Battery cell separator

Abstract

A separator for a battery cell comprising: a primary layer comprising a porous battery separator material; a thermal stability coating applied to a surface of the main layer to face an anode within the battery cell; at least one of the first edge and the second edge of the primary layer includes an uncoated region in which the thermally stable coating is not applied, and a metal coating applied onto the primary layer within the uncoated region.

Description

Technical Field

[0001] The present invention generally relates to a separator for an electrochemical energy storage device, such as a lithium-ion battery cell, and more particularly to a separator having a thermally stable coating in combination with a metal coating. Background Art

[0002] Contemporary lithium-ion batteries use porous polyolefin separators, which are susceptible to thermal contraction at high temperatures and can cause electrical shorts between the positive and negative electrodes or their respective current collectors. Ceramic coatings on the separators help inhibit direct contact and provide thermal stability. However, separators composed of porous polyolefin and ceramic materials cannot be inspected using non-destructive techniques.

[0003] Therefore, while current separators achieve their intended purpose, there remains a need for a new and improved separator for battery cells that includes a metal coating combined with a ceramic coating to provide thermal stability and that can be inspected using non-destructive techniques (e.g., X-rays). Summary of the Invention

[0004] According to several aspects of the present disclosure, a separator for a battery cell includes a main layer comprising a porous battery separator material, a thermal stability coating applied to a surface of the main layer, the surface of the main layer facing an anode within the battery cell, at least one of a first edge and a second edge of the main layer including an uncoated area to which the thermal stability coating is not applied, and a metal coating applied to the uncoated area of ​​the main layer.

[0005] According to another aspect, the diaphragm further includes a gap between the thermally stable coating and the metal coating.

[0006] According to another aspect, the porous battery separator material is a porous polyolefin comprising one of polyethylene (PE), polypropylene (PP), or a PE / PP blend.

[0007] According to another aspect, the thermally stable coating is one of a ceramic material, a metal oxide / metal hydroxide, or a controlled pore polyamine (PAI) layer.

[0008] According to another aspect, the metal coating is one of a polymer binder having metal particles suspended therein, a metal layer applied to the primary layer by electroless plating, or a metal layer applied to the primary layer by a vapor deposition method.

[0009] According to another aspect, the metal coating comprises one of aluminum, stainless steel, iron, or iron oxide.

[0010] According to another aspect, the diaphragm further comprises an electrically insulating coating applied over the uncoated areas of the primary layer and the metallic coating.

[0011] According to another aspect, the primary layer is approximately ten microns thick, the thermally stable coating is approximately three microns thick, the metal coating is at least ten microns wide, and the gap between the thermally stable layer and the metal coating is at least one micron wide.

[0012] According to several aspects of the present disclosure, a battery cell includes an anode layer, a cathode layer, and a separator positioned between the anode layer and the cathode layer, the separator including a main layer comprising a porous battery separator material, a thermally stable coating applied to a surface of the main layer, the surface of the main layer facing the anode, at least one of a first edge and a second edge of the main layer including an uncoated area, the thermally stable coating not being applied in the uncoated area, and a metal coating applied to the uncoated area on the surface of the main layer facing the anode.

[0013] According to several aspects of the present disclosure, a vehicle includes at least one battery cell suitable for storing electrical energy for the vehicle, the battery cell having an anode layer, a cathode layer, and a separator located between the anode layer and the cathode layer, the separator including a main layer comprising a porous polyolefin, the porous polyolefin including one of polyethylene (PE), polypropylene (PP), or a PE / PP mixture; a thermally stable coating including one of a ceramic material, a metal oxide / metal hydroxide, or a pore-controlled polyamine (PAI) layer, the thermally stable coating applied on the surface of the main layer facing the anode, at least one of the first edge and the second edge of the main layer including an uncoated area, the thermally stable coating not being applied in the uncoated area, and a metal coating applied to the uncoated area on the surface of the main layer facing the anode.

[0014] Further areas of applicability will become apparent from the description provided herein.It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.

[0016] Figure 1 is a schematic diagram of a vehicle having a battery system having at least one battery cell according to an exemplary embodiment of the present disclosure;

[0017] Figure 2 is a schematic cross-sectional view of a battery cell having a separator according to an exemplary embodiment;

[0018] Figure 3 yes Figure 2 The cathode layer, separator and anode layer of the battery cell shown are arranged along Figure 2 A cross-sectional view taken along line 3-3 in FIG.

[0019] Figure 4 yes Figure 3 an enlarged view of the diaphragm of the circled portion marked “4” in FIG; and

[0020] Figure 5 is with Figure 4 A similar enlarged view where the separator includes an electrically insulating coating on an uncoated portion of the primary layer.

[0021] The drawings are not necessarily drawn to scale, and some features may be exaggerated or minimized to show details of particular components. In some cases, well-known components, systems, materials, or methods have not been described in detail to avoid obscuring the present disclosure. Therefore, the specific structural and functional details disclosed herein should not be construed as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to use the present disclosure in various ways. DETAILED DESCRIPTION

[0022] The following description is merely exemplary in nature and is not intended to limit the present disclosure, application or use. In addition, there is no intention to be bound by any express or implied theory proposed in the aforementioned technical field, background technology, summary of the invention or the following specific embodiments. It should be understood that in all the drawings, corresponding reference numerals represent similar or corresponding parts and features. As used herein, the term "module" refers to any hardware, software, firmware, electronic control component, processing logic and / or processor device, alone or in any combination, including but not limited to: application specific integrated circuits (ASICs), electronic circuits, (shared, dedicated or group) processors and memories that execute one or more software or firmware programs, combinational logic circuits and / or other suitable components that provide the functions. Although the drawings shown herein depict examples with certain element arrangements, in actual embodiments, there may be additional intermediate elements, devices, features or components. It should also be understood that the drawings are merely illustrative and may not be drawn to scale.

[0023] As used herein, the term "vehicle" is not limited to automobiles. While this technology is primarily described herein in conjunction with automobiles, it is not limited to automobiles. These concepts can be used in a variety of applications, such as consumer electronics components associated with aircraft, ships, other vehicles, and non-vehicles.

[0024] Lithium-ion batteries and cells typically come in one of three traditional forms: cylindrical, prismatic, and pouch. Each of these battery types offers a range of advantages and disadvantages. The battery type determines many production factors; for example, each battery format can have different temperature distributions and heat transfer patterns.

[0025] Cylindrical batteries consist of sheets of anode, separator, and cathode, with the separator sandwiched in between, rolled, and packaged into a cylindrical can. This type of battery was one of the first to be mass-produced. Cylindrical batteries are well-suited to automated production and offer good mechanical stability. The circular shape of the battery distributes the internal pressure generated by side reactions almost evenly around the circumference of the battery, allowing the battery to withstand higher levels of internal pressure without deforming. However, when cylindrical batteries are combined into battery packs and modules, the circular cross-section of the battery does not fully utilize the available space, so the cylindrical batteries have a lower packaging density. However, thermal management of cylindrical battery packs may be easier because the spatial cavities allow coolant to circulate easily around the batteries within the battery pack.

[0026] Prismatic cells consist of large sheets of anode, cathode, and separator, which are sandwiched, rolled, and pressed into a cubic metal or hard plastic casing. The electrodes can also be assembled by stacking rather than wrapping. Prismatic cells are subject to greater stress on the electrodes and separator near the corners of the container. This can damage the electrode coating and lead to uneven electrolyte distribution. When prismatic cells are combined into battery packs, the box-like shape makes optimal use of the available space. However, this efficient use of space comes at the expense of less efficient thermal management because there is no cavity between the cells as in cylindrical battery cells.

[0027] Pouch cells lack a rigid outer casing, instead using a sealed, flexible foil as the cell container. This packaging reduces weight and makes the cell flexible, allowing it to easily fit within the available space of a given product. However, pouch cells can expand due to gas during charging and discharging. The electrode and separator layers of pouch cells are stacked rather than rolled. For pouch cells, cell and product design must account for cell expansion of up to 8% to 10%. Furthermore, due to their flexible structure, pouch cells require support structures and should not be placed near sharp edges.

[0028] According to an exemplary embodiment of the present disclosure, Figure 1 A vehicle 10 is shown having an associated battery system 11 for storing and supplying electrical energy to the vehicle 10. Generally speaking, the battery system 11 works in conjunction with other systems within the vehicle 10 to provide power to the vehicle's electric propulsion system and / or various systems within the vehicle 10. The vehicle 10 generally includes a chassis 12, a body 14, front wheels 16, and rear wheels 18. The body 14 is disposed on the chassis 12 and substantially encloses the components of the vehicle 10. The body 14 and the chassis 12 may together form a vehicle frame. The front wheels 16 and the rear wheels 18 are each rotatably coupled to the chassis 12 near a respective corner of the body 14.

[0029] In various embodiments, the vehicle 10 is an autonomous vehicle and the system 11 is incorporated into the autonomous vehicle 10. The autonomous vehicle 10 is, for example, a vehicle 10 that is automatically controlled to transport passengers from one location to another. Although the vehicle 10 is depicted as a sedan in the illustrated embodiment, it should be understood that any other vehicle may be used, including motorcycles, trucks, sport utility vehicles (SUVs), recreational vehicles (RVs), etc. In an exemplary embodiment, the vehicle 10 is equipped with a so-called level four or level five automation system. A level four system represents "highly autonomous driving" and refers to a specific driving mode performance of the autonomous driving system in all aspects of dynamic driving tasks, even if the human driver does not respond appropriately to intervention requests. A level five system represents "fully autonomous driving" and refers to the full-time performance of the autonomous driving system in all aspects of dynamic driving tasks under all road and environmental conditions that can be managed by a human driver. The novel aspects of the present disclosure are equally applicable to non-autonomous driving vehicles.

[0030] As shown, vehicle 10 generally includes a propulsion system 20, a transmission system 22, a steering system 24, a braking system 26, a sensor system 28, an actuator system 30, at least one data storage device 32, a vehicle controller 34, and a wireless communication module 36. In embodiments where vehicle 10 is an electric vehicle, the propulsion system may include one or more electric motors connected to and powered by battery system 11, and the transmission system 22 may be absent. In various embodiments, propulsion system 20 may include an internal combustion engine, an electric motor (e.g., a traction motor), and / or a fuel cell propulsion system. Transmission system 22 is configured to transmit power from propulsion system 20 to the front and rear wheels 16, 18 of the vehicle according to selectable speed ratios. According to various embodiments, transmission system 22 may include a stepped automatic transmission, a continuously variable transmission, or other suitable transmission. Braking system 26 is configured to provide braking torque to the front and rear wheels 16, 18 of the vehicle. In various embodiments, braking system 26 may include friction brakes, brake-by-wire brakes, a regenerative braking system (e.g., an electric motor), and / or other suitable braking systems. Steering system 24 influences the position of front and rear wheels 16, 18. Although depicted as including a steering wheel for illustrative purposes, in some embodiments contemplated within the scope of the present disclosure, such as for fully autonomous vehicles, the steering system 24 may not include a steering wheel.

[0031] The sensor system 28 includes one or more sensing devices 40a-40n that sense observable conditions of the external and / or internal environments of the vehicle 10. The sensing devices 40a-40n may include, but are not limited to, radar, lidar, global positioning systems, optical cameras, thermal imagers, ultrasonic sensors, and / or other sensors. In an exemplary embodiment, the plurality of sensing devices 40a-40n includes at least one of a motor speed sensor, a motor torque sensor, an electric drive motor voltage and / or current sensor, an accelerator pedal position sensor, a coolant temperature sensor, a cooling fan speed sensor, and a transmission oil temperature sensor. The actuator system 30 includes one or more actuator devices 42a-42n that control one or more features of the vehicle 10, such as, but not limited to, the propulsion system 20, the transmission system 22, the steering system 24, and the braking system 26.

[0032] The vehicle controller 34 includes at least one processor 44 and a computer-readable storage device or medium 46. The at least one data processor 44 can be any custom or commercially available processor, a central processing unit (CPU), a graphics processing unit (GPU), a secondary processor among multiple processors associated with the vehicle controller 34, a semiconductor-based microprocessor (in the form of a microchip or chipset), a macroprocessor, any combination of the above, or any device generally used to execute instructions. The computer-readable storage device or medium 46 can include volatile and non-volatile storage devices, such as read-only memory (ROM), random access memory (RAM), and keep-alive memory (KAM). KAM is a type of persistent or non-volatile memory that can be used to store various operating variables when the at least one data processor 44 is powered off. The computer-readable storage device or medium 46 can be implemented using any of a variety of known storage devices, such as PROM (programmable read-only memory), EPROM (electrically programmable read-only memory), EEPROM (electrically erasable programmable read-only memory), flash memory, or other electrical, magnetic, optical, or combination storage devices capable of storing data used by the controller 34 in controlling the vehicle 10, some of which represents executable instructions.

[0033] These instructions may include one or more separate programs, each of which includes an ordered list of executable instructions for implementing logical functions. When these instructions are executed by at least one processor 44, the processor receives and processes signals from the sensor system 28, executes logic, calculations, methods and / or algorithms for automatically controlling components of the vehicle 10, and generates control signals to the actuator system 30 based on the logic, calculations, methods and / or algorithms to automatically control components of the vehicle 10. Although Figure 1Only one controller 34 is shown, but embodiments of the vehicle 10 may include any number of controllers 34 that communicate via any suitable communication medium or combination of communication media and collaborate to process sensor signals, execute logic, calculations, methods and / or algorithms, and generate control signals to automatically control features of the vehicle 10.

[0034] The wireless communication module 36 is configured to wirelessly communicate information with other remote entities 48, such as, but not limited to, other vehicles ("V2V" communication), infrastructure ("V2I" communication), remote systems, remote servers, cloud computers, and / or personal devices. In an exemplary embodiment, the communication system 36 is a wireless communication system that is configured to communicate via a wireless local area network (WLAN) using the IEEE 802.11 standard or by using cellular data communications. However, additional or alternative communication methods, such as dedicated short-range communication (DSRC) channels, are also considered within the scope of the present disclosure. A DSRC channel refers to a one-way or two-way short- to medium-range wireless communication channel designed specifically for automotive use, and a corresponding set of protocols and standards.

[0035] The vehicle controller 34 is a non-general purpose electronic control device having a pre-programmed digital computer or processor, memory or non-transitory computer-readable medium, and a transceiver [or input / output port] for storing data such as control logic, software applications, instructions, computer code, data, look-up tables, etc. Computer-readable media includes any type of media that can be accessed by a computer, such as read-only memory (ROM), random access memory (RAM), hard drive, compact disk (CD), digital video disk (DVD), or any other type of memory. "Non-transitory" computer-readable media does not include wired, wireless, optical, or other communication links that transmit temporary electrical or other signals. Non-transitory computer-readable media includes media that can store data permanently and media that can store data and subsequently rewrite it, such as rewritable optical disks or erasable memory devices. Computer code includes any type of program code, including source code, object code, and executable code.

[0036] See also Figure 2 , a battery cell 50 for the battery system 11 includes an anode layer 52, a cathode layer 54, and a separator 56 located between the anode layer 52 and the cathode layer 54. As shown, the battery cell 50 is a cylindrical lithium-ion (LI-ION) battery cell. It should be understood that the novel features of the present disclosure are applicable to any type of battery cell 50 including an anode 52, a cathode 54, and a separator 56 therebetween, as well as non-lithium-ion battery cells.

[0037] See again Figure 2 、 Figure 3 and Figure 4 The separator 56 includes a main layer 58 comprising a porous battery separator material 60. In an exemplary embodiment, the porous battery separator material 60 is a porous polyolefin, which includes one of polyethylene (PE), polypropylene (PP), or a PE / PP blend. The porous main layer 58 is used to contain the electrolyte and prevent physical contact (electron conduction contact) between the anode layer 52 and the cathode layer 54. Multiple battery cells 50 can be arranged in a series or parallel current connection mode, or any suitable combination thereof, to meet the potential and power requirements of the battery system 11.

[0038] The lithium-ion battery cell 50 generally operates by allowing lithium ions to pass reversibly between the negative electrode (anode layer 52) and the positive electrode (cathode layer 54). The main layer 58 of the separator is impregnated with an electrolyte solution suitable for conducting lithium ions back and forth between the anode layer 52 and the cathode layer 54. Each of the anode layer 52 and the cathode layer 54 is also supported on or connected to a metal current collector (the anode layer 52 is typically copper and the cathode layer 54 is typically aluminum). During use of the battery, the current collectors associated with the anode layer 52 and the cathode layer 54 are connected by a controllable and interruptible external circuit that allows an electron current to pass between the anode layer 52 and the cathode layer 54, thereby achieving electrical balance of the relative transport of lithium ions through the battery cell 50. Many different materials can be used to produce these different components of the lithium-ion battery. However, in general, the anode layer 52 typically includes a lithium insertion material or alloy host material, the cathode layer 54 typically includes a lithium-containing active material that can store lithium at a higher potential (relative to a lithium metal reference electrode) than the host material of the anode layer 52, and the electrolyte solution typically includes one or more lithium salts dissolved and ionized in a non-aqueous solvent. The contact of the anode layer 52 and the cathode layer 54 with the electrolyte causes an electric potential to be generated between the anode layer 52 and the cathode layer 54, and when an electron current is utilized in an external circuit between the anode layer 52 and the cathode layer 54, the electric potential is maintained by the electrochemical reaction within the battery cell 50.

[0039] A lithium-ion battery cell 50, or a plurality of lithium-ion battery cells 50 arranged in series or parallel (or any suitable combination thereof) for current flow, can be used to reversibly power an associated load device. The battery system 11 delivers power to a load device such as an electric motor as needed until the lithium content of the anode layer 52 (negative electrode) has been depleted to a predetermined level. The battery cell 50 can then be recharged by passing a suitable direct current in opposite directions between the anode layer 52 and the cathode layer 54.

[0040] At the beginning of discharge, the anode layer 52 contains a high concentration of intercalated lithium, while the cathode layer 54 is relatively deficient. Under these conditions, a closed external circuit established between the anode layer 52 and the cathode layer 54 causes the intercalated lithium to be transported from the anode layer 52. The intercalated lithium is oxidized into lithium ions and electrons. The lithium ions are carried from the anode layer 52 (negative electrode) to the cathode layer 54 (positive electrode) through the ionically conductive electrolyte solution contained in the pores of the porous polyolefin main layer 58 of the separator 56. Simultaneously, the released electrons are transported from the anode layer 52 (negative electrode) to the cathode layer 54 (positive electrode) through the external circuit (via the current collector) to balance the overall reactions occurring in the electrochemical cell 50. The lithium ions are absorbed into the material of the cathode layer 54 through an electrochemical reduction reaction. The flow of electrons through the external circuit can power a load device until the level of intercalated lithium in the anode layer 52 drops below a workable level or until power is no longer required.

[0041] The available capacity of the battery cell 50 can be recharged after partial or complete discharge. To charge or repower the lithium-ion battery cell 50, an external power source is connected to the cathode layer 54 and the anode layer 52 to drive the reverse process of the battery discharge electrochemical reaction. That is, during charging, the lithium in the cathode layer 54 is oxidized to produce lithium cations and electrons. The cations are transported to the anode layer 52 through the separator 56, and the electrons also travel to the anode layer 52 through the external circuit. At the surface of the anode layer 52, the lithium cations are reduced to lithium by combining with the available electrons in the anode layer 52, and the lithium content of the anode layer 52 increases. Overall, the charging process reduces the lithium content in the cathode layer 54 and increases the lithium content in the anode layer 52.

[0042] The separator 56 plays an important role in the battery cell 50. In many lithium-ion battery configurations, the anode layer 52 and the cathode layer 54 form thin, dense, polymer-bound particulate material layers on their respective current collectors (e.g., copper foil or aluminum foil), and each battery 50 is equipped with a thin, porous polyolefin separator 56 interposed between the facing electrode layers. Thus, the pores and surface of the polyolefin main layer 58 of the separator 56 are filled with and contacted by a lithium-ion-containing non-aqueous electrolyte, which contacts and wets the facing anode layer 52 and cathode layer 54, allowing lithium ions and counterions to flow through the pores of the separator 58 and between the anode layer 52 and cathode layer 54. However, the polymer main layer 58 of the separator 56 prevents electrons from flowing directly between the anode layer 52 and cathode layer 54.

[0043] The properties of the separator 56 play an important role in determining the thermal response of the battery cell 50 during an abuse event. Commercially state-of-the-art polyolefin-based separators 56 are typically composed of polyethylene (PE), polypropylene (PP), or a blend of PE and PP. While PE- and PP-based materials have excellent mechanical properties, they are susceptible to thermal failure due to their relatively low transition temperatures (135°C for PE and 165°C for PP). Additionally, polyolefin-based materials typically exhibit poor wetting properties with the carbonate-based electrolytes used in lithium-ion batteries 50. Layering of PP and PE can exploit the difference in melting points between PP and PE, with PE acting as a shutdown layer and PP protecting structural integrity. Unfortunately, this protection is only effective below the melting point of PP.

[0044] The separator 56 of the present disclosure also includes a thermally stable coating 62 applied to a surface 64 of the main layer 58, the surface 64 of the main layer 58 facing the anode layer 52. In exemplary embodiments, the thermally stable coating 62 comprises a thin layer of a ceramic material such as silica or alumina, or a thin layer of a metal oxide or metal hydroxide such as boehmite. In a non-limiting example, the surface of the main layer 58 is coated with polymer-bound particles of such a ceramic material or metal oxide. The thermally stable coating 62 increases the strength of the separator 56, improves the dimensional stability of the separator 56 at high temperatures (above which polymers such as PE or PP would exist in a molten state), and enhances the electrolyte retention capacity of the main layer 58 of the separator 56. In another exemplary embodiment, the thermally stable coating comprises a controlled pore polyamine (PAI). The PAI is applied to the main layer 58 using phase transfer and gravure printing methods. The PAI provides a controlled pore structure with varying pore sizes. For example, the pore size can vary between 0.02 microns, 0.17 microns, and 0.85 microns. The thermally stable coating 62 made of PAI provides the advantages of "Guest-Host Transition", in which PAI undergoes a reversible transformation, enhancing thermal stability; and provides the advantages of "Pore On / Off", in which ion transport through the membrane can be selectively turned on or off by using PAI to block the pores in the PE main layer 58.

[0045] See again Figure 2, the battery cell 50 includes a plurality of alternating anode layers 52, separators 56, and cathode layers 54 wrapped into a cylindrical shape. As shown, the battery cell 50 includes a first end 66, the first end 66 including a positive electrode cap 68 electrically connected to a positive electrode tab 70, which is connected to a single cathode layer 54 (or multiple cathode layers 54). The battery cell 50 also includes a second end 72, the second end 72 including a negative electrode cap 74 electrically connected to a negative electrode tab 76, which is connected to a single anode layer 52 (or multiple anode layers 52). The main layer 58 of the separator 56 includes a first edge 78 and a second edge 80, the first edge 78 extending circumferentially around the cylindrical battery cell 50 adjacent to the first end 66 of the battery cell 50, and the second edge 80 extending circumferentially around the cylindrical battery cell 50 adjacent to the second end 72. In an exemplary embodiment, at least one of the first edge 78 and the second edge 80 of the main layer 58 of the separator 56 includes an uncoated area 82, in which the thermal stability coating 62 is not applied. The battery cell 50 may include an uncoated region 64 adjacent one or both of the first edge 78 and the second edge 80 .

[0046] During manufacturing, there is a risk that the first edge 78 and the second edge 80 of the separator 56 may be damaged by collision with other objects, etc. Therefore, for quality control reasons, during mass production, it is desirable to test the completed battery cells 50 to ensure that the first edge 78 and the second edge 80 are not damaged. Due to the polymer and ceramic / metal oxide nature of the main layer 58 and the thermal stability coating 62, non-destructive testing methods such as X-ray inspection are not feasible. Therefore, random periodic disassembly (destructive testing) is usually carried out to determine by visual inspection whether the manufactured battery cells 50 have damaged / defective separators 56. This involves the loss of the disassembled battery cells 50 and does not allow 100% inspection of the manufactured battery cells 50.

[0047] To allow for inspection of each battery cell 50 using non-destructive techniques (X-ray inspection), in the exemplary embodiment, the separator 56 includes a metal coating 84 applied to the uncoated area 82 on the surface 64 of the main layer 58 that faces the anode layer 52. Figure 4 In the exemplary embodiment, width 86 of metallic coating 84 is at least ten microns, and diaphragm 56 includes a gap 96 between metallic coating 84 and thermally stable coating 62 having a width 88 of at least one micron. Thus, minimum width 90 of uncoated region 82 is at least eleven microns.

[0048] The metal coating 84 can be any metal material that can be detected using an X-ray method. In an exemplary embodiment, the metal coating 84 includes one of aluminum or stainless steel. Due to its electrochemical stability, aluminum is typically the metal material used in the metal coating 84, however, compared to other metal materials, aluminum tends to exhibit a weaker response when using an X-ray method. When aluminum is used, aluminum image processing techniques and algorithms can be used to improve the responsiveness of aluminum in X-ray images. Metal coatings comprising iron (Fe) or iron oxide (FeO2) materials provide the best visibility using the X-ray method and do not negatively affect the performance of the battery cell 50. Unlike aluminum, iron-based metal oxides are stable at the anode potential within the lithium-ion battery cell 50.

[0049] The metal coating 84 can be applied to the surface 64 of the main layer 58 facing the anode layer 52 by any known method or process. In an exemplary embodiment, the metal coating 84 includes metal particles or powder suspended in a matrix or binder of a polymer material. During application, the polymer material is a liquid slurry and the metal particles / powder are mixed into the slurry together with a surfactant and a rheology modifier. The slurry containing the metal particles / powder and other components is then applied to the surface 64 of the main layer 58 facing the anode layer 52 using wet coating and solvent drying techniques. This application method reduces the occurrence of metal contamination, and the metal coating 84 can be prepared and applied simultaneously with the thermal stability coating 62. However, in other embodiments, the metal coating 84 can be applied to the surface 64 of the main layer 58 facing the anode layer 52 using an electroless plating method or a vacuum deposition method, as non-limiting examples, the vacuum deposition method is, for example, a physical vapor deposition (PVD) method or a chemical vapor deposition (CVD) method.

[0050] Electron beam physical vapor deposition (EB-PVD) and physical vapor deposition technologies such as magnetron sputtering and pulsed laser deposition (PLD) can be used to deposit binder-free ceramic (inorganic) films with better thickness and morphology control than slurry coating technology. Among the various thin film deposition methods, EB-PVD is a fast (2nm / s) and scalable process that produces dense, uniform ceramic layers and does not require post-manufacturing adjustments. It uses an electron beam (EB) source that can evaporate the target material at a very high rate (about 2nm / s) and deposit it on a fixed large surface area or on roll-to-roll manufacturing required for large-scale battery manufacturing.

[0051] like Figure 2As shown, the positive electrode tab 70 (cathode tab) is located at the first end 66 of the battery cell 50, and the negative electrode tab 76 (anode tab) is located at the second end 72 of the battery cell 50. In other embodiments, when the negative electrode tab 76 is located at the same end of the battery cell 50 as the positive electrode tab 70, the separator 56 further includes an electrically insulating coating 98 applied over the uncoated area 82 of the main layer 58 and the metal coating 84.

[0052] See also Figure 4 In the exemplary embodiment, the thickness 92 of the primary layer 58 is approximately ten microns, and the thickness 94 of the thermal stability coating 62 is approximately three microns, where the term "approximately" as used herein is defined as plus or minus two microns. It will be understood by those skilled in the art that the primary layer 58 and the thermal stability coating 62 may have other thicknesses depending on design constraints / requirements.

[0053] The description of the present disclosure is merely exemplary in nature, and various changes that do not depart from the gist of the present disclosure are within the scope of the present disclosure. These changes should not be regarded as departing from the spirit and scope of the present disclosure.

Claims

1. A separator for a battery cell, comprising: a main layer comprising a porous battery separator material; a thermally stable coating applied to a surface of the primary layer that faces an anode within the battery cell; at least one of the first edge and the second edge of the primary layer comprises an uncoated region in which the thermally stable coating is not applied; as well as A metallic coating is applied to the primary layer in the uncoated areas. 2 . The diaphragm of claim 1 , further comprising a gap between the thermal stability coating and the metal coating.

3. The diaphragm according to claim 2, wherein The porous battery separator material is porous polyolefin, and the porous polyolefin includes one of polyethylene (PE), polypropylene (PP) or a PE / PP mixture. The diaphragm according to claim 2 , wherein: The thermally stable coating is one of the following: Ceramic materials; Metal oxides / metal hydroxides; or Pore-controlled polyamine (PAI) layer.

5. The diaphragm according to claim 2, wherein The metallic coating is one of the following: a polymer binder having metal particles suspended therein; a metal layer applied to the main layer by electroless plating; or A metal layer is applied to the main layer by a vapor deposition method. The diaphragm according to claim 2 , wherein: The metal coating includes one of aluminum, stainless steel, iron or iron oxide.

7. The diaphragm of claim 2, further comprising an electrically insulating coating applied over the uncoated areas of the primary layer and the metallic coating.

8. The diaphragm according to claim 2, wherein: The thickness of the main layer is about ten microns; The thermally stable coating has a thickness of approximately three microns; The metal coating has a width of at least ten microns; and The width of the gap between the thermal stability layer and the metal coating is at least one micron.

9. A battery cell comprising an anode layer, a cathode layer, and a separator located between the anode layer and the cathode layer, the separator comprising: a main layer comprising a porous battery separator material; a heat-stable coating applied to a surface of the primary layer that faces the anode; at least one of the first edge and the second edge of the primary layer comprises an uncoated region in which the thermally stable coating is not applied; as well as A metallic coating is applied to the uncoated areas on the surface of the primary layer facing the anode.

10. The battery cell according to claim 9, wherein The diaphragm includes a gap between the thermally stable coating and the metallic coating.

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