Battery cell, battery pack and energy storage device

Abstract

The embodiment of the utility model provides a battery cell, a battery pack and an energy storage device, the battery cell comprises a shell, a top cover, a pole piece and an electrolyte, the top cover covers the shell in a sealing manner, a sealing cavity is defined by the top cover and the shell, the pole piece is accommodated in the sealing cavity, and the electrolyte is accommodated in the sealing cavity; the shell comprises an outer layer, an insulating layer and an inner metal layer for accommodating the electrolyte and the pole piece, the insulating layer is positioned between the outer layer and the inner metal layer and is in sealed connection with the inner metal layer, and the wear resistance of the outer layer is higher than that of the insulating layer. According to the battery cell, liquid leakage of the shell can be effectively avoided, and the use safety performance of the battery cell is ensured.

Description

Technical Field

[0001] The present application relates to the technical field of batteries, and in particular to a battery cell, a battery pack and an energy storage device. Background Art

[0002] Battery cells are widely used in multiple industries, such as energy storage and automobile fields. However, battery cells in related technologies often have the problem of short circuit between the battery cell shell and the negative electrode sheet or negative electrode column of the battery cell during use, which leads to corrosion of the battery cell shell and leakage. After the battery cell leaks, it will further cause short circuit and leakage of other battery cells, making it impossible to ensure the safety of the battery cell. Utility Model Content

[0003] The embodiments of the present application provide a battery cell, a battery pack and an energy storage device to improve the safety performance of the battery cell.

[0004] In the first aspect, an embodiment of the present application provides a battery cell, which includes a shell, a top cover, a pole piece and an electrolyte. The top cover is sealed on the shell and forms a sealed cavity with the shell. The pole piece is accommodated in the sealed cavity, and the electrolyte is accommodated in the sealed cavity; the shell includes an outer layer, an insulating layer and an inner metal layer for accommodating the electrolyte and the pole piece, the insulating layer is located between the outer layer and the inner metal layer, at least a portion of the inner metal layer is in contact with the electrolyte, the insulating layer is sealed and connected to at least a portion of the inner metal layer, and the outer layer has stronger wear resistance than the insulating layer.

[0005] In this embodiment, since the insulating layer and the inner metal layer are sealed and connected, the sealing performance of the contact position between the insulating layer and the inner metal layer can be guaranteed. When the inner metal layer is short-circuited with the negative electrode sheet, due to the potential difference between the inner metal layer and the negative electrode sheet, the electrons between the negative electrode sheet and the inner metal layer are connected, and since the inner metal layer is in direct contact with the electrolyte, the ions between the inner metal layer and the electrolyte are connected, so that the cations of the electrolyte are embedded in the inner metal layer. However, since the insulating layer is located between the outer layer and the inner metal layer, the insulating layer is sealed and connected to at least part of the inner metal layer in contact with the electrolyte, and the insulating layer has a sealing effect on the inner metal layer, so that the air outside the battery cell will not contact the inner metal layer, so that the inner metal layer embedded with cations can be prevented from contacting the air outside the battery cell and pulverizing, so that the inner metal layer can be prevented from leaking, that is, the electrolyte cannot pass through the inner metal layer to reach the insulating layer and corrode the insulating layer, nor can it reach the outer layer and corrode the outer layer. In addition, when the negative pole is overlapped with the inner metal layer, the inner metal layer can be prevented from contacting with the outside air because the insulating layer is sealed and connected with the inner metal layer, thereby preventing the inner metal layer embedded with cations from being pulverized and preventing the inner metal layer from leaking. This can effectively improve the safety performance of the battery cell in this embodiment. In addition, since the outer layer has a stronger wear resistance than the insulating layer, the outer layer can protect the insulating layer from being worn and damaged, thereby ensuring that the insulating layer can be stably sealed and connected with the inner metal layer to prevent the inner metal layer from contacting with the air outside the battery cell.

[0006] In some embodiments, the top cover is sealed on the inner metal layer and forms a sealed cavity with the inner metal layer. In this embodiment, since the inner metal layer is made of metal material, the strength of the inner metal layer is relatively high. By connecting the top cover to the inner metal layer, the connection strength between the top cover and the inner metal layer can be effectively ensured to improve the overall strength of the battery cell.

[0007] In some embodiments, the inner metal layer, the insulating layer and the outer layer all include a bottom wall arranged opposite to the top cover and a plurality of side walls connected to the periphery of the bottom wall. The bottom wall of the inner metal layer, the bottom wall of the insulating layer and the bottom wall of the outer layer are stacked in sequence from the inner side to the outer side of the sealed cavity. The side walls of the inner metal layer, the side walls of the insulating layer and the side walls of the outer layer are stacked in sequence from the inner side to the outer side of the sealed cavity. The direction perpendicular to the bottom wall is the height direction of the shell. The plurality of side walls of the inner metal layer are connected between the top cover and the bottom wall of the inner metal layer. With the bottom wall of the outer layer as a reference, in the height direction of the shell, the side walls of the insulating layer and the side walls of the outer layer are lower than the side walls of the inner metal layer. In this embodiment, since the side walls of the insulating layer and the side walls of the outer layer are lower than the side walls of the inner metal layer, the top cover can be welded to the inner metal layer by flat welding, and the insulating layer and the outer layer will not be affected by the high welding temperature.

[0008] In some embodiments, with the bottom wall of the outer layer as a reference, in the height direction of the shell, the height of the side wall of the insulating layer is higher than the height of the electrolyte in the sealed cavity. In this embodiment, since the height of the side wall of the insulating layer is higher than the height of the electrolyte in the sealed cavity, the positions where the inner metal layer contacts the electrolyte can be covered by the insulating layer, that is, the parts of the inner metal layer that can be embedded with cations are sealed and covered by the insulating layer, so that the positions where the inner metal layer contacts the electrolyte will not contact the space outside the sealed cavity of the battery cell, thereby losing the conditions for being pulverized, so that the positions where the inner metal layer contacts the electrolyte can avoid leakage. The part of the inner metal layer that is not in contact with the electrolyte will not form an ion channel, so that corrosion will not occur. Therefore, any position of the inner metal layer can effectively prevent leakage, and improve the anti-leakage ability of the battery cell when the negative electrode and the shell are short-circuited.

[0009] In some embodiments, with the bottom wall of the outer layer as a reference, in the height direction of the housing, the side wall of the outer layer is not lower than the side wall of the insulating layer. In this embodiment, the side wall of the outer layer is not lower than the side wall of the insulating layer, so that the outer layer can fully and effectively protect the insulating layer. To prevent the insulating layer from being worn and damaged. Thus, the stability of the insulating layer sealing and connecting the inner metal layer is ensured. In addition, the provision of the outer layer can also improve the overall strength of the housing.

[0010] In some embodiments, the outer layer is a metal layer, and the inner metal layer and the outer layer are insulated. In this embodiment, since the inner metal layer and the outer layer are insulated, the outer layer is not charged like the inner metal layer, and when the outer layers of adjacent battery cells are in contact with each other, a short circuit will not occur between the adjacent battery cells, and the outer layer will not be corroded.

[0011] In some embodiments, the peripheral sealing of the top cover is sealed on the inner metal layer and is spaced apart from the outer layer. In this embodiment, when the outer layer is made of metal material, since the outer layer and the top cover are not connected, when the top cover and the inner metal layer are charged, the outer layer can be prevented from being charged, so that when there is leakage or accumulation of liquid from some cells in the outer shell of the battery pack, the outer layer can be prevented from being corroded because no electron channel is formed.

[0012] In some embodiments, the thickness of the inner metal layer is greater than the thickness of the outer layer. In this embodiment, since the thickness of the inner metal layer is greater than the thickness of the outer layer, the overall strength of the inner metal layer is greater, and the strength and connection stability when connected to the top cover are also higher. In addition, since the inner metal layer is in direct contact with the electrolyte, the greater the thickness of the inner metal layer, the probability of leakage of the inner metal layer can be further effectively reduced.

[0013] In some embodiments, the thickness of the insulating layer is 0.3 mm-1 mm. In this embodiment, the thickness of the insulating layer is set within this range to ensure that the insulating layer can play both an insulating role and a sealing role for the inner metal layer.

[0014] In some embodiments, the thickness of the outer layer is 0.2 mm-0.5 mm. In this embodiment, the thickness of the outer layer is set within this range, which is sufficiently wear-resistant and can effectively ensure the protection of the insulating layer to prevent the insulating layer from being worn.

[0015] In some embodiments, the thickness of the inner metal layer is 0.4 mm-1 mm. In this embodiment, the thickness of the inner metal layer is set within this range, which can effectively ensure the strength of the inner metal layer to accommodate the electrode and the electrolyte. In addition, within this range, the strength of the inner metal layer is sufficient to support the connection with the top cover, and can also ensure the stability of the connection between the top cover and the inner metal layer.

[0016] In this embodiment, in addition to ensuring the basic functional requirements of the outer layer, the insulating layer and the inner metal layer, the thickness of the housing can be prevented from being too large. Moreover, due to the addition of the insulating layer, the overall weight of the housing can be effectively reduced.

[0017] In some embodiments, the top cover is sealed on the outer layer and forms a sealed cavity with the outer layer. In this embodiment, when the top cover is connected to the outer layer, the top cover and the outer layer will not contact the electrolyte, so when the outer layers of the adjacent battery cells are overlapped by conductive debris, the outer layers of the battery cells will not be corroded.

[0018] In some embodiments, the top cover is spaced apart from the inner metal layer. Since the top cover is spaced apart from the inner metal layer, and the inner metal layer and the outer layer are separated by an insulating layer, when conductive debris between adjacent cells overlaps the outer layer or the top cover of the cell, the inner metal layer will not participate in the electronic conduction, so the inner metal layer will not be corroded, and thus the inner metal layer and the outer layer in this embodiment will not be corroded. Thus, the safety performance of the cell can be effectively guaranteed.

[0019] In some embodiments, with the bottom wall of the outer layer as a reference, in the height direction of the housing, the side walls of the insulating layer and the side walls of the inner metal layer are lower than the side walls of the outer layer. Since the side walls of the insulating layer and the side walls of the inner metal layer are lower than the side walls of the outer layer, the contact between the inner metal layer and the top cover can be effectively avoided, and the electrical connection between the inner metal layer and the top cover can be prevented.

[0020] In a second aspect, an embodiment of the present application provides a battery pack, comprising a housing and a plurality of battery cells as described in any one of the first aspects above, wherein the plurality of battery cells are stacked in the housing.

[0021] In a third aspect, an embodiment of the present application provides an energy storage device, comprising a cabinet and a plurality of battery packs as described in the second aspect above, wherein the plurality of battery packs are stacked in the cabinet. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art are briefly introduced below.

[0023] Figure 1 A simple structural schematic diagram of an energy storage device provided in an embodiment of the present application;

[0024] Figure 2 A schematic diagram of the structure of a battery pack provided in an embodiment of the present application;

[0025] Figure 2A An implementation method of arranging multiple battery cells in the related art;

[0026] Figure 3 A schematic diagram of the structure of a battery cell provided in an embodiment of the present application;

[0027] Figure 4 for Figure 3 An exploded schematic diagram of a battery cell in an embodiment;

[0028] Figure 5 for Figure 4 A local enlarged structural diagram at A in FIG.

[0029] Figure 6 for Figure 3 An exploded schematic diagram of a shell of a battery cell in an embodiment;

[0030] Figure 7 for Figure 3 A schematic diagram of the height of the electrolyte and the height of the side wall of the shell when the shell of the battery cell contains the electrolyte;

[0031] Figure 8 for Figure 3 A top view and a partial enlarged view of the casing of the battery cell in the embodiment;

[0032] Fig. 9 For two adjacent Figure 3 Schematic diagram of the structure when the top cover of the battery cell is overlapped;

[0033] Fig.10 For two adjacent Figure 3 A schematic diagram of the structure of a medium cell, where the top cover of one cell and the outer layer of another cell are overlapped;

[0034] Fig.11 For two adjacent Figure 3 Schematic diagram of the structure when the outer layer of the battery cell is overlapped;

[0035] Fig.12 Based on Figure 3 A schematic diagram of a partial structure of a shell of another battery cell that is an extension of the battery cell in the embodiment.

[0036] Description of reference numerals:

[0037] Z, height direction of the shell;

[0038] 1. Energy storage device; 2. Cabinet; 3. Battery pack; 4. Housing; 5. Battery cell; 5a. First battery cell; 5b. Second battery cell; 6. Sealed cavity;

[0039] 10. Shell; 101. Opening; 11. Inner metal layer; 111. Bottom wall of the inner metal layer; 112. Side wall of the inner metal layer; 12. Insulating layer; 121. Bottom wall of the insulating layer; 122. Side wall of the insulating layer; 13. Outer layer; 131. Bottom wall of the outer layer; 132. Side wall of the outer layer;

[0040] 20. Top cover; 21. Pressure relief port;

[0041] 30. Electrolyte;

[0042] 40. Pole piece;

[0043] 51. Positive pole; 52. Negative pole. DETAILED DESCRIPTION

[0044] The following first explains some terms involved in the embodiments of the present application.

[0045] The terms "first", "second", "third", "fourth", etc. in the specification and claims of the embodiments of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can, for example, be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0046] In this specification, the terms "perpendicular", "parallel", etc. are explained.

[0047] Vertical: The verticality defined in this application is not limited to an absolute vertical intersection relationship (angle of 90 degrees). It allows for non-absolute vertical intersection relationships caused by factors such as assembly tolerance, design tolerance, and influence of structural flatness. It also allows for errors in a small angle range. For example, the assembly error range of 80 to 100 degrees can be understood as a vertical relationship.

[0048] Parallelism: The parallelism defined in this application is not limited to absolute parallelism. This definition of parallelism can be understood as basic parallelism, which allows for situations where the two are not absolutely parallel due to factors such as assembly tolerance, design tolerance, and the influence of structural flatness. These situations will lead to the sliding fitting portion and the first door panel not being absolutely parallel, but this application also defines this situation as parallelism.

[0049] Figure 1 A simple structural schematic diagram of an energy storage device 1 provided in an embodiment of the present application.

[0050] Reference Figure 1 The energy storage device 1 includes a cabinet 2 and a plurality of battery packs 3 disposed in the cabinet 2. The plurality of battery packs 3 are stacked in the cabinet 2. The plurality of battery packs 3 can store or output electrical energy.

[0051] To facilitate understanding of the energy storage device 1 provided in the embodiment of the present application, its application scenario is first introduced below. The energy storage device 1 is a system that can store electrical energy through a certain medium and release the stored energy to generate electricity when needed. It can be used as a load balancing device and a backup power supply in industrial and commercial parks, large ground power supply stations, or photovoltaic storage systems. The application of the energy storage device 1 is briefly described using the photovoltaic storage system scenario as an example. The photovoltaic storage system generally includes a photovoltaic module, an energy storage converter, an energy storage device 1, and a grid-connected inverter. Among them, the photovoltaic module can convert light energy into electrical energy in the form of direct current and output it to the grid-connected inverter; the grid-connected inverter can convert electrical energy in the form of direct current into electrical energy in the form of alternating current, and transmit the electrical energy in the form of alternating current to the grid, thereby realizing the grid connection of the photovoltaic storage system. The energy storage device 1 can store a portion of the electrical energy output by the photovoltaic inverter when the electrical energy generated by the photovoltaic module exceeds the demand for electrical energy of the grid, and when the electrical energy output by the photovoltaic module cannot meet the demand for electrical energy of the grid, the stored electrical energy is output to the grid to provide a more stable DC source for the grid. The energy storage converter can convert the grid voltage into the supply voltage of the energy storage device 1, or convert the voltage stored in the energy storage device 1 into the grid voltage and output it to the grid.

[0052] In addition, according to the different power consumption requirements of the application scenarios of the energy storage device 1, the energy storage device 1 can also be divided into a module-level energy storage device 1, a cabinet-level energy storage device 1 and a container-level energy storage device 1.

[0053] Figure 2 A schematic diagram of the structure of a battery pack 3 provided in an embodiment of the present application. Figure 2 The battery pack 3 in the embodiment can be used not only Figure 1 The energy storage device 1 in the embodiment can also be applied to the vehicle field or other fields that require the use of a battery pack 3 .

[0054] Reference Figure 2The battery pack 3 includes a housing 4 and a plurality of battery cells 5 in the housing 4, wherein the plurality of battery cells 5 are stacked and arranged in the housing 4. It can be understood that the plurality of battery cells 5 can be arranged in one row or in multiple rows.

[0055] In some implementations, the plurality of battery cells 5 are connected in series. In some other implementations, the plurality of battery cells 5 may be connected in parallel, or some of the battery cells 5 may be connected in series and some of the battery cells 5 may be connected in parallel.

[0056] In some embodiments, the shell 10 of the battery cell 5 is a metal shell 10, such as an aluminum shell. It is understood that the battery cell 5 in the present application at least includes the metal shell 10 to provide sufficient strength to form the components in the battery cell 5.

[0057] In some embodiments, when the shell 10 of the battery cell 5 includes an aluminum shell, in order to improve the problem that the aluminum shell is easily corroded by the electrolyte in the battery cell 5, the aluminum shell is charged, which can improve the problem of cations in the electrolyte being embedded in the aluminum shell. For example, for the lithium-ion battery cell 5, the problem of lithium ions being embedded in the aluminum shell to form lithium-embedded aluminum compounds can be effectively improved.

[0058] In some embodiments, the battery core 5 is roughly in the shape of a rectangular parallelepiped. Of course, in other embodiments, the battery core 5 may also be in other flat structures.

[0059] Figure 2A This is an implementation method of arranging multiple battery cells 5 in the related art.

[0060] Reference Figure 2A , multiple battery cells 5 are connected in series, and the shells 10 of the multiple battery cells 5 are all charged aluminum shells, the pole core inside the aluminum shell is covered with Mylar film, and the outside of the aluminum shell is covered with blue film. The related battery cells 5 often have the following problems during use:

[0061] Problem 1: The negative electrode sheet inside the battery cell 5 overlaps with the aluminum shell. For example, there are gaps and through holes at the bottom of the Mylar film, which may cause the powder that falls off the battery cell 5 during the cycle to overlap with the aluminum shell, thereby forming negative short corrosion. For example, when there are process fluctuations and design defects, it is easy to cause insulation protection failure, thereby forming an overlap between the negative electrode sheet and the aluminum shell. When the overlap occurs, lithium-aluminum alloy begins to form inside the aluminum shell (taking the lithium battery cell 5 as an example). After the lithium-aluminum alloy penetrates the entire aluminum shell, the lithium-aluminum alloy comes into contact with the air and then pulverizes. The electrolyte overflows through the pulverized position to form a leakage problem. In addition, the alkaline substance formed after the lithium-aluminum alloy reacts with the air is corrosive to the insulating film, which will cause the PET layer of the insulating film base film to dissolve, and its wear resistance and other properties will be significantly reduced.

[0062] Problem 2: During the assembly of the battery pack 3, when the battery cells 5 are connected in series and parallel, the insulation gap of the battery cells 5 is insufficient, resulting in contact between the aluminum shells of the battery cells 5 (especially the laser welding seam of the shell cover), thereby causing negative short corrosion. For example, during the laser welding of the battery pack 3, the metal chips of welding slag splash and pierce the blue film of the battery cell 5, resulting in overlap between the battery cells 5 and the insulation failure between the battery cells 5. Since the aluminum shell of the battery cell 5 is charged and the aluminum shell of the battery cell 5 contains electrolyte, the aluminum shell of the battery cell 5 will undergo a chemical reaction, causing lithium-aluminum alloy to begin to form inside the aluminum shell. After the lithium-aluminum alloy penetrates the entire aluminum shell, the lithium-aluminum alloy comes into contact with the air and then pulverizes. The electrolyte overflows through the pulverized position to cause leakage. In addition, when the negative electrode (negative electrode sheet or negative electrode column 52) of a certain battery cell 5 overlaps the aluminum shell of the battery cell 5, short circuit and leakage will also occur. When the negative electrode column 52 of a certain battery cell 5 overlaps with the aluminum shell of an adjacent battery cell 5, a short circuit and leakage problem may also occur.

[0063] Figure 3 A schematic diagram of the structure of a battery cell 5 provided in an embodiment of the present application; Figure 4 for Figure 3 An exploded schematic diagram of the battery cell 5 in the embodiment. Figure 3 The battery cell 5 in the embodiment can be applied to Figure 2 In the battery pack 3 in the embodiment.

[0064] Reference Figure 3 and Figure 4 The battery cell 5 includes a shell 10, a top cover 20, an electrolyte 30 and a pole piece 40. The top cover 20 is sealed on the shell 10 to form a sealed cavity 6. The pole piece 40 is accommodated in the sealed cavity 6. The electrolyte 30 of the battery cell 5 is also accommodated in the sealed cavity 6.

[0065] The housing 10 includes an opening 101 , and the top cover 20 is sealed on the opening 101 of the housing 10 , thereby forming a sealed cavity 6 by the top cover 20 and the housing 10 .

[0066] The top cover 20 is used to be provided with a positive pole 51 and a negative pole 52 , and a pressure relief port 21 may also be provided on the top cover 20 .

[0067] The electrode sheet 40 includes a positive electrode sheet, a negative electrode sheet, and a separator between the positive electrode sheet and the negative electrode sheet. The positive electrode sheet, the negative electrode sheet, and the separator can be wound to form a core, or can be stacked to form a core. The positive electrode sheet is connected to the positive electrode column 51, and the negative electrode sheet is connected to the negative electrode column 52.

[0068] Figure 3The shell 10 of the battery cell 5 in the embodiment adopts a multi-layer structure, wherein the layer directly in contact with the electrolyte 30 is the inner metal layer 11, and the layer in contact with the inner metal layer 11 is the insulating layer 12, and the insulating layer 12 is sealed and in contact with the inner metal layer 11. The inner metal layer 11 provides sufficient strength to support the electrode core and accommodate the electrolyte 30, and the insulating layer 12 is used to prevent the alloy formed after the inner metal layer 11 and the negative electrode sheet short-circuit further contact with the air and pulverize, thereby preventing leakage. The insulating layer 12 in this embodiment not only has an insulating effect to prevent the inner metal layer 11 from electrically contacting the outer shell 4 of the battery pack 3 and the shells 10 of other battery cells 5, but also prevents the inner metal layer 11 from contacting the air outside the battery cell 5.

[0069] It is understandable that the number of layer structures of the shell 10 of the battery cell 5 may be more than the inner metal layer 11 and the insulating layer 12 , and may include more layer structures.

[0070] In some embodiments, the positive electrode sheet and the shell 10 are electrically connected to increase the potential of the shell 10 to effectively prevent the potential of the shell 10 from being lower than its lithium insertion potential, thereby improving the problem that the anode ions are easily embedded in the shell 10 to form an alloy.

[0071] In some embodiments, the battery cell 5 is a lithium-ion battery cell 5, such as a lithium iron phosphate battery cell 5 or a ternary lithium battery cell 5. The positive electrode and the inner metal layer 11 are electrically connected to increase the potential of the inner metal layer 11 to improve the problem of lithium ions being embedded in the inner metal layer 11 to form an alloy.

[0072] It is understandable that, in some other embodiments, the battery cell 5 may also be a sodium ion battery cell 5 or other battery cells 5 .

[0073] Figure 5 for Figure 4 A local enlarged structural diagram at A in FIG. Figure 6 for Figure 3 The exploded schematic diagram of the housing 10 of the battery cell 5 in the embodiment. It should be noted that: Figure 6 Although this is an exploded view of the housing 10, it does not mean that the housing 10 in this application must be similar to Figure 6 Due to the difference in process and material, the housing 10 in the present application may not be disassembled in the same way as in the present invention. Figure 6 In the same way, some cases can also be decomposed like Figure 6 Same decomposition. Figure 6 The exploded view of the housing 10 in the embodiment is for clearly showing the specific structure of the housing 10 .

[0074] Reference Figure 5 and Figure 6In some embodiments, the housing 10 includes an outer layer 13, an inner metal layer 11, and an insulating layer 12 located between the outer layer 13 and the inner metal layer 11, and the insulating layer 12 is sealed and connected at least to the portion of the inner metal layer 11 that contacts the electrolyte 30, and the inner metal layer 11 is used to contain the electrolyte 30 and the pole piece 40. Since the insulating layer 12 is sealed and connected to the inner metal layer 11, the sealing performance of the contact position between the insulating layer 12 and the inner metal layer 11 can be guaranteed. Of course, the insulating layer 12 can also be sealed and connected to the outer layer 13 to ensure the sealing performance of the contact position between the insulating layer 12 and the outer layer 13.

[0075] In the present embodiment, when the inner metal layer 11 is short-circuited with the negative electrode sheet, there is a potential difference between the inner metal layer 11 and the negative electrode sheet, so that electrons are conducted between the negative electrode sheet and the inner metal layer 11. Since the inner metal layer 11 is in direct contact with the electrolyte 30, ions are conducted between the inner metal layer 11 and the electrolyte 30, so that cations of the electrolyte 30 are embedded in the inner metal layer 11. However, since the insulating layer 12 is located between the outer layer 13 and the inner metal layer 11, and the insulating layer 12 is at least in contact with the portion of the inner metal layer 11 that is in contact with the electrolyte 30, the insulating layer 12 has a sealing effect on the inner metal layer 11, so that the air outside the battery cell 5 will not contact the inner metal layer 11, so that the inner metal layer 11 embedded with cations can be prevented from contacting the air outside the battery cell 5 and being pulverized, so that leakage of the inner metal layer 11 can be prevented. That is, the electrolyte 30 cannot pass through the inner metal layer 11 to reach the insulating layer 12 and corrode the insulating layer 12, nor can it reach the outer layer 13 and corrode the outer layer 13.

[0076] In addition, when the negative electrode column 52 overlaps the inner metal layer 11, the insulating layer 12 is sealed and connected to the inner metal layer 11, so that the inner metal layer 11 can be prevented from contacting the external air, thereby preventing the inner metal layer 11 embedded with cations from being pulverized and preventing the inner metal layer 11 from leaking.

[0077] Therefore, the shell 10 in this embodiment effectively improves the corrosion resistance when the negative electrode (negative electrode sheet or negative electrode column 52 ) of the battery cell 5 is short-circuited with the shell 10 .

[0078] In order to ensure the sealing connection between the insulating layer 12 and the inner metal layer 11, the following methods can be used:

[0079] Method 1:

[0080] 1. The insulating layer 12 is bonded to the inner metal layer 11 having a certain thickness by spraying. The organic matter of the insulating layer 12 includes one or more combinations of resin, polyurethane, polyvinylidene fluoride (PVDF), and polytetrafluoroethylene (PTFE).

[0081] 2. The outer layer 13 is evenly attached to the outside of the insulating layer 12 by evaporation (when the outer layer 13 is made of metal material) to ensure the uniformity of the attachment of the outer layer 13, or the outer layer 13 is evenly attached to the outside of the insulating layer 12 by spraying (when the outer layer 13 is made of non-metallic material).

[0082] 3. The three-layer structure housing 10 is used for assembling the battery cell 5 , and is welded with the top cover 20 to form a new battery cell 5 .

[0083] Method 2:

[0084] 1. Stamp a metal material (such as aluminum) into a metal structure with a gap in the middle (in this case, the outer layer 13 and the inner metal layer 11 are made of the same metal material), wherein the size of the middle gap is 0.4-1 mm, the thickness of the inner aluminum layer is 0.4-1 mm, and the outer aluminum layer is 0.3-0.5 mm.

[0085] 2. The insulating layer 12 is cast in the gap between the outer layer 13 and the inner metal layer 11 by injection molding. The organic matter of the insulating layer 12 includes one or more combinations of resin, polyurethane, polyvinylidene fluoride (PVDF), and polytetrafluoroethylene (PTFE).

[0086] 3. After the injection molding is completed, the connection between the outer layer 13 and the inner metal layer 11 is removed to obtain a new shell 10 structure in which the inner metal layer 11 and the outer layer 13 are insulated from each other by the insulating layer 12.

[0087] 4. The three-layer structure housing 10 is used for assembling the battery cell 5 , and is welded with the top cover 20 to form a new battery cell 5 .

[0088] It is understandable that the sealed connection between the inner metal layer 11 and the insulating layer 12 can also be ensured by other means, such as clamping the insulating layer 12 by the outer layer 13 and the inner metal layer 11 to achieve a sealed connection between the insulating layer 12 and the inner metal layer 11 .

[0089] In some embodiments, the outer layer 13 has stronger wear resistance than the insulating layer 12 , so that the insulating layer 12 can be protected from being worn and damaged by the outer layer 13 , thereby ensuring that the insulating layer 12 can be stably sealed and connected to the inner metal layer 11 to prevent the inner metal layer 11 from contacting the air outside the battery cell 5 .

[0090] In some embodiments, the inner metal layer 11 is an aluminum layer or an aluminum alloy layer to ensure sufficient strength to accommodate the electrolyte 30 and the pole piece 40, and the aluminum material has high heat dissipation and corrosion resistance. It is understandable that in some other embodiments, the inner metal layer 11 can also be made of other materials, such as stainless steel.

[0091] In some embodiments, the insulating layer 12 may be a layered structure formed by a combination of one or more materials such as resin, polyurethane, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), etc. It is understood that any layered structure that can meet the requirements of insulation and seal the inner metal layer 11, and the connection position can prevent the inner metal layer 11 from contacting the air outside the battery cell 5 belongs to the insulating layer 12 in this application.

[0092] In some embodiments, the outer layer 13 has a stronger wear resistance than the insulating layer 12, so as to be able to provide effective wear protection for the insulating layer 12, thereby preventing the insulating layer 12 from being worn and failing to seal the inner metal layer 11 connected thereto.

[0093] In some embodiments, the outer layer 13 may be a metal layer, such as an aluminum layer or an aluminum alloy layer, to improve the overall strength of the housing 10. Of course, in some other embodiments, the housing 4 may also be a non-metal layer, as long as it has high strength, hardness and wear resistance and can effectively protect the insulating layer 12, and the outer layer 13 may be made of other materials within the scope of protection of this application.

[0094] Reference Figure 6 In some embodiments, the inner metal layer 11, the insulating layer 12, and the outer layer 13 all include a bottom wall and a plurality of side walls connected to the periphery of the bottom wall. The bottom wall 111 of the inner metal layer 11, the bottom wall 121 of the insulating layer 12, and the bottom wall 131 of the outer layer 13 are stacked in sequence from the inside to the outside of the sealed cavity 6 to form the bottom wall of the housing 10, and the side wall 112 of the inner metal layer 11, the side wall 122 of the insulating layer 12, and the side wall 132 of the outer layer 13 are stacked in sequence from the inside to the outside of the sealed cavity 6 to form the side wall of the housing 10.

[0095] The direction perpendicular to the bottom wall of the shell 10 is set as the height direction Z of the shell 10. It can be understood that the height direction Z of the shell 10 is also perpendicular to the bottom wall 111 of the inner metal layer 11, the bottom wall 121 of the insulating layer 12 and the bottom wall 131 of the outer layer 13.

[0096] It is understandable that when the battery cell 5 is assembled into the housing 4, the bottom wall of the housing 10 is placed on the bottom wall of the housing 4, and the top cover 20 of the housing 10 faces the top wall of the housing 4. Therefore, under normal placement, since the electrolyte 30 of the battery cell 5 usually does not fill the entire cavity, the electrolyte 30 of the battery cell 5 will contact the bottom wall and the side wall of the housing 10, but will not contact the top cover 20 of the housing 10. The bottom wall of the housing 10 is stacked in sequence by the outer layer 13, the insulating layer 12 and the inner metal layer 11, so that the bottom wall 111 of the inner metal layer 11 can be prevented from being powdered and leaking, and the side wall 112 of the inner metal layer 11 can be prevented from being powdered and leaking. The specific principle can be referred to the above. Since the top cover 20 is not in contact with the electrolyte 30 under normal placement, the top cover 20 will not be corroded. As a result, the corrosion resistance and liquid leakage prevention capabilities of the housing 10 in this embodiment are effectively improved.

[0097] In the height direction Z of the shell 10, the bottom wall 111 of the inner metal layer 11, the bottom wall 121 of the insulating layer 12 and the bottom wall 131 of the outer layer 13 are all arranged opposite to the top cover 20. For example, the bottom wall 111 of the inner metal layer 11, the bottom wall 121 of the insulating layer 12 and the bottom wall 131 of the outer layer 13 can be relatively parallel to the top cover 20 and arranged at intervals. Of course, the bottom wall 111 of the inner metal layer 11, the bottom wall 121 of the insulating layer 12 and the bottom wall 131 of the outer layer 13 can also have a certain angle with the top cover 20.

[0098] In the height direction Z of the shell 10, the top cover 20 and the bottom wall of the shell 10 are respectively connected to the opposite ends of the side wall of the shell 10, wherein the opening 101 of the shell 10 is located at one end of the side wall of the shell 10 away from the bottom wall of the shell 10 in the height direction Z of the shell 10.

[0099] In some embodiments, the opening 101 of the housing 10 is surrounded by one end of the side wall 112 of the inner metal layer 11 away from the bottom wall of the inner metal in the height direction Z of the housing 10, and the top cover 20 is sealed at the opening 101 on the inner metal layer 11, and forms a sealed cavity 6 with the inner metal layer 11. Since the inner metal layer 11 is made of metal material, the strength of the inner metal layer 11 is relatively high. By connecting the top cover 20 to the inner metal layer 11, the connection strength between the top cover 20 and the inner metal layer 11 can be effectively guaranteed, so as to improve the overall strength of the battery cell 5.

[0100] In some embodiments, the outer layer 13 is a metal layer, and the inner metal layer 11 and the outer layer 13 are insulated. Since the inner metal layer 11 and the outer layer 13 are insulated, the outer layer 13 is not charged like the inner metal layer 11, and when the outer layers 13 of adjacent battery cells 5 are in contact with each other, a short circuit will not occur between the adjacent battery cells 5, and the outer layer 13 will not be corroded.

[0101] In some embodiments, the periphery of the top cover 20 is sealed and covered on the inner metal layer 11, and is spaced apart from the outer layer 13. In this embodiment, when the outer layer 13 is made of metal material, since the outer layer 13 and the top cover 20 are not connected, when the top cover 20 and the inner metal layer 11 are charged, the outer layer 13 can be prevented from being charged, so that when there is leakage or accumulation of liquid from some battery cells 5 in the outer shell 4 of the battery pack 3, the outer layer 13 can be prevented from being corroded because no electron channel is formed.

[0102] In some embodiments, the top cover 20 and the inner metal layer 11 are connected by welding.

[0103] In order to improve the welding stability between the inner metal layer 11 and the top cover 20 and reduce the influence on the outer layer 13 and the insulating layer 12, in some embodiments, with the bottom wall 131 of the outer layer 13 as a reference, in the height direction Z of the shell 10, the side wall 122 of the insulating layer 12 and the side wall 132 of the outer layer 13 are both lower than the side wall 112 of the inner metal layer 11. In this embodiment, since the side wall 122 of the insulating layer 12 and the side wall 132 of the outer layer 13 are both lower than the side wall 112 of the inner metal layer 11, the top cover 20 can be welded to the inner metal layer 11 by flat welding, and the insulating layer 12 and the outer layer 13 will not be affected by the high temperature of welding.

[0104] It is understandable that in some other embodiments, with the bottom wall 131 of the outer layer 13 as a reference, the side wall 122 of the insulating layer 12, the side wall 132 of the outer layer 13, and the side wall 112 of the inner metal layer 11 may be flush in the height direction Z of the housing 10. Alternatively, in the height direction Z of the housing 10, the side wall 122 of the insulating layer 12 or the side wall 132 of the outer layer 13 may be higher than the side wall 112 of the inner metal layer 11.

[0105] Figure 7 for Figure 3 Schematic diagram of the height of the electrolyte 30 and the height of the side wall of the shell 10 when the shell 10 of the battery cell 5 contains the electrolyte 30.

[0106] Reference Figure 7In some embodiments, with the bottom wall 131 of the outer layer 13 as a reference, in the height direction Z of the shell 10, the height of the inner metal layer 11 is higher than the height of the insulating layer 12, and the height of the side wall 122 of the insulating layer 12 is higher than the height of the electrolyte 30 in the sealed cavity 6. In this embodiment, since the height of the side wall 122 of the insulating layer 12 is higher than the height of the electrolyte 30 in the sealed cavity 6, the positions where the inner metal layer 11 contacts the electrolyte 30 can be covered by the insulating layer 12, that is, the parts of the inner metal layer 11 that can be embedded with cations are sealed and covered by the insulating layer 12, so that the positions where the inner metal layer 11 contacts the electrolyte 30 will not contact the space outside the sealed cavity 6 of the battery cell 5, thereby losing the conditions for being pulverized, so that the positions where the inner metal layer 11 contacts the electrolyte 30 can avoid leakage. Since the parts of the inner metal layer 11 that are not in contact with the electrolyte 30 will not form ion channels, corrosion will not occur. Therefore, any position of the inner metal layer 11 can effectively prevent leakage, thereby improving the anti-leakage capability of the battery cell 5 when the negative electrode and the shell 10 are short-circuited.

[0107] In some embodiments, with the bottom wall 131 of the outer layer 13 as a reference, in the height direction Z of the housing 10, the side wall 132 of the outer layer 13 is not lower than the side wall 122 of the insulating layer 12. In this embodiment, the side wall 132 of the outer layer 13 is not lower than the side wall 122 of the insulating layer 12, so that the outer layer 13 can fully and effectively protect the insulating layer 12. To prevent the insulating layer 12 from being worn and damaged. Thus, the stability of the insulating layer 12 sealing and connecting the inner metal layer 11 is ensured. In addition, the provision of the outer layer 13 can also improve the overall strength of the housing 10.

[0108] It is understandable that, in some other embodiments, the outer layer 13 may be provided at a position where the insulating layer 12 is easily worn.

[0109] Figure 8 for Figure 3 A top view and a partial enlarged view of the housing 10 of the battery cell 5 in the embodiment.

[0110] Reference Figure 8 In some embodiments, the thickness H1 of the inner metal layer 11 is greater than the thickness H3 of the outer layer 13. Since the thickness H1 of the inner metal layer 11 is greater than the thickness H3 of the outer layer 13, the overall strength of the inner metal layer 11 is greater, and the strength and connection stability when connected to the top cover 20 are also higher. In addition, since the inner metal layer 11 is in direct contact with the electrolyte 30, the greater the thickness H1 of the inner metal layer 11, the more effectively the probability of leakage of the inner metal layer 11 can be reduced.

[0111] In some implementations, the thickness H2 of the insulating layer 12 is 0.3 mm-1 mm, such as 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.8 mm or 1.0 mm, etc. In this embodiment, the thickness H2 of the insulating layer 12 is set within this range to ensure that the insulating layer 12 can both play an insulating role and a sealing role for the inner metal layer 11.

[0112] The thickness H3 of the outer layer 13 is 0.2 mm-0.5 mm, for example, 0.2 mm, 0.3 mm, 0.4 mm or 0.5 mm, etc. When the outer layer 13 is within this range, it is sufficiently wear-resistant and can effectively protect the insulating layer 12 to prevent the insulating layer 12 from being worn.

[0113] The thickness H1 of the inner metal layer 11 is 0.4 mm-1 mm, for example, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.8 mm or 1.0 mm, etc. When the inner metal layer 11 is within this range, the strength of the inner metal layer 11 can be effectively guaranteed to accommodate the pole piece 40 and the electrolyte 30. In addition, within this range, the strength of the inner metal layer 11 is sufficient to support the connection with the top cover 20, and the stability of the connection between the top cover 20 and the inner metal layer 11 can also be guaranteed.

[0114] In this embodiment, in addition to ensuring the basic functional requirements of the outer layer 13, the insulating layer 12 and the inner metal layer 11, the thickness of the housing 10 can be prevented from being too large. In addition, due to the addition of the insulating layer 12, the overall weight of the housing 10 can be effectively reduced.

[0115] When a relatively large single cell 5 is required, the thickness H3 of the outer layer 13 of the cell 5 , the thickness H2 of the insulating layer 12 , and the thickness H1 of the inner metal layer 11 can all be increased.

[0116] based on Figure 3 In the embodiment, when adjacent battery cells 5 are overlapped, the principle of how the housing 10 of the battery cell 5 can effectively prevent leakage in different overlapping conditions can be referred to as follows: Figure 9-11 Three embodiments, wherein Figure 9-11 The outer layer 13 of the battery cell 5 is made of metal, the top cover 20 is connected to the inner metal layer 11 and is not connected to the outer layer 13, and the inner metal layer 11 of the battery cell 5 is connected to the positive electrode sheet of the battery cell 5. For the convenience of description, the two battery cells 5 connected in series are assumed to be the first battery cell 5a and the second battery cell 5b. Since the first battery cell 5a and the second battery cell 5b are connected in series, and the inner metal layer 11 of the first battery cell 5a and the inner metal layer 11 of the second battery cell 5b are both charged, the top cover 20 of the first battery cell 5a and the top cover 20 of the second battery cell 5b are both charged, and the potentials are different.

[0117] Fig. 9 For two adjacent Figure 3 A schematic diagram of the structure when the top cover 20 of the middle battery cell 5 is overlapped.

[0118] Reference Fig. 9 For the convenience of description, the potential of the top cover 20 of the first battery cell 5a is set to be higher than the potential of the top cover 20 of the second battery cell 5b. When the top cover 20 of the first battery cell 5a and the top cover 20 of the second battery cell 5b are overlapped by the fallen conductive debris, since the potentials of the top cover 20 of the first battery cell 5a and the top cover 20 of the second battery cell 5b are different, and the top cover 20 of the battery cell 5 is connected to the inner metal layer 11, a potential difference is formed between the top cover 20 and the inner metal layer 11 of the first battery cell 5a and the top cover 20 and the inner metal layer 11 of the second battery cell 5b, thereby conducting electrons. Moreover, the inner metal layer 11 of the first battery cell 5a is in direct contact with the electrolyte 30, so that the part of the inner metal layer 11 of the first battery cell 5a that is in contact with the electrolyte 30 is in direct contact with the cations (such as lithium ions) of the electrolyte 30, and then ions are conducted between the inner metal layer 11 of the first battery cell 5a and the electrolyte 30. When electrons and ions are conducted, the cations in the electrolyte 30 are embedded in the inner metal layer 11 of the first battery cell 5a and form an alloy. However, since the insulating layer 12 of the first battery cell 5a is sealed and connected to the outside of the inner metal layer 11 of the first battery cell 5a, the part of the inner metal layer 11 of the first battery cell 5a that contacts the electrolyte 30 cannot contact the air outside the first battery cell 5a, so that the inner metal layer 11 of the first battery cell 5a embedded with cations can be prevented from being pulverized due to contact with the air, so that the inner metal layer 11 of the first battery cell 5a can be prevented from leaking. The inner metal layer 11 of the first battery cell 5a will not leak, and the insulating layer 12 of the first battery cell 5a will not be damaged. The insulating layer 12 of the first battery cell 5a still has stable insulation and the ability to seal the inner metal layer 11 of the first battery cell 5a, so that the inner metal layer 11 of the first battery cell 5a can be guaranteed not to contact the external air. Therefore, when the top cover 20 of the first battery cell 5a and the top cover 20 of the second battery cell 5b are overlapped, the inner metal layer 11 of the first battery cell 5a will not leak, so that the safety performance of the first battery cell 5a can be guaranteed.

[0119] The top cover 20 of the second battery cell 5b is at a low potential and is connected to the inner metal layer 11 of the second battery cell 5b, so that the cations in the electrolyte 30 are usually not embedded in the inner metal layer 11 of the second battery cell 5b.

[0120] In addition, for the first battery cell 5a or the second battery cell 5b, taking the first battery cell 5a as an example, when the negative electrode column 52 of the first battery cell 5a and the top cover 20 of the first battery cell 5a are overlapped by fallen conductive debris, the inner metal layer 11 of the first battery cell 5a will also be electronically conductive with the negative electrode column 52, and the position where the inner metal layer 11 of the first battery cell 5a contacts the electrolyte 30 satisfies ion conductivity, so that the position where the inner metal layer 11 of the first battery cell 5a contacts the electrolyte 30 will also have cations embedded in the inner metal layer 11, but due to the setting of the insulating layer 12 of the first battery cell 5a, the first battery cell 5a can be prevented from being pulverized due to contact with the air outside the first battery cell 5a, thereby preventing leakage of the inner metal layer 11, thereby ensuring the safety performance of the first battery cell 5a. Similarly, for the second battery cell 5b, when the negative electrode column 52 of the second battery cell 5b is overlapped with the top cover 20 of the second battery cell 5b, the inner metal layer 11 of the second battery cell 5b will not leak, and the safety performance of the second battery cell 5b can also be guaranteed.

[0121] In addition, when the negative electrode column 52 of the second battery cell 5b overlaps the top cover 20 of the first battery cell 5a, a potential difference is formed between the negative electrode column 52 of the second battery cell 5b and the inner metal layer 11 of the first battery cell 5a, so that electrons are conducted, and the inner metal layer 11 of the first battery cell 5a contacts the electrolyte 30, so that ions are conducted, and then the cations in the electrolyte 30 are embedded in the portion where the inner metal layer 11 of the first battery cell 5a contacts the electrolyte 30. However, since the insulating layer 12 of the first battery cell 5a is sealed and connected to the outside of the inner metal layer 11 of the first battery cell 5a, the inner metal layer 11 of the first battery cell 5a embedded with cations can be prevented from being pulverized due to contact with air, thereby preventing the inner metal layer 11 of the first battery cell 5a from leaking, and thus ensuring the safety of the first battery cell 5a.

[0122] For the outer layer 13 of the first battery cell 5a and the outer layer 13 of the second battery cell 5b, since the outer layer 13 of the first battery cell 5a and the outer layer 13 of the second battery cell 5b are not electronically conductive with other components and are not ionically conductive with the electrolyte 30, the outer layer 13 of the first battery cell 5a and the outer layer 13 of the second battery cell 5b will not corrode.

[0123] Fig.10 For two adjacent Figure 3 A schematic structural diagram of a middle battery cell 5 , wherein a top cover 20 of one battery cell 5 and an outer layer 13 of another battery cell 5 are overlapped.

[0124] Reference Fig.10 When the top cover 20 of the first battery cell 5a and the outer layer 13 of the second battery cell 5b are overlapped by the fallen conductive debris, since the top cover 20 of the first battery cell 5a is charged and the outer layer 13 of the second battery cell 5b is not charged, a potential difference will be formed, thereby causing electron conduction.

[0125] If the potential of the top cover 20 of the first battery cell 5a is negative, the inner metal layer 11 of the first battery cell 5a is negative. Since the outer layer 13 of the second battery cell 5b is not in direct contact with the electrolyte 30, the outer layer 13 of the second battery cell 5b will not have cations in the electrolyte 30 embedded, so that although the outer layer 13 of the second battery cell 5b is in contact with the air outside the battery cell 5, it will not be corroded. If the outer layer 13 of the second battery cell 5b is not corroded, the insulating layer 12 of the second battery cell 5b will not be damaged, and the inner metal layer 11 of the second battery cell 5b will not be in contact with the external air, so the inner metal layer 11 of the second battery cell 5b will not be corroded.

[0126] If the potential of the top cover 20 of the first battery cell 5a is positive, the inner metal layer 11 of the first battery cell 5a is positive. The inner metal layer 11 of the first battery cell 5a is in contact with the electrolyte 30, so that the position where the inner metal layer 11 of the first battery cell 5a contacts the electrolyte 30 is ion-conductive, and the cations in the electrolyte 30 will be embedded in the inner metal layer 11 of the first battery cell 5a. However, since the inner metal layer 11 of the first battery cell 5a is sealed and connected by the insulating layer 12 of the first battery cell 5a, the inner metal layer 11 of the first battery cell 5a will not be powdered due to contact with the air outside the first battery cell 5a, thereby preventing the inner metal layer 11 of the first battery cell 5a from leaking, so as to ensure the safety performance of the second battery cell 5b.

[0127] Fig.11 For two adjacent Figure 3 A schematic diagram of the structure when the outer layer 13 of the middle battery cell 5 is overlapped.

[0128] Reference Fig.11 When the outer layer 13 of the first battery cell 5a and the outer layer 13 of the second battery cell 5b are overlapped, since the outer layer 13 of the first battery cell 5a and the outer layer 13 of the second battery cell 5b will not contact the electrolyte 30, the outer layer 13 of the first battery cell 5a and the outer layer 13 of the second battery cell 5b cannot form an ion channel, thereby preventing the outer layer 13 of the first battery cell 5a and the outer layer 13 of the second battery cell 5b from being corroded. Therefore, the insulating layer 12 of the first battery cell 5a and the insulating layer 12 of the second battery cell 5b can be prevented from being corroded, thereby preventing the inner metal layer 11 of the first battery cell 5a and the inner metal layer 11 of the second battery cell 5b from contacting with the external air, thereby ensuring the safety performance of the first battery cell 5a and the second battery cell 5b.

[0129] Fig.12 Based on Figure 3 A schematic diagram of a partial structure of a shell 10 of another battery cell 5 extending the battery cell 5 in the embodiment, wherein Fig.12 The battery cell 5 in the embodiment and Figure 3The difference between the battery cells 5 in the embodiments lies in the different connection positions between the top cover 20 and the housing 10 .

[0130] Reference Fig.12 In some embodiments, the outer layer 13 is a metal layer, and the top cover 20 is connected to the outer layer 13. It is understandable that when the top cover 20 is connected to the outer layer 13, the top cover 20 and the outer layer 13 will not contact the electrolyte 30, so when the outer layer 13 of the adjacent battery cells 5 is overlapped by conductive debris, the outer layer 13 of the battery cell 5 will not be corroded.

[0131] In some embodiments, the top cover 20 is spaced apart from the inner metal layer 11. Since the top cover 20 is spaced apart from the inner metal layer 11, and the inner metal layer 11 and the outer layer 13 are insulated and separated by an insulating layer, when conductive debris between adjacent cells 5 overlaps the outer layer 13 or the top cover 20 of the cell 5, the inner metal layer 11 will not participate in electronic conduction, so that the inner metal layer 11 will not be corroded, and thus the inner metal layer 11 and the outer layer 13 in this embodiment will not be corroded. Thus, the safety performance of the cell 5 can be effectively guaranteed.

[0132] In some embodiments, with the bottom wall 131 of the outer layer 13 as a reference, in the height direction Z of the housing 10, the side wall 122 of the insulating layer 12 and the side wall 112 of the inner metal layer 11 are lower than the side wall 132 of the outer layer 13. Since the side wall 122 of the insulating layer 12 and the side wall 112 of the inner metal layer 11 are lower than the side wall 132 of the outer layer 13, the contact between the inner metal layer 11 and the top cover 20 can be effectively avoided, and the electrical connection between the inner metal layer 11 and the top cover 20 can be prevented.

[0133] In some embodiments, the top cover 20 is connected to the outer layer 13 by welding.

[0134] It is understandable that when the top cover 20 is connected to the outer layer 13 , the thickness H3 of the outer layer 13 may be appropriately increased to ensure the connection strength between the outer layer 13 and the top cover 20 .

[0135] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A battery cell, characterized in that: The battery cell comprises a shell, a top cover, a pole piece and an electrolyte, wherein the top cover is sealed to the shell and surrounds the shell to form a sealed cavity, the pole piece is contained in the sealed cavity, and the electrolyte is contained in the sealed cavity; The shell includes an outer layer, an insulating layer and an inner metal layer, the insulating layer is located between the outer layer and the inner metal layer, at least part of the inner metal layer is in contact with the electrolyte, the insulating layer is sealed and connected to at least part of the inner metal layer, and the outer layer has stronger wear resistance than the insulating layer.

2. The battery cell according to claim 1, characterized in that: The top cover is sealed on the inner metal layer and forms the sealed cavity with the inner metal layer.

3. The battery cell according to claim 1, characterized in that: The inner metal layer, the insulating layer and the outer layer all include a bottom wall arranged opposite to the top cover and a plurality of side walls connected to the periphery of the bottom wall, the bottom wall of the inner metal layer, the bottom wall of the insulating layer and the bottom wall of the outer layer are stacked in sequence from the inner side to the outer side of the sealed cavity, and the side wall of the inner metal layer, the side wall of the insulating layer and the side wall of the outer layer are stacked in sequence from the inner side to the outer side of the sealed cavity; The direction perpendicular to the bottom wall is the height direction of the shell, and the multiple side walls of the inner metal layer are connected between the top cover and the bottom wall of the inner metal layer. Taking the bottom wall of the outer layer as a reference, in the height direction of the shell, the side walls of the insulating layer and the side walls of the outer layer are lower than the side walls of the inner metal layer.

4. The battery cell according to claim 3, characterized in that: Taking the bottom wall of the outer layer as a reference, in the height direction of the shell, the height of the side wall of the insulating layer is higher than the height of the electrolyte in the sealed cavity.

5. The battery cell according to claim 3, characterized in that: Taking the bottom wall of the outer layer as a reference, in the height direction of the shell, the side wall of the outer layer is not lower than the side wall of the insulating layer.

6. The battery cell according to any one of claims 1 to 5, characterized in that: The outer layer is a metal layer, and the inner metal layer and the outer layer are insulated.

7. The battery cell according to claim 6, characterized in that: The peripheral edge of the top cover is sealed on the inner metal layer and is spaced apart from the outer layer.

8. The battery cell according to claim 6, characterized in that: The thickness of the inner metal layer is greater than the thickness of the outer layer.

9. The battery cell according to claim 6, characterized in that: The thickness of the insulating layer is 0.3 mm-1 mm, the thickness of the outer layer is 0.2 mm-0.5 mm, and the thickness of the inner metal layer is 0.4 mm-1 mm.

10. A battery pack, characterized in that: The invention comprises a shell and a plurality of battery cells as claimed in any one of claims 1 to 9, wherein the plurality of battery cells are stacked in the shell.

11. An energy storage device, characterized in that: It comprises a cabinet and a plurality of battery packs as described in claim 10, wherein the plurality of battery packs are stacked in the cabinet.

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