CN211350883U - Battery cell, electrochemical device comprising same and electronic device - Google Patents

Abstract

An embodiment of the present application provides a battery cell, which includes an electrode assembly and a packaging bag for accommodating the electrode assembly, and an adhesive layer is provided between the electrode assembly and the packaging bag. When the bonding force of the bonding layer and the bonding area ratio satisfy a specific relationship, the battery cell can still maintain a high safety performance after being impacted. In addition, the embodiments of the present application also provide an electrochemical device and an electronic device including the above-mentioned battery cell.

Description

Cell and electrochemical device and electronic device containing the same

technical field

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

Background technique

As electrochemical devices (eg, 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 easily impacted by external forces during use (eg, falling from a high place, etc.), and are easily damaged when subjected to external forces, resulting in safety problems such as liquid leakage, fire, and even explosion.

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

Utility model content

The electrochemical device usually includes a battery cell and a casing for accommodating the battery core, the battery core includes an electrode assembly and a packaging bag for accommodating the electrode assembly, and the electrode assembly is formed by a positive pole piece, a negative pole piece, and a positive pole piece and a The separators between the negative pole pieces are sequentially wound or stacked. 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 hit. If the bonding layer is not set properly, the electrode assembly will be easily separated from the packaging bag after the battery cell is impacted, and its position will change, which will cause safety hazards such as liquid leakage, smoke, fire and even explosion.

The present application solves at least one technical problem described in the background art by providing a specific adhesive layer.

(以各参数的数值来计算)，其中所述粘接面积率a＝(W1×L1)/(W2×L2)，其中W1为所述粘接层的宽度，L1为所述粘接层的长度，W2为所述电极组件的宽度(电极组件可通过卷绕或堆叠而成)，及L2为所述电极组件的长度(或者指所述电极组件的最外圈展开后的宽度，最外圈可以指正极极片、负极极片或隔离膜)，W1、L1、W2和L2具有相同的单位，如mm或cm等。In one aspect, an embodiment of the present application provides a battery cell, including an electrode assembly and a packaging bag for accommodating the electrode assembly, an adhesive layer is provided between the electrode assembly and the packaging bag, and the adhesive layer is The adhesion force F of the layer (unit is N/m) and the adhesion area ratio a satisfy the following relationship:

(calculated by the value of each parameter), wherein the adhesive area ratio a=(W1×L1)/(W2×L2), wherein W1 is the width of the adhesive layer, and L1 is the width of the adhesive 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 refers to the width of the outermost circle of the electrode assembly after unfolding, the outermost Circle can refer to positive pole piece, negative pole piece or separator), W1, L1, W2 and L2 have the same unit, such as mm or cm.

在一些实施例中，所述粘接层的粘接力F与粘接面积率a满足以下关系式：

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

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

When the bonding force and bonding area ratio of the bonding layer in the cell conform to the above relationship, after the cell is hit, there will be a proper frictional force between the electrode assembly and the packaging bag, so that the electrode assembly and the packaging bag are in contact with each other. There will be neither separation nor excessive tearing.

In some embodiments, the positive electrode sheet in the electrode assembly is bonded to the packaging bag. In some embodiments, the negative electrode sheet in the electrode assembly is bonded to the packaging bag. In some embodiments, bonded to the packaging bag is a separator in the electrode assembly.

According to the embodiment of the present application, the bonding area ratio a is not less than 20% and not more than 97%. In some embodiments, the adhesive 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 battery cells, and thus will not affect the circulation of the battery cells. any adverse effect on performance.

According to the 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 provided at the on at least a part of the first current collector, and the first active material layer is not disposed 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 the first An active material layer is provided with a first groove, and the first tab is disposed 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 pole tab, the first active material layer is provided with at least one first groove, and the plurality of first pole 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 from the first current collector.

According to an embodiment of the present application, the electrode assembly includes a second pole piece having substantially the same arrangement 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 portion of the second current collector, and The starting end of the second current collector is not provided with the second active material layer, 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 disposed 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 pole tab, the first active material layer is provided with at least one second groove, and the plurality of second pole tabs are respectively disposed in 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 from the second current collector.

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

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

According to an embodiment of the present application, the adhesive layer is continuously or discontinuously disposed 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 shape, an irregular shape or a combination thereof.

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

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

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

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

Description of drawings

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

FIG. 1 shows a schematic diagram of a pole piece of an outermost ring of an electrode assembly according to an embodiment of the present application after being unfolded.

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

FIG. 2B shows a schematic diagram of an electrode assembly with multiple sheet-area adhesive layers according to an embodiment of the present application.

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

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

FIG. 2E shows a schematic diagram of an electrode assembly having a plurality of strip area adhesive 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 an 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 an electrode assembly including the first pole piece shown in FIG. 5 .

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

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

Detailed ways

Embodiments of the present application will be described in detail below. Throughout the specification of the present application, the same or similar components and components having the same or similar functions are denoted by similar reference numerals. The embodiments described herein with respect to the figures are illustrative, diagrammatic, and intended to provide a basic understanding of the present application. The embodiments of the present application should not be construed as limitations of the present application.

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

所述粘接面积率a＝(W1×L1)/(W2×L2)，其中W1为所述粘接层的宽度，L1为所述粘接层的长度，W2为所述电极组件的宽度，其中电极组件可通过正极极片、隔离膜和负极极片依序卷绕或堆叠而成，及L2为所述电极组件的长度，或者L2指所述电极组件的最外圈展开后的宽度，最外圈可以指正极极片(可如图1所示)、负极极片或隔离膜。An embodiment of the present application provides a battery cell, including an electrode assembly and a packaging bag for accommodating the electrode assembly, an adhesive layer is provided between the electrode assembly and the packaging bag, and the adhesive layer is bonded The force F and the bonding area ratio a satisfy the following relationship:

The adhesive area ratio 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, Wherein the electrode assembly can be formed by sequentially winding or stacking the positive pole piece, the separator and the negative pole piece, and L2 is the length of the electrode assembly, or L2 refers to the width of the outermost circle of the electrode assembly after unfolding, The outermost ring may refer to the positive pole piece (as shown in Figure 1), the negative pole piece or the separator.

在一些实施例中，所述粘接层的粘接力F与粘接面积率a满足以下关系式：

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

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

When the bonding force and bonding area ratio of the bonding layer in the cell conform to the above relationship, after the cell is impacted, there will be an appropriate frictional force between the electrode assembly and the packaging bag, so that the electrode assembly and the packaging bag are in contact with each other. There will be neither separation nor excessive tearing.

In some embodiments, the adhesive layer is in the form of sheets, dots or strips.

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 The ratio between the surface areas of the electrode assembly on one side of the junction layer. As shown in FIG. 2A , when the adhesive layer has one sheet-like adhesive layer, a=(W1×L1)/(W2×L2). As shown in FIG. 2B, when the adhesive layer includes a plurality of sheet-like adhesive layers (a, b, c, d, and e), the adhesive area is equal to that of the sheet-like 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 in the form of dots, the adhesive area ratio is the ratio between the area surrounded by the outermost adhesive material dots 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 point-shaped adhesive layers, a=(W1×L1)/(W2×L2).

When the adhesive layer is strip-shaped, 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 adhesive layer includes a plurality of strip adhesive layers (x and y), the adhesive area is the sum of the strip adhesive layers x and y, a=(W1x×L1x+W1y×L1y )/(W2×L2).

In some embodiments, the positive electrode sheet in the electrode assembly is bonded to the packaging bag. In some embodiments, the negative electrode sheet in the electrode assembly is bonded to the packaging bag. In some embodiments, bonded to the packaging bag is a separator in the electrode assembly.

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

In some embodiments, the adhesive layer is continuously disposed between the cell and the outer shell, 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 Figures 2B, 2C and 2E.

In some embodiments, the adhesive layer has a regular topography (as shown in FIG. 2E ), an irregular topography (as shown in FIG. 2D ), or a combination thereof. The term "regular topography" is a regular topography of the boundaries of the adhesive layer, eg, squares, rectangles, diamonds, circles, ovals, triangles, trapezoids, polygons, and the like. The term "irregular topography" refers to topography that has no regularity at the boundaries of the adhesive layer, ie, topography that differs from regular topography, eg, those topography that cannot be named in conventional shape terms.

In some embodiments, the adhesive area ratio a of the adhesive layer is not less than 20% and not more than 97%. In some embodiments, the adhesive 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 can be easily packaged in a packaging bag, and the surface of the bonding layer is smooth, which will not affect the interface of the cell, and thus will not affect the cycle performance of the cell. produce 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 cell 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 layer is disposed on the On at least a portion of the first current collector, as shown in FIG. 3 and FIG. 4 .

In some embodiments, the first active material layer is not disposed 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 FIG. 3 and FIG. 4 . shown.

FIG. 3 illustrates 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 tabs 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 , that is, the 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 arrangement. FIG. 4 shows an electrode assembly formed by sequentially winding the first pole piece 300 , the separator 320 and the second pole piece 310 shown in FIG. 3 , wherein W2 is the wound width of the electrode assembly.

In some embodiments, the first active material layer is provided with a first groove, the first tab is disposed 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 illustrates 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 , intermediate portions 505 a , 505 b and ending ends 506 a , 506 b along the winding direction, and the first active material 502 is disposed in the intermediate portions 505 a , 505 b of the first current collector 501 . The middle portions 505a and 505b of the first current collector 501 provided with the first active material 502 are provided with grooves 508 . 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 , that is, the 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 adopt substantially the same arrangement. FIG. 6 shows an electrode assembly formed by winding the first pole piece 500 , the separator 520 and the second pole piece 510 shown in FIG. 5 , wherein W2 is the wound width of the electrode assembly.

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

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

Figure 7 illustrates a first pole piece according to yet 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 disposed in the coated regions 705a, 705b of the first current collector 701. The first tab 703 is cut from the first current collector 701 . As shown in FIG. 7, the middle portion 705a on which the first active material 702 is provided on the first surface 700b is longer than the middle portion 705b on which the first active material 702 is provided 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 only on 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 arrangement. FIG. 8 shows an electrode assembly formed by winding the first pole piece 700 , the separator 720 and the second pole piece 710 shown in FIG. 7 , wherein W2 is the width of the electrode assembly after winding.

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

The embodiments of the present application also provide an electrochemical device including the battery cell according to any one of the embodiments of the present application. The electrochemical device of the embodiments of the present application includes any device in which an electrochemical reaction occurs, 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.

Embodiments of the present application further provide an electronic device including the electrochemical device according to any one of the embodiments of the present application. The electrochemical device of the present application includes any device in which an electrochemical reaction occurs, 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 devices of the embodiments of the present application include a positive electrode sheet having a positive electrode active material capable of inserting and extracting metal ions, a negative electrode sheet according to an embodiment of the present application, an electrolyte, and a cathode electrode disposed on the positive electrode. The separator between the sheet and the negative pole piece.

The preparation of the flexible package will be described below by taking a lithium-ion battery as an example and in conjunction with specific embodiments. Those skilled in the art will understand that the preparation method described in this application is only an example, and any other suitable preparation method is within the scope of this application. Inside.

Example

1. Preparation of batteries

The positive pole piece, the separator and the negative pole piece are placed in sequence and rolled 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 a packaging bag, and the adhesive layer is bonded to the packaging bag to obtain an electric core.

2. Test method

1. Test method of 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. Adhesion test method

Disassemble the cells that have been discharged to 2.8V to keep the bonding interface between the packaging bag and the electrode assembly in good condition. Put the disassembled cells into the punching machine, and punch them to prepare 4-8mm strips. Stick double-sided tape on the steel plate, and fix the electrode assembly surface of the test strip on the double-sided tape. Use a cardboard piece of the same width to fix one end of the packaging bag to obtain the sample to be tested.

One end of the steel plate is fixed to the lower end of the universal tensile machine (manufacturer: Yuyao Xuyang New Energy Co., Ltd.), and the paper strip is reversely pulled 180° and fixed to the upper end of the tensile machine for testing at a speed of 50mm/min. After the test is completed, the average value of the plateau of the tensile curve is recorded. 30 samples were tested in parallel for each group.

3. Drop safety test method

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

4. Test method of cycle capacity retention rate

At 45°C, 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 it stand for 5 minutes, and then charge the cell with a current of 1C. Constant current discharge to 3.0V, stand for 5min, record the first discharge capacity, cycle 500 times in the same way (that is, repeat the above steps 500 times), measure the discharge capacity after the 500th cycle. The cycle capacity retention rate of the cell is calculated by the following formula:

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

3. Test results

Table 1 shows the bonding area ratio and bonding force of the bonding layer and the drop safety and cycle performance of the battery cells in each of the comparative examples and examples.

The test results of each comparative example and embodiment of table 1

时，电芯的跌落安全性较差。当粘接层的粘接面积率a与粘接力F满足

时，电芯的跌落安全性得到显著改善。此外，在粘接层的粘接面积率a与粘接力F满足

的基础上，当粘接面积率a在20％至97％的范围内时，不会对电芯的循环容量保持率产生不利影响。The results show that when the bonding area ratio a of the bonding layer and the bonding force F are not satisfied

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

, the drop safety of the cell is significantly improved. In addition, the adhesive area ratio a and the adhesive force F of the adhesive layer satisfy

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

Reference throughout the specification to "an embodiment," "part of an embodiment," "one embodiment," "another example," "example," "specific example," or "partial example" means that At least one embodiment or example in this application incorporates a particular feature, structure, material or characteristic described in the embodiment or example. Thus, descriptions such as: "in some embodiments", "in an embodiment", "in one embodiment", "in another example", "in an example", appearing in various places throughout the specification "in", "in a particular example" or "by way of example", which are not necessarily referring to the same embodiment or example in this application. Furthermore, the particular features, structures, materials or characteristics herein may be combined in any suitable manner in one or more embodiments or examples.

Although illustrative embodiments have been shown and described, it should be understood by those skilled in the art that the above-described embodiments are not to be construed as limitations of the application, and changes may be made in the embodiments without departing from the spirit, principles and scope of the application , alternatives and modifications.

Claims (10)

1. An electric core, comprising an electrode assembly and a packaging bag for accommodating the electrode assembly, characterized in that an adhesive layer is provided between the electrode assembly and the packaging bag, and the adhesive layer of the adhesive layer is 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, and W2 is the width of the electrode assembly , and L2 is the length of the electrode assembly, W1, L1, W2 and L2 have the same unit. 2. The cell according to claim 1, wherein the bonding area ratio a is not less than 20% and not more than 97%. 3. The cell according to claim 1, wherein the adhesive force F is not less than 1 N/m and not more than 150 N/m. 4. The cell of 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 pole piece an active material layer is disposed on at least a portion of the first current collector, and the first active material layer is not disposed at the beginning of the first current collector, and wherein the first tab is electrically connected to the first current collector The starting end of the current collector; or the first active material layer is provided with a first groove, and the first tab is disposed in the first groove and is electrically connected to the first current collector. 5. The cell of claim 1, wherein the electrode assembly includes a first pole piece including a first current collector, a first active material layer, and at least one first tab, the first pole piece The first active material layer is disposed 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 disposed in the corresponding at least one A first groove is electrically connected to the first current collector; or the at least one first tab is cut from the first current collector. 6. The cell according to claim 1, wherein the adhesive layer has a single-layer structure or a multi-layer structure. 7 . The battery core according to claim 1 , wherein the adhesive layer is in a sheet shape, a dot shape or a strip shape; or the adhesive layer has a regular shape, an irregular shape or a combination thereof. 8 . 8 . The battery cell of claim 1 , wherein the adhesive layer is continuously or discontinuously disposed between the electrode assembly and the packaging bag. 9 . 9 . An electrochemical device, characterized in that , comprising the battery cell according to any one of claims 1 to 8 . 10 . 10. An electronic device comprising the electrochemical device of claim 9.

Images