METHOD FOR CONSOLIDATING MULTILAYER FILMS BY HOT PRESSING

Abstract

A method for consolidating a foil strip stack is provided. The method comprises combining foil strips of an electrode stack in a battery cell to form a combined foil strip stack. Furthermore, the method comprises hot-pressing the combined foil strip stack using heated press dies to form a consolidated foil strip stack. Furthermore, the method comprises laser welding the combined foil strip stack to a lead wire using a laser welder.

Description

INTRODUCTION

[0001] The present description relates to electrode stacks in a battery cell and in particular to the consolidation of electrode strips in the electrode stacks.

[0002] A battery cell, e.g., a prismatic battery cell, typically comprises a plurality of electrode stacks. Each of the electrode stacks contains anode electrode strips and cathode electrode strips extending from the electrode stack. The electrode tabs of the electrode stacks are welded and connected to connecting leads or current collectors. The current collectors are metal plates that concentrate the electrical current generated by the electrode stacks and transmit it to the battery cell terminals. During welding of the electrode strips, surface contaminants on the electrode strips can release gases that can form air cavities. These air cavities, combined with the stresses created by shrinkage during solidification, can lead to delamination of the electrode strips at the melt boundaries.

[0003] While prior art methods and systems attempt to minimize electrode strip delamination at weld boundaries and may achieve their specific purpose, there is a need for a new and improved method to reduce electrode strip delamination. Accordingly, a method that minimizes electrode strip delamination is needed. DESCRIPTION

[0004] According to several aspects of the present description, a method for consolidating a foil strip stack is provided. The method comprises combining foil strips of an electrode stack in a battery cell to form a combined foil strip stack. Furthermore, the method comprises hot-pressing the combined foil stack using heated press dies to form a consolidated foil strip stack. Furthermore, the method comprises laser welding the combined foil strip stack to a lead wire using a laser welder.

[0005] According to another aspect of the description, the method comprises hot pressing foil strips formed from at least one of copper or aluminum.

[0006] According to a further aspect of the description, the method comprises heating the combined foil strip stack to a temperature between 350 Kelvin and 680 Kelvin and maintaining the temperature for a period of between 5 seconds and 30 minutes.

[0007] According to a further aspect of the description, the method comprises using an induction-heated press die in hot-pressing the combined foil strip stack.

[0008] According to a further aspect of the description, the method comprises using a resistance-heated press die in hot-pressing the combined foil strip stack.

[0009] According to a further aspect of the description, the method comprises forming at least one recess feature in the combined foil strip stack with the heated press dies during hot pressing of the combined foil strip stack.

[0010] According to a further aspect of the description, the method comprises forming at least one corrugated feature in the combined foil tab stack with the heated press dies during hot pressing of the combined foil strip stack.

[0011] According to a further aspect of the description, the method comprises forming at least one rib feature in the combined foil strip stack with the heated press dies during hot pressing of the combined foil strip stack.

[0012] According to a further aspect of the description, the method comprises using a high-frequency oscillating laser in laser welding the combined foil strip stack.

[0013] According to another aspect of the description, the method further comprises cooling at least a portion of a clamp or sub-clamp configured to hold the electrode stack during hot pressing of the combined foil strip stack.

[0014] According to a further aspect of the description, the method comprises using a Peltier plate when cooling at least the part of the clamp.

[0015] According to a further aspect of the description, the method comprises using cooling channels in the lower bracket when cooling at least the part of the bracket.

[0016] According to several aspects of the present description, a method for consolidating a foil strip stack is provided. The method includes combining foil strips of an electrode stack in a battery cell to form a combined foil strip stack. The method includes clamping the combined foil strip stack to hold the combined foil strip stack in position. The electrode stack is held by a clamp, and the combined foil strip stack is held by a sub-clamp. The method includes hot-pressing the combined foil strip stack with heated press dies to form a consolidated foil strip stack. Furthermore, the method includes laser welding the combined foil strip stack to a lead using a laser welder.

[0017] According to a further aspect of the description, the method comprises heating the combined foil strip stack to a temperature between 350 Kelvin and 680 Kelvin and maintaining the temperature for a period of between 5 seconds and 30 minutes while hot pressing the combined foil strip stack.

[0018] According to another aspect of the description, the method includes using a press die enclosing induction coils in a clamp that compresses the combined foil strip stack during hot pressing of the combined foil strip stack. The induction coils heat the combined foil strip stack.

[0019] According to another aspect of the description, the method further comprises cooling at least a portion of the clamp or sub-clamp configured to hold the electrode stack during hot pressing of the combined foil strip stack.

[0020] According to several aspects of the present description, a method for consolidating a foil strip stack is provided. The method includes combining foil strips of an electrode stack in a battery cell to form a combined foil strip stack. The foil strips are formed from copper or aluminum. The method includes clamping the combined foil strip stack to hold the foil strip stack in position. The electrode stack is held by a clamp, and the combined foil strip stack is held by a sub-clamp. The method includes hot-pressing the combined foil strip stack using heated press dies to form a consolidated foil strip stack.

[0021] The method comprises cooling at least a portion of the stack of consolidated foil strips using a cooling system, wherein the cooling system is integrated into the lower clamp. The method comprises laser welding the consolidated foil strip stack to a connecting lead using an oscillating high-frequency laser welding device.

[0022] According to another aspect of the description, the method comprises using a Peltier plate when cooling at least the part of the clamp.

[0023] According to a further aspect of the description, the method comprises heating the combined foil strip stack to a temperature between 350 Kelvin and 680 Kelvin and maintaining the temperature for a period of between 5 seconds and 30 minutes while hot pressing the combined foil strip stack.

[0024] According to a further aspect of the description, the method comprises using cooling channels in the lower bracket when cooling at least the part of the bracket.

[0025] Further areas of applicability of the present disclosure will become apparent from the detailed description below. It should be understood that the detailed description and specific examples are for purposes of illustration only and are not intended to limit the scope of the disclosure.

[0026] The above features and advantages, as well as other features and advantages of the presently disclosed system and method, are apparent from the detailed description, including the claims and examples, when considered in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The present disclosure will be more fully understood from the detailed description and the accompanying drawings, in which: Fig. 1 is a perspective view showing an example of a vehicle having a battery pack with a plurality of battery cells according to the present description. Fig. 2A is a perspective view showing a battery cell used in the Fig. 1, wherein the battery cell comprises at least one electrode stack having a plurality of electrode strips welded to a current collector, according to the present description. Fig. 2B is a partial cross-sectional view through the Fig. 2A, showing the layers in a single electrode stack and a set of anode electrode strips and a set of cathode electrode strips, according to the present description. Fig. 3 is a flowchart showing a method for laser welding the anode and cathode electrode strips to the current collectors by hot pressing, according to the present description. Fig. 4 is a perspective view showing an electrode stack and a combined foil strip stack according to Fig. 2A, wherein a clamp and a sub-clamp support the electrode stack and the combined foil strip stack, according to the present description. Fig. 5 is a perspective view showing an electrode stack and a Fig. 4, wherein a press die hot-presses the combined foil strip stack, according to the present description. Fig. 6 is a perspective view showing the electrode stack and a solidified foil strip stack resulting from the hot pressing of the Fig. 4 shown combined foil strip stack, according to the present description. Fig. 7 is an isometric perspective view showing the Fig. 4 and the solidified foil strip stack, according to the present description. Fig. 8 is a perspective view showing a combined foil strip stack and press dies for hot pressing the combined foil strip stack, according to the present description. Fig. 9 is a perspective view showing a solidified film strip stack after hot pressing of the Fig. 8 shows the combined foil strip stack according to the present description. Fig. 10 is a perspective view showing a combined foil strip stack and dies for hot pressing the combined foil strip stack, the dies being configured to create a feature in the resulting consolidated foil strip stack, in accordance with the present description. Fig. 11 is a perspective view showing a solidified film strip stack resulting from the hot pressing of the Fig. 10, wherein the features created in the consolidated film strip stack include depression features, according to the present description. Fig. 12 is a perspective view showing a solidified film strip stack resulting from the hot pressing of the Fig. 10, wherein the features created in the consolidated foil strip stack include a wave feature, according to the present description. Fig. 13 is a perspective view showing a solidified film strip stack resulting from the hot pressing of the Fig. 10, wherein the features created in the consolidated foil strip stack include rib features, according to the present description. Fig. 14 is a perspective view showing a combined foil strip stack supported by a clamp and a sub-clamp having a cutting feature for trimming one end of the combined foil strip stack, in accordance with the present description. Fig. 15 is a perspective view showing a consolidated foil strip stack produced according to the present description with the Fig. 14 shown cutting feature. Fig. 16 is a perspective view showing an electrode stack and a combined foil strip stack supported by a clamp and a sub-clamp, the clamp and sub-clamp having a cooling system with cooling channels fed by a coolant, according to the present description. Fig. 17 is a perspective view showing an electrode stack and a combined foil strip stack supported by a clamp and a sub-clamp, the clamp and sub-clamp incorporating a Peltier plate cooling system according to the present description. Fig. 18 is a perspective view showing a consolidated foil strip stack welded to a lead wire, the resulting weld being a butt weld, in accordance with the present description. Fig. 19 is a perspective view showing a consolidated foil strip stack welded to a lead wire, the resulting weld being a lap weld with the weld location spaced from one end of the consolidated foil strip stack, in accordance with the present description. Fig. 20 is a perspective view showing a consolidated foil strip stack welded to a lead wire, the resulting weld being a lap weld and the weld being at the end of the consolidated foil strip stack, in accordance with the present description Fig. 21 is a perspective view showing two consolidated foil strip stacks each supported by a clamp and a sub-clamp having Peltier plates, wherein one Peltier plate heats the first consolidated foil strip stack and a second Peltier plate cools the second consolidated foil strip stack during a welding operation, according to the present description. DETAILED DESCRIPTION

[0028] The following describes in detail several examples of the description, which are illustrated in the accompanying drawings. Wherever possible, the same or similar reference numbers are used throughout the drawings and the description to refer to the same or similar parts or steps. The following description is merely exemplary and is not intended to limit the present disclosure, application, or use.

[0029] In Fig. 1 is a perspective view of a vehicle 10 having a battery pack 12 according to the present description. The battery pack 12 is illustrated with an exemplary vehicle 10. The vehicle 10 is an electric vehicle or hybrid vehicle having wheels 11 driven by electric motors / inverters 13. The electric motors / inverters 13 are powered by the battery pack 12. While the vehicle 10 is illustrated as a passenger vehicle, it should be understood that the battery pack 12 may be used with various other types of vehicles. For example, the battery pack 12 may be used in watercraft, such as boats, or in aircraft, such as drones or passenger aircraft. Furthermore, the battery pack 12 may be used as a stationary power source separate and independent from a vehicle. The battery pack 12 includes a housing 14 for housing a plurality of battery cells 18.The battery pack 12 may have fifty or more battery cells 18.

[0030] In Fig. 2A is a perspective view of a battery cell 18 shown in the Fig. 1, according to one aspect of the present description. Each battery cell 18 has a housing or shell (not shown) and a plurality of electrode stacks 22. Each battery cell 18 may have hundreds of electrode stacks 22. Each electrode stack 22 is connected to a current collector 24, 26. Furthermore, the electrode stacks 22 are inserted into the housing, and the housing is filled with a suitable electrolyte. The electrolyte is, for example, a liquid solution of organic solvents and lithium salts. The current collectors 24, 26 are thin metal plates or foils arranged on either side of the electrode stacks 22 and typically have a thickness between 0.4 and 1 millimeter. The current collectors may be made of copper or aluminum, for example. The current collectors 24, 26 are attached to the electrode stacks 22 to transfer the electrical current to an external circuit.

[0031] With additional reference to Fig. 2B shows a partial cross-sectional view through the battery cell 18, as in Fig. 2A, the layers in a single electrode stack 22, according to the present description. Each electrode stack 22 includes a negative electrode or anode electrode 40 (a foil strip) extending from a first side of the electrode stack 22, a separator 42, and a positive electrode or cathode electrode 44 (a foil strip) extending from a second side of the electrode stack 22. The anode electrode 40 is generally a thin metal plate or foil that supports an anode electrode strip 46 (shown in Fig. 2A) to establish an electrical connection between the anode electrode and the current collector 24. Similarly, the cathode electrode 44 is a thin metal plate or foil that has a cathode electrode strip 48 (in Fig. 2A) to establish an electrical connection between the cathode electrode 44 and the current collector 26. A plurality of cathode electrode strips form a foil strip stack.

[0032] The anode electrode 40 and the anode electrode strip 46 are made, for example, of copper or another suitable material and are typically coated with graphite or graphite / silicon or other carbon-based materials, silicon oxide, or lithium-containing silicon. The cathode electrode 44 and the cathode electrode strip 48 are made, for example, of aluminum or another suitable material and are typically coated with a metal oxide, such as lithium cobalt oxide (LCO), nickel cobalt aluminum (NCA), lithium iron manganese phosphate (LFP / LFMP), or lithium manganese rich (LMR). The different metals (copper anode and aluminum cathode) of the battery cell 18 generate a galvanic reaction in the battery cell 18. The copper, e.g. of the anode electrode 40, and the aluminum, e.g. of the cathode electrode 44, have different standard reduction potentials and are separated from each other by the separator 42.The aluminum, with the lower potential, will oxidize and release electrons, while the copper, with the higher potential, will reduce and gain electrons. This process of electron release and absorption generates an electric current that can be used to power devices. Several anode electrodes form a foil strip stack.

[0033] The separator 42 is generally a thin, porous membrane or material layer arranged between the anode electrode 40 and the cathode electrode 44, preventing the anode electrode 40 and the cathode electrode 44 from contacting and causing a short circuit. The separator 42 allows the lithium ions to pass through and closes the circuit. A porous and chemically stable composite material can be used as the separator 42, e.g., a composite material made of polyethylene (PE), polypropylene (PP), or other natural materials. In addition, inorganic nanoparticles such as TiO2, SiO2, AlO 23and ZrO2 are used to create coating composites for separator 42. The separator 42 increases the internal resistance of the battery cell 18, which reduces the power output and efficiency of the battery. The internal resistance depends on the thickness, porosity, and composition of the separator 42. The separator 42 is also selected to withstand high temperatures and prevent uncontrolled temperature rise due to exothermic reactions. In addition, the separator 42 has a high melting point and a low shrinkage rate to avoid contact between the anode electrode 40 and the cathode electrode 44. The separator 42 has sufficient mechanical strength not to be punctured, torn, or deformed during cell manufacture and operation. The separator 42 is also dimensionally stable and flexible to conform to the shape of the electrodes and accommodate volume changes during cycling.The separator 42 is chemically inert and compatible with the electrolyte, electrodes, and other cell components. Furthermore, the separator 42 has a low affinity for water or other contaminants that could contaminate the electrolyte or cause corrosion to the electrodes.

[0034] With reference to Fig. 3, a method 100 for consolidating a foil stack of the electrode stack 22 within the battery cell 18 according to the present description is presented. The method begins at block 102. Block 102 shows the combining of the foil strips 46, 48 of the electrode stack 22 in the battery cell 18 to form a combined foil strip stack 52. Combining the foil strips 46, 48 may include pre-assembling the electrode stack 22 in an upstream stacking process. For example, the anode electrodes 40, the cathode electrodes 44, and the separators may be deposited in a magazine (not shown) in a stacking wheel (not shown) and each arranged to form the electrode stack 22. In this arrangement, the anode electrode strips 46 extend from a first side of the electrode stack 22 and form a combined foil strip stack 52 including the anode electrode strips 46.The cathode electrode strips 48 extend from another side of the first side of the electrode stack 22 or another portion of the first side of the electrode stack 22 (i.e., away from the anode electrode strips 46) and comprise a combined foil strip stack 52 with the cathode electrode strips 48. The combined foil strip stack 52 may include either anode electrode strips 46 or cathode electrode strips 48. In one example, the combined foil strip stack 52 comprises a stack of 50 electrode strips, although the number of electrode strips may vary (e.g., fewer than 25 electrode strips to more than 100 electrode strips). The method may then proceed to block 104.

[0035] Block 104 shows the clamping of the combined foil strip stack 52 with a clamp 54 or a sub-clamp 56. Clamping of the combined foil strip stack 52 may include the use of only one clamp 54 or both a clamp 54 and a sub-clamp 56. As used herein and in Fig. 4, the clamp 54 is used to hold and support the electrode stack 22, and the sub-clamp 56 is used to hold and support the combined foil strip stack 52 in preparation for hot pressing, although it should be understood that other configurations for the clamp 54 and the sub-clamp 56 may be used. The clamping may provide a bonding force for the additional combination of the combined foil strip stack 52. Homogeneous clamping of the combined foil strip stack 52 is advantageous due to the low inherent stiffness of the electrode strips in the combined foil strip stack 52 and the residual stresses created by rolling and winding processes during the manufacture and combination of the anode electrode strips 46 and the cathode electrode strips 48. When the sub-clamp 56 is used, the sub-clamp 56 may only contact a portion of the combined foil strip stack 52 (e.g.,a part not intended for hot pressing). In some cases, the clamping of the combined foil strip stack 52 may occur during a pre-assembly step and / or during an upstream stacking operation. Additionally, the clamp 54 and / or the sub-clamp 56 may be integrated into a press die 60. Further, the clamp 54 and / or the sub-clamp 56 may be heated, for example, by inductive heating (e.g., an inductively heated clamp and / or an inductively heated sub-clamp) and / or by resistance heating (e.g., a resistance-heated clamp and / or a resistance-heated sub-clamp). A press die 60 incorporating induction coils into a non-conductive tool may press the combined foil strip stack 52, and the induction coils heat the foils to create a diffusion bond. The method then proceeds to block 106.

[0036] Block 106 shows the hot pressing of the combined foil strip stack 52 with heated press dies 60 to form a consolidated foil strip stack 62. Hot pressing the combined foil strip stack 52 heats the combined foil strip stack 52 and presses the individual electrode strips together. Hot pressing evaporates surface contaminants and moisture on the individual electrode tabs while minimizing air voids within the consolidated foil strip stack 62. Hot pressing reduces porosity and delamination within the consolidated foil strip stack 62 in subsequent welding steps.

[0037] The Fig. 5, 8, 10, 14-16 and 21 show a set of heated press dies 60 which hot press the combined foil strip stack 52, resulting in the consolidated foil strip stack 62, such as the consolidated foil strip stack 60 shown in the Fig. 6 and Fig. 9. The pressing dies 60 may include resistance-heated pressing dies 60, inductively heated pressing dies 60, and the like. In one specific example, a combined foil strip stack 52 comprising 50 strips with an initial total thickness of 890 micrometers (µm) is hot-pressed prior to a hot-pressing step, resulting in a consolidated foil strip stack 62 with a resulting total thickness of approximately 812 µm. In this example, the thickness difference is due to the hot-pressing step and the removal of surface contaminants and air voids initially present between the foil strips 46, 48. In another example, hot-pressing the combined foil strip stack 52 may include heating the combined foil strip stack 52 to a temperature between 350 Kelvin (K) and 680 K and holding the temperature for a period of between ten seconds and thirty minutes.It should be understood that a variety of temperatures and holding times can be used for hot pressing. For example, the hot pressing temperature can range from 300 K or less to 900 K or more, as long as the melting temperature of the combined foil strip stack 52 is not reached. The hot pressing time can range from 5 seconds or less to 30 minutes or more.

[0038] With reference to the Fig. 10 to 13, hot pressing the combined foil strip stack 52 may include forming at least one feature in the combined foil strip stack 52. Fig. Figure 10 illustrates the hot pressing of the combined foil strip stack 52 with heated pressing dies having features configured to imprint and / or form the features.

[0039] In Fig. 11 shows a consolidated foil strip stack 62 in which a plurality of recesses 64 are formed. The recesses 64 may extend into and / or out of the resulting consolidated foil strip stack 62. The consolidated foil strip stack 62 may have one or more recesses 64. Fig. 12 shows a consolidated foil strip stack 62 with a corrugated feature 66 formed therein. The corrugated feature 66 may be formed on an outer surface and / or throughout the consolidated foil strip stack 62. The corrugated feature 66 may facilitate improved gas venting during a subsequent welding process step. Fig. 13 shows a consolidated foil strip stack 62 with a plurality of rib features 68 formed therein. The rib features 68 may extend into and / or out of the consolidated foil strip stack 62. The consolidated foil strip stack 62 may include one or more rib features 68. These features may serve to enhance the consolidation of the foil strips, particularly during transfer of the electrode stack 22 to subsequent processing locations.

[0040] Additionally, the hot pressing of the combined foil strip stack 52 may include trimming the combined foil strip stack 52 to enable a consistent clamp fit. As shown in Fig. 14, the heated press die 60 may include a cutting feature 70 that trims and removes a portion 72 of the combined foil strip stack 52 so that an end 74 of the resulting consolidated foil strip stack 62, as shown in Fig. 15, is uniform and has a uniform fit. The method 100 may then proceed to block 108.

[0041] Block 108 shows the cooling of at least a portion of the lower bracket 56 using a cooling system 76. For example, and with reference to Fig. 16, a lower clamp 56 having cooling channels 78 may be used for the hot pressing step illustrated in block 106. The cooling channels 78 are embedded and integral with the lower clamp 56 and conduct a coolant through at least a portion of the lower clamp 56. While the heated press dies 60 heat and press the combined foil strip stack 52, the lower clamp 56 cools a portion of the combined foil strip stack 52 and / or electrode stack 22 to prevent overheating of the combined foil strip stack 52.

[0042] In another example and with reference to Fig. 17, cooling at least a portion of the sub-clamp 56 may include using a sub-clamp 56 with a Peltier plate 80. A Peltier plate operates using the Peltier effect, which occurs when an electrical current flows through a junction of two dissimilar materials. This transfers heat from one side of the plate (e.g., a cool side 82) to another side of the plate (e.g., a hot side 84). Depending on the current direction, the Peltier plate can either absorb heat (become cooler) or release heat (become hotter). The Peltier plate 80 may be arranged integrally with the sub-clamp 56 or separate from the sub-clamp 56 and / or clamp 54. The Peltier plate 80 may be arranged so that the hot side abuts and is near the combined foil strip stack 52 and the cold side is away from and away from the combined foil strip stack 52. The method then proceeds to block 110.

[0043] Block 110 illustrates laser welding the consolidated foil strip stack 62 to a lead 86 (e.g., a current collector) using a laser welder 88. The laser welder 88 may be a high-frequency oscillating laser welder. Of course, the laser welder 88 may include a variety of suitable welding devices. In one example, laser welding the consolidated foil strip stack 62 may include using the laser welder 88 to high-beam oscillation weld the consolidated foil strip stack 62 to the lead 86 with a vertical figure-8 oscillation pattern following a hot-pressing step.

[0044] Furthermore, the consolidated foil strip stack 62 can be welded to the connecting line 86 in a variety of configurations. For example, as shown in Fig. 18, the consolidated foil strip stack 62 may be welded to the connecting lead 86 in a butt-joint configuration using the laser welding device 88, with a resulting weld seam 90 being disposed at one end 92 of the consolidated foil strip stack 62 and the connecting lead 86.

[0045] In the Fig. 19, the consolidated foil strip stack 62 is welded in an overlap configuration, with the resulting weld seam 90 being disposed on a portion of the consolidated foil strip stack 62 and the consolidated foil strip stack 62 overlapping a portion of the lead wire 86.

[0046] In the Fig. 20, the consolidated foil strip stack 62 is welded in an overlap configuration, with the resulting weld seam 90 being a fillet weld disposed on a portion of the consolidated foil strip stack 62, with the consolidated foil strip stack 62 overlapping a portion of the lead wire 86.

[0047] As in Fig.21, a heated die 60A may be used to heat a first consolidated foil strip stack 62A located on a first side 98A of the electrode stack 22. A cooled die 60B may be used to cool a second consolidated foil strip stack 62B located on a second side 98B of the electrode stack 22. This heating of the first consolidated foil tab stack 62A and the cooling of the second consolidated foil tab stack 62B may occur simultaneously (e.g., during the welding step shown in block 110) or at separate times.

[0048] The present description is advantageous and useful over prior art laser welding of electrode stack strips. For example, hot pressing the combined foil strip stack 52 serves to heat the foil strips 46, 48 and vaporize surface contaminants, often in the form of aluminum oxides, and eliminate air voids. During subsequent welding steps, gases form in the resulting welds due to the rapid solidification rate of aluminum alloys, leading to pore formation. These pores, together with the stresses caused by solidification shrinkage, lead to delamination of the foils at the melt interfaces. Hot pressing reduces porosity and delamination during subsequent welding.

[0049] This description is for illustrative purposes only and is in no way intended to limit the disclosure, its application, or uses. The broad teachings of the description may be embodied in a variety of forms. Although this description contains specific examples, the true scope of the disclosure should not be so limited, since other modifications will become apparent upon study of the drawings, the description, and the following claims.

Claims

[1] A method for consolidating a stack of film strips, comprising: Combining foil strips of an electrode stack in a battery cell to form a combined foil strip stack; hot-pressing the combined foil strip stack using heated press dies to form a consolidated foil strip stack; and Laser welding of the solidified foil strip stack onto a connecting cable using a laser welding device. [2] The method of claim 1, wherein the foil strips are formed from at least one of copper or aluminum. [3] The method of claim 1, wherein hot pressing the combined foil strip stack comprises heating the combined foil strip stack to a temperature between 350 Kelvin and 680 Kelvin and holding the temperature for between 5 seconds and 30 minutes. [4] The method of claim 1, wherein hot pressing the combined foil strip stack comprises using an inductively heated press die. [5] The method of claim 1, wherein hot pressing the combined foil strip stack comprises using a resistance heated press die. [6] The method of claim 1, wherein hot pressing the combined foil strip stack comprises forming at least one depression feature in the combined foil strip stack with the heated pressing dies. [7] The method of claim 1, wherein hot pressing the combined foil strip stack comprises forming at least one corrugated feature in the combined foil strip stack with the heated pressing dies. [8] The method of claim 1, wherein hot pressing the combined foil strip stack comprises forming at least one rib feature in the combined foil strip stack with the heated press dies. [9] The method of claim 1, wherein laser welding the combined foil strip stack comprises using a high frequency oscillating laser. [10] The method of claim 1, further comprising: Cooling at least a portion of a clamp or sub-clamp configured to hold the electrode stack during hot pressing of the combined foil strip stack.

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