Functional current collectors for low voltage protection in metal-ion batteries

Abstract

A battery cell includes an electrolyte, a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode. The positive electrode includes one or more layers of a positive electrode active material deposited on a positive current collector. The negative electrode includes one or more layers of a negative electrode active material deposited on a negative current collector. At least one of the positive current collector and the negative current collector may be a functional current collector having a metal foil interposed between a first protective layer and a second protective layer. The first protective layer and the second protective layer prevent a corrosion of the metal foil while the battery cell is in a low-voltage state or a zero-voltage state.

Description

FUNCTIONAL CURRENT COLLECTORS FOR LOW VOLTAGE PROTECTION IN METAL-ION BATTERIESCROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Application No. 63 / 690,517, entitled “MULTI-LAYERED FUNCTIONAL CU FOIL LOW VOLTAGE PROTECTION FOR METAL-ION BATTERIES” and filed on September 4, 2024, and U.S. Provisional Application No. 63 / 866,768, entitled “PROTECTED AND REINFORCED CURRENT COLLECTORS FOR LOW VOLTAGE PROTECTION IN METAL-ION BATTERIES” and filed on August 19, 2025, the disclosures of which are incorporated herein by reference in their entireties.TECHNICAL FIELD

[0002] The subject matter described herein relates generally to battery technology and more specifically to protective mechanisms for a battery cell exposed to low-voltage or zerovoltage conditions.BACKGROUND

[0003] Metal ion battery cells, such as lithium ion (Li+) battery cells, exhibit high energy density and high current output. As such, metal ion battery cells are suitable for a variety of high energy and high power applications. However, metal ion battery cells are also susceptible to internal morphological deformations caused by parasitic reactions that occur during the charging and discharging of the metal ion battery cell. The development of internal morphological deformations may diminish the capacity and cycle life of the metal ion battery cell. Even more critically, some internal morphological deformations, such as the formation of dendrites on the electrodes of the metal ion battery cell, may give rise to significant safety hazards. For example, dendrite growth, a common occurrence arising from the nonuniformmetal deposits on the surface of the negative electrode (anode) during the charging of the metal ion battery cell, can penetrate the separator in a metal ion battery cell to form an internal short circuit between the negative electrode (anode) and positive electrode (cathode). Internal short circuits are a leading cause of thermal runways, a catastrophic chain reaction in which undissipated heat from an overheating battery cell accelerates exothermic reactions within the battery cell to further increase the temperature of the battery. The consequences of thermal runaway include fires and explosions that are especially difficult to contain.SUMMARY

[0004] Systems and methods for a functional current collector providing low voltage protection in metal-ion batteries. In one aspect, there is provided a battery cell. The battery cell may include: an electrolyte; a positive electrode comprising one or more layers of a positive electrode active material deposited on a positive current collector; a negative electrode comprising one or more layers of a negative electrode active material deposited on a negative current collector; and a separator interposed between the positive electrode and the negative electrode, wherein at least one of the positive current collector and the negative current collector comprise a functional current collector having a metal foil interposed between a first protective layer and a second protective layer, and wherein the first protective layer and the second protective layer prevent a corrosion of the metal foil while the battery cell is in a low-voltage state or a zero-voltage state.

[0005] In some variations, one or more features disclosed herein including the following features can optionally be included in any feasible combination.

[0006] In some variations, the first protective layer and the second protective layer prevents a structural degradation of the metal foil caused by an expansion and contraction of thepositive electrode and / or the negative electrode during a charging and discharging of the battery cell.

[0007] In some variations, the functional current collector further includes a first sacrificial layer.

[0008] In some variations, the first sacrificial layer is interposed between the first protective layer and one or more layers of electrode active material.

[0009] In some variations, the first sacrificial layer is interposed between the first protective layer and the metal foil.

[0010] In some variations, the functional current collector further includes a second sacrificial layer.

[0011] In some variations, the second sacrificial layer is disposed on a surface of the second protective layer opposite the metal foil.

[0012] In some variations, the second sacrificial layer is interposed between the metal foil and the second protective layer.

[0013] In some variations, the functional current collector further includes a first cover layer and a second cover layer, wherein the first cover layer is interposed between the first protective layer and one or more layers of electrode active material, and the second cover layer is disposed on a surface of the second protective layer opposite the metal foil.

[0014] In some variations, the functional current collector further includes a first adhesive promotion layer and a second adhesive promotion layer, wherein the first adhesive promotion layer is interposed between the first protective layer and the metal foil, and the second adhesive promotion layer is interposed between the metal foil and the second protective layer.

[0015] In some variations, one or both of the first protective layer and the second protective layer include one or more inert materials.

[0016] In some variations, the one or more inert materials include one or more metals.

[0017] In some variations, the one or more metals include titanium (Ti) and / or zinc (Zn).

[0018] In some variations, the one or more inert materials include one or more ceramic materials.

[0019] In some variations, the one or more ceramic materials include titanium nitride (TiN), titanium carbide (TiC), titanium boride (TiB), and / or titanium diboride (TiB?).

[0020] In some variations, the one or more inert materials include one or more semiconductor nanomaterials.

[0021] In some variations, the one or more semiconductor nanomaterials include zinc oxide (ZnCh), titanium dioxide (TiCh), and / or carbon nitride (CN).

[0022] In some variations, the one or more inert materials include graphene, hexagonal boron nitride (hBN), layered double hydroxide, and / or a diverse corrosion inhibitor.

[0023] In some variations, one or both of the first protective layer and the second protective layer comprise a fluorocarbon coating.

[0024] In some variations, one or both of the first protective layer and the second protective layer comprise a diamond-like carbon (DLC) coating.

[0025] In some variations, one or both of the first protective layer and the second protective layer include one or more reactive materials.

[0026] In some variations, the one or more reactive materials include magnesium (Mg), tin (Sn), carbon (C), graphene, and / or titanium oxide (TiCh).

[0027] In some variations, one or both of the first protective layer and the second protective layer include one or more nitrides.

[0028] In some variations, the one or more nitrides include silicon nitride (SislSk, SixNy), titanium nitride (TiN), aluminum nitride (AIN), boron bitride (BN), and / or zirconium nitride (ZrN).

[0029] In some variations, one or both of the first protective layer and the second protective layer include one or more oxides.

[0030] In some variations, the one or more oxides include aluminum oxide (AI2O3, A1O), titanium oxide (TiCh, TiO), silicon oxide (SiCh, SiO), zinc oxide (ZnO), magnesium oxide (MgO), hafnium oxide (HfCh), tantalum oxide (Ta20s), and / or chromium oxide (CrcCh).

[0031] In some variations, one or both of the first protective layer and the second protective layer include one or more conductive metals.

[0032] In some variations, the one or more conductive metals include nickel (Ni), zinc (Zn), titanium (Ti), silver (Ag), and / or gold (Au).

[0033] In some variations, one or both of the first protective layer and the second protective layer include one or more metal alloys.

[0034] In some variations, the one or more metal alloys include nickel chromium (NiCr), iron chromium (FeCr), aluminum chromium (AlCr), zinc aluminum (ZnAl), and / or titanium aluminum (TiAl).

[0035] In some variations, the first protective layer and the second protective layer are 20-300 micrometer (pm) thick, 50-200 micrometer (pm) thick, or 80-150 micrometer (pm) thick.

[0036] In some variations, one or both of the first protective layer and the second protective layer include one or more carbides.

[0037] In some variations, the one or more carbides include silicon carbide (SiC), titanium carbide (TiC), and / or tungsten carbide (WC).

[0038] In some variations, one or both of the first protective layer and the second protective layer comprise multilayer and / or nanolaminate coatings.

[0039] In some variations, the multilayer and / or nanolaminate coatings comprise alternating layers of oxides, nitrides, and / or metals.

[0040] The details of one or more variations of the subject matter described herein are set forth in the accompanying drawings and the description below. Other features and advantages of the subject matter described herein will be apparent from the description and drawings, and from the claims. While certain features of the currently disclosed subject matter are described for illustrative purposes, it should be readily understood that such features are not intended to be limiting. The claims that follow this disclosure are intended to define the scope of the protected subject matter.DESCRIPTION OF DRAWINGS

[0041] The accompanying drawings, which are incorporated in and constitute a part of this specification, show certain aspects of the subject matter disclosed herein and, together with the description, help explain some of the principles associated with the disclosed implementations.

[0042] FIG. 1 depicts an example of a battery cell including a protected current collector, in accordance with some example embodiments;

[0043] FIG. 2A depicts a schematic diagram illustrating an example of a functional current collector, in accordance with some example embodiments;

[0044] FIG. 2B depicts a schematic diagram illustrating another example of a functional current collector, in accordance with some example embodiments;

[0045] FIG. 2C depicts a schematic diagram illustrating another example of a functional current collector, in accordance with some example embodiments;

[0046] FIG. 2D depicts a schematic diagram illustrating another example of a functional current collector, in accordance with some example embodiments;

[0047] FIG. 2E depicts another example of a functional current collector, in accordance with some example embodiments;

[0048] FIG. 3 A depicts a table summarizing the observations of the negative electrode (anode) and positive electrode (cathode) made during the cell autopsies performed on Sample Cells I- VI, in accordance with some example embodiments;

[0049] FIG. 3B depicts a table of images of the negative electrode (anode) and positive electrode (cathode) captured during the cell autopsies performed on Sample Cells I- VI, in accordance with some example embodiments;

[0050] FIG. 4A depicts a graph illustrating the voltage and current profiles of Sample Cell I subjected to zero-voltage exposure at 200 ohms for seven days, in accordance with some example embodiments;

[0051] FIG. 4B depicts a graph illustrating the voltage and current profiles of SampleCell II subjected to -3 -volt exposure for one day and zero-voltage exposure at 200 ohms for one day, in accordance with some example embodiments;

[0052] FIG. 4C depicts a graph illustrating the voltage and current profiles of SampleCell III subjected to seven days of zero-voltage exposure at 200 ohms, in accordance with some example embodiments;

[0053] FIG. 4D depicts a graph illustrating the voltage and current profiles of Sample Cell IV subjected to seven days of zero-voltage exposure at 200 ohms, in accordance with some example embodiments;

[0054] FIG. 4E depicts a graph illustrating the voltage and current profiles of Sample Cell V subjected to -6-volt exposure for one day and zero-voltage exposure at 200 ohms for six days, in accordance with some example embodiments; and

[0055] FIG. 4F depicts a graph illustrating the voltage and current profiles of Sample Cell VI subjected to zero-voltage exposure at 200 ohms for seven days, in accordance with some example embodiments.

[0056] When practical, similar reference numbers denote similar structures, features, or elements.DETAILED DESCRIPTION

[0057] A metal ion battery cell, such as a lithium ion (Li+) battery cell, may be over discharged when the metal ion battery cell is discharged beyond a minimum voltage. Discharging a conventional metal ion battery cell to a low-voltage or zero-voltage state may destabilize the metal ion battery cell and cause a variety of irreversible damages to critical components of the battery cell. For example, the solid electrolyte interface (SEI) may decompose in a conventional metal ion battery cell that is discharged to a low-voltage state or a zero-voltage state. The degradation of the solid electrolyte interphase (SEI), which prevents electrolyte decomposition and sustain electrochemical reactions within the metal ion battery cell by enabling the transport of metal ions (e.g., lithium (Li) ions and / or the like) whileblocking the transport of electrons and further reaction between the electrolyte and negative electrode, may cause irreversible capacity loss at the metal ion battery cell. Moreover, a metal ion battery cell with a degraded solid electrolyte interphase (SEI) may exhibit a higher impendence and is thus able to provide less power to its load because more power is being dissipated as heat by the internal resistance of the metal ion battery cell.

[0058] Discharging a conventional metal ion battery cell to a low-voltage state or a zero-voltage stage may also cause the negative current collector of the metal ion battery cell to undergo an anodic corrosion, which depletes metal ions from the negative current collector. For example, copper (Cu) is a common material for negative current collectors in metal ion battery cells (e.g., lithium ion battery cells) due to copper’s high electrical conductivity and relatively low cost. However, copper (Cu), being a non-ferrous metal, is susceptible to corrosion when exposed to certain environmental triggers such as moisture, chemicals, acidity, temperature, and / or the like. A negative current collector constructed from copper (Cu) foil will gradually dissolve when a battery cell containing the copper (Cu) foil negative current collector is discharged below 1.5 volts. When the negative current collector undergoes anodic corrosion, metal ions from the negative current collector may dissolve into the electrolyte of the metal ion battery cell, travel through the separator, and accumulate on the positive electrode of the metal ion battery cell. Meanwhile, during a subsequent recharging of the battery cell, the depleted metal ions may again dissolve into the electrolyte before being deposited on the surface of the negative electrode. The resulting change in the internal morphology of the metal ion battery cell, which includes metal dendrites formed by the accumulation of metal ions on the negative electrode, may degrade the capacity of the metal ion battery cell. Moreover, an internal short circuit may develop within the metal ion battery cell when the metal dendrites formed on the surface of the negative electrode puncture the separator and come in contact with the positive electrode of the metal ion battery cell. While alternative materials may be lesssusceptible to corrosion than copper (Cu), they also tend to have inferior properties such as less electrically conductivity, higher cost, and / or the like. For instance, a battery cell with a titanium (Ti) foil negative current collector exhibits inferior performance compared to a battery cell with a copper (Cu) foil negative current collector due to titanium (Ti) having greater electrical resistance than copper (Cu). Aluminum (Al) foil is also an inferior current collector, particularly as a negative current collector in a lithium (Li) ion battery cell coupled with a graphite (C) or silicon (Si) based negative electrode (or anode) at least because of aluminum’s susceptibility to both corrosive reactions with the electrolyte in the battery cell and to forming an aluminum lithium alloy with the lithium (Li) that can accumulate at the surface of the aluminum (Al) negative current collector. Accordingly, when used as a positive current collector, aluminum (Al) foil require protection against lithium deposits.

[0059] Low-voltage and zero-voltage instability is detrimental for applications in which the metal ion battery cell is transported and stored for prolonged periods of time. For example, even in the absence of active use, a metal ion battery cell may still over discharge due to self-discharge, power consumption by a battery management system, and / or parasitic loads. In other cases, imbalances in a serially connected cluster of metal ion battery cells may inadvertently over discharge one or more of the metal ion battery cells in the cluster. The ability to preserve structural integrity while a metal ion battery cell is in a prolonged low- voltage or zero-voltage state may be desirable at least because fully or partially discharging the metal ion battery cell is a reliable mechanism for reducing fire risks during storage and transportation of the metal ion battery cell. That is, a metal ion battery cell that is discharged to a low-voltage or zero-voltage state is far less likely to catch fire than one that is more fully charged but, as noted, maintaining the metal ion battery cell in the low-voltage or zero-voltage state for a prolonged period of time may cause irreversible structural damage (e.g., solidelectrolyte interphase (SEI) decomposition, anodic corrosion, and / or the like) that renders the metal ion battery cell unusable.

[0060] Some conventional countermeasures against structural degradation in a low- voltage or zero-voltage state, such as pre-lithiating the negative electrode of a lithium (Li) ion battery cell, merely counteract the loss of lithium that occurs during the manufacturing process and are not economically viable at scale. Pre-lithiation, which includes applying a lithium powder to the surface of battery electrodes (e.g., anodes), can render the electrode highly reactive and thus require an inert manufacturing environment (e.g., dry room). Manufacturing complexity notwithstanding, conventional countermeasures against structural degradation in a low-voltage or zero-voltage state simply do not provide adequate protection against the corrosion of the negative electrode when a metal ion battery cell is in a low-voltage or a zerovoltage state for an extended period of time. For example, in the case of pre-lithiation, only the minimum quantity of surplus lithium (e.g., less than 20% by weight) necessary to compensate for the lithium that is lost during the initial charge and discharge cycle is used in order to avert the risk of converting a lithium ion battery cell into a lithium metal battery cell. The current collector remains vulnerable to anodic corrosion because this surplus lithium is exhausted during the initial charge and discharge cycle. As such, pre-lithiation alone is not sufficient to protect the current collector from anodic corrosion after the initial charge and discharge cycle. Furthermore, the instability of lithium outside of an inert manufacturing environment (e.g., dry room) renders the use of surplus lithium generally unsuitable for manufacturing at scale. Thus, what is lacking in the current state-of-the-art is a reliable and economical mechanism for preventing structural degradation in a metal ion battery cell that is maintained in a low-voltage or zero-voltage state for an extended period of time. Such mechanisms may be especially advantageous for high volume and low cost manufacturing ofmetal ion battery cells that can be transported and stored in a low-voltage or zero-voltage state for improved fire safety.

[0061] As noted, the chemical stability of negative current collectors in a corrosive environment (e.g., electrolyte) is critical for preserving the internal morphological integrity and optimal performance of metal ion battery cells. The ability to maintain a metal ion battery cell in a low- or zero-voltage state for extended periods of time without degradation of the constituent negative current collector is particularly advantageous for the safe transportation and long term storage of battery cells. In addition to exposure to a corrosive environment (e.g., electrolyte), negative current collectors in metal ion battery cells may also be subjected to mechanical stress and strain. For example, when formed from advanced negative electrode materials (e.g., nano silicon (Si)), the negative electrode in a metal ion battery cell may undergo significant expansion and contraction during the charging and discharging of the battery cell. The mechanical stress and strain arising from the expansion and contraction of the negative electrode may structurally degrade conventional negative current collectors. In more extreme circumstances, mechanical stress from the expansion and contraction of the negative electrode may cause the negative electrode to deform, fracture, or even fail. Accordingly, reinforcing or otherwise strengthening the negative current collectors in metal ion battery cells against mechanical stress and strain may further improve the performance and lifespan of the battery cells.

[0062] Various implementations of the present disclosure provide a metal ion battery cell that incorporates a functional current collector that, in addition to serving as a current collector (e.g., negative current collector coupled with the negative electrode (or anode) of the metal ion battery cell), also provides zero- or low voltage protection for the metal ion battery cell. For example, in some cases, various example embodiments of the functional current collector described herein may resist corrosion despite exposure to corrosive additives (e.g.,electrolytes) present in the metal ion battery cell containing the current collector while also being subjected to low- or zero-voltage conditions, such as the case when the battery cell is discharged for transportation or long term storage. Where a current collector (e.g., negative current collector) formed from copper (Cu) foil, for example, the protective layer may act as a physical barrier that prevents contact between the copper (Cu) foil and corrosive agents within the battery cell, such as the electrolyte. For a current collector (e.g., negative current collector) formed from aluminum (Al) foil, the protective layer may serve as a physical barrier that prevents contact with the electrolyte in the battery cell as well as lithium (Li) deposits from contacting the aluminum (Al) to form an aluminum lithium alloy on the surface of the aluminum (Al) foil. Furthermore, in some cases, various example embodiments of the functional current collector described herein may be reinforced to increase resistance against structural degradation caused by the expansion and contraction of the negative electrode (anode) during the charging and discharging of the battery cell.

[0063] FIG. 1 depicts a schematic diagram illustrating an example of a battery cell 100, in accordance with some example embodiments. Referring to FIG. 1, in some cases, the battery cell 100 may be a metal ion battery cell including, for example, a lithium (Li) ion battery cell, a sodium (Na) ion battery cell, a magnesium (Mg) ion battery cell, a zinc (Zn) ion battery cell, a calcium (Ca) ion battery cell, a potassium (K) ion battery cell, an aluminum (Al) ion battery cell, and / or the like. In some cases, the battery cell 100 may include a first current collector 111 coupled with a first electrode 113 and a second current collector 115 coupled with a second electrode 117 having an opposite polarity as the first electrode 113. In the example of the battery cell 100 shown in FIG. 1, a separator 119 may be interposed between the first electrode 113 and the second electrode 117. In some cases, the battery cell 100 may further include one or more electrolytes, such as an organic electrolyte, an aqueous electrolyte, a water in salt electrolyte, an ionic liquid electrolyte, a gel electrolyte, a solid electrolyte, and / or the like. Insome cases, one or both of the first electrode 113 and the second electrode 117 may be a composite electrode 120 containing a pressure induced transition (PIT) material combined with one or more electrode active materials. For example, in some cases, the first electrode 113 may be the negative electrode (or anode) of the battery cell 100, which may be particularly susceptible to significant volume changes (e.g., expansion, contraction, and / or the like) during the charging and discharging of the battery cell 100 when metal ions are inserted (or intercalated) and extracted (or deintercalated) therefrom. In some cases, one or both of the first current collector 111 and the second current collector 115 may be a functional current collector capable maintaining chemical stability, structural stability, and / or the like. As described in more details below, as a functional current collector, the first current collector 111 and / or the second current collector 115 may include a metal foil (e.g., copper (Cu) foil, aluminum (Al) foil, nickel (Ni) foil, silver (Ag) foil, stainless steel foil, and / or the like) whose surfaces are coated with one or more protective layers, sacrificial layers, cover layers, and / or the like.

[0064] FIG. 2A depicts a schematic diagram illustrating an example of a functional current collector 200, in accordance with some example embodiments. Referring to FIGS. 1 and 2A, in some cases, the functional current collector 200 may implement the first current collector 111 and / or the second current collector 115 of the battery cell 100 shown in FIG. 1. In some cases, the functional current collector 200 may include a metal foil 210 interposed between a first protective layer 202a and a second protective layer 202b. For example, in some cases, the first protective layer 202a may be coated on one surface of the metal foil 210 while the second protective layer 202b may be coated on an opposite surface of the metal foil 210. In some cases, the metal foil 210 may be a copper (Cu) foil, an aluminum (Al) foil, a nickel (Ni) foil, a silver (Ag) foil, a stainless steel foil, and / or the like. In some cases, one or both of the first protective layer 202a and the second protective layer 202b may be disposed on a respective surface of the metal foil 201 using a variety of deposition techniques including, forexample, atomic layer deposition (ALD), physical vapor deposition (PVD), vapor deposition, coating, and / or the like. In some cases, one or more layers of an electrode active material 210 may be deposited on a surface of the first protective layer 202a opposite the metal foil 201 to form, for example, an electrode (e.g., a negative electrode (anode), a positive electrode (cathode), and / or the like).

[0065] In some cases, one or more both of the first protective layer 202a and the second protective layer 202b may include one or more inert materials, such as an insert element, an inert compound, and / or the like. For instance, in some cases, the one or more inert materials forming the first protective layer 202a and the second protective layer 202b may include one or more metals, such as titanium (Ti), zinc (Zn), and / or the like. In some cases, the one or more inert materials may include one or more ceramic materials, such as titanium nitride (TiN), titanium carbide (TiC), titanium boride (TiB), titanium diboride (TiB?). In some cases, the one or more inert materials may include one or more semiconductor nanomaterials, such as zinc oxide (ZnCh), titanium dioxide (TiCh), carbon nitride (CN), and / or the like. In some cases, the one or more inert materials may include one or more of graphene, hexagonal boron nitride (hBN), layered double hydroxide, a diverse corrosion inhibitor, and / or the like.

[0066] In some cases, one or both of the first protective layer 202a and the second protective layer 202b may be a fluorocarbon coating (e.g., polytetrafluoroethylene (PTFE), Xylan, Teflon, Emralon, and / or the like), which may be an organic coating including a solid lubricant dispersed in an organic binder and dissolved in a mixture of solvents. In some cases, the fluorocarbon coating may be rendered corrosion-resistant when thermally cured to set the constituent synthetic binding material. Alternatively and / or additionally, one or both of the first protective layer 202a and the second protective layer 202b may be a diamond-like carbon (DLC) coating, a ceramic coating disposed by thermal spraying, or a graphene coating. In some cases, a diamond-like carbon (DLC) coating may be deposited by various technologiesincluding, for example, cathodic arc deposition or arc physical vapor deposition (arc-PVD), physical vapor deposition (PVD) sputtering, plasma assisted chemical vapor deposition (PACVD), and / or the like. Various performance characteristics, such as hydrogenated and non-hydrogenated diamond-like (DLC) coatings, can be achieved by selecting the appropriate technology and deposition parameters. In some cases, the first protective layer 202a and the second protective layer 202b may be annealed at a high temperature (e.g., 300 to 400°C).

[0067] Alternatively, instead of the one or more inert materials (e.g., inert element, inert compound, and / or the like), one or both of the first protective layer 202a and the second protective layer 202b may include one or more reactive materials, such as a reactive element, a reactive compound, and / or the like. For example, in some cases, one or both of the first protective layer 202a and the second protective layer 202b may include magnesium (Mg), tin (Sn), carbon (C), graphene, titanium oxide (TiCh), and / or the like. In some cases, one or both of the first protective layer 202a and the second protective layer 202b may between 10 nanometers (nm) to 5 micrometer ( m) in thickness. In some cases, one or both of the first protective layer 202a and the second protective layer 202b may be 1 micrometer (gm) in thickness. In some cases, the one or more reactive materials may serve as lithium reservoirs to protect the metal foil from being damaged in low- or zero-voltage conditions.

[0068] In some cases, one or both of the first protective layer 202a and the second protective layer 202b may include one or more nitrides, such as silicon nitride (SisN4, SixNy), titanium nitride (TiN), aluminum nitride (AIN), boron bitride (BN), zirconium nitride (ZrN), and / or the like. In some cases, one or both of the first protective layer 202a and the second protective layer 202b may be 1 nanometers (nm) to 500 nanometers (nm) in thickness. In some cases, one or both of the first protective layer 202a and the second protective layer 202b may be 15 nanometers (nm) in thickness.

[0069] In some cases, one or both of the first protective layer 202a and the second protective layer 202b may include one or more oxides, such as aluminum oxide (AI2O3, A1O), titanium oxide (TiCh, TiO), silicon oxide (SiCh, SiO), zinc oxide (ZnO), magnesium oxide (MgO), hafnium oxide (HfCh), tantalum oxide (Ta20s), chromium oxide (CrcCh), and / or the like. In some cases, one or both of the first protective layer 202a and the second protective layer 202b may be 1 nanometers (nm) to 1 micrometer (j m) in thickness. In some cases, one or both of the first protective layer 202a and the second protective layer 202b may be 20 nanometers (nm) in thickness.

[0070] In some cases, one or both of the first protective layer 202a and the second protective layer 202b may include one or more conductive metals, such as nickel (Ni), zinc (Zn), titanium (Ti), silver (Ag), gold (Au), and / or the like. In some cases, one or both of the first protective layer 202a and the second protective layer 202b may be 100 nanometers (nm) to 5 micrometer ( m) in thickness. In some cases, one or both of the first protective layer 202a and the second protective layer 202b may be 1 micrometer (gm) in thickness

[0071] FIG. 2B depicts a schematic diagram illustrating another example of the functional current collector 200, in accordance with some example embodiments. In the example shown in FIG. 2B, the functional current collector 200 includes a first sacrificial layer 203a and a second sacrificial layer 203b. For example, as shown in FIG. 2B, the first sacrificial layer is disposed on a surface of the first protective layer 202a opposite of the metal foil 201 while the second sacrificial layer 203b is disposed on a surface of the second protective layer 202b opposite of the metal foil 201. In some cases, one or more layers of the electrode active material 210 may be deposited on a surface of the first sacrificial layer 203 a opposite the first protective layer 202a and the metal foil 201 to form, for example, an electrode (e.g., a negative electrode (anode), a positive electrode (cathode), and / or the like).

[0072] A variation of the functional current collector 200 including the first sacrificial layer 203a and the second sacrificial layer 203b is shown in FIG. 2C. In the example of the functional current collector 220 shown in FIG. 2C, the first sacrificial layer 203a is interposed between the metal foil 201 and the first protective layer 202a while the second sacrificial layer 203b is interposed between the metal foil 201 and the second protective layer 202b. In some cases, one or both of the first sacrificial layer 203 a and the second sacrificial layer 203b may include one or more materials (e.g., zinc (Zn)) that participates in a sacrificial reaction, such as a reaction with a hydrofluoric acid (HF) produced by a non-air stable salt (e.g., lithium hexafluorophosphate (LiFPe)) in the electrolyte of the battery cell 100, thereby preventing the corrosion of the metal foil 201. In some cases, one or more layers of the electrode active material 210 may be deposited on a surface of the first cover layer 204a opposite the first protective layer 202a and the metal foil 201 to form, for example, an electrode (e.g., a negative electrode (anode), a positive electrode (cathode), and / or the like). In some cases, one or both of the first sacrificial layer 203 a and the second sacrificial layer 203b may include one or more materials with a lower decomposition voltage than the decomposition voltage of the metal foil 201. For example, where the metal foil is a copper (Cu) foil, one or both of the first sacrificial layer 203a and the second sacrificial layer 203b may include zinc (Zn). It should be appreciated that the inclusion of the first sacrificial layer 203a and the second sacrificial layer 203b may provide additional anticorrosive protection to the metal foil 201, the first protective layer 202a, and the second protective layer 202b.

[0073] FIG. 2D depicts a schematic diagram illustrating another example of the functional current collector 200, in accordance with some example embodiments. In the example shown in FIG. 2D, the functional current collector 200 may include a first cover layer 204a disposed on a surface of the first protective layer 202a opposite of the metal foil 201 and a second cover layer 204b disposed on a surface of the second protective layer 202b oppositeof the metal foil 201. In some cases, one or more layers of the electrode active material 210 may be deposited on a surface of the first protective layer 202a opposite the first adhesive promotion layer 205a and the metal foil 201 to form, for example, an electrode (e.g., a negative electrode (anode), a positive electrode (cathode), and / or the like). In some cases, the first cover layer 204a and the second cover layer 204b may serve as physical barriers that prevent the electrolyte in the battery cell 100 from contacting the first protective layer 202a and the second protective layer 202b. In some cases, the first cover layer 204a and the second cover layer 204b may further reinforce the anticorrosive protection provided by the first protective layer 202a and the second protective layer 202b to the metal foil 201. In some cases, one or both of the first cover layer 204a and the second cover layer 204b may include one or more composite materials (e.g., a polymer such as SBIR, polyethylene, polypropylene, and / or the like) and conductive additives (e.g., carbon black and / or the like). It should be appreciated that polymers, such as SBIR, polyethylene, are polypropylene, are resistant to corrosion by the electrolyte in the battery cell 100. Alternatively and / or additionally, one or both of the first cover layer 204a and the second cover layer 204b may be an oxide layer formed from, for example, aluminum oxide (AI2O3) and / or the like.

[0074] FIG. 2E depicts a schematic diagram illustrating another example of the functional current collector 200, in accordance with some example embodiments. In the example shown in FIG. 2E, the functional current collector 200 may include a first adhesive promotion layer 205a interposed between the first protective layer 202a and the metal foil 201. In some cases, as shown in FIG. 2E, the functional current collector 200 may further include a second adhesive promotion layer 205b interposed between the second protective layer 202b and the metal foil 201. In some cases, the first adhesive promotion layer 205a and the second adhesive promotion layer 205b may increase the bonding interaction between the metal foil 201 and each of the first protective layer 202a and the second protective layer 202b. In somecases, one or both of the first adhesive promotion layer 205a and the second adhesive promotion layer 205b may be one or more of a carbon (C) coating, a metalliferous coating (e.g., a SUper CArbon SLIDE (SUCASLIDE® DLC Coating)), an amorphous carbon coating (a-C:Me) from voestalpine eifeler, and / or the like. In some cases, one or both of the first adhesive promotion layer 205a and the second adhesive promotion layer 205b may be a physical vapor deposition (PVD) coating with friction-reducing properties. Furthermore, in some cases, one or both of the first adhesive promotion layer 205a and the second adhesive promotion layer 205b may be an epoxy coating (applied to a substrate pre-treated with 3-glycidoxy propyl silane), which exhibits both increased wet adhesion and improved resistance to cathodic disbonding.

[0075] Referring again to FIGS. 1 and 2A-E, in some cases, the metal foil 201 included in the functional current collector 200 implementing one or both of the first current collector 111 and the second current collector 115 in the battery cell 100 may be copper (Cu) foil. Where the metal foil 201 is copper (Cu) foil, one or both of the first protective layer 202a and the second protective layer 202b may be a nitride coating containing, for example, titanium nitride (TiN), cobalt nitride (CoN), zirconium nitride (ZrN), chromium nitride (CrN), and / or the like. In some cases, the nitride coating may increase the chemical stability of the functional current collector 200 by at least preventing the metal foil 201 from corroding in the presence of corrosive additives (e.g., electrolyte) in the battery cell 100, particularly in low- to zero-voltage conditions in which the battery cell 100 is discharged for transportation and long term storage. Furthermore, in some cases, the nitride coating may serve to reinforce the functional current collector 200, thereby increasing the structural stability of the functional current collector 200. For example, in some cases, the nitride coating may prevent the metal foil 201 from structural degradation (e.g., deformation, factures, and / or the like) caused by the mechanical stress and strain arising from the expansion and contraction of the first electrode 113 and / or the second electrode 117 during the charging and discharging of the battery cell 100.

[0076] Alternatively, the metal foil 201 in the functional current collector 200 implementing one or both of the first current collector 111 and the second current collector 115 in the battery cell 100 may be aluminum (Al) foil. In some cases, one or both of the first protective layer 202a and the second protective layer 202b disposed on the aluminum (Al) foil may be a nitride coating containing, for example, titanium nitride (TiN), cobalt nitride (CoN), zirconium nitride (ZrN), chromium nitride (CrN), and / or the like. In some cases, the nitride coating may prevent the formation of aluminum (Al) and lithium (Li) alloy, thus enabling the aluminum (Al) foil to be used as the negative current collector of the battery cell 100. When included in one or both of the first current collector 111 and the second current collector 115, the nitride coating may increase the chemical stability of one or both of the first current collector 111 and the second current collector 115 of the battery cell 100, particularly in low- to zero-volt conditions. Furthermore, the presence of the nitride coating in one or both of the first current collector 111 and the second current collector 115 may increase the structural stability of one or both of the first current collector 111 and the second current collector 115, including the ability to resist structural degradation (e.g., deformation, factures, and / or the like) caused by the mechanical stress and strain arising from the expansion and contraction of the first electrode 113 and / or the second electrode 117 during the charging and discharging of the battery cell 100. In some cases, the use of aluminum (Al) foil instead of copper (Cu) foil may also be advantageous from a cost perspective of the battery cell 100 as copper (Cu) is significantly more expensive than aluminum (Al).

[0077] Table 1 below summarizes various examples of coatings as well as the corresponding deposition techniques and functionality. It should be appreciated that the different types of coatings shown in Table 1 may implement implementing one or more of the first protective layer 202a, the second protective layer 202b, the first sacrificial layer 203a, thesecond sacrificial layer 203b, the first cover layer 204a, the second cover layer 204b, the first adhesive promotion layer 205a, the second adhesive promotion layer 205b, and / or the like.

[0078] Table 1

[0079] Table 2 below summarizes various examples of plasma and vapor deposition coating techniques as well as the types of coatings resulting therefrom. It should be appreciated that the different types of coatings shown in Table 1 may implement implementing one or more of the first protective layer 202a, the second protective layer 202b, the first sacrificial layer 203a, the second sacrificial layer 203b, the first cover layer 204a, the second cover layer 204b, the first adhesive promotion layer 205a, the second adhesive promotion layer 205b, and / or the like.

[0080] Table 2

[0081] In some cases, one or more of the first protective layer 202a, the second protective layer 202b, the first sacrificial layer 203a, the second sacrificial layer 203b, the first cover layer 204a, the second cover layer 204b, the first adhesive promotion layer 205a, and the second adhesive promotion layer 205b may be applied using one or more plasma-based coating techniques, which are surface coating methods that produce coating films by injecting powder particles into an ionized gas plasma. Examples of plasma-based coating techniques include plasma or thermal spray coating (e.g., atmospheric plasma spray (APS), vacuum plasma spray (VPS), low-pressure plasma spray (LPPS)), plasma immersion ion implantation (Pill), plasma- enhanced chemical vapor deposition (PECVD), plasma electrolytic oxidation (PEO / MAO), reactive plasma sputtering, and / or the like. Plasma-based coating techniques may achieve a variety of coating types including, for example, ceramics (e.g., oxides such as AI2O3 and ZrCE, carbides such as TiC and SiC, and nitrides such as TiN, CrN), metals (e.g., MCrAlY alloys, stainless steels), polymers (e.g., parylene-like plasma polymers), functional films (e.g., hydrophobic films, biocompatible films, optical films).

[0082] In some cases, one or more of the first protective layer 202a, the second protective layer 202b, the first sacrificial layer 203a, the second sacrificial layer 203b, the first cover layer 204a, the second cover layer 204b, the first adhesive promotion layer 205a, and thesecond adhesive promotion layer 205b may be applied using one or more vapor deposition techniques, which deposit thin, durable coatings to surfaces by vaporizing a coating material and depositing it onto a substrate. Physical vapor deposition (PVD) is one type of vapor deposition technique that includes thermal evaporation, electron beam evaporation, sputtering (e.g., direct current (DC), radio frequency (RF), magnetron, ion beam), arc vapor deposition, pulsed laser deposition (PLD), and / or the like. Chemical vapor deposition (CVD) is another type of vapor deposition technique that includes standard chemical vapor deposition (CVD), low pressure chemical vapor deposition (LPCVD), plasma enhanced chemical vapor deposition (PECVD), metal organic chemical vapor deposition (MOCVD), atomic layer deposition (ALD), and / or the like. Vapor deposition coating techniques may achieve a variety of coating types including, for example, metals (e.g., aluminum (Al), titanium (Ti), gold (Au)), nitrides (e.g., TiN, CrN, AlTiN), carbides (e.g., SiC, TiC), oxides (e.g., SiCE, AI2O3, TiCE, ElfCE)), diamond and diamond-like carbon (DLC) films, semiconductor films (e.g., silicon (Si), gallium nitride (GaN), indium phosphide (InP)), and / or the like.

[0083] Examples of Coated Copper (Cu) Foil Functional Collectors in Lithium (Li) Ion Battery Cells

[0084] Sample Negative Electrode I: Titanium Nitride (TiN) and Graphite (C)

[0085] Sample negative electrode I, which may implement one of the first electrode113 or the second electrode 117, was fabricated by first forming a functional current collector, such as the functional current collector 200. The functional current collector was formed by coating approximately 50 nanometers (nm) of titanium nitride (TiN) on copper (Cu) foil (e.g., the metal foil 201) that is approximately 9 micrometers ( im) in thickness. The formation ofSample Negative Electrode I further included dissolving a certain quantity of binder in deionized water before adding a conductive additive and mixing for 30 minutes at 6500 revolutions-per-minute. Graphite and a carbon composite were added to the resulting solutionand mixed for 60 minutes at 6500 revolutions-per-minute. Additional water was added to adjust the viscosity and form a flowable slurry. The slurry was then coated on the functional current collector using an automatic coater. The resulting Sample Negative Electrode I was calendared to a target thickness and cut to 31 millimeters in width and 44 millimeters in length with a 6-millimeter wide piece of copper (Cu) foil as the negative tab.

[0086] Sample Negative Electrode II: Zirconium Nitride (ZrN) and Silicon Oxide (SiO)

[0087] Sample negative electrode II, which may implement one of the first electrode 113 or the second electrode 117, was fabricated by first forming a functional current collector, such as the functional current collector 200. The functional current collector was formed by coating ~50 nanometers (nm) of zirconium nitride (ZrN) on copper (Cu) foil (e.g., the metal foil 201) that is approximately 9 micrometers ( im) in thickness. The formation of Sample Negative Electrode II further included dissolving a certain quantity of binder in deionized water before adding a conductive additive and mixing for 30 minutes at 6500 revolutions-per-minute. Silicon oxide (SiO) powder and a carbon composite were added to the resulting solution and mixed for 60 minutes at 6500 revolutions-per-minute. Additional water was added to adjust the viscosity and form a flowable slurry. The slurry was then coated on the functional current collector using an automatic coater. The resulting Sample Negative Electrode II was calendared to a target thickness and cut to 31 millimeters in width and 44 millimeters in length with a 6-millimeter wide piece of copper (Cu) foil as the negative tab.

[0088] Sample Negative Electrode III: Chromium Nitride (CrN) and Silicon Oxide (SiO)

[0089] Sample negative electrode III, which may implement one of the first electrode113 or the second electrode 117, was fabricated by first forming a functional current collector,such as the functional current collector 200. The functional current collector was formed by coating ~50 nanometers (nm) of chromium nitride (CrN) on copper (Cu) foil (e.g., the metal foil 201) that is approximately 9 micrometers ( m) in thickness. The formation of Sample Negative Electrode III further included dissolving a certain quantity of binder in deionized water before adding a conductive additive and mixing for 30 minutes at 6500 revolutions-per- minute. Silicon oxide (SiO) powder and a carbon composite were added to the resulting solution and mixed for 60 minutes at 6500 revolutions-per-minute. Additional water was added to adjust the viscosity and form a flowable slurry. The slurry was then coated on the functional current collector using an automatic coater. The resulting Sample Negative Electrode III was calendared to a target thickness and cut to 31 millimeters in width and 44 millimeters in length with a 6-millimeter wide piece of copper (Cu) foil as the negative tab.

[0090] Sample Negative Electrode IV: Titanium Nitride (TiN) and Silicon Carbide £SiC)

[0091] Sample negative electrode IV, which may implement one of the first electrode 113 or the second electrode 117, was fabricated by first forming a functional current collector, such as the functional current collector 200. The functional current collector was formed by coating ~50 nanometers (nm) of titanium nitride (TiN) on copper (Cu) foil (e.g., the metal foil 201) that is approximately 9 micrometers (gm) in thickness. The formation of Sample Negative Electrode IV further included dissolving a certain quantity of binder in deionized water before adding a conductive additive and mixing for 30 minutes at 6500 revolutions-per- minute. Silicon carbide (SiC) powder and a carbon composite were added to the resulting solution and mixed for 60 minutes at 6500 revolutions-per-minute. Additional water was added to adjust the viscosity and form a flowable slurry. The slurry was then coated on the functional current collector using an automatic coater. The resulting Sample Negative Electrode IV wascalendared to a target thickness and cut to 31 millimeters in width and 44 millimeters in length with a 6-millimeter wide piece of copper (Cu) foil as the negative tab.

[0092] Sample Negative Electrode V: Zirconium Nitride (ZrN) and Silicon Carbide (SiC)

[0093] Sample negative electrode V, which may implement one of the first electrode 113 or the second electrode 117, was fabricated by first forming a functional current collector, such as the functional current collector 200. The functional current collector was formed by coating ~50 nanometers (nm) of zirconium nitride (ZrN) on copper (Cu) foil (e.g., the metal foil 201) that is approximately 9 micrometers ( im) in thickness. The formation of Sample Negative Electrode V further included dissolving a certain quantity of binder in deionized water before adding a conductive additive and mixing for 30 minutes at 6500 revolutions-per-minute. Silicon carbide (SiC) powder and a carbon composite were added to the resulting solution and mixed for 60 minutes at 6500 revolutions-per-minute. Additional water was added to adjust the viscosity and form a flowable slurry. The slurry was then coated on the functional current collector using an automatic coater. The resulting Sample Negative Electrode V was calendared to a target thickness and cut to 31 millimeters in width and 44 millimeters in length with a 6-millimeter wide piece of copper (Cu) foil as the negative tab.

[0094] Sample Negative Electrode VI: Chromium Nitride (CrN) and Silicon Carbide (SiC)

[0095] Sample negative electrode VI, which may implement one of the first electrode 113 or the second electrode 117, was fabricated by first forming a functional current collector, such as the functional current collector 200. The functional current collector was formed by coating ~50 nanometers (nm) of chromium nitride (CrN) on copper (Cu) foil (e.g., the metal foil 201) that is approximately 9 micrometers ( m) in thickness. The formation of SampleNegative Electrode VI further included dissolving a certain quantity of binder in deionized water before adding a conductive additive and mixing for 30 minutes at 6500 revolutions-per- minute. Silicon carbide (SiC) powder and a carbon composite were added to the resulting solution and mixed for 60 minutes at 6500 revolutions-per-minute. Additional water was added to adjust the viscosity and form a flowable slurry. The slurry was then coated on the functional current collector using an automatic coater. The resulting Sample Negative Electrode VI was calendared to a target thickness and cut to 31 millimeters in width and 44 millimeters in length with a 6-millimeter wide piece of copper (Cu) foil as the negative tab.

[0096] Sample Positive Electrode: Nickle Manganese Cobalt (NMC)

[0097] Sample positive electrode, which may implement the other one of the first electrode 113 or the second electrode 117, was formed by dissolving a certain quantity of polyvinylidene difluoride (PVDF) in N-methylpyrrolidone (NMP) to prepare an 8% polymer solution. A certain quantity of carbon black was added to the 8% polymer solution and mixed for 30 minutes at 6500 revolutions-per-minute to form a slurry. A certain quantity of high nickel lithium nickel manganese cobalt oxide was added the slurry and mixed for 30 minutes at 6500 revolutions-per-minute with additional N-methylpyrrolidone (NMP) added to adjust viscosity to achieve a flowable slurry. The flowable slurry was coated onto an aluminum (Al) foil that is approximately 15 micrometers ( / / m) in thickness using an automatic coating machine with the first heat zone set to approximately 80°C and the second heat zone set to approximately 130°C to evaporate the N-methylpyrrolidone (NMP). Sample positive electrode was then calendared to a target thickness and cut to 31 millimeters in width and 44 millimeters in length with a 6-millimeter wide piece of aluminum (Al) foil as the positive tab.

[0098] Sample Cell I

[0099] The jelly flat of Sample Cell I was formed by stacking Sample Negative Electrode I, the Sample Positive Electrode, and a separator interposed therebetween using a stacking machine. The jelly flat was inserted into a case (e.g., a soft pouch and / or the like). The 6-millimeter wide copper (Cu) negative tab from Sample Negative Electrode I was welded to a nickel (Ni) tab while the 6-millimeter wide aluminum (Al) positive tab from the Sample Positive Electrode was welded to an aluminum (Al) tab by resistance welding. The unfinished Sample Cell I was dried at 80°C for at least 12 hours before the dried Sample Cell I is filled with electrolyte and sealed. Sample Cell I was then aged 24 hours at room temperature before being subjected to a formation process that includes being charged to 4.25 volts at 1 milliampere (mA) and discharged to 2 volts at 1 milliampere (mA).

[0100] Sample Cell II

[0101] The jelly flat of Sample Cell II was formed by stacking Sample Negative Electrode II, the Sample Positive Electrode, and a separator interposed therebetween using a stacking machine. The jelly flat was inserted into a case (e.g., a soft pouch and / or the like). The 6-millimeter wide copper (Cu) negative tab from Sample Negative Electrode II was welded to a nickel (Ni) tab while the 6-millimeter wide aluminum (Al) positive tab from the Sample Positive Electrode was welded to an aluminum (Al) tab by resistance welding. The unfinished Sample Cell II was dried at 80°C for at least 12 hours before the dried Sample Cell II is filled with electrolyte and sealed. Sample Cell II was then aged 24 hours at room temperature before being subjected to a formation process that includes being charged to 4.25 volts at 1 milliampere (mA) and discharged to 2 volts at 1 milliampere (mA).

[0102] Sample Cell III

[0103] The jelly flat of Sample Cell III was formed by stacking Sample NegativeElectrode III, the Sample Positive Electrode, and a separator interposed therebetween using astacking machine. The jelly flat was inserted into a case (e.g., a soft pouch and / or the like). The 6-millimeter wide copper (Cu) negative tab from Sample Negative Electrode III was welded to a nickel (Ni) tab while the 6-millimeter wide aluminum (Al) positive tab from the Sample Positive Electrode was welded to an aluminum (Al) tab by resistance welding. The unfinished Sample Cell III was dried at 80°C for at least 12 hours before the dried Sample CellIII is filled with electrolyte and sealed. Sample Cell III was then aged 24 hours at room temperature before being subjected to a formation process that includes being charged to 4.25 volts at 1 milliampere (mA) and discharged to 2 volts at 1 milliampere (mA).

[0104] Sample Cell IV

[0105] The jelly flat of Sample Cell IV was formed by stacking Sample Negative Electrode IV, the Sample Positive Electrode, and a separator interposed therebetween using a stacking machine. The jelly flat was inserted into a case (e.g., a soft pouch and / or the like). The 6-millimeter wide copper (Cu) negative tab from Sample Negative Electrode IV was welded to a nickel (Ni) tab while the 6-millimeter wide aluminum (Al) positive tab from the Sample Positive Electrode was welded to an aluminum (Al) tab by resistance welding. The unfinished Sample Cell IV was dried at 80°C for at least 12 hours before the dried Sample CellIV is filled with electrolyte and sealed. Sample Cell IV was then aged 24 hours at room temperature before being subjected to a formation process that includes being charged to 4.25 volts at 1 milliampere (mA) and discharged to 2 volts at 1 milliampere (mA).

[0106] Sample Cell V

[0107] The jelly flat of Sample Cell V was formed by stacking Sample NegativeElectrode V, the Sample Positive Electrode, and a separator interposed therebetween using a stacking machine. The jelly flat was inserted into a case (e.g., a soft pouch and / or the like). The 6-millimeter wide copper (Cu) negative tab from Sample Negative Electrode V waswelded to a nickel (Ni) tab while the 6-millimeter wide aluminum (Al) positive tab from the Sample Positive Electrode was welded to an aluminum (Al) tab by resistance welding. The unfinished Sample Cell V was dried at 80°C for at least 12 hours before the dried Sample CellV is filled with electrolyte and sealed. Sample Cell V was then aged 24 hours at room temperature before being subjected to a formation process that includes being charged to 4.25 volts at 1 milliampere (mA) and discharged to 2 volts at 1 milliampere (mA).

[0108] Sample Cell VI

[0109] The jelly flat of Sample Cell VI was formed by stacking Sample Negative Electrode VI, the Sample Positive Electrode, and a separator interposed therebetween using a stacking machine. The jelly flat was inserted into a case (e.g., a soft pouch and / or the like). The 6-millimeter wide copper (Cu) negative tab from Sample Negative Electrode VI was welded to a nickel (Ni) tab while the 6-millimeter wide aluminum (Al) positive tab from the Sample Positive Electrode was welded to an aluminum (Al) tab by resistance welding. The unfinished Sample Cell VI was dried at 80°C for at least 12 hours before the dried Sample CellVI is filled with electrolyte and sealed. Sample Cell VI was then aged 24 hours at room temperature before being subjected to a formation process that includes being charged to 4.25 volts at 1 milliampere (mA) and discharged to 2 volts at 1 milliampere (mA).

[0110] Zero Volt Exposure (SVE) Test Results

[0111] Sample Cell I was discharged at 0.1 amperes to -2.5 volts for 10 minutes before being further discharged at 200 ohms to 0 volts for 7 days. The voltage and current profiles of Sample Cell I being subjected to zero-voltage exposure is shown in FIG. 4A. Furthermore, as shown in Table 350 of FIG. 3B, cell autopsy analysis demonstrated that Sample Negative Electrode I exhibits both structural degradation in the form of fractures as well as chemical degradation, with the copper (Cu) foil having disintegrated and re-deposited on the SamplePositive Electrode. The results for Sample Cell I shows that a 50-nanometers (nm) coating of titanium nitride (TiN) was not sufficient to protect a 6-micrometer (pm) thick copper (Cu) foil with a graphite negative electrode subjected to low- voltage (-2.5V) to zero- voltage (OV) conditions for 7 days, which are extremely harsh conditions unlikely to be encountered in real world applications. In real world applications, the discharge current to zero volt (OV) is extremely small (e.g., < 0.25C or 5 hour charging rate). Accordingly, an exemplary coating of titanium nitride (TiN) may be 20-300 micrometer (pm) thick, 50-200 micrometer (pm) thick, or 80-150 micrometer (pm) thick.

[0112] Sample Cell II was discharged at 0.2 amperes to -3.5 volts for 1 minute before being further discharged at 200 ohms to -3 volts for 1 day and at 0 volts for 1 day. The voltage and current profiles of Sample Cell II being subjected to zero-voltage exposure is shown in FIG. 4B. Furthermore, as shown in Table 350 of FIG. 3B, cell autopsy analysis demonstrated that Sample Negative Electrode I exhibits both structural degradation in the form of fractures as well as chemical degradation, with the copper (Cu) foil having disintegrated and redeposited on the Sample Positive Electrode. The results for Sample Cell I shows that a 50- nanometers (nm) coating of titanium nitride (TiN) may not be sufficient to protect a 6- micrometer (pm) thick copper (Cu) foil with a graphite negative electrode subjected to low- voltage (-2.5V) to zero-voltage (0V) conditions for 7 days. Those, however, are extremely harsh conditions unlikely to be encountered in real world applications. In real world applications, the discharge current to zero volt (0V) is extremely small (e.g., < 0.25C or 5 hour charging rate). Accordingly, an exemplary coating of titanium nitride (TiN) may be 20-300 micrometer (pm) thick, 50-200 micrometer (pm) thick, or 80-150 micrometer (pm) thick.

[0113] Sample Cell III was discharged at 0.01 amperes to -0.5 volts for 5 minutes before being further discharged at 200 ohms to 0 volts for 7 days. The voltage and current profiles of Sample Cell III being subjected to zero-voltage exposure is shown in FIG. 4C.Furthermore, as shown in Table 350 of FIG. 3B, cell autopsy analysis demonstrated that both Sample Negative Electrode III and the Sample Positive Electrode withstood zero volt exposure (SVE) without structural or chemical degradation. That is, both Sample Negative Electrode III and the Sample Positive Electrode remained intact, without any factures or delamination from the separator. Furthermore, no disintegration of the copper (Cu) foil was observed and no deposit of copper (Cu) was present on the Sample Positive Electrode. Accordingly, ~50 nanometers (nm) of a chromium nitride (CrN) coating is sufficient to protect a 6-micrometer (pm) thick copper (Cu) foil with a silicon oxide (SiO) negative electrode under subjected to low-voltage (-0.5V) to zero-votlage (0V) conditions for 7 days. As noted, these are extremely harsh discharging conditions unlikely to be encountered in real world applications. In real world applications, the discharge current to zero volt (0V) is extremely small (e.g., < 0.25C or 5 hour charging rate). Accordingly, an exemplary coating of chromium nitride (CrN) may be 20-300 micrometer (pm) thick, 50-200 micrometer (pm) thick, or 80-150 micrometer (pm) thick.

[0114] Sample Cell IV was discharged at 0.01 amperes to -0.5 volts for 5 minutes before being further discharged at 200 ohms to 0 volts for 7 days. The voltage and current profiles of Sample Cell IV being subjected to zero-voltage exposure is shown in FIG. 4D. Furthermore, as shown in Table 350 of FIG. 3B, cell autopsy analysis demonstrated that although Sample Negative Electrode IV exhibits some structural degradation in the form delamination from the separator, the Sample Positive Electrode is free from copper (Cu) deposits. In other words, no disintegration of the copper (Cu) foil was observed. Nevertheless, ~50 nanometers (nm) of a titanium nitride (TiN) coating is insufficient to protect a 6- micrometer (pm) thick copper (Cu) foil with a silicon carbide (SiC) negative electrode under subjected to low-voltage (-0.5V) to zero-votlage (0V) conditions for 7 days. Those, however, are extremely harsh conditions unlikely to be encountered in real world applications. In realworld applications, the discharge current to zero volt (OV) is extremely small (e.g., < 0.25C or5 hour charging rate). Accordingly, an exemplary coating of silicon carbide (SiC) may be 20-300 micrometer (pm) thick, 50-200 micrometer (pm) thick, or 80-150 micrometer (pm) thick.

[0115] Sample Cell V was discharged at 0.01 amperes to -6 volts for 5 minutes before being further discharged at 200 ohms to -6 vots for 1 day and to 0 volts for 6 days. The voltage and current profiles of Sample Cell V being subjected to zero-voltage exposure is shown in FIG. 4E. Furthermore, as shown in Table 350 of FIG. 3B, cell autopsy analysis demonstrated that both Sample Electrode V and the Sample Positive Electrode exhibit some structural degradation in the form of delamination from the separator. However, no disintegration of the copper (Cu) foil was observed and no deposit of copper (Cu) was present on the Sample Positive Electrode. Nevertheless, ~50 nanometers (nm) of a zirconium nitride (ZrN) coating may not be sufficient to protect a 6-micrometer (pm) thick copper (Cu) foil with a silicon carbide (SiC) negative electrode under subjected to low-voltage (-0.5V) to zero-votlage (0V) conditions for 7 days. Those, however, are extremely harsh conditions unlikely to be encountered in real world applications. In real world applications, the discharge current to zero volt (0V) is extremely small (e.g., < 0.25C or 5 hour charging rate). Accordingly, an exemplary coating of zirconium nitride (ZrN) may be 20-300 micrometer (pm) thick, 50-200 micrometer (pm) thick, or 80-150 micrometer (pm) thick.

[0116] Sample Cell VI was discharged at 0.01 amperes to -0.5 volts for 5 minutes before being further discharged at 200 ohms to 0 volts for 7 days. The voltage and current profiles of Sample Cell VI being subjected to zero-voltage exposure is shown in FIG. 4E. Furthermore, as shown in Table 350 of FIG. 3B, cell autopsy analysis demonstrated that both Sample Negative Electrode VI and the Sample Positive Electrode exhibit some structural degradation in the form of delamination from the separator. However, no chemical degradation was observed, including no disintegration of the copper (Cu) foil or deposits of copper (Cu) onthe Sample Positive Electrode. Nevertheless, ~50 nanometers (nm) of a chromium nitride(CrN) coating may be insufficient to protect a protect a 6-micrometer (pm) copper (Cu) thick with a silicon carbide (SiC) negative electrode under zero voltage (OV) conditions for 7 days. Those, however, are extremely harsh conditions unlikely to be encountered in real world applications. In real world applications, the discharge current to zero volt (OV) is extremely small (e.g., < 0.25C or 5 hour charging rate). Accordingly, an exemplary coating of chromium nitride (CrN) may be 20-300 micrometer (pm) thick, 50-200 micrometer (pm) thick, or 80-150 micrometer (pm) thick.

[0117] In view of the foregoing, chromium nitride (CrN) appears to exhibit more superior anticorrosion properties under zero voltage exposure (ZVE), as neither the positive electrode nor the negative electrode exhibits any fractures and no disintegration of the copper (Cu) foil was observed after 7 days of zero voltage exposure. Other materials exhibits either structural degradation in the form of delamination or fracturing of the negative electrode or chemical degradation in the form of copper (Cu) deposits on the positive electrode. Also, silicon oxide (SiO) exhibits superior computability with zero voltage tolerance than silicon carbide (SiC) and graphite. This is shown in Table 300 of FIG. 3A and Table 350 of FIG.. 3B. Nevertheless, it should be appreciated that the foregoing discharging conditions are extremely harsh and unlikely to be encountered in real world applications. In real world applications where the discharge current to zero volt (0V) is extremely small (e.g., < 0.25C or 5 hour charging rate), other materials described herein, in carbides and other nitrides, may provide sufficient anticorrosive protection.

[0118] As noted, chromium nitride (CrN) exhibits superior anticorrosive properties than zirconium nitride (ZrN) and titanium nitride (TiN). These results are consistent the chemical and structural stability of chromium nitride (CrN) under extreme high chloride conditions. It should be appreciated that the thickness of the chromium nitride (CrN) coatingmay affect its anticorrosive properties. Moreover, the thickness of the protective coating, regardless of the constituent material, may be application dependent. For example, a 50- nanometer (nm) thick coating may not be sufficient to protect negative electrodes and the constituent metal foil negative current collectors under negative voltage conditions. Instead, some negative voltage conditions may require a 100-nanometer, a 200-nanometer, a 500- nanometer thick chromium nitride (CrN) coating. However, negative voltage conditions may be rare in real world applications. Accordingly, in some cases, an exemplary coating of chromium nitride (CrN) (or other materials described herein) may be 20-300 micrometer (pm) thick, 50-200 micrometer (pm) thick, or 80-150 micrometer (pm) thick.

[0119] In the descriptions above and in the claims, phrases such as “at least one of’ or “one or more of’ may occur followed by a conjunctive list of elements or features. The term “and / or” may also occur in a list of two or more elements or features. Unless otherwise implicitly or explicitly contradicted by the context in which it used, such a phrase is intended to mean any of the listed elements or features individually or any of the recited elements or features in combination with any of the other recited elements or features. For example, the phrases “at least one of A and B;” “one or more of A and B;” and “A and / or B” are each intended to mean “A alone, B alone, or A and B together.” A similar interpretation is also intended for lists including three or more items. For example, the phrases “at least one of A, B, and C;” “one or more of A, B, and C;” and “A, B, and / or C” are each intended to mean “A alone, B alone, C alone, A and B together, A and C together, B and C together, or A and B and C together.” Use of the term “based on,” above and in the claims is intended to mean, “based at least in part on,” such that an unrecited feature or element is also permissible.

[0120] The subject matter described herein can be embodied in systems, apparatus, methods, and / or articles depending on the desired configuration. The implementations set forth in the foregoing description do not represent all implementations consistent with the subjectmatter described herein. Instead, they are merely some examples consistent with aspects related to the described subject matter. Although a few variations have been described in detail above, other modifications or additions are possible. In particular, further features and / or variations can be provided in addition to those set forth herein. For example, the implementations described above can be directed to various combinations and subcombinations of the disclosed features and / or combinations and subcombinations of several further features disclosed above. In addition, the logic flows depicted in the accompanying figures and / or described herein do not necessarily require the particular order shown, or sequential order, to achieve desirable results. Other implementations may be within the scope of the following claims.

Claims

CLAIMSWhat is claimed is:

1. A battery cell, comprising: an electrolyte; a positive electrode comprising one or more layers of a positive electrode active material deposited on a positive current collector; a negative electrode comprising one or more layers of a negative electrode active material deposited on a negative current collector; and a separator interposed between the positive electrode and the negative electrode, wherein at least one of the positive current collector and the negative current collector comprise a functional current collector having a metal foil interposed between a first protective layer and a second protective layer, and wherein the first protective layer and the second protective layer prevent a corrosion of the metal foil while the battery cell is in a low-voltage state or a zero-voltage state.

2. The battery cell of claim 1, wherein the first protective layer and the second protective layer prevents a structural degradation of the metal foil caused by an expansion and contraction of the positive electrode and / or the negative electrode during a charging and discharging of the battery cell.

3. The battery cell of any of claims 1 to 2, wherein the functional current collector further includes a first sacrificial layer.

4. The battery cell of claim 3, wherein the first sacrificial layer is interposed between the first protective layer and one or more layers of electrode active material.

5. The batery cell of claim 3, wherein the first sacrificial layer is interposed between the first protective layer and the metal foil.

6. The batery cell of any of claims 3 to 5, wherein the functional current collector further includes a second sacrificial layer.

7. The batery cell of claim 6, wherein the second sacrificial layer is disposed on a surface of the second protective layer opposite the metal foil.

8. The battery cell of claim 6, wherein the second sacrificial layer is interposed between the metal foil and the second protective layer.

9. The batery cell of any of claims 1 to 8, wherein the functional current collector further includes a first cover layer and a second cover layer, wherein the first cover layer is interposed between the first protective layer and one or more layers of electrode active material, and wherein the second cover layer is disposed on a surface of the second protective layer opposite the metal foil.

10. The batery cell of any of claims 1 to 9, wherein the functional current collector further includes a first adhesive promotion layer and a second adhesive promotion layer, wherein the first adhesive promotion layer is interposed between the first protective layer and the metal foil, and wherein the second adhesive promotion layer is interposed between the metal foil and the second protective layer.

11. The battery cell of any of claims 1 to 10, wherein one or both of the first protective layer and the second protective layer include one or more inert materials.

12. The battery cell of claim 11, wherein the one or more inert materials include one or more metals.

13. The battery cell of claim 12, wherein the one or more metals include titanium(Ti) and / or zinc (Zn).

14. The batery cell of any of claims 11 to 13, wherein the one or more inert materials include one or more ceramic materials.

15. The battery cell of claim 14, wherein the one or more ceramic materials include titanium nitride (TiN), titanium carbide (TiC), titanium boride (TiB), and / or titanium diboride (TiB2).

16. The batery cell of any of claims 11 to 15, wherein the one or more inert materials include one or more semiconductor nanomaterials.

17. The battery cell of claim 16, wherein the one or more semiconductor nanomaterials include zinc oxide (ZnO2), titanium dioxide (TiO2), and / or carbon nitride (CN).

18. The batery cell of any of claims 11 to 17, wherein the one or more inert materials include graphene, hexagonal boron nitride (hBN), layered double hydroxide, and / or a diverse corrosion inhibitor.

19. The battery cell of any of claims 1 to 18, wherein one or both of the first protective layer and the second protective layer comprise a fluorocarbon coating.

20. The battery cell of any of claims 1 to 19, wherein one or both of the first protective layer and the second protective layer comprise a diamond-like carbon (DLC) coating.

21. The battery cell of any of claims 1 to 20, wherein one or both of the first protective layer and the second protective layer include one or more reactive materials.

22. The batery cell of claim 21, wherein the one or more reactive materials include magnesium (Mg), tin (Sn), carbon (C), graphene, and / or titanium oxide (TiCh).

23. The battery cell of any of claims 1 to 22, wherein one or both of the first protective layer and the second protective layer include one or more nitrides.

24. The batery cell of claim 23, wherein the one or more nitrides include silicon nitride (SisN-t, SixNy), titanium nitride (TiN), aluminum nitride (AIN), boron bitride (BN), and / or zirconium nitride (ZrN).

25. The battery cell of any of claims 1 to 24, wherein one or both of the first protective layer and the second protective layer include one or more oxides.

26. The battery cell of claim 25, wherein the one or more oxides include aluminum oxide (AI2O3, A1O), titanium oxide (TiCh, TiO), silicon oxide (SiCh, SiO), zinc oxide (ZnO), magnesium oxide (MgO), hafnium oxide (HfCh), tantalum oxide (Ta20s), and / or chromium oxide (CrcCh).

27. The battery cell of any of claims 1 to 26, wherein one or both of the first protective layer and the second protective layer include one or more conductive metals.

28. The batery cell of claim 27, wherein the one or more conductive metals include nickel (Ni), zinc (Zn), titanium (Ti), silver (Ag), and / or gold (Au).

29. The battery cell of any of claims 1 to 28, wherein one or both of the first protective layer and the second protective layer include one or more metal alloys.

30. The batery cell of claim 29, wherein the one or more metal alloys include nickel chromium (NiCr), iron chromium (FeCr), aluminum chromium (AlCr), zinc aluminum (ZnAl), and / or titanium aluminum (TiAl).

31. The battery cell of any of claims 1 to 30, wherein the first protective layer and the second protective layer are 20-300 micrometer (pm) thick, 50-200 micrometer (pm) thick, or 80-150 micrometer (pm) thick.

32. The battery cell of any of claims 1 to 31, wherein one or both of the first protective layer and the second protective layer include one or more carbides.

33. The battery cell of claim 32, wherein the one or more carbides include silicon carbide (SiC), titanium carbide (TiC), and / or tungsten carbide (WC).

34. The battery cell of any of claims 1 to 33, wherein one or both of the first protective layer and the second protective layer comprise multilayer and / or nanolaminate coatings.

35. The battery cell of claim 34, wherein the multilayer and / or nanolaminate coatings comprise alternating layers of oxides, nitrides, and / or metals.

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