Current collector, pole piece, and battery with patterned resistive coating

Abstract

The application discloses a current collector with a patterned resistance coating, a pole piece and a battery. The current collector with the patterned resistance coating comprises a conductive base material and a conductive coating arranged on at least one surface of the conductive base material, wherein the conductive coating is discontinuously distributed on the surface of the conductive base material to form a predetermined patterned structure; and the conductive coating forms different resistance values in different regions of the current collector to form a non-uniform resistance distribution on a macro scale, so as to control the charge and discharge reaction depth of the electrode in different regions. The application controls the charge and discharge depth to improve the layer spacing, aims to control the charge depth of different regions of the electrode at the end of charging, further controls the expansion ratio of the negative electrode in different regions, optimizes the electrode layer spacing and liquid retention design, and improves the comprehensive performance of the battery.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery technology, and in particular to a current collector, electrode, and battery with a patterned resistive coating. Background Technology

[0002] Lithium-ion battery manufacturing processes are divided into stacking and winding processes. The winding process is relatively mature, and its equipment cost is low, with a high degree of automation, so most battery manufacturers use the winding process. However, as the energy density of lithium-ion batteries gradually increases and the capacity of individual cells continues to rise, the thickness and areal density of the electrode sheets are also increasing, leading to increased risks such as internal stress and uneven electrolyte distribution. In particular, batteries produced by the winding process experience rebound expansion of the positive and negative electrodes after electrolyte injection and charge / discharge, causing uneven stress within the cell. This risk is exacerbated, especially as battery manufacturers are increasing cell capacity, battery size, and electrode compaction thickness. At the same time, the electrolyte retention space is severely compressed, resulting in reduced electrolyte absorption by the electrode assembly, affecting battery power performance and cycle life.

[0003] Common improvement solutions include refining the physical structure of the electrodes, such as through electrode embossing. Electrode embossing involves thickening the electrodes before winding by creating raised points of different shapes on the electrode surface. This thickens the electrode, providing ample space for the other electrode to rebound. After electrolyte injection, formation, and capacity testing, this extra space reduces stress between the positive and negative electrodes. While embossing creates grooves on the electrode surface, optimizing electrode layer spacing and electrolyte retention design, it also presents challenges such as increased electrode thickness affecting capacity design and the risk of physical damage from electrode compression. In particular, increased electrode thickness makes cell capacity design difficult, and issues like material loss, strip breakage, and difficulties in electrode winding still exist during the embossing process. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings and defects of the prior art and provide a current collector, electrode and battery with a patterned resistive coating. By controlling the charging and discharging depth, the interlayer spacing is improved. The invention aims to regulate the charging depth of different regions of the terminal electrode, thereby regulating the expansion ratio of the negative electrode in different regions, optimizing the electrode interlayer spacing and liquid retention design, and improving the overall performance of the battery.

[0005] In a first aspect, the present invention provides a current collector having a patterned resistive coating, comprising a conductive substrate and a conductive coating disposed on at least one surface of the conductive substrate, wherein the conductive coating is discontinuously distributed on the surface of the conductive substrate to form a predetermined patterned structure; the conductive coating forms different resistance values ​​in different regions of the current collector, forming a non-uniform resistance distribution on a macroscopic scale, for controlling the charge-discharge reaction depth of the electrode in different regions.

[0006] Preferably, the non-uniform resistance distribution of the conductive coating on the current collector varies in a gradient along a predetermined direction.

[0007] Preferably, the predetermined direction includes a first predetermined direction from the electrode connection end toward a direction away from the electrode.

[0008] Preferably, the non-uniform resistance distribution exhibits a gradient change from large to small along a first predetermined direction and is symmetrically distributed.

[0009] Preferably, the non-uniform resistance distribution of the conductive coating on the current collector is arranged in a periodic uniform manner.

[0010] Preferably, the patterned structure is selected from one or more combinations of grid, stripe, dot matrix, and honeycomb patterns.

[0011] Preferably, the area ratio of the coated area to the exposed substrate area is 1:9 to 9:1.

[0012] Preferably, the conductive substrate is one of aluminum foil, copper foil, or alloy foil; the conductive coating includes a conductive agent and an adhesive, wherein the conductive agent is selected from one or more of carbon nanotubes, conductive carbon black, graphene, and acetylene black; and the adhesive is selected from one or more of polyvinylidene fluoride, styrene-butadiene rubber, sodium carboxymethyl cellulose, and polyacrylic acid.

[0013] A second aspect of the invention provides an electrode comprising the current collector having a patterned resistive coating.

[0014] A third aspect of the present invention provides a battery comprising the electrode as claimed in the claims.

[0015] The current collector with a patterned resistive coating provided by the present invention comprises a conductive substrate and a conductive coating disposed on at least one surface of the conductive substrate. The conductive coating does not continuously cover the entire surface of the conductive substrate, but is distributed in a predetermined pattern. Therefore, within the area covered by the conductive coating, or between different pattern units of the discontinuous conductive coating, its resistance value exhibits a stepped change or a discontinuous distribution. This achieves the purpose of optimizing the interlayer spacing and electrolyte distribution design by controlling the expansion ratio of the negative electrode during charging and discharging, thus avoiding the risks of capacity design difficulties and electrode loss that exist in methods such as physical embossing. Attached Figure Description

[0016] Figure 1 This is a first schematic diagram of a current collector with a patterned resistive coating according to the present invention.

[0017] Figure 2 This is a second schematic diagram of the current collector with a patterned resistive coating according to the present invention.

[0018] Figure 3 This is a third schematic diagram of the current collector with a patterned resistive coating according to the present invention. Detailed Implementation

[0019] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0020] See Figures 1 to 3 As shown in the exemplary embodiment of this application, a current collector with a patterned resistive coating is provided, including a conductive substrate and a conductive coating disposed on at least one surface of the conductive substrate. The conductive coating is discontinuously distributed on the surface of the conductive substrate to form a predetermined patterned structure. The conductive coating forms different resistance values ​​in different regions of the current collector, forming a non-uniform resistance distribution on a macroscopic scale, which is used to control the charging and discharging reaction depth of the electrode in different regions.

[0021] The present invention achieves a structural optimization of electrode layer spacing by discontinuously distributing the conductive coating on the surface of the conductive substrate, resulting in a difference in resistance between coated and uncoated areas; furthermore, it causes a difference in reaction depth between coated and uncoated areas during charging / discharging; and since there is a strong correlation between the negative electrode expansion thickness and the reaction depth, it further enables coated and uncoated areas to correspond to different negative electrode thicknesses.

[0022] The conductive coating described in this application forms a patterned structure in different regions of the current collector; furthermore, it enables the negative electrodes in different regions to form corresponding gap distributions, thereby achieving the purpose of adjusting the electrolyte regional distribution design.

[0023] The conductive coating described in this application forms a patterned structure in different regions of the current collector; furthermore, it creates a corresponding electronic resistance difference distribution in different regions, thereby achieving the purpose of controlling the overcurrent heating design in different regions of the electrode.

[0024] In this application, the patterned structure is selected from one or more combinations of grid, stripe, dot matrix, and honeycomb patterns.

[0025] As a specific embodiment, the non-uniform resistance distribution of the conductive coating on the current collector in this application varies in a gradient along a predetermined direction, wherein the predetermined direction includes a first predetermined direction from the tab connection end to away from the tab, such that the non-uniform resistance distribution varies in a gradient from large to small along the first predetermined direction and is symmetrically distributed.

[0026] As a specific embodiment, the non-uniform resistance distribution of the conductive coating on the current collector in this application is arranged in a periodic uniform manner.

[0027] When applying the conductive coating, the area ratio of the coating coverage area to the exposed substrate area is 1:9 to 9:1, and the specific design should be selected within this range according to the needs of the battery.

[0028] The conductive substrate is one of aluminum foil, copper foil, or alloy foil, with a thickness of 4-20 μm; the conductive coating includes a conductive agent and an adhesive, with a single-sided thickness of 0.4 mm to 0.8 mm; the conductive agent is selected from one or more of carbon nanotubes, conductive carbon black, graphene, and acetylene black; the adhesive is selected from one or more of polyvinylidene fluoride, styrene-butadiene rubber, sodium carboxymethyl cellulose, and polyacrylic acid; the solid mass ratio of the conductive agent to the adhesive ranges from 2:8 to 8:2.

[0029] In a further embodiment of the present invention, an electrode is provided, comprising the current collector having a patterned resistive coating, and an electrode active material layer coated on the surface of the current collector.

[0030] In a further embodiment of the present invention, a battery is provided, comprising the electrode sheet as described in the claims, wherein the electrode sheet is a positive electrode sheet and / or a negative electrode sheet, and further comprising a separator and an electrolyte.

[0031] Example 1:

[0032] Current collector preparation: Combining the coating production method, the coating pattern of the positive electrode aluminum foil current collector is set as follows: Figure 1 As shown, along the coating direction, tab areas 3 are left on both sides of the positive electrode carbon-coated aluminum foil 1. The current collector coating pattern 2 is symmetrically distributed and is divided into two parts along the center of symmetry during the cell assembly process. The conductive coating pattern is distributed in a grid, and the grid density of the conductive coating pattern gradually decreases from the tab side to the center of symmetry; the area ratio of the conductive coating coverage area to the exposed substrate area is 1:9. The conductive coating is made by mixing polyacrylic acid adhesive (24.4% solid content), conductive carbon black SP, and solvent water in a ratio of 20:5:75; the thickness of the conductive coating is 0.6 mm.

[0033] Positive electrode preparation: Lithium iron phosphate positive electrode active material (LFP), conductive carbon black (SP), carbon nanotubes (CNT), and binder (PVDF5130) are mixed in a mass ratio of 97.1:0.8:0.7:1.4. Using NMP as a solvent, a slurry with a solid content of 67% is prepared using a dual planetary apparatus. The slurry is then coated onto the surface of the current collector using a coating machine, with a single-sided surface density of 22.3 mg / mm2. After drying, rolling, and slitting processes, the positive electrode is obtained.

[0034] Battery assembly: Using this positive electrode sheet, paired with a graphite electrode as the negative electrode, a 7+2+2 dot-bonded ceramic separator (7μm base film + 2μm double-sided ceramic coating), and a LiPF6 electrolyte system, a 63Ah square aluminum-cased battery is assembled.

[0035] Test data: Compared to the control group of batteries (with full coverage of the current collector coating and no pattern design), the battery using the current collector of this embodiment:

[0036] Liquid absorption of the electrode group: 98g in the control group and 106g in the example, an increase of 8.1%.

[0037] The DCIR of the battery cell decreases by approximately 14% during 1C discharge.

[0038] The temperature rise of the battery cell during 2C discharge decreases by approximately 2°C.

[0039] Cell capacity retention rate after 1000 cycles: 91.7% for the control group and 93.3% for the example.

[0040] Example 2: Dot matrix design of conductive coating on positive electrode carbon-coated aluminum foil

[0041] Current collector preparation: Combining the coating production method, the current collector coating pattern of the positive electrode aluminum foil is as follows... Figure 2 The design includes tab areas 3 on both sides of the positive electrode carbon-coated aluminum foil 1 along the coating direction. The current collector conductive coating pattern 2 is symmetrically distributed and is divided into two parts along the center of symmetry during the cell assembly process. The current collector conductive coating pattern 2 is distributed in a dot matrix pattern, with the area of ​​each dot gradually decreasing from the tab side towards the center of symmetry. The area ratio of the current collector conductive coating area to the exposed substrate area is 5:5. The conductive coating is made by mixing polyacrylic acid adhesive (24.4% solid content), conductive carbon black SP, and solvent water in a ratio of 18:4.4:77.6. The thickness of the conductive coating is 0.5 mm.

[0042] Positive electrode preparation: Nickel-cobalt-manganese ternary positive electrode active material (NCM), conductive carbon black (SP), conductive graphite (KS15), and binder (PVDF5130) were mixed in a mass ratio of 98.3:0.5:0.2:1.0. Using NMP as a solvent, a slurry with a solid content of 68% was prepared using a dual planetary apparatus. This slurry was then coated onto the surface of the current collector using a coating machine, achieving a single-sided surface density of 20.4 mg / mm². 2 After drying, rolling, and slitting processes, positive electrode sheets are obtained.

[0043] Battery assembly: Using this positive electrode sheet, paired with a graphite electrode as the negative electrode, a 9+2+2+2 dot-bonded double-sided ceramic separator (9μm base film + 2μm double-sided ceramic coating), and a LiPF6 electrolyte system, a 125Ah square aluminum-cased battery is assembled.

[0044] Test data: Compared to the control group of batteries (with full coverage of the current collector coating and no pattern design), the battery using the current collector of this embodiment:

[0045] Liquid absorption of the electrode group: 212g in the control group and 225g in the example group, an increase of 6.1%.

[0046] The DCIR of the battery cell decreases by approximately 18% during 1C discharge.

[0047] The temperature rise of the battery cell during 3C discharge decreases by approximately 4°C.

[0048] Cell capacity retention rate after 1000 cycles: 85.5% for the control group and 92.1% for the example.

[0049] Example 3:

[0050] Current collector preparation: Combining the coating production method, the current collector coating pattern of the negative electrode copper foil is as follows... Figure 3 The design includes tab areas 3 on both sides of the negative electrode copper foil 1 along the coating direction. The current collector coating pattern 2 is uniformly distributed and is divided into two parts along the center of symmetry during the cell assembly process. The conductive coating pattern is honeycomb-shaped, with the area ratio of the conductive coating coverage area to the exposed substrate area being 9:1. The conductive coating is made by mixing polyvinylidene fluoride (PVDF), conductive carbon black (SP), and solvent NMP in a ratio of 10:10:80; the conductive coating thickness is 0.5 mm.

[0051] Negative electrode preparation: Graphite negative electrode material (C), conductive carbon black (SP), styrene-butadiene rubber (SBR), and sodium carboxymethyl cellulose (CMC) are mixed in a mass ratio of 96.1:0.5:2.0:1.4. Deionized water is used as a solvent, and a slurry with a solid content of 49% is prepared using a dual planetary apparatus. The slurry is then coated onto the surface of the current collector using a coating machine, with a single-sided surface density of 11.4 mg / mm2. After drying, rolling, and slitting processes, the negative electrode is obtained.

[0052] Battery assembly: Using this negative electrode sheet, paired with a lithium iron phosphate positive electrode, and employing a 9+2+2 dot-bonded ceramic separator (7μm base film + double-sided 2μm ceramic coating), and using a LiPF6 electrolyte system, a 314Ah square aluminum-cased battery is assembled.

[0053] Test data: The battery using the current collector of this embodiment, compared with the control group of batteries (current collector without coating):

[0054] Liquid absorption of the electrode group: 541g in the control group and 566g in the example, an increase of 4.6%.

[0055] The DCIR of the battery cell decreases by approximately 7% during 1C discharge.

[0056] Energy retention rate of battery cells after 2000 cycles: 94.4% for the control group and 96.1% for the example.

[0057] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, the embodiments should be regarded as exemplary and non-limiting in all respects. The scope of the present invention is defined by the appended claims rather than the foregoing description, and therefore all changes falling within the meaning and scope of the equivalents of the claims are intended to be included within the present invention.

[0058] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A current collector having a patterned resistive coating, characterized in that, The device includes a conductive substrate and a conductive coating disposed on at least one surface of the conductive substrate. The conductive coating is discontinuously distributed on the surface of the conductive substrate to form a predetermined patterned structure. The conductive coating forms different resistance values ​​in different regions of the current collector, forming a non-uniform resistance distribution on a macroscopic scale, which is used to control the charging and discharging reaction depth of the electrode in different regions.

2. The current collector with a patterned resistive coating according to claim 1, characterized in that, The non-uniform resistance distribution of the conductive coating on the current collector varies in a gradient along a predetermined direction.

3. The current collector with a patterned resistive coating according to claim 2, characterized in that, The predetermined direction includes a first predetermined direction from the electrode connection end toward a direction away from the electrode.

4. The current collector with a patterned resistive coating according to claim 3, characterized in that, The non-uniform resistance distribution exhibits a gradient change from large to small along a first predetermined direction and is symmetrically distributed.

5. The current collector with a patterned resistive coating according to claim 1, characterized in that, The non-uniform resistance distribution of the conductive coating on the current collector is arranged in a periodic uniform pattern.

6. The current collector with a patterned resistive coating according to claim 1, characterized in that, The patterned structure is selected from one or more combinations of grid, stripe, dot matrix, and honeycomb patterns.

7. The current collector with a patterned resistive coating according to claim 1, characterized in that, The area ratio of the coated area to the exposed substrate area is 1:9 to 9:

1.

8. The current collector with a patterned resistive coating according to claim 1, characterized in that, The conductive substrate is one of aluminum foil, copper foil, or alloy foil; the conductive coating includes a conductive agent and an adhesive, wherein the conductive agent is selected from one or more of carbon nanotubes, conductive carbon black, graphene, and acetylene black; and the adhesive is selected from one or more of polyvinylidene fluoride, styrene-butadiene rubber, sodium carboxymethyl cellulose, and polyacrylic acid.

9. An electrode, characterized in that, The current collector having a patterned resistive coating as described in any one of claims 1-8.

10. A battery, characterized in that, Includes the electrode sheet as described in claim 9.

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