber layer is electrically connected with the negative electrode of the battery, acts as a pseudo current collector and has higher potential relative to the negative electrode. And the dendrite preferentially grows at a high potential, so the dendrite can preferentially grow on the conductive fiber layer. The nanometer conductive fibers in the conductive fiber layer are crossed with each other to form micropores, so that the conductive fiber layer has a large specific surface area, and the inside of the conductive fiber layer is provided with an inner surface for forming the micropores. The dendrites can be dispersedly grown on the inner surface of the conductive fiber layer, so that the growth of dendrites of the battery negative electrode is eliminated. The internal surface of the conductive fiber layer has more sites for the growth of the dendrites, so that the length of the generated dendrites is relatively reduced, and the diaphragm is prevented from being punctured by the generated longer dendrites.
Drawings
Fig. 1 is a schematic view of a composite separator according to an embodiment of the present invention.
Wherein,
composite membrane-10;
a conductive fiber layer-12;
an electrically insulating nanofiber layer-14;
inorganic nanolayer-16.
Detailed Description
For a better understanding of the present invention, reference is made to the following detailed description taken in conjunction with the accompanying drawings.
Referring to fig. 1, the present invention provides a composite separator 10 including a conductive fiber layer 12 and an electrically insulating nanofiber layer 14 stacked together. The electrically insulating nanofiber layer 14 may sequester electrons and allow lithium ions to pass through. The conductive fiber layer 12 may be conductive and allow lithium ions to pass through. The conductive fiber layer 12 includes a plurality of nano conductive fibers, the nano conductive fibers are crossed and wound to form a mesh structure, and the conductive fiber layer 12 has a plurality of micropores formed by the nano conductive fibers. The conductive fiber layer 12 is electrically connected to the battery negative electrode during operation, acts as a pseudo current collector, and has a higher potential relative to the negative electrode. While dendrites preferentially grow at a high potential, dendrites can preferentially grow on the conductive fiber layer 12. The conductive fiber layer 12 is formed by crossing the nano conductive fibersAnd thus the conductive fiber layer 12 has a large specific surface area, and has an inner surface forming micropores therein. Dendrites can be dispersedly grown on the inner surface of the conductive fiber layer 12, thereby eliminating the growth of dendrites of the battery negative electrode. The internal surface of the conductive fiber layer 12 has more sites for the growth of dendrites, so that the length of the generated dendrites is relatively reduced, which is beneficial to preventing the generated dendrites from puncturing the diaphragm. Preferably, the composite separator 10 has a mass per unit area of 6g/m2To 20g/m2And the thickness is 15 to 70 μm.
The electrically insulating nanofiber layer 14 comprises nanofibers. The nanometer fibers are mutually crossed and wound to form a network structure, and a pore structure which takes the zigzag holes as main parts and is interconnected and open is formed. The pore size can reach submicron level, the pores are communicated with each other, and the specific surface area is large. The material of the nanofiber is a polymer macromolecule, preferably a polar polymer. The crystalline region in the polymer can not be swelled by the electrolyte, and can play a certain supporting role; the amorphous region can be swollen by the electrolyte to form a gel phase, thereby having better compatibility with the electrolyte. Some electrolyte may be present in both the crystalline interstitial and swollen amorphous regions. The electrical insulation nanofiber layer 14 can be prepared by an electrostatic spinning method, so that the electrical insulation nanofiber layer 14 with low fiber crystallinity can be obtained more easily, the obtained electrical insulation nanofiber layer 14 has good electrolyte affinity, wettability and retentivity, and higher ionic conductivity and interface compatibility can be obtained, thereby being beneficial to high-current charge and discharge. The polymer is preferably at least one of polyimide, polyvinylidene fluoride, and polyacrylonitrile. The thickness of the electrically insulating nanofiber layer 14 is preferably 8 μm to 60 μm, the nanofiber diameter is preferably 50nm to 800nm, and the average pore diameter is preferably 5 μm to 6.5 μm. Wherein the thermal stability temperature of the polyimide is above 300 ℃, the thermal stability temperature of the polyvinylidene fluoride is above 150 ℃, and the thermal stability temperature of the polyacrylonitrile is above 270 ℃.
The conductive fiber layer 12 includes carbon nanofibers that are cross-wound to form a network structure having a structure of interconnected open pores, mainly with zigzag pores. The pore size can reach yaAnd in a micron scale, the pores are communicated with each other, and the specific surface area of the conductive fiber layer 12 is large, so that more lithium ion growth sites can be provided. And the conductive fiber layer 12 can reduce the polarization reaction of the battery and improve the electrical performance. The conductive fiber layer 12 may be a carbon nanofiber layer obtained by carbonizing a polymer fiber layer, so that the original properties of the polymer electrically-insulated nanofiber layer, such as fiber diameter, porosity and the like, are maintained after carbonization. The polymer fiber layer used for forming the conductive fiber layer 12 can also be prepared by an electrostatic spinning method. The polymer is preferably at least one of polyimide and polyacrylonitrile. The thickness of the conductive fiber layer 12 is preferably 5 μm to 30 μm, the diameter of the conductive fiber is preferably 50nm to 800nm, the average pore diameter is preferably 5 μm to 6.5 μm, and the specific surface area is preferably 100-800m2/g。
The electrically insulating nanofiber layer 14 and the electrically conductive fiber layer 12 of the composite separator 10 each have a network structure, so as to have a large specific surface area and porosity, and preferably, the porosity of the composite separator 10 is 60% to 96%, and the average pore diameter is preferably 4.0 μm to 5.5 μm.
Preferably, the composite separator 10 further includes an inorganic nanolayer 16 disposed in a stack. The electrically insulating nanofiber layer 14 is located between the inorganic nanofiber layer 16 and the electrically conductive fiber layer 12. The inorganic nano-layer 16 is arranged on one side of the electrical insulation nano-fiber layer 14, so that the electrolyte in the electrical insulation nano-fiber layer 14 is not easy to flow out, and the liquid retention performance of the composite diaphragm 10 is improved. By arranging the inorganic nano-layer 16 on one side of the electrical insulation nano-fiber layer 14, the liquid absorption rate of the composite diaphragm 10 can reach 400-900%.
More preferably, two inorganic nano-layers 16 are further included. The electrically insulating nanofiber layer 14 is located between two inorganic nanolayers 16. The conductive fiber layer 12 is laminated to any one of the inorganic nanolayers 16. The inorganic nano-layers 16 are respectively arranged on the two sides of the electrical insulation nano-fiber layer 14, so that the electrolyte in the electrical insulation nano-fiber layer 14 is protected from the two sides, and the liquid retention performance of the composite diaphragm 10 is greatly improved.
The inorganic nano-layer 16 includes a high molecular polymer and inorganic nano-ceramic particles uniformly mixed. The high molecular polymer is used for binding the inorganic nano ceramic particles and can be at least one of polyvinylidene fluoride and polyethylene oxide. The inorganic nano ceramic particles can be one or two of silicon dioxide, titanium dioxide, zirconium dioxide, aluminum oxide and magnesium oxide. The thickness of the inorganic nano-layer 16 is preferably 2 μm to 10 μm, and the particle diameter of the inorganic nano-ceramic particles is preferably 20nm to 1000 nm. The inorganic nano-layer 16 can improve the interface characteristics, reduce the interface impedance, and enhance the mechanical properties, ionic conductivity, and thermal stability of the interface, wherein the mechanical properties are mainly embodied by increasing the mechanical strength of the composite membrane 10, so that the membrane is not easily pierced by lithium dendrites.
The invention also provides a lithium ion battery, which comprises the composite diaphragm 10, the positive electrode and the negative electrode in any embodiment, wherein the conductive fiber layer 12 is arranged on one side of the negative electrode and is electrically connected with the negative electrode. Specifically, the conductive fiber layer 12 may be directly attached to the negative electrode. The composite separator 10 of the present invention can greatly reduce the growth length of negative lithium dendrites and change the growth position of lithium dendrites, relative to a separator without a conductive fiber layer. It was found through experiments that in the lithium ion battery using the composite separator 10 of the present invention, lithium dendrites mainly grow inside the conductive fiber layer 12 under the same conditions, and the growth length is 1/20, which is the length of the lithium dendrites of the lithium ion battery using the existing separator.
The invention also provides a preparation method of the composite diaphragm 10, which comprises the following steps:
s110, preparing a conductive fiber layer 12; and
s120, forming an electrically insulating nanofiber layer 14 on the conductive fiber layer 12.
Preferably, the method further comprises the following steps:
s130, the inorganic nano-layer 16 is formed on the electrically insulating nanofiber layer 14.
In one embodiment, S110 further comprises:
s112, providing a first polymer solution;
s114, preparing the first polymer solution into a nanofiber membrane by an electrostatic spinning method; and
and S116, carbonizing the nanofiber membrane to obtain the conductive fiber layer 12.
In step S112, the first polymer solution is preferably at least one of a polyamic acid solution and a polyacrylonitrile solution. The solvent in the first polymer solution may be at least one of N, N-dimethylformamide, dimethylacetamide, acetone, tetrahydrofuran, N-methylpyrrolidone, and dimethylsulfoxide. In the case of mixing two solvents, the mixing ratio of the two solvents is preferably 1:1 to 1: 99. The mass percentage of the solute in the first polymer solution is preferably 6% to 15%.
In one embodiment, the polyamic acid solution is prepared by synthesizing dianhydride and diamine in a solvent at a low temperature, wherein the reaction temperature is-5 ℃ to 15 ℃, and preferably 0 ℃ to 5 ℃. Wherein the dianhydride can be any one of pyromellitic dianhydride (PMDA), 3',4,4' -benzophenonetetracarboxylic dianhydride (BTDA) and biphenyl tetracarboxylic dianhydride (BPDA); the diamine may be any of p-phenylenediamine (PPD), Oxydianiline (ODA) and Biphenyldiamine (BID).
In step S114, the ambient humidity is preferably controlled to 30% to 70% in the electrospinning; the injection pump is communicated with the spinning needle through a pipeline; the distance between the spinning needle head and the receiving device is preferably 10cm to 70cm, and the voltage between the spinning needle head and the receiving device is preferably 12kV to 70 kV; the polymer solution reaching the spinning needle from the injection pump through the pipeline is sprayed out of the polymer nano-fiber at a flow rate of 0.1mL/h to 130 mL/h; collecting the polymer nanofibers on a receiving device to form a nanofiber membrane.
By controlling the voltage and the distance between the spinning needle head and the receiving device in electrostatic spinning, the concentration of the polymer solution and the ejected flow rate, fibers with different diameters can be obtained. And the thickness of the fiber membrane can be adjusted by controlling the time of electrostatic spinning and the subsequent treatment control of the fiber membrane.
In step S116, a high temperature carbonization process is performed in an inert gas atmosphere, and the carbonization temperature may be 700 to 900 ℃. The inert gas may be high purity nitrogen, argon or helium, preferably greater than 99.999%.
In one embodiment, the step S116 further includes:
s116a, pretreating the nanofiber membrane to cyclize the internal components of the nanofiber membrane, thereby improving the stability of the nanofiber membrane.
In step S116a, if the polyamic acid nanofiber membrane is prepared from a polyamic acid solution, a polyimide nanofiber membrane is obtained by thermal imidization, chemical imidization or a combination thereof; if the polyacrylonitrile nano-fiber membrane is prepared from the polyacrylonitrile solution, pre-oxidation is carried out at the temperature of 120-130 ℃ to obtain the polyacrylonitrile nano-fiber membrane with a network structure. The structure of the polyamic acid is unstable, easy to dissolve and degrade, and the polyamic acid can be dehydrated and cyclized in the imidization process to obtain the polyimide structure with stable structure. The polyacrylonitrile fiber is subjected to a series of chemical reactions such as cyclization, dehydrogenation and the like in the pre-oxidation process, so that the chemical composition and the structure of the fiber are changed, and an original structure which is converted into graphite microcrystals during carbonization is formed inside the fiber. After the polyacrylonitrile fiber membrane is pre-oxidized, the linear molecular structure in polyacrylonitrile is converted into a heat-resistant trapezoidal structure. In the polymer with the trapezoidal structure, the whole molecular chain is not broken by breaking one bond, and the melting decomposition of the polyacrylonitrile fiber in the high-temperature heating process during high-temperature carbonization is prevented. During high-temperature carbonization, the trapezoidal structure is not melted, so that polyacrylonitrile has good thermal stability, chemical and mechanical properties can be kept before the structure is broken, and polyacrylonitrile fibers can be carbonized into carbon fibers under the condition of keeping the fiber form after preoxidation.
In one embodiment, S120 further comprises:
s122, providing a second polymer solution; and
and S124, forming the electrical insulation nanofiber layer 14 on the conductive fiber layer 12 by the second polymer solution through an electrostatic spinning method.
In step S122, the second polymer solution may be at least one of a polyamic acid solution, a polyacrylonitrile solution, and a polyvinylidene fluoride solution. The solvent in the second polymer solution may be at least one of N, N-dimethylformamide, dimethylacetamide, acetone, tetrahydrofuran, N-methylpyrrolidone, and dimethylsulfoxide. If the two solvents are mixed, the mixing ratio of the two solvents is 1:1 to 1: 99. The solute in the second polymer solution is 6 to 15 mass%. The polyamic acid solution is prepared by synthesizing dianhydride and diamine in a solvent at a low temperature, wherein the reaction temperature is-5 ℃ to 15 ℃, and preferably 0 ℃ to 5 ℃. Wherein the dianhydride can be any one of pyromellitic dianhydride (PMDA), 3',4,4' -benzophenonetetracarboxylic dianhydride (BTDA) and biphenyl tetracarboxylic dianhydride (BPDA); the diamine may be any of p-phenylenediamine (PPD), Oxydianiline (ODA) and Biphenyldiamine (BID).
In step S124, the ambient humidity is preferably controlled to 30% to 70% in the electrospinning; the injection pump is communicated with the spinning needle through a pipeline; the distance between the spinning needle head and the receiving device is preferably 10cm to 70cm, and the voltage between the spinning needle head and the receiving device is preferably 12kV to 70 kV; the polymer solution reaching the spinning needle from the injection pump through the pipeline is sprayed out of the polymer nano-fiber at a flow rate of 0.1mL/h to 130 mL/h; the conductive fiber layer 12 is placed on a receiving device and the polymer nanofibers are collected over the conductive fiber layer 12.
By controlling the voltage and the distance between the spinning needle head and the receiving device in electrostatic spinning, the concentration of the polymer solution and the ejected flow rate, fibers with different diameters can be obtained. And the thickness of the fiber layer can be adjusted by controlling the time of electrostatic spinning and the subsequent treatment control of the fiber film.
In one embodiment, S124 further includes:
and S124, 124a, processing the nanofiber membrane.
In step S124a, if the polyamic acid nanofiber film is prepared from the polyamic acid solution, the polyimide electrical insulation nanofiber layer is obtained by thermal imidization, chemical imidization or a combination thereof.
In one embodiment, S130 further includes:
s132, preparing an inorganic nano ceramic particle solution; and
s134, coating the surface of the electrical insulation nanofiber layer with an inorganic nano ceramic particle solution, or dipping the electrical insulation nanofiber layer in the inorganic nano ceramic particle solution, so as to form an inorganic nano layer on the electrical insulation nanofiber layer.
In step S132, the adhesive high molecular polymer is mechanically or magnetically stirred in the solvent until completely dissolved, and then a certain amount of inorganic nano ceramic particles are added and ultrasonically dispersed for 30min to 120 min. The solvent can be N-methyl pyrrolidone or water. The mass concentration of the inorganic nano-ceramic particles is preferably 0.1% to 5%, and the mass ratio of the binding high molecular polymer to the inorganic nano-ceramic particles is preferably 1:0.5 to 1: 2.
The invention also provides a preparation method of the composite diaphragm 10, which comprises the following steps:
s210, preparing a conductive fiber layer 12;
s220, forming a first inorganic nano-layer on the conductive fiber layer 12;
s230, forming an electrically insulating nanofiber layer 14 on the first inorganic nano-layer; and
s240, a second inorganic nano-layer is formed on the electrically insulating nano-fiber layer 14.
Step S210 is the same as step S110. The steps of forming the first and second inorganic nanolayers in steps S220 and S240 are substantially the same as step S130, except that the conductive fiber layer 12 is placed on the receiving device in step S220, and the first inorganic nanolayer is stacked on the conductive fiber layer 12; in step S240, the conductive fiber layer 12/the first inorganic nano-layer/the electrically insulating nano-fiber layer 14 is placed on the receiving device, and the second inorganic nano-layer is stacked on the electrically insulating nano-fiber layer 14; the conductive fiber layer 12/the electrically insulating nanofiber layer 14 is placed on the receiving device in step S130, and the inorganic nano-layer 16 is laminated on the electrically insulating nanofiber layer 14. The same applies to the extension of step S130 to steps S220 and S240.
Example 1
S110, preparing a conductive fiber layer 12 nanometer carbon fiber layer, comprising:
s112, synthesizing a polyamic acid solution with the mass percent of 6% in N, N-dimethylformamide solution by using biphenyl tetracarboxylic dianhydride (BPDA) and p-phenylenediamine (PPD) at the temperature of-5 ℃;
and S114, preparing the polyamic acid nanofiber membrane by an electrostatic spinning method. Specifically, the polyamic acid solution obtained in step S112 is added to an injection pump, and the environmental humidity is controlled to be 30%; the injection pump is connected with the spinning needle through a pipeline; the distance between the needle head and the receiving device is 30cm, and 25kV high-voltage electricity is applied between the needle head and the receiving device; the polymer solution reaching the spinning needle head from the injection pump through a pipeline sprays the polyamic acid nano fiber at the flow rate of 1 mL/h; collecting the polyamic acid nanofiber by using a receiving device to obtain a polyamic acid nanofiber membrane with the thickness of 10 mu m;
s116a, carrying out thermal imidization on the polyamic acid nanofiber membrane to obtain a polyimide nanofiber membrane;
s116, carbonizing the polyimide nanofiber membrane in a nitrogen atmosphere with the purity of 99.999 percent at the carbonization temperature of 900 ℃ to obtain the carbon nanofiber layer.
S120, forming an electrically insulating nanofiber layer 14 on the conductive fiber layer 12, specifically including:
and S122, preparing a polyvinylidene fluoride solution with the mass percent of 15%. The selected solvent is a mixed solution of acetone and N, N-dimethylformamide in a volume ratio of 1: 50;
s124, placing the nano carbon fiber layer on a receiving device; adding a polyvinylidene fluoride solution into a syringe pump, and controlling the environmental humidity to be 50%; the injection pump is connected with the spinning needle through a pipeline; the distance between the needle head and the receiving device is 15cm, and 18kV high-voltage electricity is applied between the needle head and the receiving device; the polymer solution reaching the spinning needle head from the injection pump through the pipeline ejects the polyvinylidene fluoride nano fiber at the flow rate of 4 mL/h; and collecting the polyvinylidene fluoride nano-fiber to obtain a composite structure of the polyimide carbon nanofiber layer/the polyvinylidene fluoride electrical insulation nanofiber layer 14.
S130, forming an inorganic nano-layer 16 on the electrically insulating nanofiber layer 14, specifically including:
s132, preparing an inorganic nano ceramic particle solution, and specifically, mechanically stirring adhesive high-molecular polyvinylidene fluoride in N-methyl pyrrolidone until the adhesive high-molecular polyvinylidene fluoride is completely dissolved, adding a certain amount of silicon dioxide ceramic particles, and performing ultrasonic dispersion for 30 min. Wherein the mass concentration of the silica ceramic particle solution is 0.1 percent, and the mass ratio of the polyvinylidene fluoride to the silica ceramic particles is 1: 0.5;
and S134, forming an inorganic nano-layer 16 on the polyvinylidene fluoride electrical insulation nano-fiber layer 14 of the polyimide nano-carbon fiber layer/polyvinylidene fluoride electrical insulation nano-fiber layer 14 composite structure by using the silicon dioxide ceramic particle solution through a coating technology to obtain the composite diaphragm 10 for the lithium ion battery, wherein the polyimide nano-carbon fiber layer, the polyvinylidene fluoride electrical insulation nano-fiber layer 14 and the silicon dioxide inorganic nano-layer 16 are laminated.
Example 2
S110, preparing a conductive fiber layer 12 nanometer carbon fiber layer, comprising:
s112, preparing 15% polyacrylonitrile solution by mass, and selecting N, N dimethylformamide as a solvent;
and S114, preparing the polyamic acid nanofiber membrane by an electrostatic spinning method. Adding the polyacrylonitrile solution into an injection pump, and controlling the environmental humidity to be 50%; the injection pump is connected with the spinning needle through a pipeline; the distance between the needle head and the receiving device is 20cm, and 35kV high-voltage electricity is applied between the needle head and the receiving device; the polymer solution reaching the spinning needle head from the injection pump through the pipeline is sprayed out of the polyacrylonitrile nano-fiber at the flow rate of 2 mL/h; collecting polyacrylonitrile nanofiber by using a receiving device to obtain a polyacrylonitrile nanofiber membrane with the thickness of 20 microns;
s116a, pre-oxidizing the polyacrylonitrile nano-fiber membrane to obtain a treated polyacrylonitrile nano-fiber membrane, wherein the pre-oxidation temperature is 120 ℃;
s116, carbonizing the treated polyacrylonitrile nanofiber membrane in a nitrogen atmosphere with the purity of 99.999 percent at 700 ℃ to obtain the carbon nanofiber layer.
S120, forming an electrically insulating nanofiber layer 14 on the conductive fiber layer 12, specifically including:
s122, preparing a polyacrylonitrile solution with the mass percent of 13%, wherein the selected solvent is dimethylacetamide;
s124, placing the polyacrylonitrile nano carbon fiber layer on a receiving device; adding polyacrylonitrile solution into an injection pump, and controlling the environmental humidity to be 30%; the injection pump is connected with the spinning needle through a pipeline; the distance between the needle head and the receiving device is 10cm, and 18kV high-voltage electricity is applied between the needle head and the receiving device; the polymer solution reaching the spinning needle head from the injection pump through the pipeline is sprayed out of the polyacrylonitrile nano-fiber at the flow rate of 1 mL/h; and collecting the polyacrylonitrile nanofiber to obtain the composite structure of the polyacrylonitrile carbon nanofiber layer/polyacrylonitrile electrical insulation nanofiber layer 14.
S130, forming an inorganic nano-layer 16 on the electrically insulating nanofiber layer 14, specifically including:
s132, preparing an inorganic nano ceramic particle solution, and specifically, mechanically stirring adhesive high-molecular polyvinylidene fluoride in N-methyl pyrrolidone until the adhesive high-molecular polyvinylidene fluoride is completely dissolved, adding a certain amount of aluminum oxide ceramic particles, and performing ultrasonic dispersion for 30 min. The mass concentration of the silicon dioxide ceramic particle solution is 0.2 percent, and the mass ratio of the polyvinylidene fluoride to the aluminum oxide ceramic particles is 1: 0.5;
s134, forming an inorganic nano-layer 16 on the polyacrylonitrile electrical insulation nano-fiber layer 14 of the polyacrylonitrile carbon nano-fiber layer/polyacrylonitrile electrical insulation nano-fiber layer 14 composite structure by using the alumina ceramic particle solution through a coating technology, and obtaining the composite diaphragm 10 for the three-layer lithium ion battery, wherein the three-layer lithium ion battery is formed by stacking the polyacrylonitrile carbon nano-fiber layer, the polyacrylonitrile electrical insulation nano-fiber layer 14 and the alumina inorganic nano-layer 16.
Example 3
S110, preparing a conductive fiber layer 12 nanometer carbon fiber layer, comprising:
s112, selecting pyromellitic dianhydride (PMDA) and Oxydianiline (ODA) as monomers, selecting N, N dimethylformamide and tetrahydrofuran as solvents, and synthesizing and preparing the polyamic acid solution at low temperature, wherein the ratio of the tetrahydrofuran to the N, N dimethylformamide is 1: 20. The mass percent of the polyamic acid solution is 8%;
and S114, preparing the polyamic acid nanofiber membrane by an electrostatic spinning method. Adding a polyamic acid solution into an injection pump, and controlling the environmental humidity to be 30%; the injection pump is connected with the spinning needle through a pipeline; the distance between the needle head and the receiving device is 30cm, and high voltage of 30kV is applied between the needle head and the receiving device; the polymer solution reaching the spinning needle head from the injection pump through a pipeline sprays the polyamic acid nano fiber at the flow rate of 1 mL/h; collecting the polyamic acid nanofiber by using a receiving device to obtain a polyamic acid nanofiber membrane with the thickness of 20 microns;
s116a, imidizing the polyamic acid nanofiber membrane in a mode of combining thermal imidization and chemical imidization to obtain a polyimide nanofiber membrane;
s116, carbonizing the polyimide nanofiber membrane in the step 3 in an argon atmosphere with the purity of 99.999 percent at the carbonization temperature of 800 ℃ to obtain the polyimide nanofiber layer.
S120, forming an electrically insulating nanofiber layer 14 on the conductive fiber layer 12, specifically including:
s122, preparing a polyacrylonitrile solution with the mass percent of 11%, wherein the selected solvent is dimethylacetamide;
s124, placing the polyimide carbon nanofiber layer on a receiving device; adding polyacrylonitrile solution into an injection pump, and controlling the environmental humidity to be 30%; the injection pump is connected with the spinning needle through a pipeline; the distance between the needle head and the receiving device is 10cm, and 18kV high-voltage electricity is applied between the needle head and the receiving device; the polymer solution reaching the spinning needle head from the injection pump through the pipeline is sprayed out of the polyacrylonitrile nano-fiber at the flow rate of 1 mL/h; and collecting the polyacrylonitrile nanofiber to obtain the composite structure of the polyimide carbon nanofiber layer/polyacrylonitrile electrical insulation nanofiber layer 14.
S130, forming an inorganic nano-layer 16 on the electrically insulating nanofiber layer 14, specifically including:
s132, preparing an inorganic nano ceramic particle solution, and specifically, mechanically stirring the adhesive high-molecular polyethylene oxide in water until the adhesive high-molecular polyethylene oxide is completely dissolved, adding a certain amount of zirconium dioxide ceramic particles, and performing ultrasonic dispersion for 110 min. The mass concentration of the zirconium dioxide ceramic particle solution is 1.5%, and the mass ratio of the used polyoxyethylene to the zirconium dioxide ceramic particles is 1: 1;
s134, forming the inorganic nano-layer 16 on the polyacrylonitrile electrical insulation nano-fiber layer 14 of the polyimide nano-carbon fiber layer/polyacrylonitrile electrical insulation nano-fiber layer 14 composite structure by using the zirconium dioxide ceramic particle solution through a coating technology, so as to obtain the composite diaphragm 10 for the three-layer lithium ion battery, wherein the three-layer lithium ion battery is formed by laminating the polyimide nano-carbon fiber layer, the polyacrylonitrile electrical insulation nano-fiber layer 14 and the zirconium dioxide inorganic nano-layer 16.
Example 4
S110, preparing a conductive fiber layer 12 nanometer carbon fiber layer, comprising:
s112, preparing 15% polyacrylonitrile solution by mass, wherein the selected solvent is N, N dimethylformamide;
and S114, preparing the polyamic acid nanofiber membrane by an electrostatic spinning method. Adding the polyacrylonitrile solution into an injection pump, and controlling the environmental humidity to be 50%; the injection pump is connected with the spinning needle through a pipeline; the distance between the needle head and the receiving device is 20cm, and 35kV high-voltage electricity is applied between the needle head and the receiving device; the polymer solution reaching the spinning needle head from the injection pump through the pipeline is sprayed out of the polyacrylonitrile nano-fiber at the flow rate of 2 mL/h; collecting polyacrylonitrile nanofiber by using a receiving device to obtain a polyacrylonitrile nanofiber membrane with the thickness of 10 microns;
s116a, pre-oxidizing the polyacrylonitrile nano-fiber membrane to obtain a treated polyacrylonitrile nano-fiber membrane, wherein the pre-oxidation temperature is 130 ℃;
s116, carbonizing the treated polyacrylonitrile nanofiber membrane in a helium atmosphere with the purity of 99.999 percent at the carbonization temperature of 750 ℃ to obtain the carbon nanofiber layer.
S120, forming an electrically insulating nanofiber layer 14 on the conductive fiber layer 12, specifically including:
s122, selecting 3,3',4,4' -benzophenonetetracarboxylic dianhydride (PMDA) and Biphenyldiamine (BID) as monomers, selecting dimethylacetamide and acetone as solvents, wherein the volume ratio of dimethylacetamide to acetone is 1:1, and synthesizing at 5 ℃ to prepare the polyamic acid solution. The mass percent of the polyamic acid solution is 15 percent;
s124, placing the polyacrylonitrile nano carbon fiber layer on a receiving device; adding a polyamic acid solution into an injection pump, and controlling the environmental humidity to be 50%; the injection pump is connected with the spinning needle through a pipeline; the distance between the needle head and the receiving device is 50cm, and a high voltage of 70kV is applied between the needle head and the receiving device; the polymer solution reaching the spinning needle head from the injection pump through the pipeline sprays the polyamic acid nano fiber at the flow rate of 130 mL/h; collecting the polyamide acid nanofiber to obtain a composite structure of the polyacrylonitrile carbon nanofiber layer/polyamide acid electrically insulating nanofiber layer 14;
s124a, performing chemical imidization treatment on the polyacrylonitrile carbon nanofiber layer/polyamic acid electrical insulation nanofiber layer 14 composite structure to obtain the polyacrylonitrile carbon nanofiber layer/polyimide electrical insulation nanofiber layer 14 composite structure.
S130, forming an inorganic nano-layer 16 on the electrically insulating nanofiber layer 14, specifically including:
s132, preparing an inorganic nano ceramic particle solution, and specifically, mechanically stirring the adhesive high-molecular polyethylene oxide in water until the adhesive high-molecular polyethylene oxide is completely dissolved, adding a certain amount of zirconium dioxide ceramic particles, and performing ultrasonic dispersion for 110 min. The mass concentration of the zirconium dioxide ceramic particle solution is 1.5%, and the mass ratio of the used polyoxyethylene to the zirconium dioxide ceramic particles is 1: 2;
and S134, forming the inorganic nano-layer 16 on the polyimide electrical insulation nano-fiber layer 14 with the polyacrylonitrile nano-carbon fiber layer/polyimide electrical insulation nano-fiber layer 14 composite structure by using the zirconium dioxide ceramic particle solution through a coating technology, so as to obtain the composite diaphragm 10 for the three-layer lithium ion battery, wherein the three-layer lithium ion battery is formed by laminating the polyacrylonitrile nano-carbon fiber layer, the polyimide electrical insulation nano-fiber layer 14 and the zirconium dioxide inorganic nano-layer 16.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (16)
1. The composite diaphragm is characterized by comprising a conductive fiber layer and an electric insulation nanofiber layer which are stacked, wherein the conductive fiber layer comprises a plurality of nano conductive fibers, the nano conductive fibers are mutually crossed to form a net structure, and the conductive fiber layer is provided with a plurality of micropores formed by the nano conductive fibers.
2. The composite separator according to claim 1, wherein said electrically insulating nanofiber layer comprises nanofibers crossing each other to form a network structure, said electrically insulating nanofiber layer having a plurality of micropores formed by said nanofibers.
3. The composite separator of claim 1, wherein the material of the nano conductive fibers is at least one of carbonized polyimide and carbonized polyacrylonitrile.
4. The composite separator according to claim 2, wherein the material of the nanofibers is at least one of polyimide, polyvinylidene fluoride, and polyacrylonitrile.
5. The composite separator of claim 1, further comprising an inorganic nanolayer disposed in a stack, the electrically insulating nanofiber layer being positioned between the inorganic nanolayer and the electrically conductive fiber layer.
6. The composite separator according to claim 1, further comprising two inorganic nano-layers, wherein said electrically insulating nanofiber layer is positioned between said two inorganic nano-layers, and said conductive fiber layer is laminated on the other side of any one of said inorganic nano-layers.
7. The composite separator according to claim 5 or 6, wherein the inorganic nano layer comprises a high molecular polymer and inorganic nano ceramic particles, the high molecular polymer is at least one of polyvinylidene fluoride and polyethylene oxide, and the inorganic nano ceramic particles are one or more of silicon dioxide, titanium dioxide, zirconium dioxide, aluminum oxide and magnesium oxide.
8. The composite separator according to claim 1, wherein the porosity of the composite separator is 60 to 96% and the average pore diameter is 4.0 to 5.5 μm.
9. The composite membrane of claim 5, wherein the composite membrane has a liquid absorption rate of 400% to 900%.
10. The composite separator according to claim 1, wherein the composite separator has a mass per unit area of 6g/m2To 20g/m2And the thickness is 15 to 70 μm.
11. A lithium ion battery comprising the composite separator according to any one of claims 1 to 10, a positive electrode and a negative electrode, the composite separator being disposed between the positive electrode and the negative electrode, and the conductive fiber layer being disposed on a side of the negative electrode and being electrically connected to the negative electrode.
12. A method of making a composite separator, comprising:
preparing a conductive fiber layer, wherein the conductive fiber layer comprises a plurality of nano conductive fibers, the nano conductive fibers are mutually crossed to form a net structure, and the conductive fiber layer is provided with a plurality of micropores formed by the nano conductive fibers; and
forming an electrically insulating nanofiber layer on the conductive fiber layer.
13. The method of making a composite separator according to claim 12, further comprising:
forming an inorganic nano-layer on the electrically insulating nanofiber layer.
14. The method of manufacturing a composite separator according to claim 12, wherein the manufacturing a conductive fiber layer comprises:
providing a first polymer solution;
preparing the first polymer solution into a nanofiber membrane by an electrostatic spinning method; and
and carbonizing the nanofiber membrane to obtain the conductive fiber layer.
15. The method of manufacturing a composite separator according to claim 12, wherein the forming of the electrically insulating nanofiber layer on the electrically conductive fiber layer comprises:
providing a second polymer solution; and
forming the electrically insulating nanofiber layer from the second polymer solution on the conductive fiber layer by an electrospinning method.
16. The method for preparing a composite separator according to claim 14, further comprising, before the step of carbonizing the nanofiber film to obtain the conductive fiber layer: and (3) pretreating the nanofiber membrane to cyclize the internal components in the nanofiber membrane, so that the stability of the nanofiber membrane is improved.
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| CN109599523A (en) * | 2018-11-27 | 2019-04-09 | 湖南农业大学 | A kind of ceramic coating membrane and preparation method thereof |
| CN111799499A (en) * | 2020-05-27 | 2020-10-20 | 广西华政新能源科技有限公司 | Lithium iron phosphate lithium ion battery for hot water kettle |
| CN111799499B (en) * | 2020-05-27 | 2021-11-12 | 广西华政新能源科技有限公司 | Lithium iron phosphate lithium ion battery for hot water kettle |
| CN111864161A (en) * | 2020-06-15 | 2020-10-30 | 泰州衡川新能源材料科技有限公司 | SiO (silicon dioxide)2Doped diaphragm processing technology |
| CN113690546A (en) * | 2021-07-21 | 2021-11-23 | 华南理工大学 | Lithium-sulfur battery diaphragm and preparation method and application thereof |
| CN113745752A (en) * | 2021-09-07 | 2021-12-03 | 河南工程学院 | Composite nanofiber lithium battery diaphragm and preparation method thereof |
| CN113745752B (en) * | 2021-09-07 | 2023-03-14 | 河南工程学院 | Composite nanofiber lithium battery diaphragm and preparation method thereof |
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