Battery cell and electrical device

Abstract

A battery cell (10) and an electrical device. The battery cell (10) comprises a housing (100) and an electrode assembly (200), the electrode assembly (200) being accommodated in the housing (100), and the housing (100) comprising a first end wall (110) and a second end wall (120) arranged opposite to each other in the thickness direction (X) of the electrode assembly (200); the electrode assembly (200) comprises a first positive electrode sheet (210), a first negative electrode sheet (220) and a first separator (230), the first negative electrode sheet (220) being bonded to the first end wall (110) by means of a first bonding layer (310), the first positive electrode sheet (210) being located on the side of the first negative electrode sheet (220) facing away from the first end wall (110), and the first separator (230) being arranged between the first positive electrode sheet (210) and the first negative electrode sheet (220). The bonding force of the first bonding layer (310) is F1, where F1≥10 N / m; the bonding force between the first negative electrode sheet (220) and the first separator (230) is F2, and the bonding force between the first positive electrode sheet (210) and the first separator (230) is F3, where F2<F3. When the battery cell (10) is stressed, the housing (100) is less likely to crack, and the electrode assembly (200) is less likely to tear, such that the battery cell (10) is less likely to fail under stress.

Description

Battery cell and electric device Cross-reference to related applications

[0001] This application claims priority to Chinese Patent Application CN202411073604.9 entitled "Battery cell and electric device" filed on August 6, 2024, the entire contents of which are incorporated herein by reference. TECHNICAL FIELD

[0002] The present application relates to the technical field of batteries, in particular to a battery cell and an electric device. BACKGROUND

[0003] With the rapid development of new energy technology, batteries have been widely used in electronic devices, electric vehicles, electric two-wheel vehicles, electric tools and other fields. The requirements for the quality, safety and miniaturization of batteries are also increasingly high.

[0004] The electrode assembly in the steel shell battery cell is generally bonded to the shell by adhesive tape. If the adhesive force of the adhesive tape is large, when the steel shell battery cell is subjected to force, the impulse of the external force transmitted to the electrode assembly through the adhesive tape is large, and the electrode assembly is easy to tear. If the adhesive force of the adhesive tape is small, the impulse of the external force transmitted to the electrode assembly through the adhesive tape is small, and the shell is easy to crack. The above two failure modes are difficult to balance, resulting in a high possibility of failure of the steel shell battery cell when subjected to force. SUMMARY

[0005] The present application provides a battery cell and an electric device, which can reduce the possibility of failure of the battery cell under stress.

[0006] In a first aspect, the present application provides a battery cell, which includes a shell and an electrode assembly, the electrode assembly is accommodated in the shell, the shell includes a first end wall and a second end wall which are oppositely arranged along the thickness direction of the electrode assembly; the electrode assembly includes a first positive electrode tab, a first negative electrode tab and a first separator, the first negative electrode tab is bonded to the first end wall through a first bonding layer, the first positive electrode tab is located on the side of the first negative electrode tab away from the first end wall, and the first separator is arranged between the first positive electrode tab and the first negative electrode tab; wherein the adhesive force of the first bonding layer is F1, which satisfies F1≥10N / m; the adhesive force between the first negative electrode tab and the first separator is F2, and the adhesive force between the first positive electrode tab and the first separator is F3, which satisfies F2<F3.

[0007] In the technical solution, the battery cell includes a shell and an electrode assembly, and the electrode assembly is accommodated in the shell, so that the shell can protect the electrode assembly; by setting the bonding force F1 of the first bonding layer between the first negative electrode tab and the first end wall to be greater than or equal to 10 N / m, the bonding force between the electrode assembly and the first end wall can be greater, and an external force can be transmitted to the electrode assembly through the first bonding layer to absorb more impulse, so that the impulse of the external force of the battery cell transmitted to the electrode assembly through the first bonding layer is greater, and the possibility of cracking of the shell is smaller; by setting the bonding force F2 between the first negative electrode tab and the first separator and the bonding force F3 between the first positive electrode tab and the first separator to satisfy F2 < F3, the bonding force between the first negative electrode tab and the first separator is smaller, and the impulse transmitted to the first positive electrode tab can be reduced; since the thickness of the negative electrode tab is generally greater than the thickness of the positive electrode tab, the negative electrode tab is less likely to tear than the positive electrode tab when the battery cell is stressed, and therefore, by arranging the first negative electrode tab at the outermost side of the electrode assembly and transmitting more impulse of the external force to the first negative electrode tab and less impulse to the first positive electrode tab and other electrode tabs, the electrode tabs of the electrode assembly are less likely to tear, the possibility of tearing of the electrode assembly is reduced, the possibility of stress failure of the battery cell is lower, and the service life of the battery cell is prolonged. Therefore, in the above technical solution, the problem of tearing of the electrode tab and stress failure of the battery cell can be avoided while ensuring a large bonding force.

[0008] In some embodiments of the present application, F3-F2≥5 N / m.

[0009] In the technical solution, by setting F3-F2≥5 N / m, the first negative electrode tab and the first separator can be separated more uniformly, so that the impulse transmitted to the first positive electrode tab is further reduced, the possibility of tearing of the electrode assembly is further reduced, the possibility of stress failure of the battery cell is lower, and the service life of the battery cell is prolonged.

[0010] In some embodiments of the present application, 10 N / m≤F2≤95 N / m, and 15 N / m≤F3≤100 N / m.

[0011] In the technical solution, when F2 is greater than or equal to 10 N / m, the first negative electrode tab is less likely to be separated from the first diaphragm, so that the shell is less likely to be cracked by an excessive impulse, and other electrode tabs except the first negative electrode tab are less likely to be damaged or even short-circuited by colliding with the shell; when F2 is less than or equal to 95 N / m, the impulse transmitted to the first positive electrode tab by the external force is less, so that the possibility of the electrode assembly being torn is further reduced; therefore, when 10 N / m≤F2≤95 N / m, the first negative electrode tab is less likely to be separated from the first diaphragm, so that the shell is less likely to be cracked by an excessive impulse, and other electrode tabs except the first negative electrode tab are less likely to be damaged or even short-circuited by colliding with the shell, and the impulse transmitted to the first positive electrode tab by the external force is less, so that the possibility of the electrode assembly being torn is further reduced.

[0012] When F3 is greater than or equal to 15 N / m, the first diaphragm is less likely to be separated from the first positive electrode tab, so that the shell is less likely to be cracked by an excessive impulse, and other electrode tabs except the first negative electrode tab are less likely to be damaged or even short-circuited by colliding with the shell; when F3 is less than or equal to 100 N / m, the impulse transmitted to the first positive electrode tab by the external force is less, so that the possibility of the electrode assembly being torn is reduced; therefore, when 15 N / m≤F3≤100 N / m, the first diaphragm is less likely to be separated from the first positive electrode tab, so that the shell is less likely to be cracked by an excessive impulse, and other electrode tabs except the first negative electrode tab are less likely to be damaged or even short-circuited by colliding with the shell, and the impulse transmitted to the first positive electrode tab by the external force is less, so that the possibility of the electrode assembly being torn is reduced.

[0013] In some embodiments of the present application, the first negative electrode tab comprises a negative current collector and a negative active material layer, the negative active material layer is arranged on a side of the negative current collector facing the first positive electrode tab, and a groove is arranged on a side of the negative active material layer facing the first diaphragm.

[0014] In the technical solution, by arranging the negative active material layer on the side of the negative current collector facing the first positive electrode tab and arranging the groove on the side of the negative active material layer facing the first diaphragm, the bonding area of the negative active material layer and the first diaphragm is small, so that the bonding force between the negative active material layer and the first diaphragm is small, the impulse transmitted to the first positive electrode tab is reduced, and the possibility of the electrode assembly being torn is reduced, so that the possibility of the battery cell being stressed to failure is low, which is beneficial to prolonging the service life of the battery cell.

[0015] In some embodiments of the present application, the projected area of the groove in the thickness direction of the first negative electrode tab is S1, and the projected area of the negative electrode active material layer in the thickness direction of the first negative electrode tab is S2, and 5%≤S1 / S2≤35% is satisfied.

[0016] In the above technical solution, when S1 / S2 is greater than or equal to 5%, the bonding area of the negative electrode active material layer and the first separator can be small, so that the bonding force between the negative electrode active material layer and the first separator is small, which can reduce the impulse transmitted to the first positive electrode tab, thereby reducing the possibility of tearing of the electrode assembly; when S1 / S2 is less than or equal to 35%, the bonding area of the negative electrode active material layer and the first separator can be large, so that the bonding force between the negative electrode active material layer and the first separator is large, which can make the possibility of the first negative electrode tab being separated from the first separator small, thereby reducing the possibility of the shell being cracked by receiving too much impulse, and reducing the possibility of other electrode tabs except the first negative electrode tab being damaged or even short-circuited by colliding with the shell; therefore, when 5%≤S1 / S2≤35%, both the impulse transmitted to the first positive electrode tab can be reduced, thereby reducing the possibility of tearing of the electrode assembly, and the possibility of the first negative electrode tab being separated from the first separator can be small, thereby reducing the possibility of the shell being cracked by receiving too much impulse, and reducing the possibility of other electrode tabs except the first negative electrode tab being damaged or even short-circuited by colliding with the shell.

[0017] In some embodiments of the present application, the groove extends along the first direction, the width of the groove along the second direction is W1, and the width of the negative electrode active material layer along the second direction is W2, and 5%≤W1 / W2≤35% is satisfied; the thickness direction of the electrode assembly, the first direction, and the second direction are perpendicular to each other.

[0018] In the technical solution, when W1 / W2 is greater than or equal to 5%, the bonding area of the negative active material layer and the first separator is small, so that the bonding force between the negative active material layer and the first separator is small, the impulse transmitted to the first positive electrode sheet can be reduced, and the possibility of tearing of the electrode assembly can be reduced; when W1 / W2 is less than or equal to 35%, the bonding area of the negative active material layer and the first separator is large, so that the bonding force between the negative active material layer and the first separator is large, the possibility of the first negative electrode sheet being separated from the first separator is small, the possibility of the shell being cracked due to receiving an excessive impulse is small, the possibility of other electrode sheets except the first negative electrode sheet being damaged or even short-circuited due to colliding with the shell is small, and the possibility of the first separator being bonded to the side wall of the groove by extending into the groove is reduced; therefore, when 5%≤W1 / W2≤35%, the impulse transmitted to the first positive electrode sheet can be reduced, the possibility of tearing of the electrode assembly can be reduced, the possibility of the first negative electrode sheet being separated from the first separator is small, the possibility of the shell being cracked due to receiving an excessive impulse is small, the possibility of other electrode sheets except the first negative electrode sheet being damaged or even short-circuited due to colliding with the shell is small, and the possibility of the first separator being bonded to the side wall of the groove by extending into the groove is reduced.

[0019] In some embodiments of the present application, the first positive electrode sheet comprises a positive current collector, a first positive active material layer and a second positive active material layer, the first positive active material layer is arranged on one side of the positive current collector facing the first negative electrode sheet, and the second positive active material layer is arranged on the other side of the positive current collector facing away from the first negative electrode sheet; the side of the first positive active material layer facing the first separator is arranged in a plane.

[0020] In the technical solution, by arranging the side of the first positive active material layer facing the first separator in a plane, the bonding area of the first positive active material layer and the first separator is large, so that the bonding force between the first positive active material layer and the first separator is large, the possibility of the first negative electrode sheet, the first separator being separated from the first positive electrode sheet is small, the possibility of the shell being cracked due to receiving an excessive impulse is small, and the possibility of other electrode sheets except the first negative electrode sheet being damaged or even short-circuited due to colliding with the shell is small.

[0021] In some embodiments of the present application, the first negative electrode sheet comprises a negative current collector and a negative active material layer, the negative active material layer is arranged on one side of the negative current collector facing the first positive electrode sheet, and the negative active material layer comprises a first adhesive, the content of the first adhesive in the negative active material layer is 0.3% to 0.8%.

[0022] In the technical solution, when the content of the first binder in the negative active material layer is greater than or equal to 0.3%, the adhesion between the negative active material layer and the first separator is relatively large, the possibility of the first negative electrode sheet being separated from the first separator is relatively small, the possibility of the shell being cracked due to receiving too much impulse is relatively small, and the possibility of other electrode sheets except the first negative electrode sheet being damaged or even short-circuited due to colliding with the shell is relatively small; when the content of the first binder in the negative active material layer is less than or equal to 0.8%, the adhesion between the negative active material layer and the first separator is relatively small, and the impulse transmitted to the first positive electrode sheet is reduced. Generally, the thickness of the negative electrode sheet is greater than that of the positive electrode sheet, so when the battery cell is stressed, the negative electrode sheet is less likely to be torn than the positive electrode sheet. Therefore, by arranging the first negative electrode sheet at the outermost side of the electrode assembly and transmitting more impulse of the external force to the first negative electrode sheet and less impulse to the first positive electrode sheet and other electrode sheets, the electrode assembly is less likely to be torn, thereby reducing the possibility of the electrode assembly being torn.

[0023] In some embodiments of the present application, the first positive electrode sheet comprises a positive current collector, a first positive active material layer and a second positive active material layer, the first positive active material layer is arranged on one side of the positive current collector facing the first negative electrode sheet, and the second positive active material layer is arranged on the other side of the positive current collector away from the first negative electrode sheet; the first positive active material layer comprises a second binder, and the content of the second binder in the first positive active material layer is 0.8% to 2%.

[0024] In the technical solution, when the content of the second adhesive in the first positive active material layer is greater than or equal to 0.8%, the adhesion between the first positive active material layer and the first separator is relatively large, the possibility of the first positive electrode sheet being separated from the first separator is relatively small, and the possibility of other electrode sheets except the first negative electrode sheet being damaged or even short-circuited by colliding with the shell is relatively small; when the content of the second adhesive in the first positive active material layer is less than or equal to 2%, the adhesion between the first positive active material layer and the first separator is relatively small, the impulse transmitted to the first positive electrode sheet can be reduced, and thus the possibility of the electrode assembly being torn can be reduced; therefore, when the content of the second adhesive in the first positive active material layer is 0.8% to 2%, the possibility of the first positive electrode sheet being separated from the first separator is relatively small, the possibility of other electrode sheets except the first negative electrode sheet being damaged or even short-circuited by colliding with the shell is relatively small, and the impulse transmitted to the first positive electrode sheet can be reduced, and thus the possibility of the electrode assembly being torn can be reduced.

[0025] In some embodiments of the present application, the first separator comprises a base layer, a second adhesive layer and a third adhesive layer, the second adhesive layer is arranged on one side of the base layer facing the first negative electrode sheet, the third adhesive layer is arranged on one side of the base layer facing the first positive electrode sheet, the second adhesive layer comprises a third adhesive, the content of the third adhesive in the second adhesive layer is a, the third adhesive layer comprises a fourth adhesive, the content of the fourth adhesive in the third adhesive layer is b, and a < b is satisfied.

[0026] In the technical solution, by satisfying a < b, the adhesion between the first separator and the first negative electrode sheet is smaller than the adhesion between the first separator and the first positive electrode sheet, the impulse transmitted to the first positive electrode sheet can be reduced, and thus the possibility of the electrode assembly being torn can be reduced, and the possibility of the battery cell being stressed to failure is relatively low, which is beneficial to prolonging the service life of the battery cell.

[0027] In some embodiments of the present application, 45% ≤ a ≤ 85%.

[0028] In the technical solution, when a is greater than or equal to 45%, the adhesion between the first diaphragm and the first negative pole piece is relatively large, so that the first negative pole piece is less likely to be separated from the first diaphragm, thereby reducing the possibility that the shell is cracked due to receiving an excessive impulse, and reducing the possibility that other pole pieces except the first negative pole piece are damaged or even short-circuited due to colliding with the shell; when a is less than or equal to 85%, the adhesion between the first diaphragm and the first negative pole piece is relatively small, so that the impulse transmitted to the first positive pole piece by the external force is relatively small, thereby reducing the possibility that the electrode assembly is torn; therefore, when 45%≤a≤85%, the first negative pole piece is less likely to be separated from the first diaphragm, thereby reducing the possibility that the shell is cracked due to receiving an excessive impulse, and reducing the possibility that other pole pieces except the first negative pole piece are damaged or even short-circuited due to colliding with the shell, and the impulse transmitted to the first positive pole piece by the external force is relatively small, thereby reducing the possibility that the electrode assembly is torn.

[0029] In some embodiments of the present application, the first diaphragm comprises a base layer, a second adhesive layer and a third adhesive layer, the second adhesive layer is arranged on one side of the base layer facing the first negative pole piece, and the third adhesive layer is arranged on one side of the base layer facing the first positive pole piece, the second adhesive layer comprises a first ceramic material, the content of the first ceramic material in the second adhesive layer is c, the third adhesive layer comprises a second ceramic material, the content of the second ceramic material in the third adhesive layer is d, and c>d is satisfied.

[0030] In the technical solution, by satisfying c>d, the adhesion between the first diaphragm and the first negative pole piece is less than the adhesion between the first diaphragm and the first positive pole piece, the impulse transmitted to the first positive pole piece is reduced, thereby reducing the possibility that the electrode assembly is torn, and reducing the possibility that the battery cell is stressed to failure, which is beneficial to prolonging the service life of the battery cell.

[0031] In some embodiments of the present application, 10%≤c≤50%.

[0032] In the technical solution, when c is greater than or equal to 10%, the adhesion between the first diaphragm and the first negative electrode tab is small, so that the impulse of the external force transmitted to the first positive electrode tab is small, thereby reducing the possibility of tearing of the electrode assembly; when c is less than or equal to 50%, the adhesion between the first diaphragm and the first negative electrode tab is large, so that the possibility of the first negative electrode tab being separated from the first diaphragm is small, thereby reducing the possibility of the shell being cracked due to too large impulse, and reducing the possibility of other electrode tabs except the first negative electrode tab being damaged or even short-circuited due to collision with the shell; therefore, when 10%≤c≤50%, the impulse of the external force transmitted to the first positive electrode tab is small, thereby reducing the possibility of tearing of the electrode assembly, and the possibility of the first negative electrode tab being separated from the first diaphragm is small, thereby reducing the possibility of the shell being cracked due to too large impulse, and reducing the possibility of other electrode tabs except the first negative electrode tab being damaged or even short-circuited due to collision with the shell.

[0033] In some embodiments of the present application, the electrode assembly further comprises a second positive electrode tab, a second negative electrode tab and a second diaphragm, the second negative electrode tab is adhered to the second end wall through a fourth adhesive layer, the second positive electrode tab is located on the side of the second negative electrode tab away from the second end wall, and the second diaphragm is arranged between the second positive electrode tab and the second negative electrode tab; wherein the adhesion of the fourth adhesive layer is F4, and F4≥10N / m is satisfied; the adhesion between the second negative electrode tab and the second diaphragm is F5, and the adhesion between the second positive electrode tab and the second diaphragm is F6, and F5<F6 is satisfied.

[0034] In the technical solution, by making the adhesion F4 of the fourth adhesive layer between the second negative electrode tab and the second end wall be greater than or equal to 10N / m, the adhesion between the electrode assembly and the second end wall is large, the impulse of the external force received by the battery cell and transmitted to the electrode assembly through the fourth adhesive layer is large, and the possibility of the shell being cracked is small; by making the adhesion F5 between the second negative electrode tab and the second diaphragm and the adhesion F6 between the second positive electrode tab and the second diaphragm satisfy F5<F6, the adhesion between the second negative electrode tab and the second diaphragm is small, which can reduce the impulse transmitted to the second positive electrode tab, thereby reducing the possibility of tearing of the electrode assembly and reducing the possibility of stress failure of the battery cell, which is beneficial to prolonging the service life of the battery cell.

[0035] In some embodiments of the present application, the shell further comprises a side wall, the side wall is arranged around the first end wall, and the side wall connects the first end wall and the second end wall; the electrode assembly comprises a plurality of side surfaces connected in a head-to-tail manner, a fifth adhesive layer is arranged between at least one side surface and the side wall, and the electrode assembly is adhered to the side wall through the fifth adhesive layer.

[0036] In the technical solution, the fifth adhesive layer is arranged between the at least one side surface of the electrode assembly and the side wall of the shell, so that the electrode assembly is adhered to the side wall through the fifth adhesive layer, the possibility of collision and damage or short circuit of the electrode assembly caused by displacement of the electrode assembly relative to the shell can be further reduced, the assembly of the electrode assembly and the shell can be facilitated, and the fifth adhesive layer can absorb part of the impulse when the battery cell is stressed, so that the adhesive force range of the first adhesive layer is larger.

[0037] In some embodiments of the present application, the adhesive force of the fifth adhesive layer is F7, and F7≥50 N / m is satisfied.

[0038] In the technical solution, the adhesive force between the electrode assembly and the side wall of the shell is high when the adhesive force F7 of the fifth adhesive layer satisfies F7≥50 N / m, and the possibility of collision and damage or short circuit of the electrode assembly caused by displacement of the electrode assembly relative to the shell can be further reduced.

[0039] In some embodiments of the present application, the ratio of the length of each fifth adhesive layer to the length of the side surface on which the fifth adhesive layer is located is between 40% and 80%.

[0040] In the technical solution, when the ratio of the length of each fifth adhesive layer to the length of the side surface on which the fifth adhesive layer is located is greater than or equal to 40%, the adhesive area between the electrode assembly and the side wall of the shell is large, the adhesive force between the electrode assembly and the side wall of the shell is high, and the possibility of collision and damage or short circuit of the electrode assembly caused by displacement of the electrode assembly relative to the shell can be further reduced; when the ratio of the length of each fifth adhesive layer to the length of the side surface on which the fifth adhesive layer is located is less than or equal to 80%, the influence on electrolyte permeation can be reduced, and the possibility of winding of the fifth adhesive layer to cause low process yield of the battery cell can be reduced; therefore, when the ratio of the length of each fifth adhesive layer to the length of the side surface on which the fifth adhesive layer is located is between 40% and 80%, the possibility of collision and damage or short circuit of the electrode assembly caused by displacement of the electrode assembly relative to the shell can be further reduced, the influence on electrolyte permeation can be reduced, and the possibility of winding of the fifth adhesive layer to cause low process yield of the battery cell can be reduced.

[0041] In some embodiments of the present application, the shell is a hard shell.

[0042] In the technical solution, the shell is a hard shell, so that external force does not directly act on the electrode assembly, and the protection of the shell on the electrode assembly is better.

[0043] In some embodiments of the present application, the electrode assembly is a laminated structure.

[0044] In a second aspect, the embodiments of the present application provide a power-using device, comprising the battery cell as described above, and the battery cell is configured to provide electric energy. BRIEF DESCRIPTION OF DRAWINGS

[0045] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiments will be briefly introduced as follows. It should be understood that the following drawings only show some of the embodiments of the present application, and therefore should not be considered as a limitation on the scope. Other related drawings can also be obtained by those of ordinary skill in the art based on these drawings.

[0046] FIG. 1 is a schematic diagram of a cross-sectional structure of a battery cell according to some embodiments of the present application;

[0047] FIG. 2 is a schematic diagram of a cross-sectional structure of a battery cell according to some other embodiments of the present application;

[0048] FIG. 3 is a schematic diagram of a structure of a first separator of a battery cell according to some other embodiments of the present application;

[0049] FIG. 4 is a schematic diagram of a cross-sectional structure of a first separator of a battery cell according to some embodiments of the present application;

[0050] FIG. 5 is a schematic diagram of a cross-sectional structure of a battery cell according to some embodiments of the present application from another perspective;

[0051] FIG. 6 is a schematic diagram of a cross-sectional structure of a battery cell according to some other embodiments of the present application.

[0052] FIG. 1 is a schematic diagram of a cross-sectional structure of a battery cell according to some embodiments of the present application; DETAILED DESCRIPTION

[0053] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions in the embodiments of the present application will be clearly described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art belong to the scope of protection of the present application.

[0054] Unless otherwise defined, all technical and scientific terms used in the present application have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs; the terms used in the specification of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application; the terms "include" and "have" and any variations thereof in the specification and claims of the present application and the above description of drawings are intended to cover non-exclusive inclusion.

[0055] The terms "first", "second", and the like in the specification and claims of the present application or the above description of drawings are used to distinguish different objects, rather than to describe a specific order or primary and secondary relationship.

[0056] In the present application, referring to "embodiments" means that the specific features, structures or characteristics described in connection with the embodiments can be included in at least one embodiment of the present application. The appearance of this phrase at various places in the specification does not necessarily mean the same embodiment, nor is it an independent or alternative embodiment to other embodiments.

[0057] In the embodiments of the present application, the same reference signs represent the same components, and for brevity, detailed description of the same components is omitted in different embodiments. It should be understood that the thickness, length, width and other dimensions of various components in the embodiments of the present application shown in the drawings, as well as the overall thickness, length, width and other dimensions of the integrated device, are only exemplary and should not constitute any limitation on the present application.

[0058] With the development of the new energy industry, batteries gradually develop towards high energy density and high power density. When the battery cell is subjected to external force, the shell and the electrode assembly of the battery cell are more likely to be damaged and fail. The electrode assembly in the steel shell battery cell is generally bonded to the shell by adhesive paper. If the adhesive force of the adhesive paper is large, when the steel shell battery cell is subjected to force, the impulse of the external force transmitted to the electrode assembly through the adhesive paper is large, and the shell is not easy to crack, but the electrode assembly is easy to tear. If the adhesive force of the adhesive paper is small, the impulse of the external force transmitted to the electrode assembly through the adhesive paper is small, and the electrode assembly is not easy to tear, but the shell is easy to crack. The above two failure modes are difficult to balance, resulting in a high possibility of failure of the steel shell battery cell when subjected to force.

[0059] In order to reduce the possibility of stress failure of the battery cell, the battery cell provided by the application includes a shell and an electrode assembly, the electrode assembly is accommodated in the shell, the shell includes a first end wall and a second end wall arranged oppositely along the thickness direction of the electrode assembly; the electrode assembly includes a first positive electrode sheet, a first negative electrode sheet and a first separator, the first negative electrode sheet is bonded to the first end wall through a first bonding layer, the first positive electrode sheet is located on the side of the first negative electrode sheet away from the first end wall, and the first separator is arranged between the first positive electrode sheet and the first negative electrode sheet; wherein the bonding force of the first bonding layer is F1, which satisfies F1≥10 N / m; the bonding force of the first negative electrode sheet and the first separator is F2, and the bonding force of the first positive electrode sheet and the first separator is F3, which satisfies F2<F3. It should be noted that the bonding force included in the first bonding layer is divided into three parts: ① the bonding force between the first end wall and the first bonding layer; ② the cohesive force of the first bonding layer; and ③ the bonding force between the first bonding layer and the first negative electrode sheet. Here, the bonding force of the first bonding layer refers to the lowest bonding force of the first bonding layer, that is, the bonding force corresponding to the interface that separates first.

[0060] In the battery cell with the above structure, the battery cell includes a shell and an electrode assembly, the electrode assembly is accommodated in the shell, so that the shell can play a protective role on the electrode assembly; by making the bonding force F1 of the first bonding layer between the first negative electrode sheet and the first end wall be F1≥10 N / m, the bonding force between the electrode assembly and the first end wall can be larger, the impulse of the external force received by the battery cell is transmitted to the electrode assembly through the first bonding layer, and the possibility of cracking of the shell is smaller; by making the bonding force F2 of the first negative electrode sheet and the first separator and the bonding force F3 of the first positive electrode sheet and the first separator satisfy F2<F3, the bonding force between the first negative electrode sheet and the first separator can be smaller, the impulse transmitted to the first positive electrode sheet can be reduced, thereby the possibility of tearing of the electrode assembly can be reduced, the possibility of stress failure of the battery cell is lower, and the service life of the battery cell is prolonged.

[0061] The battery cell provided by the embodiments of the application can be a secondary battery or a primary battery, for example, can be a lithium ion battery, a sodium ion battery or a magnesium ion battery, etc., and the embodiments of the application are not limited thereto. The electrochemical device can be in the shape of a cylinder, a flat body, a cuboid or other shapes, and the embodiments of the application are not limited thereto.

[0062] The embodiments of the application provide a power consumption device using the battery cell as a power supply, and the power consumption device can be, but is not limited to, a mobile phone, a tablet computer, a notebook computer, an electric toy, an electric tool, an electric vehicle, an electric car, a ship, a spacecraft, etc.

[0063] Referring to FIG. 1, FIG. 1 is a schematic diagram of a cross-sectional structure of a battery cell provided by some embodiments of the application.

[0064] The embodiment of the present application provides a battery cell 10, which comprises a shell 100 and an electrode assembly 200, the electrode assembly 200 is accommodated in the shell 100, and the shell 100 comprises a first end wall 110 and a second end wall 120 which are oppositely arranged along the thickness direction X of the electrode assembly 200. The electrode assembly 200 comprises a first positive electrode sheet 210, a first negative electrode sheet 220 and a first separator 230, the first negative electrode sheet 220 is bonded to the first end wall 110 through a first bonding layer 310, the first positive electrode sheet 210 is located on the side of the first negative electrode sheet 220 which is away from the first end wall 110, and the first separator 230 is arranged between the first positive electrode sheet 210 and the first negative electrode sheet 220.

[0065] By accommodating the electrode assembly 200 in the shell 100, the shell 100 can play a protective role on the electrode assembly 200.

[0066] In some embodiments, the battery cell 10 is arranged in a square shape.

[0067] In some embodiments, the bonding force of the first bonding layer 310 is F1, and F1 is greater than or equal to 10 N / m. The bonding force between the first negative electrode sheet 220 and the first separator 230 is F2, and the bonding force between the first positive electrode sheet 210 and the first separator 230 is F3, and F2 is less than F3. For example, F1 can be 10 N / m, 20 N / m or 50 N / m, etc. For example, F2 can be 0.9*F3, 0.7*F3 or 0.5*F3, etc.

[0068] By making the bonding force F1 of the first bonding layer 310 between the first negative electrode tab 220 and the first end wall 110 ≥ 10 N / m, the bonding force between the electrode assembly 200 and the first end wall 110 can be larger, and external force can be transmitted to the electrode assembly 200 through the first bonding layer 310 more, so that more impulse is absorbed, and the impulse of the external force of the battery cell 10 transmitted to the electrode assembly 200 through the first bonding layer 310 is more, and the possibility of cracking of the shell 100 is smaller. By making the bonding force F2 of the first negative electrode tab 220 and the first separator 230 and the bonding force F3 of the first positive electrode tab 210 and the first separator 230 satisfy F2 < F3, the bonding force between the first negative electrode tab 220 and the first separator 230 is smaller, which can reduce the impulse transmitted to the first positive electrode tab 210. Since the thickness of the negative electrode tab is generally greater than that of the positive electrode tab, the negative electrode tab is less likely to tear than the positive electrode tab when the battery cell 10 is stressed. Therefore, by arranging the first negative electrode tab 220 at the outermost side of the electrode assembly 200 and transmitting more impulse of the external force to the first negative electrode tab 220 and less impulse to the first positive electrode tab 210 and other electrode tabs, the electrode assembly 200 can be prevented from tearing, thereby reducing the possibility of tearing of the electrode assembly 200. Therefore, by making F1 ≥ 10 N / m and F2 < F3, the possibility of cracking of the shell 100 when the battery cell 10 is stressed can be reduced, and the possibility of tearing of the electrode assembly 200 when the battery cell 10 is stressed can be reduced, so that the possibility of stress failure of the battery cell 10 is lower, which is beneficial to prolong the service life of the battery cell 10. Therefore, in the above scheme, the problem of stress failure of the battery cell caused by tearing of the electrode tab and avoiding tearing of the electrode tab under the condition of large bonding force can be ensured.

[0069] In some embodiments, F3-F2 ≥ 5 N / m. For example, F3-F2 can be 5 N / m, 8 N / m, or 10 N / m, etc.

[0070] By making F3-F2 ≥ 5 N / m, the first negative electrode tab 220 and the first separator 230 can be more uniformly separated, thereby further reducing the impulse transmitted to the first positive electrode tab 210, further reducing the possibility of tearing of the electrode assembly 200, and making the possibility of stress failure of the battery cell 10 lower, which is beneficial to prolong the service life of the battery cell 10.

[0071] In some embodiments, 10 N / m ≤ F2 ≤ 95 N / m. For example, F2 can be 10 N / m, 50 N / m, or 95 N / m, etc.

[0072] When F2 is greater than or equal to 10 N / m, the first negative pole piece 220 can be less likely to be separated from the first diaphragm 230, so that the shell 100 can be less likely to be cracked by an excessive impulse, and other pole pieces except the first negative pole piece 220 can be less likely to be damaged or even short-circuited by colliding with the shell 100; when F2 is less than or equal to 95 N / m, the impulse of the external force transmitted to the first positive pole piece 210 can be less, so that the electrode assembly 200 can be further less likely to be torn; therefore, when 10 N / m ≤ F2 ≤ 95 N / m, the first negative pole piece 220 can be less likely to be separated from the first diaphragm 230, so that the shell 100 can be less likely to be cracked by an excessive impulse, and other pole pieces except the first negative pole piece 220 can be less likely to be damaged or even short-circuited by colliding with the shell 100, and the impulse of the external force transmitted to the first positive pole piece 210 can be less, so that the electrode assembly 200 can be further less likely to be torn.

[0073] In some embodiments, 15 N / m ≤ F3 ≤ 100 N / m. For example, F3 can be 15 N / m, 60 N / m or 100 N / m, etc.

[0074] When F3 is greater than or equal to 15 N / m, the first diaphragm 230 can be less likely to be separated from the first positive pole piece 210, so that the shell 100 can be less likely to be cracked by an excessive impulse, and other pole pieces except the first negative pole piece 220 can be less likely to be damaged or even short-circuited by colliding with the shell 100; when F3 is less than or equal to 100 N / m, the impulse of the external force transmitted to the first positive pole piece 210 can be less, so that the electrode assembly 200 can be less likely to be torn; therefore, when 15 N / m ≤ F3 ≤ 100 N / m, the first diaphragm 230 can be less likely to be separated from the first positive pole piece 210, so that the shell 100 can be less likely to be cracked by an excessive impulse, and other pole pieces except the first negative pole piece 220 can be less likely to be damaged or even short-circuited by colliding with the shell 100, and the impulse of the external force transmitted to the first positive pole piece 210 can be less, so that the electrode assembly 200 can be less likely to be torn.

[0075] Referring to FIG. 2 and FIG. 3, FIG. 2 is a cross-sectional structure schematic diagram of a battery cell provided by some embodiments of the present application; and FIG. 3 is a structure schematic diagram of a first diaphragm of a battery cell provided by some embodiments of the present application.

[0076] In some embodiments, the first negative electrode tab 220 includes a negative electrode current collector 221 and a negative electrode active material layer 222, the negative electrode active material layer 222 is disposed on a side of the negative electrode current collector 221 facing the first positive electrode tab 210, and a groove 222a is disposed on a side of the negative electrode active material layer 222 facing the first separator 230.

[0077] By disposing the negative electrode active material layer 222 on a side of the negative electrode current collector 221 facing the first positive electrode tab 210 and disposing the groove 222a on a side of the negative electrode active material layer 222 facing the first separator 230, the adhesion area between the negative electrode active material layer 222 and the first separator 230 can be small, so that the adhesion force between the negative electrode active material layer 222 and the first separator 230 is small, the impulse transmitted to the first positive electrode tab 210 can be reduced, the possibility of tearing of the electrode assembly 200 can be reduced, the possibility of stress failure of the battery cell 10 is low, and the service life of the battery cell 10 can be prolonged.

[0078] In some embodiments, the projection area of the groove 222a in the thickness direction of the first negative electrode tab 220 is S1, the projection area of the negative electrode active material layer 222 in the thickness direction of the first negative electrode tab 220 is S2, and 5%≤S1 / S2≤35% is satisfied. For example, S1 / S2 can be 5%, 15%, or 35%, etc.

[0079] When S1 / S2 is greater than or equal to 5%, the adhesion area between the negative electrode active material layer 222 and the first separator 230 can be small, so that the adhesion force between the negative electrode active material layer 222 and the first separator 230 is small, the impulse transmitted to the first positive electrode tab 210 can be reduced, and the possibility of tearing of the electrode assembly 200 can be reduced; when S1 / S2 is less than or equal to 35%, the adhesion area between the negative electrode active material layer 222 and the first separator 230 can be large, so that the adhesion force between the negative electrode active material layer 222 and the first separator 230 is large, the possibility of the first negative electrode tab 220 detaching from the first separator 230 can be small, the possibility of the shell 100 being cracked due to receiving an excessive impulse can be small, and the possibility of other tabs except the first negative electrode tab 220 being damaged or even short-circuited by colliding with the shell 100 can be small; therefore, when 5%≤S1 / S2≤35%, the impulse transmitted to the first positive electrode tab 210 can be reduced, the possibility of tearing of the electrode assembly 200 can be reduced, the possibility of the first negative electrode tab 220 detaching from the first separator 230 can be small, the possibility of the shell 100 being cracked due to receiving an excessive impulse can be small, and the possibility of other tabs except the first negative electrode tab 220 being damaged or even short-circuited by colliding with the shell 100 can be small.

[0080] In some embodiments, the grooves 222a extend along the first direction Y, the width of the grooves 222a along the second direction Z is W1, and the width of the negative electrode active material layer 222 along the second direction Z is W2, satisfying 5%≤W1 / W2≤35%. For example, W1 / W2 can be 5%, 15%, or 35%, etc.

[0081] In some embodiments, the thickness direction X, the first direction Y, and the second direction Z of the electrode assembly 200 are perpendicular to each other.

[0082] In some embodiments, the first separator 222 is provided with a plurality of grooves 222a, and W1 is the width of the plurality of grooves 222a along the second direction Z.

[0083] When W1 / W2 is greater than or equal to 5%, the adhesion area between the negative electrode active material layer 222 and the first separator 230 can be small, so that the adhesion force between the negative electrode active material layer 222 and the first separator 230 is small, which can reduce the impulse transmitted to the first positive electrode tab 210, thereby reducing the possibility of tearing of the electrode assembly 200; when W1 / W2 is less than or equal to 35%, the adhesion area between the negative electrode active material layer 222 and the first separator 230 can be large, so that the adhesion force between the negative electrode active material layer 222 and the first separator 230 is large, which can make the possibility of the first negative electrode tab 220 being separated from the first separator 230 small, thereby reducing the possibility of the shell 100 being cracked by an excessive impulse, and also reducing the possibility of other electrode tabs except the first negative electrode tab 220 being damaged or even short-circuited by colliding with the shell 100, and reducing the possibility of the first separator 230 extending into the groove 222a and adhering to the side wall of the groove 222a; therefore, when 5%≤W1 / W2≤35%, both the impulse transmitted to the first positive electrode tab 210 can be reduced, thereby reducing the possibility of tearing of the electrode assembly 200, and the possibility of the first negative electrode tab 220 being separated from the first separator 230 can be small, thereby reducing the possibility of the shell 100 being cracked by an excessive impulse, and also reducing the possibility of other electrode tabs except the first negative electrode tab 220 being damaged or even short-circuited by colliding with the shell 100, and reducing the possibility of the first separator 230 extending into the groove 222a and adhering to the side wall of the groove 222a.

[0084] In some embodiments, the first positive electrode tab 210 includes a positive electrode current collector 211, a first positive electrode active material layer 212, and a second positive electrode active material layer 213, the first positive electrode active material layer 212 is arranged on the side of the positive electrode current collector 211 facing the first negative electrode tab 220, and the second positive electrode active material layer 213 is arranged on the side of the positive electrode current collector 211 facing away from the first negative electrode tab 220. The side of the first positive electrode active material layer 212 facing the first separator 230 is arranged in a plane.

[0085] By arranging the first positive active material layer 212 to be flat on the side facing the first separator 230, the bonding area between the first positive active material layer 212 and the first separator 230 can be large, so that the bonding force between the first positive active material layer 212 and the first separator 230 is large, the possibility of the first negative electrode sheet 220 and the first separator 230 being separated from the first positive electrode sheet 210 is small, so that the possibility of the shell 100 being cracked due to excessive impulse is small, and the possibility of other electrode sheets except the first negative electrode sheet 220 being damaged or even short-circuited by colliding with the shell 100 is small.

[0086] Referring to FIG. 1, in some embodiments, the first negative electrode sheet 220 includes a negative current collector 221 and a negative active material layer 222, the negative active material layer 222 is arranged on the side of the negative current collector 221 facing the first positive electrode sheet 210, and the negative active material layer 222 includes a first adhesive, the content of the first adhesive in the negative active material layer 222 is 0.3% to 0.8%. For example, the content of the first adhesive in the negative active material layer 222 can be 0.3%, 0.5% or 0.8%, etc.

[0087] When the content of the first binder in the negative active material layer 222 is greater than or equal to 0.3%, the adhesion between the negative active material layer 222 and the first separator 230 can be greater, the possibility of the first negative electrode tab 220 being separated from the first separator 230 can be smaller, the possibility of the shell 100 being cracked due to receiving too much impulse can be smaller, and the possibility of other electrode tabs except the first negative electrode tab 220 being damaged or even short-circuited due to colliding with the shell 100 can be smaller. When the content of the first binder in the negative active material layer 222 is less than or equal to 0.8%, the adhesion between the negative active material layer 222 and the first separator 230 can be smaller, and the impulse transmitted to the first positive electrode tab 210 can be reduced. Since the thickness of the negative electrode tab is generally greater than the thickness of the positive electrode tab, the negative electrode tab is less likely to be torn than the positive electrode tab when the battery cell is stressed. Therefore, by arranging the first negative electrode tab 220 at the outermost side of the electrode assembly 200 and transmitting more impulse of the external force to the first negative electrode tab 220 and less impulse to the first positive electrode tab 210 and other electrode tabs, the electrode assembly 200 can be less likely to be torn, thereby reducing the possibility of the electrode assembly 200 being torn. Therefore, when the content of the first binder in the negative active material layer 222 is 0.3% to 0.8%, the first negative electrode tab 220 can be less likely to be separated from the first separator 230, thereby reducing the possibility of the shell 100 being cracked due to receiving too much impulse, and reducing the possibility of other electrode tabs except the first negative electrode tab 220 being damaged or even short-circuited due to colliding with the shell 100. In addition, the impulse transmitted to the first positive electrode tab 210 can be reduced, thereby reducing the possibility of the electrode assembly 200 being torn.

[0088] In some embodiments, the first positive electrode tab 210 includes a positive current collector 211, a first positive active material layer 212, and a second positive active material layer 213. The first positive active material layer 212 is arranged on the side of the positive current collector 211 facing the first negative electrode tab 220, and the second positive active material layer 213 is arranged on the side of the positive current collector 211 facing away from the first negative electrode tab 220. The first positive active material layer 212 includes a second binder, and the content of the second binder in the first positive active material layer 212 is 0.8% to 2%. For example, the content of the second binder in the first positive active material layer 212 can be 0.8%, 1.2%, or 2%, etc.

[0089] When the content of the second adhesive in the first positive electrode active material layer 212 is greater than or equal to 0.8%, the adhesion between the first positive electrode active material layer 212 and the first separator 230 can be greater, the possibility of the first positive electrode tab 210 being separated from the first separator 230 can be smaller, and the possibility of other electrode tabs except the first negative electrode tab 220 being damaged or even short-circuited with the shell 100 can be smaller; when the content of the second adhesive in the first positive electrode active material layer 212 is less than or equal to 2%, the adhesion between the first positive electrode active material layer 212 and the first separator 230 can be smaller, the impulse transmitted to the first positive electrode tab 210 can be reduced, and thus the possibility of the electrode assembly 200 being torn can be reduced; therefore, when the content of the second adhesive in the first positive electrode active material layer 212 is 0.8% to 2%, the possibility of the first positive electrode tab 210 being separated from the first separator 230 can be smaller, the possibility of other electrode tabs except the first negative electrode tab 220 being damaged or even short-circuited with the shell 100 can be smaller, and the impulse transmitted to the first positive electrode tab 210 can be reduced, and thus the possibility of the electrode assembly 200 being torn can be reduced.

[0090] In some embodiments, the first separator 230 includes a base layer 231, a second adhesive layer 232, and a third adhesive layer 233, the second adhesive layer 232 is arranged on a side of the base layer 231 facing the first negative electrode tab 220, the third adhesive layer 233 is arranged on a side of the base layer 231 facing the first positive electrode tab 210, the second adhesive layer 232 includes a third adhesive, the content of the third adhesive in the second adhesive layer 232 is a, the third adhesive layer 233 includes a fourth adhesive, the content of the fourth adhesive in the third adhesive layer 233 is b, and a < b is satisfied. For example, a can be 0.9*b, 0.7*b, or 0.5*b, etc.

[0091] By satisfying a < b for the content a of the third adhesive in the second adhesive layer 232 and the content b of the fourth adhesive in the third adhesive layer 233, the adhesion between the first separator 230 and the first negative electrode tab 220 can be smaller than the adhesion between the first separator 230 and the first positive electrode tab 210, the impulse transmitted to the first positive electrode tab 210 can be reduced, and thus the possibility of the electrode assembly 200 being torn can be reduced, and the possibility of the battery cell 10 being stressed to failure can be lower, which is beneficial to prolong the service life of the battery cell 10.

[0092] In some embodiments, 45% ≤ a ≤ 85% is satisfied. For example, a can be 45%, 65%, or 85%, etc.

[0093] When a is greater than or equal to 45%, the adhesion between the first separator 230 and the first negative electrode tab 220 can be relatively large, so that the first negative electrode tab 220 is less likely to be separated from the first separator 230, thereby reducing the possibility that the shell 100 is cracked due to an excessive impact, and reducing the possibility that other electrode tabs except the first negative electrode tab 220 are damaged or even short-circuited due to collision with the shell 100; when a is less than or equal to 85%, the adhesion between the first separator 230 and the first negative electrode tab 220 can be relatively small, so that the impact of the external force transmitted to the first positive electrode tab 210 is relatively small, thereby reducing the possibility that the electrode assembly 200 is torn; therefore, when 45%≤a≤85%, the first negative electrode tab 220 is less likely to be separated from the first separator 230, thereby reducing the possibility that the shell 100 is cracked due to an excessive impact, and reducing the possibility that other electrode tabs except the first negative electrode tab 220 are damaged or even short-circuited due to collision with the shell 100, and the impact of the external force transmitted to the first positive electrode tab 210 is relatively small, thereby reducing the possibility that the electrode assembly 200 is torn.

[0094] Referring to FIG. 1 and FIG. 4, FIG. 4 is a schematic view of a cross-sectional structure of the first separator of the battery cell according to some embodiments of the present application.

[0095] In some embodiments, the first separator 230 includes a base layer 231, a second adhesive layer 232 and a third adhesive layer 233, the second adhesive layer 232 is arranged on a side of the base layer 231 facing the first negative electrode tab 220, and the third adhesive layer 233 is arranged on a side of the base layer 231 facing the first positive electrode tab 210, the second adhesive layer 232 includes a first ceramic material, the content of the first ceramic material in the second adhesive layer 232 is c, the third adhesive layer 233 includes a second ceramic material, the content of the second ceramic material in the third adhesive layer 233 is d, and c>d is satisfied. For example, c can be 1.1*d, 1.5*d or 2*d, etc.

[0096] By satisfying c>d, the content of the first ceramic material in the second adhesive layer 232 is c, and the content of the second ceramic material in the third adhesive layer 233 is d, the adhesion between the first separator 230 and the first negative electrode tab 220 can be less than the adhesion between the first separator 230 and the first positive electrode tab 210, the impact transmitted to the first positive electrode tab 210 can be reduced, thereby reducing the possibility that the electrode assembly 200 is torn, and reducing the possibility that the battery cell 10 is stressed to failure, which is conducive to prolonging the service life of the battery cell 10.

[0097] In other embodiments, the first separator 230 can also only include the second adhesive layer 232 and the third adhesive layer 233.

[0098] In some embodiments, 10%≤c≤50%. For example, c can be 10%, 30%, or 50%, etc.

[0099] When c is greater than or equal to 10%, the adhesion between the first separator 230 and the first negative electrode tab 220 can be small, so that the impulse of the external force transmitted to the first positive electrode tab 210 is small, thereby reducing the possibility of the electrode assembly 200 being torn; when c is less than or equal to 50%, the adhesion between the first separator 230 and the first negative electrode tab 220 can be large, so that the possibility of the first negative electrode tab 220 being separated from the first separator 230 is small, thereby reducing the possibility of the shell 100 being cracked due to receiving an excessive impulse, and reducing the possibility of other electrode tabs except the first negative electrode tab 220 being damaged or even short-circuited due to colliding with the shell 100; therefore, when 10%≤c≤50%, the impulse of the external force transmitted to the first positive electrode tab 210 is small, thereby reducing the possibility of the electrode assembly 200 being torn, and the possibility of the first negative electrode tab 220 being separated from the first separator 230 is small, thereby reducing the possibility of the shell 100 being cracked due to receiving an excessive impulse, and reducing the possibility of other electrode tabs except the first negative electrode tab 220 being damaged or even short-circuited due to colliding with the shell 100.

[0100] Referring to FIG. 1, in some embodiments, the electrode assembly 200 further includes a second positive electrode tab 240, a second negative electrode tab 250, and a second separator 260, the second negative electrode tab 250 is adhered to the second end wall 120 through a fourth adhesive layer 320, the second positive electrode tab 240 is located on a side of the second negative electrode tab 250 away from the second end wall 120, and the second separator 260 is arranged between the second positive electrode tab 240 and the second negative electrode tab 250; wherein the adhesion of the fourth adhesive layer 320 is F4, and F4≥10 N / m. The adhesion between the second negative electrode tab 250 and the second separator 260 is F5, and the adhesion between the second positive electrode tab 240 and the second separator 260 is F6, and F5<F6. For example, F4 can be 10 N / m, 20 N / m, or 50 N / m, etc. For example, F5 can be 0.9*F6, 0.7*F6, or 0.5*F6, etc.

[0101] By making the bonding force F4 of the fourth bonding layer 320 between the second negative electrode tab 250 and the second end wall 120 ≥ 10 N / m, the bonding force between the electrode assembly 200 and the second end wall 120 can be larger, the impulse of the external force received by the battery cell 10 transmitted to the electrode assembly 200 through the fourth bonding layer 320 is more, and the possibility of cracking of the shell 100 is smaller. By making the bonding force F5 between the second negative electrode tab 250 and the second separator 260 and the bonding force F6 between the second positive electrode tab 240 and the second separator 260 satisfy F5 < F6, the bonding force between the second negative electrode tab 250 and the second separator 260 is smaller, which can reduce the impulse transmitted to the second positive electrode tab 240, thereby reducing the possibility of tearing of the electrode assembly 200. Therefore, by making F4 ≥ 10 N / m and F5 < F6, both the possibility of cracking of the shell 100 when the battery cell 10 is stressed and the possibility of tearing of the electrode assembly 200 when the battery cell 10 is stressed can be reduced, so that the possibility of stress failure of the battery cell 10 is lower, which is beneficial to prolong the service life of the battery cell 10.

[0102] Referring to FIG. 1 and FIG. 5, FIG. 5 is a cross-sectional structural schematic view of another perspective of the battery cell provided in some embodiments of the present application.

[0103] In some embodiments, the shell 100 further includes a side wall 130, which is arranged around the first end wall 110 and connects the first end wall 110 and the second end wall 120. The electrode assembly 200 includes a plurality of side surfaces 270 connected head to tail, and a fifth bonding layer 330 is arranged between at least one side surface 270 and the side wall 130, so that the electrode assembly 200 is bonded to the side wall 130 through the fifth bonding layer 330.

[0104] By arranging the fifth bonding layer 330 between at least one side surface 270 of the electrode assembly 200 and the side wall 130 of the shell 100, the electrode assembly 200 is bonded to the side wall 130 through the fifth bonding layer 330, which can further reduce the possibility of collision and damage of the electrode assembly 200 with the shell 100 due to displacement of the electrode assembly 200 relative to the shell 100, and also facilitates the assembly of the electrode assembly 200 and the shell 100, and the fifth bonding layer 330 can absorb a part of the impulse when the battery cell 10 is stressed, so that the bonding force range of the first bonding layer 310 is larger.

[0105] In some embodiments, the bonding force of the fifth bonding layer 330 is F7, which satisfies F7 ≥ 50 N / m. For example, F7 can be 50 N / m, 80 N / m, or 1000 N / m, etc.

[0106] By making the adhesive force F7 of the fifth adhesive layer 330 satisfy F7≥50 N / m, the adhesive force between the electrode assembly 200 and the side wall 130 of the shell 100 can be higher, and the possibility of the electrode assembly 200 colliding with the shell 100 due to displacement of the electrode assembly 200 relative to the shell 100 and being damaged or even short-circuited can be further reduced.

[0107] In some embodiments, the ratio of the length of each fifth adhesive layer 330 to the length of the side surface 270 on which the fifth adhesive layer 330 is located is between 40% and 80%. For example, the ratio of the length of each fifth adhesive layer 330 to the length of the side surface 270 on which the fifth adhesive layer 330 is located can be 40%, 60%, or 80%, etc.

[0108] When the ratio of the length of each fifth adhesive layer 330 to the length of the side surface 270 on which the fifth adhesive layer 330 is located is greater than or equal to 40%, the adhesive area between the electrode assembly 200 and the side wall 130 of the shell 100 can be larger, and the adhesive force between the electrode assembly 200 and the side wall 130 of the shell 100 can be higher, which can further reduce the possibility of the electrode assembly 200 colliding with the shell 100 due to displacement of the electrode assembly 200 relative to the shell 100 and being damaged or even short-circuited; when the ratio of the length of each fifth adhesive layer 330 to the length of the side surface 270 on which the fifth adhesive layer 330 is located is less than or equal to 80%, the influence on electrolyte penetration can be reduced, and the possibility of the fifth adhesive layer 330 being rolled to cause low process yield of the battery cell 10 can be reduced; therefore, when the ratio of the length of each fifth adhesive layer 330 to the length of the side surface 270 on which the fifth adhesive layer 330 is located is between 40% and 80%, both the possibility of the electrode assembly 200 colliding with the shell 100 due to displacement of the electrode assembly 200 relative to the shell 100 and being damaged or even short-circuited can be further reduced, and the influence on electrolyte penetration can be reduced, and the possibility of the fifth adhesive layer 330 being rolled to cause low process yield of the battery cell 10 can be reduced.

[0109] Referring to FIG. 1, in some embodiments, the battery cell 10 further includes a plurality of third positive electrode plates 270, a plurality of third negative electrode plates 280, and a plurality of third separators 290, the plurality of third positive electrode plates 270 and the plurality of third negative electrode plates 280 are arranged alternately between the first positive electrode plate 210 and the second positive electrode plate 220, and the third separator 290 is arranged between the third positive electrode plate 270 and the third negative electrode plate 280.

[0110] Referring to FIG. 5, in some embodiments, the battery cell 10 comprises a first electrode terminal 410 and a second electrode terminal 420, which are arranged on one of the side walls 130, the first electrode terminal 410 is connected with the first positive electrode tab 210, the second positive electrode tab 240 and the third positive electrode tab 270, the second electrode terminal 420 is connected with the first negative electrode tab 220, the second negative electrode tab 250 and the third negative electrode tab 280, and the side wall 130 on which the first electrode terminal 410 and the second electrode terminal 420 are arranged is not provided with the fifth adhesive layer 330 between the electrode assembly 200, which can avoid the first electrode terminal 410 and the second electrode terminal 410, reduce the influence on the electrical connection between the first electrode terminal 410 and the positive electrode tab, the second electrode terminal 420 and the negative electrode tab, and reduce the influence on the electrical connection between the first electrode terminal 410 and the second electrode terminal 420 and the load.

[0111] Referring to FIG. 6, FIG. 6 is a cross-sectional structural schematic view of a battery cell according to some other embodiments of the present application.

[0112] In some other embodiments, the battery cell 10 can also be provided in a special shape, for example, an L shape. The first adhesive layer 310 is arranged between the first end wall 110 of the shell 100 and the electrode assembly 200, the second adhesive layer 320 is arranged between the second end wall 120 and the electrode assembly 200, and the fifth adhesive layer 330 is arranged between the plurality of side walls 130 of the shell 100 and the electrode assembly 200.

[0113] In some embodiments, the shell 100 is a hard shell.

[0114] In the above technical solution, the shell 100 is a hard shell, which can prevent external force from directly acting on the electrode assembly 200, so that the protection of the shell 100 on the electrode assembly 200 is better.

[0115] In some embodiments, the electrode assembly 200 is a laminated structure.

[0116] Referring to Table 1, F1 in Table 1 is the adhesive force of the first adhesive layer, F2 is the adhesive force between the first negative electrode tab and the first separator, and F3 is the adhesive force between the first positive electrode tab and the first separator.

[0117] The test method of the adhesive force is as follows:

[0118] (1) Take the battery cell sample and charge it to a state of charge (SOC) = 100%;

[0119] (2) Disassemble the battery cell, cut off the excess shell along the periphery of the battery cell, and place the battery cell in a test electrolyte, soak in an oven at 85°C for 4 hours, and then take out and air dry at room temperature;

[0120] (3) Connect the two sides of the tensile testing machine with the two parts of the battery cell to be tested for adhesion (for example, when testing the adhesion of the first adhesive layer, connect the two sides of the tensile testing machine with the first negative electrode tab and the first end wall, respectively), and test the tensile force at a speed of 50 mm / min with the two sides at a 90° direction;

[0121] (4) Record the original F-X (tensile force-displacement) data of the tensile testing machine and analyze it to measure the average tensile force of the stable region / test sample width, which is recorded as the adhesion.

[0122] The test method for drop pass rate is:

[0123] (1) Charge the battery cell sample at 23±2℃, measure and record the open circuit voltage and battery impedance of the battery cell;

[0124] (2) Drop the battery cell freely from a height of 1.5m (measured from the lowest point of the battery cell to the drop surface) onto concrete, and perform 30 rounds of drop test, with the sequence of each round being: front side-rear side-bottom side-top side-left side-right side, left upper corner-right upper corner-left lower corner-right lower corner;

[0125] (3) Statistically analyze and observe the appearance of the battery cell, and the criteria for passing the drop test are: no explosion, no smoke, no fire, and no liquid leakage within 1 hour after the battery cell is dropped; the difference between the open circuit voltage of the battery cell after 24 hours and the initial value before the drop is not greater than 50mV.

[0126] Table 1

[0127] The test method for tab tearing is:

[0128] (1) Charge the battery cell sample at 23±2℃, measure and record the open circuit voltage and battery impedance of the battery cell;

[0129] (2) Drop the battery cell freely from a height of 1.5m (measured from the lowest point of the battery cell to the drop surface) onto concrete, and perform 30 rounds of drop test, with the sequence of each round being: front side-rear side-bottom side-top side-left side-right side, left upper corner-right upper corner-left lower corner-right lower corner;

[0130] (3) Discharge the battery cell at a constant current of 0.2C to 3V;

[0131] (4) Disassemble the battery cell, and determine whether the tab has a crack greater than or equal to 2mm, if the number of cracks exceeds 1, it is determined that the tab of the battery cell is torn, and the tab tearing rate = the number of battery cells with tab tearing / the total number of battery cells.

[0132] The test method for weld seam punching is:

[0133] (1) Charge the cell sample to full at 23±2℃, measure and record the open circuit voltage and battery impedance of the cell;

[0134] (2) Drop the cell freely from a height of 1.5m (measured from the lowest point of the cell to the falling surface) onto concrete, and conduct 30 rounds of drop test, with the drop sequence being: front face - back face - lower face - upper face - left face - right face, left upper corner - right upper corner - left lower corner - right lower corner;

[0135] (3) Check the cell appearance throughout, and determine whether there is a crack greater than 1mm in the cell shell, and if the number of cracks exceeds 1, then it is determined that the weld of the cell is broken;

[0136] (4) Use an organic volatile gas tester to test whether the organic volatile gas concentration around the cell exceeds the threshold value, and if it does, then it is determined that the weld of the cell is broken; the weld breakage rate = the number of cells with weld breakage / the total number of cells.

[0137] The test method for the number of cycles is as follows:

[0138] (1) Place the cell in an environment of 25±2℃, charge the cell to the charge cut-off voltage (such as 4.5V) of the cell at a constant current of 0.2C, charge the cell to 0.025C at a constant voltage, and then discharge the cell to the discharge cut-off voltage (such as 3.0V) of the cell at a constant current of 0.2C, which is recorded as one cycle of the cell;

[0139] (2) Record the number of cycles before the first black spot appears on the cell.

[0140] The following conclusions can be drawn from Table 1:

[0141] 1. Referring to Comparative Example 1 and Examples 1-3, when the adhesion F1 of the first adhesive layer is greater than or equal to 10N / m, the drop pass rate and the number of cycles of the cell are both high, and the tab tearing rate and the weld breakage rate are both low; when the adhesion F1 of the first adhesive layer is less than 10N / m, the drop pass rate of the cell is low, the weld breakage rate is high, and the cell is easily damaged under stress, affecting the service life of the cell.

[0142] 2. Referring to Comparative Example 2 and Examples 4-7, when F2 is between 10N / m and 95N / m, the drop pass rate and the number of cycles of the cell are both high, and the tab tearing rate and the weld breakage rate are both low; when F2 is less than 10N / m, the drop pass rate and the number of cycles of the cell are both low, the weld breakage rate is high, the cell is easily damaged under stress, and the cycle life of the cell is affected; when F2 is greater than 95N / m, the drop pass rate of the cell decreases sharply, the tab tearing rate increases sharply, the cell is easily damaged under stress, and the service life of the cell is affected.

[0143] 3、Referring to Comparative Example 4 and Examples 8-11, when F3 is between 15 N / m and 100 N / m, the drop pass rate and cycle number of the battery cell are both high, and the tab tearing rate and weld tearing rate are both low; when F3 is less than 15 N / m, the drop pass rate of the battery cell is sharply reduced, the tab tearing rate is sharply increased, and the battery cell is easily damaged under stress, affecting the service life of the battery cell; when F3 is greater than 100 N / m, the cycle number of the battery cell is sharply reduced, affecting the cycle life of the battery cell.

[0144] 4、Referring to Comparative Examples 2-5 and Examples 12-14, when F3-F2 is greater than 0 N / m, the drop pass rate and cycle number of the battery cell are both high, and the tab tearing rate and weld tearing rate are both low; when F3-F2 is less than or equal to 0 N / m, the drop pass rate of the battery cell is low, and the tab tearing rate is high, the battery cell is easily damaged under stress, affecting the service life of the battery cell.

[0145] 5、Referring to Examples 15-18, when F7 is greater than or equal to 50 N / m, the drop pass rate and cycle number of the battery cell are both high, and the tab tearing rate and weld tearing rate are both low; when F7 is less than 50 N / m, the drop pass rate of the battery cell is reduced, and the weld tearing rate is increased, the battery cell is easily damaged under stress, affecting the service life of the battery cell.

[0146] The embodiments of the present application also provide a power-using device, which comprises the battery cell 10 of any one of the above schemes, and the battery cell 10 is used to provide electric energy for the power-using device.

[0147] The power-using device can be any one of the devices or apparatuses using the battery cell 10.

[0148] It should be noted that the embodiments and features in the embodiments of the present application can be combined with each other without conflict.

[0149] The above is only the preferred embodiments of the present application and is not used to limit the present application. The present application can have various modifications and changes for those skilled in the art. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. An electric cell, characterized by, The battery includes a shell and an electrode assembly accommodated in the shell, the shell includes a first end wall and a second end wall oppositely arranged along a thickness direction of the electrode assembly; The electrode assembly includes a first positive electrode tab, a first negative electrode tab and a first separator, the first negative electrode tab is bonded to the first end wall through a first bonding layer, the first positive electrode tab is located on a side of the first negative electrode tab away from the first end wall, and the first separator is arranged between the first positive electrode tab and the first negative electrode tab; The bonding force of the first bonding layer is F1, F1≥10N / m; the bonding force between the first negative electrode tab and the first separator is F2, and the bonding force between the first positive electrode tab and the first separator is F3, F2 2. The electric cell of claim 1, wherein, F3-F2≥5N / m.

3. The electric cell of claim 1, wherein, 10N / m≤F2≤95N / m, 15N / m≤F3≤100N / m.

4. The electric cell of claim 1, wherein, The first negative electrode tab includes a negative electrode current collector and a negative electrode active material layer, the negative electrode active material layer is arranged on a side of the negative electrode current collector facing the first positive electrode tab, and a groove is arranged on a side of the negative electrode active material layer facing the first separator.

5. The electric cell of claim 4, wherein, The projection area of the groove in the thickness direction of the first negative electrode tab is S1, and the projection area of the negative electrode active material layer in the thickness direction of the first negative electrode tab is S2, 5%≤S1 / S2≤35%.

6. The electric cell of claim 4, wherein, The groove extends along a first direction, the width of the groove along a second direction is W1, and the width of the negative electrode active material layer along the second direction is W2, 5%≤W1 / W2≤35%; The thickness direction of the electrode assembly, the first direction and the second direction are perpendicular to each other.

7. The electric cell of claim 4, wherein, The first positive electrode tab includes a positive electrode current collector, a first positive electrode active material layer and a second positive electrode active material layer, the first positive electrode active material layer is arranged on a side of the positive electrode current collector facing the first negative electrode tab, and the second positive electrode active material layer is arranged on a side of the positive electrode current collector away from the first negative electrode tab. The first positive electrode active material layer is arranged in a plane on a side facing the first separator.

8. The electric cell of claim 1, wherein, The first negative electrode tab includes a negative electrode current collector and a negative electrode active material layer, the negative electrode active material layer is arranged on a side of the negative electrode current collector facing the first positive electrode tab, and the negative electrode active material layer includes a first adhesive, the content of the first adhesive in the negative electrode active material layer is 0.3% to 0.8%.

9. The electric cell of claim 1, wherein, The first positive electrode tab includes a positive electrode current collector, a first positive electrode active material layer and a second positive electrode active material layer, the first positive electrode active material layer is arranged on a side of the positive electrode current collector facing the first negative electrode tab, and the second positive electrode active material layer is arranged on a side of the positive electrode current collector away from the first negative electrode tab; the first positive electrode active material layer includes a second adhesive, and the content of the second adhesive in the first positive electrode active material layer is 0.8% to 2%.

10. The electric cell of claim 1, wherein, The first diaphragm comprises a base layer, a second adhesive layer and a third adhesive layer, the second adhesive layer is arranged on one side of the base layer facing the first negative electrode tab, the third adhesive layer is arranged on one side of the base layer facing the first positive electrode tab, the second adhesive layer comprises a third adhesive, the content of the third adhesive in the second adhesive layer is a, the third adhesive layer comprises a fourth adhesive, the content of the fourth adhesive in the third adhesive layer is b, and a < b.

11. The electric cell of claim 10, wherein, 45％≤a≤85％。 12. The electric cell of claim 1, wherein, The first diaphragm comprises a base layer, a second adhesive layer and a third adhesive layer, the second adhesive layer is arranged on one side of the base layer facing the first negative electrode tab, the third adhesive layer is arranged on one side of the base layer facing the first positive electrode tab, the second adhesive layer comprises a first ceramic material, the content of the first ceramic material in the second adhesive layer is c, the third adhesive layer comprises a second ceramic material, the content of the second ceramic material in the third adhesive layer is d, and c > d.

13. The electric cell of claim 11, wherein, 10％≤c≤50％。 14. The electrically charged cell of claim 1, wherein, The electrode assembly further comprises a second positive electrode tab, a second negative electrode tab and a second diaphragm, the second negative electrode tab is adhered to the second end wall through a fourth adhesive layer, the second positive electrode tab is located on one side of the second negative electrode tab away from the second end wall, and the second diaphragm is arranged between the second positive electrode tab and the second negative electrode tab. Wherein, the adhesive force of the fourth adhesive layer is F4, and F4 ≥ 10 N / m; the adhesive force between the second negative electrode tab and the second diaphragm is F5, and the adhesive force between the second positive electrode tab and the second diaphragm is F6, and F5 < F6.

15. The electrically charged cell of claim 1, wherein, The shell further comprises a side wall, the side wall is arranged around the first end wall, and the side wall connects the first end wall and the second end wall. The electrode assembly comprises a plurality of side surfaces connected head to tail, at least one of the side surfaces and the side wall are provided with a fifth adhesive layer, and the electrode assembly is adhered to the side wall through the fifth adhesive layer.

16. The electric cell of claim 15, wherein, The adhesive force of the fifth adhesive layer is F7, and F7 ≥ 50 N / m.

17. The electric cell of claim 15, wherein, The ratio of the length of each fifth adhesive layer to the length of the side surface where the fifth adhesive layer is located is between 40% and 80%.

18. The electrically core of claim 1, wherein, The shell is a hard shell.

19. The electrically core of claim 1, wherein, The electrode assembly is a laminated structure.

20. An electrical device, comprising: An electric cell comprising any one of claims 1-19 is used to provide electric energy.

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