Battery cells and electrical equipment

Abstract

The present application provides a battery cell and an electrical device, wherein the battery cell comprises an electrode assembly, wherein the electrode assembly comprises a first pole piece and a corrosion-resistant layer; the first pole piece comprises a first current collector, a first pole ear and a first active material layer, wherein the first pole ear is connected to one end of the first current collector along a width direction of the first current collector, the first current collector has two opposite first surfaces, the first pole ear has two opposite second surfaces, at least one first surface is provided with a first active material layer, and at least one second surface is provided with a corrosion-resistant layer; an area of ​​a second surface is S, an area of ​​a second surface covered by the corrosion-resistant layer is S1, 0.8≤S1 / S≤1, and the corrosion-resistant layer can reduce the risk of the first pole ear being corroded by the electrolyte in the thickness direction of the first current collector and causing the first pole ear to break, thereby improving the safety performance and reliability of the battery cell, extending the service life of the battery cell, and facilitating improving the energy density of the battery cell.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a battery cell and an electrical device. Background Art

[0002] At present, with the rapid development of new energy technology, battery cells have been widely used in electronic equipment, electric vehicles, electric two-wheeled vehicles, power tools and other fields. As the application of battery cells becomes more and more extensive, higher requirements are placed on the safety performance of battery cells. Summary of the invention

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

[0004] In a first aspect, an embodiment of the present application provides a battery cell, comprising an electrode assembly, the electrode assembly comprising a first pole piece and a corrosion-resistant layer; the first pole piece comprises a first current collector, a first pole ear and a first active material layer, along the width direction of the first current collector, the first pole ear is connected to one end of the first current collector, along the thickness direction of the first current collector, the first current collector has two opposite first surfaces, the first pole ear has two opposite second surfaces, at least one first surface is provided with a first active material layer, and at least one second surface is provided with a corrosion-resistant layer; wherein the area of ​​a second surface is S, the area of ​​a second surface covered by the corrosion-resistant layer is S1, and 0.8≤S1 / S≤1.

[0005] In one or more optional embodiments above, by providing a corrosion-resistant layer on at least one second surface of the first pole ear, the risk of the first pole ear being corroded by the electrolyte in the thickness direction of the first current collector and causing the first pole ear to break can be reduced, thereby reducing the risk of the first pole ear being inverted and contacting the second pole piece (the pole piece with the opposite polarity to the first pole piece) under the falling condition and causing a short circuit, thereby improving the safety performance and reliability of the battery cell and extending the service life of the battery cell. By making the ratio of the area S1 of the second surface covered by the corrosion-resistant layer to the area S of a second surface greater than or equal to 0.8, the area covered by the corrosion-resistant layer on the second surface is large enough to reduce the risk of the first pole ear being corroded by the electrolyte, and reducing the risk of the first pole ear being short-circuited due to corrosion and inversion under the falling condition, thereby improving the safety performance and reliability of the battery cell and extending the service life of the battery cell. By making the ratio of the area S1 of the second surface covered by the corrosion-resistant layer to the area S of a second surface less than or equal to 1, the space occupied by the corrosion-resistant layer is reduced, which is conducive to improving the energy density of the battery cell. Therefore, 0.8≤S1 / S≤1 is beneficial to improving the safety performance and energy density of the battery cell.

[0006] In some embodiments of the first aspect of the present application, along the width direction of the first current collector, the corrosion-resistant layer includes a first part and a second part, the first part is closer to the first active material layer than the second part, and the thickness of the first part is greater than the thickness of the second part.

[0007] In one or more of the above optional embodiments, the thickness of the first part of the corrosion-resistant layer close to the first active material layer is greater than the thickness of the second part away from the first active material layer, so that the thickness of the corrosion-resistant layer tends to decrease from the end close to the first active material layer to the end away from the first active material layer, and the stiffness of the corrosion-resistant layer tends to decrease from the end close to the first active material layer to the end away from the first active material layer, which is beneficial to the formation of an arc at the corresponding position of the corrosion-resistant layer when the first pole ear is bent, reducing the risk of cracking of the first pole ear due to the formation of dead folds when the first pole ear is bent, thereby alleviating the problem of damage to the first pole ear during the bending process of the first pole ear, reducing the problem of short circuit of the battery cell due to damage to the first pole ear, and improving the safety performance of the battery cell.

[0008] In some embodiments of the first aspect of the present application, the first portion includes an insulating material; and / or the second portion includes an insulating material.

[0009] In one or more of the above optional embodiments, the first part and / or the second part includes an insulating material, which is beneficial to reducing the risk of short circuit of the battery cell and improving the safety performance of the battery cell.

[0010] In some embodiments of the first aspect of the present application, the material of the first part includes ceramic.

[0011] In one or more of the above optional embodiments, ceramics have good wear resistance and corrosion resistance. The material of the first part includes ceramics, which reduces the risk of corrosion of the first pole ear, improves the safety performance of the battery cell and extends the service life of the battery cell.

[0012] In some embodiments of the first aspect of the present application, the material of the second part includes one or more of ceramics, molecular sieves, aluminum fluoride, high molecular polymers, and graphene.

[0013] In one or more optional embodiments above, ceramics have good wear resistance and corrosion resistance, and the material of the second part includes ceramics, which reduces the risk of corrosion of the first pole ear, thereby reducing the risk of short circuit of the first pole ear due to corrosion and inversion under falling conditions, improving the safety performance and reliability of the battery cell, and extending the service life of the battery cell. Molecular sieves have good adsorption properties, and the material of the first part includes molecular sieves, which can reduce the risk of electrolyte contacting the first pole ear or reduce the amount of electrolyte contacting the first pole ear, thereby reducing the risk of corrosion of the first pole ear or alleviating the degree of corrosion of the first pole ear, improving the safety performance of the battery cell and extending the service life of the battery cell. Aluminum fluoride has good chemical stability and corrosion resistance, and the material of the second part includes aluminum fluoride, which is conducive to reducing the risk of corrosion of the first pole ear, improving the safety performance of the battery cell and extending the service life of the battery cell. The chemical structure of graphene makes graphene have a good barrier effect, and the material of the first part includes molecular sieves, which can reduce the risk of electrolyte contact or reduce the amount of electrolyte contact, improve the safety performance of the battery cell and extend the service life of the battery cell.

[0014] In some embodiments of the first aspect of the present application, the material of the second part includes molecular sieve, and the pore size of the molecular sieve is less than or equal to 0.3 nm.

[0015] In one or more of the above optional embodiments, the material of the second part includes molecular sieves, and the pore size of the molecular sieve is less than or equal to 0.3 nm, so that the second part has better adsorption properties, can reduce the risk of electrolyte contacting the first pole ear or reduce the amount of electrolyte contact with the first pole ear, thereby reducing the risk of corrosion of the first pole ear or alleviating the degree of corrosion of the first pole ear, improving the safety performance of the battery cell and extending the service life of the battery cell.

[0016] In some embodiments of the first aspect of the present application, the material of the first part and the material of the second part are different; or, the material of the first part and the material of the second part are the same.

[0017] In one or more of the above optional embodiments, the material of the first part is different from the material of the second part, which facilitates the selection of materials with better performance for the first part and the second part, thereby improving the overall performance of the corrosion-resistant layer, thereby reducing the risk of the first pole ear being corroded by the electrolyte, improving the safety performance of the battery cell and extending the service life of the battery cell. The material of the first part is the same as the material of the second part, which facilitates the setting of the corrosion-resistant layer.

[0018] In some embodiments of the first aspect of the present application, the thickness of the second portion is h, 1nm≤h≤5μm, preferably, 30nm≤h≤2μm.

[0019] In one or more optional embodiments above, the thickness of the second part is greater than or equal to 1nm, so that the thickness of the second part is larger, so that the strength and corrosion resistance of the second part are better, thereby improving the strength of the first pole ear and reducing the risk of corrosion of the second pole ear, and improving the safety performance of the battery. The thickness of the second part is less than or equal to 5μm, which can reduce the space occupied by the corrosion-resistant layer, alleviate the problem of reduced energy density of the battery cell due to the setting of the corrosion-resistant layer, and enable the battery cell to have a higher energy density. Therefore, 1nm≤h≤5μm is conducive to improving the safety performance of the battery cell and enabling the battery cell to have a higher energy density. By making the thickness of the second part greater than or equal to 30nm, the thickness of the second part is greater, so that the strength and corrosion resistance of the second part are better, thereby further improving the strength of the first pole ear and further reducing the risk of corrosion of the second pole ear, and further improving the safety performance of the battery cell. The thickness of the second part is less than or equal to 2μm, which can further reduce the space occupied by the corrosion-resistant layer, further alleviate the problem of reduced energy density of the battery cell due to the setting of the corrosion-resistant layer, and enable the battery cell to have a higher energy density. Therefore, 30nm≤h≤2μm is conducive to further improving the safety performance of the battery cell and making the battery cell have a higher energy density.

[0020] In some embodiments of the first aspect of the present application, along the width direction of the first current collector, one end of the first part facing away from the second part is connected to the first active material layer, the other end of the first part is connected to the second part, and one end of the second part facing away from the first part extends to the edge of the first electrode ear facing away from the first active material layer.

[0021] In one or more of the above optional embodiments, the first part is connected to the first active material layer at one end away from the second part, the other end of the first part is connected to the second part, and the end of the second part away from the first part extends to the edge of the first pole ear away from the first active material layer, so that the corrosion-resistant layer covers a larger area of ​​the surface of the first pole ear, further reducing the risk of corrosion of the first pole ear and improving the safety performance of the battery cell.

[0022] In some embodiments of the first aspect of the present application, the first surface includes a first area covered by a first active material layer and a second area not covered by the first active material layer, the first area, the second area and the first electrode ear are arranged in sequence and connected along the width direction of the first current collector, at least part of the second area is provided with an insulating layer, and along the width direction of the first current collector, the insulating layer is located between the corrosion-resistant layer and the first active material layer, and the material of the insulating layer includes ceramic and / or high molecular polymer.

[0023] In one or more of the above optional embodiments, at least part of the second region is provided with an insulating layer, and along the width direction of the first current collector, the insulating layer is located between the corrosion-resistant layer and the first active material layer, thereby reducing the risk of short circuit of the battery cell and improving the safety performance of the battery cell. The material of the insulating layer includes ceramic and / or high molecular polymer with good insulation and corrosion resistance, which can reduce the risk of contact short circuit inside the battery cell and the risk of corrosion of the first pole ear, thereby improving the safety performance of the battery cell.

[0024] In some embodiments of the first aspect of the present application, a minimum thickness of the insulating layer is greater than a minimum thickness of the corrosion-resistant layer.

[0025] In one or more of the above optional embodiments, the minimum thickness of the insulating layer is greater than the maximum thickness of the corrosion-resistant layer. Then, from the insulating layer to the corrosion-resistant layer, the insulating layer and the corrosion-resistant layer tend to decrease in thickness as a whole. Then, from the insulating layer to the corrosion-resistant layer, the insulating layer and the corrosion-resistant layer tend to decrease in stiffness as a whole. This is beneficial for forming an arc at corresponding positions of the insulating layer and the corrosion-resistant layer when the first pole ear is bent, reducing the risk of cracking of the first pole ear due to the formation of dead folds when the first pole ear is bent, thereby alleviating the problem of damage to the first pole ear during the bending process of the first pole ear, reducing the problem of short circuit of the battery cell due to damage of the first pole ear, and improving the safety performance of the battery cell.

[0026] In some embodiments of the first aspect of the present application, along the length direction of the first current collector, the first electrode tab has two opposite third surfaces, and at least one of the third surfaces is provided with a corrosion-resistant layer.

[0027] In one or more of the above optional embodiments, at least one third surface is provided with a corrosion-resistant layer, which can reduce the risk of the first pole ear being corroded by the electrolyte in the length direction of the first current collector and causing the first pole ear to break, thereby reducing the risk of the first pole ear being broken and causing a short circuit due to being inverted and contacting the second pole piece (the pole piece with opposite polarity to the first pole piece) under a falling condition, thereby improving the safety performance of the battery cell.

[0028] In some embodiments of the first aspect of the present application, the first pole piece includes a plurality of first pole tabs, the plurality of first pole tabs are arranged at intervals along the length direction of the first current collector, and at least one second surface of at least one first pole tab is provided with a corrosion-resistant layer.

[0029] In one or more of the above optional embodiments, the first pole piece includes a plurality of first pole tabs spaced apart along the length direction of the first current collector, which is beneficial to improving the current carrying capacity and charge and discharge rate of the battery cell.

[0030] In some embodiments of the first aspect of the present application, the second surface includes a connection area not covered by the corrosion-resistant layer; the battery core also includes a first conductive member, and the first conductive member is electrically connected to the connection area.

[0031] In one or more of the above optional embodiments, the first conductive member is electrically connected in the connection area not covered by the corrosion-resistant layer, so as to facilitate the connection between the first conductive member and the first pole lug and improve the stability of the electrical connection between the first conductive member and the first pole lug.

[0032] In a second aspect, an embodiment of the present application provides an electrical device, and the electrical device includes a battery cell provided by any embodiment of the first aspect.

[0033] In one or more of the above optional embodiments, any embodiment of the first aspect provides a battery cell with good safety performance, which is beneficial to improving the power safety and power reliability of electrical equipment powered by the battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope.

[0035] Figure 1 A cross-sectional view of a battery cell provided in some embodiments of the present application;

[0036] Figure 2 A cross-sectional view of a battery cell provided in some other embodiments of the present application;

[0037] Figure 3 A schematic diagram of a first pole piece in an unfolded state provided in some embodiments of the present application;

[0038] Figure 4 It is a cross-sectional view along the A1-A1 direction;

[0039] Figure 5 Schematic diagram of a first pole piece in an unfolded state provided in some other embodiments of the present application;

[0040] Figure 6 for Figure 5 A2-A2 sectional view;

[0041] Figure 7 A schematic diagram of a first pole piece in an unfolded state provided in some further embodiments of the present application;

[0042] Figure 8 for Figure 7 A3-A3 sectional view;

[0043] Fig. 9 A schematic diagram of unfolding a first pole piece provided in some further embodiments of the present application;

[0044] Fig.10A schematic diagram of the connection between the connection area of ​​the first electrode tab and the first conductive member provided in some further embodiments of the present application;

[0045] Fig.11 for Fig.10 A4-A4 sectional view;

[0046] Fig.12 A schematic diagram of a first pole piece after unfolding provided in yet other embodiments of the present application;

[0047] Fig.13 A schematic diagram of a first pole piece after unfolding provided in some other embodiments of the present application;

[0048] Fig.14 A schematic diagram of the structure of the second pole piece after unfolding provided in some embodiments of the present application;

[0049] Fig.15 for Fig.14 A5-A5 section view.

[0050] Icon: 100-battery cell; 10-housing; 20-electrode assembly; 21-first pole piece; 211-first current collector; 2111-first surface; 21111-first region; 21112-second region; 2112-fourth surface; 212-first pole ear; 2121-second surface; 21211-connection region; 2122-third surface; 213-first active material layer; 22-second pole piece; 221-second current collector; 2211-fifth surface; 22 2-second pole ear; 2221-sixth surface; 223-second active material layer; 23-isolation film; 24-corrosion-resistant layer; 241-first part; 242-second part; 25-insulating layer; 30-first conductive member; 40-pole; X-thickness direction of the first current collector; Y-width direction of the first current collector; Z-length direction of the first current collector; X'-thickness direction of the second current collector; Y'-width direction of the second current collector; Z'-length direction of the second current collector. DETAILED DESCRIPTION

[0051] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0052] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application claimed for protection, but merely represents selected embodiments of the present application. It should be noted that the embodiments and features in the embodiments of the present application can be combined with each other without conflict.

[0053] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0054] In the description of the embodiments of the present application, it should be noted that the indicated orientation or positional relationship is based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of the application is usually placed when in use, or the orientation or positional relationship commonly understood by those skilled in the art, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0055] At present, judging from the development of the market situation, the application of battery cells is becoming more and more extensive. Battery cells are widely used in electric vehicles such as electric bicycles, electric motorcycles, electric vehicles, as well as electric tools, drones, energy storage equipment and other fields. With the continuous expansion of the application field of battery cells, the market demand is also constantly expanding, and the requirements for battery cell safety are becoming higher and higher.

[0056] The battery cell includes an electrode assembly, the electrode assembly includes a pole piece, the pole piece includes a substrate and an active material layer, the active material layer is provided on at least one side of the substrate along the thickness direction of the substrate, the substrate includes a current collector, a pole ear and an active material layer, the pole ear is connected to one end of the current collector along its width direction, the active material layer is provided on the current collector, the area of ​​the substrate not covered by the active material is exposed, and is easily corroded after contacting with the electrolyte, thereby reducing the mechanical strength of the pole piece, thereby causing the pole piece to break, and thus reducing the safety performance of the battery cell.

[0057] Based on the above considerations, in order to improve the safety performance of the battery cell, an embodiment of the present application provides a battery cell, which includes an electrode assembly, the electrode assembly includes a first pole piece and a corrosion-resistant layer; the first pole piece includes a first current collector, a first pole ear and a first active material layer, along the width direction of the first current collector, the first pole ear is connected to one end of the first current collector, along the thickness direction of the first current collector, the first current collector has two opposite first surfaces, the first pole ear has two opposite second surfaces, at least one first surface is provided with a first active material layer, and at least one second surface is provided with a corrosion-resistant layer; wherein the area of ​​a second surface is S, the area of ​​a second surface covered by the corrosion-resistant layer is S1, and 0.8≤S1 / S≤1.

[0058] By providing a corrosion-resistant layer on at least one second surface of the first pole ear, the risk of the first pole ear being corroded by the electrolyte in the thickness direction of the first current collector and causing the first pole ear to break can be reduced, thereby reducing the risk of the first pole ear being inverted and contacting the second pole piece (the pole piece with opposite polarity to the first pole piece) under a falling condition and causing a short circuit, thereby improving the safety performance and reliability of the battery cell and extending the service life of the battery cell.

[0059] By making the ratio of the area S1 of the second surface covered by the corrosion-resistant layer to the area S of the second surface greater than or equal to 0.8, the area of ​​the second surface covered by the corrosion-resistant layer is large enough to reduce the risk of the first pole ear being corroded by the electrolyte, and the risk of the first pole ear being short-circuited due to corrosion and inversion under falling conditions, thereby improving the safety performance and reliability of the battery cell and extending the service life of the battery cell. By making the ratio of the area S1 of the second surface covered by the corrosion-resistant layer to the area S of the second surface less than or equal to 1, the space occupied by the corrosion-resistant layer is reduced, which is beneficial to improving the energy density of the battery cell. Therefore, 0.8≤S1 / S≤1 is beneficial to improving the safety performance and energy density of the battery cell.

[0060] The battery cell disclosed in the embodiment of the present application can be used in, but not limited to, electric two-wheeled vehicles, electric tools, drones, energy storage devices and other electrical equipment. The battery cell with the working condition of the present application can also be used as a power supply system for electrical equipment, which is conducive to improving the safety performance of the battery cell.

[0061] The embodiment of the present application provides an electric device using a battery cell as a power source, and the electric device may be, but is not limited to, electronic equipment, electric tools, electric vehicles, drones, and energy storage devices. Among them, electronic equipment may include mobile phones, tablets, laptops, etc., electric tools may include electric drills, electric saws, etc., and electric vehicles may include electric cars, electric motorcycles, electric bicycles, etc.

[0062] like Figure 1 , Figure 2As shown, an embodiment of the present application provides a battery cell 100 , which includes a housing 10 and an electrode assembly 20 , wherein the electrode assembly 20 is accommodated in the housing 10 .

[0063] The housing 10 forms a storage space. The storage space can be used to store the electrode assembly 20, electrolyte, etc. Figure 1 As shown, the shell 10 can be formed of a relatively soft material, for example, the shell 10 is an aluminum plastic film or a steel plastic film to form a soft-pack battery cell. Figure 2 As shown, the shell 10 may also be a hard shell, for example, the shell 10 is a steel shell or an aluminum shell to form a steel shell battery core or an aluminum shell battery core.

[0064] The housing 10 may also contain electrolyte and the like.

[0065] The electrode assembly 20 includes a first electrode sheet 21, a second electrode sheet 22 and a separator 23. The first electrode sheet 21 and the second electrode sheet 22 have opposite polarities, that is, one of the first electrode sheet 21 and the second electrode sheet 22 is a positive electrode sheet and the other is a negative electrode sheet. The separator 23 insulates and separates the first electrode sheet 21 and the second electrode sheet 22 to reduce the risk of short circuit of the battery cell 100. The material of the separator 23 may include PP (polypropylene) or PE (polyethylene).

[0066] The electrode assembly 20 may be a wound structure, wherein the first pole piece 21, the separator 23, the second pole piece 22 and the other separator 23 are stacked in a certain order and then wound to form an electrode assembly of a wound structure; or, the separator 23, the first pole piece 21, the other separator 23 and the second pole piece 22 are stacked in a certain order and then wound to form an electrode assembly of a wound structure. The wound electrode assembly 20 may be a flat wound electrode assembly 20.

[0067] The electrode assembly 20 may also be a laminated structure, where the first electrode sheet 21 , the isolation membrane 23 , and the second electrode sheet 22 are stacked in a certain order to form a laminated electrode assembly.

[0068] like Figure 3-Figure 6 As shown, the first pole piece 21 includes a first current collector 211, a first pole tab 212 and a first active material layer 213. Along the width direction Y of the first current collector, the first pole tab 212 is connected to one end of the first current collector 211. The first pole tab 212 and the first current collector 211 can be integrally formed. The first pole tab 212 can be a full pole tab structure. The first pole tab 212 can also be a split pole tab structure formed by die-cutting a substrate. Figure 3 , Figure 4 FIG. 2 shows a case where the first electrode tab 212 is a full electrode tab. Figure 5 , Figure 62 shows the case where the first pole ear 212 is a split pole ear. In the embodiment where the first pole ear 212 is a split pole ear structure, the first pole ear 212 can be one. The first pole ear 212 can also be multiple, and the multiple first pole ears 212 are arranged at intervals along the length direction Z of the first current collector. The first pole sheet 21 includes multiple first pole ears 212 arranged at intervals along the length direction Z of the first current collector, which is beneficial to improving the current capacity and charge and discharge rate of the battery cell 100.

[0069] The width direction Y of the first current collector, the thickness direction X of the first current collector, and the length direction Z of the first current collector are perpendicular to each other.

[0070] Along the thickness direction X of the first current collector, the first current collector 211 has two opposite first surfaces 2111, and at least one of the first surfaces 2111 is provided with a first active material layer 213. Among them, only one of the two first surfaces 2111 of the first current collector 211 may be provided with the first active material layer 213, or both of the first surfaces 2111 of the first current collector 211 may be provided with the first active material layer 213. Figure 4 , Figure 6 2 shows a case where the first active material layer 213 is disposed on both first surfaces 2111 of the first current collector 211 .

[0071] like Figure 3-Figure 5 As shown, along the width direction Y of the first current collector, the first active material layer 213 may completely cover the first surface 2111 .

[0072] like Figure 7 , Figure 8 As shown, along the width direction Y of the first current collector, the first active material layer 213 may also only cover a portion of the first surface 2111. Figure 7 , Figure 8 As shown, the first surface 2111 includes a first region 21111 covered by the first active material layer 213 and a second region 21112 not covered by the first active material layer 213, the first region 21111, the second region 21112 and the first pole ear 212 are arranged and connected in sequence along the width direction Y of the first current collector, and the second region 21112 is located between the first region 21111 and the second pole ear 222.

[0073] Along the thickness direction X of the first current collector, the first electrode tab 212 has two opposite second surfaces 2121. One first surface 2111 and one second surface 2121 are coplanar and connected in the width direction Y of the first current collector.

[0074] If the first electrode sheet 21 is a positive electrode sheet, the first current collector 211 is a positive current collector, and the first active material layer 213 is a positive active material layer. For the lithium-ion battery cell 100, the material of the positive current collector can be aluminum. The positive active material layer can be lithium cobalt oxide, lithium iron phosphate, ternary lithium or lithium manganese oxide. The positive current collector can be a composite current collector or a non-composite current collector.

[0075] If the first electrode sheet 21 is a negative electrode sheet, the first current collector 211 is a negative current collector, and the first active material layer 213 is a negative active material layer. For the lithium-ion battery cell 100, the material of the negative current collector can be copper. The negative current collector can be a composite current collector or a non-composite current collector. The negative active material can be a carbon material or a silicon material.

[0076] In this embodiment, the first electrode plate 21 is a positive electrode plate.

[0077] The electrode assembly 20 further includes a corrosion-resistant layer 24 , and at least one second surface 2121 is provided with the corrosion-resistant layer 24 .

[0078] The corrosion-resistant layer 24 has strong corrosion resistance. The corrosion-resistant layer 24 can be a corrosion-resistant coating applied to the second surface 2121, or a film bonded to the second surface 2121. The material of the corrosion-resistant layer 24 includes but is not limited to aluminum fluoride (AlF3), molecular sieve, graphene, high molecular polymer, etc.

[0079] By providing the corrosion-resistant layer 24 on at least one second surface 2121 of the first pole tab 212, the risk of the first pole tab 212 being corroded by the electrolyte in the thickness direction X of the first current collector and causing the first pole tab 212 to break can be reduced, thereby reducing the risk of the first pole tab 212 being inverted and contacting the second pole piece 22 (the pole piece with the opposite polarity to the first pole piece 21) under the falling condition and causing a short circuit, thereby improving the safety performance and reliability of the battery cell 100 and extending the service life of the battery cell 100. In the embodiment where the first pole piece 21 is a positive pole piece, the corrosion-resistant layer 24 is provided on the second surface 2121 of the first pole tab 212, and the problem of low strength caused by the small thickness of the first pole tab 212 can also be compensated. Since the thickness of the first pole tab 212 of the positive pole piece is small, if the corrosion-resistant layer 24 is not provided, the first pole tab 212 is more severely corroded and more likely to break. Therefore, providing the corrosion-resistant layer on the surface of the pole tab of the positive pole sheet can effectively improve the problem of corrosion of the pole tab of the positive pole sheet.

[0080] The corrosion-resistant layer 24 can completely cover the second surface 2121, or can cover part of the second surface 2121. The area of ​​a second surface 2121 is S, and the area of ​​a second surface 2121 covered by the corrosion-resistant layer 24 is S1. If the corrosion-resistant layer 24 can completely cover the second surface 2121, then S1 / S=1, so that the second surface 2121 is completely covered by the corrosion-resistant layer 24, and the risk of the first pole ear 212 being corroded is lower.

[0081] If the corrosion-resistant layer 24 covers a portion of the second surface 2121 , S1 / S<1.

[0082] In some embodiments, 0.8≤S1 / S≤1.

[0083] Illustratively, S1 / S may be 0.8, 0.81, 0.82, 0.83, 0.84, 0.85, 0.86, 0.87, 0.88, 0.89, 0.9, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99, 1, etc.

[0084] By making the ratio of the area S1 of the second surface 2121 covered by the corrosion-resistant layer 24 to the area S of the second surface 2121 greater than or equal to 0.8, the area of ​​the second surface 2121 covered by the corrosion-resistant layer 24 is large enough, reducing the risk of the first pole ear 212 being corroded by the electrolyte, reducing the risk of the first pole ear 212 being short-circuited due to corrosion and inversion under the falling condition, improving the safety performance and reliability of the battery cell 100, and extending the service life of the battery cell 100. By making the ratio of the area S1 of the second surface 2121 covered by the corrosion-resistant layer 24 to the area S of the second surface 2121 less than or equal to 1, the space occupied by the corrosion-resistant layer 24 is reduced, which is beneficial to improving the energy density of the battery cell 100. Therefore, 0.8≤S1 / S≤1 is beneficial to improving the safety performance of the battery cell 100 and the energy density of the battery cell 100.

[0085] In an embodiment where the corrosion resistant layer 24 covers a portion of the second surface 2121, as Figure 9-11 As shown, the second surface 2121 includes a connection area 21211 that is not covered by the corrosion-resistant layer 24 ; the battery cell 100 also includes a first conductive member 30 , and the first conductive member 30 is electrically connected to the connection area 21211 .

[0086] The first conductive member 30 and the connection area 21211 can be electrically connected by welding, conductive adhesive, or the like.

[0087] By electrically connecting the first conductive member 30 at the connection area 21211 not covered by the corrosion-resistant layer 24 , the first conductive member 30 and the first pole tab 212 are connected conveniently, and the stability of the electrical connection between the first conductive member 30 and the first pole tab 212 is improved.

[0088] like Figure 1 As shown, in an embodiment where the battery cell 100 is a soft-pack battery cell 100, a portion of the first conductive member 30 is located within the outer shell 10 and connected to the connection area 21211, and another portion of the first conductive member 30 extends out of the outer shell 10 to form an output pole of the battery cell 100, and the output pole can be electrically connected to an external structure.

[0089] like Figure 2 As shown, in an embodiment where the battery cell 100 is a steel shell battery cell 100, the first conductive member 30 may be a switching plate, and the first conductive member 30 may electrically connect the connection area 21211 and the pole 40 so that the pole 40 forms an output terminal of the battery cell 100.

[0090] The corrosion-resistant layer 24 may be a uniform thickness structure, that is, the thickness of any position of the corrosion-resistant layer 24 is the same.

[0091] The corrosion-resistant layer 24 may also be a non-uniform thickness structure, that is, the corrosion-resistant layer 24 has at least two locations with different thicknesses. Figure 5 , Figure 6 As shown, in some embodiments, along the width direction Y of the first current collector, the corrosion-resistant layer 24 includes a first portion 241 and a second portion 242 , the first portion 241 is closer to the first active material layer 213 than the second portion 242 , and the thickness of the first portion 241 is greater than the thickness of the second portion 242 .

[0092] The second portion 242 and the first portion 241 are connected in the width direction Y of the first current collector. The first portion 241 and the second portion 242 may be integrally formed or separately provided and connected. The end of the first portion 241 away from the second portion 242 may be connected to the first active material layer 213 or may not be in contact.

[0093] The thickness of the first portion 241 is greater than the thickness of the second portion 242, that is, the corrosion-resistant layer 24 is a non-uniform thickness structure. The first portion 241 may be an iso-thickness structure. The first portion 241 may also be a non-uniform thickness structure, for example, in the width direction Y of the first current collector, from the first active material layer 213 to the corrosion-resistant layer 24, the thickness of the first portion 241 gradually decreases.

[0094] The second portion 242 may be of uniform thickness or non-uniform thickness, for example, in the width direction Y of the first current collector, the thickness of the second portion 242 gradually decreases from the first active material layer 213 to the corrosion-resistant layer 24 .

[0095] In the embodiment where the first part 241 is a non-uniform thickness structure and the second part 242 is a non-uniform thickness structure, the thickness of the first part 241 is greater than the thickness of the second part 242 , which means that the minimum thickness of the first part 241 is greater than the maximum thickness of the second part 242 .

[0096] By making the thickness of the first part 241 of the corrosion-resistant layer 24 close to the first active material layer 213 greater than the thickness of the second part 242 away from the first active material layer 213, the thickness of the corrosion-resistant layer 24 tends to decrease from one end close to the first active material layer 213 to the end away from the first active material layer 213, and the rigidity of the corrosion-resistant layer 24 tends to decrease from one end close to the first active material layer 213 to the end away from the first active material layer 213, which is beneficial to the formation of an arc at the corresponding position of the corrosion-resistant layer 24 when the first pole ear 212 is bent, reducing the risk of the first pole ear 212 cracking due to the formation of a dead fold when the first pole ear 212 is bent, thereby alleviating the problem of the first pole ear 212 being damaged during the bending process of the first pole ear 212, reducing the problem of short circuit of the battery cell 100 caused by the damage of the first pole ear 212, and improving the safety performance of the battery cell 100.

[0097] In some embodiments, the material of the first portion 241 includes an insulating material.

[0098] For example, the material of the first part 241 includes ceramics, which have good wear resistance and corrosion resistance. The material of the first part 241 includes ceramics, which reduces the risk of corrosion of the first pole ear 212, improves the safety performance of the battery cell 100, and extends the service life of the battery cell 100. The material of the first part 241 can also include one or more of silicone rubber, fluoroplastics, polyether ketone, polytetrafluoroethylene, etc.

[0099] In some embodiments, the material of the second portion 242 includes an insulating material.

[0100] For example, the material of the second part 242 includes ceramic, silicone rubber, fluoroplastic, polyether ketone, polytetrafluoroethylene, etc.

[0101] One of the first portion 241 and the second portion 242 may further include an insulating material, and both the first portion 241 and the second portion 242 may include an insulating material.

[0102] The first portion 241 and / or the second portion 242 includes insulating material, which is beneficial to reducing the risk of short circuit of the battery cell 100 and improving the safety performance of the battery cell 100 .

[0103] In some embodiments, the material of the second portion 242 includes one or more of ceramics, molecular sieves, aluminum fluoride, high molecular polymers, and graphene.

[0104] Ceramics have good wear resistance and corrosion resistance. The material of the second part 242 includes ceramics, which reduces the risk of corrosion of the first pole ear 212, thereby reducing the risk of short circuit of the first pole ear 212 due to corrosion and inverted insertion under falling conditions, thereby improving the safety performance and reliability of the battery cell 100 and extending the service life of the battery cell 100.

[0105] The molecular sieve has good adsorption performance. The material of the first part 241 includes the molecular sieve, which can reduce the risk of the electrolyte contacting the first pole ear 212 or reduce the amount of contact between the electrolyte and the first pole ear 212, thereby reducing the risk of the first pole ear 212 being corroded or alleviating the degree of corrosion of the first pole ear 212, improving the safety performance of the battery cell 100 and extending the service life of the battery cell 100.

[0106] Aluminum fluoride has good chemical stability and corrosion resistance. The material of the second portion 242 includes aluminum fluoride, which is beneficial to reducing the risk of corrosion of the first electrode tab 212, improving the safety performance of the battery cell 100 and extending the service life of the battery cell 100.

[0107] The chemical structure of graphene makes it have a good barrier effect. The material of the first part 241 includes molecular sieve, which can reduce the risk of contact with the electrolyte or reduce the amount of contact with the electrolyte, thereby improving the safety performance of the battery cell 100 and extending the service life of the battery cell 100.

[0108] The material of the second part 242 includes one or more of ceramics, molecular sieves, aluminum fluoride, high molecular polymers, and graphene, so that the corrosion resistance of the second part 242 is better.

[0109] In the embodiment where the material of the second portion 242 includes a molecular sieve, the pore size of the molecular sieve is less than or equal to 0.3 nm.

[0110] The pore size of molecular sieve refers to the diameter of the pore system of molecular sieve. The pore size of molecular sieve is less than or equal to 0.3nm, and it can adsorb molecules with a diameter less than 0.3nm, such as water molecules.

[0111] Illustratively, the pore size of the molecular sieve may be 0.02 nm, 0.04 nm, 0.06 nm, 0.08 nm, 0.1 nm, 0.12 nm, 0.14 nm, 0.16 nm, 0.18 nm, 0.2 nm, 0.22 nm, 0.24 nm, 0.26 nm, 0.28 nm, or 0.3 nm.

[0112] The material of the second part 242 includes molecular sieves, and the pore size of the molecular sieve is less than or equal to 0.3 nm, so that the second part 242 has good adsorption properties, which can reduce the risk of the electrolyte contacting the first pole ear 212 or reduce the amount of contact between the electrolyte and the first pole ear 212, thereby reducing the risk of the first pole ear 212 being corroded or alleviating the degree of corrosion of the first pole ear 212, improving the safety performance of the battery cell 100 and extending the service life of the battery cell 100.

[0113] In some embodiments, the material of the first portion 241 and the material of the second portion 242 may be different. For example, the material of the first portion 241 is ceramic, and the material of the second portion 242 is aluminum fluoride. The material of the first portion 241 and the material of the second portion 242 are different, which facilitates the selection of materials with better performance for the first portion 241 and the second portion 242, thereby improving the overall performance of the corrosion-resistant layer 24, thereby reducing the risk of the first tab 212 being corroded by the electrolyte.

[0114] In other embodiments, the material of the first part 241 is the same as the material of the second part 242. For example, the material of the first part 241 and the material of the second part 242 are both ceramic, or the material of the first part 241 and the material of the second part 242 are both aluminum fluoride. The material of the first part 241 and the material of the second part 242 are the same, which facilitates the setting of the corrosion-resistant layer 24.

[0115] like Figure 6 As shown, in some embodiments, the thickness of the second portion 242 is h, 1 nm ≤ h ≤ 5 μm.

[0116] Illustratively, h may be 1 nn, 100 nm, 500 nm, 700 nm, 900 nm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, etc.

[0117] The thickness of the second portion 242 is greater than or equal to 1 nm, so that the thickness of the second portion 242 is relatively large, so that the strength and corrosion resistance of the second portion 242 are better, thereby improving the strength of the first pole ear 212 and reducing the risk of corrosion of the second pole ear 222, and improving the safety performance of the battery cell 100. The thickness of the second portion 242 is less than or equal to 5 μm, which can reduce the space occupied by the corrosion-resistant layer 24, alleviate the problem of reduced energy density of the battery cell 100 due to the provision of the corrosion-resistant layer 24, and enable the battery cell 100 to have a higher energy density. Therefore, 1nm≤h≤5μm is conducive to improving the safety performance of the battery cell 100 and enabling the battery cell 100 to have a higher energy density.

[0118] Furthermore, 30nm≤h≤2μm.

[0119] Illustratively, h may be 30 nm, 50 nm, 80 nm, 600 nm, 800 nm, 1.1 μm, 1.2 μm, 1.3 μm, 1.4 μm, 1.6 μm, 1.7 μm, 1.8 μm, 1.9 μm, 2 μm, etc.

[0120] By making the thickness of the second part 242 greater than or equal to 30 nm, the thickness of the second part 242 is greater, so that the strength and corrosion resistance of the second part 242 are better, thereby further improving the strength of the first pole ear 212 and further reducing the risk of corrosion of the second pole ear 222, and further improving the safety performance of the battery cell 100. The thickness of the second part 242 is less than or equal to 2 μm, which can further reduce the space occupied by the corrosion-resistant layer 24, further alleviate the problem of reduced energy density of the battery cell 100 due to the provision of the corrosion-resistant layer 24, and enable the battery cell 100 to have a higher energy density. Therefore, 30 nm ≤ h ≤ 2 μm is conducive to further improving the safety performance of the battery cell 100 and enabling the battery cell 100 to have a higher energy density.

[0121] In some embodiments, along the width direction Y of the first current collector, one end of the first portion 241 away from the second portion 242 is connected to the first active material layer 213, the other end of the first portion 241 is connected to the second portion 242, and the end of the second portion 242 away from the first portion 241 extends to the edge of the first electrode tab 212 away from the first active material layer 213.

[0122] The first part 241 is connected to the first active material layer 213 at one end away from the second part 242, and the other end of the first part 241 is connected to the second part 242. The end of the second part 242 away from the first part 241 extends to the edge of the first pole ear 212 away from the first active material layer 213, so that the corrosion-resistant layer 24 covers a larger area of ​​the surface of the first pole ear 212, further reducing the risk of corrosion of the first pole ear 212 and improving the safety performance of the battery cell 100.

[0123] In an embodiment where the first active material layer 213 covers a portion of the first surface 2111 along the width direction Y of the first current collector, as shown in FIG. Figure 7 , Figure 8 As shown, the electrode assembly 20 further includes an insulating layer 25 . At least part of the second region 21112 is provided with the insulating layer 25 . Along the width direction Y of the first current collector, the insulating layer 25 is located between the corrosion-resistant layer 24 and the first active material layer 213 .

[0124] Along the width direction Y of the first current collector, the first active material layer 213, the insulating layer 25 and the corrosion-resistant layer 24 are arranged in sequence, the insulating layer 25 is located between the first active material layer 213 and the corrosion-resistant layer 24, and one end of the insulating layer 25 and one end of the first active material layer 213 can be connected to reduce the risk of the electrolyte contacting the first current collector 211 from between the first active material layer 213 and the insulating layer 25 and corroding the first current collector 211.

[0125] Along the width direction Y of the first current collector, one end of the insulating layer 25 away from the first active material layer 213 is connected to one end of the corrosion-resistant layer 24 , reducing the risk of the electrolyte contacting the first electrode tab 212 between the corrosion-resistant layer 24 and the insulating layer 25 and corroding the first electrode tab 212 .

[0126] At least part of the second region 21112 is provided with an insulating layer 25 . Along the width direction Y of the first current collector, the insulating layer 25 is located between the corrosion-resistant layer 24 and the first active material layer 213 , thereby reducing the risk of short circuit of the battery cell 100 and improving the safety performance of the battery cell 100 .

[0127] In some embodiments, the material of the insulating layer 25 includes ceramics and / or polymers. The material of the insulating layer 25 can be one of ceramics and polymers, or the material of the insulating layer 25 can also include ceramics and polymers.

[0128] The material of the insulating layer 25 includes ceramic and / or high molecular polymer with good insulation performance and corrosion resistance, which can reduce the risk of internal contact short circuit of the battery cell 100 and the risk of corrosion of the first electrode tab 212, and improve the safety performance of the battery cell 100.

[0129] like Figure 7 , Figure 8 As shown, in some embodiments, the minimum thickness of the insulating layer 25 is greater than the minimum thickness of the corrosion-resistant layer 24 .

[0130] The insulating layer 25 may be of equal thickness, that is, the thickness of any position of the insulating layer 25 is the same. Figure 8 As shown, the insulating layer 25 is of uniform thickness, and the thickness of the insulating layer 25 is H'; the corrosion-resistant layer is of uniform thickness, and the thickness of the corrosion-resistant layer is H, where H'>H.

[0131] The insulating layer 25 may also be a non-uniform thickness structure, that is, the thicknesses of at least two locations of the insulating layer 25 are different.

[0132] If the minimum thickness of the insulating layer 25 is greater than the maximum thickness of the corrosion-resistant layer 24, then the thickness of the insulating layer 25 and the corrosion-resistant layer 24 tends to decrease as a whole from the insulating layer 25 to the corrosion-resistant layer 24, and the stiffness of the insulating layer 25 and the corrosion-resistant layer 24 tends to decrease as a whole from the insulating layer 25 to the corrosion-resistant layer 24, which is beneficial for forming an arc at corresponding positions of the insulating layer 25 and the corrosion-resistant layer 24 when the first pole ear 212 is bent, reducing the risk of cracking of the first pole ear 212 due to the formation of a dead fold when the first pole ear 212 is bent, thereby alleviating the problem of damage to the first pole ear 212 during the bending process of the first pole ear 212, reducing the problem of short circuit of the battery cell 100 due to damage of the first pole ear 212, and improving the safety performance of the battery cell 100.

[0133] like Fig.12 As shown, in some embodiments, along the length direction Z of the first current collector, the first electrode tab 212 has two opposite third surfaces 2122 , and at least one of the third surfaces 2122 is provided with a corrosion-resistant layer 24 .

[0134] In the embodiment where the first electrode sheet 21 is a winding structure, the length direction Z of the first current collector corresponds to the winding direction of the electrode assembly 20 .

[0135] A third surface 2122 of the first electrode tab 212 is provided with a corrosion-resistant layer 24 , or both third surfaces 2122 of the first electrode tab 212 are provided with a corrosion-resistant layer 24 .

[0136] The corrosion-resistant layer 24 may completely cover the third surface 2122 , or may only cover a portion of the third surface 2122 .

[0137] At least one third surface 2122 is provided with a corrosion-resistant layer 24, which can reduce the risk of the first pole ear 212 being corroded by the electrolyte in the length direction Z of the first current collector and causing the first pole ear 212 to break, thereby reducing the risk of the first pole ear 212 breaking and causing a short circuit due to being inverted and contacting the second pole piece 22 (the pole piece with opposite polarity to the first pole piece 21) when it falls, thereby improving the safety performance of the battery cell 100.

[0138] Of course, if Fig.13 As shown, in some other embodiments, along the length direction Z of the first current collector, the first current collector 211 has two opposite fourth surfaces 2112 , and at least one of the fourth surfaces 2112 is provided with a corrosion-resistant layer 24 .

[0139] A corrosion-resistant layer 24 is disposed on one fourth surface 2112 of the first current collector 211 , or both fourth surfaces 2112 of the first current collector 211 are disposed on the corrosion-resistant layer 24 .

[0140] The corrosion-resistant layer 24 may completely cover the fourth surface 2112 , or may only cover a portion of the fourth surface 2112 .

[0141] At least one fourth surface 2112 is provided with a corrosion-resistant layer 24 , which can reduce the risk of the first current collector 211 being corroded by the electrolyte in the length direction Z of the first current collector, resulting in a reduction in the strength of the first current collector 211 .

[0142] In an embodiment where the first pole piece 21 includes a plurality of first pole ears 212 , at least one second surface 2121 of some of the first pole ears 212 may be provided with a corrosion-resistant layer 24 , which can reduce the amount of the corrosion-resistant layer 24 used and reduce the space occupied by the corrosion-resistant layer 24 inside the battery cell 100 , thereby facilitating improving the energy density of the battery cell 100 .

[0143] At least one second surface 2121 of all first pole tabs 212 may also be provided with a corrosion-resistant layer 24 , so that the risk of each first pole tab 212 being corroded by the electrolyte is low, further improving the safety performance of the battery cell 100 .

[0144] like Fig.14 , Fig.15 As shown, in some embodiments, the second pole piece 22 includes a second current collector 221, a second pole ear 222 and a second active material layer 223. Along the width direction of the second current collector 221, the second pole ear 222 is connected to one end of the second current collector 221. Along the thickness direction of the second current collector 221, the second current collector 221 has two opposite fifth surfaces 2211, the second pole ear 222 has two opposite sixth surfaces 2221, at least one fifth surface 2211 is provided with the second active material layer 223, and at least one sixth surface 2221 is provided with the corrosion-resistant layer 24; wherein the area of ​​one sixth surface 2221 is W, the area of ​​one sixth surface 2221 covered by the corrosion-resistant layer 24 is W1, and 0.8≤W1 / W≤1.

[0145] By providing the corrosion-resistant layer 24 on at least one sixth surface 2221 of the second pole tab 222, the risk of the second pole tab 222 being corroded by the electrolyte in the thickness direction of the second current collector 221 and causing the second pole tab 222 to break can be reduced, thereby reducing the risk of the second pole tab 222 being inverted and contacting the first pole piece 21 under a falling condition and causing a short circuit, thereby improving the safety performance and reliability of the battery cell 100 and extending the service life of the battery cell 100. By making the ratio of the area W1 of the sixth surface 2221 covered by the corrosion-resistant layer 24 to the area W of one sixth surface 2221 greater than or equal to 0.8, the area of ​​the sixth surface 2221 covered by the corrosion-resistant layer 24 is large enough, thereby reducing the risk of the second pole tab 222 being corroded by the electrolyte, reducing the risk of the second pole tab 222 being short-circuited due to corrosion and inversion under a falling condition, thereby improving the safety performance and reliability of the battery cell 100 and extending the service life of the battery cell 100. By making the ratio of the area W1 of the sixth surface 2221 covered by the corrosion-resistant layer 24 to the area W of the sixth surface 2221 less than or equal to 1, the space occupied by the corrosion-resistant layer 24 is reduced, which is beneficial to improving the energy density of the battery cell 100. Therefore, 0.8≤W1 / W≤1 is beneficial to improving the safety performance of the battery cell 100 and the energy density of the battery cell 100.

[0146] An embodiment of the present application further provides an electrical device, and the electrical device includes the battery cell 100 provided in any of the above embodiments.

[0147] The battery cell 100 provides electric energy for the electric device to operate.

[0148] The battery cell 100 provided by any of the above embodiments has good safety performance, which is beneficial to improving the power safety and power reliability of the power-consuming equipment powered by the battery cell 100.

[0149] By comparing whether the first pole tab 212 is broken after low-temperature storage in a battery cell 100 in which the second surface 2121 of the first pole tab 212 is not provided with the corrosion-resistant layer 24 (Comparative Example 1) and a battery cell 100 in which both second surfaces 2121 of the first pole tab 212 are provided with the corrosion-resistant layer 24 (Examples 1 to 5), the results in Table 1 are obtained:

[0150] Table 1

[0151] Is the first electrode tab 212 broken after low temperature storage? Comparative Example 1 fracture Comparative Example 2 fracture Example 1 No break Example 2 No break Example 3 No break Example 4 No break Example 5 No break

[0152] Among them, in Example 1, according to the width of the positive electrode plate of the battery cell 100, HF treatment is performed on a certain width range of the edge of the aluminum foil to produce AlF3 (that is, the material of the corrosion-resistant layer 24 is AlF3).

[0153] The production process of battery cell 100 is as follows:

[0154] <Preparation of positive electrode sheet>

[0155] 19wt% lithium iron phosphate (LFP), 78wt% lithium manganese oxide (LMO), 1.5wt% PVDF, 0.8wt% SP and 0.7wt% CNT were mixed and stirred evenly, and then coated on the first area 21111 of the first surface 2111 of the positive electrode current collector with a thickness of 12μm, and the coating weight on one side was 0.357mg / mm 2 The compacted density of one side is 2.7g / cm 3 At the same time, a ceramic coating (insulating layer 25) is applied to the second area 21112, and the positive electrode sheet is obtained through processes such as drying, cold pressing, slitting, and die cutting.

[0156] <Preparation of negative electrode sheet>

[0157] 96wt% graphite, 1.5wt% CMC-Na, 1.5wt% PVDF, and 1wt% SP were mixed and stirred evenly, and then coated on the negative electrode current collector with a thickness of 6μm. The coating weight on one side was 0.061mg / mm 2 The compacted density of one side is 1.5g / cm 3 After drying, cold pressing, slitting, die cutting and other processes, the negative electrode sheet is obtained.

[0158] <Preparation of Separator>

[0159] A polypropylene (PP) film with a thickness of 16 μm is used.

[0160] <Preparation of Electrolyte>

[0161] In a dry argon atmosphere, ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC) and ethyl methyl carbonate (EMC) are mixed in a mass ratio of 20:30:40:10 to obtain an organic solvent, and then lithium salt LiFSI is added to the organic solvent to dissolve and mix evenly to obtain an electrolyte with a lithium salt concentration of 1 mol / L.

[0162] <Preparation of battery cells>

[0163] The positive electrode sheet, separator, negative electrode sheet, and separator are stacked and wound together to form an electrode assembly 20, and then packaged with aluminum-plastic film, injected with liquid, and chemically formed to prepare a battery cell 100.

[0164] The battery cells 100 prepared in the above-mentioned embodiments and comparative examples were fully charged and stored at low temperature (storage test conditions: storage at -10°C and 4.2V for 30D), and then the battery cells were disassembled to confirm whether each aluminum tab (first tab) was broken.

[0165] The difference between Example 2 and Example 1 is that the material of the corrosion-resistant layer 24 is a molecular sieve, and the pore size of the molecular sieve is less than 0.3 nm.

[0166] The difference between Example 3 and Example 1 is that the material of the corrosion-resistant layer 24 is polypropylene, and the thickness of the corrosion-resistant layer 24 is less than 5 μm.

[0167] The difference between Example 4 and Example 1 is that the material of the corrosion-resistant layer 24 is polypropylene, and the thickness of the corrosion-resistant layer 24 is less than 5 μm.

[0168] The difference between Example 5 and Example 1 is that the electrolyte is LiTFSI.

[0169] The difference between Comparative Example 1 and Example 1 is that the corrosion-resistant layer 24 is not provided.

[0170] The difference between Comparative Example 2 and Example 5 is that the corrosion-resistant layer 24 is not provided.

[0171] From Table 1, we can see that:

[0172] (1) It can be seen from Comparative Example 1 and Example 1, and from Comparative Example 1 and Example 1 that after low-temperature storage, the first pole ear 212 of the battery cell 100 provided with the corrosion-resistant layer is not broken, and the first pole ear 212 of the battery cell 100 not provided with the corrosion-resistant layer 24 is broken. The corrosion-resistant layer can reduce or avoid corrosion of the first pole ear 212, effectively improving the problem of the first pole ear 212 being broken due to corrosion by the electrolyte.

[0173] (2) It can be seen from Examples 1 to 4 that when the material of the corrosion-resistant layer 24 is AlF3, molecular sieve, polypropylene, or polypropylene, after low-temperature storage, the first pole ear 212 of the battery cell 100 is not broken. Therefore, using any one of AlF3, molecular sieve, polypropylene, or polypropylene as the material of the corrosion-resistant layer 24 can reduce or avoid corrosion of the first pole ear 212, and can effectively improve the problem of the first pole ear 212 being broken due to corrosion by the electrolyte.

[0174] (3) It can be seen from Examples 1 and 5 that the anti-corrosion performance of the corrosion-resistant layer 24 is substantially unaffected by the composition of the electrolyte. By providing the corrosion-resistant layer 24 on the first electrode tab 212, it can adapt to different electrolyte environments.

[0175] The above are only preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and changes.

Claims

1. A battery cell, characterized in that: The invention comprises an electrode assembly, wherein the electrode assembly comprises a first pole piece and a corrosion-resistant layer: The first pole sheet comprises a first current collector, a first pole tab and a first active material layer. Along the width direction of the first current collector, the first pole tab is connected to one end of the first current collector. Along the thickness direction of the first current collector, the first current collector has two opposite first surfaces, the first pole tab has two opposite second surfaces, at least one of the first surfaces is provided with the first active material layer, and at least one of the second surfaces is provided with the corrosion-resistant layer. Among them, the area of ​​one of the second surfaces is S, the area of ​​one of the second surfaces covered by the corrosion-resistant layer is S1, and 0.8≤S1 / S≤1.

2. The battery cell according to claim 1, characterized in that: Along the width direction of the first current collector, the corrosion-resistant layer includes a first portion and a second portion, the first portion is closer to the first active material layer than the second portion, and a thickness of the first portion is greater than a thickness of the second portion.

3. The battery cell according to claim 2, characterized in that: The first portion includes an insulating material; and / or the second portion includes an insulating material.

4. The battery cell according to claim 2 or 3, characterized in that: The material of the first part includes ceramic.

5. The battery cell according to any one of claims 2 to 4, characterized in that: The material of the second part includes one or more of ceramics, molecular sieves, aluminum fluoride, high molecular polymers, and graphene.

6. The battery cell according to claim 5, characterized in that: The material of the second part includes molecular sieve, and the pore size of the molecular sieve is less than or equal to 0.3 nm.

7. The battery cell according to any one of claims 2 to 6, characterized in that: The material of the first part is different from the material of the second part; or, the material of the first part is the same as the material of the second part.

8. The battery cell according to any one of claims 2 to 7, characterized in that: The thickness of the second portion is h, 1 nm≤h≤5 μm, preferably, 30 nm≤h≤2 μm.

9. The battery cell according to any one of claims 2 to 8, characterized in that: Along the width direction of the first current collector, one end of the first part away from the second part is connected to the first active material layer, the other end of the first part is connected to the second part, and one end of the second part away from the first part extends to the edge of the first electrode tab away from the first active material layer.

10. The battery cell according to any one of claims 2 to 8, characterized in that: The first surface includes a first area covered by the first active material layer and a second area not covered by the first active material layer. The first area, the second area and the first electrode tab are arranged in sequence and connected along the width direction of the first current collector. At least part of the second area is provided with an insulating layer. Along the width direction of the first current collector, the insulating layer is located between the corrosion-resistant layer and the first active material layer. The material of the insulating layer includes ceramic and / or high molecular polymer.

11. The battery cell according to claim 10, characterized in that: The minimum thickness of the insulating layer is greater than the maximum thickness of the corrosion-resistant layer.

12. The battery cell according to any one of claims 1 to 11, characterized in that: Along the length direction of the first current collector, the first electrode tab has two opposite third surfaces, and at least one of the third surfaces is provided with the corrosion-resistant layer.

13. The battery cell according to any one of claims 1 to 12, characterized in that: The first pole sheet includes a plurality of the first pole tabs, the plurality of the first pole tabs are arranged at intervals along the length direction of the first current collector, and at least one second surface of at least one of the first pole tabs is provided with the corrosion-resistant layer.

14. The battery cell according to any one of claims 1 to 13, characterized in that: The second surface includes a connection area not covered by the corrosion-resistant layer; The battery cell further includes a first conductive member electrically connected to the connection area.

15. An electrical equipment, characterized in that: Comprising a battery cell according to any one of claims 1-14.

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