Battery monomer, battery pack and electric equipment

Abstract

The invention relates to the technical field of batteries, in particular to a battery monomer, a battery pack and electric equipment. The battery monomer comprises a shell and an electrode assembly, the shell defines a containing cavity, the shell is provided with a first side wall, the first side wall is provided with a first edge and a second edge in the first direction, and the first side wall is provided with a first welding seam extending in the second direction and a first center line; the distance between the first center line and the first edge is equal to the distance between the first center line and the second edge, and the first direction, the second direction and the thickness direction of the first side wall are perpendicular to each other; the electrode assembly is arranged in the accommodating cavity; wherein in the first direction, the size of the first side wall is a, the distance between the first welding seam and the first center line is d, in the thickness direction of the first side wall, the distance between the first side wall and the electrode assembly is h, and h + d is larger than or equal to 2mm and smaller than or equal to (a / 2 + 1) mm. The probability of expansion deformation of the shell is reduced.

Description

Technical Field

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

[0002] Currently, when battery cases are long, they are formed by first bending or rolling the case and then butt-welding one side. This is typically done by fusion welding the case base material, resulting in weld strength that is weaker than the base material. When the gas generated within the electrode assembly exceeds the pressure tolerance of the case, the case will deform, and the weaker welds may rupture, compromising battery safety. Summary of the Invention

[0003] The present application provides a battery cell, a battery pack, and an electrical device, which reduce the probability of expansion and deformation of the shell.

[0004] In order to achieve the above objectives, the main technical solutions adopted in this application include:

[0005] In a first aspect, an embodiment of the present application provides a battery cell, comprising a shell and an electrode assembly, the shell defining a accommodating cavity, the shell having a first side wall, and along a first direction, the first side wall having a first edge and a second edge, the first side wall having a first weld and a first center line extending along a second direction, the distance between the first center line and the first edge is equal to the distance between the first center line and the second edge, the first direction, the second direction and the thickness direction of the first side wall are perpendicular to each other; the electrode assembly is arranged in the accommodating cavity; wherein, along the first direction, the dimension of the first side wall 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 side wall, the distance between the first side wall and the electrode assembly is h, satisfying: 2mm≤h+d≤(a / 2+1)mm.

[0006] In the battery cell proposed in the embodiments of the present application, the distance d between the first weld and the first centerline along the first direction, and the distance h between the first sidewall and the electrode assembly along the thickness direction of the first sidewall, are adjusted to reduce expansion deformation of the housing. 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 distance between the first weld and the first centerline is also too large, resulting in low space utilization of the electrode assembly. Furthermore, because the first weld is too close to the first edge or the second edge, the weld strength is poor. If h+d is too small, it means that the distance between the electrode assembly and the first side wall is too small, and the distance between the first weld and the first center line is also too small. The gas generated during 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 range of the shell. The first weld, as a weak area, is too close to the first center line, causing the gas accumulated inside the shell to impact the first side wall and the first weld during charging and discharging of the battery. Since the strength of the first weld is lower than that of other areas of the first side wall, it is prone to expansion and deformation, further increasing the risk of expansion and deformation of the first side wall at the first weld, and reducing the safety performance of the battery cell.

[0007] Therefore, it is necessary to control 2mm≤h+d≤(a / 2+1)mm so that the distance between the first side wall 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 side wall, and thus improve the safety performance of the battery cell.

[0008] In a second aspect, an embodiment of the present application provides a battery pack comprising the battery cell described in any of the above embodiments.

[0009] The battery pack proposed in the embodiment of the present application includes a battery cell and has the same beneficial effects as the battery cell.

[0010] In a third aspect, embodiments of the present application provide an electrical device comprising a battery cell or battery pack as described in any of the above embodiments.

[0011] The electrical equipment proposed in the embodiment of the present application includes a battery cell or a battery pack, and therefore has the same beneficial effects as a battery cell or a battery pack. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the specific implementation methods or the description of the prior art. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0013] Figure 1 This is a schematic diagram of the structure of the battery cell of this application;

[0014] Figure 2 This is a schematic structural diagram of a battery cell in one embodiment of the present application;

[0015] Figure 3 for Figure 2 Cross-sectional view of the middle DD section;

[0016] Figure 4 for Figure 3 Enlarged view of area F in the middle;

[0017] Figure 5 This is a schematic structural diagram of a battery cell in another embodiment of the present application;

[0018] Figure 6 This is a schematic structural diagram of a battery cell in another embodiment of the present application.

[0019] [Description of Reference Numerals]

[0020] 1: housing; 11: first side wall; 111: first edge; 112: second edge; 12: first center line; 13: first weld; 14: third side wall;

[0021] 2: Electrode assembly;

[0022] A: first direction; B: second direction; C: thickness direction of the first side wall. DETAILED DESCRIPTION

[0023] To make the purpose, technical solutions, and advantages of the embodiments of the present application more clear, the technical solutions 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, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative efforts shall fall within the scope of protection of this application.

[0024] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned drawings are intended to cover non-exclusive inclusions. The terms "first" and "second" in the specification and claims of this application or the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order or a primary-secondary relationship.

[0025] References to "embodiments" in this application mean that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described in this application may be combined with other embodiments.

[0026] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connected," and "attached" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to direct connections, indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0027] The term "and / or" in this application simply describes an association between related objects, indicating that three possible relationships exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this application generally indicates that the related objects are in an "or" relationship.

[0028] The term "multiple" in this application refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0029] 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 recharged to activate the active material after the battery is discharged and continue to be used.

[0030] Typically, a secondary battery includes an electrode assembly, an electrolyte, and an outer packaging shell. The electrode assembly includes a positive electrode sheet, a negative electrode sheet, and a separator. The electrode assembly and the electrolyte are assembled in the outer packaging shell. During the battery charging and discharging process, active ions (such as lithium ions) are embedded and released back and forth between the positive electrode sheet and the negative electrode sheet. The separator is set between the positive electrode sheet and the negative electrode sheet, mainly to prevent the positive and negative electrodes from short-circuiting, while allowing active ions to pass through. The electrolyte between the positive electrode sheet and the negative electrode sheet mainly plays the role of conducting active ions.

[0031] As an example, the preparation process of a secondary battery is as follows: stack the positive electrode sheet, separator, and negative electrode sheet in order, so that the separator is placed between the positive and negative electrode sheets to act as an isolate, and then wind or stack them to obtain an electrode assembly; place the electrode assembly in an outer packaging shell, inject the electrolyte after drying, and obtain a secondary battery through vacuum packaging, standing, formation, shaping and other processes.

[0032] The positive electrode sheet generally includes a positive electrode current collector and a positive electrode film layer arranged on at least one side of the positive electrode current collector. The positive electrode film layer includes a positive electrode active material, which can be any positive electrode active material disclosed in the prior art or a positive electrode active material optimized on the basis of the prior art.

[0033] In some embodiments, the positive electrode sheet can be prepared by the following method: the components for preparing the positive electrode sheet, such as the positive electrode active material, the conductive agent, the binder and any other components, are dispersed in a solvent (for example, N-methylpyrrolidone) to form a positive electrode slurry; the positive electrode slurry is coated on the positive electrode current collector, and after drying, rolling, cutting and other processes, the positive electrode sheet can be obtained.

[0034] The binder is used to improve the adhesion between the positive electrode active material particles and the adhesion between the positive electrode active material and the current collector. The binder can 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.

[0035] The positive electrode current collector of the present application can be made of, for example, stainless steel, aluminum, nickel, titanium, fired carbon, or aluminum or stainless steel that has been surface-treated with one of carbon, nickel, titanium, silver, etc.

[0036] 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. For example, the silicon-based material may be one or more of a silicon-carbon composite negative electrode material, a silicon oxide negative electrode material, a modified silicon oxide negative electrode material, or a nano-silicon material. 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.

[0037] In some embodiments, the negative electrode sheet can be prepared by the following method: the components for preparing the negative electrode sheet, such as the negative electrode active material, the conductive agent, the binder and any other components, are dispersed in a solvent (such as water) to form a negative electrode slurry; the negative electrode slurry is coated on the negative electrode current collector, and after drying, rolling, cutting and other processes, the negative electrode sheet can be obtained.

[0038] In some embodiments, as an example, the negative electrode conductive agent can be one or more conventional negative electrode conductive agents such as acetylene black and carbon nanotubes; as an example, the binder can be one or more conventional negative electrode binders such as styrene-butadiene rubber latex (SBR), polyvinylidene fluoride (PVDF), polyacrylic acid (PAA), sodium carboxymethyl cellulose (CMC), etc.

[0039] In some embodiments, as an example, the negative electrode current collector may be one of conventional negative electrode current collectors such as copper foil.

[0040] The electrolyte plays the role of conducting ions between the positive electrode sheet and the negative electrode sheet. As an example, the electrolyte of the present application can be various electrolytes suitable for electrochemical energy storage devices in the art. The electrolyte includes an electrolyte and a solvent. The electrolyte can generally include a lithium salt, and additives can 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 difluorooxalatoborate (LiDFOB), lithium dioxalatoborate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluorobis(oxalatophosphate) (LiDFOP) and lithium tetrafluorooxalatophosphate (LiTFOP). The concentration of the electrolyte in the electrolyte can be 0.5 to 5 mol / L. The solvent includes at least one of ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene 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), ethyl methyl sulfone (EMS) and diethyl sulfone (ESE).

[0041] In some embodiments, as examples, the additive may be conventional electrolyte additives such as fluoroethylene carbonate (FEC), chloroethylene carbonate (CEC), and vinylene carbonate (VC).

[0042] In some embodiments, the secondary battery further includes a separator. For example, the separator may be made of PP, PE, or PP / PF. Alternatively, the separator may be a structure having a coating provided on the surface of a base film. The base film coating may be made of PP, PE, or PP / PF, and the coating may be an inorganic coating and / or an organic coating. The inorganic coating may be selected from alumina ceramic layers, borax, and the like, and the organic coating may be selected from PVDF and the like.

[0043] Currently, when the gas generated inside the electrode assembly exceeds the pressure tolerance of the casing, the gas will first impact the middle area of the casing sidewall. Because the weld is located in the middle area of the casing and the spacing between the electrode assembly and the casing sidewall is small, the gas generated inside the electrode assembly does not have enough space to expand, exerting greater pressure on the sidewall, making the weld more likely to expand, deform, or even break, affecting the safety performance of the battery. Therefore, it is necessary to control the location of the weld and the spacing between the casing sidewall and the electrode assembly.

[0044] In view of this, the present application provides a battery cell, a battery pack and an electrical device, which can reduce the expansion and deformation of the shell and improve the safety performance of the battery cell.

[0045] First, reference Figures 1 to 6 , an embodiment of the present application provides a battery cell, the battery shell 1 includes a shell 1 and an electrode assembly 2, the shell 1 defines an accommodating cavity, the shell 1 has a first side wall 11, along a first direction A, the first side wall 11 has a first edge 111 and a second edge 112, the first side wall 11 has a first weld 13 and a first center line 12 extending along a second direction B, the distance between the first center line 12 and the first edge 111 is equal to the distance between the first center line 12 and the second edge 112, the first direction A, the second direction B and the thickness direction C of the first side wall 11 are perpendicular to each other; the electrode assembly 2 is arranged in the accommodating cavity; wherein, along the first direction A, the dimension of the first side wall 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 side wall 11, the distance between the first side wall 11 and the electrode assembly 2 is h, satisfying: 2mm≤h+d≤(a / 2+1)mm.

[0046] Specifically, the first direction A is the width direction of the first side wall 11, and the second direction B is the length direction of the second side wall. The shell 1 has multiple side walls, and the multiple side walls enclose an accommodating cavity, and the electrode assembly 2 is arranged in the accommodating cavity. The first weld 13 is provided on the first side wall 11, and the first weld 13 extends along the second direction B. The first weld 13 can be located between the first center line 12 and the first edge 111 or the first weld 13 is located between the second center line and the second edge 112. Of course, the first weld 13 can also coincide with the first center line 12. Along the first direction A, the distance between the first center line 12 and the first edge 111 is equal to the distance between the first center line 12 and the second edge 112.

[0047] In the battery cell proposed in the embodiment of the present application, the distance d between the first weld 13 and the first centerline 12 along the first direction A, and the distance h between the first sidewall 11 and the electrode assembly 2 along the thickness direction C of the first sidewall 11, is adjusted. By adjusting the spacing between the first weld 13 and the first centerline 12, as well as the spacing between the first sidewall 11 and the electrode assembly 2, expansion deformation of the housing 1 is reduced. If h + d is too large, it means 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 centerline 12 is also too large, resulting in low space utilization of the electrode assembly 2. Furthermore, because the first weld 13 is too close to the first edge 111 or the second edge 112, the weld strength is poor. If h+d is too small, it means that the distance between the electrode assembly 2 and the first side wall 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, and the gas generated by the electrode assembly exceeds the pressure bearing range of the shell. In addition, the first weld 13, as a weak area, is too close to the first center line 12, causing the gas pressure accumulated inside the shell during charging and discharging of the battery to impact the first side wall 11 and the first weld 13. Since the strength of the first weld 13 is lower than that of other areas of the first side wall 11, it is prone to expansion and deformation, further increasing the risk of expansion and deformation of the first side wall 11 at the first weld 13, thereby reducing the safety performance of the battery cell.

[0048] Therefore, it is necessary to control 2mm≤h+d≤(a / 2+1)mm so that the distance between the first side wall 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 side wall 11, and thus improve the safety performance of the battery cell.

[0049] It should be understood that in order to reduce the phenomenon of misalignment of the positive and negative electrode sheets due to the same size of the positive and negative electrode sheets, the size of the negative electrode sheet in the electrode assembly 2 in this application is larger than that of the positive electrode sheet. Because the electrode assembly 2 is wrapped with a white separator, it is not easy to measure the distance between the first side wall 11 and the electrode assembly 2. Therefore, this application can measure the distance between the first side wall 11 and the negative electrode sheet along the thickness direction C of the first side wall 11.

[0050] Along the first direction A, a dimension a of the first side wall 11 satisfies: 10 mm ≤ a ≤ 100 mm. The dimension of the first side wall 11 may be 10 mm, 15 mm, 16 mm, 20 mm, 25 mm, 30 mm, 35 mm, 40 mm, 45 mm, 50 mm, 55 mm, 60 mm, 65 mm, 70 mm, 75 mm, 80 mm, 85 mm, 90 mm, 95 mm, 98 mm, or 100 mm, etc.

[0051] 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 side wall 11 and the electrode assembly 2 satisfies: 1.25 mm≤h≤6 mm.

[0052] The distance between the first weld 13 and the first center line 12 cannot 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, and the welding strength will be poor; the distance between the first weld 13 and the first center line 12 cannot be too small. 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 electrode assembly 2 generates gas that exceeds the pressure tolerance range 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 side wall 11.

[0053] The distance d between the first weld 13 and the first center line 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, (0 .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.

[0054] The distance between the first side wall 11 and the electrode assembly 2 cannot be too large. If the distance between the first side wall 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 side wall 11 and the electrode assembly 2 cannot be too small. If the distance between the first side wall 11 and the electrode assembly 2 is too small, the electrode assembly 2 will generate gas during charging and discharging, and there will not be enough space in the shell 1 for the gas to expand. The gas pressure exceeds the pressure bearing range of the shell 1, and 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 side wall 11.

[0055] Among them, the distance h between the first side wall 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.

[0056] Optionally, refer to Figures 3 and 4 The first weld 13 coincides with the first center line 12 , and the distance between the first side wall 11 and the electrode assembly 2 satisfies: 3 mm ≤ h ≤ 6 mm.

[0057] If first weld 13 coincides with first centerline 12, then first weld 13 acts as a weak area. When electrode assembly 2 generates gas during charging and discharging, the gas pressure exceeds the pressure tolerance of housing 1, directly impacting first weld 13 with the gas and causing it to expand and deform. To minimize deformation caused by gas impact at first weld 13, sufficient space within housing 1 is required for gas expansion and decompression. Therefore, the distance between first sidewall 11 and electrode assembly 2 must be controlled.

[0058] The distance between the first side wall 11 and the electrode assembly 2 cannot be too large. If the distance between the first side wall 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 side wall 11 and the electrode assembly 2 cannot be too small. If the distance between the first side wall 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 shell 1 for the gas to expand, and the gas pressure exceeds the pressure bearing range of the shell 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 side wall 11.

[0059] The distance h between the first side wall 11 and the electrode assembly 2 can be 3.0 mm, 3.1 mm, 3.2 mm, 3.3 mm, 3.4 mm, 3.5 mm, 3.6 mm, 3.7 mm, 3.8 mm, 3.9 mm, 4.0 mm, 4.1 mm, 4.2 mm, 4.3 mm, 4.5 mm, 4.7 mm, 4.8 mm, 5.0 mm, 5.2 mm, 5.3 mm, 5.5 mm, 5.6 mm, 5.7 mm, 5.8 mm, 5.9 mm or 6.0 mm, etc.

[0060] 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 side wall 11 and the electrode assembly 2 satisfies: 1.5mm≤h≤4mm, and satisfies 2.5mm≤h+d≤(0.4a+1)mm.

[0061] The distance between the first weld 13 and the first center line 12 is 0<d≤(0.4a)mm, which means 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 deviates from the first center line 12. When the electrode assembly 2 generates gas during charging and discharging, the effect of the gas on the first weld 13 is reduced, and the risk of deformation of the shell 1 is reduced. At this time, the distance between the first side wall 11 and the electrode assembly 2 can be appropriately reduced. However, the distance between the first side wall 11 and the electrode assembly 2 cannot be too small. If the distance between the first side wall 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 shell 1 for the gas to expand. The gas pressure exceeds the pressure tolerance range of the shell 1, and 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 side wall 11.

[0062] Among them, 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.

[0063] Among them, the distance h between the first side wall 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.

[0064] Optionally, refer to Figure 4 Along the thickness direction C of the first side wall 11 , the dimension of the first side wall 11 is e, which satisfies: 0.2 mm ≤ e ≤ 0.8 mm, and the distance between the first side wall 11 and the electrode assembly 2 satisfies: 1.25 mm ≤ h ≤ 2.5 mm.

[0065] Along the thickness direction C of the first side wall 11, the dimension of the first side wall 11 is the thickness of the first side wall 11. The greater the thickness of the shell 1, the greater the strength of the shell 1, that is, the greater the thickness of the first side wall 11, the greater the strength of the first side wall 11, and the smaller the risk of deformation of the first weld 13 and the first side wall 11. If the dimension of the first side wall 11 along the thickness direction C of the first side wall 11 is larger, the distance between the first side wall 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 side wall 11 cannot be too small. If the thickness of the first side wall 11 is too small, the strength of the first side wall 11 and the first weld 13 will be too low, and the risk of expansion and deformation at the first weld 13 on the first side wall 11 will increase.

[0066] If the thickness of the shell 1 is small, that is, the thickness of the first side wall 11 is small, the strength of the first side wall 11 and the first weld 13 is reduced, and the risk of expansion and deformation of the first side wall 11 and the first weld 13 is increased. If the size of the first side wall 11 along the thickness direction C of the first side wall 11 is small, sufficient space needs to be reserved between the first side wall 11 and the electrode assembly 2 to reduce the pressure of the gas generated by the electrode assembly 2. However, the distance between the first side wall 11 and the electrode assembly 2 cannot be too large. If the distance between the first side wall 11 and the electrode assembly 2 is too large, the space utilization rate of the electrode assembly 2 will be low. In other words, if the thickness of the first side wall 11 is too small, the strength of the first side wall 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 side wall 11 will be high. In order to reduce the risk of expansion and deformation of the first weld 13 and the first side wall 11, the distance between the first side wall 11 and the electrode assembly 2 can only be increased, thereby reducing the space utilization rate of the electrode assembly 2.

[0067] Therefore, it is necessary to control the size of the first side wall 11 to be 0.2 mm ≤ e ≤ 0.8 mm, and the size e of the first side wall 11 can be 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, 0.45 mm, 0.48 mm, 0.5 mm, 0.55 mm, 0.57 mm, 0.6 mm, 0.65 mm, 0.68 mm, 0.7 mm, 0.73 mm, 0.75 mm, 0.78 mm, or 0.8 mm, etc. It is necessary to control the distance between the first side wall 11 and the electrode assembly 2 to be 1.25 mm ≤ h ≤ 2.5 mm, and the distance h between the first side wall 11 and the electrode assembly 2 can be 1.25 mm, 1.3 mm, 1.4 mm, 1.5 mm, 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm, 2.0 mm, 2.1 mm, 2.2 mm, 2.3 mm, 2.4 mm, or 2.5 mm, etc.

[0068] Optionally, along the thickness direction C of the first side wall 11 , the penetration of the first weld 13 is b, and the size of the first side wall 11 is e, satisfying: 0.3≤b / e≤1.

[0069] The penetration depth of the first weld 13 refers to the depth to which the base material is melted at the first weld 13. 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. This improves the strength of the housing 1 and battery safety while also increasing the space utilization of the electrode assembly 2 and the capacity of the battery cells.

[0070] If the ratio of the penetration depth of the first weld 13 to the thickness of the first side wall 11 is too large, it means 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, and further reducing the capacity of the electrode assembly 2, affecting the battery life.

[0071] If the ratio of the penetration depth of the first weld 13 to the thickness of the first side wall 11 is too small, it means that the penetration depth of the first weld 13 is too small, resulting in insufficient welding strength of the first side wall 11. When internal pressure such as gas is generated during the charging and discharging process of the electrode assembly 2, the probability of expansion and deformation of the first weld 13 with insufficient strength increases, and even serious problems such as weld cracking may occur, affecting the safety and service life of the battery.

[0072] The ratio b / e of the penetration depth of the first weld 13 to the thickness of the first side wall 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.

[0073] Optionally, refer to Figure 4 Along the thickness direction C of the first side wall 11 , the dimension of the first weld 13 protruding from the outer surface of the first side wall 11 is c, satisfying: 0≤c≤0.2mm.

[0074] During the welding process, the first weld 13 will form a bulge on the first side wall 11 that protrudes from the outer surface of the first side wall 11, wherein the first weld 13 can protrude only on either side of the first side wall 11 in the thickness direction, or can protrude on both sides of the first side wall 11.

[0075] If the first weld 13 protrudes on the side of the first side wall 11 away from the electrode assembly 2, it is necessary to control the size of the first weld 13 protruding from the outer surface of the first side wall 11 to reduce the space occupied by the battery cell, thereby reducing the gap between the battery cell and the shell after the battery cell is assembled, thereby improving space utilization. If the first weld 13 protrudes on the side of the first side wall 11 toward the electrode assembly 2, it is necessary to control the size of the first weld 13 protruding from the outer surface of the first side wall 11 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 shell 1, thereby improving space utilization. Therefore, it is necessary to control the size of the first weld 13 protruding from the outer surface of the first side wall 11 while meeting the welding strength of the first weld 13, so as to reduce the impact of the first weld 13 on the installation of the battery cell and the electrode assembly 2.

[0076] That is to say, it is necessary to control the size of the first weld 13 protruding from the outer surface of the first side wall 11 to be 0 to 0.2 mm, wherein the size c of the first weld 13 protruding from the outer surface of the first side wall 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.

[0077] If the first weld 13 protrudes too much from the side of the first sidewall 11 facing 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 from the side of the first sidewall 11 facing the electrode assembly 2, the first weld 13 may easily damage the electrode assembly 2. The protrusion of the first weld 13 from the outer surface of the first sidewall 11 cannot be too small. If the protrusion of the first weld 13 from the outer surface of the first sidewall 11 is too small, the strength of the first sidewall 11 and the first weld 13 will be insufficient, and the first weld 13 will be easily compressed, expanded and deformed.

[0078] Optionally, refer to Figure 1 The shell 1 also includes a second side wall, a third side wall 14 and a fourth side wall. Along the thickness direction C of the first side wall 11, the second side wall and the first side wall 11 are arranged opposite to each other. Along the first direction A, the third side wall 14 and the fourth side wall are arranged opposite to each other. Along the second direction B, the first side wall 11, the second side wall, the third side wall 14 and the fourth side wall define a first opening at one end on the same side and a second opening at the other end on the same side. The first opening and the second opening are connected to the accommodating cavity.

[0079] The housing 1 is constructed as a quadrangular prism. A first opening and a second opening are respectively provided at both ends of the housing 1 along the second direction B. The first opening and the second opening are both connected to the housing cavity, and the electrode assembly 2 is accommodated within the housing 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 the outer surface areas of one pair of opposing sidewalls can be smaller, while the outer surface areas of the other pair of opposing sidewalls can be larger.

[0080] Optionally, refer to Figure 6 The area of the outer surface of the first side wall 11 is smaller than the area of the outer surface of any one of the third side wall 14 and the fourth side wall, and satisfies: 1.25 mm ≤ h ≤ 3 mm.

[0081] Since the outer surface of the first side wall 11 is smaller than the outer surface area of any of the third side wall 14 and the fourth side wall, when the electrode assembly 2 is located in the shell 1, the stacking direction of the positive electrode sheet, the negative electrode sheet and the separator is perpendicular to the third side wall 14 and the fourth side wall, and therefore the positive electrode sheet, the negative electrode sheet and the separator are parallel to the third side wall 14 and the fourth side wall. In other words, the electrode assembly 2 close to the first side wall 11 is the side where the positive electrode sheet, the negative electrode sheet and the separator are stacked, and is not covered by the separator. The electrode assembly 2 has multiple heat dissipation paths at the edge of this side. Even if the electrode assembly 2 generates large heat and pressure, it can be dissipated in time, with little impact on the first weld 13 of the shell 1. The first weld 13 is not easily deformed. At this time, the distance between the first side wall 11 and the electrode assembly 2 can be reduced, thereby improving the space utilization of the electrode assembly 2.

[0082] 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 spacing h between the first side wall 11 and the electrode assembly 2 to be between 1.25 mm and 3 mm. The spacing h between the first side wall 11 and the electrode assembly 2 can be 1.25 mm, 1.3 mm, 1.4 mm, 1.5 mm, 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm, 2.0 mm, 2.1 mm, 2.2 mm, 2.3 mm, 2.4 mm, 2.5 mm, 2.6 mm, 2.7 mm, 2.8 mm, 2.9 mm or 3.0 mm, etc.

[0083] Optionally, refer to Figure 5 The area of the outer surface of the first side wall 11 is greater than the area of the outer surface of any one of the third side wall 14 and the fourth side wall, and satisfies: 3.1 mm ≤ h ≤ 6 mm.

[0084] Since the outer surface of the first side wall 11 is larger than the outer surface area of any one of the third side wall 14 and the fourth side wall, when the electrode assembly 2 is located in the shell 1, the stacking direction of the positive electrode sheet, the negative electrode sheet and the diaphragm is perpendicular to the first side wall 11 and the second side wall. Therefore, the positive electrode sheet, the negative electrode sheet and the diaphragm are parallel to the first side wall 11 and the second side wall. That is, the large surface of the diaphragm is parallel to the first side wall 11 and the second side wall, which results in less heat dissipation path on the side of the electrode assembly 2 facing the first side wall 11 and the second side wall. The high-pressure gas generated by the electrode assembly 2 can easily affect the first weld 13 on the first side wall 11, and the first weld 13 can easily expand. 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 side wall 11, it is necessary to increase the distance between the first side wall 11 and the electrode assembly 2, thereby reducing the space utilization rate of the electrode assembly 2.

[0085] 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 side wall 11 and the electrode assembly 2 to be between 3.1 mm and 6 mm. Among them, the spacing h between the first side wall 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.

[0086] When the outer surface area of the first side wall 11 is smaller than that of either the third side wall 14 or the fourth side wall, the side of the laminated electrode assembly 2 facing the first side wall 11 has more heat dissipation paths, the housing 1 is less likely to deform, and the spacing between the first side wall 11 and the electrode assembly 2 can be reduced, thereby improving the space utilization of the electrode assembly 2. When the outer surface area of the first side wall 11 is larger than that of either the third side wall 14 or the fourth side wall, the side of the laminated electrode assembly 2 facing the first side wall 11 has fewer heat dissipation paths due to the presence of the diaphragm, thereby increasing the probability of expansion and deformation of the housing 1. To reduce the probability of expansion and deformation of the housing 1, it is necessary to increase the spacing between the first side wall 11 and the electrode assembly 2. However, increasing the spacing between the first side wall 11 and the electrode assembly 2 will result in a larger free space within the housing 1, thereby reducing the space utilization of the electrode assembly 2.

[0087] Optionally, along the second direction B, the size of the housing 1 is f, satisfying: 80 mm ≤ f ≤ 600 mm.

[0088] Among them, the size f of the shell 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.

[0089] Along the second direction B, if the size of the shell 1 is too long, the size of the electrode assembly 2 is also large, the heat generated by the battery is also more, and the probability of deformation of the first side wall 11 and the first weld 13 increases; along the second direction B, if the size of the shell 1 is too short, the size of the electrode assembly 2 is also small, which reduces the space utilization of the electrode assembly 2.

[0090] Optionally, the housing 1 is constructed as an aluminum part, satisfying the following: 2 mm ≤ h ≤ 6 mm.

[0091] The aluminum housing 1 can be made of pure aluminum or an aluminum alloy. Aluminum alloys are composed of aluminum and other metal elements, such as manganese, copper, magnesium, silicon, and iron, in a specific proportion. Aluminum-based housings 1 have low hardness and strength, and are prone to expansion and deformation under pressure. Therefore, it is necessary to increase the spacing between the first sidewall 11 and the electrode assembly 2. However, the spacing between the first sidewall 11 and the electrode assembly 2 should not be too large. Excessive spacing between the first sidewall 11 and the electrode assembly 2 reduces the space utilization of the electrode assembly 2.

[0092] Therefore, in order to reduce the probability of expansion and deformation of the shell 1 and improve the space utilization of the electrode assembly 2, it is necessary to control the distance h between the first side wall 11 and the electrode assembly 2 to be between 2 mm and 6 mm. Among them, the spacing h between the first side wall 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.

[0093] Optionally, the housing 1 is constructed of steel, satisfying the following: 1.25 mm ≤ h ≤ 2 mm.

[0094] The main materials of the steel shell 1 include stainless steel, manganese steel, and nickel-titanium alloy. The steel material has high hardness and strength, and is not easy to expand and deform under pressure. The first side wall 11 can be close to the electrode assembly 2, that is, the distance between the first side wall 11 and the electrode assembly 2 is reduced, thereby improving the utilization rate of the electrode assembly 2. Among them, the distance h between the first side wall 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.

[0095] Optionally, the electrode assembly 2 is a laminated electrode assembly that satisfies the following conditions: 1.25mm≤h≤3mm. The laminated electrode assembly 2 is a stack of positive electrode sheets, diaphragms, negative electrode sheets, and diaphragms alternately stacked one by one, or stacked in a Z-shape. The positive electrode sheets and negative electrode sheets are discontinuous, and there are many heat dissipation paths. The shell 1 is not easy to expand, and the first weld print is not easy to expand and deform. Therefore, a smaller spacing can be set between the first side wall 11 and the electrode assembly 2. However, the spacing between the first side wall 11 and the electrode assembly 2 cannot be too small. If the spacing between the first side wall 11 and the electrode assembly 2 is too small, when the electrode assembly 2 generates high-pressure gas, there is not enough space in the shell 1 for the gas to expand, and 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 side wall 11.

[0096] 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 side wall 11 and the electrode assembly 2 to be between 1.25 mm and 3 mm. The distance h between the first side wall 11 and the electrode assembly 2 can be 1.25 mm, 1.3 mm, 1.35 mm, 1.4 mm, 1.45 mm, 1.5 mm, 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm, 2.0 mm, 2.1 mm, 2.2 mm, 2.3 mm, 2.4 mm, 2.5 mm, 2.6 mm, 2.7 mm, 2.8 mm, 2.9 mm or 3.0 mm, etc.

[0097] Optionally, the electrode assembly 2 is a wound electrode assembly 2 that satisfies the following conditions: 3mm≤h≤6mm. The positive electrode sheet, negative electrode sheet, and separator of the wound electrode assembly 2 are all continuous, resulting in fewer heat dissipation paths. The housing 1 is more susceptible to expansion, meaning that the first weld mark is susceptible to expansion and deformation. Therefore, it is necessary to increase the spacing between the first side wall 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 mark. However, the spacing between the first side wall 11 and the electrode assembly 2 cannot be too large. If the spacing between the first side wall 11 and the electrode assembly 2 is too large, the space utilization rate of the electrode assembly 2 will be low.

[0098] 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 side wall 11 and the electrode assembly 2 to be between 3 mm and 6 mm. The distance h between the first side wall 11 and the electrode assembly 2 can be 3.0 mm, 3.1 mm, 3.2 mm, 3.3 mm, 3.4 mm, 3.5 mm, 3.6 mm, 3.7 mm, 3.8 mm, 3.9 mm, 4.0 mm, 4.2 mm, 4.3 mm, 4.4 mm, 4.5 mm, 4.6 mm, 4.7 mm, 4.8 mm, 4.9 mm, 5.0 mm, 5.1 mm, 5.2 mm, 5.3 mm, 5.4 mm, 5.6 mm, 5.7 mm, 5.8 mm, 5.9 mm or 6.0 mm, etc.

[0099] In a second aspect, an embodiment of the present application provides a battery pack comprising the battery cell described in any of the above embodiments.

[0100] The battery pack proposed in the embodiment of the present application has the beneficial effects of the battery cell of the first aspect described above, specifically: along the first direction A, the distance between the first weld 13 and the first centerline 12 is d, and along the thickness direction C of the first side wall 11, the distance between the first side wall 11 and the electrode assembly 2 is h. By adjusting the spacing between the first weld 13 and the first centerline 12, and the spacing between the first side wall 11 and the electrode assembly 2, the expansion deformation of the housing 1 is reduced. If h + d is too large, it means that the distance h between the electrode assembly 2 and the first side wall 11 is too large, and the spacing between the first weld 13 and the first centerline 12 is also too large, resulting in low space utilization of the electrode assembly 2. In addition, because the first weld 13 is too close to the first edge 111 or the second edge 112, the welding strength is poor. If h+d is too small, it means that the distance between the electrode assembly 2 and the first side wall 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 range of the shell 1. In addition, 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 side wall 11 and the first weld 13. Since the strength of the first weld 13 is lower than that of other areas of the first side wall 11, it is prone to expansion and deformation, further increasing the risk of expansion and deformation of the first side wall 11 at the first weld 13, thereby reducing the safety performance of the battery cell.

[0101] Therefore, it is necessary to control 2mm≤h+d≤(a / 2+1)mm so that the distance between the first side wall 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 side wall 11, and thus improve the safety performance of the battery cell.

[0102] In a third aspect, embodiments of the present application provide an electrical device comprising a battery cell or battery pack as described in any of the above embodiments. This application utilizes the provided electrical device and has the beneficial effects of the battery cell provided in the first aspect or the battery pack provided in the second aspect, which will not be further elaborated here.

[0103] In the present application, the maximum range of the spacing d between the first weld 13 and the first centerline 12 is 0 to (a / 2) mm, the maximum range of the spacing 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 surface 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 spacing d between the first weld 13 and the first centerline 12 is 0 to (0.4a) mm, the maximum range of the spacing 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 surface is 20 mm to 80 mm, and the maximum range of d+h is 2.5 mm to (0.4a+1) mm.

[0104] The space utilization ratio is calculated by dividing the electrode assembly dimensions in one direction by the maximum external dimensions of the battery cell in the corresponding direction. The space utilization ratio in the second direction = the electrode assembly dimensions in the second direction / the battery cell dimensions in the second direction; the space utilization ratio in the first sidewall thickness direction = the electrode assembly dimensions in the first sidewall thickness direction / the battery cell dimensions in the first sidewall thickness direction; the space utilization ratio in the first direction = the electrode assembly dimensions in the first direction / the battery cell dimensions in the first direction; and the total utilization ratio = the space utilization ratio in the first direction * the space utilization ratio in the second direction * the space utilization ratio in the first sidewall thickness direction. It should be understood that since 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 represented by photographing the dimensions of the negative electrode sheet.

[0105] The deformation of the shell 1 is tested by the following cyclic performance test:

[0106] At 45° C., the lithium-ion batteries prepared in Examples 1 to 11 and Comparative Examples 1 and 2 were subjected to cycle testing according to the following procedure:

[0107] 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;

[0108] 2) Let it sit for 30 minutes;

[0109] 3) Discharge at a rate of 1C to 2.5V;

[0110] 4) Let it sit for 30 minutes.

[0111] Perform a cyclic test according to steps 1) to 4) with a total of 300 cycles.

[0112] In this application, a measurement reference line is selected on the first side wall 11, and 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, the deformation height of the first side wall 11 at the measurement reference line and the deformation height at the first weld 13 are measured. The maximum value of the deformation height difference between the measurement reference line and the first weld 13 is the measured deformation of the shell.

[0113] Among them, the optimal space utilization rate is 88.1% to 94%, the qualified rate is 82.1% to 88%, and the unqualified rate is 78% to 82%.

[0114] The optimal deformation of the shell 1 indicates that the deformation of the shell 1 is between 0 and 2 mm, the qualified deformation of the shell 1 indicates that the deformation of the shell 1 is between 2.1 and 4 mm, and the unqualified deformation of the shell 1 indicates that the deformation of the shell 1 is greater than 4 mm.

[0115] Taking the width a of the first side as 60mm as an example, the maximum range of the spacing d between the first weld 13 and the first center line 12 is 0-30mm, the maximum range of the spacing h between the first side wall 11 and the electrode assembly 2 is 1.25mm-6mm, and the maximum range of d+h is 2mm-31mm. The preferred range of the spacing d between the first weld 13 and the first center line 12 is 0-24mm, the preferred range of the spacing h between the first side wall 11 and the electrode assembly 2 is 1.5mm-4mm, and the preferred range of d+h is 2.5mm-25mm. This data range is used to test the space utilization of the electrode assembly and the deformation of the shell. The specific test data are shown in Table 1:

[0116] Table 1

[0117]

[0118] In Examples 1 to 6, the value of d+h is within the preferred range of the present application, the distance d between the first weld 13 and the first center line 12 is within the range of the present application, the distance h between the first side wall 11 and the electrode assembly 2 is within the range of the present application, and the deformation of the shell 1 and the space utilization rate of the electrode assembly 2 are both qualified or above.

[0119] The value of d+h in Example 7 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, and the distance h between the first side wall 11 and the electrode assembly 2 is the lower limit of the preferred range of this application. Then, the deformation of the shell 1 is qualified, and the space utilization rate of the electrode assembly 2 is optimal.

[0120] 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 side wall 11 and the electrode assembly 2 is 4.6 mm, the deformation of the shell 1 is optimal, and the space utilization of the electrode assembly 2 is qualified. This means that even if the first weld 13 coincides with the first center line 12, as long as the distance h between the first side wall 11 and the electrode assembly 2 is sufficient for the expansion of the gas 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.

[0121] In Example 9, even though the spacing h between the first side wall 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 spacing 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 rate of the electrode assembly 2 are both qualified.

[0122] In Example 10, the distance d between the first weld 13 and the first center line 12 is 29.8 mm, and 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 if the distance h between the first side wall 11 and the electrode assembly 2 is small, at 1.1 mm, the deformation of the shell 1 and the space utilization rate of the electrode assembly 2 are both qualified.

[0123] In Comparative Example 1, the spacing d between the first weld 13 and the first centerline 12 is 0, and the value of d+h exceeds the lower limit of the maximum range. The spacing 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 by the electrode assembly 2 during charging and discharging does not have enough space to expand, and the gas directly impacts the first weld 13, resulting in an unqualified deformation of the shell 1. This shows that even though the spacing d between the first weld 13 and the first centerline 12 and the spacing h between the first sidewall 11 and the electrode assembly 2 are both 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, indicating that the first weld 13 is too close to the first centerline 12 and the spacing between the first sidewall 11 and the electrode assembly 2 is too small, resulting in insufficient space for the gas pressure generated by the electrode assembly 2 to expand. 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.

[0124] In Comparative Example 2, the first weld 13 is located at the first edge 111 or the second edge 112, and the value of d + h exceeds the upper limit of the maximum range. Even though the spacing h between the first sidewall 11 and the electrode assembly 2 and the spacing d between the first weld 13 and the first centerline 12 are both within the maximum range, the deformation of the housing 1 and the space utilization of the electrode assembly 2 are both unqualified. This is because the first weld 13 is located farthest from the first centerline 12. Due to the difficulty of welding, the welding strength is poor, which makes the housing 1 prone to deformation. This requires the first sidewall 11 to be away from the electrode assembly 2 to provide space for gas expansion, resulting in unqualified deformation of the housing 1 and space utilization of the electrode assembly 2.

[0125] Taking the width a of the first side as 30mm as an example, the maximum range of the spacing d between the first weld 13 and the first center line 12 is 0-15mm, the maximum range of the spacing h between the first side wall 11 and the electrode assembly 2 is 1.25mm-6mm, and the maximum range of d+h is 2mm-16mm. The preferred range of the spacing d between the first weld 13 and the first center line 12 is 0-12mm, the preferred range of the spacing h between the first side wall 11 and the electrode assembly 2 is 1.5mm-4mm, and the preferred range of d+h is 2.5mm-13mm. This data range is used to test the space utilization of the electrode assembly and the deformation of the shell. The specific test data are shown in Table 2:

[0126] Table 2

[0127]

[0128] In Examples 1 to 7, the value of d+h is within the preferred range of the present application, the distance d between the first weld 13 and the first center line 12 is within the range of the present application, the distance h between the first side wall 11 and the electrode assembly 2 is within the range of the present application, and the deformation of the shell 1 and the space utilization rate of the electrode assembly 2 are both qualified.

[0129] 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 side wall 11 and the electrode assembly 2 is 4.6 mm, and the deformation of the shell 1 and the space utilization rate of the electrode assembly 2 are both qualified. This means that even if the first weld 13 coincides with the first center line 12, as long as the distance h between the first side wall 11 and the electrode assembly 2 is sufficient for the expansion of the gas 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 rate of the electrode assembly 2 also meet the requirements.

[0130] In Example 9, even though the spacing h between the first side wall 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 spacing 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 rate of the electrode assembly 2 are both qualified.

[0131] In Example 10, the distance d between the first weld 13 and the first center line 12 is 14.9 mm, and 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 if the distance h between the first side wall 11 and the electrode assembly 2 is small, at 1.1 mm, the deformation of the shell 1 and the space utilization rate of the electrode assembly 2 are both qualified.

[0132] In Comparative Example 1, the spacing d between the first weld 13 and the first centerline 12 is 0, and the value of d+h exceeds the lower limit of the maximum range. The spacing 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 by the electrode assembly 2 during charging and discharging does not have enough space to expand, and the gas directly impacts the first weld 13, resulting in an unqualified deformation of the shell 1. This shows that even though the spacing d between the first weld 13 and the first centerline 12 and the spacing h between the first sidewall 11 and the electrode assembly 2 are both 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, indicating that the first weld 13 is too close to the first centerline 12 and the spacing between the first sidewall 11 and the electrode assembly 2 is too small, resulting in insufficient space for the gas pressure generated by the electrode assembly 2 to expand. 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.

[0133] In Comparative Example 2, the first weld 13 is located at the first edge 111 or the second edge 112, and the value of d + h exceeds the upper limit of the maximum range. Even though the spacing h between the first sidewall 11 and the electrode assembly 2 and the spacing between the first weld 13 and the first centerline 12 are both within the maximum range, the deformation of the housing 1 and the space utilization of the electrode assembly 2 are both unqualified. This is because the first weld 13 is located farthest from the first centerline 12. Due to the difficulty of welding, the welding strength is poor, which makes the housing 1 prone to deformation. This requires the first sidewall 11 to be away from the electrode assembly 2 to provide space for gas expansion, resulting in unqualified deformation of the housing 1 and space utilization of the electrode assembly 2.

[0134] The experimental data in Tables 1 and 2 prove that even if the first weld 13 is close to the first center line 12, 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 spacing between the first side wall 11 and the electrode assembly 2 is appropriate and the d+h range is within the scope of this application, there is enough space between the first side wall 11 and the electrode assembly 2 for gas expansion, which can also reduce the impact of the gas on the first side wall 11 and the first weld 13, thereby reducing the deformation of the first side wall 11, and the electrode assembly 2 has a higher space utilization rate.

[0135] Even if the distance between the first side wall 11 and the electrode assembly 2 is small, the gas generated during the charging and discharging process of the battery 2 cannot expand well, but 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 side wall 11, and the electrode assembly 2 has a higher space utilization rate.

[0136] It should also be noted that the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, commodity, or apparatus that includes a series of elements includes not only those elements but also other elements not explicitly listed, or includes elements inherent to such process, method, commodity, or apparatus. In the absence of further limitations, an element defined by the phrase "comprises a ..." does not exclude the presence of other identical elements in the process, method, commodity, or apparatus that includes the element.

[0137] The various embodiments in this specification are described in a progressive manner. Similar parts between the various embodiments can be referred to in conjunction with each other. Each embodiment focuses on the differences between the other embodiments. In particular, the system embodiments are generally similar to the method embodiments, so the description is relatively simple. For relevant parts, refer to the description of the method embodiments.

[0138] The foregoing is merely an embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application should all be included within the scope of the claims of the present application.

[0139] Although the embodiments of the present application have been described with reference to the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present application, and such modifications and variations shall fall within the scope defined by the appended claims.

Claims

1. A battery cell, characterized in that: include: A housing defines a receiving cavity, the housing having a first sidewall, the first sidewall having a first edge and a second edge along a first direction, 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, and the first direction, the second direction, and a thickness direction of the first sidewall being perpendicular to each other; an electrode assembly, disposed in the accommodating cavity; Among them, along the first direction, the size of the first side wall 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 side wall, the distance between the first side wall and the electrode assembly is h, satisfying: 2mm≤h+d≤(a / 2+1)mm.

2. The battery cell according to claim 1, wherein: The distance between the first weld and the first center line satisfies: 0≤d<(a / 2)mm, and the distance between the first side wall and the electrode assembly satisfies: 1.25mm≤h≤6mm.

3. The battery cell according to claim 1, wherein: The first weld coincides with the first center line, and the distance between the first side wall and the electrode assembly satisfies: 3 mm ≤ h ≤ 6 mm.

4. The battery cell according to claim 1, wherein: The distance between the first weld and the first center line satisfies: 0<d≤(0.4a)mm, the distance between the first side wall and the electrode assembly satisfies: 1.5mm≤h≤4mm, and satisfies 2.5mm≤h+d≤(0.4a+1)mm.

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

6. The battery cell according to claim 1, characterized in that Along the thickness direction of the first side wall, the penetration depth of the first weld is b, and the dimension of the first side wall is e, which satisfies: 0.3≤b / e≤1.

7. The battery cell according to claim 6, characterized in that Along the thickness direction of the first side wall, a dimension c of the first weld protruding from the outer surface of the first side wall satisfies: 0≤c≤0.2 mm.

8. The battery cell according to claim 1, wherein: The shell also includes a second side wall, a third side wall and a fourth side wall. Along the thickness direction of the first side wall, the second side wall and the first side wall are arranged opposite to each other. Along the first direction, the third side wall and the fourth side wall are arranged opposite to each other. Along the second direction, the first side wall, the second side wall, the third side wall and the fourth side wall define a first opening at one end on the same side and a second opening at the other end on the same side. The first opening and the second opening are connected to the accommodating cavity.

9. The battery cell according to claim 8, characterized in that The area of the outer surface of the first side wall is smaller than the area of the outer surface of any one of the third side wall and the fourth side wall, and satisfies: 1.25 mm ≤ h ≤ 3 mm.

10. The battery cell according to claim 8, characterized in that The area of the outer surface of the first side wall is greater than the area of the outer surface of any one of the third side wall and the fourth side wall, and satisfies: 3.1 mm≤h≤6 mm.

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

12. The battery cell according to claim 1, wherein The shell is constructed of aluminum and satisfies the following requirements: 2mm≤h≤6mm.

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

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

15. The battery cell according to claim 1, characterized in that The electrode assembly is a wound electrode assembly, satisfying: 3mm≤h≤6mm.

16. A battery pack, characterized in that: The battery cell comprises the battery cell according to any one of claims 1 to 15.

17. An electrical device, characterized in that: Comprising the battery cell according to any one of claims 1 to 15 or the battery pack according to claim 16.

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