WO2023051558A1

WO2023051558A1 - Battery and electronic apparatus

Info

Publication number: WO2023051558A1
Application number: PCT/CN2022/121903
Authority: WO
Inventors: 王烽; 李素丽; 李俊义
Original assignee: 珠海冠宇电池股份有限公司
Priority date: 2021-09-30
Filing date: 2022-09-27
Publication date: 2023-04-06
Also published as: CN113904044A

Abstract

The present application provides a battery and an electronic apparatus. Provided in a first aspect of the present application is a battery comprising a cell and a packaging body, the packaging body comprising a cell accommodating region sealing the cell, and a packaging region located at four sides of the cell accommodating region; the packaging region comprises a heat-sealing layer; a hydrophobic layer is provided at an end surface of the encapsulating region distant from the cell located on at least one side of the cell accommodating region, the hydrophobic layer covering an end surface of the heat-sealing layer distant from the cell; a water contact angle of the hydrophobic layer is greater than a water contact angle of the heat-sealing layer. In the present application, by means of providing a hydrophobic layer, the long-term ability of a battery to resist water vapor infiltration is increased, and there is no need to use expensive materials, thereby reducing the manufacturing cost of batteries.

Description

Batteries and Electronics

This application claims the priority of a Chinese patent application with application number 202111166833.1 and application title "Battery and Electronic Device" filed with the China Patent Office on September 30, 2021, the entire contents of which are incorporated herein by reference.

technical field

The application relates to a battery and an electronic device, and relates to the technical field of electrochemistry.

Background technique

With the development of science and technology, more and more electronic products have entered all aspects of people's lives, and the normal use of electronic products is inseparable from batteries. Batteries refer to devices that can convert chemical energy into electrical energy. Source, the performance of the battery is crucial to the use of electronic products.

A conventional battery includes a cell and a package of a sealed cell. During the use of the battery, the performance degradation of the cell caused by water vapor entering the cell is one of the important reasons for the failure of the electrical performance and the failure of the cell package; for the electrical performance , water vapor entering the cell will cause black spots, water stains, and even serious capacity loss and gas production; for packaging, when water vapor enters the cell, the violent thermal movement in the polymer layer of the package will cause polymer chain segments relaxation, and even generate free radicals to cause thermal and oxidative aging, resulting in degradation of sealing performance. Leakage; especially for energy storage and power products requiring long life, the cumulative infiltration of water vapor will reach a considerable level after long-term storage under working conditions (especially high temperature and high humidity conditions), which is enough Trigger the various reactions listed above.

At present, it is possible to prevent the entry of water vapor by improving the waterproof level of the package (for example, the waterproof level of the pack case of the power battery is IP67). However, this method has a high cost and a short effective waterproof time. In several years (such as the life requirement of 15 years of energy storage), water vapor will still seep into the battery core, and the waterproof effect is not ideal.

Contents of the invention

The present application provides a battery, which is used to improve the long-term waterproof performance of the packaging body and reduce the preparation cost.

The present application also provides an electronic device, which includes the above-mentioned battery.

The first aspect of the present application provides a battery, including a battery cell and a package body, the package body including a cell accommodating area that seals the battery cell and packaging areas located on four sides of the battery cell accommodating area ; The packaging area includes a heat-sealing layer;

A hydrophobic layer is provided on the end face of the packaging area located on at least one side of the cell accommodating area away from the cell, and the hydrophobic layer covers the end face of the heat-sealing layer away from the cell;

The water contact angle of the hydrophobic layer is greater than the water contact angle of the heat-sealing layer.

As in the above-mentioned battery, a hydrophobic layer is provided on the end faces of the packaging area located on the four sides of the cell accommodating area away from the cell;

The hydrophobic layer is disposed around the outer side of the packaging area.

As in the above-mentioned battery, the encapsulation area further includes a metal layer disposed on both surfaces of the heat-sealing layer, and a protective layer disposed on the surface of the metal layer away from the heat-sealing layer, and the hydrophobic layer covers the metal layer and the metal layer. The protective layer is away from at least part of the end face of the battery core.

As in the aforementioned battery, the heat-sealing layer includes a heat-sealing material, and the heat-sealing material is polypropylene and its composites;

The hydrophobic layer includes a hydrophobic material, and the molecular structure of the hydrophobic material includes one of an alkyl group, a hydrocarbon group, an alkynyl group, an aromatic group, a carbonyl group, an ester group, an ether group, a perfluoroalkyl group, and a polysiloxane group. or more.

As in the above battery, the distance between the end surface of the packaging area away from the battery core and the surface of the hydrophobic layer away from the packaging area is 10 nm-10 μm.

As in the aforementioned battery, the thickness of the heat-sealing layer is 40-200 μm.

As in the aforementioned battery, the protective layer includes a composite of polyamide and polyethylene terephthalate, and the thickness of the protective layer is 10-50 μm.

As in the aforementioned battery, the metal layer includes one or both of aluminum and steel, and the thickness of the metal layer is 20-50 μm.

As in the aforementioned battery, the thickness of the encapsulation region is 120-300 μm.

The second aspect of the present application provides an electronic device, including the battery provided in the first aspect of the present application.

In this application, by setting a hydrophobic layer, the adsorption constant of water molecules on the end face of the packaging area is reduced, thereby blocking the entry of water molecules and improving the long-term waterproof ability of the battery; in addition, compared to improving the waterproof level of the package or other waterproof The method, the cost of setting the hydrophobic layer is low, and helps to reduce the preparation cost of the battery.

The electronic device provided by the present application can effectively prolong the service life of the electronic device and reduce the manufacturing cost because it includes the above-mentioned battery.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description These are some embodiments of the present application. Those skilled in the art can also obtain other drawings based on these drawings without any creative effort.

FIG. 1 is a schematic structural view of a battery in the prior art;

Fig. 2 is a structural schematic diagram of a battery packaging area in the prior art;

Figure 3 is a schematic diagram of the passage of water molecules into the cell;

Fig. 4 is a schematic structural diagram of the packaging area of the battery provided by an embodiment of the present application;

Fig. 5 is an infrared analysis comparison diagram of the end face of the packaging area provided by the prior art and an embodiment of the present application;

Fig. 6 is a graph showing the test results of the water content inside the cell after storing the soft-pack lithium-ion battery provided by an embodiment of the present application at 60° C. and 95% RH for different periods of time.

Explanation of reference signs:

100-battery core;

200-package body;

2100-packaging area;

2101 - protective layer;

2102 - metal layer;

2103-heat seal layer;

2104 - hydrophobic layer;

2200- cell storage area;

300- positive pole ear;

400-Negative pole lug.

Detailed ways

In order to make the purpose, technical solutions and advantages of the application clearer, the technical solutions in the embodiments of the application will be clearly and completely described below in conjunction with the embodiments of the application. Obviously, the described embodiments are part of the implementation of the application. example, not all examples. Based on the embodiments in this application, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the scope of protection of this application.

FIG. 1 is a schematic structural view of a battery in the prior art. As shown in FIG. 1 , a conventional battery includes a battery cell 100, a package body 200 for sealing the battery cell, a positive pole tab 300 and a negative pole tab 400, wherein the battery cell 100 As the energy storage component of the battery, it is used for electrochemical reactions, including positive pole pieces, separators and negative pole pieces; the package body 200 is wrapped outside the battery cell 100 to play the role of sealing the battery cell 100. For general batteries, The package body 200 is formed by an aluminum-plastic film. A conventional aluminum-plastic film includes a heat-sealing layer, a metal layer, and a protective layer stacked in sequence. During the packaging process, two layers of aluminum-plastic films are covered on both surfaces of the battery cell 100. Or fold the aluminum-plastic film in half, so that the heat-sealing layer in the aluminum-plastic film is located on the side close to the battery cell 100, and the battery cell 100 is placed inside the opposite two-layer aluminum-plastic film, and then the side is packaged by means such as heat sealing , so that the opposite heat-sealing layer is fused together to form a package body 200; the tab is a metal conductor that leads the positive pole and the negative pole out of the battery core, and is divided into a positive pole tab 300 and a negative pole tab 400, and a positive pole tab 300 and One end of the negative tab 400 is connected to the battery cell, and the other end is located outside the package body 200 .

It can be understood that the package body 200 specifically includes a cell accommodating area 2200 that seals the cell and a packaging area 2100 located on the four sides of the cell accommodating area 2200, that is, the cell accommodating area 2200 is used to place The battery cell 100, the battery cell accommodation area 2200 has four sides, and each side is provided with a packaging area 2100, taking the packaging area 2100 on one side of the battery cell accommodation area 2200 as an example, as shown in Figure 2, Since the heat-sealing layer opposite to the aluminum-plastic film is melted into one after heat-sealing, the encapsulation area 2100 includes the heat-sealing layer 2103 fused into one, the metal layers 2102 arranged on both surfaces of the heat-sealing layer 2103, and the metal layer 2102 arranged on the The metal layer 2102 is away from the protective layer 2101 on the surface of the heat-sealing layer 2103. It can be understood that FIG. The structure is the same as in Figure 2.

Water vapor entering the cell leads to degradation of cell performance is one of the important reasons leading to electrical performance failure and cell packaging failure; in terms of electrical performance, water vapor entering the cell will cause black spots, water stains, and even serious capacity loss and Gas generation; for packaging, when water vapor enters the cell, the violent thermal movement in the polymer layer of the package will cause the polymer chain to relax, and even generate free radicals to cause thermal and oxygen aging, resulting in degradation of sealing performance. At the same time, water vapor entering The gas production after the battery will increase the internal pressure of the battery, which will further cause the creep damage effect on the degraded package, and accelerate the gas production and liquid leakage.

After repeated thinking and verification, the applicant found that the main channel for water molecules to enter the package body 200 is the heat-seal layer 2103 where the package area is far away from the exposed end face of the battery cell. Figure 3 is a schematic diagram of the channel for water molecules to enter the battery cell, as shown in Figure 3 It shows that after the aluminum-plastic film is heat-pressed and sealed, the excess aluminum-plastic film for edge sealing is usually cut off as required to obtain a relatively neat packaging area on the outer edge. Air contact, here is the main channel for water molecules in the air to enter the cell. The heat-sealing layer 2103 is generally a polymer hydrophobic material, but microscopic water molecules can still penetrate into the package 200 through molecular thermal movement, that is to say, the air The water molecules in the heat-sealing layer 2103 can be adsorbed on the exposed surface of the heat-sealing layer 2103 in FIG.

According to the formula:

Among them, m is the mass of water infiltrated into the battery from the outside world; J is the water vapor diffusion flux,

Fick's first diffusion law; D is the diffusion coefficient of water molecules, Cs is the concentration of water vapor adsorbed on the outer surface of the aluminum-plastic film exposed to the external environment; L is the width of the packaging area; S is the heat-sealing layer exposed to the outside area; t is time. According to the formula, it can be seen that by reducing the adsorption constant of water molecules on the surface of the heat-sealing layer, the adsorption capacity of water molecules on the heat-sealing layer is reduced, and the Cs value is reduced, thereby reducing the mass m of water infiltrating into the battery from the outside.

Based on the above analysis, the present application provides a battery, including a battery cell and a package formed by an aluminum-plastic film, the package includes a cell accommodating area that seals the battery cell and a battery located in the cell accommodating area. The encapsulation area on the four sides; the encapsulation area includes a heat-sealing layer;

This application provides a battery. On the basis of the existing battery, a hydrophobic layer with a hydrophobic effect better than the heat-sealing layer is provided on at least part of the end surface of the packaging area away from the battery core, which effectively reduces the adsorption capacity of water molecules on the end surface of the packaging area. , preventing the entry of water molecules in the air and prolonging the service life of the battery. Specifically, among the four sides of the cell accommodating area 2200, at least one side of the packaging area on the end face far away from the cell is provided with Hydrophobic layer, FIG. 4 is a schematic structural diagram of the packaging area of the battery provided by an embodiment of the present application. As shown in FIG. 4 , a hydrophobic layer 2104 is provided on the end face of the packaging area 2100 away from the battery cell 100, and the hydrophobic layer 2104 covers the heat-sealing layer 2103 is away from the end face of the electric core, that is, the heat sealing layer 2103 of the packaging area 2100 away from the end face of the electric core 100 is not exposed to the air, but the hydrophobic layer 2104 is exposed to the air, and the water contact angle of the hydrophobic layer 2104 is larger than that of the heat sealing layer The water contact angle of 2103, those skilled in the art know, the larger the water contact angle, the better the hydrophobic performance, that is to say, the hydrophobic performance of the hydrophobic layer 2104 is better than that of the heat-sealing layer 2103, compared with the heat-sealing layer 2103, the hydrophobic layer 2104 can effectively reduce the adsorption capacity of water molecules on the end surface of the packaging area, block the entry of water molecules, and improve the long-term waterproof performance of the package. In this application, by setting a hydrophobic layer, the adsorption constant of water molecules on the end face of the packaging area is greatly reduced, thereby blocking the entry of water molecules and improving the long-term waterproof ability of the battery; in addition, compared to improving the waterproof level of the package Or other waterproof methods, the cost of setting the hydrophobic layer is low, which helps to reduce the cost of battery preparation.

In a specific example, a heat-sealing layer 2103 is provided on the end surface of the packaging area located on at least three sides of the battery cell accommodation area away from the battery core, that is, in a conventional battery, there are at least three sides The heat-sealing layer 2103 is exposed to the air. Therefore, in order to further improve the ability of the battery to prevent water vapor penetration, the end surface of the packaging area located on at least three sides of the battery accommodating area away from the battery is provided with hydrophobic Layer 2104, so that the package body 200 does not have the heat-sealing layer 2103 exposed to the air.

It can be understood that when the packaging area includes four heat-sealing layers 2103 exposed to the air, the end faces of the four heat-sealing layers 2103 away from the battery are provided with a hydrophobic layer 2104, that is, the hydrophobic layer 2104 forms a ring structure, surrounding It is arranged on the outer side of the packaging area 2100, by increasing the installation area of the hydrophobic layer and reducing the area of the heat-sealing layer exposed to the air, it helps to further improve the waterproof effect of the package.

In a specific example, the packaging area further includes a metal layer disposed on both surfaces of the heat-sealing layer, and a protective layer disposed on the surface of the metal layer away from the heat-sealing layer, and the hydrophobic layer covers the metal layer. layer and protective layer away from at least part of the end face of the electric core; that is to say, increase the coverage area of the hydrophobic layer 2104 on the end face of the packaging area 2100 located on one side of the electric core accommodating area 2200 away from the electric core 100, from covering the heat seal The layer 2103 extends to cover part of the metal layer 2102 and the protective layer 2101, which helps to further improve the waterproof effect of the package.

In a specific example, the heat-sealing layer includes heat-sealing materials, conventional heat-sealing materials are polypropylene (PP) and its composites, and its main function is to bond and prevent the electrolyte from directly contacting the metal layer. Based on the above-mentioned heat-sealing materials, In another specific example, the hydrophobic layer includes a hydrophobic material, and the molecular structure of the hydrophobic material includes an alkyl group, a hydrocarbon group, an alkynyl group, an aromatic group, a carbonyl group, an ester group, an ether group, a perfluoroalkyl group, and polysiloxane One or more of the substrates, the hydrophobic material can not only attract each other with the heat-sealing material, so that the hydrophobic layer is adsorbed on the surface of the heat-sealing layer, but also has strong hydrophobicity, so that water molecules cannot be adsorbed on the surface of the hydrophobic layer, thereby realizing water vapor barrier Effect.

In a specific embodiment, the hydrophobic material may be common materials such as lubricating oil and engine oil.

This application uses infrared to analyze the components of the end face of the packaging area. Figure 5 is an infrared analysis comparison diagram of the end face of the packaging area provided by the prior art and an embodiment of the application, wherein (a) is the end face of the packaging area provided by the prior art. Infrared analysis diagram, (b) is an infrared analysis comparison diagram of the end face of the packaging area provided by an embodiment of the present application, as shown in Figure 5, due to the very small amount of hydrophobic material, the main body of the infrared spectrum of (b) is the same as that of (a) normal The spectra of the samples are consistent, both being the infrared spectrum of polypropylene, but an obvious carbonyl peak is detected in the infrared spectrum of the aluminum-plastic film provided with a hydrophobic layer, indicating that the hydrophobic layer including carbonyl helps to improve the waterproof performance of the package.

In a specific example, continuing to refer to FIG. 4 , the distance H ₁ between the end surface of the packaging area away from the cell and the surface of the hydrophobic layer away from the packaging area is 10 nm-10 μm.

The thicknesses of the heat-sealing layer, metal layer and protective layer in the packaging area are set according to the thickness of the aluminum-plastic film used and the hot-pressing process. Specifically, the thickness _H of the heat-sealing layer is 40-200 μm. It should be noted that this The heat-seal layer at is the heat-seal layer located in the encapsulation area, which refers to the heat-seal layer that is arranged opposite to each other and then melted into one body after being hot-pressed.

The metal layer is arranged on the two functional surfaces of the heat-sealing layer, the metal layer includes one or both of aluminum and steel, and the thickness of the metal layer is 20-50 μm.

The protective layer is arranged on the surface of the metal layer away from the heat-sealing layer, which comprises a compound of polyamide and polyethylene terephthalate, and the thickness of the protective layer is 10-50 μm.

The total thickness of the packaging area is 120-300 μm, that is, the total thickness _H3 of the heat-sealing layer, two metal layers and two protective layers located in the packaging area is 120-300 μm.

In summary, this application has introduced the packaging area in detail. The aluminum-plastic film and the battery outside the packaging area can be processed according to conventional technical means in the field. For example, the aluminum-plastic film outside the packaging area is located on both surfaces of the battery cell. The aluminum-plastic film on the top includes a heat-sealing layer, a metal layer and a protective layer in sequence from the side close to the battery core to the side away from the battery core, and its materials are the same as before.

The cell includes a positive electrode sheet, a separator, and a negative electrode sheet that are sequentially stacked or wound. In the specific implementation process, the size of the cell accommodating area can be adjusted according to the size of the cell.

Further, the positive electrode sheet includes a positive electrode current collector and a positive electrode active layer arranged on at least one functional surface of the positive electrode current collector. The positive electrode current collector is generally an aluminum foil, and the positive electrode active layer includes a positive electrode active material, a conductive agent and a binder. The positive electrode active material includes One or more of LCO, LMO, LFP, NCM, NCA.

The negative electrode sheet includes a negative electrode current collector and a negative electrode active layer arranged on at least one functional surface of the negative electrode current collector. The negative electrode current collector is generally copper foil. It includes one or more of graphite, lithium carbonate, silicon oxide compound and silicon carbon compound, and the dispersant is selected from sodium carboxymethyl cellulose.

In a specific example, the types of conductive agent and binder in the positive active layer and the negative active layer are the same, specifically, the conductive agent is selected from conductive carbon black, acetylene black, Ketjen black, conductive graphite, conductive carbon fiber, carbon nano One or more of tubes, metal powder, and carbon fibers; the binder is selected from one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), and lithium polyacrylate (PAALi).

In a specific example, the battery further includes a positive pole tab 300 and a negative pole tab 400 , one end of the positive pole tab 300 and the negative pole tab 400 are connected to the battery cell 100 , and the other end is located outside the packaging body 200 . Specifically, in the process of processing, in order to facilitate the protruding of the tab, the cell will be placed in the cell accommodation area first, so that the other end of the tab is located outside the aluminum-plastic film, and then packaged, so as to ensure the package body The surrounding sealing structure can realize that the other end of the tab protrudes from the package body.

The preparation process of the battery in the embodiment of the present application can be carried out according to conventional technical means, for example, the positive pole piece and the negative pole piece are prepared, and the battery core is prepared according to the stacking process or the winding process, and then the positive pole tab and the One end of the negative tab is connected to the cell, and then the aluminum-plastic film is wrapped around the cell and the other end of the positive tab and the negative tab are located outside the aluminum-plastic film. The heat-sealing layer is fused together to obtain the battery of this embodiment.

In order to verify the waterproof performance of the battery provided by the application, the soft-pack lithium-ion battery is taken as an example to test, specifically, the conventional soft-pack lithium-ion battery (that is, not including the hydrophobic layer) and the soft-pack lithium-ion battery provided by the application ( Including the hydrophobic layer, the hydrophobic layer includes engine oil, apply the engine oil on the end face of the heat-seal layer away from the battery cell, lithium-ion batteries have no heat-seal layer exposed to the air) 30 pieces each, store at 60°C, 95%RH, Take 10 samples every 10 days, and use the Karl Fischer method to test the water content inside the cell (Note: The difference between the two groups of cells in the experiment is only whether there is a waterproof layer, and the materials, systems and other processes are consistent. for one-way experiments).

Fig. 6 is a graph showing the test results of the water content inside the cell after storing the soft-pack lithium-ion battery provided by an embodiment of the application at 60°C and 95% RH for different periods of time. As shown in Fig. 6, the initial water content in the cell is about 1.7ppm, with the prolongation of storage time, the water content of the normal battery cell into the battery cell increases approximately linearly, while the soft pack lithium-ion battery provided by this application is stored for 30 days under high temperature and high humidity conditions, the water content in the battery cell The water content is almost the same as the initial water content. After 30 days, almost no water seeps into the inside of the cell. A hydrophobic layer is provided on the surface of the packaging area to help block water vapor penetration and improve the long-term storage effect of the soft-pack lithium-ion battery.

The second aspect of the present application provides an electronic device, and the electronic device includes the battery provided in the first aspect of the present application. The application does not limit the types of electronic devices, which specifically include but are not limited to mobile phones, desktop computers, notebook computers, power vehicles, electric bicycles, digital cameras, smart home appliances, and the like.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit it; although the application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: It is still possible to modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the technical solutions of the various embodiments of the present application. scope.

Claims

A battery, including an electric core and a packaging body, the packaging body includes a cell accommodating area that seals the electric core and packaging areas located on four sides of the electric core accommodating area; the packaging zone includes a heat seal layer;

A hydrophobic layer is provided on the end face of the packaging area located on at least one side of the cell accommodating area away from the cell, and the hydrophobic layer covers the end face of the heat-sealing layer away from the cell;

The water contact angle of the hydrophobic layer is greater than the water contact angle of the heat-sealing layer.
The battery according to claim 1, wherein a hydrophobic layer is provided on the end surface of the packaging area located on at least three sides of the cell accommodating area away from the cell.
The battery according to claim 1 or 2, wherein the encapsulation area further comprises a metal layer disposed on both surfaces of the heat-sealing layer, and a protective layer disposed on the surface of the metal layer away from the heat-sealing layer, so The hydrophobic layer covers at least part of the end faces of the metal layer and the protective layer away from the battery core.
The battery according to any one of claims 1-3, wherein the heat-sealing layer comprises a heat-sealing material, and the heat-sealing material is polypropylene and its composites;

The hydrophobic layer includes a hydrophobic material, and the molecular structure of the hydrophobic material includes one of an alkyl group, a hydrocarbon group, an alkynyl group, an aromatic group, a carbonyl group, an ester group, an ether group, a perfluoroalkyl group, and a polysiloxane group. or more.
The battery according to any one of claims 1-4, wherein the distance between the end surface of the packaging area away from the cell and the surface of the hydrophobic layer away from the packaging area is 10 nm-10 μm.
The battery according to any one of claims 1-4, wherein the thickness of the heat-sealing layer is 40-200 μm.
The battery according to claim 3, wherein the protective layer comprises a composite of polyamide and polyethylene terephthalate, and the thickness of the protective layer is 10-50 μm.
The battery according to claim 3, wherein the metal layer comprises one or both of aluminum and steel, and the thickness of the metal layer is 20-50 μm.
The battery according to any one of claims 1-8, wherein the packaging region has a thickness of 120-300 μm.
An electronic device, wherein the electronic device comprises the battery according to any one of claims 1-9.