Battery cell housing and manufacturing method

Abstract

The present invention relates to a battery cell housing and a method for manufacturing the battery cell housing according to the present invention. In order to achieve the object of the present invention, that is, to be able to flexibly meet various requirements of the battery cell housing, such as increased strength requirements or heat conductivity requirements, it can be manufactured very easily and at the same time enables the use of a wide range of aluminum alloys. A battery cell housing having a battery cell housing jacket (1) with at least a regionally rectangular cross-section is provided in that the battery cell housing has a tubular body made of a rolled aluminum alloy as the battery cell housing jacket (1), the battery cell housing jacket (1) is joined in the longitudinal direction and has at least a regionally rectangular cross-section, and the battery cell housing jacket (1) is preferably roll-formed from an aluminum alloy strip (2).

Description

Technical Field

[0001] The present invention relates to a battery cell housing and a method for manufacturing the battery cell housing.

Background Art

[0002] Battery cell housings of various shapes are being manufactured. In addition to pouch-shaped and cylindrical battery cell housings, prismatic battery cell housings are also often used. A prismatic battery cell housing consists of a battery cell jacket, which has a substantially rectangular cross-section and thus allows for a simple and space-saving arrangement of the battery cells. The prismatic battery cell housing has a battery cell housing base and a battery cell housing lid having means for contacting two electrical terminals of the battery cell.

[0003] Currently, prismatic battery cell housings in the form of prismatic cups are mostly manufactured from metal sheet blanks made from aluminum alloy strips using a combination of a deep drawing process and a stretching process having several stretching steps. Only aluminum alloys having particularly good deep drawing properties due to the numerous stretching steps in this manufacturing process can be used to manufacture this housing. The numerous stretching steps increase the cost of this process.

[0004] Alternatively, extrusion may also be used. Extrusion works best with soft aluminum. The higher the strength of the aluminum alloy, the greater the increase in pressing pressure and the lower the productivity. Soft aluminum alloys have the disadvantage of being less suitable for realizing the strength requirements of low-weight battery cell housings.

[0005] A battery cell housing from Patent Document 1, which discloses a battery cell volume greater than 50% by providing elongated, rectangular individual battery cells, is known. A method for manufacturing individual prismatic battery cell housings is not disclosed.

Prior Art Documents

Patent Document

[0006]

Patent Document 1

Summary of the Invention

Means for Solving the Problems

[0007] Based on the above, an object of the present invention is to provide a battery cell casing that can be manufactured very easily and at the same time can flexibly meet various requirements of the battery cell casing, such as increased strength requirements, heat conductivity requirements, or installation space requirements, enabling the use of a wide range of aluminum alloys and casing dimensions. Further, an object of the present invention is to propose a method for manufacturing a battery cell casing according to the present invention.

[0008] According to a first teaching of the present invention, the above object is achieved in that the battery cell casing has a tubular body made of a rolled aluminum alloy as its battery cell casing jacket, the battery cell casing jacket is preferably joined longitudinally by form fitting, friction fitting and / or material fitting, and has at least a regionally rectangular cross-section, and the battery cell casing jacket is preferably roll-formed from an aluminum alloy strip.

[0009] In this specification, the longitudinal direction of the battery cell housing jacket refers to the axis of the tubular body that is perpendicular to the pipe cross-section. By manufacturing the battery cell housing jacket from a tubular body that is roll-formed and seam-connected longitudinally using form fitting, friction fitting, and / or material fitting, it can be manufactured very precisely and in large quantities from a wide variety of aluminum alloys. The height and width of the battery cell housing jacket can be adjusted very precisely and simultaneously flexibly by this roll-forming process. The length of the battery cell housing jacket, i.e., the extent of the battery cell housing jacket in the longitudinal direction, can likewise be very variably selected by dividing the roll-formed tubular body into lengths, providing a very precise geometry of the battery cell housing jacket.

[0010] The tubular body may optionally be coated after seam joining by longitudinal form fitting, friction fitting, and / or material fitting to provide a battery cell housing jacket having a coated surface. Further, it is possible to provide a battery cell housing jacket coated by roll-forming a coated aluminum strip. These have the advantage that, for example, the battery cell housing jacket can be electrically insulated from the electrode winding or electrode stack, and the corrosion prevention of the battery cell housing jacket is further improved.

[0011] Welding methods such as metal inert gas welding (MIG welding), friction stir welding, laser welding or induction welding, as well as soldering, adhesive bonding and flanging are possible joining methods for connections using form fitting, friction fitting and / or material fitting in the longitudinal direction. According to one preferred embodiment, the battery cell housing jacket is seam welded in the longitudinal direction and has a weld seam in the longitudinal direction. The longitudinal seam welding of the tubular body is a known technique from pipe manufacturing that can produce a high welding speed and a high-quality weld seam in the battery cell housing jacket. The longitudinal seam welding can be carried out during the manufacture of the battery cell housing jacket and inline, for example after roll forming and before cutting to the length of the battery cell housing.

[0012] According to a further embodiment, in order to meet the desired strength requirements of the battery cell housing as a function of the selected aluminum alloy, the wall thickness of the battery cell housing jacket is preferably between 0.2 mm and 1.2 mm. The higher the strength of the aluminum alloy, the smaller the wall thickness and the larger the internal volume can be. These in turn make it possible to optimize the volumetric energy density of the battery cell. This is because a larger volume fraction of the battery cell is available for the active material.

[0013] In a further configuration of the prismatic battery cell housing, the ratio of the height to the width of the battery cell housing jacket is greater than 3 and less than 10, preferably between 5 and 8. The ratio of the height to the width of the battery cell housing jacket can be provided in a straightforward manner using the roll forming process.

[0014] According to the next configuration of the prismatic battery cell housing, the inner radius R i of the battery cell housing jacket satisfies the following condition with respect to the thickness d of the aluminum alloy strip, R i ≦ 2.5 * d, preferably R i ≦ 1.5 * d or particularly preferably 0.1 * d ≦ R i ≦ 1.5 * d, When the above is satisfied, on the one hand, good stability of the present battery cell casing can be achieved, and on the other hand, an optimized internal volume of the present battery cell casing can be provided. This is because sufficient space is available without any problem for arranging the electrode winding body or the electrode stack of the battery cell.

[0015] In a further configuration of the present battery cell casing, the battery cell casing jacket has at least one pressure relief means, preferably at least one rupture element and / or a pressure valve. This means prevents the battery cell casing from exceeding the critical pressure inside the battery cell casing. This at least one pressure relief means can be introduced or arranged in or on the battery cell casing jacket, for example, by laser method, embossing method, punching method, friction fitting and / or material bonding insertion before, during or after the rolling forming process. The present pressure relief means can be activated to avoid further pressure increase and / or to reduce the pressure to avoid a critical thermal runaway in the battery cell when the pressure inside the battery cell casing increases to a pressure greater than, for example, 5 bar, preferably greater than 7.5 bar.

[0016] Preferably, a joining seam, particularly a welding seam, is arranged on the long-narrow surface of the battery cell casing jacket. The long-narrow surface means the side surface of the battery cell casing jacket having a narrower width perpendicular to the rolling forming direction, that is, in the longitudinal direction of the battery cell casing jacket. This results in good joinability or weldability of the rolled tubular body in the longitudinal direction, combined with a relatively low mechanical load in the event of a pressure increase or damage during the operation of the battery. At the same time, the long-narrow surface allows for a greater dimensional tolerance without having a damaging effect on the electrode winding body or the electrode stack with respect to the formation of the joining seam or the welding seam.

[0017] The weldability of the rolled aluminum alloy strip is improved, in particular, when MIG welding or induction welding the rolled aluminum alloy strip, by the surface tension of the surface of the rolled aluminum alloy strip being preferably greater than 30 mN / m, more preferably greater than 40 mN / m, and particularly preferably greater than 50 mN / m, preferably immediately before welding. The surface tension of the surface of the rolled aluminum strip can be measured with good accuracy, for example, by using test ink. For this purpose, the aluminum alloy strip is subjected to degreasing or corona treatment using plasma. This can be done, for example, in-line with the manufacture of welded housing cell jackets.

[0018] Preferably, this battery cell housing jacket consists of an aluminum alloy having the following composition by weight percentage: Si < 0.5%, Fe < 0.8%, Cu < 0.5%, Mn ≤ 1.5%, Mg < 1.3%, preferably < 0.5% or 2.5% < Mg < 6.0%, preferably 3.0% < Mg < 6.0%, Cr < 0.2%, Zn < 0.25%, Ti ≤ 0.1%, preferably 0.001% ≤ Ti ≤ 0.1%, with the balance being Al and unavoidable impurities of at most 0.05% individually and at most 0.15% in total.

[0019] ​The aluminum alloy having the foregoing composition can generally be well rolled and further welded. Furthermore, they can provide various strength characteristics of the battery cell casing jacket depending on, for example, the copper, manganese or magnesium content. An Si content of less than 0.5% by weight during welding of the battery cell casing jacket allows for a low hot cracking tendency. An Fe content of less than 0.8% by weight allows for a high recycling rate and further combines with Si in combination with Mn and Al to form the AlMnFeSi phase, which further reduces the hot cracking tendency during welding. A Cu content of less than 0.5% by weight allows the strength increasing effect of copper to be utilized without significantly weakening the corrosion resistance. Furthermore, the hot cracking tendency increases as the Cu content increases. An Mn content of less than 1.5% by weight, preferably less than 1.2% by weight, allows for precise control of recrystallization and microstructure by the formation of dispersoids, particularly increasing the thermal stability of the aluminum alloy. Furthermore, Mn forms the AlMnFeSi phase in combination with Fe and Si, which reduces the Si content in the solid solution, thereby reducing the hot cracking tendency. An Mg content of less than 1.0% by weight, preferably less than 0.5% by weight, results in a moderate increase in strength and a low hot cracking tendency during welding. A Cr content of less than 0.2% by weight is suitable for the formation of additional dispersoid phases, and these phases in turn stabilize the microstructure under thermal stress. A Zn content of less than 0.25% by weight and a Ti content of at most 0.1% by weight or from 0.001% to at most 0.1% by weight allow the use of recycled alloys, particularly recycled alloys containing Mn. Furthermore, a Ti content of from 0.001% to 0.1% by weight allows the addition of Ti-based grain refinement additives for optimizing the casting structure. Limiting the unavoidable impurities to at most 0.05% by weight individually and at most 0.15% by weight in total does not change the favorable effects of the alloy components.

[0020] Alternatively, in order to provide the highest possible strength of the battery cell housing jacket, the lowest possible wall thickness and thus the optimized weight of the prismatic battery cell, as well as a low tendency to hot cracking during welding and thus high process reliability, there may also be an Mg content of greater than 2.5 wt% and less than 6.0 wt%, preferably greater than 3.0 wt% and less than 6.0 wt%.

[0021] When the best possible thermal conductivity rather than the strength and weight of the battery cell housing is most important, the battery cell housing jacket has the following in weight percent: Si < 0.25%, Fe < 0.4%, Cu < 0.2%, Mn ≤ 0.05%, Mg < 0.5%, Cr < 0.2%, Zn < 0.1%, 0.001% ≤ Ti ≤ 0.1%, with the balance being Al and unavoidable impurities of at most 0.05% individually and at most 0.15% in total, and is advantageously made of an aluminum alloy of type AA1xxx having this composition.

[0022] For example, AA1xxx aluminum alloys of type AA1050 can be welded very well because the proportions of alloying elements (Si, Cu, Mg) that increase the tendency for hot cracking are very limited. Furthermore, these alloys have high corrosion resistance. Additionally, they provide sufficiently high strength and very high thermal conductivity in the mill-hardened state H18. The high thermal conductivity of this battery cell housing ensures rapid heat dissipation from the interior of the battery cell, and thus, in particular, improves the performance of the battery cell in situations of high charge or discharge rates. To minimize the tendency for hot cracking in the welding process, an Si content of less than 0.25 wt% is preferred. An Fe content of less than 0.4 wt% enables the use of pure metals and industrial primary metals at commercial levels, which is favorable in terms of availability and cost. A Cu content of less than 0.2 wt% enables alloying with copper to increase strength by solid solution formation while minimizing the tendency for hot cracking. Mn strongly adversely affects the electrical and thermal conductivity of aluminum alloys whether in the dissolved state or in the intermetallic phase, and is thus limited to less than 0.05 wt%. Mg contributes to strength by solid solution hardening, especially in the cold-worked state. However, the tendency for hot cracking increases with increasing Mg content, and therefore the Mg content is limited to <0.5 wt%. As a dispersoid former, Cr contributes to the control of the microstructure in the recovery and recrystallization processes and to the stabilization of the microstructure under thermal stress. However, Cr decreases the electrical and thermal conductivity, and therefore the Cr content is limited to less than 0.2 wt%. Zn decreases the corrosion resistance and is thus limited to less than 0.1 wt%. Ti is used for grain refinement or to optimize the casting structure during the casting process. However, Ti decreases the electrical and thermal conductivity relatively strongly, and therefore the Ti content is limited to 0.001 wt% ≤ Ti ≤ 0.1 wt%.

[0023] According to a further configuration, this battery cell housing jacket has the following, by weight: Si < 0.6%, Fe < 0.8%, Cu ≤ 0.5%, 0.3% ≤ Mn ≤ 1.5%, preferably 0.6% ≤ Mn ≤ 1.2%, Mg < 1.3%, preferably 0.8% ≤ Mg ≤ 1.3%, more preferably 0.01% < Mg < 0.5%, Cr < 0.2%, Zn < 0.25%, Ti ≤ 0.1%, preferably 0.001 wt% ≤ Ti ≤ 0.1 wt%, the balance being Al and unavoidable impurities of at most 0.05% individually and at most 0.15% in total, and made of an aluminum alloy of type AA3xxx having the composition.

[0024] For example, the AA3xxx aluminum alloy of type AA3003 has a higher maximum strength, particularly a higher yield strength Rp, than the AA1xxx aluminum alloy 0.2provides a maximum value. A silicon content of less than 0.6 wt% in combination with the iron content and manganese content according to the invention at a specified amount results in particularly dense particles of the quaternary α-Al(Fe,Mn)Si phase that are relatively uniformly distributed. These precipitated particles remove iron and manganese from the solid solution without adversely affecting other properties such as corrosion behavior, i.e., electrolyte stability or formability, thus increasing both the strength of the aluminum alloy and its electrical and thermal conductivity. An iron content of less than 0.8 wt% in combination with the manganese content according to the invention at a specified amount leads to the formation of the Al6(Mn,Fe) phase and, in combination with the silicon content and manganese content according to the invention at a specified amount as already explained above, to the precipitation of particles of the quaternary α-Al(Fe,Mn)Si phase. The iron in this case contributes to reducing the solubility of manganese in aluminum, so that more manganese is trapped in the intermetallic phase, which has a beneficial effect on electrical and thermal conductivity. Furthermore, the intermetallic phase affects the recovery and recrystallization processes and improves the thermal stability of the mechanical properties. An iron content greater than 0.8 wt% promotes the formation of coarse intermetallic phases, which can reduce formability in the deep drawing process. Since a maximum copper content of at most 0.5 wt% is possible, the strength of this alloy can be increased by solid solution formation. Furthermore, an increase in the tolerance of the aluminum alloy with respect to copper-containing aluminum alloy scrap is achieved, which promotes the realization of a high proportion of recycled material in the production of this battery housing. However, an excessively high copper content can adversely affect the corrosion properties, so the copper content is limited to at most 0.5 wt% according to the invention in order to achieve sufficient electrolyte stability. As already explained above, a manganese content of 0.3 wt% ≤ Mn ≤ 1.5 wt%, preferably 0.6 wt% ≤ Mn ≤ 1.2 wt%, results in the precipitation of particles of the quaternary α-Al(Fe,Mn)Si phase as well as the Al6(Mn,Fe) phase in combination with the silicon content and iron content at a specified amount. These intermetallic phases impede the recovery and recrystallization processes and thus improve the thermal stability of the mechanical properties. A manganese content of less than 0.6 wt% reduces the increase in strength already by dispersoid and solid solution hardening.A Mn content of less than 0.3 wt% results in an insufficient increase in strength and a decrease in thermal and electrical conductivity compared to 1xxx alloys due to dispersoids and solid solution hardening, while a manganese content greater than 1.5 wt%, especially greater than 1.2 wt%, promotes the formation of coarse intermetallic phases that have an adverse effect on the forming properties. Furthermore, a manganese content greater than 1.5 wt%, especially greater than 1.2 wt%, significantly reduces the electrical and thermal conductivity of the battery cell housing to such an extent that thermal management becomes ineffective. In order to achieve an improvement in mechanical properties while maintaining good weldability, the magnesium content in the foregoing embodiments is limited to less than 1.3 wt%, preferably 0.8 wt% ≤ Mg ≤ 1.3 wt%, more preferably 0.01% < Mg < 0.5%. These preferred ranges represent a compromise between high strength, good formability, and high electrical and thermal conductivity, along with good weldability, and recyclability with respect to Mn-containing scrap. As the Mg content increases, strength and formability improve, and electrical and thermal conductivity decrease somewhat. As the Mg content decreases, electrical and thermal conductivity improve, and strength decreases. As a dispersoid former, Cr contributes to the control of the microstructure in the recovery and recrystallization processes and the stabilization of the microstructure under thermal stress. However, Cr decreases electrical and thermal conductivity, and therefore the Cr content is limited to less than 0.2 wt%. Zn reduces corrosion resistance and is therefore limited to less than 0.25 wt%. Ti is used for grain refinement or to optimize the casting structure during the casting process. However, Ti reduces electrical and thermal conductivity relatively strongly, and therefore the Ti content is limited to at most 0.1 wt%, preferably 0.001 wt% ≤ Ti ≤ 0.1 wt%. AA3xxx aluminum alloys are also highly formable and can be welded and soldered well. The aforementioned upper limits for silicon, iron, copper, magnesium, chromium, zinc, and titanium result in good suitability of the aluminum alloy for use in a high recycling rate of at least 70% to over 90% in the aluminum alloy. For example, sufficient strength for this battery cell housing jacket has already been achieved with an aluminum alloy of type AA3003 in the H14 or H16 condition.Higher strength AA3xxx aluminum alloys, such as AA3104, already achieve these properties in the H14 condition as well.

[0025] To provide even higher strength, according to a further configuration, this battery cell housing jacket is made of an AA5xxx type aluminum alloy having the following composition by weight percentage: Si < 0.3%, Fe < 0.4%, Cu < 0.2%, Mn < 0.8%, 2.5% < Mg < 6.0%, preferably 3.0% < Mg < 6.0%, Cr < 0.2%, Zn < 0.25%, Ti ≦ 0.1%, preferably 0.001% ≦ Ti ≦ 0.1%, with the balance being Al and unavoidable impurities of at most 0.05% individually and at most 0.15% in total. It consists of an AA5xxx type aluminum alloy having the composition.

[0026] Due to the achievable high strength, battery cell housing jackets made of AA5xxx alloys can meet severe load requirements and can thus be considered as structural components, for example, in passenger cars. An Mg content greater than 2.5 wt%, preferably greater than 3.0 wt%, causes an increase in strength. Furthermore, at these Mg contents, the maximum hot cracking tendency has already been exceeded, so that an Mg content greater than 2.5 wt%, preferably greater than 3.0 wt%, enables an efficient welding process. At least 6.0 wt%, the solidification during cold rolling increases greatly and the vulnerability to intergranular corrosion increases greatly, so that the processing of aluminum alloys by cold rolling becomes increasingly difficult. An Si content of less than 0.3 wt% is preferred in order to minimize the hot cracking tendency during the welding process, to remove Mg from the solid solution, and thus to avoid the formation of the Mg2Si phase that reduces solid solution hardening. Fe is present as an impurity in primary industrial metals as well as an impurity by recycling. An Fe content of less than 0.4 wt% in combination with an Mn content of less than 0.8 wt% results in the formation of the AlMnFe phase, which contributes as a dispersoid to the effective control of recrystallization and recovery and thus enables the optimization of the grain structure. Higher Fe contents may result in the formation of coarse intermetallic phases, while an Mn content exceeding 0.8 wt% significantly reduces the thermal and electrical conductivities. As a dispersoid former, Cr contributes to the control of the microstructure in the recovery and recrystallization processes as well as the stabilization of the microstructure under thermal stress. However, Cr reduces the electrical and thermal conductivities, so that the Cr content is limited to less than 0.2 wt%. Zn reduces the corrosion resistance and is thus limited to less than 0.25 wt%. Ti is used for grain refinement or to optimize the casting structure during the casting process. However, Ti reduces the electrical and thermal conductivities relatively strongly, so that the Ti content is limited to at most 0.1 wt%, preferably 0.001 wt% ≤ Ti ≤ 0.1 wt%.

[0027] In order for the battery cell housing to achieve sufficient pressure stability, a sufficiently high strength of the battery cell housing jacket is required. For example, a battery cell housing jacket made of a rolled aluminum alloy strip made of alloy type AA5754 already achieves sufficient strength in the state H12. When an aluminum alloy strip made of aluminum alloy type AA5083 is used to manufacture this battery cell housing jacket, these already achieve sufficient strength in the soft annealed state O.

[0028] According to the following configuration, the original aluminum alloy strip from which the battery cell housing jacket of this battery cell housing is roll-formed has a yield strength Rp of at least 120 MPa, preferably at least 150 MPa 0.2 If it has, this ensures that the battery cell housing achieves sufficient pressure stability without requiring an overly large wall thickness that significantly reduces the volumetric energy density of the battery cell, especially with respect to the strength of the battery cell housing jacket.

[0029] Finally, a battery cell housing according to the following configuration has two lids connected to the battery cell housing jacket by form fitting, friction fitting and / or material fitting. These lids can be made from a wide range of materials. Plastics as well as ceramic materials or die-cut aluminum alloy sheets are suitable for this purpose. These lids can be joined by an adhesive, welded or soldered to form a material fitting connection. For lids made of aluminum alloy, for example, laser welding or laser soldering may be suitable. However, in the case of aluminum materials, a flanging method can also be envisaged for connection by form fitting and / or friction fitting.

[0030] The object shown above is also achieved by a method for manufacturing a battery cell housing according to the invention, which includes the following. - An aluminum alloy strip is produced by hot rolling and / or cold rolling from an ingot or a cast strip, - The rolled aluminum alloy strip is further processed using roll forming and longitudinal die fitting, friction fitting and / or material seam joining, in particular longitudinal seam welding, to form a closed tube having at least a regionally rectangular cross-section, and - The roll formed and joined tube is divided into shorter subsections perpendicular to its longitudinal axis, which are used as battery cell housing jackets.

[0031] By the method according to the invention, a battery cell housing having at least a regionally rectangular cross-section is produced in a simple and economical way, and various aluminum alloys can be used so as to be able to meet the various requirements of the battery cell housing in principle.

[0032] The welding speed during longitudinal seam welding can preferably be greater than 2.5 m / min, greater than 5 m / min or preferably greater than 10 m / min. By using various aluminum alloys, for example from type AA1xxx aluminum alloys having high thermal conductivity through type AA3xxx aluminum alloys suitable for recycling to type AA5xxx high-strength aluminum alloys, a battery cell housing having a battery cell housing jacket with at least a regionally rectangular cross-section can be produced in the same process.

[0033] Preferably, according to a first embodiment of the method, post-treatment of the weld seam root portion is performed for smoothing the weld seam root portion. This can further reduce the influence of the weld seam root portion on the electrode winding or electrode stack of the battery cell. This method step can be performed immediately after welding, in particular longitudinal seam welding. The weld seam root portion smoothing can be carried out, for example, by reheating the weld seam with a welding beam in a heat conduction mode.

[0034] According to a further configuration of the method, after cutting the battery cell housing jacket to the required length, in order to provide a battery cell housing in the form of a cup having at least regionally a rectangular cross-section for receiving the electrode winding or the electrode stack, one of the two end faces of the hitherto open battery cell housing jacket is closed by a lid using form fitting, friction fitting and / or material fitting.

[0035] Next, in a further automated step, the electrode winding or the electrode stack is inserted into this cup closed at one end and can be filled with an electrolyte. Next, the cell housing may be closed with a second lid using form fitting, friction fitting and / or material fitting to form the finished prismatic battery.

[0036] Alternatively, the electrode winding or the electrode stack may first be inserted into the battery cell housing jacket so that particularly good accessibility of the bonding zone for connecting the electrode stack to the terminals is ensured. The battery cell housing may then first be closed with a lid on one side using form fitting, friction fitting and / or material fitting to form a cup, which cup is filled with an electrolyte in a further manufacturing process and may then be closed with a second lid using form fitting, friction fitting and / or material fitting. Alternatively, filling with an electrolyte through the lid after form fitting, friction fitting and / or material closing of the battery cell housing on both sides may be envisaged.

[0037] The invention will be described in more detail below with the aid of embodiments in conjunction with the drawings.

Brief Description of the Drawings

[0038]

Figure 1

Figure 2

Figure 3

Figure 4

[0039] FIG. 1 shows an exemplary embodiment of a battery cell housing jacket 1 of a battery cell housing having a tubular body that is roll-formed and has at least a regionally rectangular cross-section and is welded. The battery cell housing jacket 1 is roll-formed from an aluminum alloy strip 2. The battery cell housing jacket 1 of the exemplary embodiment is seam-joined longitudinally using form fitting, friction fitting, and / or material fitting, and in this example is seam-welded longitudinally. In the exemplary embodiment, the weld seam 3 of the battery cell housing jacket 1 is provided on the long-narrow side 5 of the battery cell housing jacket.

[0040] Preferably, the wall thickness of the battery cell housing jacket is 0.2 mm to 1.2 mm. Using this wall thickness in combination with the selection of the aluminum alloy, specific properties can be provided to the battery cell housing jacket 1 having at least a regionally rectangular cross-section, and thus to the corresponding battery cell housing.

[0041] Preferably, the aluminum alloy of the battery cell housing jacket 1 is, by weight percentage, the following: Si < 0.5%, Fe < 0.8%, Cu < 0.5%, Mn ≦ 1.5%, Mg < 1.3%, preferably < 0.5% or 2.5% < Mg < 6.0%, preferably 3.0% < Mg < 6.0%, Cr < 0.2%, Zn < 0.25%, 0.001% < Ti < 0.1%, The balance is Al and unavoidable impurities of at most 0.05% individually and at most 0.15% in total. It has an alloy composition.

[0042] Furthermore, the battery cell housing jacket 1 has the following in weight percentage: Si < 0.25%, Fe < 0.4%, Cu < 0.2%, Mn ≤ 0.05%, Mg < 0.5%, Cr < 0.2%, Zn < 0.1%, 0.001% < Ti < 0.1%, The balance is Al and unavoidable impurities of at most 0.05% individually and at most 0.15% in total. An aluminum alloy of type AA1xxx having the composition, or The following in weight percentage: Si < 0.6%, Fe < 0.8%, Cu ≤ 0.5%, 0.3% ≤ Mn ≤ 1.5%, preferably 0.6% ≤ Mn ≤ 1.2%, Mg < 1.3%, preferably 0.8% ≤ Mg ≤ 1.3%, more preferably 0.01% < Mg < 0.5%, Cr < 0.2%, Zn < 0.25%, 0.001% < Ti < 0.1%, The balance is Al and unavoidable impurities of at most 0.05% individually and at most 0.15% in total. An aluminum alloy of type AA3xxx having the composition. or The following in weight percentage: Si < 0.3%, Fe < 0.4%, Cu < 0.2%, Mn < 0.8%, 2.5% < Mg < 6.0%, preferably 3.0% < Mg < 6.0%, Cr < 0.2%, Zn < 0.25%, 0.001% < Ti < 0.1%, The balance consists of Al and inevitable impurities of at most 0.05% individually and at most 0.15% in total. It may also be made of an aluminum alloy of type AA5xxx having the composition.

[0043] The battery cell jacket 1 of the battery cell housing can be manufactured by roll forming from an aluminum strip made of the various aluminum alloys described above. The various compositions of these aluminum alloys result in different characteristic profiles of this battery cell housing or this battery cell jacket 1. For example, the A1xxx aluminum alloy has, among other things, maximum thermal conductivity and yield strength Rp in the mill hard states H18 or H19 in addition to high corrosion resistance. 0.2 and favorable values for. The AA3xxx aluminum alloy has very good formability as well as good weldability or solderability and high thermal stability. The AA3xxx aluminum alloy suitable for recycling already has favorable strength, particularly yield strength Rp, in the states H14 and H16. 0.2 and may consist of more than 90% recycled aluminum. The AA5xxx aluminum alloy may provide favorable yield strength Rp values in combination with already high ductility in the state O or H12. 0.2 In one or both of these structural states having both higher yield strength Rp 0.2 and high ductility at the same time, a particularly low wall thickness is used for the battery cell jacket 1 in the case of the AA5xxx aluminum alloy and may thus be useful for volume optimization of the wound electrodes or electrode stack of the battery cell.

[0044] The length L of this battery cell jacket may be, for example, 100 mm to 400 mm. Longer lengths L are also conceivable and can be provided without problems using the roll-formed battery cell jacket 1.

[0045] According to the exemplary embodiment shown in FIG. 1, the ratio of the height H to the width B of the battery cell housing jacket may be greater than 3 and less than 10, preferably 5 to 8. The width B may vary, for example, from 15 to 45 mm, and the height H may vary, for example, from 50 to 200 mm.

[0046] Preferably, the inner radius R of the battery cell housing jacket 1 i has at most 2.5 times, at most 1.5 times or at most 0.1 times to 1.5 times the sheet thickness d of the aluminum strip 2 with respect to the thickness of each rolled aluminum alloy strip 2.

[0047] These inner radii R i result in an optimized volumetric energy density of the battery cell that can be achieved by the high packing density and thus the battery cell housing according to the present invention, and at the same time enable reliable manufacturing of the battery cell housing jacket 1 by rolling.

[0048] As also shown in this exemplary embodiment, the weld seam is preferably arranged on the long-narrow surface 5 of the battery cell housing jacket 1. This position is subject to a low load when the internal pressure increases and is sufficiently accessible for the longitudinal seam welding process.

[0049] On the long-narrow side 5, preferably at least one pressure relief means, represented herein as rupture element 5a, is also provided. The rupture element 5a is configured in the form of an embossing method or a laser method. The material in the region of the rupture element deliberately weakens the battery cell housing at this location, so that the pressure stability decreases compared to the surrounding area when the local internal pressure is exceeded at the region of the rupture element. In such a way, it is thinned by the embossing method or locally converted to a soft state using a laser. The internal pressure of the battery cell housing can be deliberately reduced to prevent an uncontrolled rupture of the entire battery cell housing in the event of a significant thermal runaway when the internal pressure is unacceptably high, and thus substantially maintain its structural integrity.

[0050] The aluminum strip of the battery cell housing jacket 1 preferably has a yield strength Rp of at least 120 MPa, preferably greater than 150 MPa. 0.2 This ensures that the battery cell housing jacket 1 has very good pressure stability, especially internal pressure stability.

[0051] Figs. 2 and 3 schematically show plan views of the upper lid 6 and the lower lid 9 of a battery cell housing having the battery cell housing jacket 1. The additional embossing lines 6a or 9a on the lids 6 and 9 create stiffening of the lids of the battery cell housing and can be easily introduced, for example, when using an aluminum alloy to manufacture these lids. For power supply through the electrical contacts of the electrode winding body of the battery cell, two cutouts 7 and 8 are schematically provided in the lid of Fig. 2 for receiving the terminals of the battery cell, respectively. These terminals are indicated as minus and plus. The electrical contacts may be powered through one side of the lid. Alternatively, the electrical contacts may be powered through each lid respectively, so that a plurality of battery cells may be interconnected at each lid at the pipe end.

[0052] The lids 6 and 9 may be connected to the battery cell housing jacket 1 in separate or similar ways by form fitting, friction fitting and / or material fitting, in which case various joining techniques such as welding, soldering and / or adhesive bonding or a combination of several joining techniques may be appropriate.

[0053] Furthermore, the lid geometry may be used to create purely frictional connections or combinations of snap, friction and / or material clamping connections. However, at the same time, for example, if lids 6 or 9 are flange-coupled to the battery cell housing jacket, lids that are purely snap-fitted to the battery cell housing may also be provided. Furthermore, the use of different materials, such as plastics or ceramics, for lids 6 and 9 of the battery cell housing can also be envisaged. Thus, the connection technique for connecting the battery cell housing jacket 1 to lids 6, 9 depends on the material of the selected lid.

[0054] Next, FIG. 4 shows a schematic view of an exemplary embodiment of a method for manufacturing a battery cell housing having a battery cell housing jacket having at least a regionally rectangular cross-section, wherein an aluminum alloy strip is produced from a bar or casting strip by hot rolling and / or cold rolling, and the rolled aluminum alloy strip 2 is roll-formed into a tubular battery cell housing jacket 1 having at least a regionally rectangular cross-section, and the battery cell housing jacket 1 is welded and cut to length.

[0055] In FIG. 4, an aluminum alloy strip 2 wound around a coil 10 is schematically shown. The aluminum alloy strip 2 is unwound from this aluminum coil 10 and fed to a roll-forming device 11. As shown in FIG. 4, the aluminum alloy strip 2 is then roll-formed in the roll-forming device 11, for example, in various sub-steps 2a, 2b, 2c, into a battery cell housing jacket 1 having a rectangular cross-section. At the end of this roll-forming process, a tubular battery cell housing jacket exits the roll-forming device 11.

[0056] The tubular battery cell housing jacket 1 with a rectangular cross-section exits the rolling forming device 11 and is seam welded longitudinally using welding means 13. Further processing of the weld seam path, such as smoothing the weld of the weld seam or other post-processing, is not shown in FIG. 4. Further, at least one rupture element may be introduced into the battery cell housing jacket 1 by an embossing method before and / or after the longitudinal seam joining or welding of the battery cell housing jacket 1. Next, the battery cell housing jacket 1 having a predetermined length L is separated using cutting means 14.

[0057] For example, the possibility of coating the battery cell housing jacket 1 before or after welding is not shown. Alternatively, the manufactured battery cell housing jacket 1 may be sent for individual coating.

[0058] After cutting the battery cell housing jacket to the required length, in order to provide a battery cell housing in the form of a cup having a rectangular cross-section for receiving at least a regionally electrode winding body or electrode stack and now having one side open and later filled with electrolyte, it is not shown in FIG. 4 that one of the two open end faces of this battery cell housing jacket can be closed by a lid using form fitting, friction fitting and / or material fitting. After closing the side which was hitherto the other side of the cup-shaped battery cell housing including the installation of the connection terminals of the battery cell, a completed battery cell having at least regionally a battery cell housing jacket 1 with a rectangular cross-section is available.

[0059] All of the manufacturing steps described so far are carried out in a highly automated manner and can provide an economical mass production of battery cell housing jackets 1 in a wide variety of shapes and lengths. Thus, a battery cell housing having at least regionally a rectangular cross-section of the battery cell housing jacket 1 can be economically manufactured with a wide variety of properties with respect to a wide variety of applications and with respect to the strength of the battery cell housing or, for example, the thermal conductivity of the battery cell housing.

Claims

1. A battery cell housing, wherein the battery cell housing has a tubular body made of a rolled aluminum alloy as the battery cell housing jacket (1), the battery cell housing jacket (1) is joined in the longitudinal direction and has at least a regionally rectangular cross-section, the battery cell housing jacket (1) is preferably roll-formed from an aluminum alloy strip (2), and the battery cell housing has two covers (6, 9) connected to the battery cell housing jacket (1) using form fitting, friction fitting and / or material fitting, The battery cell housing jacket (1) has at least one yield strength Rp according to DIN EN ISO 6892-1 of at least 120 MPa, preferably at least 150 MPa ０．２ and has characterized in that it is a battery cell housing.

2. The battery cell housing according to claim 1, characterized in that the battery cell housing jacket (1) is seam-welded in the longitudinal direction and has a weld seam (3) in the longitudinal direction.

3. The battery cell housing according to claim 1 or 2, characterized in that the wall thickness of the battery cell housing jacket (1) is 0.2 mm to 1.2 mm.

4. The battery cell housing according to any one of claims 1 to 3, characterized in that the ratio of the height (H) to the width (B) of the battery cell housing jacket (1) is greater than 3 and less than 10, preferably 5 to 8.

5. The inner radius R of the battery cell housing jacket (1) ｉ satisfies the following condition with respect to the thickness d of the roll-formed aluminum alloy strip (2), R ｉ ≦ 2.5 * d, preferably R ｉ ≦ 1.5 * d, particularly preferably 0.1 * d ≦ R ｉ ≦ 1.5 * d, and the battery cell housing according to any one of claims 1 to 4 is characterized in that it satisfies this condition.

6. The battery cell housing according to any one of claims 1 to 5, characterized in that the battery cell housing jacket (1) has at least one pressure relief means, preferably at least one rupture element (5a) and / or at least one pressure valve, which prevents the battery cell housing from exceeding the critical pressure inside the battery cell housing.

7. The battery cell housing according to any one of claims 1 to 6, characterized in that a joining seam, in particular a weld seam (3), is arranged on the long-narrow surface (5) of the battery cell housing jacket (1).

8. The battery cell housing according to any one of claims 1 to 7, characterized in that the surface tension of the aluminum alloy strip (2) supplied to the roll-forming process is greater than 30 mN / m, preferably greater than 40 mN / m, and particularly preferably greater than 50 mN / m.

9. The battery cell housing jacket (1) has the following by weight percentage, Si < 0.5%, Fe < 0.8%, Cu < 0.5%, Mn ≤ 1.5%, Mg < 1.3%, preferably < 0.5% or 2.5% < Mg < 6.0%, preferably 3.0% < Mg < 6.0%, Cr < 0.2%, Zn < 0.25%, Ti ≤ 0.1%, preferably 0.001% ≤ Ti ≤ 0.1%, the balance being Al and unavoidable impurities of at most 0.05% individually and at most 0.15% in total, characterized in that it is made of an aluminum alloy having the composition, the battery cell housing according to any one of claims 1 to 8.

10. The battery cell housing jacket (1) has the following, by weight%, Si < 0.25%, Fe < 0.4%, Cu < 0.2%, Mn ≤ 0.05%, Mg < 0.5%, Cr < 0.2%, Zn < 0.1%, 0.001% ≤ Ti ≤ 0.1%, the balance being Al and unavoidable impurities of at most 0.05% individually and at most 0.15% in total, characterized in that it is made of an aluminum alloy of type AA1xxx having the composition, the battery cell housing according to claim 9.

11. The battery cell housing jacket (1) has the following, by weight%, Si < 0.6%, Fe < 0.8%, Cu ≤ 0.5%, 0.3% ≤ Mn ≤ 1.5%, preferably 0.6% ≤ Mn ≤ 1.2%, Mg < 1.3%, preferably 0.8% ≤ Mg ≤ 1.3%, more preferably 0.01% < Mg < 0.5%, Cr < 0.2%, Zn < 0.25%, Ti ≤ 0.1%, preferably 0.001% ≤ Ti ≤ 0.1%, the balance being Al and unavoidable impurities of at most 0.05% individually and at most 0.15% in total, characterized in that it is made of an aluminum alloy of type AA3xxx having the composition, the battery cell housing according to claim 9.

12. The battery cell housing jacket (1) has the following, by weight%, Si < 0.3%, Fe < 0.4%, Cu < 0.2%, Mn < 0.8%, 2.5% < Mg < 6.0%, preferably 3.0% < Mg < 6.0%, Cr < 0.2%, Zn < 0.25%, Ti ≤ 0.1%, preferably 0.001% ≤ Ti ≤ 0.1%, the balance being Al and unavoidable impurities of at most 0.05% individually and at most 0.15% in total, characterized in that it is made of an aluminum alloy of type AA5xxx having the composition, the battery cell housing according to claim 9.

13. - An aluminum alloy strip (2) is manufactured from an ingot or a casting strip by hot rolling and / or cold rolling, - The rolled aluminum alloy strip (2) is further processed using roll forming and longitudinal joining, in particular longitudinal seam welding, to form a closed tubular body made of an aluminum alloy having at least a regionally rectangular cross-section, and - The roll-formed tubular body is divided perpendicular to its longitudinal axis into shorter subsections and used as the battery cell housing jacket (1), A method for manufacturing a battery cell housing according to claims 1 to 12, characterized in that.

14. The aluminum alloy strip (2) is seam welded longitudinally after the roll forming, and the welding speed is preferably greater than 2.5 m / min, greater than 5 m / min, or preferably greater than 10 m / min. The method according to claim 13, characterized in that.

15. The method according to claim 13 or 14, characterized in that post-treatment of the weld seam root is performed to smooth the weld seam root.

16. After cutting the battery cell housing jacket (1) to the required length, in order to provide a battery cell housing in the form of a cup having at least a regionally rectangular cross-section for receiving the electrode winding or the electrode stack, one of the two open end faces of the battery cell housing jacket (1) is closed by a lid (6a, 9a) using die fitting, friction fitting and / or material fitting. The method according to any one of claims 13 to 15, characterized in that.

17. At least one pressure relief means is introduced or arranged in or on the battery cell housing jacket by means of an insert joined using a laser method, an embossing method, a punching method, friction fitting and / or material fitting before, during or after the roll forming process. The method according to any one of claims 13 to 16, characterized in that.

Images