CN114171718B - Pole piece preparation method of composite foil current collector, pole piece and soft package battery - Google Patents

Pole piece preparation method of composite foil current collector, pole piece and soft package battery Download PDF

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Publication number
CN114171718B
CN114171718B CN202111285008.3A CN202111285008A CN114171718B CN 114171718 B CN114171718 B CN 114171718B CN 202111285008 A CN202111285008 A CN 202111285008A CN 114171718 B CN114171718 B CN 114171718B
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current collector
composite foil
foil current
pole piece
pole
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CN114171718A (en
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许晓雄
崔言明
顾凡佩
龚和澜
孔丹丹
戈志敏
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Zhejiang Funlithium New Energy Tech Co Ltd
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Zhejiang Funlithium New Energy Tech Co Ltd
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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
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • 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
    • 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
    • H01M10/058—Construction or manufacture
    • H01M10/0583—Construction or manufacture of accumulators with folded construction elements except wound ones, i.e. folded positive or negative electrodes or separators, e.g. with "Z"-shaped electrodes or separators
    • 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
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H01M4/665—Composites
    • H01M4/667—Composites in the form of layers, e.g. coatings
    • 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
    • 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
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

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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)
  • Composite Materials (AREA)
  • Battery Electrode And Active Subsutance (AREA)
  • Cell Electrode Carriers And Collectors (AREA)

Abstract

The invention discloses a pole piece preparation method of a composite foil current collector, a pole piece and a soft package battery, which comprise the following steps: s1, electrode slurry and conductive substances are coated on the surface of a composite foil current collector at intervals, an uncoated area is reserved between the electrode slurry and the conductive substances, and the conductive substances are non-sticky at normal temperature and sticky after being heated; s2, cutting the composite foil current collector obtained in the step S1 into pole pieces with pole lugs, wherein the conductive substances and the uncoated areas are positioned on the pole lug parts of the pole pieces; the composite foil current collector with lower surface density is adopted, so that the energy density of the battery can be effectively improved, and the soft-packed battery adopting the pole piece and the preparation method ensures the electronic conduction between different composite aluminum foil pole pieces, simplifies the welding process, saves the cost and improves the production efficiency and the yield.

Description

Pole piece preparation method of composite foil current collector, pole piece and soft package battery
Technical Field
The invention relates to the field of lithium batteries, in particular to a pole piece preparation method adopting a composite foil current collector, a pole piece and a soft package battery.
Background
In the production process of lithium batteries, a metal foil is generally selected as a current collector, wherein an aluminum foil is selected as a positive current collector, and a copper foil is selected as a negative current collector. In order to improve the energy density and safety of a battery, a composite current collector obtained by compositing a polymer film and a metal plating layer is attracting attention.
However, the polymer film is adopted in the middle of the composite current collector, the formed insulating layer enables the metal plating layers on two sides to be unable to be conducted, when the composite current collector lugs and the outer lugs are welded, good contact and electronic connection cannot be formed between the metal plating layers on the upper side and the lower side of the polymer film in the conventional ultrasonic spot welding process, therefore, good electric connection cannot be formed between the outer lugs and the multi-layer composite current collector lugs, current conduction in the battery is hindered, the internal resistance of the battery is increased, insulation between the positive electrode and the negative electrode of the battery is even caused, and the normal charge and discharge functions of the battery are affected.
The method commonly adopted at present is to clamp the electrode lug of a layer of composite current collector by two layers of metal electrode lugs and weld the electrode lugs together, and then weld the multi-layer metal electrode lugs with the external electrode lugs of the lithium battery respectively, thereby solving the problem of leading out the electrode lugs of the composite current collector. However, with this method, the tab portion of each composite current collector needs to be coated and welded with two metal tabs, increasing the number of aluminum copper foil layers to be welded, which increases the weight of the battery and reduces the energy density of the battery. In addition, by adopting the method to convey the current from the electrode, the welding process is complex, and the quality is uneven, so that after the composite current collector is used, the welding difficulty is increased, and the yield is affected. More importantly, even if welding is successful, the effective electron conductive metal layer in the composite current collector is limited in thickness, and under the same welding area, the resistance is still higher than that of a conventional aluminum foil copper foil, so that the power performance of the battery is influenced.
Disclosure of Invention
The invention aims to solve the technical problems of providing a pole piece preparation method, a pole piece and a soft package battery solution adopting a composite foil current collector, wherein the energy density of a battery can be effectively improved by adopting the composite foil current collector with lower surface mass density, and the soft package battery adopting the pole piece and the preparation method ensures the electronic conduction between different composite aluminum foil pole pieces, simplifies the welding process, saves the cost and simultaneously improves the production efficiency and the yield.
The technical scheme adopted for solving the technical problems is as follows:
the preparation method of the pole piece of the composite foil current collector comprises the following steps:
s1, electrode slurry and conductive substances are coated on the surface of a composite foil current collector at intervals, an uncoated area is reserved between the electrode slurry and the conductive substances, and the conductive substances are non-sticky at normal temperature and sticky after being heated;
s2, cutting the composite foil current collector obtained in the step S1 into pole pieces with pole lugs, wherein the conductive substances and the uncoated areas are positioned on the pole lug parts of the pole pieces;
or comprises the following steps:
a1, coating electrode slurry on the surface of a composite foil current collector, leaving a first blank area, and then drying;
a2, coating a conductive substance on a first blank area of the composite foil current collector, and then drying again, wherein an uncoated area is reserved between the conductive substance and the electrode slurry, and the conductive substance is non-sticky at normal temperature and sticky after heating;
a3, cutting the composite foil current collector obtained in the step A2 into a pole piece with a pole lug, wherein the conductive substance and the uncoated area are positioned at the pole lug part of the pole piece;
or comprises the following steps:
b1, coating a conductive substance on the surface of a composite foil current collector, leaving a second blank area, and then drying, wherein the conductive substance is non-sticky at normal temperature and sticky after heating;
b2, coating electrode slurry on a second blank area of the composite foil current collector, and then drying again, wherein an uncoated area is reserved between the electrode slurry and the conductive substance;
b3, cutting the composite foil current collector obtained in the step B2 into pole pieces with pole lugs, wherein the conductive substances and the uncoated areas are positioned on the pole lug parts of the pole pieces.
Preferably, the heat-melting temperature (modification temperature) of the conductive substance is greater than the drying temperature after the conductive substance is coated.
Preferably, the electrode slurry is coated on the middle position of the surface of the composite foil current collector, and the conductive substance is coated on at least one side of the electrode slurry.
Preferably, the conductive substance is a mixture of a gel liquid material and an electron conductive agent.
Preferably, the ratio of the width of the uncoated region to the width of the region coated with the conductive substance is 1/9 to 9/1.
Preferably, the thickness of the coated conductive material after drying is 5 μm to 20 μm.
Preferably, the composite foil current collector comprises a polymer film in the middle and a first metal layer and a second metal layer respectively positioned at two sides of the polymer film in the thickness direction.
The pole piece of the composite foil current collector comprises the pole piece prepared by the method.
The utility model provides a soft packet of battery, includes diaphragm or solid electrolyte membrane, external positive tab, external negative tab and a plurality of pole piece, a plurality of the pole piece corresponds respectively and is positive pole piece and negative pole piece, the positive pole piece with the crisscross overlapping setting of negative pole piece, diaphragm or solid electrolyte membrane winding is the Z type, every positive pole piece with keep apart through diaphragm or solid electrolyte membrane between the negative pole piece, a plurality of hot pressing bonding is in the same place after the tab coincide of positive pole piece, then is connected with external positive tab, a plurality of hot pressing bonding is in the same place after the tab coincide of negative pole piece, then is connected with external negative tab.
Compared with the prior art, the pole piece preparation method, the pole piece and the soft package battery of the composite foil current collector have the advantages that,
1) The composite foil current collector with lower surface mass density is adopted, so that the energy density of the battery can be effectively improved;
2) After lamination process, the multi-layer current collector is heated and pressed together, this step is equivalent to the current collector welding process of the ordinary metal foil, compared with the welding connection of the ordinary metal foil current collector, the coating of the non-sticky conductive material at normal temperature and after heating in the blank area is only slightly improved in process, the preparation process of the pole piece is highly matched with other related processes such as cutting and the like with the existing conventional process, special equipment is not needed, the problem of difficult welding of the existing composite foil current collector is effectively solved, the cost is saved, the problem of uneven quality of the welding process of the composite foil current collector is also solved, and the production efficiency and the yield are improved;
3) Through raw material screening, coating a conductive substance which is non-sticky at normal temperature and sticky after heating in a white area, thereby facilitating the rolling and storage of the pole piece;
4) By leaving a certain proportion uncoated area between the electrode slurry and the conductive substance, the adverse effect of high temperature on the diaphragm during hot pressing of the electrode lugs is reduced, and the risks of lithium precipitation of the negative electrode and short circuit of the positive electrode and the negative electrode are avoided. More importantly, the uncoated area can be set for the tab turnover process, so that the area of the top sealing area of the battery is reduced, and the energy density of the battery is improved.
Drawings
FIG. 1 is a schematic diagram of a composite foil current collector coated with a conductive material and an electrode paste;
FIG. 2 is a schematic illustration of a cut pole piece;
FIG. 3 is a schematic cross-sectional view of a composite foil current collector after being coated with a conductive material and an electrode paste;
FIG. 4 is a schematic diagram II of the structure of a composite foil current collector after being coated with a conductive material and an electrode paste;
FIG. 5 is a schematic diagram III of the structure of a composite foil current collector after being coated with a conductive material and an electrode paste;
fig. 6 is a schematic diagram of a structure of a composite foil current collector coated with a conductive material and an electrode paste.
In the figure, 1, a composite foil current collector; 11. a polymer film; 12. a first metal layer; 13. a second metal layer; 2. electrode slurry; 3. a conductive substance; 4. uncoated areas.
Detailed Description
The invention is described in further detail below with reference to the embodiments of the drawings.
Example 1,
The preparation method of the pole piece of the composite foil current collector comprises the following steps:
s1, coating electrode slurry 2 and conductive substances 3 on the surface of a composite foil current collector 1 at intervals, leaving an uncoated area 4 between the electrode slurry 2 and the conductive substances 3, drying the composite foil current collector 1 coated with the electrode slurry 2 and the conductive substances 3, and then rolling;
s2, cutting the composite foil current collector obtained in the step S1 into pole pieces with pole lugs, wherein the conductive substance 3 and the uncoated area 4 are both positioned at the pole lug parts of the pole pieces.
Wherein the conductive substance 3 is a mixture of an adhesive liquid material and an electron conductive agent, the conductive substance 3 is non-adhesive at normal temperature, has adhesive property after heating, and the hot melting temperature (modification temperature) of the conductive substance 3 is greater than the drying temperature of the conductive substance 3 after coating.
The composite foil current collector 1 comprises a polymer film 11 in the middle and a first metal layer 12 and a second metal layer 13 respectively positioned at two sides of the polymer film 11 in the thickness direction. Both the electrode paste 2 and the conductive substance 3 are coated along the extending direction (length direction) or width direction of the composite foil current collector 1.
The ratio of the width of the uncoated area 4 to the width of the area coated with the conductive substance 3 is 1/9 to 9/1, preferably 1/4 to 4/1, particularly 2/5, and the ratio is too small, so that the membrane is not contracted due to the folding or hot pressing of the tab, the ratio is too high, and the effective area of electronic contact is low. The thickness of the coated conductive material 3 after drying is 5 μm to 20 μm, preferably 8 μm to 16 μm, in particular 12 μm, too thick to affect the electron conductivity and too thin to meet the requirements of the adhesive strength.
The uncoated area 4 is provided with a starting position, a cutter of cutting equipment starts cutting from the starting position, cuts according to the preset pole piece shape and returns to the starting position to form a pole piece with a pole lug; or cutting for multiple times by one or more cutters of cutting equipment to form a pole piece with a pole lug; or a plurality of cutters of the cutting equipment are used for cutting simultaneously to form a pole piece with a pole lug.
It should be understood by those skilled in the art that the application of the electrode paste 2 and the conductive substance 3 on the surface of the composite foil current collector 1 at intervals in step S1 includes both the application of the electrode paste 2 and then the application of the conductive substance 3, and also includes the application of the conductive substance 3 and then the application of the electrode paste 2, and also includes the simultaneous application of the electrode paste 2 and the conductive substance 3.
Fig. 1 is a schematic structural diagram of a composite foil current collector coated with a conductive material 3 and an electrode paste; FIG. 2 is a schematic illustration of a cut pole piece; fig. 3 is a schematic cross-sectional view of a composite foil current collector after being coated with a conductive substance 3 and an electrode paste.
EXAMPLE 2,
The difference between the preparation method of the pole piece of the composite foil current collector and the embodiment 1 is that:
the method comprises the following steps:
a1, coating electrode slurry 2 on the surface of a composite foil current collector 1, leaving a first blank area, and then drying and rolling;
a2, coating a conductive substance 3 on a first blank area of the composite foil current collector 1, then drying and rolling again, leaving an uncoated area 4 between the conductive substance 3 and the electrode slurry 2, wherein the conductive substance 3 is non-sticky at normal temperature and sticky after heating;
a3, cutting the composite foil current collector 1 obtained in the step A2 into pole pieces with pole lugs, wherein the conductive substance 3 and the uncoated area 4 are positioned at the pole lug parts of the pole pieces.
EXAMPLE 3,
The difference between the preparation method of the pole piece of the composite foil current collector and the embodiment 1 is that:
the method comprises the following steps:
b1, coating a conductive substance 3 on the surface of the composite foil current collector 1, leaving a second blank area, drying and rolling, wherein the conductive substance 3 is non-sticky at normal temperature and sticky after heating;
b2, coating electrode slurry 2 on a second blank area of the composite foil current collector 1, and then drying and rolling again, wherein an uncoated area 4 is reserved between the electrode slurry 2 and the conductive substance 3;
b3, cutting the composite foil current collector 1 obtained in the step B2 into pole pieces with pole lugs, wherein the conductive substance 3 and the uncoated area 4 are positioned at the pole lug parts of the pole pieces.
EXAMPLE 4,
The preparation method of the pole piece of the composite foil current collector comprises the following steps:
s1, taking a roll of composite foil, coating electrode slurry 2 on the surface of the composite foil by using a coating machine along the length direction of the composite foil, coating a conductive substance 3 on one side of the electrode slurry 2, leaving an uncoated area 4 between the electrode slurry 2 and the conductive substance 3, drying and then rolling the composite foil current collector 1 coated with the electrode slurry 2 and the conductive substance 3;
s2, cutting the composite foil current collector 1 obtained in the step S1 into pole pieces with pole lugs, wherein the conductive substance 3 and the uncoated area 4 are both positioned at the pole lug parts of the pole pieces.
Wherein, the thickness of the composite aluminum foil is 8 μm, the thickness of the polymer film 11 is 6 μm, the thickness of the first metal layer 12 is 1 μm, the thickness of the second metal layer 13 is 1 μm, the thickness of the composite copper foil is 7 μm, the thickness of the polymer film 11 is 6 μm, the thickness of the first metal layer 12 is 0.5 μm, and the thickness of the second metal layer 13 is 0.5 μm. The width of the uncoated region 4 was 6mm, the width of the region coated with the conductive substance 3 was 15mm, and the tab width of the cut pole piece was 21mm, and the thickness of the coated conductive substance 3 after drying was 12 μm.
The conductive substance 3 is a mixture of epoxy conductive silver adhesive and AB, the mixing ratio is 1:1, the modification temperature of the conductive substance 3 is 180 ℃, and the drying temperature in the step S2 is 120 ℃.
EXAMPLE 5,
The preparation method of the pole piece of the composite foil current collector comprises the following steps:
a1, taking a roll of composite foil, coating electrode slurry 2 on the surface of the composite foil by using a coating machine along the length direction of the composite foil, leaving a first blank area, and then drying and rolling at the drying temperature of 120 ℃;
a2, coating a conductive substance 3 on a first blank area of the composite foil current collector 1 along the extending direction of the composite foil, and then drying and rolling again, wherein the drying temperature is 120 ℃, and an uncoated area 4 is reserved between the conductive substance 3 and the electrode slurry 2;
a3, cutting the composite foil current collector 1 obtained in the step A2 into pole pieces with pole lugs, wherein the conductive substance 3 and the uncoated area 4 are positioned at the pole lug parts of the pole pieces.
The selection of the composite foil, the width of the uncoated area 4, the selection of the conductive substance 3 and the coating width and thickness were all the same as in example 4.
EXAMPLE 6,
The preparation method of the pole piece of the composite foil current collector comprises the following steps:
b1, taking a roll of composite foil, coating a conductive substance 3 on the surface of the composite foil along the length direction of the composite foil by using a coating machine, leaving a second blank area, and then drying at 120 ℃;
b2, coating electrode slurry 2 on a second blank area of the composite foil current collector 1 along the extending direction of the composite foil, and then drying again at 120 ℃ with an uncoated area 4 left between the electrode slurry 2 and the conductive substance 3;
b3, cutting the composite foil current collector 1 coated with the electrode slurry 2 and the conductive substance 3 into pole pieces with pole lugs, wherein the conductive substance 3 and the uncoated area 4 are positioned at the pole lug parts of the pole pieces.
The selection of the composite foil, the width of the uncoated area 4, the selection of the conductive substance 3 and the coating width and thickness were all the same as in example 4.
EXAMPLE 7,
The difference between the preparation method of the pole piece of the composite foil current collector and the embodiment 4 is that the width of the uncoated area 4 is 2.1mm, the width of the area coated with the conductive substance 3 is 18.9mm, and the width of the tab of the cut pole piece is 21mm.
EXAMPLE 8,
The difference between the preparation method of the pole piece of the composite foil current collector and the embodiment 4 is that the width of the uncoated area 4 is 18.9mm, the width of the area coated with the conductive substance 3 is 2.1mm, and the width of the tab of the cut pole piece is 21mm.
EXAMPLE 9,
The difference between the preparation method of the pole piece of the composite foil current collector and the embodiment 4 is that the thickness of the coated conductive substance 3 after drying is 5 μm.
EXAMPLE 10,
The difference between the preparation method of the pole piece of the composite foil current collector and the embodiment 4 is that the thickness of the coated conductive substance 3 after drying is 20 μm.
EXAMPLE 11,
The preparation method of the pole piece of the composite foil current collector is different from example 4 in that the conductive substance is a mixture of epoxy conductive silver adhesive and AB, and the mixing ratio is 1:2.
EXAMPLE 12,
The preparation method of the pole piece of the composite foil current collector is different from the preparation method of the embodiment 4 in that the conductive substance is a mixture of epoxy conductive silver adhesive and SP, the mixing ratio is 1:1, the modification temperature of the conductive substance is 175 ℃, and the drying temperature in the step S2 is 120 ℃.
EXAMPLE 13,
The preparation method of the pole piece of the composite foil current collector is different from the preparation method of the embodiment 4 in that the conductive substance is a mixture of epoxy conductive silver adhesive and SP, the mixing ratio is 1:2, the modification temperature of the conductive substance is 175 ℃, and the drying temperature in the step S2 is 120 ℃.
EXAMPLE 14,
The preparation method of the pole piece of the composite foil current collector is different from example 4 in that the conductive substance is a mixture of epoxy conductive silver adhesive and CNT, the mixing ratio is 1:1, the modification temperature of the conductive substance is 175 ℃, and the drying temperature in step S2 is 120 ℃.
EXAMPLE 15,
The difference between the preparation method of the pole piece of the composite foil current collector and the embodiment 4 is that the electrode slurry 2 is coated at the middle position of the surface of the composite foil current collector 1, and the conductive substances 3 are coated at two sides of the electrode slurry 2, as shown in fig. 4, when in cutting, the pole piece is cut along the middle of the electrode slurry 2 on the composite foil current collector 1, and then a plurality of pole pieces with one pole ear are cut.
EXAMPLE 16,
The difference between the preparation method of the pole piece of the composite foil current collector and the embodiment 4 is that the electrode slurry 2 is coated on two sides of the surface of the composite foil current collector 1, the conductive substance 3 is coated in the middle of the two electrode slurries 2, as shown in fig. 5, when cutting, the pole piece is cut back to the starting position from the starting position according to the preset pole piece shape, thereby forming a plurality of electrode pieces with one pole ear, and the electrode pieces on two sides share the conductive substance 3 in the middle, so that the material can be effectively saved.
EXAMPLE 17,
The difference between the preparation method of the pole piece of the composite foil current collector and the embodiment 4 is that the electrode paste 2 and the conductive substance 3 are coated at intervals along the width direction of the composite foil current collector 1, and the conductive substance 3 is coated on two sides of the electrode paste 2 as shown in fig. 6.
EXAMPLE 18,
A pole piece of a composite foil current collector comprising the pole piece prepared by the method described in examples 1-17 above.
EXAMPLE 19,
A soft package battery comprises a diaphragm or a solid electrolyte membrane, an external positive electrode lug, an external negative electrode lug and a plurality of pole pieces manufactured by the method of the embodiment 1-17, wherein the plurality of pole pieces are respectively corresponding to the positive electrode piece and the negative electrode piece, the positive electrode piece and the negative electrode piece are arranged in a staggered and overlapped mode, the diaphragm or the solid electrolyte membrane is wound to be Z-shaped, each positive electrode piece and each negative electrode piece are isolated through the diaphragm or the solid electrolyte membrane, the pole lugs of the plurality of positive electrode pieces are overlapped and then bonded together through hot pressing, then are connected with the external positive electrode lug, and the pole lugs of the plurality of negative electrode pieces are overlapped and then bonded together through hot pressing, and then are connected with the external negative electrode lug.
Comparative example 1,
The preparation method of the pole piece of the composite foil current collector comprises the following steps:
s1, coating electrode slurry on the surface of a composite foil current collector, and reserving a white area on one side of the electrode slurry;
s2, drying the composite foil current collector coated with the electrode slurry, and cutting the composite foil current collector into a pole piece with a pole lug, wherein a white area is positioned at the pole lug part of the pole piece.
The thickness of the composite aluminum foil material is 8 mu m, the thickness of the polymer film 11 is 6 mu m, the thickness of the first metal layer 12 is 1 mu m, the thickness of the second metal layer 13 is 1 mu m, the thickness of the composite copper foil material is 7 mu m, the thickness of the polymer film 11 is 6 mu m, the thickness of the first metal layer 12 is 0.5 mu m, the thickness of the second metal layer 13 is 0.5 mu m, and the width of the tab of the cut pole piece is 21mm.
When the electrode plate prepared by the method is manufactured into a battery, the metal plates are welded on the two sides of the electrode plate and then welded with the external electrode lugs, so that current is led out.
Comparative example 2,
The preparation method of the pole piece comprises the following steps:
s1, coating electrode slurry on the surface of a 12-mu m aluminum foil current collector or an 8-mu m copper foil current collector, and reserving a white area on one side of the electrode slurry;
s2, drying the metal foil current collector coated with the electrode slurry, and cutting the metal foil current collector into a pole piece with a pole lug, wherein a white area is positioned at the pole lug part of the pole piece.
Test example,
Testing of internal resistance, energy density improvement rate, battery capacity retention rate and yield of soft package battery
A pouch battery comprising positive and negative electrode sheets prepared by the method of examples 4-14, each containing 100 parallel samples.
The method for detecting the internal resistance of the battery comprises the following steps: and (3) fully charging the battery (charging to 4.2V at a constant current of 0.33C, and then charging to a constant voltage until the current is reduced to 0.05C), and then testing the internal resistance of the battery, wherein the frequency of an alternating current signal is set to be 1 KHz.
The energy density improvement rate and battery capacity retention rate test method comprises the following steps: and (3) carrying out charge and discharge cycle test on the battery at 25 ℃ by using a battery charge and discharge tester, wherein the charge and discharge system is as follows: (0.33C constant current is charged to 4.2V, then constant voltage is charged to 0.05C, the battery is discharged to 3.0V at 0.33C constant current after standing for 5 min, 1 cycle, the battery charge-discharge tester cycle number is set to 3 times, the average value of three discharge capacities is finally taken as the discharge capacity of 0.33C, the average value of three discharge capacities is taken as the discharge energy of 0.33C, the discharge energy of 0.33C is divided by mass and taken as the mass energy density, the mass energy density of the embodiment is further taken as the energy density increasing rate by dividing the mass energy density of comparative example 2, then the battery is charged to 4.2V at 1.0C constant current, then the constant voltage is charged to 0.05C, the battery is discharged to 3.0V at 1 cycle after standing for 5 min, the average value of three discharge capacities is finally taken as the discharge capacity of 0.33C, the average value of three discharge capacities is finally taken as the discharge capacity of 1.0C, the battery is subjected to the first cycle of the discharge capacity of 1.0C, and the discharge capacity of the battery is attenuated as the first cycle of the discharge capacity of the battery is not increased by the attenuation of the discharge capacity of the battery is maintained at the cycle rate of 1.33C. Each example contains 100 parallel samples, and the yield is counted.
In example 7, the coating area of the conductive material was widened, and although the internal resistance was reduced, the coating area was too wide, resulting in 3 cells being micro-shorted and self-discharged, and the yield was rather lowered. In example 8, the coating area of the conductive substance was reduced, resulting in an increase in internal resistance and a decrease in capacity retention; meanwhile, the bonding area is too small, so that poor bonding is caused, and the yield is only 90%.
In example 9, the thickness of the dried conductive substance was reduced, and although the internal resistance was reduced, the conductive substance was too thin, resulting in poor contact of 5 cells. In contrast, in example 10, the conductive material was too thick after drying, which resulted in an increase in internal resistance and a decrease in power performance, but the adhesion was good and did not affect the yield.
In example 11, the amount of AB was increased, but the conductivity was better, but the amount of the epoxy conductive silver paste was decreased, the adhesiveness was deteriorated, and the yield was reduced to 92%.
Examples 12 and 14 changed the mixtures to SP and CNT, respectively, and the internal resistance was gradually decreased due to the conductivity CNT > SP > AB. In example 13, the ratio of the mixture was changed to 1:2 based on example 12, and the yield was reduced for the same reasons as in example 11, but the conductivity of SP was higher than that of AB, so that the yield was 97% and higher than that of example 11.
The test shows that the conducting material and the electrode slurry are coated and then dried or respectively coated and dried, so that the influence on the internal resistance and the cycle life of the battery is small, but the conducting material and the electrode slurry are coated and then dried, the production period can be greatly shortened, and the efficiency is improved.
The coating thickness of the conductive substance 3 affects that when the thickness of the conductive substance 3 is selected, a reasonable thickness can improve various performances of the battery.
The width of the uncoated region 4 is too large, the conductive performance is weakened, the width of the region coated with the conductive substance is too large, the short-circuit self-discharge is caused, and the ratio of the width of the uncoated region 4 to the width of the region coated with the conductive substance 3 is optimally 2/5.
Compared with the prior art, the pole piece preparation method, the pole piece and the soft package battery adopting the composite foil current collector 1 have the advantages that after the hot pressing mode is adopted to connect 100 batteries for test production, the optimal coating area width ratio, the conductive material coating thickness and the conductive material ratio are adopted, the yield reaches 100 percent, and compared with the yield of 65 percent of the prior welding mode, the pole piece preparation method, the pole piece and the soft package battery have the advantages of remarkably improving the yield, along with simple operation compared with the welding mode and capability of improving the production efficiency.
While the preferred embodiments of the present invention have been described in detail, it is to be clearly understood that the same may be varied in many ways by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (6)

1. A preparation method of a pole piece of a composite foil current collector is characterized by comprising the following steps: the method comprises the following steps:
s1, electrode slurry and conductive substances are coated on the surface of a composite foil current collector at intervals, an uncoated area is reserved between the electrode slurry and the conductive substances, and the conductive substances are non-sticky at normal temperature and sticky after being heated;
s2, cutting the composite foil current collector obtained in the step S1 into pole pieces with pole lugs, wherein the conductive substances and the uncoated areas are positioned on the pole lug parts of the pole pieces; the method is convenient for thermally pressing and bonding the lugs of the plurality of pole pieces together after the lamination process;
or comprises the following steps:
a1, coating electrode slurry on the surface of a composite foil current collector, leaving a first blank area, and then drying;
a2, coating a conductive substance on a first blank area of the composite foil current collector, and then drying again, wherein an uncoated area is reserved between the conductive substance and the electrode slurry, and the conductive substance is non-sticky at normal temperature and sticky after heating;
a3, cutting the composite foil current collector obtained in the step A2 into a pole piece with a pole lug, wherein the conductive substance and the uncoated area are positioned at the pole lug part of the pole piece; the method is convenient for thermally pressing and bonding the lugs of the plurality of pole pieces together after the lamination process;
or comprises the following steps:
b1, coating a conductive substance on the surface of a composite foil current collector, leaving a second blank area, and then drying, wherein the conductive substance is non-sticky at normal temperature and sticky after heating;
b2, coating electrode slurry on a second blank area of the composite foil current collector, and then drying again, wherein an uncoated area is reserved between the electrode slurry and the conductive substance;
b3, cutting the composite foil current collector obtained in the step B2 into a pole piece with a pole lug, wherein the conductive substance and the uncoated area are positioned at the pole lug part of the pole piece; the method is convenient for thermally pressing and bonding the lugs of the plurality of pole pieces together after the lamination process;
the conductive substance is a mixture of adhesive liquid material epoxy conductive silver adhesive and an electron conductive agent, and the electron conductive agent is one of AB, SP and CNT;
the thickness of the coated conductive material after drying is 5-20 mu m;
the composite foil current collector comprises a polymer film in the middle and a first metal layer and a second metal layer respectively positioned at two sides of the thickness direction of the polymer film.
2. The method for preparing the pole piece of the composite foil current collector according to claim 1, wherein the method comprises the following steps: the hot melting temperature of the conductive material is greater than the drying temperature of the conductive material after coating.
3. The method for preparing the pole piece of the composite foil current collector according to claim 2, wherein the method comprises the following steps: the electrode slurry is coated on the middle position of the surface of the composite foil current collector, and the conductive substance is coated on at least one side of the electrode slurry.
4. The method for preparing the pole piece of the composite foil current collector according to claim 2, wherein the method comprises the following steps: the ratio of the width of the uncoated region to the width of the region coated with the conductive substance is 1/9 to 9/1.
5. The pole piece of the composite foil current collector is characterized in that: a pole piece comprising a pole piece prepared by the method of any of the preceding claims 1-4.
6. A soft pack battery characterized in that: the electrode plate comprises a diaphragm or a solid electrolyte membrane, an external positive electrode lug, an external negative electrode lug and a plurality of electrode plates in claim 5, wherein the plurality of electrode plates are respectively corresponding to the positive electrode plate and the negative electrode plate, the positive electrode plate and the negative electrode plate are arranged in a staggered and overlapped mode, the diaphragm or the solid electrolyte membrane is wound to be Z-shaped, each positive electrode plate is isolated from the negative electrode plate through the diaphragm or the solid electrolyte membrane, the plurality of electrode lugs of the positive electrode plate are overlapped and then bonded together through hot pressing, then are connected with the external positive electrode lug, and the plurality of electrode lugs of the negative electrode plate are overlapped and then bonded together through hot pressing, and then are connected with the external negative electrode lug.
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