WO2024230528A1 - Packaging film and battery - Google Patents

Abstract

A packaging film and a battery. The packaging film comprises a first material layer, a second material layer and a third material layer, which are sequentially stacked, wherein the second material layer comprises a first surface and a second surface, which are opposite each other, the first material layer being bonded to the first surface, and the third material layer being bonded to the second surface; the first material layer, the second material layer and the third material layer match one another, and the first material layer, the second material layer and the third material layer are sequentially aligned; the thickness of the first material layer ranges from 5 μm to 100 μm, the thickness of the second material layer ranges from 5 μm to 100 μm, and the thickness of the third material layer ranges from 10 μm to 80 μm; and the first material layer, the second material layer and the third material layer are all high-molecular polymer layers. By means of providing the three different high-molecular polymer layers, the energy density of the battery is increased.

Description

Packaging film and battery

This application claims the priority of the Chinese patent application filed with the China Patent Office on May 10, 2023, with application number 202310527356.X and application name “A packaging film and battery”, all contents of which are incorporated by reference in this application.

Technical Field

The present application relates to the field of battery technology, and in particular to a packaging film and a battery.

Background Art

With the development of battery technology, the requirements for batteries are getting higher and higher. Soft-packaged batteries are widely used in various fields, such as mobile phones, notebooks, electric vehicles, energy storage, power tools, electronic wearable devices, etc., due to their high energy density and long battery life. One of the characteristics of soft-packaged batteries is that they use aluminum-plastic composite film as the packaging shell. In the prior art, aluminum foil is arranged in the middle of the aluminum-plastic composite film. Due to the low tensile ductility of the aluminum foil in the middle, the aluminum-plastic composite film cannot be thinned and cannot be punched deeper, resulting in the problem of low battery energy density.

Summary of the invention

The embodiments of the present application provide a packaging film and a battery, which solve the problem of low battery energy density in the prior art.

In a first aspect, the present application provides a packaging film, comprising: a first material layer, a second material layer and a third material layer stacked in sequence, the second material layer comprising a first surface and a second surface opposite to each other, the first material layer being bonded to the first surface, and the third material layer being bonded to the second surface;

The first material layer, the second material layer and the third material layer match each other, and the first material layer, the second material layer and the third material layer are aligned in sequence, the thickness of the first material layer is in the range of 5 μm to 100 μm, the thickness of the second material layer is in the range of 5 μm to 100 μm, and the thickness of the third material layer is in the range of 10 μm to 80 μm;

The first material layer, the second material layer and the third material layer are all high molecular polymer layers.

Optionally, the first material layer includes: one or more of polyvinylidene chloride PVDC, polyvinylidene fluoride PVDF, cycloolefin copolymer COC, polyethylene terephthalate PET, polyethylene naphthalate PEN, polyvinyl chloride PVC, polyetheretherketone PEEK, polychlorotrifluoroethylene PCTFE, polytetrafluoroethylene PTFE and polyamide PA.

Optionally, the second material layer includes: one or more of polyvinylidene chloride PVDC, polyvinylidene fluoride PVDF, cycloolefin copolymer COC, polyethylene terephthalate PET, polyethylene naphthalate PEN, polyvinyl chloride PVC, polyetheretherketone PEEK, polychlorotrifluoroethylene PCTFE, polytetrafluoroethylene PTFE, ethylene-vinyl alcohol copolymer EVOH and ethylene-tetrafluoroethylene copolymer ETFE.

Optionally, the second material layer further comprises a barrier polymer and an inorganic substance, wherein the inorganic substance comprises one or more of Si, SiOxx≤2, Al ₂ O ₃ , BaSO ₄ , Ti ₂ O ₃ , CaCO ₃ , MgO, Y ₂ O ₃ , TiO ₂ and Gd ₂ O ₃ ;

The particle size of the inorganic substance is in the range of 30 nm to 1.5 μm, and the mass addition amount of the inorganic substance in the barrier polymer is in the range of 0.05 to 3%.

Optionally, the third material layer includes a high molecular polymer, and the high molecular polymer includes one or both of an olefin polymer and an olefin modified polymer;

The olefin polymer includes one or more of polyethylene, polypropylene, polybutene and polyolefin elastomer POE;

The olefin modified polymer includes: one or more of ethylene-acrylic acid copolymer EAA, ethylene-ethyl acrylate copolymer EEA, ethylene-methacrylic acid EMAA, polyvinyl chloride, polyvinyl fluoride, ethylene-propylene blended modified polymer, ethylene-butene blended modified polymer, maleic anhydride grafted modified polypropylene, acrylic acid grafted modified polypropylene and propylene-butene blended modified polymer.

Optionally, a first adhesive layer is further provided in the first material layer and the second material layer;

The length of the first adhesive layer is aligned with the first material layer, and the thickness of the first adhesive layer is in the range of 1 μm to 5 μm;

The first adhesive layer includes: one or more of polyurethane, acrylate, epoxy resin, phenolic resin, SBS thermoplastic resin, polyimide resin and modified polyolefin adhesive.

Optionally, a second adhesive layer is further provided in the second material layer and the third material layer;

The length of the second adhesive layer is aligned with the second material layer, and the thickness of the second adhesive layer is in the range of 1 μm to 5 μm;

The second adhesive layer includes one or more of polyurethane, acrylate, epoxy resin, phenolic resin, SBS thermoplastic resin, polyimide resin and modified polyolefin adhesive.

Optionally, the packaging film further comprises a coating;

The coating is arranged on the surface of the first material layer and away from the second material layer, the length of the coating is aligned with the first material layer, and the thickness of the coating is in the range of 1 μm to 20 μm;

The coating comprises: one or more of Si, SiOxx≤2, Al ₂ O ₃ , BaSO ₄ , Ti ₂ O ₃ , CaCO ₃ , MgO, Y ₂ O ₃ , TiO ₂ and Gd ₂ O ₃ ;

or

The coating includes: one or more of polychlorotrifluoroethylene PCTFE, polyparaxylene Parylene, polyetheretherketone PEEK, polyvinylidene chloride PVDC and polyvinylidene fluoride PVDF; wherein the polyparaxylene can be one or more of parylene C, parylene D, parylene N and parylene HT.

Optionally, the packaging film has a thickness in the range of 20 μm to 200 μm;

The peel strength between the second material layer and the third material layer is greater than or equal to 1.5N/15mm, and the peel strength between the first material layer and the third material layer is greater than or equal to 1.5N/15mm.

A second aspect of the present application further provides a battery, the battery comprising the packaging film as described in any one of the first aspects.

The present application provides a packaging film and a battery, the packaging film comprising: a first material layer, a second material layer and a third material layer stacked in sequence, the second material layer comprising a first surface and a second surface opposite to each other, the first material layer is bonded to the first surface, and the third material layer is bonded to the second surface; the first material layer, the second material layer and the third material layer match, and the first material layer, the second material layer and the third material layer are aligned in sequence, the thickness of the first material layer is in the range of 5μm to 100μm, the thickness of the second material layer is in the range of 5μm to 100μm, and the thickness of the third material layer is in the range of 10μm to 80μm; the first material layer, the second material layer and the third material layer are all high molecular polymer layers. The present application improves the energy density of the battery by setting three layers of different high molecular polymer layers.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is one of the structural schematic diagrams of a packaging film provided in an embodiment of the present application;

FIG2 is a second schematic diagram of the structure of a packaging film provided in an embodiment of the present application;

FIG. 3 is a third schematic diagram of the structure of a packaging film provided in an embodiment of the present application.

DETAILED DESCRIPTION

The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

It should be mentioned before discussing the exemplary embodiments in more detail that some exemplary embodiments are described as processes or methods depicted as flow charts. Although the flow charts describe the steps as sequential processes, many of the steps therein can be implemented in parallel, concurrently or simultaneously. In addition, the order of the steps can be rearranged. The process can be terminated when its operation is completed, but can also have additional steps not included in the accompanying drawings. The process can correspond to a method, function, procedure, subroutine, subprogram, etc.

In addition, the terms "first", "second", etc. can be used in this article to describe various directions, actions, steps or elements, but these directions, actions, steps or elements are not limited by these terms. These terms are only used to distinguish a first direction, action, step or element from another direction, action, step or element. For example, without departing from the scope of the present application, the first speed difference can be referred to as the second speed difference, and similarly, the second speed difference can be referred to as the first speed difference. Both the first speed difference and the second speed difference are speed differences, but they are not the same speed difference. The terms "first", "second", etc. cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Thus, the features defined as "first" and "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

As shown in FIG1 , an embodiment of the present application provides a packaging film, comprising: a first material layer 100, a second material layer 200, and a third material layer 300 stacked in sequence, wherein the second material layer 200 comprises a first surface and a second surface opposite to each other, the first material layer 100 is bonded to the first surface, and the third material layer 300 is bonded to the second surface;

The first material layer 100, the second material layer 200 and the third material layer 300 match each other, and the first material layer 100, the second material layer 200 and the third material layer 300 are aligned in sequence, the thickness of the first material layer 100 is in the range of 5 μm to 100 μm, the thickness of the second material layer 200 is in the range of 5 μm to 100 μm, and the thickness of the third material layer 300 is in the range of 10 μm to 80 μm. In the range of μm;

The first material layer 100 , the second material layer 200 , and the third material layer 300 are all high molecular polymer layers.

In this embodiment, the packaging film is a non-metallized composite film. In actual use, the packaging film covers the outer surface of the battery to prevent the battery from being exposed to the air for a long time, and plays a role in heat sealing and corrosion resistance. Wherein, the matching of the first material layer 100, the second material layer 200 and the third material layer 300 means that the first material layer 100, the second material layer 200 and the third material layer 300 have the same length.

Specifically, the packaging film is a first material layer 100, a second material layer 200 and a third material layer 300 which are stacked in sequence, wherein the first material layer 100 is a protective layer, the second material layer 200 is a barrier layer, and the third material layer 300 is a heat sealing layer. The first material layer 100, the second material layer 200 and the third material layer 300 are all high molecular polymer layers, which have extremely high tensile properties and have extremely high molding depths compared to conventional metal composite films, which can greatly improve the energy density of the battery. It should also be noted that when each layer structure is a high molecular polymer layer, it has good corrosion resistance, no risk of electrochemical corrosion, and can improve the safe service life of the battery.

The present application provides a packaging film, which includes: a first material layer 100, a second material layer 200 and a third material layer 300 stacked in sequence, the second material layer 200 includes a first surface and a second surface opposite to each other, the first material layer 100 is bonded to the first surface, and the third material layer 300 is bonded to the second surface; the first material layer 100, the second material layer 200 and the third material layer 300 match each other, and the first material layer 100, the second material layer 200 and the third material layer 300 are aligned in sequence, the thickness of the first material layer 100 is in the range of 5μm to 100μm, the thickness of the second material layer 200 is in the range of 5μm to 100μm, and the thickness of the third material layer 300 is in the range of 10μm to 80μm; the first material layer 100, the second material layer 200 and the third material layer 300 are all high molecular polymer layers. The present application improves the energy density of the battery by setting three different high molecular polymer layers.

In other feasible embodiments, the first material layer 100 includes: one or more of polyvinylidene chloride PVDC, polyvinylidene fluoride PVDF, cycloolefin copolymer COC, polyethylene terephthalate PET, polyethylene naphthalate PEN, polyvinyl chloride PVC, polyetheretherketone PEEK, polychlorotrifluoroethylene PCTFE, polytetrafluoroethylene PTFE and polyamide PA.

The second material layer 200 includes: polyvinylidene chloride PVDC, polyvinylidene fluoride PVDF, cycloolefin copolymer COC, polyethylene terephthalate PET, polyethylene naphthalate PEN, polyvinyl chloride PVC, polyetheretherketone PEEK, polychlorotrifluoroethylene PCTFE, polytetrafluoroethylene PTFE, One or more of ethylene-vinyl alcohol copolymer EVOH and ethylene-tetrafluoroethylene copolymer ETFE.

The second material layer 200 further comprises a barrier polymer and an inorganic substance, wherein the inorganic substance comprises one or more of Si, SiOxx≤2, Al ₂ O ₃ , BaSO ₄ , Ti ₂ O ₃ , CaCO ₃ , MgO, Y ₂ O ₃ , TiO ₂ and Gd ₂ O ₃ ;

The particle size of the inorganic substance is in the range of 30 nm to 1.5 μm, and the mass addition amount of the inorganic substance in the barrier polymer is in the range of 0.05 to 3%.

It should be noted that the second material layer 200 is preferably polyvinylidene chloride PVDC and polyvinylidene fluoride PVDF. Polyvinylidene chloride PVDC is the most commonly used packaging material in food packaging because of its good barrier properties and stability to oxygen and water vapor. Its water vapor transmission coefficient is 1-1.5g/m2.day, while PP of the same thickness is 6 times that. Polyvinylidene chloride PVDC is preferred because of its high barrier properties, which can be used as an auxiliary barrier for the oxide vacuum coating 600.

The third material layer 300 includes a high molecular polymer, and the high molecular polymer includes one or both of an olefin polymer and an olefin modified polymer;

The olefin polymer includes one or more of polyethylene, polypropylene, polybutene and polyolefin elastomer POE;

The olefin modified polymer includes: one or more of ethylene-acrylic acid copolymer EAA, ethylene-ethyl acrylate copolymer EEA, ethylene-methacrylic acid EMAA, polyvinyl chloride, polyvinyl fluoride, ethylene-propylene blended modified polymer, ethylene-butene blended modified polymer, maleic anhydride grafted modified polypropylene, acrylic acid grafted modified polypropylene and propylene-butene blended modified polymer.

In other feasible embodiments, as shown in FIG. 2 , a first adhesive layer 400 is further provided in the first material layer 100 and the second material layer 200 ;

The length of the first adhesive layer 400 is aligned with the first material layer 100 , and the thickness of the first adhesive layer 400 is in the range of 1 μm to 5 μm;

The first adhesive layer 400 includes: one or more of polyurethane, acrylate, epoxy resin, phenolic resin, SBS thermoplastic resin, polyimide resin and modified polyolefin adhesive.

A second adhesive layer 500 is further provided in the second material layer 200 and the third material layer 300;

The length of the second adhesive layer 500 is aligned with the second material layer 200 , and the thickness of the second adhesive layer 500 is in the range of 1 μm to 5 μm;

The second adhesive layer 500 includes one or more of polyurethane, acrylate, epoxy resin, phenolic resin, SBS thermoplastic resin, polyimide resin and modified polyolefin adhesive.

In this embodiment, the protective layer and the barrier layer, and the barrier layer and the heat-sealing layer are bonded by an adhesive layer. Specifically, a first adhesive layer 400, namely, an outer adhesive layer, is added between the protection layer and the barrier layer; and a second adhesive layer 500, namely, an inner adhesive layer, is compounded between the barrier layer and the heat-sealing layer.

In other feasible embodiments, as shown in FIG3 , the packaging film further includes a coating layer 600;

The coating layer 600 is disposed on the surface of the first material layer 100 and away from the second material layer 200 . The length of the coating layer 600 is aligned with the first material layer 100 . The thickness of the coating layer 600 is in the range of 1 μm to 20 μm.

The coating layer 600 includes: one or more of Si, SiOxx≤2, Al ₂ O ₃ , BaSO ₄ , Ti ₂ O ₃ , CaCO ₃ , MgO, Y ₂ O ₃ , TiO ₂ and Gd ₂ O ₃ ;

or

The coating 600 includes: one or more of polytrifluorochloroethylene PCTFE, polyparaxylene Parylene, polyetheretherketone PEEK, polyvinylidene chloride PVDC and polyvinylidene fluoride PVDF; wherein the polyparaxylene can be one or more of parylene C, parylene D, parylene N and parylene HT.

In this embodiment, a coating layer 600 is added to the outer surface (the side away from the barrier layer) of the first material layer 100, and the thickness of the coating layer 600 is in the range of 1 μm to 20 μm. It should be noted that the first adhesive layer 400, the second adhesive layer 500 and the coating layer 600 are arranged in sequence, specifically, the lengths of the first adhesive layer 400, the second adhesive layer 500 and the coating layer 600 are the same, and are the same as the lengths of the three material layers.

In this embodiment, the thickness of the packaging film is in the range of 20 μm to 200 μm;

The peel strength between the second material layer 200 and the third material layer 300 is greater than or equal to 1.5 N/15 mm, and the peel strength between the first material layer 100 and the third material layer 300 is greater than or equal to 1.5 N/15 mm.

In this embodiment, the thickness of the packaging film is preferably in the range of 30 μm to 100 μm; each layer of the packaging film in this embodiment is a high molecular polymer layer, which has good corrosion resistance and no risk of electrochemical corrosion, and can increase the safe service life of the battery.

In this embodiment, the packaging film obtained by the above structure has the following characteristics: the water vapor transmission rate of the packaging film is ≤0.5g/( ^m2 ·d) under the conditions of temperature 38°C and humidity 90%; the transverse tensile strength and longitudinal tensile strength of the packaging film are respectively greater than or equal to 30MPa, and the transverse elongation at break and longitudinal elongation at break of the packaging film are respectively greater than or equal to 50%; the surface dyne value of the outer surface of the packaging film is ≥28dynes/cm; the transverse heat shrinkage rate and longitudinal heat shrinkage rate of the packaging film at a temperature of 130°C and a time of 30min are respectively less than or equal to 5%.

In other embodiments, a battery is provided, comprising the packaging film as described in any one of the above items.

It should be noted that the battery is generally a secondary battery. Exemplarily, the battery can be a lithium-ion battery, a lithium metal battery, a lithium-sulfur battery, a sodium battery, a solid-state battery, and the like.

The following examples and comparative examples are evaluated and compared according to the performance test examples described below, specifically:

Example 1

The packaging film of this embodiment has a total thickness of 65 μm, wherein the heat-sealing layer is a 30 μm polypropylene layer, the barrier layer is a 14 μm PVDC layer, and the protective layer is a 15 μm PCTFE layer; wherein the protective layer and the barrier layer are laminated together via an outer adhesive layer of a 3 μm polyurethane layer, and the barrier layer and the heat-sealing layer are laminated together via an inner adhesive layer of a 3 μm modified polypropylene adhesive; in the packaging film, the peel strength between the barrier layer and the heat-sealing layer is 6.5 N/15 mm, and the peel strength between the protective layer and the barrier layer is 4.6 N/15 mm.

Example 2

The packaging film of this embodiment has a total thickness of 36 μm, a heat-sealing layer is a 20 μm ethylene-propylene blended modified polymer layer, a barrier layer is a 5 μm PVDC layer, a protective layer is a 5 μm PET layer, and the protective layer is coated with a ₂ μm SiO2 inorganic layer; wherein, the protective layer and the barrier layer are compositely bonded together by an outer adhesive layer of a 2 μm acrylic adhesive layer, and the barrier layer and the heat-sealing layer are compositely bonded together by an inner adhesive layer of a 2 μm polyurethane adhesive; in the packaging film, the peel strength between the barrier layer and the heat-sealing layer is 4.4 N/15 mm, and the peel strength between the protective layer and the barrier layer is 3.3 N/15 mm.

Example 3

The packaging film of this embodiment has a total thickness of 100 μm, and the heat-sealing layer is a mixed layer of 40 μm polypropylene, POE, and ethylene-butene blended modified polymer layers, the barrier layer is a 35 μm PCTFE layer, the protective layer is a 15 μm PA layer, and a 5 μm polyparaxylene layer is provided outside the protective layer; wherein, the protective layer and the barrier layer are compositely bonded together by an outer adhesive layer of 2 μm acrylic adhesive, and the barrier layer and the heat-sealing layer are compositely bonded together by an inner adhesive layer of 3 μm polyurethane adhesive; in the packaging film, the peel strength between the barrier layer and the heat-sealing layer is 7.2 N/15 mm, and the peel strength between the protective layer and the barrier layer is 5.4 N/15 mm.

Example 4

The packaging film of this embodiment has a total thickness of 178 μm, the heat sealing layer is a mixed layer of 45 μm polypropylene, POE, polyvinyl chloride, and ethylene-butylene blended modified polymer layer, and the barrier layer is 100 μm PCTFE, The mixed modified layer is of PVDF and inorganic _SiO2 , and the protective layer is a 25μm PET and PA co-extruded layer, wherein the protective layer and the barrier layer are laminated together by an outer adhesive layer of 5μm fluororubber adhesive layer, and the barrier layer and the heat sealing layer are laminated together by an inner adhesive layer of 3μm acid anhydride grafted modified polypropylene adhesive; in the packaging film, the peel strength between the barrier layer and the heat sealing layer is 12.6N/15mm, and the peel strength between the protective layer and the barrier layer is 6.8N/15mm.

Example 5

The packaging film of this embodiment has a total thickness of 65μm, wherein the heat-sealing layer is a 30μm polypropylene layer, the barrier layer includes a barrier polymer PVDC and _an inorganic substance _Al2O3 , wherein the particle size of _Al2O3 is 1μm, and _the mass addition amount of _Al2O3 in the barrier _polymer is 2%, the thickness is 14μm, and the protective layer is a 15μm PCTFE layer; wherein the protective layer and the barrier layer are compositely bonded together by an outer adhesive layer of a 3μm polyurethane layer, and the barrier layer and the heat-sealing layer are composited together by an inner adhesive layer of a 3μm modified polypropylene adhesive; in the packaging film, the peel strength between the barrier layer and the heat-sealing layer is 6.2N/15mm, and the peel strength between the protective layer and the barrier layer is 4.1N/15mm.

Example 6

The packaging film of this embodiment has a total thickness of 65μm, wherein the heat-sealing layer is a 30μm polypropylene layer, the barrier layer includes a barrier polymer PVDC and _an inorganic substance _Al2O3 , wherein the particle size of _Al2O3 is 2μm, and _the mass addition amount of _Al2O3 in the barrier _polymer is 4%, the thickness is 14μm, and the protective layer is a 15μm PCTFE layer; wherein the protective layer and the barrier layer are compositely bonded together by an outer adhesive layer of a 3μm polyurethane layer, and the barrier layer and the heat-sealing layer are composited together by an inner adhesive layer of a 3μm modified polypropylene adhesive; in the packaging film, the peel strength between the barrier layer and the heat-sealing layer is 5.2N/15mm, and the peel strength between the protective layer and the barrier layer is 2.8N/15mm.

Example 7

The packaging film of this embodiment has a total thickness of 68 μm, wherein the heat-sealing layer is a 30 μm polypropylene layer, the barrier layer is a 14 μm PVDC layer, and the protective layer is a 15 μm PCTFE layer; wherein the protective layer and the barrier layer are laminated together by an outer adhesive layer of a 6 μm polyurethane layer, and the barrier layer and the heat-sealing layer are laminated together by an inner adhesive layer of a 3 μm modified polypropylene adhesive; in the packaging film, the peel strength between the barrier layer and the heat-sealing layer is 6.8 N/15 mm, and the peel strength between the protective layer and the barrier layer is 4.5 N/15 mm.

Example 8

The packaging film of this embodiment has a total thickness of 68 μm, wherein the heat sealing layer is a 30 μm polypropylene layer, the barrier layer is a 14 μm PVDC layer, and the protective layer is a 15 μm PCTFE layer; wherein the protective layer The barrier layer is laminated together with an outer adhesive layer of 3μm polyurethane, and the barrier layer and the heat-sealing layer are laminated together with an inner adhesive layer of 6μm modified polypropylene adhesive; in the packaging film, the peel strength between the barrier layer and the heat-sealing layer is 6.6N/15mm, and the peel strength between the protective layer and the barrier layer is 4.5N/15mm.

Example 9

The packaging film of this embodiment has a total thickness of 95.5 μm, and the heat-sealing layer is a mixed layer of 40 μm polypropylene, POE, and ethylene-butene blended modified polymer layers, the barrier layer is a 35 μm PCTFE layer, the protective layer is a 15 μm PA layer, and a 0.5 μm polyparaxylene layer is provided outside the protective layer; wherein, the protective layer and the barrier layer are compositely bonded together by an outer adhesive layer of 2 μm acrylic adhesive layer, and the barrier layer and the heat-sealing layer are compositely bonded together by an inner adhesive layer of 3 μm polyurethane adhesive; in the packaging film, the peel strength between the barrier layer and the heat-sealing layer is 7.0 N/15 mm, and the peel strength between the protective layer and the barrier layer is 4.8 N/15 mm.

Comparative Example 1

The packaging film of this comparative example is specifically a conventional aluminum-plastic film with a thickness of 86 μm, and its structural components and thicknesses are: 30 μm polypropylene layer, 3 μm inner adhesive layer, 35 μm aluminum foil layer, 3 μm outer adhesive layer, and 15 μm nylon; in the packaging film, the peel strength between the barrier layer and the heat-sealing layer is 6.2 N/15 mm, and the peel strength between the protective layer and the barrier layer is 3.8 N/15 mm.

Comparative Example 2

The packaging film of this comparative example is specifically a conventional aluminum-plastic film with a thickness of 153 μm, and its structural components and thicknesses are: polypropylene layer 80 μm, inner adhesive layer 3 μm, aluminum foil layer 40 μm, outer adhesive layer 3 μm, nylon 15 μm, and PET layer 12 μm; in the packaging film, the peel strength between the barrier layer and the heat-sealing layer is 9.8 N/15 mm, and the peel strength between the protective layer and the barrier layer is 5.4 N/15 mm.

Comparative Example 3

The packaging film in this comparative example is basically the same as that in Example 1, except that the thickness of the protective layer is adjusted to 3 μm; in this packaging film, the peel strength between the barrier layer and the heat-sealing layer is 6.2 N/15 mm, and the peel strength between the protective layer and the barrier layer is 1.6 N/15 mm.

Comparative Example 4

The packaging film in this comparative example is basically the same as that in Example 1, except that the thickness of the barrier layer is adjusted to 3 μm; in this packaging film, the peel strength between the barrier layer and the heat-sealing layer is 6.8 N/15 mm, and the peel strength between the protective layer and the barrier layer is 4.8 N/15 mm.

Comparative Example 5

The packaging film in this comparative example is basically the same as that in Example 1, except that the thickness of the heat-sealing layer is adjusted to 8 μm; in this packaging film, the peel strength between the barrier layer and the heat-sealing layer is 6.6 N/15 mm, and the peel strength between the protective layer and the barrier layer is 4.4 N/15 mm.

The packaging films obtained in Examples 1 to 4 and Comparative Examples 1 to 2 were used to prepare lithium cobalt oxide soft-pack batteries in the following manner:

1) Lithium cobalt oxide, conductive agent, binder, solvent and other additives are put into a stirring tank in a certain manner, and after being stirred and mixed evenly, they are coated on the surface of a 9μm positive electrode current collector, and the obtained electrode sheet is then dried, rolled and cut in sequence to obtain a positive electrode sheet of a certain size; similarly, graphite, conductive agent, binder, solvent and other additives are put into a stirring tank in a certain proportion and feeding method, and after being stirred and mixed evenly, they are coated on the surface of a 6μm copper foil current collector, and then dried, rolled and cut to obtain a negative electrode sheet of a desired size;

2) welding the positive electrode sheet and the negative electrode sheet obtained in step 1) to the tabs in the reserved foil welding area, and then winding them with a separator to obtain a winding core;

4) The prepared roll core is placed in the packaging film obtained in the above-mentioned embodiment and comparative example, and the top side is packaged, and then baking, liquid injection, sealing, aging, formation, secondary sealing, sorting and capacity division are performed to obtain the desired battery cell; wherein the obtained battery cell has a voltage of 4.45V, a capacity of 5000mAh, and a consistent size.

Test Example 1

The packaging films obtained in Examples 1 to 4 and Comparative Examples 1 to 2 were tested for water vapor transmission rate according to GB/T 1037-1988 "Test Method for Water Vapor Permeability of Plastic Film and Sheet - Cup Method" (refer to the test principle of the WPT-301B water vapor transmission rate tester using the permeable cup weighing method). The specific operating steps are: under the conditions of 38°C and 90% relative humidity, a specific humidity difference is formed on both sides of the sample, and water vapor passes through the sample in the permeable cup into the dry side. By measuring the change in the weight of the permeable cup over time, the water vapor transmission rate and other parameters of the sample are obtained. The relevant water vapor transmission rate results are shown in Table 1.

Test Example 2

The packaging films obtained in Examples 1 to 4 and Comparative Examples 1 to 2 were subjected to a stamping performance test according to the group standard T/CIAPS0005-2018 "Aluminum-plastic composite film for lithium-ion batteries" to confirm the corresponding deep drawing limit capacity of each group. The specific operation steps are: referring to the stamping die and stamping conditions of the group standard, under the conditions of 25°C ± 3°C and relative humidity of 65% ± 10%, the test was performed with a 0.5mm depth increase gradient until the sample broke through, and the critical stamping depth that did not break through was recorded as the deep drawing limit capacity of the sample. The relevant deep drawing limit capacity results are shown in Table 1.

Test Example 3

The prepared battery cells were subjected to a moisture and heat resistance test. The specific test steps were as follows: fully charge the battery cells and test the thickness H1 of each battery cell, then place them in a constant temperature and humidity chamber at a temperature of 60°C and a relative humidity of 95% for 7 days, take them out after storage and let them stand at room temperature for 2 hours, then immediately test the thickness H2 of each battery cell, and finally calculate the thickness expansion rate H of the battery cell. If the thickness expansion H≤10%, it can be judged as qualified, otherwise it is unqualified. The relevant test results are shown in Table 1. The calculation formula of H is as follows,

Test Example 4

The prepared battery cells were subjected to high temperature storage test. The specific test steps were as follows: fully charge the battery cells and test the thickness h1 of each battery cell, then place them in a constant temperature and humidity chamber at 60°C and 95% relative humidity for 30 days, take them out after storage and test the thickness h2 of each battery cell immediately after standing at room temperature for 2 hours, and finally calculate the thickness expansion rate h of the battery cell. If the thickness expansion h≤10%, it can be judged as qualified, otherwise it is unqualified. The relevant test results are shown in Table 1. The calculation formula of h is as follows,

Table 1

From the test results in Table 1, it can be seen that a packaging film and a battery containing the packaging film have obvious advantages in terms of deep punching limit capability, and can greatly improve the energy density of the battery; in addition, the packaging film of the present application is not much different from the conventional aluminum-plastic composite film in terms of water vapor permeability, moisture and heat resistance, and high-temperature storage performance, and can meet the overall sealing and water vapor barrier requirements of the battery.

Note that the above are only preferred embodiments of the present application and the technical principles used. Those skilled in the art will understand that the present application is not limited to the specific embodiments described herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the scope of protection of the present application. Therefore, although the present application is described in more detail through the above embodiments, the present application is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present application, and the scope of the present application is determined by the scope of the appended claims.

Claims (10)

A packaging film, comprising: a first material layer, a second material layer and a third material layer stacked in sequence, wherein the second material layer comprises a first surface and a second surface opposite to each other, the first material layer is bonded to the first surface, and the third material layer is bonded to the second surface; The first material layer, the second material layer and the third material layer match each other, and the first material layer, the second material layer and the third material layer are aligned in sequence, the thickness of the first material layer is in the range of 5 μm to 100 μm, the thickness of the second material layer is in the range of 5 μm to 100 μm, and the thickness of the third material layer is in the range of 10 μm to 80 μm; The first material layer, the second material layer and the third material layer are all high molecular polymer layers. The packaging film according to claim 1, wherein the first material layer comprises one or more of polyvinylidene chloride (PVDC), polyvinylidene fluoride (PVDF), cycloolefin copolymer (COC), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyvinyl chloride (PVC), polyetheretherketone (PEEK), polychlorotrifluoroethylene (PCTFE), polytetrafluoroethylene (PTFE) and polyamide (PA). According to the packaging film according to claim 1, the second material layer comprises one or more of polyvinylidene chloride (PVDC), polyvinylidene fluoride (PVDF), cycloolefin copolymer (COC), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyvinyl chloride (PVC), polyetheretherketone (PEEK), polychlorotrifluoroethylene (PCTFE), polytetrafluoroethylene (PTFE), ethylene-vinyl alcohol copolymer (EVOH) and ethylene-tetrafluoroethylene copolymer (ETFE). The packaging film according to claim 3, wherein the second material layer further comprises a barrier polymer and an inorganic substance, and the inorganic substance comprises one or more of Si, SiOxx≤2, Al ₂ O ₃ , BaSO ₄ , Ti ₂ O ₃ , CaCO ₃ , MgO, Y ₂ O ₃ , TiO ₂ and Gd ₂ O ₃ ; The particle size of the inorganic substance is in the range of 30 nm to 1.5 μm, and the mass addition amount of the inorganic substance in the barrier polymer is in the range of 0.05 to 3%. The packaging film according to claim 1, wherein the third material layer comprises a high molecular polymer, and the high molecular polymer comprises one or both of an olefin polymer and an olefin modified polymer; The olefin polymer includes one or more of polyethylene, polypropylene, polybutene and polyolefin elastomer POE; The olefin modified polymers include: ethylene-acrylic acid copolymer EAA, ethylene-ethyl acrylate copolymer One or more of EEA polymer, ethylene-methacrylic acid EMAA, polyvinyl chloride, polyvinyl fluoride, ethylene-propylene blended modified polymer, ethylene-butene blended modified polymer, maleic anhydride grafted modified polypropylene, acrylic acid grafted modified polypropylene and propylene-butene blended modified polymer. The packaging film according to claim 1, wherein a first adhesive layer is further provided in the first material layer and the second material layer; The length of the first adhesive layer is aligned with the first material layer, and the thickness of the first adhesive layer is in the range of 1 μm to 5 μm; The first adhesive layer includes: one or more of polyurethane, acrylate, epoxy resin, phenolic resin, SBS thermoplastic resin, polyimide resin and modified polyolefin adhesive. The packaging film according to claim 1, wherein a second adhesive layer is further provided in the second material layer and the third material layer; The length of the second adhesive layer is aligned with the second material layer, and the thickness of the second adhesive layer is in the range of 1 μm to 5 μm; The second adhesive layer includes: one or more of polyurethane, acrylate, epoxy resin, phenolic resin, SBS thermoplastic resin, polyimide resin and modified polyolefin adhesive. The packaging film according to claim 1, wherein the packaging film further comprises a coating; The coating is arranged on the surface of the first material layer and away from the second material layer, the length of the coating is aligned with the first material layer, and the thickness of the coating is in the range of 1 μm to 20 μm; The coating comprises: one or more of Si, SiOxx≤2, Al ₂ O ₃ , BaSO ₄ , Ti ₂ O ₃ , CaCO ₃ , MgO, Y ₂ O ₃ , TiO ₂ and Gd ₂ O ₃ ; or The coating includes: one or more of polychlorotrifluoroethylene PCTFE, polyparaxylene Parylene, polyetheretherketone PEEK, polyvinylidene chloride PVDC and polyvinylidene fluoride PVDF; wherein the polyparaxylene can be one or more of parylene C, parylene D, parylene N and parylene HT. The packaging film according to claim 1, wherein the thickness of the packaging film is in the range of 20 μm to 200 μm; The peel strength between the second material layer and the third material layer is greater than or equal to 1.5N/15mm, and the peel strength between the first material layer and the third material layer is greater than or equal to 1.5N/15mm. A battery, wherein the battery comprises a package as claimed in any one of claims 1 to 9 membrane.