Battery and electric device comprising battery

Abstract

The present application relates to the technical field of batteries, and more specifically relates to a battery and an electric device comprising the battery. The battery comprises a housing, and a battery cell arranged in the housing, wherein the material of the housing comprises steel, the components of which comprise Ti, Nb and Cr, the mass percentage of Cr being equal to or greater than 16 wt.% based on the total mass of the steel; the housing comprises a side wall and end walls, the end walls comprising a first end wall and a second end wall located at two ends of the side wall, and two ends of the battery cell comprise a first end surface close to the first end wall and a second end surface close to the second end wall; and the housing satisfies the following relational expression: 0.15≤a / [d×(b+c)]≤300. By means of controlling the relationship among the sum a of the distances between end walls at two ends of a housing and end faces at two ends of a battery cell, the thickness d of a first end wall, and the contents b and c of Ti and Nb, the present application balances the formability of the housing during a forming process and the ability of the housing to resist the risk of deformation caused by the expansion of the battery cell.

Description

A battery and an electrical device including the battery

[0001] Cross-reference of related applications

[0002] This application claims priority to Chinese Patent Application No. 202411556208.1, filed on November 4, 2024, entitled “A Battery and an Electrical Device Including the Battery”, the entire contents of which are incorporated herein by reference. Technical Field

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

[0004] The battery casing not only serves as a physical protective barrier, preventing internal components from being affected by external environmental factors (such as humidity, dust, and vibration), but also ensures battery safety during use. Battery casings are typically made of materials with sufficient strength, corrosion resistance, and insulation properties to meet the battery's requirements in various operating environments. Battery safety is particularly crucial for power batteries used in new energy vehicles.

[0005] Currently, deep drawing is one of the important forming methods for manufacturing battery casings. It utilizes the plasticity of metal materials, stretching and deforming them under specific pressure conditions to create the desired shape. Deep drawing is widely used in automotive manufacturing, aerospace, and electronic equipment industries due to its advantages such as high processing efficiency, low cost, and stable quality.

[0006] To ensure the processing performance of metals during deep drawing, the material needs a certain degree of ductility and plastic deformation capability. However, the shell thickness decreases after deep drawing, and the high plastic deformation capability of the material increases the risk of deformation of the formed shell, thus affecting battery safety. This is especially true when manufacturing battery shells through deep drawing, as the expansion of the cells inside the shell during charging and discharging further increases the risk of shell deformation. Increasing the thickness of the battery shell to improve its strength may increase battery cost and weight, thus reducing the battery's energy density. Summary of the Invention

[0007] The purpose of this application is to overcome the shortcomings of the prior art in balancing the three performance aspects of casing molding and processing performance, casing resistance to deformation risk caused by cell expansion, and battery energy density, and to provide a battery and an electrical device including the battery.

[0008] To achieve the above objectives, in a first aspect of this application, a battery is provided, comprising a casing and a battery cell disposed within the casing. The casing is made of steel, and the steel composition includes Ti, Nb, and Cr, wherein, based on the total mass of the steel, the mass percentage of Cr is ≥16 wt.%. The casing includes sidewalls and endwalls, the endwalls including a first endwall and a second endwall located at both ends of the sidewalls. The battery cell has a first end face near the first endwall and a second end face near the second endwall at both ends. The first endwall is integrally formed with the sidewalls.

[0009] The shell satisfies the following relationship: 0.15≤a / [d×(b+c)]≤300;

[0010] Where 'a' is the sum of the distance from the first end face to the first end wall and the distance from the second end face to the second end wall, in mm;

[0011] d is the thickness of the first end wall, in mm;

[0012] b represents the mass percentage of Ti based on the total mass of the steel, expressed in wt.%.

[0013] c represents the mass percentage of Nb based on the total mass of steel, expressed in wt.%.

[0014] As an optional implementation of this application, the shell satisfies the following relationship: 1≤a / [d×(b+c)]≤200.

[0015] As an optional embodiment of this application, the range of b+c is 0.2-0.8 wt.%.

[0016] As an optional embodiment of this application, the range of b+c is 0.25-0.5 wt.%.

[0017] As an optional embodiment of this application, the range of b is 0.05-0.2 wt.%.

[0018] As an optional embodiment of this application, the range of c is 0.17-0.5 wt.%.

[0019] As an optional implementation of this application, the range of d is 0.15-1.2 mm.

[0020] As an optional implementation of this application, the range of 'a' is 0.1-10 mm.

[0021] As an optional embodiment of this application, the battery is a cylindrical battery.

[0022] As an optional implementation of this application, the range of 'a' is 0.5-10 mm.

[0023] As an optional embodiment of this application, the battery cell is provided with a winding hole, and the battery satisfies the following relationship: 0.4≤S×a≤600;

[0024] Where S is the area of ​​the core hole, in mm. 2 .

[0025] As an optional embodiment of this application, the battery is a tetragonal prism battery.

[0026] As an optional implementation of this application, the range of 'a' is 0.1-8 mm.

[0027] As an optional embodiment of this application, when the aspect ratio of the shell is not less than 2, the range of b+c is 0.2-0.7 wt.%.

[0028] As an optional embodiment of this application, the battery cell includes a positive electrode tab and a negative electrode tab, which are electrically connected to the casing, and the Cr content is 16-30 wt.%.

[0029] As an optional implementation of this application, both the positive electrode tab and the negative electrode tab are disposed on the first end face or the second end face of the battery cell, and the range of a is 0.5-10mm.

[0030] As an optional implementation of this application, the positive electrode tab and the negative electrode tab are respectively disposed on the first end face and the second end face of the battery cell, and the range of a is 0.2-8mm.

[0031] An electrical device comprising the battery as described above.

[0032] The beneficial effects of this application are as follows:

[0033] This application balances the processing performance of the casing during molding with its ability to resist deformation risks caused by cell expansion by controlling the sum of distances *a* between the end walls at both ends of the casing and the end faces at both ends of the cell, the thickness *d* of the first end wall, and the contents of Ti and Nb, *b* and *c*. This makes the casing easy to deep-draw and form, while also providing a certain degree of resistance to deformation after molding, preventing casing deformation caused by cell expansion during charging and discharging, thus ensuring battery safety. Simultaneously, it ensures that the battery's energy density is not too low, avoiding excessively large values ​​of *a* or *d* to reduce the risk of casing deformation, which would lead to a decrease in battery energy density. Attached Figure Description

[0034] Figure 1 is a schematic diagram of the overall structure of the shell in Embodiment 1;

[0035] Figure 2 is a schematic diagram of the internal structure of the shell in Embodiment 1;

[0036] Figure 3 is a schematic diagram of the overall structure of the shell in Example 29.

[0037] The markings in the diagram are explained as follows: 1-Housing, 11-First end wall, 12-Second end wall, 13-Side wall, 2-Battery cell, 21-Core hole. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0039] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0040] In this application, numerical ranges are referred to as continuous unless otherwise specified, and include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0041] Unless otherwise specified, all reagents or instruments used in this application are commercially available products.

[0042] One embodiment of this application provides a battery, including a casing 1 and a battery cell 2 disposed within the casing 1. The casing 1 is made of steel, and the steel composition includes Ti, Nb, and Cr, wherein, based on the total mass of the steel, the mass percentage of Cr is ≥16 wt.%. The casing 1 includes sidewalls 13 and endwalls. The endwalls include a first endwall 11 and a second endwall 12 located at both ends of the sidewalls 13. The battery cell 2 has a first end face near the first endwall 11 and a second end face near the second endwall 12 at both ends. The first endwall 11 is integrally formed with the sidewalls 13.

[0043] The shell 1 satisfies the following relationship: 0.15≤a / [d×(b+c)]≤300;

[0044] Where a is the sum of the distance from the first end face to the first end wall 11 and the distance from the second end face to the second end wall 12, in mm;

[0045] d is the thickness of the first end wall 11, in mm;

[0046] b represents the mass percentage of Ti based on the total mass of the steel, expressed in wt.%.

[0047] c represents the mass percentage of Nb based on the total mass of steel, expressed in wt.%.

[0048] As the battery casing 1 needs to meet certain corrosion resistance requirements, the corrosion resistance of the steel-cased battery casing 1 is improved by increasing the Cr mass percentage to ≥16wt.%. However, as the Cr mass percentage increases, the hardness of the casing 1 increases while its toughness and plasticity decrease, resulting in poor deep drawing performance. This increases the risk of fracture during deep drawing, leading to a decrease in manufacturing yield and performance. Therefore, the addition of Ti and Nb improves the deep drawing performance of the steel, ensuring rapid forming and high yield of the casing 1.

[0049] The content of Ti (titanium) (b) and Nb (niobium) (c) in the shell 1, which is formed by deep drawing of steel, affects the plastic deformation capacity of the shell 1. If the total content of Ti and Nb is too low, the plastic deformation capacity of the steel is poor, and the shell 1 is prone to damage during stamping, resulting in an increased defect rate. However, the content of Ti and Nb cannot be too high either. Although the plastic deformation capacity is improved within a certain range, which is beneficial to the deep drawing of the shell 1, the risk of deformation under stress will also increase. In particular, the thinner the wall thickness (d) of the end wall of the shell 1 after forming, the greater the risk of deformation. Furthermore, if the content of Ti and Nb is too high, it will react with iron to form coarse particles, reducing the formability of the steel.

[0050] During charging and discharging, the battery cell 2 expands, increasing the risk of deformation of the casing 1. This is especially true since the end walls of the casing 1 typically integrate various components, such as integrated modules; expansion of these end walls significantly increases the battery's safety risks. To reduce or avoid deformation of the casing 1 caused by the expansion of the battery cell 2, it is necessary to control the sum of the distances 'a' between the first end face of the battery cell 2 and the first end wall 11 of the casing 1, and the distances 'a' between the second end face of the battery cell 2 and the second end wall 12 of the casing 1. This sum is 'a', which represents the total gap between the two ends of the battery cell 2 and the inner wall 13 of the casing 1. If 'a' is too small, the expansion of the battery cell 2 will easily cause deformation of the casing 1; if 'a' is too large, it will result in low internal space utilization of the casing 1, reducing the battery's energy density. The battery cell 2 includes a battery cell 2 body and a tab. The first end face and the second end face refer to the end face of the battery cell 2 body. The tab is located on the end face of the battery cell 2 body. Therefore, the distance between the first end face and the first end wall 11 refers to the distance from the battery cell 2 body to the first end wall 11, not the distance from the tab to the first end wall 11. Similarly, the distance between the second end face and the second end wall 12 refers to the distance from the battery cell 2 body to the second end wall 12.

[0051] Therefore, when 'a' is relatively large, there is a larger space between the end walls of cell 2 and casing 1, making casing 1 less prone to deformation due to the expansion of cell 2. This allows b+c to also be relatively large, resulting in better plastic deformation capability and improved deep drawing performance. However, 'a' cannot be made too large to avoid deformation of casing 1 due to the expansion of cell 2, as an excessively large 'a' would lead to a decrease in the volumetric energy density of the battery.

[0052] The first end wall 11 is integrally formed with the side wall 13. When the housing 1 is deep-drawn, an opening is required for the punch to enter. This opening is usually one of the end walls of the battery, which is integrally formed with the side wall 13. The other end wall is formed separately and then fixedly connected to the side wall 13 by welding, riveting, bonding, or other methods. In this application, the first end wall 11 refers to the end wall integrally formed with the side wall 13, and the second end wall 12 refers to the end wall that is formed separately and then fixedly connected to the side wall 13. Since the first end wall 11 and the side wall 13 are integrally formed by deep drawing, the thickness that the first end wall 11 can be formed is related to the deep drawing performance of the steel. At the same time, the greater the thickness of the first end wall 11, the greater its resistance to deformation, and the lower the risk of breakage during the forming process of the housing 1. Therefore, this application limits the thickness of the first end wall 11 rather than the thickness of the second end wall 12.

[0053] When d is large, that is, the thickness of the first end wall 11 is large, the risk of deformation of the shell 1 is small, the stretch ratio of the shell 1 is smaller, and the wind direction of fracture during the molding process will be reduced. At this time, a and b+c can be relatively reduced, but d cannot be too large. If d is too large, it will lead to excessive energy density of the battery and excessive cost.

[0054] When d is small, that is, the wall thickness of the first end wall 11 is small, the tensile strength of the shell 1 is large, and the risk of breakage during the molding process is higher. In order to improve the molding performance of the shell 1, b+c should be increased appropriately, but this will increase the risk of deformation of the shell 1. Therefore, in order to reduce the risk of deformation of the shell 1, a should also be increased appropriately.

[0055] In summary, by ensuring that the sum of the distance from the first end face to the first end wall 11 and the distance from the second end face to the second end wall 12 (a), the thickness of the first end wall 11 (d), the mass percentage of Ti (b), and the mass percentage of Nb (c) satisfy the following condition: 0.15 ≤ a / [d×(b+c)] ≤ 300, the shell 1 can meet the plastic deformation capacity required for deep drawing processing, while reducing the risk of deformation of the shell 1 after molding, avoiding the risk of deformation of the shell 1 due to the expansion of the cell 2, and ensuring that the energy density of the battery is not too low.

[0056] In one embodiment, the first end wall 11 is integrally formed with the housing 1, and the second end wall 12 can be a separate cover plate. The second end wall 12 and the circumferential side wall 13 of the housing 1 can be connected by welding, riveting, bonding, etc. The material of the cover plate can be the same as the material of the side wall 13 and the first end wall 11.

[0057] In some embodiments of this application, the specific selection of a / [d×(b+c)] can be 0.15, 0.2, 0.3, 0.5, 1, 2, 5, 8, 10, 20, 30, 50, 75, 100, 120, 150, 180, 200, 220, 250, 270, 280, 300, or it can be any range formed by any two of the above values, such as 1-200, 0.2-120, 2-220, etc.

[0058] The testing methods for Ti, Nb, and Cr content are not limited, and those skilled in the art can detect the Ti, Nb, and Cr content using conventional methods, such as inductively coupled plasma atomic absorption spectrometry (ICP-AES) and X-ray fluorescence spectrometry.

[0059] The method for measuring 'a' is as follows:

[0060] Measure the height of cell 2, i.e., the maximum distance a1 from the first end face to the second end face, and measure the height inside casing 1, i.e., the minimum distance a2 from the first end wall to the second end wall. Then a = a2 - a1. To minimize errors, measure a1 and a2 multiple times and take their average value.

[0061] The method for measuring b is as follows:

[0062] The thickness of the first end wall 11 is measured using an ultrasonic thickness gauge. To reduce errors, the measurement is performed at multiple different positions of the first end wall 11 of each housing 1 and the average value is taken as the thickness d of the first end wall 11 of the housing 1.

[0063] The testing methods for Ti, Nb, and Cr content are not limited, and those skilled in the art can detect the Ti, Nb, and Cr content using conventional methods. For example, inductively coupled plasma method, X-ray fluorescence spectrometry, or other testing methods will not affect the implementation of this solution.

[0064] Inductively coupled plasma method:

[0065] (1) Sample preparation: Stainless steel samples need to undergo appropriate pretreatment, such as dissolving in a specific acid solution to release the analyte. For example, aqua regia can be used to dissolve the sample, or a specific mixed acid system can be used for digestion to ensure effective release of the analyte.

[0066] (2) Analytical Methods: The main analytical methods of ICP-OES include the standard curve method and the internal standard method. The standard curve method involves plotting the relationship between the concentration of a standard solution and the emission intensity at the corresponding wavelength, comparing the emission intensity of the sample solution with the standard curve to determine the content of each element in the sample. The internal standard method selects an element with similar chemical properties to the analyte and a constant content in the sample as an internal standard. By comparing the emission intensity ratio of the analyte and the internal standard element, the influence of factors such as sample composition and experimental conditions is eliminated.

[0067] X-ray fluorescence spectroscopy

[0068] (1) Sample preparation: First, the stainless steel sample needs to be properly treated to allow X-rays to penetrate and excite fluorescence. This may include steps such as cutting, grinding, and polishing to ensure that the sample surface is flat and free of contamination.

[0069] (2) X-ray excitation: High-energy X-rays are used to irradiate the sample surface, exciting the characteristic X-ray fluorescence of each element. The wavelength or energy characteristics of these fluorescence spectra correspond to the element types, thus allowing the determination of which elements are contained in the sample.

[0070] (3) Spectral collection and analysis: X-rays reflected from the sample surface and fluorescence spectra emitted are collected using a spectrometer. The type and content of elements can be determined by using the position and intensity of characteristic spectral lines.

[0071] (4) Matrix effect correction: Due to the interaction between various elements in stainless steel (matrix effect), the collected spectral data needs to be corrected to eliminate the influence of this interaction on the analysis results and improve the accuracy of the analysis.

[0072] (5) Interpretation of results: Based on the corrected data, the content of each element in stainless steel can be calculated, and its performance and quality can be evaluated.

[0073] In one embodiment, the housing 1 satisfies the following relationship: 1≤a / [d×(b+c)]≤200.

[0074] In this scheme, the shell 1, which satisfies the above relationship, not only meets the plastic deformation capacity required for deep drawing processing, but also has a lower degree of deformation due to the expansion of the battery cell 2.

[0075] In one embodiment, the range of b+c is 0.2-0.8 wt.%.

[0076] In some embodiments of this application, b+c can be specifically selected as 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, or 0.8, or it can be any range formed by any two of the above values, such as 0.25-0.5, 0.3-0.7, or 0.2-0.6.

[0077] In one embodiment, the range of b is 0.05-0.2 wt.%.

[0078] In some embodiments of this application, b can be specifically selected as 0.05, 0.06, 0.07, 0.08, 0.1, 0.12, 0.15, 0.17, 0.18, 0.19, or 0.2, or it can be an interval range formed by any two of the above values, such as 0.05-0.15, 0.07-0.2, 0.1-0.2, etc.

[0079] In one embodiment, the range of c is 0.17-0.5 wt.%.

[0080] In some embodiments of this application, the specific selection of c can be 0.17, 0.18, 0.19, 0.2, 0.22, 0.25, 0.28, 0.3, 0.35, 0.4, 0.45, 0.48, or 0.5, or it can be any range formed by any two of the above values, such as 0.17-0.4, 0.2-0.4, 0.25-0.5, etc.

[0081] Ti and Nb are both carbon and nitrogen stabilizing elements, capable of combining with carbon and nitrogen to form TiC, TiN, or NbC, NbN, inhibiting the formation of chromium carbides and nitrides in steel and improving the intergranular corrosion resistance of stainless steel. Simultaneously, Ti and Nb are both ferrite forming elements; an appropriate amount of Ti in steel can refine the ferrite weld microstructure, improving weld plasticity and formability. However, excessive addition of Ti will decrease the material's formability. Furthermore, Ti mainly exists as precipitated phases such as TiN. TiN has a very low solidsity product, therefore it begins to precipitate before solidification. This non-uniform nucleation site promotes an excessively high proportion of equiaxed grains in the solidified microstructure, thus achieving excellent deep-drawing properties. Solid-solution Nb can promote the formation of γ+α two-phase texture in steel. A small amount of this texture is beneficial to improve deep drawing performance, but excessive Nb content will lead to the formation of Fe2Nb hard phase in steel, which will reduce the elongation and deep drawing performance of the material. Excessive Nb nitride (NbN) formed by Nb and nitrogen will also reduce the hot plasticity of steel.

[0082] The mass percentage of Ti is the percentage of Ti's mass in the total mass of the steel, and the mass percentage of Nb is the percentage of Nb's mass in the total mass of the steel.

[0083] In one embodiment, the range of d is 0.15-1.2 mm.

[0084] In some embodiments of this application, the specific selection of d can be 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 1.0, 1.05, 1.1, 1.15, 1.2, or any range formed by any two of the above values, such as 0.2-1.0, 0.15-0.8, 0.5-1.2, etc.

[0085] In one embodiment, the range of 'a' is 0.1-10 mm.

[0086] In some embodiments of this application, the specific selection of 'a' can be 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, or 1.0, or it can be any range formed by any two of the above values, such as 0.2-0.8, 0.5-1.0, or 0.35-0.85.

[0087] In one embodiment, the battery is a cylindrical battery.

[0088] In one embodiment, the range of 'a' is 0.5-10 mm.

[0089] During charging and discharging, cell 2 expands, exerting a force on housing 1 and causing it to deform. When housing 1 is cylindrical, the expansion force of cell 2 on the circumference of the cylindrical housing 1 is self-cancelling, resulting in a relatively small impact force on the circumference of housing 1 and a relatively low risk of lateral deformation. However, the expansion of the end face of cell 2 has a greater impact on the end wall of housing 1, leading to a higher risk of deformation of the end wall of the cylindrical housing 1. Therefore, to reduce the risk of deformation of housing 1, the value of a can be appropriately increased for cylindrical housing 1, allowing sufficient clearance between cell 2 and housing 1 to reduce the deformation rate of the end wall of housing 1 caused by the expansion of cell 2. Thus, when housing 1 is cylindrical, the lower limit of the selectable range of a is appropriately increased; in this scheme, the range of a is 0.5-10 mm.

[0090] In one embodiment, the battery cell 2 is provided with a winding hole 21, and the battery satisfies the following relationship: 0.4≤S×a≤600;

[0091] Where S is the area of ​​the core hole 21, in mm. 2 .

[0092] Cell 2 includes a positive electrode, a negative electrode, and a separator, with the separator disposed between the positive and negative electrode. The positive electrode, negative electrode, and separator are formed by winding or stacking to form cell 2. The positive electrode includes a positive current collector and a positive active material layer, and the negative electrode includes a negative current collector and a negative active material layer. The material of the positive current collector is not limited, as long as it is conductive and will not cause adverse chemical changes in the battery. For example, it can be made of stainless steel, aluminum, nickel, titanium, sintered carbon, or aluminum or stainless steel with a surface treatment of carbon, nickel, titanium, silver, etc. The current collector can also be a composite current collector, including a polymer interlayer and conductive layers disposed on both sides of the interlayer, with the active material layer disposed on the surface of the conductive layer. Further, the negative current collector can be made of copper, stainless steel, nickel, titanium, etc. In a specific embodiment, the positive current collector can be made of aluminum, and the negative current collector can be made of copper.

[0093] The positive electrode active material layer includes positive electrode active materials, such as nickel-cobalt-manganese ternary materials, lithium iron phosphate materials, and lithium manganese iron phosphate materials; the negative electrode active material layer includes negative electrode active materials, such as artificial graphite, natural graphite, and silicon-based materials.

[0094] During the winding process of cell 2, a winding needle is used as a support. After winding, the winding needle is removed from cell 2, and a core hole 21 is formed at the center of cell 2 due to the removal of the winding needle. The core hole 21 can serve as a gas storage space, reducing the expansion rate of cell 2 and thus minimizing the deformation rate of the end wall of casing 1 caused by the expansion of cell 2. Therefore, the larger the core hole 21, the more gas storage space there is, and the lower the expansion rate of casing 1 caused by the expansion of cell 2. Consequently, the value 'a' can be appropriately reduced, thereby improving the space utilization of casing 1 and increasing the energy density of the battery.

[0095] In one embodiment, the battery is a tetragonal prism battery.

[0096] When the battery is a quadrangular prism battery, both the battery casing 1 and the battery cell 2 are quadrangular prisms.

[0097] In one embodiment, the range of 'a' is 0.1-8 mm.

[0098] When the housing 1 is a quadrangular prism, the area of ​​the sidewall 13 and the endwalls at both ends of the housing 1 are usually different. In particular, when the endwall is rectangular, the sidewall 13 includes two opposing first sidewalls and two opposing second sidewalls. The area of ​​the first sidewall is larger than that of the second sidewall. At the same time, the shape of the battery cell 2 is also quadrangular prism, and the battery cell 2 also includes two opposing first sidewalls and two opposing second sidewalls. The battery cell 2 is placed in the same position when it is inside the housing 1. The first sidewall is set opposite to the first sidewall, and the second sidewall is set opposite to the second sidewall. During the charging and discharging process of the battery cell 2, the first sidewall with the largest area of ​​the battery cell 2 expands more and exerts a greater force on the first sidewall of the housing 1. Therefore, the first sidewall is more likely to deform.

[0099] Therefore, when the shell 1 is a quadrangular prism, the expansion of the shell 1 is not uniform. The side with the largest area of ​​the shell 1 is expanded more, and this side is usually the side wall 13 of the shell 1. The expansion of the end wall is less affected. Therefore, the preferred range of a can be appropriately reduced. In this scheme, the range of a is 0.1-8mm.

[0100] In one embodiment, when the aspect ratio of the housing 1 is not less than 2, the range of b+c is 0.2-0.7 wt.%.

[0101] When shell 1 is a quadrangular prism, its length and width are the lengths of the long and short sides of its end walls. Deep drawing of shell 1 involves a process of transforming a round shape into a square one. A larger aspect ratio (length to width) of shell 1 results in better plastic deformation capability required for deep drawing, but also a higher risk of deformation due to the expansion of the battery cell 2. Therefore, the deformation resistance of shell 1 needs to be considered. Thus, when the aspect ratio of shell 1 is not less than 2, the preferred range for b+c is 0.2-0.7 wt.%.

[0102] In one embodiment, the battery cell 2 includes a positive electrode tab and a negative electrode tab, which are electrically connected to the housing 1, and the Cr content is 16-30 wt.%.

[0103] Regarding the forming method of the positive and negative electrode tabs, specifically, the positive and negative electrode sheets include a current collector and an active material layer, with the active material layer coated on the current collector. The positive and negative electrode tabs can be formed by overcutting the current collector; they can also be separate conductive parts electrically connected to the current collector; or other methods can be used without affecting the implementation of the solution.

[0104] The battery also includes a terminal assembly, which is located on the housing 1. Two terminal assemblies can be provided and connected to the positive and negative terminals respectively. However, in this solution, only one terminal assembly is provided and located on the end wall of the housing 1. One of the positive and negative terminals is connected to the housing 1. One of the positive and negative terminals of the cell 2 is connected to the housing 1, and the other is connected to the terminal assembly. For example, if the positive terminal is connected to the housing 1, the housing 1 will be positively charged, and if the terminal assembly is connected to the negative terminal of the battery, the terminal assembly will be negatively charged; or if the positive terminal is connected to the terminal assembly of the battery, the terminal assembly will be positively charged, and if the negative terminal is connected to the housing 1, the housing 1 will be negatively charged.

[0105] Connecting housing 1 to either the positive or negative electrode tab makes housing 1 an electrode output terminal. Housing 1 has a larger area for electrical connection, increasing the current-carrying area and saving space for one electrode assembly, thus providing sufficient space for the remaining motor assembly. This simplifies the battery structure and provides space for the arrangement of other components such as the battery busbar. The connection between the positive or negative electrode tab and housing 1 is an electrical connection. This can be achieved directly by welding, or indirectly by connecting the positive or negative electrode tab before the current collector, and then welding the current collector to housing 1. Indirect connection improves welding efficiency. Other connection methods are also possible without affecting the implementation of this solution.

[0106] The positive or negative electrode tab is connected to the shell 1, which serves as the positive or negative electrical connection terminal. This increases the risk of electrochemical corrosion for the shell 1. To improve its resistance to electrochemical corrosion, the Cr content needs to be increased. Cr is the main element determining the corrosion resistance of stainless steel and can increase the base electrode potential, thus significantly improving the steel's corrosion resistance. Additionally, Cr, as a major component of the oxide film, helps form a more stable oxide film, improving oxidation resistance at high temperatures. However, increasing the Cr content increases the hardness of the shell 1, reduces its plastic deformation capacity during forming, and worsens its machinability. To improve the machinability of the shell 1, the Ti and Nb contents need to be increased, which in turn increases the risk of deformation.

[0107] Therefore, controlling the Cr content by 16-30 wt.% ensures the corrosion resistance of shell 1, reduces the risk of deformation, and avoids an increase in the risk of breakage during the molding process of shell 1, which would reduce the manufacturing yield of shell 1.

[0108] In one embodiment, both the positive and negative electrode tabs are disposed on the first or second end face of the battery cell 2, and the range of a is 0.5-10mm.

[0109] Since the positive and negative electrodes are located on the same end of the cell 2, the heat is concentrated, which increases the risk of deformation of the end wall of the casing 1. Therefore, the range of a can be appropriately increased. Thus, the preferred range of a in this scheme is 0.5-10mm.

[0110] In one embodiment, the positive electrode tab and the negative electrode tab are respectively disposed on the first end face and the second end face of the battery cell 2, and the range of a is 0.2-8mm.

[0111] The positive and negative electrodes are respectively disposed on the first and second end faces of the battery cell 2. This disperses heat, reduces the risk of deformation of the end wall of the casing 1, and allows for a suitable reduction in the range of a. Therefore, the preferred range of a in this design is 0.2-8 mm. Alternatively, the positive electrode can be disposed on the first end face and the negative electrode on the second end face; or the positive electrode can be disposed on the second end face and the negative electrode on the first end face.

[0112] In some embodiments, the steel comprises:

[0113] Fe, and the following components in mass percentage (based on the total mass of steel):

[0114] C: greater than 0 and less than 0.03%, Si: 0 to 0.75%, Mn: 0 to 1.0%, P: 0 to 0.04%, S: 0 to 0.03%, Cr: 16 to 30%, Ti: 0.05 to 0.2%, Nb: 0.17 to 0.5%, unavoidable impurities 0.5%.

[0115] Another embodiment of this application also provides an electrical device, including the battery described above.

[0116] For example, in some embodiments, the battery manufacturing process is as follows:

[0117] 1. Preparation of the shell:

[0118] (1) Steel preparation: The molten steel is smelted to remove impurities and finely adjusted according to the target chemical composition required by shell 1. After obtaining the molten steel with the composition as described above, it is cast to obtain steel ingots.

[0119] (2) Preparation of blanks: The steel ingots are rolled into coils, and then the coils are cut into plates of appropriate size;

[0120] (3) Deep drawing: Place the sheet in a suitable mold and fix it, then press the punch on the mold with a certain force and repeat the drawing until the shell 1 is formed.

[0121] (4) Trimming: Remove and trim the excess material during the deep drawing process to ensure that the burrs and flatness of the cut meet the requirements; thus obtaining shell 1.

[0122] 2. Preparation of lithium-ion batteries

[0123] The positive electrode, separator, and negative electrode are stacked in sequence, with the separator positioned between the positive and negative electrodes to act as an isolation layer. Then, the cells are wound to obtain bare cell 2.

[0124] The cell 2 is placed in the shell 1 prepared above, and the second end wall 12 and the shell 1 are connected together by laser welding; after drying, the electrolyte is injected into the bare cell 2, formed, and volume is adjusted to obtain the prepared lithium-ion battery.

[0125] The positive electrode, separator, negative electrode, and electrolyte can be conventional positive electrode, separator, negative electrode, and electrolyte in the art; they can be conventional commercial products or prepared by conventional preparation methods in the art.

[0126] Specific embodiments further illustrate this application:

[0127] Examples 1-17:

[0128] Examples 1-17 provide a battery, as shown in Figures 1 and 2, wherein the casing 1 is cylindrical.

[0129] The chemical composition of the shell 1 includes: C, Si, Mn, P, S, Ti, Nb, Cr and Fe; wherein, based on the total mass of steel, the mass percentages of C, Si, Mn, P and S are: C: 0.03%, Si: 0.7%, Mn: 0.95%, P: 0.04%, S: 0.03%.

[0130] The mass percentages of Cr, Ti, and Nb are shown in Table 1;

[0131] The rest is iron.

[0132] The battery is manufactured as follows:

[0133] 1. Preparation of the shell

[0134] (1) Steel preparation: The molten steel is smelted to remove impurities and finely adjusted according to the target chemical composition required by shell 1. After obtaining the molten steel with the composition as described above, it is cast to obtain steel ingots.

[0135] (2) Preparation of blanks: The steel ingot is rolled into a coil. During the rolling process, the thickness of the coil is adjusted by adjusting the size, gap and speed of the rolling mill rollers to prepare shells 1 with different thicknesses d of the first end wall 11. Then the coil is cut into plates of appropriate size.

[0136] (3) Deep drawing: The sheet metal is placed in a suitable mold and fixed. Then, the punch is pressed onto the mold with a certain force, and the drawing is repeated until the shell 1 is formed. The formed shell 1 is cylindrical with a volume of 10048 mm². 3 .

[0137] (4) Trimming: Remove and trim excess material during deep drawing to ensure that the burrs and flatness of the cut meet the requirements.

[0138] 2. Preparation of the positive electrode sheet

[0139] LiNi, the positive electrode active material 0.9 Co 0.05 Mn 0.05 O3, conductive agent acetylene black, and binder PVDF are mixed at a mass ratio of 96:2:2, and solvent NMP is added. The mixture is stirred under vacuum until the system is homogeneous to obtain the positive electrode slurry. The positive electrode slurry is uniformly coated on both surfaces of the positive electrode current collector aluminum foil, air-dried at room temperature, and then transferred to an oven for further drying. After cold pressing and slitting, the positive electrode sheet is obtained.

[0140] 3. Preparation of negative electrode sheet

[0141] The negative electrode active material, conductive agent (SP), and binder are mixed in a certain mass ratio (97:1:1), wherein the negative electrode active material includes artificial graphite and silicon carbide, with an artificial graphite:silicon carbide ratio of 92:5. Then, deionized water is added as a solvent, and the mixture is stirred under vacuum until the system is homogeneous, obtaining a negative electrode slurry. The negative electrode slurry is uniformly coated onto both surfaces of the negative electrode current collector copper foil, air-dried at room temperature, and then transferred to an oven for further drying. Finally, it is cold-pressed and slit to obtain the negative electrode sheet.

[0142] 4. Preparation of electrolyte

[0143] Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) were mixed in a volume ratio of 1:1:1 to obtain an organic solvent. FEC was added according to the examples and comparative examples. Then, fully dried lithium salt LiPF6 was dissolved in the mixed organic solvent to prepare an electrolyte with a lithium salt concentration of 1 mol / L.

[0144] 5. Preparation of the diaphragm

[0145] In this embodiment, polyethylene film is selected as the diaphragm, and the polyethylene film is cut to form the diaphragm.

[0146] 6. Preparation of lithium-ion batteries

[0147] The positive electrode, separator, and negative electrode are cut to appropriate sizes and stacked in the order of positive electrode - separator - negative electrode, so that the separator is placed between the positive electrode and the negative electrode to play a role in isolation. Then, they are wound to obtain bare cell 2, and the height of the wound cell 2 is a1.

[0148] The cell 2 is placed in the housing 1 (prepared as described above), and the second end wall 12 and the housing 1 are connected together by laser welding; after drying, liquid is injected, formation is performed, and the volume is adjusted to obtain the prepared lithium-ion battery.

[0149] X-ray fluorescence spectroscopy

[0150] (1) Sample preparation: First, the stainless steel sample needs to be properly treated to allow X-rays to penetrate and excite fluorescence. This may include steps such as cutting, grinding, and polishing to ensure that the sample surface is flat and free of contamination.

[0151] (2) X-ray excitation: High-energy X-rays are used to irradiate the sample surface, exciting the characteristic X-ray fluorescence of each element. The wavelength or energy characteristics of these fluorescence spectra correspond to the element types, thus allowing the determination of which elements are contained in the sample.

[0152] (3) Spectral collection and analysis: X-rays reflected from the sample surface and fluorescence spectra emitted are collected using a spectrometer. The type and content of elements can be determined by using the position and intensity of characteristic spectral lines.

[0153] (4) Matrix effect correction: Due to the interaction between various elements in stainless steel (matrix effect), the collected spectral data needs to be corrected to eliminate the influence of this interaction on the analysis results and improve the accuracy of the analysis.

[0154] (5) Interpretation of results: Based on the corrected data, the content of each element in stainless steel can be calculated, and its performance and quality can be evaluated.

[0155] The method for measuring 'a' is as follows:

[0156] Measure the height of cell 2, i.e. the maximum distance a1 from the first end face to the second end face, and measure the height inside the casing 1, i.e. the minimum distance a2 from the first end wall to the second end wall. Measure three sets for each casing 1 and take the average value. Calculate the value of a using a = a2 - a1.

[0157] The method for measuring d is as follows:

[0158] The thickness of the first end wall 11 is measured using an ultrasonic thickness gauge. During the measurement, measurements are taken at three different positions of the first end wall 11 of each housing 1, and the average value is taken as the thickness d of the first end wall 11 of the housing 1.

[0159] Method for measuring the area of ​​core hole 21:

[0160] The inner diameter of the core hole 21 is measured three times in different directions, and the average value is taken as the diameter k of the core hole 21. The formula S = π(k / 2) is then used to calculate the diameter. 2 Calculate the area S of the core hole 21.

[0161] The values ​​of a, d, and S of the prepared battery are shown in Table 1.

[0162] Examples 18-24:

[0163] Examples 18-24 are similar to Example 1, except that the battery cell 2 includes a positive electrode tab and a negative electrode tab, which are electrically connected to the housing 1. The positive and negative electrode tabs are disposed on the same end wall of the battery cell 2. The mass percentage of Cr and the values ​​of a, b, c, d, and S of the prepared battery are shown in Table 2.

[0164] Examples 25-28:

[0165] Examples 25-28 are similar to Example 18, except that the positive and negative electrode tabs are respectively disposed on the two end walls of cell 2. The mass percentage of Cr and the values ​​of a, b, c, d, and S of the prepared battery are shown in Table 2.

[0166] Examples 29-38:

[0167] Examples 29-38 are similar to Example 1, except that, as shown in Figure 3, the shell 1 is in the shape of a quadrangular prism.

[0168] This embodiment is similar to Embodiment 1, except that:

[0169] 1. The shell is prepared as follows:

[0170] (1) Steel preparation: The molten steel is smelted to remove impurities and finely adjusted according to the target chemical composition required by shell 1. After obtaining the molten steel with the composition as described above, it is cast to obtain steel ingots.

[0171] (2) Preparation of blanks: The steel ingot is rolled into a coil. During the rolling process, the thickness of the coil is adjusted by adjusting the size, gap and speed of the rolling mill rollers to prepare shells 1 with different thicknesses d of the first end wall 11. Then the coil is cut into plates of appropriate size.

[0172] (3) Deep drawing: Place the sheet metal into a suitable mold and fix it in place. Then, press the punch onto the mold with a certain force. Change the square mold and punch to perform round-to-square drawing, repeating the drawing process until shell 1 is formed. The formed shell 1 is a cuboid with a volume of 970,000 mm². 3 .

[0173] (4) Trimming: Remove and trim excess material during deep drawing to ensure that the burrs and flatness of the cut meet the requirements.

[0174] 2. Preparation of the positive electrode sheet

[0175] LiNi, the positive electrode active material 0.6 Co 0.2 Mn 0.2 O3, conductive agent acetylene black, and binder PVDF are mixed at a mass ratio of 96:2:2, and solvent NMP is added. The mixture is stirred under vacuum until the system is homogeneous to obtain the positive electrode slurry. The positive electrode slurry is uniformly coated on both surfaces of the positive electrode current collector aluminum foil, air-dried at room temperature, and then transferred to an oven for further drying. After cold pressing and slitting, the positive electrode sheet is obtained.

[0176] 3. Preparation of negative electrode sheet

[0177] Artificial graphite (anode active material), conductive agent (SP), and binder are mixed in a certain mass ratio (97:1:1), and deionized water is added as a solvent. The mixture is stirred under vacuum until the system is homogeneous to obtain a cathode slurry. The cathode slurry is uniformly coated on both surfaces of the cathode current collector copper foil, air-dried at room temperature, and then transferred to an oven for further drying. After cold pressing and slitting, the cathode sheet is obtained.

[0178] The values ​​of a, b, c, d, and S of the prepared battery are shown in Table 3.

[0179] Comparative Examples 1-3

[0180] Comparative Examples 1-3 are similar to Example 1, except that the values ​​of a, b, c, d, and S of the prepared batteries are shown in Table 1.

[0181] Table 1

[0182] Table 2

[0183] Table 3

[0184] Performance testing:

[0185] 1. Degree of deformation of housing 1 after cyclic testing:

[0186] The lithium-ion batteries prepared in the examples and comparative examples were cycled at 25°C according to the following procedure, wherein when the positive electrode active material was selected as a nickel-cobalt-manganese ternary cathode, the cycling strategy was as follows:

[0187] (1) Charge at a constant current rate of 1C to 4.35V, and charge at a constant voltage until the current drops to 0.05C;

[0188] (2) Let it stand for 10 minutes;

[0189] (3) Discharge to 2.75V at a 1C rate;

[0190] (4) Let stand for 10 minutes.

[0191] Perform 50 cycles of testing according to steps (1)-(4), and observe the height of the protrusion at the point of maximum deformation of the first end wall 11, where:

[0192] No deformation: Deformation height is between 0-0.1mm;

[0193] Slight deformation: Deformation height is between 0.1-0.5 mm;

[0194] Moderate deformation: Deformation height between 0.5-1mm;

[0195] Severe deformation: greater than 1 mm.

[0196] 2. Battery capacity testing method:

[0197] Place the battery in a 25°C constant temperature chamber and perform the following operations on the test subject:

[0198] (1) Charge at a constant current rate of 0.33C to 4.35V, and then charge at a constant voltage until the current drops to 0.05C;

[0199] (2) Let stand for 30 minutes;

[0200] (3) Discharge at 0.33C to the lower limit voltage of 2.75V;

[0201] Repeat the above steps 3 times, and use the discharge capacity of the third cycle as the battery capacity.

[0202] 3. Shell molding ratio

[0203] The shell 1 was deep-drawn according to the above-mentioned preparation method, and the forming rate of 200 shells 1 was calculated.

[0204] Comparative analysis of Examples 1-12, 29-38 and Comparative Examples 1-3 shows that when 0.15≤a / [d×(b+c)]≤300 is satisfied, the casing 1 has a high molding rate. Furthermore, after 50 charge-discharge cycles of the battery, the deformation of the casing 1 due to the expansion of the cell 2 is low, and the energy density of the battery is not too low. Based on this, when 1≤a / [d×(b+c)]≤200 is also satisfied, the molding rate of the casing 1 is even higher.

[0205] When shell 1 is cylindrical, it satisfies the condition that 1 ≤ a / [d×(b+c)] ≤ 200, and also satisfies 0.15 < d < 1.2 mm, 0.5 < a < 10 mm, and 0.25 < b+c < 0.5 wt.%. Shell 1 has a high molding rate and does not deform. When shell 1 is square prism, it satisfies the condition that 1 ≤ a / [d×(b+c)] ≤ 200, and also satisfies 0.15 < d < 1.2 mm, 0.1 < a < 8 mm, and 0.25 < b+c < 0.5 wt.%. Shell 1 also has a high molding rate and does not deform. Since the cylindrical shell 1 is most easily deformed by the expansion of the cell 2 at the end wall, while the quadrangular prism-shaped battery shell 1 is most easily deformed by the expansion of the cell 2 at the side wall 13 with the largest area, in order to make the shell 1 have a high forming rate and not deform, the value of a for the cylindrical shell 1 must satisfy 0.5 < a < 10 mm, while the value of a for the quadrangular prism must satisfy 0.1 < a < 8 mm.

[0206] Meanwhile, when the shell 1 is a quadrangular prism with an aspect ratio greater than 2, the shape change during the deep drawing process of the side wall 13 is greater, and the plastic deformation capability required for deep drawing is better. However, the risk of shell 1 being deformed due to the expansion of the battery cell 2 is higher. When b+c is 0.2-0.7wt.%, the deformation of shell 1 is smaller while taking into account the forming rate of shell 1.

[0207] As can be seen from Examples 13-17, since the core hole 21 can serve as a gas storage space to reduce the expansion rate of the battery cell 2, the possibility of deformation of the casing 1 is reduced when 0.4≤S×a≤600 is satisfied. When the area of ​​the core hole 21 is less than 0.4, the core hole 21 cannot store gas due to its small area, and the casing 1 is prone to deformation.

[0208] As can be seen from Examples 18-28, an excessive Cr content reduces the molding yield of the shell 1. Furthermore, when the positive and negative electrode tabs are located on the same end of the cell 2, heat concentration increases the risk of deformation of the end wall of the shell 1. To achieve a high molding yield and prevent deformation of the shell 1, when the positive and negative electrode tabs are located on the same end of the cell 2, a satisfies 0.5 < a < 10 mm; when the positive and negative electrode tabs are located on opposite ends of the cell 2, a satisfies 0.1 < a < 8 mm.

[0209] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit the scope of protection of this application. Although this application has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this application without departing from the substance and scope of the technical solutions of this application.

Claims

1. A battery comprising a casing (1) and a battery cell (2) disposed within the casing (1), wherein the casing (1) is made of steel, characterized in that, The steel composition includes Ti, Nb and Cr, wherein, based on the total mass of the steel, the mass percentage of Cr is ≥16wt.%; the shell (1) includes a side wall (13) and an end wall, the end wall including a first end wall (11) and a second end wall (12) located at both ends of the side wall (13), the battery cell (2) includes a first end face near the first end wall (11) and a second end face near the second end wall (12) at both ends; the first end wall (11) is integrally formed with the side wall (13); The shell (1) satisfies the following relationship: 0.15≤a / [d×(b+c)]≤300; Where a is the sum of the distance from the first end face to the first end wall (11) and the distance from the second end face to the second end wall (12), in mm; d is the thickness of the first end wall (11), in mm; b represents the mass percentage of Ti based on the total mass of the steel, expressed in wt.%. c represents the mass percentage of Nb based on the total mass of steel, expressed in wt.%.

2. The battery according to claim 1, characterized in that, The shell (1) satisfies the following relationship: 1≤a / [d×(b+c)]≤200.

3. The battery according to claim 1 or 2, characterized in that, The range of b+c is 0.2-0.8 wt.%.

4. The battery according to claim 3, characterized in that, The range of b+c is 0.25-0.5 wt.%.

5. The battery according to claim 4, characterized in that, The range of b is 0.05-0.2 wt.%.

6. The battery according to claim 1, characterized in that, The range of c is 0.17-0.5 wt.%.

7. The battery according to claim 1 or 2, characterized in that, The range of d is 0.15-1.2 mm.

8. The battery according to claim 1 or 2, characterized in that, The range of 'a' is 0.1-10 mm.

9. The battery according to claim 1 or 2, characterized in that, The battery is a cylindrical battery.

10. The battery according to claim 9, characterized in that, The range of 'a' is 0.5-10 mm.

11. The battery according to claim 9, characterized in that, The battery cell (2) is provided with a winding hole (21), and the battery satisfies the following relationship: 0.4≤S×a≤600; Where S is the area of ​​the core hole (21), in mm. 2 .

12. The battery according to claim 1 or 2, characterized in that, The battery is a quadrangular prism battery.

13. The battery according to claim 12, characterized in that, The range of 'a' is 0.1-8 mm.

14. The battery according to claim 12, characterized in that, When the aspect ratio of the shell (1) is not less than 2, the range of b+c is 0.2-0.7 wt.%.

15. The battery according to claim 1, characterized in that, The battery cell (2) includes a positive electrode tab and a negative electrode tab, which are electrically connected to the housing (1), and the mass percentage of Cr is 16-30 wt.%.

16. The battery according to claim 15, characterized in that, Both the positive and negative electrode tabs are disposed on the first or second end face of the battery cell (2), and the range of a is 0.5-10mm.

17. The battery according to claim 16, characterized in that, The positive electrode tab and the negative electrode tab are respectively disposed on the first end face and the second end face of the battery cell (2), and the range of a is 0.2-8mm.

18. An electrical appliance, characterized in that, Includes the battery as described in any one of claims 1-17.

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