Cylindrical battery cell housing with small co2 footprint

Abstract

The invention relates to a cylindrical battery cell housing having an aluminum material, to a method for producing a cylindrical battery cell housing, and to the use of an aluminum material in order to produce a cylindrical battery cell housing. The aim of the invention is to provide a cylindrical battery cell housing with a CO2 footprint which is reduced in comparison to the current reference material steel, said cylindrical battery cell housing simultaneously allowing an improved heat conduction and a reduced weight of the battery cell. This is achieved in that the cylindrical battery cell housing has an aluminum material in which the ratio of the carbon dioxide (CO2e) quantity emitted during the production of the aluminum material, in kgCO2e per kgAl material , to the yield point Rp0.2 of the aluminum material, in MPa, of CO2e / Rp0.2 is ≤ 1.9% kgCO2e / (MPa*kgAl material).

Description

[0001] March 28, 2024 Cylindrical battery cell housing with a low CO2 footprint The invention relates to a cylindrical battery cell housing comprising an aluminum material, a method for producing a cylindrical battery cell housing, and a use of an aluminum material for producing a cylindrical battery cell housing. Battery cells can fundamentally be divided into primary cells, which can only be discharged once and cannot be recharged, and secondary cells, which are rechargeable. For both primary and secondary cells, the necessary electrochemical processes that enable the battery cell to function can be realized using a variety of different materials. Examples of primary cells in this context include alkaline manganese cells, zinc carbon cells, nickel oxyhydroxide cells, or lithium iron sulfide cells, to name just a few.Examples of secondary cells include lithium-ion cells, sodium-ion cells, nickel-cadmium cells, nickel-metal hydride cells, and nickel-zinc cells, to name just a few. Lithium-ion secondary cells have been increasingly used in recent years, particularly in the fields of electromobility and consumer electronics, due, among other things, to their comparatively high gravimetric and volumetric energy density. Like other types of battery cells, lithium-ion secondary cells have a battery cell casing. This forms the outer shape of the battery cell and encloses a cavity containing, among other things, the anode material, the cathode material, and an electrolyte. Different battery cell casing designs can be distinguished: Cylindrical battery cell casings essentially have the shape of a cylinder.If the height of the cylinder is greater than the diameter, they are called round cells; otherwise, they are called button cells. Prismatic battery cell housings are essentially shaped like a prism, especially a cuboid. Another variant is the pouch design, in which the battery cell housing is essentially shaped like a pocket or bag. Due to high demands on strength and mechanical stability, as well as high demands on electrochemical resistance to the electrolyte, which has a corrosive effect on the battery cell housing, cylindrical battery cell housings in particular have so far generally been made of nickel-plated steel. The dominant round battery cell format is the 18650 type with an 18 mm diameter. These are being replaced in various applications by 21 mm round battery cells of the 21700 type.However, a substitution of type 21700 battery cells with 46 mm diameter battery cells of type 46800 is also expected, for example in the field of electromobility. The growing cell formats place greater demands on the dissipation of heat generated inside the battery cell and thus on the electrical and thermal conductivity of the battery cell housing. Approaches to using aluminum alloys for cylindrical battery cell housings are already known, but are limited to the aluminum alloy AA3003. For example, a battery cell housing with an outer diameter of 13.8 mm and a height of 49.0 mm is known from US patent US 6,258,480 B1. The battery cell housing was manufactured by deep drawing and stretch drawing from a round blank of an aluminum alloy sheet made of an aluminum alloy of type AA3003.While in battery cell housings with smaller cross-sections the mechanical stability of the battery cell housing results essentially from the rigidity of the geometric shape as a cylinder, in the case of larger cross-sections of the round battery cells from 15 mm outer diameter the yield strength Rp0.2Z plays an increasing role. I / ZI 230340WOMarch 28, 2024, the material of the battery cell housing plays a role. In terms of mechanical strength, nickel-plated steel, which is well-known as a material for battery cell housings, serves as a reference. A typical yield strength Rp0.2 of 350 MPa is assumed for nickel-plated steel strips of type AISI1020. The use of lithium-ion secondary cells for storing electrical energy represents a key technology in combating global climate change, as they enable highly efficient and economical storage of electrical energy. At the same time, the production of lithium-ion secondary cells causes greenhouse gas emissions, which are quantified using CO2 equivalents (CO2e). Therefore, whenever greenhouse gas emissions or greenhouse gas emissions are mentioned below, this always refers to their CO2 equivalents (CO2e).According to a European battery manufacturer from 2021, approximately 10% of greenhouse gas emissions are caused by the provision of the mechanical components of a battery cell alone, in this case, the battery cell casing. For the nickel-plated steel strips previously used for cylindrical battery cell casings, a greenhouse gas emission value of 2.4 kgCO2e / kgSt is known from the literature. However, steel has a density of 7.80 g / cm³ compared to 2.7 g / cm³ for aluminum. Compared to steel, aluminum has the disadvantage of lower strength and a higher CO2 footprint per kg, which for primary metal is 8.6 kgCO2e / kgAl material, which is the average for primary metal consumed in the EU. Primary aluminum is aluminum produced directly from the raw material bauxite or from the alumina extracted from it. Because it is produced in aluminum smelters, it is also referred to as primary aluminum.Taking into account the greenhouse gas emissions from the production of the primary metal at 8.6 kgCO2e / kgAl material, between 3 and 4% of the greenhouse gas emissions from primary aluminum-based aluminum material are currently attributable to the production of the battery cell housing. I / ZI 230340WOMarch 28, 2024. However, it is planned to reduce greenhouse gas emissions during battery cell production by a factor of 10, from the current level of approximately 100 kgCO2e / kWh to approximately 10 kgCO2e / kWh. This could increase the share of greenhouse gas emissions from the battery cell housing per kWh when using an aluminum material to as much as 30 to 40% of the greenhouse gas emissions of the entire battery cell per kWh, provided the share of greenhouse gas emissions or CO2 equivalents from the battery cell housing is not reduced. In contrast, the reference material steel has lower greenhouse gas emissions per kg. Although steel accounts for a smaller share of total emissions from battery cell production, it poses significant disadvantages for battery applications, for example, in electric vehicles, in terms of weight and thermal management of the battery cell.The report "ENVIROMENTAL PROFILE REPORT, Life-Cycle Inventory Data for Aluminum Production and Transformation Processes in Europe, February 2018" (https: / / european-aluminium.eu / wp-content / uploads / 2023 / 01 / European-Aluminium_Environmental-Profile-Report-2018_full-version.pdf) identifies the greenhouse gas emissions emitted during the production of aluminum and aluminum alloy products in Europe, quantified as CO2 equivalents (CO2e) in kgCO2e. The CO2 equivalents in the report were determined according to the ISO 14040 and 14044 standards. These standards therefore provide a predefined procedure for determining CO2 equivalents. The identical standards were used to determine CO2 equivalents in other regions, for example for aluminum production in North America in the report "The Environmental Footprint of Semi-Fabricated Aluminum Products in North America, A Life Cycle Assessment Report" by the Aluminum Association (https: / / www.aluminum.org / sites / default / files / 2022-01 / 2022_Semi-Fab_LCA_Report.pdf). Michael Zotter's diploma thesis entitled "Life-Cycle Analysis of Lightweight Construction Concepts for Automotive Engineering", TU Graz from April 2014, is also based on Z. I / ZI 230340WOMarch 28, 2024, the international standards ISO 14040 and ISO 14044 for determining CO2 equivalents. In the professional world, CO2 equivalents are therefore determined according to the two aforementioned standards. All CO2 equivalents in kgCO2e mentioned below therefore refer in particular to CO2 equivalents in kgCO2e determined according to ISO 14040 and ISO 14044. Based on this, the present invention is based on the object of providing a cylindrical battery cell housing with a reduced CO2 footprint compared to the current reference material, which simultaneously enables improved thermal conduction and a lower weight of the battery cell. Furthermore, a method for producing the battery cell housing is to be specified and an aluminum material for use in the production of cylindrical battery cell housings is to be proposed.According to the invention, the above-mentioned object is achieved for a cylindrical battery cell housing comprising an aluminum material in that the cylindrical battery cell housing comprises an aluminum material whose ratio of the amount of carbon dioxide (CO2e) emitted during the production of the aluminum material in kgCO2e per kgAl material to the yield strength Rp0.2 of the aluminum material in MPa is CO2e / Rp0.2 ≤ 1.9% kgCO2 / (MPa*kgAl material), preferably CO2e / Rp0.2 ≤ 1.8% kgCO2 / (MPa*kgAl material), more preferably CO2e / Rp0.2 ≤ 1.6% kgCO2 / (MPa*kgAl material), particularly preferably CO2e / Rp0.2 ≤ 1.2% kgCO2e / (MPa*kgAl material) or CO2e / Rp0.2 ≤ 1.0% kgCO2e / (MPa*kgAl material), whereby the yield strength Rp0.2 is measured according to DIN EN ISO 6892-1 at room temperature.It has been found that using an aluminum material with a CO2e / Rp0.2 ratio of maximum 1.9% kgCO2e / (MPa*kgAl material) can achieve a reduction in greenhouse gas emissions in the production of battery cell casings of about 4%Z. I / ZI 230340WOMarch 28, 2024 compared to the reference material steel, so that both a reduction in greenhouse gas emissions for the production of the battery cell housing and a battery cell with improved thermal conduction at a lower weight can be provided. The claimed CO2e / Rp0.2 ratio can be used to achieve the savings in greenhouse gas emissions in CO2 equivalents (CO2e) per kg of the aluminum material, regardless of the aluminum alloy classification and the corresponding design of the cylindrical battery cell. The mechanical properties of the cylindrical battery cell housing specified by the reference material, here AISI1020 steel with a yield strength Rp0.2 of 350 MPa, are taken into account and maintained. Fig. 1 schematically shows a cylindrical battery cell housing with a length l and an outer radius R.The battery cell housing consists of a battery cell housing shell and two battery cell housing covers. The wall thickness of the aluminum material is denoted by s. At least one of the covers and the shell can have different wall thicknesses, which are determined by the internal pressure stability of the battery cell housing. For simplicity, however, identical wall thicknesses are assumed for both covers. The approximation of two covers with identical wall thickness is used to simplify the calculations, as there is no significant influence on the calculated change in greenhouse gas emissions. In addition, a density of ^^ = 2.7 g cm-3 is approximately assumed for all aluminum materials. The cylindrical battery cell housing made of the reference material steel is used. I / ZI 230340WOMarch 28, 2024 The mass ^^ ^^ ^^ ^^ℎ ^^ for the shell surface of the steel version is given by the following equation, where ^^ ^^ ^^ ^^ℎ ^^ is the density of steel, l is the length of the tube, ^^ ^^ ^^ ^^ℎ ^^ is the wall thickness of the steel casing, and ^^ ^^ is the inner radius of the tube: ^^ ^^ ^^ ^^ℎ ^^ = ^^ ^^ ^^ ^^ℎ ^^∗ ^^ ∗ ^^ ∗ ( ^^ ^ 2 ^ ^^ ^^ℎ ^^ + 2 ∗ ^^ ^^ ^^ ^^ℎ ^^ ∗ ^^ ^^ ) (1)Based on the boiler formula, the mass ^^ ^^ ^^ ^^ of the battery cell casing shell in the form of an aluminum tube, which is designed to have the same flow onset as the steel version, can be calculated as follows. Aus with ^^ ^^ ^^ ^^ : Dense aluminum material ^^ ^^ ^^ ^^ : Wall thickness aluminum material ^^ ^^ : Inner radius follows The wall thickness ^^ ^^ ^^ ^^ of the aluminum tube, i.e. the battery cell casing, results from the boiler formula and the design against the onset of flow using the equivalent stress according to Tresca to: Z I / ZI 230340WO March 28, 2024The mass ^^ ^^ ^^ ^^ℎ ^^, ^^ of the steel lid is the product of the circular area of ​​the lid, the wall thickness of the lid, and the density of steel: For the lid of the cylindrical battery cell housing, a different relationship arises from the internal pressure stability requirement. Näherung: ^^ p0,2 σ ^ ≈ max^ ^^ (7)where p is the internal pressure in the prismatic battery cell casing and ^max is the maximum stress of the cover material according to Tresca, results from the proportionality of the relationship between stress and pressure at a wall thickness s for a plate with a uniform compressive load acting normal to the surface (e.g. Dubbel, "Handbook for Mechanical Engineering", 19th edition, Springer Verlag 1997: Chapter C, "Strength of Materials"): When comparing two materials with identical geometry, (8)(9) Starting from the reference material AISI1020 with a yield strength Rp0.2 of 350MPa for a given wall thickness of the cover, if the identical internal pressure stability is met for the wall thickness of the new aluminum material; Z I / ZI 230340WO March 28, 2024 The wall thickness of the aluminum lid is again determined so that the same resistance to flow is achieved. The mass of the aluminum lid is determined as follows: The mass of the steel battery cell housing is then as follows: The weight of the aluminum housing follows analogously to: The percentage change in greenhouse gas emissions for the cylindrical battery cell casing is calculated using the products of the respective masses in kg of the battery cell casing and the respective masses in kg of greenhouse gas emissions CO2e of the respective material: Z I / ZI 230340WOMarch 28, 2024 with^^ ^^2 ^^, ^^ ^^ ^^, ^^ ^^2 ^^, ^^ ^^ ^^ℎ ^^: emitted mass of CO2 equivalents in kgCO2e per kg aluminum or steel. For the aluminum material according to the invention with a CO2e / Rp0.2 ratio of maximum 1.9% kgCO2e / (MPa*kgAl material), based on a cylindrical battery cell casing of the 18650 format made of steel type AISI 1020 with the wall thicknesses of the tube ^^ ^^ ^^ ^^ℎ ^^ = 0.185 ^^ ^^ or the cover ^^ ^^ ^^ ^^ℎ ^^, ^^ = 0.22 ^^ ^^ and an inner radius ^^ ^^ = 8.815 ^^ ^^ with a length L = 65 mm, a saving of in greenhouse gas emissions of more than 4%. To achieve greater savings in greenhouse gas emissions, the selected aluminum material preferably has a CO2e / Rp0.2 ratio of maximum 1.8% kgCO2e / (MPa*kgAl material), more preferably maximum 1.6% kgCO2e / (MPa*kgAl material), particularly preferably maximum 1.2% kgCO2e / (MPa*kgAl material) or particularly preferably maximum 1.0% kgCO2e / (MPa*kgAl material).As a result, a saving in greenhouse gas emissions with this battery cell housing format of preferably more than 10%, further preferably more than 20%, particularly preferably more than 40% or particularly preferably at least 50% can be achieved compared to the current reference material steel. For larger battery cell formats such as the 21700 or 4680 format, essentially identical values ​​are achieved with regard to the saving in greenhouse gas emissions at the stated CO2e / Rp0.2 ratios of the aluminum material. According to a first embodiment, the cylindrical battery cell housing has a housing shell with an outer diameter of more than 14 mm, preferably more than 17.5 mm, particularly preferably more than 22 mm, wherein optionally the length of the cylindrical battery cell housing is at least 40 mm. For larger battery cell formats, the aluminum material can take advantage of its lower weight and the Z. I / ZI 230340WOMarch 28, 2024 significantly improved heat conduction translates into improved battery cell performance. Preferably, the cylindrical battery cell housing has the formats 18650, 21700, 26105, 4680, 4690, or 46125. According to a further advantageous embodiment, the aluminum material is a wrought aluminum material. Wrought aluminum materials have the property of allowing high degrees of deformation, as required for the production of cylindrical battery cell housings. At the same time, they provide a very dense microstructure compared to cast aluminum materials, so that the sealing requirements of the cylindrical battery cell housings are also met. können.A preferred heat-treatable wrought aluminum material is provided by AA6xxx aluminum alloys. These can be extruded into a battery cell casing shell in the form of a cylindrical tube, which, when fitted with two battery cell covers, can form the battery cell casing. This provides a more economical manufacturing process. Naturally hard wrought aluminum materials can be manufactured using simpler manufacturing processes than heat-treatable wrought aluminum materials, which can also generally result in lower greenhouse gas emissions, since, for example, high-temperature annealing steps, particularly at the final thickness, such as those required for solution annealing of heat-treatable alloys, can be avoided.With regard to thermal joining processes, such as welding of cylindrical battery cell casings, the naturally hard aluminum materials exhibit a significantly lower tendency to strength loss and generally possess good corrosion resistance. Optionally, the naturally hard aluminum materials are made of an aluminum alloy of the type AA1xxx, AA3xxx, AA5xxx, or AA8xxx, whose manufacturing processes are well known. I / ZI 230340WOMarch 28, 2024. According to a further embodiment, lower greenhouse gas emissions can be achieved if the battery cell housing comprises an aluminum alloy of the type AA1050, AA1100, AA1200, AA3003, AA3004, AA3104, AA3005, AA3105, AA5005, AA5052, AA5454, AA5754, AA5182, AA5083, AA5086, AA8006, AA8008, AA8010, AA8011, AA8111, AA8021, AA8026, AA8050, or AA8079. Different manufacturing routes for the cylindrical battery cell housing can be pursued using the aforementioned alloy types. For example, the lower-alloyed aluminum alloy of type AA1xxx is suitable for extrusion processes, while aluminum alloys of type AA3003, AA3004, AA3104, AA3005 or AA3105 provide high degrees of deformation in the production of battery cell housings, for example from sheet metal blanks, but also good to very good welding properties.At the same time, alloy types AA3004, AA3104, AA3005, and AA3105 are particularly recycling-friendly and allow for high proportions of recycled material. The higher magnesium content of aluminum alloy types AA5005, AA5052, AA5454, AA5754, AA5182, AA5083, and AA5086 not only exhibits excellent forming properties but also provides particularly high yield strengths, even in the soft state, allowing maximum utilization of savings potential in terms of greenhouse gas emissions through lower wall thicknesses of the battery cell casing. At the same time, alloy types AA5052, AA5454, AA5754, AA5182, AA5083, and AA5086 allow for a high proportion of recycled material due to their chemical composition.The alloy types AA8006, AA8008, AA8010, AA8011, AA8111, AA8021, AA8026, AA8050, and AA8079 not only allow for higher recycling rates due to their wider alloy window compared to 1xxx alloys, but also enable higher strengths. Due to their high permissible iron content, these alloys are particularly suitable for accepting iron-containing scrap. I / ZI 230340WOMarch 28, 2024. Preferably, the aluminum material of the battery cell housing has a yield strength Rp0.2 of at least 100 MPa, preferably at least 150 MPa, particularly preferably at least 200 MPa. Soft aluminum materials with yield strengths Rp0.2 of less than 100 MPa often enable particularly high degrees of deformation, but require greater wall thicknesses compared to the standard material steel to provide sufficient strength. From a yield strength of 100 MPa, savings in greenhouse gas emissions, based on an identical battery cell format, can be realized primarily through savings in greenhouse gas emissions during aluminum production, in particular through the use of external scrap and through the use of primary aluminum containing a high proportion of primary metal produced using renewable energy.Higher yield strengths of at least 150 MPa or at least 200 MPa allow for additional material savings in addition to these savings, which also have a positive impact on reducing greenhouse gas emissions. The average greenhouse gas emissions for primary aluminum used in the European Union (EU) are 8.6 kgCO2e / kgAl material. Therefore, if the aluminum material of the battery cell housing preferably consists at least partially of a primary aluminum, during the production of which the amount of CO2 emitted per kg of aluminum material of the battery cell housing is a maximum of 6.7 kgCO2e / kgAl, preferably a maximum of 5 kgCO2e / kgAl, particularly preferably a maximum of 4 kgCO2e / kgAl, significant reductions in greenhouse gas emissions can also be achieved through the primary metal content.Corresponding greenhouse gas emission values ​​per kg of primary aluminum can be achieved by using CO2-neutral energy, preferably renewable energy, in production, especially renewable electricity. A maximum of 4 kgCO2e / kgAl is achieved if the primary metal is produced entirely using renewable energy, i.e., CO2-neutral energy. If the greenhouse gas emissions per kg of aluminum material in the battery cell housing during the production of the aluminum material for the battery cell housing are Z. I / ZI 230340WOMarch 28, 2024 maximum 4 kgCO2e / kgAl material, preferably maximum 3 kgCO2e / kgAl material, particularly preferably maximum 2 kgCO2e / kgAl material, the inventive CO2e / Rp0.2 ratio of maximum 1.8% kgCO2e / (MPa*kgAl material) can also be achieved using less solid aluminum materials, for example AA1xxx alloys. For this purpose, the proportion of external scrap and / or post-consumer scrap must be selected accordingly. According to a further teaching of the present invention, the above-mentioned object for a method for producing a battery cell housing according to the invention is achieved in that the method comprises forming the aluminum material and preferably comprises deep drawing, ironing, extrusion, extrusion or extrusion, or roll forming of the aluminum material. Deep drawing, ironing, extrusion, or impact molding are forming processes that enable economical production of battery cell housings.At the same time, however, the manufacturing processes also impose limits on the use of specific aluminum alloys. For example, extrusion processes using softer wrought aluminum alloys such as AA1050 are preferred, while AA6xxx alloys are primarily used for extrusion. A process for producing cylindrical battery cell housings that particularly efficiently avoids greenhouse gas emissions can be provided by producing the aluminum material of the battery cell housing from at least 30%, preferably at least 60%, and particularly preferably 100% primary aluminum produced using CO2-neutral energy. By using primary aluminum produced with 100% CO2-neutral energy, greenhouse gas emissions are reduced from 8.6 to 4 kgCO2e / kgAl for the correspondingly produced primary aluminum compared to the average primary metal consumed in the EU, which corresponds to a reduction of more than 50%.I / ZI 230340WOMarch 28, 2024. According to a further embodiment, the aluminum material is produced from at least 40%, preferably at least 70%, external scrap and / or post-consumer scrap, whereby internal scrap can optionally also be used to produce the aluminum material. Internal scrap, cumulatively compared to the production of the aluminum material from, for example, primary metal, accounts for 0.3 kgCO2e / kgAl material greenhouse gas emissions due to the production and further processing that has already taken place. Nevertheless, taking these metal sources into account contributes to increasing the efficiency of the production of the cylindrical battery cell housings, as material consumption is significantly reduced by remelting the internal scrap and waste is avoided.External scrap and / or post-consumer scrap contribute significantly to reducing the greenhouse gas emissions of the aluminum material, as they only generate greenhouse gas emissions of 0.5 kgCO2e / kgAl material. A maximum proportion of this scrap is therefore desirable. According to a further embodiment, a slug is first produced from the aluminum material, which is then extruded into a cup-shaped, cylindrical battery cell housing blank. The cylindrical battery cell housing, comprising a battery cell housing shell and a battery cell housing base, is finally formed from the cup-shaped battery cell housing blank via at least one further forming step, preferably by ironing. Aluminum alloys of the type AA1xxx, AA3xxx, but also AA6xxx are preferably used for the aluminum material.Subsequently, a battery cell housing cover can be produced using a sheet metal blank, for example in the form of a stamped part, and the cylindrical battery cell housing can be closed with the battery cell housing cover after its assembly. In an alternative process for producing the battery cell housing, an aluminum strip is first produced from the aluminum material by rolling, from which a cylindrical battery cell housing having a battery cell housing shell and aZ. I / ZI 230340WOMarch 28, 2024. The battery cell housing base is manufactured, for example, directly from the aluminum strip or from sheet blanks made from the aluminum strip, preferably using aluminum alloys of the AA1xxx, AA3xxx, AA5xxx, or AA8xxx types. The deep drawing or ironing production steps are proven industrial processes that can be carried out in a highly automated manner with low energy consumption, i.e., without complex annealing processes. This makes this process also suitable for the efficient production of cylindrical battery cell housings. Starting from an aluminum strip, according to another alternative variant, an aluminum strip can also be initially produced from the aluminum material by rolling.Using a roll-forming process, a roll-formed battery cell housing shell, which has a cylindrical cross-section at least in some regions, is formed from the aluminum strip, and the battery cell housing shell is joined longitudinally, preferably by positive, frictional, and / or material-locking. The cylindrical battery cell housing shell is then cut to length and joined to a battery cell housing base made from a sheet metal blank from an aluminum strip of the same or a different aluminum material by positive, frictional, and / or material-locking, preferably using aluminum alloys of the type AA1xxx, AA3xxx, AA5xxx, or AA8xxx. Roll-forming, longitudinal seam joining, cutting, and joining battery cell housing covers are also industrially proven processes that, when using the aforementioned aluminum alloys, lead to advantageous properties of the battery cell housing.At the same time, the processes mentioned are also particularly energy-efficient, so that greenhouse gas emissions continue to be dominated by the manufacturing process for the aluminum materials. According to a further alternative embodiment, a tube is extruded from the aluminum material, which is optionally cut to length and, after at least one optional processing step, is provided with a battery cell housing base made of Z. I / ZI 230340WOMarch 28, 2024 a sheet metal blank made from an aluminum strip made of the same or a different aluminum material is joined in a form-fitting, friction-fitting, and / or material-fitting manner, preferably using aluminum alloys of the type AA1xxx, AA3xxx, AA6xxx, or AA8xxx. In order to provide a finished cylindrical battery cell, according to a further embodiment, the cup-shaped battery cell housings are closed during cell assembly with a battery cell housing cover made from a sheet metal blank made from an aluminum material. In the case of tubular cell housings, the cell housing shell is closed on both sides with a cover during cell assembly. Here, too, form-fitting, friction-fitting, and / or material-fitting joining processes can preferably be used to join the battery cell housing cover.Finally, the above-mentioned object is achieved by the use of an aluminum material for the production of a cylindrical battery cell housing, wherein the aluminum material has a ratio of the amount of greenhouse gases emitted during the production of the aluminum material, expressed in kgCO2e per kgAl material, to the yield strength Rp0.2 of the aluminum material in MPa of CO2e / Rp0.2 ≤ 1.9% kgCO2e / (MPa*kgAl material), preferably CO2e / Rp0.2 ≤ 1.6% kgCO2e / (MPa*kgAl material), particularly preferably CO2e / Rp0.2 ≤ 1.2% kgCO2e / (MPa*kgAl material) or CO2e / Rp0.2 ≤ 1.0% kgCO2e / (MPa*kgAl material). The use of the aluminum material according to the invention represents a saving of Greenhouse gas emissions compared to today's standard material, nickel-plated steel strips, so that the carbon footprint of the cylindrical battery cell casing can be further reduced while providing a lower battery cell weight and better thermal conduction.The invention will be explained in more detail below using exemplary embodiments in conjunction with the drawing. The drawing shows in Z. I / ZI 230340WO March 28, 2024Fig. 1 a schematic representation of a battery cell with a cylindricalB atteriezellgehäuse,Fig. 2 shows a flow diagram of a method for producing a cylindrical battery cell housing by impact extrusion according to a first embodiment, Fig. 3 shows a flow diagram of a method for producing a cylindrical battery cell housing by deep drawing and ironing a blank of aluminum strip according to a second embodiment, Fig. 4 shows a flow diagram for producing a cylindrical battery cell housing by roll forming and longitudinal seam joining according to a third embodiment, and Fig. 5 shows a flow diagram for producing a prismatic battery cell housing by extruding a prismatic tube according to a fourth embodiment. First, Fig. 1 shows a schematic representation of a battery cell 10 with a cylindrical battery cell housing 11. The battery cell 10 has, in addition to the battery cell housing 11, an anode terminal 12 and a cathode terminal 13.As already explained above, the cylindrical battery cell housing 11 has two battery cell housing covers 14 and 15 and a battery cell housing shell 16. Furthermore, Fig. 1 shows the shape specifications important for the format of the cylindrical battery cell, the length l and the radius R. Fig. 2 schematically illustrates a manufacturing method of an exemplary embodiment. According to step A1, a slug is first produced from an aluminum material. The production of a slug can be achieved, for example, by sawing a Z-shaped section. I / ZI 230340WOMarch 28, 2024 a corresponding diameter rod. Alternatively, slugs can be produced from a rolled or cast strip production, whereby the slugs are punched from the rolled or cast strip and then surface-treated and optionally annealed. The slug is then placed in an extrusion tool and extruded into a cylindrical battery cell housing blank by extrusion according to step B1. This is converted in step C1 by at least one manufacturing step, for example trimming or ironing, into the cylindrical battery cell housing 11 with battery cell housing base 15 and battery cell housing shell 16 and is ready for cell assembly. In step D1, during cell assembly, the battery cell housing cover 14 is mounted and joined to the battery cell housing shell 16 in a form-fitting, friction-fitting, and / or material-fitting manner. The starting point of the process shown in Fig. 3 and Fig.4 is an aluminum strip, which is provided in step A2 or A3. The aluminum strip can be produced, for example, by the following steps. werden: - Casting of a rolling ingot from an aluminum alloy, - Optional homogenization of the rolling ingot, - Hot rolling of the rolling ingot to form a hot-rolled strip, - Cold rolling of the hot-rolled strip with optional intermediate annealing. After cold rolling, the strips can be in the H12, H14, H16, H18, or H19 tempers. However, cold rolling can optionally be followed by heat treatment of the strip in the form of temper annealing, preferably in the form of reannealing. After reannealing, the values ​​for the yield strength Rp0.2 are barely reduced. However, the possible degrees of deformation are significantly improved, for example, in the H24 temper. Alternatively, the aluminum strip can also be provided in step A2 or A3 by continuous casting, optionally using a twin-roll caster or ZI / ZI 230340WOMarch 28, 2024 Twin-Belt Casters are used, which enable large production capacities. After casting the cast strip, for example, cold rolling takes place at the final thickness of the aluminum strip. According to Fig. 3, in step B2, a cylindrical battery cell housing comprising a battery cell housing shell and a battery cell housing base is produced from the rolled aluminum strip through deep-drawing and ironing processes, preferably using aluminum alloys of the type AA1xxx, AA3xxx, AA5xxx, or AA8xxx. The deep-drawing and ironing processes preferably take place on blanks of the aluminum strip, but can also be performed on the aluminum strip in progressive dies. In step C2, an optional further forming step is performed to achieve the final geometry of the cylindrical battery cell housing 11, including the battery cell housing base 15 and the battery cell housing shell 16.In step D2, during cell assembly, the battery cell housing cover 14 is mounted and joined to the battery cell housing shell 16 in a form-fitting, frictional, and / or material-fitting manner. According to Fig. 4, a roll-formed battery cell housing shell, which has a cylindrical cross-section at least in some regions, is formed from the rolled aluminum strip using a roll-forming process in step B3. Subsequently, the battery cell housing shell is joined longitudinally, preferably in a form-fitting, frictional, and / or material-fitting manner, and cut to length in step B3. Optionally, the battery cell housing shell can also be joined longitudinally after cutting.In step C3, a cut battery cell housing base 15 made from a sheet metal blank from an aluminum strip made of the same or a different aluminum material is joined to the battery cell housing shell 16 in a form-fitting, friction-fitting and / or material-fitting manner, wherein aluminum alloys of the type AA1xxx, AA3xxx, AA5xxx or AA8xxx are preferably used for the battery cell housing shell 16 or the battery cell housing covers 14 and 15. In step D3, the battery cell housing cover 14 is mounted and form-fitting, Z. I / ZI 230340WOMarch 28, 2024, frictionally and / or materially bonded to the battery cell casing shell 16. Optionally, steps C3 and D3 can be performed during cell assembly. The cylindrical battery cell casings 11 that can be manufactured using the processes described above were examined with regard to their potential for reducing greenhouse gas emissions. The following assumptions were made: Greenhouse gas emissions are essentially dominated by the provision of aluminum alloys, particularly when primary aluminum is used. Sheet metal production typically generates only 0.4 kgCO2e / kgAl material. In the global energy mix, however, 16 kgCO2e / kgAl material are emitted for the production of primary aluminum. In the European Union, primary aluminum consumed up to the production of the rolling ingot has an emission quota of only 8.6 kgCO2e / kgAl material.For the following calculation, it is assumed that internal scrap made from primary metal with a CO2 equivalent of 8.6 kgCO2e / kgAl material is used, and that an average emission of 0.3 kgCO2e / kgAl material is used for its processing, resulting in an emission rate of 8.9 kgCO2e / kgAl material. External scrap and post-consumer scrap are considered with 0.5 kgCO2e / kgAl material. If primary aluminum is produced solely using greenhouse gas-neutral energy, the resulting greenhouse gas emissions are only 4 kgCO2e / kgAl material. (cf. International Aluminum Association: https: / / international-aluminium.org / statistics / greenhouse-gas-emissions-intensity-primary-aluminium / ) In Tables 1 and 2, the relationships shown in equation (15) have now been examined with regard to exemplary embodiments according to the invention and comparative examples.Table 1 contains exemplary embodiments according to the invention, while Table 2 contains comparative examples. The first three columns of both tables indicate the alloy designation, the temper state, and the yield strength tested. This is the minimum yield strength Rp0.2 according to DIN EN 485-2 of the Z. I / ZI 230340WO March 28, 2024 Aluminum alloy in the respective tempered state. This is followed by five columns that indicate the proportions of the respective primary metal and / or internal and external scrap of the aluminum materials examined. CO2e is the CO2 footprint of the aluminum material in the 6th column, including 0.4 kg CO2e / kg of Al material for the production of the battery cell casing. From this value, the ratio to the yield strength in the 7th column was determined. The stated greenhouse gas savings are derived from equation (15), taking into account the nickel-plated reference material, steel type AISI 1020, with 2.4 kg. CO2e / kg Stahl, a yield strength R p0,2of 350 MPa and the battery cell format 18650 with the wall thicknesses of the battery cell casing shell ^^ ^^ ^^ ^^ℎ ^^ = 0.185 ^^ ^^ or the lid ^^ ^^ ^^ ^^ℎ ^^, ^^ = 0.22 ^^ ^^ and an inner radius ^^ ^^ = 8.815 ^^ ^^ with a length L = 65 mm. It was shown that all investigated aluminum materials made of the aluminum alloys type AA1xxx, AA3xxx, AA5xxx and AA8xxx can provide a reduction in greenhouse gas emissions at a CO2e / Rp0.2 ratio of maximum 1.9% kgCO2e / (MPa*kgAl material) compared to the current reference material, a nickel-clad steel type AISI 1020 manufactured with an emission rate of 2.4 kgCO2e / kgsteel, provided that specifications for the Yield strength Rp0.2 as well as the origin of the primary aluminum and / or the use of the scrap components.As already explained above, starting from a cylindrical battery cell casing of the 18650 format made of the above-mentioned steel with the wall thicknesses of the battery cell casing shell ^^ ^^ ^^ ^^ℎ ^^ = 0.185 ^^ ^^ or the cover ^^ ^^ ^^ ^^ℎ ^^, ^^ = 0.22 ^^ ^^ and an inner radius ^^ ^^ = 8.815 ^^ ^^ with a length L = 65 mm, a saving in greenhouse gas emissions of more than 4% results. The inventive embodiments 1 to 11 have a ratio CO2e / Rp0.2 of a maximum of 1.9% to more than 1.6% kgCO2e / (MPa*kgAl material), so that a saving in greenhouse gas emissions in kgCO2e / kgAl material, taking into account the above-mentioned 18650 format, of at least 4% achievedZ. I / ZI 230340WOMarch 28, 2024. It can be seen that to achieve the aforementioned emission savings, at least 40% of external scrap must be used in production, provided primary metal with the energy requirements of the primary metals currently processed in the EU is used (Examples 1 and 2). In addition, high strengths with yield strengths Rp0.2 of more than 200 MPa can again bring the total emissions for the cylindrical battery cell housing into the desired range through reduced material usage. This is demonstrated by embodiments 2, 9, 20, and 35, whose aluminum materials have an emission rate of more than 4 kgCO2e / kgAl material. Embodiments 12 to 22 have a CO2e / Rp0.2 ratio of a maximum of 1.6% to more than 1.2% kgCO2e / (MPa*kgAl material) and therefore achieve greenhouse gas emission savings of more than 25%.Such savings are achieved primarily through the use of CO2-neutral, renewable energy-produced primary aluminum in combination with the use of external scrap, as shown in working examples 12, 13, 15 to 19, and 21 and 22. Working examples 14 and 20 demonstrate that, at very high yield strengths of the aluminum material above 200 MPa, both the partial use of primary metal with a CO2 footprint of currently 8.6 kgCO2e / kgAl material of the primary metal used in the EU (see working example 14) and the use of primary aluminum produced exclusively with renewable energy, as in working example 20, achieve the above-mentioned reduction in greenhouse gas emissions.The exemplary embodiments 23 to 32 show that even higher savings in greenhouse gas emissions are possible, because with a CO2e / Rp0.2 ratio of maximum 1.2% kgCO2e / (MPa*kgAl material), the saving, taking into account the above-mentioned reference material and the battery cell format used, is more than 40% for the exemplary embodiments 23 to 29 and more than 50% for the exemplary embodiments 29 to 34 with a CO2e / Rp0.2 ratio of maximum 1.0% kgCO2e / (MPa*kgAl material). I / ZI 230340WOMarch 28, 2024 Furthermore, it can be seen from the exemplary embodiments that, with an emitted amount of CO2 per kg of aluminum material of the battery cell housing between 3 and 4 kgCO2e / kgAl material, aluminum materials with at least 185 MPa are used to achieve the savings in greenhouse gas emissions. Lower greenhouse gas emissions during the production of the aluminum material of the battery cell housing, preferably a maximum of 3 kgCO2e / kgAl or particularly preferably a maximum of 2 kgCO2e / kgAl, allow the use of softer aluminum materials with yield strengths Rp0.2 of less than 185 MPa, for example a maximum of 180 MPa, as shown in exemplary embodiments 22 and 24.Even though the exemplary embodiments of the invention in Table 1 do not show any proportions of internal scrap, their use to achieve CO2 savings is nevertheless important and useful, since, as already explained, they reduce the overall material consumption of primary aluminum. If the CO2 emissions for the aluminum material from which the internal scrap is generated are significantly reduced, the CO2 emission contributions of the internal scrap also decrease. In principle, for example, by increasing the proportion of external scrap to more than 70%, for example, 85%, or even more than 90%, compensation for the use of internal scrap can be made possible in the exemplary embodiments presented.A study of other battery formats, such as the 4680 format, showed that changing the battery format had only a very small impact on potential CO2 savings for a given CO2e / Rp0.2 ratio of a maximum of 1.9% kgCO2e / (MPa*kgAl material). Larger-volume formats, such as the 4680, result in single-digit percentage increases in greenhouse gas emissions compared to the smaller format. 18650. Z I / ZI 230340WOMarch 28, 2024. Therefore, the exemplary embodiments according to the invention can be used to specify aluminum materials for battery cell housings that allow significant savings in greenhouse gas emissions during battery cell housing production while still providing the advantages of using aluminum materials for battery cell housings. Comparative examples are now given in Table 2. In particular, it can be seen that at low yield strength Rp0.2 values ​​of less than 100 MPa, even high proportions of 70% of external scrap do not lead to greenhouse gas savings compared to the reference material steel, see Comparative Examples 1 and 2. The same applies to the use of ultrahigh-strength materials using energy with global greenhouse gas emissions of 16 kgCO2e / kgAl, dominated by coal-fired power generation, as Comparative Examples 16 and 17 show, which have significantly too high CO2e / Rp0.2 ratios. I / ZI 230340WOMarch 28, 2024 Table 1: Inventive embodiments AA- Tempering Rp0.2 Proportion of primary metal in [%] Proportion of internal Proportion of external CO2e CO2e / Rp0.2 No. Alloy state (MPa) made from scrap [%] scrap [%] [kgCO2e / [%] kgAl material] Renewable energy mix Energy mix Energy ^ EU ^ weltweit 5005 H19 185 30 70 3.33 1.80 15182 H19 320 60 40 5.76 1.80 21050 H18 120 30 70 1.95 1.63 33003 H19 180 60 40 3 1.67 43004 H24 170 60 40 3 1.76 53105 H18 180 60 40 3 1.67 65005 H24 110 30 70 1.95 1.77 75052 H14 180 60 40 3 1.67 85754 H18 250 100 4.4 1.76 95182 O 110 30 70 1.95 1.77 108011 H14 110 30 70 1.95 1.77 111050 H19 130 30 70 1.95 1.50 123003 H14 125 30 70 1.95 1.56 133004 H19 240 30 70 3.33 1.39 143005 H14 150 30 70 1.95 1.30 153105 H14 130 30 70 1.95 1.50 165052 H24 150 30 70 1.95 1.30 175052 H18 240 60 40 3 1.25 18T I / ZI 230340WO March 28, 2024

[0002] AA- Temper Rp0.2 Proportion of primary metal in [%] Proportion of internal Proportion of external CO2e CO2e / Rp0.2 No. Alloy condition (MPa) made from scrap [%] scrap [%] [kgCO2e / [%] kgAl material] Renewable energy mix Energy mix Energy ^ EU ^ weltweit 5083 O 125 30 70 1.95 1.56 195083 H14 280 100 4.4 1.57 205083 H32 215 60 40 3 1.40 218011 H18 145 30 70 1.95 1.34 223003 H18 170 30 70 1.95 1.15 233004 H24 170 30 70 1.95 1.15 243105 H19 190 30 70 1.95 1.03 255005 H19 185 30 70 1.95 1.05 265754 H14 190 30 70 1.95 1.03 275182 H19 320 30 70 3.33 1.04 285083 H14 280 30 70 3.33 1.19 293004 H19 240 30 70 1.95 0.81 303005 H18 200 30 70 1.95 0.98 315052 H18 240 30 70 1.95 0.81 325182 H19 320 60 40 3 0.94 335083 H14 280 30 70 1.95 0.70 345182 H19 320 30 70 5.55 1.73 35Table 2: Comparative examples Z I / ZI 230340WO March 28, 2024

[0003] AA- Temper Rp0,2 Proportion of primary metal in [%] Proportion of internal Proportion of external CO2e CO2e / Rp0,2 No. Alloy condition (MPa) made from scrap [%] scrap [%] [kgCO2e / [%] Renewable energy mix Energy mix kgAl- Energy ^ EU ^ weltweit Material] 1050 H14 85 60 40 6.36 7.48 11050 H14 85 30 70 1.95 2.29 21050 H18 120 60 40 3 2.50 33003 H14 125 60 40 3 2.40 43003 H14 125 30 70 3.33 2.66 53003 H18 170 30 70 3.33 1.96 63004 H14 180 30 70 3.33 1.85 73004 H18 230 60 40 5.76 2.50 83005 H18 200 100 4.4 2.20 93005 H19 210 60 40 5.76 2.74 103005 H19 210 30 70 5.55 2.64 115754 H24 160 30 70 3.33 2.08 125083 H14 280 60 40 5.76 2.06 135083 H24 250 30 70 5.55 2.22 148011 H18 145 60 40 3 2.07 153005 H19 210 100 16.4 7.81 165182 H19 320 100 16.4 5.13 175182 H19 320 60 40 10.2 3.19 185083 O 125 60 40 10.2 8.16 195083 O 125 30 70 5.55 4.44 20Z I / ZI 230340WO March 28, 2024

Claims

March 28, 2024 Patent claims 1. Cylindrical battery cell housing, characterized in that the cylindrical battery cell housing comprises an aluminum material whose ratio of the amount of carbon dioxide (CO2e) emitted during the production of the aluminum material in kgCO2e per kgAl material to the yield strength Rp0.2 of the aluminum material in MPa is CO2e / Rp0.2 ≤ 1.9% kgCO2 / (MPa*kgAl material), preferably CO2e / Rp0.2 ≤ 1.6% kgCO2 / (MPa*kgAl material), particularly preferably CO2e / Rp0.2 ≤ 1.2% kgCO2e / (MPa*kgAl material) or CO2e / Rp0.2 ≤ 1.0% kgCO2e / (MPa*kgAl material), whereby the yield strength Rp0.2 is measured according to DIN EN ISO 6892-1 at room temperature.2.Battery cell housing according to claim 1, characterized in that the cylindrical battery cell housing has a housing shell with an outer diameter of more than 14 mm, preferably more than 17.5 mm, particularly preferably more than 22 mm, wherein the length of the cylindrical battery cell housing is optionally at least 40 mm.

3. Battery cell housing according to claim 1 or 2, characterized in that the aluminum material is a wrought aluminum material. - 2 -4. Battery cell housing according to one of claims 1 to 3, characterized in that the aluminum material is a naturally hard wrought aluminum material and optionally comprises an aluminum alloy of the type AA1xxx, AA3xxx, AA5xxx or AA8xxx.

5. Battery cell housing according to one of claims 1 to 4, characterized in that the battery cell housing comprises an aluminum alloy of the type AA1050, AA1000, AA1200, AA3003, AA3004, AA3104, AA3005, AA3105, AA5005, AA5052, AA5454, AA5754, AA5182, AA5083, AA5086, AA8006, AA8008, AA8010, AA8011, AA8111, AA8021, AA8026, AA8050 or AA8079.

6. Battery cell housing according to one of claims 1 to 5, characterized in that the aluminum material in the battery cell housing has a yield strength Rp0.2 of more than 100 MPa, preferably 150 MPa, particularly preferably more than 200 MPa aufweist.

7. Battery cell housing according to one of claims 1 to 6, characterized in that the aluminum material consists at least partially of a primary aluminum, during the production of which the emitted amount of CO2 per kg of aluminum material of the battery cell housing is a maximum of 6.7 kgCO2e / kgAl, preferably a maximum of 5 kgCO2 / kgAl, particularly preferably a maximum of 4 kgCO2e / kgAl beträgt.

8. Battery cell housing according to one of claims 1 to 7, characterized in that in the manufacture of the aluminum material of the battery cell housing, theZ I / ZI 230340WO March 28, 2024 - 3 - the amount of CO2 emitted per kg of aluminum material of the battery cell housing is a maximum of 4 kgCO2e / kgAl material, preferably a maximum of 3 kgCO2 / kgAl, particularly preferably a maximum of 2 kgCO2e / kgAl.

9. A method for producing a cylindrical battery cell housing according to one of claims 1 to 8, characterized in that the method comprises forming the aluminum material, preferably deep drawing, extrusion, or roll forming of the aluminum material.

10. A method according to claim 9, characterized in that the aluminum material is produced from at least 30%, preferably at least 60%, and particularly preferably 100% primary aluminum produced using CO2-neutral energy.11.Method according to claim 9 or 10, characterized in that the aluminum material is produced from primary-based aluminum and at least 40%, preferably at least 70%, external scrap and / or post-consumer scrap, wherein internal scrap is optionally also used to produce the aluminum material.

12. Method according to one of claims 9 to 11, characterized in that a slug is first produced from the aluminum material, the slug is extruded into a cup-shaped, cylindrical battery cell housing blank, and the cylindrical battery cell housing comprising a battery cell housing shell and a battery cell housing base is produced from the cup-shaped battery cell housing blank via at least one further forming step, e.g. I / ZI 230340WO March 28, 2024 - 4 - is preferably finally formed by ironing, wherein preferably aluminum alloys of the type AA1xxx, AA3xxx, but also AA8xxx are used for the aluminum material.

13. Method according to one of claims 9 to 11, characterized in that an aluminum strip is produced from the aluminum material by rolling, from which a cylindrical battery cell housing comprising a battery cell housing shell and a battery cell housing base is produced by deep-drawing and ironing processes, wherein preferably aluminum alloys of the type AA1xxx, AA3xxx, AA5xxx, or AA8xxx are used, or alternatively, a roll-formed battery cell housing shell, which has a cylindrical cross-section at least in regions, is formed from the aluminum strip using a roll-forming process, the battery cell housing shell being joined in the longitudinal direction, preferably by form-fitting, frictional, and / or material-fitting,the cylindrical battery cell housing shell is cut to length and joined to a battery cell housing base made from a sheet metal blank from an aluminum strip made from the same or a different aluminum material in a form-fitting, friction-fitting, and / or material-fitting manner, preferably using aluminum alloys of the type AA1xxx, AA3xxx, AA5xxx, or AA8xxx.

14. Method according to one of claims 9 to 11, characterized in that its tube is extruded from the aluminum material, which is optionally cut to length and, after at least one optional processing step to provide the final-shaped battery cell housing shell, is joined to a battery cell housing base made from a sheet metal blank from an aluminum strip made from the same or a different aluminum material in a form-fitting, friction-fitting, and / or material-fitting manner, wherein Z, I / ZI 230340WO March 28, 2024 - 5 - preferably aluminum alloys of the type AA1xxx, AA3xxx, AA5xxx, AA6xxx or AA8xxx are used.

15. Method according to claim 11, 12, 13 or 14, characterized in that the cup-shaped, cylindrical battery cell housing is joined, during the cell assembly, to a battery cell housing cover made of a sheet metal blank made of an aluminum material, preferably by form-fitting, frictional and / or material-fitting.16.Use of an aluminum material for producing a cylindrical battery cell housing according to one of claims 1 to 8, optionally using a method according to claims 9 to 15, characterized in that the aluminum material has a ratio of the amount of carbon dioxide emitted during production of the aluminum material (CO2e) in kgCO2e per kgAl material to the yield strength Rp0.2 of the aluminum material in MPa of CO2e / Rp0.2 ≤ 1.9% kgCO2e / (MPa*kgAl material), preferably CO2e / Rp0.2 ≤ 1.6% kgCO2e / (MPa*kgAl material), particularly preferably CO2e / Rp0.2 ≤ 1.2% kgCO2e / (MPa*kgAl material) or CO2e / Rp0.2 ≤ 1.0% kg. CO2e / (MPa*kgAl material). Z I / ZI 230340WO March 28, 2024

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