CN205439418U - Lithium-ion battery flexible packaging material and lithium-ion battery using the material - Google Patents

Abstract

The utility model discloses the battery field specifically says, relates to a lithium ion battery soft packaging material and uses the lithium ion battery of this material. The flexible packaging material for the lithium ion battery comprises a base material layer, a first bonding layer, a metal foil layer, a second bonding layer and a sealing layer which are sequentially arranged from outside to inside; and an anti-corrosion treatment layer is arranged between the sealing layer and the second bonding layer, and is composed of a polytetrafluoroethylene film layer. The flexible packaging material provided with the anti-corrosion treatment layer is adopted, the hydrofluoric acid resistance is obviously improved, the electrochemical corrosion can be better resisted, the use safety of the lithium ion battery is enhanced, and the service life is prolonged. In order to further increase the security, be provided with at least one spacing arch to the inside extension of electricity core on the internal surface of wrapping bag, can reduce the impact of electricity core to the bag, thereby reduce the bag and be pierced through by the metal burr on the mass flow body and arouse the risk that the bag is corroded by electrochemistry or short circuit.

Description

Lithium-ion battery flexible packaging material and lithium-ion battery using the material

technical field

The utility model relates to the battery field, specifically, to a lithium-ion battery flexible packaging material and a lithium-ion battery using the material.

Background technique

In related technologies, aluminum-plastic composite films are generally used as flexible packaging materials for lithium-ion batteries. The basic composition of the aluminum-plastic composite film is the inner polypropylene film layer, the middle aluminum foil layer and the outer nylon protective layer. When the lithium-ion battery is packaged in the cell, there may be burrs or active material particles around the cell. During the pumping process, these burrs or particles will pierce the inner layer to the aluminum foil layer; during the cell packaging process, due to mechanical effects Or the inner layer of the aluminum-plastic composite film is damaged due to over-melting during heat sealing, which in turn leads to the direct contact of the aluminum foil layer with the electrolyte. The function of the air will cause the lithium-ion battery to bulge or leak and fail. At the same time, under the action of the potential difference between the positive electrode and the aluminum foil layer, lithium ions will be inserted into the aluminum foil layer through the damaged inner layer to form an aluminum-lithium alloy, which will electrochemically corrode the aluminum foil layer, thereby accelerating the corrosion of the aluminum foil layer.

It has been disclosed in the prior art that the aluminum-plastic composite film of polyamide film/thermosetting adhesive layer/aluminum foil/thermosetting adhesive layer/unsaturated acid anhydride modified polypropylene film has excellent water vapor barrier properties, explosion-proof properties and heat-sealing adhesion, but It has no obvious effect on solving electrochemical corrosion. In the prior art, there are also lithium-ion batteries with inorganic oxide-polymer coatings and transparent shells to improve electrochemical corrosion resistance. However, although polymer coatings can alleviate corrosion to a certain extent, they cannot fundamentally Solve the problem, especially under the trend that the energy density of lithium-ion batteries is getting higher and higher, and the packaging bags used are getting thinner and thinner, the corrosion problem is even more serious. In view of this, it is indeed necessary to provide a packaging material with better resistance to electrochemical corrosion.

Utility model content

The utility model proposes a lithium-ion battery soft packaging material, which can better resist electrochemical corrosion, enhance the use safety and increase the service life of the lithium-ion battery.

According to the lithium-ion battery flexible packaging material proposed in the first aspect of the utility model, it includes a substrate layer 10, a first adhesive layer 11, a metal foil layer 12, a second adhesive layer 13 and a sealing layer 15 arranged in sequence from outside to inside , An anti-corrosion treatment layer 14 is arranged between the sealing layer and the second adhesive layer, and the anti-corrosion treatment layer is composed of a polytetrafluoroethylene film layer.

Preferably, the anti-corrosion treatment layer is combined on the sealing layer; specifically, it is combined on the sealing layer by spraying or coating.

Preferably, the thickness of the anti-corrosion treatment layer does not exceed 50% of the thickness of the sealing layer.

Preferably, the sum of the thicknesses of the anti-corrosion treatment layer and the sealing layer is 30-70 μm.

Preferably, the material of the sealing layer is one or more of polyethylene terephthalate, polyvinyl chloride, polyethylene or polypropylene.

Preferably, a decoration layer 16 is further provided on the outside of the base material layer.

Preferably, the metal foil layer is an aluminum foil layer or a stainless steel foil layer.

A lithium-ion battery proposed according to the second aspect of the utility model includes a battery cell 2, a packaging bag 1 for accommodating the battery cell, and an electrolyte poured into the packaging bag, and the packaging bag uses the lithium ion battery of the present invention. Battery flexible packaging materials.

Preferably, the inner surface of the packaging bag is provided with at least one limiting protrusion 3 extending toward the inside of the electric core.

Preferably, the height of the limiting protrusion is 0.1-0.4 mm.

The technical solution provided by the application can achieve the following beneficial effects:

The lithium-ion battery provided by this application adopts a flexible packaging material combined with an anti-corrosion treatment layer, which has significantly improved hydrofluoric acid resistance, can better resist electrochemical corrosion, and enhances the safety and service life of the lithium-ion battery.

In order to further increase safety, as a supplement to the structural design of the bag, there is a protrusion on at least one inner surface in the length direction or width direction of the bag, which restricts the movement of the battery core and reduces the impact of the battery core on the bag. The impact of the bag reduces the risk of the bag being pierced by the metal burr on the current collector and causing the bag to be electrochemically corroded or short-circuited.

It is to be understood that both the foregoing general description and the following detailed description are exemplary only and are not restrictive of the application.

Description of drawings

Fig. 1 is the structural schematic diagram of the lithium-ion battery flexible packaging material without decorative layer provided by the embodiment of the present application;

Fig. 2 is the structural schematic diagram of the lithium-ion battery soft packaging material with decorative layer provided by the embodiment of the present application;

FIG. 3 is a schematic diagram of a lithium-ion battery provided with a protruding structure along the width direction in the first embodiment of the present application.

FIG. 4 is a schematic diagram of a lithium-ion battery provided in Embodiment 1 of the present application with a protruding structure provided along the length direction. Description of drawings:

1-packaging bag; 10-substrate layer; 11-first adhesive layer; 12-metal foil layer; 13-second adhesive layer; 14-anti-corrosion treatment layer; 15-sealing layer; 16-decoration layer;

2-cell;

3-limit protrusion;

4 - Polar lugs.

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the application and together with the description serve to explain the principles of the application.

detailed description

The present application will be described in further detail below through specific embodiments and in conjunction with the accompanying drawings. "Front", "back", "left", "right", "upper" and "lower" mentioned in the article refer to the lithium-ion battery flexible packaging material and the placement state of the lithium-ion battery using the material in the attached drawings .

As shown in Figure 1, a specific embodiment of the present application provides a flexible packaging material for lithium-ion batteries, the packaging material sequentially includes a substrate layer 10, a first adhesive layer 11, a metal foil layer 12, The second adhesive layer 13 , the anti-corrosion treatment layer 14 and the sealing layer 15 .

The base material layer 10 is located on the outside of the packaging material and plays the role of outer layer protection. It adopts a single-layer or multi-layer heat-resistant resin film. For the outer layer material suitable for cold stamping, it can be selected from polyamide resin or polyamide resin. Stretched or unstretched film of ester resin. And according to the appearance requirements of the product, decorative layers 16 (see FIG. 2 ) such as a matte layer and a dyed coating can also be added on the outer surface of the base material layer 10 to enhance the aesthetics of the product. The decoration layer 16 can be coated on the surface of the substrate layer 10 by means of gravure coating, or by extrusion coating on the surface of the substrate layer 10 .

The metal foil layer 12 can be a common aluminum foil layer, or a foil layer made of stainless steel, such as martensitic stainless steel, austenitic stainless steel or ferritic stainless steel.

The anti-corrosion treatment layer 14 is composed of a polytetrafluoroethylene film layer, which can be combined with the sealing layer 15 by spraying or coating.

The sealing layer 15 is located on the innermost side and is directly in contact with the electrolyte and the battery cell. It is the first protective measure for the metal foil layer 12 and also the last line of defense to prevent the battery cell and electrolyte from being affected by the external environment. In this embodiment, the material of the sealing layer 15 can be selected from materials such as polyethylene terephthalate, polyvinyl chloride, polyethylene or polypropylene. In addition, the sum of the thicknesses of the anti-corrosion treatment layer 14 and the sealing layer 15 is 30-70 μm, so as not to affect the high-temperature and high-humidity test passing ratio of the battery due to the thickness being too thin.

As shown in Figure 3, another specific embodiment of the present application provides a lithium-ion battery, including a packaging bag 1, a cell 2, tabs 4 and an electrolyte (not shown in the figure), wherein the packaging bag 1 It is made of the lithium-ion battery flexible packaging material provided in Embodiment 1, and the packaging bag 1 wraps the battery cell 2 and the electrolyte together.

The inner surface of the packaging bag is provided with at least one limiting protrusion 3 extending toward the inside of the battery core. And it is further arranged on at least one inner surface preferably in the length direction or the width direction, and the height of the limiting protrusion is 0.1-0.4 mm. In this embodiment, one inner surface of the packaging bag in the width direction has two protrusions extending toward the inside of the battery cell, and the height of the protrusions is 0.2 mm. This can increase the energy density of the lithium-ion battery as much as possible.

The technical effects of the present application will be described in detail below through experimental data.

Example 1

1. Treatment of the anti-corrosion treatment layer on the surface of the sealing layer

The anti-corrosion treatment layer 14 can be combined with the sealing layer 15 by spraying or coating.

2. Preparation of Packaging Materials

Preparation of the packaging material includes a substrate layer 10 , a first adhesive layer 11 , a metal foil layer 12 , a second adhesive layer 13 , an anti-corrosion treatment layer 14 and a sealing layer 15 from the outer layer to the inner layer. The anti-corrosion treatment layer 14 is coated on the sealing layer 15 by gravure coating. The base layer 10 used is nylon, and the bonding layer is a common adhesive.

Lithium cobaltate, conductive agent, and binder are mixed and pulped by known technology, coated on an aluminum foil current collector, dried, pressed into sheets, and cut to obtain a positive plate; artificial graphite, conductive agent, and binder are mixed to make Slurry, coated on the copper foil current collector, dried, pressed into sheets and cut to obtain the positive plate; Weld the tabs on the positive and negative plates respectively; Separate the positive plate and the negative plate with a separator and wind it into a battery core; the battery core is placed in the packaging bag 1 made of nylon film layer 10, adhesive layer 11, aluminum foil layer 12, adhesive layer 13, anti-corrosion treatment layer 14, and sealing layer 15 (wherein the anti-corrosion treatment layer 14 The thickness is 10 μm, and the thickness of the sealing layer 15 is 35 μm) for wrapping.

On the inner surface of the packaging bag in the width direction, a limit protrusion extending toward the inside of the battery cell is provided. The height of the limit protrusion is 0.2 mm, as shown in Figure 3; A limiting protrusion extending toward the inside of the cell is provided on the surface, and the height of the limiting protrusion is 0.3 mm, as shown in FIG. 4 . Place a piece of acid-modified PP polymer resin layer on the upper and lower sides of the heat-sealed side of the tab through the packaging bag 1, and then heat-seal the packaging bag 1, tab 4, and polymer resin layer. The heat-sealing temperature is 120 ~250°C; first pack the battery core into a pocket, and then inject the liquid electrolyte made of lithium hexafluorophosphate, ethylene carbonate, anti-overcharge additives, and flame retardant additives into the pocket pack; after chemical conversion, the battery The last heat seal is made into a soft-packed lithium-ion battery.

Example 2

It is basically the same as the embodiment 1, except that the thickness of the anti-corrosion treatment layer 14 is 20 μm, and the thickness of the sealing layer 15 is 35 μm.

Example 3

It is basically the same as the embodiment 1, except that the anti-corrosion treatment layer 14 has a thickness of 30 μm, and the sealing layer 15 has a thickness of 35 μm.

Example 4

It is basically the same as that of Embodiment 1, except that: the packaging bag has two protrusions on the two inner surfaces in the width direction, the protrusions face the battery cells, and the protrusions protrude at a distance of 0.2 mm.

Comparative example 1

Replace the packaging bag 1 in Example 1 with a packaging bag without an anti-corrosion treatment layer 14, and use the same method as above to make a soft-package lithium-ion battery.

Comparative example 2

The packaging bag 1 in Example 1 was replaced with a packaging bag without an anti-corrosion treatment layer 14, and no protrusions were provided on the inner surface of the packaging bag in the width direction, and a soft-packed lithium-ion battery was made by the same method as above.

The soft-packaged lithium-ion batteries prepared in Examples 1-4 and the soft-packaged lithium-ion batteries prepared in Comparative Example 1 and Comparative Example 2 were used for comparative testing. Among them, the method of accelerated corrosion test is: short-circuit the negative terminal of the charged lithium-ion battery and the packaging film with a metal wire to simulate the formation of an electronic channel, and then place the above-mentioned battery in an environment with a relative humidity of >90% at 40-50°C Store under the environment, and regularly check whether the battery case has electrochemical corrosion. Both high temperature and high humidity and vibration-vacuum simulation are used to test the airtightness of the shell. The ambient temperature of the high temperature and high humidity test is 65-75°C, and the relative humidity of the environment is 85-95%. The method of vibration-vacuum simulation test is: first The battery vibrates sinusoidally, and then the battery is transferred to an environment with a vacuum degree <-90Kpa for more than 6 hours, and whether there is liquid leakage or air leakage is judged by the weight change before and after.

Table 1

It can be seen from the comparison results that the lithium-ion battery provided by the application adopts a flexible packaging material combined with an anti-corrosion treatment layer, and the ability to resist hydrofluoric acid is significantly improved, which can better resist electrochemical corrosion and enhance the use of lithium-ion batteries. safety and increased service life. In order to further increase safety, as a supplement to the structural design of the bag, there is a protrusion on at least one inner surface in the length direction or width direction of the bag, which restricts the movement of the battery core and reduces the impact of the battery core on the bag. The impact of the bag reduces the risk of the bag being pierced by the metal burr on the current collector and causing the bag to be electrochemically corroded or short-circuited.

According to the above principles, the present application can also make appropriate changes and modifications to the above specific implementation methods. Therefore, the present application is not limited to the specific embodiments disclosed and described above, and some modifications and changes to the present application should also fall within the protection scope of the claims of the present application. In addition, although some specific terms are used in this specification, these terms are only for convenience of description and do not constitute any limitation to the present application.

Claims (9)

1. A lithium-ion battery flexible packaging material, said lithium-ion battery flexible packaging material comprises a substrate layer (10), a first adhesive layer (11), a metal foil layer (12), a second adhesive layer (10) arranged in sequence from outside to inside Adhesive layer (13) and sealing layer (15); It is characterized in that, be provided with one deck anticorrosion treatment layer (14) between described sealing layer and described second adhesive layer, described anticorrosion treatment layer is made of It is composed of a polytetrafluoroethylene film layer; the anti-corrosion treatment layer is combined on the sealing layer. 2. The lithium-ion battery flexible packaging material according to claim 1, wherein the thickness of the anti-corrosion treatment layer is no more than 50% of the thickness of the sealing layer. 3. The flexible packaging material for lithium-ion batteries according to claim 1, wherein the sum of the thicknesses of the anti-corrosion treatment layer and the sealing layer is 30-70 μm. 4. The lithium-ion battery flexible packaging material according to claim 1, wherein the material of the sealing layer is one of polyethylene terephthalate, polyvinyl chloride, polyethylene or polypropylene. 5. The lithium-ion battery flexible packaging material according to claim 1, characterized in that, a decorative layer (16) is further provided on the outside of the base material layer. 6. The flexible packaging material for lithium-ion batteries according to claim 1, wherein the metal foil layer is an aluminum foil layer or a stainless steel foil layer. 7. A lithium-ion battery, comprising an electric core (2), a packaging bag (1) for accommodating the electric core and an electrolyte poured into the packaging bag, characterized in that, the packaging bag adopts claims 1 to 6 Lithium-ion battery flexible packaging material described in any one. 8 . The lithium-ion battery according to claim 7 , wherein at least one limiting protrusion ( 3 ) extending toward the inside of the battery cell is provided on the inner surface of the packaging bag. 9 . The lithium ion battery according to claim 8 , wherein the height of the limiting protrusion is 0.1-0.4 mm.