Electrochemical device with multifunctional electrode separator arrangement with built-in reference electrodes

Abstract

This paper presents electrochemical devices with stacked reference electrodes, methods for manufacturing / using such devices, and battery cells with stacked electrodes separated by electrode separator assemblies with integrated reference electrodes. An electrochemical device comprises a protective outer casing containing an ion-conducting electrolyte. A stack of working electrodes is located within the device casing in electrochemical contact with the electrolyte. At least one electrode separator assembly is situated within the casing between an adjacent pair of these working electrodes. The electrode separator assembly includes an electrically insulating separator plate with a reference electrode. A tab pocket projecting from one end of the separator plate contains a tab chamber with a chamber opening.An electrode tab is made of an electrically conductive material and attached to the tab pocket. One end of the electrode tab is positioned inside the tab chamber, and the other end protrudes from the chamber opening.

Description

introduction

[0001] The present disclosure generally relates to electrochemical devices. More specifically, aspects of this disclosure relate to stacked electrode assemblies with reference electrodes integrated into the stack for lithium-class battery cells.

[0002] Today's production vehicles, such as the modern automobile, are originally equipped with a powertrain that propels the vehicle and supplies the vehicle's on-board electronics. In motor vehicles, for example, the powertrain typically consists of a prime mover that transfers drive torque to the vehicle's final drive (e.g., differential, axle shafts, cam modules, wheels, and so on) via an automatic or manual transmission. In the past, motor vehicles were powered by reciprocating internal combustion engines (ICE) because they were readily available, relatively inexpensive, lightweight, and highly efficient. These engines include compression-ignition (CI) diesel engines, spark-ignition (SI) gasoline engines, two-, four-, and six-stroke engines, and rotary engines, to name just a few.Hybrid electric and fully electric vehicles (collectively referred to as “electric propulsion vehicles”), on the other hand, use alternative energy sources to power the vehicle, thus minimizing or eliminating dependence on a fossil fuel-based engine for traction power.

[0003] A fully electric vehicle (FEV)—also colloquially referred to as an "electric car"—is an electric-powered vehicle configuration that completely eliminates the internal combustion engine and its peripheral powertrain components, using a rechargeable energy storage system (RESS) and a traction motor for vehicle propulsion. The engine assembly, fuel supply, and exhaust system of an internal combustion engine vehicle are replaced in a battery-assisted FEV by one or more traction motors, a traction battery pack, and battery cooling and charging technology. Hybrid electric vehicle (HEV) powertrains, on the other hand, utilize multiple types of motive power to propel the vehicle, typically using an internal combustion engine in conjunction with a battery- or fuel-cell-powered traction motor.Because electric vehicles are capable of obtaining their energy from sources other than the engine, HEV engines can be fully or partially shut down while the vehicle is powered by the electric motor(s).

[0004] High-voltage electrical systems regulate the power transfer between the traction motors and the rechargeable battery packs that provide the energy required to operate many hybrid-electric and all-electric powertrains. To provide the power capacity and energy density required to propel a vehicle at the desired speed over the desired range, modern traction battery packs group multiple battery cells (e.g., 8-16+ cells / group) into individual battery modules (e.g., 10-40+ modules / pack), which are electrically connected in series or parallel and mounted on the vehicle chassis via a battery pack enclosure or carrier.On the battery side of the high-voltage network, a DC-DC converter is electrically connected to the traction batteries to boost the voltage supply to a main DC bus and a power inverter module (PIM). A high-frequency, large-capacity capacitor can be placed between the positive and negative rails of the main DC bus to ensure electrical stability and store additional electrical energy. A dedicated electronic battery control module (EBCM), in conjunction with a powertrain control module (PCM) and the power electronics of each motor, controls the operation of the battery pack(s) and traction motor(s).

[0005] There are four main types of batteries used in electric vehicles: lithium-class batteries, nickel-metal hydride batteries, ultracapacitor batteries, and lead-acid batteries. As with lithium batteries, lithium metal and lithium-ion (secondary) batteries make up the majority of commercially available lithium battery (LiB) configurations, with lithium-ion (Li-ion) variants finding widespread use in automotive applications due to their improved stability, high energy density, and fast-charging capabilities. A standard Li-ion cell generally consists of at least two conductive electrodes, an electrolyte material, and a permeable separator, all enclosed in an electrically insulated package. One electrode serves as the positive ("cathode") electrode, and the other electrode serves as the negative ("anode") electrode during cell discharge.The separator—often a microporous polymer membrane—is placed between the two electrodes to prevent electrical short circuits while allowing the transport of ionic charge carriers. The electrolyte is suitable for conducting lithium ions and can be in solid form (e.g., solid-state diffusion), liquid form (e.g., liquid-phase diffusion), or quasi-solid form (e.g., solid electrolyte in a liquid carrier). Rechargeable lithium-ion batteries operate by reversibly transferring lithium ions between these working electrodes. Description

[0006] Electrochemical devices with stacked reference electrodes, methods for fabricating and operating such devices, and lithium battery cells with stacked working electrodes separated by electrode separator assemblies with built-in reference electrodes are presented. For example, a pouch-type lithium-ion battery cell contains an electrode stack with a sequence of first (anode) working electrodes interleaved with an equal number of second (cathode) working electrodes. Between each pair of adjacent electrodes, an electrically insulating and ionically conductive separator is arranged. This separator can be in the form of a polymeric separator plate immersed in a liquid electrolyte or bonded to a solid electrolyte.The nested electrodes and separator plates can be stacked and housed in a protective bag, rolled in jelly and housed in a cylindrical container, or rolled flat and housed in a prismatic container. A reference electrode can be baked into the separator plate or otherwise integrally connected to it.

[0007] One or more of these electrode separator plates can be manufactured as a multifunctional separator assembly with an electrically conductive reference electrode tab extending from a tab pocket extending longitudinally from one end of the separator plate. The tab pocket can comprise a reduced-width tab panel formed coplanar and integral with the main body of the separator plate. Extending transversely from one side of the tab panel is an integrated tab flap that folds against the tab panel to form a compartment in which the reference electrode tab is securely mounted. The functional attachment of the reference electrode tab to the separator plate can comprise cleaning and roughening a first (proximal) end of the tab; an electrically conductive adhesive is applied to both sides of the proximal end of the tab.One side of the flap is aligned with the flap panel and pressed into place; the flap flap is then folded against the opposite side of the flap and glued to it. After application, at least approximately 50% of the flap protrudes from the flap pocket, with the proximal end of the flap spaced from the longitudinal end of the separator plate.

[0008] Accompanying benefits of at least some of the disclosed concepts include functional separator assemblies that enable in-stack measurement of electrode electrical properties while ensuring electrical and thermal isolation of adjacent working electrodes. By measuring electrode electrical properties using in-stack reference electrodes, the disclosed concepts aid in the detection of potential battery failures and optimized control of battery operation. The disclosed separators also help reduce packaging space and the complexity of manufacturing reference electrodes and their conductive tabs. In addition to improved monitoring and operation of battery cells, the disclosed concepts can help increase battery range, fuel consumption, and performance for electric vehicles.

[0009] Aspects of this disclosure relate to electrochemical devices, such as cylindrical, pouch-like, and prismatic LiB cells used, for example, in the battery modules of vehicle traction batteries. In one example, an electrochemical device is constructed with an insulated and sealed housing for storing therein an electrolyte composition chemically configured to conduct ions. An electrode stack, located within the device housing in electrochemical contact with the electrolyte, includes one or more first working electrodes (e.g., anodes) interleaved with one or more second working electrodes (e.g., cathodes). At least one electrode separator assembly is located within the device housing and is disposed between and physically separated from an adjacent pair of working electrodes.Each electrode separator assembly includes a separator plate formed entirely or partially from an electrically insulating material. The separator plate includes a reference electrode. A tab pocket extending from one end of the separator plate defines a tab chamber with a chamber opening. An electrically conductive reference electrode tab is attached to the tab pocket and electrically connected to the reference electrode. One end of the reference electrode tab is disposed within the tab chamber, and the other end of the electrode tab protrudes from the chamber opening.

[0010] Further aspects of this disclosure relate to lithium battery cells having stacked electrode assemblies with in-stack sensor capabilities, rechargeable battery packs employing such lithium 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, HEV, FEV, fuel cell, fully and semi-autonomous vehicles, and so on), commercial vehicles, industrial vehicles, tracked vehicles, off-highway and all-terrain vehicles (ATVs), motorcycles, agricultural equipment, e-bikes, e-scooters, personal watercraft, aircraft, and so on.For non-automotive applications, the disclosed concepts may be implemented for any logically relevant use, including stand-alone power plants and portable power units, photovoltaic systems, portable electronic devices, pumping systems, machine tools, appliances, and so on. Although not limited per se, the disclosed concepts may be particularly advantageous for use in cylindrical, pouch-type, and prismatic lithium metal cells (secondary cells).

[0011] In one example, a motor vehicle includes a vehicle body with a passenger compartment, a plurality of drive wheels rotatably mounted to the vehicle body (for example, via corner modules coupled to a unibody or body-on-frame chassis), and other standard equipment. In electric-powered vehicles, one or more electric traction motors operate alone (for example, in FEV powertrains) or in conjunction with an internal combustion engine (for example, in HEV powertrains) to selectively drive one or more wheels and propel the vehicle. A rechargeable traction battery pack is mounted on the vehicle body and can supply power to the traction motor(s).

[0012] As described in the previous example, the traction battery contains several lithium-class battery cells, for example, stacked in one or more battery modules and / or arranged in a battery pack housing. Each battery cell is equipped with a protective battery housing containing a liquid, solid, or quasi-solid electrolyte composition for ion conduction. Inside the battery housing is an electrode stack in electrochemical contact with the electrolyte. The electrode stack comprises a series of first (anode) working electrodes interleaved with a corresponding number of second (cathode) working electrodes. Also inside the battery housing is an electrode separator assembly disposed between each pair of working electrodes.The electrode separator assembly comprises a separator plate formed wholly or partially from an electrically insulating material, and a tab pocket connected to and extending from a longitudinal end of the separator plate. A reference electrode is carried by the separator plate. The tab pocket contains an inner tab chamber with a chamber opening at one end. A reference electrode tab is fixedly attached, for example, via an electrically conductive adhesive, to the tab pocket and formed wholly or partially from an electrically conductive material. The reference electrode tab has a first (proximal) end disposed within the tab chamber and a second (distal) end opposite the first end and extending from the chamber opening.

[0013] Aspects of this disclosure also relate to manufacturing methods, control logic, and computer-readable media (CRM) for making and / or using the disclosed electrochemical devices, battery packs, and / or vehicles. In one example, a method of assembling an electrochemical device is presented. This representative method comprises, in any order and in any combination with any of the options and features disclosed above and below: receiving a device housing of the electrochemical device; disposing an electrolyte within the device housing, the electrolyte configured to conduct ions; disposing an electrode stack within the device housing in electrochemical contact with the electrolyte, the electrode stack comprising first and second working electrodes;and disposing an electrode separator assembly between the first and second working electrodes, the electrode separator assembly comprising: a separator plate formed from an electrically insulating material and containing a reference electrode; a tab pocket extending from one end of the separator plate and defining a tab chamber having a chamber opening; and an electrode tab attached to the tab pocket and formed from an electrically conductive material, the electrode tab having a first end disposed within the tab chamber and a second end extending from the chamber opening.

[0014] In all of the disclosed vehicles, methods, and devices, the tab pocket may include a tab panel that extends from and is coplanar with the separator plate. In this case, the separator plate may have a (first) blade width and height, while the tab panel may have a (second) field width and height that are less than the blade width and height, respectively. The tab pocket may also include a tab flap that extends from one side of the tab panel; the tab flap may be pressed against and firmly attached to the tab panel to jointly define the tab chamber therebetween. In this case, the tab flap may have a (third) height that is less than the height of the separator plate and the height of the tab panel.To simplify design and manufacturing, it may be desirable for the separator plate and the tab pocket, including the tab flap and the tab panel, to be integrally molded from the electrically insulating material as a single, one-piece structure. Another possibility is for the separator plate, the tab flap, and the tab panel to each have a specific polyhedral shape (e.g., a square or rectangular polyhedron) with a specific size (e.g., total surface area).

[0015] In all of the disclosed vehicles, methods, and devices, the reference electrode tab may be firmly attached to the tab pocket via an electrically conductive adhesive. As a further option, the reference electrode tab may comprise a substantially flat, rectangular tab body, one (first) side of which has a (first) surface facing the panel, which is provided with a non-smooth surface texture. On the opposite side of the tab body, there is another (second) side with a (second) surface facing the flap, which may also be provided with a non-smooth surface texture. In this case, the electrically conductive adhesive may be located on one or both of the surfaces of the tab body having the non-smooth surface texture.In this case, the non-smooth surface texture may include depressions, ridges, cross-hatched grooves, sinusoidal grooves, horizontal grooves and / or oblique grooves.

[0016] In all disclosed vehicles, methods, and devices, the reference electrode tab may be made entirely or partially of gold, gold-plated plastic, aluminum, nickel, copper, copper-plated aluminum, stainless steel, and so on. As a further option, the electrically conductive adhesive may be an air-, heat-, and / or UV-cured adhesive, may include a filler material, a conductive additive material, and / or a binder material, and may have an epoxy base, an acrylate base, and / or a silicone base. Optionally, the reference electrode tab may have an elongated tab body, with at least 50% of the tab body protruding from the chamber opening. It may be desirable for the proximal (first) end of the reference electrode tab, disposed within the tab chamber, to be spaced from the end of the separator plate from which the tab pocket protrudes.

[0017] The above summary does not represent every embodiment or aspect of the present disclosure. Rather, the above summary merely provides an overview of some of the novel concepts and features set forth herein. The above features and advantages, as well as other features and associated advantages of this disclosure, will be readily apparent from the following detailed description of illustrated examples and representative modes for carrying out the disclosure when considered in conjunction with the accompanying drawings and the appended claims. Furthermore, this disclosure expressly includes all combinations and subcombinations of the elements and features set forth above and below. Brief description of the drawings Fig. 1 is a partially schematic side view of a representative motor vehicle powered by an electrified powertrain having a motor-generator unit powered by a traction battery pack including battery cells with in-stack reference electrodes in accordance with aspects of the present disclosure. Fig. 2 is a schematic representation of a representative electrochemical device with which aspects of the present disclosure may be practiced. Fig. 3 is a plan view of a representative multifunctional electrode separator assembly with a built-in reference electrode for an electrode stack of an electrochemical device according to aspects of the present disclosure. Fig. 4 is a flow diagram illustrating a representative method for manufacturing an electrode separator assembly with a built-in reference electrode in accordance with aspects of the present disclosure.

[0018] The present disclosure is susceptible to various modifications and alternative forms, and some representative embodiments of the disclosure are illustrated by way of example in the drawings and will be described in detail herein. It should be understood, however, that the novel aspects of this disclosure are not limited to the particular forms illustrated in the drawings enumerated above. Rather, this disclosure encompasses all modifications, equivalents, combinations, permutations, groupings, and alternatives falling within the scope of this disclosure, such as those encompassed by the appended claims. Detailed description

[0019] This disclosure may be embodied in many different forms. Representative embodiments of the disclosure are illustrated in the drawings and are described in detail herein, with the understanding that these embodiments serve as examples of the disclosed principles and not as limitations on the general aspects of the disclosure. As such, elements and limitations described, for example, in the "Summary," "Introduction," "Summary," "Description of the Drawings," and "Detailed Description" sections, but not expressly recited in the claims, should not be incorporated into the claims, individually or in the aggregate, by implication, inference, or otherwise.Furthermore, the reference to "first", "second", "third", and so on in the description or claims is not intended to impose a serial or numerical limitation; unless expressly stated otherwise, these designations may be used to facilitate reference to similar features in the description and drawings and to distinguish between similar elements in the claims.

[0020] For the purposes of this Detailed Description, unless expressly excluded: the singular includes the plural and vice versa; the words "and" and "or" are both conjunctive and disjunctive; the words "each" and "all" mean "each and all"; and the words "including," "including," "comprising," "with," and the like each mean "including without limitation." In addition, words of approximation such as "approximately," "nearly," "substantially," "generally," "about," and the like may be used herein to mean, for example, "at, near, or nearly at," or "within 0-5% of," or "within acceptable manufacturing tolerances," or any logical combination thereof.Finally, directional adjectives and adverbials such as "front", "rear", "inside", "outside", "starboard", "port", "vertical", "horizontal", "up", "down", "forward", "backward", "left", "right" and so on may refer to a motor vehicle, for example, to the forward direction of travel of a motor vehicle when the vehicle is operated on a horizontal driving surface.

[0021] With reference to the drawings, in which like reference numbers refer to like features in the several views, Fig. 1, a representative motor vehicle is illustrated, generally designated 10, and shown here for discussion purposes as an electric sedan. The illustrated motor vehicle 10—also referred to herein for short as a “motor vehicle” or “vehicle”—is merely an exemplary application with which novel aspects of this disclosure may be practiced. Likewise, the incorporation of the present concepts into an FEV powertrain should be understood as a non-limiting implementation of the disclosed features. It should be understood that aspects and features of this disclosure may be applied to other electrochemical device form factors, may be incorporated into any logically relevant type of motor vehicle, and may be utilized for both automotive and non-automotive applications. Furthermore, only selected components of the motor vehicles and battery assemblies are shown and described in detail herein.Nonetheless, the vehicles and assemblies discussed below may include numerous additional and alternative features and other available peripheral components to perform the various methods and functions of this disclosure.

[0022] The representative vehicle 10 of Fig. 1 is originally equipped with a central telecommunications and information unit 14 (“telematics”) that communicates wirelessly, for example via cell towers, satellite services, and so on, with a remote cloud computing host service 24 (for example, ONSTAR®). Other in Fig. 1 include, as non-limiting examples, an electronic video display device 18, a microphone 28, audio speakers 30, and various user input controls 32 (e.g., buttons, knobs, switches, touchscreens, and so on). These hardware components 16 function as a human-machine interface (HMI), allowing the user to communicate with the telematics unit 14 and other components located both within and remote from the vehicle 10. For example, the microphone 28 allows occupants to input verbal commands. Conversely, the speakers 30 provide audible output to the vehicle occupants and may be either a standalone speaker designed for use with the telematics unit 14 or may be part of an audio system 22.The audio system 22 is operatively connected to a network connection interface 34 and an audio bus 20 to receive analog information and reproduce it as sound through one or more speaker components.

[0023] The network connection interface 34 is communicatively coupled to the telematics unit 14. Suitable examples include twisted pair / fiber optic Ethernet switches, parallel / serial communication buses, local area network (LAN) interfaces, controller area network (CAN) interfaces, and the like. The network connection interface 34 enables the vehicle hardware 16 to send and receive signals with each other and with systems and subsystems both onboard and external to the vehicle body 12. This enables the vehicle 10 to perform various vehicle functions, such as modulating driveline power, activating a vehicle braking system, controlling the vehicle steering, regulating the charging and discharging of the vehicle batteries, and other automated functions.For example, the telematics unit 14 may receive and transmit signals from / to a powertrain control module (PCM) 52, an onboard charging module (OBCM) 54, an electronic battery control module (EBCM) 56, a steering control module (SCM) 58, a braking system control module (BSCM) 60, and various other vehicle ECUs.

[0024] With further reference to Fig. 1, the telematics unit 14 is an in-vehicle computing device that provides a mix of services both individually and through its communication with other networked devices. This telematics unit 14 generally consists of one or more processors 40, each of which may be embodied as a discrete microprocessor, an application-specific integrated circuit (ASIC), or a dedicated control module. The vehicle 10 may provide centralized vehicle control via a central processing unit (CPU) 36 operatively coupled to an integrated circuit (RTC) real-time clock 42 and one or more electronic storage devices 38, each of which may take the form of a CD-ROM, solid-state drive (SSD), hard disk drive (HDD), semiconductor memory, and so on.

[0025] Long-range communication (LRC) with devices outside the vehicle may be provided via a cellular communication component, a navigation and positioning component (e.g., GPS transceiver), or a wireless modem, all shown collectively at 44. Short-range communication (SRC) may be provided via a short-range wireless communication device 46 (e.g., a Bluetooth® unit), a dedicated short-range communication (DSRC) component 48, and / or a dual antenna 50. It should be understood that the vehicle 10 may be implemented without one or more of the components listed above or may optionally include additional components and features desired for a particular end application.The communication devices described above may provide data exchange as part of a periodic broadcast in a vehicle-to-vehicle (V2V) or vehicle-to-general (V2X) communication system.

[0026] The CPU 36 receives sensor data from one or more sensing devices using, for example, photodetection, radar, laser, ultrasound, optics, infrared, or other suitable technologies, including short-range communication technologies (for example, DSRC) or ultra-wide-band (UWB) radio technologies, for example, to perform automated vehicle operation or a vehicle navigation service. According to the illustrated example, the motor vehicle 10 may be equipped with one or more digital cameras 62, one or more range sensors 64, one or more vehicle speed sensors 66, one or more vehicle dynamics sensors 68, and the necessary filtering, classification, fusion, and analysis hardware and software for processing raw sensor data.The type, placement, number, and interoperability of the distributed array of vehicle sensors can be tailored individually or collectively to a specific vehicle platform to achieve a desired level of autonomous vehicle operation.

[0027] To drive the motor vehicle 10, an electrified drive train is capable of generating a traction torque and transmitting it to one or more of the drive wheels 26 of the vehicle. The drive train is Fig. 1 by an electric traction motor 78 connected to a rechargeable energy storage system (RESS), which may be in the form of a chassis-mounted traction battery pack 70. The battery pack 70 may include one or more battery modules 72, each housing a group of electrochemical battery cells 74, for example, lithium-ion or lithium polymer battery cells of the pouch, can, or prismatic type. One or more electrical machines, such as a multi-phase permanent magnet motor / generator (M) unit 78, receive electrical energy from, and optionally supply electrical energy to, the battery pack 70. A high-voltage electrical system including a power inverter module (PIM) 80 electrically connects the battery pack 70 to the motor / generator unit(s) 78 and modulates the transfer of electrical power between these units.The battery pack 70 can be configured so that the functions for module management, cell sensing, and module-to-host communication are integrated directly into each module 72 and are carried out wirelessly via a wireless cell monitoring unit (CMU) 76.

[0028] In Fig. 2, an exemplary electrochemical device in the form of a rechargeable lithium battery 110 is shown that can drive a desired electrical load, such as the motor 78 of Fig. 1. The battery 110 includes a series of electrically conductive electrodes, namely a first (negative or anode) working electrode 122 and a second (positive or cathode) working electrode 124, stacked and packaged within an outer protective casing 120. Referring to either working electrode 122, 124 as an "anode" or "cathode," or as "positive" or "negative," does not imply that the electrodes 122, 124 are limited to a particular polarity, as the system polarity may change depending on whether the battery 110 is operating in a charge or discharge mode. In at least some configurations, the cell casing 120 (or "cell case") may take a can-like cylindrical construction, a sleeve-like pouch construction, or a box-like prismatic construction constructed of aluminum, nickel-plated steel, ABS, PVC, or other suitable material or composite.The surfaces of a metallic cell casing can be coated with a polymer to insulate the metal from the internal cell elements and from neighboring cells. Although . Fig. 2 shows a single galvanic mono-cell unit enclosed within the cell housing 120, the housing 120 may also accommodate a stack or roll of mono-cell units (e.g., five to 500 cells or more).

[0029] The anode electrode 122 may be fabricated with an active anode electrode material capable of accepting lithium ions during a battery charging process and releasing lithium ions during a battery discharging process. In at least some embodiments, the anode electrode 122 is fabricated in whole or in part from a lithium metal, such as lithium aluminum (LiAl) alloy materials with a Li / Al atomic ratio (as indicated by an atomic percentage (at.%) of an atomic species relative to a total number of atoms) in a range of 0 at.%≤Li / Al<70 at.%, and / or aluminum alloys with an Al atomic ratio >50 at.% (e.g., lithium metal is molten).Other examples of suitable active anode electrode materials are carbonaceous materials (e.g., graphite, hard carbon, soft carbon, etc.), silicon, silicon-carbon mixed materials (silicon-graphite composite), Li4Ti5O. 12 , transition metals (alloy types, for example Sn), metal oxides / sulfides (for example SnO2, FeS and the like) and so on

[0030] With further reference to Fig. 2, the cathode electrode 124 can be fabricated with an active cathode electrode material capable of supplying lithium ions during a battery charging process and accepting lithium ions during a battery discharging process. The cathode material 124 can include, for example, lithium transition metal oxide, phosphate (including olivine), or silicate, such as LiMO2 (M=Co, Ni, Mn, or combinations thereof), LiM2O4 (M=Mn, Ti, or combinations thereof), LiMPO4 (M=Fe, Mn, Co, or combinations thereof), and LiMxM'2-xO4 (M, M'=Mn, or Ni). Other non-limiting examples of suitable active cathode electrode materials include lithium nickel cobalt manganese oxide (NCM), lithium nickel cobalt aluminum oxide (NCA), lithium nickel cobalt manganese aluminum oxide (NCMA), and other lithium transition metal oxides.

[0031] Inside the battery cell housing 120 of Fig. 2, and between each paired pair of working electrodes 122, 124, an electrically insulating porous separator 126 is arranged. The porous separator 126 may be in the form of an electrically non-conductive, ion-transporting microporous or nanoporous polymeric separator plate. The separator 126 may be a film-like structure consisting of a porous polyolefin membrane, for example, with a porosity of about 35% to about 65% and a thickness of about 10-30 micrometers. Electrically non-conductive ceramic particles (for example, silicon dioxide) may be applied to the porous membrane surfaces of the separators 126. The porous separator 126 may contain a non-aqueous liquid electrolyte composition, a solid electrolyte composition, and / or a quasi-solid electrolyte composition, which are collectively designated 130 and may also be present in the negative electrode 122 and the positive electrode 124.

[0032] A negative electrode current collector 132 of the electrochemical battery cell 110 may be disposed on or near the negative electrode 122, and a positive electrode current collector 134 may be disposed on or near the positive electrode 124. The negative electrode current collector 132 and the positive electrode current collector 134 each collect and transport free electrons to and from an external circuit 140. An interruptible external circuit 140 having a load 142 is connected to the negative electrode 122 via its respective current collector 132 and electrode tab 136, and to the positive electrode 124 via its respective current collector 134 and electrode tab 138.

[0033] The porous separator 126 can act as both an electrical insulator and a mechanical support structure by being inserted between the two electrodes 122, 124 to prevent the electrodes from coming into physical contact with each other and thus causing a short circuit. In addition to providing a physical barrier between the electrodes 122, 124, the separator 126 can provide a minimal resistance path for the internal passage of lithium ions (and related anions) during cycling of the lithium ions to facilitate the function of the battery 110. In some configurations, the porous separator 126 can be a microporous polymeric separator containing a polyolefin. The polyolefin can be a homopolymer consisting of a single monomer component or a heteropolymer consisting of more than one monomer component and can be either linear or branched.In a solid-state battery, the role of the separator can be partially / completely taken over by a solid electrolyte layer.

[0034] When operating as a rechargeable energy storage system, battery 110 generates electrical power that is transferred to one or more loads 142 connected to external circuit 140. Load 142 may be any number of electrical devices. Some non-limiting examples of power-consuming and power-generating devices include electric motors for hybrid electric vehicles and all-electric vehicles, photovoltaic cell arrays, stand-alone power plants and portable generators, server systems, wind turbines, and so on. Battery 110 may include a variety of other components not illustrated here for simplicity and brevity, but which are nevertheless readily available.For example, the battery 110 may include one or more seals, terminal caps, tabs, battery posts, cooling and charging devices, and other commercially available components or materials that may be located on or within the battery 110. Furthermore, the size and shape, as well as the operating characteristics, of the battery 110 may vary depending on the particular application for which it is designed.

[0035] Introduced here are multifunctional electrode separator assemblies with robust and compatible reference electrode terminals that enable current flow through the separator plate for measuring and controlling the working electrode potential. The separator assembly utilizes a folded, sandwich-like tab pocket with an electrically conductive adhesive to securely attach and operatively connect a reference electrode tab to the separator plate. This space-saving tab connection solution utilizes a tab pocket made of a flexible substrate with a plate integrally formed with and extending longitudinally from the top of the separator plate.A foldable tab structure protrudes transversely from one lateral side of this tab sheet. The tab is folded transversely and glued to the tab sheet to create a pocket with a double-sided bonding area, significantly increasing the fatigue strength and fracture toughness of the shell. In addition to preventing peel failure, this tab pocket design can also increase (for example, double) the contact area between the reference electrode tab and the separator plate to resist shear fractures.

[0036] Simplified and efficient manufacturing processes for the production of multifunctional separators with built-in reference electrodes are also presented here. In one example, a manufacturing process for assembling a multifunctional electrode separator may begin with punching, cutting, or forming an electrically conductive workpiece from a metal blank or sheet metal stock roll, followed by a surface preparation process to roughen the bottom 40–65% of the front and back surfaces of the workpiece. After applying the aforementioned surface texture, the workpiece can be cleaned and, if desired, undergo further pre-processing steps. At this time, a conductive adhesive is applied to the textured areas of the front and back surfaces of the workpiece, which can be done by masking, smearing with a knife, and / or air blowing.The textured and coated workpiece is then pressed against the plate or the flap portion of the flap pocket protruding from the separator plate. The flap is simultaneously folded onto the flap sheet to firmly attach the electrode flap to the separator plate and form the flap pocket, which encloses at least the lower half of the electrode flap.

[0037] As mentioned above, the separator plate can be manufactured as a unitary, one-piece microporous or nanoporous structure formed from an electrically non-conductive, ion-transporting material such as a polyolefin (e.g., polyethylene (PE), polypropylene (PP), or a blend of PE and PP), or it can be a multilayer structure, such as laminated porous films of PE and / or PP. The tab material can include, but is not limited to, gold (Au), gold-plated plastic, aluminum (Al), nickel (Ni), copper (Cu), copper-plated aluminum, stainless steel, and so on.In contrast, the conductive adhesive material can include, but is by no means limited to, an air-cured conductive adhesive, a heat-cured conductive adhesive, a UV-cured conductive adhesive, which may contain an electrode bonding material, a conductive additive, and / or a mixture of conductive particles and epoxy, among others. The separators presented can help reduce the footprint of the electrode tab, which in turn reduces the overall size and weight of the electrochemical device. Other benefits include reducing manufacturing complexity and processing time for the fabrication / use of multifunctional separator assemblies.

[0038] In Fig. 3 illustrates another non-limiting example of an electrochemical device, illustrated as a rechargeable battery assembly 210 for storing and delivering high voltage electrical energy, for example, for powering an electrically powered vehicle, such as the FEV vehicle 10 of Fig. 1. This battery assembly 210 may be part of a deep-cycle, high-amperage vehicle battery system, for example, rated for approximately 350 to 1200 high-voltage direct current (HVDC) or more, depending on the desired vehicle range, the overall vehicle weight, and the power ratings of the various accessory loads that draw electrical energy from the RESS. Although they differ in appearance, it is conceivable that all of the features and options described above with respect to the battery pack 70 of Fig. 1 and the lithium battery cell 110 from Fig. 2, individually or in any combination into the battery assembly 210 of Fig. 3 and Fig. 4 can be integrated and vice versa.

[0039] As a representative point of similarity with the battery pack 70 of Fig. 1 and the battery 110 of Fig. 2, the battery assembly 210 of Fig. 3 may comprise a liquid-tight, electrically insulated battery assembly housing 220 (also referred to as a "device housing") for storing an electrolyte material 212 chemically configured to conduct ions (for example, lithium hexafluorophosphate (LiPF6) in an organic solution). Also inside the device housing 220, in electrochemical contact with the electrolyte 212, is an electrode stack 214 consisting of one or more (first) working electrodes 222 nested with one or more (second) working electrodes 224 and arranged side by side. While in Fig. 3 shows a single pair of working electrodes, each electrochemical device may contain multiple pairs of electrodes (e.g. 10-20 or more) stacked and connected in parallel or in series to store and deliver electrical energy.

[0040] An electrode separator assembly 250 is inserted between the two adjacent electrodes 222, 224, which is also arranged within the device housing 220 in electrochemical contact with the electrolyte 212. In device configurations with multiple paired pairs of electrodes of opposite polarity, a corresponding electrode separator assembly 250 can be inserted between one, some, or all of the paired pairs. According to the illustrated example, the electrode separator assembly 250 can essentially comprise, or, if desired, consist of, a separator plate 230, a tab pocket 252 protruding from an upper end of the separator plate 230, and a reference electrode tab 254 (also referred to herein as an "electrode tab") fixedly attached to the tab pocket 252. The separator plate 230 of the Fig. 3 and Fig. 4 may be similar or identical to the porous separator 126 of the Fig. 2 and thus have all the corresponding features and options thereof, including the fact that it is formed wholly or partly from an electrically insulating but porous material.

[0041] In contrast to separator 126 of Fig. 2, the separator plate 230 can be Fig. 3 and Fig. 4 may contain a reference electrode. As shown, the reference electrode may be carried by the separator plate 230 or otherwise integrated with it (and is therefore not identified by a separate reference number). For example, a dried, electrically conductive electrode material may be pressed onto a surface of the sheet 230 and then baked to form a reference electrode. The reference electrode may be made entirely or partially of an electrically conductive material in a similar manner to the two working electrodes 122, 124 of Fig. 2; however, the reference electrode tab 254 may differ in shape, size, and function from the working electrodes 122, 124.

[0042] With continued reference to the representative electrochemical device of Fig. 3, the tab pocket 252 may be manufactured with an "L-shaped" construction prior to assembly, characterized by a tab panel 256 extending longitudinally from and coplanar with the separator plate 230, and a tab flap 258 coplanar with a lateral (right) side of the tab panel 256 and extending transversely therefrom. After assembly, the tab pocket 252 may have an "I-shaped" construction, with the tab flap 258 folded transversely over the tab panel 256, pressed against it, and firmly attached thereto to jointly define a tab chamber 251 therebetween, as shown in the inspection view of Fig. 3. It may be desirable for both the upper and lower ends of the tab chamber 251 to have corresponding chamber openings 253 and 255 (as shown); alternatively, only the upper end of the chamber 251 may have a corresponding opening 253. To facilitate manufacture and assembly, it may be desirable for the separator plate 230 and the tab pocket 252, including the tab panel 256 and the tab flap 258, to be integrally molded from the same electrically insulating material as a unitary, one-piece structure.

[0043] According to the example shown, the separator plate 230, the tab panel 256, and the tab flap 258 may each have a polyhedral shape with a corresponding size. As a non-limiting example, the sheet 230, the plate 256, and the flap 258 may each be a rectangular polyhedron (prism) with a specific width-to-height ratio and a specific total surface area on the opposite major faces. As shown, the separator plate 230 has a (first) sheet width W S1 and a (first) leaf height H S1 , while the tab plate 256 has a (second) plate width W P2 which is less than the blade width W S1 , and a (second) plate height H P2 which is less than the blade height H S1 , In comparison, the flap has a (third) flap width W F3 and a flap height H F3 ; the flap width W F3 is smaller than the sheet width WS1 and can be approximately equal to or smaller than the panel width W P2 be ; and the flap height H F3 is smaller than the arch height H S1 and can be less than or approximately equal to the panel height H P2 It should be noted that the plate 230, the panel 256, and the flap 258 may take on other regular and irregular shapes and, if desired, may have different individual and relative dimensions than those shown in the drawings.

[0044] The reference electrode tab 254 is in the Fig. 3 and Fig. 4 directly to the tab pocket 252 and indirectly via the tab pocket 252 to the separator plate 230. A lower (first) end portion of the reference electrode tab 254 may be fixedly secured within the tab chamber 251, while an upper (second) end portion of the reference electrode tab 254 may protrude through the opening 253 in the upper end of the tab chamber 251. Optionally, a proximal tip at the lower end of the reference electrode tab 254 may be exposed through the opening 255 in the lower end of the tab chamber 251. According to the illustrated example, the reference electrode tab 254 comprises an elongated, rectangular tab body that may protrude at least 50% from the chamber opening 253. Alternatively, 55%-75% of the rectangular tab body may be disposed within the tab chamber 251 to ensure secure attachment between the reference electrode tab 254 and the tab pocket 252.As a further option, the lower (first) end of the reference electrode tab 254, which is arranged in the tab chamber 251, can be arranged at a predefined distance (for example, approximately 2 mm to 10 mm distance) from the upper end of the separator plate 230, for example, to ensure that the electrode tab 254 does not impede the ion flow through the foil 230. Furthermore, the lower end of the tab body can assume other geometries, for example, an enlarged rectangle or a circle, to increase the contact area between the electrode tab 254 and the pocket 252.

[0045] To ensure a secure connection between the electrode tab 254 and the pocket 252, the reference electrode tab 254 may be firmly bonded to the tab pocket 252 via an electrically conductive adhesive 260. The conductive adhesive layers 260 may take any of the options described herein, including air-cured, heat-cured, and UV-cured conductive adhesives, conductive additives containing an electrode bonding material, and conductive additives with a mixture of conductive particles encapsulated in epoxy. The inspection view of Fig. For example, Figure 3 shows the reference electrode tab 254 having a pair of opposing (first / front and second / back) sides; the front side has a lower (first / front) surface and the back side has a lower (second / back) surface, both located within the tab pocket 252. One or both of these surfaces may be machined or shaped to have a non-smooth surface texture 261. The electrically conductive adhesive 260 may be applied to the reference electrode tab 254 so that it is located on and substantially covers the surface texture 261 on the front and / or back surfaces. The surface texture 261 may receive any suitable surface texture treatment that enhances adhesion with the electrically conductive adhesive 260, such as dimples, ridges, cross-hatched grooves, sinusoidal grooves, horizontal grooves, and / or oblique grooves.Surface texture can be generated at two levels: a surface profile level and a roughness level. At the profile level, texturing can consist of linear grooves, crosshatches, depressions, and so on in the submillimeter range. At the roughness level, texturing can have an average roughness height (Ra) of at least 0.5 micrometers (µm) and a developed interface ratio (Sdr) of at least 50%.

[0046] Once assembled, the electrode separator assembly 250 can be inserted between the two working electrodes 222, 224; the separator plate 230 can physically separate the three electrodes 222, 224, 254 (anode, cathode, and reference electrodes). By mounting the reference electrode tab 254 on the tab pocket 252—a flexible surface extension of the non-conductive separator plate 230—the substrate of the separator plate 230 can also serve as electrical insulation for the reference electrode tab 254. The reference electrode tab 254 has a predefined "stable" potential and can therefore be paired with one of the working electrodes 222, 224 to measure the voltage across the paired electrodes (e.g., cathode / reference or anode / reference). In this way, a battery system controller is able to measure an absolute potential of the paired electrodes based on the predefined potential of the reference electrode tab 254.It is intended that the disclosed multifunctional separators are not limited to reference electrodes and can also be applied to other electrodes.

[0047] Fig. Figure 4 shows a workflow diagram illustrating a representative method 300 for manufacturing electrode separator assemblies with built-in reference electrodes. Some or all of the steps described in Fig. 4 and described in more detail below may represent an algorithm corresponding to non-transitory, processor-executable instructions stored, for example, in main, auxiliary, or remote memory and executed, for example, by an electronic control unit, processing unit, dedicated control module, logic circuit, or other module or device, or network of modules / devices, to perform any or all of the functions described above and below related to the disclosed concepts. It should be recognized that the order of execution of the illustrated blocks of operations may be changed, that additional blocks of operations may be added, and that some of the operations described herein may be modified, combined, or eliminated.Although aspects of the present disclosure are discussed in the context of a rectangular separator plate and electrode tab, those skilled in the art will recognize that the present disclosure is applicable to workpieces of any size, shape, and cross-section.

[0048] The method 300 may begin with processor-executable instructions executed by a programmable controller or control module, or a similarly suitable processor, to invoke an initialization procedure for a closed-loop control sequence to perform the various illustrated operations. The initial stages of the manufacturing process may include acquiring, accessing, fabricating, and / or utilizing (collectively, "providing") the various materials, tools, and machines needed to manufacture the electrode separator assembly. Additional control commands, tolerances, and parameters may be entered at this time before a desired assembly operation begins.After completing all necessary preparatory work, the method 300 proceeds to a first process step (1) in which an electrically conductive workpiece 254A is punched, cut, or otherwise manufactured from a metal blank, a sheet metal stock roll, or a metal-coated plastic substrate.

[0049] Thereafter, the method 300 proceeds to a second process step (2) to apply a non-smooth surface texture to one or more selected portions of one or more major surfaces of the workpiece 254A to create a textured workpiece 254B. As mentioned above, a lower portion (e.g., about 40-65%) of the front and / or back surfaces of the workpiece 254A may be roughened with ridges, channels, depressed grooves, and so forth. At this time, the textured workpiece 254B may be cleaned and undergo other metal pretreatment processes (e.g., overflow rinsing, polishing, air drying, and so forth). In a third process step (3), the method 300 applies an adhesive to selected portions of the textured and cleaned workpiece 254B to define a coated workpiece 254C.After masking the non-roughened surface(s) of the textured workpiece 254B, for example, with a low-tack pressure-sensitive adhesive (PSA), an electrically conductive adhesive may be applied to the roughened surface(s) of the textured workpiece 254B, for example, by scraping with a knife or by air blowing.

[0050] With further reference to Fig. 4, the method 300 continues with a fourth process step (4) to attach the adhesive-coated workpiece 254C to an electrically insulating, ionically conductive separator plate. As shown, the textured and coated workpiece 254C is pressed against a portion of the tab panel 256 (or a portion of the tab flap 258) of a tab pocket 252 extending coplanarly from one end of a separator plate 230. The workpiece 254C is positioned to establish an electrical connection, for example, via the electrically conductive adhesive, to a reference electrode carried by the separator plate 230. The method 300 then performs a fifth process step (5) to form a tab pocket around the workpiece 254C, thereby operatively securing it to the separator. In Fig.For example, Figure 4 illustrates how the tab flap 258 is folded onto and pressed against the tab panel 256; during this process, the electrically conductive adhesive 260 firmly attaches the electrode tab 254 to the panel 256 and the tab 258 and simultaneously forms the tab pocket 252 enclosing at least the lower half of the electrode tab 254.

[0051] Aspects of the present disclosure have been described in detail with reference to the illustrated embodiments; however, those skilled in the art will recognize 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; all modifications, changes, and variations apparent from the foregoing descriptions are within the scope of the disclosure as defined by the appended claims. Furthermore, the present concepts expressly include all combinations and subcombinations of the foregoing elements and features.

Claims

[1] An electrochemical device comprising: a device housing; an electrolyte located inside the device housing and configured to conduct ions; an electrode stack located inside the device housing and comprising a first and a second working electrode in electrochemical contact with the electrolyte; and an electrode separator assembly disposed between the first and second working electrodes, the electrode separator assembly comprising: a separator plate formed of an electrically insulating material and including a reference electrode; a tab pocket extending from one end of the separator plate and defining a tab chamber having a chamber opening; and an electrode tab attached to the tab pocket and formed of an electrically conductive material, the electrode tab having a first end disposed within the tab chamber and a second end extending from the chamber opening. [2] The electrochemical device of claim 1, wherein the tab pocket comprises a tab panel extending from and coplanar with the separator plate, the separator plate having a first width and a first height, and the tab panel having a second width and a second height less than the first width and the first height, respectively. [3] The electrochemical device of claim 2, wherein the tab pocket further comprises a tab flap projecting from one side of the tab panel, the tab flap being pressed against and fixedly secured to the tab panel to collectively define the tab chamber therebetween. [4] The electrochemical device of claim 3, wherein the tab flap has a third height that is less than the first height of the separator plate and the second height of the tab panel. [5] The electrochemical device of claim 3, wherein the separator plate and the tab pocket, including the tab flap and the tab panel, are integrally formed as a one-piece structure with the electrically insulating material. [6] The electrochemical device according to claim 3, wherein the separator plate, the tab flap and the tab board each have a polyhedral shape with a certain size. [7] The electrochemical device of claim 1, wherein the electrode tab is fixedly attached to the tab pocket via an electrically conductive adhesive. [8] The electrochemical device of claim 7, wherein the electrode tab has a first side with a first surface containing a non-smooth surface texture, wherein the electrically conductive adhesive is located on the first surface having the non-smooth surface texture. [9] The electrochemical device of claim 8, wherein the electrode tab has a second side opposite the first side with a second surface including the non-smooth surface texture, the electrically conductive adhesive further being on the second surface having the non-smooth surface texture. [10] The electrochemical device according to claim 9, wherein the non-smooth surface texture comprises depressions, grooves, cross-hatched grooves, sinusoidal grooves, horizontal grooves and / or oblique grooves.

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