Resilient metallized pet as current collector for lithium- ion batteries

Abstract

Implementations of the present disclosure generally relate to lithium batteries. In particular, the disclosure relates to metallized polymer materials for current collectors and methods of making the same. In one implementation, a current collector is provided. The current collector includes a substrate, the substrate comprising a polyethylene terephthalate (PET) material. The current collector further includes a barrier layer disposed on the substrate, the barrier layer including an inorganic material, and a copper film disposed on the barrier layer.

Description

RESILIENT METALLIZED PET AS CURRENT COLLECTOR FOR LITHIUM- ION BATTERIES BACKGROUND Field

[0001] Implementations of the present disclosure generally relate to energy storage devices. In particular, the disclosure relates to metallized polymer materials for current collectors and methods of making the same. Description of the Related Art

[0002] Lithium-ion batteries are widely used in a variety of applications, such as electric vehicles, portable electronic devices, and renewable energy systems. For example, a typical Li-ion battery includes a positive electrode (cathode), a negative electrode (anode), an electrolyte to conduct ions, and a porous separator membrane to keep the electrodes physically apart. The performance and durability of lithium-ion batteries depend on the quality and reliability of the batteries’ components, including the current collector. The current collector serves as a conductive substrate for the active material and helps to distribute the current uniformly across the battery electrode.

[0003] Therefore what is needed in the art is an improved current collector and methods of making the same. SUMMARY

[0004] In one implementation, a current collector is provided. The current collector includes a substrate, the substrate comprising a polyethylene terephthalate (PET) material. The current collector further includes a barrier layer disposed on the substrate, the barrier layer including an inorganic material, and a copper film disposed on the barrier layer.

[0005] In another implementation, a method for forming a current collector is provided. The method includes treating a substrate to improve adhesion of the substrate and depositing a barrier layer upon the substrate, the barrier layercomprising an inorganic material and an organic material. The method further includes depositing a copper film upon the barrier layer, the copper film providing current collection capability.

[0006] In yet another implementation, a method for forming a current collector is provided. The method includes treating a substrate to improve adhesion of the substrate and depositing a barrier layer upon the substrate, the barrier layer comprising an inorganic material. The method further includes depositing a copper film upon the barrier layer, the copper film providing current collection capability, and transferring an anode onto the copper film forming a negative electrode structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to implementations, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only exemplary implementations of the disclosure and are therefore not to be considered limiting of its scope, may admit to other equally effective implementations.

[0008] Figure 1 is a schematic view of a current collector, according to some implementations.

[0009] Figure 2 is a flow diagram describing a method of forming a current collector, according to some implementations.

[0010] Figures 3A-3C illustrate side views of various stages of manufacturing a current collector according to the method of FIG.2, according to some implementations.

[0011] Figure 4 is a schematic of an energy storage device, according to some implementations.

[0012] Figure 5 is a schematic view of a roll-to-roll tool that can be used to perform part of the method, according to some implementations.

[0013] To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements and features of one implementation may be beneficially incorporated in other implementations without further recitation. DETAILED DESCRIPTION

[0014] The present disclosure relates to energy storage devices and methods of making the same. In particular, the disclosure relates to metallized polymer materials for current collectors and methods of making the same. Metallized polyethylene terephthalate (PET) has emerged as a promising current collector material due to its excellent properties such as low cost, high conductivity, and good mechanical strength. However, metallized PET is prone to copper film defects, including pinholes and scratches, which can compromise the performance and reliability of lithium-ion batteries. As described, a barrier layer between the metal layer and PET will alleviate the aforementioned defects.

[0015] It is noted that while the particular substrate on which some implementations described herein can be practiced is not limited, it is particularly beneficial to practice the implementations on flexible substrates, including for example, web-based substrates, panels and discrete sheets. The flexible substrate can also be in the form of a foil, a polymer film, or a thin plate.

[0016] It is also noted here that a flexible substrate or web as used within the implementations described herein can typically be characterized in that it is bendable. The term “web” can be synonymously used to the term “strip,” the term “flexible substrate,” or the term “flexible conductive substrate.” For example, the web as described in implementations herein can be or include a polymer material.

[0017] It is further noted that the methods and systems described may be used in forming single-sided electrode structures and double-sided electrode structures.

[0018] Figure 1 is a cross-section of a current collector 100. The current collector 100 includes a substrate 101, a barrier layer 110, and a copper film 120. The barrier layer 110 is disposed on the substrate 101. The copper film 120 is disposed on the barrier layer 110.

[0019] The substrate 101 may comprise any suitable material that is compatible with the targeted processing conditions including the barrier layer 110 disposed above the substrate 101. In one or more implementations, which can be combined with other implementations, the substrate 101 can be or include, one or more layers selected from polymer materials. Example of suitable polymer materials include PET, polyethylene naphthalate (PEN), polyimide (PI), poly(methyl methacrylate) (PMMA), cellulose tri-acetate (TAC), polypropylene (PP), polyethylene (PE), polycarbonates (PC), multilayers thereof, or a combination thereof. In one implementation, the substrate 101 can be polyethylene terephthalate (PET). In one or more implementations, which can be combined with other implementations, the substrate 101 is a web- based substrate. In one or more implementations, the substrate 101 is selected from substrates prepared by a film casting process, an extrusion process, a coating process, a melt pressing process, or a solvent casting process.

[0020] In one or more implementations, which can be combined with other implementations, the substrate 101 has a thickness in a range from about 1 micron to about 25 microns, or in a range from about 1 micron to about 10 microns, or in a range from about 3 microns to about 7 microns. In one or more implementations, the substrate 101 has a thickness of about 5 microns.

[0021] The barrier layer 110 includes or is an inorganic material. In some implementations, the barrier layer 110 includes or is a hybrid coating comprising an inorganic material and an organic material. The barrier layer may be a multi- layer structure including one or more inorganic material layers and one or moreorganic material layers. The hybrid coating includes an inorganic material layer and an organic material layer. The inorganic material layer may be a ceramic material. The ceramic material may be an oxide. The inorganic material layer may be a dielectric material. The dielectric material may be selected from, for example, aluminum oxide (Al2O3), AlOx, AlOxNy, AlN (aluminum deposited in a nitrogen environment), calcium carbonate (CaCO3), titanium dioxide (TiO2), indium tin oxide (ITO), zinc oxide (ZnO), SiS2, SiPO4, silicon oxide (SiO2), zirconium oxide (ZrO2), MgO, Ta2O5, Nb2O5, LiAlO2, BaTiO3, BN, ion- conducting garnet, ion-conducting perovskite, ion-conducting anti-perovskites, porous glass ceramic, and the like, or combinations thereof, where x and y are zero or positive integers. In one implementation, the inorganic material layer is a material selected from the group comprising, consisting of, or consisting essentially of: porous aluminum oxide, porous-ZrO2, porous-SiO2, porous-MgO, porous-TiO2, porous-Ta2O5, porous-Nb2O5, porous-LiAlO2, porous-BaTiO3, ion- conducting garnet, anti-ion-conducting perovskites, porous glass dielectric, or combinations thereof. In some implementations, the inorganic material layer is a porous aluminum oxide layer. The inorganic material may include other similar materials or combinations thereof. The inorganic material may offer various properties, such as high thermal stability, chemical resistance, electrical insulation, ion conduction, or specific dielectric properties. For example, ion- conducting garnets or perovskites may be employed as solid electrolytes in solid-state batteries, where they enable ion conduction while acting as protective coatings on electrode materials. Inorganic materials like Al2O3 or SiO2can serve as protective layers against corrosion or as dielectric coatings for electronic components.

[0022] The organic material may include polyethylene terephthalate glycol (PETG), polypropylene (PP), conductive polymers, carbon-based materials, and polymer-metal composites or other similar materials or combinations thereof. Conductive polymers include polyaniline (PANI), polypyrrole (PPy), and poly(3,4-ethylenedioxythiophene) (PEDOT) and other similar materials. Carbon-based materials include Carbon nanotubes (CNTs), graphene, and carbon-based composites. Polymer-metal composites include incorporatingmetal nanoparticles or thin films within a polymer matrix. In some implementations, the organic layer is formed from a surface treatment on the surfaces 301A-B of the substrate 101 when the substrate 101 is a polymer. These surface treatments include mechanical abrasion, UV / ozone exposure, silane coupling agents, plasma polymerization, and photografting. In some implementations for the hybrid coating, the organic material layer is disposed on the inorganic material layer. In other implementations, the inorganic material layer is disposed on the organic material layer.

[0023] The copper film 120 performs the functions of the current collector 100, including providing current collection capability. In one or more implementations, which can be combined with other implementations, the copper film 120 has a thickness in a range from about 0.05 microns to about 100 microns, or in a range from about 0.1 microns to about 50 microns, or in a range from about 0.2 micron to about 10 micron, or in a range from about 0.3 microns to about 1 micron. In one or more implementations, the copper film 120 has a thickness of 0.5 microns.

[0024] The barrier layer 110 provides excellent barrier properties against moisture, oxygen, and other gases, as well as improved adhesion and flexibility. The barrier layer 110 also helps to prevent the diffusion of lithium ions through defects such as pinholes and scratches in the copper film 120, resulting in improved durability and performance of the metallized PET current collector. The resulting resilient metallized PET current collector can be used in a variety of energy storage device applications, for example, lithium ion battery applications, including electric vehicles, consumer electronics, and grid storage systems.

[0025] Figure 2 is a flow diagram for a method 200 of producing the current collector 100. Figures 3A-3C are views of various stages of manufacturing a current collector 300 according to the method 200 of Figure 1. The method 200 describes forming the current collector 300. Although Figures 3A-3C are described in relation to the method 200, it will be appreciated that the structures disclosed in Figures 3A-3C are not limited to the method 200, but instead maystand alone as structures independent of the method 200. Similarly, although the method 200 is described in relation to Figures 3A-3C, it will be appreciated that the method 200 is not limited to the structures disclosed in Figures 3A-3C but instead may stand alone independent of the structures disclosed in Figures 3A-3C. It should also be noted that although the method 200 illustrated in Figures 3A-3C is described sequentially, other process sequences that include one or more operations that have been omitted and / or added, and / or have been rearranged in another desirable order, fall within the scope of the implementations of the disclosure provided herein.

[0026] Referring to Figure 3A, optionally at operation 201, the substrate 101 is treated. The pre-treatment of the substrate 101 is a surface treatment process. In some implementations, the pre-treatment of the substrate 101 is one or more surface treatment processes. The substrate 101 has a first surface 301A and a second surface 301B that oppose each other. The surface treatment process can be performed to remove contaminants (if present) from the first surface 301A and the second surface 301B of the substrate 101 to activate the first surface 301A and second surface 301B for better bonding, attachment, or wetting by subsequently deposited material. The surface treatment process can be selected from a cleaning process, a corona treatment process, an atmospheric plasma treatment process, a low energy plasma treatment process, a plasma treatment process performed in a vacuum environment, a chemical etching process, a surface activation process, a primer coating process or a combination thereof.

[0027] The surface treatment process can be performed under atmospheric conditions, near atmospheric conditions, or vacuum conditions. In one example the surface treatment process can be carried out in a vacuum environment with an environment of 1 x 10-2mbar to about 1 x 10-6mbar (e.g., 1 x 10-3or below; 1 x 10-4or below).

[0028] The surface treatment process can be a plasma treatment performed in an oxidizing gas environment, a reducing gas environment, or a combination of oxidizing and reducing gases. The plasma treatment can be performedunder atmospheric conditions, near atmospheric conditions, or vacuum conditions. The oxidizing environment can include one or more oxidizing gases. The one or more oxidizing gases can be selected from oxygen (O2), ozone (O3), nitrous oxide (N2O), fluorine (F2), chlorine (Cl2), carbon monoxide (CO), carbon dioxide (CO2), radicals thereof, derivatives thereof, or a combination thereof. In one implementation, the one or more oxidizing gases include oxygen (O2). The one or more oxidizing gases can be introduced with one or more inert gases, such as nitrogen, helium or argon. The reducing environment can include one or more reducing gases. The reducing gases can be selected from ammonia (NH3), hydrazine (N2H4), hydrogen (H2), NF3, atomic hydrogen, radicals thereof, derivatives thereof, or a combination thereof. In one example, the one or more reducing gases includes hydrogen. The one or more reducing gases can be introduced with one or more inert gases, such as nitrogen, helium or argon.

[0029] In some implementations, the surface treatment process is a plasma treatment process performed in a vacuum environment. The plasma treatment process can include exposing the electrode structure to a reducing plasma. The reducing plasma can be formed from a reducing gas mixture comprising ammonia (NH3), hydrazine (N2H4), hydrogen (H2), atomic hydrogen, radicals thereof, derivatives thereof, or a combination thereof. The reducing gas mixture can further include one or more inert gases. The reducing plasma can be a remotely formed plasma, a capacitively coupled plasma, or an inductively coupled plasma. The plasma treatment process can include exposing the electrode structure to an oxidizing plasma. The oxidizing plasma can be formed from an oxidizing gas mixture comprising oxygen (O2), ozone (O3), nitrous oxide (N2O), fluorine (F2), chlorine (Cl2), carbon monoxide (CO), carbon dioxide (CO2), radicals thereof, derivatives thereof, or a combination thereof. The oxidizing gas mixture can further include one or more inert gases. The oxidizing plasma can be a remotely formed plasma, a capacitively coupled plasma, or an inductively coupled plasma.

[0030] The surface treatment process can be a corona treatment (e.g., an air plasma treatment) used to modify the surface of the electrode structure. The corona treatment can be performed using a low temperature corona discharge plasma to impart changes to the surface energy of the electrode structure. The corona treatment discharge process includes generating an ionized corona discharge plasma. The generated corona discharge plasma can include a positive or negatively charged plasma.

[0031] Corona discharge usually involves two asymmetric electrodes positioned in a processing region; one highly curved, e.g., a needle tip or a small diameter wire, and one of low curvature, e.g., a plate, or a ground. The high curvature ensures a high potential around the electrode, providing for the generation of a plasma. If the geometry and gradient are such that the ionized region continues to grow instead of stopping at a certain radius, a completely conductive path may be formed, resulting in a momentary spark or a continuous arc.

[0032] In some implementations, the corona is positive. In other implementations, the corona is negative. This is determined by the polarity of the voltage on the highly-curved electrode. If the curved electrode is positive with respect to the flat electrode a positive corona exists; otherwise the corona is negative. In some implementations, the corona treatment is carried out in part under atmospheric or partial pressure, under vacuum, or a combination thereof.

[0033] The surface treatment process can be a cleaning process including a solvent cleaning, ultrasonic cleaning, or plasma cleaning as described above. Cleaning processes remove any contaminates such as oils, dust, and particles that could hinder adhesion from the first surface 301A and the second surface 301B of the substrate 101. The surface treatment process can be a chemical etching process. Chemical etching processes include the use of chemicals to modify the first surface 301A and the second surface 301B of the substrate 101. For example, chemical etching with acids or alkaline solutions can createmicrostructures or increase surface roughness, promoting mechanical interlocking and adhesion of the barrier layers 110 to the substrate 101.

[0034] The surface treatment process can be a surface activation process that can include flame treatment or corona discharge as described above. The flame treatment may modify the polymer surface by introducing reactive groups or increasing surface energy enhancing the adhesion between the substrate 101 and the barrier layers 110. The surface treatment process can be a primer coating process. The primer coating process includes applying a thin layer of a compatible primer or adhesion promoter to the substrate 101. A primer may improve the bonding between the substrate 101 and the barrier layers 110. The primer enhances the interfacial compatibility and provides a chemically favorable environment for adhesion.

[0035] Referring to Figure 3B, at operation 203, the barrier layers 110 are deposited. The barrier layers 110 include a first barrier layer 310A and a second barrier layer 310B. A first barrier layer 310A is deposited on the first surface 301A of the substrate 101. A second barrier layer 310B is deposited on the second surface 301B of the substrate 101. The first barrier layer 310A has a first surface 311A and a second surface 311B opposed to the first surface 311A. The second surface 311B of the first barrier layer 310A is disposed over the first surface 301A of the substrate 101. The second barrier layer 310B has a first surface 312A and a second surface 312B opposed to the first surface 312A. The second surface 312B of the second barrier layer 310B is disposed over the second surface 301B of the substrate 101. The deposition of the barrier layers 110 may include atomic layer deposition (ALD), physical vapor deposition (PVD), chemical vapor deposition (CVD), spin coating, electrochemical deposition, extrusion coating, or laminating. In one or more implementations, the second barrier layer 310B is not disposed on the second surface 301B.

[0036] The inorganic layer of the barrier layers 110 may be deposited by an ALD process, a CVD process, spin coating process, electrochemical process, or a PVD process. In one implementation, the ALD process can be plasmaenhanced. The PVD process may include a cold electron beam, sputter or a similar process. The CVD process may be a thermal CVD process, a plasma assisted CVD process, or a low-pressure CVD process. The inorganic layer may be a thin film or a thick coating. The thin film of the inorganic layer has a thickness in a range from about 1 nm to about 10 μm, or in a range from about 2 nm to about 6 μm, or in a range from about 4 nm to about 4 μm. The thick coating of the inorganic layer has a thickness in a range from about 2 μm to about 90 μm or in a range from about 4 μm to about 50 μm, or in a range from about 6 nm to about 20 μm.

[0037] In some implementations where an organic layer is present in the barrier layer 110, the organic layer is deposited over the inorganic layer. In other implementations, the inorganic layer is deposited over the organic layer. In some implementations, an inorganic layer is deposited on the substrate 101, an organic layer is deposited on the inorganic layer, and a second inorganic layer is deposited on the organic layer. The organic layer of the barrier layers 110 may be deposited by an extrusion coating process, a vapor deposition process, a spin coating process, or a laminating process. The organic layer may be a thin coating or if the organic layer is made of a polymer a polymer film. The thin coating of the organic layer has a thickness in a range from about 1 nm to about 10 μm, or in a range from about 2 nm to about 6 μm, or in a range from about 4 nm to about 4 μm. The polymer coating of the organic layer has a thickness in a range from about 2 μm to about 500 μm or in a range from about 4 μm to about 100 μm, or in a range from about 6 nm to about 50 μm.

[0038] Referring to Figure 3C, at operation 205, the copper film 120 is deposited. The copper films 120 are deposited on the barrier layers 110. The copper films 120 may include a first copper film 320A and a second copper film 320B. A first copper film 320A is deposited of the first surface 311A of the first barrier layer 310A. A second copper film 320B is deposited on the second surface 311B of the substrate 101. The first copper film 320A has a first surface 321A and a second surface 321B opposed to the first surface 321A. The second surface 321B of the first copper film 320A is disposed over the firstsurface 311A of the first barrier layer 310A. The second copper film 320B has a first surface 322A and a second surface 322B opposed to the first surface 322A. The second surface 322B of the second copper film 320B is disposed over the first surface 312A of the second barrier layer 310B. The deposition may include a sputtering process or an electroplating process. The sputtering process is a PVD process using plasma. The sputtering process may be a DC sputtering process, an RF sputtering process, a magnetron sputtering process, or a reactive sputtering process.

[0039] In operation 207, an anode 350 is optionally deposited on the current collector 100. Referring to Figure 4, the anode 350 is disposed on the first surface 321A of the first copper film 320A. The anode 350 may have an energy capacity greater than or equal to 372 mAh / g, preferably ≥ 700 mAh / g, and most preferably ≥ 1000 mAh / g. The anode 350 may be constructed from a graphite, silicon-containing graphite (e.g., silicon (<5%) blended graphite), a lithium metal foil or a lithium alloy foil (e.g. lithium aluminum alloys), or a mixture of a lithium metal and / or lithium alloy and materials such as carbon (e.g. coke, graphite), nickel, copper, tin, indium, silicon, oxides thereof, or combinations thereof. The anode 350 may comprise intercalation compounds containing lithium or insertion compounds containing lithium.

[0040] The anode 350 can be deposited onto the current collector 100 using any suitable method. In one or more implementations, which can be combined with other implementations, the anode is transferred to the current collector 100 using a substrate independent direct transfer (SIDT) method. SIDT is a method to transfer anodes 350 to current collectors in energy storage devices using a transfer substrate and a release layer. In SIDT processes, the anode is first deposited on a transfer substrate then transferred to the first surface 321A of the first copper film 320A on the current collector 100 using a release layer. The anode 350 and current collector 100 together make up the negative electrode structure 360.

[0041] At operation 209, the negative electrode structure 360 is optionally integrated with a separator 410 and a cathode structure 420 to form an energystorage device 400 as is shown in Figure 4. Figure 4 is a schematic view of the energy storage device 400.

[0042] The separator 410 may include, a microporous polymeric separator including a polyolefin, by way of non-limiting example. The polyolefin may be a homopolymer (derived from a single monomer constituent) or a heteropolymer (derived from more than one monomer constituent), which may be either linear or branched. If a heteropolymer is derived from two monomer constituents, the polyolefin may assume any copolymer chain arrangement, including those of a block copolymer or a random copolymer. Similarly, if the polyolefin is a heteropolymer derived from more than two monomer constituents, it may likewise be a block copolymer or a random copolymer. In certain implementations, the polyolefin may be polyethylene (PE), polypropylene (PP), or a blend of PE and PP, or multi-layered structured porous films of PE and / or PP. Commercially available polyolefin porous membranes include CELGARD® 2500 (a monolayer polypropylene separator) and CELGARD® 2320 (a tri-layer polypropylene / polyethylene / polypropylene separator) available from Celgard LLC.

[0043] In one or more implementations, which can be combined with other implementations, the cathode structure 420 includes a cathode current collector 440 and cathode 430. The cathode current collector 440 may be or include any of the flexible films described and aluminum (Al), copper (Cu), zinc (Zn), nickel (Ni), cobalt (Co), tin (Sn), silicon (Si), manganese (Mn), magnesium (Mg), alloys thereof, and combinations thereof. The cathode current collector 440 may be or include any of aluminum (Al), copper (Cu), zinc (Zn), nickel (Ni), cobalt (Co), tin (Sn), silicon (Si), manganese (Mn), magnesium (Mg), alloys thereof, and combinations thereof. In particular implementations, the cathode current collector 440 may be or include aluminum.

[0044] The cathode 430 may be or include any suitable cathode material. The cathode 430 may be or include any material compatible with the anode and may include an intercalation compound, an insertion compound, or an electrochemically active polymer. Suitable intercalation materials include, forexample, sulfur, lithium-containing metal oxides, MoS2, FeS2, MnO2, TiS2, NbSe3, LiCoO2, LiNiO2, LiMnO2, LiMn2O4, V6O13 and V2O5. Suitable polymers include, for example, polyacetylene, polypyrrole, polyaniline, and polythiophene. In some implementations the cathode 430 includes a polymer binder material as described herein. The cathode 430 or cathode may be or include a layered oxide, such as lithium cobalt oxide, an olivine, such as lithium iron phosphate, or a spinel, such as lithium manganese oxide. Examples of lithium-containing oxides may be layered, such as lithium cobalt oxide (LiCoO2), or mixed metal oxides, such as LiNixCo1-2xMnO2, LiNiMnCoO2 (“NMC”), LiNi0.5Mn1.5O4, Li(Ni0.8Co0.15Al0.05)O2, LiMn2O4, and doped lithium rich layered-layered materials, wherein x is zero or a non-zero number. Examples ofphosphates may be or include iron olivine (LiFePO4) and it is variants (such as LiFe(1-x)MgxPO4), LiMoPO4, LiCoPO4, LiNiPO4, Li3V2(PO4)3, LiVOPO4, LiMP2O7, or LiFe1.5P2O7, wherein x is zero or a non-zero number. Examples offluorophosphates may be or include LiVPO4F, LiAlPO4F, Li5V(PO4)2F2,Li5Cr(PO4)2F2,Li2CoPO4F, or Li2NiPO4F. Example of silicates may be orinclude Li2FeSiO4, Li2MnSiO4, or Li2VOSiO4. Examples of non-lithium compounds may be or include Na5V2(PO4)2F3.

[0045] Figure 5 is a schematic view of a roll-to-roll tool 500 that can be used in some implementations to perform the method 200. According to typical implementations, the roll-to-roll tool 500 can be used for manufacturing the current collector 100. The roll-to-roll tool 500 is constituted as a roll-to-roll system including an unwinding module 502, a processing module 504 and a winding module 506. In certain implementations, the processing module 504 comprises a plurality of processing modules or chambers 510, 520, 530 and 540 arranged in sequence, each configured to perform one processing operation to a continuous sheet of material 550 or web of material. In one implementation, as depicted in FIG.5, the processing chambers 510-540 are radially disposed about a coating drum 555. Other arrangements besides radial are contemplated. For example, in another implementation, the processing chambers may be positioned in a linear configuration.

[0046] In one implementation, the processing chambers 510-540 are stand- alone modular processing chambers wherein each modular processing chamber is structurally separated from the other modular processing chambers. Therefore, each of the stand-alone modular processing chambers, can be arranged, rearranged, replaced, or maintained independently without affecting each other. Although four processing chambers 510-540 are shown, it should be understood that any number of processing chambers may be included in the roll-to-roll tool 500.

[0047] The processing chambers 510-540 may include any suitable structure, configuration, arrangement, and / or components that enable the roll- to-roll tool 500 to form the current collector. For example, the processing chambers may include suitable deposition systems including, but not limited to, coating sources, power sources, individual pressure controls, deposition control systems, and temperature control. In some implementations, the chambers are provided with individual gas supplies. The chambers are typically separated from each other for providing a good gas separation. The roll-to-roll tool 500 according to implementations described herein is not limited in the number of deposition chambers. For example, the roll-to-roll tool 500 may include, but not be limited to, 3, 6, or 12 processing chambers.

[0048] The processing chambers 510-540 typically include one or more deposition units 512, 522, 532, and 542. Generally, the one or more deposition units as described herein can be selected from the group of a CVD source, a PECVD source and a PVD source. The one or more deposition units can include an evaporation source, a sputter source, such as, a magnetron sputter source, DC sputter source, AC sputter source, pulsed sputter source, radio frequency (RF) sputtering, or middle frequency (MF) sputtering. For instance, MF sputtering with frequencies in the range of 5 kHz to 100 kHz, for example, 30 kHz to 50 kHz, can be provided. The one or more deposition units can include an evaporation source. In one implementation, the evaporation source is a thermal evaporation source or an electron beam evaporation.

[0049] In some implementations, any of the processing chambers 510-540 of the roll-to-roll tool 500 may be configured for performing deposition by sputtering, such as magnetron sputtering. As used herein, "magnetron sputtering" refers to sputtering performed using a magnet assembly, that is, a unit capable of generating a magnetic field. Typically, such a magnet assembly includes a permanent magnet. This permanent magnet is typically arranged within a rotatable target or coupled to a planar target in a manner such that the free electrons are trapped within the generated magnetic field generated below the rotatable target surface. Such a magnet assembly may also be arranged coupled to a planar cathode.

[0050] Magnetron sputtering may also be realized by a double magnetron cathode, such as, but not limited to, a TwinMag™ cathode assembly. In some implementations, the cathodes in the processing chamber may be interchangeable. Thereby, a modular design of the apparatus is provided which facilitates optimizing the apparatus for particular manufacture requirements. In some implementations, the number of cathodes in a chamber for sputtering deposition is chosen for optimizing an optimal productivity of the roll-to-roll tool 500.

[0051] In some implementations, one or some of the processing chambers 510-540 may be configured for performing sputtering without a magnetron assembly. In some implementations, one or some of the chambers may be configured for performing deposition by other methods, such as, but not limited to, chemical vapor deposition, atomic laser deposition or pulsed laser deposition. In some implementations, one or some of the chambers may be configured for performing a plasma treatment process, such as a plasma oxidation or plasma nitridation process.

[0052] In certain implementations, the processing chambers 510-540 are configured to process both sides of the continuous sheet of material 550. Although the roll-to-roll tool 500 is configured to process a horizontally oriented continuous sheet of material 550, the roll-to-roll tool 500 may be configured to process substrates positioned in different orientations, for example, a verticallyoriented continuous sheet of material 550. In certain implementations, the continuous sheet of material 550 is a flexible conductive substrate. In certain implementations, the continuous sheet of material 550 includes a conductive substrate with one or more layers formed thereon. In certain implementations, the conductive substrate is the substrate 101 shown in FIGS.3A-3C.

[0053] In certain implementations, the roll-to-roll tool 500 comprises a transfer mechanism 552. The transfer mechanism 552 may comprise any transfer mechanism capable of moving the continuous sheet of material 550 through the processing region of the processing chambers 510-540. The transfer mechanism 552 may comprise a common transport architecture. The common transport architecture may comprise a roll-to-roll system with a common take-up-reel 554 positioned in the winding module 506, the coating drum 555 positioned in the processing module 504, and a feed reel 556 positioned in the unwinding module 502. The take-up reel 554, the coating drum 555, and the feed reel 556 may be individually heated. The take-up reel 554, the coating drum 555 and the feed reel 556 may be individually heated using an internal heat source positioned within each reel or an external heat source. The common transport architecture may further comprise one or more auxiliary transfer reels 553a, 553b positioned between the take-up reel 554, the coating drum 555, and the feed reel 556. Although the roll-to-roll tool 500 is depicted as having a single processing region, in certain implementations, it may be advantageous to have separated or discrete processing regions for each individual processing chamber 510-540. For implementations having discrete processing regions, modules, or chambers, the common transport architecture may be a roll-to-roll system where each chamber or processing region has an individual take-up-reel and feed reel and one or more optional intermediate transfer reels positioned between the take-up reel and the feed reel.

[0054] A controller 560 is in communication with the roll-to-roll tool 500 and the components thereof. The controller 560 can be configured to run the method 200 or portions of the method 200. The controller 560 includes amemory, a central processing unit (CPU), and a support circuit. The memory is configured to store instructions corresponding to any portion of the method 200 described above. The CPU can be one of any form of computer processor that can be used in an industrial setting. The memory is coupled to the CPU. The memory can be one or more of readily available memory, such as random access memory (RAM), read only memory (ROM), floppy disk, hard disk, or any other form of digital storage, local or remote. The support circuits include cache, power supplies, clock circuits, input / output circuitry, subsystems, and the like.

[0055] The roll-to-roll tool 500 may comprise the feed reel 556 and the take- up reel 554 for moving the continuous sheet of material 550 through the different processing chambers 510-540. In one implementation, the first processing chamber 510 is configured to .treat the surface of the substrate 101 as described in operation 201. The second processing chamber 520 is configured to deposit the barrier layer 110 as shown in operation 203. The third processing chamber 530 is configured to deposit the copper film 120, as described in operation 205. The fourth processing chamber 540 is configured to deposit an anode 350 on the current collector 100, as described in operation 207. In some implementations, the negative electrode structure 360 will not be collected on take-up reel 554 as shown in Figure 5, but may go directly for integration with the separator 410 and the cathode structure 420 to form the energy storage device 400.

[0056] In operation, the continuous sheet of material 550 is unwound from the feed reel 556 as indicated by the substrate movement direction shown by arrow 508. The continuous sheet of material 550 may be guided via one or more auxiliary transfer reels 553a, 553b. It is also possible that continuous sheet of material 550 is guided by one or more substrate guide control units (not shown) that shall control the proper run of the flexible substrate, for instance, by finely adjusting the orientation of the flexible substrate.

[0057] After uncoiling from the feed reel 556 and running over the auxiliary transfer reel 553a, the continuous sheet of material 550 is then moved through the deposition areas provided at the coating drum 555 and corresponding topositions of the deposition units 512, 522, 532, and 542. During operation, the coating drum 555 rotates around axis 551 such that the flexible substrate moves in the direction of arrow 508.

[0058] The previously described implementations of the present disclosure have many advantages. However, the present disclosure does not require that all the advantageous features and all the advantages need to be incorporated into every implementation of the present disclosure. In summation, the current collector produced by the present disclosure provides several advantages. The barrier layer applied between the substrate and the copper film provides excellent protection against scratches, pinholes, and lithium diffusion, which can significantly enhance the performance and durability of lithium-ion batteries. The current collector has improved adhesion, surface smoothness, and resistance to delamination, which may improve the manufacturing process and reduce expenses.

[0059] While the foregoing is directed to implementations of the present disclosure, other and further implementations of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.

Claims

What is claimed is:

1. A current collector, comprising: a substrate, the substrate comprising a polyethylene terephthalate (PET) material; a barrier layer disposed on the substrate, the barrier layer including an inorganic material; and a copper film disposed on the barrier layer.

2. The current collector of claim 1, wherein the barrier layer further comprises an organic material.

3. The current collector of claim 2, wherein the barrier layer is a hybrid coating comprising an inorganic layer comprising the inorganic material and an organic layer comprising the organic material.

4. The current collector of claim 1, wherein the inorganic material comprises aluminum oxide, silicon oxide, or combinations thereof.

5. The current collector of claim 2, wherein the organic material comprises polyethylene terephthalate glycol (PETG), polypropylene (PP), or combinations thereof.

6. The current collector of claim 1, wherein the substrate has a thickness of 5 microns.

7. The current collector of claim 1, wherein the copper film has a thickness of 0.5 microns.

8. A method for forming a current collector, comprising: treating a substrate to improve adhesion of the substrate;depositing a barrier layer upon the substrate, the barrier layer comprising an inorganic material and an organic material; and depositing a copper film upon the barrier layer, the copper film providing current collection capability.

9. The method for forming a current collector of claim 8, wherein the inorganic material of the barrier layer is deposited by atomic layer deposition (ALD) or physical vapor deposition (PVD).

10. The method for forming a current collector of claim 8, wherein the organic material of the barrier layer is deposited by an extrusion coating process or a laminating process.

11. The method for forming a current collector of claim 8, wherein the copper film is deposited by a sputtering process or an electroplating process.

12. The method for forming a current collector of claim 8, wherein the barrier layer prevents lithium ions, moisture, oxygen, and other gases from passing through defects in the copper film.

13. The method for forming a current collector of claim 8, wherein the barrier layer improves adhesion and flexibility of the copper film.

14. A method for forming a current collector, comprising: treating a substrate to improve adhesion of the substrate; depositing a barrier layer upon the substrate, the barrier layer comprising an inorganic material; depositing a copper film upon the barrier layer, the copper film providing current collection capability; and transferring an anode onto the copper film to form a negative electrode structure.

15. The method for forming a current collector of claim 14, wherein the inorganic material of the barrier layer is deposited by atomic layer deposition (ALD) or physical vapor deposition (PVD).

16. The method for forming a current collector of claim 14, wherein the barrier layer further comprises an organic material, the organic material deposited by an extrusion coating process or a laminating process.

17. The method for forming a current collector of claim 14, wherein the copper film is deposited by a sputtering process or an electroplating process.

18. The method for forming a current collector of claim 14, wherein the barrier layer prevents lithium ions, moisture, oxygen, and other gases from passing through defects in the copper film.

19. The method for forming a current collector of claim 14, wherein the barrier layer improves adhesion and flexibility of the copper film.

20. The method for forming a current collector of claim 14, further comprising: integrating the negative electrode structure with a separator and cathode structure to form an energy storage device.

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