Battery cell with tab anchor

Abstract

The invention provides a battery cell with a tab anchor. The invention relates to a soft package type battery cell which comprises a metal connecting sheet extending to the outer part of a sealing envelope. To increase seal durability around these tabs, polymer anchors are formed through anchor holes in the tabs during the manufacturing process of the tab assembly. Fabricating such tabs may include: placing a polymeric tab film on each side of a conductive tab, the conductive tab having at least one anchoring hole; and heating the conductive tab and the polymer tab films, thereby causing the polymer tab films to bond to each other through the at least one anchoring hole to form the at least one anchor.

Description

Technical Field

[0001] The present disclosure relates to a battery, such as a battery for an electrified vehicle. More particularly, the present disclosure relates to a pouch-type battery cell having a tab assembly with a membrane layer mechanically anchored to a tab through a hole in the tab. Background Art

[0002] Instead of or in addition to internal combustion engines, electric vehicles use electricity stored in batteries for propulsion. Some electric vehicles utilize batteries with pouch-type battery cells, in which the electrode assembly is enclosed between lower and upper membranes. These two membranes are thermally bonded to form a seal. The maximum allowable internal pressure is limited by the seal's weakest area, which is often the area surrounding the tab. Summary of the Invention

[0003] A pouch battery cell includes an electrode stack, positive and negative electrode tabs, upper and lower pouch films, and a polymer. The electrode stack has an anode, a cathode, and a separator. The positive electrode tab is electrically connected to the cathode, while the negative electrode tab is electrically connected to the anode. These connections can be made, for example, by welding. The positive electrode tab defines at least one first anchoring hole, while the negative electrode tab defines at least one second anchoring hole. The positive electrode tab can be made of aluminum. The negative electrode tab can be made of copper. The upper and lower pouch films are on opposite sides of the electrode stack. The positive and negative electrode tabs protrude beyond the edges of the pouch films. The upper and lower films can also be adhered to each other to form a sealed envelope surrounding the electrode stack and containing the electrolyte. The polymer is adhered to the inner surfaces of the upper and lower pouch films. The polymer has anchors extending through the at least one first anchoring hole and the at least one second anchoring hole. The polymer can be a thermoplastic polymer, such as polypropylene.

[0004] A tab assembly for a battery cell includes a conductive tab and a polymer. The conductive tab defines at least one anchor hole extending from a first surface to a second surface. The tab can be made of aluminum or copper. The polymer is adhered to the first and second surfaces and includes at least one anchor extending through the at least one anchor hole. The polymer can be a thermoplastic polymer such as polypropylene. The tab protrudes from the polymer in two directions.

[0005] A process for manufacturing a tab assembly for a pouch battery cell includes placing a polymer tab film on each side of a conductive tab and applying heat. The tab has at least one anchor hole. At least one of the polymer tab films may have at least one protrusion extending into the at least one anchor hole. Heating causes the polymer films to bond to each other through the at least one anchor hole to form at least one anchor. Heating may also cause the polymer films to bond to the tab and to each other around both edges of the tab. Pressure may also be applied. A process for manufacturing a pouch battery cell includes: manufacturing two tab assemblies as indicated; welding them to the anode and cathode of an electrode stack, respectively; and sealing the electrode stack between the upper and lower pouch films. The tabs extend beyond the edges of the pouch films. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 This is a block diagram of a battery for an electric vehicle.

[0007] Figure 2 is a top view of a tab blank at one stage in the tab assembly manufacturing process.

[0008] Figure 3 is a diagram of a stage in the manufacturing process of a splice assembly.

[0009] Figure 4 This is a top view of the completed splice assembly.

[0010] Figure 5 It passes through Figure 4 Cross-sectional view of the completed tab assembly.

[0011] Figure 6 A top view of the electrode stack assembly during the manufacturing stage of a soft-pack battery cell.

[0012] Figure 7 is a cross-sectional view of the membrane.

[0013] Figure 8 It is a top view of a soft-pack battery cell.

[0014] Figure 9 yes Figure 8 Flowchart of the manufacturing process of soft-pack battery cells. DETAILED DESCRIPTION

[0015] Embodiments are described herein. However, it should be understood that the disclosed embodiments are merely examples and that other embodiments may take various and alternative forms. The drawings are not necessarily drawn to scale. Some features may be exaggerated or minimized to illustrate details of particular components. Therefore, the specific structural and functional details disclosed herein should not be construed as limiting, but merely as a representative basis for teaching those skilled in the art.

[0016] The various features shown and described with reference to any one of the accompanying drawings may be combined with features shown in one or more other drawings to produce embodiments not explicitly shown or described. The combinations of features shown provide representative embodiments for typical applications. However, for specific applications or implementations, various combinations and modifications of features may be desired consistent with the teachings of this disclosure.

[0017] A pouch cell (also known as a soft pack battery) is a type of lithium-ion battery characterized by its flexible packaging. Unlike more rigid cylindrical and prismatic cell formats, pouch cells wrap the battery materials in, for example, a flexible laminated aluminum foil or similar material. In some cases, this packaging approach can offer benefits including higher energy density, flexibility in size and shape, and reduced weight.

[0018] The construction of certain pouch battery cells involves several components and materials organized in a layered structure. The two main electrodes in a pouch cell are the cathode (positive electrode) and the anode (negative electrode). These electrodes are made of different materials that allow lithium ions to move in and out during charging and discharging. Common materials include lithium cobalt oxide (LiCoO2) or lithium iron phosphate (LiFePO4) for the cathode and graphite for the anode. There is a porous separator between the cathode and the anode that allows lithium ions to pass through while electrically isolating the electrodes from each other to prevent short circuits. The separator is typically made of polyethylene film or polypropylene film. The electrolyte can be a lithium salt solution in an organic solvent that facilitates the movement of lithium ions between the cathode and the anode during battery operation. The electrolyte fills the space within the cell, saturating the electrodes and separator.

[0019] A characteristic feature of pouch cells is their packaging, which in some arrangements uses a flexible multilayer laminate consisting of aluminum foil sandwiched between polymer layers. The packaging is heat-sealed to form a lightweight, leak-proof enclosure for the cell components. The flexible nature of the packaging allows for space utilization and can accommodate cell expansion during charge and discharge cycles. Electrical tabs are attached to the electrodes to provide external electrical connections. These tabs are welded to the cathode and anode current collectors and extend outside the pouch to connect to the battery management system and other cells.

[0020] refer to Figure 1, a battery 10 (such as a traction battery for an electrified vehicle) provides an electrical potential (voltage) between a positive terminal 12 and a negative terminal 14. The battery includes a stack of battery cells 16. The illustrated embodiment includes six cells, but the number can vary. Each cell includes an anode, a cathode, and a separator. Each cell also has a positive tab electrically connected to the cathode and a negative tab electrically connected to the anode. In the illustrated embodiment, the cells are connected in parallel. In other words, the positive tab is electrically connected to the positive terminal 12 and the negative tab is electrically connected to the negative terminal 14 of the battery so that the voltage of the battery is equal to the voltage provided by each cell. In other embodiments, some cells can be connected in series with each other so that the voltage of the battery exceeds the voltage of individual cells. An insulator or heat sink 18 can be inserted between adjacent cells. A pressure plate 20 on each end of the cell stack is arranged to compress the cells together.

[0021] Figures 2 to 5 The manufacturing process of the tab assembly for the soft pack battery cell is shown. Figure 2 The tab 22 is shown at one stage of the manufacturing process. The tab 22 is made of a conductive material such as aluminum or copper. The tab includes a set of anchor holes 24. In the embodiment shown, there are three oval anchor holes, but the number, shape, size and arrangement of the anchor holes can vary. Figure 3 FIG2 is a cross-section illustrating one stage of the tab assembly manufacturing process. Tab films 26 are placed on the surface of tab 22. The tab films are made of a thermoplastic polymer such as polypropylene (PP). Each tab film 26 has a protrusion 27 extending into an anchor hole 24. Pressure and heat are applied, causing the tab films 26 to bond to each other and to tab 22. The protrusions also bond to each other through the anchor holes, forming anchors 28. These anchors help hold the tab films securely in place relative to tab 22. Figure 4 There is shown a completed tab assembly 30. The tab film 30 covers the area of ​​the tab 22 including the anchor holes, but the tab extends beyond the tab film in both directions. Figure 5 is a cross-sectional view of the completed tab assembly 30 showing how the anchors 28 mechanically connect the two tab films 26 to each other.

[0022] Figures 6 to 8 The manufacturing process of the soft pack battery cell using the tab assembly as described above is shown. Figure 6At the stage shown, two tab assemblies 30A and 30B have been welded to an electrode stack 32. The electrode stack includes an anode 34, a cathode 36, and a separator. The positive tab assembly 30A is welded to the cathode 36. The tabs of the tab assembly 30A can be aluminum. The negative tab assembly 30B is welded to the anode 34. The tabs of the tab assembly 30B can be copper. The electrode stack is enclosed between two soft film films 38, which may be referred to herein as a lower film 38A and an upper film 38B, but the orientation is not important. Figure 7 is a cross-section of the soft envelope. The soft envelope 38 includes a foil layer 40, which may be, for example, aluminum. The inner surface is coated with a thermoplastic polymer layer, such as polypropylene (PP and / or PPa). The outer surface is coated with an insulating layer, which may be, for example, polyethylene terephthalate (PET), nylon, or other materials. Figure 8 The completed pouch-type battery cell 16 is shown. A seal 48 is formed around the perimeter of the lower and upper films by applying heat, which causes the polymer inner layers to bond to each other. Near the terminals, the polymer inner layer bonds to the tab film 26. The seal can be formed in sections. Section 48A surrounding the tab can be formed first. Then, section 48B can be formed. Finally, section 48C can be formed after the pouch is filled with electrolyte.

[0023] Figure 9 is a flow chart of a manufacturing process 50. Some steps may be performed in a different order than indicated. At 52, manufacturing Figure 2 The number, shape, size and arrangement of the anchor holes can vary, as long as they provide sufficient anchoring area and the remaining metal is sufficient to conduct current without excessive resistance. At 54, the tab film is positioned relative to the tab stock with the protrusions extending into the anchor holes. At 56, as shown Figure 3 Heat and pressure are applied as shown. The tab films bond to each other and to the tab stock, and when the protrusions bond to each other, an anchor is formed. At 58, as shown Figure 4 and Figure 5 The tab assembly shown is welded to the Figure 6The anode and cathode of the electrode stack are shown. At 60, the electrode stack, with the tabs welded in place, is positioned between two soft envelope films. The tabs protrude beyond the edges of the soft envelope films. In an alternative embodiment, a single sheet of film material can be folded to form upper and lower soft envelope films. At 62, heat is applied along the edges from which the tabs extend to form a seal 48A. The inner layer of each soft envelope film is bonded to the tab film. Away from the tabs, the inner layers of the soft envelope films are bonded to each other. At 64, heat is applied along one edge to form a seal 48B. In an alternative embodiment using folded films, this step may not be required because the upper and lower films are joined at the fold line. After step 64, the soft envelope is open only on one side and can hold liquid as long as the open side is at the top. At 66, the soft envelope is filled with electrolyte. At 66, heat is applied to the remaining edges to form a seal 48C. After step 68, the soft envelope is completely sealed and can hold electrolyte in any orientation, even under pressure.

[0024] While exemplary embodiments are described above, these embodiments are not intended to describe all possible forms encompassed by the claims. Of course, other topologies and variations are conceivable.

[0025] The words used in the specification are words of description rather than limitation, and it is understood that various changes can be made without departing from the spirit and scope of the disclosure.

[0026] As previously mentioned, features of the various embodiments may be combined to form additional embodiments of the invention that may not be explicitly described or shown. Although various embodiments may have been described as providing advantages or being preferred over other embodiments or prior art implementations with respect to one or more desired characteristics, it will be recognized by those of ordinary skill in the art that one or more features or characteristics may be compromised to achieve desired overall system properties, depending on the specific application and implementation. These properties may include, but are not limited to, strength, durability, marketability, appearance, packaging, size, serviceability, weight, manufacturability, ease of assembly, etc. Therefore, embodiments described as being less desirable than other embodiments or prior art implementations with respect to one or more characteristics are not outside the scope of this disclosure and may be desirable for specific applications.

[0027] According to the present invention, a soft-pack battery cell is provided, the soft-pack battery cell having: an electrode stack, the electrode stack having an anode, a cathode and a separator; a positive electrode tab electrically connected to the cathode, the positive electrode tab defining at least one first anchoring hole; a negative electrode tab electrically connected to the anode, the negative electrode tab defining at least one second anchoring hole; upper and lower soft-pack membranes on opposite sides of the electrode stack, the positive electrode tab and the negative electrode tab protruding beyond edges of the upper and lower soft-pack membranes; and a polymer adhered to inner surfaces of the upper and lower soft-pack membranes, the polymer having anchors extending through at least one first anchoring hole and at least one second anchoring hole.

[0028] According to an embodiment, the upper pouch film and the lower pouch film are adhered to each other to form a sealed envelope around the electrode stack.

[0029] According to an embodiment, the invention also features an electrolyte contained within the sealed envelope.

[0030] According to an embodiment, the positive electrode tab is made of aluminum.

[0031] According to an embodiment, the negative electrode tab is made of copper.

[0032] According to an embodiment, the negative tab is welded to the anode; and the positive tab is welded to the cathode.

[0033] According to an embodiment, the polymer is a thermoplastic polymer.

[0034] According to an embodiment, the polymer is polypropylene.

[0035] According to the present invention, a tab assembly for a battery cell is provided, the tab assembly comprising: a conductive tab defining at least one anchor hole extending from a first surface to a second surface; and a polymer adhered to the first and second surfaces and including at least one anchor extending through the at least one anchor hole; wherein the conductive tab protrudes from the polymer in two directions.

[0036] According to an embodiment, the polymer is a thermoplastic polymer.

[0037] According to an embodiment, the polymer is polypropylene.

[0038] According to an embodiment, the conductive tabs are made of aluminum.

[0039] According to an embodiment, the conductive tabs are made of copper.

[0040] According to the present invention, a process for manufacturing a tab assembly for a soft-pack battery cell includes: placing a polymer tab film on each side of a conductive tab, the conductive tab having at least one anchor hole; and heating the conductive tab and the polymer tab film, thereby causing the polymer tab films to bond to each other through the at least one anchor hole to form at least one anchor.

[0041] In one aspect of the invention, the process includes applying pressure to the conductive tab and the polymer tab film during heating.

[0042] In one aspect of the invention, at least one of the polymer tab films has at least one protrusion extending into at least one anchor hole prior to heating.

[0043] In one aspect of the present invention, heating the conductive tab and the polymer tab film also causes the polymer tab film to bond to the conductive tab and to each other around both edges of the conductive tab.

[0044] According to the present invention, a process for manufacturing a soft-pack battery cell includes: manufacturing the first tab assembly and the second tab assembly of the previous embodiment; welding the first tab assembly to the anode of the electrode stack; welding the second tab assembly to the cathode of the electrode stack; placing an upper soft-pack film and a lower soft-pack film on opposite sides of the electrode so that the first tab assembly and the second tab assembly extend beyond the edges of the upper soft-pack film and the lower soft-pack film; and applying heat to adhere the upper soft-pack film and the lower soft-pack film to each other and to the polymer tab films of the first tab assembly and the second tab assembly to form a sealed envelope.

Claims

1. A soft pack battery cell, comprising: an electrode stack having an anode, a cathode, and a separator; a positive electrode tab electrically connected to the cathode, the positive electrode tab defining at least one first anchoring hole; a negative electrode tab electrically connected to the anode, the negative electrode tab defining at least one second anchoring hole; upper and lower soft-coat films on opposite sides of the electrode stack, the positive and negative electrode tabs protruding beyond edges of the soft-coat films; as well as A polymer adhered to the inner surfaces of the upper soft envelope and the lower soft envelope, the polymer having anchors extending through the at least one first anchoring hole and the at least one second anchoring hole. 2 . The pouch battery cell of claim 1 , wherein the upper film and the lower film are adhered to each other to form a sealed envelope around the electrode stack.

3. The soft pack battery cell of claim 2, further comprising an electrolyte contained within the sealed envelope.

4. The soft pack battery cell according to claim 1, wherein The positive electrode tab is made of aluminum; and The negative electrode tab is made of copper.

5. The soft pack battery cell according to claim 1, wherein The negative electrode tab is welded to the anode; and The positive tab is welded to the cathode.

6. A tab assembly for a battery cell, the tab assembly comprising: a conductive tab defining at least one anchor hole extending from the first surface to the second surface; as well as a polymer adhered to the first surface and the second surface and comprising at least one anchor extending through the at least one anchor hole; in The tabs protrude from the polymer in two directions.

7. The tab assembly of claim 6, wherein the polymer is a thermoplastic polymer.

8. The tab assembly of claim 6, wherein the polymer is polypropylene.

9. The tab assembly of claim 6, wherein the tab is made of aluminum.

10. The tab assembly of claim 6, wherein the tab is made of copper.

11. A process for manufacturing a tab assembly for a soft-pack battery cell, the process comprising: placing a polymer tab film on each side of a conductive tab, the tab having at least one anchor hole; as well as The tab and the polymer film are heated, thereby causing the polymer films to bond to each other through the at least one anchor hole to form at least one anchor.

12. The process of claim 11 further comprising applying pressure to the tab and the polymer film while heating them.

13. The process of claim 11, wherein at least one of the polymer films has at least one protrusion extending into the at least one anchor hole prior to heating.

14. The process of claim 11, wherein heating the tab and the polymer film further causes the polymer film to bond to the tab and to each other around two edges of the tab.

15. A process for manufacturing a soft pack battery cell, the process comprising: manufacturing a first tab assembly and a second tab assembly according to the process of claim 11; welding the first tab assembly to the anode of the electrode stack; welding the second tab assembly to the cathode of the electrode stack; placing an upper pouch and a lower pouch on opposite sides of the electrode stack such that the first tab and the second tab extend beyond edges of the pouch; as well as Heat is applied to adhere the upper and lower soft cover films to each other and to the polymer of the tab assembly to form a sealing envelope.

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