Tool and method for producing electrodes for lithium ion batteries

Abstract

The present disclosure provides a tool and method for producing an electrode for a lithium ion battery. A method of manufacturing an electrode includes supplying a stack of material into a chamber of a vertical press. The material stack includes a current collector sheet and an active material disposed thereon. The method further includes closing the vertical press to compress the stack of materials to shape an electrode blank; and while still compressed, cutting the electrode blank to a length while cutting a current collector tab to form a finished electrode.

Description

Technical Field

[0001] The present disclosure relates to the production of lithium-ion batteries, and more particularly, to the manufacture of electrodes. Background Art

[0002] The vehicle may include an electric powertrain. The powertrain may include one or more electric machines capable of acting as a motor to propel the vehicle and as a generator to regeneratively brake the vehicle. The one or more electric machines may be powered by a traction battery. The traction battery may include a plurality of battery cells. The battery cells may have a lithium-ion chemistry. Summary of the invention

[0003] According to one embodiment, a method of manufacturing an electrode includes supplying a material stack into a chamber of a vertical press. The material stack includes a current collector sheet and an active material disposed thereon. The method also includes: closing the vertical press to compress the material stack to form an electrode blank; and while still being compressed, cutting the electrode blank to a certain length while cutting the current collector tab to form a finished electrode.

[0004] According to another embodiment, a method for manufacturing an electrode includes: opening a tool having side-by-side presses so that an upper mold of the press is spaced apart from a lower mold of the press; supplying a material stack including a collector sheet and an active material disposed thereon into the press; closing the presses simultaneously to compress the material stack between the molds of each press to form a pair of coating films; and cutting the coating films while still being compressed to form two electrodes.

[0005] According to yet another embodiment, a tool for forming a battery electrode includes a press having a lower die and an upper die that are closable to compress a current collector between active material layers to form an electrode blank. A cutting tool is attached to one of the lower die and the upper die. The cutting tool includes a continuous cutting edge that completely circumscribes the one of the lower die and the upper die, wherein the cutting edge includes a first portion configured to cut a tab in the current collector and a second portion configured to cut a first side of the electrode blank. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 is a perspective view of an example battery cell.

[0007] Figure 2 is a diagrammatic perspective view of an example electrode for use in a battery cell.

[0008] Figure 3 is a diagrammatic side view of a tool for producing electrodes from dry active material.

[0009] Figure 4 This is a top view of the material pile.

[0010] Figure 5 yes Figure 3 Diagrammatic bottom view of the upper die and cutting unit of the tool.

[0011] Figure 6 is a diagrammatic side view of another tool for producing electrodes.

[0012] Figure 7 is a diagrammatic side view of yet another tool for producing multiple electrodes in a single cycle. DETAILED DESCRIPTION

[0013] Embodiments of the present disclosure are described herein. However, it should be understood that the disclosed embodiments are merely examples, and other embodiments may take on various forms and alternative forms. The drawings are not necessarily drawn to scale; some features may be enlarged or minimized to show the details of a particular component. Therefore, the specific structural details and functional details disclosed herein are not to be interpreted as limiting, but only as a representative basis for teaching those skilled in the art to adopt the present invention in various ways. As will be understood by those of ordinary skill in the art, the various features shown and described with reference to any one of the drawings may be combined with the features shown in one or more other drawings to produce embodiments that are not explicitly shown or described. The combination of features shown provides representative embodiments for typical applications. However, for specific applications or embodiments, various combinations and modifications of features consistent with the teachings of the present disclosure may be desired.

[0014] An electrified vehicle may include one or more electric machines mechanically connected to driven wheels through a drive train. The electric machine may be capable of operating as a motor or a generator. In the case of a hybrid, the engine is connected to one or more electric machines through a transmission. The electric machine may provide propulsion and braking capabilities. The electric machine also acts as a generator and may provide fuel economy benefits by recovering energy through regenerative braking.

[0015] The traction battery or battery pack stores energy that can be used by the electric machine. The traction battery typically provides a high voltage direct current (DC) output from one or more battery cell arrays (sometimes referred to as battery cell stacks) within the traction battery. A battery cell array includes one or more battery cells.

[0016] A battery cell (such as a prismatic, pouch, cylindrical, or any other type of unit) converts stored chemical energy into electrical energy. A battery cell may include a housing, a positive electrode (cathode), and a negative electrode (anode). An electrolyte allows ions to move between the anode and cathode during discharge and then back during recharge. Terminals may allow current to flow out of the cell for use in a vehicle.

[0017] Different battery pack configurations can be used to meet various vehicle variables, including packaging constraints and power requirements. Thermal management systems can be used to thermally control the battery cells. Examples of thermal management systems include air cooling systems, liquid cooling systems, and combinations of air and liquid systems.

[0018] The traction battery may be electrically connected to the one or more power electronics modules via one or more contactors (not shown). The one or more contactors isolate the traction battery from other components when open and connect the traction battery to the other components when closed. In addition to providing energy for propulsion, the traction battery may also provide energy to other vehicle electrical systems.

[0019] The traction battery assembly includes one or more battery arrays, each battery array having a plurality of battery cells arranged in a stack. Figure 1 An example battery cell 20 is shown in FIG. The cell may be a pouch cell, a square cell, a cylindrical cell, or the like. A positive terminal 22 and a negative terminal 24 extend from an outer body 25 of the cell 20. Each cell 20 may have two terminals, for example, where the positive terminal and the negative terminal extend from different sides (as shown) or extend on the same side. Typically, each cell contains a cathode, an anode, a separator, and an electrolyte. The positive terminal 22 is electrically connected to the cathode, and the negative terminal 24 is electrically connected to the anode. The anode and cathode may be referred to as electrodes.

[0020] refer to Figure 2 , the electrode 30 can be used as an anode or a cathode. The electrode can be used in a lithium-ion battery or other suitable chemistry. In one embodiment, the electrode 30 is associated with the anode of a lithium-ion battery. The electrode 30 generally includes three layers: an intermediate current conductor layer 32 and a first outer layer 34 and a second outer layer 36 bonded to the current collector 32. The current collector 32 is formed of a metal such as copper, aluminum or other suitable conductive material, and includes a tab 38 that provides an electrical connector. The outer layers 34, 36 can be referred to as active material coatings. The outer layers 34, 36 are produced using a "dry" process or a "wet" process.

[0021] Figure 3 An example tool 50 configured to produce an electrode using a pressing and cutting process is shown. The tool 50 shown is for use with dry active materials. The tool 50 includes an input area 52 that supports a roll of current collector 54, a roll of upper coating material 56 (active material), and a roll of lower coating material 58 (active material). The upper coating 56, the current collector 54, and the lower coating 58 are fed into a tension adjustment system 60, which includes a pair of entry rollers 62, 64, a movable roller 66, and an exit roller 68. The rollers 62, 64, 66 are fixed, while the roller 68 can move up and down.

[0022] The upper coating 56, the current collector 54, and the lower coating 58 are fed between rollers 62 and 64 to create a material stack 65 that will be processed into a finished electrode. The width of the current collector roll 54 can be wider than the coating rolls 56, 58 so that the material stack has an exposed current collector 70 along the edge, as shown in FIG. Figure 4 The exposed current collector will be cut later to form the tabs of the electrode.

[0023] The tool 50 includes a press 72 having an upper die 74 and a lower die 76. The upper die 74 and the lower die 76 can move relative to each other between an open position and a closed position. For example, the lower die 76 can be fixed, while the upper die 74 can move up and down. The dies 74, 76 cooperate to define a pressing chamber 78.

[0024] The material pile 65 is received within an open press chamber 78 with an upper die 74 spaced apart from a lower die 76. As the material pile is fed into the press 72, the rollers 66 are moved upward to reduce tension, and when a sufficient amount of the material pile has been fed into the press chamber 78, the rollers are moved downward (position shown) to increase tension.

[0025] The press 72 is used to bond the upper coating 56 and the lower coating 58 to the current collector 54. This is in contrast to the conventional calendering method. The upper mold 74 is lowered toward the lower mold 76 to compress the material stack, so that the active materials 56, 58 are bonded to the current collector 54. At this point, the material stack can be referred to as a coating film or an electrode blank. The press 72 can be heated (optional). For example, a heating channel 80 can be defined in the upper mold 74, the lower mold 76, or both. The heating channel 80 is configured to circulate a hot fluid (e.g., oil) to heat the mold, which can be a metal. Alternatively, an electric heating element can be used. During pressing, the pressure is controlled to achieve target electrode density, porosity, and thickness.

[0026] refer to Figure 3 and Figure 5, the tool 50 also includes a cutting unit 82 configured to cut the coating film. The cutting unit 82 is configured to simultaneously cut the coating film into a desired length and cut the tab from the exposed edge 70 of the collector 54. The cutting unit 82 includes a cutting tool 84 supported on the press 72. For example, the cutting tool 84 can be movably attached to the upper mold 74 so that the cutting tool 84 can move up and down. Alternatively, the cutting tool 84 can be mounted to the lower mold 76 or other supporting structure. The cutting tool 84 includes a cutting edge 86. The cutting edge 86 can be continuous and form a closed polygon. The cutting tool 84 and the cutting edge 86 can be sized to circumscribe the upper mold 74 or the lower mold 76 or both. The cutting edge 86 can be formed by a plurality of sections, and the plurality of sections can be straight. For example, the cutting edge 86 includes a first section 88, a second section 90, a third section 92, a fourth section 94, a fifth section 96, a sixth section 98, and a seventh section 100, all of which are interconnected to form a continuous cutting edge. Segments 88 and 92 cut the electrode stock to the desired length. Segments 90, 94 and 102 cut the electrode stock to the desired length. Segments 96, 98 and 100 are used to cut tabs in the current collector. All segments of cutting edge 86 may be coplanar.

[0027] The cutting unit 82 includes a lowering mechanism (not shown) for moving the cutting tool 84 up and down. The lowering mechanism can be hydraulic, pneumatic, electronic, manual, etc. The cutting edge 86 (or other parts of the cutting tool 84) can be heated. The heating can be electrical heating, fluid heating, etc.

[0028] Tool 50 integrates various individual processes of traditional electrode forming methods into a single tool, thereby creating an efficient and simplified process for forming electrodes. The new process begins by feeding the upper coating 52, the current collector 54 and the lower coating 58 into the slack adjustment system 60, thereby creating a material pile. The material pile 65 is fed into the open press 72. Once properly positioned, the upper mold 74 is lowered toward the lower mold 76 when the cutting tool 84 is retracted. The upper mold 74 and the lower mold 76 compress the active materials of the upper coating 56 and the lower coating 58 onto the current collector 54, thereby creating an electrode blank. The press provides the desired pressure, temperature and holding time to properly bond the active material to the current collector. Next, the electrode blank is cut to form the desired size of the electrode and the current collector tab is cut. This cutting occurs when the mold is still compressed. The electrode blank is cut by lowering the cutting tool 84 through the electrode blank. This single cutting process performs all necessary cutting, and once completed, a finished electrode 93 is produced. The mold is then opened, allowing the finished electrode 93 to be separated from the waste. The waste can be wound on a waste roll 91, and the finished electrode 93 can be loaded in a box and delivered to another area to be assembled into a battery cell. Alternatively, the electrode can be delivered directly to the next manufacturing process.

[0029] Tool 50 can include a suction system (not shown) for separating electrode 93 from waste material 91. For example, once cutting is completed, cutting tool 84 begins to retract toward its original position, while upper mold 74 remains downward to hold the electrode being cut in place to prevent any lifting of the electrode. Once the cutting tool has passed a certain height of the upper mold (sensors inside the upper mold can check the stroke), the upper mold will be lifted from the electrode. Because the electrode is still located in the foil around, it can be carried on the suction conveyor by its foil. At this point, the waste material will be lifted, and the electrode will be held via the suction on the conveyor, and transported to a visual inspection system (optional), and according to the inspection result, transported to a waste box or a box unit for further processing in downstream equipment. Tool 50 can include a plurality of presses arranged upstream and downstream of each other, thereby allowing each cycle to produce a plurality of electrodes.

[0030] Figure 6 Another tool 101 for use with an electrode made of a solvent-based slurry or a solvent-free dry active material is shown. In the illustrated embodiment, tool 101 is loaded with a solvent-based slurry active material. Here, the material pile is previously formed and wound by another tool, and a preformed roll 103 (e.g., a mother roll or a daughter roll) is supported on a slide valve of tool 101. As described above, roll 103 may include an exposed edge of a current collector. Similar to tool 50, tool 101 includes a tension adjustment system 104 for feeding material pile 103 to press 106. Press 106 may be the same or similar to press 72. Presses 72 and 106 may be slightly different to account for the difference between wet active materials and dry active materials. For example, pressure and / or pressing time may vary as desired. A cutting system 108, which may be the same or similar to cutting unit 82, may be supported on the press. In addition to forming the material pile, tool 101 may produce an electrode similar to the process discussed above, and for the sake of brevity, this will not be described again. The tool 101 may include multiple presses arranged upstream and downstream of each other, allowing multiple electrodes to be produced per cycle.

[0031] Figure 7Another tool 150 is shown that includes multiple presses. Tool 150 can be used with electrodes made of solvent-based slurries or solvent-free dry active materials. If tool 150 is used for drying, tool 150 may include an input area (not shown) similar to input area 52. In this example, four presses are shown; however, it should be understood that this is only an example and tool 150 may include two presses or more than four presses. In the illustrated embodiment, the presses are arranged in side-by-side pairs, which allows the parent roll (a roll with exposed collectors on both sides) to be fed into tool 150. Similar to the above-mentioned tools, an unbonded material pile is provided at the input side of tool 150, and a finished electrode or, in this case, an electrode is output.

[0032] The tool 150 includes a first press 152 arranged side by side with a second press 154. A second pair of presses 156 and 158 are arranged side by side downstream of the first pair of presses. Each press includes associated upper and lower dies and a cutting tool 160. This allows four electrodes to be produced during each cycle of the tool 150. The upper and lower dies and the cutting tool 160 can be the same or similar to those described above. By arranging the presses side by side, a parent roll can be provided into the tool 150, thus skipping the traditional manufacturing step of slitting to produce sub-rolls.

[0033] The material pile 162 is fed into the tool 150 so that the material pile is disposed in the chamber of each of the presses. Similar to the above process, the upper and lower molds are then closed to bond the active material 164 to the current collector 166, thereby forming four electrode blanks. Next, the electrode blanks are cut using the cutting tool 160 as described above. The cutting process produces four electrodes 170, which are transferred to a conveyor or other area to be installed in the battery cell. In this example, all four molds can be closed at the same time, and all four cutting tools can be deployed at the same time, so that four electrodes are produced at the same time.

[0034] The above tools combine multiple steps of the traditional manufacturing process (performed with dedicated tools such as calendars, slitters and slotters) into simultaneous steps performed on a single tool. This can improve efficiency by limiting the number of tools required to produce the electrode.

[0035] Using a press to form the electrode blank also overcomes the shortcomings of the calendaring process. For example, calendaring creates shear stresses in the active material. In the process of the present disclosure, these shear stresses are reduced because the shear forces generated during pressing are outside the cutting line of the cutting tool.

[0036] Although exemplary embodiments are described above, these embodiments are not intended to describe all possible forms covered by the claims. The words used in the specification are descriptive words rather than restrictive words, and it should be understood that various changes can be made without departing from the spirit and scope of the present disclosure. As previously described, the features of various embodiments can be combined to form other embodiments of the present invention that may not be explicitly described or shown. Although various embodiments may have been described as providing advantages or being superior to other embodiments or prior art implementations in terms of one or more desired characteristics, it will be appreciated by those of ordinary skill in the art that one or more features or characteristics may be compromised to achieve the 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, maintainability, weight, manufacturability, ease of assembly, etc. For this reason, embodiments described as less desirable than other embodiments or prior art implementations in terms of one or more characteristics are within the scope of the present disclosure and may be desirable for specific applications.

[0037] According to the present invention, a method for manufacturing an electrode includes: supplying a material stack into a chamber of a vertical press, wherein the material stack includes a current collector sheet and an active material disposed thereon; closing the vertical press to compress the material stack to form an electrode blank; and while still being compressed, cutting the electrode blank to a certain length and simultaneously cutting the current collector tabs to form a finished electrode.

[0038] In one aspect of the invention, the method includes opening the vertical press so that the finished electrode is lifted from the waste material of the blank.

[0039] In one aspect of the present invention, the press comprises an upper die and a lower die, and further comprises lifting the finished electrode from the lower die via the upper die.

[0040] In one aspect of the invention, the active material is an active material film.

[0041] In one aspect of the invention, said cutting of said current collector comprises actuating a cutting tool attached to said vertical press.

[0042] In one aspect of the present invention, the press includes an upper die, a lower die, and a cutting tool slidably coupled to the upper die, wherein the cutting of the current collector includes lowering the cutting tool past a bottom surface of the lower die.

[0043] In one aspect of the present invention, the cutting tool includes a cutting edge having a closed polygonal cross-section when viewed from the bottom of the cutting tool.

[0044] According to the present invention, a method for manufacturing an electrode includes: opening a tool having side-by-side presses so that an upper mold of the press is spaced apart from a lower mold of the press; supplying a material stack including a collector sheet and an active material disposed thereon into the press; closing the presses simultaneously to compress the material stack between the molds of each press to form a pair of coating films; and cutting the coating films while still being compressed to form two electrodes.

[0045] In one aspect of the invention, the cutting includes simultaneously cutting the current collector sheet to form tabs and cutting the stack of material to length.

[0046] In one aspect of the invention, each of said presses comprises an associated cutting tool for performing said cutting.

[0047] In one aspect of the present invention, each of the cutting tools includes a first cutting edge configured to cut a corresponding one of the tabs and a second cutting edge configured to cut the pile of material to length.

[0048] In one aspect of the invention, the active material is narrower than the current collector sheet, such that the current collector sheet is exposed along the side edges of the material stack.

[0049] In one aspect of the invention, the method comprises opening the press after the cutting such that the electrode remains attached to its respective upper or lower die while waste material remains attached to the other of the upper or lower die.

[0050] In one aspect of the invention, said cutting of said coating film comprises sliding cutting tools through said coating film, each cutting tool being associated with one of said presses.

[0051] In one aspect of the present invention, the cutting tool is slidably attached to the upper die.

[0052] In one aspect of the invention, the method comprises heating the upper die and the lower die of the press during at least a portion of the closing of the press.

[0053] In one aspect of the invention, the method includes feeding a current collector roll and upper and lower coating film rolls through a slack adjustment system of the tool to form the material stack.

[0054] According to the present invention, a tool for forming a battery electrode is provided, which comprises: a press, the press comprising a lower mold and an upper mold, the lower mold and the upper mold being closable to compress a current collector between active material layers to form an electrode blank; and a cutting tool, the cutting tool being attached to one of the lower mold and the upper mold, the cutting tool comprising a continuous cutting edge that completely circumscribes the one of the lower mold and the upper mold, wherein the cutting edge comprises a first portion configured to cut a tab in the current collector and a second portion configured to cut a first side of the electrode blank.

[0055] According to an embodiment, the cutting edge further includes a third portion configured to cut the second side of the electrode blank, a fourth portion configured to cut the third side of the electrode blank, and a fifth portion configured to cut the fourth side of the electrode blank.

[0056] According to an embodiment, the second portion, the third portion, the fourth portion and the fifth portion are straight sections arranged to form a rectangle.

Claims

1. A method for manufacturing an electrode, comprising: supplying a material stack into a chamber of a vertical press, wherein the material stack includes a current collector sheet and an active material disposed thereon; closing the vertical press to compress the material stack to form an electrode blank; as well as While still compressed, the electrode blank is cut to length and the current collector tabs are cut simultaneously to form the finished electrode.

2. The method of claim 1, further comprising: The vertical press is opened, allowing the finished electrode to be lifted from the waste material of the blank.

3. The method of claim 1, wherein the press comprises an upper die and a lower die, and further comprising lifting the finished electrode from the lower die via the upper die. The method of claim 1 , wherein the active material is an active material film.

5. The method of claim 1, wherein said cutting of said current collector comprises actuating a cutting tool attached to said vertical press.

6. The method of claim 1, wherein the press comprises an upper die, a lower die, and a cutting tool slidably coupled to the upper die, wherein the cutting of the current collector comprises lowering the cutting tool past a bottom surface of the lower die.

7. The method of claim 6, wherein the cutting tool includes a cutting edge having a closed polygonal cross-section when viewed from a bottom of the cutting tool.

8. A method for manufacturing an electrode, comprising: opening a tool having a side-by-side press such that an upper die of the press is spaced apart from a lower die of the press; supplying a material stack including a current collector sheet and an active material disposed thereon into the press; closing the presses simultaneously to compress the stack of material between the dies of each press to form a pair of coating films; as well as The coated film is cut while still compressed to form two electrodes.

9. The method of claim 8, wherein said cutting comprises simultaneously cutting said current collector sheet to form tabs and cutting said stack of material to length.

10. The method of claim 8, wherein each of the presses includes an associated cutting tool that performs the cutting.

11. The method of claim 10, wherein each of the cutting tools comprises a first cutting edge configured to cut a corresponding one of the tabs and a second cutting edge configured to cut the pile of material to length.

12. The method of claim 8, wherein the active material is narrower than the current collector sheet such that the current collector sheet is exposed along side edges of the material stack.

13. The method of claim 8, further comprising opening the press after the cutting such that the electrode remains attached to its respective upper or lower die while waste material remains attached to the other of the upper or lower die.

14. The method of claim 8, wherein the cutting of the coating film comprises sliding cutting tools through the coating film, each cutting tool being associated with one of the presses.

15. A tool for forming a battery electrode, the tool comprising: a press including a lower mold and an upper mold that are closable to compress the current collector between the active material layers to form an electrode blank; as well as A cutting tool is attached to one of the lower die and the upper die, the cutting tool comprising a continuous cutting edge that completely circumscribes the lower die and the upper die, wherein the cutting edge comprises a first portion configured to cut a tab in the current collector and a second portion configured to cut a first side of the electrode blank.

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