CN220710345U

CN220710345U - Pole piece, electrode assembly, battery monomer, battery and power utilization device

Info

Publication number: CN220710345U
Application number: CN202322202125.XU
Authority: CN
Inventors: 吴凯; 袁海峰; 周仓; 薛龙飞; 曹俊琪
Original assignee: Contemporary Amperex Technology Co Ltd
Current assignee: Contemporary Amperex Technology Co Ltd
Priority date: 2023-08-16
Filing date: 2023-08-16
Publication date: 2024-04-02
Anticipated expiration: 2033-08-16

Abstract

The application relates to a pole piece, an electrode assembly, a battery monomer, a battery and an electricity utilization device, wherein a first active layer and a second active layer with opposite polarities are integrated on the same current collecting structure to form a composite positive and negative electrode structure. Compared with the traditional independent positive and negative plates, the electrode plate structure has higher integration level, and can reduce the number of current collectors in the traditional independent positive and negative plates and the number of diaphragms arranged between the independent positive and negative plates to a certain extent. Thus, in the electrode assembly forming process, the number of assemblies in forming can be reduced, so that more pole pieces can be laminated or wound at the same thickness, and the energy density of the battery cell can be improved.

Description

Pole piece, electrode assembly, battery monomer, battery and power utilization device

Technical Field

The application relates to the technical field of batteries, in particular to a pole piece, an electrode assembly, a battery cell, a battery and an electric device.

Background

The electrode assembly is a component in which electrochemical reaction occurs in the battery cell, and is mainly formed by winding or stacking a positive electrode sheet and a negative electrode sheet, and a separator is generally provided between the negative electrode sheet and the positive electrode sheet. However, the structural design defect of the conventional electrode assembly is limited, so that the number of the electrode assembly is large when the electrode assembly is formed, and the improvement of the energy density of the battery is limited.

Disclosure of Invention

Based on the above, it is necessary to provide a pole piece, an electrode assembly, a battery cell, a battery and an electric device, which simplify the number of molding assemblies and help to increase the energy density of the battery cell.

In a first aspect, the present application provides a pole piece, the pole piece comprising: the electrode plate comprises a current collecting structure, a first active layer and a second active layer, wherein the first active layer and the second active layer are respectively arranged on two opposite side surfaces of the current collecting structure along the thickness direction of the electrode plate; the polarities of the first active layer and the second active layer are opposite, and the first active layer and the second active layer are isolated by a current collecting structure.

The pole piece integrates the first active layer and the second active layer with opposite polarities on the same current collecting structure to form a composite anode-cathode structure. Compared with the traditional independent positive and negative plates, the electrode plate structure has higher integration level, and can reduce the number of current collectors in the traditional independent positive and negative plates and the number of diaphragms arranged between the independent positive and negative plates to a certain extent. Thus, in the electrode assembly forming process, the number of assemblies in forming can be reduced, so that more pole pieces can be laminated or wound at the same thickness, and the energy density of the battery cell can be improved.

In some embodiments, the current collecting structure includes an insulating layer and a conductive layer disposed on at least one side of the insulating layer, where a side of the conductive layer facing away from the insulating layer is provided with a first active layer or a second active layer. In this way, the current collecting structure is designed into the conducting layer and the insulating layer, so that the first active layer and the second active layer can stably output current outwards; at the same time, the first active layer and the second active layer are also convenient to be isolated in an insulating way, so that the electrode assembly can normally operate.

In some embodiments, the conductive layer is disposed on a side of the insulating layer, the first active layer is disposed on a side of the conductive layer facing away from the insulating layer, and the second active layer is disposed on a side of the insulating layer facing away from the conductive layer, wherein the second active layer is configured as an active structure having a conductive function. Therefore, the second active layer is designed into an active structure with a conductive function, the arrangement of the conductive layer can be reduced, more active substances can be distributed under the requirement of the space with the same thickness, and the energy density of the battery cell is further improved.

In some embodiments, the second active layer is configured as a metal layer comprising aluminum or tin. Therefore, the second active layer is designed into an aluminum or tin-containing metal layer, and the overall weight of the pole piece is reduced on the premise of the same capacity, so that the energy density of the battery cell can be improved.

In some embodiments, the thickness of the second active layer along the thickness direction of the pole piece is no thinner than the thickness of the conductive layer along the thickness direction of the pole piece. The design is such that the thickness design of the second active layer can simultaneously satisfy the conductive function and participate in the battery reaction.

In some embodiments, the thickness of the conductive layer along the thickness direction of the pole piece is denoted as B1, and the thickness of the second active layer along the thickness direction of the pole piece is denoted as B2, wherein 1.ltoreq.B2/B1.ltoreq.20. Therefore, the ratio of the thickness of the second active layer to the thickness of the conductive layer is controlled to be 1-20, and the overall effective weight of the pole piece is conveniently controlled on the premise of meeting the effective active matter quantity on the second active layer, so that the overall energy density of the battery monomer is favorably improved.

In some embodiments, the value of B2/B1 also satisfies the condition: B2/B1 is more than or equal to 13 and less than or equal to 15. Therefore, the ratio of the thickness of the second active layer to the thickness of the conductive layer is controlled between 13 and 15, so that the whole effective weight of the pole piece is easier to control, and the energy density of the battery cell is convenient to improve.

In some embodiments, the current collecting structure further includes a tab, and the conductive layer and the second active layer are both connected to the tab. Therefore, the electrode lugs are respectively arranged on the conductive layer and the second active layer, so that the electrode assembly is convenient to charge and discharge.

In some embodiments, the insulating layer is configured to be deformable in a thickness direction of the pole piece. Therefore, the insulating layer is designed into a structure capable of deforming along the thickness direction, so that the volume expansion of the first active layer and the second active layer can be effectively buffered, and the stability of the whole structure of the battery cell is effectively improved.

In some embodiments, the material of the insulating layer includes one of polyethylene, polypropylene, polyvinyl chloride, polyamide resin, polyimide, ethylene phthalate, and polyester. Thus, the insulating layer is designed into a polymer, so that the volume expansion of the first active layer and the second active layer can be effectively buffered; the short circuit resistance of the battery cell when the inside of the battery cell is pierced by foreign matters can be improved, the risk of out-of-control short circuit in the battery cell is reduced, and the safety performance of the battery cell is improved.

In some embodiments, the thickness of the insulating layer along the thickness direction of the pole piece is denoted as B3, wherein 5 μm.ltoreq.B3.ltoreq.25μm. Thus, the thickness of the insulating layer is controlled to be 5-25 mu m, so that the structural design of the pole piece can effectively consider the structural stability and the energy density of the battery cell.

In some embodiments, the thickness B3 also satisfies the condition: b3 is more than or equal to 8 mu m and less than or equal to 16 mu m. Thus, the thickness of the insulating layer is further controlled to be 8-16 μm, so that the stability of the electrode assembly structure and the energy density of the battery cell can be better considered.

In some embodiments, the material of the first active layer comprises one of lithium iron phosphate, lithium nickel cobalt manganese oxide, lithium cobalt oxide, or lithium manganese oxide. In this way, the composition of the positive electrode material layer is reasonably designed so as to obtain an electrode assembly satisfying the requirements.

In a second aspect, the present application provides an electrode assembly comprising a separator disposed in a stack and a pole piece of any one of the above.

In some embodiments, the pole pieces include a plurality of pole pieces, a diaphragm is arranged between any two adjacent pole pieces at intervals, and a first active layer and a second active layer are respectively attached to two opposite side surfaces of the diaphragm between any two adjacent pole pieces. Thus, the pole pieces on two sides of the diaphragm are reasonably distributed, so that the positive and negative electrode active materials are convenient to be opposite, and the electrode assembly can be stably charged and discharged.

In a third aspect, the present application provides a battery cell comprising the above electrode assembly.

In a fourth aspect, the present application provides a battery comprising the above battery cell.

In a fifth aspect, the present application provides an electrical device comprising the above battery.

Drawings

Fig. 1 is a schematic structural diagram of a vehicle according to some embodiments of the present application.

Fig. 2 is an exploded view of a battery provided in some embodiments of the present application.

Fig. 3 is an exploded view of a battery cell according to some embodiments of the present application.

Fig. 4 is a view illustrating a structure of a pole piece according to some embodiments of the present application.

Fig. 5 is another view of the structure of a pole piece according to some embodiments of the present application.

Fig. 6 is a schematic structural view of a laminated electrode assembly according to some embodiments of the present application.

Fig. 7 is a schematic structural view of a rolled electrode assembly according to some embodiments of the present application.

1000. A vehicle; 100. a battery; 200. a controller; 300. a motor; 110. a battery cell; 120. a case; 12a, a first portion; 12b, a second portion; 10. an electrode assembly; 1. a pole piece; 11. a first active layer; 12. a second active layer; 13. a current collecting structure; 131. a conductive layer; 132. an insulating layer; 133. a tab; x, thickness direction; 2. a diaphragm; 20. an end cap; 30. an electrode terminal; 40. a housing.

Detailed Description

In order to make the above objects, features and advantages of the present application more comprehensible, embodiments accompanied with figures are described in detail below. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. This application is, however, susceptible of embodiment in many other forms than those described herein and similar modifications can be made by those skilled in the art without departing from the spirit of the application, and therefore the application is not to be limited to the specific embodiments disclosed below.

In the description of the present application, it should be understood that, if there are terms such as "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., these terms refer to the orientation or positional relationship based on the drawings, which are merely for convenience of description and simplification of description, and do not indicate or imply that the apparatus or element referred to must have a specific orientation, be configured and operated in a specific orientation, and therefore should not be construed as limiting the present application.

Furthermore, the terms "first," "second," and the like, if any, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In the description of the present application, the terms "plurality" and "a plurality" if any, mean at least two, such as two, three, etc., unless specifically defined otherwise.

In this application, unless explicitly stated and limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly. For example, the two parts can be fixedly connected, detachably connected or integrated; can be mechanically or electrically connected; either directly or indirectly, through intermediaries, or both, may be in communication with each other or in interaction with each other, unless expressly defined otherwise. The specific meaning of the terms in this application will be understood by those of ordinary skill in the art as the case may be.

In this application, unless expressly stated or limited otherwise, the meaning of a first feature being "on" or "off" a second feature, and the like, is that the first and second features are either in direct contact or in indirect contact through an intervening medium. Moreover, a first feature being "above," "over" and "on" a second feature may be a first feature being directly above or obliquely above the second feature, or simply indicating that the first feature is level higher than the second feature. The first feature being "under", "below" and "beneath" the second feature may be the first feature being directly under or obliquely below the second feature, or simply indicating that the first feature is less level than the second feature.

It will be understood that if an element is referred to as being "fixed" or "disposed" on another element, it can be directly on the other element or intervening elements may also be present. If an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and the like as used herein, if any, are for descriptive purposes only and do not represent a unique embodiment.

Currently, the application of power batteries is more widespread from the development of market situation. The power battery is not only applied to energy storage power supply systems such as hydraulic power, firepower, wind power and solar power stations, but also widely applied to electric vehicles such as electric bicycles, electric motorcycles, electric automobiles, and the like, and a plurality of fields such as military equipment, aerospace, and the like. With the continuous expansion of the application field of the power battery, the market demand of the power battery is also continuously expanding.

As an electrode assembly in which electrochemical reaction occurs in a battery cell, it is mainly formed by winding or stacking a positive electrode sheet and a negative electrode sheet, and a separator is generally provided between the negative electrode sheet and the positive electrode sheet. Generally, the higher the energy density of the battery monomer is, the larger the energy storage energy of the battery is, and the cruising of the battery can be effectively ensured.

In order to improve the energy density of the battery cell, the current collectors on the positive and negative plates are generally designed into a composite current collector, and the weight energy density of the battery cell is improved by reducing the weight of the current collector. However, although this structural design can raise the energy density to some extent, the degree of raising is limited. For example: in the structural design, in the forming process, the independent positive and negative plates are still adopted for lamination or winding, and the independent positive and negative plates are required to be respectively provided with the composite current collector; meanwhile, a diaphragm and the like are additionally arranged between the independent positive and negative plates, so that the structural design can lead to a large number of formed assemblies of the electrode assemblies, and therefore, the improvement of the energy density of the battery unit is limited.

Based on this, in order to effectively solve the problem of traditional structural design to the limitation of energy density promotion, the application provides a pole piece, with the first active layer and the second active layer integration that the polarity is opposite on same current collecting structure, constitutes compound positive negative pole structure. Compared with the traditional independent positive and negative plates, the electrode plate structure has higher integration level, and can reduce the number of current collectors in the traditional independent positive and negative plates and the number of diaphragms arranged between the independent positive and negative plates to a certain extent. Thus, in the electrode assembly forming process, the number of assemblies in forming can be reduced, so that more pole pieces can be laminated or wound at the same thickness, and the energy density of the battery cell can be improved.

In addition, the reduction of the number of components can also enable the winding mode to be quicker and the efficiency to be higher; while the requirements on the winding equipment are lower.

The battery cell disclosed by the embodiment of the application can be used in electric devices such as vehicles, ships or aircrafts, but is not limited to the electric devices. A power supply system having a battery cell, a battery, or the like disclosed in the present application, which constitutes the power utilization device, may be used.

The embodiment of the application provides an electricity utilization device using a battery as a power supply, wherein the electricity utilization device can be, but is not limited to, a mobile phone, a tablet, a notebook computer, an electric toy, an electric tool, a battery car, an electric car, a ship, a spacecraft and the like. Among them, the electric toy may include fixed or mobile electric toys, such as game machines, electric car toys, electric ship toys, electric plane toys, and the like, and the spacecraft may include planes, rockets, space planes, and spacecraft, and the like.

For convenience of description, the following embodiment will take an electric device according to an embodiment of the present application as an example of the vehicle 1000.

Referring to fig. 1, fig. 1 is a schematic structural diagram of a vehicle 1000 according to some embodiments of the present application. The vehicle 1000 may be a fuel oil vehicle, a gas vehicle or a new energy vehicle, and the new energy vehicle may be a pure electric vehicle, a hybrid vehicle or a range-extended vehicle. The battery 100 is provided in the interior of the vehicle 1000, and the battery 100 may be provided at the bottom or the head or the tail of the vehicle 1000. The battery 100 may be used for power supply of the vehicle 1000, for example, the battery 100 may be used as an operating power source of the vehicle 1000. The vehicle 1000 may also include a controller 200 and a motor 300, the controller 200 being configured to control the battery 100 to power the motor 300, for example, for operating power requirements during start-up, navigation, and travel of the vehicle 1000.

In some embodiments of the present application, battery 100 may not only serve as an operating power source for vehicle 1000, but may also serve as a driving power source for vehicle 1000, instead of or in part instead of fuel oil or natural gas, to provide driving power for vehicle 1000.

Referring to fig. 2, fig. 2 is an exploded view of a battery 100 according to some embodiments of the present application. The battery 100 includes a case 120 and a battery cell 110, and the battery cell 110 is accommodated in the case 120. The case 120 is used to provide an accommodating space for the battery cell 110, and the case 120 may have various structures. In some embodiments, the case 120 may include a first portion 12a and a second portion 12b, the first portion 12a and the second portion 12b being mutually covered, the first portion 12a and the second portion 12b together defining a receiving space for receiving the battery cell 110. The second portion 12b may be a hollow structure with an opening at one end, the first portion 12a may be a plate-shaped structure, and the first portion 12a covers the opening side of the second portion 12b, so that the first portion 12a and the second portion 12b together define an accommodating space; the first portion 12a and the second portion 12b may be hollow structures each having an opening at one side, and the opening side of the first portion 12a is covered with the opening side of the second portion 12 b. Of course, the case 120 formed by the first portion 12a and the second portion 12b may be of various shapes, such as a cylinder, a rectangular parallelepiped, or the like.

In the battery 100, the number of the battery cells 110 may be plural, and the plural battery cells 110 may be connected in series, parallel, or series-parallel, where series-parallel refers to both of the plural battery cells 110 being connected in series and parallel. The plurality of battery cells 110 can be directly connected in series or in parallel or in series-parallel, and then the whole formed by the plurality of battery cells 110 is accommodated in the box 120; of course, the battery 100 may also be a form of a plurality of battery cells 110 connected in series or parallel or series-parallel to form a battery 100 module, and a plurality of battery 100 modules connected in series or parallel or series-parallel to form a whole and accommodated in the case 120. The battery 100 may further include other structures, for example, the battery 100 may further include a bus bar member for making electrical connection between the plurality of battery cells 110.

Wherein each battery cell 110 may be a secondary battery or a primary battery; but not limited to, lithium sulfur batteries, sodium ion batteries, or magnesium ion batteries. The battery cell 110 may be in the shape of a cylinder, a flat body, a rectangular parallelepiped, or other shapes, etc.

Referring to fig. 3, fig. 3 is an exploded structure diagram of a battery cell 110 according to some embodiments of the present application. The battery cell 110 refers to the smallest unit constituting the battery 100. As shown in fig. 3, the battery cell 110 includes the end cap 20, the case 40, the electrode assembly 10, and other functional components.

The end cap 20 refers to a member that is covered at the opening of the case 40 to isolate the inner environment of the battery cell 110 from the outer environment. Without limitation, the shape of the end cap 20 may be adapted to the shape of the housing 40 to fit the housing 40. Optionally, the end cover 20 may be made of a material (such as an aluminum alloy) with a certain hardness and strength, so that the end cover 20 is not easy to deform when being extruded and collided, so that the battery cell 110 can have higher structural strength, and the safety performance can be improved. The end cap 20 may be provided with functional parts such as electrode terminals 30. The electrode terminal 30 may be used to be electrically connected with the electrode assembly 10 for outputting or inputting electric power of the battery cell 110. In some embodiments, the end cap 20 may also be provided with a pressure relief mechanism for relieving the internal pressure when the internal pressure or temperature of the battery cell 110 reaches a threshold. The material of the end cap 20 may be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., which is not particularly limited in the embodiments of the present application. In some embodiments, insulation may also be provided on the inside of the end cap 20, which may be used to isolate electrical connection components within the housing 40 from the end cap 20 to reduce the risk of short circuits. By way of example, the insulation may be plastic, rubber, or the like.

The case 40 is an assembly for cooperating with the end cap 20 to form an internal environment of the battery cell 110, wherein the formed internal environment may be used to accommodate the electrode assembly 10, electrolyte, and other components. The case 40 and the end cap 20 may be separate components, and an opening may be provided in the case 40, and the interior of the battery cell 110 may be formed by covering the opening with the end cap 20 at the opening. It is also possible to integrate the end cap 20 and the housing 40, but specifically, the end cap 20 and the housing 40 may form a common connection surface before other components are put into the housing, and when the interior of the housing 40 needs to be sealed, the end cap 20 is then covered with the housing 40. The housing 40 may be of various shapes and sizes, such as rectangular parallelepiped, cylindrical, hexagonal prism, etc. Specifically, the shape of the case 40 may be determined according to the specific shape and size of the electrode assembly 10. The material of the housing 40 may be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., which is not particularly limited in the embodiment of the present application.

The electrode assembly 10 is a component in which an electrochemical reaction occurs in the battery cell 110. One or more electrode assemblies 10 may be contained within the housing 40. The portion of the electrode assembly 10 having the active material constitutes the main body portion of the electrode assembly 10, and the portion having no active material constitutes the tab 133. The positive electrode tab 133 and the negative electrode tab 133 may be located at one end of the main body portion together or at two ends of the main body portion respectively. During charge and discharge of the battery 100, the positive and negative electrode active materials react with the electrolyte, and the tab 133 is connected to the electrode terminal 30 to form a current loop.

Referring to fig. 4, according to some embodiments of the present application, there is provided a pole piece 1, the pole piece 1 comprising: a current collecting structure 13, a first active layer 11 and a second active layer 12. The first active layer 11 and the second active layer 12 are respectively arranged on two opposite side surfaces of the current collecting structure 13 along the thickness direction X of the pole piece 1; the polarities of the first active layer 11 and the second active layer 12 are opposite, and the first active layer 11 and the second active layer 12 are isolated by the current collecting structure 13.

The current collecting structure 13 is a member or a component that can not only support an active material but also collect and output current generated by an electrode active material.

The first active layer 11 and the second active layer 12 are active materials respectively coated on opposite sides of the current collecting structure 13, and specific components thereof are different according to polarities. Such as: the active material of the positive electrode may be, but is not limited to, lithium cobalt oxide (e.g., liCoO 2), lithium nickel oxide (e.g., liNiO 2), lithium manganese oxide (e.g., liMnO2, liMn2O 4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (e.g., liNi1/3Co1/3Mn1/3O2 (which may also be abbreviated as NCM 333), liNi0.5Co0.2Mn0.3O2 (which may also be abbreviated as NCM 523), liNi0.5Co0.25Mn0.25O2 (which may also be abbreviated as NCM 211) at least one of LiNi0.6Co0.2Mn0.2O2 (which may also be abbreviated as NCM 622), liNi0.8Co0.1Mn0.1O2 (which may also be abbreviated as NCM 811), lithium nickel cobalt aluminum oxide (such as LiNi0.85Co0.15Al0.05O2) and modified compounds thereof, lithium iron phosphate (such as LiFePO4 (which may also be abbreviated as LFP)), a composite material of lithium iron phosphate and carbon, a composite material of lithium manganese phosphate (such as LiMnPO 4), a composite material of lithium manganese phosphate and carbon, lithium manganese iron phosphate, a composite material of lithium manganese iron phosphate and carbon, and the like.

And the active material of the negative electrode may be, but is not limited to, graphite, lithium titanate, silicon oxide, or the like. Of course, the active material of the anode may also be a structure having conductivity, such as: aluminum cathodes, and the like.

Since the polarities of the first active layer 11 and the second active layer 12 are opposite, the first active layer 11 and the second active layer 12 on the same current collecting structure 13 need an insulating process so that they are not electrically conducted with each other. At this time, the current collecting structure 13 should have an insulating effect, and can insulate the first active layer 11 from the second active layer 12.

In this manner, the number of components during the molding of the electrode assembly 10 can be advantageously reduced, so that more electrode sheets 1 can be laminated or wound at the same thickness, which helps to increase the energy density of the battery cell 110.

According to some embodiments of the present application, referring to fig. 4, optionally, the current collecting structure 13 includes an insulating layer 132 and a conductive layer 131 disposed on at least one side of the insulating layer 132, and a side of the conductive layer 131 facing away from the insulating layer 132 is provided with the first active layer 11 or the second active layer 12.

The insulating layer 132 is a structure having an insulating function such that the first active layer 11 and the second active layer 12 are not electrically connected to each other, and the material thereof may be selected from various materials such as: may be, but is not limited to, at least one of polyethylene, polypropylene, polyvinyl chloride, polyamide resin, polyimide, ethylene phthalate, polyester, and the like.

The conductive layer 131 refers to a member capable of converging and outputting current generated on the first active layer 11 and/or the second active layer 12. The material of the conductive layer 131 may also be selected from a variety of materials, such as: metallic materials such as copper, aluminum, nickel, stainless steel, etc.; and can also be a semiconductor material such as carbon, a composite material such as conductive resin, titanium-nickel shape memory alloy and carbon-coated aluminum foil.

The conductive layer 131 may be disposed on one side of the insulating layer 132, or may be disposed on opposite sides of the insulating layer 132, respectively. When the conductive layer 131 is disposed on one side of the insulating layer 132, one of the first active layer 11 and the second active layer 12 may be designed as an active layer having conductive capability. Among these, the conductive layer 131 is disposed on the insulating layer 132 in various manners, for example: may be, but is not limited to, bonding, electroplating, chemical vapor deposition, physical vapor deposition, and the like.

The current collecting structure 13 is designed to be a conductive layer 131 and an insulating layer 132, so that not only the first active layer 11 and the second active layer 12 can stably output current to the outside; at the same time, it is also convenient to insulate the first active layer 11 from the second active layer 12 so that the electrode assembly 10 can operate normally.

Optionally, referring to fig. 4, the conductive layer 131 is disposed on a side of the insulating layer 132, the first active layer 11 is disposed on a side of the conductive layer 131 opposite to the insulating layer 132, and the second active layer 12 is disposed on a side of the insulating layer 132 opposite to the conductive layer 131, wherein the second active layer 12 is configured as an active structure with a conductive function.

The second active layer 12 is configured as an active structure having a conductive function, which should be understood as: when an electric current is generated from the active material in the second active layer 12, the electric current is converged on the second active layer 12 and can be output to the outside. Such as: the second active layer 12 may be designed as a pure metallic aluminum or tin layer that forms an alloy compound with lithium ions during cyclic charge and discharge; alternatively, a composite layer of aluminum or tin metal and other metal phase may be designed for lithium ion occlusion and release.

In this way, the second active layer 12 is designed into an active structure with a conductive function, so that the arrangement of the conductive layer 131 can be reduced, more active substances can be distributed under the requirement of the same thickness space, and the energy density of the battery cell 110 is further improved.

Optionally, according to some embodiments of the present application, the second active layer 12 is configured as a metal layer comprising aluminum or tin.

The aluminum or tin-containing metal layer serves as a negative electrode active material, and may be pure metal aluminum or tin. In the cyclic charge and discharge process, metal aluminum also participates in the reaction with lithium ions besides realizing the conductive function, such as: the lithium ion and metallic aluminum may form an alloy compound, wherein the alloy compound LixAly may be, but is not limited to, li3Al2, li9Al4, and the like. Similarly, metallic tin reacts with lithium ions to produce alloy compounds, and LixSny can be Li22Sn5, li7Sn2 and the like

Of course, the metal layer containing aluminum or tin may also be an alloy structure, such as: the metal aluminum or tin in combination with other metal phases, wherein the other metal phases may be, but are not limited to, at least one of Si, ge, ag, sb, bi, in and Mg. At this time, other metal phases may be dispersed in the aluminum metal phase, and lithium ions may be occluded and released during cyclic charge and discharge. At the same time, act as buffer substances to mitigate volume changes caused during alloying.

The metal layer containing aluminum or tin is directly used as the negative electrode, and compared with the traditional graphite and copper foil combined structure, the weight of the negative electrode can be obviously reduced on the premise of the same capacity. Of course, in other words, at equal thicknesses, the metal layer containing aluminum or tin may have more capacity.

The second active layer 12 is designed to be a metal layer containing aluminum or tin, which is favorable for reducing the overall weight of the pole piece 1 on the premise of the same capacity, so that the energy density of the battery cell 110 can be improved.

Optionally, referring to fig. 5, the thickness of the second active layer 12 along the thickness direction X of the pole piece is not thinner than the thickness of the conductive layer 131 along the thickness direction X of the pole piece according to some embodiments of the present application.

The second active layer 12 is configured as an active structure having a conductive function, which means that a part of the second active layer 12 serves as an active material and participates in the reaction of the battery 100; another part is used as a conductive structure to collect and output generated current, such as: the second active layer 12 may be an aluminum-containing metal layer.

Thus, the thickness of the second active layer 12 can be designed with reference to the thickness of the conductive layer 131, such as: the thickness of the second active layer 12 should not be lower than the thickness of the conductive layer 131.

The design is such that the thickness design of the second active layer 12 is capable of satisfying both the conductive function and participating in the battery reaction.

Optionally, referring to fig. 5, the thickness of the conductive layer 131 along the thickness direction X of the pole piece 1 is denoted as B1, and the thickness of the second active layer 12 along the thickness direction X of the pole piece 1 is denoted as B2, wherein 1+.b2/b1+.20.

The thickness of the second active layer 12 may be the same as that of the conductive layer 131, i.e., b2/b1=1; or may be different. When the thickness of the second active layer 12 is not the same as that of the conductive layer 131, the thickness of the second active layer 12 may be designed to be greater than that of the conductive layer 131. Further, the ratio of the thickness of the second active layer 12 to the thickness of the conductive layer 131 is not preferably too large, and if too large, the amount of active material in the second active layer 12 is excessive and wasted. And at the same time, the weight of the electrode assembly 10 is increased with the same capacity, resulting in a decrease in the weight-to-energy density of the battery cell 110.

The value of B2/B1 can be one of 1 to 20, for example: the values of B2/B1 may be, but are not limited to, 1, 2, 4, 6, 10, 14, 18, 20, etc.

The thickness of the conductive layer 131 may depend on the actual product, for example: the thickness of the conductive layer 131 may be 1 μm to 10 μm. Of course, in other embodiments, the thickness of the conductive layer 131 may be 1 μm to 4 μm, such as: the thickness of the conductive layer 131 may be, but is not limited to, 1 μm, 2 μm, 3 μm, 4 μm, etc.

The ratio of the thickness of the second active layer 12 to the thickness of the conductive layer 131 is controlled between 1 and 20, so that the overall effective weight of the pole piece 1 is conveniently controlled on the premise of meeting the effective active matter quantity on the second active layer 12, and the overall energy density of the battery cell 110 is conveniently improved.

According to some embodiments of the present application, optionally, the value of B2/B1 further satisfies the condition: B2/B1 is more than or equal to 13 and less than or equal to 15.

The ratio B2/B1 can be between 13 and 15, for example: B2/B1 can be, but is not limited to, 13, 13.5, 14, 14.5, 15, etc. In particular to some embodiments, B2/B1 may be 14.

The ratio of the thickness of the second active layer 12 to the thickness of the conductive layer 131 is controlled between 13 and 15, so that the overall effective weight of the pole piece 1 is easier to control, and the energy density of the battery cell 110 is convenient to increase.

Optionally, referring to fig. 4, the current collecting structure 13 further includes a tab 133, and the tab 133 is connected to both the conductive layer 131 and the second active layer 12 according to some embodiments of the present application.

The tab 133 is a conductive structure extending outward from the electrode assembly 10, and the tab 133 is connected to the conductive layer 131 and the second active layer 12 in various manners, such as: the connection means may be, but is not limited to, welding, bonding, etc.

The tabs 133 are disposed on the conductive layer 131 and the second active layer 12, respectively, to facilitate charge and discharge of the electrode assembly 10.

According to some embodiments of the present application, the insulating layer 132 is optionally configured to be deformable in the thickness direction X of the pole piece 1.

During cyclic charge and discharge, the first active layer 11 and the second active layer 12 undergo volume expansion. If the insulating layer 132 is of a rigid structure, the swelling of the first active layer 11 and the second active layer 12 may be reflected in the swelling phenomenon occurring on the surface of the battery cell 110. For this reason, the insulating layer 132 is constructed in a structure deformable in the thickness direction X of the pole piece 1, such as a flexible structure or the like, which can well cushion expansion of the first active layer 11 and the second active layer 12. The material of the insulating layer 132 may be selected in various ways, and only a certain deformation function may be satisfied.

The insulating layer 132 is designed to be of a structure capable of deforming along the thickness direction X, so that the volume expansion of the first active layer 11 and the second active layer 12 can be effectively buffered, and the stability of the overall structure of the battery cell 110 can be effectively improved.

Optionally, according to some embodiments of the present application, the material of the insulating layer 132 includes one of polyethylene, polypropylene, polyvinyl chloride, polyamide resin, polyimide, ethylene terephthalate, and polyester.

The insulating layer 132 may be one of polyethylene, polypropylene, polyvinyl chloride, polyamide resin, polyimide, ethylene terephthalate, polyester. Of course, in other embodiments, the insulating layer 132 may also include two or more of polyethylene, polypropylene, polyvinyl chloride, polyamide resin, polyimide, ethylene terephthalate, and polyester.

In addition, in order to reduce the ductility of the polymer, a ceramic material such as one or more of oxide ceramic, nitride ceramic, carbide ceramic may be doped therein.

The insulating layer 132 is designed as a polymer, which is effective not only in buffering the volume expansion of the first active layer 11 and the second active layer 12; the short circuit resistance of the battery cell 110 when the battery cell 110 is pierced by foreign matters can be improved, the risk of out-of-control short circuit in the battery cell 110 is reduced, and the safety performance of the battery cell is improved.

According to some embodiments of the present application, the thickness of the insulating layer 132 in the thickness direction X of the pole piece 1 is optionally denoted as B3, wherein 5 μm.ltoreq.B3.ltoreq.25μm.

The thickness B3 of the insulating layer 132 may have a certain influence on the stability of the structure of the electrode sheet 1 and the energy density of the battery cell 110. For example: the thickness of the insulating layer 132 is too thin, so that the overall structural strength of the pole piece 1 is affected, and the structural stability of the electrode assembly 10 is reduced; too thick insulating layer 132 increases the overall weight of electrode assembly 10 and reduces the energy density of battery cell 110.

For this purpose, the thickness B3 of the insulating layer 132 may be a value between 5 μm and 25 μm, such as: the thickness B3 of the insulating layer 132 may be, but is not limited to, 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, etc.

By the design, the thickness of the insulating layer 132 is controlled to be 5-25 μm, so that the structural design of the pole piece 1 can effectively consider the structural stability and the energy density of the battery cell 110.

Optionally, referring to fig. 5, the thickness B3 further satisfies the following conditions according to some embodiments of the present application: b3 is more than or equal to 8 mu m and less than or equal to 16 mu m.

The thickness B3 of the insulating layer 132 may also be a value between 8 μm and 16 μm, such as: the thickness B3 of the insulating layer 132 may be, but is not limited to, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, etc.

The thickness of the insulating layer 132 is further controlled to be 8 μm to 16 μm so that the stability of the structure of the electrode assembly 10 and the energy density of the battery cell 110 can be better combined.

Optionally, according to some embodiments of the present application, the material of the first active layer 11 comprises one of lithium iron phosphate, lithium nickel cobalt manganate, lithium cobalt oxide or lithium manganate.

The material of the first active layer 11 may be one of lithium iron phosphate, lithium nickel cobalt manganese oxide, lithium cobalt oxide, or lithium manganese oxide. Of course, in other embodiments, the material of the first active layer 11 may be a combination of two or more of the above.

The composition of the positive electrode material layer is appropriately designed so as to obtain an electrode assembly 10 that satisfies the requirements.

In a second aspect, the present application provides an electrode assembly 10, the electrode assembly 10 comprising a separator 2 and a pole piece 1 of any one of the above, which are arranged in a stack.

The diaphragm 2 is a porous plastic film, ensures free passage of lithium ions to form a loop, and prevents two electrodes from contacting each other to perform an electronic insulation function. The type of which may be selected from, but is not limited to, polyethylene monolayer films, polypropylene monolayer films, and the like.

In addition, the electrode assembly 10 may be designed in a lamination type structure or a winding type structure, and reference is made to fig. 6 and 7.

The electrode assembly 10 adopts the above electrode sheet 1, so that the number of assemblies during the forming process of the electrode assembly 10 can be reduced, and more electrode sheets 1 can be laminated or wound under the same thickness, thereby being beneficial to improving the energy density of the battery cells 110.

According to some embodiments of the present application, the pole piece 1 optionally comprises a plurality. A diaphragm 2 is arranged between any two adjacent pole pieces 1 at intervals, and a first active layer 11 and a second active layer 12 are respectively stuck to the opposite two side surfaces of the diaphragm 2 between any two adjacent pole pieces 1.

The separator 2 has a first active layer 11 and a second active layer 12 attached to opposite sides thereof, respectively, which means that the opposite sides of the separator 2 are provided with a negative electrode active material and a positive electrode active material, respectively. Meanwhile, between the separator 2 and the electrode sheet 1, which are stacked, a lamination process may be used, and a winding process may be also used to obtain the electrode assembly 10.

The pole pieces 1 on two sides of the diaphragm 2 are reasonably distributed, so that positive and negative electrode active materials are convenient to be opposite, and the electrode assembly 10 can be charged and discharged stably.

According to some embodiments of the present application, there is provided a battery cell 110, the battery cell 110 including the above electrode assembly 10.

According to some embodiments of the present application, there is provided a battery 100, the battery 100 including the above battery cell 110.

According to some embodiments of the present application, there is provided an electric device including the above battery 100.

Referring to fig. 4 to 7, according to some embodiments of the present application, a pole piece 1 is provided, where the pole piece 1 includes a first active layer 11 and a composite anode structure. The composite anode structure comprises an insulating layer 132, a conductive layer 131 and an aluminum-containing metal layer, wherein the conductive layer 131 and the aluminum-containing metal layer are respectively attached to two opposite sides of the insulating layer 132, and the first active layer 11 is coated on one side of the conductive layer 131, which is opposite to the insulating layer 132.

For the purpose of simplifying and clarifying the objects, technical solutions and advantages of the present application, the present application will be described with reference to the following specific examples, but the present application is by no means limited to these examples. The embodiments described below are only preferred embodiments of the present application and may be used to describe the present application and should not be construed as limiting the scope of the present application. It should be noted that any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application are intended to be included in the scope of the present application.

For a better description of the present application, the following is a further description of the present application in connection with the examples. The following are specific examples.

Example 1

Preparing a composite negative electrode: and respectively depositing 2 mu m and 28 mu m aluminum metal layers on two sides of a 7 mu m ethylene glycol terephthalate (PET) material by a vacuum physical vapor deposition method, wherein the 28 mu m thick aluminum metal layer is used as a negative electrode and a negative electrode current collector, and the 2 mu m thick aluminum metal layer is used as a positive electrode current collector.

Preparing a composite positive and negative plate 1: the preferable LiCoO2 positive electrode slurry is coated on an Al positive electrode layer with the thickness of 2 mu m in a scraping way, a region with the thickness of 4 multiplied by 4cm is coated, the thickness of the coating is controlled to be 52 mu m, and the dried coating is cut into a pole piece 1 with the thickness of 4.3cm multiplied by 4.3cm to be used as a composite positive and negative pole piece 1 for standby, so that the total thickness of the composite positive and negative poles is controlled to be 89 mu m.

Assembly of laminated battery cell 110: punching an aluminum plastic film into a 5cm multiplied by 5cm aluminum plastic film bag, placing the composite positive and negative plates 1 in the aluminum plastic film to form a single-layer lamination, then sequentially performing side top sealing, injecting electrolyte, standing, sealing, forming, and separating to obtain the battery cell 110. The electrolyte is prepared by dissolving lithium hexafluorophosphate in a mixed solvent of ethylene carbonate, dimethyl carbonate and methyl ethyl carbonate (the volume ratio of the ethylene carbonate to the dimethyl carbonate to the methyl ethyl carbonate is 1:2:1), so as to obtain the electrolyte of the lithium ion battery 100.

Comparative example 1

Preparing a negative electrode sheet: dispersing graphite anode conductive agent and binder in solvent (N-methyl pyrrolidone), and stirring to form anode slurry. Then scraping the film on a copper foil current collector with the thickness of 5 mu m, drying the film with the thickness of 37 mu m, and cutting the film into pole pieces with the thickness of 4.3cm multiplied by 4.3cm to serve as a negative pole piece for standby.

Preparing a positive plate: the LiCoO2 positive electrode slurry is coated on a metal aluminum foil with the thickness of 13 mu m in a scraping way, the thickness of the coating is controlled to be 27 mu m, and the coating is dried and then cut into a pole piece with the thickness of 4cm multiplied by 4cm to be used as a positive electrode piece for standby.

The separator 2 is prepared: the 7 μm polyethylene film was cut into a 5 cm. Times.5 cm separator 2 for use, and the total thickness of the positive and negative electrodes plus the separator 2 was controlled to 89. Mu.m.

Laminated cell 110 assembly: the aluminum plastic film is punched into a 5cm multiplied by 5cm aluminum plastic film bag, and is placed in the aluminum plastic film according to the mode of 1 layer of positive electrode, 1 layer of diaphragm 2 and 1 layer of negative electrode to form a single-layer laminated battery cell 110, then side top sealing is sequentially carried out, electrolyte is injected, standing is carried out, sealing is carried out, and the battery cell 110 is obtained after formation and capacity division.

For energy density testing, reference may be made to Table 1 for specific results:

the battery cell 110 prepared above was evaluated by performing a 1/3C discharge test in a voltage interval of 2.5V to 4.45V. The battery cell 110 is discharged to obtain discharge energy. By measuring the mass of the battery cell 110, the weight energy density of the battery cell 110 can be calculated. Where energy density = discharge energy/mass.

TABLE 1

As is apparent from the comparison of example 1 and comparative example 1, the integration of the anode and the cathode on the same current collecting structure 13, and the use of the aluminum-containing metal layer as the anode, can effectively increase the energy density of the battery cell 110.

The technical features of the above-described embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above-described embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.

The above examples only represent a few embodiments of the present application, which are described in more detail and are not to be construed as limiting the scope of the claims. It should be noted that it would be apparent to those skilled in the art that various modifications and improvements could be made without departing from the spirit of the present application, which would be within the scope of the present application. Accordingly, the scope of protection of the present application is to be determined by the claims appended hereto.

Claims

1. A pole piece, the pole piece comprising: the electrode comprises a current collecting structure (13), a first active layer (11) and a second active layer (12), wherein the first active layer (11) and the second active layer (12) are respectively arranged on two opposite side surfaces of the current collecting structure (13) along the thickness direction (X) of the electrode piece;

Wherein the polarity of the first active layer (11) is opposite to that of the second active layer (12), and the first active layer (11) and the second active layer (12) are insulated and separated by the current collecting structure (13).

2. The pole piece according to claim 1, wherein the current collecting structure (13) comprises an insulating layer (132) and a conductive layer (131) arranged on at least one side surface of the insulating layer (132), and a side surface of the conductive layer (131) opposite to the insulating layer (132) is provided with the first active layer (11) or the second active layer (12).

3. The pole piece according to claim 2, characterized in that the conductive layer (131) is provided on a side of the insulating layer (132), the first active layer (11) is provided on a side of the conductive layer (131) facing away from the insulating layer (132), and the second active layer (12) is provided on a side of the insulating layer (132) facing away from the conductive layer (131), wherein the second active layer (12) is configured as an active structure with a conductive function.

4. A pole piece according to claim 3, characterized in that the second active layer (12) is configured as a metal layer containing aluminum or tin.

5. A pole piece according to claim 3, characterized in that the thickness of the second active layer (12) in the thickness direction (X) of the pole piece is not thinner than the thickness of the conductive layer (131) in the thickness direction (X) of the pole piece.

6. Pole piece according to claim 5, characterized in that the thickness of the conductive layer (131) in the thickness direction (X) of the pole piece is denoted B1, and the thickness of the second active layer (12) in the thickness direction (X) of the pole piece is denoted B2, wherein 1.ltoreq.b2/B1.ltoreq.20.

7. The pole piece of claim 6, wherein the value of B2/B1 further satisfies the condition: B2/B1 is more than or equal to 13 and less than or equal to 15.

8. A pole piece according to claim 3, characterized in that the current collecting structure (13) further comprises a pole lug (133), and the pole lug (133) is connected to both the conductive layer (131) and the second active layer (12).

9. The pole piece according to claim 2, characterized in that the insulating layer (132) is configured as a structure deformable in the thickness direction (X) of the pole piece.

10. The pole piece of claim 9, wherein the insulating layer (132) comprises one of polyethylene, polypropylene, polyvinyl chloride, polyamide resin, polyimide, ethylene phthalate, polyester.

11. Pole piece according to any of claims 2-10, characterized in that the thickness of the insulating layer (132) in the thickness direction (X) of the pole piece is denoted B3, wherein 5 μm +.b3 +.25 μm.

12. The pole piece of claim 11, wherein the thickness B3 further satisfies the condition: b3 is more than or equal to 8 mu m and less than or equal to 16 mu m.

13. A pole piece according to any of claims 1-10, characterized in that the material of the first active layer (11) comprises one of lithium iron phosphate, lithium nickel cobalt manganate, lithium cobalt oxide or lithium manganate.

14. An electrode assembly, characterized in that the electrode assembly comprises a separator (2) and a pole piece according to any one of claims 1-13, which are arranged in a stack.

15. The electrode assembly according to claim 14, wherein the electrode plate comprises a plurality of electrode plates, the separator (2) is arranged between any two adjacent electrode plates at intervals, and the first active layer (11) and the second active layer (12) are respectively attached to two opposite side surfaces of the separator (2) between any two adjacent electrode plates.

16. A battery cell comprising the electrode assembly of claim 14 or 15.

17. A battery comprising the cell of claim 16.

18. An electrical device comprising the battery of claim 17.