阅读说明：本技术 电芯以及电池 (Battery cell and battery ) 是由 陶强 李帅 党琦 郑强 方占召 余仕禧 于 2018-07-03 设计创作，主要内容包括：本申请公开了一种电芯以及电池。电芯包括第一集流体、第二集流体和第一保护层,第一集流体包括第一段和第二段,第二集流体包括第三段和第四段,第一段的外侧表面设置活性物质层,第二段的外侧表面、第二段的内侧表面、第一段的内侧表面、第三段的外侧表面、第四端的内侧表面未设置活性物质层,第三段的外侧表面面对第一段的内侧表面和第二段的内侧表面,第四段的内侧表面面对第二段的外侧表面,第四段的内侧表面设置第一保护层。根据本申请的电芯,在针刺测试中通过第一集流体和第二集流体之间的短路,可以快速把电芯能量释放掉,避免电芯起火失效。另外,通过控制活性物质层的长度,可有效避免卷绕过程中集流体的滑动引起的短路问题。(The application discloses electric core and battery. The electric core includes first mass flow body, second mass flow body and first protective layer, first mass flow body includes first section and second section, the second mass flow body includes third section and fourth section, the outside surface of first section sets up active substance layer, the outside surface of second section, the inside surface of first section, the outside surface of third section, the inside surface of fourth end does not set up active substance layer, the outside surface of third section is to the inside surface of first section and the inside surface of second section, the inside surface of fourth section is to the outside surface of second section, the inside surface of fourth section sets up first protective layer. According to the battery core, through the short circuit between the first current collector and the second current collector in the acupuncture test, the battery core energy can be released quickly, and the battery core is prevented from being on fire and losing efficacy. In addition, the short circuit problem caused by the sliding of the current collector in the winding process can be effectively avoided by controlling the length of the active material layer.)

1. A cell, comprising:

a first current collector;

a second current collector, wherein the first current collector and the second current collector are wound to form the battery core;

a first protective layer;

the first current collector comprises a first section and a second section which are sequentially connected, wherein an active material layer is arranged on the outer side surface of the first section, and no active material layer is arranged on the outer side surface of the second section, the inner side surface of the second section and the inner side surface of the first section;

the second current collector comprises a third section and a fourth section, the third section is positioned at the inner side of the first section, the fourth section is positioned at the outer side of the second section, the outer side surface of the third section and the inner side surface of the fourth end are not provided with active material layers,

the outer side surface of the third section faces the inner side surface of the first section and the inner side surface of the second section, and the inner side surface of the fourth section faces the outer side surface of the second section;

wherein the first protective layer is located on the inner side surface of the fourth section.

2. The cell of claim 1, the first segment comprising a first arcuate segment and a first flat segment connected in series, the second segment comprising a second arcuate segment,

wherein the second arcuate segment is connected to the first straight segment.

3. The cell of claim 1, the third segment comprising a third arc-shaped segment, a second straight segment, and a fourth arc-shaped segment connected in series,

wherein the fourth segment comprises a fifth arcuate segment that is not connected to the fourth arcuate segment.

4. The cell of claim 3, the second current collector comprising a fifth segment,

wherein the fifth segment connects the fifth arcuate segment and the fourth arcuate segment.

5. The cell of claim 3, comprising a second protective layer, wherein the second protective layer is located on an outer side surface of the third segment.

6. The cell of claim 5, wherein the second protective layer is located on an outside surface of the third arc segment.

7. The cell of claim 1, wherein the first current collector is an anode current collector and the second current collector is a cathode current collector.

8. The cell of claim 1, wherein the first current collector is a copper foil and the second current collector is an aluminum foil.

9. A battery, comprising:

the cell of any of claims 1-8;

a first tab electrically connected to the first current collector;

the second pole lug is electrically connected with the second current collector;

packaging the shell;

the battery core is located in the packaging shell, and the first pole lug and the second pole lug penetrate through the packaging shell.

10. The battery according to claim 9, the package case including a first face and a second face, the first face and the second face being oppositely disposed at both sides of the package case in a direction perpendicular to the first tab;

wherein the first tab is closer to the second face than to the first face;

the first flat section is closer to the first face than the second face.

Technical Field

The present application relates to the field of electrochemical devices, and in particular, to an electrical core and a battery.

Background

Polymer lithium ion batteries are continually pursuing high energy density, which is accompanied by a great challenge in terms of safety, and many high energy density cells are at risk of failing certain safety tests, such as a needle punch test. The common method for improving the needling is carried out by a cathode-anode current collector which is not provided with two sides. However, the cathode and anode current collectors without two surfaces have certain disadvantages: firstly, the cathode and anode current collectors which are not arranged on the two sides easily slide in the winding process, so that the current collectors are contacted with each other, and the risk of short circuit exists in the subsequent charging and power generation process; secondly, for the cathode and anode current collectors which are not arranged on the two outer sides, when the battery core and the aluminum-plastic film generate relative displacement, such as falling, the double-sided adhesive tape at the ending part can tear the non-arranged current collectors, so that short circuit risk is caused; in addition, for the cathode and anode current collectors which are not arranged on the two inner sides, in actual working conditions, only a few layers of the surfaces of the battery cells are needled, and the cathode and anode current collectors which are not arranged on the two inner sides cannot be needled, so that the needling cannot play a role.

Content of application

The present application is directed to solving at least one of the problems in the prior art. For this reason, this application proposes a kind of electric core, electric core has simple structure, advantage that the performance is good.

The application also provides a battery, which is provided with the battery core.

According to the battery cell of the embodiment of the application, the battery cell comprises a first current collector, a second current collector and a first protective layer, the first current collector and the second current collector are wound to form the battery cell, the first current collector comprises a first section and a second section which are sequentially connected, an active material layer is arranged on the outer side surface of the first section, and no active material layer is arranged on the outer side surface of the second section, the inner side surface of the second section and the inner side surface of the first section; the second current collector comprises a third section and a fourth section, the third section is positioned on the inner side of the first section, the fourth section is positioned on the outer side of the second section, the outer side surface of the third section and the inner side surface of the fourth end are not provided with active material layers, the outer side surface of the third section faces the inner side surface of the first section and the inner side surface of the second section, and the inner side surface of the fourth section faces the outer side surface of the second section; the first protective layer is located on the inner side surface of the fourth section.

According to electric core of this application embodiment, set up first protective layer through the inboard surface at the fourth section, and the outside surface of the second section that faces with the inboard surface of fourth section does not set up active material layer, and this structure is short circuit between first mass flow body and the second mass flow body in the acupuncture test from this, can be fast to electric core energy release, avoids electric core to catch fire and loses efficacy. In addition, the length of the active material layer is controlled and arranged on the opposite surface of the first current collector and the second current collector, so that the problem of short circuit caused by the fact that the active material current collectors are not arranged on the two surfaces in the winding process in a sliding mode can be effectively solved.

In some embodiments, the first segment comprises a first arcuate segment and a first straight segment connected in series, and the second segment comprises a second arcuate segment connected to the first straight segment.

In some embodiments, the third segment comprises a third arc segment, a second straight segment, and a fourth arc segment connected in series, and the fourth segment comprises a fifth arc segment that is not connected to the fourth arc segment.

In some embodiments, the second current collector includes a fifth segment connecting the fifth arc segment and the fourth arc segment.

In some embodiments, the cell includes a second protective layer located on an outer side surface of the third segment.

In some embodiments, the second protective layer is located on an outer side surface of the third arc segment.

In some embodiments, the first current collector is an anode current collector and the second current collector is a cathode current collector.

In some embodiments, the first current collector is a copper foil and the second current collector is an aluminum foil.

A battery according to an embodiment of the present application includes: the battery cell is positioned in the packaging shell, and the first tab is electrically connected with the first current collector; the second pole lug is electrically connected with the second current collector; the first pole lug and the second pole lug penetrate through the packaging shell.

According to the battery of this application embodiment, set up first protective layer through the inside surface at the fourth section, and the outside surface of the second section that faces with the inside surface of fourth section does not set up active material layer, and this structure is short circuit between first mass flow body and the second mass flow body in the acupuncture test from this, can release electric core energy fast, avoids electric core to catch fire and loses efficacy. In addition, the length of the active material layer is controlled and arranged on the opposite surface of the first current collector and the second current collector, so that the problem of short circuit caused by the sliding of the active material current collectors which are not arranged on the two sides in the winding process can be effectively solved

In some embodiments, the package case includes a first face and a second face, and the first face and the second face are oppositely disposed at both sides of the package case in a vertical direction of the first tab; the first tab is closer to the second face than the first face; the first flat section is closer to the first face than the second face.

Drawings

The above and/or additional aspects and advantages of the present application will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

FIG. 1 is a schematic diagram of a cell according to an embodiment of the present application;

fig. 2 is a schematic structural diagram of a cell according to an embodiment of the present application;

fig. 3 is a schematic view of a winding structure of a first current collector of a cell according to an embodiment of the present application;

fig. 4 is a schematic view of a partial winding structure of a first current collector of a cell according to an embodiment of the present application;

fig. 5 is a schematic view of an unfolded structure of a first current collector of a battery cell according to an embodiment of the present application, wherein an arrow a is a winding direction;

fig. 6 is a schematic view of a winding structure of a second current collector of a cell according to an embodiment of the present application;

fig. 7 is a schematic view of a partial winding structure of a second current collector of a cell according to an embodiment of the present application;

fig. 8 is a schematic view of an unfolded structure of a second current collector of a battery cell according to an embodiment of the present application, wherein an arrow a is a winding direction;

fig. 9 is a schematic structural view of a package case of a battery cell according to an embodiment of the present application.

Reference numerals:

the cell 100, the active material layer 101,

a first current collector 110, a first section 111, a first arc-shaped section 1111, a first flat section 1112,

second segment 112, second arcuate segment 1121,

the second current collector 120 is disposed on the first current collector,

a third segment 121, a third arcuate segment 1211, a second straight segment 1212, a fourth arcuate segment 1213,

the length of the fourth segment 122, the fifth arc segment 1221,

in the fifth section 123, the first and second sections,

the first protective layer 130 is formed on the substrate,

the second protective layer (140) is formed on the substrate,

a battery 200, a first tab 201, a second tab 202,

a package shell 210, a deep-well surface 211 and a shallow-well surface 212.

Detailed Description

Reference will now be made in detail to embodiments of the present application, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are exemplary only for the purpose of explaining the present application and are not to be construed as limiting the present application.

In the description of the present application, it is to be understood that the terms "central," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the present application and to simplify the description, and are not intended to indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and are therefore not to be considered limiting of the present application. Furthermore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present application, "a plurality" means two or more unless otherwise specified.

In the description of the present application, it is to be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present application can be understood in a specific case by those of ordinary skill in the art.

The battery cell 100 and the battery 200 according to an embodiment of the present application are described in detail below with reference to the accompanying drawings. It should be noted that the battery 200 may include all kinds of primary batteries, secondary batteries, fuel cells, solar cells, and capacitors, such as a super capacitor. Particularly preferred are lithium secondary batteries including lithium metal secondary batteries, lithium ion secondary batteries, lithium polymer secondary batteries and lithium ion polymer secondary batteries.

In general, a lithium ion secondary battery may include a lithium-based oxide as a positive electrode active material constituting a cathode and a carbon material as a negative electrode active material constituting an anode. The cathode and anode are separated from each other by a separator (typically a polymeric microporous membrane) which allows the exchange of lithium ions between the two electrodes, while electrons cannot. Lithium ion batteries are further classified into liquid electrolyte batteries and polymer electrolyte batteries according to electrolytes used for lithium ion secondary batteries. For example, a secondary battery using a liquid electrolyte is called a "lithium ion secondary battery", and a secondary battery using a polymer electrolyte is called a "lithium polymer secondary battery". The lithium ion secondary battery may be formed in various shapes, such as a can type lithium ion secondary battery and a pouch type lithium ion secondary battery.

Typically, the battery cells 100 are assembled in a discharged state because the discharged cathode material (e.g., LiCoO2, LiFePO4) and anode material (e.g., carbon) are stable in air and thus easily handled in industrial practice. During charging, the two electrodes are connected to a power source outside the battery, thereby releasing electrons from the cathode to the anode. At the same time, lithium ions migrate inside the cell from the cathode through the electrolyte to the anode. In this way, external energy is stored electrochemically in the form of chemical energy in the anode material and the cathode material having different chemical potential energies (i.e., the cathode has a high potential and the anode has a low potential). During discharge, electrons migrate from the anode to the cathode for operation outside the battery through an external load (e.g., a circuit in a mobile phone or a motor in an electric vehicle), while, inside the battery, lithium ions migrate from the anode to the cathode in an electrolyte. As a result, the electrochemical reactions at the two electrodes release the stored chemical energy. This is also known as the "shuttle chair" mechanism by which lithium ions are shuttled between the anode and cathode during charge and discharge cycles.

Various parameters may be employed to monitor the performance of lithium ion batteries, such as specific energy, volumetric energy, specific capacity, cycling characteristics, safety, abuse resistance, and charge-discharge rate. For example, specific energy (Wh/kg) is used to measure the amount of energy that can be stored and released per unit mass of battery, and can be determined by multiplying specific capacity (Ah/kg) by battery operating voltage (V). The specific capacity is used to measure the amount of charge that can be reversibly stored per unit mass of the battery, and is closely related to the number of electrons released through the electrochemical reaction and the atomic weight of the host. The cycling characteristic is a measure of the reversibility of the lithium ion intercalation and deintercalation process, in terms of the number of charge and discharge cycles before the battery loses significant energy or is no longer able to maintain the functionality of the device it powers.

As shown in fig. 1, a battery cell 100 according to an embodiment of the present application includes a first current collector 110, a second current collector 120, and a first protective layer 130, which are stacked, and the first current collector 110 and the second current collector 120 are wound to form the battery cell 100. The first protective layer 130 may be a layer with viscosity, which may be adhered to the surface of the current collector.

As shown in fig. 3, 4, and 5, the first collector 110 may include a first section 111 and a second section 112 connected in sequence, an outer side surface (a surface in a c-side direction as shown in fig. 5) of the first section 111 is provided with the active material layer 101, an outer side surface (a surface in a c-side direction as shown in fig. 5) of the second section 112, an inner side surface (a surface in a b-side direction as shown in fig. 5) of the second section 112, and an inner side surface (a surface in a b-side direction as shown in fig. 5) of the first section 111 are not provided with the active material layer 101.

As shown in fig. 6, 7, and 8, the second current collector 120 may include a third section 121 and a fourth section 122.

Wherein the third segment 121 is located at the inner side of the first segment 111 (in the b-side direction shown in fig. 5 and 8), the fourth segment 122 is located at the outer side of the second segment 112 (in the c-side direction shown in fig. 5 and 8), the outer side surface of the third segment 121 (in the c-side direction shown in fig. 8), the inner side surface of the fourth end (the surface in the b-side direction shown in fig. 8) is not provided with the active material layer 101, the outer side surface of the third segment 121 (the surface in the c-side direction shown in fig. 8) faces the inner side surface of the first segment 111 (the surface in the b-side direction shown in fig. 5) and the inner side surface of the second segment 112 (the surface in the b-side direction shown in fig. 5), and the inner side surface of the fourth segment 122 (the surface in the b-side direction shown in fig. 8) faces the outer side surface of the second segment 112 (the surface in the c-side direction shown in fig. 5).

As shown in fig. 7, the first protective layer 130 is disposed on the inner side surface of the fourth section 122, that is, the inner side surface (the surface in the b-side direction shown in fig. 8) of the fourth section 122, so that the sliding of the battery cell 100 due to the absence of the active material collector on both sides during the winding process can be avoided.

According to the battery cell 100 of the embodiment of the present application, the first protection layer 130 is disposed on the inner side surface (the surface in the b-side direction shown in fig. 8) of the fourth section 122, and the active material layer 101 is not disposed on the outer side surface (the surface in the c-side direction shown in fig. 5) of the second section 112 facing the inner side surface (the surface in the b-side direction shown in fig. 8) of the fourth section 122, so that the structure can rapidly release the energy of the battery cell 100 through the short circuit between the first current collector 110 and the second current collector 120 in the needle punching test, and the battery cell 100 is prevented from being ignited and failed. In addition, by controlling the length of the active material layer 101 on the opposite surfaces of the first current collector 110 and the second current collector 120, the problem of short circuit caused by the sliding of the active material current collectors not arranged on the two surfaces during the winding process can be effectively avoided.

As shown in fig. 3, 4, according to some embodiments of the present application, the first segment 111 may include a first arc-shaped segment 1111 and a first straight segment 1112 connected in sequence. That is, during the winding process of the first segment 111, there is a portion of the first segment 111 located at the turning position to form the first arc-shaped segment 1111, and there is a portion of the first segment 111 located at the straight position to form the first straight segment 1112. Second segment 112 may include a second arcuate segment 1121, and second arcuate segment 1121 is connected to first straight segment 1112. It is understood that during the winding process of the second segment 112, at least a part of the structure of the second segment 112 is located at the turning position, which is the second arc-shaped segment 1121, and the second arc-shaped segment 1121 is connected to the first straight segment 1112 on the first segment 111.

As shown in fig. 6 and 7, the third segment 121 may include a third arc-shaped segment 1211, a second straight segment 1212, and a fourth arc-shaped segment 1213, which are connected in sequence. For example, as shown in fig. 7, in the winding process of the third segment 121, the structure of the wound third segment 121 includes a two-segment curved structure (i.e., the third arc-shaped segment 1211 and the fourth arc-shaped segment 1213) and a straight structure (i.e., the second straight segment 1212), and a straight structure is sandwiched between the two curved structures.

Further, as shown in fig. 7, fourth segment 122 may include a fifth arcuate segment 1221, where fifth arcuate segment 1221 is not connected to fourth arcuate segment 1213. It is understood that during the winding process of the fourth segment 122, at least part of the structure of the fourth segment 122 is located at the turning position to form the fifth arc-shaped segment 1221, and the other part of the structure of the second current collector 120 is located between the fifth arc-shaped segment 1221 and the fourth arc-shaped segment 1213, i.e., the fifth arc-shaped segment 1221 is indirectly connected to the fourth arc-shaped segment 1213.

In some embodiments, as shown in fig. 7, the second current collector 120 may include a fifth section 123, the fifth section 123 being U-shaped, the fifth section 123 being connected between a fifth arc-shaped section 1221 and a fourth arc-shaped section 1213. According to some embodiments of the present application, as shown in fig. 6 and 7, the second protective layer 140 is located on the outer side surface of the third segment 121, and the second protective layer 140 is disposed on the outer side surface of the third segment 121, so that the sliding of the battery cell 100 due to the fact that the active material current collector is not disposed on both sides during the winding process can be avoided. Further, the second passivation layer 140 is disposed on the outer surface of the third arc 1211. The second protective layer 140 may be a sticky material layer, which may be adhered to the surface of the current collector.

In some embodiments, the outermost ring of the battery cell 100 is a current collector with active material disposed on one side. For example, in the examples shown in fig. 2, 6, and 7, the tail structure of the second current collector 120 forms the outermost circle of the battery cell 100, and the active material layer 101 is disposed on only one side of the structure of the second current collector 120 located in the circle, so that the problem of tearing of the current collector caused by double-sided tapes when the battery cell 100 falls can be avoided.

According to some embodiments of the present application, the first current collector 110 is an anode current collector and the second current collector 120 is a cathode current collector. Further, the first current collector 110 is a copper foil, and the second current collector 120 is an aluminum foil. As shown in fig. 1 and fig. 2, a first tab 201 may be disposed at an end of the first current collector 110, a second tab 202 may be disposed at an end of the second current collector 120, and in a winding process of the battery cell 100, a connection end of the first tab 201 and the first current collector 110 is located inside the battery cell 100, and another end of the first tab 201 is located outside the battery cell 100; similarly, during the winding process of the battery cell 100, the connection end of the second tab 202 and the second current collector 120 is located inside the battery cell 100, and the other end of the second tab 202 is located outside the battery cell 100.

The main requirements for the cathode material include high free energy to react with lithium, high lithium incorporation, and insolubility in the electrolyte. In certain embodiments, the cathode materials can be classified based on voltage versus lithium as follows: (i)2 volt cathode materials, e.g. TiS with 2D layered structure₂And MoS₂(ii) a (i i)3 volt cathode materials, e.g. MnO₂And V₂O₅(ii) a (ii i i)4 volt cathode material, such as LiCoO with 2D layered structure₂、LiNiO₂3D spinel type LiMn₂O₄And olivine type LiFePO₄(ii) a And (iv)5 volt cathode materials such as olivine-type LiMnPO₄、LiCoPO₄And Li having a spinel-type 3D structure₂M_xMn4_-xO₈(M ═ at least one of Fe and Co). It is to be noted that, although a high cathode voltage is desired since the stored energy is proportional to the operating voltage of the battery cell 100, electrolyte stability is also required to be considered in selecting a high voltage cathode material.

Among the cathode materials described above, LiCoO₂And LiFePO₄Are most widely used in commercial lithium ion batteries because of their good cycle life: (>500 cycles). Further, LiCoO₂Is easy to mass-produce and stable in air. With LiCoO₂In contrast, LiFePO₄The base cathode material has lower production cost and low environmental load. LiFePO₄Other advantages offeredIncluding stability, excellent cycle life and temperature tolerance (-20-70 degrees centigrade). Two strategies (i.e., ion doping and carbon coating) have been employed to further enhance LiFePO₄Electron conductivity and ion conductivity.

The anode material has a larger library of candidates than the cathode material. The electrochemical performance of lithium ion batteries, including cycling characteristics, charge rate, and energy density, can be significantly affected by the anode material. Currently, carbon remains the dominant choice in today's commercial lithium ion batteries. For example, graphitic carbon having a layered structure can promote lithium ion migration into and out of the lattice space of graphitic carbon with minimal irreversibility, and excellent cycle characteristics are achieved.

Studies have shown that tin and many other elements (including silicon) known to be capable of alloying with lithium are good candidates for replacing carbon to achieve lithium storage. These elements are capable of electrochemically alloying and dealloying with lithium. However, during the charge/discharge process, the alloying/dealloying process is achieved by a substantial change in the specific volume of the material. Over several cycles, the high mechanical stresses induced can lead to a breakdown of the crystalline structure and to a decomposition of the active material and the current collector, or the so-called "chalking" phenomenon. The resulting poor cycle characteristics have significantly limited their applicability in practical situations. One way to improve the cycling characteristics of the anode material is to incorporate a composite. In such composite materials, one component (typically carbon) acts as a stress absorber, while the other component (e.g., silicon or tin) provides a substantial increase in capacity. In this way, a composite body having a higher capacity than carbon and a higher cycle characteristic than Sn or Si can be obtained.

The electrochemical characterization suggests that TiO, if used₂The potential risks of metallic lithium deposition and dendrite formation, cell shorting, and thermal runaway in carbon-based batteries can be avoided. In addition, in the potential window, in TiO₂No Surface Electrolyte Interphase (SEI) is formed thereon. Thus, in situations where safety is the first priority, e.g., in aerospace applications, TiO₂The base anode can find certain applications in terms of Li-base.

Iron oxide has been considered as a promising carbon substitute anode material for high capacity lithium ion batteries because of its low cost, non-toxicity, and environmental friendliness. Carbon coating has been used to improve the electrochemical performance of iron oxides. The carbon cladding layer can enhance the electrical conductivity of each single unit and improve better electrical contact between different units. The carbon layer may also act as a buffer layer to relieve stress due to large volume expansion, avoid structural collapse, or improve cycle characteristics.

Finally, studies have revealed that size and shape tunability of those nanoscale lithium active materials can impart additional parameters for further optimizing their electrochemical performance. Nanostructured electrode materials can impart a number of advantages not available in conventional bulk materials.

As shown in fig. 1 and fig. 9, a battery 200 according to an embodiment of the present application includes a first tab 201, a second tab 202, a package casing 210, and a battery cell 100, where the battery cell 100 may be the battery cell 100 described above, and the battery cell 100 is located in the package casing 210.

According to the battery 200 of the embodiment of the present application, the first protective layer 130 is disposed on the inner side surface (the surface in the b-side direction shown in fig. 8) of the fourth section 122, and the active material layer 101 is not disposed on the outer side surface (the surface in the c-side direction shown in fig. 5) of the second section 112 facing the inner side surface (the surface in the b-side direction shown in fig. 8) of the fourth section 122, so that the structure can rapidly release the energy of the battery cell 100 through the short circuit between the first current collector 110 and the second current collector 120 in the needle punching test, thereby preventing the battery cell 100 from being failed due to fire. In addition, by controlling the length of the active material layer 101 on the opposite surfaces of the first current collector 110 and the second current collector 120, the problem of short circuit caused by the sliding of the active material current collectors not arranged on the two surfaces during the winding process can be effectively avoided.

In some embodiments, as shown in fig. 9, the package 210 may include a deep pit 211 and a shallow pit 212, the deep pit 211 is opposite to the shallow pit 212, and the first section 111 is located in the deep pit 211, and since the waistcoat region is located at the deep pit 211 and the side of the second outer ring, the needle-punching operation can be effectively performed.

In some embodiments, as shown in fig. 9, the package case 210 includes a first surface 211 and a second surface 212, the first surface 211 and the second surface 212 are oppositely disposed on two sides of the package case 210 in a vertical direction of the first tab 201, the first tab 201 is closer to the second surface 212 than to the first surface 211, and the first flat segment 1112 is closer to the first surface 211 than to the second surface 212.

In the description herein, reference to the description of the terms "one embodiment," "some embodiments," "an illustrative embodiment," "an example," "a specific example," or "some examples" or the like means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the application. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

While embodiments of the present application have been shown and described, it will be understood by those of ordinary skill in the art that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the application, the scope of which is defined by the claims and their equivalents.