Patent Application
20230054685
The present disclosure relates generally to electrochemical devices. More specifically, aspects of this disclosure relate to stacked electrode designs for cylindrical and prismatic lithium-class battery cells.
Current production motor vehicles, such as the modern-day automobile, are originally equipped with a powertrain that operates to propel the vehicle and power the vehicle's onboard electronics. In automotive applications, for example, the vehicle powertrain is generally typified by a prime mover that delivers driving torque through an automatic or manually shifted power transmission to the vehicle's final drive system (e.g., differential, axle shafts, corner modules, road wheels, etc.). Automobiles have historically been powered by a reciprocating-piston type internal combustion engine (ICE) assembly due to its ready availability and relatively inexpensive cost, light weight, and overall efficiency. Such engines include compression-ignited (CI) diesel engines, spark-ignited (SI) gasoline engines, two, four, and six-stroke architectures, and rotary engines, as some non-limiting examples. Hybrid electric and full electric (collectively “electric-drive”) vehicles, on the other hand, utilize alternative power sources to propel the vehicle and, thus, minimize or eliminate reliance on a fossil-fuel based engine for tractive power.
A full-electric vehicle (FEV)—colloquially labeled an “electric car”—is a type of electric-drive vehicle configuration that altogether omits the internal combustion engine and attendant peripheral components from the powertrain system, relying on a rechargeable energy storage system (RESS) and a traction motor for vehicle propulsion. The engine assembly, fuel supply system, and exhaust system of an ICE-based vehicle are replaced with a single or multiple traction motors, a traction battery pack, and battery cooling and charging hardware in a battery-based FEV. Hybrid electric vehicle (HEV) powertrains, in contrast, employ multiple sources of tractive power to propel the vehicle, most commonly operating an internal combustion engine assembly in conjunction with a battery-powered or fuel-cell-powered traction motor. Since hybrid-type, electric-drive vehicles are able to derive their power from sources other than the engine, HEV engines may be turned off, in whole or in part, while the vehicle is propelled by the electric motor(s).
Many commercially available hybrid electric and full electric vehicles employ a rechargeable traction battery pack to store and supply the requisite power for operating the powertrain's traction motor unit(s). In order to generate tractive power with sufficient vehicle range and speed, a traction battery pack is significantly larger, more powerful, and higher in capacity (Amp-hr) than a standard 12-volt starting, lighting, and ignition (SLI) battery. Contemporary traction battery packs, for example, group stacks of battery cells (e.g., 8-16 cells/stack) into individual battery modules (e.g., 10-40 modules/pack) that are mounted onto the vehicle chassis by a battery pack housing or support tray. Stacked electrochemical battery cells may be connected in series or parallel through use of an electrical interconnect board (ICB) or front-end DC bus bar assembly. A dedicated Electronic Battery Control Module (EBCM), through collaborative operation with a Powertrain Control Module (PCM) and Traction Power Inverter Module (TPIM), regulates the opening and closing of battery pack contactors to govern operation of the battery pack.
There are four primary types of batteries that are used in electric-drive vehicles: lithium-class batteries, nickel-metal hydride batteries, ultracapacitor batteries, and lead-acid batteries. As per lithium-class designs, lithium-metal (primary) batteries and lithium-ion (secondary) batteries make up the bulk of commercial lithium battery (LiB) configurations with Li-ion batteries being employed in automotive applications due to their enhanced stability, energy density, and rechargeable capabilities. A standard lithium-ion cell is generally composed to at least two conductive electrodes, an electrolyte material, and a permeable separator, all of which are enclosed inside an electrically insulated packaging. One electrode serves as a positive (“cathode”) electrode and the other electrode serves as a negative (“anode”) electrode during cell discharge. Rechargeable Li-ion batteries operate by reversibly passing lithium ions back and forth between these negative and positive electrodes. The separator—oftentimes a microporous polymeric membrane—is disposed between the two electrodes to prevent electrical short circuits while also allowing the transport of ionic charge carriers. The electrolyte is suitable for conducting lithium (Li) ions and may be in solid form (e.g., solid state diffusion), liquid form (e.g., liquid phase diffusion), or quasi-solid form (e.g., solid electrolyte entrained within a liquid carrier). Lithium-ions move from the negative electrode to the positive electrode during discharge of the battery while under load, and in the opposite direction when recharging the battery.
Presented herein are stacked electrode designs for electrochemical devices, methods for manufacturing and methods for operating such electrochemical devices, and lithium-class cylindrical and prismatic battery cells with stacked electrode architectures. By way of example, a lithium-metal cylindrical can cell employs a stack of annular anode electrodes interleaved with annular cathode electrodes. Insulation pads may be seated on opposing longitudinal ends of the stack, and the insulated stack packaged inside a protective outer housing (i.e., “cell casing”). The stacked electrodes are nested inside of a current collector cylinder such that the anode electrodes, cathode electrodes, and current collector cylinder are mutually coaxial with and circumscribe a current collector bar. An electrically insulating and ionically conductive separator (e.g., polymeric separator immersed within liquid electrolyte or including a solid electrolyte) may be disposed between each pair of neighboring electrodes.
One set of electrodes (e.g., the cathode electrodes) press-fits onto and thereby electrically connects with the current collector bar via inner-diameter (ID) tabs projecting radially inward from a central hole of the electrodes. Outer-diameter (OD) peripheries of these electrodes may be covered with an electrical insulator or the diameter of these electrodes may be reduced to space the OD edges from the interior of the current collector cylinder. Conversely, the other set of electrodes (e.g., the anode electrodes) press-fits into and thereby electrically connects with the current collector cylinder via OD tabs projecting radially outward from the electrodes. ID edges of these electrodes may be covered with an electrical insulator or the diameter of central hole of these electrodes may be increased to space the ID edges from the exterior of the current collector bar. Moreover, a biasing member, such as a helical compression spring, may be compressed between the stacked electrodes and a housing cap or housing base to maintain the electrodes in compression with one another while inside the housing.
Attendant benefits for at least some of the disclosed concepts include a stacked electrode architecture that enables cylindrical and prismatic battery cells to facially compress the stack of interleaved electrodes, e.g., for lithium-metal anode applications. In addition, laying the electrodes flat against one another in a stack enables prismatic battery cells to increase the number of electrode layers, e.g., as compared to conventional “jelly roll” configurations. Other attendant benefits may include increased heat dissipation characteristics and a reduced electrode geometry that helps to ensure uniform current density, electrode morphology, and mechanical properties. In addition to improved thermal performance and uniform operating parameters, disclosed concepts may help to increase driving range, fuel economy, and pack performance for electric-drive vehicles. Disclosed features also enable an “anodeless” design which incorporates or consists essentially of multiple collectors whereby lithium is supplied by a cathode or cathodes that plate(s) on and strips from an anode collector as a means of ionic transfer.
Aspects of this disclosure are directed to electrochemical devices, such as cylindrical and prismatic battery cells used in the battery modules of vehicular traction battery packs. In an example, an electrochemical device includes two sets of electrodes: multiple first (anode) electrodes, each of which has one or more layers of active (anode) electrode material borne by a respective electrode body; and multiple second (cathode) electrodes, each of which has one or more layers of active (cathode) electrode material, distinct from the first electrodes' active material, borne by a respective electrode body. One or more flexible electrode tabs projects from the body of each electrode. Electrically insulating separators are interleaved between and stacked along a central stack axis with the electrodes to define an electrode stack. A first (negative) current collector fully or partially surrounds the electrode stack. The set of first electrodes electrically connects to the first current collector by interference fitting (i.e., press fitting) the electrode tabs of the first electrodes to a mating surface of the first current collector. Additionally, a second current collector is located inside the first current collector and aligned substantially parallel with the central stack axis. The set of second electrodes electrically connects to the second current collector by interference/press fitting the electrode tabs of the second electrodes to a mating surface of the second current collector.
Additional aspects of this disclosure are directed to lithium-class battery cells with weld-free stacked electrode architectures, rechargeable battery packs employing such lithium-class battery cells, and motor vehicles equipped with such battery packs. As used herein, the terms “vehicle” and “motor vehicle” may be used interchangeably and synonymously to include any relevant vehicle platform, such as passenger vehicles (ICE, REV, FEV, fuel cell, fully and partially autonomous, etc.), commercial vehicles, industrial vehicles, tracked vehicles, off-road and all-terrain vehicles (ATV), motorcycles, farm equipment, watercraft, aircraft, e-bikes, e-scooters, etc. For non-automotive applications, disclosed concepts may be implemented for any logically relevant use, including stand-alone power stations and portable power packs, photovoltaic systems, handheld electronic devices, pumping equipment, machine tools, appliances, etc. While not per se limited, disclosed concepts may be particularly advantageous for use in lithium-metal cylindrical and prismatic can cells.
In an example, a motor vehicle includes a vehicle body with a passenger compartment, multiple road wheels rotatably mounted to the vehicle body (e.g., via wheel corner modules coupled to a unibody chassis or a body-on-frame chassis), and other standard original equipment. For electric-drive vehicle applications, one or more electric traction motors operate alone (e.g., for FEV powertrains) or in conjunction with an internal combustion engine assembly (e.g., for HEV powertrains) to selectively drive one or more of the road wheels to propel the vehicle. A rechargeable traction battery pack is mounted onto the vehicle body and operable to power the traction motor(s).
Continuing with the discussion of the preceding example, the traction battery pack contains multiple lithium-class battery cells. Each battery cell is fabricated with a plurality of first electrodes, each of which has a first active electrode material borne by a substantially flat first body, and a plurality of second electrodes, each of which has a second active electrode material, distinct from the first active electrode material, borne by a substantially flat second body. Multiple flexible electrode tabs project from the body of each first electrode, and multiple flexible electrode tabs project from the body of each second electrode. A set of substantially flat and electrically insulating separators is interleaved between and stacked along a central stack axis with the electrodes to form an electrode stack. A first electrically conductive current collector, which at least partially surrounds the electrode stack, is interference fit with the flexible electrode tabs of the first electrodes. In addition, a second current collector is disposed inside the first current collector and aligned substantially parallel with the central stack axis. The second current collector interference fits with the second electrode tabs of the second electrodes.
Aspects of this disclosure are directed to manufacturing processes, control logic, and computer-readable media (CRM) for making and/or using any of the disclosed electrochemical devices, battery packs, and/or vehicles. In an example, a method is presented for assembling an electrochemical device. This representative method includes, in any order and in any combination with any of the above and below disclosed options and features: receiving a plurality of first electrodes each having a first active electrode material borne by a first body and a flexible first electrode tab projecting from the first body; receiving a plurality of second electrodes each having a second active electrode material, distinct from the first active electrode material, borne by a second body and a flexible second electrode tab projecting from the second body; receiving a plurality of electrically insulating separators; interleaving each of the separators between one of the first electrodes and one of the second electrodes; stacking the first and second electrodes with the interleaved separators along a central stack axis to define an electrode stack; positioning a first current collector at least partially around the electrode stack such that the first electrode tabs interference fit with the first current collector to thereby electrically connect the first electrodes to the first current collector; and positioning a second current collector inside the first current collector and aligned substantially parallel with the central stack axis such that the second electrode tabs interference fit with the second current collector to thereby electrically connect the second electrodes to the second current collector. The above and below-described method steps may be performed manually (e.g., by an operator), may be automated (e.g., by a robotic cell), or a combination of both.
For any of the disclosed devices, vehicles, and methods, the electrode bodies of the first and second electrodes may each have a substantially flat annular shape. As a further option, the electrode bodies have respective central holes that are coaxially aligned on the central stack axis to define a stack cavity, which extends through of the center of the electrode stack. In this instance, the second current collector includes an elongated, electrically conductive bar that extends axially through the central stack cavity. Each tab of each second electrode may include multiple electrode tabs that project radially inward from an inner-diameter edge of its electrode body, circumferentially spaced around the electrode body, and bent against an outer surface of the electrically conductive bar. The electrode body of each second electrode may have an outer-diameter edge with a layer of electrical insulation, e.g., to prevent electrical contact with the first current collector.
For any of the disclosed devices, vehicles, and methods, the first current collector may include an electrically conductive cylinder that is concentric with and surrounds the electrode stack. In this instance, each electrode tab of each first electrode may include multiple electrode tabs that projecting radially outward from an outer-diameter periphery of its electrode body, circumferentially spaced around the electrode body, and bent against an inner surface of the electrically conductive cylinder. The electrode body of each first electrode may have an inner-diameter edge with a layer of electrical insulation, e.g., to prevent electrical contact with the second current collector. The separators may be ring-shaped, porous polymeric sheets.
For any of the disclosed devices, vehicles, and methods, the electrochemical device may also include a rigid outer housing that securely contains therein the electrode stack and the two current collectors. The outer housing may be a two-piece construction with a main housing and a housing cap that closes off an open end of the main housing. An optional biasing member may be compressed between the electrode stack and either the housing cap or the main housing. The biasing member may be sandwiched between a pair of non-conductive plates or metallic plates each coated with a layer of insulation. The housing cap may be fabricated with one or more passive or active gas vents.
For any of the disclosed devices, vehicles, and methods, the electrode bodies of the first electrodes may each have a substantially flat first polygonal shape with a first size (e.g., a rectangle with an enlarged plan-view area), and the electrode bodies of the second electrodes may each have a substantially flat second polygonal shape with a second size that is distinct from the first size (e.g., a rectangle with a reduced plan-view area). In this example, the second current collector may include an electrically conductive plate that extends longitudinally along a lateral side of the electrode stack, abutting the second electrodes, and spaced relation to the first electrodes. In addition, the first current collector includes an electrically conductive cylinder coaxial with and surrounding the first and second electrodes. It is also envisioned that the first current collector may include another electrically conductive plate that extends longitudinally along another lateral side of the electrode stack, opposite that of the second current collector's electrically conductive plate. In this instance, the first current collector's electrically conductive plate abuts the first electrodes and is spaced from the second electrodes.
The above summary does not represent every embodiment or every aspect of this disclosure. Rather, the above features and advantages, and other features and attendant advantages of this disclosure, will be readily apparent from the following detailed description of illustrative examples and modes for carrying out the present disclosure when taken in connection with the accompanying drawings and the appended claims. Moreover, this disclosure expressly includes any and all combinations and subcombinations of the elements and features described above and below.
Representative embodiments of this disclosure are shown by way of non-limiting example in the drawings and are described in additional detail below. It should be understood, however, that the novel aspects of this disclosure are not limited to the particular forms illustrated in the above-enumerated drawings. Rather, the disclosure is to cover all modifications, equivalents, combinations, subcombinations, permutations, groupings, and alternatives falling within the scope of this disclosure as encompassed, for instance, by the appended claims.
This disclosure is susceptible of embodiment in many different forms. Representative examples of the disclosure are shown in the drawings and herein described in detail with the understanding that these embodiments are provided as an exemplification of the disclosed principles, not limitations of the broad aspects of the disclosure. To that end, elements and limitations that are described, for example, in the Abstract, Introduction, Summary, Description of the Drawings, and Detailed Description sections, but not explicitly set forth in the claims, should not be incorporated into the claims, singly or collectively, by implication, inference, or otherwise. Moreover, the drawings discussed herein may not be to scale and are provided purely for instructional purposes. Thus, the specific and relative dimensions shown in the Figures are not to be construed as limiting.
For purposes of the present detailed description, unless specifically disclaimed: the singular includes the plural and vice versa; the words “and” and “or” shall be both conjunctive and disjunctive; the words “any” and “all” shall both mean “any and all”; and the words “including,” “containing,” “comprising,” “having,” and permutations thereof, shall each mean “including without limitation.” Moreover, words of approximation, such as “about,” “almost,” “substantially,” “generally,” “approximately,” and the like, may each be used herein in the sense of “at, near, or nearly at,” or “within 0-5% of,” or “within acceptable manufacturing tolerances,” or any logical combination thereof, for example. Lastly, directional adjectives and adverbs, such as fore, aft, inboard, outboard, starboard, port, vertical, horizontal, upward, downward, front, back, left, right, etc., may be with respect to a motor vehicle, such as a forward driving direction of a motor vehicle, when the vehicle is operatively oriented on a horizontal driving surface.
Referring now to the drawings, wherein like reference numbers refer to like features throughout the several views, there is shown in
The representative vehicle powertrain system is shown in
To propel the hybrid vehicle 10 of
The ICE assembly 12 operates to propel the vehicle 10 independently of the electric traction motor 14, e.g., in an “engine-only” operating mode, or in cooperation with the motor 14, e.g., in “vehicle-launch” or “motor-boost” operating modes. In the example depicted in
Power transmission 16 may use differential gearing 24 to achieve selectively variable torque and speed ratios between transmission input and output shafts 17 and 19, respectively. One form of differential gearing is the epicyclic planetary gear arrangement, which offers the advantage of compactness and different torque and speed ratios among members of the planetary gearing. Traditionally, hydraulically actuated torque establishing devices, such as clutches and brakes, are selectively engageable to activate the aforementioned gear elements for establishing desired forward and reverse speed ratios between the transmission's input and output shafts 17, 19. While envisioned as a 6-speed or 8-speed automatic transmission, the power transmission 16 may optionally take on other functionally appropriate configurations, including Continuously Variable Transmission (CVT) architectures, automated-manual transmissions, etc.
Hydrodynamic torque converter assembly 18 of
Presented in
With continuing reference to
Disposed inside the battery housing 120 between the two electrodes 122, 124 is a porous separator 126, which may be in the nature of a microporous or nanoporous polymeric separator. The porous separator 126 may include a non-aqueous fluid electrolyte composition and/or solid electrolyte composition, collectively designated 130, which may also be present in the negative electrode 122 and the positive electrode 124. A negative electrode current collector 132 may be positioned on or near the negative electrode 122, and a positive electrode current collector 134 may be positioned on or near the positive electrode 124. The negative electrode current collector 132 and positive electrode current collector 134 respectively collect and move free electrons to and from an external circuit 140. An interruptible external circuit 140 with a load 142 connects to the negative electrode 122, through its respective current collector 132 and electrode tab 136, and to the positive electrode 124, through its respective current collector 134 and electrode tab 138. Separator 126 may be a sheet-like structure that is composed of a porous polyolefin membrane, e.g., with a porosity of about 35% to 65% and a thickness of approximately 25-30 microns. Electrically non-conductive ceramic particles (e.g., silica) may be coated onto the porous membrane surfaces of the separators 126.
The porous separator 126 may operate as both an electrical insulator and a mechanical support structure by being sandwiched between the two electrodes 122, 124 to prevent the electrodes from physically contacting each other and, thus, the occurrence of a short circuit. In addition to providing a physical barrier between the electrodes 122, 124, the porous separator 126 may provide a minimal resistance path for internal passage of lithium ions (and related anions) during cycling of the lithium ions to facilitate functioning of the battery 110. For some optional configurations, the porous separator 126 may be a microporous polymeric separator including a polyolefin. The polyolefin may be a homopolymer, which is derived from a single monomer constituent, or a heteropolymer, which is derived from more than one monomer constituent, and may be either linear or branched. In a solid-state battery, the role of the separator may be partially/fully provided by a solid electrolyte layer.
Operating as a rechargeable energy storage system (RESS), battery 110 generates electric current that is transmitted to one or more loads 142 operatively connected to the external circuit 140. While the load 142 may be any number of electrically powered devices, a few non-limiting examples of power-consuming load devices include an electric motor for a hybrid electric vehicle or an all-electric vehicle, a laptop computer or tablet computer, a cellular smartphone, cordless power tools and appliances, portable power stations, etc. The battery 110 may include a variety of other components that, while not depicted herein for simplicity and brevity, are nonetheless readily available. For instance, the battery 110 may include one or more gaskets, terminal caps, tabs, battery terminals, and other commercially available components or materials that may be situated on or in the battery 110. Moreover, the size and shape and operating characteristics of the battery 110 may vary depending on the particular application for which it is designed.
Discussed below are stacked electrode architectures for improved thermal performance and uniform operating characteristics of electrochemical devices, such as cylindrical and prismatic battery cell formats. By way of non-limiting example, a cylindrical battery cell may employ a stack of ring-shaped or partial ring-shape electrodes that is interleaved with ring-shaped or partial ring-shaped separators. Inner-diameter edges of the cathode electrodes connect to a positive current collector packaged at the center of the cell stack, whereas outer-diameter edges of the anode electrodes connect to a negative current collector that envelops the electrode stack or is interposed between the stack and a cell casing. Alternatively, the anode electrodes may connect to a negative current collector at the center of the cell stack, whereas the cathode electrodes may connect to a positive current collector that is adjacent to or surrounds the electrode stack.
Each electrode is connected to one of the current collectors through an interference-fit mating between the current collector and the electrode's electrically conductive tabs, which are press fit onto and thereby folded against the current collector. Other weld-less interface options may include snap-fitting or key-fitting the electrodes to their designated current collectors. The cathode and anode electrode tabs may be fabricated by preforming a designated number of slits (e.g., 3-50 slits spaced around an inner edge of the electrode, or 3-100 slits spaced around an outer edge of the electrode) to enable tab folding. These slits may align with the radius of the ring-shaped electrodes or may have an angular offset from the radius. The ring-shaped electrodes may be prepared by cutting each electrode during roll-to-roll coating and processing, rotation (spin) coating, printing, scrap material recycling, etc. The stacked-electrode cylindrical cell format may be assembled using, for example, a controller-automated robotic assembly process to ensure proper stack alignment, electrode connection, and stack compression. Disclosed concepts may be applied to both cylindrical battery cells, such as those illustrated in
To electrically isolate the anode electrodes from the positive current collector and the cathode electrodes from the negative current collector, a layer of dielectric material or other electrically insulating material may be applied to the non-interfacing edge of each electrode (i.e., the edge that does not electrically connect to the designated current collector). Electrical isolation may also be achieved with a reduced outer diameter for the ring-shaped cathode (or anode) electrodes to prevent contact with the negative (positive) current collector, and an enlarged inner diameter for the anode (or cathode) electrodes to prevent contact with the positive (negative) current collector. While a weld-less tab-to-collector interface may be desired for ease of assembly and reduced manufacturing time and costs, mating edges of the cathode and anode electrodes may optionally be welded to their designated current collectors.
Cell assembly may include pre-laminating separator sheets onto the axial faces of the cathode electrodes, the axial faces of the anode electrodes, or select surfaces of both such that at least one separator is disposed between each neighboring pair of cathode and anode electrodes. After lamination of the separator sheets, the cathode electrodes and anode electrodes are then fed, in alternating fashion, onto a support mold that operatively aligns the electrodes to form an electrode stack. The electrode stack is then pressed into engagement with the anode and cathode current collectors via a pneumatic piston or other suitable press mechanism. Alternatively, the anode and cathode current collectors may be pressed into engagement with the electrode stack while the stack is held stationary. In either case, the electrodes are interference fit with the current collectors by press-fitting and folding the radially projecting electrode tabs onto the collectors. One or more or all of the disclosed manufacturing operations may be automated, e.g., using a robotic assembly to move and operatively position a temporary stack casing and a central collector with respect to the stacked electrodes with interleaved separators. After pressing the electrode stack into the temporary casing and onto the central collector, the stack-collector-casing subassembly is transferred for mating with a cell casing (or outer collector) and insulation layer(s). This new subassembly is then mated with a cell cap, spring plate, and spring subassembly, e.g., in a manner that ensures the stack is held in compression.
Each electrode may be stacked with an in-plane rotation of a predefined offset angle with respect to the placement of the immediately preceding electrode. For instance, a designated origin point of a first electrode may be located at 0 degree from a calibrated start coordinate. A second electrode is stacked on top of the first electrode; the designated origin point of the second electrode may be located at 1 to 60 degrees from the calibrated start coordinate. This process is repeated for each additional electrode when forming the stack. The cylindrical cell may employ a pneumatic vent or a re-sealable vent with a spring-loaded valve to allow for evacuation of gas that has been generated in the cell. The cylindrical cell may employ a spring or other suitable biasing member to provide continuous compression on the stack.
Turning next to
For “anodeless” electrochemical device designs—with no anodes in their initial state—one or more negative electrodes function as a current collector while lithium from one or more cathode electrodes are plated on and stripped from the negative current collector(s). Put another way, lithium ions may be extracted from the cathode(s) and electrodeposited as metallic lithium onto one or more current collectors during the initial charging process. During a subsequent discharging process, lithium ions may be stripped from the current collector and intercalated back into the cathode. Eliminating lithium metal at the anode side of the as-assembled batteries or fully discharged batteries reduces concerns stemming from the presence of large amounts of lithium metal in the cell.
A substantially flat, ring-shaped separator 226 is sandwiched between each adjacent pair of electrodes 222, 224, as best seen in the inset view of
Surrounding the stack 230 of electrodes 222, 224 and interleaved separator sheets 226 is a first lithium-ion (anode) current collector 232 that helps to pass electric current between complementary working electrodes. In accord with the illustrated example, the first current collector 232 may consist essentially of a rigid metallic cylinder, e.g., that is formed of stainless steel, aluminum, nickel, or copper. With this configuration, the current collector 232 is concentrically aligned with and encases therein the first and second electrodes 222, 224. This electrically conductive cylinder may be a single-piece construction with a hollow, right-circular cylinder geometry having an open proximal end 241 that is longitudinally spaced from a closed distal end 243. The current collector 232 may function in a manner similar to the negative electrode current collector 132 described above in the discussion of
In this example, the first current collector 232 may function as the device's 210 protective outer housing for isolating and safeguarding the electrode stack 230. An optional housing cap 236 may rigidly mount to and closes off the open proximal end 241 of the current collector 232. This housing cap 236 helps to secure the electrode stack 230 and other internal hardware of the electrochemical device 210 inside the current collector 232. To retain the electrode stack 230 under compression after assembly of the electrochemical device 210, a biasing member 238 applies pressure to one end of the stack 230. Although portrayed as a helical compression spring, biasing member 238 of
Anode electrodes 222 mechanically interface with the anode current collector 232 through a folding-tab interference fit in order to electrically connect the current collector 232 to its corresponding set of electrodes 222. With reference again to
Packaged inside the first current collector 232 is a second lithium-ion permeable (cathode) current collector 234 that is aligned substantially parallel with the central axis A1-A1 of the electrode stack 230. In accord with the illustrated example, the second current collector 234 may consist essentially of a rigid metallic bar, e.g., that is formed of stainless steel, aluminum, nickel, or copper. This electrically conductive bar may be a single-piece construction with an elongated and solid, right-circular cylinder geometry that is secured within a central stack cavity 247 that extends through the center of the electrode stack 230. With this configuration, the current collector 234 is coaxially aligned with and seats inside the electrode stack 230. The current collector 234 may function in a manner similar to the positive electrode current collector 134 described above in the discussion of
Cathode electrodes 224 mechanically interface with the cathode current collector 234 through a folding-tab interference fit in order to electrically connect the current collector 234 to its corresponding set of electrodes 224. The inner diameter D3 of the cathode electrodes 224 is smaller than the outer diameter D4 of the cathode current collector 234. Additionally, each of the inwardly projecting electrode tabs 235 is sufficiently flexible such that pressing the electrode stack 230 onto the current collector 234 and/or pressing the collector 234 into the central through-holes 237 defining the stack cavity 247 along a central stack axis A1-A1 causes the tabs 235 to bend against a proximal end of the collector 234. Once bent, the tabs 235 slide along and press against an exterior surface of the current collector 234 to thereby electrically connect the electrodes 224 to the collector 234. To obviate the chances of a short circuit, the layer of electrical insulation 229 on the inner perimeter of the first (anode) electrodes 222 helps to electrically isolate the electrodes 222 from the current collector 234.
With reference next to
Manufacturing system/process 250 of
Once the separators are received and operatively attached to the electrodes, manufacturing system/process 250 advances to a third manufacturing step or station S3 and stacks the electrodes with the interleaved separators. Manufacturing step/station S3 may include feeding the electrodes, one at a time and in an alternating fashion (anode, cathode, anode, cathode . . . ), onto a support mold 252 to assemble an electrode stack 230. A central locating pin 254 may be provided to axially align the electrodes and separators during stacking. The inner walls of the support mold 252 and/or the locating pin 254 may be lubricated to facilitate stacking of the electrodes. The support mold 252 may be seated on a stationary base plate 256, as shown in Step S3, or on a pneumatic, hydraulic, or motor-driven piston (“base presser”) 258, as shown in Step S4.
Manufacturing system/process 250 of
Turning next to
A substantially flat, rectangular separator 326 is sandwiched between each adjacent pair of electrodes 322, 324, as best seen in
Seated adjacent a first face of the electrode stack 330 (left side in
Aspects of this disclosure may be implemented, in some embodiments, through a computer-executable program of instructions, such as program modules, generally referred to as software applications or application programs executed by any of a controller or the controller variations described herein. Software may include, in non-limiting examples, routines, programs, objects, components, and data structures that perform particular tasks or implement particular data types. The software may form an interface to allow a computer to react according to a source of input. The software may also cooperate with other code segments to initiate a variety of tasks in response to data received in conjunction with the source of the received data. The software may be stored on any of a variety of memory media, such as CD-ROM, magnetic disk, and semiconductor memory (e.g., various types of RAM or ROM).
Moreover, aspects of the present disclosure may be practiced with a variety of computer-system and computer-network configurations, including multiprocessor systems, microprocessor-based or programmable-consumer electronics, minicomputers, mainframe computers, and the like. In addition, aspects of the present disclosure may be practiced in distributed-computing environments where tasks are performed by resident and remote-processing devices that are linked through a communications network. In a distributed-computing environment, program modules may be located in both local and remote computer-storage media including memory storage devices. Aspects of the present disclosure may therefore be implemented in connection with various hardware, software, or a combination thereof, in a computer system or other processing system.
Any of the methods described herein may include machine readable instructions for execution by: (a) a processor, (b) a controller, and/or (c) any other suitable processing device. Any algorithm, software, control logic, protocol or method disclosed herein may be embodied as software stored on a tangible medium such as, for example, a flash memory, a solid-state drive (SSD) memory, a hard-disk drive (HDD) memory, a CD-ROM, a digital versatile disk (DVD), or other memory devices. The entire algorithm, control logic, protocol, or method, and/or parts thereof, may alternatively be executed by a device other than a controller and/or embodied in firmware or dedicated hardware in an available manner (e.g., implemented by an application specific integrated circuit (ASIC), a programmable logic device (PLD), a field programmable logic device (FPLD), discrete logic, etc.). Further, although specific algorithms may be described with reference to flowcharts and/or workflow diagrams depicted herein, many other methods for implementing the example machine-readable instructions may alternatively be used.
Aspects of the present disclosure have been described in detail with reference to the illustrated embodiments; those skilled in the art will recognize, however, that many modifications may be made thereto without departing from the scope of the present disclosure. The present disclosure is not limited to the precise construction and compositions disclosed herein; any and all modifications, changes, and variations apparent from the foregoing descriptions are within the scope of the disclosure as defined by the appended claims. Moreover, the present concepts expressly include any and all combinations and subcombinations of the preceding elements and features.
