A new soft package material for lithium ion battery and lithium ion battery

Abstract

The application discloses a novel soft package material for lithium ion batteries and a lithium ion battery, and relates to the technical field of lithium ion batteries. The novel soft package material for lithium ion batteries comprises, from outside to inside, an outer protective layer, an outer adhesive bonding layer, a chromizing treatment layer, a tin layer, a tin / aluminum alloy layer, an aluminum foil layer, a chromizing treatment layer, an inner adhesive bonding layer and an inner heat sealing layer. The lithium ion battery is made of the novel soft package material for lithium ion batteries. The novel soft package material for lithium ion batteries has the advantages of excellent anti-warping performance and simple preparation process steps.

Description

Technical Field

[0001] This invention belongs to the field of lithium battery pouch materials, and specifically relates to a novel pouch material for lithium-ion batteries and a lithium-ion battery. Background Technology

[0002] Lithium-ion battery pouch material is a composite material used to protect the inner core of a lithium-ion battery. It is generally composed of materials such as nylon, aluminum foil, and polypropylene. As the outer shell of the lithium battery, the pouch material protects the internal structure. Functionally, lithium-ion battery packaging materials mainly consist of three layers: an outer protective layer, a middle barrier layer, and an inner heat-sealing layer. The middle barrier layer is often made of aluminum-plastic film.

[0003] In the production and processing of lithium battery pouch materials, the aluminum-plastic film undergoes deep-drawing. Due to the film manufacturing process and the stretching effect of the aluminum-plastic film after deep-drawing, the outer nylon film exhibits macroscopic tensile stress. This manifests as severe warping of the film edges after deep-drawing, affecting subsequent cutting, packaging, and other operations. Currently, methods for controlling film stress mainly include film layer mechanical matching design, manufacturing process control, and post-processing stress release, but these methods involve relatively complex process steps. Summary of the Invention

[0004] The purpose of this invention is to provide a novel soft-pack material for lithium-ion batteries and a lithium-ion battery, which has the advantages of excellent anti-warping performance and simple preparation process.

[0005] The above-mentioned technical objective of the present invention is achieved through the following technical solution:

[0006] A novel soft-pack material for lithium-ion batteries includes, from the outside to the inside, an outer protective layer, an outer adhesive layer, a chromated layer, a tin layer, a tin / aluminum alloy layer, an aluminum foil layer, a chromated layer, an inner adhesive layer, and an inner heat-sealing layer, stacked sequentially.

[0007] Further preferably, the method for preparing the tin layer includes at least the following steps:

[0008] S1: Clean and dry the aluminum foil layer;

[0009] S2: Using an aluminum foil layer as a base, a tin target is deposited on the surface of the aluminum foil through a sputtering process to form a tin / aluminum composite layer, and the tin on the surface is the tin layer.

[0010] Further optimization yielded the following sputtering process parameters: sputtering voltage 400V, sputtering current 0.2A, sputtering power 80W, and vacuum degree 3.5×10⁻⁶. -3 Pa, argon partial pressure 0.4 Pa, tin film deposition rate 150 nm / min, target / substrate spacing 70 mm.

[0011] Further preferably, the tin layer, tin / aluminum alloy layer, and aluminum foil layer are obtained by heat treatment of the tin / aluminum composite layer in a vacuum oven. Further preferably, the thickness of the tin / aluminum alloy layer is 0.1 μm.

[0012] Further optimization yielded the following heat treatment parameters: vacuum degree 9×10-2MPa, temperature 200℃, and time 30min.

[0013] Further preferably, the outer protective layer is a biaxially oriented nylon film, the outer adhesive layer is a two-component polyurethane adhesive layer, the tin layer is a 99.9% pure tin sputtering material, the aluminum foil layer is an 8021O-state aluminum alloy, the inner adhesive layer is a multifunctional epoxy resin adhesive layer, and the inner heat-sealing layer is a modified cast polypropylene film. Further preferably, the outer protective layer thickness is 25 μm, the outer adhesive layer thickness is 4 μm, the aluminum foil layer thickness is 40 μm, the tin layer thickness is 0.5 μm, the inner adhesive layer thickness is 4 μm, and the inner heat-sealing layer thickness is 40 μm.

[0014] Further preferably, the chromate treatment layer uses a trivalent chromium passivating agent and is formed by roller coating. Further preferably, the thickness of the chromate treatment layer is 0.05 μm.

[0015] A lithium-ion battery made of a novel soft-pack material for lithium-ion batteries.

[0016] In summary, the present invention has the following beneficial effects:

[0017] 1. The stress of the aluminum foil layer is controlled by the interface alloying method. By adding a tin layer and under certain conditions, an alloy phase (solid solution) is generated at the interface between the aluminum foil layer and the tin layer, which causes lattice distortion and volume expansion of the interface. This alleviates the warping of the aluminum-plastic film caused by nylon stress and improves the overall anti-warping performance of the lithium battery soft pack material.

[0018] 2. A tin layer is added using a sputtering process, and an alloy phase is generated at the interface between the aluminum foil layer and the tin layer through heat treatment. The process steps are simple. Attached Figure Description

[0019] Figure 1 This is a structural schematic diagram of a novel soft-pack material for lithium-ion batteries.

[0020] Figure 2 It is a two-dimensional contour image of the edge of the aluminum-plastic film.

[0021] The attached diagram shows the following labels: 1. Outer protective layer; 2. Outer adhesive layer; 3. Chromated layer; 4. Tin layer; 5. Tin / aluminum alloy layer; 6. Aluminum foil layer; 7. Inner adhesive layer; 8. Inner heat-sealing layer. Detailed Implementation

[0022] The present invention will now be described in detail with reference to preferred embodiments and accompanying drawings.

[0023] like Figure 1 As shown in the preferred embodiment, a novel soft-pack material for lithium-ion batteries is prepared by the following steps:

[0024] S1: Clean and dry 8021O state aluminum foil with alcohol and ultrasonic cleaning;

[0025] S2: Using 8021O state aluminum foil as the substrate, a two-stage DC sputtering coating equipment is used to deposit 99.9% pure tin target material onto the surface of the aluminum foil through sputtering process to form a tin / aluminum composite layer;

[0026] S3: The tin / aluminum composite layer is placed in a vacuum oven for heat treatment, so that a tin / aluminum alloy layer appears in the tin / aluminum composite layer;

[0027] S4: A chromium-treated layer is applied to the tin surface by roller coating, and a biaxially oriented nylon film is laminated to it using a two-component polyurethane adhesive.

[0028] S5: A chromated layer is applied to the aluminum surface by roller coating, and a modified cast polypropylene film is composited with it using a multifunctional epoxy resin adhesive.

[0029] S6: The composite soft-pack material is hot-pressed and then cured at 70°C for 6 days to obtain a new type of soft-pack material for lithium-ion batteries.

[0030] Table 1 - Thickness of each layer of the soft-pack material in the preferred embodiment

[0031] Thickness / μm outer protective layer 25 outer adhesive layer 4 Chromium treatment layer 0.05 Tin layer 0.5 Tin / aluminum alloy layer 0.1 Aluminum foil layer 40 Inner adhesive layer 4 Inner heat seal layer 40

[0032] Comparative example: conventional aluminum-plastic film.

[0033] Performance testing

[0034] 1. Drawing performance test

[0035] Sample size: 100×120mm

[0036] Drawing die model: 105050, die edge radius: 1.5, corner radius: 1.5, drawing depth: 7mm

[0037] Table 2 - Test Results of Deep Drawing Forming Performance

[0038]

[0039]

[0040] 2. Anti-warping performance test

[0041] Measure the specimens in the deep drawing test and compare the differences in warpage.

[0042] Table 3 - Results of Anti-warping Performance Test

[0043] Sample Warp height / mm Preferred embodiment 0.7 Comparative Example 4

[0044] Combining Tables 2 and 3, and combining Figure 2 It is understood that the novel aluminum-plastic film structure of the present invention uses a tin layer / tin-aluminum alloy layer / aluminum layer instead of an aluminum layer, which has both excellent deep-drawing formability and anti-warping performance.

[0045] The above-described embodiments are merely explanations of the present invention and are not intended to limit the present invention. After reading this specification, those skilled in the art can make modifications to these embodiments without contributing any inventive step, but such modifications are protected by patent law as long as they are within the scope of the claims of the present invention.

Claims

1. A novel soft-pack material for lithium-ion batteries, characterized in that, It includes an outer protective layer (1), an outer adhesive layer (2), a chromating layer (3), a tin layer (4), a tin / aluminum alloy layer (5), an aluminum foil layer (6), a chromating layer (3), an inner adhesive layer (7), and an inner heat-sealing layer (8), which are stacked sequentially from the outside to the inside. The method for preparing the tin layer (4) includes at least the following steps: S1: Clean and dry the aluminum foil layer (6); S2: Using aluminum foil layer (6) as a substrate, tin target material is deposited on the surface of aluminum foil layer (6) by sputtering process to form tin / aluminum composite layer, and the tin on its surface is tin layer (4); The tin layer (4), tin / aluminum alloy layer (5), and aluminum foil layer (6) are obtained by heat treatment of the tin / aluminum composite layer in a vacuum oven.

2. The novel soft-pack material for lithium-ion batteries according to claim 1, characterized in that, The sputtering process parameters are: sputtering voltage 400V, sputtering current 0.2A, sputtering power 80W, and vacuum degree 3.5×10⁻⁶. -3 Pa, argon partial pressure 0.4 Pa, tin film deposition rate 150 nm / min, target / substrate spacing 70 mm.

3. The novel soft-pack material for lithium-ion batteries according to claim 1, characterized in that, The heat treatment parameters are: vacuum degree 9×10 -2 MPa, temperature 200℃, time 30min.

4. The novel soft-pack material for lithium-ion batteries according to claim 1, characterized in that, The outer protective layer (1) is a biaxially oriented nylon film, the outer adhesive layer (2) is a two-component polyurethane adhesive layer, the tin layer (4) is a tin target material with a purity of 99.9%, the aluminum foil layer (6) is an 8021O state aluminum alloy, the inner adhesive layer (7) is a multifunctional epoxy resin adhesive layer, and the inner heat-sealing layer (8) is a modified cast polypropylene film.

5. The novel soft-pack material for lithium-ion batteries according to claim 1, characterized in that, The chromated layer (3) is made by roller coating using a trivalent chromium passivating agent.

6. A lithium-ion battery, characterized in that, It is made using the novel soft-pack material for lithium-ion batteries as described in any one of claims 1-5.

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