High voltage lithium-containing electrochemical cells and related methods

Abstract

Electrodes and electrochemical cells capable of operating at high voltages, as well as related methods, are reviewed.

Description

[Technical field]

[0001] Electrodes and electrochemical cells capable of operating at high voltages, and related methods, are reviewed. [Background technology]

[0002] To meet the demand for higher energy density in devices and electronic devices, electrodes that can withstand high voltages without degradation are desired. Another consideration is that when electrodes are placed in electrochemical cells or batteries, the electrolyte should also be able to withstand high voltages without decomposing. However, many conventional electrochemical cells and batteries, such as rechargeable lithium-based batteries, have electrodes that are unstable at high voltages, electrolytes that are unstable at high voltages, or both. Thus, improved electrochemical cells and methods are desired. Summary of the Invention

[0003] Described herein are electrochemical cells capable of operating at high voltages and related methods. The subject matter of the present disclosure includes, in some cases, interrelated products, alternative solutions to a particular problem, and / or a number of different applications of one or more systems and / or articles.

[0004] In one embodiment, a method for forming a protective layer on an electrode is described, the method comprising the steps of: in an electrochemical cell comprising a first electrode comprising a lithium intercalation compound having a nickel content of 70 atomic % or greater relative to other transition metals in the lithium intercalation compound; applying one or more formation cycles to the second electrode, charging the second electrode with a first current to a voltage of 4.4 V or greater; and discharging the second electrode at a second current to a voltage less than 4.4 V. A process comprising: Forming a protective layer on at least a portion of the surface of the second electrode. This includes carrying out the following:

[0005] In another aspect, a method of forming a protective layer on an electrode is described, the method comprising: in an electrochemical cell comprising a first electrode, applying one or more formation cycles to the second electrode, charging the second electrode with a first current to a voltage of 4.4 V or greater; and discharging the second electrode at a second current to a voltage less than 4.4 V. A process comprising: Forming a protective layer on at least a portion of the surface of the second electrode. Includes doing the protective layer comprises a lithium compound; The protective layer has an average thickness of 10 μm or less.

[0006] In another aspect, a first electrode comprising a lithium intercalation compound having a nickel content of 70 atomic % or more relative to other transition metals in the lithium intercalation compound; a second electrode comprising a current collector; a separator between the first electrode and the second electrode; and A lithium source between the first electrode and the separator. Including, An electrochemical cell is described in which the average thickness of the lithium between the second electrode and the separator is 30 μm or less.

[0007] In another embodiment, a first electrode comprises a lithium intercalation compound having a nickel content of 70 atomic % or more relative to other transition metals in the lithium intercalation compound; a second electrode comprising a current collector; a separator disposed between the first electrode and the second electrode; A protective layer provided on at least a portion of the surface of the second electrode. Equipped with the protective layer comprises a lithium compound; An electrochemical cell is described in which the protective layer has an average thickness of 10 μm or less.

[0008] In another aspect, a first electrode comprising a lithium intercalation compound having a nickel content of 70 atomic % or more relative to other transition metals in the lithium intercalation compound; a second electrode comprising a current collector having magnesium on at least a portion of a surface of the current collector; and A separator between the first and second electrodes An electrochemical cell is described comprising:

[0009] In another aspect, a first electrode comprising a lithium intercalation compound having a nickel content of 70 atomic % or more relative to other transition metals in the lithium intercalation compound; a second electrode comprising a current collector having magnesium disposed on at least a portion of a surface of the current collector; a separator between the first electrode and the second electrode; and A protective layer adjacent to the second electrode Including, the protective layer comprises a magnesium compound; An electrochemical cell is described in which the protective layer has an average thickness of 10 μm or less.

[0010] In yet another aspect, a method of forming a protective layer on an electrode is described, the method comprising: in an electrochemical cell including a first electrode and a second electrode, applying one or more formation cycles to the second electrode; A method for forming a protective layer on an electrode, comprising: One or more formation cycles charging the second electrode with a first current to a voltage of 4.4 V or greater; discharging the second electrode at a second current to a voltage of 4.4 V or less; and forming a protective layer on at least a portion of the surface of the second electrode; Including, the protective layer comprises a magnesium compound; The protective layer has an average thickness of 10 μm or less.

[0011] Other advantages and novel features of the present disclosure will become apparent from the following detailed description of various non-limiting embodiments of the invention when considered in conjunction with the accompanying figures. In cases where the present specification and a document incorporated by reference include conflicting and / or inconsistent disclosure, the present specification shall control. [Brief description of the drawings]

[0012] Non-limiting embodiments of the present invention are illustratively described with reference to the accompanying figures, which are schematic and are not intended to be drawn to scale. In the figures, each identical or nearly identical component shown is typically represented by a single numeral. Also, for clarity, not every component is shown in every figure, and not every component of each embodiment of the present invention is shown, unless illustration is necessary for a person skilled in the art to understand the invention. [Figure 1A] FIG. 2 is a schematic cross-sectional side view of an electrochemical cell having a protective layer on some, but not all, of the surface of the second electrode, according to some embodiments. [Figure 1B] FIG. 2 is a schematic cross-sectional side view of an electrochemical cell having a protective layer on a surface of a second electrode between the solid-electrolyte interface of the second electrode and the electrolyte, according to some embodiments. [Figure 2A] 13A-13C are schematic diagrams illustrating the application of one or more formation cycles to form a protective layer adjacent to a second electrode, according to some embodiments. [Figure 2B] 13A-13C are schematic diagrams illustrating the application of one or more formation cycles to form a protective layer adjacent to a second electrode, according to some embodiments. [Figure 3A] 4A-4D are schematic cross-sectional side views of a process for forming a layer of lithium metal and a protective layer on a current collector, according to some embodiments. [Figure 3B] 4A-4D are schematic cross-sectional side views of a process for forming a layer of lithium metal and a protective layer on a current collector, according to some embodiments. [Figure 3C]4A-4D are schematic cross-sectional side views of a process for forming a layer of lithium metal and a protective layer on a current collector, according to some embodiments. [Figure 3D] FIG. 1 is a schematic cross-sectional side view of an electrochemical cell having a lithium source between a first electrode and an electrolyte, according to some embodiments. [Figure 4] FIG. 1 illustrates the cycle life of several electrochemical cells fabricated with and without magnesium coated current collectors, according to some embodiments. [Diagram 5] 13 illustrates the effect of elevated temperatures when used during a formation cycle, according to some embodiments. [Figure 6] 14 illustrates the effect of application of various anisotropic pressures on the cycling performance of an electrochemical cell, according to some embodiments. [Figure 7] 1 shows the cycling performance of several electrochemical cells with different amounts of cathode active material, according to some embodiments. [Figure 8] 1 shows the cycling performance of cells charged at different voltages according to some embodiments. [Figure 9] 1 illustrates the effect of various cathode active materials on the performance of an electrochemical cell, according to some embodiments. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Lithium-based batteries capable of operating at higher voltages (e.g., 4.4V or higher) may enable a wider range of applications, for example, in electric vehicles. However, many existing lithium-based batteries, such as certain lithium-ion batteries, cannot exceed voltages higher than 4V due to either electrode and / or electrolyte degradation in the battery. For example, some existing lithium-ion battery electrolytes decompose at voltages above 4V, and therefore, these electrolytes in the battery were thought to be unstable at these high voltages. To avoid this problem, some existing lithium-ion batteries have connected multiple lower voltage lithium-ion electrochemical cells in series to increase the overall battery voltage. However, it would be beneficial to increase the operating voltage of individual electrochemical cells in a high voltage battery, thereby increasing the overall battery voltage while reducing the number of individual electrochemical cells in the battery.

[0014] Given the instability of the electrodes and / or electrolytes described above at high voltages, high voltage lithium ion batteries have been considered impractical in many environments. However, it is recognized and understood herein that electrodes can be made to operate at higher voltages without significant loss of cycling capacity. The use of these electrodes in electrochemical cells (e.g., lithium ion batteries) allows the electrochemical cells to operate at higher voltages than previously anticipated. Advantageously, these high voltage electrodes and electrochemical cells can maintain cycling capacity even in so-called lithium-free configurations (e.g., before subjecting the cathode and / or anode to one or more formation cycles), in which the cathode and / or anode, at least initially, does not contain any lithium or contains less lithium than required for full discharge. In such configurations, a lithium anode can be subsequently formed from a source of lithium (e.g., lithium ions in the first electrode) without significant loss of cycling capacity of the electrodes in the electrochemical cell.

[0015] It has been discovered herein that a first electrode (e.g., cathode) comprising a lithium intercalation compound having a relatively high nickel content (e.g., relative to other transition metals in the compound) can improve the stability of the electrode and / or electrolyte, all other factors being equal, compared to an electrode that does not contain such an amount of nickel. Without wishing to be bound by theory, it is believed that when an electrode having a high nickel content is charged and / or discharged against a counter electrode (e.g., a second electrode, anode), a protective layer forms at or between the solid-electrolyte interface (SEI) of the second electrode (e.g., on at least a portion of the surface of the second electrode), which contributes to improved cycling performance of the electrochemical cell.

[0016] In some cases, the inclusion of magnesium (e.g., magnesium metal, magnesium alloy) in or on at least a portion of a current collector (e.g., disposed on at least a portion of a surface of the current collector) of a second electrode (e.g., an anode) may also contribute to the formation of a protective layer on (at least a portion of) the surface of the second electrode. For example, the second electrode may be or may include a current collector (e.g., a copper current collector) onto which an anode active material (e.g., lithium) may then be formed. Without wishing to be bound by a particular theory, it is believed that the inclusion of magnesium on at least a portion of the surface of the current collector of the second electrode contributes to the formation of a protective layer adjacent to the second electrode at or near a solid-electrolyte interface (SEI) between the second electrode and the electrolyte in an electrochemical cell. For example, the protective layer may form adjacent to a lithium layer between the current collector and the electrolyte. Advantageously, the protective layer may protect the electrode surface (or at least a portion of the electrode surface) from degradation and / or protect the electrolyte from degradation at the electrode surface.

[0017] 1A-1B, a protective layer may be formed on at least a portion of the surface of an electrode (e.g., a second electrode, an anode). By way of example, FIG. 1A shows a schematic diagram of an electrochemical cell 100 including a first electrode 110 adjacent to an electrolyte 130 and a separator 140 adjacent to the electrolyte 130 and between the first electrode 110 and the second electrode 120. Also shown is a protective layer 150 formed on at least a portion of the second electrode 120. As previously mentioned, this protective layer can prevent or inhibit degradation of the second electrode and / or electrolyte in the electrochemical cell. In some embodiments, the protective layer is formed at or within the SEI layer. For example, in FIG. 1B, the protective layer 150 is present in the SEI (152) between the second electrode 120 and the electrolyte 130.

[0018] Although Figure 1A shows protective layer 150 formed on at least a portion of the surface of second electrode 120, in some embodiments, the protective layer may be formed on the entire surface of second electrode 120 within the SEI (152). For example, in Figure 1B, protective layer 150 is formed on the surface of second electrode 120 that is encompassed by the SEI (152). Other configurations or locations for the protective layer are possible.

[0019] In some embodiments, the protective layer comprises an inorganic compound, for example, a lithium salt or lithium compound, such as, by way of non-limiting example, lithium oxide (Li2O) and / or lithium carbonate (LiCO3). In some embodiments, the protective layer may comprise lithium fluoride (LiF).

[0020] In some embodiments, the protective layer includes a magnesium salt or compound, such as, by way of non-limiting example, MgO, MgO3, and / or MgF2. In some embodiments, the protective layer includes a magnesium compound and a lithium compound. For example, the protective layer may include one or more of Li2O, LiCO3, and LiF in combination with one or more of MgO, MgCO3, and MgF2.

[0021] The protective layer may have any suitable thickness. In some embodiments, the average thickness of the protective layer is 0.1 μm or more, 0.5 μm or more, 1 μm or more, 2 μm or more, 3 μm or more, 4 μm or more, 5 μm or more, 6 μm or more, 7 μm or more, 8 μm or more, 9 μm or more, or 10 μm or more. In some embodiments, the average thickness of the protective layer is 10 μm or less, 9 μm or less, 8 μm or less, 7 μm or less, 6 μm or less, 5 μm or less, 4 μm or less, 3 μm or less, 2 μm or less, 1 μm or less, 0.5 μm or less, or 0.1 μm or less. Combinations of the above ranges are also possible (e.g., 0.1 μm or more and 10 μm or less). Other ranges are also possible. The average thickness of the protective layer may be determined using scanning electron microscopy (SEM) techniques.

[0022] The protective layer may be formed after application of one or more formation cycles to an electrode (e.g., a second electrode, a current collector of a second electrode). In some embodiments, the electrode (e.g., a second electrode) may be initially free of a protective layer, but after application of one or more formation cycles, a protective layer may be formed on at least a portion of a surface of the second electrode, for example, on the surface of the current collector, and / or on the surface of lithium that may be formed on the current collector during or after the one or more formation cycles.

[0023] 2A-2B are schematic diagrams showing the formation of a protective layer on the surface of the second electrode. In FIG. 2A, a voltage source 210 is connected to the first electrode 110 and the second electrode 120 of the electrochemical cell 100. When a voltage (e.g., a voltage of 4.4 V or more) is applied from the voltage source 210, a protective layer may be formed on (at least a portion of) the surface of the second electrode 120. As shown in FIG. 2B, a protective layer 150 is formed on at least a portion of the second electrode 120 after or during application of the voltage from the voltage source 210.

[0024] In some embodiments, applying one or more formation cycles includes applying a voltage of 4.4V or more to the electrode. Of course, it should be understood that applying a voltage to an electrode may also include applying a voltage of the same magnitude to a counter electrode with an opposite charge. For example, when applying a voltage to a first electrode (e.g., a cathode), a voltage of the same magnitude but of opposite sign may be applied to a second electrode (e.g., an anode). In some embodiments, the formation cycle occurs during the first, second, third, fourth, fifth, sixth, seventh, eighth, ninth, or tenth cycle of the electrode. That is, in some embodiments, the one or more formation cycles occur in or within the first ten charge-discharge cycles of the first electrode and / or second electrode during the formation stage.

[0025] Charging of an electrode (e.g., first electrode, second electrode) (e.g., during one or more formation cycles) may occur at any suitable rate. As will be understood by those skilled in the art, charging and / or discharging may be described with respect to the C-rate of the electrode, where the C-rate (C) of the electrode is a measure of the rate at which the electrode is charged and / or discharged to its maximum capacity. For example, a 1C rate means that the discharge current discharges the entire battery in 1 hour. In some embodiments, charging of the electrode is performed at a rate of C / 40 or more, C / 20 or more, C / 12 or more, C / 10 or more, C / 6 or more, C / 3 or more, C / 2 or more, 1C or more, 2C or more, or 3C or more. In some embodiments, charging of the electrode occurs at a rate of 3C or less, 2C or less, 1C or less, C / 2 or less, C / 3 or less, C / 6 or less, C / 10 or less, C / 12 or less, C / 20 or less, or C / 40 or less. Combinations of the above ranges are also possible (e.g., C / 40 or more, 3C or less). Other ranges are possible.

[0026] Discharging of the electrodes may occur at any suitable rate. In some embodiments, discharging of the electrodes occurs at a rate of C / 40 or more, C / 20 or more, C / 12 or more, C / 10 or more, C / 6 or more, C / 3 or more, C / 2 or more, 1C or more, 2C or more, 3C or more, 5C or more, or 10C or more. In some embodiments, discharging of the electrodes occurs at a rate of 10C or less, 5C or less, 3C or less, 2C or less, 1C or less, C / 2 or less, C / 3 or less, C / 6 or less, C / 10 or less, C / 12 or less, C / 20 or less, or C / 40 or less. Combinations of the above ranges are also possible (e.g., C / 40 or more and 10C or less). Other ranges are also possible.

[0027] In some embodiments, charging occurs at a different rate than discharging. For example, in some embodiments, it may be advantageous to discharge an electrode at a faster rate than the rate used to charge the electrode. Conversely, in some cases, it may be advantageous to charge an electrode at a faster rate than the rate used to discharge the electrode.

[0028] In some embodiments, one or more formation cycles may be applied before or during heating of the electrodes (e.g., first electrode, second electrode, second electrode including current collector). In some embodiments, the electrodes are heated to a temperature of 40° C. or more, 45° C. or more, 50° C. or more, 55° C. or more, or 60° C. or more. In some embodiments, the electrodes are heated to a temperature of 60° C. or less, 55° C. or less, 50° C. or less, 45° C. or less, or 40° C. or less. Combinations of the above ranges are also possible (e.g., 40° C. or more, 60° C. or less). Other ranges are also possible.

[0029] In some embodiments, the electrochemical cell may be configured to be at least initially free of lithium (e.g., lithium metal). In some such embodiments, the electrochemical cell may include a current collector that can function as an electrode (or electrode precursor) for subsequent formation of a lithium anode on a surface of the current collector. For illustrative purposes, FIG. 3A shows a schematic lithium-free configuration of an electrochemical cell. As exemplarily shown in the figure, the electrochemical cell 300 includes a first electrode 310 adjacent to an electrolyte 320. A second electrode current collector 330 is initially free of lithium directly adjacent thereto, as shown diagrammatically in the figure. However, upon application of a voltage (e.g., from a potentiostat 309), a lithium source, such as lithium in the first electrode 310, may be oxidized while lithium ions (e.g., from the electrolyte 320) may be simultaneously reduced at the current collector 330.

[0030] In some embodiments, a protective layer may be formed on the second current collector while a layer of lithium metal may also be formed on the second current collector. For example, as shown in FIG. 3B, upon application of voltage (e.g., from potentiostat 309), a layer of lithium metal 340 is formed on the surface of current collector 330 in addition to protective layer 350. During one or more subsequent cycles (e.g., formation cycle, operation cycle), lithium metal layer 340 may be consumed (or depleted) while protective layer 350 remains. For example, in FIG. 3C, electrochemical cell 300 is cycled such that lithium metal layer 340 is consumed while lithium ions are reduced in first electrode 310. Protective layer 350 still remains adjacent to second electrode current collector 330 even after the layer of lithium metal 340 is consumed.

[0031] In some embodiments, the lithium source may be present (at least initially) between the first electrode (e.g., cathode) and the separator and / or electrolyte. In some embodiments, the lithium source is within the first electrode. However, in some embodiments, the lithium source is external to the first electrode. For example, in FIG. 3D, lithium source 360 ​​is between the first electrode 310 and the electrolyte 320. This lithium source may be consumed during cycling (e.g., during one or more formation cycles) in some embodiments. In some embodiments, the lithium source is in the form of a layer, such as layer 360 shown in FIG. 3D. In some such embodiments, lithium from the source between the first electrode and the electrolyte (or separator) may be oxidized and then reduced at the second electrode, and upon further cycling, layer 360 does not form again. Instead, lithium may intercalate or redeposit at the first electrode (e.g., within the first electrode).

[0032] In some embodiments, the formation process includes a sufficient number of formation cycles involving lithium deposition and depletion and re-deposition until a lithium electrode is formed with sufficient energy density to participate in a full discharge of the cell. In some embodiments, 10, 8, 6, 4, or 2 or fewer formation cycles are required to form an electrode with sufficient energy density to participate in a full discharge of the cell. During this process, a protective layer, such as protective layer 350, may also be formed as described herein.

[0033] Although the protective layer in FIG. 3B shows the protective layer directly adjacent to the current collector, it should be understood that other arrangements of the protective layer are possible. For example, in some embodiments, the protective layer may be directly adjacent to a layer of lithium metal. In some embodiments, the protective layer may form a gradient with the active material (e.g., lithium metal) on the current collector, making the protective layer indistinguishable from the active material. Other arrangements of the protective layer relative to the current collector are also possible, as the disclosure is not limited thereto. In some embodiments, the protective layer is formed during one or more formation cycles, and lithium metal is formed on the surface of the current collector during one or more formation cycles.

[0034] Also, when a part (e.g., a layer, structure, region) is referred to as being "on," "above," "over," "adjacent," "overlying," or "supported by" another part, it should be understood that it can be directly on the part, or there may be intervening parts (e.g., layers, structures, regions). Similarly, when a part is "below" or "underneath" another part, it can be immediately below the part, or there may be intervening parts (e.g., layers, structures, regions). A part that is "directly on," "directly adjacent," "immediately adjacent," "in direct contact," or "directly supported by" another part means that there are no intervening parts. Also, when a part is referred to as being "on," "adjacent," "over," "in contact with," "under," or "supported by," it should be understood that it may cover the entire part, or a portion of the part.

[0035] In some embodiments, the one or more formation cycles may occur within an electrochemical cell or battery. In some embodiments, in an electrochemical cell including a first electrode comprising a lithium intercalation compound and / or a second electrode comprising a current collector, the one or more formation cycles are applied to the first electrode and / or the second electrode. Further details describing the various electrochemical cell components are described in more detail below.

[0036] As previously mentioned, various embodiments described herein may include electrodes, such as a first electrode and a second electrode. In some embodiments, the first electrode is a cathode or includes a cathode active material, and the second electrode is an anode or includes an anode active material. However, it should be understood that the electrochemical cell or battery may have additional electrodes, such as a third electrode, a fourth electrode, a fifth electrode, etc., as the present disclosure is not limited thereto. In some embodiments, multiple cathodes and / or anodes may be present as a multi-layer stack, for example, where multiple electrodes are fabricated on a substrate (e.g., a flexible substrate). In some embodiments, the electrode (e.g., the second electrode) does not (at least initially) include an electrode active material (e.g., an anode active material), and may include or be a current collector. Further details regarding current collectors are provided elsewhere herein.

[0037] In some embodiments, the electrode (e.g., the first electrode) is a cathode that includes a cathode active material. In an exemplary embodiment, the cathode active material includes a nickel-cobalt-manganese (NCM) compound and is capable of intercalating and deintercalating lithium (e.g., lithium ions). For example, the NCM compound is lithium nickel manganese cobalt oxide (LiNi x Mn y Co z In some such embodiments, the sum of x, y and z is 1. For example, a non-limiting example of a suitable NCM compound is LiNi 1 / 3 Mn 1 / 3Co 1 / 3 O2. In some such embodiments, the NCM compounds have a relatively high nickel content (e.g., 70 atomic % or more, 75 atomic % or more, 80 atomic % or more) relative to other transition metals in the compound. For example, in NCM811, the relative atomic ratios of nickel, cobalt, and manganese are 8:1:1, respectively, with the atomic percentage of nickel being 8 / 10, or 80 atomic %. In some embodiments, the NCM compounds are (at least initially) lithium-free, although lithium may intercalate into the compound during cycling (e.g., during one or more formation cycles).

[0038] In some embodiments, the cathode active material comprises an NCM material, although other cathode active materials are possible. For example, in some embodiments, the cathode active material is a lithium transition metal oxide (other than NCM) or a lithium transition metal phosphate. Non-limiting examples include Li x CoO2 (e.g., Li 1.1 CoO2), Li x NiO2, Li x MnO2, Li x Mn2O4 (e.g., Li 1.05 Mn2O4), Li x CoPO4, Li x MnPO4, and LiCo x Ni (1-x) In some such embodiments, the value of x may be from 0 to 2, inclusive, and the value of y may be from 0 to 2, inclusive. In some embodiments, x is typically from 1 to 2, inclusive, when the electrochemical device is fully discharged, and is 1 or less, inclusive, when the electrochemical device is fully charged. In some embodiments, a fully charged electrochemical device may have a value of x that is from 1 to 1.05, from 1 to 1.1, or from 1 to 1.2, inclusive. Further examples include (0 <x≦1)であるLi x NiPO4, (x+y=2) LiMn x Ni y O4 (e.g., LiMn 1.5 Ni 0.5 O4), (x+y+z=1) LiNix C y Al z O2, LiFePO4, and combinations thereof. In some embodiments, the cathode active material in the cathode includes a lithium transition metal phosphate (e.g., LiFePO4), which in some embodiments may be substituted with a borate and / or a silicate.

[0039] As mentioned above, in some embodiments, the cathode active material includes a lithium intercalation compound (i.e., a compound capable of reversibly inserting lithium ions into lattice and / or interstitial sites). In some cases, the cathode active material includes a layered oxide. Layered oxide generally refers to an oxide having a lamellar structure (e.g., multiple sheets or layers stacked together). Non-limiting examples of suitable layered oxides include lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), and lithium manganese oxide (LiMnO2). In some embodiments, the layered oxide is lithium nickel cobalt aluminum oxide (LiNi x Co y Al z O2, also referred to as "NCA"). In some such embodiments, the sum of x, y and z is 1. For example, a non-limiting example of a suitable NCA compound is LiNi 0.8 Co 0.15 Al 0.05 In some embodiments, the electroactive material comprises a transition metal polyanion oxide (e.g., a compound comprising a transition metal, oxygen, and / or an anion having an absolute charge greater than one). A non-limiting example of a suitable transition metal polyanion oxide is lithium iron phosphate (LiFePO4, also known as "LFP"). Another non-limiting example of a suitable transition metal polyanion oxide is lithium manganese iron phosphate (LiMn x Fe 1-x PO4, also referred to as "LMFP"). A non-limiting example of a suitable LMFP compound is LiMn 0.8 Fe 0.2In some embodiments, the electroactive material is a spinel (e.g., a compound having the structure AB2O4, where A can be Li, Mg, Fe, Mn, Zn, Cu, Ni, Ti, or Si, and B can be Al, FECr, Mn, or V). A non-limiting example of a suitable spinel is represented by the formula LiM x Mn 2-x O4, where M is one or more of Co, Mg, Cr, Ni, Fe, Ti, and Zn. In some embodiments, x may be equal to 0, and the spinel may be lithium manganese oxide (LiMn2O4, also known as "LMO"). Another non-limiting example is lithium manganese nickel oxide (LiNi x M 2-x O4, also referred to as "LMNO"). A non-limiting example of a suitable LMNO compound is LiNi 0.5 Mn 1.5 O4. In some cases, the electroactive material of the second electrode is Li 1.14 Mn 0.42 Ni 0.25 Co 0.29 O2 ("HC-MNC"), lithium carbonate (Li2CO3), lithium carbides (e.g., Li2C2, Li4C, Li6C2, Li8C3, Li6C3, Li4C3, Li4C5), vanadium oxides (e.g., V2O5, V2O3, V6O 13 ), and / or vanadium phosphate (e.g., lithium vanadium phosphate such as Li3V2(PO4)3), or any combination thereof.

[0040] In some embodiments, the cathode active material (e.g., the cathode active material of the first electrode) may include a lithium source. For example, the cathode active material may be an NCM compound that includes lithium ions within the compound and may be used to form a lithium anode upon charging. In some embodiments, the lithium source (e.g., in the cathode) has a thickness of 30 μm or less, 25 μm or less, 20 μm or less, 15 μm or less, 10 μm or less, 5 μm or less, or 1 μm or less. In some embodiments, the lithium source has a thickness of 1 μm or more, 5 μm or more, 10 μm or more, 15 μm or more, 20 μm or more, 25 μm or more, or 30 μm or more. Combinations of the above ranges are also possible (e.g., 1 μm or more to 30 μm or less). Other ranges are also possible.

[0041] In some embodiments, the cathode active material comprises a conversion compound. It is recognized that cathodes comprising a conversion compound may have a relatively large specific capacity. Without wishing to be bound by a particular theory, a relatively large specific capacity can be achieved by utilizing all possible oxidation states of the compound through a conversion reaction in which multiple electron transfers occur per transition metal (e.g., compared to 0.1 to 1 electron transfer in intercalation compounds). Suitable conversion compounds include, but are not limited to, transition metal oxides (e.g., Co3O4), transition metal hydrides, transition metal sulfides, transition metal nitrides, and transition metal fluorides (e.g., CuF2, FeF2, FeF3). Transition metals generally refer to elements whose atoms have a partially filled d-subshell (e.g., Sc, Ti, V, Cr, Mn, FeCo, Ni, Cu, Zn, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, Hf, Ta, W, Re, Os, Ir, Pt, Au, Hg, Rf, Db, Sg, Bh, Hs).

[0042] In some cases, the cathode active material may be doped with one or more dopants to change the electrical properties (e.g., electrical conductivity) of the cathode active material. Non-limiting examples of suitable dopants include aluminum, niobium, silver, and zirconium.

[0043] In some embodiments, the cathode active material may be modified with a surface coating that includes an oxide. Non-limiting examples of surface oxide coating materials include MgO, Al2O3, SiO2, TiO2, ZnO2, SnO2, and ZrO2. In some embodiments, such coatings can prevent direct contact between the cathode active material and the electrolyte, thereby inhibiting side reactions.

[0044] The cathode (e.g., a first electrode having a cathode active material deposited on a surface of a current collector) has a particular thickness. In some embodiments, the cathode has a thickness of 100 nm or more, 250 nm or more, 500 nm or more, 750 nm or more, 1 μm or more, 2 μm or more, 3 μm or more, 5 μm or more, 10 μm or more, 20 μm or more, 25 μm or more, or 50 μm or more. In some embodiments, the cathode has a thickness of 50 μm or less, 25 μm or less, 20 μm or less, 10 μm or less, 5 μm or less, 3 μm or less, 2 μm or less, 1 μm or less, 750 nm or less, 500 nm or less, 250 nm or less, or 100 nm or less. Combinations of the above ranges are also possible (e.g., 100 nm or more, 10 μm or less). Other ranges are also possible. In embodiments in which there is more than one cathode, each cathode may independently have a thickness of one or more of the above ranges.

[0045] In some embodiments, the electrode (e.g., the second electrode) is an electrode or comprises an anode active material. A variety of suitable anode active materials are possible. In some embodiments, the anode active material comprises lithium (e.g., lithium metal), such as lithium foil, lithium deposited on a conductive substrate (i.e., a current collector) or on a non-conductive substrate (e.g., an adhesive layer), vacuum-deposited lithium metal, spray-deposited lithium, deposited lithium, and lithium alloys (e.g., lithium-aluminum alloys and lithium-tin alloys). The lithium can be provided as a film or as multiple films, optionally separated. The lithium can also be a lithium alloy. Lithium alloys suitable for use in the embodiments described herein can include alloys of lithium with aluminum, magnesium, silicon, indium, zinc, and / or tin. The lithium can also be provided by aerosol deposition.

[0046] In some embodiments, lithium metal or lithium metal alloy may be present during only a portion of the charge / discharge cycle. For example, a cell may be constructed without any lithium metal / lithium metal alloy present on the anode current collector (e.g., copper, magnesium), and then lithium metal / lithium metal alloy may be deposited on the anode current collector during the charge or discharge process. In some embodiments, lithium may be completely depleted after discharge, such that it is present only during a portion of the charge / discharge cycle.

[0047] For embodiments in which the anode comprises a lithium metal alloy, each of the one or more alloying metals (e.g., magnesium, tin, zinc) may be present in the lithium alloy in a particular amount (with the remainder comprising lithium and / or some other alloying metal). In some embodiments, the amount of one or more alloying metals in the lithium metal alloy is each independently 25 ppm or more, 50 ppm or more, 100 ppm or more, 200 ppm or more, 300 ppm or more, 400 ppm or more, or 500 ppm or more. In some embodiments, the amount of one or more alloying metals in the lithium metal alloy is each independently 500 ppm or less, 400 ppm or less, 300 ppm or less, 200 ppm or less, 100 ppm or less, 50 ppm or less, or 25 ppm or less. Combinations of the above ranges are also possible. In some embodiments, the amount of one or more alloying metals in the lithium metal alloy is each independently 0.001% or more, 0.01% or more, 0.1% or more, 1% or more, 2% or more, 5% or more, 10% or more, 12% or more, 15% or more, 20% or more, 25% or more, 30% or more, 35% or more, 40% or more, or 45% or more. In some embodiments, the amount of one or more alloying metals in the lithium metal alloy is each independently 50% or less, 45% or less, 40% or less, 35% or less, 30% or less, 25% or less, 20% or less, 15% or less, 12% or less, 10% or less, 5% or less, 2% or less, 1% or less, 0.1% or less, or 0.001% or less. Combinations of the above ranges are also possible (eg, 0.001% to 10% by weight, 25 ppm to 50 ppm by weight, etc.). Other ranges are also possible.

[0048] Suitable alloying metals for lithium metal alloys can include, for example, Groups 1-17, 2-14, or Groups 2, 10, 11, 12, 13, 14. Suitable elements from Group 2 of the periodic table can include, for example, beryllium, magnesium, calcium, strontium, barium, and / or radium. Suitable elements from Group 10 can include, for example, nickel, palladium, and / or platinum. Suitable elements from Group 11 can include, for example, copper, silver, and / or gold. Suitable elements from Group 12 can include, for example, zinc, cadmium, and / or mercury. Suitable elements from Group 13 can include, for example, aluminum, gallium, indium, and / or thallium. Suitable elements from Group 14 can include, for example, silicon, germanium, tin, and / or lead.

[0049] In some embodiments, the anode active material (e.g., deposited on a current collector) comprises 50% or more lithium, 75% or more lithium, 80% or more lithium, 90% or more lithium, 95% or more lithium, 99% or more lithium, or more by weight. In some embodiments, the anode active material comprises 99% or less lithium, 95% or less lithium, 90% or less lithium, 80% or less lithium, 75% or less lithium, 50% or less lithium, or less by weight. Combinations of the above ranges are also possible (e.g., 90% or more lithium, up to 99% lithium by weight). Other ranges are also possible.

[0050] In some embodiments, the electrode (e.g., the second electrode) does not contain lithium (e.g., lithium metal), at least initially (i.e., before charging and discharging). However, other embodiments may include some lithium metal deposited on the current collector. In some such embodiments, the thickness of the lithium deposited on the current collector is 0.1 μm or more, 1 μm or more, 3 μm or more, 5 μm or more, 10 μm or more, 20 μm or more, or 30 μm or more. In some such embodiments, the thickness of the lithium deposited on the current collector is 30 μm or less, 20 μm or less, 10 μm or less, 5 μm or less, 3 μm or less, 1 μm or less, or 0.1 μm or less. Combinations of the above ranges are also possible (e.g., 0.1 μm or more and 10 μm or less). Other ranges are also possible. In some embodiments, there is no lithium present on the surface of the anode.

[0051] In some embodiments, the anode active material is a material in which lithium ions are released during discharge and incorporated (e.g., intercalated) during charging. In some embodiments, the anode active material includes a lithium intercalation compound (i.e., a compound that can reversibly insert lithium ions into lattice and / or interstitial sites). In some embodiments, the anode active material includes carbon. In some cases, the anode active material is or includes a graphitic material (e.g., graphite). A graphitic material generally refers to a two-dimensional material comprising multiple layers of graphene (i.e., layers containing carbon atoms covalently bonded in a hexagonal lattice). Adjacent graphene layers are typically attracted to each other by van der Waals forces, although in some cases there may be covalent bonds between one or more sheets. In some cases, the carbon-containing anode active material is or includes coke (e.g., petroleum coke). In some embodiments, the anode active material includes any alloy of silicon, lithium, and / or combinations thereof. In some embodiments, the anode active material includes lithium titanate (Li4Ti5O 12 , also referred to as "LTO"), tin-cobalt oxide, or any combination thereof.

[0052] In some embodiments, the anode (e.g., a current collector, having an active anode material deposited on its surface) may be adjacent to a source of lithium (e.g., lithium included with the active cathode material of the first electrode) and / or may be adjacent to a separator.

[0053] The anode (e.g., a second electrode having an anode active material attached to a surface of a current collector) has a particular thickness. In some embodiments, the anode has a thickness of 100 nm or more, 250 nm or more, 500 nm or more, 750 nm or more, 1 μm or more, 2 μm or more, 3 μm or more, 5 μm or more, 10 μm or more, 20 μm or more, 25 μm or more, or 50 μm or more. In some embodiments, the anode has a thickness of 50 μm or less, 25 μm or less, 20 μm or less, 10 μm or less, 5 μm or less, 3 μm or less, 2 μm or less, 1 μm or less, 750 nm or less, 500 nm or less, 250 nm or less, or 100 nm or less. Combinations of the above ranges are also possible (e.g., 100 nm or more, 10 μm or less). Other ranges are also possible. In embodiments in which there is more than one anode, each anode may independently have a thickness of one or more of the above ranges.

[0054] In some embodiments, an electrode (e.g., a first electrode, a second electrode) comprises a current collector. For example, in some embodiments, the current collector is adjacent (e.g., directly adjacent) to the cathode active material and / or the anode active material such that the current collector can remove current from and / or provide current to the electroactive layer. It is also understood that in some embodiments, an electrode may comprise (at least initially) a current collector that does not comprise an electrode active material (e.g., lithium) so that the current collector is a current collector for at least a portion of the charging or discharging of the electrode. That is, in some embodiments, an electrode, such as a second electrode, does not comprise lithium, or other electrode active material. In some such embodiments, upon charging and / or discharging (e.g., applying one or more formation cycles) to the electrode, an electrode active material, such as lithium metal, may form adjacent to the current collector as part of the electrode. However, in other embodiments, the electrode comprises a current collector and an electrode active material (e.g., NCM, lithium metal).

[0055] A wide variety of current collectors are known in the art. Suitable current collectors can include, for example, metals, metal foils (e.g., aluminum foil), polymer films, metallized polymer films (e.g., aluminized plastic films such as aluminized polyester films), conductive polymer films, polymer films having a conductive coating, conductive polymer films having a conductive metal coating, and polymer films having conductive particles dispersed therein.

[0056] In some embodiments, the current collector comprises one or more conductive metals, such as aluminum, copper, magnesium, chromium, zinc, stainless steel, and / or nickel. For example, the current collector can include a copper metal layer. Optionally, another conductive metal layer, such as magnesium or titanium, can be disposed on the copper layer. For example, as previously described, in some embodiments, the current collector (e.g., a copper current collector) has magnesium deposited on at least a portion of the surface of the current collector.

[0057] In some embodiments, the current collector or a layer on the current collector may include a metal that alloys with lithium, such as one or more of the alloying metals described herein. Upon cycling of the cell, the alloying metal may combine with the lithium metal in the lithium metal layer to form a lithium metal alloy as described herein. The alloying metal may be present in or on the current collector in an amount suitable to form a lithium metal alloy in one or more of the amounts described herein.

[0058] Other current collectors can include, for example, expanded metal, metal mesh, metal grid, expanded metal grid, metal wool, woven carbon fabric, woven carbon mesh, non-woven carbon mesh, and carbon felt. Additionally, the current collector can be electrochemically inert. However, in other embodiments, the current collector can include an electroactive material or have an electrode active material deposited on a surface of the current collector.

[0059] For embodiments that include a current collector, the current collector may include an alloy / one or more alloying metals (e.g., magnesium, tin, zinc), and each metal in the alloy may be present in a particular amount (the balance including any other alloying metals of the current collector). In some embodiments, the amount of one or more alloying metals of the current collector is each independently 25 ppm or more, 50 ppm or more, 100 ppm or more, 200 ppm or more, 300 ppm or more, 400 ppm or more, or 500 ppm or more. In some embodiments, the amount of one or more alloying metals of the current collector is each independently 500 ppm or less, 400 ppm or less, 300 ppm or less, 200 ppm or less, 100 ppm or less, 50 ppm or less, or 25 ppm or less. Combinations of the above ranges are also possible. In some embodiments, the amount of one or more alloying metals of the current collector is each independently 0.001% or more, 0.01% or more, 0.1% or more, 1% or more, 2% or more, 5% or more, 10% or more, 12% or more, 15% or more, 20% or more, 25% or more, 30% or more, 35% or more, 40% or more, or 45% or more. In some embodiments, the amount of one or more alloying metals of the current collector is each independently 50% or less, 45% or less, 40% or less, 35% or less, 30% or less, 25% or less, 20% or less, 15% or less, 12% or less, 10% or less, 5% or less, 2% or less, 1% or less, 0.1% or less, or 0.001% or less. Combinations of the above ranges are also possible (eg, 0.001% to 10% by weight, 25 ppm to 50 ppm by weight, etc.). Other ranges are also possible.

[0060] Suitable alloying metals for the current collector material include, for example, Groups 1-17, 2-14, or Groups 2, 10, 11, 12, 13, or 14. Suitable elements from Group 2 of the Periodic Table include, for example, beryllium, magnesium, calcium, strontium, barium, and / or radium. Suitable elements from Group 10 include, for example, nickel, palladium, and / or platinum. Suitable elements from Group 11 include, for example, copper, silver, and / or gold. Suitable elements from Group 12 include, for example, zinc, cadmium, and / or mercury. Suitable elements from Group 13 include, for example, aluminum, gallium, indium, and / or thallium. Suitable elements from Group 14 include, for example, silicon, germanium, tin, and / or lead.

[0061] As previously mentioned, in some embodiments, current may be present during at least a portion of the formation cycle of the electrode and / or during at least a portion of the charge / discharge cycle without the presence of active electrode material (e.g., active cathode material, active anode material) on the surface of the current collector. In such embodiments, the current collector may function as an electrode precursor, where active electrode material (e.g., active anode material such as lithium) may be formed (or deposited) on at least a portion of the surface of the current collector during formation and / or subsequent charge / discharge cycles.

[0062] The current collector may have any suitable thickness. For example, the thickness of the current collector is 0.1 μm or more, 0.3 μm or more, 0.5 μm or more, 1 μm or more, 3 μm or more, 5 μm or more, 7 μm or more, 9 μm or more, 10 μm or more, 12 μm or more, 15 μm or more, 20 μm or more, 25 μm or more, 30 μm or more, 40 μm or more, or 50 μm or more. In some embodiments, the thickness of the current collector may be 50 μm or less, 40 μm or less, 30 μm or less, 25 μm or less, 20 μm or less, 15 μm or less, 12 μm or less, 10 μm or less, 9 μm or less, 7 μm or less, 5 μm or less, 3 μm or less, 1 μm or less, 0.5 μm or less, 0.3 μm or less, or 0.1 μm or less. Combinations of the above ranges are also possible (e.g., 0.3 μm or more, 15 μm or less). Other ranges are possible.

[0063] In some embodiments, the electrochemical cell or battery may include a separator (e.g., adjacent to the cathode, adjacent to the anode, adjacent to a lithium source, adjacent to a current collector of an electrode). The separator material may be a non-electronically and / or non-ionically conductive material that prevents undesired shorting of the cathode and anode, for example, due to the formation of metal dendrites from one layer to another. That is, the separator may be configured to inhibit (e.g., prevent) physical contact between layers (e.g., between a cathode layer and an anode layer) that may result in a short circuit of the electrochemical cell. In some embodiments, the separator may be configured to be substantially electronically non-conductive, which can inhibit the extent to which the separator causes a short circuit of the electrochemical cell. In some embodiments, all or a portion of the separator has a lattice constant of at least about 10 4 , at least about 10 5 , at least 10 10 , at least 10 15 , or at least 10 20 It may be formed of a material having a bulk electronic resistivity in ohmmeters, which may be measured at room temperature (e.g., 25° C.).

[0064] In some embodiments, the separator may be ionically conductive, while in other embodiments, the separator is substantially ionically non-conductive. In some embodiments, the average ionic conductivity of the separator is greater than 10 -7 S / cm or more, 10 -6 S / cm or more, 10 -5 S / cm or more, 10 -4 S / cm or more, 10 -2 S / cm or more, or 10 -1 In some embodiments, the average ionic conductivity of the separator is 1 S / cm or less, 10 -1 S / cm or less, 10 -2 S / cm or less, 10 -3 S / cm or less, 10 -4 S / cm or less, 10 -5 S / cm or less, 10 -6 S / cm or less, 10 -7 S / cm or less, or 10 -8 Combinations of the above ranges are also possible (e.g., 10 -8 S / cm or more about 10 -1 (average ionic conductivity in S / cm or less).

[0065] In some embodiments, the separator is solid. The separator may be porous to allow the electrolyte solvent (i.e., liquid electrolyte) to pass through. However, in some cases, the separator is substantially free of solvent (as in a gel), except for solvent that may pass through or be present in the pores of the separator. In other aspects, the separator may be in the form of a gel.

[0066] Separators as described herein can be formed from a variety of materials. In some cases, the separator may comprise a polymeric material, and in other cases, the separator may be formed from an inorganic material (e.g., fiberglass filter paper). Examples of suitable separator materials include, but are not limited to, polyolefins (e.g., polyethylene, poly(butene-1), poly(n-pentene-2), polypropylene, polytetrafluoroethylene), polyamines (e.g., poly(ethyleneimine) and polypropyleneimine (PPI)); polyamides (e.g., polyamide(nylon), poly(ε-caprolactam) (nylon 6), poly(hexamethylene adipamide) (nylon 66)); polyimides (e.g., polyimide, polynitrile, poly(pyromellitimide-1,4-diphenyl ether) ("Kapton®") ("NOMEX®") ("KEVLAR®"); polyether ether ketone (PEEK); vinyl polymers (e.g., polyacrylamide, poly(2-vinylpyridine), poly(N-vinylpyrrolidone), poly(methyl cyanoacrylate), poly(ethyl cyanoacrylate), poly(butyl cyanoacrylate), poly(isobutyl cyanoacrylate), poly(vinyl acetate), poly(vinyl alcohol), poly(vinyl chloride), poly(vinyl fluoride), poly(2-vinylpyridine), vinyl polymers, polychlorotrifluoroethylene, and poly(isohexyl cyanoacrylate); polyacetals; polyesters (e.g., polycarbonate, polybutylene terephthalate, polyhydroxybutyrate); polyethers (poly(ethylene ether) poly(propylene oxide) (PEO), poly(propylene oxide) (PPO), poly(tetramethylene oxide) (PTMO); vinylidene polymers (e.g., polyisobutylene, poly(methylstyrene), poly(methyl methacrylate) (PMMA), poly(vinylidene chloride), and poly(vinylidene fluoride)); polyaramids (e.g., poly(imino-1,3-phenyleneiminoisophthaloyl) and poly(imino-1,4-phenyleneiminoterephthaloyl));Polyheteroaromatics (e.g., polybenzimidazole (PBI), polybenzobisoxazole (PBO), and polybenzobisthiazole (PBT)); polyheterocyclic compounds (e.g., polypyrrole); polyurethanes; phenolic polymers (e.g., phenol formaldehyde); polyalkynes (e.g., polyacetylene); polydienes (e.g., 1,2-polybutadiene, cis or trans-1,4-polybutadiene); polysiloxanes (e.g., poly(dimethylsiloxane) (PDMS), poly(diethylsiloxane) (PDES), polydiphenylsiloxane (PDPS), and polymethylphenylsiloxane (PMPS)); and inorganic polymers (e.g., polyphosphazenes, polyphosphonates, polysilanes, polysilazanes). In some embodiments, the polymer may be selected from poly(n-pentene-2), polypropylene, polytetrafluoroethylene, polyamides (e.g., polyamide (nylon), poly(ε-caprolactam) (nylon 6), poly(hexamethylene adipamide) (nylon 66), polyamides (e.g., polynitrile, and poly(pyromellitimide-1,4-diphenyl ether) ("Kapton®") ("NOMEX®") ("KEVLAR®")), polyether ether ketone (PEEK), and combinations thereof;

[0067] The mechanical and electronic properties (e.g., conductivity, resistivity) of these polymers are known. Thus, a person skilled in the art can select suitable materials based on their mechanical and / or electronic properties (e.g., ionic conductivity and / or electronic conductivity / resistivity) and / or modify such polymers to be ionically conductive (e.g., conductive to a single ion) based on the knowledge of the art in combination with the description herein. For example, the polymeric materials described above and herein may further include salts, such as lithium salts (e.g., LiSCN, LiBr, LiI, LiClO4, LiAsF6, LiSO3CF3, LiSO3CH3, LiBF4, LiB(Ph)4, LiPF6, LiC(SO2CF3)3, and LiN(SO2CF3)2), if desired, to enhance ionic conductivity.

[0068] One of ordinary skill in the art in view of the present disclosure will be able to select a suitable material for use as a separator or separator material. Relevant factors that may be considered in making such a selection include the ionic conductivity of the separator material, the ability to deposit or otherwise form the separator material on or with other materials in the electrochemical cell, the flexibility of the separator material, the porosity of the separator material (e.g., overall porosity, average pore size, pore size distribution, and / or tortuosity), the compatibility of the separator material with the manufacturing process used to form the electrochemical cell, the compatibility of the separator material with the electrolyte of the electrochemical cell, and / or the ability to deposit the separator material on the ion conductor material. In some embodiments, the separator material may be selected based on its ability to withstand an aerosol deposition process without mechanical failure. For example, in aspects in which relatively high velocities are used to deposit a plurality of particles (e.g., inorganic particles), the separator material may be selected or configured to withstand such deposition.

[0069] The separator (e.g., a separator including a separator material) may have any suitable porosity. In some embodiments, the separator has a porosity of 20% or more, 25% or more, 30% or more, 40% or more, or 50% or more. In some embodiments, the porosity of the separator is 70% or less, 60% or less, 50% or less, 40% or less, 30% or less, 25% or less, or 20% or less. Combinations of the above ranges are also possible (e.g., 20% or more, 40% or less). Other ranges are also possible.

[0070] The separator may have any suitable thickness. In some embodiments, the separator has a thickness of 100 nm or more, 250 nm or more, 500 nm or more, 750 nm or more, 1 μm or more, 2 μm or more, 3 μm or more, 5 μm or more, 10 μm or more, 20 μm or more, 25 μm or more, or 50 μm or more. In some embodiments, the separator has a thickness of 50 μm or less, 25 μm or less, 20 μm or less, 10 μm or less, 5 μm or less, 3 μm or less, 2 μm or less, 1 μm or less, 750 nm or less, 500 nm or less, 250 nm or less, or 100 nm or less. Combinations of the above ranges are also possible (e.g., 100 nm or more and 10 μm or less). Other ranges are also possible.

[0071] Various embodiments described herein may include an electrolyte. In some embodiments, the electrolyte is a liquid electrolyte in an electrochemical cell. As will be understood by those skilled in the art, a liquid electrolyte includes a solvent and one or more ions (e.g., lithium ions). Suitable electrolytes include, but are not limited to, organic electrolytes (i.e., electrolytes that include an organic solvent), gel polymer electrolytes, and solid polymer electrolytes. The solvent may be an aqueous or non-aqueous solvent. Examples of useful non-aqueous solvents (i.e., non-aqueous liquid electrolyte solvents) include, but are not limited to, N-methylacetamide, acetonitrile, acetals, ketals, esters (e.g., esters of carbonic, sulfonic, and / or phosphoric acids), carbonates (e.g., dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, propylene carbonate, ethylene carbonate, fluoroethylene carbonate, difluoroethylene carbonate), sulfones, sulfites, sulfolane, sulfonimides (e.g., bis(trifluoromethane)sulfonimide lithium salt), ethers (e.g., aliphatic ethers, acyclic ethers, cyclic ethers), glymes, polyethers, phosphate esters (e.g., hexafluorophosphate), siloxanes, dioxolanes, N-alkylpyrrolidones (e.g., N-methyl 2-pyrrolidone), nitrate-containing compounds, substituted forms of the foregoing, and blends thereof. Examples of acyclic ethers that can be used include, but are not limited to, diethyl ether, dipropyl ether, dibutyl ether, dimethoxymethane, trimethoxymethane, 1,2-dimethoxyethane, diethoxyethane, 1,2-dimethoxypropane, and 1,3-dimethoxypropane. Examples of cyclic ethers that can be used include, but are not limited to, tetrahydrofuran, tetrahydropyran, 2-methyltetrahydrofuran, 1,4-dioxane, 1,3-dioxolane, trioxane, and the like.Examples of usable polyethers include, but are not limited to, diethylene glycol dimethyl ether (diglyme), triethylene glycol dimethyl ether (triglyme), tetraethylene glycol dimethyl ether (tetraglyme), higher glymes, ethylene glycol divinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether, dipropylene glycol dimethyl ether, and butylene glycol ether. Examples of usable sulfones include, but are not limited to, sulfolane, 3-methylsulfolane, 3-sulfolene, and the like. The aforementioned fluorinated derivatives are also useful as liquid electrolyte solvents. These electrolytes may optionally include one or more ionic electrolyte salts (e.g., to provide or enhance ionic conductivity).

[0072] In some cases, mixtures of the solvents described herein can also be used. For example, in some embodiments, the mixture of solvents is selected from the group consisting of 1,3-dioxolane and dimethoxyethane, 1,3-dioxolane and diethylene glycol dimethyl ether, 1,3-dioxolane and triethylene glycol dimethyl ether, and 1,3-dioxolane and sulfolane. In some embodiments, the mixture of solvents includes dimethyl carbonate and ethylene carbonate. In some embodiments, the mixture of solvents includes ethylene carbonate and ethyl methyl carbonate. The weight ratio of the two solvents in the mixed solvent may range from about 5%:95% to 95%:5% by weight in some cases. For example, in some embodiments, the electrolyte includes a 50%:50% by weight mixture of dimethyl carbonate:ethylene carbonate. In other embodiments, the electrolyte includes a 30%:70% by weight mixture of ethylene carbonate:ethyl methyl carbonate. The electrolyte may comprise a mixture of dimethyl carbonate:ethylene carbonate in a ratio of dimethyl carbonate:ethylene carbonate not greater than 50%:50% by weight and not less than 30%:70% by weight.

[0073] In some embodiments, the electrolyte may include a mixture of fluoroethylene carbonate and dimethyl carbonate. The weight ratio of fluoroethylene carbonate to dimethyl carbonate may be 20%:80% or 25%:75% by weight. The weight ratio of fluoroethylene carbonate to dimethyl carbonate may be greater than or equal to 20%:80% by weight and less than or equal to 25%:75% by weight.

[0074] As previously mentioned, in some cases, an aqueous solvent can be used with an electrolyte, for example in a lithium battery. The aqueous solvent can include water and can include other components, such as ionic salts. As previously mentioned, in some embodiments, the electrolyte can include species such as lithium hydroxide to reduce the hydrogen ion concentration in the electrolyte, or other species that make the electrolyte basic.

[0075] The liquid electrolyte solvent is also useful as a plasticizer for gel polymer electrolytes, i.e. electrolytes that contain one or more polymers that form a semi-solid network. Examples of useful gel polymer electrolytes include, but are not limited to, those that contain one or more polymers selected from the group consisting of polyethylene oxide, polypropylene oxide, polyacrylonitrile, polysiloxane, polyimide, polyphosphazene, polyether, sulfonated polyimide, perfluorinated membrane (NAFION resin), polydivinyl polyethylene glycol, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, polysulfone, polyethersulfone, derivatives thereof, copolymers thereof, crosslinked and network structures thereof, and blends thereof, and optionally one or more plasticizers. In some embodiments, the gel polymer electrolyte comprises 10-20%, 20-40%, 60-70%, 70-80%, 80-90%, or 90-95% by volume of a heterogeneous electrolyte.

[0076] In some embodiments, one or more gels and / or solid polymers may be used to form the electrolyte. Examples of useful solid polymer electrolytes include, but are not limited to, those that include one or more polymers selected from the group consisting of polyethers, polyethylene oxides, polypropylene oxides, polyimides, polyphosphazenes, polyacrylonitriles, polysiloxanes, derivatives thereof, copolymers thereof, crosslinked and network structures thereof, and blends thereof.

[0077] In addition to the electrolyte solvents, gelling agents, and polymers known in the art to form the electrolyte, the electrolyte may further include one or more ionic electrolyte salts, also known in the art, to enhance ionic conductivity.

[0078] The electroactive species may be present with the electrolyte as an ionic electrolyte salt. Examples of ionic electrolyte salts for use in the electrolyte of the electrochemical cells described herein include, but are not limited to, LiSCN, LiBr, LiI, LiClO4, LiAsF6, LiSO3CF3, LiSO3CH3, LiBF4, LiB(Ph)4, LiPF6, LiC(SO2CF3)3, LiN(SO2CF3)2, and lithium bis(fluorosulfonyl)imide (LiFSI). Other electrolyte salts that may be useful include lithium polysulfide (Li2S x ), and lithium salts of organic polysulfides (LiS x R) n (wherein x is an integer from 1 to 20, n is an integer from 1 to 3, and R is an organic group), including those disclosed in Lee et al., US Pat. No. 5,538,812.

[0079] In some embodiments, the electrolyte comprises one or more room temperature ionic liquids. Room temperature ionic liquids, when present, typically comprise one or more cations and one or more anions. Non-limiting examples of suitable cations include lithium cations and / or one or more quaternary ammonium cations, such as imidazolium cations, pyrrolidinium cations, pyridinium cations, tetraalkylammonium cations, pyrazolium cations, piperidinium cations, pyridazinium cations, pyrimidinium cations, pyrazinium cations, oxazolium cations, and trizolium cations. Non-limiting examples of suitable anions include trifluoromethylsulfonate (CF3SO3 - ), bis(fluorosulfonyl)imide (N(FSO2)2 - ), bis(trifluoromethylsulfonyl)imide ((CF3SO2)2N - ), bis(perfluoroethylsulfonyl)imide ((CF3CF2SO2)2N - ) and tris(trifluoromethylsulfonyl)methide ((CF3SO2)3C - ). Non-limiting examples of suitable ionic liquids include N-methyl-N-propylpyrrolidinium / bis(fluorosulfonyl)imide and 1,2-dimethyl-3-propylimidazolium / bis(trifluoromethanesulfonyl)imide. In some embodiments, the electrolyte comprises both a room temperature ionic liquid and a lithium salt. In other embodiments, the electrolyte comprises a room temperature ionic liquid and does not comprise a lithium salt.

[0080] When present, the lithium salt may be present in the electrolyte at various suitable concentrations. In some embodiments, the lithium salt is present in the electrolyte at a concentration of 0.01M or more, 0.02M or more, 0.05M or more, 0.1M or more, 0.2M or more, 0.5M or more, 1M or more, 2M or more, or 5M or more. The lithium salt may be present in the electrolyte at a concentration of 10M or less, 5M or less, 2M or less, 1M or less, 0.5M or less, 0.2M or less, 0.1M or less, 0.05M or less, or 0.02M or less. Combinations of the above ranges are also possible (e.g., 0.01M or more and 10M or less, or 0.01M or more and 5M or less). Other ranges are also possible.

[0081] In some embodiments, the electrolyte includes fluoroethylene carbonate. In some embodiments, the total weight of fluoroethylene carbonate in the electrolyte may be 30% or less, 28% or less, 25% or less, 22% or less, 20% or less, 18% or less, 15% or less, 12% or less, 10% or less, 8% or less, 6% or less, 5% or less, 4% or less, 3% or less, 2% or less, or 1% or less by weight, based on the total weight of the electrolyte. In some embodiments, the total weight of fluoroethylene carbonate in the electrolyte is greater than 0.2% by weight, greater than 0.5% by weight, greater than 1% by weight, greater than 2% by weight, greater than 3% by weight, greater than 4% by weight, greater than 6% by weight, greater than 8% by weight, greater than 10% by weight, greater than 15% by weight, greater than 18% by weight, greater than 20% by weight, greater than 22% by weight, greater than 25% by weight, or greater than 28% by weight, based on the total weight of the electrolyte. Combinations of the above ranges are also possible (eg, 0.2% or less and greater than 30% by weight, 15% or less and greater than 20% by weight, or 20% or less and greater than 25% by weight). Other ranges are also possible.

[0082] In some embodiments, the electrolyte may include several chemical species together that are particularly beneficial in combination. For example, in some embodiments, the electrolyte includes fluoroethylene carbonate, dimethyl carbonate, and / or LiPF6. In some such embodiments, the weight ratio of fluoroethylene carbonate:dimethyl carbonate may be 20 wt%:80 wt% to 25 wt%:75 wt%, and the concentration of LiPF6 in the electrolyte may be about 1 M (e.g., 0.05 M to 2 M). The electrolyte may further include lithium bis(oxalato)borate (e.g., at a concentration in the electrolyte of 0.1 wt% to 6 wt%, 0.5 wt% to 6 wt%, or 1 wt% to 6 wt%), and / or lithium tris(oxalato)phosphate (e.g., at a concentration in the electrolyte of 1 wt% to 6 wt%).

[0083] As mentioned above, in some embodiments, the electrolyte is a solid electrolyte. In some such embodiments, the solid electrolyte may function as a separator, separating the first and second electrodes (e.g., cathode and anode) such that the solid electrolyte (e.g., the solid electrolyte material of the solid electrolyte) can facilitate the transport of ions (e.g., lithium ions) between the first and second electrodes, while being electronically non-conductive to prevent short circuits. However, it should be understood that in some embodiments, the battery or cell may additionally or alternatively include a liquid electrolyte. Details regarding liquid electrolytes are described above and elsewhere herein.

[0084] In some embodiments, the solid electrolyte comprises a ceramic material (e.g., particles of a ceramic material). Non-limiting examples of suitable ceramic materials include oxides (e.g., aluminum oxide, silicon oxide, lithium oxide), nitrides, and / or oxynitrides of aluminum, silicon, zinc, tin, vanadium, zirconium, magnesium, indium, and alloys thereof, LixMPySz (where x, y, and z are each an integer, e.g., an integer less than 32, an integer equal to or less than 24, an integer equal to or less than 16, an integer equal to or less than 8; and / or an integer equal to or greater than 8, an integer equal to or greater than 16, an integer equal to or greater than 24); and M=Sn, Ge, or Si), such as Li 22 SiP2S 18 , Li 24 MP2S 19 , or LiMP2S 12 (e.g., where M=Sn, Ge, Si), and LiSiPS, garnets, crystalline or glassy sulfides, phosphates, perovskites, antiperovskites, other ion-conducting inorganic materials, and mixtures thereof. LixMPySz particles may be formed, for example, using the raw material components Li2S, SiS2, and P2S5 (or alternatively Li2S, Si, S, and P2S5). In some embodiments, the solid electrolyte comprises a lithium ion conducting ceramic compound. In an exemplary embodiment, the ceramic compound is Li 24 SiP2S 19 In another exemplary embodiment, the ceramic compound is Li 22 SiP2S 18 It is.

[0085] In some embodiments, the ceramic material is selected from the group consisting of lithium nitride, lithium nitrate (e.g., LiNO), lithium silicate, lithium borate (e.g., lithium bis(oxalate)borate, lithium difluoro(oxalate)borate), lithium aluminate, lithium oxalate, lithium phosphate (e.g., LiPO, LiPO), lithium oxynitride, lithium germanosulfide, lithium oxide (LiO, Li ... iRO2), lithium fluorides (e.g., LiF, LiBF4, LiAlF4, LiPF6, LiAsF6, LiSbF6, Li2SiF6, LiSO3F, LiN(SO2F)2, LiN(SO2CF3)2), lithium lanthanum oxide, lithium titanium oxide, lithium borosulfide, lithium aluminosulfide, and lithium phosphosulfides, oxysulfides (e.g., lithium oxysulfide), and combinations thereof. In some embodiments, the plurality of particles may include Al2O3, ZrO2, SiO2, CeO2, and / or Al2TiO5 (e.g., alone or in combination with one or more of the above materials). In certain aspects, the plurality of particles may include Li-Al-Ti-PO4 (LATP). The choice of material (e.g., ceramic) depends on many factors, including, but not limited to, the properties of the layer and adjacent layers used in the electrochemical cell.

[0086] In some embodiments, the electrolyte is in the form of a layer having a particular thickness. The electrolyte layer may have a thickness of, for example, 1 μm or more, 5 μm or more, 10 μm or more, 15 μm or more, 20 μm or more, 25 μm or more, 30 μm or more, 40 μm or more, 50 μm or more, 70 μm or more, 100 μm or more, 200 μm or more, 500 μm or more, or 1 mm or more. In some embodiments, the thickness of the electrolyte layer is 1 mm or less, 500 μm or less, 200 μm or less, 100 μm or less, 70 μm or less, 50 μm or less, 40 μm or less, 30 μm or less, 20 μm or less, 10 μm or less, or 5 μm or less. Combinations of the above ranges are also possible (e.g., 1 μm or more, 1 mm or less). Other ranges are also possible.

[0087] The electrochemical cells described herein may be operated under the application of an anisotropic force. As understood in the art, an "anisotropic force" is a force that is not equal in all directions. In some embodiments, the electrodes or electrochemical cells described herein may be configured to withstand an applied anisotropic force (e.g., a force applied to improve the morphology or performance of an electrode in the cell) while maintaining its structural integrity. In some embodiments, the electrodes or electrochemical cells are adapted and arranged such that an anisotropic force having a component perpendicular to the active surface of a layer in the electrochemical cell is applied to the cell during at least one period during charging and / or discharging the cell.

[0088] In such a case, the anisotropic force includes a component perpendicular to the active surface of the electrodes (e.g., the first electrode, the second electrode) in the electrochemical cell. As used herein, the term "active surface" is used to describe the surface of the electrode where an electrochemical reaction can occur. A force with a "normal component" to the surface is given its usual meaning as understood by those skilled in the art, and includes, for example, a force that exerts itself at least partially in a direction substantially perpendicular to the surface. For example, if an object rests on a horizontal table and is only influenced by gravity, the object exerts a force in a direction substantially completely perpendicular to the surface of the table. If the object is also biased in a lateral direction across the horizontal table surface, the object exerts a force on the table that is not completely perpendicular to the horizontal surface, but includes a component perpendicular to the table surface. Those skilled in the art will understand other examples of these terms, particularly as they apply within the description of the present disclosure. In the case of a curved surface (e.g., a concave or convex surface), the component of the anisotropic force perpendicular to the active surface of the electrode may correspond to a component perpendicular to a plane tangent to the curved surface at the point where the anisotropic force is applied. The anisotropic force may in some cases be applied at one or more predetermined locations distributed over the active surface of the electrode or layer. In some embodiments, the anisotropic force is applied uniformly over the active surface of the layer.

[0089] Any of the electrochemical cell properties and / or performance metrics described herein may be achieved alone or in combination with one another while an anisotropic force is applied to the electrochemical cell (e.g., during charging and / or discharging of the cell). In some embodiments, the anisotropic force applied to a layer or electrochemical cell (e.g., during at least one period during charging and / or discharging of the cell) may include a component perpendicular to the active surface of the layer.

[0090] In some embodiments, the component of the anisotropic force perpendicular to the active surface of a layer or electrode is less than 1 kgf / cm 2 More than 2kgf / cm 2 Above 4kgf / cm 2 More than 6kgf / cm 2 Above, 7.5kgf / cm 2 Above, 8kgf / cm 2 Above, 10kgf / cm 2 Above, 12kgf / cm 2 Above, 14kgf / cm 2 Above, 16kgf / cm 2 Above, 18kgf / cm 2 Above, 20kgf / cm 2 Above, 22kgf / cm 2 Above, 24kgf / cm 2 Above, 26kgf / cm 2 Above, 28kgf / cm 2 Above, 30kgf / cm 2 Above, 32kgf / cm 2 Above, 34kgf / cm 2 Above, 36kgf / cm 2 Above, 38kgf / cm 2 More than, more than, 40kgf / cm 2 Above, 42kgf / cm 2 Above, 44kgf / cm 2 Above, 46kgf / cm 2 Above, 48kgf / cm 2 In some embodiments, the component of the anisotropic force perpendicular to the active surface is greater than, for example, 50 kgf / cm 2 Below, 48kgf / cm 2 Below, 46kgf / cm2 Below, 44kgf / cm 2 Below, 42kgf / cm 2 Below, 40kgf / cm 2 Below, 38kgf / cm 2 Below, 36kgf / cm 2 Below, 34kgf / cm 2 Below, 32kgf / cm 2 kgf / cm 2 Below 30kgf / cm 2 Below, 28kgf / cm 2 Below, 26kgf / cm 2 Below, 24kgf / cm 2 Below, 22kgf / cm 2 Below, 20kgf / cm 2 Below, 18kgf / cm 2 Below, 16kgf / cm 2 Below, kgf / cm 2 Below, 14kgf / cm 2 Below, 12kgf / cm 2 Below, 10kgf / cm 2 kgf / cm 2 Below, 8kgf / cm 2 Below, 6kgf / cm 2 Below, 4kgf / cm 2 Below, 2kgf / cm 2 It is possible to specify a pressure of less than or equal to 1 kgf / cm. Combinations of the above ranges are also possible (e.g., 1 kgf / cm 2 Above, 50kgf / cm 2 (See below). Other ranges are possible.

[0091] The anisotropic force applied during at least a portion of the charge and / or discharge may be applied using any method known in the art. In some embodiments, the force may be applied using a compression spring. The force may also be applied using other elements (either inside or outside the containment structure), including, but not limited to, Belleville washers, machine screws, pneumatic devices, and / or weights. In some cases, the cells are pre-compressed before being inserted into the containment structure, and expand upon insertion into the containment structure to generate a net force on the cells. Suitable methods for applying such forces are described in detail, for example, in U.S. Pat. No. 9,105,938.

[0092] The electrodes described herein can be part of an electrochemical cell that is incorporated into a battery (e.g., a rechargeable battery). In some embodiments, an electrochemical cell (including one or more or electrodes described herein) can be used to power or otherwise be incorporated into an electric vehicle. As a non-limiting example, the electrochemical cells described herein can in some cases be used to power the drivetrain of an electric vehicle. The vehicle can be any vehicle suitable for traveling on land, sea, and / or air. For example, the vehicle can be a car, a truck, a motorcycle, a boat, a helicopter, an airplane, and / or any other suitable type of vehicle. EXAMPLES

[0093] The following examples are intended to illustrate some embodiments of the present invention, but do not exemplify the full scope of the invention.

[0094] Example 1 The following examples demonstrate the improved cycle life performance of a second electrode (ie, anode) in which at least a portion of the second electrode current collector surface is coated with magnesium. The electrochemical cells were fabricated as previously described. The cathode was prepared by depositing NCM811 on a copper current collector. The anode was constructed by vapor depositing lithium metal (0.5 μm) on a 0.5 mil copper foil current collector. The cathode and anode were separated by an Entek 9 μm EP separator. In one electrochemical cell, the anode was magnesium vapor deposited on the surface of the current collector. Each electrochemical cell was charged at 30 mA and discharged at 300 mA for the first formation cycle, followed by charging at 75 mA and discharging at 300 mA for the remaining cycles.

[0095] The anode with a magnesium-coated copper current collector showed improved cycle life compared to electrochemical cells fabricated without a magnesium-coated current collector, as shown in Figure 4. All cells were charged and discharged at the same rate (75 mA charge / 300 mA discharge), including the initial formation cycle (30 mA charge / 300 mA discharge).

[0096] Example 2 The following examples demonstrate the effect of using elevated temperatures during the formation cycle. The electrochemical cell used in this example was fabricated as described in Example 1, except that elevated temperature was applied during the formation cycle. As shown in Figure 5, the cell showed higher cycling performance after the temperature was increased to 45°C during the initial formation cycle and during the normal cycle. In this example, 12 kg / cm was applied during the cycling process. 2 An anisotropic pressure of 1:3 FEC / DMC was used, and a copper current collector was used as the anode. Furthermore, higher FEC content showed improved cycle life in Lion28 (1:3 FEC / DMC) compared to Lion14 (1:4 FEC / DMC).

[0097] Example 3 The following example shows the effect of different applied amounts of anisotropic pressure on the cycling performance of the cell. An electrochemical cell was fabricated as described in Example 1. FIG. 6 shows a cell with improved cycle life after application of pressure.

[0098] Example 4 The following examples show the cycling performance of electrochemical cells with varying amounts of cathode active material. Electrochemical cells were fabricated as described in Example 1. FIG. 7 shows that the cell with the highest loading of NCM cathode active material showed improved cycling performance, even though less Li was cycled per cycle.

[0099] Example 5 The following example illustrates the effect of varying the applied voltage during the formation cycle. An electrochemical cell was constructed as described in Example 1.

[0100] Figure 8 shows the cycle performance of the cell charged and discharged at voltages of 4.35 V to 3.2 V, 4.6 V to 3.2 V, and 4.7 V to 3.2 V. The cycle performance improved as the cell was charged higher, as can be seen by the measurements at 4.7 V compared to 4.35 V.

[0101] Example 6 The following examples show the charge / discharge performance of several cathode active materials relative to electrochemical cell performance. The cathode active materials included NCM, LCO, and NCA with various ratios of these materials for each electrode. As shown in Figure 9, NCM851005 showed improved performance compared to other cathode active materials when cycling electrochemical cells containing this NCM electrode.

[0102] Although several embodiments of the invention have been described and illustrated herein, those skilled in the art can readily envision various other means and / or structures for carrying out and / or obtaining the functions and / or results and / or one or more advantages described herein, and each such variation and / or modification is deemed to be within the scope of the present disclosure. More generally, those skilled in the art will readily appreciate that all parameters, dimensions, materials, and configurations described herein are meant to be exemplary, and that the actual parameters, dimensions, materials, and / or configurations will depend on the particular use or application for which the teachings of the present disclosure are / are used. Those skilled in the art will recognize or be able to ascertain, using no more than routine experimentation, many equivalents to the specific embodiments of the invention described herein. Thus, the foregoing embodiments are presented by way of example only, and it will be understood that within the scope of the appended claims and their equivalents, the invention may be practiced otherwise than as specifically described and claimed. The present disclosure is directed to each individual feature, system, article, material, and / or method described herein. Furthermore, any combination of two or more such features, systems, articles, materials, and / or methods is within the scope of the present disclosure, provided that such features, systems, articles, materials, and / or methods are not mutually inconsistent.

[0103] As used in the specification and the claims, the indefinite articles "a" and "an" should be understood to mean "at least one," unless clearly indicated to the contrary.

[0104] As used in the specification and claims, the phrase "and / or" should be understood to mean "either or both" of conjugated elements, i.e., elements that are present conjunctively in some cases and disjointly in others. Unless expressly indicated, other elements may optionally be present other than the elements specifically identified by the "and / or" clause, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, "A and / or B," when used in conjunction with an open-ended term such as "comprising," means, in one embodiment, A without B (optionally including elements other than B); in another embodiment, B without A (optionally including elements other than A); in yet another embodiment, both A and B (optionally including other elements); and so forth.

[0105] As used in the specification and claims, "or" should be understood to have the same meaning as "and / or" as defined above. For example, when separating items in a list, "or" or "and / or" should be interpreted as being inclusive, i.e., including at least one, including more than one, of a number or list of elements, and optionally further items not listed. Only the items explicitly indicated, e.g., "only one of" or "exactly one of," or "comprising" when used in the claims, means including exactly one of a number or list of elements. In general, the term "or" as used herein will only be interpreted as indicating exclusive alternatives (i.e., "one or the other but not both") when preceded by a term of exclusivity, such as "either," "one of," "only one of," or "exactly one of." When used in the claims, "essentially comprising" has its ordinary meaning as used in the field of patent law.

[0106] As used in the specification and claims, the phrase "at least one" in reference to a list of one or more elements should be understood to mean at least one element selected from one or more elements in the list of elements, but not necessarily including at least one of each element specifically listed in the list of elements, and not necessarily excluding combinations of elements in the list of elements. This definition also allows for elements to be optionally present other than elements specifically identified in the list of elements, meaning related or unrelated to those elements specifically identified. Thus, as a non-limiting example, "at least one of A and B" (equivalently, "at least one of A or B," or, equivalently, "at least one of A and / or B") can mean, in one embodiment, at least one, including optionally more than one, A (optionally including elements other than B) in the absence of B; in another embodiment, at least one, including optionally more than one, B (optionally including elements other than A) in the absence of A; in yet another embodiment, at least one, including optionally more than one, A and at least one, including optionally more than one, B (optionally including other elements); etc.

[0107] Some embodiments may be embodied as a method, various examples of which have been described. The acts performed as part of the method may be ordered in any suitable manner. Thus, an embodiment may be configured to perform acts in a different order than shown, to include different (e.g., more or fewer) acts than those described, and / or to include performing some acts simultaneously, even though the acts have been shown as being performed sequentially in the specifically described embodiments above.

[0108] The use of ordinal terms such as "first," "second," "third," etc. in the claims to modify elements of the claims does not, in and of itself, imply a priority, precedence, or ordering of one element over another, or the chronological order in which acts of a method are performed, but is used solely as a label to distinguish one claim element having a particular name from other elements having the same name (for which the ordinal terminology is used).

[0109] Throughout the claims as well as in the specification, all transitional phrases such as "comprising," "including," "carrying," "having," "containing," "involving," "holding," and the like, are intended to be open-ended, i.e., to mean inclusive, but not limited to, the following. Only the transitional phrases "consisting of" and "consisting essentially of" are closed or semi-closed transitional phrases, respectively, as set forth in the United States Patent Office Manual of Patent Examining Procedures, Section 2111.03. [Explanation of symbols]

[0110] 100, 300 … electrochemical cells 110, 310 ... first electrode 120 ... second electrode 130 … electrolyte 140 ... Separator 150…protective layer 152 … SEI 210 … Voltage source 309 ... Potentiostat 320 … electrolyte 330 ... Current collector 340 ... Lithium metal layer 350…protective layer 360 … Lithium source

Claims

1. 1. An electrochemical cell comprising a first electrode comprising a lithium intercalation compound having a nickel content of 70 atomic % or greater relative to other transition metals in the lithium intercalation compound, applying one or more formation cycles to the second electrode, charging the second electrode with a first current to a voltage of 4.4 V or greater; and discharging the second electrode at a second current to a voltage less than 4.4 V; and forming a protective layer on at least a portion of the surface of the second electrode; A method for forming a protective layer on an electrode, comprising:

2. 1. An electrochemical cell comprising a first electrode, applying one or more formation cycles to the second electrode, charging the second electrode with a first current to a voltage of 4.4 V or greater; and discharging the second electrode at a second current to a voltage less than 4.4 V; and forming a protective layer on at least a portion of the surface of the second electrode; [0033] the protective layer contains a lithium compound; A method for forming a protective layer on an electrode, wherein the protective layer has an average thickness of 10 μm or less.

3. a first electrode comprising a lithium intercalation compound having a nickel content of 70 atomic % or greater relative to other transition metals in the lithium intercalation compound; a second electrode comprising a current collector; a separator between the first electrode and the second electrode; and a lithium source between the first electrode and the separator; Including, An electrochemical cell wherein the average thickness of the lithium between the second electrode and the separator is 30 μm or less.

4. a first electrode comprising a lithium intercalation compound having a nickel content of 70 atomic % or greater relative to other transition metals in the lithium intercalation compound; a second electrode comprising a current collector; a separator disposed between the first electrode and the second electrode; a protective layer provided on at least a portion of the surface of the second electrode; Equipped with the protective layer contains a lithium compound; An electrochemical cell, wherein the protective layer has an average thickness of 10 μm or less.

5. The protective layer is ２ , Li ２ CO ３ 5. The electrochemical cell of claim 3 or 4, comprising a lithium compound comprising LiF.

6. 3. The method of claim 1 or 2, wherein the first electrode comprises a lithium intercalation compound having a nickel content of 70 atomic % or greater relative to other transition metals in the lithium intercalation compound.

7. 3. The method of claim 1 or 2, wherein charging occurs at a rate of C / 40 or higher and / or 3C or lower.

8. 3. The method of claim 1 or 2, wherein the discharge occurs at a rate of ≧C / 40 and / or ≦10C.

9. 3. The method of claim 1 or 2, wherein charging occurs at a different rate than discharging.

10. 3. The method of claim 1 or 2, wherein discharging occurs at a faster rate than charging.

11. 3. The method of claim 1 or 2, further comprising applying one or more subsequent cycles different from the formation cycle, wherein the voltage of the first electrode and / or the second electrode does not exceed 4.4 V.

12. 3. The method of claim 1 or 2, further comprising performing one or more or ten or fewer formation cycles.

13. 3. The method of claim 1 or 2, wherein the one or more formation cycles occur at or within the first 10 charge-discharge cycles of the first electrode and / or the second electrode.

14. 3. The method of claim 1 or 2, further comprising heating the second electrode to a temperature of 40° C. or greater during the one or more formation cycles.

15. 5. An electrochemical cell or method according to any one of claims 1 to 4, wherein the first electrode and / or the second electrode are lithium-free.

16. 5. The electrochemical cell or method of any one of claims 1 to 4, wherein the protective layer comprises Mg.

17. 5. The electrochemical cell or method of any one of claims 1 to 4, further comprising a current collector, at least a portion of a surface of the current collector comprising magnesium or a magnesium alloy.

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