CN113903878A - Battery pole piece compression roller, battery pole piece rolling method, battery pole piece and battery - Google Patents
Battery pole piece compression roller, battery pole piece rolling method, battery pole piece and battery Download PDFInfo
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- CN113903878A CN113903878A CN202111135036.7A CN202111135036A CN113903878A CN 113903878 A CN113903878 A CN 113903878A CN 202111135036 A CN202111135036 A CN 202111135036A CN 113903878 A CN113903878 A CN 113903878A
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- 238000000034 method Methods 0.000 title claims abstract description 40
- 238000005096 rolling process Methods 0.000 title claims abstract description 34
- 238000007906 compression Methods 0.000 title claims abstract description 25
- 230000006835 compression Effects 0.000 title claims abstract description 25
- 239000002002 slurry Substances 0.000 claims abstract description 57
- 238000003825 pressing Methods 0.000 claims abstract description 36
- 239000011248 coating agent Substances 0.000 claims abstract description 31
- 238000000576 coating method Methods 0.000 claims abstract description 31
- 239000007787 solid Substances 0.000 claims description 11
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 10
- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 claims description 7
- 239000002033 PVDF binder Substances 0.000 claims description 6
- 239000011230 binding agent Substances 0.000 claims description 6
- 239000002041 carbon nanotube Substances 0.000 claims description 6
- 229910021393 carbon nanotube Inorganic materials 0.000 claims description 6
- 239000006258 conductive agent Substances 0.000 claims description 6
- 229920002981 polyvinylidene fluoride Polymers 0.000 claims description 6
- 239000002904 solvent Substances 0.000 claims description 6
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims 1
- 229910052744 lithium Inorganic materials 0.000 claims 1
- 239000013543 active substance Substances 0.000 description 17
- 239000007791 liquid phase Substances 0.000 description 12
- 238000005056 compaction Methods 0.000 description 10
- 239000003792 electrolyte Substances 0.000 description 8
- 239000011149 active material Substances 0.000 description 5
- 239000011888 foil Substances 0.000 description 5
- 230000008595 infiltration Effects 0.000 description 5
- 238000001764 infiltration Methods 0.000 description 5
- 229910052799 carbon Inorganic materials 0.000 description 4
- 238000001035 drying Methods 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 3
- 229910052782 aluminium Inorganic materials 0.000 description 3
- 239000006255 coating slurry Substances 0.000 description 3
- 238000007599 discharging Methods 0.000 description 3
- 238000003411 electrode reaction Methods 0.000 description 3
- 239000012530 fluid Substances 0.000 description 3
- 239000007790 solid phase Substances 0.000 description 3
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 2
- 238000005520 cutting process Methods 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- 229910001416 lithium ion Inorganic materials 0.000 description 2
- 230000010287 polarization Effects 0.000 description 2
- 239000011148 porous material Substances 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 241000251468 Actinopterygii Species 0.000 description 1
- 230000002238 attenuated effect Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 230000001351 cycling effect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000009472 formulation Methods 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 230000008707 rearrangement Effects 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/04—Processes of manufacture in general
- H01M4/043—Processes of manufacture in general involving compressing or compaction
- H01M4/0435—Rolling or calendering
-
- 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
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/04—Processes of manufacture in general
- H01M4/0402—Methods of deposition of the material
- H01M4/0404—Methods of deposition of the material by coating on electrode collectors
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/139—Processes of manufacture
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Battery Electrode And Active Subsutance (AREA)
- Cell Electrode Carriers And Collectors (AREA)
- Secondary Cells (AREA)
Abstract
The invention relates to the technical field of batteries, and discloses a battery pole piece pressing roller, a battery pole piece rolling method, a battery pole piece and a battery. The battery pole piece compression roller comprises a roller shaft, the roller shaft is cylindrical, a plurality of protruding portions are uniformly arranged on the surface of the roller shaft at intervals, the cross section of each protruding portion is square, and the distance between every two adjacent protruding portions ranges from 1mm to 5 mm. The rolling method of the battery pole piece comprises the following steps of S1: coating first pole piece slurry on the surface of a current collector according to a preset surface density; s2: cold-pressing the current collector coated with the first pole piece slurry by using a battery pole piece compression roller to form a semi-finished pole piece; s3: coating the second pole piece slurry on the surface of the cold-pressed semi-finished pole piece according to the preset surface density for the second time; s4: and carrying out secondary cold pressing on the semi-finished pole piece coated with the second pole piece slurry by adopting a plane pressing roller to obtain the pole piece. The battery pole piece is manufactured by the method, and the battery comprises the battery pole piece. The battery pole piece has larger characteristic thickness, so that the energy density of the battery is higher.
Description
Technical Field
The invention relates to the technical field of battery processes, in particular to a battery pole piece pressing roller, a battery pole piece rolling method, a battery pole piece and a battery.
Background
The main performance parameters of the lithium ion battery, such as charging and discharging efficiency, capacity and the like, are attenuated in the charging and discharging process, and become main factors restricting the further development of the lithium ion battery. The battery pole piece is one of the important components of the battery and is made by a series of special processes, wherein the coating and rolling processes are the most critical, the formulation of process parameters and the control of process precision in the pole piece manufacturing process directly influence the performance of the battery pole piece, and the surface density, the compaction density and the thickness consistency are three parameters which are frequently involved in the pole piece manufacturing process and have important influence on the battery performance. At present, the pole piece is rolled by the compression roller with the large roller diameter, the tangent force in the pole piece rolling process is reduced, the zigzag holes of the pole piece are reduced, but the surface of the pole piece is compacted greatly by the rolling mode, the porosity is small, and the compaction is reduced and the porosity is increased along with the increase of the thickness in the thickness direction of the pole piece.
Disclosure of Invention
Based on the above, the invention aims to provide a battery pole piece compression roller, so that the specific surface area of a rolled pole piece is increased, the porosity is reduced, and the binding force between an active substance during secondary coating and an active substance during primary coating is improved.
In order to achieve the purpose, the invention adopts the following technical scheme:
the battery pole piece compression roller comprises a roller shaft, wherein the roller shaft is cylindrical, a plurality of protrusions are uniformly arranged on the surface of the roller shaft at intervals, the cross sections of the protrusions are square, and the distance between every two adjacent protrusions is 1-5 mm.
As a preferable scheme of the battery pole piece compression roller, the length of the convex part ranges from 0.5mm to 4mm, the width ranges from 0.05mm to 0.3mm, and the height ranges from 10 mu m to 90 mu m.
The invention also aims to provide a battery pole piece rolling method, which improves the surface and shallow layer porosity, reduces the liquid phase conduction resistance and increases the characteristic thickness of the pole piece.
A rolling method of a battery pole piece comprises the following steps:
s1: coating first pole piece slurry on the surface of a current collector according to a preset surface density;
s2: cold pressing the current collector coated with the first pole piece slurry by using the battery pole piece compression roller of any one of claims 1-2 to form a semi-finished pole piece;
s3: coating second pole piece slurry on the surface of the cold-pressed semi-finished pole piece according to a preset surface density for the second time;
s4: and carrying out secondary cold pressing on the semi-finished pole piece coated with the second pole piece slurry by adopting a plane pressing roller to obtain the pole piece.
As a preferable scheme of the rolling method of the battery pole piece, between the step S1 and the step S2, the current collector coated with the first pole piece slurry is dried, and between the step S3 and the step S4, the semi-finished pole piece coated with the second pole piece slurry is dried.
As a preferable scheme of the rolling method of the battery pole piece, the solid content and the viscosity of the first pole piece slurry are less than those of the second pole piece slurry.
As a preferable scheme of the rolling method of the battery pole piece, the coating surface density of the second pole piece slurry coated for the second time is lower than that of the first pole piece slurry coated for the first time.
As a preferred scheme of the rolling method of the battery pole piece, 96% -98% of lithium iron phosphate, 1.5% -2.0% of conductive agent SP, 0.5% -1% of carbon nanotube CNT and 2% -3% of binder PVDF are adopted as solutes in the first pole piece slurry, and 40% -42% of NMP is adopted as a solvent.
As a preferred scheme of the rolling method of the battery pole piece, 96% -98% of lithium iron phosphate, 1.5% -2.0% of conductive agent SP, 0.5% -1% of carbon nanotube CNT and 2% -3% of binder PVDF are adopted as solutes in the second pole piece slurry, and 30% -35% of NMP is adopted as a solvent.
The invention also aims to provide a battery pole piece with larger characteristic thickness.
A battery pole piece is manufactured by the battery pole piece rolling method in any technical scheme.
The invention also aims to provide a battery which is higher in energy density and better in cycle performance.
A battery comprises the battery pole piece in the technical scheme.
The invention has the beneficial effects that:
the invention provides a battery pole piece compression roller, a battery pole piece rolling method, a battery pole piece and a battery, wherein a roller shaft of the battery pole piece compression roller is cylindrical, and a bulge part with a square cross section is arranged on the surface of the roller shaft, so that the specific surface area of the rolled pole piece is increased in the pole piece rolling process, the porosity is reduced, and the binding force between an active substance during secondary coating and an active substance during primary coating is improved. The current collector coated with the first pole piece slurry is subjected to cold pressing by the pole piece pressing roller, and the current collector is not easy to be embrittled under the condition of high compaction due to the large surface area of the square bulge, and the strip breakage is not easy to occur in the subsequent die cutting process; and then, the semi-finished pole piece coated with the second pole piece slurry is subjected to secondary cold pressing by adopting a plane pressing roller, so that on one hand, a current collector is protected, on the other hand, active substances coated for the first time and the second time can be better contacted, the current collector is ensured not to be damaged, and the pole piece stripping force is also improved. Through twice cold pressing, the first pressing roller with the protruding parts is adopted, the second pressing roller is a plane pressing roller, the electrode structure can be improved, the surface porosity and the shallow layer porosity of the pole piece are improved, the infiltration of electrolyte is facilitated, the liquid phase conduction resistance is reduced, and the internal resistance of the battery is reduced. Meanwhile, the electrode reaction area can be increased, the current density is reduced, and the ohmic polarization is reduced. The pole piece made by the above method has a large characteristic thickness. And the battery with the pole piece has higher energy density and higher cycle performance.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments of the present invention will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the contents of the embodiments of the present invention and the drawings without creative efforts.
FIG. 1 is a schematic structural diagram of a battery pole piece compression roller provided by an embodiment of the invention;
fig. 2 is a flowchart of a battery pole piece rolling method provided by an embodiment of the invention.
In the figure:
1. a roll shaft; 2. a raised portion.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.
In the description of the present invention, unless expressly stated or limited otherwise, the terms "connected," "connected," and "fixed" are to be construed broadly, e.g., as meaning permanently connected, removably connected, or integral to one another; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
In the present invention, unless otherwise expressly stated or limited, "above" or "below" a first feature means that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact with each other via another feature therebetween. Also, the first feature being "on," "above" and "over" the second feature includes the first feature being directly on and obliquely above the second feature, or merely indicating that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature includes the first feature being directly under and obliquely below the second feature, or simply meaning that the first feature is at a lesser elevation than the second feature.
In the description of the present embodiment, the terms "upper", "lower", "left", "right", and the like are used based on the orientations and positional relationships shown in the drawings only for convenience of description and simplification of operation, and do not indicate or imply that the referred device or element must have a specific orientation, be configured and operated in a specific orientation, and thus, should not be construed as limiting the present invention. In the description of the present invention, "a plurality" means two or more unless otherwise specified. Furthermore, the terms "first" and "second" are used only for descriptive purposes and are not intended to have a special meaning.
As shown in fig. 1, the embodiment provides a battery pole piece compression roller, and this battery pole piece compression roller includes roller 1, and roller 1 is cylindricly, and roller 1 surface is even and the interval is provided with a plurality of bellyings 2, and the cross-section of bellyings 2 is square. Specifically, roller 1 surface just evenly is provided with a plurality of protruding groups along the circumference interval of roller 1, and protruding group includes a plurality of bellying 2, and bellying 2 is just evenly set up along the axial interval of roller 1. In the production process of the battery pole piece, the battery pole piece is generally coated with the active substance twice and is subjected to cold pressing respectively. The bulge 2 of the battery pole piece compression roller can enable the surface to form grooves after the inner layer is subjected to cold pressing, and form convex points between adjacent grooves, so that the specific surface area of the rolled pole piece is increased, supporting points can be formed by the convex points in the subsequent cold pressing process, the secondarily coated active substances are better combined with the primarily coated active substances, and the stripping force is improved; and the porosity of the active material on the outer layer can be ensured, and the wettability of the electrolyte can be improved.
Preferably, the distance between two adjacent convex parts 2 ranges from 1mm to 5 mm. In this embodiment, the distance between two adjacent protrusions 2 ranges from 2mm to 3 mm. Further preferably, the length of the protrusions 2 ranges from 0.5mm to 4mm, the width ranges from 0.05mm to 0.3mm, and the height ranges from 10 μm to 90 μm. In this embodiment, the length of the protrusion ranges from 1mm to 2mm, the width ranges from 0.1mm to 0.2mm, and the height ranges from 40 μm to 60 μm. Through using the compression roller with the protruding part 2 with reasonable size, the maximum compaction effect can be achieved during cold pressing, and the groove distribution rule formed on the surface after the cold pressing of the inner layer is finished is ensured, so that the yield of pole pieces is ensured. Of course, in other embodiments, the size, shape and spacing distance of the protrusions 2 may be designed according to actual requirements.
As shown in fig. 2, this embodiment further provides a rolling method for a battery pole piece, which includes the following steps:
s1: coating first pole piece slurry on the surface of a current collector according to a preset single-sided surface density;
s2: cold-pressing the current collector coated with the first pole piece slurry by adopting the battery pole piece compression roller to form a semi-finished pole piece;
s3: coating the second pole piece slurry on the surface of the cold-pressed semi-finished pole piece according to the preset single-sided surface density for the second time;
s4: and carrying out secondary cold pressing on the semi-finished pole piece coated with the second pole piece slurry by adopting a plane pressing roller to obtain the pole piece.
Alternatively, the current collector may be an aluminum foil or a carbon-coated aluminum foil.
Specifically, between step S1 and step S2, the current collector coated with the first pole piece slurry is dried, and between step S3 and the step S4, the semi-finished pole piece coated with the second pole piece slurry is dried. Preferably, drying is performed by using a drying oven.
Firstly, preparing first pole piece slurry, then coating the first pole piece slurry on the surface of a prepared current collector to form an inner layer on the surface of the current collector, drying the inner layer, and then cold-pressing the inner layer by using a battery pole piece compression roller with a convex part 2 to form a plurality of uniformly distributed grooves on the inner layer; and coating the second pole piece slurry on the surface of the inner layer to form an outer layer, drying the outer layer, and cold pressing the outer layer by adopting a plane pressing roller to obtain a finished pole piece. By adopting the cold pressing mode of combining the battery pole piece compression roller with the convex part 2 and the plane roller, the electrode structure can be improved, the porosity of coarse pores on the surface and the shallow layer of the pole piece is improved, the infiltration of electrolyte is facilitated, and the liquid phase conduction resistance is reduced, so that the internal resistance of the battery is reduced, the electrode reaction area is increased, the current density is reduced, and the ohmic polarization is reduced. Meanwhile, the secondary rolling adopts a plane roller, so that the current collector is protected, and active substances coated for the first time and the second time can be better contacted with each other, so that the current collector is not damaged, and the stripping force of the pole piece is improved.
Preferably, the viscosity and solid content of the first pole piece slurry are both less than those of the second pole piece slurry. The viscosity and solid content of the second pole piece slurry used for secondary coating are higher than those of the first pole piece slurry used for primary coating, and the energy density of the battery and the stripping force between active substances can be improved. Optionally, the solid content of the first pole piece slurry is 58% -60%, and the viscosity is 10000mPa · s-18000 mPa · s; the solid content of the second pole piece slurry is 65-70%, and the viscosity is 15000 mPa.s-20000 mPa.s. The solid content and viscosity of the first pole piece slurry during the first coating are low, and the pole piece fluid is not damaged in the cold pressing process. And during secondary coating, the solid content and viscosity of the second pole piece slurry are higher, so that the stripping force between two layers of active materials during secondary coating is ensured, and the energy density of the battery can be improved.
Preferably, the coating surface density, the compaction density and the press roll pressure of the second pole piece coating slurry are lower than those of the first pole piece coating slurry. The lower coating surface density and compaction density of the secondary coating are combined with the bulge 2 formed by the primary coating, so that the porosity of a shallow layer can be obviously improved, the infiltration of electrolyte is improved, the utilization rate of active substances is improved, and the characteristic thickness of the pole piece is improved. Meanwhile, the high compaction density during one-time coating can improve the binding force between the active substance and the pole piece fluid, and can prevent the problem of the falling of the active substance caused by material expansion in the subsequent circulation process, thereby improving the circulation performance of the battery.
Optionally, the coating surface density of the first pole piece slurry coated at one time is in the range of 180g/m3～190g/m3The pressure range of the compression roller is 20-23 MPa, and the cold pressing after primary coating adopts the battery pole piece compression roller with the convex part 2 on the surface, at the moment, the solid content and the viscosity of the first pole piece slurry are lower, in order to ensure that the pole piece fluid is not damaged in the cold pressing process, the compaction density adopted for the first time is 2.45-2.55 g/cm3, the primary compaction density is high, and the stripping force of an active substance and a carbon-coated aluminum foil can be ensured. The coating surface density of the second pole piece coating slurry is 170g/m3～180g/m3The range of the compacted density is 2.00g/cm3～2.15g/cm3The rolling pressure range is 15 MPa-17 MPa. By adopting a cold pressing method of compacting the inner layer with high pressure and compacting the outer layer with low pressure, the solid-liquid phase conduction conversion efficiency in the thickness direction of the pole piece can be improved, the multiplying power performance of the battery is improved, and the charging and discharging direct current internal resistance of the battery is reduced. Meanwhile, the inner layer is highly compacted, so that the current collector is not easy to be compacted and brittle, and the strip breakage is not easy to occur in the subsequent die cutting process; and the first pole piece slurry can be combined with the carbon-coated foil more tightly, so that the stripping force of the active substance on the inner layer and the carbon-coated foil is improved.
Furthermore, 96% -98% of lithium iron phosphate, 1.5% -2.0% of conductive agent SP, 0.5% -1% of carbon nanotube CNT and 2% -3% of binder PVDF are adopted as solutes in the first pole piece slurry, and 40% -42% of NMP is adopted as a solvent. The NMP content of the first pole piece slurry of one coating was calculated from the required solid content. Wherein lithium iron phosphate is an active material. Furthermore, 96% -98% of lithium iron phosphate, 1.5% -2.0% of conductive agent SP, 0.5% -1% of carbon nanotube CNT and 2% -3% of binder PVDF are adopted as solutes in the second pole piece slurry, and 30% -35% of NMP is adopted as a solvent. The NMP content of the first pole piece slurry of the second coating is calculated according to the required solid content. The first pole piece slurry and the second pole piece slurry are evenly mechanically stirred and then coated, and are cold-pressed through the battery pole piece compression roller and the plane compression roller with the protruding portions 2, so that the surface porosity and the shallow layer porosity of the pole piece are improved, the infiltration of electrolyte is facilitated, the liquid phase conductivity is improved, and the characteristic thickness of the pole piece is increased. The rolling method of the battery pole piece can increase the characteristic thickness of the pole piece and improve the utilization rate of active substances in the thickness direction of the pole piece, thereby increasing the energy density of the battery.
The rolling method of the battery pole piece can increase the specific surface area of the pole piece and improve the wettability of the electrolyte in the battery liquid injection process. The pole piece surface after disassembling the battery does not have the fold and the interface is level and smooth, can make the pole piece reduce and fall whitewashed, and the mass flow body is difficult to the fish tail diaphragm and arouses the battery short circuit, also can increase the adherence of active material and mass flow body, avoids active material to drop the mass flow body, promotes to some extent to the capacity and the cycling performance of electric core simultaneously. And through high compaction, the energy density can be improved, the electrolyte wettability is good, the safety performance is excellent, the cost is low, and large-scale processing and mass production are easy to realize.
The embodiment also provides a battery pole piece, and the battery pole piece is manufactured by the battery pole piece rolling method. The pole piece manufactured by the rolling method of the battery pole piece has larger characteristic thickness and electrode reaction area. The porous battery pole piece mainly comprises coarse holes and fine holes, wherein the micron-sized coarse holes are gaps among the powder and are main transmission channels of ions, and the submicron-sized fine holes are inner holes of the powder and have small contribution to ion transmission. The change of solid-liquid phase voltage is also involved in the thickness direction of the pole piece, liquid phase conduction is mainly adopted on the surface and shallow layer of the pole piece, the liquid phase voltage is highest, the liquid phase conduction is gradually converted into solid phase conduction along with the increase of the thickness of the pole piece, the liquid phase voltage is gradually reduced, the solid phase voltage is gradually increased, and the solid phase voltage is highest and the liquid phase voltage is zero when reaching the interface of a current collector and slurry. By adopting the rolling method of the battery pole piece, the porosity of the coarse pores on the surface and the shallow layer of the battery pole piece is large, and the porosity of the deep layer of the electrode is small, so that the infiltration of electrolyte is facilitated, and the liquid phase conductivity is improved; and the characteristic thickness of the pole piece is increased, and the utilization rate of active substances in the thickness direction of the pole piece is improved, so that the energy density of the battery is increased.
The embodiment also provides a battery, which comprises the battery pole piece. The battery pole piece is arranged, so that the internal resistance of the battery is small, and the energy density is high.
It is to be noted that the foregoing is only illustrative of the preferred embodiments of the present invention and the technical principles employed. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail by the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present invention, and the scope of the present invention is determined by the scope of the appended claims.
Claims (10)
1. The utility model provides a battery pole piece compression roller, its characterized in that, includes roller (1), roller (1) is cylindricly, roller (1) surface is even and the interval is provided with a plurality of bellyings (2), the cross-section of bellyings (2) is squarely, and adjacent two the interval scope is 1mm-5mm between bellyings (2).
2. The battery pole piece pressing roll according to claim 1, wherein the protrusions (2) have a length in the range of 0.5mm to 4mm, a width in the range of 0.05mm to 0.3mm and a height in the range of 10 μm to 90 μm.
3. A rolling method for a battery pole piece is characterized by comprising the following steps:
s1: coating first pole piece slurry on the surface of a current collector according to a preset surface density;
s2: cold pressing the current collector coated with the first pole piece slurry by using the battery pole piece compression roller of any one of claims 1-2 to form a semi-finished pole piece;
s3: coating second pole piece slurry on the surface of the cold-pressed semi-finished pole piece according to a preset surface density for the second time;
s4: and carrying out secondary cold pressing on the semi-finished pole piece coated with the second pole piece slurry by adopting a plane pressing roller to obtain the pole piece.
4. The battery pole piece rolling method of claim 3, wherein between the step S1 and the step S2, the current collector coated with the first pole piece slurry is dried, and between the step S3 and the step S4, the semi-finished pole piece coated with the second pole piece slurry is dried.
5. The rolling method for battery pole pieces according to claim 3, wherein the solid content and viscosity of the first pole piece slurry are less than those of the second pole piece slurry.
6. The battery pole piece rolling method according to claim 3, wherein the coated surface density of the second pole piece slurry coated at the second time is lower than that of the first pole piece slurry coated at the first time.
7. The rolling method of the battery pole piece according to claim 3, wherein 96% -98% of lithium iron phosphate, 1.5% -2.0% of conductive agent SP, 0.5% -1% of carbon nanotube CNT and 2% -3% of binder PVDF are adopted as solute in the first pole piece slurry, and 40% -42% of NMP is adopted as solvent.
8. The rolling method of the battery pole piece according to claim 3, wherein 96% -98% of lithium iron phosphate, 1.5% -2.0% of conductive agent SP, 0.5% -1% of carbon nanotube CNT and 2% -3% of binder PVDF are adopted as solutes in the second pole piece slurry, and 30% -35% of NMP is adopted as a solvent.
9. A battery pole piece, characterized in that the battery pole piece is manufactured by the rolling method of the battery pole piece according to any one of claims 3 to 8.
10. A lithium battery comprising the battery pole piece of claim 9.
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