Battery cell housings made from aluminum alloy strips with high recovery rates

Abstract

The invention relates to a battery cell housing having an aluminum alloy strip or sheet. The object of the invention is to provide a battery cell housing having an aluminum alloy strip or sheet which, on the one hand, achieves a high recycling rate and, on the other hand, meets the requirements for a battery cell housing, in particular the requirements for strength, electrolyte stability, electrical conductivity and thermal conductivity, which is achieved in that the aluminum alloy strip or sheet has an aluminum alloy having the following alloying constituents in % by weight: 0.1% ≤ Si ≤ 0.5%, 0.25% ≤ Fe ≤ 0.8%, Cu ≤ 0.6%, 0.6% ≤ Mn ≤ 1.4%, 0.5% ≤ Fe ≤ 1.5%, Cr ≤ 0.25%, Zn ≤ 0.4%, Ti ≤ 0.2%, the remainder being Al and unavoidable impurities, individual maximum 0.05%, total maximum 0.15%.

Description

TECHNICAL FIELD

[0001] The present invention relates to a battery cell housing having an aluminum alloy strip or sheet and to the use of an aluminum alloy strip or sheet for manufacturing a battery cell housing. BACKGROUND

[0002] Battery cells are widely used in various technical applications to provide electrical energy for electrical appliances. For example, to name only a few, fields of application of battery cells include electric mobility, in particular electric cars, electric bicycles and electric scooters, consumer electronics, in particular laptops, tablets, mobile phones, digital cameras and camcorders, or energy technology, in particular battery storage, etc. Multiple battery cells are usually connected in series or in parallel to form a battery module or a battery system. However, there are also applications in which a single battery cell is used as an energy source.

[0003] Battery cells can basically be divided into primary batteries, which can only be discharged once and cannot be charged, and secondary batteries, which can be charged. In both primary and secondary batteries, the electrochemical processes required to provide the functionality of the battery cell can be implemented using a variety of different materials. Briefly, primary batteries include, for example, alkaline manganese batteries, zinc-carbon batteries, nickel hydroxide batteries or lithium-iron sulfide batteries. Briefly, secondary batteries include, for example, lithium-ion batteries, sodium-ion batteries, nickel-cadmium batteries, nickel-metal hydride batteries or nickel-zinc batteries.

[0004] For many years, lithium-ion secondary batteries have been increasingly used, in particular in the field of electric mobility and consumer electronics, due to their relatively high gravimetric and volumetric energy density. Like other types of battery cells, lithium-ion secondary batteries also have a battery cell housing. This constitutes the outer shape of the battery cell and encloses a cavity in which, among other things, anode material, cathode material and electrolyte are present. Here, the battery cell housing can be divided into various construction forms: A cylindrical construction form of the battery cell has essentially the shape of a cylinder. If the height of the cylinder is greater than the diameter, it is referred to as a round battery cell, otherwise as a button battery. A prismatic construction form of the battery cell housing essentially has the shape of a prism, in particular a cuboid. Another variant is a pouch construction form, i.e. the battery cell housing essentially has the shape of a pocket or bag.

[0005] Due to the high requirements on strength or mechanical stability and at the same time on the electrochemical stability with respect to the electrolyte, which is corrosive to the battery cell housing, hitherto, in particular cylindrical battery housings have generally been manufactured from nickel-plated steel. However, more and more battery forms, such as in the field of electrically driven vehicles, 18650-type round cells are increasingly replaced by 21700-type round cells, and it is to be expected that in the future 21700-type round cells will also be replaced by 46800-type round cells, but this puts higher demands on the electrical and thermal conductivity, since more heat is generated, which has to be dissipated. In addition, the potential aluminum material also has to meet the high requirements on the strength of the housing material.

[0006] The concept of using aluminum alloys for cylindrical battery cell housings has already been known, but only for AA3003 aluminum alloys. An example is US 6,258,480 B1. On the other hand, for prismatic battery cell housings, the aluminum alloy AA3003 is the standard material, but the use in the field of prismatic battery housings is also limited to this alloy.

[0007] From US 2006 / 093908 A1 a high-strength battery housing is known, which consists of a composite material having an outer plastic layer and an aluminum foil made of an aluminum alloy of the type AA8079, 1N30, AA8021, AA3003, AA3004, AA3104 or AA3105.

[0008] The same aluminum alloys are also known from KR 2016 0056731 A, although this Korean patent application prefers the use of an aluminum alloy of the type AA3003.

[0009] The Japanese patent application JP 2015 125886 A focuses on the strength and weldability of the battery housing and suggests the use of an aluminum alloy of the type AA3003, AA3203, AA3004, AA3104, AA3005 or AA3105.

[0010] Taking into account the requirements on the strength of the battery cell housing, the stability of the electrolyte, the electrical and thermal conductivity, none of the above documents deals with the problem of recyclability.

[0011] However, in recent years the requirements for sustainability have increased significantly, which requires that battery cell casings must be produced with a CO2 footprint that is as low as possible. The most effective way to reduce the use of energy-intensive primary aluminium is by increasing the use of recycled material, also called secondary aluminium. Secondary aluminium is obtained by melting aluminium scrap. Aluminium scrap is divided into pre-consumer scrap and post-consumer scrap. Pre-consumer scrap is scrap that is generated when semi-finished products or finished products are manufactured from aluminium or aluminium alloys in various possible processing steps. Pre-consumer scrap can be further divided into internal process scrap and external process scrap, internal process scrap being scrap that is inevitably generated in the production process of aluminium strips or aluminium sheets, such as sprues, offcuts, chips, production residues or production rejects, external process scrap being scrap that is inevitably generated in the further processing to form a finished product, such as punching scrap, chips or production rejects. Post-consumer scrap is a finished product that has completed its life cycle and becomes waste after use. It is independent of whether or not it has been used by an end user, which means, for example, that it can also have been used in an industrial or commercial facility. Examples of post-consumer scrap include food packaging, in particular beverage cans, window frames, lithographic printing plate supports, cable cores and car parts.

[0012] According to international specifications, the alloy composition of the AA3003 aluminium alloy used so far for battery cell casings is limited in many respects, for example in terms of the standard alloying elements copper, magnesium, chromium, zinc and titanium. The use of this alloy therefore requires the use of a high proportion of primary aluminium, which hinders the achievement of a high recycling rate. Battery cell casings made of AA3003 aluminium alloy in the prior art therefore need to be improved in terms of sustainability. SUMMARY

[0013] Against this background, it is an object of the present application to provide a battery cell casing having an aluminium alloy strip or sheet which can achieve a high recycling rate while at the same time meeting the requirements for battery cell casings, in particular the requirements in terms of strength, electrolyte stability, electrical conductivity and thermal conductivity.

[0014] It is a further object of the present application to provide a corresponding use of an aluminium alloy strip or sheet for the production of a battery cell casing.

[0015] According to a first teaching of the present application, the above object is solved for a battery cell casing having an aluminium alloy strip or sheet, in that the aluminium alloy strip or sheet has an aluminium alloy with the following alloying constituents in wt.-%:

[0016] 0.1% < Si < 0.5%,

[0017] 0.25% < Fe < 0.8%,

[0018] Cu < 0.6%,

[0019] 0.6% < Mn < 1.4%,

[0020] 0.5% < Mg < 1.5%,

[0021] Cr < 0.25%,

[0022] Zn < 0.4%,

[0023] Ti < 0.2%,

[0024] remainder Al and unavoidable impurities, individual max. 0.05%, total max. 0.15%.

[0025] Surprisingly, the inventors found in experiments that the battery cell housing having the aluminum alloy strip or sheet according to the invention meets the respective requirements, in particular with regard to strength, electrolyte stability, electrical conductivity and thermal conductivity. Most importantly, it was surprisingly found that the electrolyte stability and weldability are not reduced or not substantially reduced compared to the known AA3003 alloy. At the same time, due to the given copper and magnesium content of the aluminum alloy, the battery cell housing according to the invention is suitable for achieving a high recycling rate. This applies in particular to the use of UBC scrap (UBC: used beverage can), i.e. beverage cans made of an aluminum alloy which contains a high amount of magnesium and copper, and the aluminum alloy of the aluminum strip or aluminum sheet which is suitable for producing the battery cell housing. All of the above-mentioned advantages are achieved by the alloy composition of the aluminum alloy strip or sheet of the battery cell housing. Furthermore, since the aluminum alloy contains only standard alloying elements, it can also be well recycled in itself, so that the battery cell housing according to the invention can be smoothly supplied to existing scrap recycling operations.

[0026] According to the application, the silicon content in the aluminum alloy is in the range of 0.1 wt.-% < Si < 0.5 wt.-%. In one embodiment of the battery cell housing according to the application, the silicon content of the aluminum alloy is in the range of 0.2 wt.-% < Si < 0.4 wt.-%, preferably 0.2 wt.-% < Si < 0.35 wt.-%. In combination with the specified iron and manganese contents according to the application, a silicon content of 0.1 wt.-% < Si < 0.5 wt.-% particularly leads to a relatively homogeneous distribution of compact tetravalent α-Al(Fe,Mn)Si phase particles. These precipitated particles both increase the strength of the aluminum alloy and increase its electrical and thermal conductivity, since they remove iron and manganese from the mixed crystal without adversely affecting other properties, such as the corrosion behavior, i.e. the electrolyte stability, or the formability. A silicon content of less than 0.1 wt.-% leads to a reduction in the precipitation of the α-Al(Fe,Mn)Si phase, which can impair the electrical and thermal conductivity due to the dissolution of manganese. Furthermore, the absence of the α-Al(Fe,Mn)Si phase also has a negative effect on tool wear. A silicon content of more than 0.5 wt.-% can form Mg2Si phases in combination with magnesium, which adversely affect the mixed crystal strengthening of the magnesium. The silicon content in the range of 0.2 wt.-% < Si < 0.4 wt.-%, preferably 0.2 wt.-% < Si < 0.35 wt.-% in the above-mentioned embodiment is an ideal compromise between high strength and high electrical and thermal conductivity.

[0027] According to the application, the iron content of the aluminum alloy is in the range of 0.25 wt.-% < Fe < 0.8 wt.-%. In one embodiment of the battery cell housing according to the application, the iron content of the aluminum alloy is in the range of 0.3 wt.-% < Fe < 0.7 wt.-%, preferably 0.4 wt.-% < Fe < 0.7 wt.-%. An iron content of 0.25 wt.-% < Fe < 0.8 wt.-%, in combination with the specified manganese content according to the application, can form Al6(Mn,Fe) phases, and, as described above, in combination with the specified silicon and manganese contents according to the application, can precipitate tetravalent α-Al(Fe,Mn)Si phase particles. In this case, iron helps to reduce the solubility of manganese in aluminum, thereby enabling more manganese to be bound in intermetallic phases, which has a positive effect on the electrical and thermal conductivity. Furthermore, the intermetallic phases also influence the recovery and recrystallization processes and increase the thermal stability of the mechanical properties. An iron content of more than 0.8 wt.-% promotes the formation of coarse intermetallic phases, which can impair the formability during deep-drawing processes. On the other hand, too low an iron content of less than 0.25 wt.-% greatly limits the tolerance of the aluminum alloy to iron-containing scrap, since conventional scrap usually contains a considerable proportion of iron. Thus, too much restriction of the iron content can hinder the achievement of a high recycling rate. Therefore, the iron content in the range of 0.3 wt.-% < Fe < 0.7 wt.-%, preferably 0.4 wt.-% < Fe < 0.7 wt.-% in the above-mentioned embodiment is an ideal combination of recyclability, use of high proportions of recycled material, thermal stability, electrical and thermal conductivity and formability.

[0028] According to the application, the copper content of the aluminum alloy is in the range of Cu < 0.6 wt.-%. In one embodiment of the battery cell housing according to the application, the copper content of the aluminum alloy is in the range of Cu < 0.3 wt.-%, preferably 0.1 wt.-% < Cu < 0.2 wt.-%. By allowing a copper content of up to 0.6 wt.-%, the resistance of the aluminum alloy to copper-containing aluminum alloy scrap can be increased, thus facilitating a high proportion of recycled material in the battery housing manufacturing process.

[0029] However, since a too high copper content can have a negative effect on the corrosion properties, the application limits the copper content to a maximum of 0.6 wt.-% in order to achieve a sufficiently high electrolyte stability. In order to increase the electrolyte stability and sufficiently high electrical and thermal conductivity, the copper content in the above-mentioned embodiment is limited to 0.3 wt.-%. However, the presence of copper also increases the strength of the aluminum alloy by means of mixed crystal strengthening, but only becomes significant above 0.1 wt.-%. Therefore, the preferred range of 0.1 wt.-% < Cu < 0.2 wt.-% represents a compromise between high strength, sufficiently high electrical and thermal conductivity and further increased electrolyte stability and sufficient recycling resistance.

[0030] According to the application, the manganese content in the aluminum alloy is in the range of 0.6 wt.-% < Mn < 1.4 wt.-%. In one embodiment of the battery cell housing according to the application, the manganese content of the aluminum alloy is in the range of 0.8 wt.-% < Mn < 1.1 wt.-%. As described above, a manganese content of 0.6 wt.-% < Mn < 1.4 wt.-%, or 0.8 wt.-% < Mn < 1.1 wt.-%, in combination with the specified amounts of silicon content and iron content, leads to the precipitation of particles of the tetravalent a- Al(Fe,Mn)Si phase and the tetravalent Al6(Mn,Fe) phase. The intermetallic phases impede the recovery and recrystallization process, thus increasing the thermal stability of the mechanical properties. A manganese content below 0.8 wt.-% reduces the strength increase due to dispersion hardening and mixed crystal hardening. A manganese content below 0.6 wt.-% leads to an insufficient strength increase due to dispersion hardening and mixed crystal hardening, while a manganese content exceeding 1.1 wt.-%, in particular exceeding 1.4 wt.-%, promotes the formation of coarse intermetallic phases, which have a negative effect on the formability in deep-drawing processes. Furthermore, a manganese content exceeding 1.1 wt.-%, in particular exceeding 1.4 wt.-%, greatly reduces the electrical and thermal conductivity of the battery cell housing, thus leading to a low thermal management efficiency.

[0031] According to the present application, the magnesium content of the aluminum alloy is in the range of 0.5 wt.-% < Mg < 1.5 wt.-%. In one embodiment of the battery cell housing according to the present application, the magnesium content of the aluminum alloy is in the range of 0.8 wt.-% < Mg < 1.5 wt.-%, preferably 0.8 wt.-% < Mg < 1.2 wt.-%. By allowing a magnesium content of up to 1.5 wt.-%, the tolerance of the aluminum alloy to magnesium containing aluminum alloy scrap, such as UBC scrap, is increased, which further promotes an increase of the proportion of recycled material in the manufacture of the battery cell housing. Furthermore, a magnesium content of more than at least 0.5 wt.-% leads to an effective mixed crystal strengthening, which contributes to an increase of the cold work hardening and thus to an increase of the strength. However, since a too high magnesium content can have a negative effect on the electrical and thermal conductivity, the magnesium content is limited according to the present application to a maximum of 1.5 wt.-%. In order to achieve better mechanical properties, the magnesium content in the above-mentioned embodiment is increased to at least 0.8 wt.-%. The preferred range of 0.8 wt.-% < Mg < 1.2 wt.-% represents a compromise between high strength, good formability and high electrical and thermal conductivity, while having a good recycling tolerance.

[0032] According to the present application, the chromium content of the aluminum alloy is in the range of Cr < 0.25 wt.-%. In one embodiment of the battery cell housing according to the present application, the chromium content of the aluminum alloy is in the range of Cr < 0.1 wt.-%, preferably Cr < 0.05 wt.-%. By allowing a chromium content of up to 0.25 wt.-%, the tolerance of the aluminum alloy to chromium containing aluminum alloy scrap can be increased, which allows a high proportion of recycled material in the manufacture of the battery cell housing. Furthermore, chromium has the effect of increasing the strength and forms a dispersoid, which increases the thermal stability and hinders softening due to recrystallization or recovery. However, since a too high chromium content can have a negative effect on the electrical conductivity of the aluminum alloy, the chromium content is limited according to the present application to a maximum of 0.25 wt.-%. In order to increase the conductivity, while ensuring a sufficient recycling tolerance and strength, the chromium content in the above-mentioned embodiment is limited to 0.1 wt.-%, preferably 0.05 wt.-%.

[0033] According to the application, the zinc content in the aluminum alloy is in the range of Zn < 0.4 wt.%. In one embodiment of the battery cell housing according to the application, the zinc content of the aluminum alloy is in the range of 0.02 wt.% < Zn < 0.25 wt.%, preferably 0.04 wt.% < Zn < 0.25 wt.%. By allowing a zinc content of at most 0.4 wt.%, the resistance of the aluminum alloy to zinc-containing aluminum alloy scrap can be increased, thereby further increasing the recycling rate. In addition, zinc also has the effect of increasing the strength. However, since too high a zinc content can deteriorate the weldability, the electrical and thermal conductivity and the corrosion resistance of the aluminum alloy, the zinc content is limited to at most 0.4 wt.% according to the application. In the above-mentioned embodiment, the zinc content is adjusted in the range of 0.02 wt.% < Zn < 0.25 wt.%, preferably 0.04 wt.% < Zn < 0.25 wt.%, thereby achieving an optimal compromise between high strength, good weldability and good electrolyte stability, while maintaining good recycling resistance.

[0034] According to the application, the titanium content in the aluminum alloy is in the range of 0.005 wt.% < Ti < 0.2 wt.%. In one embodiment of the battery cell housing according to the application, the titanium content of the aluminum alloy is in the range of 0.005 wt.% < Ti < 0.1 wt.%, preferably 0.005 wt.% < Ti < 0.05 wt.%. By allowing a titanium content of at most 0.2 wt.%, the resistance of the aluminum alloy to titanium-containing aluminum alloy scrap can be increased, thereby achieving a high proportion of recycled material in the manufacture of the battery cell housing. However, too high a titanium content can have a negative effect on the formability of the aluminum alloy and significantly reduce the electrical and thermal conductivity, so the titanium content is limited to at most 0.2 wt.% according to the application. Conversely, from a titanium content of 0.005 wt.%, the grain refinement during casting of the aluminum alloy can be improved. Therefore, in order to achieve good formability, good grain refinement, sufficiently high electrical and thermal conductivity and sufficient recycling resistance, the titanium content in the above-mentioned embodiment should be adjusted in the range of 0.005 wt.% < Ti < 0.1 wt.%, preferably 0.005 wt.% < Ti < 0.05 wt.%.

[0035] In addition to the above-mentioned alloying components, the aluminum alloy of the battery cell housing according to the application has aluminum and unavoidable impurities as a remainder. Unavoidable impurities are alloying components which are not intentionally added, but are inevitably contained in the aluminum alloy due to production limitations. According to the application, the content of individual unavoidable impurities is limited to 0.05 wt.% and the sum of the contents of all unavoidable impurities is limited to 0.15 wt.%. This ensures that the unavoidable impurities do not adversely affect the properties of the aluminum alloy, for example by forming undesirable phases, or do not significantly adversely affect the properties.

[0036] In another embodiment of the battery cell housing according to the application, the proportion of recycled material in the aluminum alloy is at least 50% by weight, preferably at least 70% by weight. Due to the high recycling resistance of the aluminum alloy described above, a high recycling proportion of at least 50% by weight, preferably at least 70% by weight, can be achieved with the battery cell housing according to the application. Through the energy-saving measures associated therewith, the battery cell housing can be produced with the smallest possible CO2 footprint and a higher sustainability can be achieved. The aluminum alloy of the battery cell housing according to the application has in particular a proportion of post-consumer scrap of at least 50% by weight, preferably at least 70% by weight. Since the use of post-consumer scrap saves CO2 in particular, the CO2 footprint can be greatly reduced. Additionally or alternatively, a proportion of recycled material of at least 50%, preferably at least 70%, can also be achieved by using pre-consumer scrap, in particular by using internal and / or external process scrap. For internal process scrap, the composition and quantity of the various alloys are generally very well known, so that the alloy composition can be well determined when melting the internal process scrap. The composition of external process scrap is less well defined than that of internal process scrap and can require further processing, but a large amount of external process scrap is produced, for example, in the production of stamped parts, so that its reuse is of great importance from an economic and sustainability perspective. By reusing external process scrap, the demand for primary metal can be reduced, thus lowering the overall CO2 balance.

[0037] In another embodiment of the battery cell housing according to the application, the aluminum alloy strip or sheet has a cold-worked hardening state of the type H1X. In particular, the states H12, H14, H16, H18 and H19 familiar to the person skilled in the art. The aluminum alloy strip or sheet preferably has the cold-worked hardening state H18 or H19. The states described above, in particular H18 and H19, are characterized by a particularly high mechanical stability, thus providing the battery cell housing with a particularly high strength.

[0038] In another embodiment of the battery cell housing according to the application, the aluminum alloy strip or sheet has a thickness of between 0.1 mm and 2.0 mm. In this thickness range, the typical wall thickness of a battery cell housing can essentially be completely covered. Reducing the thickness below 0.1 mm would greatly reduce the mechanical stability of the battery cell housing. Conversely, if the thickness exceeds 2.0 mm, the material cannot be used efficiently. Furthermore, if the aluminum alloy strip or sheet of the battery cell housing has a thickness of more than 2.0 mm, the weight and volumetric energy density of the battery cell or battery module or battery system is greatly reduced. The thickness of the aluminum alloy strip or sheet is preferably between 0.2 mm and 1.5 mm, in particular between 0.35 mm and 1.2 mm.

[0039] In another embodiment of the battery cell housing according to the application, the electrical conductivity σ of the aluminium alloy strip or sheet is at least 35% IACS. In comparison with the battery cell housings made of nickel-plated steel used hitherto, the electrical conductivity is significantly increased, so that the charging times are faster and the electrical losses are lower, whereby the heat generated by the battery cell during operation is also lower. According to the Wiedemann-Franz law, there is a direct relationship between the electrical and thermal conductivity of a metal, so that, with the higher thermal conductivity in comparison with nickel-plated steel, the electrical conductivity is also increased. This enables the waste heat generated by the battery cell during operation to be dissipated more effectively. In addition, the higher thermal conductivity also enables a more uniform temperature distribution in the interior of the battery, which has a positive effect on the ageing of the battery. The electrical conductivity σ of at least 35% IACS thus improves the conduction properties of the battery cell as a whole.

[0040] In another embodiment of the battery cell housing according to the application, the yield strength Rp 0.2 of the aluminium alloy strip or sheet is at least 180 MPa, preferably at least 220 MPa and in particular at least 250 MPa. This enables a high strength to be provided for the battery cell housing. The aluminium alloy strip or sheet preferably already has the above-mentioned yield strength values before it is processed into the battery cell housing, for example in the H16, H18 or H19 state. However, since the processing of the aluminium alloy strip or sheet is usually carried out by cold forming, for example deep drawing, which is usually accompanied by an increase in strength, it can be assumed that the given minimum values for the yield strength also apply to the battery cell housing according to the application in the finished state.

[0041] In another embodiment of the battery cell housing according to the application, the tensile strength Rm of the aluminium alloy strip or sheet is at least 190 MPa, preferably at least 230 MPa and in particular at least 260 MPa. This also enables a high strength to be provided for the battery cell housing. Again, the aluminium alloy strip or sheet preferably already has the above-mentioned tensile strength values before it is processed into the battery cell housing, for example in the H16, H18 or H19 state. Here too, it can be assumed that these values also apply to the battery cell housing according to the application in the finished state.

[0042] In another embodiment of the battery cell housing according to the application, the yield strength Rp 0.2 of the aluminium alloy strip or sheet at a temperature of 100°C is at least 200 MPa. Simultaneously or as an alternative, the yield strength Rp 0.2at least 150 MPa. Since the battery cell is heated to temperatures which are sometimes significantly above room temperature in the event of defects, damage or improper use, the above-mentioned yield limit at 100°C or 200°C also provides a higher thermal stability for the battery cell housing. Likewise, the aluminium alloy strip or sheet, prior to being processed into a battery cell housing, preferably already has the above-mentioned yield limit values at 100°C or 200°C, which can also be considered to apply to the battery cell housing according to the application in the finished state.

[0043] In another embodiment of the battery cell housing according to the application, the aluminium alloy strip or sheet, prior to being processed into a battery cell housing, has a steel-based wall thickness ratio δ of at most 1.6, preferably at most 1.4. The steel-based wall thickness ratio δ is determined by the yield limit Rp 0.2,St of an AISI 1020 type nickel-plated steel strip divided by the yield limit Rp 0.2,Al of the aluminium alloy strip. The yield limit Rp 0.2,St of the steel is determined using a typical value of 350 MPa. In order to derive the wall thickness ratio δ, the internal pressure load scenario relevant in practice for a battery cell housing is considered. For the sake of simplicity, it is assumed that the battery cell housing is a closed thin-walled cylinder. On this basis, the Barlow formula σ φ = p • R i / s is used, where σ φ : stress component in the circumferential direction, p: internal pressure, R i : internal radius, s: wall thickness, and the comparative stress according to is used, which is designed for a load limited by the flow initiation point, i.e. σ V,Tresca ≤ R p0.2 • s p0.2,Al / R Al . Assuming that there is the same maximum internal pressure p = R i • s p0.2,St / R St , Al = R i,St • s i / R p0.2,Al and that the internal radius R Al of the battery is the same, R p0.2,St • s St = R Al • s St , it is possible to calculate the wall thickness ratio δ from the above-mentioned yield limit ratio: δ = s 0.2,St / s 0.2,AlThe steel-based wall thickness ratio δ is a measure of the increase in the wall thickness of the battery cell housing when steel is replaced by aluminum and can be used, inter alia, to compare different aluminum alloy strips or sheets. A δ value according to the application of at most 1.6, preferably at most 1.4, has a positive effect on the volumetric energy density of the battery cell, since the space volume taken up by the aluminum alloy strip or sheet is thus minimized while maintaining the same mechanical stability. Furthermore, by limiting the wall thickness ratio in combination with the low density of aluminum compared to steel, the gravimetric energy density can be maximized.

[0044] In a further embodiment of the application of the battery cell housing according to the application, the aluminum alloy strip or sheet, prior to being processed into a battery cell housing, has an average percentage burr height Z of at most 4%, preferably at most 3% Z, preferably a maximum percentage burr height Z of at most 6%, preferably at most 5.5% max The burr characteristic values Z and Z max are determined in the burr test according to DIN EN 1669 using a round blank with a diameter of 60 mm, a punch diameter of 33 mm and the lubricant lanolin. An average percentage burr height Z of at most 4%, preferably at most 3%, and preferably a maximum percentage burr height Z of at most 6%, preferably at most 5.5% are achieved max so that the aluminum alloy strip or sheet is very well suited for deep drawing, in which only little waste material is produced during the process, so that the battery cell housing according to the application can be manufactured efficiently.

[0045] According to a second teaching of the application, the above object is solved for the application of the aluminum alloy strip or sheet for the manufacture of a battery cell housing, in that the aluminum alloy strip or sheet is used for the manufacture of a battery cell housing according to the first teaching of the application. Since the aluminum alloy strip or sheet has the above-mentioned advantageous properties, an improved battery cell housing compared to the prior art can be provided.

[0046] In an embodiment of the application of the application, the battery cell housing is a housing of a secondary battery, preferably a lithium-ion secondary battery or a sodium-ion secondary battery. Since secondary batteries, in particular lithium-ion secondary batteries, are currently being used more and more in the field of electric vehicles and consumer electronics, the advantageous properties of the aluminum alloy strip or sheet used according to the application can be used in particular for such battery cells. This also applies to sodium-ion secondary batteries, which are currently still mainly a subject of research and, due to better economics and better availability of sodium, can replace lithium-ion secondary batteries in the future in certain applications. The application of the battery cell housing according to the application also particularly includes a housing for a solid-state secondary battery with a solid-state electrolyte.

[0047] In another embodiment of the use according to the application, the battery cell housing adopts a cylindrical configuration, a prismatic configuration or a pouch configuration. Thus, the advantageous properties of the aluminum alloy strip or sheet used according to the application can be used for all currently conventional configuration forms of battery cell housings.

[0048] In another embodiment of the use according to the application, the method for producing the aluminum alloy strip or sheet comprises the following steps:

[0049] casting of the ingot from an aluminum alloy,

[0050] homogenization of the ingot,

[0051] hot rolling of the ingot to a hot-rolled strip,

[0052] cold rolling of the hot-rolled strip.

[0053] The above-mentioned method steps are preferably carried out in the order given, in which case the homogenization of the ingot can be carried out separately or integrated into the preheating of the ingot for hot rolling. It has been found that an aluminum alloy strip or sheet can be produced using the above-mentioned method, which can meet the requirements of battery cell housings, in particular with regard to strength, electrolyte stability, electrical and thermal conductivity, when used in the use according to the application, while at the same time a high recycling rate can be achieved. In addition, this method also enables the economical production of aluminum alloy strips or sheets.

[0054] The aluminum alloy is preferably cast as an ingot in a direct-chill casting, also known as Direct-Chill casting or DC casting, which further improves the economy of the production method.

[0055] By homogenizing the ingot, the microstructure of the aluminum alloy strip or sheet can be improved, which has a positive effect on the strength and formability. The homogenization is preferably carried out at a temperature of 480 °C to 620 °C, in particular 550 °C to 610 °C, for a duration of at least 0.5 h, preferably at least 1 h, in particular at least 2 h.

[0056] The hot rolling of the ingot to form the hot rolled strip is preferably carried out at a temperature of 280 °C to 550 °C, wherein the hot rolled strip temperature after the last hot rolling pass is between 280 °C and 380 °C, preferably between 310 °C and 360 °C. The hot rolling of the ingot can be carried out in a back-and-forth manner on rolling stands or in a sequential manner on sequential stands. The hot rolling can in particular be carried out in a back-and-forth manner when the slab thickness is between 20 mm and 50 mm, and then the slab is rolled to the hot rolled strip thickness on sequential stands. The hot rolled strip thickness, i.e. the thickness of the hot rolled strip, is in one embodiment of the method between 1 mm and 15 mm, preferably between 2 mm and 12 mm, in particular between 2 mm and 9 mm. This allows a sufficiently high rolling rate in the subsequent cold rolling process, so that the strength, formability, crystallographic texture and the tip profile of the aluminium alloy strip or sheet can be adjusted.

[0057] The cold rolling of the aluminium alloy strip or sheet can be carried out in one or more passes. In one embodiment of the method, in which the method is carried out with a plurality of cold rolling passes, at least one intermediate annealing can be carried out selectively during the cold rolling process. In one embodiment of the method, the intermediate annealing is carried out in a temperature range of 150 °C to 450 °C, preferably 200 °C to 400 °C, in particular 300 °C to 400 °C. The intermediate annealing is preferably carried out in the form of a recrystallisation annealing, so that a recrystallised microstructure is provided for the subsequent cold rolling pass. A higher rolling rate can be used during the cold rolling process, so that the strength of the finished aluminium alloy strip or sheet is increased. Alternatively, a recovery annealing can also be used instead of a recrystallisation annealing, so that the degree of hardening is reduced.

[0058] In one embodiment of the method, the rolling rate during the cold rolling to the final thickness is at least 20 %, preferably at least 50 %, in particular at least 70 %. If the method is carried out with intermediate annealings during the cold rolling, the rolling rate of the cold rolling to the final thickness after the last intermediate annealing is at least 20 %, preferably at least 50 %, in particular at least 70 %. By providing a rolling rate of at least 20 %, preferably at least 50 %, in particular at least 70 %, during the cold rolling to the final thickness, the strength of the produced aluminium alloy strip or sheet can be increased, so that it is particularly suitable for the applications according to the application. Due to the higher rolling rate, a tip (Zipfelbildung) can be formed at a 45° position. However, the tip formation can be compensated for by selecting the hot rolling parameters such that a recrystallised hot rolled strip is produced which forms a tip at a 0° / 90° position, so that the tip formation at the 45° position can be compensated for. This allows the average percentage tip height Z and the maximum percentage tip height Z max so that the productivity of the deep-drawing process is positively influenced and the amount of rejects produced in the deep-drawing process is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0059] The application will be explained in more detail below with the help of examples and with reference to the drawings. In the drawings

[0060] Figure 1 A schematic view of a cylindrical battery cell with a battery cell housing according to the application is shown,

[0061] Figure 2 A schematic view of a prismatic battery cell with a battery cell housing according to the application is shown,

[0062] Figure 3 A schematic view of a pouch construction battery cell with a battery cell housing according to the application is shown, and

[0063] Figure 4 A flow chart of a method for producing an aluminum alloy strip or sheet for use according to the application is shown. DETAILED DESCRIPTION

[0064] Figure 1 A schematic view of a battery cell 10 of cylindrical construction is shown. The battery cell 10 has a battery cell housing 11 according to the application and in addition an anode connection 12 and a cathode connection 13.

[0065] Figure 2 A schematic view of a battery cell 20 of prismatic construction is shown. The battery cell 20 has a battery cell housing 21 according to the application and in addition an anode connection 22 and a cathode connection 23.

[0066] Figure 3 A schematic view of a battery cell 30 of pouch construction is shown. The battery cell 30 has a battery cell housing 31 according to the application and in addition an anode connection 32 and a cathode connection 33.

[0067] Figure 4 A flow chart of a method 40 for producing an aluminum alloy strip or sheet for use according to the application is shown. The method 40 comprises the following steps:

[0068]

[0069] - casting 42 an ingot from an aluminum alloy,

[0070] - homogenizing 44 the ingot,

[0071] - hot rolling 46 the ingot to a hot rolled strip,

[0072] - cold rolling 48 the hot rolled strip.

[0073] ​Within the scope of this invention, seven aluminum alloy strips were manufactured from different aluminum alloys, hereinafter referred to as strips 1 to 7. The alloy compositions of strips 1 to 7 are shown in Table 1 below. The content of each alloying element is expressed in weight % (%). The remainder, i.e., the difference from 100% by weight, consists of aluminum and unavoidable impurities, with a maximum individual impurity content of 0.05% by weight and a maximum total of 0.15% by weight. Strips 1, 2, 3, and 7 are embodiments of the invention, having alloy compositions according to the invention, wherein the alloy compositions of strips 1 and 2 are identical. Conversely, strips 4, 5, and 6 are comparative examples, with an aluminum alloy type of AA3003.

[0074] Table 1

[0075] Strip Si Fe Cu Mn Mg Cr Zn Ti 1 (Invention) 0.25 0.59 0.18 0.84 1.03 0.01 0.04 0.02 2 (Invention) 0.25 0.59 0.18 0.84 1.03 0.01 0.04 0.02 3 (Invention) 0.23 0.59 0.18 0.82 1.03 0.01 0.04 0.03 4 (Comparison) 0.12 0.57 0.14 0.99 0.01 <0.01 0.01 0.01 5 (Comparison) 0.20 0.53 0.14 1.05 <0.01 <0.01 <0.01 0.02 6 (Comparison) 0.47 0.53 0.11 1.18 <0.01 <0.01 <0.01 0.02 7 (Invention) 0.14 0.30 0.52 1.18 0.63 <0.01 <0.01 0.02

[0076] Aluminum alloy strip 1 to 7 and so on Figure 4 The method shown is used for production. Specifically, ingots are cast using the corresponding aluminum alloys in a direct-cooling continuous casting machine. Here, when manufacturing ingots of strips 1, 2, 3, and 7 according to the invention, the proportion of recycled material selected is at least 70%. The maximum recycling proportion for comparative examples 4, 5, and 6 is 30%. The ingots are homogenized after casting and then hot-rolled into hot-rolled strips. The hot-rolled strips are then cold-rolled to a final thickness between 0.5 mm and 1.0 mm. Table 2 below lists the various method parameters for producing strips 1 to 7. Specifically, these include the thickness of the hot-rolled strip, i.e., the corresponding thickness of the hot-rolled strip, the temperature, duration, and strip thickness parameters of the selective intermediate annealing during cold rolling, and the rolling rate during cold rolling to the final thickness.

[0077] Table 2

[0078]

[0079] As can be seen from Table 2, strips 1 to 3 according to the present invention were not subjected to intermediate annealing during production, while strip 7 according to the present invention and comparative strips 4 to 6 were subjected to intermediate annealing, especially recrystallization annealing, during production. Strip 2 underwent final annealing after cold rolling at a temperature of 250°C for a holding time of 2 hours.

[0080] Subsequently, various performance tests related to the battery cell casing were performed on the aluminum alloy strip. Table 3 summarizes these test results. Table 3 details the material state, thickness d (as the final thickness after cold rolling), electrical conductivity σ, and yield strength R of strips 1 to 7. p0.2 Tensile strength R m Based on the steel's wall thickness ratio δ, average percentage tip height Z, and maximum percentage tip height Z... max Yield limit R p0.2 and tensile strength R mare determined according to DIN EN ISO 6892-1. The steel-based wall thickness ratio δ is derived based on the yield limit Rp0.2 of 350 MPa typical for AISI 1020 type nickel-plated steel strip

[0081] 6892-1. The steel-based wall thickness ratio δ is derived based on the yield limit Rp0.2 of 350 MPa typical for AISI 1020 type nickel-plated steel strip 0.2，St of the respective yield limit Rp0.2 of the aluminum alloy strips 1 to 7 0.2 Al The average percentage cup height Z and the maximum percentage cup height Z max .

[0082] Table 3

[0083]

[0084] As shown in Table 3, the strips 1, 2, 3 and 7 according to the application achieve a yield limit and a tensile strength which are higher than the yield limit and the tensile strength of the comparative strips 4, 5 and 6 made of AA3003 aluminum alloy. The cold work-hardened state H1X, in particular the H18 or H19 state, has a further positive effect on the strength, as shown by the comparison between the strips 1, 2, 3 and 7 according to the application. Thus, the yield limit and the tensile strength of the strip 2 having the same alloy composition (see Table 1) as the strip 1 but being in the cold work-hardened and annealed state H24, although higher than those of the comparative strips 3, 4 and 5, are lower than those of the strip 1 being in the cold work-hardened state H18 only.

[0085] As shown in Table 3, the strips 1, 2, 3 and 7 according to the application achieve a yield limit and a tensile strength which are higher than the yield limit and the tensile strength of the comparative strips 4, 5 and 6 made of AA3003 aluminum alloy. The cold work-hardened state H1X, in particular the H18 or H19 state, has a further positive effect on the strength, as shown by the comparison between the strips 1, 2, 3 and 7 according to the application. Thus, the yield limit and the tensile strength of the strip 2 having the same alloy composition (see Table 1) as the strip 1 but being in the cold work-hardened and annealed state H24, although higher than those of the comparative strips 3, 4 and 5, are lower than those of the strip 1 being in the cold work-hardened state H18 only. p0.2 at least 180 MPa, and a tensile strength Rm m at least 190 MPa. Thus, they are particularly suitable for the manufacture of the battery cell housing according to the application. Although the values for the yield limit and the tensile strength shown in Table 3 apply to the strips 1, 2, 3 and 7 before the machining to form the battery cell housing, it can be assumed that the battery cell housing manufactured from the strips 1, 2, 3 and 7 has at least equally high values in the finished state. This is because the machining, which is usually carried out by cold forming, for example deep drawing and punching, is usually accompanied by an increase in strength.

[0086] In addition to the yield limit at room temperature in Table 3, the yield limit at 100°C and the yield limit at 200°C of the strip 3 according to the application and the comparative strip 4 were determined in accordance with DIN EN ISO 6892-2. Here, the yield limit at 100°C of the strip 3 according to the application amounted to a value of 270 MPa and the yield limit at 200°C amounted to a value of 161 MPa. The comparative strip 4 amounted to a value of 151 MPa at 100°C and to a value of 92 MPa at 200°C. Since in the event of defects, damage or improper use, the battery cell can be heated to temperatures which are sometimes significantly above room temperature, the strip 3 according to the application is particularly suitable for the production of a battery cell housing according to the application due to its significantly higher thermal stability than the comparative strip 4. Although the above-mentioned yield limit values at 100°C and 200°C apply to the strip 3 before it is processed to form a battery cell housing, it can again be assumed that a battery cell housing produced from the strip 3 has at least equally high values in the finished state.

[0087] As further shown in Table 3, the strips 1, 3 and 7 according to the application have a wall thickness ratio δ of the steel of at most 1.6. This value has a positive effect on the volumetric and gravimetric energy density of the finished battery cell when using the above-mentioned strips for the production of a battery cell housing according to the application, since the space volume occupied by the aluminum alloy strip and the weight of the battery cell are thus minimized while maintaining the same mechanical stability. The strips 1, 3 and 7 according to the application are therefore particularly suitable for the production of a battery cell housing according to the application.

[0088] As further shown in Table 3, the strips 1, 2 and 3 according to the application have an average percentage tip height Z of at most 4% and a maximum percentage tip height Z max of at most 6%. For this reason, they are very suitable for deep drawing, thus minimizing the amount of scrap when producing a battery cell housing according to the application. The values for Z and Z max are comparable or slightly better than those of the comparative strips 4, 5 and 6.

[0089] As further shown in Table 3, the electrical conductivity s of the strip materials 1, 2, 3 and 7 according to the present application is at least 35% IACS. In comparison to the battery cell housings made of nickel-plated steel used so far, its electrical conductivity is significantly improved, thus enabling faster charging times, lower electrical losses and thus reducing the heating of the battery cell during operation. Although the electrical conductivity s of the strip materials 1, 2, 3 and 7 according to the present application is slightly lower than that of the comparative strip materials 4, 5 and 6, it fully still meets the requirements for a battery cell housing. According to the Wiedemann-Franz law, there is a direct correlation between the electrical and thermal conductivity of a metal, so similar considerations apply to the thermal conductivity. In comparison to nickel-plated steel, the thermal conductivity of the aluminum alloy strip material according to the present application is improved, which significantly increases the cooling efficiency of the battery cell, especially at high C-rates occurring during fast charging, and also enables a more uniform temperature distribution over the coil, thus limiting the aging of the battery cell.

[0090] As further shown in Table 3, the thickness of the strip materials 1, 2, 3 and 7 according to the present application is between 0.1 mm and 2.0 mm. Thus, in the application for producing a battery cell housing according to the present application, a good compromise between mechanical stability and efficient use of the material is achieved. Furthermore, the weight and volumetric energy density of the respective battery cell or battery module or battery system is not reduced too much.

[0091] The corrosion behavior of the strip material 3 according to the present application and the comparative strip material 4 was evaluated exemplarily by means of cyclic polarization measurements according to DIN 50918:2018-09 using a lithium hexafluorophosphate electrolyte. First, the resting potential of the pickled and degreased strip material in the electrolyte was determined, then the following polarization was carried out:

[0092] 1. Polarization of the resting potential in the cathodic direction by 600 mV at 1 mV / s,

[0093] 2. Polarization in the anodic direction from the cathodic region to a potential corresponding to a corrosion current of 1 mA / cm 2 at 1 mV / s,

[0094] 3. Reverse polarization in the cathodic direction at 1 mV / s.

[0095] The evaluation of the measurement results leads to the characteristic values for characterizing the corrosion behavior shown in Table 4. Table 4 lists in detail the cathodic current density, exchange current density and polarization resistance. As shown in the table, the strip material 3 according to the present application and the comparative strip material 4 have almost the same cathodic current density, exchange current density and polarization resistance, so the strip material 3 according to the present application meets the requirements for electrolyte stability as the comparative strip material 4, which has the typical alloy state combination of the prismatic battery cell housings of the prior art.

[0096] Table 4

[0097]

[0098]

[0099] Since the electrolyte stability is mainly determined by the chemical composition and the chemical composition of the strips 1, 2, 3 and 7 according to the application and the comparative strips 4, 5 and 6 are very similar, respectively, the cyclic polarization measurements according to the DIN 50918:2018-09 standard generally show that the electrolyte stability of the strips 1, 2, 3 and 7 according to the application is essentially the same as the electrolyte stability of the comparative strips 4, 5 and 6 made of the aluminum alloy AA3003. Thus, the strips produced according to the application also meet the requirements for electrolyte stability and are therefore suitable for use in the production of the battery cell housings according to the application.

[0100] Due to the just described advantageous properties of the strips 1, 2, 3 and 7 according to the application, in particular of the strips 1 and 3, they are particularly suitable for use in the application of the battery cell housings according to the application. In this way, it is possible to produce battery cell housings according to the application as Figures 1 to 3 exemplarily shown.

[0101] Figures 1 to 3 The battery cells (10, 20, 30) shown can be secondary batteries, in particular lithium-ion secondary batteries or sodium-ion secondary batteries, so that the battery cell housings (11, 21, 31) according to the application are secondary battery housings, in particular housings for lithium-ion secondary batteries or sodium-ion secondary batteries, respectively. The advantageous properties of the aluminum alloy strips used according to the application are therefore particularly suitable for these types of battery cells.

[0102] In addition, the battery cell housings (11, 21, 31) according to the application shown can in particular adopt a cylindrical configuration, a prismatic configuration or a pouch configuration. Figures 1 to 3 Figure 1 shown is a cylindrical configuration of a battery cell housing (11) according to the application; Figure 2 shown is a prismatic configuration of a battery cell housing (21) according to the application; Figure 3 shown is a pouch configuration of a battery cell housing (31) according to the application. The advantageous properties of the aluminum alloy strips used according to the application can therefore be used in all currently typical battery cell housing configurations.

[0103] In addition, as Figures 1 to 3 ​The proportion of recycled material in the aluminium alloy material used for the battery cell housing (11, 21, 31) according to the application is preferably at least 50%, preferably at least 70%. The recycling proportion is preferably achieved by using post-consumer scrap. By means of the associated energy-saving measures, the battery cell housing can be produced with the smallest possible CO2 footprint and the sustainability of the battery cell housing is increased. This is possible because the alloy composition of the battery cell housing (11, 21, 31) according to the application is very well suited to achieving a high recycling proportion. Additionally or alternatively, the recycling proportion can also be achieved by using internal or external process scrap, which likewise reduces the CO2 footprint compared to the production based on primary aluminium.

Claims

1. A battery cell housing in cylindrical or prismatic configuration and having an aluminum alloy strip or sheet, characterized in that the aluminum alloy strip or sheet has an aluminum alloy with the following alloying constituents in weight %: 0.1 % < Si < 0.5 %, 0.25 % < Fe < 0.8 %, Cu < 0.6 %, 0.6 % < Mn < 1.4 %, 0.5 % < Mg < 1.5 %, Cr≤0.25％， Zn < 0.4 %, 0.005 % < Ti < 0.2 %, the remainder being Al and unavoidable impurities, max. 0.05 % each, max. 0.15 % in total, and the proportion of recycled material in the aluminum alloy being at least 50 %, wherein the electrical conductivity σ of the aluminum alloy strip or sheet is at least 35 % IACS.

2. The battery cell housing according to claim 1, characterized in that the aluminum alloy strip or sheet has an aluminum alloy with the following alloying constituents in weight %: 0.2 % < Si < 0.4 %, 0.3 % < Fe < 0.7 %, Cu < 0.3 %, 0.8 % < Mn < 1.1 %, 0.8 % < Mg < 1.5 %, Cr≤0.1％， 0.02 % < Zn < 0.25 %, 0.005 % < Ti < 0.1 %, the remainder being Al and unavoidable impurities, max. 0.05 % each, max. 0.15 % in total.

3. The battery cell housing according to claim 2, characterized in that 0.2 % < Si < 0.35 %.

4. The battery cell housing according to claim 2, characterized in that 0.4 % < Fe < 0.7 %.

5. The battery cell housing according to claim 2, characterized in that 0.1 % < Cu < 0.2 %.

6. The battery cell housing according to claim 2, characterized in that 0.8 % < Mg < 1.2 %.

7. The battery cell housing according to claim 2, characterized in that Cr≤0.05％。 8. The battery cell housing according to claim 2, characterized in that 0.04 % < Zn < 0.25 %.

9. The battery cell housing according to claim 2, characterized in that 0.005 % < Ti < 0.05 %.

10. The battery cell housing according to claim 1, characterized in that the proportion of recycled material in the aluminum alloy is at least 70 %.

11. The battery cell housing according to claim 1, characterized in that the aluminum alloy strip or sheet has a cold-worked hardening state of type H1X, or is in a cold-worked hardening state of type H18 or H19.

12. The battery cell housing according to claim 1, characterized in that the aluminum alloy strip or sheet has a thickness of between 0.1 mm and 2.0 mm.

13. The battery cell housing according to claim 12, characterized in that the aluminum alloy strip or sheet has a thickness of between 0.2 mm and 1.5 mm.

14. The battery cell housing according to claim 12, characterized in that the aluminum alloy strip or sheet has a thickness of between 0.35 mm and 1.2 mm.

15. The battery cell housing according to claim 1, characterized in that The aluminum alloy strip or sheet has a yield strength Rm measured according to DIN EN ISO 6892-1 of at least 180 MPa. p0.2 at least 180 MPa.

16. The battery cell housing according to claim 15, characterized in that The aluminum alloy strip or sheet has a yield strength Rm measured according to DIN EN ISO 6892-1 of at least 220 MPa. p0.2 at least 220 MPa.

17. The battery cell housing according to claim 15, characterized in that The aluminum alloy strip or sheet has a yield strength Rm measured according to DIN EN ISO 6892-1 of at least 250 MPa. p0.2 250 MPa.

18. The battery cell housing according to claim 1, characterized in that The yield strength R at a temperature of 100°C of the aluminium alloy strip or sheet p0.2 is at least 200 MPa, and / or the yield strength R at a temperature of 200°C p0.2 is at least 150 MPa.

19. The battery cell housing according to claim 1, characterized in that the aluminum alloy strip or sheet prior to its processing into a battery cell housing has a steel-based wall thickness ratio δ of at most 1.

6.

20. The battery cell housing according to claim 1, characterized in that the aluminum alloy strip or sheet prior to its processing into a battery cell housing has a steel-based wall thickness ratio δ of at most 1.

4.

21. The battery cell housing according to claim 1, characterized in that The aluminum alloy strip or sheet has an average percentage tip height Z of at most 4% or a maximum percentage tip height Z of at most 6% in a tip test according to DIN EN 1669 before it is processed into a battery cell housing. max at most 6%.

22. The battery cell housing according to claim 21, characterized in that the aluminum alloy strip or sheet prior to its processing into a battery cell housing has an average percentage tip height Z of at most 3% in a tip test according to DIN EN 1669.

23. The battery cell housing according to claim 21, characterized in that The aluminum alloy strip or sheet, prior to its processing into a battery cell housing, has a maximum percentage tip height Z in a tip test according to DIN EN 1669 max 5.5%.

24. Use of an aluminum alloy strip or sheet for the manufacture of a battery cell housing according to any one of claims 1 to 23.

25. The use according to claim 24, characterized in that the battery cell housing is a housing of a secondary battery cell.

26. The use according to claim 25, characterized in that the battery cell housing is a housing of a lithium-ion secondary battery cell, a sodium-ion secondary battery cell or a solid-state secondary battery cell.

27. The use according to claim 24, characterized in that the battery cell housing adopts a cylindrical configuration, a prismatic configuration.

28. The use according to claim 24, characterized in that the aluminum alloy strip or sheet is produced by a manufacturing method comprising the following steps: - casting (42) an ingot from an aluminum alloy, - homogenizing (44) the ingot, - hot rolling (46) the ingot into a hot rolled strip, - cold rolling (48) the hot rolled strip.

29. The use according to claim 28, characterized in that the hot rolled strip has a thickness between 1 mm and 15 mm.

30. The use according to claim 29, characterized in that the hot rolled strip has a thickness between 2 mm and 12 mm.

31. The use according to claim 29, characterized in that the hot rolled strip has a thickness between 2 mm and 9 mm.

32. The use according to claim 28, characterized in that at least one intermediate annealing is performed during the cold rolling process.

33. The use according to claim 28, characterized in that the rolling reduction during the cold rolling to the final thickness is at least 20%.

34. The use according to claim 33, characterized in that the rolling reduction during the cold rolling to the final thickness is at least 50%.

35. The use according to claim 33, characterized in that the rolling reduction during the cold rolling to the final thickness is at least 70%.

36. The use according to any one of claims 33 to 35, characterized in that the rolling reduction during the cold rolling to the final thickness is the rolling reduction after the last intermediate annealing.

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