PRISMATIC STEEL CAN CONSTRUCTION FOR IMPROVED THERMAL EFFICIENCY

Abstract

A battery comprises a prismatic cell can formed from steel. The prismatic cell can includes a first end, a second end spaced apart from the first end, a top face, a bottom face, a first side face, and a second side face, defining a hollow can cavity. An anode current collector includes an anode foil tab. A cathode current collector includes a cathode foil tab. An anode connection lead is attached to the anode foil tab. A cathode connection lead is attached to the cathode foil tab. The anode current collector and the cathode current collector form an electrode stack arranged within the hollow can cavity, with the anode connection lead being connected to the bottom face of the prismatic cell can and forming a direct heat path through the electrode stack to the bottom face.

Description

INTRODUCTION

[0001] The information contained in this section serves to present the general context of the disclosure. Works of the inventors mentioned herein, insofar as they are described in this introduction, as well as aspects of the description that may not otherwise be considered prior art at the time of filing, are neither expressly nor implicitly admitted as prior art against this disclosure.

[0002] The present disclosure relates to battery arrangements and in particular to a battery arrangement comprising a prismatic can-shaped housing made of steel.

[0003] Electric vehicles (EVs), such as battery electric vehicles (BEVs), hybrid vehicles, and / or fuel cell vehicles, comprise one or more electric motors and a battery system with one or more battery cells, modules, and / or battery packs. A power control system is used to manage the charging and / or discharging of the battery system during charging and / or driving.

[0004] Battery cells comprise cathode electrodes, anode electrodes, and separators arranged in a battery cell stack housed within a battery cell casing (or cell can). The cathode electrodes comprise a layer of active cathode material arranged on a cathode current collector. The anode electrodes comprise a layer of active anode material arranged on an anode current collector. The cathode and anode electrodes are connected by cathode and anode terminals located on an outer surface of the casing.

[0005] Batteries or battery packs typically include a cell housing that holds and surrounds the battery cells. The terminals of the battery cells are connected to the corresponding terminals of the cell housing. The batteries are then arranged in a casing and connected to each other to provide a desired output voltage. Generally, the batteries rest on a heat sink that absorbs and dissipates heat from the battery cells. SUMMARY

[0006] A battery according to the present disclosure comprises a prismatic cell can made of steel. The prismatic cell can comprises a first end, a second end spaced apart from the first end, an upper surface, a lower surface, a first side surface, and a second side surface. The upper surface, the lower surface, the first side surface, and the second side surface define a hollow can cavity. An anode current collector is arranged in the hollow can cavity. The anode current collector comprises an upper surface section, a lower surface section, and an anode foil tab projecting outward from either the upper surface section or the lower surface section. A cathode current collector is arranged in the hollow can cavity.The cathode current collector comprises an upper surface section, a lower surface section, and a cathode foil tab projecting outwards from either the upper or lower surface section. An anode connection leads extend across either the upper or lower surface section of the anode current collector and is attached to the anode foil tab. A cathode connection leads extend across either the upper or lower surface section of the cathode current collector and are attached to the cathode foil tab. The anode current collector and the cathode current collector form an electrode stack arranged within the hollow can cavity, with the anode connection leads being connected to the lower surface of the prismatic cell can and forming a direct heat path through the electrode stack to the lower surface.

[0007] In other features, a first cap plate is mounted at the first end of the prismatic cell box and a second cap plate is mounted at the second end of the prismatic cell box.

[0008] In other respects, the anode connection is electrically attached to the first cap plate and the cathode connection is electrically attached to the second cap plate.

[0009] Other features include a ventilation opening in the first cap plate or in the second cap plate.

[0010] In other features, a first rib is formed on the first cap plate and a second rib is formed on the second cap plate, with the first rib engaging with the electrode stack at the first end of the prismatic cell box and the second rib engaging with the electrode stack at the second end of the prismatic cell box.

[0011] In other respects, the electrode stack comprises a variety of anode current collectors and a variety of anode foil tabs, and a variety of cathode current collectors and a variety of cathode foil tabs.

[0012] In other respects, the anode current collector includes a variety of anode foil tabs, and the cathode current collector includes a variety of cathode foil tabs.

[0013] A method for forming a battery comprises forming a prismatic cell can made of steel, comprising a first end, a second end spaced apart from the first end, a top face, a bottom face, a first side face, and a second side face, wherein the top face, the bottom face, the first side face, and the second side face define a hollow can cavity; forming an electrode stack comprising an anode current collector having a top surface section and a bottom surface section, and a cathode current collector having a top surface section and a bottom surface section; folding an anode foil flap over the top surface section or the bottom surface section; folding a cathode foil flap over the top surface section or the bottom surface section; and connecting an anode connection lead to the anode foil flap.wherein the anode connection leads extend over the upper surface section or the lower surface section, connecting a cathode connection leads to the cathode foil tab, wherein the cathode connection leads extend over one of the upper surface sections and the lower surface section, inserting the electrode stack into the hollow can cavity, wherein the anode connection leads are in electrical contact with the lower surface, and connecting the anode connection leads to the lower surface, thereby creating a direct heat path through the electrode stack to the lower surface.

[0014] Other features include connecting a first cap plate to the anode connection line and connecting a second cap plate to the cathode connection line.

[0015] In other features, the first cap plate is attached to the first end of the prismatic cell box and the second cap plate is attached to the second end of the prismatic cell box.

[0016] In other features, a gap is maintained between the upper surface of the prismatic cell box and the upper surface section of the anode current collector and the upper surface section of the cathode current collector.

[0017] For other features, the electrode stack is carried on an insertion holder.

[0018] For other features, inserting the electrode stack into the hollow can cavity involves sliding the insertion holder along the upper surface of the prismatic cell can with the anode connection lead.

[0019] For other features, connecting the anode lead to the lower surface of the prismatic can cell involves removing an air gap between the lower surface and the anode lead, with the electrode stack being supported on the insertion holder.

[0020] For other features, the insertion holder is removed from the prismatic cell box after connecting the anode terminal to the lower surface.

[0021] For other features, carrying the electrode stack on the insertion holder includes resting the electrode stack on a tray of a selected thickness.

[0022] For other features, carrying the electrode stack on the insertion holder includes fitting a first U-shaped end cap to a first end of the electrode stack and fitting a second U-shaped end cap to a second end of the electrode stack.

[0023] For other features, inserting the electrode stack into the hollow can cavity involves forming a prismatic cell can around the electrode stack to form the prismatic cell can.

[0024] For other features, forming the prismatic cell box around the electrode stack may involve welding the anode connection lead to a surface of a prismatic cell box.

[0025] For other features, the formation of the prismatic cell box around the electrode stack may involve folding a first side of the prismatic cell box to form the first side surface and a first section of the top surface, and folding a second side of the prismatic cell box to form the second side surface and a second section of the top surface.

[0026] Further applications of the present disclosure will become apparent from the detailed description, the claims, and the drawings. The detailed description and the specific examples serve only for illustration and are not intended to limit the scope of the disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The present disclosure will be better understood with the help of the detailed description and the accompanying drawings, whereby: Fig. 1 a front elevation view of a plurality of batteries, each comprising a prismatic cell box formed according to the present disclosure and resting on a cooling plate; Fig. 2 a perspective view of one of the many batteries of Fig. 1 represents a non-restrictive example; Fig. 3 a perspective view of a prismatic cell box formed from steel according to a non-restrictive example; Fig. 4 a perspective view of an anode electrode with a notched anode foil tab and a cathode electrode with a notched cathode foil tab according to a non-restrictive example; Fig. 5 a perspective view of an anode electrode with a notched anode foil tab and a cathode electrode with a notched cathode foil tab according to another aspect of the non-restrictive example; Fig. 6 a perspective view of an anode electrode with a notched anode foil tab and a cathode electrode with a notched cathode foil tab according to a further non-restrictive example; Fig. 7 represents an electrode stack comprising anode foil flaps folded over an upper surface of the anode electrode and the cathode electrode, and the cathode foil flap folded under a lower surface of the anode electrode and the cathode electrode, according to a non-restrictive example; Fig. 8 represents an anode connection lead connected to the anode foil tab and a cathode connection lead connected to the cathode foil tab, according to a non-restrictive example; Fig. 9 represents an anode connection line and a cathode connection line according to another non-restrictive example; Fig. 10 represents an anode connection line and a cathode connection line according to another non-restrictive example; Fig. 11 the electrode stack of Fig. 8, which is mounted on an insertion bracket, according to a non-restrictive example; Fig. 12. Inserting the electrode stack of Fig. 11 into the prismatic cell dose of Fig. 3 represents a non-restrictive example; Fig. 13 represents the welding of the anode connection lead to an upper surface of the prismatic cell box according to a non-restrictive example; Fig. 14A represents connecting a first end cap to the anode connection lead and connecting a second end cap to the cathode connection lead after the cell stack has been placed into the prismatic cell box of Fig. 3 represents a non-restrictive example; Fig. 14B represents the connection of the first end cap and the second end cap to the prismatic cell box according to a non-restrictive example; Fig. 15 U-shaped end caps are located at opposite ends of the electrode stack. Fig. 8 are mounted according to a non-restrictive example; Fig. 16 the insertion of the electrode stack of Fig. 15 into the prismatic cell dose of Fig. 3 represents a non-restrictive example; Fig. 17 the welding of the anode connection lead of the electrode cell stack of Fig. 16 represents an upper surface of the prismatic cell box according to a non-restrictive example; Fig. 18A represents the welding of a cell stack to an inner surface of a prismatic cell box according to a non-restrictive example; Fig. 18B Folding the prismatic cell box around the cell stack of Fig. 18A represents a non-restrictive example; and Fig. 18C the sealing of the prismatic cell box around the cell stack of Fig. 18B is illustrated by a non-restrictive example.

[0028] Reference symbols can be reused in the drawings to identify similar and / or identical elements. DETAILED DESCRIPTION

[0029] Prismatic can batteries comprise a cell can with a top, bottom, and side faces. An electrode stack is arranged within the prismatic cell. The electrode stack can be immersed in an electrolyte. The electrode stack includes foil tabs that connect to terminals on the prismatic cell can.

[0030] The prismatic batteries are arranged in a housing and interconnected to generate a desired output voltage. The batteries are subjected to a number of charge and discharge cycles. For example, if the battery is part of an electric vehicle's battery pack, a discharge cycle occurs when the vehicle is powered or in motion. The type of discharge cycle varies depending on the driving conditions. The charging cycle typically takes place when the vehicle is at rest. However, charging can also occur during braking.

[0031] During charging and discharging cycles, heat is generated in the electrode stack. For this reason, the cell can is typically mounted on a cooling plate within the housing. The cooling plate draws heat away from the electrode stack through the walls of the prismatic can. Since there is no direct contact between the electrode stack and the bottom surface of the prismatic can, heat conduction usually occurs through the side surfaces. Accordingly, the prismatic can is typically made of a material with high thermal conductivity, such as aluminum. In this design, heat flows more easily through the side walls to the bottom surface.

[0032] A battery arrangement according to the present disclosure is generally characterized by 10 in Fig. 1. The battery assembly 10 comprises a plurality of batteries 12 mounted on a cooling plate 14. The heat generated in each of the plurality of batteries 12 is transferred to the cooling plate 14 via a thermal conduction system, as described in more detail herein. The plurality of batteries 12 comprises a first battery 16, a second battery 18, and a third battery 20. The number and arrangement of the plurality of batteries 12 in the battery assembly 10 can vary.

[0033] With the following reference to Fig. 2 and Fig. Figure 3, in which the first battery 16 is described, with the understanding that the second battery 18 and the third battery 20 are similarly constructed. The battery 16 comprises a prismatic cell box 30, which, according to the present disclosure, is made of steel. The prismatic cell box 30 comprises a first end 34, a second end 36, and an intermediate section 38. The intermediate section 38 extends between the first end 34 and the second end 36. The prismatic cell box 30 also comprises a top surface 40, a bottom surface 42, a first side surface 44, and a second side surface 46. The top surface 40, the bottom surface 42, the first side surface 44, and the second side surface 46 together define a cavity 50 that accommodates the electrode stack.

[0034] An electrode stack 56, arranged in the hollow can cavity 50, is shown in Fig. 4. The electrode stack 56 comprises an anode current collector 58 and a cathode current collector 60. The number of each anode current collector 58 and cathode current collector 60 for each battery 16 can vary and may depend on the desired performance characteristics for the battery arrangement 10. That is, the anode current collector 58 and the cathode current collector 60 are provided in pairs. The number of pairs can vary between a single pair (i.e., a single anode current collector and a single electrode current collector separated by a separator) and multiple pairs, depending on the battery performance requirements. The anode current collector 58 comprises an upper surface section 62 and a lower surface section 64. The lower surface section 64 is notched to form an anode foil tab 66. The cathode current collector 60 comprises an upper surface section 68 and a lower surface section 70.The upper surface section 68 is notched to form a cathode foil tab 72.

[0035] At this point, it is understood that the number and size of each anode foil tab 66 and each cathode foil tab 72 can vary. For example, the anode current collector 58 and the cathode current collector 60 can each be notched to form twelve foil tabs, as shown in Fig. 5. The anode current collector 58 and the cathode current collector 60 can also be notched to enclose two foil tabs, as shown in Fig. 6. The number and arrangement of the foil tabs can depend on the number of current collectors that make up the battery stack 56. Since the foil tabs are arranged as in Fig. As shown in Figure 7, the foil tabs can be folded to form an anode connection surface 78 and a cathode connection surface 80. Battery stacks with a large number of current collectors can include more foil tabs than those with fewer current collectors. The anode connection surface 78 and the cathode connection surface 80 extend between a first end section 82 and a second end section 84 of the battery stack 56.

[0036] With reference to Fig. An anode connection 90 is connected to the anode terminal 78, and a cathode connection 92 is connected to the cathode terminal 80. The anode connection includes a first terminal 94, and the cathode connection 92 includes a second terminal 96. The anode connection 90 is made of copper, and the cathode connection 92 is made of aluminum. The specific shape of the anode connection 90 and the cathode connection 92 may vary. For example, as in Fig. As shown in Figure 9, the anode connection line 90 comprises a first continuous surface 102, which serves as an interface to the anode connection surface 78. The cathode connection line 92 comprises a second continuous surface 104, which serves as an interface to the cathode connection surface 80.

[0037] In other examples, such as in Fig. As shown in Figure 10, the anode connection line 90 can include a first slot 106, and the cathode connection line 92 can include a second slot 108. Anode foil tabs 66 can pass through the first slot 102 and be folded before being connected to the anode connection line 90. Similarly, cathode foil tabs 68 can pass through the second slot 108 and be folded before being connected to the cathode connection line 92. The first slot 106 and the second slot 108 can, as shown, have open ends, or they can terminate in the respective anode connection lines 90 and cathode connection lines 92.

[0038] After attaching the anode connection lead 90 and the cathode connection lead 92, the electrode stack 56 is positioned on an insertion holder 113, as shown in Fig. 11. The insertion holder 113 can take the form of a shell 116 that guides the electrode stack 56 into the electrode stack receiving cavity 50, so that the anode connection lead 90 does not contact the surfaces of the prismatic cell box 30 during insertion. The shell 1 is formed with a selected thickness. The thickness is chosen to ensure that, when the electrode stack 56 is inserted into the electrode stack receiving cavity 50, the anode connection lead 90 contacts the lower surface 42 of the prismatic cell box 30. As shown in Fig. As shown in Figure 12, the electrode stack 56 is guided into the electrode stack receiving zone 50, which is supported on the shell 116. The shell 116 comprises a first end section 118 and a second end section 120.

[0039] The electrode stack 56 is inserted into the electrode stack receiving zone 50 such that the first end section 118 of the shell 116 projects outwards from the first end 34 and the second end section 120 projects outwards from the second end 36. Once in place, the first end section 118 and the second end section 120 are held in position, for example by clamping (not shown), while pressure is applied to the lower surface 42. The pressure on the lower surface 42 eliminates or reduces air gaps to promote a tighter connection with the anode lead 90. Once the air gaps are eliminated, the anode lead 90 is connected to the lower surface 42 by a weld 124, as shown in Fig. 13. At this point, it is understood that other joining techniques, such as the use of thermally conductive adhesive, can also be employed. In a non-restrictive example, weld 124 is formed by a laser welding process designed for joining copper and steel. After welding the anode connection 90 to the lower surface 42, the prismatic cell box 30 can be inverted and the shell 116 removed, leaving a gap 128 between the cathode connection 92 and the upper surface 40 of the prismatic cell box 30.

[0040] A first cap plate 132 is connected to the first terminal 94 of the anode connection line 90, and a second cap plate 134 is connected to the second terminal 96 of the cathode connection line 92, as shown in Fig. Figure 14A shows the first cap plate 132 being connected to the first terminal end 94 by brazing, soldering, welding, or the like. Similarly, the second cap plate 134 can be connected to the second terminal end 96 by brazing, soldering, welding, or the like. The first cap plate 132 comprises a first inner surface 137 and a first outer surface 139. The second cap plate 137 comprises a second inner surface 141 and a second outer surface 143.

[0041] The first inner surface 137 carries a first rib 146 and the second inner surface 141 carries a second rib 148. When the first cap plate 132 and the second cap plate 134 are installed, as in Fig. As shown in Figure 14B, the first rib 146 contacts the first end section 82 of the electrode stack 56, and the second rib 148 contacts the second end section 84 of the electrode stack 56. In this way, the electrode stack 56 is held firmly in position within the electrode stack receiving zone 50. The first cap plate 132 includes a first terminal connected to the anode terminal 90, and the second cap plate 134 includes a second terminal 152 connected to the cathode terminal 92. The first terminal 150 and the second terminal 152 provide external connection points for the battery 16. In addition to supporting the first terminal 150, the first cap plate 132 has a vent 154 that opens selectively to connect the electrode stack receiving zone 50 to the environment when the module's internal pressure exceeds a selected pressure threshold.

[0042] With the following reference to Fig. 15 and Fig. In Figure 16, an insertion holder 166 is described according to another non-restrictive example. The insertion holder 166 comprises a first U-shaped end cap 170 that fits over the first end section 82 of the electrode stack 56, and a second U-shaped cap 172 that fits over the second end section 84 of the electrode stack 56. The first U-shaped end cap 170 has a first projection element 174, and the second U-shaped end cap 172 comprises a second projection element 176. The first U-shaped end cap 170 and the second U-shaped end cap 172 determine the selected position of the electrode stack 56 in the electrode stack receiving zone 50 when it is inserted into the prismatic cell box 30, as shown in Figure 16. Fig. 16. The first U-shaped end cap 170 and the second U-shaped end cap 172 are held in position, for example, by applying clamping pressure to the first and second projecting elements 174 and 176, respectively. At this point, pressure is exerted on the prismatic cell box 30, causing the lower surface 42 to eliminate or reduce any existing air gaps to promote a tight connection with the anode connection lead 90. Once in position, a weld 178 is used to connect the anode connection lead 90 to the lower surface 42, as shown in Fig. 17. As already discussed, other joining techniques, such as the use of thermally conductive adhesive, can also be employed. At this point, the first and second end caps 132 and 134 can be installed as discussed here.

[0043] With the following reference to Fig. 18A, Fig. 18B and Fig. In 18C, a prismatic cell dose 188 is described. A cell dose shape 190, which is described as an essentially planar element in Fig. As shown in Figure 18A, the structure comprises an upper surface 40, a lower surface 42, a first side surface 44, and a second side surface 46. The upper surface 40 comprises a first upper surface section 194, which is part of the first side surface 44, and a second upper surface section 196, which is part of the second side surface 46. The lower surface 42 is defined between a first fold line 200 and a second fold line 202. The first side surface 44 is defined between the first fold line 200 and a third fold line 204, and the second side surface 46 is defined between the second fold line 202 and a fourth fold line 206.

[0044] The anode connection element 90 is welded to the lower surface 42. After the electrode stack 56 is attached, the cell can shape 190 is folded. In particular, the first side surface 44 is folded around the first fold line 200 and the second side surface 46 is folded around the second fold line 202, as shown in Fig. Figure 18B shows the first upper surface section 194 being folded around the third fold line 204 and the second upper surface section 196 being folded around the fourth fold line 206. At this point, the first upper surface section 194 is joined to the second upper surface section 196, as shown in Fig. Figure 18C illustrates that the first upper surface section 194 and the second upper surface section 196 can be joined by various metal joining techniques, including welding, flanging, and the like. At this point, the first and second cap plates 132 and 134 can be installed in a similar manner to that discussed herein.

[0045] Attaching the anode terminal directly to the bottom surface of the prismatic cell can greatly improves heat dissipation. Heat flows directly from the electrode stack to the bottom surface. This configuration opens up additional materials, including steel, for manufacturing the prismatic cell can. By eliminating gaps between the anode terminal and the bottom surface of the prismatic cell can, and creating a direct heat transfer path, materials with lower thermal conductivity than aluminum are now available. Steel provides a desirable option due to its higher melting point, strength, and stiffness. The higher melting point means the prismatic can is less likely to fail under thermal runaway.

[0046] The above description is for illustrative purposes only and is not intended to limit the disclosure, its application, or its use in any way. The comprehensive teachings of the disclosure can be implemented in a wide variety of ways. Although this disclosure includes certain examples, the true scope of the disclosure should therefore not be limited to them, since other modifications will become apparent upon study of the drawings, the patent specification, and the following claims. It is understood that one or more steps within a process may be carried out in a different order (or simultaneously) without altering the principles of the present disclosure.Even though the configurations described above are each characterized by specific features, each or more of these features described in relation to one configuration of the disclosure can be implemented with features of any of the other configurations and / or combined with them, even if this combination is not expressly described. In other words, the described configurations are not mutually exclusive, and the interchangeability of one or more configurations remains within the scope of this disclosure.

[0047] Spatial and functional relationships between elements (e.g., between modules, circuit elements, semiconductor layers, etc.) are described using various terms, including "connected," "interlocking," "coupled," "adjacent," "next to," "on top of," "above," "below," and "arranged." Unless a relationship between first and second elements is explicitly described as "direct" in the above disclosure, this relationship may be a direct relationship, in which no other intervening elements exist between the first and second elements, or an indirect relationship, in which one or more intervening elements (either spatial or functional) exist between the first and second elements.As used herein, the expression “A, B and / or C” should be interpreted using a non-exclusive logical OR operation as logical (A OR-connected with B OR-connected with C) and not as “at least one of A, at least one of B and at least one of C”.

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