Battery cells and battery packs

Abstract

This utility model relates to the field of battery technology and discloses a battery cell and battery pack. The battery cell includes a housing, electrode assembly, electrolyte reservoir, and cover assembly. The housing has a cavity, and at least one end is open; at least one expansion groove is provided on any side wall of the housing, and the expansion groove communicates with the cavity of the housing; the electrode assembly is disposed within the cavity of the housing; the electrolyte reservoir is disposed within the expansion groove and faces the electrode assembly, and stores electrolyte within the electrolyte reservoir; after the electrode assembly expands, it applies expansion pressure to the electrolyte reservoir, and the electrolyte reservoir is adapted to rupture when the expansion pressure reaches a pressure threshold to release the electrolyte; the cover assembly is disposed at the open end of the housing and encapsulates the electrolyte, electrode assembly, and electrolyte reservoir within the housing. In this utility model, the housing is provided with an expansion groove, and the electrolyte reservoir is disposed within the expansion groove. The electrolyte reservoir ruptures when the expansion pressure from the electrode assembly reaches a pressure threshold to release the electrolyte, achieving automatic electrolyte replenishment without disassembling the battery, improving the performance of the battery cell, and extending the service life of the battery cell.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, specifically to battery cells and battery packs. Background Technology

[0002] In existing lithium-ion or ternary lithium batteries, the electrolyte gradually depletes during daily use, directly shortening the battery's lifespan. Battery performance degrades rapidly in the later stages of use; therefore, replenishing the electrolyte during battery use is crucial.

[0003] In existing battery structures, individual cells are typically sealed using laser welding, while battery packs generally use structural adhesives to bond multiple individual cells together, along with a battery pack cover and other structures, to seal the entire battery. Because the individual cells and the battery pack are well-sealed, it is difficult to replenish the electrolyte by disassembling the battery system later in the battery's lifespan, and disassembling the battery system would undoubtedly increase the battery's operating costs. Utility Model Content

[0004] In view of this, the present invention provides a battery cell and battery pack to solve the problem that the difficulty of replenishing electrolyte in the later stages of battery use affects battery performance and lifespan.

[0005] In a first aspect, this utility model provides a battery cell, including a housing, an electrode assembly, a liquid reservoir, and a cover assembly. The housing has a cavity, and at least one end is an open end; at least one expansion groove is provided on any side wall of the housing, and the expansion groove communicates with the cavity of the housing; the electrode assembly is disposed within the cavity of the housing; the liquid reservoir is disposed within the expansion groove and faces the electrode assembly, and stores electrolyte within the liquid reservoir; after the electrode assembly expands, it applies expansion pressure to the liquid reservoir, and the liquid reservoir is adapted to rupture when the expansion pressure reaches a pressure threshold to release the electrolyte; the cover assembly is disposed at the open end of the housing, and encapsulates the electrolyte, the electrode assembly, and the liquid reservoir within the housing.

[0006] Beneficial Effects: The battery cell provided by this utility model provides a cavity for the electrolyte storage component by setting an expansion groove on the side wall of the casing. The electrolyte storage component is set in the expansion groove and faces the electrode assembly. The electrolyte storage component stores electrolyte. As the battery cell is used continuously, the electrolyte is gradually consumed, and the expansion of the electrode assembly also increases. During the expansion of the electrode assembly, the electrode assembly applies pressure to the electrolyte storage component. When the pressure applied to the electrolyte storage component due to the expansion of the electrode assembly reaches a pressure threshold, the electrolyte storage component ruptures, releasing the electrolyte. The electrolyte flows out and wets the electrode assembly, realizing the automatic release and replenishment of electrolyte according to the battery cell's usage without disassembling the battery. This improves the battery cell's performance in the later stages of use and extends its service life.

[0007] In one alternative embodiment, the housing includes two opposing first sidewalls, the thickness of which is h in mm, and the depth of the expansion groove is H in mm, satisfying: 0.5 ≤ H / h ≤ 2.

[0008] In one alternative implementation, the following condition is also satisfied: 0.25mm≤h≤0.8mm.

[0009] In one optional embodiment, the two ends of the housing along the X direction are set as open ends, and the minimum distance between the expansion groove and any open end of the housing along the X direction is L, in mm, where L≥10mm.

[0010] In one alternative embodiment, in the initial state after assembly, along the Z direction, the cavity size of the housing is T in mm, and the minimum distance between the liquid reservoir and the electrode assembly is t in mm, where 0.035 ≤ t / T ≤ 0.075.

[0011] In one alternative embodiment, the first surface of the liquid reservoir is fixedly connected to the bottom wall of the expansion groove by an adhesive layer, and the second surface of the liquid reservoir faces the electrode assembly.

[0012] In one alternative embodiment, in the initial state after assembly, the second surface of the liquid reservoir does not protrude beyond the inner surface of the first sidewall along the Z direction.

[0013] In one alternative embodiment, the liquid reservoir is a sealed container made of micro / nano films.

[0014] In one alternative implementation, the pressure threshold is P, in MPa, where 0.15MPa≤P≤0.4MPa.

[0015] Secondly, this utility model also provides a battery pack, including the battery cells described in any one of the above technical solutions.

[0016] Beneficial effects: Since the battery pack includes the cells, it has all the technical benefits of the cells, which will not be elaborated here. Attached Figure Description

[0017] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the structure of a battery cell according to an embodiment of the present utility model;

[0019] Figure 2 for Figure 1 The exploded view of the battery cell shown;

[0020] Figure 3 for Figure 2 A schematic diagram of the shell structure in the middle;

[0021] Figure 4 for Figure 3 The front view of the casing is shown;

[0022] Figure 5 For along Figure 4 Sectional view at point AA;

[0023] Figure 6 for Figure 5 A magnified view of a section at point B in the middle;

[0024] Figure 7 for Figure 2 Schematic diagram of the structure after the connection between the liquid storage component and the adhesive layer;

[0025] Figure 8 A schematic diagram of the structure after the liquid storage component is assembled inside the shell;

[0026] Figure 9 for Figure 1 The image shows the front view of the battery cell;

[0027] Figure 10 For along Figure 9 Sectional view at CC;

[0028] Figure 11 for Figure 10 Enlarged view of a section at point D.

[0029] Explanation of reference numerals in the attached figures:

[0030] 1. Housing; 101. First sidewall; 102. Expansion groove; 2. Electrode assembly; 3. Liquid reservoir; 4. Adhesive layer; 5. Cover plate assembly. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0032] To address the problem of battery performance degradation and shortened lifespan due to electrolyte deficiency in the later stages of battery use, and the inconvenience of disassembling the battery to replenish the electrolyte, this invention provides a battery cell with a pre-designed electrolyte storage structure inside. In the later stages of battery cycle use, the pre-designed electrolyte storage structure inside the battery is subjected to the expansion pressure of the electrode assembly 2. When the pressure reaches a pressure threshold, the electrolyte storage structure cracks, and the electrolyte flows out. This allows for electrolyte replenishment without disassembling the battery, improving battery performance and lifespan.

[0033] The following is combined with Figures 1 to 11 The following describes embodiments of the present invention.

[0034] According to an embodiment of the present invention, in a first aspect, a battery cell is provided, comprising a housing 1, an electrode assembly 2, a liquid reservoir 3, and a cover plate assembly 5. The housing 1 has a cavity, and at least one end is an open end; at least one expansion groove 102 is provided on any side wall of the housing 1, the expansion groove 102 communicating with the cavity of the housing 1; the electrode assembly 2 is disposed within the cavity of the housing 1; the liquid reservoir 3 is disposed within the expansion groove 102 and faces the electrode assembly 2, and stores electrolyte within the liquid reservoir 3; after the electrode assembly 2 expands, it applies expansion pressure to the liquid reservoir 3, and the liquid reservoir 3 is adapted to rupture when the expansion pressure reaches a pressure threshold to release the electrolyte; the cover plate assembly 5 is disposed at the open end of the housing 1, and encapsulates the electrolyte, the electrode assembly 2, and the liquid reservoir 3 within the housing 1.

[0035] The battery cell provided by this utility model provides a cavity for the electrolyte storage component 3 by setting an expansion groove 102 on the side wall of the housing 1. The electrolyte storage component 3 is disposed in the expansion groove 102 and faces the electrode assembly 2. The electrolyte storage component 3 stores electrolyte. As the battery cell is used continuously, the electrolyte is gradually consumed, and the expansion of the electrode assembly 2 also increases. During the expansion process of the electrode assembly 2, the electrode assembly 2 will apply expansion pressure to the electrolyte storage component 3. When the pressure applied to the electrolyte storage component 3 due to the expansion of the electrode assembly 2 reaches the pressure threshold, the electrolyte storage component 3 ruptures and releases the electrolyte. The electrolyte flows out and wets the electrode assembly 2, realizing the automatic release and replenishment of electrolyte according to the usage of the battery cell without disassembling the battery, thereby improving the performance of the battery cell in the later stages of use and extending the service life of the battery cell.

[0036] The electrolyte reservoir 3 is configured to rupture when the expansion pressure from the electrode assembly 2 reaches a pressure threshold, thereby releasing the electrolyte. The pressure threshold is the pressure value at which the electrolyte reservoir 3 ruptures. It is understood that if the pressure applied to the electrolyte reservoir 3 after the electrode assembly 2 expands does not reach the pressure threshold, the electrolyte reservoir 3 remains intact.

[0037] In the composition of the battery cell, the main functions of the casing 1 include the following aspects:

[0038] Encapsulation and protection. The cell casing 1 is used to encapsulate the internal components of the battery, such as the electrode assembly 2 and electrolyte, to prevent moisture, oxygen, and other harmful substances from entering from the external environment, thereby protecting the internal structure of the battery from damage.

[0039] Mechanical support. The housing 1 provides the necessary mechanical strength and support for the battery cell, enabling it to withstand external pressure, impact and vibration, and ensuring the stability and integrity of the battery during use.

[0040] Electrical insulation. The cell casing 1 typically has good electrical insulation properties, which can effectively isolate the positive and negative terminals, prevent short circuits, and ensure the safe operation of the battery.

[0041] Sealing performance. To extend battery life and ensure safety, the cell casing 1 needs to have excellent sealing performance to prevent electrolyte leakage or the ingress of external contaminants.

[0042] Specifically, taking the blade battery cell as an example, the housing 1 has open ends for inserting the electrode assembly 2. After inserting the electrode assembly 2, cover plate assemblies 5 are respectively installed at the two open ends (one end is a positive cover plate assembly and the other end is a negative cover plate assembly) to encapsulate the electrode assembly 2, electrolyte and liquid storage device 3 inside the housing 1.

[0043] The blade battery casing 1 has a rectangular frame structure with four sidewalls: two opposing first sidewalls 101 and two opposing second sidewalls. The area of ​​the first sidewalls 101 is larger than the area of ​​the second sidewalls. The first sidewalls 101 are also referred to as the large surface of the casing 1. Specifically, refer to... Figure 3 The X direction is the length direction of shell 1, the Y direction is the width direction of shell 1, and the Z direction is the thickness direction of shell 1. The first sidewall 101 is the sidewall of the plane shown in XY. The second sidewall is the sidewall of the plane shown in XZ.

[0044] Since the relative area between the large surface of the shell 1 and the electrode group 2 is relatively large, an expansion groove 102 can be provided on the large surface of the shell 1 to increase the pre-storage amount of electrolyte.

[0045] Since the housing 1 has two large surfaces, in some embodiments, two or more expansion grooves 102 can be provided. For example, expansion grooves 102 can be provided on both large surfaces of the housing 1. In this way, when the electrode group 2 expands and applies pressure to cause the liquid storage device 3 to rupture, both sides of the electrode group 2 can be replenished and wetted with electrolyte, so that the electrode group 2 is uniformly and fully wetted, further improving the performance of the battery cell.

[0046] The expansion groove 102 provided in the housing 1 serves several purposes. First, it provides a cavity for the electrolyte storage component 3, enabling automatic replenishment of electrolyte to the battery cell during later use. Second, to reduce weight and cost, the housing 1 has a thin wall thickness; the expansion groove 102 enhances the structural strength and deformation resistance of the housing 1, thereby improving its flatness. Finally, in the event of a rupture of the electrolyte storage component 3, the expansion groove 102 and the electrode assembly 2 form an air passage, facilitating gas flow during internal gas generation. Especially in the later stages of battery use, when the risk of thermal runaway is high, the air passage formed by the expansion groove 102 accelerates gas exhaust during thermal runaway, allowing the gas to flow rapidly to the explosion-proof valve, enabling rapid response, gas exhaust, and pressure relief, thus improving the safety of the battery cell.

[0047] The shape of pole group 2 is adapted to that of housing 1. Pole group 2 has a cuboid structure. The surface of pole group 2 facing the large face of housing 1 is also the large face of pole group 2. One pole group 2 can be provided, or multiple pole groups 2 can be provided. When multiple pole groups 2 exist, adjacent pole groups 2 are arranged side by side by means of adjacent large faces.

[0048] In some embodiments, the housing 1 includes two opposing first sidewalls 101, the thickness of the first sidewalls 101 being h in mm, and the depth of the expansion groove 102 being H in mm, satisfying: 0.5 ≤ H / h ≤ 2.

[0049] The depth H of the expansion groove 102 is the vertical distance from the inner surface of the first sidewall 101 to the bottom wall of the expansion groove 102. Specifically, the expansion groove 102 includes a bottom wall and sidewalls. The bottom wall of the expansion groove 102 is opposite to the large surface of the pole group 2 and parallel to the large surface of the housing 1. The sidewalls of the expansion groove 102 are located on the side of the bottom wall of the expansion groove 102. When the expansion groove 102 is a rectangular groove, the expansion groove 102 has one bottom wall and four sidewalls.

[0050] The depth H of the expansion groove 102 is controlled between 0.5h and 2h. This provides sufficient cavity to accommodate the liquid storage component 3 and ensures the pre-storage amount of electrolyte, which is the amount of electrolyte to be replenished in the later stage of battery use. At the same time, it is not too large and affects the thickness of the battery, thus avoiding a significant increase in the space occupied by the battery in the thickness direction (Z direction).

[0051] In some embodiments, the following condition is also satisfied: 0.25mm≤h≤0.8mm.

[0052] To reduce weight and cost, the thickness h of the first sidewall 101 of the housing 1 is controlled within the range of 0.25mm to 0.8mm. In this embodiment, since the first sidewall 101 of the housing 1 is also provided with an expansion groove 102, the structural strength of the housing 1 is improved on the basis of the original structure, and it has a strong resistance to deformation.

[0053] In this embodiment, the housing 1 has four sidewalls, and the thickness of the first sidewall 101 and the second sidewall can be the same or different.

[0054] In some embodiments, the two ends of the housing 1 along the X direction are set as open ends. Along the X direction, the minimum distance between the expansion groove 102 and any open end of the housing 1 is L, in mm, and L≥10mm.

[0055] Specifically, in this embodiment, the two ends of the shell 1 along its length (X direction) are open ends, and a positive electrode cover plate assembly and a negative electrode cover plate assembly are respectively provided thereon. The expansion groove 102 is located in an area 10mm away from any open end of the shell 1, which can avoid interference with the cover plate assembly 5 and ensure that the assembly of the cover plate assembly 5 is not affected.

[0056] The location, number, size, and shape of the expansion groove 102 within this area are not limited. The required amount of electrolyte can be determined by simulating the battery's lifespan based on the battery's capacity and usage requirements, and then the volume of the expansion groove 102 can be determined.

[0057] In the expansion groove 102, there is an assembly gap of 0.1mm to 10mm between the periphery of the liquid storage component 3 and the side wall of the expansion groove 102. The shape of the liquid storage component 3 in the expansion groove 102 is not limited after ensuring the assembly gap.

[0058] In some embodiments, in the initial state after assembly, along the Z direction, the size of the cavity of the housing 1 is T, in mm, and the minimum distance between the liquid storage element 3 and the electrode group 2 is t, in mm, where 0.035≤t / T≤0.075.

[0059] The first surface of the liquid storage component 3 is connected to the bottom wall of the expansion groove 102, and the second surface of the liquid storage component 3 faces the electrode assembly 2. In the initial state after assembly, the second surface of the liquid storage component 3 may or may not be in contact with the electrode assembly 2. Preferably, in this embodiment, the second surface of the liquid storage component 3 does not contact the electrode assembly 2, and the distance between them is controlled within the range of 0.035≤t / T≤0.075. That is, the percentage of the distance between the second surface of the liquid storage component 3 and the electrode assembly 2 relative to the size of the cavity of the housing 1 is in the range of 3.5% to 7.5%. In this way, on the one hand, it is convenient for the electrode assembly 2 to be installed into the housing 1; on the other hand, in the early and middle stages of battery use, the liquid storage component 3 does not contact the electrode assembly 2 and is not affected by the expansion, compression, and heat generation of the electrode assembly 2. This allows for more precise control of the timing of liquid storage component 3 rupture and electrolyte replenishment, ensuring that the liquid storage component 3 is replenished during its expected service life.

[0060] Specifically, the assembly ratio of electrode assembly 2 to housing 1 is in the range of 85% to 93%, and the distance t between liquid storage component 3 and electrode assembly 2 is the size of the remaining space on one side of the expansion groove 102 after electrode assembly 2 is assembled.

[0061] In some specific embodiments, along the Z direction, the cavity size of the housing 1 is 20mm, the assembly ratio of the electrode group 2 is 90%, and the size ratio of the remaining space on one side of the expansion groove 102 is 5%, that is, the distance between the liquid storage component 3 and the electrode group 2 is t = 1mm.

[0062] In some embodiments, the first surface of the liquid storage component 3 is fixedly connected to the bottom wall of the expansion groove 102 by an adhesive layer 4, and the second surface of the liquid storage component 3 faces the electrode group 2.

[0063] Fixing the liquid storage component 3 to the bottom wall of the expansion groove 102 can prevent the liquid storage component 3 from shifting or shaking inside the housing 1, and prevent the liquid storage component 3 from breaking prematurely due to external force.

[0064] Furthermore, the adhesive layer 4 is made of an electrolyte-resistant material.

[0065] In some embodiments, in the initial state after assembly, the second surface of the liquid reservoir 3 does not protrude from the inner surface of the first sidewall 101 along the Z direction.

[0066] Specifically, the liquid storage component 3 is placed inside the expansion groove 102.

[0067] In some embodiments, the liquid storage component 3 is a sealed container made of micro-nano films.

[0068] The electrolyte reservoir 3 is a sealed container in which electrolyte is stored. In the early or middle stages of battery use, if the electrode assembly 2 does not expand or the pressure exerted on the electrolyte reservoir 3 by the expansion does not reach the pressure threshold, the electrolyte reservoir 3 will not rupture and will still isolate the pre-stored electrolyte from the casing 1 and the electrode assembly 2.

[0069] The liquid storage component 3 is made of materials including PE, PC or PP.

[0070] The electrolyte storage device 3 is an integrated structure. The interior of the electrolyte storage device 3 can contain electrolyte. The electrolyte storage device 3 is composed of micro-nano films, which have a certain structural strength. At the same time, in the later stage of battery use, as the battery expands, the film can be directionally ruptured under the influence of expansion force, so as to replenish electrolyte inside the battery and further improve battery performance.

[0071] In some embodiments, the pressure threshold is P, in MPa, which satisfies: 0.15MPa≤P≤0.4MPa.

[0072] Specifically, the opening pressure of the explosion-proof valve of the battery cell is P1, which is between 0.4 MPa and 1.2 MPa. The pressure threshold for the rupture of the liquid reservoir 3 is less than the opening pressure of the explosion-proof valve, i.e., P < P1. The pressure threshold for the rupture of the liquid reservoir 3 is controlled between 0.15 MPa and 0.4 MPa. Specifically, the timing of liquid replenishment can be determined based on the battery cell's capacity, usage requirements, and cycle life, thus determining the pressure threshold for the rupture of the liquid reservoir 3.

[0073] According to an embodiment of the present invention, a second aspect also provides a battery pack comprising multiple battery cells as described in any of the above embodiments. In some embodiments, multiple battery cells are bonded and fixed together with their large surfaces adjacent.

[0074] Since the battery pack includes the battery cells and has all the technical benefits of the battery cells, it will not be elaborated here.

[0075] Although embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A battery cell, characterized in that, include: A housing having a cavity and at least one open end; at least one expansion groove is provided on any side wall of the housing, the expansion groove communicating with the cavity of the housing; A pole assembly, wherein the pole assembly is disposed within the cavity of the housing; An electrolyte reservoir is disposed within the expansion groove and faces the electrode assembly. The electrolyte reservoir stores electrolyte. After the electrode assembly expands, it applies expansion pressure to the electrolyte reservoir. The electrolyte reservoir is adapted to rupture when the expansion pressure reaches a pressure threshold to release the electrolyte. A cover plate assembly is disposed at the open end of the housing, and encapsulates the electrolyte, the electrode assembly and the liquid storage device within the housing.

2. The battery cell according to claim 1, characterized in that, The housing includes two opposing first sidewalls, the thickness of which is h in mm, and the depth of the expansion groove is H in mm, satisfying: 0.5 ≤ H / h ≤ 2.

3. The battery cell according to claim 2, characterized in that, It also satisfies: 0.25mm≤h≤0.8mm.

4. The battery cell according to any one of claims 1 to 3, characterized in that, The shell has two open ends along the X direction. The minimum distance between the expansion groove and any open end of the shell along the X direction is L, in mm, and L≥10mm.

5. The battery cell according to any one of claims 1 to 3, characterized in that, In the initial state after assembly, along the Z direction, the size of the cavity of the housing is T in mm, and the minimum distance between the liquid storage component and the electrode assembly is t in mm, where 0.035≤t / T≤0.

075.

6. The battery cell according to claim 2 or 3, characterized in that, The first surface of the liquid storage component is fixedly connected to the bottom wall of the expansion groove by an adhesive layer, and the second surface of the liquid storage component faces the electrode assembly.

7. The battery cell according to claim 6, characterized in that, In the initial state after assembly, along the Z direction, the second surface of the liquid reservoir does not protrude from the inner surface of the first sidewall.

8. The battery cell according to any one of claims 1 to 3, characterized in that, The liquid storage device is a sealed container made of micro-nano films.

9. The battery cell according to any one of claims 1 to 3, characterized in that, The pressure threshold is P, in MPa, and satisfies: 0.15MPa≤P≤0.4MPa.

10. A battery pack, characterized in that, It includes the battery cells according to any one of claims 1 to 9.

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