CN115832614A

CN115832614A - Diaphragm, secondary battery and power utilization device

Info

Publication number: CN115832614A
Application number: CN202210736251.0A
Authority: CN
Inventors: 袁海峰; 黄奶兴; 许文竹
Original assignee: Contemporary Amperex Technology Co Ltd
Current assignee: Contemporary Amperex Technology Co Ltd
Priority date: 2022-06-27
Filing date: 2022-06-27
Publication date: 2023-03-21

Abstract

The present invention relates to a separator, and a secondary battery and an electric device formed by the separator. A separator comprising a base film; the base film includes a first region, a second region, and a third region in a width direction; the first region surface of base film is equipped with first adhesive linkage and the inorganic protective layer that piles up in proper order, and the second region surface is equipped with the second adhesive linkage, and the third region is equipped with third adhesive linkage and the conducting polymer layer that piles up in proper order. The present application addresses the different problems that exist in different regions of the diaphragm.

Description

Diaphragm, secondary battery and power utilization device

Technical Field

The invention relates to the field of batteries, and relates to a diaphragm, a secondary battery formed by the diaphragm, and an electric device.

Background

The lithium ion battery has the characteristics of large energy, high working voltage, low self-discharge rate, small volume, light weight and the like, and is widely applied to various fields of electric energy storage, portable electronic equipment, electric automobiles and the like. An isolating membrane in a lithium ion battery is generally arranged between a positive pole piece and a negative pole piece, and plays a role in blocking an electronic channel between a positive pole and a negative pole and conducting lithium ions.

In the prior art, the performance of the isolation film is improved by modifying or arranging a coating on the surface of the isolation film, and the modification of each region on the surface is basically the same, so that although a certain performance of the isolation film is improved to a certain extent, the problems existing in different regions of the isolation film are not completely the same in the working process of the battery, which leads to the problem that the problems existing in each region cannot be solved at the same time.

The invention is therefore proposed.

Disclosure of Invention

The invention mainly aims to provide a diaphragm, a secondary battery formed by the diaphragm and an electric device, which simultaneously solve different problems existing in different areas of the diaphragm and provide a powerful foundation for improving the comprehensive performance of the battery, particularly the aspects of improving the exhaust, improving the safety and liquid retention functions, improving the lithium precipitation, improving the needling performance and the like.

In order to achieve the above object, the present invention provides the following technical solutions.

A first aspect of the present invention provides a separator including a base film;

the base film includes a first region, a second region, and a third region in a width direction;

the first region surface is equipped with first adhesive linkage and the inorganic protective layer that piles up in proper order, the second region surface is equipped with the second adhesive linkage, the third region is equipped with third adhesive linkage and the conducting polymer layer that piles up in proper order.

The present invention divides the base film into three distinct regions that typically present distinct major problems in battery operation. For example, the first region near the head end is located inside the battery cell, and mainly has the problems of poor exhaust, poor liquid retention, easy lithium separation and piercing, the second region in the middle mainly has the problem of poor bonding performance, and the third region at the tail end mainly has the problems of large distance to the pole piece, poor conductivity and the like. The invention carries out differentiation modification aiming at different technical problems existing in the three areas so as to solve all the problems. For example, the targeted addition of an inorganic protective layer in the first region can make harder inorganic substances preferentially contact the outside, thereby reducing the risk of puncture, and on the other hand can improve the oxidation resistance. The adhesive is added in the second area in a targeted manner, so that the adhesive force between the second area and the anode and the cathode can be improved, and the influence of redundant layers on the conductivity can be avoided. The conductive polymer layer is added in the third region in a targeted manner, so that the conductivity of the outside of the battery cell can be improved, and the problems of short circuit and the like are avoided.

Therefore, the invention solves different problems of different areas of the diaphragm in the working process of the battery core through regionalization distinguishing modification.

In some embodiments, the membrane area fraction of the first region is from 2% to 5%, the membrane area fraction of the second region is from 90% to 96%, and the membrane area fraction of the third region is from 2% to 5%.

The areas of the three regions are reasonably divided to optimize the comprehensive performance of the diaphragm, and the division can be adaptively adjusted within the range. In addition, in order to reduce the process difficulty, the first region and the third region may have the same area.

In some embodiments, the separator has a porosity of 50% to 70% in the first region, a porosity of 20% to 60% in the second region, and a porosity of 20% to 60% in the third region.

As mentioned above, the first region is required to have high air permeability, so the porosity of the first region is required to be high, and can be adjusted at will from 50% to 70%, for example, 50%, 55%, 60%, 65%, 70%, etc., by controlling the selection of the base film and the modifier, and the shape distribution of the adhesive and the inorganic protective layer. Similarly, the porosity of the second and third regions is also related to the material and shape distribution of the layers.

In some embodiments, the first binder contains a cellulose-based material, and the weight ratio of the cellulose-based material in the first binder is preferably 20wt% or more.

Cellulose-based materials may serve to increase porosity, enhance liquid absorption, and resist oxidation.

In some embodiments, the first binder is a combination of an organic binder and a cellulose-based material.

In some embodiments, the inorganic protective layer employs at least one of silicon oxide, aluminum oxide, zirconium oxide, magnesium oxide, titanium oxide, or calcium oxide. Both of them have high hardness, can reduce the shrinkage of the diaphragm at high temperature and have good oxidation resistance.

In some embodiments, the second adhesive and the third adhesive are each independently one or more of polyvinylidene fluoride, styrene-butadiene rubber, styrene-acrylic latex, polytetrafluoroethylene, polyacrylonitrile, polyvinylpyrrolidone, polyurethane, polyvinyl alcohol, and polyimide, preferably polyvinylidene fluoride.

The second adhesive is preferably a material with strong adhesive force, so that the large-area second area can be tightly attached to the positive electrode and the negative electrode.

In some embodiments, the conductive polymer layer has a conductivity of 10 ² ～10 ⁴ S/cm, preferably one or a mixture of polyacetylene, polypyrrole, polyphenylacetylene and polyaniline.

The conductive polymer layer has high conductivity, good coating performance and easy realization of the process.

In some embodiments, the inorganic protective layer is silica, and the first adhesive is cellulose and styrene-butadiene rubber.

The two materials are stacked in the first area of the diaphragm to achieve a synergistic effect, so that the liquid absorption capacity of the diaphragm is remarkably improved, and meanwhile, the safety performance of the battery cell is also remarkably enhanced by the styrene butadiene rubber and the silica material.

In some embodiments, the conductive polymer layer is polyaniline, and the third adhesive is styrene-butadiene rubber

The two materials stacked in the first area of the diaphragm can play a synergistic effect, so that the bonding performance of the diaphragm and the pole piece is obviously improved.

In some embodiments, the separator is a composite of one or both of PE, PP materials.

The above materials are listed, and in practice, the present invention is not limited to the type of the base film, and a polymer material having good insulation properties, flexibility and air permeability is generally used.

In some embodiments, the first adhesive is disposed in dots on the base film.

The first adhesive distributed in a dot shape can improve the roughness of the diaphragm in the area 1, improve the exhaust capacity in the diaphragm and better improve the liquid retention performance of the battery cell. The interval of the point distribution can be adaptively adjusted according to actual requirements.

In some embodiments, the thickness of the separator in the first region, the second region, and the third region is 12 to 20 μm, 7 to 15 μm, and 10 to 18 μm, respectively.

In order to ensure the uniformity and stability of the battery performance, the three regions of the diaphragm should not differ too much, and should be completely adapted to the technical problem to be solved. For this reason, the film thickness of each region can be adjusted within the above range.

A second aspect of the present invention provides a secondary battery including the above-described separator.

A third aspect of the invention provides an electric device including the secondary battery described above.

In summary, compared with the prior art, the invention achieves the following technical effects:

(1) Three different areas of the base film are modified in a differentiated mode, so that the problems of poor air exhaust, easiness in puncture, lithium separation, short circuit, insufficient binding power and the like existing in the use process of the diaphragm are solved;

(2) The adhesive is coated on the first area of the base film by a dot coating method, so that the air exhaust property and the liquid retention capacity can be improved;

(3) The combination of the materials of the two decorative layers of the first area and the third area is optimized, and the comprehensive performance of the diaphragm is further improved.

The foregoing description is only an overview of the technical solutions of the present application, and the present application can be implemented according to the content of the description in order to make the technical means of the present application more clearly understood, and the following detailed description of the present application is given in order to make the above and other objects, features, and advantages of the present application more clearly understandable.

Drawings

Various additional advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the application. Moreover, like reference numerals are used to refer to like elements throughout. In the drawings:

FIG. 1 is a schematic structural diagram of a barrier film according to the present invention;

FIG. 2 is a cross-sectional view of a first region of a separator provided by the present invention;

FIG. 3 is a cross-sectional view of a third region of a separator provided by the present invention;

fig. 4 is a schematic view of a secondary battery according to an embodiment of the present application;

fig. 5 is an exploded view of the secondary battery according to an embodiment of the present application shown in fig. 4;

FIG. 6 is a schematic view of a battery module according to an embodiment of the present application;

fig. 7 is a schematic view of a battery pack according to an embodiment of the present application;

fig. 8 is an exploded view of the battery pack of an embodiment of the present application shown in fig. 7;

fig. 9 is a schematic diagram of an electric device in which a secondary battery according to an embodiment of the present application is used as a power source.

Detailed Description

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The following examples are merely used to more clearly illustrate the technical solutions of the present application, and therefore are only examples, and the protection scope of the present application is not limited thereby.

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 herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application; the terms "including" and "having," and any variations thereof, in the description and claims of this application and the description of the above figures are intended to cover non-exclusive inclusions.

In the description of the embodiments of the present application, the technical terms "first", "second", and the like are used only for distinguishing different objects, and are not to be construed as indicating or implying relative importance or implicitly indicating the number, specific order, or primary-secondary relationship of the technical features indicated. In the description of the embodiments of the present application, "a plurality" means two or more unless specifically defined otherwise.

Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. It is explicitly and implicitly understood by one skilled in the art that the embodiments described herein can be combined with other embodiments.

In the description of the embodiments of the present application, the term "and/or" is an association relationship describing an associated object, and means that three relationships may exist, for example, a and/or B, and may mean: a exists alone, A and B exist simultaneously, and B exists alone. In addition, the character "/" herein generally indicates that the former and latter related objects are in an "or" relationship.

In the description of the embodiments of the present application, the term "plurality" refers to two or more (including two), and similarly, "plural sets" refers to two or more (including two), and "plural pieces" refers to two or more (including two).

In the description of the embodiments of the present application, unless otherwise explicitly stated or limited, the terms "mounted," "connected," "fixed," and the like are used in a broad sense, and for example, may be fixedly connected, detachably connected, or integrated; mechanical connection or electrical connection is also possible; the two components can be directly connected or indirectly connected through an intermediate medium, and the two components can be communicated with each other or mutually interacted. The specific meanings of the above terms in the embodiments of the present application can be understood by those of ordinary skill in the art according to specific situations.

As discussed in the background, existing membrane modifications do not address the different problems that exist in different areas.

To this end, the present invention provides a separator as shown in fig. 1, which includes a base film 1; the base film includes a first region 11, a second region 12, and a third region 13 in a width direction.

The surface of the first region 11 is provided with a first adhesive layer 111 and an inorganic protective layer 112, which are sequentially stacked, the surface of the second region 12 is provided with a second adhesive layer 121, and the third region 13 is provided with a third adhesive layer 131 and a conductive polymer layer 132, which are sequentially stacked.

Wherein the modification of the first region 11 reduces the risk of puncture on the one hand and improves the resistance to oxidation on the other hand; the second region 12 focuses on improving adhesion; the third region 13 improves the conductivity to avoid short circuit problems.

To further enhance the overall performance of the separator in use, the present invention also improves the structure and materials, as exemplified below.

In some embodiments, the membrane area ratio of the first region is 2% to 5%, the membrane area ratio of the second region is 90% to 96%, and the membrane area ratio of the third region is 2% to 5%.

Cellulose-based materials may serve to increase porosity and oxidation resistance.

In some embodiments, the conductive polymer layer is polyaniline, and the third adhesive is styrene-butadiene rubber.

In some embodiments, the first adhesive is distributed in dots on the base film.

Hereinafter, a secondary battery, a battery module, a battery pack, and an electric device to which the separator of the present invention is applicable will be described with reference to the drawings as appropriate.

In one embodiment of the present application, a secondary battery is provided.

In general, a secondary battery includes a positive electrode tab, a negative electrode tab, an electrolyte, and a separator. In the process of charging and discharging the battery, active ions are embedded and separated back and forth between the positive pole piece and the negative pole piece. The electrolyte plays a role in conducting ions between the positive pole piece and the negative pole piece. The isolating membrane is arranged between the positive pole piece and the negative pole piece, mainly plays a role in preventing the short circuit of the positive pole and the negative pole, and can enable ions to pass through.

[ Positive electrode sheet ]

The positive pole piece comprises a positive pole current collector and a positive pole film layer arranged on at least one surface of the positive pole current collector, wherein the positive pole film layer comprises positive pole active materials listed below.

As an example, the positive electrode current collector has two surfaces opposite in its own thickness direction, and the positive electrode film layer is disposed on either or both of the two surfaces opposite to the positive electrode current collector.

In some embodiments, the positive electrode current collector may employ a metal foil or a composite current collector. For example, as the metal foil, aluminum foil may be used. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel alloy, titanium alloy, silver alloy, etc.) on a base material of a polymer material (e.g., a base material of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

In some embodiments, when the secondary battery is a lithium ion battery, the positive active material may be a positive active material for a lithium ion battery, which is well known in the art. As an example, the positive electrode active material may include at least one of the following materials: olivine structured lithium-containing phosphates, lithium transition metal oxides and their respective modified compounds. However, the present application is not limited to these materials, and other conventional materials that can be used as a positive electrode active material of a battery may be used. These positive electrode active materials may be used alone or in combination of two or more. Among them, examples of the lithium transition metal oxide may include, but are not limited to, lithium cobalt oxide (e.g., liCoO) ₂ ) Lithium nickel oxide (e.g., liNiO) ₂ ) Lithium manganese oxide (e.g., liMnO) ₂ 、 LiMn ₂ O ₄ ) Lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (e.g., liNi) _1/3 Co _1/ ₃ Mn _1/3 O ₂ (may also be abbreviated as NCM) ₃₃₃ )、 LiNi _0.5 Co _0.2 Mn _0.3 O ₂ (may also be abbreviated as NCM) ₅₂₃ )、LiNi _0.5 Co _0.25 Mn _0.25 O ₂ (may also be abbreviated as NCM) ₂₁₁ )、LiNi _0.6 Co _0.2 Mn _0.2 O ₂ (may also be abbreviated as NCM) ₆₂₂ )、 LiNi _0.8 Co _0.1 Mn _0.1 O ₂ (may also be abbreviated as NCM) ₈₁₁ ) Lithium nickel cobalt aluminum oxides (e.g., liNi) _0.85 Co _0.15 Al _0.05 O ₂ ) And modified compounds thereof, and the like. Examples of olivine structured lithium-containing phosphates may include, but are not limited to, lithium iron phosphate (e.g., liFePO) ₄ (also referred to as LFP for short)), a composite material of lithium iron phosphate and carbon, and lithium manganese phosphate (e.g., liMnPO) ₄ ) At least one of a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon.

In some embodiments, when the secondary battery is a sodium ion battery, the positive active material may be a positive active material for a sodium ion battery, which is well known in the art. As an example, only one kind of the positive electrode active material may be used alone, or two or more kinds may be combined. Wherein the positive electrode active material is selected from sodium-iron composite oxide (NaFeO) ₂ ) Sodium cobalt composite oxide (NaCoO) ₂ ) Sodium chromium composite oxide (NaCrO) ₂ ) Sodium manganese oxide (NaMnO) ₂ ) Sodium nickel composite oxide (NaNiO) ₂ ) Sodium nickel titanium composite oxide (NaNi) _1/2 Ti _1/2 O ₂ ) Sodium nickel manganese composite oxide (NaNi) _1/2 Mn _1/2 O ₂ ) Sodium-iron-manganese composite oxide (Na) _2/3 Fe _1/3 Mn _2/3 O ₂ ) Sodium nickel cobalt manganese complex oxide (NaNi) _1/3 Co _1/3 Mn _1/3 O ₂ ) Sodium iron phosphate compound (NaFePO) ₄ ) Sodium manganese phosphate compound (NaMn) _P O ₄ ) Sodium cobalt phosphate compound (NaCoPO) ₄ ) A prussian blue-based material, a polyanion material (phosphate, fluorophosphate, pyrophosphate, sulfate), and the like, but the present application is not limited to these materials, and other conventionally known materials that can be used as a positive electrode active material of a sodium ion battery may be used.

In some embodiments, the positive electrode film layer further optionally includes a binder. As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluoroacrylate resin.

In some embodiments, the positive electrode film layer further optionally includes a conductive agent. As an example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

In some embodiments, the positive electrode sheet may be prepared by: dispersing the above components for preparing the positive electrode sheet, such as the positive active material, the conductive agent, the binder and any other components, in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; and coating the positive electrode slurry on a positive electrode current collector, and drying, cold pressing and the like to obtain the positive electrode piece.

[ negative electrode sheet ]

The negative pole piece includes the negative pole mass flow body and sets up the negative pole rete on the negative pole mass flow body at least one surface, the negative pole rete includes negative pole active material.

As an example, the negative electrode current collector has two surfaces opposite in its own thickness direction, and the negative electrode film layer is disposed on either or both of the two surfaces opposite to the negative electrode current collector.

In some embodiments, the negative electrode current collector may employ a metal foil or a composite current collector. For example, as the metal foil, copper foil can be used. The composite current collector may include a polymer base layer and a metal layer formed on at least one surface of the polymer base material. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel alloy, titanium alloy, silver alloy, etc.) on a base material of a polymer material (e.g., a base material of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

In some embodiments, the negative active material may employ a negative active material for a battery known in the art. As an example, the anode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate and the like. The silicon-based material can be at least one selected from the group consisting of elemental silicon, a silicon oxy compound, a silicon carbon compound, a silicon nitrogen compound and a silicon alloy. The tin-based material may be selected from at least one of elemental tin, tin-oxygen compounds, and tin alloys. The present application is not limited to these materials, however, and other conventional materials that can be used as a battery negative active material may also be used. These negative electrode active materials may be used alone or in combination of two or more.

In some embodiments, the anode film layer further optionally includes a binder. The binder may be at least one selected from Styrene Butadiene Rubber (SBR), polyacrylic acid (PAA), sodium Polyacrylate (PAAs), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium Alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

In some embodiments, the negative electrode film layer further optionally includes a conductive agent. The conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

In some embodiments, the negative electrode film layer may also optionally include other adjuvants, such as thickeners (e.g., sodium carboxymethyl cellulose (CMC-Na)), and the like.

In some embodiments, the negative electrode sheet can be prepared by: dispersing the components for preparing the negative electrode plate, such as a negative electrode active material, a conductive agent, a binder and any other components, in a solvent (such as deionized water) to form negative electrode slurry; and coating the negative electrode slurry on a negative electrode current collector, and drying, cold pressing and the like to obtain the negative electrode pole piece.

[ electrolyte ]

The electrolyte plays a role in conducting ions between the positive pole piece and the negative pole piece. The kind of the electrolyte is not particularly limited and may be selected as desired. For example, the electrolyte may be liquid, gel, or all solid.

In some embodiments, the electrolyte is an electrolytic solution. The electrolyte includes an electrolyte salt and a solvent.

In some embodiments, the electrolyte salt may be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis-fluorosulfonylimide, lithium bis-trifluoromethanesulfonylimide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalato borate, lithium dioxaoxalato borate, lithium difluorodioxaoxalato phosphate, and lithium tetrafluorooxalato phosphate.

In some embodiments, the solvent may be selected from at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1, 4-butyrolactone, sulfolane, dimethylsulfone, methylethylsulfone, and diethylsulfone.

In some embodiments, the electrolyte further optionally includes an additive. For example, the additives may include a negative electrode film-forming additive, a positive electrode film-forming additive, and may further include additives capable of improving certain properties of the battery, such as an additive for improving overcharge properties of the battery, an additive for improving high-temperature or low-temperature properties of the battery, and the like.

[ isolation film ]

In some embodiments, the secondary battery further includes a separation film, and the separation film provided by the present invention may be used.

In some embodiments, the positive electrode tab, the negative electrode tab, and the separator may be manufactured into an electrode assembly through a winding process or a lamination process.

In some embodiments, the secondary battery may include an exterior package. The exterior package may be used to enclose the electrode assembly and electrolyte.

In some embodiments, the outer package of the secondary battery may be a hard case, such as a hard plastic case, an aluminum case, a steel case, or the like. The outer package of the secondary battery may also be a pouch, such as a pouch-type pouch. The material of the soft bag may be plastic, and examples of the plastic include polypropylene, polybutylene terephthalate, polybutylene succinate, and the like.

The shape of the secondary battery is not particularly limited, and may be a cylindrical shape, a square shape, or any other arbitrary shape. For example, fig. 4 is a secondary battery 5 of a square structure as an example.

In some embodiments, referring to fig. 5, the outer package may include a housing 51 and a cover plate 53. The housing 51 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose to form an accommodating cavity. The housing 51 has an opening communicating with the accommodating chamber, and a cover plate 53 can be provided to cover the opening to close the accommodating chamber. The positive electrode tab, the negative electrode tab, and the separator may be formed into the electrode assembly 52 through a winding process or a lamination process. An electrode assembly 52 is enclosed within the receiving cavity. The electrolyte wets the electrode assembly 52. The number of electrode assemblies 52 contained in the secondary battery 5 may be one or more, and those skilled in the art can select them according to the actual needs.

In some embodiments, the secondary batteries may be assembled into a battery module, and the number of the secondary batteries contained in the battery module may be one or more, and the specific number may be selected by those skilled in the art according to the application and capacity of the battery module.

Fig. 6 is a battery module 4 as an example. Referring to fig. 6, in the battery module 4, a plurality of secondary batteries 5 may be arranged in series along the longitudinal direction of the battery module 4. Of course, the arrangement may be in any other way. The plurality of secondary batteries 5 may be further fixed by a fastener.

Alternatively, the battery module 4 may further include a case having an accommodation space in which the plurality of secondary batteries 5 are accommodated.

In some embodiments, the battery modules may be assembled into a battery pack, and the number of the battery modules contained in the battery pack may be one or more, and the specific number may be selected by one skilled in the art according to the application and the capacity of the battery pack.

Fig. 7 and 8 are a battery pack 1 as an example. Referring to fig. 7 and 8, a battery pack 1 may include a battery case and a plurality of battery modules 4 disposed in the battery case. The battery box comprises an upper box body 2 and a lower box body 3, wherein the upper box body 2 can be covered on the lower box body 3, and an enclosed space for accommodating the battery module 4 is formed. A plurality of battery modules 4 may be arranged in any manner in the battery box.

In addition, this application still provides a power consumption device, power consumption device includes at least one in secondary battery, battery module or the battery package that this application provided. The secondary battery, the battery module, or the battery pack may be used as a power source of the electric device, and may also be used as an energy storage unit of the electric device. The powered device may include, but is not limited to, a mobile device (e.g., a mobile phone, a laptop computer, etc.), an electric vehicle (e.g., a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc.), an electric train, a ship, and a satellite, an energy storage system, etc.

As the electricity-using device, a secondary battery, a battery module, or a battery pack may be selected according to the use requirement thereof.

Fig. 9 is an electric device as an example. The electric device is a pure electric vehicle, a hybrid electric vehicle or a plug-in hybrid electric vehicle and the like. In order to meet the demand of the electric device for high power and high energy density of the secondary battery, a battery pack or a battery module may be used.

As another example, the device may be a cell phone, a tablet, a laptop, etc. The device is generally required to be thin and light, and a secondary battery may be used as a power source.

Examples

Hereinafter, examples of the present application will be described. The following description of the embodiments is merely exemplary in nature and is in no way intended to limit the present disclosure. The examples, where specific techniques or conditions are not indicated, are to be construed according to the techniques or conditions described in the literature in the art or according to the product specifications. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products commercially available.

Example 1

The present embodiment provides a lithium ion battery separator as shown in fig. 1-3. The base isolation film 11 is PE; thickness: 7 μm. The area of the first area accounts for 3% of the total area of the isolating membrane, the first bonding layer 111 of the first area is a mixture of cellulose and polytetrafluoroethylene, the cellulose content is 20wt.%, the coating mode is spot gluing, and the thickness: 4 μm; the first region inorganic protective layer 112 is a silicon dioxide layer with a thickness of 4 μm, and the cross-sectional shape of the first region is shown in fig. 2. The second zone bonding layer is polyvinylidene fluoride and is uniformly coated, and the thickness: 5 μm. The third region accounts for 3% of the total area of the separator, the third adhesive layer 131 is polyvinylidene fluoride and is uniformly coated, and the thickness: 5 μm; conductive polymer layer 132 is: polyacetylene, thickness: 4 μm, and the cross-sectional shape of the third region is shown in FIG. 3.

Example 2

The embodiment provides a lithium ion battery isolating membrane, wherein a basal membrane of the isolating membrane is PP/PE/PP; thickness: 12 μm. The first region accounts for 5% of the total area of the separator, the first region bonding layer thickness: 4 μm, the composition is the same as in example 1. The first region inorganic layer was a silicon dioxide layer with a thickness of 4 μm. The second zone bonding layer is polyvinylidene fluoride and is uniformly coated, and the thickness: 5 μm. The third area accounts for 5% of the total area of the isolating membrane, the bonding layer is polyvinylidene fluoride and is uniformly coated, and the thickness: 3 μm; the conducting layer is: polyacetylene, thickness: 3 μm.

Example 3

The embodiment provides a lithium ion battery isolating membrane, wherein a basal membrane of the isolating membrane is PP; thickness: 10 μm. The first region accounts for 5% of the total region of the release film, the first region bonding layer thickness: 4 μm, the composition is the same as in example 1; the inorganic layer in the first region is an aluminum oxide layer with a thickness of 4 μm. The second zone bonding layer is polyvinylidene fluoride and is uniformly coated, and the thickness: 5 μm. The third area accounts for 5% of the total area of the isolating membrane, the bonding layer is polyvinylidene fluoride and is uniformly coated, and the thickness: 5 μm; the conducting layer is: polyphenylacetylene, thickness: 4 μm.

Example 4

The difference from example 1 is that the first region is a uniform adhesive layer, and the rest remains unchanged.

Examples 5 to 8

The difference from example 1 is that the cellulose content in the binder used in the first region was 0, 40wt.%, 50wt.%, 80wt.%, respectively.

Example 9

The difference from example 1 is that cellulose and styrene-butadiene rubber are used as the binder in the first region and silica is used as the inorganic protective layer in the first region.

Example 10

The difference from example 1 is that the composition of the adhesive and the conductive polymer layer in the third region is different, polyaniline is used for the adhesive in the third region, and styrene-butadiene rubber is used for the conductive polymer layer.

Comparative example

A commercially available PE separator was used as it is, and had a thickness of 7 μm without any surface treatment.

The performance of the separators obtained in all the above examples was measured, and the results are shown in tables 1 and 2 below.

The detection method is as follows.

And (3) testing air permeability:

under normal pressure and low humidity environment, 6cm diaphragm is fixed to the air outlet (6.45 cm area) of air compression cylinder ² ) The time to pass 100cc of gas through the barrier film, i.e., the Gurley value, was recorded by applying a pressure of 1.21kPa to the compression cylinder by the test instrument.

And (3) porosity testing:

kneading the isolating membrane into a cluster, filling the cluster into a 3.5mL sample cup, placing the sample cup containing the sample into a true density tester, sealing a test system, introducing helium according to a program, detecting the pressure of gas in the sample chamber and the expansion chamber, and calculating the true volume according to Bohr's law (PV = nRT), thereby obtaining the porosity of the sample to be tested.

Porosity = (V1-V2)/V1 × 100%, V1: apparent volume of sample, V2: the true volume of the sample was measured and the triplicate structures averaged.

And (3) testing the bonding strength:

taking an isolating membrane sample with the area of more than 2.5cm x 20cm, flatly placing the sample on a short steel ruler pasted with a pole piece and double faced adhesive tapes, then bonding the pole piece and the isolating membrane together under certain pressure and temperature on a hot press, and finally carrying out a peeling test of the isolating membrane and an anode of 180 degrees on a tensile machine, wherein the tensile speed is 50mm/min, and taking the average value of three measurement results.

And (3) testing the liquid absorption rate:

under the normal-temperature and low-humidity environment, 10 battery isolating films (15cm × 15cm) are taken and placed on an electronic balance, the weight of the isolating films is weighed and recorded as m1, the isolating films are placed in a beaker containing 200mL of organic solvent (absolute ethyl alcohol, n-butyl alcohol and cyclohexane), the isolating films are guaranteed to be completely immersed in the organic solvent, after the fixing time is 10min, the isolating films immersed in the organic solvent are taken out, and m2 is weighed.

The liquid absorption rate of the separator = (m 2-m 1)/m 1 × 100%, and 5 measurements were taken as an average.

Table 1 porosity and bond strength of separators of different examples

Table 2 air permeability and liquid absorption of the membranes of the different examples

The above results show that:

1. compared with continuous gluing, the first area is glued in a dot mode, so that the bonding strength is hardly affected, and the porosity and the liquid absorption rate are remarkably improved;

2. the liquid absorption rate can be obviously improved by using the cellulose in the first area, and the liquid absorption rate is obviously improved along with the increase of the content of the cellulose in a certain range;

3. and after the third area adopts the combination of polyaniline and styrene butadiene rubber, the porosity, the bonding strength and the liquid absorption rate are obviously improved.

4. After the first area adopts the combination of cellulose and styrene butadiene rubber, the porosity and the air permeability are obviously improved.

Finally, it should be noted that: the above embodiments are only used for illustrating the technical solutions of the present application, and not for limiting the same; 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 or all of the technical features may be equivalently replaced; these modifications and substitutions do not depart from the spirit of the embodiments of the present application, and they should be construed as being included in the scope of the claims and description of the present application. In particular, the technical features mentioned in the embodiments can be combined in any way as long as there is no structural conflict. The present application is not intended to be limited to the particular embodiments disclosed herein but is to cover all embodiments that may fall within the scope of the appended claims.

Claims

1. A separator, comprising a base film;

2. The separator according to claim 1, wherein the membrane area ratio of the first region is 2% to 5%, the membrane area ratio of the second region is 90% to 96%, and the membrane area ratio of the third region is 2% to 5%.

3. The separator according to claim 1, wherein the porosity of the separator in the first region is 50% to 70%, the porosity in the second region is 20% to 60%, and the porosity in the third region is 20% to 60%.

4. The separator according to claim 1, wherein the first binder contains a cellulose-based material, and the weight ratio of the cellulose-based material in the first binder is preferably 20wt% or more.

5. The separator according to claim 1, wherein the inorganic protective layer comprises inorganic particles selected from the group consisting of: at least one of silica, alumina, zirconia, magnesia, titania, or calcia.

6. The diaphragm according to claim 1, wherein the second adhesive and the third adhesive are each independently one or a mixture of polyvinylidene fluoride, styrene-butadiene rubber, styrene-acrylic latex, polytetrafluoroethylene, polyacrylonitrile, polyvinylpyrrolidone, polyurethane, polyvinyl alcohol, and polyimide, preferably polyvinylidene fluoride.

7. Separator according to claim 1, characterized in that the conductivity of the conductive polymer layer is 10 ² ～10 ⁴ S/cm, preferably one or a mixture of polyacetylene, polypyrrole, polyphenylacetylene and polyaniline.

8. The separator as claimed in any one of claims 1 to 3, wherein the inorganic protective layer is silicon oxide, and the first binder is cellulose and styrene-butadiene rubber.

9. The separator according to any one of claims 1 to 3, wherein polyaniline is used as the conductive polymer layer, and styrene-butadiene rubber is used as the third binder.

10. A separator as claimed in any of claims 1 to 3, wherein said first adhesive is distributed in dots on said base film.

11. The separator according to claim 1, wherein the thicknesses of the separator in the first region, the second region, and the third region are 12 to 20 μm, 7 to 15 μm, and 10 to 18 μm, respectively.

12. A secondary battery characterized by comprising the separator according to any one of claims 1 to 11.

13. An electric device comprising the secondary battery according to claim 12.