Patent Application
20230010970
Lithium based batteries (or Li-ion batteries) are being produced in large quantities and battery recycling is becoming important for environmental health and a sustainable future. One of the biggest challenges in Li-ion battery recycling is the disassembly and separation of cell components. Currently, most battery recycling process uses a mechanical means to crush the discharged battery creating a mixture of cell components. This mixture undergoes a high-temperature melting-and-extraction or smelting process to purify these components making battery recycling economically and environmentally unfeasible.
WO 2017/039143 A1 (LG Chem) discloses an electrode assembly of a battery, including a positive electrode plate having positive electrode tabs, a negative electrode plate having negative electrode tabs, and a separator interposed between the positive electrode plate and the negative electrode plate. In one embodiment, the positive electrode tabs and the negative electrode tabs protrude in four directions of the electrode assembly while forming a 90-degree angle.
The patent references CN 203434245 U (Kunwing University of Science & Technology), CN 209860067 U (Shantou Kairui Investment), U.S. Pat. No. 6,692,866 B2 (NEC Mobile Energy Corporation) and CN 201717335 U (Xingbao Chen) disclose a battery comprising a positive and a negative tab that are orthogonal to each other.
An object of the present invention is to provide a cost-effective, flexible packaging-based recycling solution to make battery recycling economically feasible and allowing conservation of natural resources required for a sustainable future.
In a first embodiment, a cell of a lithium-ion battery comprises a plurality of anodes of rectangular shape, each anode having a current collector tab protruding from a side of the rectangular shape, and a plurality of cathodes of rectangular shape, each cathode having a current collector tab protruding from a side of the rectangular shape,
wherein each cathode is wrapped in a separator sheet, the cathode tab being exposed outside of the separator sheet, and
wherein, the cathodes and anodes are stacked on each other according to the following arrangement:
a first anode with the tab protruding in a first direction,
a first cathode with the tab protruding in a second direction orthogonal to the first direction,
a second anode with the tab protruding in a third direction opposite to the first direction, and
a second cathode with the tab protruding in a fourth direction opposite to the second direction.
This embodiment may comprise other features, alone or in combination such as:
In a second embodiment, a lithium-ion battery comprises at least one cell according to the first embodiment and at least four bus bar posts, each bus bar post being positioned in front of one tab in order to create an electrical connection between the tab and the bus bar post.
This embodiment may comprise other features, alone or in combination such as:
In a third embodiment, a method for disassembling a battery according to the second embodiment comprises:
This embodiment may comprise other features, alone or in combination such as:
The cell materials can be recovered without destroying electrode structures or material mixing, thereby enabling profitable direct recycling of each of the cell components with a low environmental profile.
Reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein:
The present disclosure more fully describes various embodiments with reference to the accompanying drawings. It should be understood that some, but not all embodiments are shown and described herein. Indeed, the embodiments may take many different forms, and accordingly this disclosure should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like numbers refer to like elements throughout. Also, in the following description, a same element may have different references in different figures.
Should the disclosure of any patents, patent applications, and publications which are incorporated herein by reference conflict with the description of the present application to the extent that it may render a term unclear, the present description shall take precedence.
In general, a secondary Li-ion battery has a structure in which a unit cell composed of a positive electrode (cathode), a negative electrode (anode), and a polymer separator interposed between the positive electrode and the negative electrode is stacked or wound and built in a case of a metal can or laminate sheets, and the electrolyte is injected therein.
A unit cell, also called electrochemical cell or battery cell, is thus the basic active unit of the battery and comprises a cathode, an anode and a polymer separator interposed between the cathode and the anode.
The present disclosure relates to a unit cell, a battery and a method for disassembling process. The unit cell and stack of cells in the battery are such as to enable an automated disassembly of the battery cell components. The cell materials can be recovered without destroying electrode structures or material mixing, thereby enabling profitable direct recycling of each of the cell components with a low environmental profile.
The present disclosure relates to a unit cell comprising a plurality of anodes of square or rectangular shape, each anode having at least one current collector tab protruding from a side of the rectangular shape, and a plurality of cathodes of square or rectangular shape, each cathode having at least one current collector tab protruding from another side of the square or rectangular shape,
The unit cell disclosed herein comprises four electrodes having tabs protruding in four distinct directions.
The electrodes have a square or a rectangular shape with a length to width aspect ratio equal to 1 or, preferably greater than 1. If the electrodes are rectangular, the length side is the longest side of the rectangular shape and the width side is the shortest side of the rectangular shape.
The cathodes and anodes are respectively electrically connected to the cathode bus bar posts and the anode bus bar posts via conducting members, which are hereby called tabs (e.g., thin flat conducting strips and/or the like). Tabs can be of various shapes and sizes, as explained below in more details. As described below, the size and shape of the tabs are adapted to the electrode bus bar posts, more specially to the shape and size of the bus bar posts.
The anode may have one or several tabs, for example on its length side. Similarly, the cathode may have one or several tabs, for example on its width side. The number of tabs for each electrode is not limited. Each electrode may for example have 1, 2, 3 or more tabs. The number of tabs for each electrode (anode and cathode) in a stack is usually the same; however, various embodiments are possible.
In some embodiments, the anodes comprise a plurality of tabs protruding on the length sides of the anodes and the cathodes comprise a plurality of tabs protruding on the width sides of the cathodes.
In a preferred embodiment, the anode tabs protrude (i.e., are located) on the length sides of the anodes and the cathode tabs protrude (i.e., are located) on the width sides of the cathodes.
In an embodiment, a cell designed for easy recyclability is depicted in
Electrodes 1, 3, 5, 7 have a rectangular shape with a length to width aspect ratio greater than or equal to 1. Each electrode 1, 3, 5, 7 has a current collector tab 9, 11, 13, 15 protruding from a side of the rectangular shape.
Electrodes 1, 3, 5, 7 comprise two anodes 1, 5 and two cathodes 3, 7 and the cathodes 3, 7 and anodes 1, 5 are stacked on each other according to the following arrangement:
The tabs 9, 13 of anodes 1, 5 protrude on the length sides of the rectangle and the tabs 11, 15 of cathodes 3, 7 protrude on the width sides of the rectangle.
According to the disclosed embodiment, electrode pair consists of one anode and one cathode, wherein the cathode is wrapped in a separator sheet (which is not shown on
In some preferred embodiment, only one separator sheet is used and folded over the cathode along the length of the cathode, so that the tab protrudes (i.e., is located) on the width side of the cathode.
As depicted on
Wrapping the cathode in a separator is advantageous because it avoids the high current density between the anode and the cathode, as there is typically misalignment of the electrodes when assembling and/or using the battery, notably due to the fact that the anodes and cathodes do not necessarily have the same size.
Referring to
The separator (reference 21 on
The separator seal 23 may be done using a press, for example a heat press, which melts the polymer (e.g., polymer of the polymeric microporous layer) used in the separator until it melts. And heat sealing is possible with single sided ceramic coated separator. Single side coating of separator allows heat sealing of edges as one side has only polymer. The sealing step is carried out at a temperature equal to or above the melting temperature (Tm) of the polymer used in the separator sheet.
The present disclosure also relates to a Li-ion battery comprising at least one-unit cell as described herein and four bus bar posts, each bus bar post being positioned in front of one tab in order to create an electrical connection between the tab and the bus bar post. The anode bus bar post is always electrically isolated from the casing and the cathode bus bar post, depending upon the battery application, may be electrically isolated from the casing.
In some embodiments, the battery is such that it comprises:
Therefore, in the disclosed embodiment, during the assembling process, the anodes are placed such that their tabs are placed at opposite locations e.g., if the first anode tab (1st anode tab—odd) is on one side along the length of the electrode, the second anode tab (2nd anode tab—even) is then on the opposite side along the length of the electrode. Similarly, for the cathodes, tabs are placed at opposite locations along the width e.g., if the first cathode tab (1st cathode tab—odd) is on one side along the width of the electrode, the tab second cathode tab (2nd cathode tab—even) is on the opposite side along the width of the electrode. Thus, all odd-numbered anode tabs are located on one side while all even-numbered anode tab are located on the opposite side. Similarly, all odd-numbered cathode tabs are located on one side while all even-numbered cathode tabs are located on the opposite side.
The unit cell of the present disclosure therefore comprises two electrode pairs:
In some preferred embodiments, the electrodes have tabs protruding in one direction only. For example, in some embodiments, the electrode have one tab only per electrode, and each of the four electrodes tab in the unit cell disclosed herein protrudes in a distinct direction from the three other tabs of the unit cell. If the electrodes are rectangular, the tabs of the cathodes are preferably located on the length sides, while the tabs of the anodes are preferably located on the width sides.
Referring to
In the present disclosure, the stacking of electrodes pair in the assembling process is performed in two steps: anode placement followed by cathode placement (cathode being wrapped in a separator sheet). This stacking scheme differs from the traditional stacking of electrodes, consisting in three steps, i.e., stacking of the anode, the separator and the cathode in sequence. Further, the traditional electrode stacking process can result in lithium plating due to higher current density at the electrode edges arising from the misalignment of the stacked electrodes. The disclosed embodiment overcomes such limitation of traditional stacking and make cells safer by preventing lithium plating issues, even with misaligned electrode placement, as the positive electrode is wrapped in the separator covering the edges of the positive electrode. In a not preferred embodiment, separator can be placed using traditional stacking method or can be wrapped without sealing when separator has ceramic coating on both sides.
Referring to
Battery 31 includes a casing (or a housing) 37 for closing the battery, comprising a top cover 38 and side walls 39, a bottom plate (or base plate) 36, and a stack of cells 35. Alternatively, the casing 37 can be in two separate parts: one top cover 38 and one ring for the side walls, as notably depicted in
The bottom plate 36 preferably include heat transfer elements 361, for example ribs, for increasing the air flow. They increase the surface area of the bottom plate 36 and allow a better cooling of the battery when in use. The heat transfer elements 361 are preferably part of the bottom plate (integrated in the bottom plate) as depicted in
The bottom plate 36 also preferably include slots (or cavities) 362 which are the same size and shape as the bus bar posts, in order to maintain the bus bar posts in place when the battery is assembled. Other methods to attach bus bar to casing are also possible. The top cover 38 (should it be in the form of a casing or as separate element of the assembly) may also include slots or cavities or holes 382 which are the same size and shape as the bus bar posts, in order to maintain the bus bar posts in place when the battery is assembled.
The casing and the bottom plate are for example made of electrically and thermally conductive metals such as steel or aluminum.
Odd and even electrode pairs are stacked to create a cell stack. Odd and even anodes within electrode pairs are respectively electrically connected to the same bus bar post. For example, the 1st, 3rd, 5th . . . nth anodes (i.e., odd anodes) within each electrode pairs are connected to the same bus bar post on the length side, while the 2nd, 4th, 6th . . . nth anodes (even anodes) are connected to the bus bar post located on the opposite length side of the cell stack. In a similar way, odd and even cathodes within electrode pairs are respectively electrically connected to the same bus bar post. 1st, 3rd, 5th . . . nth cathodes (i.e., odd cathodes) within electrode pairs are connected to one bus bar post in the width side of the cell stack, while 2nd, 4th, 6th . . . nth cathodes (even cathodes) are connected to the bus bar post on the opposite width side. Alternate electrode tab location eases separation of cell components during the dissembling process, while providing high safety and capacity scalability as discussed thereafter.
The electrode tabs are preferably attached to the bus bar post by welding, for example ultrasonic welding, laser welding, resistance welding, or the like.
Two bus bar posts 33 (33a, 33b) for the anodes and two bus bar posts 32 (32a, 32b) for the cathodes are depicted on
According to the disclosed embodiments, tabs and bus bar posts can be of various size and shape. Several layouts of the tabs and the bus bar posts, as well as connections between the two, are now disclosed.
In a preferred embodiment, which is depicted in
In the embodiment of
The embodiment of
The embodiment of
In one preferred embodiment associated with
In the embodiment of
Bus bar posts may be in one-piece or in several pieces. For example, the bus bar post may be a one-U-shape piece, or alternatively it can consist in two bars which are positioned side-by-side in the battery assembly, for example screwed on the bottom plate close enough so that the tabs can be welded on them.
During the assembling process, the distal ends of the tabs (i.e., the tab parts situated farthest from point of attachment to the electrodes) may be bent and welded onto the bus bar posts. Preferably, the size of the tabs is such that the welded tabs overlap on each other when welded on the bus bar posts. This is advantageous as the overlaps increase the strength of the battery assembly.
For example, in one embodiment wherein the anode thickness is about 200 microns, the wrapped cathode thickness is about 155 microns, the electrode tabs are at least about 500 microns long from the base to distal extremity. In some embodiments, the electrode tabs are at least about 600 microns long from the base to distal extremity, at least 700 microns, at least 800 microns, at least 900 microns, and even at least 1,000 microns long (or 1 mm). Referring to
The bus bar posts in the battery assembly of the present disclosure may preferably be the same. Distinct bus bar post designs may alternatively be used in the assembly of the present disclosure.
The electrode tabs in the battery assembly of the present disclosure may be the same for all electrodes. Alternatively, the electrodes of the present disclosure may present tabs of distinct designs, as long as all the electrodes connected to the same bus bar post present the same design.
In some embodiments, the tabs are positioned in the bus bars post and are welded to a side of their respective bus bars posts (not shown in
In the embodiment of
In the embodiment of
An electrical connection design where the top of the electrode bus bar post 91 has internal threads or similar connecting embodiment is depicted in
In another embodiment, both odd and even positive electrodes are isolated from the casing using a method similar to the one used for negative electrode isolation from the casing. This embodiment provides flexibility in electrical connection.
One aspect of the present disclosure is a method for assembling the battery described herein. The assembling method of the present disclosure is preferably designed to be automated. The method comprises wrapping a cathode into a separator, placing an anode on a bottom plate (or base plate) or in a casing, and stacking the wrapped cathode onto the anode. These steps are repeated as needed, depending on the number of unit cells or electrode pairs in the battery.
Because the cathodes tabs are located on the width sides of the cathodes, the wrapping of the cathode in the separator sheet, for example according to
Electrode tab design, stacking method and packaging described above allow simplified separation of electrodes from the cell structure at the end-of-cell life, without mixing of electrode material. An aspect of the present disclosure is directed to a method for disassembling a battery as described above. This method comprises the following four steps:
The disassembling method of the present invention is preferably designed to be automated. Force to slide electrodes can be reduced by reducing friction between layers with the application of vibration and/or use of appropriate liquid.
In the method for disassembling the battery described herein, the tabs are attached to the bus bar posts when the anode bus bar posts are hold and the cathode bus bar posts are simultaneously pulled in the direction of the cathode tab protrusions.
A step-by-step process to separate the positive electrode, negative electrode and cell component is depicted in
At the end of the first step of the disassembling process:
The odd and even anode attached to their respective bus bar posts are then separated from each other by pulling the posts in opposite direction.
At the end of the second step of the disassembling process:
The third and four steps of the disassembling process may be carried out in any order:
separating the cathodes from the separators and then separating electrodes from the bus bar posts, or the other way around.
Also, the step of separating the electrodes from the bus bar posts may be carried out between the first and the second steps of the disassembling process.
In some embodiments, the method for disassembling a battery comprises at least one the following additional steps:
In some preferred embodiments, the method for disassembling a battery according to the present disclosure comprises a step consisting in sorting electrodes, bus bar posts, separators, bottom plate, and casing. Optionally, such preferred method also comprises the recycling of the individual cell components.
In one embodiment, the method for disassembling a battery as described above comprises the following steps in the following order:
The cell components including electrodes, separator, casing, bottom plate, bus bar posts, can then be individually recycled.
In one specific embodiment of the present disclosure which is described in
Application of the process described above result is an easy and safe disassembly of electrodes and packaging material and separation of individual cell components without mixing.
Embodiments where tabs are placed at opposite location enable electrical isolation of odd-numbered negative electrodes from even-numbered negative electrode within the cell stack. For example, within the stack, negative electrode #1 is not electrically connected with the negative electrode #2. This makes cell design safer as any short in one electrode pair will not propagate through the stack. Embodiments teach multiple electrical connection schemes. For example, in one embodiment where negative and positive electrode bus bar posts are electrically isolated from the casing, odd number negative electrodes within the stack can be paired to odd number positive electrodes while even numbered negative electrodes within the stack is paired to even numbered positive electrodes. In another example, odd and even positive electrode can be connected to the casing at positive electrode potential and odd and even negative electrodes are separately connected to the casing. The disclosed embodiments provide electrical connection flexibility not available in traditional cell designs while providing high safety.
The disclosed embodiments present several advantages. One additional benefit of the cell and battery assembly describe herein is with respect to the heat transfer. Typically, heat transfer can take place during operation of the battery at the bottom plate and around the bus bar posts. The specific arrangement of the present disclosure provides an effective management of the heat transfer between the cells within a battery pack. As shown in
In a particular embodiment, a unique way to scale cell capacity ranging from 10 Wh to 1000 Wh by increasing either the number of electrodes or by increasing the length of the cell or both is shown in
Many new negative electrode chemistries such as silicon or lithium and/or solid-state battery all require the application of stack pressure to cycle efficiently. For example, during lithiation at the first charge cycle, silicon-based negative electrode expands considerable exerting about 300 kPa to 2800 kPa peak stack pressure on packaging. This peak pressure decreases gradually with subsequent cycling and stack in thickness direction contract. This expansion and contraction of silicon can result in electrodes and/or current collector damage. The disclosed embodiment depicted as
This application claims priority to U.S. Provisional Application No. 63/184,269, filed on May 5, 2021, which is incorporated in its entirety herein for all purposes.
| Number | Date | Country | |
|---|---|---|---|
| 63184269 | May 2021 | US |
