Battery cell and energy storage device

Abstract

This application provides a battery cell and an energy storage device, relating to the field of battery technology. In this battery cell, a first one-way valve and a second housing are provided, both located within the second housing. The first one-way valve is located within the first housing. When the pressure within the first housing is greater than or equal to a first preset pressure, the first one-way valve opens and releases the gas from the first housing into the second housing. This alleviates the phenomenon of gas accumulation inside the electrode assembly, helps suppress side reactions, and thus improves the electrical performance of the secondary battery. Furthermore, by providing the second housing, a sealed space is created for the gas release process, reducing the risk of contaminants from the external environment entering the first housing during the venting process of the first one-way valve. The electrode posts passing through the second housing facilitate the connection of the secondary battery to an external circuit for charging and discharging.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a battery cell and an energy storage device. Background Technology

[0002] The information disclosed in this background section is intended only to enhance the understanding of the general background of this disclosure and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art.

[0003] During long-term cycling, irreversible side reactions can easily occur between the electrolyte and the active material layer of the electrode assembly in a secondary battery, generating gas. As cycling continues, the generated gas gradually accumulates inside the battery and may form bubbles on the surface of the active material layer, affecting the stability of the electrode interface and further promoting the occurrence of side reactions, thus negatively impacting the electrical performance of the secondary battery. Summary of the Invention

[0004] In view of this, the purpose of this application is to provide a battery cell and an energy storage device, which aims to solve the technical problem of how to suppress the side reactions of secondary batteries.

[0005] To solve the above-mentioned technical problems, the technical solution adopted in this application is as follows: In a first aspect, embodiments of this application provide a battery cell, comprising: a secondary battery, including a first housing, an electrode assembly, a terminal post, and a first one-way gas valve, wherein the electrode assembly is located within the first housing, the terminal post passes through the first housing and is electrically connected to the electrode assembly, and the first one-way gas valve is disposed within the first housing; and a second housing, wherein both the first housing and the first one-way gas valve are located within the second housing, and the terminal post passes through the second housing; when the pressure within the first housing is greater than or equal to a first preset pressure, the first one-way gas valve opens and discharges the gas within the first housing into the second housing.

[0006] In some embodiments of the first aspect, the battery cell further includes a compression member and an elastic member, both of which are located within the second housing. The compression member is located between the first housing and the elastic member, and is connected to the first housing. The elastic member is connected to both the compression member and the second housing.

[0007] In some embodiments of the first aspect, the extruder is a pressure plate, the pressure plate including a first plate surface and a second plate surface disposed opposite to each other, the first plate surface abutting against the first housing, and the elastic element being connected to the second plate surface.

[0008] In some embodiments of the first aspect, the elastic element is a cylindrical spring, and the battery cell further includes a support column located within the second housing. The support column is located on the side of the extruder facing away from the first housing. The support column is fixedly connected to the extruder or the second housing. The cylindrical spring is sleeved on the support column and abuts against the extruder and the second housing, respectively.

[0009] In some embodiments of the first aspect, the battery cell further includes a guide located within the second housing, one of the extrusion member and the second housing being fixedly connected to the guide, and the other of the extrusion member and the second housing being provided with a guide groove, the guide passing through the guide groove.

[0010] In some embodiments of the first aspect, the first one-way valve includes a first valve body, a first piston, and a first elastic element. The first valve body passes through the first housing and defines a first piston chamber. The first valve body has a first exhaust port communicating with the first piston chamber at one end near the electrode assembly and a first exhaust hole communicating with the first piston chamber at one end away from the electrode assembly. The first piston and the first elastic element are both located in the first piston chamber. The first elastic element is located at the end of the first piston away from the first exhaust port and is connected to both the first piston and the first valve body. The first piston is used to cover or open the first exhaust port.

[0011] In some embodiments of the first aspect, the battery cell further includes a second one-way valve, which is disposed in the second housing; when the pressure inside the second housing is greater than or equal to a second preset pressure, the second one-way valve opens and discharges the gas inside the second housing to the outside of the second housing.

[0012] In some embodiments of the first aspect, the second one-way valve is offset from the first one-way valve.

[0013] In some embodiments of the first aspect, the second one-way valve includes a second valve body, a second piston, and a second elastic element. The second valve body passes through the second housing and defines a second piston chamber. The second valve body has a second exhaust port communicating with the second piston chamber at one end near the first housing and a second exhaust hole communicating with the second piston chamber at one end away from the first housing. The second piston and the second elastic element are both located in the second piston chamber. The second elastic element is located at the end of the second piston away from the second exhaust port. The second elastic element is connected to the second piston and the second valve body respectively. The second piston is used to cover or open the second exhaust port.

[0014] Secondly, embodiments of this application provide an energy storage device, including the battery cell described in any of the embodiments of the first aspect above.

[0015] The beneficial effects of this application are as follows: In the battery cell provided in this application, a first one-way gas valve and a second housing are provided, both located within the second housing. The first one-way gas valve is located within the first housing. When the pressure inside the first housing is greater than or equal to a first preset pressure, the first one-way gas valve opens and discharges the gas inside the first housing into the second housing. This alleviates the phenomenon of gas accumulation inside the electrode assembly, helps suppress the occurrence of side reactions, and thus improves the electrical performance of the secondary battery. Furthermore, by providing the second housing, a sealed space is created for the gas discharge process, reducing the risk of contaminants from the external environment entering the first housing during the venting process of the first one-way gas valve. The electrode posts passing through the second housing facilitate the connection of the secondary battery to an external circuit for charging and discharging. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 A three-dimensional structural schematic diagram of a battery cell in an embodiment of this application is shown; Figure 2 It shows Figure 1 A schematic diagram of the decomposed structure; Figure 3 It shows Figure 1 A cross-sectional view of the battery cell section; Figure 4 It shows Figure 1 Schematic diagram of the cross-sectional structure at point BB; Figure 5 It shows Figure 4 A magnified structural diagram of region C in the middle; Figure 6 It shows Figure 4 A magnified structural diagram of region D in the middle.

[0018] Explanation of key component symbols: 10-Battery cell; 100-Secondary battery; 110-First housing; 120-Electrode assembly; 130-Terminal post; 140-First one-way valve; 141-First valve body; 1411-First piston chamber; 1412-First exhaust port; 1413-First exhaust hole; 142-First piston; 143-First elastic element; 200-Second housing; 300-Extrusion part; 310-First plate; 320-Second plate; 330-Guide groove; 400-Elastic element; 500-Support column; 600-Guide element; 700-Second one-way valve; 710-Second valve body; 711-Second piston chamber; 712-Second exhaust port; 713-Second exhaust hole; 720-Second piston; 730-Second elastic element; 800-Protective layer. Detailed Implementation

[0019] The embodiments of this application are described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0020] In the description of this application, the terms "center", "longitudinal", "lateral", "length", "width", "height", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0021] Furthermore, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first and second features are in direct contact, or that they are in indirect contact through an intermediate medium. Moreover, "above" or "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below" or "below" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0022] In the description of this application, the terms "first," "second," etc., are used to distinguish different objects and should not be construed as indicating or implying a specific order or hierarchy, or implicitly specifying the number of technical features indicated. Therefore, a feature marked "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, the term "multiple" means two or more, unless otherwise explicitly defined.

[0023] In the description of this application, unless otherwise explicitly specified, the term "connection" should be interpreted broadly. For example, it can refer to a non-detachable connection, a detachable connection, or a single-piece structure; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0024] In the description of this application, the term "fixed connection" refers to two objects that are connected to each other and whose relative positions remain unchanged under normal use conditions, i.e., they will not easily undergo relative movement (e.g., relative rotation and relative movement); the term "rotational connection" refers to two objects that are connected to each other and can rotate relative to each other; and the term "sliding connection" refers to two objects that are connected to each other and can move relative to each other.

[0025] Secondary batteries are a crucial component of battery packs. During long-term cycling, irreversible side reactions can easily occur between the active material layer of the electrode assembly and the electrolyte, generating gas. As cycling continues, this gas gradually accumulates inside the battery and may form bubbles on the surface of the active material layer, affecting the stability of the electrode interface and further promoting side reactions. This leads to electrical performance problems in secondary batteries, such as capacity decay and decreased cycle performance.

[0026] like Figure 1 As shown, to solve the above-mentioned technical problems, embodiments of this application provide a battery cell 10 including a secondary battery 100, relating to the field of battery technology, mainly applied to battery packs, so as to be indirectly applied to electrical devices and energy storage devices in the form of battery packs. Of course, the battery cell 10 can also be directly applied to energy storage devices and electrical devices without adopting the form of a battery pack.

[0027] For example, energy storage devices can be energy storage containers, energy storage cabinets, energy storage power stations, wind power generation devices, solar power generation devices, mobile power devices, temporary power supply devices, etc.; electrical equipment can be vehicles, computers, ships, spacecraft, etc. Vehicles can be gasoline vehicles, natural gas vehicles, new energy vehicles, etc., and new energy vehicles can be pure electric vehicles, hybrid electric vehicles, range-extended electric vehicles, etc.; spacecraft can be airplanes, rockets, drones, spacecraft, etc.

[0028] It should be noted that the secondary battery 100 mainly relies on the migration of metal ions between the positive and negative electrodes to function. The secondary battery 100 can be rectangular, cylindrical, flat, or other shapes. Classified by packaging method, the secondary battery 100 can be a square battery, cylindrical battery, pouch battery, etc.; classified by metal ion type, the secondary battery 100 can be a lithium-ion battery, sodium-ion battery, etc.; classified by the physical state of the electrolyte, the secondary battery 100 can be a liquid battery, i.e., using a liquid electrolyte (electrolyte); of course, the secondary battery 100 can also be a solid-state battery or a semi-solid-state battery, i.e., the electrolyte is at least partially solid-state, with common materials such as sulfide, oxide, or polymer electrolytes. The solid-state electrolyte can replace the liquid electrolyte and the separator layer between the positive and negative electrodes, providing both ion conduction and isolation functions.

[0029] like Figure 1 , Figure 2 and Figure 4 As shown, the battery cell 10 provided in this embodiment includes a secondary battery 100 and a second housing 200. The secondary battery 100 includes a first housing 110, an electrode assembly 120, a terminal post 130, and a first one-way valve 140. The electrode assembly 120 is located inside the first housing 110, and the terminal post 130 passes through the first housing 110 and is electrically connected to the electrode assembly 120. The first one-way valve 140 is located in the first housing 110. Both the first housing 110 and the first one-way valve 140 are located inside the second housing 200, and the terminal post 130 passes through the second housing 200. When the pressure inside the first housing 110 is greater than or equal to a first preset pressure, the first one-way valve 140 opens and discharges the gas inside the first housing 110 into the second housing 200.

[0030] It is understood that in the battery cell 10 provided in this embodiment, by setting a first one-way gas valve 140 and a second housing 200, both the first housing 110 and the first one-way gas valve 140 are located inside the second housing 200. The first one-way gas valve 140 is located in the first housing 110. When the pressure inside the first housing 110 is greater than or equal to a first preset pressure, the first one-way gas valve 140 opens and discharges the gas inside the first housing 110 into the second housing 200, which alleviates the phenomenon of gas accumulation inside the electrode assembly 120, helps to suppress the occurrence of side reactions, and thus improves the electrical performance of the secondary battery 100.

[0031] In addition, by providing a second housing 200, a sealed space is provided for the gas emission process, reducing the risk of pollutants in the external environment entering the first housing 110 during the exhaust process of the first one-way valve 140; the electrode post 130 passes through the second housing 200, which facilitates the charging and discharging of the secondary battery 100 by connecting it to an external circuit.

[0032] For example, the material of the first housing 110 / the material of the second housing 200 can be aluminum, aluminum alloy, copper, steel, plastic, titanium, etc. When the secondary battery 100 is a soft-pack battery, the first housing 110 can also be an aluminum-plastic film.

[0033] For example, the electrode 130 can be a positive electrode or a negative electrode. The material of the positive electrode can be aluminum, aluminum alloy, etc., and the material of the negative electrode can be copper, copper alloy, copper-aluminum composite material, etc.

[0034] It should be noted that the electrode assembly 120 may include a positive electrode sheet, a negative electrode sheet, and an insulating layer, and is manufactured using a winding process or a stacking process. The insulating layer is disposed between the positive electrode sheet and the negative electrode sheet. The positive electrode sheet includes a positive current collector and a positive active material layer, with the positive active material layer coated on the positive current collector. The negative electrode sheet includes a negative current collector and a negative active material layer, with the negative active material layer coated on the negative current collector. The portion of the positive current collector not coated with the positive active material layer is the positive tab electrically connected to the positive electrode post, and the portion of the negative current collector not coated with the negative active material layer is the negative tab electrically connected to the negative electrode post.

[0035] For example, the material of the separator layer can be polypropylene, polyethylene, etc.; taking lithium ions as an example, the material of the positive electrode current collector can be aluminum, and the material of the positive electrode active material layer can be lithium cobalt oxide, lithium iron phosphate, ternary lithium, lithium manganese oxide, etc.; the material of the negative electrode current collector can be copper, and the negative electrode active material can be graphite, silicon, etc.

[0036] like Figure 1 , Figure 2 and Figure 4As shown, in some embodiments, the battery cell 10 further includes an extrusion member 300 and an elastic member 400. The extrusion member 300 and the elastic member 400 are both located inside the second housing 200. The extrusion member 300 is located between the first housing 110 and the elastic member 400. The extrusion member 300 is connected to the first housing 110, and the elastic member 400 is connected to the extrusion member 300 and the second housing 200 respectively.

[0037] Understandably, under the push of the elastic member 400, the extrusion member 300 can apply a restraining force to the first housing 110, causing the first housing 110 to deform. This helps to squeeze out the gas accumulated inside the electrode assembly 120. When used in conjunction with the first one-way gas valve 140, it can more effectively suppress the occurrence of side reactions, thereby further improving the electrical performance of the secondary battery 100.

[0038] like Figure 1 , Figure 2 and Figure 4 As shown, the extrusion member 300 is a pressure plate, which includes a first plate surface 310 and a second plate surface 320 disposed opposite to each other. The first plate surface 310 abuts against the first housing 110, and the elastic member 400 is connected to the second plate surface 320.

[0039] It is understandable that by using a pressure plate as the extrusion component 300, the force-bearing area of ​​the first housing 110 can be increased, thereby allowing the restraining force to be applied evenly to the first housing 110 and improving the extrusion effect on the gas inside the electrode assembly 120.

[0040] Of course, in the above embodiments, the extrusion component 300 can also be a pressure block, pressure bar, etc., and the structure of the extrusion component 300 is not specifically limited here.

[0041] like Figure 1 , Figure 2 and Figure 4 As shown, the elastic element 400 is a cylindrical spring, and the battery cell 10 also includes a support column 500 located inside the second housing 200. The support column 500 is located on the side of the extruder 300 facing away from the first housing 110. The support column 500 is fixedly connected to the extruder 300 or the second housing 200. The cylindrical spring is sleeved on the support column 500 and abuts against the extruder 300 and the second housing 200 respectively.

[0042] It is understandable that when the elastic element 400 is a cylindrical spring, the support column 500 facilitates the installation of the cylindrical spring, and at the same time, the support column 500 can guide the deformation direction of the cylindrical spring and improve the extension and contraction stability of the cylindrical spring.

[0043] Of course, for the above embodiments, the elastic element 400 can also be a spring sheet, an elastic arm, etc., which can also provide restraint force. The structure of the elastic element 400 is not specifically limited here.

[0044] It should be noted that when the extruder 300 is a pressure plate, the support column 500 is fixedly connected to the second plate surface 320 or the second housing 200, and the column spring abuts against the second plate surface 320; in addition, when the support column 500 is fixedly connected to the extruder 300, the support column 500 can move together with the extruder 300; when the support column 500 is fixedly connected to the second housing 200, the support column 500 and the second housing 200 remain stationary together.

[0045] like Figures 1 to 3 As shown, the battery cell 10 further includes a guide member 600 located in the second housing 200. One of the extrusion member 300 and the second housing 200 is fixedly connected to the guide member 600. The other of the extrusion member 300 and the second housing 200 is provided with a guide groove 330, and the guide member 600 passes through the guide groove 330.

[0046] It is understandable that the guide member 600 and the guide groove 330 cooperate with each other to guide the movement direction of the extruder 300 and improve its movement stability, thereby helping to make the restraining force act evenly on the first housing 110 and improve the gas extrusion effect.

[0047] For example, the guide 600 may be a protruding structure integrally formed with the extruder 300 or the second housing 200, or a guide rail fixed to the extruder 300 or the second housing 200 by means of fasteners or welding. The structure of the guide 600 is not specifically limited here.

[0048] It should be noted that when the extruder 300 is provided with a guide groove 330 and the extruder 300 is a pressure plate, the guide groove 330 penetrates the first plate surface 310 and the second plate surface 320.

[0049] like Figure 1 , Figure 4 and Figure 5 As shown, in some embodiments, the first one-way valve 140 includes a first valve body 141, a first piston 142, and a first elastic member 143. The first valve body 141 passes through the first housing 110 and defines a first piston chamber 1411. The first valve body 141 has a first exhaust port 1412 communicating with the first piston chamber 1411 at one end near the electrode assembly 120, and a first exhaust hole 1413 communicating with the first piston chamber 1411 at one end away from the electrode assembly 120. The first piston 142 and the first elastic member 143 are both located in the first piston chamber 1411. The first elastic member 143 is located at the end of the first piston 142 away from the first exhaust port 1412. The first elastic member 143 is connected to the first piston 142 and the first valve body 141 respectively. The first piston 142 is used to seal or open the first exhaust port 1412.

[0050] Understandably, when the pressure inside the first housing 110 is less than the first preset pressure, the first piston 142 seals the first exhaust port 1412 under the action of the first elastic member 143. At this time, the first exhaust port 1412 and the first exhaust hole 1413 are not interconnected, and the gas cannot pass through the first one-way valve 140. When the pressure inside the first housing 110 is greater than or equal to the first preset pressure, the first piston 142 overcomes the force of the first elastic member 143 under the action of air pressure and opens the first exhaust port 1412. At this time, the first exhaust port 1412 and the first exhaust hole 1413 are interconnected through the first piston chamber 1411. The gas inside the first housing 110 can be discharged into the second housing 200 sequentially through the first exhaust port 1412, the first piston chamber 1411, and the first exhaust hole 1413 until the pressure inside the first housing 110 is less than the first preset pressure. At this time, the first piston 142 re-seals the first exhaust port 1412 under the push of the first elastic member 143, thereby realizing one-way exhaust.

[0051] like Figure 1 , Figure 2 and Figure 4 As shown, in some embodiments, the battery cell 10 further includes a second one-way valve 700, which is disposed in the second housing 200. When the pressure inside the second housing 200 is greater than or equal to a second preset pressure, the second one-way valve 700 opens and discharges the gas inside the second housing 200 to the outside. This helps to balance the air pressure between the first housing 110 and the second housing 200, thereby improving the situation where the gas in the first housing 110 is difficult to discharge due to excessive pressure inside the second housing 200, and also reduces the possibility of the second housing 200 bulging.

[0052] For example, the first preset pressure / second preset pressure can be 0.1 MPa to 0.2 MPa, such as any value from 0.1 MPa, 0.11 MPa, 0.12 MPa, 0.14 MPa, 0.15 MPa, 0.155 MPa, 0.156 MPa, 0.16 MPa, 0.17 MPa, 0.18 MPa, 0.19 MPa and 0.2 MPa or any value from any combination thereof, without being specifically limited here.

[0053] like Figure 1 and Figure 4 As shown, the second one-way valve 700 is further offset from the first one-way valve 140. This reduces the risk of gas discharged from the first one-way valve 140 directly impacting the second one-way valve 700, thus improving the reliability and service life of the second one-way valve 700.

[0054] like Figure 1 , Figure 4 and Figure 6 As shown, the second one-way valve 700 further includes a second valve body 710, a second piston 720, and a second elastic member 730. The second valve body 710 passes through the second housing 200 and defines a second piston chamber 711. The end of the second valve body 710 near the first housing 110 is provided with a second exhaust port 712 communicating with the second piston chamber 711, and the end of the second valve body 710 away from the first housing 110 is provided with a second exhaust hole 713 communicating with the second piston chamber 711. The second piston 720 and the second elastic member 730 are both located in the second piston chamber 711. The second elastic member 730 is located at the end of the second piston 720 away from the second exhaust port 712. The second elastic member 730 is connected to the second piston 720 and the second valve body 710 respectively. The second piston 720 is used to cover or open the second exhaust port 712.

[0055] Understandably, when the pressure inside the second housing 200 is less than the second preset pressure, the second piston 720, under the action of the second elastic element 730, seals the second exhaust port 712. At this time, the second exhaust port 712 and the second exhaust hole 713 are not interconnected, and gas cannot pass through the second one-way valve 700. When the pressure inside the second housing 200 is greater than or equal to the second preset pressure, the second piston 720, under the action of air pressure, overcomes the force of the second elastic element 730 and opens the second exhaust port 712. At this time, the second exhaust port 712 and the second exhaust hole 713 are interconnected through the second piston chamber 711, and the gas inside the second housing 200 can be discharged to the outside of the second housing 200 sequentially through the second exhaust port 712, the second piston chamber 711, and the second exhaust hole 713 until the pressure inside the second housing 200 is less than the second preset pressure. At this time, the second piston 720, under the push of the second elastic element 730, re-seals the second exhaust port 712, thereby realizing one-way exhaust.

[0056] For example, the first elastic element 143 and the second elastic element 730 can be a cylindrical spring, a sheet, an elastic arm, etc., without specific limitations.

[0057] It should be noted that, in addition to the piston-type one-way valve mentioned above, the first one-way valve 140 and the second one-way valve 700 can also be selected as diaphragm-type one-way valves (such as duckbill valves, umbrella valves, etc.), ball-type one-way valves, magnetic one-way valves, etc., which can also achieve one-way exhaust.

[0058] like Figure 1 and Figure 2As shown, in some embodiments, the battery cell 10 further includes a protective layer 800, at least a portion of which is located within the second housing 200. The protective layer 800 wraps around the outer periphery of the terminal post 130, reducing the risk of corrosion of the terminal post 130 by the emitted gas, thereby improving the reliability of the secondary battery 100.

[0059] For example, the material of the protective layer 800 can be polytetrafluoroethylene, polyvinylidene fluoride, polypropylene, polyethylene, polyetheretherketone, etc., without specific limitations.

[0060] To address the aforementioned technical problems, embodiments of this application also provide an energy storage device, including the battery cell 10 from any of the above embodiments.

[0061] It is understood that since the energy storage device provided in this embodiment includes the battery cell 10 in any of the above embodiments, it has all the beneficial effects of the battery cell 10, which will not be described in detail here.

[0062] To better illustrate the beneficial effects of the battery cell 10 provided in this embodiment, some embodiments are provided below for description, as detailed in the table below:

[0063] I. Testing Method: S01. Capacity calibration: Under room temperature conditions, charge the secondary battery 100 at a constant current and constant voltage of 0.33C. When the charging voltage reaches 3.65V, switch to constant voltage charging. The cutoff current is 0.05C, and the upper limit of charging time is 240min. After standing for 5min, discharge the battery under test at a constant current of 0.33C. The discharge cutoff voltage is 2.5V, and the upper limit of discharge time is 240min. Record the initial discharge capacity C0 of the secondary battery 100. S02. Cyclic Test: Charge the secondary battery 100 with a constant current and constant voltage of 0.33C. When the charging voltage reaches 3.65V, switch to constant voltage charging. The cutoff current is 0.05C, and the maximum charging time is 240min. After resting for 5min, discharge the secondary battery 100 with a constant current of 0.33C. The discharge cutoff voltage is 2.5V, and the maximum discharge time is 240min, completing one cycle. S03. Repeat step S02 to cycle the secondary battery 100 for 1000 cycles, and record the discharge capacity C after 1000 cycles. 1000 ; S04. Capacity retention rate calculation: Based on the initial discharge capacity C0 and the discharge capacity C after 1000 cycles. 1000 Calculate the capacity retention rate of the secondary battery 100: Capacity retention rate = (C 1000 / C0)×100%.

[0064] II. Test Results: In the secondary battery 100 of Example 1, no compression member 300 and elastic member 400 are provided, that is, there is no restraining force acting on the first housing 110. The cycle retention rate of the secondary battery 100 is tested and calculated to be 96.51%.

[0065] In the secondary battery 100 of Example 2, a pressing member 300 and an elastic member 400 are provided, that is, there is a restraining force acting on the first housing 110. The cycle retention rate of the secondary battery 100 is tested and calculated to be 98.62%, which is an improvement compared to Example 1.

[0066] The secondary battery 100 of Example 1 and the secondary battery 100 of Example 2 were disassembled respectively. It was observed that the brown spots and impurities on the electrode of the latter were significantly reduced compared with the former, indicating that the side reaction phenomenon was further improved.

[0067] In the description of this application, the terms "some embodiments," "one embodiment," "example," "specific example," "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In the description of this application, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0068] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A battery cell, characterized in that, include: A secondary battery (100) includes a first housing (110), an electrode assembly (120), a terminal post (130), and a first one-way valve (140). The electrode assembly (120) is located inside the first housing (110), the terminal post (130) passes through the first housing (110) and is electrically connected to the electrode assembly (120), and the first one-way valve (140) is located in the first housing (110). The second housing (200) is located inside the first housing (110) and the first one-way valve (140), and the pole post (130) passes through the second housing (200). When the pressure inside the first housing (110) is greater than or equal to the first preset pressure, the first one-way valve (140) opens and discharges the gas inside the first housing (110) into the second housing (200).

2. The battery cell according to claim 1, characterized in that, The battery cell further includes an extrusion member (300) and an elastic member (400). The extrusion member (300) and the elastic member (400) are both located inside the second housing (200). The extrusion member (300) is located between the first housing (110) and the elastic member (400). The extrusion member (300) is connected to the first housing (110), and the elastic member (400) is connected to both the extrusion member (300) and the second housing (200).

3. The battery cell according to claim 2, characterized in that, The extrusion member (300) is a pressure plate, which includes a first plate surface (310) and a second plate surface (320) disposed opposite to each other. The first plate surface (310) abuts against the first housing (110), and the elastic member (400) is connected to the second plate surface (320).

4. The battery cell according to claim 2 or 3, characterized in that, The elastic element (400) is a cylindrical spring. The battery cell also includes a support column (500) located inside the second housing (200). The support column (500) is located on the side of the extrusion member (300) facing away from the first housing (110). The support column (500) is fixedly connected to the extrusion member (300) or the second housing (200). The cylindrical spring is sleeved on the support column (500). The cylindrical spring abuts against the extrusion member (300) and the second housing (200) respectively.

5. The battery cell according to claim 2 or 3, characterized in that, The battery cell also includes a guide (600) located inside the second housing (200). One of the extruder (300) and the second housing (200) is fixedly connected to the guide (600). The other of the extruder (300) and the second housing (200) is provided with a guide groove (330). The guide (600) passes through the guide groove (330).

6. The battery cell according to claim 1, characterized in that, The first one-way valve (140) includes a first valve body (141), a first piston (142), and a first elastic element (143). The first valve body (141) passes through the first housing (110) and defines a first piston chamber (1411). The first valve body (141) has a first exhaust port (1412) communicating with the first piston chamber (1411) at one end near the electrode assembly (120), and a first exhaust port (1412) communicating with the first piston chamber (1411) at the other end away from the electrode assembly (120). The first piston chamber (1411) is connected to the first exhaust port (1413). The first piston (142) and the first elastic element (143) are both located in the first piston chamber (1411). The first elastic element (143) is located at the end of the first piston (142) away from the first exhaust port (1412). The first elastic element (143) is connected to the first piston (142) and the first valve body (141) respectively. The first piston (142) is used to cover or open the first exhaust port (1412).

7. The battery cell according to claim 1, characterized in that, The battery cell also includes a second one-way air valve (700), which is located in the second housing (200). When the pressure inside the second housing (200) is greater than or equal to a second preset pressure, the second one-way air valve (700) opens and discharges the gas inside the second housing (200) to the outside of the second housing (200).

8. The battery cell according to claim 7, characterized in that, The second one-way air valve (700) is offset from the first one-way air valve (140).

9. The battery cell according to claim 7, characterized in that, The second one-way valve (700) includes a second valve body (710), a second piston (720), and a second elastic element (730). The second valve body (710) passes through the second housing (200) and defines a second piston chamber (711). A second exhaust port (712) communicating with the second piston chamber (711) is provided at one end of the second valve body (710) near the first housing (110), and a second exhaust port (712) is provided at the other end of the second valve body (710) away from the first housing (110). The second exhaust port (713) is connected to the second piston chamber (711). The second piston (720) and the second elastic member (730) are both located in the second piston chamber (711). The second elastic member (730) is located at the end of the second piston (720) away from the second exhaust port (712). The second elastic member (730) is connected to the second piston (720) and the second valve body (710) respectively. The second piston (720) is used to cover or open the second exhaust port (712).

10. An energy storage device, characterized in that, Includes the battery cell according to any one of claims 1 to 9.

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