CN217405514U - Positive pole piece and lithium ion battery thereof - Google Patents
Positive pole piece and lithium ion battery thereof Download PDFInfo
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- CN217405514U CN217405514U CN202220834981.XU CN202220834981U CN217405514U CN 217405514 U CN217405514 U CN 217405514U CN 202220834981 U CN202220834981 U CN 202220834981U CN 217405514 U CN217405514 U CN 217405514U
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- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 title claims abstract description 27
- 229910001416 lithium ion Inorganic materials 0.000 title claims abstract description 27
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 74
- 239000011888 foil Substances 0.000 claims abstract description 68
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 60
- 229920002635 polyurethane Polymers 0.000 claims abstract description 55
- 239000004814 polyurethane Substances 0.000 claims abstract description 55
- 239000010410 layer Substances 0.000 claims description 126
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical group [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 29
- 229910052782 aluminium Inorganic materials 0.000 claims description 29
- 239000012790 adhesive layer Substances 0.000 claims description 21
- 239000011247 coating layer Substances 0.000 claims description 17
- 239000006229 carbon black Substances 0.000 claims description 14
- 230000003287 optical effect Effects 0.000 claims description 13
- 229910021393 carbon nanotube Inorganic materials 0.000 claims description 7
- 239000002041 carbon nanotube Substances 0.000 claims description 7
- 229910002804 graphite Inorganic materials 0.000 claims description 7
- 239000010439 graphite Substances 0.000 claims description 7
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 7
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 6
- 239000011889 copper foil Substances 0.000 claims description 6
- 125000000129 anionic group Chemical group 0.000 claims description 3
- 125000002091 cationic group Chemical group 0.000 claims description 3
- 238000001523 electrospinning Methods 0.000 claims 1
- 239000000853 adhesive Substances 0.000 abstract description 20
- 230000001070 adhesive effect Effects 0.000 abstract description 20
- 238000000034 method Methods 0.000 abstract description 17
- 239000011230 binding agent Substances 0.000 abstract description 5
- 238000005516 engineering process Methods 0.000 abstract description 5
- 230000002349 favourable effect Effects 0.000 abstract description 5
- 230000001737 promoting effect Effects 0.000 abstract 1
- 239000011149 active material Substances 0.000 description 18
- 230000000052 comparative effect Effects 0.000 description 15
- 239000007774 positive electrode material Substances 0.000 description 14
- 239000006258 conductive agent Substances 0.000 description 12
- 239000011248 coating agent Substances 0.000 description 11
- 238000000576 coating method Methods 0.000 description 11
- 239000002002 slurry Substances 0.000 description 11
- 238000010041 electrostatic spinning Methods 0.000 description 10
- 229910010710 LiFePO Inorganic materials 0.000 description 6
- 239000002904 solvent Substances 0.000 description 6
- 239000013543 active substance Substances 0.000 description 5
- 239000003575 carbonaceous material Substances 0.000 description 4
- 239000002131 composite material Substances 0.000 description 4
- 239000000839 emulsion Substances 0.000 description 4
- QIJNJJZPYXGIQM-UHFFFAOYSA-N 1lambda4,2lambda4-dimolybdacyclopropa-1,2,3-triene Chemical compound [Mo]=C=[Mo] QIJNJJZPYXGIQM-UHFFFAOYSA-N 0.000 description 3
- LSNNMFCWUKXFEE-UHFFFAOYSA-M Bisulfite Chemical compound OS([O-])=O LSNNMFCWUKXFEE-UHFFFAOYSA-M 0.000 description 3
- 229910039444 MoC Inorganic materials 0.000 description 3
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- 238000007599 discharging Methods 0.000 description 3
- 238000001035 drying Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 238000002156 mixing Methods 0.000 description 3
- 239000000243 solution Substances 0.000 description 3
- NIXOWILDQLNWCW-UHFFFAOYSA-M Acrylate Chemical compound [O-]C(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-M 0.000 description 2
- QGZKDVFQNNGYKY-UHFFFAOYSA-O Ammonium Chemical compound [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 0.000 description 2
- 241000872198 Serjania polyphylla Species 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 description 2
- SBWRUMICILYTAT-UHFFFAOYSA-K lithium;cobalt(2+);phosphate Chemical compound [Li+].[Co+2].[O-]P([O-])([O-])=O SBWRUMICILYTAT-UHFFFAOYSA-K 0.000 description 2
- ILXAVRFGLBYNEJ-UHFFFAOYSA-K lithium;manganese(2+);phosphate Chemical compound [Li+].[Mn+2].[O-]P([O-])([O-])=O ILXAVRFGLBYNEJ-UHFFFAOYSA-K 0.000 description 2
- 230000014759 maintenance of location Effects 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 238000004537 pulping Methods 0.000 description 2
- 238000005096 rolling process Methods 0.000 description 2
- 239000012265 solid product Substances 0.000 description 2
- 238000009987 spinning Methods 0.000 description 2
- 238000005507 spraying Methods 0.000 description 2
- 229920000049 Carbon (fiber) Polymers 0.000 description 1
- 229910010707 LiFePO 4 Inorganic materials 0.000 description 1
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 1
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 1
- 239000012670 alkaline solution Substances 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000005030 aluminium foil Substances 0.000 description 1
- 239000004917 carbon fiber Substances 0.000 description 1
- 150000001732 carboxylic acid derivatives Chemical class 0.000 description 1
- 239000013065 commercial product Substances 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000007812 deficiency Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- QHGJSLXSVXVKHZ-UHFFFAOYSA-N dilithium;dioxido(dioxo)manganese Chemical compound [Li+].[Li+].[O-][Mn]([O-])(=O)=O QHGJSLXSVXVKHZ-UHFFFAOYSA-N 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 238000003487 electrochemical reaction Methods 0.000 description 1
- 238000004146 energy storage Methods 0.000 description 1
- 239000003292 glue Substances 0.000 description 1
- 239000004519 grease Substances 0.000 description 1
- 230000017525 heat dissipation Effects 0.000 description 1
- 229910052744 lithium Inorganic materials 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- 230000003446 memory effect Effects 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 229910000510 noble metal Inorganic materials 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 239000007800 oxidant agent Substances 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 238000002791 soaking Methods 0.000 description 1
- 230000003068 static effect Effects 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- RWSOTUBLDIXVET-UHFFFAOYSA-O sulfonium Chemical compound [SH3+] RWSOTUBLDIXVET-UHFFFAOYSA-O 0.000 description 1
Images
Classifications
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Abstract
The utility model provides a positive pole piece and lithium ion battery thereof, positive pole piece includes the light foil layer, and scribble carbon layer, waterborne polyurethane adhesive linkage and the active layer that sets gradually from bottom to top in light foil layer one side. The utility model discloses an add the one deck and scribble the charge transfer in the carbon-coated layer can strengthen positive pole piece on the light foil layer, promote the electrical property, again through adding one deck waterborne polyurethane as the adhesive linkage between scribbling carbon-coated layer and active layer for the active layer with scribble the adhesion between the carbon-coated layer and increase, effectively improve the peeling strength of positive pole piece, can also avoid because of the active layer in the inflation of charge-discharge in-process with peel off the problem that the cycle performance that leads to descends, thereby effectively improve the security performance, simultaneously, do not contain the binder in the active layer of positive pole piece, therefore can make the technology of making the active layer obtain simplifying, be favorable to improving the electrical property of active layer simultaneously, finally make positive pole piece wholeness can obtain promoting.
Description
Technical Field
The utility model belongs to the lithium ion battery field relates to a positive pole piece and lithium ion battery thereof.
Background
The lithium ion battery has the advantages of high energy density, good cycle performance, wide working temperature, no memory effect, small self-discharge, high safety and the like, along with the diversification of times, the application range of the lithium ion battery is continuously widened, and the lithium ion battery is rapidly developed into a new generation of energy storage energy source and is used for power support in the fields of information technology, electric vehicles, hybrid electric vehicles, aerospace and the like. In a lithium ion battery, a current collector is one of indispensable components, and not only plays a role of bearing active substances, but also collects electrons generated by an electrochemical reaction and conducts the collected electrons to an external circuit, so that a process of converting chemical energy into electric energy is realized, and therefore, the contact quality of the current collector and the active substances, namely the stripping force, is an important factor influencing the charging and discharging performance of the battery.
The traditional lithium ion battery positive pole piece mainly uses an aluminum optical foil as a current collector, in the pole piece preparation process of the lithium ion battery, active substance slurry is directly coated on the surface of the aluminum optical foil, after drying by an oven, an adhesive in the active substance slurry can fix an active material on the surface of the current collector, but the contact area between a rigid metal current collector and the active material is limited, so that the interface resistance is increased, the internal resistance of the battery is increased, the battery performance is negatively influenced, and particularly, the electrical performance under the condition of high-rate charge and discharge is remarkably reduced; and the adhesive has limited bonding strength, so that the problem of expansion and separation between the active material and the current collector is easily caused in the continuous charging and discharging process, the internal resistance of the battery is further increased, and the cycle life and the safety performance of the battery are further influenced.
At present, the mainstream process is to add a functional coating on the surface of an aluminum optical foil so as to improve the electrochemical performance of the lithium ion battery. A typical case of the carbon-coated aluminum foil is that a conductive carbon material is coated on a photo foil. The defect of light foil can be filled up by adding the conductive carbon material, so that the lithium ion battery has excellent static conductivity, and micro-current of the active material can be collected, thereby greatly reducing the contact resistance between the active material and the current collection, improving the adhesion capacity between the active material and the current collection, reducing the using amount of the adhesive in the active material slurry, and further remarkably improving the overall performance of the battery. CN113422065A discloses a coated aluminum foil and a preparation method and application thereof, wherein the coated aluminum foil comprises a conductive coating and an aluminum foil, the conductive coating comprises molybdenum carbide, the molybdenum carbide is added into the conductive coating of the coated aluminum foil, and the electronic structure of the molybdenum carbide is similar to that of noble metal Pt, so that the coated aluminum foil has excellent conductivity and the conductivity of the carbon-coated aluminum foil can be improved; CN112952106A provides a carbon-coated aluminum foil and a method for preparing the same, wherein the method comprises mixing an oxidant, a first solvent and a conductive agent, adding a second solvent, mixing to obtain a solid product, mixing the solid product with an adhesive in a third solvent to obtain a modified composite slurry, and finally spraying the modified composite slurry onto a pretreated aluminum foil to obtain the carbon-coated aluminum foil, wherein the carbon-coated aluminum foil can improve the stripping force of a positive electrode plate and can improve various performances of a battery cell.
However, in the carbon-coated current collector, the conductive carbon materials commonly used for the carbon-coated layer mainly include carbon black, graphite, carbon nanotubes and the like, the conductive materials have low thermal conductivity and are not favorable for battery heat dissipation when in use, and the conductive carbon materials have poor dispersibility in water, so that a coating is difficult to be uniformly and finely formed on the optical foil during coating, the bonding strength and stability of the carbon-coated layer and the optical foil are reduced, the contact between the active material and the carbon-coated layer is influenced, the stripping force of the positive electrode plate is reduced, and the performance of the lithium ion battery is not favorably and sufficiently improved.
In view of the above, it is further necessary to develop a new positive electrode plate, so that the contact condition between the active material and the current collector is improved and enhanced, and the stripping force of the positive electrode plate is sufficiently improved.
SUMMERY OF THE UTILITY MODEL
The utility model aims to the deficiencies in the prior art exist, the utility model provides a positive pole piece and lithium ion battery thereof, positive pole piece includes the light foil layer, and scribble carbon layer, waterborne polyurethane adhesive linkage and the active layer that sets gradually from bottom to top light foil layer one side. The utility model discloses an add the one deck and scribble the charge transfer in the carbon-coated layer can strengthen positive pole piece on the light foil layer, promote the electrical property, again through scribbling one deck waterborne polyurethane as the adhesive linkage between carbon-coated layer and active layer for the active layer with scribble the adhesion between the carbon-coated layer and increase, effectively improve the peeling strength of positive pole piece, can also avoid because of the active layer in the inflation of charge-discharge process and the problem that the cyclicity that results in descends of peeling off, thereby effectively improve the security performance.
To achieve the purpose, the utility model adopts the following technical proposal:
in a first aspect, the utility model provides a positive pole piece, positive pole piece includes the light foil layer, and scribble carbon-layer, waterborne polyurethane adhesive linkage and the active layer that sets gradually from bottom to top in light foil layer one side.
The utility model discloses a set up the one deck and increase the carbon-coated layer of conductivity on the light foil layer, again through adding one deck waterborne polyurethane as the adhesive linkage between carbon-coated layer and active layer for the active layer with scribble the adhesion between the carbon-coated layer and increase, effectively improve the peeling force of positive pole piece, can also avoid because of the active layer in the inflation of charge-discharge process and the problem that the cycle performance that results in descends of peeling off, thereby effectively improve the security performance.
In a preferred embodiment of the present invention, the thickness of the aqueous polyurethane adhesive layer is 1 to 3 μm, for example, 1 μm, 1.2 μm, 1.4 μm, 1.6 μm, 1.8 μm, 2 μm, 2.2 μm, 2.4 μm, 2.6 μm, 2.8 μm, or 3 μm, but is not limited to the above-mentioned values, and other values not shown in the above-mentioned numerical value range are also applicable.
Waterborne polyurethane adhesive linkage should be even and complete, but too thick thickness can lead to the resistance of gained positive pole piece to rise, finally influences the pole piece performance.
As the preferable technical proposal of the utility model, the waterborne polyurethane adhesive layer is an electrostatic spinning structure layer.
The utility model discloses preferably use the coating of electrostatic spinning device waterborne polyurethane adhesive linkage, form electrostatic spinning structural layer, waterborne polyurethane are low viscous emulsion form, and consequently the tie coat of using the coating of electrostatic spinning device is more even, and its fluffy spinning structure is favorable to specific surface area's increase, therefore improves the contact situation between active layer and the mass flow body more effectively, effectively improves peel strength.
As a preferred technical solution of the present invention, the aqueous polyurethane adhesive layer is any one of an anionic aqueous polyurethane layer, a cationic aqueous polyurethane layer, or a nonionic aqueous polyurethane layer.
The anionic waterborne polyurethane in the raw materials of the waterborne polyurethane adhesive layer comprises sulfonic acid waterborne polyurethane or carboxylic acid waterborne polyurethane and the like; the cationic waterborne polyurethane comprises ammonium ion waterborne polyurethane or sulfonium ion waterborne polyurethane and the like; the non-ionic water-based polyurethane comprises non-ionic double-bond end-capped water-based polyurethane self-emulsifying emulsion or acrylate modified non-ionic water-based polyurethane emulsion and the like.
As the preferred technical proposal of the utility model, the carbon coating layer is any one of a carbon black layer, a graphite layer or a carbon nanotube layer.
The utility model discloses in through add on the light foil layer scribble the carbon-coated layer, set up the waterborne polyurethane adhesive linkage again on scribbling the carbon-coated layer, not only can not influence the bonding effect of active layer, still have excellent electric conductivity because of scribbling the carbon-coated layer, and be favorable to the charge transfer in the positive pole piece more to effectively improve the performance of positive pole piece. It should be noted that, if do not set up the carbon-coated layer and directly use the light foil layer as the mass flow body to directly set up on the light foil layer waterborne polyurethane adhesive linkage, though can also improve the bonding effect of active layer, nevertheless use the lithium ion battery's that gained positive pole piece produced contact internal resistance can increase, and the during operation heat production increases, and the capacity performance of gained electricity core can receive great influence, finally leads to multiplying power discharge performance to worsen, and cycle life reduces.
In a preferred embodiment of the present invention, the carbon-coated layer has a thickness of 1 to 2 μm, for example, 1.1 μm, 1.2 μm, 1.3 μm, 1.4 μm, 1.5 μm, 1.6 μm, 1.7 μm, 1.8 μm, 1.9 μm or 2 μm, but the carbon-coated layer is not limited to the above-mentioned values, and other values not shown in the above-mentioned range of values are also applicable.
As the preferred technical scheme of the utility model, the light foil layer is aluminium foil layer or copper foil layer.
In the utility model, the optical foil layer is made of a thermoprinting material which is made of metal and directly rolled into a sheet, when a carbon coating layer is arranged on the optical foil layer, the material of the optical foil layer is preferably an aluminum foil due to better bonding performance, the aluminum foil can be a single-light (double-combined rolling) aluminum foil or a double-light (single-sheet rolling) aluminum foil, and the alloy number of the aluminum foil comprises 1100, 1060, 1050 or 1070A; note that the optical foil provided with the carbon-coated layer is also a commercial product itself, that is, "carbon-coated aluminum foil" or "carbon-coated copper foil", and can be selected and purchased by those skilled in the art according to actual circumstances.
In a preferred embodiment of the present invention, the thickness of the optical foil layer is 9 to 20 μm, for example, 9 μm, 10 μm, 12 μm, 14 μm, 16 μm, 18 μm, or 20 μm, but the optical foil layer is not limited to the above-mentioned values, and other values not mentioned in the above-mentioned range are also applicable.
In a preferred embodiment of the present invention, the thickness of the active layer is 50 to 400 μm, for example, 20 μm, 40 μm, 60 μm, 80 μm, 100 μm, 120 μm, 140 μm, 150 μm, etc., but the active layer is not limited to the above-mentioned values, and other values not listed in the above-mentioned range are also applicable.
It is worth to say that, the utility model discloses a positive pole piece is made through following method, the method includes following step:
s1, firstly, carrying out soaking pretreatment on an aluminum foil or a copper foil by using a NaOH solution or other alkaline solutions to remove surface grease and increase the roughness of a smooth foil, and then spraying any one of carbon black, graphite or carbon nano tubes on the smooth foil layer to form a carbon coating layer and obtain a current collector; or directly using a commercially available carbon-coated aluminum foil or carbon-coated copper foil as a current collector;
preparing active material slurry, and preparing the positive active material, a conductive agent and a solvent into the active material slurry by adopting a dry method or wet method homogenizing process in the lithium ion battery pulping technology;
s2, coating waterborne polyurethane on the carbon coating layer of the current collector obtained in the step S1 by using an electrostatic spinning device, and drying at 50-80 ℃ to form a waterborne polyurethane bonding layer as a bonding layer to obtain a composite;
s3, coating the active substance slurry obtained in the step S1 on the complex in the step S2 by using a coating machine, and drying at 50-80 ℃ to form an active layer to obtain the positive pole piece.
Waterborne polyurethane adhesive linkage's bonding is effectual, to the common use in the lithium ion battery field, but the active material thick liquids that the composition is different all have good adaptability, for example the utility model discloses used active material thick liquids can be made through selecting for use following material when forming the active layer, and wherein anodal active material can be lithium cobaltate, lithium manganate, lithium iron phosphate (LiFePO) 4 ) The conductive agent can be superconducting carbon black, flake graphite, carbon nano tubes or carbon fibers, and the solvent can be N-methylpyrrolidone; it is worth emphasizing that the active layer of the positive pole piece of the utility model does not contain a binder, i.e. when the active material is used for pulping, the binder is not required to be additionally added, the glue making process is omitted, the process economy of the lithium ion pole piece manufacturing is greatly improved, the electrical property of the active layer is not influenced by the binder, the charge transfer of the positive active material and the conductive agent is favorably optimized, and the overall performance of the positive pole piece is finally improved; when the active material slurry is applied and dried to form an active layer, the active layer is a composite layer in which a positive electrode active material and a conductive agent are uniformly mixed due to volatilization of a solvent.
In a second aspect, the present invention provides a lithium ion battery comprising the positive electrode plate of the first aspect.
Compared with the prior art, the beneficial effects of the utility model are that:
(1) the utility model discloses an add one deck waterborne polyurethane layer as the adhesive linkage between carbon-coated layer and active layer, not only increased the adhesion between carbon-coated layer and the active layer, effectively improved the stripping force of positive pole piece, can also avoid because of the positive pole piece is in the charge-discharge process, because of the inflation of active layer and the decline that leads to lithium ion battery cycle performance with peeling off, effectively improve the security performance simultaneously, and under the cooperation of carbon-coated layer that has excellent conductivity, the charge transfer in the positive pole piece obtains further optimization, thereby effectively improves positive pole piece performance;
(2) all contain the adhesive in the active layer of present positive pole piece to make active layer and mass flow body bond and form positive pole piece, and the utility model discloses do not contain the binder in the active layer of gained positive pole piece, saved the system and glued technology, not only improved the technology economy that lithium ion pole piece made greatly, the electrical property that can also make the active layer does not receive the influence of adhesive, is favorable to the promotion of positive pole piece overall performance.
Drawings
FIG. 1 is a schematic structural view of the positive electrode plate obtained in embodiments 1-4 of the present invention;
wherein, 1 is a light foil layer, 2 is a carbon coating layer, 3 is a water-based polyurethane layer, and 4 is an active layer.
Detailed Description
The technical solution of the present invention is further explained by the following embodiments.
Fig. 1 is the schematic structural diagram of the positive electrode plate obtained in embodiments 1-3 and comparative example 1 of the present invention, the positive electrode plate includes a light foil layer 1, and a carbon coating layer 2, a water-based polyurethane adhesive layer 3 and an active layer 4, which are sequentially disposed on one side of the light foil layer 1 from bottom to top.
Example 1
This example provides a positive electrode sheet comprising a 14 μm thick aluminum foil as a plain foil layer and 1.5 μm thick carbon black as a carbon-coated layerA current collector, a 2 mu m thick aqueous polyurethane adhesive layer which is formed by sulfonic acid type aqueous polyurethane through electrostatic spinning and is arranged on one side of the carbon coating layer of the current collector from bottom to top, and a positive active material lithium iron phosphate (LiFePO) 4 ) And a 220 μm thick active layer compounded with conductive agent superconducting carbon black.
Example 2
The embodiment provides a positive pole piece, which comprises a current collector, a 3 mu m-thick aqueous polyurethane adhesive layer and a positive active material lithium cobalt phosphate (LiCoPO) wherein the current collector is composed of a 20 mu m-thick aluminum foil serving as a light foil layer and a 2 mu m-thick graphite serving as a carbon coating layer, the 3 mu m-thick aqueous polyurethane adhesive layer is formed by performing electrostatic spinning on ammonium ion type aqueous polyurethane and is sequentially arranged on one side of the carbon coating layer of the current collector from bottom to top 4 ) And a 400 μm thick active layer compounded with carbon nanotubes as a conductive agent.
Example 3
The embodiment provides a positive pole piece, which comprises a current collector, a 1 micron-thick aqueous polyurethane adhesive layer and a positive active material lithium manganese phosphate (LiMnPO) wherein the current collector is composed of a copper foil with the thickness of 9 microns as a light foil layer and a carbon nano tube with the thickness of 1 micron as a carbon coating layer, the 1 micron-thick aqueous polyurethane adhesive layer is formed by performing electrostatic spinning on an acrylate modified nonionic aqueous polyurethane emulsion and is sequentially arranged on one side of the carbon coating layer of the current collector from bottom to top, and the positive active material lithium manganese phosphate (LiMnPO) is used as a positive active material 4 ) And a conductive agent flake graphite, and has a thickness of 50 μm.
Example 4
The embodiment provides a positive pole piece, which comprises a current collector, a 5-micron waterborne polyurethane adhesive layer and a positive active material LiFePO, wherein the current collector is composed of an aluminum foil with the thickness of 14 microns as a light foil layer and carbon black with the thickness of 1.5 microns as a carbon coating layer, the 5-micron waterborne polyurethane adhesive layer is formed by performing electrostatic spinning on sulfonic waterborne polyurethane and is sequentially arranged on one side of the carbon coating layer of the current collector from bottom to top, and the positive active material LiFePO is a positive active material 4 And a 220 μm active layer compounded with conductive agent superconducting carbon black.
Comparative example 1
This comparative example provides a positive electrode tab comprising an aluminum foil 14 μm thickA current collector, a 2 mu m thick waterborne polyurethane adhesive layer which is formed by electrostatic spinning of sulfonic acid waterborne polyurethane and is arranged on one side of the current collector in sequence from bottom to top, and a positive active material LiFePO 4 And a 220 μm thick active layer compounded with conductive agent superconducting carbon black.
Comparative example 2
The comparative example provides a positive electrode plate comprising a current collector composed of an aluminum foil with the thickness of 14 microns as a light foil layer and carbon black with the thickness of 1.5 microns as a carbon coating layer, and a positive active material LiFePO arranged on the carbon coating layer of the current collector 4 And a 220 μm thick active layer compounded with conductive agent superconducting carbon black.
Comparative example 3
The present comparative example provides a positive electrode sheet including a current collector composed of an aluminum foil having a thickness of 14 μm as a plain foil layer and carbon black having a thickness of 1.5 μm as a carbon-coated layer, and a positive electrode active material LiFePO disposed on the carbon-coated layer of the current collector 4 And a 220-micron active layer compounded with conductive agent superconducting carbon black and adhesive waterborne polyurethane.
The positive electrode sheets obtained in the examples and comparative examples were fabricated into lithium ion batteries, and the lithium ion batteries were tested, and the results are shown in table 1.
TABLE 1
| Item | Peel force | Pole piece film resistor | Specific capacity after 500 cycles |
| Example 1 | 0.82 | 0.4023 | 98.0％ |
| Example 2 | 0.78 | 0.4156 | 97.6％ |
| Example 3 | 0.85 | 0.3987 | 97.9％ |
| Example 4 | 0.56 | 0.5689 | 94.3％ |
| Comparative example 1 | 0.47 | 0.5997 | 93.1％ |
| Comparative example 2 | 0.32 | 0.6143 | 91.5％ |
| Comparative example 3 | 0.68 | 0.4243 | 96.7％ |
As can be seen from table 1:
(1) compared with the positive pole pieces obtained in the embodiment 4 and the comparative examples 1 to 3, the positive pole pieces obtained in the embodiments 1 to 3 have higher overall stripping force, the resistance of the pole piece film is smaller, the capacity retention rate is higher than 4-5% after 500 cycles, and the capacity retention rate can be maintained above 97% and can reach 98% at most;
(2) compared with example 1, in example 4, the thickness of the adhesive layer is too large, which is not only not beneficial to the improvement of the peeling force, but also easily causes the increase of the resistance;
(3) compared with the embodiment 1, the comparative example 1 has poor bonding effect of the bonding layer because of no support of the carbon coating layer, poor direct contact condition between the active layer and the optical foil layer and obvious reduction of the peeling force;
(4) compared with the embodiment 1, the comparative example 2 has no adhesive layer, so that the peeling force is reduced sharply, and the resistance of the pole piece film is increased obviously;
(5) compared with the embodiment 1, the comparative example 3 is not provided with an adhesive layer, but the active material slurry is added with the adhesive, and the active material slurry is directly coated on the carbon-coated layer to form the active layer, so that the positive pole piece is obtained, and the stripping force, the pole piece membrane resistance and the specific capacity of the obtained lithium ion battery after circulating for 500 circles are obviously different from those of the embodiment 1;
(6) the above results prove that by adding a spinning type aqueous polyurethane layer between the carbon-coated layer and the active layer as the adhesive layer, the adhesion between the carbon-coated layer and the active layer is increased, the stripping force of the positive pole piece is effectively improved, the reduction of the cycle performance of the lithium ion battery caused by the expansion and stripping of the active layer in the charging and discharging process of the positive pole piece can be avoided, the safety performance is effectively improved, and the charge transfer in the positive pole piece is further optimized under the cooperation of the carbon-coated layer with excellent conductivity, so that the performance of the positive pole piece is effectively improved.
The above description is only the specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto, and it should be understood by those skilled in the art that any changes or substitutions that can be easily conceived by those skilled in the art are within the technical scope of the present invention, and all fall within the protection scope and the disclosure scope of the present invention.
Claims (10)
1. The positive pole piece is characterized by comprising a light foil layer, and a carbon coating layer, a water-based polyurethane adhesive layer and an active layer which are sequentially arranged on one side of the light foil layer from bottom to top.
2. The positive pole piece of claim 1, wherein the thickness of the aqueous polyurethane adhesive layer is 1-3 μm.
3. The positive electrode plate as claimed in claim 1 or 2, wherein the aqueous polyurethane adhesive layer is an electrospinning structural layer.
4. The positive electrode sheet according to claim 1 or 2, wherein the aqueous polyurethane adhesive layer is any one of an anionic aqueous polyurethane layer, a cationic aqueous polyurethane layer, or a nonionic aqueous polyurethane layer.
5. The positive electrode sheet according to claim 1, wherein the carbon-coated layer is any one of a carbon black layer, a graphite layer, and a carbon nanotube layer.
6. The positive electrode sheet according to claim 1 or 5, wherein the carbon-coated layer has a thickness of 1 to 2 μm.
7. The positive electrode sheet according to claim 1, wherein the optical foil layer is an aluminum foil layer or a copper foil layer.
8. The positive electrode plate as claimed in claim 1 or 7, wherein the thickness of the light foil layer is 9 to 20 μm.
9. The positive electrode sheet according to claim 1, wherein the active layer has a thickness of 50 to 400 μm.
10. A lithium ion battery comprising the positive electrode sheet according to any one of claims 1 to 9.
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| CN202220834981.XU CN217405514U (en) | 2022-04-12 | 2022-04-12 | Positive pole piece and lithium ion battery thereof |
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