Battery cell, battery apparatus and electrical apparatus

Abstract

Provided is a battery cell, the battery cell comprising a housing, a first electrode terminal and an electrode assembly. The first electrode terminal is arranged on a wall portion of the housing. The electrode assembly is arranged in the housing, and comprises a first electrode sheet; the first electrode sheet comprises an electrode sheet body and a first tab, the first tab being arranged on one side of the electrode sheet body in a first direction; the first tab comprises a first portion and a second portion, the first portion and the first electrode terminal being welded to form a first welding mark, and the second portion being connected to the first portion and the electrode sheet body; and in a second direction, the size of the second portion is greater than the size of the first portion, and the second portion protrudes outward from at least one side of the first portion. The battery cell has high reliability.

Description

Battery cells, battery packs and electrical devices

[0001] Cross-reference to related applications

[0002] This application claims priority to Chinese patent application 202510009978.2, filed on January 3, 2025, entitled “Battery cell, battery device and power consumption device”, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application relates to the field of battery technology, specifically to a battery cell, a battery device, and an electrical device. Background Technology

[0004] Energy conservation and emission reduction are key to the sustainable development of the automotive industry, and electric vehicles, due to their energy-saving and environmentally friendly advantages, have become an important component of this sustainable development. For electric vehicles, battery technology is a crucial factor in their development.

[0005] Improving the reliability of individual battery cells is a pressing issue in battery technology. Summary of the Invention

[0006] In view of the above problems, this application provides a battery cell, a battery device, and an electrical device that can improve the reliability of the battery cell.

[0007] In a first aspect, this application provides a battery cell, which includes a casing, a first electrode terminal, and an electrode assembly. The first electrode terminal is disposed on the wall of the casing. The electrode assembly is disposed within the casing and includes a first electrode plate. The first electrode plate includes an electrode plate body and a first electrode tab. The first electrode tab is disposed on one side of the electrode plate body in a first direction and includes a first portion and a second portion. The first portion is welded to the first electrode terminal to form a first solder mark, and the second portion connects the first portion and the electrode plate body. Along a second direction, the size of the second portion is larger than the size of the first portion, and the second portion protrudes outward from at least one side of the first portion. The second direction and the first direction are perpendicular to each other and to the thickness direction of the electrode plate body.

[0008] In the technical solution of this application embodiment, the first part of the first tab is directly connected to the first electrode terminal, which helps to reduce power loss during power transmission. Along the second direction, the size of the second part is larger than that of the first part, and the second part protrudes outward from at least one side of the first part, meaning that the overcurrent cross-sectional area of ​​the first tab changes abruptly between the second and first parts. When a short circuit occurs externally to the battery cell, the short-circuit current generates a large amount of heat as it flows from the second part to the first part due to the abrupt change in the overcurrent cross-sectional area between the first and second parts, causing the first tab to melt in time, thereby reducing the risk of thermal runaway caused by the battery cell failing to disconnect the circuit in time. The aforementioned battery cell possesses high reliability.

[0009] In one or more embodiments of the first aspect, the second portion protrudes outward from both sides of the first portion along the second direction.

[0010] In the above scheme, since the second part protrudes outward from both sides of the first part along the second direction, the degree of abrupt change in the cross-sectional area of ​​the first tab can be further increased. In the event of an external short circuit in the battery cell, the first tab can melt more quickly, further improving the reliability of the battery cell.

[0011] In one or more embodiments of the first aspect, the first portion has a first side in the second direction, the second portion has a second side in the second direction, and the second side protrudes from the first side; the first electrode includes a third side, and the third side connects the first side and the second side.

[0012] The electrode assembly includes multiple first tabs, which are stacked and welded to form a second solder mark; the third side and the first side intersect at a first intersection point, or the extension line of the third side and the extension line of the first side intersect at a first intersection point; along the first direction, the minimum distance between the second solder mark and the first intersection point is L, which satisfies: 0.5mm≤L≤8mm.

[0013] In the above scheme, when L ≥ 0.5 mm, the area of ​​the melting region of the first tab can be relatively large, allowing the first tab to melt in a timely manner within the preset melting region. This reduces the risk of the battery cell catching fire due to the increased time for internal short circuits caused by the first tab failing to melt at the preset position. When L ≤ 8 mm, the proportion of the larger second part in the first tab can be higher, which is beneficial to improving the structural strength of the first tab and the structural stability of the battery cell. Therefore, when 0.5 mm ≤ L ≤ 8 mm, the battery cell can achieve both high reliability and high structural stability.

[0014] In one or more embodiments of the first aspect, 1mm ≤ L ≤ 5mm.

[0015] In the above scheme, when L ≥ 1 mm, the area of ​​the melting region of the first tab can be further increased, enabling the first tab to melt in a timely manner within the preset melting region. This further reduces the risk of the battery cell catching fire due to the increased time for internal short circuits caused by the first tab failing to melt at the preset position. When L ≤ 5 mm, the proportion of the larger second part in the first tab can be further increased, which is beneficial to further improving the structural strength of the first tab and the structural stability of the battery cell. Therefore, when 1 mm ≤ L ≤ 5 mm, the structural stability of the battery cell can be further improved while simultaneously enhancing its reliability.

[0016] In one or more embodiments of the first aspect, the electrode body has a first edge, and a first electrode tab is connected to the first edge; the third side has a first end and a second end, the first end is connected to the first side, the second end is connected to the second side, and the distance between the third side and the first edge gradually increases from the second end to the first end.

[0017] In the above scheme, since the distance between the third side and the first edge gradually increases from the second end to the first end, the risk of stress concentration is low at the connection points between the third side and the second side, and between the third side and the first side, thus the first electrode lug has high structural strength.

[0018] In one or more embodiments of the first aspect, the angle between the third side and the first edge is α, satisfying: 0°<α≤80°.

[0019] In the above scheme, when α > 0°, the third side is inclined relative to the first edge, which facilitates a smooth transition between the first side, the third side, and the second side, reducing the risk of stress concentration in the first tab and improving the structural strength of the first tab. When α ≤ 80°, it facilitates a significant change in the cross-sectional area between the first and second parts, allowing the first tab to melt in time and ensuring high reliability of the battery cell. Therefore, when 0° < α ≤ 80°, both high structural strength of the first tab and high reliability of the battery cell can be achieved.

[0020] In one or more embodiments of the first aspect, 10°≤α≤40°.

[0021] In the above scheme, when α ≥ 10°, the transition between the first side, the third side, and the second side is smoother, further reducing the risk of stress concentration in the first tab and improving its structural strength. When α ≤ 80°, the change in the cross-sectional area between the first and second parts is more pronounced, allowing the first tab to melt in time and further improving the reliability of the battery cell. Therefore, when 10° ≤ α ≤ 40°, the reliability of the battery cell can be further improved while simultaneously enhancing the structural strength of the first tab.

[0022] In one or more embodiments of the first aspect, the first electrode tab further includes a first rounded edge and a second rounded edge, the first side and the third side are connected by the first rounded edge, and the second side and the third side are connected by the second rounded edge.

[0023] In the above scheme, since the first side and the third side are connected by the first rounded corner edge, and the second side and the third side are connected by the second rounded corner edge, the transition between the first side and the third side, as well as between the second side and the third side, is smoother, which can reduce the risk of stress concentration in the first electrode tab and improve the structural strength of the first electrode tab.

[0024] In one or more embodiments of the first aspect, the first part further includes a top edge and a third rounded corner edge, the top edge being located at the end of the first electrode tab away from the electrode body, and the top edge and the first side edge being connected by the third rounded corner edge.

[0025] In the above scheme, since the top edge and the first side edge are connected by the third rounded corner edge, the transition between the top edge and the first side edge is smoother, which can reduce the risk of stress concentration in the first electrode lug and improve the structural strength of the first electrode lug.

[0026] In one or more embodiments of the first aspect, the battery cell further includes a second electrode terminal disposed on the wall of the housing; the electrode assembly further includes a second electrode plate with opposite polarity to the first electrode plate, the second electrode plate includes a second tab, and the second tab is welded to the second electrode terminal to form a third solder mark.

[0027] In the above scheme, the second tab is directly connected to the second electrode terminal, which can further reduce the loss during the power transmission process.

[0028] In one or more embodiments of the first aspect, the resistivity of the second electrode is lower than that of the first electrode; the minimum current-carrying cross-sectional area of ​​the first electrode is S1, and the minimum current-carrying cross-sectional area of ​​the second electrode is S2, satisfying: 60%≤S2 / S1≤100%.

[0029] In the above scheme, because the resistivity of the second tab is lower than that of the first tab, the second tab has better current-carrying capacity than the first tab. When S2 / S1 ≥ 60%, the second tab can have a larger current-carrying cross-sectional area, giving it better current-carrying capacity, and thus giving the battery cell as a whole better current-carrying capacity. When S2 / S1 ≤ 100%, in the event of an external short circuit in the battery cell, the fuse can be made to melt at the location of the abrupt change in the current-carrying cross-section in the first tab, so that the battery cell melts in time at a preset position, reducing the risk of thermal runaway caused by the inability to cut off the circuit in time due to cross-melting of the battery cell. The above battery cell has high reliability. Therefore, when 60% ≤ S2 / S1 ≤ 100%, the battery cell can achieve both good current-carrying capacity and high reliability.

[0030] In one or more embodiments of the first aspect, 65% ≤ S2 / S1 ≤ 90%.

[0031] In the above scheme, when S2 / S1 ≥ 65%, the current-carrying cross-sectional area of ​​the second tab can be further increased, giving the second tab better current-carrying capacity, thereby further improving the current-carrying capacity of the battery cell. When S2 / S1 ≤ 90%, in the event of an external short circuit in the battery cell, the risk of thermal runaway caused by cross-fusing of the battery cell due to the fuse not occurring at the preset fuse position can be further reduced, thus preventing the circuit from being cut off in time. This further improves the reliability of the battery cell. Therefore, when 65% ≤ S2 / S1 ≤ 95%, while further improving the reliability of the battery cell, it also enables the battery cell to have a high current-carrying capacity.

[0032] In one or more embodiments of the first aspect, the melting point of the first electrode is less than the melting point of the second electrode.

[0033] In the above scheme, since the melting point of the first tab is lower than that of the second tab, the first tab can melt faster than the second tab, which can further shorten the time of melting of the battery cell and further improve the reliability of the battery cell.

[0034] In one or more embodiments of the first aspect, the first electrode is made of aluminum and the second electrode is made of copper.

[0035] In one or more embodiments of the first aspect, along the second direction, the maximum size of the first tab is W2, and the width of the first portion is W1, satisfying: 20%≤W1 / W2≤65%.

[0036] In the above scheme, when W1 / W2 ≥ 20%, the larger second part accounts for a higher proportion of the first tab, resulting in higher strength of the first tab. When W1 / W2 ≤ 65%, the size difference between the first and second parts is significant, leading to a larger abrupt change in the current-carrying cross-sectional area of ​​the first tab, which allows for timely melting of the first tab and thus ensures high reliability of the battery cell. Therefore, when 20% ≤ W1 / W2 ≤ 65%, both high reliability of the battery cell and high strength of the first tab are achieved.

[0037] In one or more embodiments of the first aspect, 45% ≤ W1 / W2 ≤ 60%.

[0038] In the above scheme, when W1 / W2 ≥ 45%, the proportion of the larger second part in the first tab is further increased, which can further improve the strength of the first tab. When W1 / W2 ≤ 60%, the size difference between the first and second parts is further increased, the degree of abrupt change in the current-carrying cross-sectional area of ​​the first tab is further increased, the time required for the first tab to melt is further shortened, and the reliability of the battery cell is further improved. Therefore, when 45% ≤ W1 / W2 ≤ 60%, the reliability of the battery cell is further improved, and the strength of the first tab is also further improved.

[0039] In one or more embodiments of the first aspect, the electrode assembly includes a plurality of first tabs, which are stacked and welded to form a second solder mark, wherein the first solder mark is located within the second solder mark.

[0040] In the above scheme, since multiple first tabs are stacked and welded to form a second solder mark, the difficulty of welding multiple first tabs to the first electrode terminal can be reduced.

[0041] In one or more embodiments of the first aspect, the second part includes a first sub-part and a second sub-part, the first sub-part and the second sub-part being arranged sequentially along a first direction, the first sub-part being closer to the first part than the second sub-part; along a second direction, the size of the second sub-part is larger than the size of the first sub-part, and the second sub-part protrudes outward from at least one side of the first sub-part; along a second direction, the size of the first sub-part is larger than the size of the first part, and the first sub-part protrudes outward from at least one side of the first part.

[0042] In the above scheme, because the size of the second sub-part is larger than the size of the first sub-part along the second direction, the second sub-part protrudes outward from at least one side of the first sub-part; and because the size of the first sub-part is larger than the size of the first part along the second direction, the first sub-part protrudes outward from at least one side of the first part. The width of the first tab gradually decreases, which can reduce the risk of wrinkling and tearing during the rolling process of the first tab due to excessive abrupt changes in the size of the first tab.

[0043] In one or more embodiments of the first aspect, the electrode assembly is a wound structure, and the first electrode includes a plurality of first tabs, which are stacked together.

[0044] Among the above solutions, the wound electrode assembly has higher processing efficiency.

[0045] In one or more embodiments of the first aspect, the electrode assembly is a stacked structure, and the electrode assembly includes a plurality of first electrodes, with the first tabs of the plurality of first electrodes stacked together.

[0046] In the above scheme, the stacked electrode assembly has a high energy density.

[0047] In one or more embodiments of the first aspect, the battery cell is a lithium-ion battery cell, and the first electrode is a positive electrode.

[0048] In one or more embodiments of the first aspect, the battery cell is a sodium-ion battery cell, and the first electrode is a positive electrode or a negative electrode.

[0049] Secondly, this application provides a battery device that includes the battery cell described in one or more of the above embodiments.

[0050] In the above solutions, since the battery cells in one or more of the above embodiments have high reliability, the battery device including the battery cells in one or more of the above embodiments also has high reliability.

[0051] Thirdly, this application provides a battery device that includes a battery cell or a battery device as described in one or more of the above embodiments, wherein the battery cell or battery device is used to provide electrical energy.

[0052] In the above solutions, since the battery cells or battery devices in one or more of the above embodiments have high reliability, the battery devices including the battery cells or battery devices in one or more of the above embodiments also have high reliability.

[0053] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the other objects, features and advantages of this application more obvious and understandable, specific embodiments of this application are given below. Attached Figure Description

[0054] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0055] Figure 1 is a schematic diagram of the vehicle structure according to some embodiments of this application;

[0056] Figure 2 is an exploded view of a battery device according to some embodiments of this application;

[0057] Figure 3 is an exploded view of a battery cell according to some embodiments of this application;

[0058] Figure 4 is a schematic diagram of the structure of an electrode assembly according to some embodiments of this application;

[0059] Figure 5 is a schematic diagram of the structure of the first electrode sheet in some embodiments of this application;

[0060] Figure 6 is a magnified view of part A in Figure 5;

[0061] Figure 7 is a schematic diagram of the structure of the second pole piece in some embodiments of this application;

[0062] Figure 8 is a magnified view of part B in Figure 7;

[0063] Figure 9 is a schematic diagram of the structure of an electrode assembly according to some other embodiments of this application;

[0064] Figure 10 is a magnified view of part B in Figure 9;

[0065] Figure 11 is a schematic diagram of the structure of the first electrode sheet in some embodiments of this application;

[0066] Figure 12 is a schematic diagram of a portion of the structure of a battery cell according to some embodiments of this application;

[0067] Figure 13 is a magnified view of point C in Figure 12.

[0068] The reference numerals in the detailed embodiments are as follows:

[0069] 1000 - Vehicle; 200 - Controller; 300 - Motor; 100 - Battery Unit; 11 - Housing; 111 - First Housing; 112 - Second Housing; 12 - Battery Cell; 121 - Casing; 1211 - End Cap; 1212 - Housing; 122 - Electrode Assembly; 1223 - First Electrode; 1224 - Electrode Body; 1225 - First Tab; 1226 - First Part; 1227 - Second Part; 1228 - First Side; 1229 - Second Side; 1230 - Third Side ; 12301 - First end; 12302 - Second end; 1231 - First edge; 1232 - First rounded corner edge; 1233 - Second rounded corner edge; 1234 - Top edge; 1235 - Third rounded corner edge; 1236 - Second electrode tab; 1237 - Second electrode plate; 123 - First electrode terminal; 124 - Second electrode terminal; 125 - First solder mark; 126 - Third solder mark; 127 - Second solder mark; 128 - First intersection point; X - Second direction; Y - First direction; Z - Thickness direction of electrode plate body. Embodiments of the present invention

[0070] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0071] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms in the specification, claims and foregoing description of the drawings of this application include and have, and any variations thereof, and are intended to cover non-exclusive inclusion.

[0072] In the description of the embodiments of this application, technical terms such as "first," "second," etc., are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0073] References to embodiments herein mean that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0074] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple groups" refers to two or more (including two groups), and "multiple pieces" refers to two or more (including two pieces).

[0075] In this embodiment of the application, the battery cell can be a secondary battery, which refers to a battery cell that can be recharged to activate the active materials and continue to be used after the battery cell has been discharged.

[0076] Battery cells include, but are not limited to, lithium-ion batteries, sodium-ion batteries, sodium-lithium-ion batteries, lithium metal batteries, sodium metal batteries, lithium-sulfur batteries, magnesium-ion batteries, nickel-metal hydride batteries, nickel-cadmium batteries, lead-acid batteries, etc.

[0077] A single battery cell typically includes an electrode assembly. The electrode assembly includes a positive electrode, a negative electrode, and a separator. During the charging and discharging process of a single battery cell, active ions (such as lithium ions) repeatedly insert and extract between the positive and negative electrodes. The separator, positioned between the positive and negative electrodes, reduces the risk of short circuits while allowing active ions to pass through.

[0078] In some embodiments, the positive electrode can be a positive electrode sheet, which may include a positive current collector and a positive active material disposed on at least one surface of the positive current collector.

[0079] As an example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive active material is disposed on either or both of the two opposite surfaces of the positive current collector.

[0080] As an example, the positive electrode current collector can be a metal foil or a composite current collector. For example, as a metal foil, it can be aluminum with a silver-plated surface, stainless steel with a silver-plated surface, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel, or titanium, etc. Composite current collectors can include a polymer material base layer and a metal layer. Composite current collectors can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0081] As an example, the positive electrode active material may include at least one of the following materials: lithium phosphate, lithium transition metal oxide, and their respective modified compounds. However, this application is not limited to these materials, and other conventional materials that can be used as battery positive electrode active materials may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium phosphate may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium manganese iron phosphate, and lithium manganese iron phosphate and carbon composites. Examples of lithium transition metal oxide may include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, and lithium nickel cobalt manganese oxide (such as LiNi1 / 3Co1 / 3Mn1 / 3O2 (also referred to as NCM)). 333 LiNi 0.5 Co 0.2 Mn 0.3 O2 (also known as NCM) 523 LiNi 0.5 Co 0.25 Mn 0.25 O2 (also known as NCM) 211 LiNi 0.6 Co 0.2 Mn 0.2 O2 (also known as NCM) 622 LiNi 0.8 Co 0.1 Mn 0.1 O2 (also known as NCM) 811 ), lithium nickel cobalt aluminum oxide (such as LiNi) 0.85 Co 0.15 Al 0.05 At least one of O2 and its modified compounds.

[0082] In some embodiments, the positive electrode can be a foamed metal. The foamed metal can be foamed nickel, foamed copper, foamed aluminum, foamed alloys, etc. When foamed metal is used as the positive electrode, the surface of the foamed metal may or may not contain a positive electrode active material. As an example, lithium source material, potassium metal, or sodium metal can also be filled and / or deposited within the foamed metal, where the lithium source material is lithium metal and / or a lithium-rich material.

[0083] In some embodiments, the negative electrode can be a negative electrode sheet, and the negative electrode sheet can include a negative current collector.

[0084] As an example, the negative electrode current collector can be a metal foil, a foamed metal, or a composite current collector. For example, as a metal foil, it can be aluminum with a silver-plated surface, stainless steel with a silver-plated surface, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel, or titanium, etc. Foamed metal can be nickel foam, copper foam, aluminum foam, foam alloy, etc. Composite current collectors can include a polymer material base layer and a metal layer. Composite current collectors can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0085] As an example, the negative electrode sheet may include a negative current collector and a negative active material disposed on at least one surface of the negative current collector.

[0086] As an example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode active material is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0087] As an example, the negative electrode active material may be a negative electrode active material known in the art for use in battery cells. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc. Silicon-based materials may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, this application is not limited to these materials, and other conventional materials that can be used as battery negative electrode active materials may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0088] In some embodiments, the positive current collector can be made of aluminum, and the negative current collector can be made of copper.

[0089] In some embodiments, the separator is a separator membrane. The separator membrane can be any known porous structure separator membrane with good chemical and mechanical stability.

[0090] As an example, the material of the separator may include at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multi-layer composite film. When the separator is a multi-layer composite film, the materials of each layer may be the same or different. The separator may be a separate component located between the positive and negative electrodes, or it may be attached to the surfaces of the positive and negative electrodes.

[0091] In some embodiments, the separator is a solid electrolyte. The solid electrolyte is disposed between the positive and negative electrodes, serving both to transport ions and to isolate the positive and negative electrodes.

[0092] In some embodiments, the battery cell also includes an electrolyte, which acts as a conductor of ions between the positive and negative electrodes. The electrolyte can be liquid, gel-like, or solid. Liquid electrolytes include electrolyte salts and solvents.

[0093] In some embodiments, the electrolyte salt may include at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium dioxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0094] In some embodiments, the solvent may include at least one selected from ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butyl carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone. The solvent may also be an ether solvent. Ether solvents may include one or more selected from ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyl tetrahydrofuran, diphenyl ether, and crown ethers.

[0095] Among them, the gel electrolyte includes a polymer as the electrolyte backbone network, combined with an ionic liquid - lithium salt.

[0096] Solid electrolytes include polymer solid electrolytes, inorganic solid electrolytes, and composite solid electrolytes.

[0097] As an example, polymer solid electrolytes can be polyethers (polyoxyethylene), polysiloxanes, polycarbonates, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, monoionic polymers, polyionic liquids-lithium salts, cellulose, etc.

[0098] As an example, inorganic solid electrolytes may include one or more of the following: oxide solid electrolytes (crystalline perovskite, sodium superconducting ion conductor, garnet, amorphous LiPON thin film), sulfide solid electrolytes (crystalline lithium superconducting ion conductor (lithium germanium phosphate sulfide, silver sulfide germanium ore), amorphous sulfides), halide solid electrolytes, nitride solid electrolytes, and hydride solid electrolytes.

[0099] As an example, composite solid electrolytes are formed by adding inorganic solid electrolyte fillers to polymer solid electrolytes.

[0100] In some embodiments, the electrode assembly is a wound structure. The positive electrode and the negative electrode are wound into a wound structure.

[0101] In some implementations, the electrode assembly is a stacked structure.

[0102] As an example, multiple positive and negative electrode plates can be set, and multiple positive and multiple negative electrode plates can be stacked alternately.

[0103] As an example, multiple positive electrode sheets can be set, and negative electrode sheets are folded to form multiple stacked folded segments, with a positive electrode sheet sandwiched between adjacent folded segments.

[0104] As an example, both the positive and negative electrode sheets are folded to form multiple stacked folded segments.

[0105] As an example, multiple separators can be provided, each positioned between any adjacent positive or negative electrode plates.

[0106] As an example, the separator can be continuously arranged between any adjacent positive or negative electrode plates by folding or rolling.

[0107] In some embodiments, the electrode assembly can be cylindrical, flat, or polygonal, etc.

[0108] In some embodiments, the electrode assembly is provided with tabs that allow current to be drawn from the electrode assembly. The tabs include a positive tab and a negative tab.

[0109] In some embodiments, the battery cell may include a housing. The housing is used to encapsulate components such as electrode assemblies and electrolytes. The housing may be made of steel, aluminum, plastic (such as polypropylene), composite metal (such as copper-aluminum composite), or aluminum-plastic film, etc.

[0110] As an example, a battery cell can be a cylindrical battery cell, a prismatic battery cell, a pouch battery cell, or a battery cell of other shapes. Prismatic battery cells include prismatic battery cells, blade-shaped battery cells, and multi-prismatic battery cells, such as hexagonal prismatic battery cells.

[0111] The battery mentioned in the embodiments of this application refers to a single physical module comprising one or more battery cells to provide higher voltage and capacity.

[0112] In related technologies, a battery cell generally includes a casing and an electrode assembly. The casing may include a housing and an end cap. The housing has an opening. After the electrode assembly is installed inside the housing, the opening of the housing can be closed by the end cap to form a sealed space inside the housing to accommodate the electrode assembly.

[0113] The battery apparatus mentioned in the embodiments of this application may include one or more battery cell assemblies for providing voltage and capacity. A battery cell assembly may include multiple battery cells connected in series, parallel, or mixed connections via a busbar.

[0114] In some embodiments, a battery cell assembly is typically formed by arranging multiple battery cells; as an example, a battery cell assembly can be a battery module, which is formed by arranging and fixing multiple battery cells together to form a single module. As an example, a battery module can be formed by bundling multiple battery cells together with cable ties.

[0115] In some embodiments, the battery device may be a battery pack, which includes a housing and one or more individual battery cells housed within the housing.

[0116] As an example, the battery cell assembly can be a battery module, and the battery cell assembly can be housed in the housing by fixing the battery module in the housing.

[0117] As an example, battery cell assemblies can also be housed in a housing by directly fixing multiple battery cells to the housing.

[0118] In some embodiments, the housing may be part of the vehicle's chassis structure. For example, a portion of the housing may be at least a part of the vehicle's floor, or a portion of the housing may be at least a part of the vehicle's crossbeams and longitudinal beams.

[0119] In some embodiments, the battery can be an energy storage device. Energy storage devices include energy storage containers, energy storage cabinets, etc.

[0120] The following discussion will primarily focus on rectangular battery cells. It should be understood that the embodiments described below are also applicable in some respects to cylindrical battery cells, pouch cell cells, or blade cell cells.

[0121] The development of battery technology must take into account multiple design factors, such as energy density, cycle life, discharge capacity, charge / discharge rate and other performance parameters. In addition, the reliability of the battery device also needs to be considered.

[0122] A typical battery cell includes a casing, electrode assembly, adapter, and electrode terminals. The electrode assembly is housed within the casing, and the electrode terminals are located on the casing wall. The tabs of the electrode assembly are electrically connected to the adapter, and the adapter is electrically connected to the electrode terminals, allowing the electrical energy from the electrode assembly to be drawn out through the adapter. A fusible link is typically provided on the adapter. This fusible link has a small overcurrent cross-sectional area, generating significant heat during short-circuit current flow to melt and break the circuit. To reduce energy loss through the adapter, the tabs are sometimes directly connected to the electrode terminals. In this case, without the adapter, the battery cell lacks a fusible link, resulting in lower reliability.

[0123] In view of this, this application provides a battery cell, which includes a casing, a first electrode terminal, and an electrode assembly. The first electrode terminal is disposed on the wall of the casing. The electrode assembly is disposed inside the casing and includes a first electrode plate, which includes an electrode plate body and a first electrode tab. The first electrode tab is disposed on one side of the electrode plate body in a first direction and includes a first portion and a second portion. The first portion is welded to the first electrode terminal to form a first solder mark, and the second portion connects the first portion and the electrode plate body. Along a second direction, the size of the second portion is larger than the size of the first portion, and the second portion protrudes outward from at least one side of the first portion. The second direction and the first direction are perpendicular to the thickness direction of the electrode plate body. When the battery cell is short-circuited externally, the short-circuit current flows from the second portion to the first portion. Due to the abrupt change in the cross-sectional area between the first and second portions, a large amount of heat is generated, causing the first electrode tab to melt in time, thereby reducing the risk of thermal runaway caused by the battery cell failing to disconnect the circuit in time. The above-mentioned battery cell has high reliability.

[0124] The technical solutions described in the embodiments of this application are applicable to battery cells, battery devices, and electrical devices using battery devices.

[0125] Electrical devices include, but are not limited to: electric vehicles, electric cars, ships, and spacecraft, etc. For example, spacecraft include airplanes, rockets, space shuttles, and spacecraft.

[0126] For ease of explanation, the following embodiments will be described using a vehicle as an example of an electrical device according to an embodiment of this application.

[0127] For example, Figure 1 is a structural schematic diagram of a vehicle 1000 according to some embodiments of this application. The vehicle 1000 can be a fuel-powered vehicle, a natural gas-powered vehicle, or a new energy vehicle. New energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. The vehicle 1000 may have a motor 300, a controller 200, and a battery device 100 installed inside. The controller 200 controls the battery device 100 to supply power to the motor 300. For example, the battery device 100 can be installed at the bottom, front, or rear of the vehicle 1000. The battery device 100 can be used to power the vehicle 1000. For example, the battery device 100 can serve as the operating power source for the vehicle 1000's electrical system, such as meeting the power requirements for starting, navigation, and operation of the vehicle 1000. In another embodiment of this application, the battery device 100 can not only serve as the operating power source for the vehicle 1000 but also as the driving power source, replacing or partially replacing fuel or natural gas to provide driving power to the vehicle 1000.

[0128] To meet different power demands, the battery device 100 may include multiple battery cells 12, which can be connected in series, parallel, or a combination thereof. The battery device 100 may also be referred to as a battery pack. Optionally, the multiple battery cells 12 can first be connected in series, parallel, or a combination thereof to form a battery cell assembly, and then the battery cell assemblies can be connected in series, parallel, or a combination thereof to form the battery device 100. In other words, the multiple battery cells 12 can directly form the battery device 100, or they can first be assembled into battery cell assemblies, and then the battery cell assemblies can be assembled into the battery device 100.

[0129] For example, please refer to Figure 2, which is an exploded view of a battery device 100 according to some embodiments of this application. The battery device 100 may include a plurality of battery cells 12. The battery device 100 may also include a housing 11, which has a hollow internal structure, and the plurality of battery cells 12 are housed within the housing 11. As shown in the figure, these are referred to here as a first housing 111 and a second housing 112, which are fastened together. The shapes of the first housing 111 and the second housing 112 can be determined according to the shape of the combination of the plurality of battery cells 12. Both the first housing 111 and the second housing 112 may have an open surface. For example, both the first housing 111 and the second housing 112 may be hollow cuboids with only one open surface each. The open surfaces of the first housing 111 and the second housing 112 are arranged opposite to each other, and the first housing 111 and the second housing 112 are fastened together to form a housing 11 with a closed cavity. Multiple battery cells 12 are connected in parallel, series, or mixed and placed inside the housing 11 formed by the first housing 111 and the second housing 112 being fastened together.

[0130] Optionally, the battery device 100 may also include other structures, which will not be described in detail here. For example, the battery device 100 may also include a busbar component for realizing electrical connection between multiple battery cells 12, such as in parallel, series, or mixed connection. Specifically, the busbar component can realize electrical connection between battery cells 12 by connecting the electrode terminals of the battery cells 12. Further, the busbar component can be fixed to the electrode terminals of the battery cells 12 by welding. The electrical energy of the multiple battery cells 12 can be further led out through the housing 11 via a conductive mechanism.

[0131] The number of battery cells 12 can be set to any value depending on different power requirements. Multiple battery cells 12 can be connected in series, parallel, or mixed connection to achieve a larger capacity or power. Since each battery device 100 may include a large number of battery cells 12, for ease of installation, the battery cells 12 can be grouped, with each group of battery cells 12 forming a battery cell assembly. The number of battery cells 12 included in a battery cell assembly is unlimited and can be set according to requirements. The battery device 100 may include multiple battery cell assemblies, which can be connected in series, parallel, or mixed connection.

[0132] Please refer to Figure 3, which is an exploded view of a battery cell 12 according to some embodiments of this application. The battery cell 12 includes one or more electrode assemblies 122 and a housing 121. The housing 121 may include a shell 1212, and multiple walls of the shell 1212 form a cavity that can be used to accommodate the electrode assemblies 122. The shape of the shell 1212 depends on the combined shape of the one or more electrode assemblies 122. For example, the shell 1212 may be a hollow cuboid, cube, or regular polyhedron, and one face of the shell 1212 has an opening so that one or more electrode assemblies 122 can be placed inside the shell 1212. The shell 1212 is filled with an electrolyte, such as an electrolyte solution.

[0133] The battery cell 12 may also include two electrode terminals, which can be disposed on an end cap 1211. The end cap 1211 is typically flat, and the two electrode terminals are fixed to the flat surface of the end cap 1211, which are respectively a positive electrode terminal and a negative electrode terminal. In this battery cell 12, depending on actual usage requirements, the electrode assembly 122 may be single or multiple, and multiple independent electrode assemblies 122 may be disposed within the battery cell 12.

[0134] According to some embodiments of this application, referring to Figures 4-6, the battery cell 12 includes a housing 121, a first electrode terminal 123, and an electrode assembly 122. The first electrode terminal 123 is disposed on the wall of the housing 121. The electrode assembly 122 is disposed within the housing 121 and includes a first electrode plate 1223. The first electrode plate 1223 includes an electrode plate body 1224 and a first electrode tab 1225. The first electrode tab 1225 is disposed on one side of the electrode plate body 1224 in a first direction Y. The first electrode tab 1225 includes a first portion 1226 and a second portion 1227. The first portion 1226 is welded to the first electrode terminal 123 to form a first solder mark 125. The second portion 1227 connects the first portion 1226 and the electrode plate body 1224. Along the second direction X, the size of the second portion 1227 is larger than the size of the first portion 1226, and the second portion 1227 protrudes outward from at least one side of the first portion 1226. The second direction X and the first direction Y are perpendicular to the thickness direction Z of the electrode body.

[0135] The first direction Y is the direction in which the first tab 1225 extends out of the electrode body 1224. For example, when the first tab 1225 is disposed on one side of the length direction of the electrode body 1224, the length direction of the electrode body 1224 is the first direction Y. For example, when the first tab 1225 is disposed on one side of the width direction of the electrode body 1224, the width direction of the electrode body 1224 is the first direction Y.

[0136] The first electrode terminal 123 can be either a positive terminal or a negative terminal.

[0137] In some embodiments, the battery cell 12 further includes a second electrode terminal 124, wherein the first electrode terminal 123 and the second electrode terminal 124 have opposite polarities.

[0138] In some embodiments, the first electrode terminal 123 serves as one output terminal of the battery cell 12, and the housing 121 serves as the other output terminal of the battery cell 12.

[0139] In some embodiments, the first portion 1226 and the first electrode terminal 123 can be laser-welded to form a first solder mark 125. This allows for higher processing efficiency in the battery cell 12.

[0140] The first portion 1226 of the first tab 1225 is directly connected to the first electrode terminal 123, which helps to reduce power loss during power transmission. Compared with the embodiment in which the first tab 1225 is connected to the adapter, and the adapter is then connected to the first electrode terminal 123, the power loss when the power flows through the adapter is reduced.

[0141] In some embodiments, the first electrode 1223 includes a current collector and an active material layer, the electrode body 1224 is the portion of the current collector coated with the active material layer, and the first tab 1225 is the portion of the current collector not coated with the active material layer.

[0142] In some embodiments, the first tab 1225 is made of aluminum. It should be noted that the aluminum tab can be a positive tab or a negative tab. For example, in a lithium-ion battery, the first tab 1225 is a positive tab; in a sodium-ion battery, the first tab 1225 can be a positive tab or a negative tab.

[0143] In some embodiments, along the second direction X, the size of the second portion 1227 is larger than the size of the first portion 1226, the second portion 1227 protrudes outward from one side of the first portion 1226, and along the second direction X, one side of the first tab 1225 is stepped, for example, when it is in a two-step shape, the first tab 1225 is L-shaped.

[0144] Along the second direction X, the size of the second portion 1227 is larger than the size of the first portion 1226, and the second portion 1227 protrudes outward from at least one side of the first portion 1226. This means that from the second portion 1227 to the first portion 1226, the cross-sectional area of ​​the first tab 1225 undergoes an abrupt change, that is, the cross-sectional area of ​​the current flow suddenly decreases.

[0145] In some embodiments, the first tab 1225 has a first intersection line (which can be a virtual intersection line rather than a physical edge) connecting to the electrode body 1224 and a top edge 1234 located away from the electrode body 1224. Along the first direction Y, from the first intersection line to the top edge 1234, the width of the first tab 1225 gradually decreases. Of course, in other embodiments, along the first direction Y, from the first intersection line to the top edge 1234, the width of the second portion 1227 remains unchanged, and the width of the second portion 1227 is greater than the width of the first portion 1226, while the width of the first portion 1226 remains unchanged. The width of the second portion 1227 refers to the dimension along the second direction X of the second portion 1227, and the width of the first portion 1226 refers to the dimension along the second direction X of the first portion 1226.

[0146] In the technical solution of this application embodiment, when a short circuit occurs externally to the battery cell 12, the short-circuit current, during its flow from the second part 1227 to the first part 1226, generates a large amount of heat due to the abrupt change in the cross-sectional area between the first part 1226 and the second part 1227. This heat causes the first tab 1225 to melt in time, thereby reducing the risk of thermal runaway caused by the battery cell 12 failing to disconnect the circuit in time. The aforementioned battery cell 12 possesses high reliability.

[0147] According to some embodiments of this application, please refer to Figures 4-6. Along the second direction X, the second portion 1227 protrudes outward from both sides of the first portion 1226.

[0148] In some embodiments, along the second direction X, the size of the second portion 1227 is larger than the size of the first portion 1226, and the second portion 1227 protrudes outward from both sides of the first portion 1226. Along the second direction X, both sides of the first tab 1225 are stepped, for example, when it is in a two-step shape, the first tab 1225 is convex.

[0149] In the above scheme, the second part 1227 protrudes outward from both sides of the first part 1226 along the second direction X. This can further increase the degree of abrupt change in the cross-sectional area of ​​the first tab 1225, allowing the first tab 1225 to melt more quickly when there is an external short circuit in the battery cell 12, thereby further improving the reliability of the battery cell 12.

[0150] According to some embodiments of this application, referring to Figures 4-6 and Figure 13, the first portion 1226 has a first side 1228 in the second direction X, and the second portion 1227 has a second side 1229 in the second direction X, the second side 1229 protruding from the first side 1228; the first tab 1225 includes a third side 1230, the third side 1230 connecting the first side 1228 and the second side 1229. The electrode assembly 122 includes a plurality of first tabs 1225, the plurality of first tabs 1225 are stacked and welded to form a second solder mark 127; the third side 1230 and the first side 1228 intersect at a first intersection point 128, or, the extension line of the third side 1230 and the extension line of the first side 1228 intersect at the first intersection point 128; along the first direction Y, the minimum distance between the second solder mark 127 and the first intersection point 128 is L, satisfying: 0.5mm≤L≤8mm.

[0151] In some embodiments, the electrode body 1224 has a first edge 1231, and a first electrode tab 1225 is connected to the first edge 1231. A third side 1230 is parallel to the first edge 1231.

[0152] In some embodiments, the first portion 1226 further includes a top edge 1234, which is located at the end of the first tab 1225 away from the electrode body 1224. The top edge 1234 is connected to the first side edge 1228. Along the second direction X, a second side edge 1229 protrudes from the first side edge 1228, and a third side edge 1230 connects the first side edge 1228 and the second side edge 1229. Since the top edge 1234, the first side edge 1228, the third side edge 1230, and the second side edge 1229 are connected in sequence, the risk of warping or excessive deformation near the top edge 1234 is low during the rolling process of the first electrode 1223.

[0153] In some embodiments, the included angle between the first side 1228 and the third side 1230 can be an obtuse angle.

[0154] In some embodiments, the included angle between the second side 1229 and the third side 1230 can be an obtuse angle.

[0155] In some embodiments, the electrode body 1224 has a first edge 1231, and a first electrode tab 1225 is connected to the first edge 1231. A first side 1228 is perpendicular to the first edge 1231.

[0156] In some embodiments, the electrode body 1224 has a first edge 1231, and a first electrode tab 1225 is connected to the first edge 1231. A second side 1229 is perpendicular to the first edge 1231.

[0157] In some embodiments, the electrode body 1224 has a first edge 1231, and a first tab 1225 is connected to the first edge 1231. A second side 1229 has a third end and a fourth end; the third end is connected to the third side 1230, and the fourth end is connected to the first edge 1231. From the fourth end to the third end, the distance between the second side 1229 and the first edge 1231 gradually increases. This arrangement helps reduce the risk of wrinkling of the first tab 1225 during the rolling process of the first electrode 1223.

[0158] In some embodiments, the first portion 1226 further includes a top edge 1234, located at the end of the first tab 1225 away from the electrode body 1224. The electrode body 1224 has a first edge 1231, and the first tab 1225 is connected to the first edge 1231. The first side edge 1228 has a fifth end and a sixth end. The fifth end is connected to the top edge 1234, and the sixth end is connected to the third side edge 1230. From the sixth end to the fifth end, the distance between the first side edge 1228 and the first edge 1231 gradually increases. This arrangement helps to reduce the risk of wrinkling of the first tab 1225 during the rolling process of the first electrode 1223.

[0159] In some embodiments, the abrupt change in the current-carrying cross-sectional area of ​​the first tab 1225 can be achieved by designing the second side 1229 of the first tab 1225 to protrude from its first side 1228. This design and manufacturing process of the first tab 1225 is relatively simple. Furthermore, compared to methods such as opening holes inside the first tab 1225, the impact of manufacturing stress on the first tab 1225 is smaller, allowing the first tab 1225 to have high structural strength while ensuring timely melting in the event of an external short circuit in the battery cell 12.

[0160] In some embodiments, a plurality of first tabs 1225 are stacked and formed into a second weld mark 127 by ultrasonic welding. Since the tabs are relatively thin, welding multiple first tabs 1225 by ultrasonic welding can reduce the risk of excessive deformation of the first tabs 1225 during the welding process.

[0161] The minimum distance between the second solder mark 127 and the first intersection point 128 can be measured after flipping the electrode body 1224 to make the current collector of the first electrode 1223 into a flat plate shape (see Figures 5 and 6). In embodiments where the battery cell 12 includes multiple first electrodes 1223, the electrode body 1224 can be flipped (see Figure 12), cut along the first direction Y, and then the current collector of the first electrode 1223 can be made into a flat plate shape (see Figures 5 and 6) before measuring the minimum distance between the second solder mark 127 and the first intersection point 128. Of course, only a portion of the first electrode 1223 can be measured. The edge of the second solder mark 127 can be determined by equipment such as an electrode solder joint detection system.

[0162] The minimum distance between the second solder mark 127 and the first intersection point 128 can be any value between 0.5 mm and 8 mm, for example, any one of the following point values ​​or any range between two: 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm, 5.5 mm, 6 mm, 6.5 mm, 7 mm, 7.5 mm, 8 mm.

[0163] In the above scheme, when L ≥ 0.5 mm, the area of ​​the melting region of the first tab 1225 can be relatively large, so that the first tab 1225 can melt in time within the preset melting region, reducing the risk of the battery cell 12 catching fire due to the increased time of internal short circuit caused by the first tab 1225 failing to melt at the preset position. When L ≤ 8 mm, the proportion of the larger second part 1227 in the first tab 1225 can be higher, which is beneficial to improving the structural strength of the first tab 1225 and the structural stability of the battery cell 12. Therefore, when 0.5 mm ≤ L ≤ 8 mm, the battery cell 12 can achieve both high reliability and high structural stability.

[0164] According to some embodiments of this application, please refer to Figures 4-6 and Figure 13, 1mm≤L≤5mm.

[0165] The minimum distance between the second solder mark 127 and the first intersection point 128 can be any value between 1 mm and 5 mm, for example, any one of the following point values ​​or any range between two values: 1 mm, 1.2 mm, 1.4 mm, 1.6 mm, 1.8 mm, 2 mm, 2.2 mm, 2.4 mm, 2.6 mm, 2.8 mm, 3 mm, 3.2 mm, 3.4 mm, 3.6 mm, 3.8 mm, 4 mm, 4.2 mm, 4.4 mm, 4.6 mm, 4.8 mm, 5 mm.

[0166] In the above scheme, when L≥1mm, the area of ​​the melting region of the first tab 1225 can be further increased, so that the first tab 1225 can melt in time within the preset melting region, further reducing the risk of the battery cell 12 catching fire due to the increased time of internal short circuit caused by the first tab 1225 failing to melt at the preset position. When L≤5mm, the proportion of the larger second part 1227 in the first tab 1225 can be further increased, which is beneficial to further improving the structural strength of the first tab 1225 and further improving the structural stability of the battery cell 12. Therefore, when 1mm≤L≤5mm, the reliability of the battery cell 12 can be further improved while the structural stability of the battery cell 12 can be further improved.

[0167] According to some embodiments of this application, please refer to Figures 4-6, 12 and 13. The electrode body 1224 has a first edge 1231, and a first electrode tab 1225 is connected to the first edge 1231. The third side 1230 has a first end 12301 and a second end 12302. The first end 12301 is connected to the first side 1228, and the second end 12302 is connected to the second side 1229. From the second end 12302 to the first end 12301, the distance between the third side 1230 and the first edge 1231 gradually increases.

[0168] In some embodiments, the distance between the third side 1230 and the first edge 1231 can be measured after the electrode body 1224 is flipped to make the current collector of the first electrode 1223 into a flat plate shape (see Figures 5 and 6). In embodiments where the battery cell 12 includes multiple first electrodes 1223, the electrode body 1224 can be flipped (see Figure 12), cut along the first direction Y, and then the current collector of the first electrode 1223 into a flat plate shape (see Figures 5 and 6) can be measured.

[0169] In the above scheme, the distance between the third side 1230 and the first edge 1231 gradually increases from the second end 12302 to the first end 12301. The connection position between the third side 1230 and the second side 1229, and the connection position between the third side 1230 and the first side 1228, have a low risk of stress concentration, and the first tab 1225 has high structural strength.

[0170] According to some embodiments of this application, please refer to Figures 4-6, 12 and 13. The angle between the third side 1230 and the first edge 1231 is α, which satisfies: 0°<α≤80°.

[0171] In some embodiments, the angle between the third side 1230 and the first edge 1231 can be measured after the electrode body 1224 is flipped to make the current collector of the first electrode 1223 into a flat plate shape (see Figures 5 and 6). In embodiments where the battery cell 12 includes multiple first electrodes 1223, the electrode body 1224 can be flipped (see Figure 12), cut along the first direction Y, and then the current collector of the first electrode 1223 can be made into a flat plate shape (see Figures 5 and 6) before measuring the angle between the third side 1230 and the first edge 1231.

[0172] The angle between the third side 1230 and the first edge 1231 can be any value between 0° and 80°, for example, any point value or a range between any two of the following: 5°, 10°, 15°, 20°, 25°, 30°, 35°, 40°, 45°, 50°, 55°, 60°, 65°, 70°, 75°, 80°.

[0173] In the above scheme, when α > 0°, the third side 1230 is inclined relative to the first edge 1231, which facilitates a smooth transition between the first side 1228, the third side 1230, and the second side 1229, reducing the risk of stress concentration in the first tab 1225 and improving the structural strength of the first tab 1225. When α ≤ 80°, it facilitates a significant change in the cross-sectional area between the first part 1226 and the second part 1227, allowing the first tab 1225 to melt in time, thus ensuring high reliability of the battery cell 12. Therefore, when 0° < α ≤ 80°, both the first tab 1225 and the battery cell 12 can achieve high structural strength and high reliability.

[0174] According to some embodiments of this application, please refer to Figures 4-6, 10°≤α≤40°.

[0175] The angle between the third side 1230 and the first edge 1231 can be any value between 10° and 40°, for example, any one of the following values ​​or a range between any two: 10°, 12°, 14°, 16°, 18°, 20°, 22°, 24°, 26°, 28°, 30°, 32°, 34°, 36°, 38°, 40°.

[0176] In the above scheme, when α ≥ 10°, it helps to make the transition between the first side 1228, the third side 1230, and the second side 1229 smoother, further reducing the risk of stress concentration in the first tab 1225 and further improving the structural strength of the first tab 1225. When α ≤ 80°, it helps to make the change in the cross-sectional area between the first part 1226 and the second part 1227 more obvious, so that the first tab 1225 can melt in time, further improving the reliability of the battery cell 12. Therefore, when 10° ≤ α ≤ 40°, the structural strength of the first tab 1225 can be further improved while the reliability of the battery cell 12 can be further improved.

[0177] According to some embodiments of this application, please refer to Figures 4-6. The first electrode 1225 further includes a first rounded edge 1232 and a second rounded edge 1233. The first side 1228 and the third side 1230 are connected by the first rounded edge 1232, and the second side 1229 and the third side 1230 are connected by the second rounded edge 1233.

[0178] In some embodiments, the first side 1228, the second side 1229, and the third side 1230 may be formed by laser cutting, wire cutting, machining, stamping, or other methods.

[0179] In the above scheme, since the first side 1228 and the third side 1230 are connected by the first rounded corner 1232, and the second side 1229 and the third side 1230 are connected by the second rounded corner 1233, the transition between the first side 1228 and the third side 1230, as well as between the second side 1229 and the third side 1230, is smoother. This reduces the risk of stress concentration in the first tab 1225 and improves the structural strength of the first tab 1225.

[0180] According to some embodiments of this application, please refer to Figures 4-6. The first part 1226 further includes a top edge 1234 and a third rounded edge 1235. The top edge 1234 is located at the end of the first tab 1225 away from the electrode body 1224. The top edge 1234 and the first side edge 1228 are connected by the third rounded edge 1235.

[0181] In some embodiments, the electrode body 1224 has a first edge 1231, and a first electrode tab 1225 is connected to the first edge 1231. The top edge 1234 is parallel to the first edge 1231.

[0182] In the above scheme, since the top edge 1234 and the first side edge 1228 are connected by the third rounded corner edge 1235, the transition between the top edge 1234 and the first side edge 1228 is smoother, which can reduce the risk of stress concentration in the first electrode 1225 and improve the structural strength of the first electrode 1225.

[0183] According to some embodiments of this application, please refer to Figures 4-6. The battery cell 12 further includes a second electrode terminal 124, which is disposed on the wall of the housing 121. The electrode assembly 122 further includes a second electrode 1237, which has the opposite polarity to the first electrode 1223. The second electrode 1237 includes a second tab 1236, which is welded to the second electrode terminal 124 to form a third solder mark 126.

[0184] The first electrode terminal 123 and the second electrode terminal 124 can be disposed on the same wall portion of the housing 121, or on different wall portions of the housing 121. For example, the housing 121 includes a shell 1212 and an end cap 1211. The shell 1212 has an opening, and the end cap 1211 closes the opening. The first electrode terminal 123 and the second electrode terminal 124 are both disposed on the end cap 1211. As another example, the housing 121 includes a shell 1212 and two end caps 1211. The shell 1212 has two openings. One end cap 1211 closes one opening, and the other end cap 1211 closes the other opening. The first electrode terminal 123 and the second electrode terminal 124 are respectively disposed on the two end caps 1211.

[0185] The second tab 1236 and the second electrode terminal 124 can be laser welded to form a third weld mark 126. This allows for high processing efficiency in the cell 12.

[0186] In the above scheme, the second tab 1236 is directly connected to the second electrode terminal 124, which can further reduce the loss during the power transmission process.

[0187] According to some embodiments of this application, please refer to Figures 4-10. The resistivity of the first tab 1225 is lower than that of the second tab 1236. The minimum current-carrying cross-sectional area of ​​the first tab 1225 is S1, and the minimum current-carrying cross-sectional area of ​​the second tab 1236 is S2, satisfying: 60%≤S2 / S1≤100%.

[0188] The minimum flow cross-sectional area of ​​the first tab 1225 can be determined by cutting the first tab 1225 along its thickness direction. The cross-sectional area can be calculated based on its shape. For example, if the cross-sectional area is rectangular, the product of its length (the width of the first tab 1225, i.e., the dimension along the second direction X of the first tab 1225) and its width (the thickness of the first tab 1225) is its cross-sectional area. If the cross-sectional area is circular, the product of the square of its radius and π is its cross-sectional area. If the cross-sectional area is annular, the product of the difference between the square of its major diameter and the square of its minor diameter and π is its cross-sectional area. The minimum flow cross-sectional area can be determined by cutting the tab multiple times at different locations and taking the minimum value.

[0189] The minimum flow cross-sectional area of ​​the second tab 1236 can be determined by cutting the second tab 1236 along its thickness direction. The cross-sectional area can be calculated based on its shape. For example, if the cross-sectional area is rectangular, the product of its length (the width of the second tab 1236, i.e., the dimension along the second direction X of the second tab 1236) and its width (the thickness of the second tab 1236) is its cross-sectional area. If the cross-sectional area is circular, the product of the square of its radius and π is its cross-sectional area. If the cross-sectional area is annular, the product of the difference between the square of its major diameter and the square of its minor diameter and π is its cross-sectional area. The minimum flow cross-sectional area can be determined by cutting the tab multiple times at different locations and taking the minimum value.

[0190] The ratio of the minimum cross-sectional area of ​​the second electrode 1236 to the minimum cross-sectional area of ​​the first electrode 1225 can be any value between 60% and 100%, for example, any one of 60%, 70%, 80%, 90%, 100% or any range between the two.

[0191] The resistivity of the second tab 1236 is lower than that of the first tab 1225, meaning that the second tab 1236 has better current-carrying capacity than the first tab 1225. In other words, because the first tab 1225 has a region with a sudden change in current-carrying cross-sectional area, the fuse point can still be located at the first tab 1225 while allowing the second tab 1236 to have a larger current-carrying cross-section. This ensures that the battery cell 12 as a whole has a high current-carrying capacity while maintaining controllable fuse breaking.

[0192] In the above scheme, when S2 / S1 ≥ 60%, the second tab 1236 bundle can have a larger current-carrying cross-sectional area, giving it better current-carrying capacity, and thus giving the battery cell 12 as a whole better current-carrying capacity. When S2 / S1 ≤ 100%, in the event of an external short circuit in the battery cell 12, the fuse can be made to melt at the location of the abrupt change in the current-carrying cross-section in the first tab 1225, so that the battery cell 12 melts in time at a preset position, reducing the risk of thermal runaway caused by the battery cell 12 failing to cut off the circuit in time due to cross-melting. The above-mentioned battery cell 12 has high reliability. Therefore, when 60% ≤ S2 / S1 ≤ 100%, the battery cell 12 can achieve both good current-carrying capacity and high reliability.

[0193] According to some embodiments of this application, please refer to Figures 4-10, 65%≤S2 / S1≤90%.

[0194] The ratio of the minimum current-carrying cross-sectional area of ​​the second electrode 1236 to the minimum current-carrying cross-sectional area of ​​the first electrode 1225 can be any value between 65% and 90%, for example, any one of 65%, 70%, 75%, 80%, 85%, 90%, or any range between the two.

[0195] In the above scheme, when S2 / S1≥65%, the current-carrying cross-sectional area of ​​the second tab 1236 bundle can be further increased, giving the second tab 1236 bundle better current-carrying capacity, thereby further improving the current-carrying capacity of the battery cell 12. When S2 / S1≤90%, in the event of an external short circuit in the battery cell 12, the risk of thermal runaway caused by the battery cell 12 failing to break the circuit in time due to the fuse not occurring at the preset fuse position can be further reduced. This further improves the reliability of the battery cell 12. Therefore, when 65%≤S2 / S1≤95%, while further improving the reliability of the battery cell 12, it also enables the battery cell 12 to have a higher current-carrying capacity.

[0196] According to some embodiments of this application, referring to Figures 4-10, the melting point of the first tab 1225 is lower than the melting point of the second tab 1236.

[0197] The melting point of the first tab 1225 is lower than that of the second tab 1236, which means that the first tab 1225 is more likely to melt than the second tab 1236 during the process of temperature increase.

[0198] In the above scheme, since the melting point of the first tab 1225 is lower than that of the second tab 1236, the first tab 1225 can melt faster than the second tab 1236, thereby further shortening the time for the battery cell 12 to melt and further improving the reliability of the battery cell 12.

[0199] According to some embodiments of this application, please refer to Figures 4-10. The first electrode 1225 is made of aluminum, and the second electrode 1236 is made of copper.

[0200] In some embodiments, the first tab 1225 is a positive tab made of aluminum, and the second tab 1236 is a negative tab made of copper.

[0201] According to some embodiments of this application, please refer to Figures 4-10. Along the second direction X, the maximum size of the first tab 1225 is W2, and the width of the first part 1226 is W1, satisfying: 20%≤W1 / W2≤65%.

[0202] In some embodiments, the maximum size of the first tab 1225 and the width of the first portion 1226 can be measured after the electrode body 1224 is flipped so that the current collector of the first electrode 1223 is in a flat plate shape (see Figures 5 and 6). In embodiments where the battery cell 12 includes multiple first electrodes 1223, the maximum size of the first tab 1225 and the width of the first portion 1226 can be measured after the electrode body 1224 is flipped (see Figure 12), the electrode body 1224 is cut along the first direction Y, and the current collector of the first electrode 1223 is made into a flat plate shape (see Figures 5 and 6).

[0203] The width of the first part 1226 is the dimension of the first part 1226 in the first direction Y.

[0204] Along the second direction X, the ratio of the width of the first portion 1226 to the maximum size of the first tab 1225 can be any value between 20% and 65%, for example, any one of 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65% or any range between two.

[0205] In the above scheme, when W1 / W2 ≥ 20%, the larger second part 1227 has a higher proportion in the first tab 1225, resulting in higher strength for the first tab 1225. When W1 / W2 ≤ 65%, the size difference between the first part 1226 and the second part 1227 is significant, leading to a larger abrupt change in the current-carrying cross-sectional area of ​​the first tab 1225. This allows the first tab 1225 to melt promptly, ensuring high reliability for the battery cell 12. Therefore, when 20% ≤ W1 / W2 ≤ 65%, both high reliability and high strength are achieved for the battery cell 12.

[0206] According to some embodiments of this application, please refer to Figures 4-10, 45%≤W1 / W2≤60%.

[0207] Along the second direction X, the ratio of the width of the first portion 1226 to the maximum size of the first tab 1225 can be any value between 45% and 65%, for example, any one of the following values ​​or a range between any two: 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%.

[0208] In the above scheme, when W1 / W2 ≥ 45%, the proportion of the larger second part 1227 in the first tab 1225 is further increased, which can further improve the strength of the first tab 1225. When W1 / W2 ≤ 60%, the size difference between the first part 1226 and the second part 1227 is further increased, the degree of abrupt change in the current-carrying cross-sectional area of ​​the first tab 1225 is further increased, the time required for the first tab 1225 to melt is further shortened, and the reliability of the battery cell 12 is further improved. Therefore, when 45% ≤ W1 / W2 ≤ 60%, the reliability of the battery cell 12 is further improved, and the strength of the first tab 1225 is also further improved.

[0209] According to some embodiments of this application, please refer to Figures 4-10. The electrode assembly 122 includes a plurality of first tabs 1225. The plurality of first tabs 1225 are stacked and welded to form a second solder mark 127. The first solder mark 125 is located within the second solder mark 127.

[0210] The first solder mark 125 is located within the second solder mark 127, which means that multiple first tabs 1225 can be pre-welded together as one piece, and then the multiple first tabs 1225 integrated together can be welded to the first electrode terminal 123. The multiple first tabs 1225 integrated together have a large thickness, and the risk of excessive deformation after welding to the first electrode terminal 123 is low.

[0211] In the above scheme, since multiple first tabs 1225 are stacked and welded to form a second solder mark 127, the difficulty of welding multiple first tabs 1225 to the first electrode terminal 123 can be reduced.

[0212] According to some embodiments of this application, referring to Figures 4-11, the second part 1227 includes a first sub-part and a second sub-part, which are arranged sequentially along a first direction Y. The first sub-part is closer to the first part 1226 than the second sub-part. Along the second direction X, the size of the second sub-part is larger than the size of the first sub-part, and the second sub-part protrudes outward from at least one side of the first sub-part. Along the second direction X, the size of the first sub-part is larger than the size of the first part 1226, and the first sub-part protrudes outward from at least one side of the first part 1226.

[0213] In some embodiments, the first electrode tab 1225 is multi-step, for example, the first electrode tab 1225 is three-step, the first sub-part can refer to the second step, and the second sub-part can refer to the third step. For example, the first electrode tab 1225 is four-step, the first sub-part can refer to the second and third steps, and the second sub-part can refer to the fourth step. For example, the first electrode tab 1225 is five-step, the first sub-part can refer to the second, third, and fourth steps, and the second sub-part can refer to the fifth step. The number of steps can be set as needed according to the size of the first electrode tab 1225 along the first direction Y.

[0214] In the above scheme, because the size of the second sub-part is larger than the size of the first sub-part along the second direction X, the second sub-part protrudes outward from at least one side of the first sub-part; and because the size of the first sub-part is larger than the size of the first portion 1226 along the second direction X, the first sub-part protrudes outward from at least one side of the first portion 1226. The width of the first tab 1225 gradually decreases, which can reduce the risk of wrinkling and tearing during the rolling process of the first tab 1225 due to excessive abrupt changes in size.

[0215] According to some embodiments of this application, please refer to Figures 4-13. The electrode assembly 122 has a wound structure. The first electrode 1223 includes a plurality of first tabs 1225, which are stacked.

[0216] In the above scheme, the wound electrode assembly 122 has higher processing efficiency.

[0217] According to some embodiments of this application, the electrode assembly 122 has a stacked structure, and the electrode assembly 122 includes a plurality of first electrode plates 1223, and the first electrode tabs 1225 of the plurality of first electrode plates 1223 are stacked.

[0218] In the above scheme, the stacked electrode assembly 122 has a high energy density.

[0219] According to some embodiments of this application, the battery cell 12 is a lithium-ion battery cell, and the first electrode 1223 is a positive electrode.

[0220] According to some embodiments of this application, the battery cell 12 is a sodium-ion battery cell, and the first electrode 1223 is a positive electrode or a negative electrode.

[0221] In some embodiments, both the positive and negative current collectors of the sodium-ion battery cell are made of aluminum.

[0222] According to some embodiments of this application, referring to FIG2, this application provides a battery device 100, which includes the battery cell 12 in one or more of the above embodiments.

[0223] In the above scheme, since the battery cell 12 in one or more of the above embodiments has high reliability, the battery device 100 including the battery cell 12 in one or more of the above embodiments also has high reliability.

[0224] According to some embodiments of this application, please refer to FIG1. ​​This application provides a battery device 100, which includes a battery cell 12 or a battery device 100 as described in one or more of the above embodiments, wherein the battery cell 12 or the battery device 100 is used to provide electrical energy.

[0225] In the above scheme, since the battery cell 12 or battery device 100 in one or more of the above embodiments has high reliability, the battery device 100 including the battery cell 12 or battery device 100 in one or more of the above embodiments also has high reliability.

[0226] According to some embodiments of this application, referring to Figures 4-13, this application provides a battery cell 12, which includes a housing 121, a first electrode terminal 123, a second electrode terminal 124, and an electrode assembly 122. The first electrode terminal 123 and the second electrode terminal 124 are disposed on the same wall of the housing 121. Electrode assembly 122 is disposed within housing 121. Electrode assembly 122 includes a first electrode 1223, which includes an electrode body 1224 and a first tab 1225. The first tab 1225 is disposed on one side of the electrode body in a first direction Y. Electrode assembly 122 also includes a second electrode 1237, which has the opposite polarity to the first electrode 1223. The second electrode 1237 includes a second tab 1236, which is disposed on one side of the electrode body in the first direction Y. The first tab 1225 includes a first portion 1226 and a second portion 1227. The first portion 1226 is welded to the first electrode terminal 123 to form a first solder mark 125. The second portion 1227 connects the first portion 1226 and the electrode body 1224. The second tab 1236 is welded to the second electrode terminal 124 to form a third solder mark 126. The first tab 1225 is made of aluminum, and the second tab 1236 is made of copper. The electrode assembly 122 includes multiple first tabs 1225 and multiple second tabs 1236. The multiple first tabs 1225 are stacked and welded to form a second solder mark 127, with the first solder mark 125 located within the second solder mark 127. The multiple second tabs 1236 are stacked and welded to form a fourth solder mark, with a third solder mark 126 located within the fourth solder mark.

[0227] Along the second direction X, the second portion 1227 is larger than the first portion 1226, and the second portion 1227 protrudes outward from both sides of the first portion 1226. The first portion 1226 has a first side 1228 in the second direction X, and the second portion 1227 has a second side 1229 in the second direction X, with the second side 1229 protruding from the first side 1228. The first tab 1225 includes a third side 1230, which connects the first side 1228 and the second side 1229.

[0228] The electrode body 1224 has a first edge 1231, and a first electrode tab 1225 is connected to the first edge 1231. The third side 1230 has a first end 12301 and a second end 12302. The first end 12301 is connected to the first side 1228, and the second end 12302 is connected to the second side 1229. From the second end 12302 to the first end 12301, the distance between the third side 1230 and the first edge 1231 gradually increases. The first electrode tab 1225 also includes a first rounded edge 1232 and a second rounded edge 1233. The first side 1228 and the third side 1230 are connected by the first rounded edge 1232, and the second side 1229 and the third side 1230 are connected by the second rounded edge 1233. The first part 1226 also includes a top edge 1234 and a third rounded edge 1235. The top edge 1234 is located at the end of the first electrode tab 1225 away from the electrode body 1224. The top edge 1234 and the first side edge 1228 are connected by the third rounded edge 1235.

[0229] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered within the scope of the claims and specification of this application. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A battery cell, characterized in that, include: shell; The first electrode terminal is disposed on the wall of the housing; An electrode assembly is disposed within the housing. The electrode assembly includes a first electrode plate, which includes an electrode plate body and a first electrode tab. The first electrode tab is disposed on one side of the electrode plate body in a first direction. The first electrode tab includes a first part and a second part. The first part is welded to the first electrode terminal to form a first solder mark, and the second part connects the first part and the electrode plate body. Wherein, along the second direction, the size of the second part is larger than the size of the first part, the second part protrudes outward from at least one side of the first part, and the second direction and the first direction are perpendicular to the thickness direction of the electrode body.

2. The battery cell according to claim 1, characterized in that, Along the second direction, the second portion protrudes outward from both sides of the first portion.

3. The battery cell according to claim 1 or 2, characterized in that, The first portion has a first side in the second direction, and the second portion has a second side in the second direction, the second side protruding from the first side; The first electrode includes a third side, which connects the first side and the second side; The electrode assembly includes multiple first tabs, which are stacked and welded together to form a second solder mark. The third side and the first side intersect at a first intersection point, or the extension line of the third side and the extension line of the first side intersect at a first intersection point; Along the first direction, the minimum distance between the second solder mark and the first intersection point is L, which satisfies: 0.5mm≤L≤8mm.

4. The battery cell according to claim 3, characterized in that, 1mm≤L≤5mm.

5. The battery cell according to claim 3 or 4, characterized in that, The electrode body has a first edge, and the first electrode tab is connected to the first edge; The third side has a first end and a second end, the first end being connected to the first side and the second end being connected to the second side. From the second end to the first end, the distance between the third side and the first edge gradually increases.

6. The battery cell according to claim 5, characterized in that, The angle between the third side and the first edge is α, which satisfies: 0°<α≤80°.

7. The battery cell according to claim 6, characterized in that, 10°≤α≤40°。 8. The battery cell according to any one of claims 3-6, characterized in that, The first electrode also includes a first rounded edge and a second rounded edge, the first side and the third side are connected by the first rounded edge, and the second side and the third side are connected by the second rounded edge.

9. The battery cell according to claim 8, characterized in that, The first part also includes a top edge and a third rounded corner edge. The top edge is located at the end of the first electrode tab away from the electrode body, and the top edge and the first side edge are connected by the third rounded corner edge.

10. The battery cell according to any one of claims 1-9, characterized in that, The battery cell also includes a second electrode terminal, which is disposed on the wall of the housing; The electrode assembly further includes a second electrode plate, which has the opposite polarity to the first electrode plate. The second electrode plate includes a second tab, which is welded to the second electrode terminal to form a third solder mark.

11. The battery cell according to claim 10, characterized in that, The resistivity of the second electrode is lower than that of the first electrode; The minimum current-carrying cross-sectional area of ​​the first electrode is S1, and the minimum current-carrying cross-sectional area of ​​the second electrode is S2, satisfying: 60%≤S2 / S1≤100%.

12. The battery cell according to claim 11, characterized in that, 65%≤S2 / S1≤90%.

13. The battery cell according to any one of claims 10-12, characterized in that, The melting point of the first electrode is lower than that of the second electrode.

14. The battery cell according to claim 13, characterized in that, The first electrode is made of aluminum, and the second electrode is made of copper.

15. The battery cell according to any one of claims 1-14, characterized in that, Along the second direction, the maximum size of the first electrode tab is W2, and the width of the first portion is W1, satisfying the following: 20%≤W1 / W2≤65%.

16. The battery cell according to claim 15, characterized in that, 45%≤W1 / W2≤60%.

17. The battery cell according to any one of claims 1-16, characterized in that, The electrode assembly includes a plurality of first tabs, which are stacked and welded together to form a second solder mark, wherein the first solder mark is located within the second solder mark.

18. The battery cell according to any one of claims 1-17, characterized in that, The second part includes a first sub-part and a second sub-part, the first sub-part and the second sub-part are arranged sequentially along the first direction, and the first sub-part is closer to the first part than the second sub-part; Along the second direction, the size of the second sub-part is larger than the size of the first sub-part, and the second sub-part protrudes outward from at least one side of the first sub-part; Along the second direction, the size of the first sub-part is larger than the size of the first part, and the first sub-part protrudes outward from at least one side of the first part.

19. The battery cell according to any one of claims 1-18, characterized in that, The electrode assembly has a wound structure, and the first electrode includes multiple first electrode tabs, which are stacked together.

20. The battery cell according to any one of claims 1-18, characterized in that, The electrode assembly has a stacked structure, and the electrode assembly includes a plurality of first electrodes, with the first tabs of the plurality of first electrodes stacked together.

21. The battery cell according to any one of claims 1-20, characterized in that, The battery cell is a lithium-ion battery cell, and the first electrode is a positive electrode.

22. The battery cell according to any one of claims 1-20, characterized in that, The battery cell is a sodium-ion battery cell, and the first electrode is either a positive electrode or a negative electrode.

23. A battery device, characterized in that, Includes the battery cell as described in any one of claims 1-22.

24. An electrical appliance, characterized in that, Includes a battery cell as described in any one of claims 1-22 or a battery device as described in claim 23, wherein the battery cell or the battery device is used to provide electrical energy.

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