WO2021134788A1

WO2021134788A1 - Battery core, and electrochemical apparatus and electronic apparatus comprising battery core

Info

Publication number: WO2021134788A1
Application number: PCT/CN2020/070294
Authority: WO
Inventors: 曾巧; 肖良针; 闫东阳
Original assignee: 宁德新能源科技有限公司
Priority date: 2020-01-03
Filing date: 2020-01-03
Publication date: 2021-07-08
Also published as: CN113491029A

Abstract

A battery core, comprising an electrode assembly and a packaging bag for accommodating the electrode assembly, a bonding layer being arranged between the electrode assembly and the packaging bag. When the ratio of the bonding force and bonding area of the bonding layer satisfies a specific relationship, the battery core can maintain a high degree of safety performance even after being impacted. Also comprising an electrochemical apparatus and an electronic apparatus comprising said battery core.

Description

Electric core and electrochemical device and electronic device containing the same

Technical field

This application relates to the field of energy storage, in particular to a battery cell, an electrochemical device and an electronic device containing the same.

Background technique

As electrochemical devices (for example, lithium ion batteries) are widely used in electronic devices such as cameras, digital video cameras, mobile phones, and notebook computers, manufacturers and users are increasingly concerned about their safety and reliability. However, electrochemical devices are susceptible to external impacts (for example, falling from a height, etc.) during use, and are prone to breakage when impacted by external forces, resulting in safety problems such as liquid leakage, fire or even explosion.

In view of this, it is indeed necessary to provide an improved battery with good safety performance.

Summary of the invention

An electrochemical device usually includes a battery cell and a shell housing the battery cell. The battery cell includes an electrode assembly and a packaging bag for accommodating the electrode assembly. The electrode assembly passes through a positive pole piece, a negative pole piece, and is arranged between the positive pole piece and the positive pole piece. The separator between the negative pole pieces is wound or stacked in sequence. The electrode assembly may include tabs, and an adhesive layer is provided between the electrode assembly and the packaging bag. The setting of the adhesive layer plays an important role in the stability and safety of the cell after being impacted. If the adhesive layer is not set properly, the electrode assembly will be easily separated from the packaging bag after the battery is impacted, and its position will be changed, which may cause safety hazards such as liquid leakage, smoke, fire and even explosion.

This application solves at least one of the technical problems described in the background art through the provision of a specific adhesive layer.

In one aspect, an embodiment of the present application provides a battery cell, including an electrode assembly and a packaging bag accommodating the electrode assembly, an adhesive layer is provided between the electrode assembly and the packaging bag, and the adhesive The bonding force F (unit: N/m) of the layer and the bonding area ratio a satisfy the following relationship:

(Calculated by the value of each parameter), where the bonding area ratio a=(W1×L1)/(W2×L2), where W1 is the width of the bonding layer, and L1 is the bonding layer Length, W2 is the width of the electrode assembly (the electrode assembly can be formed by winding or stacking), and L2 is the length of the electrode assembly (or the width of the outermost ring of the electrode assembly after unfolding, the outermost The circle can refer to the positive pole piece, the negative pole piece or the separator), and W1, L1, W2 and L2 have the same unit, such as mm or cm.

In some embodiments, the bonding force F and the bonding area ratio a of the bonding layer satisfy the following relationship:

When the adhesion force and the bonding area ratio of the adhesive layer in the cell conform to the above relationship, after the cell is impacted, the electrode assembly and the packaging bag have appropriate friction, so that the electrode assembly and the packaging bag have an appropriate frictional force. There will be neither separation nor excessive tearing between.

In some embodiments, the positive pole piece in the electrode assembly is bonded to the packaging bag. In some embodiments, the negative pole piece in the electrode assembly is adhered to the packaging bag. In some embodiments, the separator in the electrode assembly is adhered to the packaging bag.

According to an embodiment of the present application, the bonding area ratio a is not less than 20% and not more than 97%. In some embodiments, the bonding area ratio a is not less than 70% and not more than 97%. When the bonding area ratio a of the bonding layer is within the above range, the electrode assembly is easy to be packaged in the packaging bag, and the surface of the bonding layer is flat, which will not affect the interface of the cell, and thus will not affect the circulation of the cell. Any adverse effects on performance.

According to an embodiment of the present application, the adhesive force F is not less than 1 N/m and not more than 150 N/m. In some embodiments, the adhesive force F is not less than 10 N/m and not more than 120 N/m. In some embodiments, the adhesive force F is not less than 30 N/m and not more than 100 N/m. In some embodiments, the adhesive force F is not less than 50 N/m and not more than 80 N/m.

According to an embodiment of the present application, the electrode assembly includes a first pole piece, the first pole piece includes a first current collector, a first active material layer, and a first tab, and the first active material layer is disposed on the On at least a part of the first current collector, and the first active material layer is not provided at the starting end of the first current collector, and the first tab is electrically connected to the starting end of the first current collector; or An active material layer is provided with a first groove, and the first tab is arranged in the first groove and is electrically connected to the first current collector.

According to an embodiment of the present application, the first pole piece may further include at least one first tab, the first active material layer is provided with at least one first groove, and the plurality of first tabs are respectively disposed in The corresponding at least one first groove is electrically connected to the first current collector; or the at least one first tab is cut by the first current collector.

According to an embodiment of the present application, the electrode assembly includes a second pole piece, and the second pole piece has substantially the same configuration as the first pole piece. In some embodiments, the second pole piece includes a second current collector, a second active material layer, and a second tab, the second active material layer is disposed on at least a part of the second current collector, and The second active material layer is not provided at the starting end of the second current collector, and the second tab is electrically connected to the starting end of the second current collector; or the second active material layer is provided with a second groove, The second tab is arranged in the second groove and is electrically connected to the second current collector. In some embodiments, the second pole piece includes at least one second tab, the first active material layer is provided with at least one second groove, and the plurality of second tabs are respectively disposed on the corresponding The at least one second groove is electrically connected to the second current collector; or the at least one second tab is cut by the second current collector.

According to an embodiment of the present application, the adhesive layer has a single-layer structure or a multi-layer structure.

According to an embodiment of the present application, the adhesive layer is in the shape of a sheet, a dot or a strip.

According to an embodiment of the present application, the adhesive layer is continuously or discontinuously provided between the electrode assembly and the packaging bag.

According to an embodiment of the present application, the adhesive layer is disposed on at least one straight section of the wound electrode assembly.

According to an embodiment of the present application, the adhesive layer has a regular morphology, an irregular morphology or a combination thereof.

According to an embodiment of the present application, the adhesive layer includes at least one of polybutadiene, polypropylene, polypentadiene, and a copolymer of styrene or butadiene, and a petroleum resin. In some embodiments, the adhesive layer further includes at least one of wood powder, talc, or calcium carbonate.

In another aspect, an embodiment of the present application provides an electrochemical device, which includes any of the above-mentioned battery cells according to the embodiments of the present application.

In yet another aspect, an embodiment of the present application provides an electronic device, which includes any of the electrochemical devices described above according to the embodiments of the present application.

The additional aspects and advantages of the embodiments of the present application will be partially described, shown, or explained through the implementation of the embodiments of the present application in the subsequent description.

Description of the drawings

Hereinafter, the drawings necessary to describe the embodiments of the present application or the prior art will be briefly described in order to describe the embodiments of the present application. Obviously, the drawings in the following description are only part of the embodiments in the present application. For those skilled in the art, without creative work, the drawings of other embodiments can still be obtained according to the structures illustrated in these drawings.

Fig. 1 shows a schematic diagram of the pole piece of the outermost circle of the electrode assembly according to an embodiment of the present application after unfolding.

Fig. 2A shows a schematic diagram of an electrode assembly having a sheet-shaped area adhesive layer according to an embodiment of the present application.

Fig. 2B shows a schematic diagram of an electrode assembly having a plurality of sheet-shaped area adhesive layers according to an embodiment of the present application.

FIG. 2C shows a schematic diagram of an electrode assembly with a dot-shaped area adhesive layer according to an embodiment of the present application.

Fig. 2D shows a schematic diagram of an electrode assembly having a strip-shaped area adhesive layer according to an embodiment of the present application.

FIG. 2E shows a schematic diagram of an electrode assembly having multiple strip-shaped area bonding layers according to an embodiment of the present application.

Fig. 3 shows a schematic diagram of a first pole piece according to an embodiment of the present application.

FIG. 4 shows a cross-sectional view of the electrode assembly including the first pole piece shown in FIG. 3.

Fig. 5 shows a schematic diagram of a first pole piece according to another embodiment of the present application.

FIG. 6 shows a cross-sectional view of the electrode assembly including the first pole piece shown in FIG. 5.

Fig. 7 shows a schematic diagram of a first pole piece according to another embodiment of the present application.

FIG. 8 shows a cross-sectional view of the electrode assembly including the first pole piece shown in FIG. 7.

Detailed ways

The embodiments of this application will be described in detail below. In the full text of the specification of this application, the same or similar components and components with the same or similar functions are denoted by similar reference numerals. The embodiments related to the drawings described herein are illustrative, diagrammatic, and used to provide a basic understanding of the present application. The embodiments of this application should not be construed as limitations on this application.

In this application, unless otherwise specified or limited, when a first feature is located "above" or "below" a second feature in a structure, the structure may include embodiments in which the first feature and the first feature The two features are in direct contact, and the structure may also include another embodiment, wherein the first feature is not in direct contact with the second feature, but is in contact with an additional feature formed between the two. In addition, when the first feature is "above", "above", or "on top of" the second feature, it may include embodiments in which the first feature is directly or obliquely Located "above" the second feature, "above" or "on the top of the second feature", or only means that the height of the first feature is higher than the height of the second feature; and when the first feature When located "under" the second feature, "under" the second feature, or "at the bottom of the second feature", it may include embodiments in which the first feature is directly or obliquely located on the second feature" "Below", "below" the second feature, or "at the bottom of the second feature", or only means that the height of the first feature is lower than the height of the second feature.

The embodiment of the present application provides a battery cell, which includes an electrode assembly and a packaging bag containing the electrode assembly. An adhesive layer is provided between the electrode assembly and the packaging bag. The force F and the bonding area ratio a satisfy the following relationship:

The bonding area ratio a=(W1×L1)/(W2×L2), where W1 is the width of the bonding layer, L1 is the length of the bonding layer, W2 is the width of the electrode assembly, The electrode assembly can be formed by winding or stacking positive pole pieces, separators and negative pole pieces in sequence, and L2 is the length of the electrode assembly, or L2 refers to the width of the outermost ring of the electrode assembly after unfolding, The outermost circle can refer to the positive pole piece (as shown in Figure 1), the negative pole piece or the separator.

In some embodiments, the adhesive layer has a sheet shape, a dot shape or a strip shape.

When the adhesive layer is in the form of a sheet, the adhesive area ratio of the adhesive layer is the sum of the adhesive area of each sheet-shaped adhesive layer (that is, the area where each adhesive layer is in contact with the electrode assembly) and the adhesive The ratio between the surface area of the electrode assembly on the side of the layer. As shown in FIG. 2A, when the adhesive layer has a sheet-shaped adhesive layer, a=(W1×L1)/(W2×L2). As shown in Figure 2B, when the adhesive layer includes a plurality of sheet-shaped adhesive layers (a, b, c, d, and e), the bonding area is the size of the sheet-shaped adhesive layers a, b, c, d, and e. The total area, a=(W1a×L1a+W1b×L1b+W1c×L1c+W1d×L1d+W1e×L1e)/(W2×L2).

When the adhesive layer is dot-shaped, the adhesive area ratio is the ratio between the area surrounded by the adhesive material dots of the outermost circle and the surface area of the electrode assembly on the side where the adhesive layer is provided. As shown in FIG. 2C, the adhesive layer includes a plurality of dot-shaped adhesive layers, a=(W1×L1)/(W2×L2).

When the adhesive layer has a strip shape, the adhesive area ratio is the ratio between the total area of each strip-shaped adhesive layer and the surface area of the electrode assembly on the side where the adhesive layer is provided. As shown in FIG. 2D, when the adhesive layer has a strip-shaped adhesive layer, a=(W1×L1)/(W2×L2). As shown in Figure 2E, when the bonding layer includes multiple strip-shaped bonding layers (x and y), the bonding area is the sum of the strip-shaped bonding layers x and y, a=(W1x×L1x+W1y×L1y )/(W2×L2).

In some embodiments, the adhesive layer has a single-layer structure or a multi-layer structure.

In some embodiments, the adhesive layer is continuously disposed between the battery core and the housing, as shown in FIGS. 2A and 2D.

In some embodiments, the adhesive layer is discontinuously disposed between the electrode assembly and the packaging bag, as shown in FIGS. 2B, 2C, and 2E.

In some embodiments, the adhesive layer has a regular morphology (as shown in FIG. 2E), an irregular morphology (as shown in FIG. 2D), or a combination thereof. The term "regular topography" refers to the regular topography of the bonding layer boundary, for example, square, rectangle, rhombus, circle, ellipse, triangle, trapezoid, polygon, etc. The term "irregular topography" refers to the irregular topography of the bonding layer boundary, that is, the topography that is different from the regular topography, for example, those topography that cannot be named by conventional shape terms.

In some embodiments, the bonding area ratio a of the bonding layer is not less than 20% and not more than 97%. In some embodiments, the bonding area ratio a is not less than 70% and not more than 97%. When the bonding area ratio of the bonding layer is within the above range, the electrode assembly is easy to be packaged in the packaging bag, and the bonding layer has a flat surface, which will not affect the interface of the cell, and will not affect the cycle performance of the cell. Have any adverse effects.

In some embodiments, the adhesive force F is not less than 1 N/m and not more than 150 N/m. In some embodiments, the adhesive force F is not less than 10 N/m and not more than 120 N/m. In some embodiments, the adhesive force F is not less than 30 N/m and not more than 100 N/m. In some embodiments, the adhesive force F is not less than 50 N/m and not more than 80 N/m.

In some embodiments, the battery cell includes a first pole piece, the first pole piece includes a first current collector, a first active material layer, and a first tab, and the first active material layer is disposed on the At least a part of the first current collector may be as shown in FIGS. 3 and 4.

In some embodiments, the first active material layer is not provided at the starting end of the first current collector, and the first tab is electrically connected to the starting end of the first current collector, as shown in FIGS. 3 and 4 Shown.

Fig. 3 shows a first pole piece according to an embodiment of the present application. The first pole piece 300 includes a first current collector 301, a first active material 302 and a first tab 303. The first active material 302 is provided on both surfaces of the first current collector 301 (ie, the first surface 300a and the second surface 300b). The first current collector 301 includes a starting end 304,

middle portions

305a, 305b, and ending ends 306a, 306b along the winding direction. The first active material 302 is disposed on the

middle portions

305a, 305b of the first current collector 301, and the first tab 303 It is arranged at the starting end 304 of the first current collector 301 and is electrically connected to the first current collector 301. As shown in FIG. 3, the middle portion 305a provided with the first active material 302 on the first surface 300a is longer than the middle portion 305b provided with the first active material 302 on the second surface 300b, so that the first current collector 301 includes a single side The portion 307 is a portion having the first active material 302 only on one side surface of the first current collector 301. In some embodiments, the second pole piece 310 includes a second current collector 311, a second active material 312, and a second tab 313, and the second pole piece 310 and the first pole piece 300 may adopt substantially the same configuration. FIG. 4 shows an electrode assembly formed by winding the first pole piece 300, the isolation film 320, and the second pole piece 310 shown in FIG. 3 in sequence, where W2 is the width of the electrode assembly after being wound.

In some embodiments, the first active material layer is provided with a first groove, and the first tab is arranged in the first groove and is electrically connected to the first current collector, as shown in FIG. 5 and Shown in Figure 6.

Fig. 5 shows a first pole piece according to another embodiment of the present application. The first pole piece 500 includes a first current collector 501, a first active material 502 and a first tab 503. The first active material 502 is provided on both surfaces of the first current collector 501 (ie, the first surface 500a and the second surface 500b). The first current collector 501 includes a starting end 504,

middle portions

505a, 505b, and ending ends 506a, 506b along the winding direction, and the first active material 502 is provided in the

middle portions

505a, 505b of the first current collector 501. The

middle parts

505 a and 505 b of the first current collector 501 provided with the first active material 502 are provided with grooves 508, and the first tab 503 is arranged in the groove 508 and is electrically connected to the first current collector 501. As shown in FIG. 5, the middle portion 505a provided with the first active material 502 on the first surface 500a is longer than the middle portion 505b provided with the first active material 502 on the second surface 500b, so that the first current collector 501 includes a single side The portion 507 is a portion having the first active material 502 only on one side surface of the first current collector 501. In some embodiments, the second pole piece 510 includes a second current collector 511, a second active material 512, and a second tab 513, and the second pole piece 510 and the first pole piece 500 may have substantially the same configuration. FIG. 6 shows an electrode assembly formed by winding the first pole piece 500, the isolation film 520, and the second pole piece 510 shown in FIG. 5, where W2 is the width of the electrode assembly after being wound.

In some embodiments, the first pole piece includes at least one first tab, the first active material layer is provided with at least one first groove, and the plurality of first tabs are respectively disposed on the corresponding The at least one first groove is electrically connected to the first current collector, as shown in FIGS. 7 and 8.

In some embodiments, the at least one first tab is cut through the first current collector.

Fig. 7 shows a first pole piece according to another embodiment of the present application. The first pole piece 700 includes a first current collector 701, a first active material 702, and a first tab 703. The first active material 702 is provided on both surfaces of the first current collector 701 (ie, the first surface 700a and the second surface 700b). The first current collector 701 includes

coated regions

705a, 705b and uncoated regions 706a, 706b along the winding direction, and the first active material 702 is provided in the

coated regions

705a, 705b of the first current collector 701. The first tab 703 is cut through the first collector 701. As shown in FIG. 7, the middle portion 705a provided with the first active material 702 on the first surface 700b is longer than the middle portion 705b provided with the first active material 702 on the second surface 700b, so that the first current collector 701 includes a single side The portion 707, that is, the portion having the first active material 702 on only one side surface of the first current collector 701. In some embodiments, the second pole piece 710 includes a second current collector 711, a second active material 712, and a second tab 713, and the second pole piece 710 and the first pole piece 700 may adopt substantially the same configuration. FIG. 8 shows an electrode assembly formed by winding the first pole piece 700, the isolation film 720, and the second pole piece 710 shown in FIG. 7, where W2 is the width of the electrode assembly after being wound.

In some embodiments, the adhesive layer is disposed on at least one straight section of the wound electrode assembly.

In some embodiments, the adhesive layer includes at least one of polybutadiene, polypropylene, polypentadiene, and a copolymer of styrene or butadiene, and a petroleum resin. In some embodiments, the adhesive layer further includes at least one of wood powder, talc, or calcium carbonate.

The embodiment of the present application also provides an electrochemical device, which includes the battery cell according to any one of the embodiments of the present application. The electrochemical device of the embodiment of the present application includes any device that undergoes an electrochemical reaction, and specific examples thereof include all kinds of primary batteries, secondary batteries, fuel cells, solar cells, or capacitors. In particular, the electrochemical device is a lithium secondary battery, including a lithium metal secondary battery, a lithium ion secondary battery, a lithium polymer secondary battery, or a lithium ion polymer secondary battery.

An embodiment of the application further provides an electronic device, which includes the electrochemical device according to any embodiment of the application. The electrochemical device of the present application includes any device that undergoes an electrochemical reaction, and specific examples thereof include all kinds of primary batteries, secondary batteries, fuel cells, solar cells, or capacitors. In particular, the electrochemical device is a lithium secondary battery, including a lithium metal secondary battery, a lithium ion secondary battery, a lithium polymer secondary battery, or a lithium ion polymer secondary battery. In some embodiments, the electrochemical device of the embodiment of the present application includes a positive pole piece having a positive active material capable of inserting and extracting metal ions, a negative pole piece according to the embodiment of the present application, an electrolyte, and a positive electrode. Separating film between sheet and negative pole sheet.

The following takes a lithium ion battery as an example and describes the preparation of the flexible package in combination with specific examples. Those skilled in the art will understand that the preparation methods described in this application are only examples, and any other suitable preparation methods are within the scope of this application. Inside.

Example

One, the preparation of the battery

The positive pole piece, the isolation membrane and the negative pole piece are placed in sequence and wound to form an electrode assembly. An adhesive substance is provided on a straight section of the outer surface of the wound electrode assembly to form an adhesive layer. The electrode assembly is placed in the packaging bag, and the adhesive layer is bonded to the packaging bag to obtain an electric core.

2. Test method

1. Test method for bonding area ratio

Test the width and length of the bonding layer, the width and length of the electrode assembly, and calculate the bonding area ratio a by the following formula:

a=(W1×L1)/(W2×L2)

Wherein W1 is the width of the adhesive layer, L1 is the length of the adhesive layer, W2 is the width of the electrode assembly, and L2 is the length of the electrode assembly.

2. Cohesion test method

Disassemble the battery cell that has been discharged to 2.8V, and keep the bonding interface between the packaging bag and the electrode assembly in good condition. Put the disassembled battery cell in a punching machine and punch it to prepare 4-8mm strips. Paste double-sided tape on the steel plate, stick the electrode assembly surface of the test strip on the double-sided tape and fix it. Fix it with one end of the packaging bag with a cardboard sheet of the same width to obtain the sample to be tested.

Fix one end of the steel plate at the lower end of the universal tensile machine (manufacturer: Yuyao Xuyang New Energy Co., Ltd.), and fix the paper strip on the upper end of the tensile machine at a speed of 50mm/min. After the test is completed, record the average value of the smooth section of the stretch curve. Each group tests 30 samples in parallel.

3. Falling safety test method

Take at least 30 cell samples and make them fall freely from a certain height (such as 1.5 meters). If the battery sample does not emit smoke, does not fire, and does not leak, it is recorded as passed. Record the rate of samples passing the drop safety test.

4. Test method of cyclic capacity retention rate

At 45℃, charge the cell with a constant current of 0.8C to 4.4V, then charge the cell with a constant voltage of 4.4V to 0.2C, let stand for 5 minutes, and then charge the cell with a current of 1C Discharge at a constant current to 3.0V, stand for 5 minutes, record the first discharge capacity, cycle 500 times in the same way (that is, repeat the above steps 500 times), and measure the discharge capacity after the 500th cycle. The cycle capacity retention rate of the battery cell is calculated by the following formula:

Cycle capacity retention ratio=discharge capacity after the 500th cycle/discharge capacity at the first cycle×100%.

Three, test results

Table 1 shows the bonding area ratio and bonding force of the bonding layer in each comparative example and the examples, as well as the drop safety and cycle performance of the battery core.

Table 1 Test results of each comparative example and embodiment

The results show that when the bonding area ratio a of the bonding layer and the bonding force F do not satisfy

When the battery cell falls, the safety of the battery is poor. When the bonding area ratio a of the bonding layer and the bonding force F meet

When the battery cell falls, the safety of the battery is significantly improved. In addition, the bonding area ratio a and the bonding force F of the bonding layer satisfy

On the basis of, when the bonding area ratio a is in the range of 20% to 97%, it will not adversely affect the cycle capacity retention rate of the cell.

References to "embodiments", "parts of embodiments", "one embodiment", "another example", "examples", "specific examples" or "partial examples" throughout the specification mean that At least one embodiment or example in this application includes the specific feature, structure, material, or characteristic described in the embodiment or example. Therefore, descriptions appearing in various places throughout the specification, such as: "in some embodiments", "in embodiments", "in one embodiment", "in another example", "in an example "In", "in a specific example" or "exemplified", which are not necessarily quoting the same embodiment or example in this application. In addition, the specific features, structures, materials, or characteristics herein can be combined in one or more embodiments or examples in any suitable manner.

Although illustrative embodiments have been demonstrated and described, those skilled in the art should understand that the above-mentioned embodiments should not be construed as limiting the present application, and the embodiments can be changed without departing from the spirit, principle, and scope of the present application , Substitution and modification.

Claims

A battery cell, comprising an electrode assembly and a packaging bag accommodating the electrode assembly, characterized in that an adhesive layer is provided between the electrode assembly and the packaging bag, and the adhesive force of the adhesive layer is F It satisfies the following relationship with the bonding area ratio a:
Wherein the bonding area ratio a=(W1×L1)/(W2×L2), where W1 is the width of the bonding layer, L1 is the length of the bonding layer, and W2 is the width of the electrode assembly , And L2 are the length of the electrode assembly, and W1, L1, W2, and L2 have the same unit.
The battery cell according to claim 1, wherein the bonding area ratio a is not less than 20% and not more than 97%.
The battery cell according to claim 1, wherein the adhesive force F is not less than 1 N/m and not more than 150 N/m.
The battery cell according to claim 1, wherein the electrode assembly includes a first pole piece, the first pole piece includes a first current collector, a first active material layer, and a first tab, the first active material The layer is provided on at least a part of the first current collector, and the first active material layer is not provided at the starting end of the first current collector, and wherein the first tab is electrically connected to the first current collector Or the first active material layer is provided with a first groove, and the first tab is arranged in the first groove and is electrically connected to the first current collector.
The battery cell according to claim 1, wherein the electrode assembly includes a first pole piece, the first pole piece includes a first current collector, a first active material layer and at least one first tab, the first The active material layer is arranged on at least a part of the first current collector, the first active material layer is provided with at least one first groove, and the at least one first tab is respectively arranged on the corresponding at least one first In a groove and electrically connected to the first current collector; or the at least one first tab is cut by the first current collector.
The battery cell according to claim 1, wherein the adhesive layer has a single-layer structure or a multi-layer structure.
The battery cell according to claim 1, wherein the adhesive layer is in a sheet, dot or strip shape; or the adhesive layer has a regular morphology, an irregular morphology, or a combination thereof.
The battery cell according to claim 1, wherein the adhesive layer is continuously or discontinuously provided between the electrode assembly and the packaging bag.
An electrochemical device, characterized by comprising the battery cell according to any one of claims 1-8.
An electronic device comprising the electrochemical device according to claim 9.