Battery cell, battery module, battery pack, and energy storage system

Abstract

Embodiments of the present application provide a battery cell, a battery module, a battery pack, and an energy storage system. The battery cell comprises an electrode core, a flow guide component, an electrolyte, and a packaging shell; the electrode core and the electrolyte are both packaged in the packaging shell; the electrode core is infiltrated in the electrolyte; the electrode core has tabs; one end of the flow guide component is connected to a corresponding tab and located in the packaging shell, and the other end of the flow guide component is exposed outside the packaging shell. The battery module can comprise a plurality of battery cells, and any two adjacent battery cells are connected in series by means of one flow guide component; or the battery module can comprises a plurality of electrode cores, any two adjacent electrode cores are connected in series by means of one flow guide component, and these electrode cores and the flow guide components are packaged in a single packaging shell. The battery pack comprises a plurality of battery modules connected in series. The energy storage system comprises a power converter and the battery pack. The embodiments of the present application can simplify the structure of a secondary battery, thereby reducing the cost, reducing the internal resistance of the secondary battery, and increasing the output power.

Description

Battery cells, battery modules, battery packs and energy storage systems

[0001] This application claims priority to the Chinese patent application with application number 202321712483.9 filed with the State Intellectual Property Office of China on June 30, 2023, and priority to the Chinese patent application with the invention name “Battery Cell, Battery Module, Battery Pack and Energy Storage System”, all contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of secondary battery technology, and in particular to a battery cell, a battery module, a battery pack and an energy storage system. Background Art

[0003] As a chemical energy storage component, secondary batteries offer high energy density and have become a widely used energy storage device. However, traditional secondary batteries are complex in structure, comprised of numerous components, and are expensive. Furthermore, they have high internal resistance and low output power.

[0004] Summary of the Invention

[0005] The embodiments of the present application provide a battery cell, a battery module, a battery pack, an energy storage system, and a vehicle, which can simplify the structure of the secondary battery, reduce costs, reduce the internal resistance of the secondary battery, and improve output power.

[0006] In the first aspect, an embodiment of the present application provides a battery cell, comprising a pole core, a flow guide, an electrolyte and a packaging shell, wherein the pole core and the electrolyte are both encapsulated in the packaging shell, and the pole core is immersed in the electrolyte; the pole core has a pole ear, one end of the flow guide is connected to the pole ear and is located in the packaging shell, and the other end of the flow guide is exposed outside the packaging shell.

[0007] In this solution, one tab of the battery cell is connected to a current guide, which serves as the electrode terminal for electrical connection between the battery cell and other components. Compared to conventional battery cells, this solution's battery cell has fewer components, a simpler structure, and lower costs. Due to its simple structure, the battery cell of this solution has lower internal resistance and higher output power. Furthermore, one end of the current guide is located within the packaging shell, which helps ensure a reliable connection between the current guide and the tab, thereby ensuring the reliability of the battery cell.

[0008] In an implementation of the first aspect, the battery cell includes a sealing ring, which surrounds the outer periphery of the flow guide and is located in the packaging shell, and the outer peripheral surface of the sealing ring is connected to the inner wall of the packaging shell; the electrolyte is located on the side of the sealing ring that is opposite to the end of the flow guide exposed outside the packaging shell.

[0009] In this solution, a sealing ring is provided so that the sealing ring and the packaging shell together form a receiving cavity, which facilitates the packaging of the electrode core and the electrolyte. The sealing ring packaging solution is relatively simple, reliable in performance, and easy to mass produce.

[0010] In an implementation of the first aspect, one end of the guide member is welded to the tab, the tab is made of aluminum alloy, and the material of the weld between the one end of the guide member and the tab is also aluminum alloy.

[0011] In this solution, when the battery cell is a sodium ion battery cell, the characteristic that both the positive and negative tabs of the battery cell are made of aluminum foil can be utilized, and a guide piece made of the same material as the tab can be welded to the tab. This can reduce the connection size and help improve the energy density of the battery cell.

[0012] In an implementation of the first aspect, the electrode tab is a negative electrode tab; the flow guide includes a first fusible portion, which is located in the packaging shell and immersed in the electrolyte. The first fusible portion is used to generate an electrochemical reaction with the electrolyte and disconnect the electrical connection between the negative electrode tab and the flow guide when the voltage of the battery cell is less than or equal to a first voltage threshold.

[0013] In this solution, a first fuse part can be provided on the flow guide. When the battery cell is operating normally, the potential of the first fuse part located between the negative electrode ear and the sealing ring is consistent with that of the negative electrode ear, which is a low potential. When the voltage of the battery cell is less than or equal to the first voltage threshold, the battery cell will be over-discharged, and the potential of the negative electrode ear will rise, causing the first fuse part to undergo an electrochemical reaction and melt, disconnecting the discharge circuit of the battery cell, thereby avoiding failure of the battery cell and the risk of explosion, fire or leakage. Therefore, this solution can protect the battery cell from over-discharge and ensure that the battery cell can successfully pass the over-discharge test.

[0014] In one implementation of the first aspect, the material of the first fusible breaking portion is a readily soluble metal or an alloy of a readily soluble metal and aluminum, wherein the readily soluble metal is one or more of copper, magnesium, manganese, iron, cobalt, nickel, zinc, gallium, germanium, yttrium, zirconium, niobium, molybdenum, technetium, ruthenium, rhodium, palladium, silver, cadmium, indium, tin, and antimony. These materials can effectively meet the over-discharge fusible breaking requirements of the first fusible breaking portion and are also easy to mass-produce.

[0015] In one implementation of the first aspect, the battery cell further includes a liquid wicking ring disposed around the periphery of the first fusible portion and configured to absorb electrolyte. The liquid wicking ring absorbs and stores the electrolyte, ensuring sufficient contact between the first fusible portion and the electrolyte, thereby facilitating an electrochemical reaction in the first fusible portion during over-discharge.

[0016] In a second aspect, an embodiment of the present application provides a battery module, which includes a plurality of battery cells, wherein the plurality of battery cells are connected in series, and any two adjacent battery cells among the plurality of battery cells are electrically connected via a flow guide.

[0017] In this solution, any two adjacent cells in the battery module can be connected in series through a flow guide. There is no complex electrical connection structure between any two adjacent cells, which makes the structure of the battery module relatively simple, which is conducive to reducing the cost of the battery module. In addition, the internal resistance of the battery module is low, which makes the output power of the battery module higher. Since multiple cells are connected in series in the battery module, the battery module has a higher voltage and energy density, which is conducive to reducing the number of cells connected in series in the battery pack, thereby helping to simplify the structure of the energy storage system. In addition, the end of the flow guide can be located inside the packaging shell, which is conducive to ensuring a reliable connection between the flow guide and the tab, thereby ensuring the reliability of the battery cell and the battery module.

[0018] In an implementation of the second aspect, the flow guide of the battery cell at the end of multiple battery cells includes a first flow guide and a second flow guide; one end of the first flow guide is connected to the negative electrode ear of the battery cell at the end and is located in the packaging shell of the battery cell at the end, and the other end of the first flow guide is exposed outside the packaging shell where the battery cell at the head end is located; one end of the second flow guide is connected to the positive electrode ear of the battery cell at the end and is located in the packaging shell of the battery cell at the end, and the other end of the second flow guide is electrically connected to another battery cell adjacent to the battery cell at the end.

[0019] In this solution, the positive tab of the end cell can be connected to the second current guide, and the negative tab can be connected to the first current guide. Both the positive and negative tabs of the end cell can be connected to a single current guide. Compared to conventional cells, this solution has fewer components and a simpler structure, resulting in a simpler battery module structure and lowering battery module costs. Furthermore, the battery module has lower internal resistance, resulting in higher output power.

[0020] In an implementation of the second aspect, the battery cell at the end includes a sealing ring, which surrounds the outer periphery of the first flow guide and the outer periphery of the second flow guide, and is located in the packaging shell where the battery cell at the head end is located, and the outer peripheral surface of the sealing ring is connected to the inner wall of the packaging shell; the electrolyte is located between the sealing ring on the outer periphery of the first flow guide and the sealing ring on the outer periphery of the second flow guide.

[0021] In this solution, sealing rings are installed on the outer peripheries of the first and second flow guides. These sealing rings and the packaging shell of the terminal cell together form a receiving cavity, facilitating the encapsulation of the terminal cell's core and electrolyte. This sealing ring packaging solution is relatively simple, offers reliable performance, and is easily mass-produced.

[0022] In an implementation of the second aspect, the first flow guide includes a second fuse portion, which is located in the packaging shell of the terminal battery cell and immersed in the electrolyte. The second fuse portion is used to generate an electrochemical reaction with the electrolyte and disconnect the electrical connection between the negative electrode ear of the terminal battery cell and the first flow guide when the voltage of the battery module is less than or equal to the second voltage threshold.

[0023] In this solution, a second fuse part can be provided on the first flow guide. When the battery module is operating normally, the potential of the second fuse part located between the negative electrode ear and the sealing ring is consistent with that of the negative electrode ear, which is a low potential. When the voltage of the battery module is less than or equal to the second voltage threshold, the battery module will be over-discharged, and the potential of the negative electrode ear will rise, causing the second fuse part to undergo an electrochemical reaction and melt, disconnecting the discharge circuit of the battery module, thereby avoiding failure of the battery module and the risk of explosion, fire or leakage. Therefore, this solution can protect the battery module from over-discharge and ensure that the battery module can successfully pass the over-discharge test.

[0024] In one implementation of the second aspect, the terminal battery cell further includes a liquid wicking ring, which is disposed around the outer periphery of the second fusible portion and is configured to absorb electrolyte. The liquid wicking ring absorbs and stores the electrolyte, ensuring sufficient contact between the second fusible portion and the electrolyte, thereby facilitating an electrochemical reaction in the second fusible portion during over-discharge.

[0025] In a third aspect, an embodiment of the present application provides a battery module comprising a plurality of pole cores, at least one transition guide, at least one sealing ring, an electrolyte and a packaging shell, wherein the plurality of pole cores, at least one transition guide and at least one sealing ring are all encapsulated in the packaging shell; the plurality of pole cores are connected in series, and the pole ears of any two adjacent pole cores among the plurality of pole cores are electrically connected through a transition guide; the outer periphery of each transition guide is surrounded by a sealing ring, and the outer peripheral surface of each sealing ring is connected to the inner wall of the packaging shell, and the sealing ring on at least one transition guide divides the internal space of the packaging shell into a plurality of accommodating cavities, and each of the plurality of accommodating cavities accommodates electrolyte and a pole core, wherein the pole core is immersed in the electrolyte.

[0026] In this solution, any two adjacent cells in the battery module can be connected in series through a flow guide, and there is no complex electrical connection structure between any two adjacent cells, which makes the structure of the battery module relatively simple, which is conducive to reducing the cost of the battery module. In addition, the internal resistance of the battery module is low, which makes the output power of the battery module higher. Since multiple cells are connected in series in the battery module, the battery module has a higher voltage and energy density, which is conducive to reducing the number of cells connected in series in the battery pack, thereby simplifying the structure of the energy storage system. In addition, the end of the flow guide can be located inside the packaging shell, which is conducive to ensuring a reliable connection between the flow guide and the tab, thereby ensuring the reliability of the cell and the battery module. A single packaging shell and the sealing ring inside it can construct multiple isolated accommodation spaces, so that each cell can work normally, and the problem of electrolyte decomposition in the battery module at higher voltage can be avoided. The multiple pole cores of this solution are encapsulated in a single packaging shell, which is relatively compact and has good structural strength.

[0027] In an implementation of the third aspect, in any two adjacent pole cores among the multiple pole cores, the positive pole ear of one pole core is welded to one end of the transition guide member, and the negative pole ear of the other pole core is welded to the other end of the transition guide member. The material of the positive pole ear and the negative pole ear of each pole core among the multiple pole cores is aluminum alloy, and the material of the welding points at both ends of each transition guide member is aluminum alloy.

[0028] In this solution, when the battery cell is a sodium ion battery cell, the characteristic that both the positive and negative tabs of the battery cell are made of aluminum foil can be utilized, and a transition guide made of the same material as the tabs can be welded to the tabs. This can reduce the connection size and is beneficial to improving the energy density of the battery cell and battery module.

[0029] In an implementation of the third aspect, at least one of all the transition guides includes a first fuse portion, the first fuse portion is located between the negative electrode ear of the pole core to which the transition guide is electrically connected and the sealing ring on the transition guide, the first fuse portion is immersed in the electrolyte, and the first fuse portion is used to generate an electrochemical reaction with the electrolyte and disconnect the electrical connection between the negative electrode ear and the positive electrode ear when the voltage of the battery module is less than or equal to the second voltage threshold.

[0030] In this solution, a first melting portion can be provided on at least a portion of the transition guide. When the battery module is operating normally, the potential of the first melting portion located between the negative electrode ear and the sealing ring is consistent with that of the negative electrode ear, which is a low potential. When the voltage of the battery module is less than or equal to the first voltage threshold, the battery cell will be over-discharged, and the potential of the negative electrode ear will rise, causing the first melting portion to undergo an electrochemical reaction and melt, disconnecting the discharge circuit of the battery module, thereby avoiding failure of the battery module and the risk of explosion, fire or leakage. Therefore, this solution can protect the battery module from over-discharge and ensure that the battery module can successfully pass the over-discharge test.

[0031] In an implementation of the third aspect, the battery module further includes a first end flow guide and a second end flow guide; one end of the first end flow guide is electrically connected to the positive electrode ear of the pole core located at the head end of the multiple pole cores connected in series and is located inside the packaging shell, and the other end of the first end flow guide is exposed outside the packaging shell; one end of the second end flow guide is electrically connected to the negative electrode ear of the pole core located at the end end of the multiple pole cores connected in series, and the other end of the second end flow guide is exposed outside the packaging shell.

[0032] In this solution, both the front-end battery cell and the rear-end pole core are connected to a flow guide. Compared to conventional battery modules, this solution's battery module has fewer components and a simpler structure, which helps reduce battery module costs. Furthermore, the battery module's lower internal resistance results in higher output power.

[0033] In an implementation of the third aspect, a sealing ring is provided around the outer periphery of the first end flow guide member and the second end flow guide member. The sealing ring on the first end flow guide member and the sealing ring on the second end flow guide member are both located inside the packaging shell and are connected to the inner wall of the packaging shell. The sealing ring on the first end flow guide member closes one end of the packaging shell, and the sealing ring on the second end flow guide member closes the other end of the packaging shell.

[0034] In this solution, the sealing rings on the package shell and the end guide can be used to seal the two ends of the package shell, thereby sealing multiple electrode cores and electrolyte. The sealing ring packaging solution is relatively simple, has reliable performance, and is easy to mass produce.

[0035] In one implementation of the third aspect, the positive ear of the pole core at the first end is welded to the first end guide piece, and the materials of the welding point between the positive ear of the pole core at the first end and the first end guide piece are both aluminum alloy, and the negative ear of the pole core at the end is welded to the second end guide piece, and the materials of the welding point between the negative ear of the pole core at the end and the second end guide piece are both aluminum alloy.

[0036] In this solution, when the battery cell is a sodium ion battery cell, the characteristic that both the positive and negative tabs of the battery cell are made of aluminum foil can be utilized, and end guides made of the same material as the tabs can be welded to the tabs. This can reduce the connection size and is beneficial to improving the energy density of the battery cell and battery module.

[0037] In one implementation of the third aspect, the second end flow guide includes a second fusible portion, which is located between the negative pole ear of the terminal core and the sealing ring on the second end flow guide, and the second fusible portion is immersed in the electrolyte. The second fusible portion is used to generate an electrochemical reaction with the electrolyte and disconnect the electrical connection between the second end flow guide and the negative pole ear when the voltage of the battery module is less than or equal to the second voltage threshold.

[0038] In this solution, a second fuse part can be provided on the second end guide member. When the battery module is operating normally, the potential of the second fuse part located between the negative electrode ear and the sealing ring is consistent with that of the negative electrode ear, which is a low potential. When the voltage of the battery module is less than or equal to the voltage threshold, the battery module will be over-discharged, and the potential of the negative electrode ear will rise, causing the second fuse part to undergo an electrochemical reaction and melt, disconnecting the discharge circuit of the battery module, thereby avoiding failure of the battery module and the risk of explosion, fire or leakage. Therefore, this solution can protect the battery module from over-discharge and ensure that the battery module can successfully pass the over-discharge test.

[0039] In a fourth aspect, an embodiment of the present application provides a battery pack comprising a plurality of such battery modules; the plurality of battery modules are connected in series; or, the plurality of battery modules include a first battery module, a second battery module and a third battery module, wherein the first battery module and the second battery module are connected in series, and the first battery module and the third battery module are connected in parallel.

[0040] The battery pack of this solution incorporates the aforementioned battery modules, resulting in an optimized structure and internal resistance. The battery pack also features a smaller number of cells connected in series, simplifying the energy storage system structure. Furthermore, the battery pack offers high voltage and energy density, and excellent operational reliability.

[0041] In a fifth aspect, an embodiment of the present application provides an energy storage system, comprising a power converter and the battery pack, wherein the power converter is electrically connected to the battery pack, and is configured to convert the electrical energy output by the battery pack and output it to an external load or a power grid, and / or the power converter is configured to convert the electrical energy output by a power supply device and output it to the battery pack. The energy storage system of this solution includes the aforementioned battery pack, making the structure of the energy storage system relatively simple and low-cost.

[0042] In a sixth aspect, an embodiment of the present application provides a vehicle, comprising an electrical device and the battery pack, wherein the electrical device is electrically connected to the battery pack. The vehicle of this solution comprises the battery pack, has a relatively simple structure, and is relatively low in cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] FIG1a is a schematic diagram of an application scenario of an energy storage system in an embodiment;

[0044] FIG1b is a schematic diagram of an application scenario of an energy storage system in another embodiment;

[0045] FIG1c is a schematic diagram of an application scenario of an energy storage system in another embodiment;

[0046] FIG2 is a schematic structural diagram of a vehicle in an embodiment;

[0047] FIG3 is a schematic diagram of a battery pack in an embodiment;

[0048] FIG4 is a schematic cross-sectional view of the battery module in Example 1;

[0049] FIG5 is a schematic diagram of the structure of the battery cell in Example 1;

[0050] FIG6 is a partially enlarged schematic cross-sectional view of point A in FIG4 ;

[0051] FIG7 is a schematic diagram of the exploded structure of the transition guide member in Example 1;

[0052] FIG8 is a schematic cross-sectional view of the transition guide member, the liquid suction ring and the sealing ring in Example 1;

[0053] FIG9 is a partial enlarged cross-sectional view of the structure at point C in FIG4 ;

[0054] FIG10 is a partial enlarged cross-sectional view of the structure at point B in FIG4 ;

[0055] FIG11 is a schematic cross-sectional view of the battery module in Example 2;

[0056] FIG12 is a schematic diagram of a partially enlarged cross-sectional view of the structure shown in FIG11 at position D;

[0057] FIG13 is a schematic cross-sectional view of the transition guide member, the liquid suction ring and the sealing ring in the second embodiment. DETAILED DESCRIPTION

[0058] For ease of understanding, the relevant technical terms involved in the embodiments of this application are explained and described below.

[0059] In the description of the embodiments of the present application, unless otherwise specified, "plurality" refers to two or more.

[0060] The terms "first", "second", etc. are used for descriptive purposes only and should not be understood to suggest or imply relative importance or to implicitly indicate the quantity of the technical features indicated. Features qualified as "first" or "second" may explicitly or implicitly include one or more of such features.

[0061] The term "connect" should be interpreted broadly. For example, "connect" can mean either a detachable or non-detachable connection, a direct connection, or an indirect connection through an intermediary. The term "fix" should also be interpreted broadly. For example, "fix" can mean either a direct fixation or an indirect fixation through an intermediary.

[0062] The directional terms mentioned in the embodiments of this application, such as "upper," "lower," "front," "back," "left," "right," "inner," "outer," "side," "top," and "bottom," are merely references to directions in the accompanying drawings. These directional terms are intended to better and more clearly illustrate and understand the embodiments of this application, and are not intended to explicitly or implicitly indicate that the devices or components referred to must have a specific orientation, be constructed or operate in a specific orientation, and are therefore not to be construed as limiting the embodiments of this application.

[0063] In the description of the embodiments of this application, unless otherwise specified, "and / or" is simply a description of an association relationship between associated objects, indicating that three relationships can exist. For example, "A and / or B" can represent: A exists alone, A and B exist simultaneously, or B exists alone.

[0064] The embodiments of the present application are described below in conjunction with the drawings in the embodiments of the present application.

[0065] The following embodiments of the present application provide a battery pack that can be used in application scenarios such as energy storage systems or vehicles.

[0066] For example, Figure 1a illustrates an application scenario of an energy storage system 120 in one embodiment. As shown in Figure 1a, the energy storage system 120 is connected between a power supply device 110 and a power grid 130 or an external load 140 (the power grid 130 or the external load 140 refers to the power grid 130 or the external load 140, the same below).

[0067] The power supply device 110 may be a power supply that outputs electrical energy in a unidirectional manner. The power supply may be a power supply in a narrow sense, or the power supply may include a power supply in a narrow sense and a power converter. Alternatively, the power supply device 110 may be a battery that can both output electrical energy and receive and store electrical energy. The power supply device 110 may output direct current or alternating current. For example, the power supply device 110 may be a direct current source including a plurality of photovoltaic modules. The photovoltaic modules in the power supply device 110 may be connected in series and / or in parallel to form a photovoltaic string. A plurality of photovoltaic strings may also be connected in parallel to form a photovoltaic array. The external load 140 may be a direct current load or an alternating current load.

[0068] As shown in Figure 1a, the energy storage system 120 may include a power converter 121, a battery pack 122, and a power converter 123 connected in sequence. The power converter 121 may be connected to the power supply device 110, and the power converter 123 may be connected to the power grid 130 / external load 140. Both the power converter 121 and the power converter 123 may include a controller and a conversion circuit. The controller is used to control the operation of the conversion circuit, and the conversion circuit is used to perform power conversion. Power conversion includes but is not limited to voltage conversion, conversion between AC and DC (AC / DC or DC / AC), and conversion between DC and DC (DC / DC).

[0069] As shown in FIG1a , in one embodiment, the power supply device 110 may be a DC source, and the power converter 121 may include a DC / DC conversion circuit. The power converter 121 may perform DC / DC conversion on the DC power of the power supply device 110 and input the converted power into the battery pack 122 to charge the battery pack 122. The power converter 123 may include a DC / DC conversion circuit. The power converter 123 may perform DC-DC conversion on the DC power output by the battery pack 122 and input the converted power into an external load 140 that uses DC power. Alternatively, the power converter 123 may include a DC / AC conversion circuit. The power converter 123 may perform DC / AC conversion on the DC power output by the battery pack 122 and input the converted power into the power grid 130 or the external load 140 that uses AC power.

[0070] As shown in FIG1a , in another embodiment, the power supply device 110 may be an AC source, and the power converter 121 may include an AC / DC conversion circuit. The power converter 121 may perform AC / DC conversion on the AC power of the power supply device 110 and input the converted power into the battery pack 122 to charge the battery pack 122. The power converter 123 may include a DC / DC conversion circuit. The power converter 123 may perform DC / DC conversion on the DC power output by the battery pack 122 and input the converted power into an external load 140 that uses DC power. Alternatively, the power converter 123 may include a DC / AC conversion circuit. The power converter 123 may perform DC / AC conversion on the DC power output by the battery pack 122 and input the converted power into the power grid 130 or the external load 140 that uses AC power.

[0071] FIG1b illustrates a schematic diagram of an application scenario of an energy storage system 120 in another embodiment. Different from FIG1a , the energy storage system 120 in FIG1b includes a power converter 121 and a battery pack 122. The power converter 121 can connect the power supply device 110 and the battery pack 122. Similar to the above, the power supply device 110 can be a DC source or an AC source, and the power converter 121 can include a DC / DC conversion circuit or an AC / DC conversion circuit. The power converter 121 can perform DC / DC conversion (or AC / DC conversion) on the DC power (or AC power) of the power supply device 110 and input it into the battery pack 122 to charge the battery pack 122.

[0072] FIG1c illustrates a schematic diagram of an application scenario of an energy storage system 120 in another embodiment. Unlike FIG1a , the energy storage system 120 in FIG1c includes a battery pack 122 and a power converter 123. The power converter 123 can connect the battery pack 122 to the power grid 130 or the external load 140. As in the above, the external load 140 can be a DC load or an AC load. The power converter 123 can include a DC / DC conversion circuit, which can convert the DC power output by the battery pack 122 into DC / DC and input it into the external load 140 that uses DC power; or, the power converter 123 can include a DC / AC conversion circuit, which can convert the DC power output by the battery pack 122 into DC / AC and input it into the power grid 130 or the external load 140 that uses AC power.

[0073] Figure 2 illustrates a schematic structural diagram of a vehicle 200. As shown in Figure 2 , vehicle 200 may be a wheeled vehicle driven or towed by a power unit. Vehicle 200 may include, but is not limited to, electric vehicles, electric bicycles, electric motorcycles, electric trains, electric buses, electric amusement rides, or other electric vehicles. Electric vehicles may include pure electric vehicles and hybrid electric vehicles. Vehicle 200 may also include fuel-powered vehicles, such as gasoline-powered cars and gasoline-powered motorcycles.

[0074] As shown in Figure 2, the vehicle 200 may include a vehicle body 201, a battery pack 202, and electrical equipment 203. Among them, the vehicle body 201, as the main part of the vehicle 200, may include basic components such as doors, windows, seats, chassis, and a powertrain system located inside the vehicle body 201. The battery pack 202 and the electrical equipment 203 may be installed on the vehicle body 201. The battery pack 202 is electrically connected to the electrical equipment 203, and the battery pack 202 supplies power to the electrical equipment 203. The electrical equipment 203 may be a device, equipment, or instrument in the vehicle 200 that requires power consumption. For example, the electrical equipment 203 may be a drive motor, air conditioner, compressor, seat heating module, vehicle computer, central control display, headlights, USB interface, etc.

[0075] In one embodiment, the battery pack 202 can be charged via a charging station, which can be an AC charging station or a DC charging station. For an AC charging station, the onboard charger in the vehicle 200 converts the AC power into DC power, and the DC power is then charged into the battery pack 202. For a DC charging station, the DC power is directly charged into the battery pack 202.

[0076] The structure of the battery pack according to the embodiment of the present application will be described in detail below.

[0077] FIG3 is a schematic structural diagram of a battery pack 300 provided in an embodiment. As shown in FIG3 , the battery pack 300 may include a housing 301 and a plurality of battery modules 302 disposed within the housing 301 .

[0078] In one embodiment, the battery modules 302 in the battery pack 300 are connected in series.

[0079] In another embodiment, the battery modules 302 in the battery pack 300 may include a series connection and a parallel connection. For example, the battery pack 300 may include a first battery module, a second battery module, and a third battery module. Each of the first battery module, the second battery module, and the third battery module may include at least one battery module 302. The first battery module and the second battery module are connected in series, and the first battery module and the third battery module are connected in parallel.

[0080] Conventional battery modules have a complex structure and high internal resistance, resulting in high costs and low output power. Therefore, simplifying the structure and reducing the internal resistance of battery modules have become research challenges in the field of secondary battery technology. The battery modules of the present invention, through structural improvements, can address these issues. This is discussed in detail below.

[0081] 4 is a schematic side cross-sectional view of the battery module 400 in the first embodiment, FIG. 5 is a schematic structural view of the battery cell 2 of the battery module 400 in the first embodiment, and FIG. 6 is a schematic partial enlarged structural view of point A in FIG. 4 .

[0082] As shown in FIG4 , a battery module 400 may include multiple pole cores 2, multiple transition guides 4, an end guide 1, multiple wicking rings 3, multiple first sealing rings 6, an electrolyte 7, and a first packaging shell 5. The pole cores 2, transition guides 4, wicking rings 3, first sealing rings 6, and electrolyte 7 may all be enclosed within the first packaging shell 5. A portion of the end guide 1 is located within the first packaging shell 5, while another portion of the end guide 1 may be exposed outside the first packaging shell 5.

[0083] As shown in FIG4 , multiple pole cores 2 can be arranged sequentially along a first direction. It should be understood that the number of pole cores 2 shown in FIG4 is merely an example; in practice, the number of pole cores 2 can be at least two. The first direction shown in FIG4 is merely an example; in practice, the first direction can be determined as needed, for example, any linear or curved direction.

[0084] As shown in Figures 4 to 6, the two opposite ends of the electrode core 2 along the first direction can be respectively referred to as the positive terminal (indicated by "+") and the negative terminal (indicated by "-"). The positive terminal is the end of the electrode core 2 with a higher potential, and the negative terminal is the end of the electrode core 2 with a lower potential. The electrode cores 2 can be arranged in the order of positive terminal - negative terminal - positive terminal - negative terminal - ..., that is, for any two adjacent electrode cores 2, the negative terminal of the preceding electrode core 2 is arranged to face the positive terminal of the following electrode core 2, and the positive terminal of the preceding electrode core 2 is arranged to face away from the negative terminal of the following electrode core 2.

[0085] As shown in Figures 4 and 6 , a transition guide 4 is provided between each pair of adjacent pole cores 2. The transition guide 4 is electrically connected to the negative terminal of one pole core 2 and the positive terminal of another pole core 2, allowing multiple pole cores 2 to be connected in series along a first direction. The positive and negative terminals at opposite ends of the multiple series-connected pole cores 2 can each be electrically connected to an end guide 1.

[0086] As shown in FIG4 and FIG5 , the electrode core 2 may include a main body 21 , a positive electrode tab 23 and a negative electrode tab 22 , wherein the positive electrode tab 23 and the negative electrode tab 22 are located at opposite ends of the main body 21 along a first direction.

[0087] The main body 21 may include a positive electrode current collector, a negative electrode current collector, and a separator located between the positive electrode current collector and the negative electrode current collector, wherein both the positive electrode current collector and the negative electrode current collector may be attached with active materials. The main body 21 may be formed by a winding process or a lamination process, and accordingly, the pole core 2 may be a "rolled core type" or a "stacked core type". Schematically, the pole core 2 may be a sodium ion battery cell, the material of the positive electrode current collector may be an aluminum alloy, the active material on the positive electrode current collector may be a sodium-containing compound, the material of the negative electrode current collector may be an aluminum alloy, and the active material on the negative electrode current collector may be a lithium or sodium-intercalable material. Alternatively, the pole core 2 may be a type other than a sodium ion battery cell, such as a lithium ion battery cell.

[0088] The positive electrode tab 23 can be connected to an area of ​​the positive electrode current collector where no active material is provided, and the negative electrode tab 22 can be connected to an area of ​​the negative electrode current collector where no active material is provided. Illustratively, the material of the positive electrode tab 23 can be the same as that of the positive electrode current collector, and the material of the negative electrode tab 22 can be the same as that of the negative electrode current collector. The number of positive and negative electrode tabs 23 and 22 can be set as needed, for example, each can be multiple. In this embodiment, the end where the positive electrode tab 23 is located is the positive end of the electrode core 2, and the end where the negative electrode tab 22 is located is the negative end of the electrode core 2.

[0089] In this embodiment, the electrode core 2 may be, for example, a sodium ion battery cell, and the materials of the positive electrode collector, the positive electrode tab, the negative electrode collector, and the negative electrode tab of the electrode core 2 may all be aluminum alloy.

[0090] Figure 7 is a schematic diagram of the exploded structure of the transition guide member 4 in Example 1. As shown in Figure 7, the transition guide member 4 can be generally plate-shaped or strip-shaped. The length L1 (the length direction can be substantially consistent with the first direction), width D, and thickness T of the transition guide member 4 can be designed as needed. For example, the length L1 can be between 20 mm and 200 mm (e.g., 20 mm, 60 mm, 100 mm, 200 mm, etc.), the width D can be between 20 mm and 100 mm (e.g., 20 mm, 50 mm, 100 mm, etc.), and the thickness T can be between 0.2 mm and 5 mm (e.g., 0.2 mm, 1 mm, 2.5 mm, 5 mm, etc.).

[0091] As shown in Figure 7, the transition guide 4 may include a fourth weld 41, a first fusible portion 42, and a third weld 43, connected sequentially along a lengthwise direction (which may coincide with the first direction). The fourth weld 41 and the third weld 43 are welded locations (or welds) at opposite ends of the transition guide 4. In this embodiment, the first fusible portion 42 may be provided in each transition guide 4; alternatively, the first fusible portion 42 may be provided in only some of the transition guides 4, for example, at least one transition guide 4. For ease of reference, the transition guide 4 provided with the first fusible portion 42 may be referred to as the first transition guide. The specific configurations of the fourth weld 41, the first fusible portion 42, and the third weld 43 may be determined as needed and are not limited in this embodiment. In other embodiments, the transition guide 4 may not be provided with the first fusible portion 42.

[0092] As shown in FIG7 , the length of the fourth weld portion 41 can be illustratively less than the length of the third weld portion 43. The length L2 of the first fusible portion 42 can be designed as needed. In an exemplary embodiment, the length L2 of the first fusible portion 42 can be between 0.1 mm and 5 mm (e.g., 0.1 mm, 1 mm, 5 mm, etc.). In an exemplary embodiment, the width and thickness of the first fusible portion 42 can be the same as the width and thickness of the transition guide 4.

[0093] As shown in Figures 6 and 7 , every two adjacent electrode cores 2 can be connected via a transition guide 4. Specifically, the fourth weld portion 41 of the transition guide 4 can be welded to the negative electrode tab 22 of the preceding electrode core 2, and the third weld portion 43 of the transition guide 4 can be welded to the positive electrode tab 23 of the succeeding electrode core 2. To ensure the feasibility and reliability of the welding process, the fourth weld portion 41, the negative electrode tab 22, the third weld portion 43, and the positive electrode tab 23 can be made of the same material, such as aluminum alloy.

[0094] In other embodiments, the positive tab 23 / negative tab 22 of the electrode core 2 can be connected to the transition guide 4 using other suitable methods. In this case, the portion of the transition guide 4 connected to the negative tab 22 and the portion connected to the positive tab 23 can be referred to as a connecting portion (corresponding to the fourth weld portion 41 and the third weld portion 43 described above, respectively). The connecting portion and the positive tab 23 / negative tab 22 can be made of different materials. Alternatively, in other embodiments, the transition guide 4 can be connected to other structures of the electrode core 2, such as a current collector.

[0095] In this embodiment, the first fusible portion 42 may be located on the electrical connection path between the negative terminal of the preceding pole core 2 and the positive terminal of the following pole core 2, or in other words, the negative terminal, the first fusible portion 42 and the positive terminal are connected in series.

[0096] In one implementation of this embodiment, the first dissolving portion 42 can be made of a readily soluble metal. A readily soluble metal refers to a metal that can undergo an electrochemical reaction with the electrolyte 7 under specific conditions, where the potential of the readily soluble metal reaches a dissolution potential. Illustratively, the readily soluble metal can be one or more of copper, magnesium, manganese, iron, cobalt, nickel, zinc, gallium, germanium, yttrium, zirconium, niobium, molybdenum, technetium, ruthenium, rhodium, palladium, silver, cadmium, indium, tin, and antimony.

[0097] In another implementation of this embodiment, the first fusible portion 42 can be made of an alloy formed by a soluble metal and aluminum, wherein the mass proportion of the soluble metal in the alloy can be between 1% and 70% (for example, 1%, 20%, 35%, 70%, etc.).

[0098] During operation, the battery module 400 may be over-discharged. Over-discharge refers to the state in which a fully charged battery module 400 continues to discharge when it reaches the rated capacity (rated capacity refers to the amount of electricity that the battery module 400 can discharge at a specified current) during the discharge process, or the voltage is less than or equal to the cut-off voltage (the cut-off voltage refers to the lower limit of the voltage for normal external discharge of the battery module 400). During over-discharge, the potential of the negative terminal of the pole core 2 will increase, and the potential of the positive terminal of the pole core 2 will decrease. If over-discharge protection is not performed, over-discharge may cause the battery module 400 to fail, and may also cause safety problems such as explosion, fire or leakage of the battery module 400 due to continuous discharge, heat generation and gas generation of the battery module 400. In this embodiment, by providing a first fuse 42, the battery module 400 can be protected from over-discharge to avoid the above-mentioned defects. The specific principles of over-discharge protection are as follows:

[0099] As shown in Figures 6 and 7, when the voltage of the battery module 400 is less than or equal to a voltage threshold (referred to as the second voltage threshold to distinguish it from the first voltage threshold of the battery cell below), the battery module 400 may enter an over-discharge state. This voltage threshold can be lower than the aforementioned cutoff voltage. For example, when the readily soluble metal in the first fusible portion 42 is copper, the second voltage threshold of the battery module 400 can be -n*1.2V, where n is the number of electrode cores 2 connected in series. During over-discharge, the potential at the negative terminal of the electrode core 2 will increase. The potential of the first fusible portion 42 near the negative terminal is the same as that of the negative terminal (the reason for this potential parity will be explained below), so the potential of the first fusible portion 42 also increases. When the potential of the first fusible portion 42 reaches its own dissolution potential, it can undergo an electrochemical reaction with the electrolyte 7 and dissolve, disconnecting the transition guide 4 and thereby severing the electrical connection between the negative and positive terminals of two adjacent electrode cores 2. As a result, the discharge circuit of the entire battery module 400 is disconnected, thereby avoiding the risk of failure of the battery module 400 and the risk of explosion, fire or leakage. It is easy to understand that by providing the first fuse 42, the safety performance of the battery module 400 in the over-discharge state can be guaranteed, which is conducive to the battery module 400 successfully passing the over-discharge test (the over-discharge test is a safety test whose purpose is to test whether the battery will explode, catch fire or leak due to over-discharge. If the battery has any of the above conditions, it will fail the over-discharge test, otherwise it can pass the over-discharge test).

[0100] As can be understood from the above, to provide over-discharge protection for the battery module 400, at least one transition guide 4 needs to be provided with the first fuse 42. As an example, the first fuse 42 can be provided in each transition guide 4, which facilitates the mass production of the transition guides 4.

[0101] As shown in Figures 6 and 8 , the first fusible portion 42 of each transition guide 4 may be surrounded by a wicking ring 3 . The wicking ring 3 overlaps the first fusible portion 42. For example, both sides of the wicking ring 3 may be longer than the first fusible portion 42. The wicking ring 3 has adsorption properties, serving to absorb and store electrolyte 7 (described below), allowing the first fusible portion 42 to fully contact the electrolyte 7 for electrochemical reactions. The wicking ring 3 may, for example, have a porous structure, utilizing its multiple micropores for adsorption. The porosity of the wicking ring 3 (porosity refers to the percentage of pore volume in a material to its total volume) can be designed based on product requirements. For example, the porosity of the wicking ring 3 can range from 35% to 90% (e.g., 35%, 60%, 90%, etc.). Illustratively, the wicking ring 32 may be made of polypropylene, polycarbonate, polyethylene, polyurethane, etc. In addition, the liquid-absorbing ring 3 may also have insulating properties to ensure that the portions on both sides of the first fusible portion 42 are in an open circuit state after the first fusible portion 42 is fused. It is understandable that the liquid-absorbing ring 3 outside the first fusible portion 42 is not necessary.

[0102] As shown in Figure 4, the end guide 1 includes a first end guide 11 and a second end guide 12. The first end guide 11 and the second end guide 12 are respectively located at opposite ends of a plurality of pole cores 2 connected in series. The first end guide 11 is connected to the positive end of one of the pole cores 2, and the second end guide 12 is connected to the negative end of the other pole core 2. Schematically, the first end guide 11 and the second end guide 12 can both be roughly plate-shaped or strip-shaped. Schematically, the length, width and thickness of the first end guide 11 (or the second end guide 12) can be equal to the length, width and thickness of the transition guide 4, and will not be repeated here.

[0103] Figure 9 is a partially enlarged cross-sectional view of the structure at point C in Figure 4 . As shown in Figure 9 , one end of the first end flow guide 11 can be welded to the positive tab 23 of a battery core 2. The welded portion (or welded area) between the first end flow guide 11 and the positive tab 23 can be referred to as the first weld. The end of the first end flow guide 11 facing away from the positive tab 23 can serve as the positive electrode column of the battery module 400.

[0104] Figure 10 is a partial, enlarged, cross-sectional view of the structure at point B in Figure 4 . As shown in Figure 10 , the second end flow guide 12 may include a second weld portion 12a. The second weld portion 12a is the welded portion of the second end flow guide 12 and can be welded to the negative electrode tab 22 of a core 2. To ensure the feasibility and reliability of the welding process, the first end flow guide 11, the positive electrode tab 23, the second weld portion 12a, and the negative electrode tab 22 may be made of the same material, such as aluminum alloy.

[0105] In other embodiments, the first end flow guide 11 can be connected to the positive electrode tab 23 of the electrode core 2 by other suitable means, and the materials of the first end flow guide 11 and the positive electrode tab 23 can be different. The second end flow guide 12 can be connected to the negative electrode tab 22 of the electrode core 2 by other suitable means. In this case, the portion of the second end flow guide 12 connected to the negative electrode tab 22 can be referred to as a connecting portion (corresponding to the second welding portion 12a described above), and the connecting portion and the negative electrode tab 22 can be made of different materials. Alternatively, in other embodiments, at least one of the first end flow guide 11 and the second end flow guide 12 can be connected to other structures of the electrode core 2, such as a current collector.

[0106] As shown in Figure 10, the second end flow guide 12 may further include a second fusible portion 12c and a portion 12b excluding the second fusible portion 12c and the second welded portion 12a. The second fusible portion 12c is connected between the second welded portion 12a and portion 12b. The second fusible portion 12c is located in the electrical connection path of the second end flow guide 12. Portion 12b can serve as the negative electrode of the battery module 400. The specific structure of the second welded portion 12a, the second fusible portion 12c, and these portions can be determined as needed and are not limited in this embodiment. The length of the second fusible portion 12c can be designed as needed. For example, the length of the second fusible portion 12c can be between 0.1 mm and 5 mm (e.g., 0.1 mm, 1 mm, 5 mm, etc.). For example, the width and thickness of the second fusible portion 12c can be the same as the width and thickness of the second end flow guide 12. In other embodiments, the second end flow guide 12 may not include the second fusible portion 12c.

[0107] In this embodiment, the material of the second fusible portion 12c in the second end flow guide 12 can be the same as that of the second fusible portion 12c in the transition flow guide 4, and description thereof will not be repeated here. The second fusible portion 12c in the second end flow guide 12 can also be used to provide over-discharge protection for the battery module 400, ensuring that the battery module 400 successfully passes the over-discharge test. The specific principles are the same as those described above and will not be repeated here.

[0108] As can be understood from the foregoing, over-discharge protection for the battery module 400 only requires providing a fuse (in this embodiment of the present application, the first fuse and the second fuse are collectively referred to as the fuse) in the transition guide 4 or the second end guide 12. As an example, fuses can be provided in both the transition guide 4 and the second end guide 12, which facilitates mass production.

[0109] As shown in Figure 10, the second fusible portion 12c of the second end flow guide 12 may be surrounded by a liquid-absorbing ring 3. The liquid-absorbing ring 3 may be an annular structure that circumscribes the entire circumference and overlaps the second fusible portion 12c. The liquid-absorbing ring 3 has adsorption properties, serving to absorb and store the electrolyte 7 (described below), allowing the second fusible portion 12c to fully contact the electrolyte 7 for electrochemical reactions. The liquid-absorbing ring 3 may, for example, have a porous structure, utilizing its multiple micropores for adsorption. The porosity of the liquid-absorbing ring 3 (porosity refers to the percentage of pore volume in a material to its total volume) can be designed based on product requirements. For example, the porosity of the liquid-absorbing ring 3 may range from 35% to 90% (e.g., 35%, 60%, 90%, etc.). Illustratively, the liquid-absorbing ring 32 may be made of polypropylene, polycarbonate, polyethylene, polyurethane, etc. Furthermore, the liquid-absorbing ring 3 may have insulating properties to ensure that the portions on both sides of the second fusible portion 12c remain open-circuited after the second fusible portion 12c has dissolved. It is understandable that the liquid-absorbing ring 3 on the periphery of the second fusible portion 12c is not necessary.

[0110] As shown in Figure 4 , each transition guide 4, first end guide 11, and second end guide 12 may be surrounded by a first sealing ring 6. The first sealing ring 6 may be an annular structure that surrounds the entire periphery. Illustratively, there may be a single first sealing ring 6 around the first end guide 11, each transition guide 4, and second end guide 12. Alternatively, multiple first sealing rings 6 may be arranged side by side around the periphery of these components, and these first sealing rings 6 may be tightly fitted one after the other.

[0111] In this embodiment, the width of the first sealing ring 6 can be, for example, between 1 mm and 20 mm (e.g., 1 mm, 6 mm, 20 mm, etc.), and the thickness of the first sealing ring 6 can be, for example, 0.6 mm. Illustratively, the first sealing ring 6 can be made of a polymer material such as polyethylene, polypropylene, or polyacrylic acid. Furthermore, the first sealing ring 6 can have insulating properties.

[0112] As shown in Figure 6, the width of the first sealing ring 6 on the transition guide 4 can be smaller than the width of the transition guide 4. The first sealing ring 6 can maintain a certain distance from the two electrode cores 2 on opposite sides of the transition guide 4. As an example, the distances between the first sealing ring 6 and the two electrode cores 2 can be substantially equal, and the first fusible portion 42 in the transition guide 4 can be located between the negative electrode tab 22 and the first sealing ring 6.

[0113] As shown in FIG9 , the width of the first sealing ring 6 on the first end flow guide 11 may be smaller than the width of the first end flow guide 11 , and the first sealing ring 6 may maintain a certain distance from the positive electrode tab 23 of the electrode core 2 .

[0114] As shown in FIG10 , the width of the first sealing ring 6 on the second end flow guide 12 can be smaller than the width of the second end flow guide 12 , and the first sealing ring 6 can maintain a certain distance from the negative electrode tab 22 of the electrode core 2 . The second fusible portion 12 c in the second end flow guide 12 can be located between the negative electrode tab 22 and the first sealing ring 6 .

[0115] In this embodiment, the first sealing ring 6 can be connected to the first packaging shell 5, and the two together form a plurality of accommodating cavities, which will be described below.

[0116] In this embodiment, the first packaging shell 5 can have insulating properties. Illustratively, the first packaging shell 5 can be made of an aluminum-plastic film. As shown in FIG4 , the first packaging shell 5 can be a long, sac-like structure formed by folding two shell walls 51 in half. Each shell wall 51 can be provided with a plurality of receiving grooves formed by continuous punching. Each pair of receiving grooves on the two shell walls 51 can enclose a receiving space 5a, and these receiving spaces 5a can be arranged sequentially along the first direction. In this embodiment, the first packaging shell 5 is a single packaging shell having multiple receiving spaces 5a.

[0117] As shown in Figures 4, 6, 9, and 10, the first encapsulating shell 5 can be disposed around the first end flow guide 11, multiple pole cores 2, multiple transition flow guides 4, the second end flow guide 12, multiple fuses, multiple wicking rings 3, and multiple first sealing rings 6. The inner wall of each accommodating space 5a in the first encapsulating shell 5 can be connected to the outer circumference of the first sealing ring 6, with the inner wall of the accommodating space 5a wrapping around the first sealing ring 6 along its circumferential direction. This connection can be achieved, for example, by heat fusion. Thus, each first sealing ring 6 separates two adjacent accommodating spaces 5a, preventing them from communicating. Consequently, the first encapsulating shell 5 and the first sealing rings 6 on opposite sides of each pole core 2 can each form an accommodating cavity, each of which is isolated from the others. In other words, the first sealing rings 6 on all transition flow guides 4 divide the interior space of the first encapsulating shell 5 into multiple accommodating cavities. A pole core 2, its corresponding fuse, and wicking ring 3 can be accommodated within a single accommodating cavity. During normal operation, for any two adjacent electrode cores 2, the positive electrode tab 23 of one electrode core 2 is separated from the negative electrode tab 22 of the other electrode core 2 by the first sealing ring 6. Ion exchange does not occur between the positive electrode tab 23 and the negative electrode tab 22 (i.e., the ion channel is blocked), resulting in a high potential for the positive electrode tab 23 and a low potential for the negative electrode tab 22. Therefore, the fuse portion, connected in series with the negative electrode tab 22 and located between the negative electrode tab 22 and the first sealing ring 6, also has a low potential. A portion of the first end flow guide 11 and a portion of the second end flow guide 12 can be exposed from each end of the first packaging shell 5 to function as a terminal post.

[0118] In another embodiment, the first end flow guide 11 and the second end flow guide 12 can be completely housed within the first packaging shell 5. A first electrode and a second electrode can be respectively disposed at opposite ends of the first packaging shell 5. The first electrode can be completely located outside the first packaging shell 5, or a portion of the first electrode can be exposed outside the first packaging shell 5 while the remaining portion extends into the first packaging shell 5. These two structures can be collectively referred to as "first electrode exposed outside the first packaging shell 5." The second electrode can be completely located outside the first packaging shell 5, or a portion of the second electrode can be exposed outside the first packaging shell 5 while the remaining portion extends into the first packaging shell 5. These two structures can be collectively referred to as "second electrode exposed outside the first packaging shell 5." The first end flow guide 11 is connected to the first electrode, which serves as the positive electrode of the entire battery module 400. The second end flow guide 12 is connected to the second electrode, which serves as the negative electrode of the entire battery module 400. It will be appreciated that FIG4 is a side cross-sectional view of the battery module 400. When viewed from a top-down perspective (i.e., with the line of sight along the vertical direction), the peripheries of the two shell walls 51 of the first packaging shell 5 are connected and sealed. Specifically, in areas where the first sealing ring 6 is provided, both shell walls 51 are connected to the first sealing ring 6; in areas where the first sealing ring 6 is not provided, the two shell walls 51 can be directly connected, for example, by heat-melting the two shell walls 51 together.

[0119] As shown in Figures 4, 6, 9, and 10, each accommodating cavity can accommodate an electrolyte 7. Since the electrolytes 7 in each accommodating cavity are isolated from each other, each pole core 2 can operate normally and can also avoid the problem of electrolyte decomposition in the battery module 400 at higher voltages. The electrolyte 7 can be an organic solvent, such as an organic solvent containing sodium ions. The pole core 2 and the corresponding dissolving part and the liquid wicking ring 3 can be immersed in the electrolyte 7. The adsorption and storage effect of the liquid wicking ring 3 on the electrolyte 7 can ensure that the dissolving part is in full contact with the electrolyte 7, facilitating an electrochemical reaction in the dissolving part during over-discharge.

[0120] In Example 1, any two adjacent pole cores 2 in the battery module 400 can be connected in series via a transition guide 4. There is no complex electrical connection structure between any two adjacent pole cores 2, making the structure of the battery module 400 relatively simple, which helps reduce the cost of the battery module 400. In particular, when the pole core 2 is a sodium-ion battery cell, the characteristic that the positive and negative tabs 23 and 22 of the pole core 2 are both aluminum foil can be utilized. A single transition guide 4, also made of aluminum foil, can be used to connect adjacent pole cores 2. This can greatly reduce the connection size and help improve the energy density of the battery module 400. In addition, the internal resistance of the battery module 400 is low, resulting in a higher output power of the battery module 400. Because multiple pole cores 2 are connected in series in the battery module 400, the battery module 400 has a higher voltage and energy density, which helps reduce the number of cells connected in series in the battery pack, thereby simplifying the structure of the energy storage system 120.

[0121] Furthermore, the provision of the fusible portion protects the battery module 400 from over-discharge and ensures that the battery module 400 successfully passes the over-discharge test. Furthermore, the provision of the liquid-siphoning ring 3 ensures sufficient contact between the fusible portion and the electrolyte 7, facilitating electrochemical dissolution of the fusible portion during over-discharge, thereby protecting the battery module 400 from over-discharge.

[0122] Figure 11 is a schematic cross-sectional structural diagram of the battery module 500 in Example 2, Figure 12 is a schematic partial enlarged structural diagram of the structure shown in Figure 11 at point D, and Figure 13 is a schematic cross-sectional structural diagram of the transition guide 4, the liquid suction ring 3 and the second sealing ring 6a in this Example 2.

[0123] As shown in Figures 11 to 13 , unlike the solution of Example 1, the outer circumference of the transition guide member 4 of Example 2 can be surrounded by two spaced-apart second sealing rings 6a. The spacing L3 between the two second sealing rings 6a can be designed as needed. To ensure that the two second sealing rings 6a are appropriately spaced on the transition guide member 4, the length L1 of the transition guide member 4 can be appropriately increased. For example, the length L1 of the transition guide member 4 can be between 40 mm and 400 mm (e.g., 40 mm, 60 mm, 200 mm, 400 mm, etc.), and the spacing L3 between the two second sealing rings 6a can be 0.25*L1 (e.g., 16 mm). In this embodiment of the present application, the second sealing rings 6a and the first sealing ring 6 can be collectively referred to as sealing rings.

[0124] As shown in Figure 12, the two second sealing rings 6a on the transition guide 4 maintain a certain distance from the two electrode cores 2 at opposite ends of the transition guide 4. Illustratively, the distance between one second sealing ring 6a and the negative electrode tab 22 can be substantially equal to the distance between the other second sealing ring 6a and the positive electrode tab 23. Both second sealing rings 6a can be located on the side of the liquid suction ring 3 facing away from the negative electrode tab 22, with the second sealing ring 6a closer to the liquid suction ring 3 being spaced apart from the liquid suction ring 3. At least one transition guide 4 can have a first fusible portion 44. In the second embodiment, for ease of distinction, the transition guide 4 having the first fusible portion 44 can be referred to as the second transition guide.

[0125] As shown in Figures 11 and 12 , unlike the solution of Example 1, the battery module 500 of Example 2 further includes multiple second packaging shells 13. The housing assembly formed by these multiple second packaging shells 13 can be referred to as a packaging shell, and each second packaging shell 13 can form a storage space. The second packaging shells 13 of Example 2 have a similar structure to the first packaging shell 5 of Example 1. The difference is that each second packaging shell 13 of Example 2 can be correspondingly disposed on the periphery of a pole core 2, as well as on the peripheries of two second sealing rings 6a at opposite ends of the pole core 2 and two flow guides, wherein the flow guides can be first end flow guides 11, transition flow guides 4, or second end flow guides 12. Each second packaging shell 13 can be connected to the two second sealing rings 6a within the second packaging shell 13 to form a storage cavity, so that each pole core 2, the corresponding liquid suction ring 3, and the first fusible portion 44 are all enclosed within a storage cavity. Each storage cavity contains electrolyte 7. A gap is formed between each adjacent second packaging shell 13, and a partial area of ​​the transition guide 4 can be exposed through the gap. A portion of the first end guide 11 can be exposed from the left second packaging shell 13 to serve as a positive electrode column, and a portion of the second end guide 12 can be exposed from the right second packaging shell 13 to serve as a negative electrode column.

[0126] In the second embodiment, the gap between two adjacent second packaging shells 13 can be used for voltage collection. The voltage collection device can be connected to the transition guide 4 through this gap to achieve voltage collection. Voltage collection can monitor the voltage of each pole core 2 to detect pole core 2 failure.

[0127] The battery module 500 of the second embodiment also has the advantages of the battery module 400 of the first embodiment, which will not be repeated here. In addition, the second embodiment forms a gap between adjacent second packaging shells 13 by providing multiple second packaging shells 13, so as to facilitate voltage acquisition and monitor the voltage of each battery cell. Voltage monitoring can detect whether the battery cell has failed, for example, it can detect whether there are abnormalities such as excessive voltage drop or excessive temperature on the guide member. In other embodiments, different from the first and second embodiments, the first end guide member 11 and the sealing ring thereon may not be provided, and / or the second end guide member 12 and the sealing ring thereon may not be provided, the positive electrode ear of the battery module may be directly connected to the positive electrode column, and the negative electrode ear may be directly connected to the negative electrode column. The battery cell and the electrolyte may be encapsulated in the packaging shell in any other suitable manner, which is not limited in the embodiments of the present application.

[0128] An embodiment of the present application provides a battery cell, which includes a packaging shell and a pole core 2 packaged therein. The battery cell may further include one or two current guides. When the battery cell includes one current guide, one end of the current guide can be connected to the positive or negative pole ear of the battery cell, and the other end of the current guide can be exposed outside the packaging shell. When the battery cell includes two current guides, one end of one current guide can be connected to the negative pole ear of the battery cell (the current guide can be called a first current guide), and the other end of the current guide can be exposed outside the packaging shell; one end of the other current guide can be connected to the positive pole ear of the battery cell (the current guide can be called a second current guide), and the other end of the current guide can be exposed outside the packaging shell. Compared with conventional battery cells, the battery cell of the embodiment of the present application has fewer components, a simpler structure, and a lower cost. Due to the simple structure of the battery cell of the embodiment of the present application, the internal resistance is low and the output power is high. In addition, one end of the flow guide of the battery cell of the embodiment of the present application is located inside the packaging shell, which is conducive to ensuring a reliable connection between the flow guide and the tab, thereby ensuring the reliability of the battery cell.

[0129] The battery cell of the embodiment of the present application can achieve the sealing of the package shell by various suitable methods. For example, the edges of the package shell can be directly connected (for example, by hot-melt connection), and one end of the flow guide can be exposed to achieve the sealing of the package shell. Alternatively, a sealing ring can be wrapped around the periphery of the flow guide, and the outer peripheral surface of the sealing ring can be connected to the inner wall of the package shell to form a receiving cavity, thereby achieving the sealing of the package shell. The sealing of the package shell by the sealing ring is consistent with that described in the above-mentioned embodiment 2, and will not be repeated here.

[0130] The battery cell in the embodiments of the present application can be a sodium-ion battery cell, and both the positive and negative tabs can be made of aluminum alloy. The guide member can also be made of aluminum alloy and welded to the positive and / or negative tabs. Using the same material as the tabs for welding, the guide member can reduce the joint dimensions and improve the energy density of the battery cell.

[0131] The battery cell in the embodiment of the present application may include a flow guide connected to the negative electrode ear, and a fusible portion (which may be referred to as a first fusible portion) may be provided on the flow guide. The fusible portion is located in the packaging shell and is immersed in the electrolyte. The first fusible portion is used to react electrochemically with the electrolyte and disconnect the electrical connection between the negative electrode ear and the flow guide when the voltage of the battery cell is less than or equal to the first voltage threshold. The first voltage threshold may be -1.2V, for example. A fusible portion may be provided on the flow guide to implement over-discharge protection of the battery cell and ensure that the battery cell passes the over-discharge test. Implementing over-discharge protection by the fusible portion is consistent with that described in the above-mentioned embodiment 2 and will not be repeated here.

[0132] The battery cell in the embodiments of the present application may include a liquid-absorbing ring disposed on the first fuse portion. The liquid-absorbing ring is positioned around the periphery of the first fuse portion and within the packaging shell. The liquid-absorbing ring absorbs and stores electrolyte, ensuring sufficient contact between the first fuse portion and the electrolyte, facilitating an electrochemical reaction in the first fuse portion during over-discharge.

[0133] In the embodiment of the present application, multiple battery cells can be connected in series to form a battery module, and any two battery cells can be electrically connected via a flow guide (the flow guide is the same as the transition flow guide 4 described above). The two ends of the flow guide can be located in two adjacent packaging shells, respectively; alternatively, one end of the flow guide can be located in one packaging shell (the flow guide can be considered to belong to the battery cell to which the packaging shell belongs), and the other end of the flow guide can be located outside another adjacent packaging shell (the flow guide can be considered not to belong to the battery cell to which the other packaging shell belongs). In the embodiment of the present application, any battery cell in the battery module can have one or two flow guides, and the number of flow guides possessed by each battery cell in the battery module can be the same or different.

[0134] For example, the battery module 500 shown in FIG11 may include a plurality of battery cells connected in series, each of which may include a second packaging shell 13 and an electrode core 2 encapsulated therein. Schematically, in order from left to right:

[0135] Among the first three battery cells in the battery module 500, each battery cell may further include a flow guide, for example, the first battery cell may further include a first end flow guide 11, one end of the first end flow guide 11 is located in the second packaging shell 13; the second battery cell may further include a transition flow guide 4, the two ends of the transition flow guide 4 are respectively located in the first second packaging shell 13 and the second second packaging shell 13; the third battery cell may further include a transition flow guide 4, the two ends of the transition guide 4 are respectively located in the second second packaging shell 13 and the third second packaging shell 13.

[0136] The fourth cell (or the end cell) in the battery module 500 may also include two flow guides, which may be a transition flow guide 4 and a second end flow guide 12, respectively. The two ends of the transition flow guide 4 are located in the third second packaging shell 13 and the fourth second packaging shell 13, respectively, and one end of the second end flow guide 12 is located in the fourth second packaging shell 13. For the fourth cell, its second end flow guide 12 is connected to the negative electrode tab, and its transition guide 4 is connected to the positive electrode tab. Based on the above description, the second end flow guide 12 of the fourth cell can be referred to as a first flow guide, and the transition guide 4 of the fourth cell can be referred to as a second flow guide. In the above embodiments, the battery module is described as including multiple pole cores 2 connected in series. In other embodiments, the pole cores 2 in the battery module can be connected both in series and in parallel. For example, the battery module may include a first battery cell, a second battery cell, and a third battery cell. The first battery cell and the second battery cell are connected in series, and the third battery cell is connected in parallel with the first battery cell. The third battery cell may be a single battery cell or include multiple battery cells connected in series.

[0137] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A battery cell, characterized in that: The battery cell includes a pole core, a flow guide, an electrolyte and a packaging shell, wherein the pole core and the electrolyte are both packaged in the packaging shell, and the pole core is immersed in the electrolyte; the pole core has a pole ear, one end of the flow guide is connected to the pole ear and is located in the packaging shell, and the other end of the flow guide is exposed outside the packaging shell.

2. The battery cell according to claim 1, characterized in that: The battery cell includes a sealing ring, which surrounds the outer circumference of the guide member and is located in the packaging shell, and the outer circumference of the sealing ring is connected to the inner wall of the packaging shell; the electrolyte is located on one side of the sealing ring that is away from the guide member and exposed outside the packaging shell.

3. The battery cell according to claim 1 or 2, characterized in that: One end of the guide member is welded to the pole lug, the pole lug is made of aluminum alloy, and the material of the welding point between the one end of the guide member and the pole lug is aluminum alloy.

4. The battery cell according to claim 1 or 2, characterized in that: The pole ear is a negative pole ear; The guide member includes a first fuse portion, which is located in the packaging shell and immersed in the electrolyte. The first fuse portion is used to generate an electrochemical reaction with the electrolyte and disconnect the electrical connection between the negative electrode ear and the guide member when the voltage of the battery cell is less than or equal to a first voltage threshold.

5. The battery cell according to claim 4, characterized in that: The material of the first dissolving part is a soluble metal or an alloy of a soluble metal and aluminum, and the soluble metal is one of copper, magnesium, manganese, iron, cobalt, nickel, zinc, gallium, germanium, yttrium, zirconium, niobium, molybdenum, technetium, ruthenium, rhodium, palladium, silver, cadmium, indium, tin, and antimony.

6. The battery cell according to claim 4, characterized in that: The battery core further comprises a liquid absorption ring, which is sleeved on the outer periphery of the first fuse part and is used for absorbing the electrolyte.

7. A battery module, characterized in that: The battery module comprises a plurality of battery cells according to any one of claims 1 to 6, the plurality of battery cells are connected in series, and any two adjacent battery cells among the plurality of battery cells are electrically connected via one of the flow guides.

8. The battery module according to claim 7, characterized in that: The flow guide member of the battery cell at the end of the multiple battery cells includes a first flow guide member and a second flow guide member; one end of the first flow guide member is connected to the negative electrode ear of the battery cell at the end and is located in the packaging shell of the battery cell at the end, and the other end of the first flow guide member is exposed outside the packaging shell where the battery cell at the end is located; one end of the second flow guide member is connected to the positive electrode ear of the battery cell at the end and is located in the packaging shell of the battery cell at the end, and the other end of the second flow guide member is electrically connected to another battery cell adjacent to the battery cell at the end.

9. The battery module according to claim 8, characterized in that: The battery cell at the end includes a sealing ring, which surrounds the outer periphery of the first flow guide and the outer periphery of the second flow guide, and is located in the packaging shell where the battery cell at the end is located, and the outer peripheral surface of the sealing ring is connected to the inner wall of the packaging shell; the electrolyte is located between the sealing ring on the outer periphery of the first flow guide and the sealing ring on the outer periphery of the second flow guide.

10. The battery module according to claim 8 or 9, characterized in that: The first flow guide member includes a second fuse portion, which is located in the packaging shell of the terminal battery cell and immersed in the electrolyte. The second fuse portion is used to generate an electrochemical reaction with the electrolyte and disconnect the electrical connection between the negative electrode ear of the terminal battery cell and the first flow guide member when the voltage of the battery module is less than or equal to a second voltage threshold.

11. The battery module according to claim 10, characterized in that: The battery core at the end further includes a liquid absorption ring, which is sleeved on the outer circumference of the second fuse portion and is used for absorbing the electrolyte.

12. A battery module, characterized in that: The battery module comprises a plurality of pole cores, at least one transition guide, at least one sealing ring, an electrolyte and a packaging shell, wherein the plurality of pole cores, the at least one transition guide and the at least one sealing ring are all packaged in the packaging shell; The plurality of pole cores are connected in series, and the pole ears of any two adjacent pole cores among the plurality of pole cores are electrically connected through one of the transition guides; The outer circumference of each transition guide is surrounded by the sealing ring, and the outer circumferential surface of each sealing ring is connected to the inner wall of the packaging shell. The sealing ring on at least one transition guide divides the internal space of the packaging shell into a plurality of accommodating cavities, and each of the plurality of accommodating cavities accommodates the electrolyte and one of the pole cores, wherein the pole core is immersed in the electrolyte.

13. The battery module according to claim 12, characterized in that: Among any two adjacent pole cores among the multiple pole cores, the positive pole ear of one pole core is welded to one end of the transition guide member, and the negative pole ear of the other pole core is welded to the other end of the transition guide member. The materials of the positive pole ear and the negative pole ear of each pole core among the multiple pole cores are both aluminum alloy, and the materials of the welding points at both ends of each transition guide member are both aluminum alloy.

14. The battery module according to claim 12 or 13, characterized in that: At least one of all the transition guides includes a first fuse portion, the first fuse portion is located between the negative pole ear of the pole core electrically connected to the transition guide and the sealing ring on the transition guide, the first fuse portion is immersed in the electrolyte, and the first fuse portion is used to generate an electrochemical reaction with the electrolyte when the voltage of the battery module is less than or equal to a second voltage threshold, and disconnect the electrical connection between the negative pole ear and the positive pole ear of the pole core electrically connected to the negative pole ear through the transition guide.

15. The battery module according to claim 12 or 13, characterized in that: The battery module also includes a first end flow guide member and a second end flow guide member; one end of the first end flow guide member is electrically connected to the positive pole ear of the pole core located at the head end of the multiple pole cores connected in series and is located in the packaging shell, and the other end of the first end flow guide member is exposed outside the packaging shell; one end of the second end flow guide member is electrically connected to the negative pole ear of the pole core located at the end end of the multiple pole cores connected in series, and the other end of the second end flow guide member is exposed outside the packaging shell.

16. The battery module according to claim 15, characterized in that: The sealing ring is surrounded by the outer circumference of the first end guide piece and the second end guide piece. The sealing ring on the first end guide piece and the sealing ring on the second end guide piece are both located inside the packaging shell and are connected to the inner wall of the packaging shell. The sealing ring on the first end guide piece closes one end of the packaging shell, and the sealing ring on the second end guide piece closes the other end of the packaging shell.

17. The battery module according to claim 15, characterized in that: The positive pole ear of the pole core at the first end is welded to the first end guide piece, and the materials of the welding place between the positive pole ear of the pole core at the first end and the first end guide piece are both aluminum alloy, and the negative pole ear of the pole core at the terminal end is welded to the second end guide piece, and the materials of the welding place between the negative pole ear of the pole core at the terminal end and the second end guide piece are both aluminum alloy.

18. The battery module according to claim 15, characterized in that: The second end guide member includes a second fuse portion, which is located between the negative pole ear of the terminal core and the sealing ring on the second end guide member, and the second fuse portion is immersed in the electrolyte. The second fuse portion is used to generate an electrochemical reaction with the electrolyte and disconnect the electrical connection between the second end guide member and the negative pole ear when the voltage of the battery module is less than or equal to a second voltage threshold.

19. A battery pack, characterized in that: The battery pack comprises a plurality of battery modules according to any one of claims 7 to 18; The multiple battery modules are connected in series; Alternatively, the plurality of battery modules include a first battery module, a second battery module and a third battery module, wherein the first battery module is connected in series with the second battery module, and the first battery module is connected in parallel with the third battery module.

20. An energy storage system, characterized in that: The energy storage system includes a power converter and a battery pack as described in claim 19, wherein the power converter is electrically connected to the battery pack, and is used to convert the electric energy output by the battery pack and output it to an external load or a power grid, and / or, the power converter is used to convert the electric energy output by a power supply device and output it to the battery pack.

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