A hot and cold press lamination core package and manufacturing method and a battery prepared by using the core package

Abstract

This invention relates to the field of rechargeable battery technology, specifically to a hot-cold pressed laminated core pack and its manufacturing method, as well as a battery prepared using this core pack. It addresses the technical problem in the prior art where, after full-area bonding of the core pack, the formation of the SEI film and side reactions during the formation process generate a large amount of gas. Because the separator and electrode are completely bonded together, the gas cannot be smoothly discharged through the interlayer gaps, resulting in stagnation at the interface. The invention includes the following steps: Step 1: Core pack preparation, where electrode sheets and a separator coated with hot melt adhesive on both sides are laminated to form an initial core pack; Step 2: Strip hot pressing, where the initial core pack is placed in a hot pressing device and hot-pressed using a pressure plate with strip-shaped protrusions. After hot pressing, adhesive bands are formed only in the areas corresponding to the strip-shaped protrusions, while the separator and electrode remain separable in the unpressed areas; Step 3: Obtaining the processed core pack, which has multiple non-connected adhesive bands distributed inside, with unbonded portions between adjacent adhesive bands forming venting channels.

Description

Technical Field

[0001] This invention relates to the field of rechargeable battery technology, specifically to a hot-cold laminated core pack, its manufacturing method, and a battery using the core pack. Background Technology

[0002] With the increasing demands for energy density in electric vehicles and energy storage systems, lithium-ion battery cell designs are trending towards larger sizes. When the cell length exceeds 500mm, the core package, formed by stacking positive electrode plates, negative electrode plates, and separators, is prone to bending during subsequent transport due to insufficient rigidity. This can lead to electrode misalignment, and in severe cases, short circuits or performance degradation. To address this issue, existing technologies employ adhesive-coated separators (such as PVDF or PMMA coated separators) and perform hot and cold pressing on the entire core package after stacking. Hot pressing melts the adhesive layer on the separator surface, and cold pressing solidifies the adhesive layer, tightly bonding the positive and negative electrode plates to the separator to form a rigid, integral core package, effectively suppressing bending during transport. However, this full-area bonding method introduces a new problem: during the formation process after electrolyte injection, the formation of the SEI film and side reactions generate a large amount of gas. Because the separator and electrode plates are completely bonded together, the gas cannot smoothly escape through the interlayer gaps into the gas bag, causing gas to stagnate between the interfaces and form "bubble-like black spots." These dark spots hinder lithium-ion transport, leading to localized lithium plating that severely reduces the cell's capacity, cycle life, and safety.

[0003] Therefore, there is an urgent need to develop a new hot-cold pressing process that can both ensure the overall rigidity of the core package to resist bending during transport and provide an effective outlet channel for the formation gas. Summary of the Invention

[0004] This invention provides a hot-cold laminated core package, a manufacturing method thereof, and a battery using the core package, to solve one of the aforementioned technical problems.

[0005] A method for manufacturing a hot-cold pressed laminated core package includes the following steps: Step 1: Core pack preparation: The electrode sheet and the separator coated with hot melt adhesive on both sides are stacked to form the initial core pack; Step 2: Strip hot pressing. The initial core package is placed in a hot pressing device, and a pressure plate with strip protrusions is used to hot press the initial core package. After hot pressing, an adhesive band is formed only in the area corresponding to the strip protrusions, and the diaphragm and electrode remain separable in the unpressed area. Step 3: Obtain the processed core package. The processed core package contains multiple unconnected adhesive strips, and the unbonded portions between adjacent adhesive strips form venting channels.

[0006] Furthermore, a cold pressing step is provided after step 2, wherein the cold pressing temperature is controlled at 15℃-30℃, the pressure is 0.3MPa-2MPa, and the time is 50s-150s.

[0007] Furthermore, the hot pressing conditions in step 2 are: temperature 80℃-120℃, pressure 0.5MPa-3MPa, and time 50s-150s.

[0008] Furthermore, the shape of the strip-shaped protrusion can be straight, wavy, or dashed.

[0009] Furthermore, the width of the strip-shaped protrusion is 1mm-10mm.

[0010] Furthermore, the spacing between adjacent strip-shaped protrusions is 5mm-30mm.

[0011] Furthermore, the direction of the strip-shaped protrusion is parallel to, perpendicular to, or at an angle of 30° or -60° to the length direction of the electrode.

[0012] The present invention also provides a battery cell pack prepared by the above method.

[0013] The present invention also provides a battery prepared using the above-described battery cell pack.

[0014] Compared with existing technologies, the advantages of this invention are: it balances bending resistance and venting; the strip-shaped adhesive tape acts as a "skeleton" to provide sufficient bending stiffness, especially ensuring that core packages with a length > 500mm do not experience significant bending or electrode misalignment during transport; at the same time, the unbonded strip-shaped areas form micron-level gaps (venting channels) parallel to the electrode layers, allowing formation gases to be quickly vented into the gas bag along these channels, avoiding dot-like black spots caused by gas stagnation and reducing the interface black spot defect rate after formation; it improves the performance of large-size LFP cells and increases capacity retention; it has good process compatibility, requiring only the replacement or modification of the hot and cold pressing plates, without changing the original lamination and assembly main process, making it easy to implement on existing production lines. Attached Figure Description

[0015] Figure 1 : Interface diagram of electrode sheet after traditional all-planar hot-cold pressing.

[0016] Figure 2 : Schematic diagram of the electrode interface after hot and cold pressing using the method of the present invention.

[0017] Figure 3 : Interface photos of large-size LFP cells from the same batch after formation, prepared using traditional methods.

[0018] Figure 4 : Interface photos of large-size LFP cells from the same batch prepared using the method of this invention after formation. Detailed Implementation

[0019] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are used only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature.

[0020] In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0021] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0022] A method for manufacturing a hot-cold pressed laminated core package includes the following steps: Step 1: Core pack preparation: The electrode sheet and the separator coated with hot melt adhesive on both sides are stacked to form the initial core pack; Step 2: Strip hot pressing. The initial core package is placed in a hot pressing device, and a pressure plate with strip protrusions is used to hot press the initial core package. After hot pressing, an adhesive band is formed only in the area corresponding to the strip protrusions, and the diaphragm and electrode remain separable in the unpressed area. Step 3: Obtain the processed core package. The processed core package contains multiple unconnected adhesive strips, and the unbonded portions between adjacent adhesive strips form venting channels.

[0023] In a preferred embodiment, a cold pressing step is provided after step 2. In the cold pressing step, the cold pressing temperature is controlled at 15℃-30℃, the pressure is 0.3MPa-2MPa, and the time is 50s-150s, so that the adhesive layer of the adhesive tape is cured and shaped to form a rigid strip-shaped adhesive skeleton.

[0024] In a preferred embodiment, the hot pressing conditions in step 2 are a temperature of 80℃-120℃, a pressure of 0.5MPa-3MPa, and a time of 50s-150s.

[0025] In a preferred embodiment, the shape of the strip-shaped protrusion is a straight line, a wavy line, or a dashed line.

[0026] In a preferred embodiment, the width of the strip-shaped protrusion is 1mm-10mm.

[0027] In a preferred embodiment, the spacing between adjacent strip-shaped protrusions is 5mm-30mm.

[0028] In a preferred embodiment, the direction of the strip-shaped protrusion is parallel to, perpendicular to, or at an angle of 30° or -60° to the length direction of the electrode.

[0029] The present invention also provides a battery cell pack manufactured by the above method.

[0030] The present invention also provides a battery made using the above-described battery cell pack.

[0031] Example 1: A stacked LFP cell with a length of 550 mm, a width of 90 mm, and a designed energy density of 190 Wh / kg was fabricated.

[0032] Positive electrode: LFP / conductive carbon / PVDF=95.5:2.5:2.0, double-sided areal density 47.8mg / cm².

[0033] Negative electrode: Artificial graphite / conductive carbon / CMC / SBR=96:1:1.2:1.8, double-sided areal density 22mg / cm².

[0034] Separator: 9μm base film + double-sided 2μm PVDF coating (hot melt adhesive layer).

[0035] Number of lamination layers: 25 layers for positive electrode and 26 layers for negative electrode.

[0036] Hot and cold pressing: A pressure plate with parallel straight strip-shaped protrusions (5mm wide, 12mm spaced, i.e., the ratio of the width D of the venting channel to the width d of the adhesive tape D / d = 2.4, and the direction of the strip-shaped protrusions is parallel to the 550mm length of the battery cell). Hot pressing temperature is 95℃, pressure is 1.2MPa, and time is 90s; then switch to a cold pressing plate (25℃), pressure is 1.0MPa, and time is 60s.

[0037] Results: After processing, the edges of the cell pack are straight, without bending or deformation. After electrolyte injection, formation (0.05C constant current charging to 3.65V), and full charging, disassembly revealed no black spots at the positive and negative electrode interfaces, indicating a good interface. A 73Ah soft-pack battery was fabricated, exhibiting normal capacity performance, with a capacity retention of 95.2% after 500 cycles at 0.5C.

[0038] Comparative Example 1 (Full Planar Hot and Cold Pressing): The process was identical to Example 1, except that the hot-cold pressing used a fully flat pressing plate (without strip-shaped protrusions). Results: The core pack exhibited good rigidity, but upon disassembly after formation, numerous dot-shaped black spots with diameters of 0.2-0.8 mm appeared on the surface of the positive electrode, covering approximately 8% of the area. After 500 cycles, the capacity retention rate was only 90.1%, a 5% decrease compared to the cell with strip-shaped embossed hot-cold pressing, and the cell showed signs of gas expansion.

[0039] Example 2: A 78Ah LFP cell (with a higher compaction density) with a length of 620mm, a width of 85mm, and a designed energy density of 195Wh / kg was prepared. The hot and cold pressing parameters were adjusted as follows: the width of the strip protrusions was 4mm, the spacing was 15mm, i.e., the ratio of the width D of the venting channel to the width d of the adhesive tape was D / d = 3.75, and the direction was parallel to the long side. The hot pressing temperature was 90℃, the pressure was 1.5MPa, and the time was 120s. The cold pressing parameters were the same as in Example 1.

[0040] Results: The core package showed no bending during transport on the automated production line; no obvious black spots were observed on the interface after formation. Capacity retention was 94.3% after 500 cycles at 0.5C.

[0041] Comparative Example 2 (Full Planar Hot and Cold Pressing): The process was identical to Example 2, except that the hot-cold pressing used a fully flat pressing plate (without strip-shaped protrusions). Results: The core pack exhibited good rigidity, but upon disassembly after formation, numerous dot-shaped black spots with diameters of 0.2-0.8 mm appeared on the surface of the positive electrode, accounting for approximately 25% of the area. After 500 cycles, the capacity retention rate was only 86.5%, representing a decrease of approximately 8% compared to the cell after strip-embossed hot-cold pressing, and the cell showed significant gas expansion. plan Hot and cold pressing Energy density Do you have dark spots? Capacity retention after 500 cycles Example 1 Strip hot and cold pressing 190Wh / kg none 95.2% Example 2 Strip hot and cold pressing 195Wh / kg none 94.3% Comparative Example 1 Full-plane hot and cold pressing 190Wh / kg Area accounting for approximately 8% 90.1% Comparative Example 2 Full-plane hot and cold pressing 195Wh / kg Area accounting for approximately 25% 86.5%

[0042] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A method for manufacturing a hot-cold pressed laminated core package, characterized in that: Includes the following steps, Step 1: Core pack preparation: The electrode sheet and the separator coated with hot melt adhesive on both sides are stacked to form the initial core pack; Step 2: Strip hot pressing. The initial core package is placed in a hot pressing device, and a pressure plate with strip protrusions is used to hot press the initial core package. After hot pressing, an adhesive band is formed only in the area corresponding to the strip protrusions, and the diaphragm and electrode remain separable in the unpressed area. Step 3: Obtain the processed core package. The processed core package contains multiple unconnected adhesive strips, and the unbonded portions between adjacent adhesive strips form venting channels.

2. The method for manufacturing a hot-cold pressed laminated core package according to claim 1, characterized in that: A cold pressing step is provided after step 2. In the cold pressing step, the cold pressing temperature is controlled at 15℃-30℃, the pressure is 0.3MPa-2MPa, and the time is 50s-150s, so that the adhesive layer of the adhesive tape is cured and shaped to form a rigid strip-shaped adhesive skeleton.

3. The method for manufacturing a hot-cold pressed laminated core package according to claim 1, characterized in that: The hot pressing conditions in step 2 are: temperature 80℃-120℃, pressure 0.5MPa-3MPa, and time 50s-150s.

4. The method for manufacturing a hot-cold pressed laminated core package according to claim 1, characterized in that: The shape of the strip-shaped protrusions can be straight, wavy, or dashed.

5. The method for manufacturing a hot-cold pressed laminated core package according to claim 1, characterized in that: The width of the strip-shaped protrusion is 1mm-10mm.

6. The method for manufacturing a hot-cold pressed laminated core package according to claim 1, characterized in that: The spacing between adjacent strip-shaped protrusions is 5mm-30mm.

7. The method for manufacturing a hot-cold pressed laminated core package according to claim 1, characterized in that: The direction of the strip-shaped protrusion is parallel to, perpendicular to, or at an angle of 30° or -60° to the length direction of the electrode.

8. A battery cell pack prepared by the method according to any one of claims 1-7.

9. A battery prepared using the battery cell pack according to claim 8.

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