Battery cell, battery pack and electric device

Abstract

This application relates to the field of battery technology, and more particularly to a battery cell, battery pack, and electrical device. An embodiment of this application provides a battery cell including a housing and an electrode assembly. The housing defines a receiving cavity and has a first sidewall. Along a first direction, the first sidewall has a first edge and a second edge. The first sidewall has a first weld and a first centerline extending along a second direction. The distance between the first centerline and the first edge is equal to the distance between the first centerline and the second edge. The first direction, the second direction, and the thickness direction of the first sidewall are mutually perpendicular. The electrode assembly is disposed within the receiving cavity. Along the first direction, the dimension of the first sidewall is 'a', the distance between the first weld and the first centerline is 'd', and along the thickness direction of the first sidewall, the distance between the first sidewall and the electrode assembly is 'h', satisfying: 2mm ≤ h + d ≤ (a / 2 + 1)mm. This reduces the probability of the housing expanding and deforming.

Description

This application is a divisional application. The original application has the application number 2025105636219 and the original application date is April 30, 2025. The entire contents of the original application are incorporated herein by reference. Technical Field

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

[0002] Currently, when the battery casing is long, it is formed by first bending or rolling the casing, and then welding it to the side. Typically, the casing substrate is fused together, resulting in a weld strength lower than the substrate. When the gas generated inside the electrode assembly exceeds the casing's pressure tolerance, the casing will deform, and the weaker weld may crack, affecting battery safety. Summary of the Invention

[0003] This application provides a battery cell, a battery pack, and an electrical device that reduces the probability of the casing expanding and deforming.

[0004] To achieve the above objectives, the main technical solutions adopted in this application include: In a first aspect, embodiments of this application provide a battery cell, including a housing and an electrode assembly. The housing defines a receiving cavity. The housing has a first sidewall. Along a first direction, the first sidewall has a first edge and a second edge. The first sidewall has a first weld and a first centerline extending along a second direction. The distance between the first centerline and the first edge and the distance between the first centerline and the second edge are equal. The first direction, the second direction, and the thickness direction of the first sidewall are perpendicular to each other. The electrode assembly is disposed within the receiving cavity. Wherein, along the first direction, the dimension of the first sidewall is a, satisfying: 10mm≤a≤100mm; the distance between the first weld and the first centerline is d; and along the thickness direction of the first sidewall, the distance between the first sidewall and the electrode assembly is h, satisfying: 2mm≤h+d≤(a / 2+1)mm.

[0005] The battery cell proposed in this application has a distance d between the first weld and the first center line along the first direction, and a distance h between the first sidewall and the electrode assembly along the thickness direction of the first sidewall. The expansion and deformation of the casing is reduced by adjusting the spacing between the first weld and the first center line, and the spacing between the first sidewall and the electrode assembly. If h+d is too large, it indicates that the distance h between the electrode assembly and the first sidewall is too large, and the spacing between the first weld and the first center line is also too large. This results in low space utilization of the electrode assembly, and poor welding strength because the first weld is too close to the first or second edge. If h+d is too small, it indicates that the distance between the electrode assembly and the first sidewall is too small, and the distance between the first weld and the first centerline is also too small. The gas generated during the charging and discharging of the electrode assembly does not have enough space to expand, and the gas generated by the electrode assembly exceeds the pressure bearing capacity of the casing. The first weld, as a weak area, is too close to the first centerline, causing the gas accumulated inside the casing during the charging and discharging of the battery to impact the first sidewall and the first weld. Since the strength of the first weld is lower than that of other areas of the first sidewall, it is prone to expansion and deformation, which further increases the risk of the first sidewall expanding and deforming at the first weld and reduces the safety performance of the battery cell.

[0006] Therefore, it is necessary to control 2mm≤h+d≤(a / 2+1)mm so that the distance between the first sidewall and the electrode assembly and the spacing between the first weld and the first center line meet the strength requirements, reduce the expansion deformation at the first weld on the first sidewall, and thus improve the safety performance of the battery cell.

[0007] Furthermore, since the outer surface area of ​​the first sidewall is smaller than that of either the third or fourth sidewall, when the electrode assembly is located inside the housing, the stacking direction of the positive electrode, negative electrode, and separator is perpendicular to the third and fourth sidewalls. Therefore, the positive electrode, negative electrode, and separator are parallel to the third and fourth sidewalls. In other words, the electrode assembly near the first sidewall is the side where the positive electrode, negative electrode, and separator are stacked, and it is not covered by the separator. To reduce the probability of expansion and deformation of the first weld and improve the space utilization of the electrode assembly, the distance h between the first sidewall and the electrode assembly can be controlled between 1.25 mm and 3 mm.

[0008] Secondly, embodiments of this application provide a battery pack comprising the battery cells described in any of the above embodiments.

[0009] The battery pack proposed in this application includes individual battery cells and has the same beneficial effects as individual battery cells.

[0010] Thirdly, embodiments of this application provide electrical equipment, including battery cells or battery packs as described in any of the above embodiments.

[0011] The electrical equipment proposed in this application includes a battery cell or a battery pack, and therefore has the same beneficial effects as a battery cell or battery pack. Attached Figure Description

[0012] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0013] Figure 1 This is a schematic diagram of the structure of a single battery cell in this application; Figure 2 This is a schematic diagram of the structure of a single battery cell in one embodiment of this application; Figure 3 for Figure 2 Sectional view of section DD; Figure 4 for Figure 3 Enlarged view of region F in the middle; Figure 5 This is a schematic diagram of the structure of a single battery cell in another embodiment of this application; Figure 6 This is a schematic diagram of the structure of a single battery cell in another embodiment of this application.

[0014] [Explanation of Labels in the Attached Image] 1: Shell; 11: First sidewall; 111: First edge; 112: Second edge; 12: First centerline; 13: First weld; 14: Third sidewall; 2: Electrode assembly; A: First direction; B: Second direction; C: Thickness direction of the first sidewall. Detailed Implementation

[0015] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0016] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the description of this application is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms "comprising" and "having," and any variations thereof, in the description, claims, and accompanying drawings of this application are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the description, claims, or accompanying drawings of this application are used to distinguish different objects, not to describe a specific order or hierarchy.

[0017] In this application, the reference to "embodiment" means that a specific 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 mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this application can be combined with other embodiments.

[0018] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "attachment" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0019] In this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, in this application, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0020] In this application, "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0021] The battery in this application is a secondary battery, also known as a rechargeable battery or storage battery, which refers to a battery that can be used again after being discharged by recharging to activate the active materials.

[0022] Typically, a secondary battery includes an electrode assembly, an electrolyte, and an outer casing. The electrode assembly consists of a positive electrode, a negative electrode, and a separator. The electrode assembly and electrolyte are assembled inside the outer casing. During charging and discharging, active ions (such as lithium ions) move back and forth between the positive and negative electrodes, inserting and extracting. The separator, positioned between the positive and negative electrodes, primarily prevents short circuits while allowing active ions to pass through. The electrolyte, located between the positive and negative electrodes, mainly serves to conduct active ions.

[0023] As an example, the preparation process of a secondary battery is as follows: the positive electrode, separator, and negative electrode are stacked in sequence, with the separator acting as a separator between the positive and negative electrodes. Then, the electrodes are wound or stacked to obtain an electrode assembly. The electrode assembly is placed in an outer packaging shell, dried, and then injected with electrolyte. After vacuum sealing, settling, formation, and shaping, a secondary battery is obtained.

[0024] A positive electrode typically includes a positive current collector and a positive electrode film layer disposed on at least one side of the positive current collector. The positive electrode film layer includes a positive electrode active material, which can be any existing publicly disclosed positive electrode active material or a positive electrode active material optimized based on existing materials.

[0025] In some embodiments, the positive electrode sheet can be prepared by dispersing the above-mentioned components for preparing the positive electrode sheet, such as positive electrode active material, conductive agent, binder and any other components, in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry onto the positive electrode current collector, and then obtaining the positive electrode sheet after drying, rolling, cutting and other processes.

[0026] The binder is used to improve the adhesion between positive electrode active material particles and the adhesion between the positive electrode active material and the current collector. The binder may be at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyvinyl alcohol (PVA), styrene-butadiene rubber (SBR), polyacrylonitrile (PAN), polyimide (PI), polyacrylic acid (PAA), polyacrylate, polyolefin, sodium carboxymethyl cellulose (CMC) or sodium alginate.

[0027] The positive current collector of this application may be made of, for example, stainless steel, aluminum, nickel, titanium, sintered carbon; or aluminum or stainless steel that has undergone a surface treatment of carbon, nickel, titanium, silver, etc.

[0028] The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer disposed on at least one side of the negative electrode current collector. The negative electrode active material layer includes a silicon-based material, which may be a silicon-carbon material and / or a silicon-oxygen material. As an example, the silicon-based material may be one or more of a silicon-carbon composite negative electrode material, a silicon suboxide negative electrode material, a modified silicon suboxide negative electrode material, and nano-silicon materials. The negative electrode active material in the negative electrode active material layer may also optionally include one or more of artificial graphite, natural graphite, and hard carbon.

[0029] In some embodiments, the negative electrode sheet can be prepared by dispersing the components used to prepare the negative electrode sheet, such as the negative electrode active material, conductive agent, binder and any other components, in a solvent (e.g., water) to form a negative electrode slurry; coating the negative electrode slurry onto the negative electrode current collector, and then obtaining the negative electrode sheet after drying, rolling, cutting and other processes.

[0030] In some implementations, as an example, the negative electrode conductive agent may be one or more of conventional negative electrode conductive agents such as acetylene black and carbon nanotubes; as an example, the binder may be one or more of conventional negative electrode binders such as styrene-butadiene rubber latex (SBR), polyvinylidene fluoride (PVDF), polyacrylic acid (PAA), and sodium carboxymethyl cellulose (CMC).

[0031] In some implementations, as an example, the negative current collector can be one of the conventional negative current collectors such as copper foil.

[0032] The electrolyte acts as a conductor of ions between the positive and negative electrodes. As an example, the electrolyte of this application can be any electrolyte suitable for electrochemical energy storage devices in the art. The electrolyte includes an electrolyte and a solvent. The electrolyte typically includes a lithium salt, and additives may also be added to the electrolyte. Specifically, the lithium salt includes at least one of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalate borate (LiDFOB), lithium dioxalate borate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluorodioxalate phosphate (LiDFOP), and lithium tetrafluorooxalate phosphate (LiTFOP). The concentration of the electrolyte in the electrolyte can be 0.5–5 mol / L. The solvent includes at least one of ethylene carbonate (EC), propylene carbonate (PC), methyl ethyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butyl carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS), and diethyl sulfone (ESE).

[0033] In some implementations, as an example, the additive may be a conventional electrolyte additive such as fluoroethylene carbonate (FEC), chloroethylene carbonate (CEC), or vinylene carbonate (VC).

[0034] In some embodiments, the secondary battery also includes a separator. As an example, the separator can be one of PP, PE, or PP / PF; the separator can also be a structure in which a coating is formed on the surface of a base film, wherein the base film coating can be one of PP, PE, or PP / PF, and the coating can be an inorganic coating and / or an organic coating. The inorganic coating can be selected from alumina ceramic layers, osmium silicate, etc., and the organic coating can be selected from PVDF, etc.

[0035] Currently, when the gas generated inside the electrode assembly exceeds the pressure tolerance of the casing, the gas first impacts the middle area of ​​the casing sidewall. Because the weld seam has lower strength compared to other areas of the casing, it is more prone to expansion and deformation. If the weld seam is located in the middle area of ​​the casing sidewall, and the distance between the electrode assembly and the casing sidewall is small, the gas generated inside the electrode assembly does not have enough space to expand, resulting in greater pressure on the sidewall. This makes the weld seam more likely to expand and deform, or even rupture, affecting the battery's safety performance. Therefore, it is necessary to control the location of the weld seam and the distance between the casing sidewall and the electrode assembly.

[0036] In view of this, this application provides a battery cell, a battery pack, and an electrical device that can reduce the expansion and deformation of the casing and improve the safety performance of the battery cell.

[0037] Firstly, reference Figures 1 to 6 This application provides a battery cell, the battery housing 1 including a housing 1 and an electrode assembly 2. The housing 1 defines a receiving cavity. The housing 1 has a first sidewall 11. Along a first direction A, the first sidewall 11 has a first edge 111 and a second edge 112. The first sidewall 11 has a first weld 13 extending along a second direction B and a first center line 12. The distance between the first center line 12 and the first edge 111 and the distance between the first center line 12 and the second edge 112 are equal. The first direction A, the second direction B, and the thickness direction C of the first sidewall 11 are perpendicular to each other. The electrode assembly 2 is disposed in the receiving cavity. Wherein, along the first direction A, the dimension of the first sidewall 11 is a, satisfying: 10mm≤a≤100mm, the distance between the first weld 13 and the first center line 12 is d, and along the thickness direction C of the first sidewall 11, the distance between the first sidewall 11 and the electrode assembly 2 is h, satisfying: 2mm≤h+d≤(a / 2+1)mm.

[0038] Specifically, the first direction A is the width direction of the first sidewall 11, and the second direction B is the length direction of the second sidewall. The housing 1 has multiple sidewalls that enclose a receiving cavity, within which the electrode assembly 2 is disposed. A first weld 13 is disposed on the first sidewall 11 and extends along the second direction B. The first weld 13 can be located between the first centerline 12 and the first edge 111, or between the second centerline and the second edge 112. Alternatively, the first weld 13 can coincide with the first centerline 12. Along the first direction A, the distance between the first centerline 12 and the first edge 111 is equal to the distance between the first centerline 12 and the second edge 112.

[0039] The battery cell proposed in this application has a distance d between the first weld 13 and the first center line 12 along the first direction A, and a distance h between the first sidewall 11 and the electrode assembly 2 along the thickness direction C of the first sidewall 11. By adjusting the spacing between the first weld 13 and the first center line 12, and the spacing between the first sidewall 11 and the electrode assembly 2, the expansion and deformation of the casing 1 can be reduced. If h+d is too large, it indicates that the distance h between the electrode assembly 2 and the first sidewall 11 is too large, and the spacing between the first weld 13 and the first center line 12 is also too large. This results in low space utilization of the electrode assembly 2, and poor welding strength because the first weld 13 is too close to the first edge 111 or the second edge 112. If h+d is too small, it indicates that the distance between the electrode assembly 2 and the first sidewall 11 is too small, and the distance between the first weld 13 and the first center line 12 is also too small. The gas generated by the electrode assembly 2 during charging and discharging does not have enough space to expand. The gas generated by the electrode assembly exceeds the pressure bearing capacity of the shell. Furthermore, the first weld 13, as a weak area, is too close to the first center line 12. This causes the gas pressure accumulated inside the shell during battery charging and discharging to impact the first sidewall 11 and the first weld 13. Since the strength of the first weld 13 is lower than that of other areas of the first sidewall 11, it is prone to expansion and deformation, which further increases the risk of the first sidewall 11 expanding and deforming at the first weld 13 and reduces the safety performance of the battery cell.

[0040] Therefore, it is necessary to control 2mm≤h+d≤(a / 2+1)mm so that the distance between the first sidewall 11 and the electrode assembly 2 and the spacing between the first weld 13 and the first center line 12 meet the strength requirements, reduce the expansion deformation at the first weld 13 on the first sidewall 11, and thus improve the safety performance of the battery cell.

[0041] It should be understood that, in order to reduce the misalignment of the positive and negative electrodes due to their identical dimensions, the size of the negative electrode in the electrode assembly 2 of this application is larger than that of the positive electrode. Since the electrode assembly 2 is wrapped with a white diaphragm, it is difficult to measure the distance between the first sidewall 11 and the electrode assembly 2. Therefore, this application can measure the distance between the first sidewall 11 and the negative electrode along the thickness direction C of the first sidewall 11.

[0042] Along the first direction A, the dimension a of the first sidewall 11 satisfies: 10mm ≤ a ≤ 100mm. The dimension of the first sidewall 11 can be 10mm, 15mm, 16mm, 20mm, 25mm, 30mm, 35mm, 40mm, 45mm, 50mm, 55mm, 60mm, 65mm, 70mm, 75mm, 80mm, 85mm, 90mm, 95mm, 98mm, or 100mm, etc.

[0043] Optionally, the distance between the first weld 13 and the first center line 12 satisfies: 0≤d<(a / 2)mm, and the distance between the first sidewall 11 and the electrode assembly 2 satisfies: 1.25mm≤h≤6mm.

[0044] The distance between the first weld 13 and the first center line 12 should not be too large. If the distance between the first weld 13 and the first center line 12 is too large, the first weld 13 will be close to the first edge 111 or the second edge 112, resulting in poor welding strength. The distance between the first weld 13 and the first center line 12 should not be too small either. If the distance between the first weld 13 and the first center line 12 is too small, the first weld 13 will be close to the first center line 12. If the gas generated by the electrode assembly 2 exceeds the pressure bearing capacity of the shell 1, the first weld 13 will be directly impacted by the gas, which will increase the probability of expansion and deformation at the first weld 13 on the first sidewall 11.

[0045] The distance d between the first weld 13 and the first centerline 12 can be 0, (0.01a)mm, (0.03a)mm, (0.05a)mm, (0.08a)mm, (0.1a)mm, (0.12a)mm, (0.14a)mm, (0.15a)mm, (0.16a)mm, (0.18a)mm, (0.20a)mm, (0.22a)mm ...12a)mm, (0.14a)mm, (0.15a)mm, (0.16a)mm, (0.18a)mm, (0.18a)mm, (0.18a)mm, (0.18a)mm, (0.18a)mm, (0.18a)mm, (0.18a)mm, (0.18a)mm, (0.18a)mm, (0.18a)mm, (0.18a)mm, (0.18a)mm, (0.18a)mm, (0.1 .24a)mm, (0.25a)mm, (0.27a)mm, (0.28a)mm, (0.30a)mm, (0.32a)mm, (0.35a)mm, (0.38a )mm, (0.40a)mm, (0.43a)mm, (0.45a)mm, (0.46a)mm, (0.47a)mm, (0.48a)mm or (0.49a)mm, etc.

[0046] The distance between the first sidewall 11 and the electrode assembly 2 should not be too large. If the distance between the first sidewall 11 and the electrode assembly 2 is too large, the space utilization rate of the electrode assembly 2 will be low. The distance between the first sidewall 11 and the electrode assembly 2 should not be too small. If the distance between the first sidewall 11 and the electrode assembly 2 is too small, the electrode assembly 2 will generate gas during charging and discharging. There will not be enough space in the housing 1 for the gas to expand. If the gas pressure exceeds the pressure bearing capacity of the housing 1, the pressure generated by the gas will directly impact the first weld 13, thereby increasing the probability of expansion and deformation at the first weld 13 on the first sidewall 11.

[0047] The distance h between the first sidewall 11 and the electrode assembly 2 can be 1.25mm, 1.3mm, 1.4mm, 1.5mm, 1.8mm, 2.0mm, 2.3mm, 2.6mm, 2.7mm, 2.8mm, 3.0mm, 3.2mm, 3.4mm, 3.5mm, 3.8mm, 4.0mm, 4.3mm, 4.5mm, 4.8mm, 5.0mm, 5.3mm, 5.5mm, 5.7mm, 5.8mm, or 6.0mm, etc.

[0048] Optionally, refer to Figures 3 to 4 The first weld 13 coincides with the first center line 12, and the distance between the first sidewall 11 and the electrode assembly 2 satisfies: 3mm≤h≤6mm.

[0049] If the first weld 13 coincides with the first centerline 12, then the first weld 13 is a weak area. When the electrode assembly 2 generates gas during charging and discharging, the gas pressure exceeds the pressure tolerance range of the housing 1, and the first weld 13 is directly impacted by the gas, easily causing expansion and deformation. In order to reduce the deformation caused by the gas impact at the first weld 13, the housing 1 needs to have sufficient space for gas expansion and decompression. Therefore, it is necessary to control the distance between the first sidewall 11 and the electrode assembly 2.

[0050] The distance between the first sidewall 11 and the electrode assembly 2 should not be too large. If the distance between the first sidewall 11 and the electrode assembly 2 is too large, the space utilization rate of the electrode assembly 2 will be low. The distance between the first sidewall 11 and the electrode assembly 2 should not be too small. If the distance between the first sidewall 11 and the electrode assembly 2 is too small, when the electrode assembly 2 generates gas during charging and discharging, there is not enough space in the housing 1 for the gas to expand. If the gas pressure exceeds the pressure bearing capacity of the housing 1, the pressure generated by the gas will directly impact the first weld 13, thereby increasing the probability of expansion and deformation at the first weld 13 on the first sidewall 11.

[0051] The distance h between the first sidewall 11 and the electrode assembly 2 can be 3.0mm, 3.1mm, 3.2mm, 3.3mm, 3.4mm, 3.5mm, 3.6mm, 3.7mm, 3.8mm, 3.9mm, 4.0mm, 4.1mm, 4.2mm, 4.3mm, 4.5mm, 4.7mm, 4.8mm, 5.0mm, 5.2mm, 5.3mm, 5.5mm, 5.6mm, 5.7mm, 5.8mm, 5.9mm, or 6.0mm, etc. Optionally, the distance between the first weld 13 and the first center line 12 satisfies: 0 < d ≤ (0.4a) mm, and the distance between the first sidewall 11 and the electrode assembly 2 satisfies: 1.5 mm ≤ h ≤ 4 mm, and satisfies 2.5 mm ≤ h + d ≤ (0.4a + 1) mm.

[0052] The distance between the first weld 13 and the first center line 12 is 0 < d ≤ (0.4a) mm, indicating that the first weld 13 is located between the first edge 111 or the second edge 112 and the first center line 12. The first weld 13 is offset from the first center line 12. When the electrode assembly 2 generates gas during charging and discharging, the influence of the gas on the first weld 13 is reduced, and the risk of deformation of the housing 1 is reduced. At this time, the distance between the first sidewall 11 and the electrode assembly 2 can be appropriately reduced. However, the distance between the first sidewall 11 and the electrode assembly 2 cannot be too small. If the distance between the first sidewall 11 and the electrode assembly 2 is too small, when the electrode assembly 2 generates gas during charging and discharging, there is not enough space in the housing 1 for the gas to expand. If the gas pressure exceeds the pressure bearing capacity of the housing 1, the pressure generated by the gas will directly impact the first weld 13, thereby increasing the probability of expansion and deformation at the first weld 13 on the first sidewall 11.

[0053] The distance d between the first weld 13 and the first center line 12 can be (0.01a) mm, (0.03a) mm, (0.05a) mm, (0.08a) mm, (0.1a) mm, (0.12a) mm, (0.14a) mm, (0.15a) mm, (0.16a) mm, (0.18a) mm, (0.20a) mm, (0.22a) mm, (0.24a) mm, (0.25a) mm, (0.27a) mm, (0.28a) mm, (0.30a) mm, (0.32a) mm, (0.35a) mm, (0.38a) mm, or (0.40a) mm, etc.

[0054] The distance h between the first sidewall 11 and the electrode assembly 2 can be 1.5mm, 1.6mm, 1.8mm, 2.0mm, 2.2mm, 2.3mm, 2.5mm, 2.6mm, 2.7mm, 2.8mm, 2.9mm, 3.0mm, 3.1mm, 3.2mm, 3.3mm, 3.4mm, 3.5mm, 3.6mm, 3.7mm, 3.8mm, 3.9mm, or 4.0mm, etc.

[0055] Optionally, refer to Figure 4 Along the thickness direction C of the first sidewall 11, the dimension of the first sidewall 11 is e, which satisfies: 0.2mm≤e≤0.8mm, and the distance between the first sidewall 11 and the electrode assembly 2 satisfies: 1.25mm≤h≤2.5mm.

[0056] Along the thickness direction C of the first sidewall 11, the dimension of the first sidewall 11 is equal to its thickness. A larger thickness of the shell 1 results in greater strength, which in turn means a larger thickness of the first sidewall 11 leads to greater strength and a lower risk of deformation of the first weld 13 and the first sidewall 11. If the dimension of the first sidewall 11 is larger along the thickness direction C, the distance between the first sidewall 11 and the electrode assembly 2 can be reduced, thereby improving the space utilization of the electrode assembly 2. However, the thickness of the first sidewall 11 cannot be too small. If the thickness of the first sidewall 11 is too small, the strength of the first sidewall 11 and the first weld 13 will be too low, increasing the risk of expansion and deformation at the first weld 13 on the first sidewall 11.

[0057] If the thickness of the shell 1 is small, that is, the thickness of the first sidewall 11 is small, the strength of the first sidewall 11 and the first weld 13 is reduced, and the risk of expansion and deformation of the first sidewall 11 and the first weld 13 increases. If the size of the first sidewall 11 is small along the thickness direction C, sufficient space needs to be reserved between the first sidewall 11 and the electrode assembly 2 for the decompression of the gas generated by the electrode assembly 2. However, the distance between the first sidewall 11 and the electrode assembly 2 cannot be too large. If the distance between the first sidewall 11 and the electrode assembly 2 is too large, it will result in low space utilization of the electrode assembly 2. In other words, if the thickness of the first sidewall 11 is too small, the strength of the first sidewall 11 and the first weld 13 will be too low, and the risk of expansion and deformation of the first weld 13 and the first sidewall 11 will be high. In order to reduce the risk of expansion and deformation of the first weld 13 and the first sidewall 11, the distance between the first sidewall 11 and the electrode assembly 2 can only be increased, thereby reducing the space utilization of the electrode assembly 2.

[0058] Therefore, the dimension of the first sidewall 11 needs to be controlled to be 0.2mm ≤ e ≤ 0.8mm, and the dimension e of the first sidewall 11 can be 0.2mm, 0.25mm, 0.3mm, 0.35mm, 0.4mm, 0.45mm, 0.48mm, 0.5mm, 0.55mm, 0.57mm, 0.6mm, 0.65mm, 0.68mm, 0.7mm, 0.73mm, 0.75mm, 0.78mm, or 0.8mm, etc. The distance between the first sidewall 11 and the electrode assembly 2 needs to be controlled to be 1.25mm ≤ h ≤ 2.5mm, and the distance h between the first sidewall 11 and the electrode assembly 2 can be 1.25mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, 2.0mm, 2.1mm, 2.2mm, 2.3mm, 2.4mm, or 2.5mm, etc.

[0059] Optionally, along the thickness direction C of the first sidewall 11, the penetration depth of the first weld 13 is b, and the dimension of the first sidewall 11 is e, satisfying: 0.3≤b / e≤1.

[0060] The penetration depth of the first weld 13 refers to the depth to which the substrate at the first weld 13 is melted. The ratio of the penetration depth of the first weld 13 to the thickness of the first sidewall 11 is between 0.3 and 1, which can improve the strength of the casing 1 and the safety of the battery, while also improving the space utilization of the electrode assembly 2 and increasing the capacity of the battery cell.

[0061] If the ratio of the penetration depth of the first weld 13 to the thickness of the first sidewall 11 is too large, it indicates that the penetration depth of the first weld 13 is too large, thereby occupying the space that the electrode assembly 2 should occupy, making the space of the electrode assembly 2 smaller, thus reducing the capacity of the electrode assembly 2 and affecting the battery's endurance.

[0062] If the ratio of the penetration depth of the first weld 13 to the thickness of the first sidewall 11 is too small, it indicates that the penetration depth of the first weld 13 is too small, resulting in insufficient welding strength of the first sidewall 11. When the electrode assembly 2 generates internal pressure such as gas during charging and discharging, the probability of the weak first weld 13 expanding and deforming increases, and even serious problems such as weld cracking may occur, affecting the safety and service life of the battery.

[0063] The ratio b / e of the penetration depth of the first weld 13 to the thickness of the first sidewall 11 can be 0.3, 0.33, 0.35, 0.38, 0.4, 0.42, 0.45, 0.47, 0.5, 0.53, 0.56, 0.59, 0.6, 0.63, 0.65, 0.68, 0.69, 0.7, 0.72, 0.74, 0.76, 0.78, 0.8, 0.83, 0.85, 0.86, 0.89, 0.9, 0.93, 0.96, 0.98, 0.99, or 1.0, etc. Optionally, refer to Figure 4 Along the thickness direction C of the first sidewall 11, the first weld 13 protrudes from the outer surface of the first sidewall 11 by a dimension c, which satisfies: 0≤c≤0.2mm.

[0064] During the welding process, the first weld 13 will form a protrusion on the outer surface of the first sidewall 11. The first weld 13 may protrude on either side of the first sidewall 11 in the thickness direction, or it may protrude on both sides of the first sidewall 11.

[0065] If the first weld 13 protrudes from the side of the first sidewall 11 away from the electrode assembly 2, the size of the first weld 13 protruding from the outer surface of the first sidewall 11 needs to be controlled to reduce the space occupied by the battery cell, thereby reducing the gap between the battery cell and the casing after assembly and improving space utilization. If the first weld 13 protrudes from the side of the first sidewall 11 towards the electrode assembly 2, the size of the first weld 13 protruding from the outer surface of the first sidewall 11 needs to be controlled to reduce the risk of scratching the electrode assembly 2 due to the protrusion of the first weld 13, and also to reduce the gap between the electrode assembly 2 and the casing 1, thereby improving space utilization. Therefore, while meeting the welding strength requirements of the first weld 13, the size of the first weld 13 protruding from the outer surface of the first sidewall 11 needs to be controlled to reduce the impact of the first weld 13 on the battery cell installation and the electrode assembly 2.

[0066] In other words, the size of the first weld 13 protruding from the outer surface of the first sidewall 11 needs to be controlled within the range of 0 to 0.2 mm. The size c of the first weld 13 protruding from the outer surface of the first sidewall 11 can be 0, 0.01 mm, 0.02 mm, 0.03 mm, 0.04 mm, 0.05 mm, 0.06 mm, 0.07 mm, 0.08 mm, 0.09 mm, 0.1 mm, 0.11 mm, 0.12 mm, 0.13 mm, 0.14 mm, 0.15 mm, 0.16 mm, 0.17 mm, 0.18 mm, 0.19 mm, or 0.20 mm, etc.

[0067] If the first weld 13 protrudes too much on the side of the first sidewall 11 away from the electrode assembly 2, the first weld 13 will affect the assembly of the battery cell; if the first weld 13 protrudes too much on the side of the first sidewall 11 facing the electrode assembly 2, the first weld 13 may easily damage the electrode assembly 2. The size of the first weld 13 protruding from the outer surface of the first sidewall 11 cannot be too small. If the size of the first weld 13 protruding from the outer surface of the first sidewall 11 is too small, it will lead to insufficient strength of the first sidewall 11 and the first weld 13, and the first weld 13 will be prone to expansion and deformation under pressure.

[0068] Optionally, refer to Figure 1 The housing 1 also includes a second sidewall, a third sidewall 14 and a fourth sidewall. Along the thickness direction C of the first sidewall 11, the second sidewall and the first sidewall 11 are arranged opposite to each other. Along the first direction A, the third sidewall 14 and the fourth sidewall are arranged opposite to each other. Along the second direction B, one end of the first sidewall 11, the second sidewall, the third sidewall 14 and the fourth sidewall on the same side defines a first opening, and the other end on the same side defines a second opening. The first opening and the second opening communicate with the receiving cavity.

[0069] The housing 1 is constructed as a quadrangular prism. Along the second direction B, the two ends of the housing 1 are respectively provided with a first opening and a second opening. Both the first opening and the second opening are connected to the receiving cavity, and the electrode assembly 2 is received in the receiving cavity. The outer surface areas of the first sidewall 11, the second sidewall, the third sidewall 14, and the fourth sidewall can be equal, or one pair of opposite sidewalls can have a smaller outer surface area and the other pair of opposite sidewalls can have a larger outer surface area.

[0070] Optionally, refer to Figure 6 The area of ​​the outer surface of the first sidewall 11 is less than the area of ​​the outer surface of either the third sidewall 14 or the fourth sidewall, satisfying: 1.25mm≤h≤3mm.

[0071] Since the outer surface area of ​​the first sidewall 11 is smaller than that of either the third sidewall 14 or the fourth sidewall, when the electrode assembly 2 is located inside the housing 1, the stacking direction of the positive electrode, negative electrode, and separator is perpendicular to the third sidewall 14 and the fourth sidewall. Therefore, the positive electrode, negative electrode, and separator are parallel to the third sidewall 14 and the fourth sidewall. In other words, the electrode assembly 2 near the first sidewall 11 is the side where the positive electrode, negative electrode, and separator are stacked, and it is not covered by a separator. The electrode assembly 2 has multiple heat dissipation paths at the edge of this side, so even if the electrode assembly 2 generates a lot of heat and pressure, it can be dissipated in time, with little impact on the first weld 13 of the housing 1. The first weld 13 is not easily deformed, and the distance between the first sidewall 11 and the electrode assembly 2 can be reduced, thereby improving the space utilization of the electrode assembly 2.

[0072] Therefore, in order to reduce the probability of expansion and deformation of the first weld 13 and improve the space utilization of the electrode assembly 2, the distance h between the first sidewall 11 and the electrode assembly 2 needs to be controlled between 1.25mm and 3mm. The distance h between the first sidewall 11 and the electrode assembly 2 can be 1.25mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, 2.0mm, 2.1mm, 2.2mm, 2.3mm, 2.4mm, 2.5mm, 2.6mm, 2.7mm, 2.8mm, 2.9mm, or 3.0mm, etc.

[0073] Optionally, refer to Figure 5 The area of ​​the outer surface of the first sidewall 11 is greater than the area of ​​the outer surface of either the third sidewall 14 or the fourth sidewall, satisfying: 3.1mm≤h≤6mm.

[0074] Since the outer surface area of ​​the first sidewall 11 is larger than the outer surface area of ​​either the third sidewall 14 or the fourth sidewall, when the electrode assembly 2 is located inside the housing 1, the stacking direction of the positive electrode, negative electrode, and separator is perpendicular to the first sidewall 11 and the second sidewall. Therefore, the positive electrode, negative electrode, and separator are parallel to the first sidewall 11 and the second sidewall. In other words, the large surface of the separator is parallel to the first sidewall 11 and the second sidewall. This results in fewer heat dissipation paths on the side of the electrode assembly 2 facing the first sidewall 11 and the second sidewall. The high-pressure gas generated by the electrode assembly 2 is likely to affect the first weld 13 on the first sidewall 11. The first weld 13 is prone to expansion. In order to reduce the impact of the gas generated by the electrode assembly 2 on the first weld 13 and reduce the expansion deformation of the first sidewall 11, it is necessary to increase the distance between the first sidewall 11 and the electrode assembly 2, thereby reducing the space utilization rate of the electrode assembly 2.

[0075] Therefore, in order to reduce the probability of expansion and deformation of the first weld 13 and improve the space utilization of the electrode assembly 2, it is necessary to control the distance h between the first sidewall 11 and the electrode assembly 2 to be between 3.1 mm and 6 mm. The distance h between the first sidewall 11 and the electrode assembly 2 can be 3.1mm, 3.15mm, 3.2mm, 3.25mm, 3.3mm, 3.35mm, 3.4mm, 3.45mm, 3.5mm, 3.55mm, 3.6mm, 3.65mm, 3.7mm, 3.75mm, 3.8mm, 3.85mm, 3.9mm, 3.95mm, 4.0mm, 4.2mm, 4.3mm, 4.4mm, 4.5mm, 4.6mm, 4.7mm, 4.8mm, 4.9mm, 5.0mm, 5.1mm, 5.2mm, 5.3mm, 5.4mm, 5.6mm, 5.7mm, 5.8mm, 5.9mm, or 6.0mm, etc.

[0076] When the outer surface area of ​​the first sidewall 11 is smaller than either the third sidewall 14 or the fourth sidewall, the stacked electrode assembly 2 has more heat dissipation paths facing the first sidewall 11, making the housing 1 less prone to deformation. This allows for a reduction in the distance between the first sidewall 11 and the electrode assembly 2, improving the space utilization of the electrode assembly 2. When the outer surface area of ​​the first sidewall 11 is larger than either the third sidewall 14 or the fourth sidewall, the stacked electrode assembly 2 has fewer heat dissipation paths facing the first sidewall 11 due to the presence of the diaphragm, increasing the likelihood of the housing 1 expanding and deforming. To reduce this likelihood, the distance between the first sidewall 11 and the electrode assembly 2 needs to be increased. However, increasing the distance between the first sidewall 11 and the electrode assembly 2 results in a larger amount of unused space inside the housing 1, reducing the space utilization of the electrode assembly 2.

[0077] Optionally, along the second direction B, the size of the housing 1 is f, which satisfies: 80mm≤f≤600mm.

[0078] The size f of the housing 1 can be 80mm, 100mm, 120mm, 140mm, 150mm, 180mm, 200mm, 230mm, 250mm, 270mm, 280mm, 300mm, 330mm, 350mm, 360mm, 390mm, 400mm, 420mm, 440mm, 460mm, 480mm, 500mm, 520mm, 530mm, 560mm, 580mm, 590mm, or 600mm, etc.

[0079] Along the second direction B, if the size of the housing 1 is too long, the size of the electrode assembly 2 will also be large, the battery will generate more heat, and the probability of deformation of the first sidewall 11 and the first weld 13 will increase; along the second direction B, if the size of the housing 1 is too short, the size of the electrode assembly 2 will also be small, reducing the space utilization rate of the electrode assembly 2.

[0080] Optionally, the housing 1 is constructed of aluminum, satisfying the following condition: 2mm ≤ h ≤ 6mm.

[0081] The aluminum housing 1 can be made of pure aluminum or an aluminum alloy. The aluminum alloy is synthesized from aluminum and other metallic elements such as manganese, copper, magnesium, silicon, and iron in a specific ratio. The aluminum-containing housing 1 has low hardness and strength, and is prone to expansion and deformation under pressure. Therefore, it is necessary to increase the distance between the first sidewall 11 and the electrode assembly 2. However, the distance between the first sidewall 11 and the electrode assembly 2 cannot be too large, as an excessively large distance would reduce the space utilization rate of the electrode assembly 2.

[0082] Therefore, in order to reduce the probability of expansion and deformation of the housing 1 and improve the space utilization of the electrode assembly 2, it is necessary to control the distance h between the first sidewall 11 and the electrode assembly 2 to be between 2mm and 6mm. The distance h between the first sidewall 11 and the electrode assembly 2 can be 2.0mm, 2.1mm, 2.2mm, 2.3mm, 2.4mm, 2.5mm, 2.6mm, 2.7mm, 2.8mm, 2.9mm, 3.0mm, 3.1mm, 3.2mm, 3.3mm, 3.4mm, 3.5mm, 3.6mm, 3.7mm, 3.8mm, 3.9mm, 4.0mm, 4.2mm, 4.3mm, 4.4mm, 4.5mm, 4.6mm, 4.7mm, 4.8mm, 4.9mm, 5.0mm, 5.1mm, 5.2mm, 5.3mm, 5.4mm, 5.6mm, 5.7mm, 5.8mm, 5.9mm, or 6.0mm, etc.

[0083] Optionally, the shell 1 is constructed of steel, satisfying the following condition: 1.25mm≤h≤2mm.

[0084] The main materials of the steel housing 1 include stainless steel, manganese steel, and nickel-titanium alloy. Steel components have high hardness and strength, and are not easily expanded or deformed under pressure. The first sidewall 11 can be close to the electrode assembly 2, thus reducing the distance between the first sidewall 11 and the electrode assembly 2, thereby improving the utilization rate of the electrode assembly 2. The distance h between the first sidewall 11 and the electrode assembly 2 can be 1.25mm, 1.3mm, 1.35mm, 1.4mm, 1.45mm, 1.5mm, 1.6mm, 1.65mm, 1.7mm, 1.75mm, 1.8mm, 1.85mm, 1.9mm, 1.95mm, or 2.0mm, etc.

[0085] Optionally, the electrode assembly 2 is a stacked electrode assembly, satisfying the following condition: 1.25mm ≤ h ≤ 3mm. The stacked electrode assembly 2 consists of positive electrode sheets, separators, negative electrode sheets, and separators stacked alternately, or in a Z-shape. The positive and negative electrode sheets are discontinuous, resulting in multiple heat dissipation paths, making the housing 1 less prone to expansion, and the first weld less prone to expansion and deformation. Therefore, a small gap can be set between the first sidewall 11 and the electrode assembly 2. However, the gap between the first sidewall 11 and the electrode assembly 2 cannot be too small. If the gap between the first sidewall 11 and the electrode assembly 2 is too small, when the electrode assembly 2 generates high-pressure gas, there will not be enough space in the housing 1 for the gas to expand. The pressure generated by the gas will directly impact the first weld 13, thereby increasing the probability of expansion and deformation at the first weld 13 on the first sidewall 11.

[0086] Therefore, in order to reduce the probability of expansion and deformation of the housing 1 and improve the space utilization of the electrode assembly 2, the distance h between the first sidewall 11 and the electrode assembly 2 needs to be controlled between 1.25mm and 3mm. Specifically, the distance h between the first sidewall 11 and the electrode assembly 2 can be 1.25mm, 1.3mm, 1.35mm, 1.4mm, 1.45mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, 2.0mm, 2.1mm, 2.2mm, 2.3mm, 2.4mm, 2.5mm, 2.6mm, 2.7mm, 2.8mm, 2.9mm, or 3.0mm, etc.

[0087] Optionally, the electrode assembly 2 is a wound electrode assembly 2, satisfying: 3mm≤h≤6mm. The positive electrode, negative electrode, and separator of the wound electrode assembly 2 are all continuous, resulting in fewer heat dissipation paths. This makes the housing 1 more prone to expansion, meaning the first weld seam is more susceptible to expansion and deformation. Therefore, it is necessary to increase the distance between the first sidewall 11 and the electrode assembly 2 to increase the expansion space for the high-pressure gas generated by the electrode assembly 2 and reduce the expansion and deformation of the first weld seam. However, the distance between the first sidewall 11 and the electrode assembly 2 cannot be too large. If the distance is too large, it will lead to low space utilization of the electrode assembly 2.

[0088] Therefore, in order to reduce the probability of expansion and deformation of the housing 1 and improve the space utilization of the electrode assembly 2, the distance h between the first sidewall 11 and the electrode assembly 2 needs to be controlled between 3mm and 6mm. Specifically, the distance h between the first sidewall 11 and the electrode assembly 2 can be 3.0mm, 3.1mm, 3.2mm, 3.3mm, 3.4mm, 3.5mm, 3.6mm, 3.7mm, 3.8mm, 3.9mm, 4.0mm, 4.2mm, 4.3mm, 4.4mm, 4.5mm, 4.6mm, 4.7mm, 4.8mm, 4.9mm, 5.0mm, 5.1mm, 5.2mm, 5.3mm, 5.4mm, 5.6mm, 5.7mm, 5.8mm, 5.9mm, or 6.0mm, etc.

[0089] Secondly, embodiments of this application provide a battery pack comprising the battery cells described in any of the above embodiments.

[0090] The battery pack proposed in this application embodiment has the beneficial effects of the battery cell as described in the first aspect above. Specifically, the distance between the first weld 13 and the first center line 12 along the first direction A is d, and the distance between the first sidewall 11 and the electrode assembly 2 along the thickness direction C of the first sidewall 11 is h. By adjusting the spacing between the first weld 13 and the first center line 12, and the spacing between the first sidewall 11 and the electrode assembly 2, the expansion deformation of the housing 1 is reduced. If h+d is too large, it indicates that the distance h between the electrode assembly 2 and the first sidewall 11 is too large, and the spacing between the first weld 13 and the first center line 12 is also too large. The space utilization rate of the electrode assembly 2 is low, and the welding strength is poor because the first weld 13 is too close to the first edge 111 or the second edge 112. If h+d is too small, it indicates that the distance between the electrode assembly 2 and the first sidewall 11 is too small, and the distance between the first weld 13 and the first center line 12 is also too small. The gas generated by the charging and discharging of the electrode assembly 2 does not have enough space to expand, and the gas pressure exceeds the pressure bearing capacity of the shell 1. Furthermore, the first weld 13, as a weak area, is too close to the first center line 12, resulting in a large pressure impact on the first sidewall 11 and the first weld 13. Since the strength of the first weld 13 is lower than that of other areas of the first sidewall 11, it is prone to expansion and deformation, which further increases the risk of the first sidewall 11 expanding and deforming at the first weld 13, and reduces the safety performance of the battery cell.

[0091] Therefore, it is necessary to control 2mm≤h+d≤(a / 2+1)mm so that the distance between the first sidewall 11 and the electrode assembly 2 and the spacing between the first weld 13 and the first center line 12 meet the strength requirements, reduce the expansion deformation at the first weld 13 on the first sidewall 11, and thus improve the safety performance of the battery cell.

[0092] Thirdly, embodiments of this application provide an electrical device, including a battery cell or battery pack as described in any of the above embodiments. This application utilizes the provided electrical device, which has the beneficial effects of the battery cell provided in the first aspect or the battery pack provided in the second aspect, as will not be elaborated further here.

[0093] In this application, the maximum range of the distance d between the first weld 13 and the first center line 12 is 0 to (a / 2) mm, the maximum range of the distance h between the first sidewall 11 and the electrode assembly 2 is 1.25 mm to 6 mm, the maximum range of the width a of the first side is 10 mm to 100 mm, and the maximum range of d+h is 2 mm to (a / 2+1) mm. The preferred range of the distance d between the first weld 13 and the first center line 12 is 0 to (0.4a) mm, the maximum range of the distance h between the first sidewall 11 and the electrode assembly 2 is 1.5 mm to 4 mm, the maximum range of the width a of the first side is 20 mm to 80 mm, and the maximum range of d+h is 2.5 mm to (0.4a+1) mm.

[0094] Space utilization is obtained by calculating the dimension of the electrode assembly in one direction divided by the maximum external dimension of the battery cell in the corresponding direction. Space utilization in the second direction = dimension of the electrode assembly in the second direction / dimension of the battery cell in the second direction; Space utilization in the first sidewall thickness direction = dimension of the electrode assembly in the first sidewall thickness direction / dimension of the battery cell in the first sidewall thickness direction; Space utilization in the first direction = dimension of the electrode assembly in the first direction / dimension of the battery cell in the first direction; Total utilization = Space utilization in the first direction * Space utilization in the second direction * Space utilization in the first sidewall thickness direction. It should be understood that because the separator is transparent, it is difficult to directly photograph the dimensions of the electrode assembly; therefore, the dimensions of the electrode assembly can be characterized by photographing the dimensions of the negative electrode sheet.

[0095] The deformation of shell 1 was tested through the following cyclic performance test: The lithium-ion batteries prepared in Examples 1 to 11 and Comparative Examples 1 and 2 were subjected to cycle tests at 45°C according to the following procedure: 1) Charge at a constant current rate of 1C to 3.65V, and then charge at a constant voltage until the current drops to 0.05C; 2) Let it stand for 30 minutes; 3) Discharge to 2.5V at a 1C rate; 4) Let it stand for 30 minutes. Perform the cyclic test according to steps 1) to 4), with a total of 300 cycles.

[0096] In this application, a measurement reference line is selected on the first sidewall 11. The distance between the measurement reference line and the first edge 111 or the second edge 112 is 1.5±0.5mm. After the battery is tested according to the above-mentioned charge and discharge cycle test, the deformation height of the first sidewall 11 at the measurement reference line and the deformation height at the first weld 13 are measured. The maximum value of the difference between the deformation height at the measurement reference line and the first weld 13 is the measured deformation of the shell.

[0097] Among them, the optimal space utilization rate is 88.1%–94%, the qualified rate is 82.1%–88%, and the unqualified rate is 78%–82%.

[0098] The optimal deformation range for housing 1 indicates that the deformation of housing 1 is between 0 and 2 mm; the acceptable deformation range for housing 1 indicates that the deformation of housing 1 is between 2.1 and 4 mm; and the unacceptable deformation range for housing 1 indicates that the deformation of housing 1 is greater than 4 mm.

[0099] Taking a width 'a' of 60mm for the first side as an example, the maximum range of the distance 'd' between the first weld 13 and the first center line 12 is 0–30mm; the maximum range of the distance 'h' between the first sidewall 11 and the electrode assembly 2 is 1.25mm–6mm; the maximum range of 'd+h' is 2mm–31mm; the preferred range of the distance 'd' between the first weld 13 and the first center line 12 is 0–24mm; the preferred range of the distance 'h' between the first sidewall 11 and the electrode assembly 2 is 1.5mm–4mm; and the preferred range of 'd+h' is 2.5mm–25mm. This data range was used to test the space utilization of the electrode assembly and the deformation of the housing. Specific test data are shown in Table 1. Table 1 In Examples 1 to 6, the value of d+h is within the preferred range of this application, the distance d between the first weld 13 and the first center line 12 is within the range of this application, the distance h between the first sidewall 11 and the electrode assembly 2 is within the range of this application, and the deformation of the shell 1 and the space utilization rate of the electrode assembly 2 are both qualified or above.

[0100] In Example 7, the value of d+h is the lower limit of the preferred range of this application. The distance d between the first weld 13 and the first center line 12 meets the preferred range. The distance h between the first sidewall 11 and the electrode assembly 2 is the lower limit of the preferred range of this application. Therefore, the deformation of the shell 1 is qualified and the space utilization rate of the electrode assembly 2 is optimal.

[0101] In Example 8, the distance d between the first weld 13 and the first center line 12 is 0, but the value of d+h is within the preferred range. The distance h between the first sidewall 11 and the electrode assembly 2 is 4.6 mm. The deformation of the shell 1 is at the optimal level, and the space utilization of the electrode assembly 2 is qualified. This shows that even if the first weld 13 coincides with the first center line 12, as long as the distance h between the first sidewall 11 and the electrode assembly 2 is sufficient for the gas expansion generated by the electrode assembly 2 and meets the range of d+h in this application, the deformation of the shell 1 and the space utilization of the electrode assembly 2 are also qualified.

[0102] In Embodiment 9, even if the distance h between the first sidewall 11 and the electrode assembly 2 is 1.1 mm, which exceeds the lower limit of the maximum range of this application, the value of d+h is within the maximum range of this application, and the distance d between the first weld 13 and the first center line 12 meets the preferred range, then the deformation of the shell 1 and the space utilization of the electrode assembly 2 are both qualified.

[0103] In Example 10, the distance d between the first weld 13 and the first center line 12 is 29.8 mm. The first weld 13 is close to the first edge 111 or the second edge 112, but the value of d+h is within the maximum range. Even though the distance h between the first sidewall 11 and the electrode assembly 2 is small, at 1.1 mm, the deformation of the shell 1 and the space utilization of the electrode assembly 2 are both qualified.

[0104] In Comparative Example 1, the distance d between the first weld 13 and the first center line 12 is 0, and the value of d+h exceeds the lower limit of the maximum range. The distance h between the first sidewall 11 and the electrode assembly 2 is 1.25 mm. Although the space utilization rate of the electrode assembly 2 is optimal, the gas pressure generated during charging and discharging of the electrode assembly 2 does not have enough expansion space. The gas directly impacts the first weld 13, resulting in an unqualified deformation of the shell 1. This shows that even if the distance d between the first weld 13 and the first center line 12 and the distance h between the first sidewall 11 and the electrode assembly 2 are within the range of this application, the value of d+h in Comparative Example 1 exceeds the lower limit of the range of d+h in this application. This indicates that the first weld 13 is too close to the first center line 12, and the distance between the first sidewall 11 and the electrode assembly 2 is too small. As a result, the gas pressure generated by the electrode assembly 2 does not have enough expansion space, and the gas pressure directly impacts the first weld, resulting in a large deformation of the shell 1 and low space utilization of the electrode assembly 2.

[0105] In Comparative Example 2, the first weld 13 is located at either the first edge 111 or the second edge 112. The value of d+h exceeds the upper limit of the maximum range. Even though the distance h between the first sidewall 11 and the electrode assembly 2 and the distance d between the first weld 13 and the first centerline 12 are both within the maximum range, the deformation of the shell 1 and the space utilization of the electrode assembly 2 are still unqualified. The reason is that the first weld 13 is the furthest from the first centerline 12. Due to the high welding difficulty, the welding strength is poor, and the shell 1 is prone to deformation. The first sidewall 11 needs to be far away from the electrode assembly 2 to provide space for gas expansion, which results in the deformation of the shell 1 and the space utilization of the electrode assembly 2 being unqualified.

[0106] Taking a width 'a' of 30mm for the first side as an example, the maximum range of the distance 'd' between the first weld 13 and the first center line 12 is 0–15mm; the maximum range of the distance 'h' between the first sidewall 11 and the electrode assembly 2 is 1.25mm–6mm; the maximum range of 'd+h' is 2mm–16mm; the preferred range of the distance 'd' between the first weld 13 and the first center line 12 is 0–12mm; the preferred range of the distance 'h' between the first sidewall 11 and the electrode assembly 2 is 1.5mm–4mm; and the preferred range of 'd+h' is 2.5mm–13mm. This data range was used to test the space utilization of the electrode assembly and the deformation of the housing. Specific test data are shown in Table 2. Table 2 In Examples 1 to 7, the value of d+h is within the preferred range of this application, the distance d between the first weld 13 and the first center line 12 is within the range of this application, the distance h between the first sidewall 11 and the electrode assembly 2 is within the range of this application, and the deformation of the shell 1 and the space utilization rate of the electrode assembly 2 are both qualified.

[0107] In Example 8, the distance d between the first weld 13 and the first center line 12 is 0, but the value of d+h is within the preferred range. The distance h between the first sidewall 11 and the electrode assembly 2 is 4.6 mm. The deformation of the shell 1 and the space utilization of the electrode assembly 2 are both qualified. This shows that even if the first weld 13 coincides with the first center line 12, as long as the distance h between the first sidewall 11 and the electrode assembly 2 is sufficient for the gas expansion generated by the electrode assembly 2 and meets the range of d+h in this application, the deformation of the shell 1 and the space utilization of the electrode assembly 2 also meet the requirements.

[0108] In Example 9, even though the distance h between the first sidewall 11 and the electrode assembly 2 is 1.2 mm, which exceeds the lower limit of the maximum range of this application, the value of d+h is within the maximum range of this application, and the distance d between the first weld 13 and the first center line 12 meets the preferred range, then the deformation of the shell 1 and the space utilization of the electrode assembly 2 are both qualified.

[0109] In Example 10, the distance d between the first weld 13 and the first center line 12 is 14.9 mm. The first weld 13 is close to the first edge 111 or the second edge 112, but the value of d+h is within the maximum range. Even though the distance h between the first sidewall 11 and the electrode assembly 2 is small, at 1.1 mm, the deformation of the shell 1 and the space utilization of the electrode assembly 2 are both qualified.

[0110] In Comparative Example 1, the distance d between the first weld 13 and the first center line 12 is 0, and the value of d+h exceeds the lower limit of the maximum range. The distance h between the first sidewall 11 and the electrode assembly 2 is 1.3 mm. Although the space utilization rate of the electrode assembly 2 is optimal, the gas pressure generated during charging and discharging of the electrode assembly 2 does not have enough expansion space. The gas directly impacts the first weld 13, resulting in an unqualified deformation of the shell 1. This shows that even if the distance d between the first weld 13 and the first center line 12 and the distance h between the first sidewall 11 and the electrode assembly 2 are within the range of this application, the value of d+h in Comparative Example 1 exceeds the lower limit of the range of d+h in this application. This indicates that the first weld 13 is too close to the first center line 12, and the distance between the first sidewall 11 and the electrode assembly 2 is too small. As a result, the gas pressure generated by the electrode assembly 2 does not have enough expansion space, and the gas pressure directly impacts the first weld, resulting in a large deformation of the shell 1 and low space utilization of the electrode assembly 2.

[0111] In Comparative Example 2, the first weld 13 is located at either the first edge 111 or the second edge 112. The value of d+h exceeds the upper limit of the maximum range. Even though the distance h between the first sidewall 11 and the electrode assembly 2 and the distance between the first weld 13 and the first centerline 12 are both within the maximum range, the deformation of the shell 1 and the space utilization of the electrode assembly 2 are still unqualified. The reason is that the first weld 13 is the furthest from the first centerline 12. Due to the high welding difficulty, the welding strength is poor, and the shell 1 is prone to deformation. The first sidewall 11 needs to be far away from the electrode assembly 2 to provide space for gas expansion, which results in the deformation of the shell 1 and the space utilization of the electrode assembly 2 being unqualified.

[0112] The experimental data in Tables 1 and 2 demonstrate that even if the first weld 13 is close to the first centerline 12, the high-pressure gas can easily impact the first weld 13 during the charging and discharging process of the battery 2. However, as long as the distance between the first sidewall 11 and the electrode assembly 2 is appropriate and the d+h range is within the scope of this application, there is sufficient space between the first sidewall 11 and the electrode assembly 2 for gas expansion, which can reduce the impact of the gas on the first sidewall 11 and the first weld 13, thereby reducing the deformation of the first sidewall 11. Furthermore, the electrode assembly 2 has a high space utilization rate.

[0113] Even if the distance between the first sidewall 11 and the electrode assembly 2 is small, the gas generated during the charging and discharging process of the battery 2 cannot expand well. However, as long as the distance d between the first weld 13 and the first center line 12 is controlled and the range of d+h is controlled within the scope of this application, the high-pressure gas does not directly impact the first weld 13, thereby reducing the deformation of the first weld 13 and the first sidewall 11, and the electrode assembly 2 has a high space utilization rate.

[0114] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0115] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to interchangeably. Each embodiment focuses on describing the differences from other embodiments. In particular, the system embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments.

[0116] The above description is merely an embodiment of this application and is not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

[0117] Although embodiments of this application have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of this application, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A battery cell, characterized in that, include: A housing defining a receiving cavity, the housing having a first sidewall along a first direction, the first sidewall having a first edge and a second edge, the first sidewall having a first weld and a first centerline extending along a second direction, the distance between the first centerline and the first edge being equal to the distance between the first centerline and the second edge, the first direction, the second direction and the thickness direction of the first sidewall being perpendicular to each other; The electrode assembly is disposed within the receiving cavity; Wherein, along the first direction, the dimension of the first sidewall is a, satisfying: 10mm≤a≤100mm, the distance between the first weld and the first center line is d, and along the thickness direction of the first sidewall, the distance between the first sidewall and the electrode assembly is h, satisfying: 2mm≤h+d≤(a / 2+1)mm; The housing further includes a second sidewall, a third sidewall, and a fourth sidewall. Along the thickness direction of the first sidewall, the second sidewall and the first sidewall are disposed opposite to each other. Along the first direction, the third sidewall and the fourth sidewall are disposed opposite to each other. Along the second direction, one end of the first sidewall, the second sidewall, the third sidewall, and the fourth sidewall on the same side defines a first opening, and the other end on the same side defines a second opening. The first opening and the second opening communicate with the receiving cavity. The area of ​​the outer surface of the first sidewall is smaller than the area of ​​the outer surface of either the third or the fourth sidewall, satisfying: 1.25mm≤h≤3mm.

2. The battery cell according to claim 1, characterized in that, The distance between the first weld and the first center line satisfies: 0 < d ≤ (0.4a) mm, and the distance between the first sidewall and the electrode assembly satisfies: 1.5 mm ≤ h ≤ 3 mm, and 2.5 mm ≤ h + d ≤ (0.4a + 1) mm.

3. The battery cell according to claim 1, characterized in that, Along the thickness direction of the first sidewall, the dimension of the first sidewall is e, which satisfies: 0.2mm≤e≤0.8mm, and the distance between the first sidewall and the electrode assembly satisfies: 1.25mm≤h≤2.5mm.

4. The battery cell according to claim 1, characterized in that, Along the thickness direction of the first sidewall, the penetration depth of the first weld is b, and the dimension of the first sidewall is e, satisfying: 0.3≤b / e≤1.

5. The battery cell according to claim 4, characterized in that, Along the thickness direction of the first sidewall, the first weld protrudes from the outer surface of the first sidewall by a dimension c, satisfying: 0≤c≤0.2mm.

6. The battery cell according to claim 1, characterized in that, Along the second direction, the size of the shell is f, which satisfies: 80mm≤f≤600mm.

7. The battery cell according to claim 1, characterized in that, The shell structure is made of aluminum and satisfies the following condition: 2mm≤h≤3mm.

8. The battery cell according to claim 1, characterized in that, The shell structure is made of steel and satisfies the following condition: 1.25mm≤h≤2mm.

9. The battery cell according to claim 1, characterized in that, The electrode assembly is a stacked electrode assembly, satisfying the following condition: 1.25mm≤h≤3mm.

10. A battery pack, characterized in that, Includes the battery cell described in any one of claims 1-9.

11. An electrical appliance, characterized in that, Includes the battery cell as described in any one of claims 1-9 or the battery pack as described in claim 10.

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