阅读说明：本技术 隔离膜、锂离子电芯及用电装置 (Isolating membrane, lithium ion battery cell and electric device ) 是由 宋传涛 于 2021-07-13 设计创作，主要内容包括：本申请实施例涉及电池技术领域,公开了隔离膜、锂离子电芯及用电装置。锂离子电芯包括第一极片、第二极片以及隔离膜,第一极片和第二极片之间设有隔离膜。隔离膜包括隔离膜基材以及设于隔离膜基材的涂层,隔离膜通过涂层与相邻的第一极片或第二极片粘接固定。涂层被配置为所述涂层被配置为在温度高于预设阈值时使所述隔离膜与外部的部件之间的剥离力降低或能够与酸性物质发生化学反应。本申请实施例提供的锂离子电芯在温度高于某阈值时,隔离膜与相邻的极片之间的剥离力降低。即是,该锂离子电芯可改善电芯在温度高于某阈值时,隔离膜与极片之间的剥离力仍较高的现状。(The embodiment of the application relates to the technical field of batteries and discloses an isolating membrane, a lithium ion battery cell and an electric device. The lithium ion battery cell comprises a first pole piece, a second pole piece and an isolating membrane, wherein the isolating membrane is arranged between the first pole piece and the second pole piece. The isolating film comprises an isolating film substrate and a coating arranged on the isolating film substrate, and the isolating film is fixedly bonded with the adjacent first pole piece or the second pole piece through the coating. The coating is configured such that the coating is configured to reduce a peeling force between the separator and an external member or to be capable of chemically reacting with an acidic substance when a temperature is higher than a preset threshold value. When the temperature of the lithium ion battery cell provided by the embodiment of the application is higher than a certain threshold value, the stripping force between the isolating film and the adjacent pole piece is reduced. That is, the lithium ion battery cell can improve the current situation that the peeling force between the isolating film and the pole piece is still high when the temperature of the battery cell is higher than a certain threshold value.)

1. An isolation film is characterized by comprising an isolation film substrate and a coating layer arranged on the surface of the isolation film substrate, wherein the isolation film is fixedly bonded with an external component of the isolation film through the coating layer;

the coating is configured to reduce a peel force between the release film and the external component when a temperature is above a preset threshold; alternatively, the first and second electrodes may be,

the coating is configured to chemically react with an acidic substance to reduce the peel force.

2. The separator of claim 1, wherein the coating comprises:

a micro-matrix particle configured to be capable of chemically reacting with an acidic substance; and

and the adhesive is used for adhering the micro-matrix particles to the isolating film substrate.

3. The separator of claim 2, wherein the micro-matrix particles comprise an alkaline substance.

4. The separator of claim 2, wherein the micro-matrix particles comprise carbonates comprising at least one of:

lithium carbonate, sodium bicarbonate, calcium carbonate, and magnesium carbonate.

5. The separator of claim 2, wherein the coating is configured to decrease in intensity when the temperature is above the preset threshold;

the coating comprises:

micro-matrix particles configured to soften or melt at a temperature above the preset threshold; and

and the adhesive is used for adhering the micro-matrix particles to the isolating film substrate.

6. The separator of claim 5, wherein the micro-matrix particles comprise at least one of:

polyethylene, polypropylene, ethylene propylene rubber, ethylene propylene random polymers, 1-butene and 1-propylene polymers, ethylene butene propylene copolymers and block copolymerized polypropylene.

7. The separator according to any one of claims 2 to 6, wherein the microparticulate is spherical, ellipsoidal, flaky, tetragonal or prismoid.

8. The separator of any of claims 2-6, wherein the maximum linear dimension of the micro-matrix particles is less than 5 μm.

9. The release film of any one of claims 2 to 6, wherein the binder is in the form of particles, and the ratio of the maximum diameter of the particles of the binder to the maximum diameter of the particles of the micro-matrix is less than 0.5.

10. The separator according to any one of claims 2 to 6, wherein the surface area of the micro base particles coated with the binder accounts for 10% to 90% of the surface area of the micro base particles.

11. The separator of any of claims 2 to 6, wherein the coating further comprises a dispersant;

the mass percentage of the micro-matrix particles in the coating is more than 90%;

the mass percentage of the adhesive in the coating is less than 10%;

the mass percentage of the dispersant in the coating is less than 2%.

12. A lithium ion cell comprising an electrode assembly, wherein the electrode assembly comprises:

a first pole piece;

a second pole piece; and

the isolating film according to any one of claims 1 to 11, wherein the isolating film is arranged between the first pole piece and the second pole piece, and the isolating film is bonded and fixed with the adjacent first pole piece or the second pole piece through the coating.

13. The li-ion battery cell of claim 12, wherein the li-ion battery cell further comprises an electrolyte;

the electrolyte is configured to generate the acidic substance when a temperature is above the set threshold.

14. An electric device comprising the lithium ion battery cell according to claim 13.

[ technical field ] A method for producing a semiconductor device

The embodiment of the application relates to the technical field of batteries, in particular to an isolating membrane, a lithium ion battery cell and an electric device.

[ background of the invention ]

A lithium ion battery cell is a device that converts external energy into electrical energy and stores the electrical energy in the battery cell so as to supply power to an external electrical device (e.g., a portable electronic device) at a desired time. At present, lithium ion batteries are widely used in electronic products such as mobile phones, tablet computers, notebook computers and the like.

Generally, a lithium ion battery includes a case, an electrode assembly housed in the case, and tabs connected to the electrode assembly and partially protruding out of the case. The electrode assembly comprises a first pole piece, a second pole piece and a separation film. The isolation film is arranged between the adjacent first pole piece and the second pole piece and is bonded and fixed with the adjacent first pole piece and the second pole piece, so that the first pole piece, the second pole piece and the isolation film are fixed.

When the lithium ion battery cell has abnormal accidents such as short circuit or overcharge, thermal runaway can occur, high-temperature gas can be generated inside the shell, the high-temperature gas can enable the shell to expand along the thickness direction of the shell, and the shell can adaptively contract along the length direction and the width direction of the shell and further extrude the electrode assembly; meanwhile, the temperature of the electrode assembly is continuously increased, and the electrolyte generates acidic substances due to the high temperature. When the lithium ion cell is in a high temperature state, the isolation film and the pole piece (the first pole piece or the second pole piece) cannot be separated in time, so that the temperature of the lithium ion cell continuously rises, heat accumulated inside the cell is difficult to dissipate in time, and further safety accidents such as explosion and the like may be caused.

[ summary of the invention ]

The embodiment of the application aims at providing an isolating membrane, a lithium ion cell and a power consumption device, wherein the isolating membrane can improve the peeling force between the isolating membrane and a pole piece when the temperature of the lithium ion cell is higher than a certain threshold value, and further is favorable for opening the interface between the isolating membrane and the pole piece so as to increase the heat dissipation area inside the cell and improve the stability of the cell.

In order to solve the technical problem, the embodiment of the application adopts the following technical scheme:

a lithium ion cell comprises an electrode assembly, wherein the electrode assembly comprises a first pole piece, a second pole piece and a separation film, and the separation film is arranged between the first pole piece and the second pole piece. The isolating film comprises an isolating film substrate and a coating arranged on the isolating film substrate, and the isolating film is fixedly bonded with the adjacent first pole piece or the second pole piece through the coating; the coating is configured to reduce a peeling force between the release film and the external member when a temperature is higher than a preset threshold value, or the coating is configured to be capable of chemically reacting with an acidic substance. In some embodiments, the predetermined threshold may be 100 ℃; in other embodiments, the predetermined threshold may be 130 ℃; in still other embodiments, the predetermined threshold may be 150 ℃.

When the temperature of the lithium ion cell provided by the embodiment of the application is higher than the preset threshold value, the stripping force between the isolating membrane and the adjacent first pole piece or second pole piece is reduced, and then the bonding interface between the isolating membrane and the pole pieces is favorably opened, so that the contact area between the electrode assembly and the electrolyte is increased, the heat dissipation area inside the lithium ion cell is further increased, and the stability of the lithium ion cell is improved.

As a further improvement of the above technical solution, the lithium ion battery further includes an electrolyte. The electrolyte is configured to generate the acidic substance when a temperature is above the set threshold.

As a further improvement of the above technical solution, the coating layer includes micro-matrix particles and a binder. The micro-matrix particles are configured to chemically react with the acidic substance. The adhesive is used for adhering the micro-matrix particles to the release film substrate.

As a further improvement of the above technical solution, the micro matrix particles include an alkaline substance.

As a further improvement of the above technical solution, the micro matrix particles comprise carbonates, the carbonates comprising at least one of the following: lithium carbonate, sodium bicarbonate, calcium carbonate, and magnesium carbonate.

As a further improvement of the above technical solution, the coating layer includes micro-matrix particles and a binder. The micro-matrix particles are configured to soften or melt when the temperature is above the preset threshold. And the adhesive is used for adhering the micro-matrix particles to the isolating film substrate.

As a further improvement of the above technical solution, the micro matrix particles include at least one of: polyethylene, polypropylene, ethylene propylene rubber, ethylene propylene random polymers, 1-butene and 1-propylene polymers, ethylene butene propylene copolymers and block copolymerized polypropylene.

As a further improvement of the above technical solution, the micro-matrix particles are spherical, ellipsoidal, flaky, tetragonal or prismoid.

As a further improvement of the above technical solution, the maximum linear dimension of the micro-matrix particles is less than 5 μm.

As a further improvement of the technical scheme, the adhesive is granular, and the ratio of the maximum diameter of the granules of the adhesive to the maximum diameter of the particles of the micro-matrix is between 0.1 and 0.5.

As a further improvement of the above technical means, a surface area of the microparticulate substrate coated with the binder accounts for 10% to 90% of a surface area of the microparticulate substrate.

As a further improvement of the technical scheme, the coating also comprises a dispersing agent. The mass percentage of the micro-matrix particles in the coating is more than 90%, the mass percentage of the adhesive in the coating is less than 10%, and the mass percentage of the dispersant in the coating is less than 2%.

Another embodiment of the present application further provides an isolation film, where the isolation film includes an isolation film substrate and a coating layer disposed on the isolation film substrate, and the isolation film is bonded and fixed to the adjacent first pole piece or the adjacent second pole piece through the coating layer; the coating is configured to decrease in intensity when the temperature is above a preset threshold, or the coating is configured to be capable of chemically reacting with an acidic substance.

As a further improvement of the above technical solution, the lithium ion battery further includes an electrolyte. The electrolyte is configured to generate the acidic substance when a temperature is above the set threshold.

As a further improvement of the above technical solution, the coating layer includes micro-matrix particles and a binder. The micro-matrix particles are configured to chemically react with the acidic substance. The adhesive is used for adhering the micro-matrix particles to the release film substrate.

As a further improvement of the above technical solution, the micro matrix particles include an alkaline substance.

As a further improvement of the above technical solution, the micro matrix particles comprise carbonates, the carbonates comprising at least one of the following: lithium carbonate, sodium bicarbonate, calcium carbonate, and magnesium carbonate.

As a further improvement of the above technical solution, the coating layer includes micro-matrix particles and a binder. The micro-matrix particles are configured to soften or melt when the temperature is above the preset threshold. And the adhesive is used for adhering the micro-matrix particles to the isolating film substrate.

As a further improvement of the above technical solution, the micro matrix particles include at least one of: polyethylene, polypropylene, ethylene propylene rubber, ethylene propylene random polymers, 1-butene and 1-propylene polymers, ethylene butene propylene copolymers and block copolymerized polypropylene.

As a further improvement of the above technical solution, the micro-matrix particles are spherical, ellipsoidal, flaky, tetragonal or prismoid.

As a further improvement of the above technical solution, the maximum linear dimension of the micro-matrix particles is less than 5 μm.

As a further improvement of the technical scheme, the adhesive is granular, and the ratio of the maximum diameter of the granules of the adhesive to the maximum diameter of the particles of the micro-matrix is between 0.1 and 0.5.

As a further improvement of the above technical means, a surface area of the microparticulate substrate coated with the binder accounts for 10% to 90% of a surface area of the microparticulate substrate.

As a further improvement of the technical scheme, the coating also comprises a dispersing agent. The mass percentage of the micro-matrix particles in the coating is more than 90%; the mass percentage of the adhesive in the coating is less than 10%; the mass percentage of the dispersant in the coating is less than 2%.

Another embodiment of the present application further provides an electric device, which includes any one of the lithium ion batteries described above.

[ description of the drawings ]

One or more embodiments are illustrated in drawings corresponding to, and not limiting to, the embodiments, in which elements having the same reference number designation may be represented as similar elements, unless specifically noted, the drawings in the figures are not to scale.

Fig. 1 is a schematic perspective view of a lithium ion battery provided in an embodiment of the present application;

FIG. 2 is a sectional view of the rear edge A-A of the hidden housing of the lithium ion battery cell in FIG. 1;

FIG. 3 is a partial configuration view of the electrode assembly of FIG. 2;

FIG. 4 is a partial schematic view of the coating of FIG. 3;

FIG. 5 is a schematic illustration of the coating of FIG. 3 after partial etching;

fig. 6 is a graph of interfacial peel force between respective separator films and adjacent pole pieces in the lithium ion cell of fig. 1 and the conventional lithium ion cell as a function of temperature;

FIG. 7 is a schematic view of a partial configuration of an electrode assembly in a lithium ion cell according to another embodiment of the present disclosure;

FIG. 8 is a partial schematic view of the coating of FIG. 7;

fig. 9 is a schematic view of an electric device according to an embodiment of the present disclosure.

In the figure:

1. a lithium ion cell;

100. a housing;

200. an electrode assembly; 210. a first pole piece; 220. a second pole piece; 230. an isolation film; 231. a release film substrate; 232. coating; 2321. a particulate micro-matrix; 2322. an adhesive;

1b, lithium ion battery cells;

200b, an electrode assembly; 210b, a first pole piece; 220b, a second pole piece; 230b, a barrier film; 231b, a separation film substrate; 232b, coating; 2321b, micro-matrix particles; 2322b, adhesive;

2. and (4) a power utilization device.

[ detailed description ] embodiments

In order to facilitate an understanding of the present application, the present application is described in more detail below with reference to the accompanying drawings and specific embodiments. It should be noted that when an element is referred to as being "fixed to"/"mounted to" another element, it can be directly on the other element or one or more intervening elements may be present therebetween. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may be present. The terms "vertical," "horizontal," "left," "right," "inner," "outer," and the like as used herein are for descriptive purposes only.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

In addition, the technical features mentioned in the different embodiments of the present application described below may be combined with each other as long as they do not conflict with each other.

In this specification, the term "mount" includes welding, screwing, clipping, adhering, etc. to fix or restrict a certain element or device to a specific position or place, the element or device may be fixed or movable in a limited range in the specific position or place, and the element or device may be dismounted or not dismounted after being fixed or restricted to the specific position or place, which is not limited in the embodiment of the present application.

Fig. 1 to fig. 3 respectively show a schematic view of a lithium ion battery cell 1, a cut-away schematic view of the lithium ion battery cell 1 along a line a-a after the lithium ion battery cell 1 is hidden in a casing, and a partial structural schematic view of an electrode assembly 200, where the lithium ion battery cell 1 includes a casing 100, an electrode assembly 200, and an electrolyte (not shown in the drawings). The electrode assembly 200 and the electrolyte are contained in the case 100, and the specific structures of the case 100 and the electrode assembly 200 will be described in turn.

Referring to fig. 1, the case 100 is a flat rectangular parallelepiped shape, and a receiving cavity (not shown) is formed inside the case 100 for receiving the electrode assembly 200 and the electrolyte. In this embodiment, the lithium ion battery cell 1 is a soft package battery cell, and the casing 100 is an aluminum-plastic film; it is understood that in other embodiments of the present application, the lithium ion battery cell 1 may also be a hard shell cell, and accordingly, the casing 100 is a metal shell.

Referring to the electrode assembly 200, specifically to fig. 2 and 3, the electrode assembly 200 includes a first pole piece 210, a second pole piece 220, and a separation film 230. The first pole piece 210 and the second pole piece 220 have opposite polarities and are arranged at intervals, one of the two pieces is an anode piece, and the other piece is a cathode piece. The separator 230 is disposed between the first pole piece 210 and the second pole piece 220 to separate the two. In this embodiment, the electrode assembly 200 is a wound structure; specifically, the first pole piece 210, one isolation film 230, the second pole piece 220 and the other isolation film 230 are stacked and wound into a cylindrical structure with an oval cross section so as to be accommodated in the accommodation cavity. It is understood that the electrode assembly 200 may also be a stacked structure in other embodiments of the present application, which is not limited herein.

The electrolyte is contained in the case 100, and the electrode assembly 200 is soaked in the electrolyte. The electrolyte is used for providing an environment for lithium ion conduction, so that lithium ions can be timely embedded into the first pole piece 210 or the second pole piece 220, thereby realizing the charge and discharge process of the lithium ion cell 1. When the temperature of the battery core is higher than a set threshold value, the electrolyte can generate acidic substances, and hydrogen ions exist in the electrolyte. The term "set threshold" used in this document refers to a temperature at which the temperature of the lithium ion battery cell rises to a value at which the electrolyte just generates the acidic substance, that is, the acidic substance is already generated in the electrolyte when the temperature is higher than the set threshold; the set threshold is the temperature of the lithium ion battery cell in an abnormal working state, and can be changed along with the specific specification and the use scene of the battery cell. For example, in some embodiments, the predetermined threshold may be 100 ℃; in other embodiments, the predetermined threshold may be 130 ℃; in still other embodiments, the predetermined threshold may be 150 ℃.

The first pole piece 210 and the second pole piece 220 are conventional structures in the prior art, and will not be described in detail herein; the structure of the isolation film 230 will be described in detail below. Referring to fig. 3 in conjunction with fig. 2, the isolation film 230 includes an isolation film substrate 231 and a coating layer 232 disposed on a surface of the isolation film substrate 231, and the isolation film 230 is adhered and fixed to the adjacent first pole piece 210 or the adjacent second pole piece 220 through the coating layer 232.

The release film substrate 231 is a flexible strip-like structure, which is a carrier coated with the coating layer 232. In this embodiment, the separation film substrate 231 includes organic fibers and an adhesive for bonding the organic fibers together, thereby forming the separation film substrate 231 having a plurality of micropores. Optionally, the organic fiber includes one or a mixture of two or more of polypropylene, glass fiber, carbon fiber, boron fiber, and polyamide. It is understood that in other embodiments of the present application, other suitable materials may be selected for the organic fibers. Optionally, the adhesive comprises acrylic glue; of course, in other embodiments of the present application, the adhesive may comprise other types of glues. The release film substrate 231 has a major surface defined by both its length and width, and both major surfaces thereof are oppositely disposed; with one major surface facing the first pole piece 210 and the other major surface facing the second pole piece 220.

The coating layer 232 is applied to a major surface of the release film substrate 231, which is configured to be capable of chemically reacting with an acidic substance. Thus, when the temperature of the lithium ion battery cell 1 is higher than the set threshold, the coating layer 232 may chemically react with the acidic substance generated from the electrolyte and be consumed, and the strength of the coating layer is reduced, so that the bonding strength between the coating layer and the pole piece (i.e., the first pole piece 210 or the second pole piece 220) outside the isolation film 230 is reduced accordingly. In this embodiment, the main surface of the side of the isolation film substrate 231 facing the first pole piece 210 and the main surface of the side facing the second pole piece 220 are both provided with a coating 232, and the isolation film 230 is adhered and fixed to the adjacent first pole piece 210 and the adjacent second pole piece 220 through the coatings 232; it is understood that in other embodiments of the present application, the separation film 230 may also be provided with the above-mentioned coating 232 only on the side of the separation film substrate 231 facing the first pole piece 210 or the side facing the second pole piece 220.

Specifically, referring to fig. 4 and fig. 5, which respectively show a schematic view of a part of the coating layer 232 and a schematic view of the coating layer 232 after being partially corroded, and referring to fig. 1 to fig. 3, the coating layer 232 includes micro-matrix particles 2321 and a bonding agent 2322. In this embodiment, the particulate micro-matrix 2321 is in the form of fine particles, and a plurality of particulate micro-matrix is laid on the surface of the isolation film substrate 231; the micro-matrix particles 2321 are configured to chemically react with the acidic substance, so that the acidic substance corrodes when the temperature of the lithium ion battery cell is higher than a set threshold value, and the strength of the lithium ion battery cell is reduced. Optionally, the micro-matrix particles 2321 include an alkaline substance. Further optionally, the micro-matrix particles 2321 include a carbonate. In this example, the micro-matrix particles 2321 include lithium carbonate.

When the temperature T of the lithium ion battery cell 1 is out of control and rises above a set threshold, the lithium ion battery cell 1 expands in the thickness direction thereof, and also contracts adaptively in the length direction and the width direction thereof, and generates a pressing force in the shearing direction to the laminated first pole piece 210, second pole piece 220, and separator 230, and the pressing force causes an interface separation force F between the separator 230 and the adjacent pole piece in the direction perpendicular to the separator 230. Meanwhile, the electrolyte generates an acidic substance, and the lithium carbonate reacts with the acidic substance to generate lithium salt, carbon dioxide and water; on one hand, the chemical reaction causes the strength of the micro-matrix particles 2321 to be reduced due to corrosion of the surface, and the contact area between the micro-matrix particles 2321 and the adhesive 2322 to be reduced, so that the interfacial peeling force f between the isolation film 230 and the pole piece (the first pole piece 210 or the second pole piece 220) is significantly reduced; on the other hand, the carbon dioxide causes the housing 100 to further expand in the thickness direction thereof and to further contract adaptively in the length direction and the width direction, thereby further increasing the above-mentioned separating force F. This trade off between the interfacial peel force F and interfacial separation force F described above promotes easier separation between the separator 230 and the adjacent pole piece; when the interfacial peeling force F is decreased to be smaller than the above-mentioned separation force F, the separation film 230 will be separated from the adjacent pole piece, and the contact area between the whole electrode assembly 200 and the electrolyte is increased, thereby facilitating the heat dissipation of the electrode assembly to the outside of the lithium ion battery cell 1 through the electrolyte and the case 100. It is to be understood that even though the micro matrix particles 2321 in the present embodiment include the above-described lithium carbonate, the present application is not limited thereto; in other embodiments of the present application, the micro-matrix particles 2321 may further include other carbonates such as sodium carbonate, sodium bicarbonate, calcium carbonate, or magnesium carbonate, or at least two of the above materials. In addition, the microparticle 2321 may also include a strongly basic substance such as lithium hydroxide and/or sodium hydroxide and/or potassium hydroxide. In some embodiments, the peel force f and the temperature T satisfy the following relationship: when T is more than or equal to 100 ℃ and less than or equal to 130 ℃, f is (62-0.47T) N/m.

Typically, the largest linear dimension of the micro-matrix particles 2321 is less than 5 micrometers (μm); in order to make the overall thickness of the separation film 230 thin to ensure that the energy density of the lithium ion battery cell 1 is as high as possible, the maximum linear dimension of the micro-matrix particles 2321 is preferably less than 2 μm. Alternatively, the shape of the micro-matrix particles 2321 is spherical; of course, the shape of the particulate micro-matrix 2321 may be varied in this application, and in other embodiments of the application, the particulate micro-matrix 2321 may have other shapes such as an ellipsoid, a plate, a cube, or a prism, but is not limited thereto.

The adhesive 2322 is disposed on the surface of the fine matrix particles 2321, so as to adhere the fine matrix particles 2321 to the release film substrate 231, so that the fine matrix particles 2321 and the adhesive 2322 together form the coating 232, and facilitate the adhesion and fixation of the coating 232 and the adjacent pole piece (i.e. the first pole piece or the second pole piece). Certainly, in order to avoid that the micro-matrix particles 2321 are completely coated by the adhesive 2322 and further the subsequent reaction of the micro-matrix particles 2321 with the acidic substance cannot be normally performed, the area of the micro-matrix particles 2321 coated by the adhesive 2322 accounts for 10% to 90% of the surface area of the micro-matrix particles 2321. In this embodiment, the adhesive 2322 is present in a granular form on the surface of the micro-matrix particles 2321, and a plurality of granular adhesives are attached to the surface of each adhesive 2322; preferably, the ratio of the maximum diameter of the adhesive 2322 to the maximum diameter of the particles 2321 is between 0.1 and 0.5, so as to ensure that the area of the particles 2321 covered by the adhesive 2322 falls within the above ratio range, and to prevent the particles 2321 from being completely immersed by the two adhesive particles disposed opposite to each other as shown. Optionally, the adhesive 2322 includes one or more of epoxy, polyester, polyurethane, polyester imide, and polyimide.

It is worth mentioning that the way of forming the coating layer 232 on the surface of the release film substrate 231 is various. For example, in some embodiments, the molding process of the coating 232 includes the steps of:

s11: the primer adhesive is applied to the surface of the release film substrate 231. Specifically, the adhesive may be applied to the surface of the release film substrate 231 by coating or spraying to form a primer adhesive. Optionally, the thickness of the primer adhesive is about 0.5 μm to minimize the overall thickness of the coating 232 while ensuring good adhesive strength.

S12: the micro-matrix particles are laid on the bottom layer adhesive. Specifically, a layer of micro-matrix particles can be sprayed on the surface of the bottom adhesive by a spraying device, and the micro-matrix particles 2321 at each part of the isolating membrane substrate 231 are ensured to be distributed relatively uniformly; the primer adhesive is used to bond and fix the particulate filter 2321 to the release film substrate 231. Since the size of the micro-matrix particles 2321 has a large influence on the overall thickness of the coating layer 232, the maximum linear dimension of the micro-matrix particles 2321 is preferably less than 2 μm, so that the thickness of the layer of the micro-matrix particles 2321 is about 2 μm. Of course, in other embodiments, a plurality of layers of micro-matrix particles may be sprayed on the bottom layer adhesive, which is not limited herein.

S13: a top layer of adhesive is applied to the particles of the micro-matrix. Specifically, the adhesive may be disposed on the surface of the micro matrix particles 2321 by coating or spraying to form a top layer adhesive. The top layer adhesive is used for bonding and fixing the micro-matrix particles 2321 and the adjacent pole pieces. Optionally, the thickness of the top layer adhesive is about 0.5 μm to minimize the overall thickness of the coating 232 while ensuring good adhesive strength.

For another example, in other embodiments of the present application, the process of forming the coating 232 includes the steps of:

s21: the micro-matrix particles 2321 are mixed with the binder 2322 to form a coating slurry. Specifically, the micro matrix particles 2321 and the binder 2322 are mixed in a set ratio and stirred to form a coating slurry. Since the adhesive 2322 is fluid when mixed, and adheres to the surface of the micro matrix particles 2321 during the mixing process, the amount of the adhesive 2322 used may be relatively small; in this embodiment, the mass percentage of the micro-matrix particles 2321 to the entire coating layer 232 is greater than 90%, and the mass percentage of the adhesive 2322 to the entire coating layer 232 is less than 10%. Thus, it is ensured that the binder 2322 is sufficiently used, and meanwhile, the binder 2322 is prevented from completely covering the surface of each micro-matrix particle 2321, which may cause interference to the subsequent reaction of the micro-matrix particles 2321 with the acidic substance in the electrolyte.

S22: the coating slurry is applied to the surface of the release film substrate 231.

Further, in order to make the distribution of the micro-matrix particles 2321 more uniform in the stirring process and reduce the phenomenon of local agglomeration, the coating 232 further comprises a dispersant; the dispersant serves to more uniformly distribute the micro-matrix particles 2321 in the binder 2322. Optionally, the dispersant comprises at least one of polyoxyethylene ether, sodium carboxymethylcellulose, and gelatin. The above-mentioned forming process includes the following steps:

s21': the micro-matrix particles 2321, the binder 2322, and a dispersant are mixed to form a coating slurry. Specifically, the micro matrix particles 2321, the binder 2322 and the dispersant are mixed in a set ratio and stirred to form a coating slurry. In this embodiment, the mass percentage of the micro-matrix particles 2321 to the entire coating layer 232 is greater than 90%, the mass percentage of the adhesive 2322 to the entire coating layer 232 is less than 10%, and the mass percentage of the dispersant to the entire coating layer 232 is less than 2%. Thus, it is ensured that the binder 2322 and the dispersant are sufficiently present, and at the same time, it is avoided that the binder 2322 completely covers the surface of each of the micro-matrix particles 2321, which may cause interference with the subsequent reaction of the micro-matrix particles 2321 with the acidic substance in the electrolyte.

S22: the coating slurry is applied to the surface of the release film substrate 231.

Fig. 6 shows a graph of interfacial peel force versus temperature for the respective separator and adjacent pole pieces in lithium ion cell 1 with coating 232 and conventional lithium ion cells; the coating 232 of the separation film 230 in the lithium ion cell 1 is prepared by the steps S11 to S13, and the coating of the separation film in the conventional lithium ion cell as a comparison is prepared by sequentially coating an adhesive, ceramic particles and a binder on the basis of a separation film substrate.

Next, taking the testing procedure of the lithium ion battery cell 1 with the coating 232 as an example, a method for testing the interfacial peeling force between the respective isolation film and the adjacent pole piece is described, and the testing method is as follows:

s31: preparing a finished lithium ion battery cell by using an isolating film with a coating 232;

s32: completely discharging the finished product battery cell;

s33: disassembling the battery core, cutting the unfolded pole piece and the adjacent isolating membrane into a to-be-stretched sample with the width of 20mm and the length of 10cm, wherein the to-be-stretched sample comprises three layers of a positive pole piece, an isolating membrane and a negative pole piece, and airing the sample in a fume hood for 12 hours;

s34: pre-stretching a sample to be stretched to peel an interface between the pole piece (the positive pole piece or the negative pole piece) and the isolating film 230, and forming a 180-degree peeling test direction;

s35: setting a high-temperature box of the high-speed rail tensile machine to be at a target temperature, and stabilizing the temperature in the high-temperature box within +/-2 ℃ of the target temperature for 5 min;

s36: soaking a sample to be stretched in a container containing electrolyte, and placing the container in the high-temperature box;

s37: when the temperature of the container reaches the target temperature +/-2 ℃ and is stabilized for 5min, taking out a sample, and starting to stretch the pole piece;

wherein the target temperature is 20 ℃, 30 ℃ and 40 ℃ … … 150 ℃ in sequence. The testing steps of the lithium ion battery cell in the prior art are basically the same, and are not described herein again.

As can be seen from fig. 6, when the test temperature is lower than 100 ℃, the interfacial peeling force f between the separation film 230 and the pole piece in the lithium ion cell 1 in the embodiment of the present application is 15N/m; after the test temperature is higher than 100 ℃, the coating 232 begins to react with acidic substances generated in the electrolyte, and the interfacial peeling force f begins to decrease and decrease remarkably, namely the set threshold value is close to 100 ℃; when the temperature reaches around 140 ℃, the interfacial peeling force f is reduced to nearly zero. The interfacial peeling force f' between the isolating membrane and the pole piece in the conventional lithium ion cell is 15N/m when the test temperature is lower than 100 ℃; after the test temperature is higher than 100 ℃, the interfacial peel force f' begins to decrease but to a lesser extent; even when the temperature reached about 150 ℃, the interfacial peeling force f' was reduced to nearly 8N/m. That is, compared with the conventional lithium ion cell, when the temperature of the lithium ion cell 1 provided in the embodiment of the present application is higher than 100 ℃, the interfacial peeling force between the inner isolation film 230 and the pole piece is significantly reduced, so as to improve the current situation that the peeling force between the isolation film and the pole piece of the conventional lithium ion cell is still higher after 100 ℃. It is noted that, on the basis of the above, the ratio between the micro base particles 3221 and the binder 3222, the material of the micro base particles, and the composition of the electrolyte solution may be adjusted by those skilled in the art, so that the set threshold is shifted toward a direction lower than 100 ℃ or a direction higher than 100 ℃.

In summary, the lithium ion battery cell 1 provided in the embodiment of the present application includes an electrode assembly 200, where the electrode assembly 200 includes a first pole piece 210, a second pole piece 220, and a separation film 230 disposed therebetween, and the separation film 230 is adhesively fixed to the adjacent first pole piece or second pole piece 220 through a coating 232. The coating 232 of the separator 230 is configured to react with the acidic substance; thus, when the temperature is higher than the preset threshold, the acidic material generated by the electrolyte may corrode the coating 232, so that the interfacial peeling force between the isolation film 230 and the adjacent first or second pole piece 210 or 220 may be reduced when the relative temperature is lower than the preset threshold, thereby facilitating opening of the adhesive interface between the isolation film 230 and the pole pieces, increasing the contact area between the electrode assembly 200 and the electrolyte, further increasing the heat dissipation area inside the lithium ion battery cell, and improving the stability of the lithium ion battery cell 1.

It should be understood that even though the above embodiments are configured to react with acidic substances to reduce the interfacial peel force between the separator 230 and the pole piece after a certain temperature threshold, the application is not limited thereto. For example, fig. 7 and fig. 8 respectively show a partial schematic diagram of an electrode assembly 200b and a partial schematic diagram of a coating of a separation film 230b in a lithium ion cell 1b provided in another embodiment of the present application, where the lithium ion cell 1b still includes a casing, the electrode assembly 200b and an electrolyte, the electrode assembly 200b includes a first pole piece 210b, a second pole piece 220b and a separation film 230b, and the lithium ion cell 1b is mainly different from the first lithium ion cell 1 in that: the coating in the separator 230b is not configured to react with the acidic substance, but is configured to reduce the separation force between the separator 230b and the pole piece outside thereof when the temperature is higher than a preset threshold. In this embodiment, coating 230b is specifically configured to decrease in strength at temperatures above a preset threshold, such that the separating force between separator 230b and the pole piece outside separator 230 b; thus, when the temperature of the lithium ion battery cell 1b is higher than the predetermined threshold, the strength of the coating layer 232b itself is reduced, and the bonding strength between the isolation film 230b and the external pole piece (i.e. the first pole piece 210 or the second pole piece 220) is reduced accordingly. Here, the "preset threshold" mentioned in this document refers to a temperature value at which the temperature of the li-ion battery cell is increased to just lower the separation force between the separation film 230b and the connected component, that is, at a temperature higher than the preset threshold, the separation force of the coating layer 232b is lower than that at a temperature lower than the preset threshold; the preset threshold is the temperature of the lithium ion battery cell in an abnormal working state, and can be changed along with the specific specification and the use scene of the battery cell.

Specifically, the coating layer 232b of the separation film 230b includes the micro-matrix particles 2321b and the adhesive 2322 b. Wherein, the shape and size of the micro-matrix particles 2321b are substantially the same as the micro-matrix particles 2321 in the above embodiment, and are configured to soften when the temperature is higher than a preset threshold. Optionally, the micro-matrix particles 2321b include a polymer. Further optionally, the micro-matrix particles 2321b are polyethylene, and the softening temperature of the polyethylene is 125 ℃ to 135 ℃, that is, the preset threshold is about 130 ℃. When the temperature of the lithium ion cell 1b is out of control and rises to be higher than the preset threshold value, the lithium ion cell 1b expands along the thickness direction thereof, and shrinks adaptively in the length direction and the width direction thereof, and generates a pressing force in the shearing direction to the stacked first pole piece 210b, second pole piece 220b, and separator 230b, and the pressing force causes an interface separation force F to be generated between the separator 230b and the adjacent pole piece. Meanwhile, the micro-matrix particles 2321 are softened, so that the interfacial peeling force f between the isolation film 230b and the pole piece is remarkably reduced, and the reduction of the interfacial peeling force f facilitates the separation between the isolation film 230b and the adjacent pole piece; when the interfacial peeling force F is decreased to be smaller than the above-mentioned separation force F, the separation film 230b will be separated from the adjacent pole piece, and the contact area between the whole electrode assembly 200b and the electrolyte is increased, thereby facilitating the heat dissipation of the electrode assembly to the outside of the lithium ion battery cell 1b via the electrolyte and the case. It is understood that even though the micro matrix particles 2321b in this embodiment include the above polyethylene, the present application is not limited thereto; in other embodiments of the present application, the micro-matrix particles 2321 may further include polypropylene, ethylene propylene rubber, ethylene propylene random polymer, polypropylene, polyethylene, polypropylene,

A polymer of 1-butene and 1-propylene, an ethylene butene propylene copolymer or a block copolymer polypropylene, or comprising at least two of the foregoing materials; by adjusting the material composition of the particles 2321b, the predetermined threshold value can be shifted in a direction lower than 130 ℃ or in a direction higher than 130 ℃. It is understood that even though the embodiment of the micro-matrix particles 2321b is a polymer material with a softening point, the micro-matrix particles 2321b may be a material with a melting point in other embodiments of the present application, and accordingly, the micro-matrix particles 2321b are configured to melt when the temperature is higher than a predetermined threshold.

The adhesive 2322b is used to adhere and fix the micro-matrix particles 2321b to the separation film substrate 231b, and the separation film 230b is also adhered and fixed to the adjacent first pole piece 210b or second pole piece 220b through the adhesive 2322 b. The manufacturing method of the isolation film 230b is substantially the same as that of the isolation film 230, and is not described herein again.

In the embodiment, the micro-matrix particles 2321b made of a material with a low softening or melting temperature is selected to separate the isolating membrane 230b from the pole piece in time, so that the contact area between the electrode assembly and the electrolyte is increased, the heat dissipation area inside the lithium ion battery cell is increased, and the stability of the lithium ion battery cell is improved. The material cost of this lithium ion cell 1b is lower than that of the previous embodiment. In addition, since the process of softening or melting the micro-matrix particles 2321b is a physical change, it is easier to control than the manner achieved by the chemical change in the previous embodiment because factors affecting the chemical reaction are more and more complicated.

Based on the same inventive concept, another embodiment of the present application further provides a separation film, which is the same as the separation film described in any of the above embodiments, and is adhesively fixed to an external component through a coating. When the isolating membrane is applied to a lithium ion battery, the isolating membrane is bonded and fixed with an adjacent pole piece through a coating; the current situation that the heat dissipation rate of an electrode assembly is low when the temperature of the current lithium ion battery cell is higher than a certain threshold value can be improved.

Based on the same inventive concept, another embodiment of the application also provides an electric device. Referring to fig. 9, a schematic diagram of an electric device 2 provided in an embodiment of the present application is shown, where the electric device 2 includes the lithium ion battery described in any of the embodiments. In this embodiment, the power consumption device 2 is a mobile phone; it is understood that, in other embodiments of the present application, the electric device 2 may also be a tablet computer, a drone or other electric devices that need to be driven by electricity.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit the same; within the context of the present application, where technical features in the above embodiments or in different embodiments can also be combined, the steps can be implemented in any order and there are many other variations of the different aspects of the present application as described above, which are not provided in detail for the sake of brevity; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present application.