Silicon-containing lithium-ion battery

Abstract

A lithium-ion battery cell includes an electrode assembly having an anode and a cathode. The anode includes an anode current collector and a first silicon-containing anode active material layer disposed on a first side of the anode current collector, the first silicon-containing anode active material layer containing at least 85 atomic percent silicon. The cathode includes a cathode current collector and a first cathode active material layer disposed on a first side of the cathode current collector, the first side of the cathode current collector being in close proximity to the first side of the anode current collector. The battery cell further includes a lithium-ion electrolyte disposed between the anode and the cathode, and a battery cell housing that accommodates the electrode assembly and the electrolyte. During an electrochemical charging event, the first cathode active material layer is compressible to less than 95% of its thickness before the charging event.

Description

[Technical Field]

[0001] Cross-reference of related applications This application claims priority to U.S. Provisional Application No. 63 / 498,400, filed on 26 April 2023, the entirety of which is incorporated herein by reference for all purposes.

[0002] This disclosure relates to lithium-ion battery cells. [Background technology]

[0003] Silicon has been proposed for lithium-ion batteries to replace conventional graphite-based anodes, which have a limited energy storage capacity of approximately 370 mAh / g. Silicon readily alloys with lithium and has a theoretically much higher energy storage capacity (approximately 3600-4200 mAh / g at room temperature) than carbon (graphite) anodes. However, the insertion and extraction of lithium into the silicon matrix causes significant volume expansion (>300%) and contraction. This can cause the silicon to rapidly pulverize into small particles, potentially leading to electrical disconnection from the current collector. Such expansion can compromise the structural integrity of the lithium-ion battery cell housing, potentially causing cell failure and even rupture. Consequently, when silicon is used as an anode, it is typically added in only a few weight percent compared to conventional graphite.

[0004] Despite research into various approaches, silicon-based batteries have not yet had a significant market impact due to unresolved issues. [Overview of the Initiative]

[0005] There is still a demand for lithium-ion battery cells that can withstand the expansion of silicon-based anodes while retaining many of the advantages that silicon brings to cells.

[0006] A lithium-ion battery cell according to an embodiment of the present disclosure includes an electrode assembly having an anode, a cathode, and optionally a first separator. The anode includes an anode current collector and a first silicon-containing anode active material layer disposed on a first side of the anode current collector, wherein the first silicon-containing anode active material layer contains at least 85 atomic percent silicon. The cathode includes a cathode current collector and a first cathode active material layer disposed on a first side of the cathode current collector, wherein the first side of the cathode current collector is adjacent to the first side of the anode current collector. An optional first separator is disposed between the first cathode active material layer and the first anode active material layer. The battery cell further includes a lithium-ion-containing electrolyte disposed between the anode and the cathode and in contact with the anode and the cathode. The electrolyte may be in contact with any specific components of the anode and the cathode. A battery cell includes a housing that contains an electrode assembly and an electrolyte, the housing including a positive battery terminal that is electrically connected to the cathode and a negative battery terminal that is electrically connected to the anode.

[0007] According to some embodiments, a battery cell may include a compressible separator, a compressible cathode active material layer, a compressible current collector, a compressible central element, a compressible liner, an electrolyte reservoir, a high porosity silicon-containing anode active material, or any combination thereof.

[0008] This disclosure provides a lithium-ion battery cell having at least one of the following advantages over conventional lithium-ion battery cells: longer battery life, improved safety, reduced pressure rise within the cell, higher gravimetric charge capacity, higher volumetric charge capacity, improved stability at high charge and / or discharge rates of ≥1C, improved low-temperature performance, improved physical durability, simplified manufacturing process, improved repeatability of the manufacturing process, manufacturing process with less environmental impact, or reduced dimensional changes during operation. [Brief explanation of the drawing]

[0009] [Figure 1A] This is a cross-sectional view of a non-limiting example of an anode according to several embodiments. [Figure 1B] The cutting line AA is a plan view of the anode that can represent the cross-section shown in Figure 1A. [Figure 1C] The cutting line AA is a plan view of the anode that can represent the cross-section shown in Figure 1A. [Figure 2A] This is a cross-sectional view of a non-limiting example of a cathode according to several embodiments. [Figure 2B] The cutting line AA is a plan view of the cathode that can represent the cross-section shown in Figure 2A. [Figure 2C] The cutting line AA is a plan view of the cathode that can represent the cross-section shown in Figure 2A. [Figure 3A] This is a cross-sectional view of a non-limiting example of a multilayer electrode assembly according to several embodiments. [Figure 3B] The image shown is a rotated version of Figure 3A. [Figure 4] Non-limiting examples of cylindrical battery cells according to several embodiments are shown. [Figure 5A] This is a perspective view of a non-limiting example of a prismatic battery cell according to several embodiments. [Figure 5B] Figure 5A is a simplified schematic cross-sectional view of a prism cell cut along the XY plane. [Figure 6A] These are schematic cross-sectional views of an anode according to several embodiments. [Figure 6B] Cross-sectional views of anodes are shown, including several non-restrictive examples of lithium storage nanostructures. [Figure 7] These are double-sided anode cross-sectional views according to several embodiments. [Figure 8A] This is a cross-sectional view of a compressible element according to various embodiments. [Figure 8B] This is a cross-sectional view of a compressible element according to various embodiments. [Figure 8C] This is a cross-sectional view of a compressible element according to various embodiments. [Figure 9A] This is a schematic cross-sectional view of some battery cells having compressible separators according to various embodiments. [Figure 9B]This is a schematic cross-sectional view of some battery cells having compressible separators according to various embodiments. [Figure 9C] This is a schematic cross-sectional view of some battery cells having compressible separators according to various embodiments. [Figure 9D] This is a schematic cross-sectional view of some battery cells having compressible separators according to various embodiments. [Figure 9E] This is a schematic cross-sectional view of some battery cells having compressible separators according to various embodiments. [Figure 9F] This is a schematic cross-sectional view of some battery cells having compressible separators according to various embodiments. [Figure 10] This is a schematic cross-sectional view of an electrode having a compressible current collector according to several embodiments. [Figure 11] This is a schematic cross-sectional view of a part of a battery cell having a compressible cathode active material layer according to several embodiments. [Figure 12] This is a schematic cross-sectional view of a solid-state battery cell according to several embodiments. [Modes for carrying out the invention]

[0010] These drawings are for illustrative purposes only and should not be to scale. Terms such as “overlapping” and “on top” include, but do not require, direct contact (unless such direct contact is described or explicitly required by the function). In this specification, “average” means the mean, median, or mode, and “average thickness” may be determined based on at least three measurements (e.g., 3, 4, 5, 6, 7, 8, 9, 10 or more). Additional details relating to specific embodiments of this application can be found in U.S. Patent Publication No. 2019 / 0267631, U.S. Patent Publication No. 2020 / 0411851, U.S. Patent Publication No. 2021 / 0050584, U.S. Patent Publication No. 2021 / 0057733, U.S. Patent Publication No. 2021 / 0057757, U.S. Patent Publication No. 2021 / 0057755, U.S. Patent Publication No. 2021 / 0066702, PCT International Publication No. WO2022 / 005999, PCT International Publication No. WO2021 / 2073. These may be found in PCT applications No. 57, PCT / US2021 / 064018, U.S. Patent Application Publication No. 2022 / 0344627, PCT applications No. PCT / US2022 / 053321, PCT / US2023 / 024254, PCT applications No. PCT / US2023 / 025773, PCT applications No. PCT / US2024 / 015578, and PCT applications No. PCT / US2024 / 015585, all of which are incorporated herein by reference for all purposes.

[0011] A lithium-ion battery cell typically includes at least one anode, at least one cathode, at least one separator (if the electrolyte is liquid) positioned between the anode and the cathode, and a non-aqueous lithium-ion electrolyte positioned between the anode and the cathode and in contact with the anode and cathode. These components, also called an electrode assembly, are housed within a battery cell housing that includes a positive electrode battery terminal for external connection to the cathode and a negative electrode battery terminal for external connection to the anode.

[0012] Figure 1A is a cross-sectional view of a non-limiting example of an anode according to several embodiments. The anode 100 includes an anode current collector 101. A first silicon-containing anode active material layer 107a is provided on the first side 101a of the anode current collector. A second silicon-containing anode active material layer 107b is provided on the second side 101b of the anode current collector. In some embodiments, at least one of the anode active material layers contains at least 85 atomic percent silicon, deposited, for example, by a PVD or CVD process. The second silicon-containing anode active material layer may be substantially identical or different from the first silicon-containing active material layer with respect to its chemical composition or physical properties (such as thickness and porosity). In this specification, “substantially identical” means, in some cases, that an index describing a component is within 5% of the corresponding index of the component being compared. Indices include, but are not limited to, height, width, molecular weight, density, position, or orientation.

[0013] The anode current collector may include an electrical contact area 102 where no anode active material is present. For example, an area from which the anode active material has been removed or from which its accumulation has been prevented. As shown in the figure, the anode contact area 102 may include a contact area 102a on the first side of the anode current collector and a contact area 102b on the second side of the anode current collector. In some other embodiments, only one side is devoid of anode active material. As described elsewhere, the contact area may directly touch a battery terminal element or represent an area to which a tab element (not shown) can be joined. The tab element makes contact with the battery terminal element. The battery terminal element is a conductive structure within the cell that helps establish an electrical connection between the current collector and a given battery terminal.

[0014] Figure 1B is a plan view of anode 100, where the cutting line AA may represent the cross-section shown in Figure 1A. As shown in the figure, the contact area 102 may correspond to the edge area of ​​the anode current collector extending along the longitudinal direction (Y-axis) of the anode. In some embodiments (not shown), the contact area may extend along the short-side direction (X-axis) of the anode and is typically used in combination with a tab element. Figure 1C is a plan view of anode 100', where the cutting line A'-A' may correspond to the cross-section shown in Figure 1A. Anode 100' may be similar to anode 100, except that the contact area 102' is limited to a local edge area of ​​the anode current collector rather than the entire longitudinal direction. Such a configuration is typically used in combination with a tab element.

[0015] Figure 2A is a cross-sectional view of a non-limiting example of a cathode according to several embodiments. The cathode 130 includes a cathode current collector 131. A first cathode active material layer 137a is provided on the first side 131a of the cathode current collector. A second cathode active material layer 137b is provided on the second side 131b of the cathode current collector. The cathode current collector may include an electrical contact area 132 where cathode active material is not present. For example, an area from which cathode active material has been removed or an area from which deposition has been prevented. As shown in the figure, the cathode contact area 132 may include a contact area 132a on the first side of the cathode current collector and a contact area 132b on the second side of the cathode current collector. In some other embodiments, only one side has cathode active material. As described elsewhere, the contact area may directly touch the battery terminal element, or it may represent an area to which a tab element (not shown) can be joined. The tab element makes contact with the battery terminal element.

[0016] Figure 2B is a plan view of cathode 130, where cutting line AA may represent the cross-section of Figure 2A. As shown in the figure, the contact area 132 may correspond to the edge area of ​​the cathode current collector extending along the longitudinal direction (Y-axis) of the cathode. In some embodiments (not shown), the contact area may extend along the short-side direction (X-axis) of the cathode and is typically used in combination with a tab element. Figure 2C is a plan view of cathode 130', where cutting line A'-A' may correspond to the cross-section shown in Figure 2A. Cathode 130' may be similar to cathode 130, except that the contact area 132' is limited to a local edge area of ​​the anode current collector rather than the entire longitudinal direction. Such a configuration is typically used in combination with a tab element.

[0017] Figure 3A is a cross-sectional view of a non-limiting example of a multilayer electrode assembly according to several embodiments. In the cross-section, the electrode assembly 140 may include a first anode 100-1, a second anode 100-2, a first cathode 130-1, and a second cathode 130-2. The anodes and cathodes may be as described in Figures 1 and 2, but for clarity, not all elements are labeled. The first separator 120-1 may include a first anode active material layer 107a of the first anode 100-1 (provided on one side of the first anode current collector 101-1) and a first cathode active material layer 137a of the first cathode 130-1 (provided on one side of the first cathode current collector 131-1). In some embodiments, a second separator 120-2 may be provided between the second cathode active material layer 137b of the first cathode 130-1 (provided on the other side of the first cathode current collector 131-1) and the second anode active material layer 107b' of the second anode 100-2 (provided on one side of the second anode current collector 101-2). In some cases, a third separator 120-3 may be provided between the first anode active material layer 107a' of the second anode 100-2 (provided on the other side of the second anode current collector 101-2) and the first cathode active material layer 137a' of the second cathode 130-2 (provided on one side of the second cathode current collector 131-2).

[0018] The cross-section in Figure 3A may represent a portion of a multilayer electrode assembly that may be supplied in pouch cells, prismatic cells, cylindrical cells, or other cell forms. In some cases, the electrode assembly may have a winding or jelly roll structure. In this case, each anode / cathode in Figure 3A is simply a view of the same anode / cathode at a different location within the jelly roll / winding structure. For example, in a winding structure, the first anode 100-1 and the second anode 100-2 are structural parts of the same (continuous) anode formed using a common current collector, and are simply at different locations within the winding structure in cross-sectional view.

[0019] In some other embodiments, referring again to Figure 3A, the electrode assembly may include a stacked structure of individual sheets, for example, in a pouch cell. For example, anodes 100-1 and 100-2 may be formed by individual current collectors 101-1 and 101-2, respectively, on which individual active material layers may be formed. Even if the anodes are stacked individually, the anode sheets, and especially their current collectors, are usually electrically connected to one another. The same applies to the cathode in the stacked structure. In some cases, the anode and cathode are in the form of individual sheets and are provided between folds of a single (continuous) separator. For example, Figure 3B shows a rotated view of Figure 3A, where separator 120 is folded to surround the anode and cathode (i.e., folded along the Y-axis edge), forming separators 120-1, 120-2, and 120-3. This is a structure seen, for example, in a pouch cell. Although not shown in the diagram here, the separator may instead be folded along the X-axis edge, as long as the fold does not interfere with the contact area.

[0020] Regardless of whether the battery assembly is in a stacked or jelly-rolled structure, in a cross-sectional view such as Figure 3A, the anode, first separator, cathode, and second separator may define a repeating subunit of the battery assembly. The cross-section of the battery assembly may, in some cases, contain only a single subunit, but in some embodiments, it may have multiple subunits. For example, a battery assembly viewed in cross-section may contain 2 to 5, 5 to 10, 10 to 15, 15 to 20, 20 to 30, 30 to 40, 4 to 50 subunits, any combination within these ranges, or even more than 50 subunits. In some cases, the battery assembly may contain a partial subunit at either end. For example, the end may be an anode or a cathode.

[0021] Cylindrical cell Figure 4 shows non-limiting examples of cylindrical battery cells according to several embodiments. The cylindrical battery cell 460 may be similar to that described in U.S. Patent Application Publication No. 2023 / 0006189, the whole of which is incorporated herein by reference for any use. The battery includes a housing which may include a cylindrical casing 20, an insulating gasket 40, and a top cap assembly 30 coupled to the opening of the casing 20 via a gasket interposed between the top cap and the opening of the casing 20. The housing is configured to house an electrode assembly 10 inside it. The casing 20 may be in the form of a can and may include a base positioned opposite the top cap. In some embodiments, a central element (e.g., a center pin) 60 is located at the center of the electrode assembly 10. The electrode assembly 10 includes a cathode (positive electrode) 11, a separator 12 (which may include a first separator 12-1 and a second separator 12-2, respectively), and an anode (negative electrode) 13, which are sequentially stacked. The separator 12 is positioned between the cathode 11 and the anode 13, and the two are insulated from each other. The electrode assembly 10 may be a cylindrical jelly roll type formed by stacking the cathode 11, separator 12, and anode 13 and winding them helically around a central element 60. The cathode, anode, and separator will be described in more detail elsewhere in this specification.

[0022] The cathode 11 and anode 13 each include cathode and anode active material layer regions, i.e., areas 11a and 13a, and uncoated edge regions (i.e., contact areas) 11b and 13b where active material is absent and a foil current collector is present. The uncoated edge region 11b of the cathode and the uncoated edge region 13b of the anode may be located at opposing ends of the electrode assembly 10.

[0023] When arranged in a jelly-roll state within the battery housing, the positive electrode current collector plate 11d (battery terminal element) may be connected to the uncoated edge region 11b of the cathode of the electrode assembly 10, and the negative electrode current collector plate 13d (battery terminal element) may be connected to the uncoated edge region 13b of the anode of the electrode assembly 10. The positive electrode current collector plate 11d may be formed to be narrower than the negative electrode current collector plate 13d, so that the negative electrode current collector plate 13d is in contact with the casing 20, while the positive electrode current collector plate 11d is spaced apart from the casing 20 and does not make contact. Insulating material may be provided in the edge area of ​​the positive electrode current collector plate.

[0024] In some embodiments, the lead tab 37 (battery terminal element) may be electrically connected to the positive electrode current collector plate 11d. One end of the lead tab 37 may be welded to the positive electrode current collector plate 11d, and the other end may be electrically connected to the top cap assembly 30. The lead tab 37 may be bent toward one face of the electrode assembly 10 to increase the contact area with the top cap assembly 30.

[0025] An insulating plate 50 having an opening for exposing the central element 60 may be positioned on the positive electrode current collector plate 11d. The insulating plate 50 may be formed larger than the positive electrode current collector plate 11d so as to contact the inner surface of the casing 20. If the insulating plate 50 is formed larger than the positive electrode current collector plate 11d as described above, a certain gap is formed between the positive electrode current collector plate 11d and the casing 20, depending on the width of the insulating plate 50 protruding from the positive electrode current collector plate 11d. The gap between the positive electrode current collector plate 11d and the casing 20 may help prevent the positive electrode current collector plate 11d and the casing 20 from contacting each other and short-circuiting. The lead tab 37 may be connected to the first auxiliary plate 34 of the electrode assembly 10 via the opening 51 of the insulating plate 50.

[0026] Since the electrode assembly 10 is wound around the central element 60, the central element 60 may be located approximately in the center of the electrode assembly 10 and aligned with the insertion direction of the electrode assembly 10 into the casing 20. In some embodiments, the central element 60 may be formed of a material with a certain degree of rigidity (e.g., metal) so that it undergoes minimal deformation under external impact or internal pressure. In some cases, the central element may be formed of a material with less rigidity than metal (e.g., polymer or foam). In some cases, the central element may be compressible when subjected to internal pressure. In some cases (not shown), the cell may include a compressible liner between the central element and the electrode assembly.

[0027] If the central element 60 is made of a conductive metal, the opposite end of the central element 60 is positioned to be electrically insulated from the positive electrode current collector plate 11d and the negative electrode current collector plate 13d. For example, an insulating pad 52 may be placed between the lower end of the central element 60 and the corresponding negative electrode current collector plate 13d. The upper end of the central element 60 insulates through a through hole formed in the center of the positive electrode current collector plate 11d and is supported by an insulating plate 50. In this case, the upper end of the central element 60 may be separated from the through hole in the positive electrode current collector plate 11d, or an insulating element (not shown) may be interposed between them. This restricts the movement of the central element 60 in the longitudinal direction of the central pin 60 and maintains the central element 60 in a stable position at the center of the electrode assembly 10.

[0028] The casing 20 may have an opening for inserting the electrode assembly 10 and may be formed to have a shape substantially identical to that of the electrode assembly 10, for example, a cylindrical shape. The casing 20 may be connected to the negative electrode current collector plate 13d of the electrode assembly to function as the negative electrode terminal of the rechargeable battery. In some embodiments, the casing 20 may be formed of a rigid material such as a conductive metal including, but not limited to, aluminum, an aluminum alloy, or nickel-plated steel.

[0029] The top cap assembly 30 is positioned at the opening of the casing 20 and is coupled to the casing 20 via a gasket 40 between them. The gasket 40 insulates the casing 20 from the cap assembly 30 and seals the inside of the casing 20 containing the electrode assembly 10 and the electrolyte solution (if a solid electrolyte is not used). In some cases, the cap assembly 30 includes a cap plate 31, a positive temperature coefficient element 35, a vent plate 32, an insulating element 33, a first auxiliary plate 34, and a second auxiliary plate 38. The first auxiliary plate 34 is electrically connected to the lead tabs 37 of the electrode assembly and may be welded to the lead tabs 37. The second auxiliary plate 38 is laminated on the first auxiliary plate 34 and is electrically connected to the first auxiliary plate 34 and may be welded to the first auxiliary plate 34. The second auxiliary plate 38 is positioned at the center of the electrode assembly 10 corresponding to the central element 60 and has a through hole that exposes the first auxiliary plate 34.

[0030] The vent plate 32 may be positioned on the second auxiliary plate 38 via an insulating element 33. The edges of the vent plate 32 may be inserted into a gasket 40 and coupled to the casing 20. The vent plate 32 may have a vent 32a positioned in a location corresponding to the central element 60. The vent 32a protrudes from the vent plate 32 toward the electrode assembly 10 and is electrically connected to the first auxiliary plate 34 by contacting it through a through hole. The vent plate 32 has a notch 32b around the vent 32a to induce rupture of the vent 32a. By rupturing under predetermined pressure conditions, the vent 32a disconnects the electrical connection with the first auxiliary plate 34 and releases internal gas to the outside. In other words, if the internal pressure of the casing 20 increases due to gas generation, the notch 32b may rupture in advance to release the gas to the outside through the exhaust port 31d, thereby preventing the rechargeable battery from expelling. Furthermore, if the vent 32a breaks due to an abnormal reaction, the electrical connection between the vent plate 32 and the first auxiliary plate 34 is interrupted. Consequently, the electrical connection between the cap plate 31, which is electrically connected to the vent plate 32, and the first auxiliary plate 34 is interrupted, thereby eliminating the flow of current.

[0031] The cap plate 31 may include a central plate 31a corresponding to the central element 60 at the center of the electrode assembly 10, a plurality of branch portions 31b extending from the central plate 31a toward the insulating gasket 40, and a connecting plate 31c inserted into and joined to the insulating gasket 40 to connect the ends of the branch portions 31b. The exhaust port 31d may be formed between adjacent branch portions 31b that are open to the outside.

[0032] The branch section 31b is connected to the center plate 31a in a bent state from the connecting plate 31c, causing the center of the cap plate 31 to protrude outward from the casing 20. The cap plate 31 is electrically connected to the positive electrode current collector plate 11d via the vent plate 32, the second auxiliary plate 38, the first auxiliary plate 34, and the lead tab 37, and can be used as the positive electrode terminal of a rechargeable battery. Therefore, by causing the center of the cap plate 31 to protrude outward from the casing 20, connection to the terminals of external equipment can be facilitated.

[0033] In some embodiments, the PTC (Positive Temperature Coefficient) element may be formed along the second plate of the cap plate 31 and inserted and bonded to the gasket 40 in a laminated state between the second plate of the cap plate and the edge of the vent plate. The positive temperature element 35 may be mounted between the cap plate 31 and the vent plate 32 to control the current between the cap plate 31 and the vent plate 32 in accordance with the internal temperature of the rechargeable battery. When the internal temperature is within a predetermined range, the positive temperature element 35 functions as a conductor that electrically connects the cap plate 31 and the vent plate 32. When the internal temperature exceeds a predetermined temperature, the electrical resistance of the positive temperature element 35 increases significantly. As a result, the positive temperature element 35 can block the flow of charging or discharging current between the cap plate 31 and the vent plate 32.

[0034] The edge of the cap assembly 30 can be inserted into the opening of the casing 20 after it has been inserted into the insulating gasket 40 with the vent plate 32, positive temperature element 35, and cap plate 31 stacked on top of each other. Next, the cap assembly 30 is tightened into the opening of the casing 20 by a clamping process. In this case, a beading portion 21 recessed toward the radial center of the casing 20 and a clamp portion 22 that grips the outer circumference of the insulating gasket 40 into which the cap assembly 30 is inserted can be formed on the casing 20.

[0035] Although not shown in the illustration, the battery cell 460 may further include a compressible liner positioned between the cylindrical casing 20 and the battery assembly 10. The top cap and / or casing further include one or more ports for injecting or discharging the electrolyte. The battery cell 460 is merely one non-limiting example, and many options are available. In some cases, the battery may utilize so-called tablet technology, in which the edge contact area of ​​the current collectors may include notches to bend them to contact each other and, if necessary, weld them to contact the ends of the battery cell.

[0036] In some embodiments, the cylindrical cell standard may be the so-called 18650, 21700, or 4680. In some cases, the wall thickness of the cylindrical cell casing may be in the range of 0.2–0.3 mm, 0.3–0.4 mm, 0.4–0.5 mm, 0.5–0.7 mm, 0.7–0.9 mm, 0.9–1.1 mm, 1.1–1.3 mm, 1.3–1.5 mm, or any combination of these ranges. For example, the wall thickness of steel (e.g., nickel-plated steel) may be in the range of 0.2–0.5 mm. In another example, the wall thickness of aluminum or aluminum alloy casing walls may be in the range of 0.4–0.9 mm. Greater thickness increases resistance to cell expansion but increases weight and cell volume (which reduces the energy density of the battery cell). In some embodiments of this disclosure, it is possible to reduce the casing wall thickness and / or weight and / or volume.

[0037] prism-shaped cell In some embodiments, the jelly roll structure can be used in battery cell structures other than cylindrical cells, such as prismatic cells. Figure 5A is a perspective enlargement of a non-limiting example of a prismatic cell according to some embodiments. Figure 5B is a simplified schematic cross-section of a prismatic cell, cut along the XY plane of a prismatic cell like the one in Figure 5A. The prismatic battery cell 560 may include a casing 550 in the shape of a rectangular box. The casing may be formed of a rigid material such as a metal such as steel or aluminum. The jelly roll battery assembly 540 is placed inside the casing 550. The battery assembly 540 may include an anode 500, a first separator 520-1, a cathode 530, and a second separator 520-1, all wrapped around an elongated central element 542. The central element can be rigid or compressible. The battery cell may include an anode tab 509 and a cathode tab 539 for external connections to the cell. An insulating plate or gasket 557 may be placed between the top of the battery assembly and the top lid 551. In some cases, the top lid may be electrically insulating. In some cases, the top lid may be formed of a conductive metal, but at least one or both of the anode tab and cathode tab are insulated from the top lid. The cathode tab and anode tab may extend through the insulating plate and openings 553 and 554 in the top lid 551, respectively. Insulating adhesive or other material may be applied to the openings, optionally. The top lid 551 may be welded, glued, crimped, or otherwise secured to the casing 550. The top lid 551 may further include a port 556 used as an electrolyte injection port, an electrolyte discharge port, or both. Additional ports, not shown, may be provided. The battery cell 560 may further include a compressible liner 545 positioned between the electrode assembly 540 and the casing 550. A non-aqueous lithium-ion electrolyte 570 is also present inside the cell. Fasteners 544 may contribute to ensuring the stability of the various components of the battery assembly 540.

[0038] In some embodiments, the wall thickness of the prismatic cell casing may be in the range of 0.2–0.3 mm, 0.3–0.4 mm, 0.4–0.5 mm, 0.5–0.7 mm, 0.7–0.9 mm, 0.9–1.1 mm, 1.1–1.3 mm, 1.3–1.5 mm, or any combination of these ranges. For example, the wall thickness of an aluminum or aluminum alloy casing wall may be in the range of 0.4–1.5 mm. Larger thicknesses increase resistance to cell expansion but increase weight and cell volume (which reduces the energy density of the battery cell). In some embodiments of this disclosure, it is possible to reduce the casing wall thickness and / or weight and / or volume. In both cylindrical and prismatic cell configurations, in some embodiments, the jelly roll may be wound to a density less than the maximum density, thereby constituting a volume in which the total gap between the separator and adjacent electrodes corresponds to a range of 0.1%–0.5%, 0.5–1%, 1–2%, 2–3%, 3–5%, 5–7%, 7–10%, or any combination thereof, of the total volume of the wound electrode assembly.

[0039] anode Figure 6A is a schematic cross-sectional view of an anode according to several embodiments. For clarity, only one silicon-containing anode active material layer is shown. The anode 600 includes a current collector 601 and a silicon-containing anode active material layer 607 arranged on top of the current collector. For convenience, the anode active material layer 607 may also be referred to herein as a lithium storage layer. In some embodiments, at least one lithium storage layer may be a silicon-containing anode active material layer deposited by a physical vapor deposition (PVD) process (e.g., sputtering or electron beam) or by a chemical vapor deposition (CVD) process including but not limited to hot-wire CVD or plasma-enhanced chemical vapor deposition (PECVD). In some embodiments, the silicon-containing anode active material layer may be a interconnected porous lithium storage layer as described elsewhere herein. In some embodiments, the silicon-containing anode active material layer 607 contains at least 85 atomic percent silicon. The current collector 601 may include a surface layer 605 provided on a conductive layer 603 (e.g., a conductive metal layer). For convenience, the surface of the current collector is shown as flat in the figure, but as will be described later, the current collector may have a rough surface. The silicon-containing anode active material layer 607 may be provided on the surface layer 605. In some embodiments, the top of the silicon-containing anode active material layer 607 corresponds to the top surface 608 of the anode 600. In some embodiments, the silicon-containing anode active material layer 607 is in physical contact with the surface layer 605.

[0040] In some embodiments, the silicon-containing anode active material layer 607, such as a interconnected porous lithium storage layer, may substantially not include high aspect ratio nanostructures, such as spaced wires, pillars, tubes, or regular chain-like vertical channels penetrating the lithium storage layer. Figure 6B shows a cross-sectional view of an anode 670 provided on a current collector 680, including some non-limiting examples of lithium storage nanostructures such as nanowires 690, nanopillars 692, nanotubes 694, and nanochannels 696. Some of the lithium storage layers of this disclosure may include such nanostructures, but interconnected porous lithium storage layers generally do not. Unless otherwise specified, the term “lithium storage nanostructure” as used herein generally refers to a lithium storage active material structure (e.g., a structure of silicon, germanium, or an alloy thereof) having at least one cross-sectional dimension less than about 2,000 nm, excluding dimensions substantially perpendicular to the underlying substrate (such as layer thickness) and dimensions resulting from random pores and channels. Similarly, the terms “nanowire,” “nanopillar,” and “nanotube” refer to wires, pillars, and tubes, respectively, whose diameter is less than 2,000 nm in at least part of the structure. A “high aspect ratio” nanostructure has an aspect ratio greater than 4:1, which is generally the height or length of the structure (which can be measured along the axis of the structure aligned at an angle of 45 to 90 degrees to the surface of the underlying current collector) divided by the width of the structure (which can be measured roughly perpendicular to the axis of the structure). In some embodiments, a lithium storage layer (e.g., a interconnected porous lithium storage layer) is considered “substantially free” of lithium storage nanostructures if it has fewer than 10 lithium storage nanostructures on average (e.g., mean, median, or mode) per 1600 square microns (the number of lithium storage nanostructures is the sum of the number of nanowires, nanopillars, and nanotubes in the same unit area), and such lithium storage nanostructures have an aspect ratio of 4:1 or greater. Alternatively, the average number of the relevant lithium storage nanostructures per 1600 square microns may be less than 1.As described below, current collectors may have high surface roughness or contain nanostructures, but these mechanisms are separate from lithium storage layers and are distinct from lithium storage nanostructures.

[0041] In some embodiments, deposition conditions are selected in combination with current collectors, resulting in a relatively smooth lithium storage layer (e.g., a interconnected porous lithium storage layer) providing an anode with a diffuse reflectance or total reflectance of at least 10% or at least 20% (measured on the interconnected porous lithium storage layer side) at 550 nm. In some embodiments, anodes with such diffuse reflectance or total reflectance may be less susceptible to damage from physical handling. In some embodiments, anodes that are not substantially free of lithium storage nanostructures may have low reflectance and be susceptible to damage from physical handling.

[0042] The anodes of this disclosure are typically coated with anode active material on both sides. For example, Figure 7 is a cross-sectional view of a double-sided anode according to several embodiments. The current collector 701 may include a conductive layer 703 and surface layers (705a, 705b) provided on both sides of the conductive layer 703. Silicon-containing anode active material layers (707a, 707b) are arranged on both sides to constitute the anode 700. In some embodiments, at least one of the silicon-containing anode active material layers is deposited by a PVD or CVD process. The surface layers 705a and 705b (if present) may be identical or different in terms of composition, thickness, roughness, or other properties. Similarly, the silicon-containing anode active material layers 707a and 707b may be identical or different in terms of composition, thickness, porosity, or other properties. In some embodiments, one of the silicon-containing anode active material layers is deposited by a slurry coating method. In some cases, both silicon-containing anode active material layers are deposited by a PVD or CVD process.

[0043] Current collector In some embodiments, the current collector or conductive layer is characterized by a tensile strength Rm or yield strength Re. In some cases, the tensile strength and yield strength of the current collector depend primarily on the conductive layer. In some embodiments, this conductive layer may be thicker than the surface layer. If the tensile strength is too high or too low, handling in manufacturing processes such as roll-to-roll processes may become difficult. If the tensile strength is too low, deformation of the anode may occur during the electrochemical cycle of the anode and the associated expansion / contraction of the silicon-containing anode active material.

[0044] In some cases, the current collector or conductive layer has a tensile strength R in the range of 100-150 MPa, or 150-200 MPa, or 200-250 MPa, or 250-300 MPa, or 300-350 MPa, or 350-400 MPa, or 400-500 MPa, or 500-600 MPa, or 600-700 MPa, or 700-800 MPa, or 800-900 MPa, or 900-1000 MPa, or 1000-1200 MPa, or 1200-1500 MPa, or any combination of these ranges. m The present invention is characterized by having the following: In some embodiments, the current collector or conductive layer may have an average thickness in the range of 4 to 8 μm, or 8 to 10 μm, or 10 to 15 μm, or 15 to 20 μm, or 20 to 25 μm, or 25 to 30 μm, or 30 to 40 μm, or 40 to 50 μm, or any combination of these ranges.

[0045] In some embodiments, the conductive layer is at least 10 3 S / m, or at least 10 6 S / m, or at least 10 7The conductive layer has an conductivity of S / m and may include inorganic or organic conductive materials, or combinations thereof. In some embodiments, the conductive layer includes metallic materials, such as titanium (and its alloys), nickel (and its alloys), copper (and its alloys), or stainless steel. In some embodiments, the conductive layer may include a multilayer structure, for example, multiple metal layers. In some embodiments, the conductive layer may be a coated foil. In some embodiments, the conductive layer may include conductive carbon such as carbon black, carbon nanotubes, graphene, graphene oxide, reduced graphene oxide, and graphite.

[0046] In some embodiments, the conductive layer may be in the form of foil, mesh, fiber, or sheet of conductive material. In this specification, conductive “mesh” includes woven wire, carbon nanotubes, foam structures, foil with a perforated arrangement, or any conductive structure having openings found elsewhere. In some embodiments, the conductive layer may comprise multiple layers of different conductive materials. The conductive layer may be in the form of layers deposited on an insulating substrate (e.g., a polymer sheet or ceramic substrate coated with a conductive material including, but not limited to, nickel or copper, on both sides as necessary). In some embodiments, the conductive layer may comprise a mesh or sheet of conductive carbon, including, but not limited to, bundled carbon nanotubes or nanofibers, or carbon fibers.

[0047] If a higher tensile strength is desired, the conductive layer may include nickel (and certain alloys), titanium (and certain alloys), or brass (an alloy mainly of copper and zinc), bronze (an alloy mainly of copper and tin), CuMgAgP (an alloy mainly composed of copper, magnesium, silver and phosphorus), CuFe2P (an alloy mainly composed of copper, iron and phosphorus), CuNi3Si (an alloy mainly composed of copper, nickel and silicon), and other specific copper alloys. The nomenclature of metal alloys is not the stoichiometric molecular formula used in chemistry, but rather the nomenclature used by those skilled in alloy technology. For example, CuNi3Si does not mean that there are 3 nickel atoms and 1 silicon atom for each copper atom. In some embodiments, these nickel-based or copper-based high tensile strength conductive layers may include roll-formed nickel or copper alloy foils.

[0048] On the other hand, a mesh or sheet of conductive carbon, including but not limited to those formed from bundled carbon nanotubes or nanofibers, may provide a conductive layer with higher tensile strength. In some cases, the conductive carbon sheet or mesh may be compressible or deformable to reduce the expansion of silicon during charging. In some embodiments, a conductive metal intermediate layer may be interposed between the conductive carbon and the surface layer.

[0049] In some embodiments, the anode current collector may have a compressible structure described elsewhere in this specification.

[0050] In some embodiments, the current collector is characterized by having a surface roughness. In some embodiments, referring back to FIG. 6A, the top surface 608 of the silicon-containing anode active material layer 607 may have a lower surface roughness than the surface roughness of the current collector 601. In this specification, the comparison and measurement of surface roughness are performed using the arithmetic mean roughness e(R a ), root mean square roughness (R q ), maximum peak height roughness (R p ), mean maximum height (R z ), or peak density (P c ). In some embodiments, the current collector has a surface roughness Rz Surface roughness R ≥ 2.5 μm a It is characterized to have both ≥0.25 μm. In some embodiments, R z is in the range of 2.5-3.0 μm, or 3.0-3.5 μm, or 3.5-4.0 μm, or 4.0-4.5 μm, or 4.5-5.0 μm, or 5.0-5.5 μm, or 5.5-6.0 μm, or 6.0-6.5 μm, or 6.5-7.0 μm, or 7.0-8.0 μm, or 8.0-9.0 μm, or 9.0-10 μm, 10-12 μm, 12-14 μm, or any combination thereof. In some embodiments, R a This range is 0.25–0.30 μm, or 0.30–0.35 μm, or 0.35–0.40 μm, or 0.40–0.45 μm, or 0.45–0.50 μm, or 0.50–0.55 μm, or 0.55–0.60 μm, or 0.60–0.65 μm, or 0.65–0.70 μm, or 0.70–0.80 μm, or 0.80–0.90 μm, or 0.90–1.0 μm, or 1.0–1.2 μm, or 1.2–1.4 μm, or any combination thereof.

[0051] In some embodiments, some or most of the surface roughness of the current collector may be imparted by a conductive layer. Alternatively, some or most of the surface roughness of the current collector may be imparted by a surface layer. Furthermore, any combination of a conductive layer, a metal interlayer, and a surface layer may substantially contribute to the surface roughness. In some embodiments, the conductive layer may be equipped with a roughening mechanism, such as an electrodeposition roughening mechanism, to increase the surface roughness. Alternatively, or in combination with an electrodeposition roughening mechanism, the conductive layer may be subjected to another electrochemical, chemical, or physical treatment to impart a desired surface roughness before the formation of the surface layer (if used). In some embodiments, roughening of the conductive layer may include, for example, physical abrasion (sanding, sandblasting, polishing, etc.), ablation (by laser ablation, etc.), embossing, stamping, casting, imprinting, chemical treatment, electrochemical treatment, or heat treatment. In some cases, the roughening mechanism may be random or have a predetermined pattern.

[0052] surface layer In some embodiments, the surface layer may provide chemical components that facilitate the formation of an adhesive silicon-containing anode active material layer, particularly in commercially useful loads or thicknesses of the anode active material layer. In some cases, deposition on the conductive layer alone may be insufficient to provide even initial adhesion, and the anode active material may be easily brushed off or peeled off. Even if sufficient initial adhesion is present, it may become insufficient during electrochemical formation and cycling. Some non-limiting examples of surface layers are described below. In some cases, the surface layer may comprise two or more separate sub-surface layers having different chemical components. In some cases, the surface layer or even the sub-surface layers may comprise a mixture of different surface layer materials.

[0053] In some embodiments, the thickness of the surface layer may be as thin as a single molecular layer. In some embodiments, the thickness of the surface layer is in the range of 0.0001 μm to 0.0002 μm, or 0.0002 μm to 0.0005 μm, or 0.0005 μm to 0.001 μm, or 0.001 μm to 0.005 μm, or 0.002 μm to 0.005 μm, or 0.005 μm to 0.01 μm, or 0.01 μm to 0.02 μm, or 0.02 μm to 0.03 μm, or 0.03 μm to 0.05 μm, or 0.05 μm to 0.1 μm, or 0.1 μm to 0.2 μm, or 0.2 μm to 0.5 μm, or 0.5 μm to 1 μm, or 1 μm to 2 μm, or 2 μm to 5 μm, or any combination thereof.

[0054] In some embodiments, the surface layer or sublayer may contain a metal-oxygen compound. In some cases, the metal-oxygen compound may contain a metal oxide or metal hydroxide, e.g., a transition metal oxide or transition metal hydroxide. In some cases, the metal-oxygen compound may contain an oxometalate, e.g., a transition metal oxometalate. In some embodiments, the surface layer may contain a silicon compound containing or derived from a siloxane, silane (i.e., a silane-containing compound), silazane, or their reaction products. In this specification, “silicon compound” does not include simple elemental silicon such as amorphous silicon. In some embodiments, the surface layer may contain a silicate compound. In some embodiments, the surface layer may contain a metal silide, e.g., a transition metal silide. In some embodiments, the surface layer may contain a metal chalcogenide (e.g., a metal sulfide), e.g., a transition metal sulfide.

[0055] Metal-oxygen compounds In some embodiments, the surface layer or subsurface layer contains a metal-oxygen compound. The metal-oxygen compound may include alkali metals, alkaline earth metals, transition metals, or post-transition metals. Unless otherwise specified, the term “transition metal” as used anywhere in this application includes any element from Group 3 through Group 12 of the periodic table, as well as lanthanides and actinides. The metal-oxygen compound may include metal oxides, metal hydroxides, oxometalates, or mixtures thereof. In some cases, the metal-oxygen compound may include transition metal oxides, transition metal hydroxides, transition metal oxometalates, or mixtures thereof. In some embodiments, a metal interlayer may be provided between the conductive layer and the surface layer containing the metal-oxygen compound. In some embodiments, the metal interlayer may be a transition metal. In some cases, the metal interlayer may include zinc, nickel, or an alloy of zinc and nickel. The interlayer may be considered part of the conductive layer, thereby being positioned between the surface layer and the remainder of the underlying conductive layer.

[0056] metal oxides In some embodiments, the surface layer or sub-surface layer may contain a metal oxide. In some embodiments, the metal oxide may contain a transition metal oxide. In some embodiments, the metal oxide may contain oxides of scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, yttrium, zinc, molybdenum, tungsten, silver, zirconium, tantalum, hafnium, tin, aluminum, indium, or niobium. In some embodiments, the metal oxide may be a conductive doped oxide, including, but not limited to, indium-doped tin oxide (ITO) or aluminum-doped zinc oxide (AZO). In some embodiments, the metal oxide may contain alkali metal oxides or alkaline earth metal oxides. In some embodiments, the metal oxide may contain lithium oxide. The metal oxide may contain a mixture of metal oxides. For example, "nickel oxide" may optionally contain other metal oxides in addition to nickel oxide. In some embodiments, the metal oxide includes oxides of alkali metals (e.g., lithium or sodium) or alkaline earth metals (e.g., magnesium or calcium) and oxides of transition metals (e.g., titanium, nickel, or copper). In some embodiments, the metal oxide may contain a certain amount of hydroxide such that the ratio of oxygen atoms present as hydroxide to oxygen atoms present as oxide is 1:1 or less, or 1:2 or less, 1:3 or less, or 1:4 or less, respectively. The metal oxide may include stoichiometric oxides, non-stoichiometric oxides, or both. In some embodiments, the metal in the metal oxide may exist in multiple oxidation states. Generally, oxometalates can be considered a subclass of metal oxides. For clarity, unless otherwise specified, oxometalates are excluded when "metal oxide" in this specification refers to use in surface layers or sublayers.

[0057] In some embodiments, the thickness of the metal oxide surface layer or sublayer may be at least one monolayer, or at least two, three, five, or ten monolayers. In some embodiments, the average thickness of the surface layer or sublayer having the metal oxide material may be at least 0.1 nm, or at least 0.2 nm. In some embodiments, the average thickness of the surface layer or sublayer having the metal oxide material may be less than 5000 nm, or less than 3000 nm. In some embodiments, the surface layer or sublayer having a metal oxide material may have an average thickness range of 0.1-0.2 nm, or 0.2-0.5 nm, or 0.5-1 nm, or 1-2 nm, or 2-5 nm, or 5-10 nm, or 10-20 nm, or 20-50 nm, or 50-100 nm, or 100-200 nm, or 200-500 nm, or 500-1000 nm, or 1000-1500 nm, or 1500-2000 nm, or 2000-2500 nm, or 2500-3000 nm, or 3000-4000 nm, or 4000-5000 nm, or any combination of these ranges.

[0058] In some embodiments, the metal oxide may be formed by atomic layer deposition (ALD), chemical vapor deposition (CVD), thermal deposition, or sputtering. In some cases, the metal oxide may be formed by coating a suspension of metal oxide particles. In some embodiments, the metal oxide may be formed by electroplating or electroless plating (which may include "dip plating").

[0059] In some embodiments, a metal oxide precursor composition is coated or printed onto a current collector having one or more subsurface layers as described above, and then processed to form a metal oxide. Some non-limiting examples of metal oxide precursor compositions include sol-gels (metal alkoxides), metal carbonates, metal acetates (including organic acetates), metal hydroxides, and metal oxide dispersions. The metal oxide precursor composition may form a metal oxide by heat treatment.

[0060] In some embodiments, the metal oxide precursor composition may include a metal, such as metal-containing particles or a metal sputtered layer. The metal may then be subjected to oxidation (e.g., thermal oxidation) in the presence of oxygen, electrolytic oxidation, or chemical oxidation in an oxidizing liquid or gaseous medium to form a metal oxide.

[0061] metal hydroxide In some embodiments, the surface layer or sub-surface layer may contain a metal hydroxide. In some embodiments, the metal hydroxide may contain a transition metal hydroxide. In some embodiments, the metal hydroxide may contain hydroxides of scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, yttrium, zinc, molybdenum, tungsten, silver, zirconium, tantalum, hafnium, tin, aluminum, indium, or niobium. In some embodiments, the metal hydroxide may contain an alkali metal hydroxide or an alkaline earth metal hydroxide. In some embodiments, the metal hydroxide may contain a lithium hydroxide. The metal hydroxide may contain a mixture of metal hydroxides. For example, "nickel hydroxide" may optionally contain other metal hydroxides in addition to nickel hydroxide. In some embodiments, the metal hydroxide includes hydroxides of alkali metals (e.g., lithium or sodium) or alkaline earth metals (e.g., magnesium or calcium) and hydroxides of transition metals (e.g., titanium, nickel, or copper). In some embodiments, the metal hydroxide sublayer may contain a certain amount of oxide such that the ratio of oxygen atoms present as oxide to oxygen atoms present as hydroxide is less than 1:1, less than 1:2, less than 1:3, or less than 1:4. The metal hydroxide may include stoichiometric hydroxides, non-stoichiometric hydroxides, or both. In some embodiments, the metal in the metal hydroxide may exist in multiple oxidation states.

[0062] In some embodiments, the thickness of the metal hydroxide sub-surface layer ("metal hydroxide sublayer") may be at least one monolayer, or at least two, three, five, or ten monolayers. In some embodiments, the average thickness of the surface layer or sublayer having the metal hydroxide material may be at least 0.1 nm, or at least 0.2 nm. In some embodiments, the average thickness of the surface layer or sublayer having the metal hydroxide material may be less than 5000 nm, or less than 3000 nm. In some embodiments, the surface layer or sublayer having a metal hydroxide material may have an average thickness in the range of 0.1-0.2 nm, or 0.2-0.5 nm, or 0.5-1 nm, or 1-2 nm, or 2-5 nm, or 5-10 nm, or 10-20 nm, or 20-50 nm, or 50-100 nm, or 100-200 nm, or 200-500 nm, or 500-1000 nm, or 1000-1500 nm, or 1500-2000 nm, or 2000-2500 nm, or 2500-3000 nm, or 3000-4000 nm, or 4000-5000 nm, or any combination of these ranges.

[0063] In some embodiments, the metal hydroxide may be formed by atomic layer deposition (ALD), chemical vapor deposition (CVD), thermal deposition, or sputtering. In some cases, the metal hydroxide may be formed by coating a suspension of metal hydroxide particles. In some embodiments, the metal hydroxide may be formed by electroplating or electroless plating (which may include "dip plating").

[0064] In some embodiments, a metal hydroxide precursor composition is coated or printed onto a current collector having one or more subsurface layers as described above, and then processed to form a metal hydroxide. Some non-limiting examples of metal hydroxide precursor compositions include sol-gels (metal alkoxides), metal carbonates, metal acetates (including organic acetates), and metal oxide dispersions. The metal hydroxide precursor composition may optionally be heat-treated in the presence of water or an alkaline aqueous medium to form a metal hydroxide.

[0065] In some embodiments, the metal hydroxide precursor composition may include a metal, such as metal-containing particles or a metal layer. The metal may then be subjected to oxidation (e.g., thermal oxidation) in the presence of oxygen, electrolytic oxidation, or chemical oxidation in an oxidizing liquid or gaseous medium to form a metal hydroxide. Such oxidation may optionally be carried out in the presence of water or under alkaline conditions.

[0066] Oxometalate As previously mentioned, oxometalates in this specification are treated separately from other non-anionic metal oxides. Oxometalates can be considered a type of metal oxide in which the metal oxide portion is substantially anion and binds with a cation (which may optionally be an alkali metal, alkaline earth metal, transition metal, or even a post-transition metal). In some embodiments, transition oxometalates may include scandium, titanium, vanadium, manganese, iron, cobalt, nickel, copper, yttrium, zirconium, niobium, molybdenum, tantalum, or tungsten. In some embodiments, transition oxometalates may include chromates, tungstates, vanadates, or molybdates. In some embodiments, a surface layer or subsurface layer may contain or be formed from a transition oxometalate other than a chromate.

[0067] In some embodiments, the oxometalate may be formed by sputtering. In some cases, the oxometalate may be formed by coating a suspension or solution of oxometalate material or particles. In some embodiments, the oxometalate may be formed by electroplating or electroless plating (which may include "dip plating"). In some embodiments, such electroplating or electroless plating may use a solution containing the transition oxometalate. In some cases, the properties of the deposited coating may include oxides, hydroxides and / or mixtures of oxometalates of transition metals.

[0068] In some embodiments, the amount of transition metal from the transition oxometalate in the surface layer or sublayer is at least 0.5 mg / 2 , or at least 1 mg / m² 2 , or at least 2 mg / m² 2 This may also be the case. In some embodiments, the amount of transition metal from the transition oxometalate is 250 mg / m³. 2 It is less than 0.5 to 1 mg / m³. In some embodiments, the amount of transition metal from the transition oxometalate is 0.5 to 1 mg / m³. 2 , or 1-2 mg / m² 2 , or 2-5 mg / m² 2 , or 5-10 mg / m² 2 , or 10-20 mg / m² 2 , or 20-50 mg / m² 2 , or 50-75 mg / m² 2 , or 75-100 mg / m² 2 , or 100-250 mg / m² 2The thickness may be in the range of , or any combination of these ranges. In some embodiments, the surface layer or sublayer having the oxometalate material may have a thickness of at least 0.2 nm, or at least 0.5 nm, or at least 1 nm, or at least 2 nm. In some embodiments, the thickness of the surface layer or sublayer having the oxometalate material may be in the range of 0.2 to 0.5 nm, or 0.5 to 1.0 nm, or 1.0 to 2.0 nm, or 2.0 to 5.0 nm, or 5.0 to 10 nm, or 10 to 20 nm, or 20 to 50 nm, or 50 to 100 nm, or any combination of these ranges.

[0069] Transition metalates typically refer to transition metal compounds that carry a negative charge. An anionic transition metal compound may be bound to one or more cations ("transition metalate compound"). Optionally, this cation may be an alkali metal, an alkaline earth metal, an ammonium, an alkylammonium, another transition metal (the same or different from the transition metal of the anionic transition metal compound), or another cation species. Transition oxometalates are a specific type of transition metalate. In addition to transition oxometalates, some non-limiting examples of useful transition metalates may include sulfometalates, cyanometalates, and halometalates, which may be used alone, in combination, or in combination with oxometalates. Unless otherwise specified, in embodiments where transition oxometalates are used, transition metalates may be used instead.

[0070] silicon compounds In some embodiments, the surface layer or sublayer comprises a silicon compound formed by treatment with a silane, siloxane, or silazane compound, all of which are referred to herein as silicon compound agents. As already stated, the silicon compound or silicon compound agent does not contain silicate compounds. In some embodiments, treatment with the silicon compound agent can improve adhesion to the upper sublayer or lithium storage layer. In some embodiments, the silicon compound may be a polymer, which includes, but is not limited to, polysiloxanes. In some embodiments, the siloxane compound may have the general structure shown in formula (1). Si(R) n (OR') 4-n (1) Here, n=1, 2, or 3, and R and R' are independently selected from substituted or unsubstituted alkyl groups, alkenyl groups, or aryl groups.

[0071] The silicon compound in the layer or sublayer may be derived from a silicon compound agent, but may have a different chemical structure from the agent used to form it. In some embodiments, the silicon compound reacts with the underlying surface to form bonds such as metal-oxygen-silicon bonds, thereby causing the silicon compound to lose one or more functional groups (e.g., OR' groups from siloxane). In some embodiments, the silicon compound agent may contain groups that polymerize to form polymers. In some embodiments, the silicon compound agent may form a matrix consisting of Si-O-Si crosslinks. In some embodiments, PECVD deposition of the lithium storage material may alter the chemical structure of the silicon compound agent or even form secondary derived compound species. The silicon compound contains silicon. The silicon compound may be the result of the silicon compound agent reacting with 1, 2, 3, or 4 reactants in 1, 2, 3, or 4 different reactions.

[0072] The silicon compound agent may be provided in solution, for example, in water or an organic solvent at a concentration of about 0.3 g / l to 15 g / l. Methods for adsorption of the silicon compound agent include, but are not limited to, immersion, shower, and spray methods. In some embodiments, the silicon compound agent may be supplied as a vapor and adsorbed to the lower layer. In some embodiments, the silicon compound agent may be deposited by initiating chemical vapor deposition (iCVD). In some embodiments, the silicon compound agent may include olefin-functionalized silane moieties, epoxy-functionalized silane moieties, acrylic-functionalized silane moieties, amino-functionalized silane moieties, or mercapto-functionalized silane moieties, which may optionally be combined with siloxane or silazane groups. In some embodiments, the silicon compound agent may be siloxysilane. In some embodiments, the silicon compound agent may be polymerized during or after deposition. Some non-limiting examples of silicon compounds include hexamethyldisilazane (HMDS), vinyltrimethoxysilane, vinylphenyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 4-glycidylbutyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N- Examples include 3-(4-(3-aminopropoxy)butoxy)propyl-3-aminopropyltrimethoxysilane, imidazolesilane, triazinesilane, 3-mercaptopropyltrimethoxysilane, 1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane, 1,3,5-trivinyl-1,3,5-trimethylcyclotrisiloxane, pentavinylpentamethylcyclopentasiloxane, and octavinyl-T8-silsesquioxane. In some embodiments, the layer or sublayer containing the silicon compound may contain silicon, oxygen, and carbon, and may further contain nitrogen or sulfur.

[0073] In some embodiments, treatment with a silicon compound agent may be followed by a step of removing the solvent, a step of initiating polymerization, or a step of initiating another chemical transformation, which may involve heating, contact with a reactant, or both. In some embodiments, the surface layer or sublayer formed using the silicon compound agent may contain 0.1-0.2 mg / m² 2 The range, or 0.1-0.25 mg / m² 2 The range, or 0.25-0.5 mg / m² 2 The range, or 0.5-1 mg / m² 2 , or 1-2 mg / m² 2 , or 2-5 mg / m² 2 , or 5-10 mg / m² 2 , or 10-20 mg / m² 2 , or 20-50 mg / m² 2 , or 50-100 mg / m² 2 , or 100-200 mg / m² 2 , or 200-300 mg / m² 2 The silicon content may be in the range of or any combination of these ranges. In some embodiments, the surface layer or sub-layer formed from the silicon compound agent may contain up to 1 monolayer, or up to 2 monolayers, or up to 4 monolayers, or up to 6 monolayers, or up to 8 monolayers, or up to 10 monolayers, or up to 15 monolayers, or up to 20 monolayers, or up to 50 monolayers, or up to 100 monolayers, or up to 200 monolayers of the silicon compound agent or its reaction products. The surface layer or sub-surface layer containing the silicon compound is porous. In some embodiments, the silicon compound may decompose or partially decompose during the deposition of the lithium storage layer.

[0074] Silicates The surface layer may contain a silicate compound. The silicate compound may contain silicon or anionic silicate species, or may be formed from a solution containing these. In this specification, anionic silicate species contains silicon and oxygen and is usually bonded to a suitable cationic group. In some cases, anionic silicate species may be represented by formula (2). ([SiO(4-x) ] (4-2x)- ) n (2) Here, 0 ≤ x < 2 and n ≥ 1. In some cases, the anionic silicate species is [SiO4]. 4- (x=0, n=1, may also be called orthosilicate in some cases), [SiO3] 2- (x=1, n=1, sometimes also called metasilicate), or [Si2O7] 6- It may also contain (x=0.5, n=2, which may also be called a pyrosilicate). The anionic silicate species may, in some cases, include larger structures such as polysilicates with n≦3.

[0075] In some embodiments, the corresponding cation moiety may include a proton, a metal ("metal silicate"), an alkylammonium moiety, or a mixture thereof. The metal silicate may include alkali metals, alkaline earth metals, transition metals, and post-transition metals. In some embodiments, the silicon compound may include a mixture of silicic acid and metal silicate.

[0076] In some embodiments, the surface layer may be formed by contacting the current collector precursor with a silicate treatment agent. The current collector precursor typically includes a conductive layer and may optionally include one or more additional subsurface layers, as described in other parts of this specification. The silicate treatment agent may include, for example, an aqueous mixture (solution, dispersion, emulsion, etc.) containing a silicate compound. In some cases, the silicate compound may have a solubility of at least 10 ppm, at least 50 ppm, or at least 100 ppm. In some cases, the treatment agent may include silicic acid, sodium silicate, potassium silicate, or a mixture thereof. In some embodiments, the aqueous mixture may have a pH of at least 2, or at least 4. In some embodiments, the aqueous mixture may have a pH in the range of about 4-5, or 5-6, or 6-7, or 7-8, or 8-9, or 9-10, or 10-11, or 11-12, or any combination of these ranges.

[0077] In some cases, the silicate treatment agent may be provided as a bath for immersing the current collector precursor, or the current collector precursor may be coated by spray coating or other methods. Contact with the silicate treatment agent may optionally include stirring steps such as bath circulation, sparing, agitation, and movement of the current collector precursor. The silicate treatment agent may be at room temperature or controlled to a temperature range, for example, about 0°C to 5°C, or 5°C to 10°C, or 10°C to 15°C, or 15°C to 20°C, or 20°C to 25°C, or 25°C to 30°C, or 30°C to 40°C, 40°C to 50°C, or 50°C to 60°C, or 60°C to 80°C, or any combination of these ranges. In some cases, a rinsing step with a rinsing agent may be performed after contact with the silicate treatment agent. In some embodiments, the rinsing agent may include water, such as distilled water or tap water. The rinsing agent may optionally include surfactants, dispersants, neutralizing agents, or other materials.

[0078] In some embodiments, the surface density of silicon derived from silicate compounds in the surface layer is at least 0.2 mg / m². 2 , or at least 0.5 mg / m² 2 This may also be the case. In some embodiments, the surface density of silicon derived from the silicate compound in the surface layer is 0.2 to 0.5 mg / m². 2 , or 0.5-1.0 mg / m² 2 , or 1.5-2 mg / m² 2 , or 2-3 mg / m² 2 , or 3-5 mg / m² 2 , or 5-7 mg / m² 2 , or 7-10 mg / m² 2 , or 10-15 mg / m² 2 , or 15-20 mg / m² 2 , or 20-30 mg / m² 2 , or 30-50 mg / m² 2 This may be within the range of , or any combination of these ranges.

[0079] Metal silicides The surface layer may contain a metal silicide. In some embodiments, the metal silicide is M x Si y The chemical composition may be characterized by the following, where M is a transition metal, x is the total atomic percent of one or more transition metals, and y is the atomic percent of silicon, and the ratio of x to y may be in the range of about 0.25 to about 7. The ratio of x to y may vary within the metal silicide layer. In some embodiments, the surface layer may contain metal silicides with a gradient in metal content, for example, the atomic percent of the transition metal(s) may decrease toward the lithium storage layer. If the ratio of x to y is less than 0.25, in some embodiments, the silicon may be considered part of the lithium storage layer as specified herein. If the ratio of x to y is greater than 7, the transition metal may be considered part of the conductive layer as specified herein. In some embodiments, M may be Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zr, Mo, or W, or a combination of two or three of these elements. The metal silicide may be stoichiometric or non-stoichiometric. The metal silicide layer may contain a mixture of metal silicides, a mixture of metals, or both, having a uniformly or non-uniformly distributed stoichiometric composition.

[0080] In some embodiments, the surface density of silicon derived from metal silicides in the surface layer is at least 0.2 mg / m². 2 , or at least 0.5 mg / m² 2 This may also be the case. In some embodiments, the surface density of silicon derived from metal silide in the surface layer is 0.2 to 0.5 mg / m². 2 , or 0.5-1.0 mg / m² 2 , or 1.5-2 mg / m² 2 , or 2-3 mg / m² 2 , or 3-5 mg / m² 2 , or 5-7 mg / m² 2 , or 7-10 mg / m² 2 , or 10-15 mg / m² 2 , or 15-20 mg / m² 2 , or 20-30 mg / m² 2 , or 30-50 mg / m² 2, or 50-100 mg / m² 2 , or 100-200 mg / m² 2 , or 200-300 mg / m² 2 , or 300-400 mg / m² 2 , or 400-500 mg / m² 2 This may be within the range of , or any combination of these ranges.

[0081] In some embodiments, the metal silicide is at least 10 2 S / m, at least 10 3 S / m, at least 10 4 S / m, at least 10 5 S / m, or at least 10 6 It may have conductivity of S / m.

[0082] In some embodiments, the metal silicide may be formed before the deposition of the silicon-containing anode active material layer. For example, the metal silicide layer may be formed directly by atomic layer deposition (ALD), PECVD, or PVD processes (e.g., sputtering). Sputtering may use a single metal silicide sputtering source or two sources, one for metal and one for silicon. In some embodiments, a slurry of metal silicide particles may be coated onto the conductive layer and optionally dried or sintered. In some embodiments, the metal silicide layer may be formed by heating a metal layer in contact with the silicon layer (e.g., the metal portion of the conductive layer).

[0083] Lithium storage layer (anode active material layer) The lithium storage layer may include a silicon-containing anode active material into which lithium can be reversibly incorporated, for example, a interconnected porous lithium storage layer. In addition to silicon, the anode active material may further include germanium, antimony, tin, or a mixture thereof. In some embodiments, the silicon-containing anode active material layer is substantially amorphous. In some embodiments, the lithium storage layer includes substantially amorphous silicon. Such substantially amorphous storage layer may contain small amounts (e.g., less than 20 atomic percent) of crystalline material dispersed therein. The storage layer may contain dopants selected from hydrogen, boron, phosphorus, carbon, sulfur, fluorine, aluminum, gallium, indium, arsenic, antimony, bismuth, nitrogen, and metallic elements. In some embodiments, the lithium storage layer may include porous substantially amorphous silicon hydride (a-Si:H), for example, having a hydrogen content of 0.1 to 20 atomic percent or more. In some embodiments, the lithium storage layer may include methylated amorphous silicon. However, unless otherwise specified regarding hydrogen content, the atomic percent unit used in this specification for lithium storage materials or layers is based on atoms other than hydrogen.

[0084] In some embodiments, the silicon-containing anode active material layer (e.g., a interconnected porous lithium storage layer) may contain at least 40 atomic percent, or at least 50 atomic percent, or at least 60 atomic percent, or at least 70 atomic percent, or at least 80 atomic percent, or at least 90 atomic percent, or at least 95 atomic percent, or at least 97 atomic percent, or at least 98 atomic percent, or at least 99 atomic percent of silicon. In some cases, the silicon-containing anode active material layer may contain silicon in the range of 40-50 atomic percent, 50-60 atomic percent, 60-70 atomic percent, 70-80 atomic percent, 80-90 atomic percent, 90-95 atomic percent, 95-97 atomic percent, 97-98 atomic percent, or 98-99 atomic percent, or any combination of these ranges. However, in the case of pre-lithiumized anodes as described below, the lithium content is excluded from this atomic percent characterization.

[0085] In some embodiments, the silicon-containing anode active material layer (e.g., a interconnected porous lithium storage layer) may contain less than 10 atomic percent, or less than 5 atomic percent, or less than 2 atomic percent, or less than 1 atomic percent, or less than 0.5 atomic percent, or less than 0.3 atomic percent of carbon. In some embodiments, the total weight of the silicon-containing anode active material layer may be less than 15 wt%, or less than 10 wt%, or less than 5 wt%, or less than 2 wt% of carbon-based binders, graphite carbon, graphene, graphene oxide, reduced graphene oxide, carbon black, and conductive carbon. In some embodiments, the silicon-containing anode active material layer is substantially free of carbon-based binders, graphite carbon, graphene, graphene oxide, reduced graphene oxide, carbon black, and conductive carbon. That is, the total weight of the carbon material in the lithium storage layer is less than 1 wt%, or less than 0.5 wt%, or less than 0.3 wt%, or less than 0.1 wt%, or less than 0.01 wt%. Some non-limiting examples of carbon-based binders include organic polymers based on styrene-butadiene rubber, polyvinylidene fluoride, polytetrafluoroethylene, polyacrylic acid, carboxymethylcellulose, or polyacrylonitrile.

[0086] The silicon-containing anode active material layer (e.g., a interconnected porous lithium storage layer) may contain cavities and voids (pores), which may be random or non-uniform in size, shape, and distribution. In the interconnected porous lithium storage layer, such porosity does not cause, nor is caused by, the formation of any recognizable lithium storage nanostructures, such as nanowires, nanopillars, nanotubes, or aligned nanochannels. In some embodiments, the pores are polydispersible. In some embodiments, the porous lithium storage layer is characterized as nanoporous. In some embodiments, the silicon-containing anode active material layer has a density of 1.0–1.1 g / cm³. 3 , or 1.1~1.2 g / cm³ 3 , or 1.2-1.3 g / cm³ 3 , or 1.3~1.4 g / cm³ 3 , or 1.4~1.5 g / cm³3 or 1.5 - 1.6 g / cm 3 or 1.6 - 1.7 g / cm 3 or 1.7 - 1.8 g / cm 3 or 1.8 - 1.9 g / cm 3 or 1.9 - 2.0 g / cm 3 or 2.0 - 2.1 g / cm 3 or 2.1 - 2.2 g / cm 3 or 2.2 - 2.25 g / cm 3 or 2.25 - 2.29 g / cm 3 in the range of, or may have an average density of any combination of these ranges, and contain at least 70 atomic%, 80 atomic%, or at least 85 atomic%, or at least 90 atomic%, or at least 95 atomic%, or at least 97 atomic%, or at least 98 atomic%, or at least 99 atomic% of silicon. The foregoing may apply particularly to silicon deposited by PVD or CVD processes, but may also apply to some slurry-coated silicon-based materials. A density less than 2.3 g / cm 3 is evidence of the porosity of a-Si containing a lithium storage layer. In some embodiments, the lower density / higher porosity can suppress cell expansion during charging (e.g., because the expansion of the silicon layer during lithiation is suppressed). Also, note that the aforementioned density range applies to the "deposited" layer. Within the cell, especially after electrochemical formation and / or prelithiation, these densities may change but may still remain within one of the listed ranges.

[0087] In some embodiments, the silicon-containing anode active material (e.g., silicon, germanium, or an alloy thereof) of a lithium storage layer (e.g., a interconnected porous lithium storage layer) has substantial lateral connectivity over a wide area of ​​the current collector, and this connectivity extends to surround irregular pores and gaps. Referring again to Figure 6A, in some embodiments, “substantial lateral connectivity” means that the active material at one point X in the interconnected porous lithium storage layer 607 can be connected to the active material at a second point X' in the same layer by a linear lateral distance LD of at least the average thickness T of the lithium storage layer (or at least twice the thickness, or at least three times the thickness). Although not shown, by bypassing pores and conforming to the surface shape of the current collector, the total path length of material connectivity may be longer than LD. In some embodiments, the interconnected porous lithium storage layer can be described as an interconnected silicon matrix filled with random pores and gaps. In some embodiments, the silicon-containing anode active material layer (e.g., a interconnected porous lithium storage layer) may have a spongy morphology in cross-sectional view. It should be noted that the lithium storage layer (e.g., an interconnected porous lithium storage layer) does not necessarily need to extend across the entire anode without lateral fractures, and may be considered continuous even if numerous random discontinuities or cracks are present. In some embodiments, such discontinuities may occur more frequently on rough current collector surfaces. In some embodiments, the silicon-containing anode active material layer (e.g., an interconnected porous lithium storage layer) may exhibit adjacent columnar structures of anode active material in cross-sectional view. These adjacent columnar structures are characterized by their average height and average width, with a height-to-width aspect ratio typically less than 4:1, or less than 3:1, or less than 2:1, or less than 1:1. Such adjacent columnar structures are generally continuous laterally. In some embodiments, the silicon-containing anode active material layer (e.g., an interconnected porous lithium storage layer) may contain a matrix of interconnected nanoparticle aggregates. In some embodiments, the silicon-containing anode active material layer may include a mixture of amorphous and crystalline silicon.For example, nanocrystalline silicon with an average particle size of less than 100 nm, or less than approximately 50 nm, less than approximately 20 nm, less than approximately 10 nm, or less than approximately 5 nm. In some cases, the silicon-containing anode active material layer may contain up to 30 atomic percent of nanocrystalline silicon relative to all silicon in the lithium storage layer.

[0088] In some embodiments, the silicon-containing anode active material layer (e.g., a interconnected porous lithium storage layer) is a quasi-stoichiometric oxide of silicon (SiO₂). x ) and optionally germanium (GeO x ) or tin (SnO x ) includes, where the ratio of oxygen atoms to silicon, germanium, or tin atoms is less than 2:1, i.e., x < 2, or less than 1:1, i.e., x < 1. In some embodiments, x is in the range of 0.02 to 0.95, or 0.02 to 0.10, or 0.10 to 0.50, or 0.50 to 0.95, or 0.95 to 1.25, or 1.25 to 1.50, or any combination of these ranges. A lithium storage layer having a quasi-stoichiometric oxide of silicon may also be called oxygen-doped silicon.

[0089] In some embodiments, the silicon-containing anode active material layer (e.g., a interconnected porous lithium storage layer) is a quasi-stoichiometric nitride of silicon (SiN y ) contains germanium (GeN y ) or tin (SnN y ) is included, where the ratio of nitrogen atoms to silicon, germanium, or tin atoms is less than 1.25:1, i.e., y < 1.25. In some embodiments, the range of y is 0.02 to 0.95, or 0.02 to 0.10, or 0.10 to 0.50, or 0.50 to 0.95, or 0.95 to 1.20, or any combination thereof. A lithium storage layer having a quasi-stoichiometric nitride of silicon may also be called nitrogen-doped silicon or silicon-nitrogen alloy.

[0090] In some embodiments, the silicon-containing anode active material layer (e.g., a interconnected porous lithium storage layer) is a quasi-stoichiometric oxynitride of silicon (SiO₂ x N y ), and optionally germanium (GeO x N y ) or tin (SnO x N y The material comprises an oxynitride such that the ratio of the sum of oxygen and nitrogen atoms to silicon, germanium, or tin atoms is less than 1:1, i.e., (x+y)<1. In some embodiments, the range of (x+y) is 0.02 to 0.95, or 0.02 to 0.10, or 0.10 to 0.50, or 0.50 to 0.95, or any combination of these ranges.

[0091] In some embodiments, the quasi-stoichiometric oxides, nitrides, or oxynitrides are supplied by a CVD process (including, but not limited to, a PECVD process). Oxygen and nitrogen may be supplied uniformly within the interconnected porous lithium storage layer, or the oxygen and nitrogen content may vary as a function of the thickness of the storage layer. By including several quasi-stoichiometric oxides, nitrides, or oxynitrides of silicon, an anode active material layer with less expansion during lithiation than substantially pure silicon may be provided.

[0092] CVD CVD typically involves flowing a precursor gas, a gasifying liquid in direct liquid injection CVD, or a gas and liquid into a chamber containing one or more objects to be coated, which are usually heated. The chemical reaction occurs on and near the hot surface, resulting in the deposition of a film on the surface. This is accompanied by the production of chemical byproducts, which are discharged from the chamber along with the unreacted precursor gas. As expected, depending on the diversity of materials to be deposited and the wide range of applications, there are many variations of CVD that can be used to form lithium storage layers, surface layers or sublayers, auxiliary layers (see below), or other layers. This can be carried out in hot-wall or cold-wall reactors, from sub-tall total pressure to above atmospheric pressure, with or without a carrier gas, and in some embodiments typically in the temperature range of 100 to 1600°C. There are also various enhanced CVD processes that utilize plasma, ions, photons, lasers, thermal filaments, or combustion reactions to increase the deposition rate and / or lower the deposition temperature. To control deposition, various process conditions are used, including but not limited to temperature, precursor material, gas flow rate, pressure, substrate voltage bias (if applicable), and plasma energy (if applicable).

[0093] As already mentioned, silicon-containing anode active material layers, such as interconnected porous lithium storage layers, can be provided by plasma-enhanced chemical deposition (PECVD). Compared to some other CVD processes, deposition by PECVD can often be carried out at lower temperatures and higher rates, which is advantageous for high manufacturing efficiency. In some embodiments, PECVD is used to deposit a substantially amorphous silicon layer (optionally doped) on a surface layer. In some embodiments, PECVD is used to deposit a substantially amorphous interconnected porous silicon layer on a surface layer.

[0094] In various embodiments, the plasma in the PECVD process may be generated within the chamber where the substrate is placed, or upstream of the chamber and supplied into the chamber. Various types of plasma are available, including, but not limited to, capacitively coupled plasma, inductively coupled plasma, and conductively coupled plasma. Any suitable plasma source is available, including DC, AC, RF, VHF, hollow cathode, combined PECVD, and microwave sources. In some embodiments, magnetron-assisted RF PECVD may be employed.

[0095] PECVD process conditions (temperature, pressure, precursor gas, carrier gas, dopant gas, flow rate, energy, etc.) can vary depending on the specific process and equipment employed, as is known in the art.

[0096] In some embodiments, the PECVD process is an expanding thermal plasma chemical deposition (ETP-PECVD) process. In such a process, a plasma generating gas is passed through a DC arc plasma generator to form a plasma, and other substrates, including a web or current collector, may be placed in an adjacent vacuum chamber. A silicon source gas is injected into the plasma to generate radicals. The plasma is expanded by a diffusion nozzle and injected into the vacuum chamber toward the substrate. An example of a plasma generating gas is argon (Ar). In some embodiments, ionized argon species in the plasma collide with silicon source molecules to form silicon source radical species. As a result, deposition occurs on the current collector.

[0097] Any suitable silicon source may be used for silicon deposition. In some embodiments, the silicon source may be a silane-based precursor gas, including but not limited to silane (SiH4), dichlorosilane (H2SiCl2), monochlorosilane (H3SiCl), trichlorosilane (HSiCl3), silicon tetrachloride (SiCl4), disilane, tetrafluorosilane, triethylsilane, and diethylsilane. Depending on the gas(s) used, the silicon layer may be formed by decomposition or reaction with other compounds, such as hydrogen reduction. In some embodiments, the gas(s) may include a silicon source such as silane, a noble gas such as helium, argon, neon, or xenon, and optionally one or more dopant gases, and substantially free of hydrogen. In some embodiments, the gas(s) may include argon, silane, and hydrogen, and optionally several dopant gases. In some embodiments, the ratio of argon to the total gas flow rate of silane and hydrogen is at least 3.0, or at least 4.0. In some embodiments, the ratio of argon to the total gas flow rate of silane and hydrogen may be in the range of 3 to 5, or 5 to 10, or 10 to 15, or 15 to 20, or any combination of these ranges. In some embodiments, the gas flow rate ratio of hydrogen gas to silane may be in the range of 0 to 0.1, or 0.1 to 0.2, or 0.2 to 0.5, or 0.5 to 1, or 1 to 2, or 2 to 5, or any combination of these ranges. In some embodiments, as the ratio of silane to the total gas flow rate of silane and hydrogen increases, silicon with higher porosity may be formed and / or the silicon deposition rate may increase. In some cases, higher porosity may allow for reduced expansion of the silicon layer during charging. In some embodiments, the dopant gas is borane or phosphine, which may be mixed with the carrier gas of any choice.In some embodiments, the ratio of gas flow rates between the dopant gas (e.g., borane or phosphine) and the silicon source gas (e.g., silane) may be in the range of 0.0001 to 0.0002, or 0.0002 to 0.0005, or 0.0005 to 0.001, or 0.001 to 0.002, or 0.002 to 0.005, or 0.005 to 0.01, or 0.01 to 0.02, or 0.02 to 0.05, or 0.05 to 0.10, or any combination of these ranges. Such gas flow rate ratios above may refer to relative gas flow rates, e.g., standard cubic centimeters / minute (SCCM). In some embodiments, the PECVD deposition conditions and gases may be modified during the deposition process.

[0098] In some embodiments, the current collector temperature for at least a portion of the time during PECVD deposition is in the range of 20°C to 50°C, 50°C to 100°C, or 100°C to 200°C, or 200°C to 300°C, or 300°C to 400°C, or 400°C to 500°C, or 500°C to 600°C, or a combination of these ranges. In some embodiments, the temperature may change during PECVD deposition. For example, the initial temperature of PECVD may be higher than the later temperature, or the later temperature of PECVD may be higher than the initial temperature.

[0099] The thickness or mass per unit area of ​​the silicon-containing anode active material layer (e.g., a interconnected porous lithium storage layer) depends on the storage material, the desired charge capacity, and other operational and lifetime considerations. Generally, increasing the thickness increases the capacity. If the lithium storage layer is too thick, electrical resistance may increase and stability may decrease. In some embodiments, the anode has a surface density of active silicon of at least 0.2 mg / cm³. 2 , or at least 0.5 mg / cm³ 2 , or at least 1.0 mg / cm³ 2 , or at least 1.5 mg / cm³ 2 , or at least 3 mg / cm³ 2 , or at least 5 mg / cm³ 2It may also be characterized as follows. In some embodiments, the lithium storage structure has an active silicon surface density of 0.2 to 0.5 mg / cm³. 2 , or 0.5-1.0 mg / cm³ 2 , or 1.0-1.5 mg / cm³ 2 , or 1.5-2 mg / cm³ 2 , or 2-3 mg / cm³ 2 , or 3-5 mg / cm³ 2 , or 5-10 mg / cm³ 2 , or 10-15 mg / cm³ 2 , or 15-20 mg / cm³ 2 It may be characterized as being within the range of, or any combination of these ranges. "Activated silicon" refers to silicon that is electrically connected to the current collector and available for reversible lithium storage at the start of the cell cycle (after the "electrochemical formation" of the anode, as described later). "Surface density" refers to the surface area of ​​the conductive layer provided with activated silicon. In some embodiments, not all of the silicon content is activated silicon; i.e., some silicon may be fixed in the form of inactive silicide or electrically insulated from the current collector.

[0100] In some embodiments, the average thickness of the silicon-containing anode active material layer (e.g., a interconnected porous lithium storage layer) is at least 0.5 μm, or at least 1 μm, or at least 2.5 μm, or at least 5 μm, or at least 6.5 μm. In some embodiments, the average thickness of the lithium storage layer (e.g., an interconnected porous lithium storage layer) is in the range of about 0.5 μm to about 50 μm. In some embodiments, the silicon-containing anode active material layer (e.g., an interconnected porous lithium storage layer) deposited by a PVD or CVD process contains at least 80 atomic percent amorphous silicon and has a thickness of 1 to 1.5 μm, or 1.5 to 2.0 μm, or 2.0 to 2.5 μm, or 2.5 to 3.0 μm, or 3.0 to 3.5 μm, or 3.5 to 4.0 μm, or 4.0 to 4.5 μm, or 4.5 The range is 5.0 μm, or 5.0-5.5 μm, or 5.5-6.0 μm, or 6.0-6.5 μm, or 6.5-7.0 μm, or 7.0-8.0 μm, or 8.0-9.0 μm, or 9.0-10 μm, or 10-15 μm, or 15-20 μm, or 20-25 μm, or 25-30 μm, or 30-40 μm, or 40-50 μm, or any combination of these ranges.

[0101] In some embodiments, the silicon-containing anode active material may be formed by a physical vapor deposition (PVD) process such as sputtering, rather than by CVD (e.g., PECVD). Although the deposition rate of sputtering is typically slower than that of PECVD, sputtering may be suitable for applications where a relatively small load of active material such as silicon is required. For example, in some embodiments, the lithium storage layer formed by the sputtering process (e.g., a interconnected porous lithium storage layer) may have a thickness of less than about 15 μm, or less than about 10 μm, or less than 7 μm, or less than 5 μm, or less than 3 μm.

[0102] In some embodiments, the silicon-containing anode active material layer may include nanowires deposited by a CVD process (for example, as described in US8257866, US9923201, US20100285358, US20100330421, US20110159365, US20130143124, US20140248543, US20150118572, US20150325852, and US20170338464, all of which are incorporated herein by reference for any purpose).

[0103] In some embodiments, the silicon-containing anode active material layer may include a slurry-coated active material (containing silicon or quasi-stoichiometric silicon oxide, and typically including a carbon-based binder, conductive carbon, etc.). The slurry-coated silicon-containing active material layer may be used on both sides of the anode, but in some cases it is advantageous that at least one lithium storage layer is deposited by a CVD or PVD process. Some non-limiting examples of slurry-coated silicon-containing active material layers are described in US11183689, US11450850, US20230056009, US7316792, and US8597831, all of which are incorporated herein by reference for any purpose.

[0104] Other anode mechanisms The anode may optionally include various additional layers and mechanisms. In some embodiments, an auxiliary layer is placed on top of the lithium storage layer. In some embodiments, the auxiliary layer is a protective layer to improve lifespan or physical durability. The auxiliary layer may be an oxide formed from the lithium storage material itself (e.g., silicon dioxide in the case of silicon) or some other suitable material. The auxiliary layer may be deposited by, for example, ALD, S-ALD, CVD, i-CVD, PECVD, MLD, vapor deposition, sputtering, solution coating, inkjet, or any method compatible with the anode. In some embodiments, the top surface of the auxiliary layer may correspond to the top surface of the anode.

[0105] The auxiliary layer has moderate conductivity to lithium ions and allows lithium ions to move in and out of the patterned lithium storage structure during charging and discharging. In some embodiments, the lithium ion conductivity of the auxiliary layer is at least 10 -9 S / cm, or at least 10 -8 S / cm, or at least 10 -7 S / cm, or at least 10 -6 The density is S / cm. In some embodiments, the auxiliary layer functions as a solid electrolyte.

[0106] Some non-limiting examples of materials used in auxiliary layers include metal oxides, nitrides, or oxynitrides, such as aluminum, titanium, vanadium, zirconium, hafnium, or tin, or mixtures thereof. Metal oxides, metal nitrides, or metal oxynitrides may contain other components such as phosphorus or silicon. Auxiliary layers include lithium phosphate oxynitride (LIPON), lithium phosphate, lithium aluminum oxide, (Li, La) x Ti y O z , or Li x Si yIt may include lithium-containing materials such as Al2O3. In some embodiments, the auxiliary layer comprises a metal oxide, metal oxide, or metal oxynitride and has an average thickness of less than about 100 nm, for example, in the range of about 0.1 to about 10 nm, or in the range of about 0.2 nm to about 5 nm. LIPON or other solid electrolyte materials having excellent lithium transport properties may have a thickness greater than 100 nm, or in the range of about 1 nm to about 50 nm. In some embodiments, LIPON or other solid electrolyte materials have a thickness of 0.1 to 0.5 μm, or 0.5 to 1.0 μm, or 1 to 1.5 μm, or 1.5 to 2.0 μm, or 2.0 to 2.5 μm, or 2.5 to 3.0 μm, or 3.0 to 3.5 μm, or 3.5 to 4.0 μm, or 4.0 to 4.5 μm, or 4.5 to 5.0 μm, or 5.0 to 5.5 μm. , or the ranges of 5.5-6.0 μm, or 6.0-6.5 μm, or 6.5-7.0 μm, or 7.0-8.0 μm, or 8.0-9.0 μm, or 9.0-10 μm, or 10-15 μm, or 15-20 μm, or 20-25 μm, or 25-30 μm, or 30-40 μm, or 40-50 μm, or any combination of these ranges.

[0107] Pre-lithium In some embodiments, the silicon-containing anode active material layer (e.g., a interconnected porous lithium storage layer) may be at least partially pre-lithified before the first electrochemical cycle after battery assembly, or even before battery assembly. That is, some lithium may be incorporated into the silicon-containing anode active material layer to form a lithified storage layer even before the first battery cycle. In some embodiments, the lithified storage layer may break into smaller structures, including but not limited to platelets or segments, that maintain an electrochemically active state and continue to reversibly store lithium. It should be noted that “lithified storage layer” simply means that at least a portion of the potential energy storage capacity of the lithium storage layer is filled, but not necessarily all of it. In some embodiments, the lithium content in the lithified storage layer may be in the range of 1% to 5%, or 5% to 10%, or 10% to 15%, or 15% to 20%, or 20% to 30%, or 30% to 40%, or 40% to 50%, or 50% to 60%, or 60% to 70%, or 70% to 80%, or 80% to 90%, or 90% to 100%, or any combination of these ranges relative to the theoretical lithium storage capacity of the lithium storage layer. In some embodiments, since the surface layer may capture some lithium, this capture effect may also need to be taken into account in order to achieve the desired lithium range in the lithified storage layer.

[0108] In some embodiments, pre-lithiation may involve physical contact between a silicon-containing anode active material and a lithiation material. The lithiation material may include a reducing lithium compound, a lithium metal, or a stabilized lithium metal powder. Such a material may be in direct contact with the anode active material or may be provided as a coating on a lithium transition substrate. The lithium transition substrate may include a metal (e.g., as foil), a polymer, a ceramic, or any combination thereof, and may optionally be in a multilayer form. In some embodiments, such a lithiation material may be provided on at least one side of a separator facing the anode, i.e., the separator also functions as a lithium transition substrate. In some embodiments, the lithiation material may facilitate the lithium transition to a continuous lithium storage layer (optionally via one or more auxiliary layers) by the application of pressure and / or heat. In some embodiments, the pressure applied between the anode and the lithiation material may be at least 200 kPa, or at least 1000 kPa, or at least 5000 kPa. Pressure may be added, for example, by calendering, by a pressure plate, or, in the case of a lithium material coating on a separator, by incorporating it into a battery with a limit or other pressure mechanism.

[0109] In some embodiments, pre-lithiation may involve depositing lithium metal onto a silicon-containing anode active material layer. For example, this may be deposited by a CVD or PVD process, or between or on one or more lithium storage sublayers, by, for example, evaporation, electron beam, or sputtering. This may optionally be performed in-line when manufacturing the silicon-containing anode active material layer by CVD or PVD.

[0110] In some embodiments, the anode may be heat-treated before the battery assembly. In some embodiments, heat treatment of the anode may improve the adhesion or conductivity of each layer by, for example, diffusing metal from the current collector or atoms from any auxiliary layer into the lithium storage layer.

[0111] In some embodiments, the silicon-containing anode active material layer (e.g., a interconnected porous lithium storage layer) contains at least 0.05 atomic percent of one or more transition metals, or at least 0.1 atomic percent, or at least 0.2 atomic percent, or at least 0.5 atomic percent, or at least 1 atomic percent of a transition metal. In some embodiments, the silicon-containing anode active material layer contains less than about 10 atomic percent of one or more transition metals, or less than 5 atomic percent, or less than 2 atomic percent, or less than 1 atomic percent, or less than 0.5 atomic percent, or less than 0.3 atomic percent of a transition metal. In some embodiments, the silicon-containing anode active material layer may contain one or more transition metals in atomic percent ranges of 0.05 to 0.1%, or 0.1 to 0.2%, or 0.2 to 0.5%, or 0.5 to 1%, or 1 to 2%, or 2 to 3%, or 3 to 5%, or 5 to 7%, or 7 to 10%, or any combination of these ranges. In some embodiments, the atomic percentage range of the aforementioned transition metal(s) is at least 1 μm. 2 This may correspond to the cross-sectional area of ​​the lithium storage layer, and its measurement may be performed, for example, by energy-dispersive X-ray spectroscopy (EDS). In some embodiments, the above transition metal atomic % value may represent the atomic % of a single transition metal, or, if a mixture of transition metals is present, it may correspond to the total atomic % of those mixtures. Some non-limiting examples of transition metals that may be present in the lithium storage layer include copper, nickel, titanium, vanadium, and molybdenum. In some embodiments, there is a gradient in the concentration of the transition metal in the portion of the lithium storage layer closer to the current collector than in the portion further away from the current collector. In some embodiments, the silicon-containing anode active material layer may contain the same transition metals as those present in the transition metalates of the conductive layer or surface layer. In some cases, one or more transition metals may be introduced into the silicon-containing anode active material layer by heat treatment to move the metals into the lithium storage layer, or other methods may be used, such as co-depositing the lithium storage material and the metals.

[0112] In some embodiments, the heat treatment of the anode may be carried out in a controlled environment with low oxygen and moisture content (e.g., less than 10 ppm, or partial pressure less than 0.1 Torr, or content less than 0.01 Torr) to prevent degradation. In some embodiments, the anode heat treatment may be carried out using an oven, an infrared heating element, contact with a hot plate, or exposure to a flash lamp. The heat treatment temperature and time of the anode depend on the anode material. In some embodiments, the anode heat treatment includes heating the anode to a temperature in the range of at least 50°C, or 50°C to 950°C, or 100°C to 250°C, or 250°C to 350°C, or 350°C to 450°C, or 450°C to 550°C, or 550°C to 650°C, or 650°C to 750°C, or 750°C to 850°C, or 850°C to 950°C, or a combination of these ranges. In some embodiments, the heat treatment may be applied for a time range of 0.1 minutes to 120 minutes.

[0113] In some embodiments, one or more of the above processing steps may be carried out in a roll-to-roll manner. In this case, the conductive layer or current collector may take the form of a roll of film, a roll of metal foil, a conductive mesh, or a conductive carbon fabric.

[0114] Cathode The positive electrode (cathode) material is a lithium metal oxide compound (e.g., LiCoO2 (also known as "LCO"), LiFePO4 (also known as "LFP"), LiMn x Fe y PO4 (also known as "LMFP"), LiNi x Mn x O4 (also known as "LNMO"), LiMnO2, LiNiO2, LiMn2O4 (also known as "LMO"), LiCoPO4, LiNi x Co y Mn z O2 (also known as "NMC"), LiNi x Co y Al zThe cathode active material includes, but is not limited to, O2 (also known as "NCA"), LiFe2(SO4)3, or Li2FeSiO4), carbon fluoride, and metal fluorides (e.g., iron fluoride (FeF3), metal oxides, sulfur, selenium, and combinations thereof). The cathode active material may operate by intercalation, conversion, or a combination thereof. The cathode active material may optionally be mixed with one or more binders and coated onto a cathode current collector to form a cathode. In some embodiments, the cathode current collector may include a metal foil, mesh, or a sheet of conductive material such as aluminum. In some embodiments, the cathode current collector may include a metal coating such as aluminum provided on an electrically insulating polymer. In some embodiments, the cathode current collector may be a film, paper, fiber, or sheet containing conductive carbon such as carbon black, carbon nanotubes, graphene, graphene oxide, reduced graphene oxide, and graphite. In some embodiments, the conductive layer may be in the form of a foil, a conductive mesh, or a sheet of conductive material.

[0115] Separator A separator allows ions to flow between the anode and cathode but prevents direct electrical contact. Such separators are typically porous sheets or other self-supporting films that occupy at least a portion of the space between the anode and cathode along with the electrolyte. Depending on the cell design, the separator may be in contact with the cathode, anode, both anode and cathode, or not in physical contact with either the anode or cathode. Non-aqueous lithium-ion separators may comprise single-layer or multi-layer polymer sheets, usually made from polyolefins such as polyethylene or polypropylene, but polyethylene terephthalate (PET) and polyvinylidene fluoride (PVdF) are also available, as well as many other synthetic or natural polymers. Cellulosic materials are another polymer material that may be useful. For example, separators may have a porosity of over 30%, low ion resistivity, and a thickness of about 10–70 μm. In some cases, separators have high overall puncture strength. Alternatively, the separator may include, for example, a glass material, a ceramic material, a ceramic embedded in a polymer, a ceramic-coated polymer, or other composite materials or multilayer structures to provide higher mechanical and thermal stability. In some embodiments, the separator may include a polymer that can be provided as a film. The polymer has high elasticity and / or exhibits gel-like properties in the presence of a liquid electrolyte.

[0116] Compressible element Several embodiments disclosed herein relate to various elements that are compressible under pressure. Pressure is generated directly or indirectly, for example, by silicon expansion during an electrochemical cycle (e.g., an electrochemical charging event (e.g., lithiumization of silicon)). Figure 8A is a cross-sectional view of a compressible element 890 according to several embodiments. As described elsewhere in this specification, the compressible element 890 may be, for example, a compressible separator, a compressible current collector, a compressible liner, a compressible central element, a compressible cathode active material layer, or a compressible solid electrolyte layer. For example, the compressible element 890 may be formed from a compressible material and / or have a compressible / foldable structure.

[0117] In Figure 8A, the compressible element 890 may have a thickness A. This thickness may represent the thickness before an electrochemical cycle such as an electrochemical charge event, or when the cell is in a discharged state and the anode has stored less than 30%, 20%, or 10% of its operational lithium storage capacity. The compressible element 890 may be said to be in its initial state.

[0118] In Figure 8B, a pressure 895 is applied, and the compressible element 890b has a compressed thickness C that is B less than its initial thickness A. In Figure 8B, the compressible element 890b is in a compressed state. For example, the pressure may be caused by an electrochemical cycle, such as an electrochemical charging event. In some embodiments, the compressible element is an element that can be compressed to less than 95% of its thickness before the electrochemical charging event during at least one electrochemical charging event. That is, the compressibility ratio C / A (which may also be expressed as “compressibility percentage”) is less than 0.95 (95%), or the ratio B / A is greater than 0.05. In some cases, the compressible element can be compressed to less than 90%, 85%, 80%, 75%, or 70% of its thickness before the electrochemical charging event. In some cases, the ratio C / A may be in the range of 0.1-0.3, 0.3-0.5, 0.5-0.6, 0.6-0.7, 0.7-0.75, 0.75-0.80, 0.80-0.85, 0.85-0.90, 0.90-0.94, or any combination of these ranges.

[0119] Figure 8C shows a compressible element after an electrochemical discharge event according to several embodiments, where the compressible element 895c has a thickness C' after at least a portion of the pressure 895 has been reduced. In some embodiments (as shown here), C' is still smaller than A (the difference is B'), but larger than C. That is, when the pressure 895 is released, the thickness of the compressible element is partially recovered. In some cases, C'=A, and the compressible element is reversibly compressible. Generally, if C' / A is 0.95 or greater, the compressible element is considered substantially reversibly compressible. In some cases, C'=C (or B'=B), and the compressible element is irreversibly compressible. Generally, if B' / B is 0.95 or greater, the compressible element is considered substantially irreversibly compressible. Generally, if B' / B is less than 0.95 and C' / A is less than 0.95, a compressible element is considered partially irreversibly compressible (or similarly, partially reversibly compressible).

[0120] In some embodiments, the pressure 895 required to compress a compressible element to less than 95% of its initial thickness, or less than 90%, 85%, 80%, 75%, or 70%, is 100 MPa or less, or 50 MPa, 20 MPa, 10 MPa, 5 MPa, 2 MPa, 1 MPa, 0.5 MPa, 0.2 MPa, or 0.1 MPa or less. In some cases, such pressures may be in the range of 0.01–0.02 MPa, 0.02–0.05 MPa, 0.05–0.1 MPa, 0.1–0.2 MPa, 0.2–0.5 MPa, 0.5–1 MPa, 1–2 MPa, 2–5 MPa, 5–10 MPa, 10–20 MPa, 20–50 MPa, 50–100 MPa, or any combination of these ranges. In some cases, an element is considered incompressible if its compressibility does not fall below 95% under a pressure of 100 MPa.

[0121] In some embodiments, the compressible element may be characterized by having a bending yield strength of less than 100 MPa, or less than 50 MPa, 20 MPa, 10 MPa, 5 MPa, 2 MPa, 1 MPa, 0.5 MPa, 0.2 MPa, or 0.1 MPa. In some cases, the bending yield strength of the compressible element may be in the range of 0.01 to 0.02 MPa, 0.02 to 0.05 MPa, 0.05 to 0.1 MPa, 0.1 to 0.2 MPa, 0.2 to 0.5 MPa, 0.5 to 1 MPa, 1 to 2 MPa, 2 to 5 MPa, 5 to 10 MPa, 10 to 20 MPa, 20 to 50 MPa, 50 to 100 MPa, or any combination of these ranges.

[0122] Compressible separator In some embodiments, one or more separators are compressible during battery operation or cycling. That is, the compressible element may be a separator. The separator may contain a compressible material and / or have a compressible structure. Figures 9A-9F are schematic cross-sectional views of some battery cells having compressible separators according to various embodiments. The compressible separator 920 is located between the silicon-containing active material layer 907 (located on one side of the anode current collector 901) and the cathode active material layer 937 (located on one side of the cathode current collector 931). The pores and voids of the compressible separator 920 may contain a non-aqueous lithium-ion electrolyte 970, which is also located between the anode active material layer and the cathode active material layer. Figure 9A may show a battery cell before any electrochemical cycle, or when the anode is in a substantially discharged state, storing less than 30%, 20%, or 10% of its operating lithium storage capacity. The battery cell is in its initial state. The separator 920 may be characterized by its initial thickness A, as described with respect to Figures 8A to 8C.

[0123] In Figure 9B, the battery cell enters a charged state after an electrochemical charging event or cycle, and the anode has accumulated more than 30% of its operating lithium storage capacity. As already mentioned, silicon expands upon lithiation. The compressible separator does not transmit all of this expansion force to the cell housing, but absorbs a portion of it, compressing by a quantity B to a post-compression thickness C. In some embodiments, during the compression of the separator, a portion of the electrolyte 970 may move out of the separator and into an electrolyte reservoir or pocket (not shown) provided within the cell. In some embodiments, the electrolyte reservoir may be characterized by a reservoir volume in the range of 0.1–0.5%, 0.5–1.0%, 1–2%, 2–5%, 5–10%, 10–15%, or any combination of these ranges, relative to the total internal cell volume not occupied by the battery assembly. In some cases, the electrolyte reservoir may be housed within the cell by a bladder structure that can expand and contract as needed.

[0124] In some embodiments, the separator may be substantially reversibly compressible, and in subsequent discharge events, the cell may appear similar to that shown in Figure 9A. In some embodiments, if any electrolyte 970 has moved to the reservoir, it may flow back into the pores / voids of the separator during cell discharge. In some embodiments, the substantially reversibly separator may contain a highly elastic polymer material or have gel-like properties in the presence of the liquid electrolyte.

[0125] In some embodiments, the separator is at least partially irreversibly compressible. If the separator is partially or substantially irreversibly compressible, after a discharge event, the separator may remain primarily in contact with the cathode side (separator 920c, Figure 9C), primarily in contact with the anode side (separator 920d, Figure 9D), substantially separated from both (separator 920e, Figure 9E), or a mixture of these states within the battery cell. In some embodiments, if some of the electrolyte 970 flows into the reservoir during charging, it may flow into new voids created by the deformed separator structure.

[0126] Compressible (reversible or irreversible) separators may typically include polymeric materials (including synthetic polymers and / or naturally occurring polymers, such as cellulosic materials). The polymeric materials may have some degree of elasticity. As mentioned above, the separator may include pores and channels in which electrolytes may exist / retain. In some embodiments, the separator may further include electrolyte-free pockets, such as micropockets or nanopockets, which contain voids or gas and are preferably left unfilled with electrolyte. The internal pockets may be in the form of trapped bubbles. Such pockets are readily compressible and may reduce the need for and volume of an electrolyte reservoir to capture electrolyte squeezed out of the separator during compression. Thus, the separator may have a compressible structure. The compressible separator or a part thereof may have a foamy appearance in cross-section.

[0127] The separator may have a multilayer structure. In some embodiments, as shown in Figure 9F, the separator 920f may include a separator sublayer 920-1 adjacent to the anode active material layer 907 and a separator sublayer 920-2 adjacent to the cathode active material layer 937. Although not shown, the separator may include an additional sublayer between 920-1 and 920-2. In some embodiments, the separator sublayer 920-1 may have lower compressibility than the separator sublayer 920-2. For example, the separator sublayer 920-1 may contain a ceramic material, while the separator sublayer 920-2 may contain a compressible polymer material (with reversible or irreversible properties). Some non-limiting examples of ceramic materials include oxides of Al, Ti, P, Si, Li, Ta, Zr, and La, as well as mixtures thereof. While the silicon-containing anode active material layer 907 may expand uniformly during charging, there may sometimes be hot spots that expand more than other areas. If the separator sublayer 920-1 has low or virtually no compressibility, the force applied by the hot spot is dispersed along the separator sublayer 920-1 and uniformly transmitted through the cathode active material layer via the more compressible separator sublayer 920-2. Furthermore, the less compressible separator sublayer may play a role in suppressing the formation of hot spots by providing a firm reaction force against the expanding area of ​​the anode, thereby promoting more uniform utilization of the entire anode.

[0128] In some other cases, it may be advantageous for separator sublayer 920-2 to have lower compressibility compared to separator sublayer 920-1. For example, separator sublayer 920-2 may contain a porous ceramic material, while separator sublayer 920-1 may contain a compressible polymer material. In some cases, placing a compressible separator material adjacent to the anode may reduce the likelihood of the silicon-containing anode active material layer rupturing during expansion, thereby extending the cycle life.

[0129] Although not shown in the figures, the separator may include three or more sublayers, and in some embodiments, at least one of the two separator sublayers adjacent to the active material layer may contain a material that is more compressible than one or more internal sublayers (e.g., ceramics) (e.g., polymers). Alternatively, at least one of the two separator sublayers adjacent to the active material layer may contain a material that is less compressible than one or more internal sublayers (e.g., polymers) (e.g., ceramics). In some cases, the separator structure may even provide a gradient that increases or decreases compressibility.

[0130] In the above comparison, the less compressible separator material may be a material other than ceramic, such as a low-compressibility polymer. In some cases, the highly compressible polymer separator material may include cellulose-based materials or polymer films that are gel-like or have elastic properties.

[0131] In some embodiments, the separator may include a material or coating that promotes electrolyte wetting. This may improve cell performance (e.g., uniformity between electrodes) or assist in manufacturing processes such as electrolyte filling.

[0132] Compressible liner / compressible central element In some embodiments, the battery cell may include a compressible liner around the wall(s) or central element, as mentioned elsewhere. In some cases, the central element may be a compressible central element. In some embodiments, the compressible liner or central element may be similar in material and structure to those described with respect to the separator. The compressible liner or central element may be substantially reversibly compressible, at least partially irreversibly compressible, completely irreversibly compressible, or even non-compressible. However, unlike the separator, there is no porosity requirement for the electrolyte and ions to flow through it. For example, the compressible liner or central element may be non-porous. In some cases, it may be advantageous that the compressible liner or central element substantially does not absorb or contain the electrolyte. In some cases, the compressible liner or central element may include a polymer material having pockets containing voids or gas, preferably maintaining a state where the electrolyte does not enter. Such pockets may be relatively large, or they may be micropockets or nanopockets. The internal pockets may be in the form of trapped bubbles. Such pockets are easily compressible and may reduce the need for an electrolyte reservoir to capture electrolytes that could be squeezed out of the liner or central element if not captured during compression (or reduce its volume). In some embodiments, the compressible liner or central element may partially function as an electrolyte reservoir, while the other portion remains electrolyte-free.

[0133] Compressible current collector In some cases, one or both of the anode and cathode current collectors may have a compressible current collector structure, i.e., the current collector may be a compressible element. Figure 10 is a schematic cross-sectional view of an electrode having a compressible current collector according to several embodiments. The electrode 1040 represents the anode or cathode and may include a compressible current collector structure 1041. This structure may include a compressible core 1042, a first conductive layer 1044a provided on the surface of the compressible core corresponding to the first side of the current collector, and a second conductive layer 1044b provided on the surface of the compressible core corresponding to the second side of the current collector. The first active material layer 1047a is provided on the first side of the current collector structure, and the second active material layer 1047b is provided on the second side of the current collector structure. Although not shown, the current collector may include surface layers as described elsewhere.

[0134] The compressible core 1042 generally includes structures and materials that are substantially impermeable to the electrolyte, i.e., structures and materials that do not readily absorb the electrolyte or allow it to penetrate into the structure. The compressible current collector structure may be substantially reversibly compressible, at least partially irreversibly compressible, or completely irreversibly compressible.

[0135] In some embodiments, the compressible core 1042 is electrically insulating and may contain a polymer. The polymeric compressible core may contain a compressible polymer material and / or have a plurality of compressible internal pockets, such as micropockets or nanopockets containing voids or gases, which preferably remain electrolyte-free. The internal pockets may be in the form of trapped gas bubbles. In some cases, the polymeric compressible core may be substantially reversibly compressible.

[0136] In some embodiments, the compressible core 1042 is conductive and may include a metallic material having multiple micropockets or nanopockets containing voids or gases. These pockets preferably remain electrolyte-free. The internal pockets may be in the form of trapped bubbles. In some cases, the conductive layer(s) may be formed from the same metal as the compressible core or from a different conductive material. In some cases, the conductive layer(s) may not be separate layers but simply correspond to the first and second surfaces of the conductive compressible core. In some cases, the metallic compressible core is not reversibly compressible.

[0137] In some cases, the compressible current collector may have a foam-like appearance in cross-section.

[0138] In some embodiments, the conductive layer may have a lower compressibility than the compressible core, which can enhance the structural integrity of the active material / current collector interface.

[0139] Compressible active material layer When the active material layer is coated from a slurry, it is common to calender the active material layer (roll rolling under pressure). This compresses the layer and improves its conductivity (for example, by improving the packing of conductive carbon-based materials, which are often added to active materials). It also improves the cohesiveness of the active material layer or its adhesion to the current collector. In this disclosure, one or both of the cathode active material layers may be coated from a slurry. Similarly, one of the silicon-containing anode active material layers may also be slurry coated.

[0140] In some embodiments, instead of optimally calendering the active material layer before battery assembly, calendering is omitted or limited, allowing the active material layer to function well within the cell while still maintaining compressibility. During cycling, as the silicon, particularly the silicon-containing anode active material layer deposited by CVD or PVD processes, expands, the pressure inside the cell is absorbed, at least partially, by the compressible slurry-coated active material layer. This can result in the active material layer being further "in situ" calendered, potentially leading to improved properties (e.g., lower resistance) after the initial cycle compared to its original state within the cell. The battery cell may optionally include an electrolyte reservoir.

[0141] In some cases, the slurry-coating active material layer within the battery cell (e.g., the cathode active material layer) may be a compressible element. The active material layer is reversibly compressible, but in many cases, it is partially or substantially irreversibly compressible.

[0142] In non-specific examples, the density is typically 3.7 g / cm³. 3 Instead of a cathode active material layer that is calendered to a thickness of 92 microns, a high porosity, low density cathode active material is used, resulting in a calendered thickness of 120 microns and a density of 2.8 g / cm³. 3 It may be limited to this extent. While the thickness and density of conventional cathode material layers can meet the performance characteristics required during operation, low-density cathodes also function without problems. If a 14-micron silicon-containing anode active material layer expands to 42 microns (increment of 28 microns) during initial charging, that pressure is transmitted and applied to the low-density cathode active material layer, compressing it by 28 microns to achieve the desired thickness and density (92 microns and 3.7 g / cm³). 3This can be achieved. In this non-limiting example, the separator may be relatively low compressible, for example, a ceramic separator, thereby ensuring sufficient transmission of compressive force to the low-density cathode. Similarly, the current collector may be selected to have a low compressibility. However, in other embodiments, one may start with a cathode having an intermediate density and not requiring much compression to achieve the desired operating thickness and density. In such cases, the separator(s) or current collector(s) may have some degree of compressibility.

[0143] In some embodiments, the cathode active material layer may initially have a multilayer structure. Figure 11 is a schematic cross-sectional view of a portion of a battery cell 1140 having a compressible cathode active material layer according to some embodiments. The separator 1120 is positioned between the silicon-containing active material layer 1107 (provided on one side of the anode current collector 1101) and the compressible cathode active material layer 1137 (provided on one side of the cathode current collector 1131). The compressible cathode active material layer 1137 may include a first sublayer 1137-1 adjacent to the cathode current collector 1131 and a second sublayer 1137-2 positioned toward the anode (adjacent to the separator 1120 in Figure 11). Sublayer 1137-2 may have a lower density than sublayer 1137-1. For example, sublayer 1137-1 may be first coated onto the cathode current collector from the first cathode formulation and calendered to a desired thickness. Sublayer 1137-2 may be coated onto the first sublayer 1137-1 from the second cathode formulation. In some cases, the second sublayer 1137-2 may not be calendered or may be calendered at a lower pressure than sublayer 1137-1. In some cases, the second cathode formulation may be the same as or different from the first cathode formulation. For example, the second cathode formulation may have a higher ratio of binder to cathode active material. Alternatively or additionally, the second cathode formulation may use a different binder or a different amount or type of conductive agent. During an electrochemical cycle, for example, during a charging event, the second cathode material sublayer 1137-2 is compressed more than sublayer 1137-1 (acting as a compressible element). While a single low-density compressible cathode active material layer has initial resistance or other problems, the presence of sublayer 1137-1 enables an effective charging event that compresses the second sublayer, thereby improving initial cell performance. This not only allows for at least partial expansion of the silicon anode, but also results in a more effective structural state (higher density and / or higher conductivity) for the cathode after compression.

[0144] Although not mentioned in the section on separators and liners, similar strategies may be optionally applied to any of these materials (including but not limited to cellulose) that may be calendered before use or sale. That is, in such cases, they may instead be calendered in situ by the expansive force generated during anode charging.

[0145] Solid-state cell This disclosure relates to a battery cell comprising a liquid non-aqueous electrolyte and a separator, but many of the expansion mitigation measures disclosed herein are also applicable to solid-state batteries. Figure 12 is a schematic cross-sectional view of a portion of a solid-state battery cell 1240 according to several embodiments. The solid-state battery cell 1240 may include a solid electrolyte ("SSE") layer 1222 positioned between a silicon-containing active material layer 1207 (provided on one side of the anode current collector 1201) and a cathode active material layer 1237 (provided on one side of the cathode current collector 1231). In some embodiments, one or more of these mechanisms may function as compressible elements. For example, the SSE layer may be a compressible SSE layer. Alternatively, or additionally, one or both current collectors may be compressible current collectors. Alternatively, or additionally, the cathode active material layer may be a compressible cathode active material layer.

[0146] Electrochemical pretreatment Before use, the battery assembly within the cell housing typically undergoes one or more electrochemical cycle formation processes. "Electrochemical formation" (sometimes simply referred to as "formation" in the art) is an electrochemical process that involves applying and varying a voltage between the anode and cathode, causing the cell to be charged and discharged one or more times. This involves forming an SEI coating on the anode and a cathode-electrolyte interface phase ("CEI") coating on the cathode, and stabilizing over several formation cycles, which results in some initial (usually irreversible) loss of charge capacity (sometimes called "formation loss"). This allows the cell to achieve a more reliable initial state for actual use. Electrochemical formation in silicon-based anodes can sometimes cause significant expansion, although actual expansion during operation may be much smaller. This can place a significant burden on cell design during the electrochemical formation process to accommodate such expansion.

[0147] In some embodiments, the anode and cathode, or the anode alone, may be electrochemically pretreated before being assembled into the final battery cell. The electrochemical pretreatment may, in some cases, be similar to an electrochemical formation cycle procedure, but performed in a temporary cell in the presence of a pretreatment electrolyte (which may have the same or a different composition as the electrolyte used in the final battery cell). In some cases, the electrochemical pretreatment may involve at least partial charging of the anode, followed by at least partial discharge. For example, a jelly roll electrode assembly may be loosely rolled and placed in an oversized temporary cell and pretreatment electrolyte. The electrode assembly may be electrochemically pretreated, and the temporary cell may readily accommodate expansion and other dimensional changes. The pretreated jelly roll assembly may then be transferred to the final cell for final battery construction. The pretreated jelly roll assembly may be washed, dried, crimped, or subjected to any other intermediate treatment as needed before being transferred to the final cell casing. In the final cell, anode expansion during charging in operation is substantially smaller than expansion during electrochemical pretreatment, for example, within the following ranges: 20-30% smaller, 30-40% smaller, 40-50% smaller, 50-60% smaller, 60-70% smaller, or any combination of these ranges, or even more than 70% smaller. Expansion may, in some cases, refer to changes in the dimensionality of the anode, such as expansion of the anode active material layer or stress on the anode current collector.

[0148] In some embodiments, the anode, or anode and cathode, may be electrochemically pretreated by passing them through an electrolyte bath with a suitable counter electrode placed as needed. The pretreated electrode(s) may then be wound up or cut and transferred to a battery cell casing.

[0149] The electrochemical pretreatment may be carried out at room temperature (approximately 20°C), or at temperatures higher or lower than room temperature. In some embodiments, the electrochemical pretreatment may be carried out at temperatures of 0-10°C, 10-20°C, 20-30°C, 30-40°C, 40-50°C, 50-60°C, 60-70°C, 70-80°C, 80-90°C, 90-100°C, any combination of these ranges, or even above 100°C.

[0150] In some embodiments, the anode, or both the anode and cathode, may be calendered after electrochemical pretreatment.

[0151] electrolyte Non-aqueous lithium-ion electrolytes may be liquid, solid, gel, or some kind of multiphase mixture. A typical liquid electrolyte comprises one or more solvents and one or more salts, at least one of which contains lithium. During the first few charging cycles (sometimes called formation cycles), the organic solvent and / or electrolyte may partially decompose at the negative electrode surface to form an SEI (Solid Electrolyte Interface Phase) layer. The SEI is generally electrically insulating but ionic conductive, thereby allowing lithium ions to pass through. The SEI can suppress the decomposition of the electrolyte in subsequent charging cycles.

[0152] Some non-exclusive examples of non-aqueous solvents suitable for lithium-ion cells include cyclic carbonates (e.g., ethylene carbonate (EC), fluoroethylene carbonate (FEC), propylene carbonate (PC), butylene carbonate (BC), and vinylethylene carbonate (VEC)), vinylene carbonate (VC), lactones (e.g., gamma-butyrolactone (GBL), gamma-valerolactone (GVL), and alpha-angelicalactone (AGL)), linear carbonates (e.g., dimethyl carbonate (DMC), methyl ethyl carbonate (MEC, commonly abbreviated as EMC), diethyl carbonate (DEC), methyl propyl carbonate (MPC), and dipropyl carbonate (DP)). Examples include C) methylbutyl carbonate (MBC) and dibutyl carbonate (DBC), ethers (e.g., tetrahydrofuran (THF), 2-methyltetrahydrofuran, 1,4-dioxane, 1,2-dimethoxyethane (DME), 1,2-diethoxyethane and 1,2-dibutoxyethane), nitriles (e.g., acetonitrile and adiponitrile), linear esters (e.g., methylpropionate, methylpivalate, butylpivalate and octylpivalate), amides (e.g., dimethylformamide), organophosphates (e.g., trimethyl phosphate and trioctyl phosphate), S=O group-containing organic compounds (e.g., dimethyl sulfone and divinyl sulfone), and combinations thereof.

[0153] Non-aqueous liquid solvents can be used in combination. Examples of these combinations include cyclic carbonate-chain carbonate, cyclic carbonate-lactone, cyclic carbonate-lactone-chain carbonate, cyclic carbonate-chain carbonate-lactone, cyclic carbonate-chain carbonate-ether, and cyclic carbonate-chain ester. In some embodiments, the cyclic carbonate may be combined with the chain ester. Furthermore, the cyclic carbonate may be combined with lactone and chain ester. In some embodiments, the weight ratio or volume ratio of the cyclic carbonate to the chain ester may be in the range of 1:9 to 10:1 or 2:8 to 7:3.

[0154] Examples of salts used in liquid electrolytes include, but are not limited to, LiPF6, LiBF4, LiClO4, LiAsF6, LiN(CF3SO2)2 ("LiTFSI"), LiN(C2F5SO2)2, LiCF3SO3, LiC(CF3SO2)3, LiPF4(CF3)2, LiPF3(C2F5)3, LiPF3(CF3)3, LiPF3(iso-C3F7)3, LiPF5(iso-C3F7), and lithium salts having cyclic alkyl groups (e.g., (CF2)2(SO2) 2x Li and (CF2)3(SO2) 2x It may contain one or more of the following: Li), LiFSI (lithium bis(fluorosulfonyl)imide), LiTDI (lithium 4,5-dicyano-2-(trifluoromethyl)imidazole), and combinations thereof.

[0155] In some embodiments, the total concentration of the lithium salt in the liquid non-aqueous solvent (or combination of solvents) is at least 0.3 M, or at least 0.7 M. The upper limit of the concentration may be determined by the solubility limit and the operating temperature range. In some embodiments, the salt concentration is about 2.5 M or less, or about 1.5 M or less. In some embodiments, the electrolyte may include a saturated solution of the lithium salt and an excess of solid lithium salt.

[0156] The electrolyte may contain additives to provide various functions, such as stabilizing the battery. For example, additives such as polymerizable compounds having unsaturated double bonds may be added to stabilize or modify the SEI. Certain amines or borate compounds may function as cathode protectants. By adding a Lewis acid (PF6) -Fluorine-containing anions such as can be stabilized. Safety protectants include those that protect against overcharging, such as anisoles, or those that function as flame retardants, such as alkyl phosphates. Other additives may include fluorinating materials (e.g., FEC or various hydrofluoroethers), or silane or siloxane derivatives. Other additives may include ionic liquids, or materials that capture or sequester water, HF, transition metal ions, etc. In some embodiments, the electrolyte may be prepared as a locally concentrated electrolyte. In some embodiments, the electrolyte may include a non-aqueous ionic liquid and a lithium salt.

[0157] SSE Solid electrolytes include a mobile lithium-ion source that diffuses between the anode and cathode (moving to the anode during charging and away from the anode during discharging). The three main families of SSEs are solid polymer electrolytes (SPEs), solid inorganic electrolytes (SIEs), and hybrid SSEs that use both SPE and SIE materials. Note that, in this specification, SPEs also include the category of gel electrolytes. In some cases, the lithium-ion source may include a lithium salt in small molecule form (e.g., LiTSFI, LiPF6, or any other lithium salt mentioned above) suspended or dissolved in the SSE matrix. In some cases, the SPE material may include an anionic functional group that acts as a counterion to the lithium salt. SSEs may optionally include plasticizers, rheology regulators, or even small amounts of organic solvents.

[0158] Some non-limiting examples of polymer materials usable in SSE compositions include poly(ethylene oxide) (PEO), poly(acrylonitrile) (PAN), poly(methyl methacrylate) (PMMA), poly(vinyl alcohol) (PVA), poly(trimethylene carbonate), diester polymers, PVdF polymers, polycaprolactone, and their derivatives and copolymers, which can be used alone or in combination. The polymers of SSE may, in some cases, be crosslinked or branched. The polymers may be block copolymers. Polymer SSE may be completely amorphous or may contain some degree of crystallinity. The polymers may contain anionic functional groups.

[0159] Some non-limiting classifications of SIE materials that can be used in SSE compositions include β-alumina, LISICON, thio-LISICON, NASICON, perovskite, anti-perovskite, garnet, composite hydrides, and solid sulfides.

[0160] Some non-limiting classifications of solid sulfides include ceramic sulfides, glass sulfides, and glass-ceramic sulfides. Glass sulfides exhibit very little long-range order, as evidenced by the absence of peaks in patterns resulting from X-ray diffraction (XRD) measurements. Glass-ceramic sulfides contain several glassy structural regions and several regions with long-range order that appear as characteristic peaks in patterns resulting from XRD measurements. Ceramic sulfides (also called crystalline sulfides) consist of regions with long-range order identified by characteristic peaks appearing in patterns resulting from X-ray diffraction (XRD) measurements. Non-limiting examples of ceramic sulfides include algyrodites, silicon thiophosphate, and silicon thiophosphate halides. Exemplary but non-limiting solid sulfides include thiophosphate esters (PS4) that exhibit characteristic peaks in patterns obtained by infrared spectroscopy or Raman spectroscopy measurements. Some additional examples of solid sulfides include Li6PS5Cl, Li 10 GeP2S 12 LGPS materials such as Li7P3S11 It may contain LPS materials such as those mentioned above.

[0161] In some embodiments, under battery operating conditions, the SSE may have lithium-ion conductivity in the range of 0.001 mS / cm to 0.01 mS / cm, or in the range of 0.01 mS / cm to 0.1 mS / cm, or in the range of 0.1 mS / cm to 1.0 mS / cm, or in the range of greater than 1 mS / cm.

[0162] The thickness of the SSE (Single-Sequence Element) must be sufficient to prevent short circuits between the anode and cathode, while ensuring that the increase in resistance or decrease in energy density does not exceed desirable levels. The thickness of the SSE is generally greater than 100 nm and less than 800 microns. For microbatteries, the thickness ranges from approximately 100 nm to 5 microns. In conventional battery cells, the SSE can typically have a thickness in the range of 5 to 300 microns.

[0163] In some embodiments, the SSE may contain a smaller amount of organic solvent, for example, to enhance lithium ion conductivity, or simply as a medium for adding lithium salts. Some non-limiting examples of such solvents include those described above as liquid electrolytes. In some embodiments, the weight percentage of the solvent relative to the other components of the SSE may be less than 10%, or less than 5%, 2%, 1%, 0.5%, 0.2%, or 0.1%.

[0164] In some embodiments, the SSE may be a compressible element (e.g., a compressible SSE layer).

[0165] In some embodiments, the battery cell may include a liquid electrolyte and an SSE layer (which may optionally be a compressible SSE layer) disposed on the cathode active material layer and / or the silicon-containing anode active material layer. Such a battery cell may further include a separator.

[0166] Cathode The positive electrode (cathode) active material used in the cathode active material layer is a lithium metal oxide or compound (e.g., LiCoO2, LiFePO4, LiMnO2, LiNiO2, LiMn2O4, LiCoPO4, LiNi x Co y Mn z O2, LiLiLi X Co Y Al Z The cathode active material includes, but is not limited to, O2, LiFe2(SO4)3, or Li2FeSiO4, metallic fluorides such as carbon fluoride and iron fluoride (FeF3), metal oxides, sulfur, selenium, and combinations thereof. The cathode active material may operate by intercalation, conversion, or a combination thereof. The cathode active material may be mixed with one or more binders and / or conductive agents (e.g., conductive carbon) and coated to form a cathode active material layer. In some cases, the cathode active material layer may include, in addition to the cathode active material, any polymer system, SIE, or hybrid SSE material as described elsewhere in this specification, which may be the same as or different from the material used in the SSE layer between the anode and the cathode. In some cases, the solid electrolyte used in the cathode may be different from that of the SSE layer. The cathode active material layer is usually provided on or electrically connected to a conductive cathode current collector.

[0167] Electrochemical formation In some embodiments, the original uncycled anode may undergo structural or chemical changes through electrochemical charge-discharge (e.g., during normal battery use or an initial "electrochemical formation process"). As is known in the art, electrochemical formation processes are commonly used to form the initial SEI layer and are sometimes carried out under milder conditions of low current and limited voltage. Modified anodes, partially conditioned through such electrochemical charge-discharge cycles, may maintain superior performance characteristics even after undergoing structural and / or chemical changes compared to the original uncycled anode. In some embodiments, the lithium storage layer of the cycled anode appears not as a continuous layer but as separate segments or islands, generally with an average aspect ratio of height to width of less than 2. Not bound by theory, this may be because, in the case of amorphous silicon, trace amounts of delamination may occur during cycling in high-stress regions. Alternatively, or additionally, such islands or segments may arise because the structural changes associated with lithiation and delithiation are asymmetrical.

[0168] In some embodiments, a battery cell may be configured to have one or more ports. In some cases, ports may be used to transfer electrolyte into and / or out of the cell. For example, a cell may have one port used to evacuate the cell and provide a low-pressure (vacuum) environment. The electrolyte may then be injected into the cell through the port. In some cases, there may be separate ports for draining the electrolyte or for "flushing" the cell with electrolyte via the injection and drain ports. In some embodiments, the electrochemical formation cycle may be performed using a first electrolyte (formed electrolyte) and then replaced with a non-aqueous lithium-ion electrolyte used in the working cell. In some cases, the electrochemical formation may be performed at a high temperature, such as in the range of 40–100°C. Furthermore, electrolyte filling and / or electrochemical formation may be performed at such high temperatures, and the cell may be sealed while still warm. This creates a slightly reduced-pressure environment and also provides a margin for expansion during operation. That is, starting the cell at low pressure results in lower pressure on the cell during expansion associated with silicon lithiation compared to starting at atmospheric pressure.

[0169] In some embodiments, the electrochemical cycling conditions of the operating battery cell may be set to utilize only a portion of the silicon's theoretical charge-discharge capacity (3600 mAh / g). In some embodiments, the electrochemical charge-discharge cycle may be configured to utilize 400-600 mAh / g, or 600-800 mAh / g, or 800-1000 mAh / g, or 1000-1200 mAh / g, or 1200-1400 mAh / g, or 1400-1600 mAh / g, or 1600-1800 mAh / g, or 1800-2000 mAh / g, or 2000-2200 mAh / g, or 2200-2400 mAh / g, or 2400-2600 mAh / g, or 2600-2800 mAh / g, or 2800-3000 mAh / g, or 3000-3200 mAh / g, or 3200-3400 mAh / g, or any combination of these ranges.

[0170] In some embodiments, the battery cells of the present disclosure may have a volumetric energy density of at least 750 Wh / L (e.g., 750-800 Wh / L, 800-900 Wh / L, 900-1000 Wh / L, or any combination of these ranges, or even greater than 1000 Wh / L). In some embodiments, the battery cells of the present disclosure may have a gravimetric energy density of at least 300 Wh / kg (e.g., 300-350 Wh / kg, 350-400 Wh / kg, 400-500 Wh / kg, 500-600 Wh / kg, 600-700 Wh / kg, or any combination of these ranges, or even greater than 700 Wh / kg). In some embodiments, the battery cells of the present disclosure may be characterized by having an 80% SoH (Battery Health) cycle life of more than 150 cycles, or optionally more than 200 cycles, or optionally more than 300 cycles, when tested at a discharge rate of C / 3 and a charge rate of C / 3 (or a charge rate of 1C, or a charge rate of 3C).

[0171] N / P ratio A battery cell may be characterized by an "N / P ratio," which is the ratio of the charge capacity per unit area of ​​the anode (negative electrode) active material to the charge capacity per unit area of ​​the cathode (positive electrode) active material. In some embodiments, the N / P ratio may be in the range of 0.95 to 1.0, or 1.0 to 1.05, 1.05 to 1.1, 1.1 to 1.2, 1.2 to 1.3, 1.3 to 1.4, 1.4 to 1.5, 1.5 to 1.6, 1.6 to 1.7, 1.7 to 1.8, 1.8 to 1.9, 1.9 to 2.0, 2.0 to 2.5, 2.5 to 3.0, 3.0 to 3.5, 3.5 to 4.0, or any combination of these ranges, or even a range greater than 4.0. In some cases, the N / P ratio is at least 1.05.

[0172] In non-limiting examples, a battery cell may include a) an anode having a copper foil current collector (10-14 μm) and silicon (10-16 μm) deposited on both sides by PECVD, b) a compressible separator (25-35 μm) that can be compressed by 40-60%, and c) a cathode having an aluminum current collector (8-15 μm) and cathode active material (85-100 μm) coated on both sides.

[0173] In some embodiments, by using one or more of the expansion suppression techniques disclosed above (such as compressible separators, compressible cathode active material layers, compressible current collectors, compressible central elements, compressible liners, electrolyte reservoirs, high porosity silicon-containing anode active materials, electrochemical pretreatment, etc.), the pressure applied to the cell casing due to anode expansion (e.g., during charging or formation) can be reduced by at least 25%, at least 50%, or at least 75% compared to the same cell to which no expansion suppression technique is applied. In some embodiments, by using one or more expansion suppression techniques, the expansion of the electrode assembly during charging can be suppressed to less than 10%, less than 8%, or less than 5% of the initial electrode assembly thickness (or subunit thickness).

[0174] systematic consideration In some cases, the battery cell may include one or more pressure elements that apply some moderate physical pressure between the anode and cathode, which may improve the overall structural stability of the electrode assembly during the cycle. For example, in the case of a solid-state battery, the anode or cathode tends to detach from the SSE during the discharge cycle, but a good connection can be maintained by an external force. The pressure element may be a compressible film, which may be made from a porous polymer or silicon, for example. In some cases, a compressible liner used between the electrode assembly and the housing may function as a pressure element. Alternatively, the pressure element may include a spring or a spring array. Alternatively, the pressure element may correspond to both sides of a compression clip or clamp.

[0175] In some embodiments, multiple battery cells may be used together within a single battery module. In the case of prismatic lithium-ion battery cells, some bending may occur during operation. As a precaution, compressible pads may be placed between the prismatic cells to prevent bending / expansion forces from propagating throughout the module. In some cases, the expansion suppression techniques disclosed herein may reduce or eliminate the need for such compressible pads between battery cells.

[0176] Enumerated embodiments Furthermore, further embodiments described herein include the following enumerated embodiments.

[0177] Enumerated Embodiment 1. An electrode assembly, a) An anode comprising an anode current collector and a first silicon-containing anode active material layer disposed on the first side of the anode current collector, wherein the first silicon-containing anode active material layer contains at least 85 atomic percent silicon, and the anode and b) A cathode comprising a cathode current collector and a compressible first cathode active material layer disposed on the first side of the cathode current collector, wherein the first side of the cathode current collector is adjacent to the first side of the anode current collector, c) The electrode assembly comprising a first separator disposed between the first cathode active material layer and the first anode active material layer, A non-aqueous lithium-ion electrolyte is disposed between the anode and the cathode and in contact with the anode and the cathode. A lithium-ion battery cell comprising a battery cell housing that accommodates the electrode assembly and the non-aqueous lithium-ion electrolyte, wherein the housing includes a positive electrode battery terminal electrically connected to the cathode and a negative electrode battery terminal electrically connected to the anode.

[0178] Enumerated Embodiment 2. The battery cell described in Enumerated Embodiment 1, The anode includes a second silicon-containing anode active material layer disposed on the second side of the anode current collector, The battery cell wherein the cathode includes a second cathode active material layer located on the second side of the cathode current collector, and the second side of the cathode current collector is distal to the first side of the anode current collector.

[0179] Enumerated Embodiment 3. A lithium-ion battery cell according to Enumerated Embodiment 2, wherein the electrode assembly further comprises a second separator, i) disposed between the second cathode active material layer and the second silicon-containing anode active material layer if the electrode assembly includes a jelly roll structure, or ii) disposed between the second cathode active material layer and a silicon-containing anode active material provided on the second anode current collector if the electrode assembly includes a stack structure.

[0180] Enumerated Embodiment 4. The battery cell according to Enumerated Embodiment 2, wherein the electrode assembly further includes a second separator, and the cathode is disposed between the first separator and the second separator.

[0181] Enumerated Embodiment 5. The battery cell according to Enumerated Embodiment 4, wherein the electrode assembly includes a jelly roll structure or a stack structure.

[0182] Enumerated Embodiment 6. A battery cell according to any of the enumerated embodiments 3 to 5, In cross-section, the anode, the first separator, the cathode, and the second separator form a first subunit of the electrode assembly. The first subunit is one of a plurality of subunits, each subunit comprising its respective anode, its respective first separator, its respective cathode, and its respective second separator. The battery cell wherein the plurality of subunits are arranged in a stacked structure or a jelly roll structure.

[0183] Enumerated Embodiment 7. A lithium-ion battery cell according to Enumerated Embodiment 6, wherein the plurality of subunits include at least five subunits.

[0184] Enumerated Embodiment 8. A battery cell according to any of the enumerated embodiments 1 to 7, wherein at least one silicon-containing anode active material layer comprises 1 to 4 mg / cm³. 2 The battery cell characterized by silicon loading in the range of [range].

[0185] Enumerated Embodiment 9. A battery cell according to any of the enumerated embodiments 1 to 8, wherein, before assembly of the cell, at least one silicon-containing anode active material layer is 1.2 to 2.2 g / cm³. 3 The battery cell, characterized by its density immediately after deposition within a range of [value].

[0186] Enumerated Embodiment 10. A battery cell according to any of the enumerated embodiments 1 to 9, wherein at least one silicon-containing anode active material layer is 1.2 to 2.2 g / cm³. 3 The battery cell, characterized by the density of the range.

[0187] Enumerated Embodiment 11. A battery cell according to any of the enumerated embodiments 1 to 10, wherein, prior to assembly of the cell, at least one silicon-containing anode active material layer is characterized by a deposition thickness in the range of 3 to 25 μm.

[0188] Enumerated Embodiment 12. A battery cell according to any of the enumerated embodiments 1 to 11, wherein at least one silicon-containing anode active material layer is characterized by a thickness in the range of 3 to 25 μm.

[0189] Enumerated Embodiment 13. A battery cell according to any of the enumerated embodiments 1 to 12, wherein at least one separator comprises a compressible material.

[0190] Enumerated Embodiment 14. A battery cell according to any of the enumerated embodiments 1 to 13, wherein during battery cell operation, at least one separator is compressible by at least 25% from its initial thickness, or optionally at least 50%.

[0191] Enumerated Embodiment 15. The battery cell according to Enumerated Embodiment 13 or 14, wherein at least one separator is substantially reversibly compressible.

[0192] Enumerated Embodiment 16. The battery cell according to Enumerated Embodiment 13 or 14, wherein the at least one separator is at least partially irreversibly compressible.

[0193] Enumerated Embodiment 17. The battery cell according to Enumerated Embodiment 16, wherein at least one separator comprises a cellulose-based material.

[0194] Enumerated Embodiment 18. A battery cell according to any of the enumerated embodiments 1 to 17, wherein at least one separator includes a multilayer structure comprising an anode-facing side and a cathode-facing side.

[0195] Enumerated Embodiment 19. The battery cell according to Enumerated Embodiment 18, wherein the anode-facing side has higher compressibility than the cathode-facing side.

[0196] Enumerated Embodiment 20. The battery cell according to Enumerated Embodiment 18 or 19, wherein the anode-facing side comprises a cellulose-based material or a synthetic polymer, and the cathode-facing side comprises a ceramic material or a synthetic polymer.

[0197] Enumerated Embodiment 21. The battery cell according to Enumerated Embodiment 18, wherein the anode-facing side has lower compressibility than the cathode-facing side.

[0198] Enumerated Embodiment 22. The battery cell according to Enumerated Embodiment 18 or 19, wherein the anode-facing side comprises a ceramic material or a synthetic polymer, and the cathode-facing side comprises a cellulose-based material or a synthetic polymer.

[0199] Enumerated Embodiment 23. A battery cell according to any of the enumerated embodiments 1 to 22, further comprising an electrolyte reservoir, wherein the electrolyte reservoir is in fluid communication with the electrolyte disposed between the anode and the cathode.

[0200] Enumerated Embodiment 24. A battery cell according to Enumerated Embodiment 23, wherein the battery cell is configured such that the electrolyte can flow in and out of the electrolyte reservoir during battery operation.

[0201] Enumerated Embodiment 25. A battery cell according to Enumerated Embodiment 23 or 24, wherein the battery cell has an internal volume, and the electrolyte reservoir occupies a reservoir volume in the range of 5% to 15% of the internal volume.

[0202] Enumerated Embodiment 26. A battery cell according to any of the enumerated embodiments 1 to 25, wherein at least one separator comprises a material that captures or binds HF or water.

[0203] Enumerated Embodiment 27. A battery cell according to any of the enumerated embodiments 1 to 26, wherein at least one current collector includes a compressible current collector structure.

[0204] Enumerated Embodiment 28. The battery cell according to Enumerated Embodiment 27, wherein the compressible current collector structure includes a compressible core, a first conductive layer provided on the compressible core corresponding to the first side of the current collector, and a second conductive layer provided on the compressible core corresponding to the second side of the current collector.

[0205] Enumerated Embodiment 29. The battery cell according to Enumerated Embodiment 28, wherein the compressible core comprises a polymer.

[0206] Enumerated Embodiment 30. A battery cell according to the enumerated embodiment 28 or 29, wherein the compressible core defines internal bubbles or voids.

[0207] Embodiment 31. The battery cell according to any one of Embodiments 28 to 30, wherein the compressible core is electrically insulating, the battery cell.

[0208] Embodiment 32. The battery cell according to any one of Embodiments 28 to 30, wherein the compressible core is electrically conductive, the battery cell.

[0209] Embodiment 33. The battery cell according to any one of Embodiments 28 to 32, wherein the current collector structure is substantially impermeable to the electrolyte, the battery cell.

[0210] Embodiment 34. The battery cell according to any one of Embodiments 27 to 33, wherein the current collector structure is substantially reversibly compressible, the battery cell.

[0211] Embodiment 35. The battery cell according to any one of Embodiments 27 to 33, wherein the current collector structure is at least partially irreversibly compressible, the battery cell.

[0212] Embodiment 36. The battery cell according to any one of Embodiments 27 to 35, wherein the current collector structure is compressible by at least 10%, or optionally at least 20%, or optionally at least 30%, or optionally at least 40% from the initial thickness, the battery cell.

[0213] Embodiment 37. The battery cell according to any one of Embodiments 27 to 36, wherein the anode current collector includes the compressible structure and the cathode current collector is non-compressible, the battery cell.

[0214] Embodiment 38. The battery cell according to any one of Embodiments 27 to 36, wherein the cathode current collector includes the compressible structure and the anode current collector is non-compressible, the battery cell.

[0215] Enumerated Embodiment 39. A battery cell according to any of the enumerated embodiments 27 to 36, wherein the anode current collector and the cathode current collector each include a compressible current collector structure selected individually.

[0216] Enumerated Embodiment 40. A battery cell according to any of the enumerated embodiments 1 to 39, wherein at least one cathode active material layer is compressible.

[0217] Enumerated Embodiment 41. The battery cell according to Enumerated Embodiment 34, wherein during at least one electrochemical cycle, the at least one cathode active material layer is compressible to less than 90% of its original thickness, or optionally less than 80% of its original thickness, or optionally less than 70% of its original thickness.

[0218] Enumerated Embodiment 42. A battery cell according to the enumerated embodiment 40 or 41, wherein the at least one cathode active material layer is substantially reversibly compressible.

[0219] Enumerated Embodiment 43. A battery cell according to the enumerated embodiment 40 or 41, wherein the at least one cathode active material layer is at least partially irreversibly compressible.

[0220] Enumerated Embodiment 44. A battery cell according to any of the enumerated embodiments 2 to 43, wherein the first cathode active material layer and the second cathode active material layer are compressible.

[0221] Enumerated Embodiment 45. A battery cell according to any of the enumerated embodiments 2 to 44, wherein the first cathode active material layer and the second cathode active material layer each have a thickness in the range of 40 to 200 μm, independently selected before any electrochemical cycle.

[0222] Enumerated Embodiment 46. A battery cell according to any of the enumerated embodiments 2 to 45, wherein the first cathode active material layer differs from the second cathode active material layer in terms of thickness, chemical composition, or both thickness and chemical composition.

[0223] Enumerated Embodiment 47. A battery cell according to any of the enumerated embodiments 2 to 46, wherein the first cathode active material layer is substantially the same as the second cathode active material layer.

[0224] Enumerated Embodiment 48. A battery cell according to any of the enumerated embodiments 2 to 47, wherein the first cathode active material layer and the second cathode active material layer each contain a lithium metal oxide compound.

[0225] Enumerated Embodiment 49. A battery cell according to any of the enumerated embodiments 2 to 47, wherein the first cathode active material layer and the second cathode active material layer each contain sulfur, selenium, or both sulfur and selenium.

[0226] Enumerated Embodiment 50. A battery cell according to any of the enumerated embodiments 1 to 49, wherein at least one silicon-containing anode active material layer substantially does not contain a high aspect ratio lithium storage nanostructure.

[0227] Enumerated Embodiment 51. A battery cell according to any of the enumerated embodiments 1 to 50, wherein at least one silicon-containing anode active material layer is a interconnected porous lithium storage layer.

[0228] Enumerated Embodiment 52. A battery cell according to any of the enumerated embodiments 1 to 51, wherein at least one silicon-containing anode active material layer contains a quasi-stoichiometric nitride of silicon.

[0229] Enumerated Embodiment 53. A battery cell according to any one of Enumerated Embodiments 1 to 52, wherein at least one silicon-containing anode active material layer contains a quasi-stoichiometric oxide of silicon, said battery cell.

[0230] Enumerated Embodiment 54. A battery cell according to any one of Enumerated Embodiments 1 to 53, wherein at least one silicon-containing anode active material layer contains amorphous silicon, said battery cell.

[0231] Enumerated Embodiment 55. A battery cell according to any one of Enumerated Embodiments 1 to 54, wherein at least one silicon-containing anode active material layer contains less than 30% nanocrystalline silicon, said battery cell.

[0232] Enumerated Embodiment 56. A battery cell according to any one of Enumerated Embodiments 1 to 55, wherein said at least one silicon-containing anode active material layer contains columns of silicon nanoparticle aggregates, said battery cell.

[0233] Enumerated Embodiment 57. A battery cell according to any one of Enumerated Embodiments 1 to 56, wherein at least one silicon-containing anode active material layer is deposited by a PVD or CVD process, said battery cell.

[0234] Enumerated Embodiment 58. A battery cell according to Enumerated Embodiment 57, wherein said at least one silicon-containing anode active material layer is deposited by PECVD, said battery cell.

[0235] Enumerated Embodiment 59. A battery cell according to any one of Enumerated Embodiments 1 to 58, wherein at least one silicon-containing anode active material layer substantially does not contain a carbon-based binder, said battery cell.

[0236] Enumerated Embodiment 60. A battery cell according to any one of Enumerated Embodiments 1 to 49, wherein at least one silicon-containing anode active material layer contains silicon-containing nanowires, said battery cell.

[0237] Enumerated Embodiment 61. A battery cell according to any of the enumerated embodiments 2 to 60, wherein the second silicon-containing anode active material layer contains at least 85 atomic percent of silicon and is optionally deposited by a PVD or CVD process.

[0238] Enumerated Embodiment 62. A battery cell according to any of the enumerated embodiments 2 to 61, wherein the second silicon-containing anode active material layer is substantially identical to the first silicon-containing anode active material layer in terms of thickness, chemical composition, area capacity, or any combination thereof.

[0239] Enumerated Embodiment 63. A battery cell according to any of the enumerated embodiments 2 to 61, wherein the second silicon-containing anode active material layer differs from the first silicon-containing anode active material layer in terms of thickness, chemical composition, area capacity, or any combination thereof.

[0240] Enumerated Embodiment 64. A battery cell according to any of the enumerated embodiments 2 to 63, wherein the second silicon-containing anode active material layer is a interconnected porous lithium storage layer.

[0241] Enumerated Embodiment 65. A battery cell according to any of the enumerated embodiments 2 to 64, wherein the second silicon-containing anode active material layer contains amorphous silicon.

[0242] Enumerated Embodiment 66. A battery cell according to any of the enumerated embodiments 2 to 65, wherein the second silicon-containing anode active material layer contains less than 30% nanocrystalline silicon.

[0243] Enumerated Embodiment 67. A battery cell according to any of the enumerated embodiments 2 to 66, wherein the second silicon-containing anode active material layer includes a column of silicon nanoparticle aggregates.

[0244] Enumerated Embodiment 68. A battery cell according to any of the enumerated embodiments 2 to 67, wherein the second silicon-containing anode active material layer is deposited by PECVD.

[0245] Enumerated Embodiment 69. A battery cell according to any of the enumerated embodiments 2 to 61, wherein the second silicon-containing anode active material layer includes silicon-containing nanowires or microwires.

[0246] Enumerated Embodiment 70. A battery cell according to any of the enumerated embodiments 2 to 60, wherein the second silicon-containing anode active material layer comprises silicon-containing particles dispersed in a binder.

[0247] Enumerated Embodiment 71. The battery cell according to Enumerated Embodiment 70, wherein the second silicon-containing anode active material layer contains at least 10% by weight of silicon.

[0248] Enumerated Embodiment 72. A battery cell according to any of the enumerated embodiments 1 to 71, further characterized in that its volumetric energy density is at least 800 Wh / L.

[0249] Enumerated Embodiment 73. A battery cell according to any of the enumerated embodiments 1 to 72, further characterized in that its gravimetric energy density is at least 400 Wh / kg.

[0250] Enumerated Embodiment 74. A battery cell according to any of the enumerated embodiments 1 to 73, characterized in that the 80% battery health (SoH) cycle life when tested at a discharge rate C / 3, a charge rate C / 3, or optionally a charge rate of 1C, or optionally a charge rate of 3C, is greater than 150 cycles, or optionally more than 200 cycles, or optionally more than 300 cycles.

[0251] Enumerated Embodiment 75. A battery cell according to any of the enumerated embodiments 1 to 74, further characterized in that the N / P ratio is in the range of 1.05 to 4.0, or optionally 1.1 to 2.0.

[0252] Enumerated Embodiment 76. A battery cell according to any of the enumerated embodiments 2 to 75, wherein the electrode assembly includes a plurality of anodes and a plurality of cathodes having a stacked structure, and a separator is disposed between each pair of anodes and cathodes.

[0253] Enumerated Embodiment 77. The battery cell according to Enumerated Embodiment 76, wherein the first separator and the second separator are part of a single continuous separator folded between adjacent anodes and cathodes.

[0254] Enumerated Embodiment 78. The battery cell according to Enumerated Embodiment 76 or 70, further comprising a compressible liner disposed between at least a portion of the housing and the electrode assembly.

[0255] Enumerated Embodiment 79. The battery cell according to Enumerated Embodiment 78, wherein the compressible liner comprises an electrically insulating polymer.

[0256] Enumerated Embodiment 80. The battery cell according to the enumerated embodiment 78 or 79, wherein the compressible liner defines internal bubbles or voids.

[0257] Enumerated Embodiment 81. A battery cell according to any of the enumerated embodiments 78 to 80, wherein the compressible liner is reversibly compressible.

[0258] Enumerated Embodiment 82. A battery cell according to any of the enumerated embodiments 78 to 80, wherein the compressible liner is at least partially irreversibly compressible.

[0259] Enumerated Embodiment 83. A battery cell according to the enumerated embodiments 76 to 82, wherein the cell is a pouch cell and the housing comprises a flexible polymer material.

[0260] Enumerated Embodiment 84. The battery cell according to Enumerated Embodiment 83, wherein the housing comprises an aluminum polymer laminate having a thickness of less than 0.2 mm.

[0261] Enumerated Embodiment 85. A battery cell according to the enumerated embodiments 76 to 72, wherein the cell is a prismatic cell and the housing includes a rigid material.

[0262] Enumerated Embodiment 86. The battery cell according to Enumerated Embodiment 85, wherein the housing includes a metal having a thickness of at least 0.2 mm.

[0263] Enumerated Embodiment 87. The battery cell according to the enumerated embodiment 85 or 86, wherein the housing comprises aluminum or stainless steel.

[0264] Enumerated Embodiment 88. A battery cell according to any of the enumerated embodiments 2 to 75, wherein the housing comprises a rigid material, and the anode, the first separator, the cathode, and the second separator are wound up to form a jelly roll structure disposed within the housing.

[0265] Enumerated Embodiment 89. The battery cell according to Enumerated Embodiment 88, further comprising a central element around which the jelly roll structure is wound.

[0266] Enumerated Embodiment 90. The battery cell according to Enumerated Embodiment 89, wherein the central element comprises a compressible material.

[0267] Enumerated Embodiment 91. The battery cell according to Enumerated Embodiment 89 or 90, further comprising an internally compressible liner disposed between at least a portion of the central element and the jelly roll structure.

[0268] Enumerated Embodiment 92. The battery cell according to any of the enumerated embodiments 88 to 91, further comprising an external compressible liner disposed between at least a portion of the housing and the jelly roll structure.

[0269] Enumerated Embodiment 93. The battery cell according to Enumerated Embodiment 92, wherein the compressible liner comprises an electrically insulating polymer.

[0270] Enumerated Embodiment 94. The battery cell according to Enumerated Embodiment 92 or 93, wherein the compressible liner defines internal bubbles or voids.

[0271] Enumerated Embodiment 95. A battery cell according to any of the enumerated embodiments 92 to 94, wherein the compressible liner is reversibly compressible.

[0272] Enumerated Embodiment 96. A battery cell according to any of the enumerated embodiments 92 to 94, wherein the compressible liner is partially irreversibly compressible or completely irreversibly compressible.

[0273] Enumerated Embodiment 97. A battery cell according to any of the enumerated embodiments 88 to 96, wherein the housing includes a cylindrical casing, a top cap, a base facing the top cap, and an electrically insulating seal for separating the top cap from the cylindrical casing.

[0274] Enumerated Embodiment 98. A battery cell according to Enumerated Embodiment 97, wherein i) the top cap includes a positive battery terminal for electrically connecting the top cap to the cathode, and ii) the base includes a negative battery terminal for electrically connecting the base to the anode.

[0275] Enumerated Embodiment 99. The battery cell according to Enumerated Embodiment 98, wherein the cathode is electrically connected to the top cap via i) a cathode tab element that is in electrical contact with the cathode current collector, or ii) via an edge area of ​​the cathode current collector that does not contain cathode active material.

[0276] Enumerated Embodiment 100. A battery cell according to Enumerated Embodiment 98 or 99, wherein the anode is electrically connected to the base via i) one or more anode tab elements that are in electrical contact with the anode current collector, or ii) via an edge area of ​​the anode current collector that does not contain anode active material.

[0277] Enumerated Embodiment 101. A battery cell according to Enumerated Embodiment 97, wherein i) the top cap includes a negative battery terminal for electrically connecting the top cap to the anode, and ii) the base includes a positive battery terminal for electrically connecting the base to the cathode.

[0278] Enumerated Embodiment 102. The battery cell according to Enumerated Embodiment 101, wherein the anode is electrically connected to the top cap via i) an anode tab element that is in electrical contact with the anode current collector, or ii) via an edge area of ​​the anode current collector that does not contain anode active material.

[0279] Enumerated Embodiment 103. A battery cell according to Enumerated Embodiment 101 or 102, wherein the cathode is electrically connected to the base via i) one or more cathode tab elements that are in electrical contact with the cathode current collector, or ii) via an edge area of ​​the cathode current collector that does not contain cathode active material.

[0280] Enumerated Embodiment 104. A battery cell according to any of the enumerated embodiments 98 to 103, wherein the electrical connection to the anode or cathode is made in part by laser welding, resistance welding, or ultrasonic welding.

[0281] Enumerated Embodiment 105. A battery cell according to any of the enumerated embodiments 88 to 104, wherein the battery cell is a cylindrical cell.

[0282] Enumerated Embodiment 106. A battery cell according to any of the enumerated embodiments 88 to 96, wherein the housing includes a rectangular casing, a top lid, and a base facing the top lid, and the jelly roll structure is elongated elliptical.

[0283] Enumerated Embodiment 107. The battery cell according to Enumerated Embodiment 106, wherein the top lid includes the positive battery terminal and the negative battery terminal.

[0284] Enumerated Embodiment 108. The battery cell according to Enumerated Embodiment 107, wherein the positive battery terminal is electrically connected to the cathode current collector via a cathode tab element, and the negative battery terminal is electrically connected to the anode current collector via an anode tab element.

[0285] Enumerated Embodiment 109. A battery cell according to any of the enumerated embodiments 88 to 96 or 106 to 108, characterized in that the battery cell is a prismatic cell.

[0286] Enumerated Embodiment 110. A battery cell according to any of the enumerated embodiments 88 to 109, wherein the jelly roll structure or a part thereof is characterized by a radius of curvature, and the thickness of the at least one silicon-containing anode active material layer is less than 1% of the radius of curvature.

[0287] Enumerated Embodiment 111. A battery cell according to any of the enumerated embodiments 88 to 110, wherein the thickness of the at least one silicon-containing anode active material layer is at least 10% thinner in the inner portion of the jelly roll structure than in the outer portion of the jelly roll structure.

[0288] Enumerated Embodiment 112. A method for manufacturing a battery cell according to any of the enumerated embodiments 88 to 111, comprising pre-lithifying the anode to form a pre-lithified anode before winding it with the cathode.

[0289] Enumerated Embodiment 113. The method according to Enumerated Embodiment 112, wherein the prelithiation comprises contacting at least one silicon-containing anode active material layer with a non-aqueous lithium salt solution, and applying a voltage bias between the anode current collector and a counter electrode in contact with the lithium salt solution, thereby electrochemically reducing lithium ions to form the prelithified anode.

[0290] Enumerated Embodiment 114. The method according to Enumerated Embodiment 112, wherein the pre-lithiation comprises contacting at least one silicon-containing anode active material layer with a reducing lithium organic compound or stabilized lithium metal powder.

[0291] Enumerated Embodiment 115. The method according to Enumerated Embodiment 112, wherein the pre-lithiation comprises bringing at least one silicon-containing anode active material layer into contact with a lithium metal.

[0292] Enumerated Embodiment 116. The method according to Enumerated Embodiment 115, further comprising depositing the lithium metal on at least one silicon-containing anode active material layer by PVD.

[0293] Enumerated Embodiment 117. The method according to Enumerated Embodiment 112, wherein at least one separator surface comprises a lithium metal-containing layer, and the at least one separator is laminated with the lithium metal-containing layer to at least one silicon-containing anode active material layer.

[0294] Enumerated Embodiment 118. The method according to Enumerated Embodiment 117, further comprising applying a pressure of at least 200 kPa to the laminate.

[0295] Enumerated Embodiment 119. The method according to any of the enumerated embodiments 112 to 118, further comprising heating the prelithiumized anode to a temperature of at least 50°C, or optionally in the range of 50°C to 150°C, for at least 10 seconds, or optionally for at least 1 minute.

[0296] Enumerated Embodiment 120. The method according to Enumerated Embodiment 119, wherein the heat treatment is performed before the winding of the cathode.

[0297] Enumerated Embodiment 121. The method according to Enumerated Embodiment 119, wherein the heat treatment is performed after or during the formation of the jelly roll structure.

[0298] Enumerated Embodiment 122. The method according to any of the enumerated embodiments 112 to 121, wherein at least one silicon-containing anode active material layer contains lithium in an amount of 2% to 50% with respect to the lithium energy storage capacity of the anode active material layer.

[0299] Enumerated Embodiment 123. A method for manufacturing a battery cell according to any of the enumerated embodiments 1 to 111, comprising: contacting the anode and the cathode with a pre-treated electrolyte; applying a voltage bias between the anode current collector and the cathode current collector to induce at least one electrochemical cycle in the pre-treated electrolyte to generate a pre-treated electrode structure; and contacting the pre-treated electrode structure with a non-aqueous lithium-ion electrolyte.

[0300] Enumerated Embodiment 124. The method according to Enumerated Embodiment 123, further comprising transferring the pre-treated electrode structure from an electrochemical pre-treatment housing containing the pre-treated electrolyte to the battery cell housing, and adding the non-aqueous lithium-ion electrolyte.

[0301] Enumerated Embodiment 125. The method according to Enumerated Embodiment 123, further comprising: placing the electrode assembly in the battery cell housing; adding the pre-treated electrolyte to the cell via an electrolyte injection port; removing at least a portion of the pre-treated electrolyte from the cell via an electrolyte discharge port after generating the pre-treated electrolyte structure; and adding the non-aqueous lithium-ion electrolyte to the cell via an electrolyte injection port.

[0302] Enumerated Embodiment 126. The method according to Enumerated Embodiment 125, wherein the electrolyte injection port and the electrolyte discharge port are the same port.

[0303] Enumerated Embodiment 127. The method according to any of the enumerated embodiments 123 to 126, wherein the at least one electrochemical cycle in the pretreatment electrolyte is carried out at a temperature of at least 40°C, or optionally in the range of 40°C to 100°C.

[0304] Enumerated Embodiment 128. The method according to any of the enumerated embodiments 123 to 127, further comprising bringing the pre-treated electrode structure into contact with the non-aqueous lithium-ion electrolyte, and then applying another voltage bias between the anode current collector and the cathode current collector to induce at least one electrochemical formation cycle in the non-aqueous lithium-ion electrolyte.

[0305] Enumerated Embodiment 129. A method for manufacturing a battery cell according to any of the enumerated embodiments 1 to 111, comprising applying a voltage bias between the anode current collector and the cathode current collector to induce at least one electrochemical formation cycle in the non-aqueous lithium-ion electrolyte, wherein the temperature of the non-aqueous lithium-ion electrolyte is at least 40°C, or optionally in the range of 40°C to 100°C.

[0306] Enumerated Embodiment 130. The method according to Enumerated Embodiment 129, further comprising releasing gas through pores in the battery cell housing during the at least one electrochemical formation cycle in the non-aqueous lithium-ion electrolyte.

[0307] Enumerated Embodiment 131. The method according to Enumerated Embodiment 130, further comprising closing the pores before cooling the non-aqueous lithium-ion electrolyte to below 40°C.

[0308] Enumerated Embodiment 132. A method for manufacturing a battery cell according to any of the enumerated embodiments 1 to 111, comprising: i) providing the battery cell in an unsealed state while maintaining the non-aqueous lithium-ion electrolyte at a high temperature of at least 40°C (or optionally 40 to 100°C); ii) sealing the battery cell; and iii) cooling the battery cell to below 40°C.

[0309] Enumerated Embodiment 133. A method for manufacturing a battery cell according to any of the enumerated embodiments 1 to 111, comprising: i) assembling the electrode assembly under normal pressure; ii) exhausting the internal gas through the port of the battery cell housing to reduce the pressure inside the housing; iii) partially filling the housing with the non-aqueous lithium-ion electrolyte; and iv) sealing the housing to lower the internal pressure of the housing to below normal pressure.

[0310] Enumerated Embodiment 134. A method for manufacturing a battery cell according to any of the enumerated embodiments 1 to 111, comprising subjecting the battery cell to one or more electrochemical formation cycles, wherein at least one cathode active material layer is compressible, and the thickness of the at least one cathode active material layer is reduced by at least 5%, or optionally at least 10%, due to the expansion of at least one silicon-containing anode active material.

[0311] Enumerated Embodiment 135. The method according to Enumerated Embodiment 134, wherein the at least one cathode active material layer is reversibly compressible.

[0312] Enumerated Embodiment 136. The method according to Enumerated Embodiment 134, wherein the at least one cathode active material layer is at least partially irreversibly compressible.

[0313] Enumerated Embodiment 137. The method according to any of the enumerated embodiments 134 to 136, wherein the at least one cathode active material layer has a lower electrical resistance after the one or more electrochemical formation cycles.

[0314] Enumerated Embodiment 138. The method according to any of the enumerated embodiments 134 to 137, wherein at least one separator comprises a ceramic material.

[0315] Enumerated Embodiment 139. A lithium-ion battery cell, An electrode assembly, a) an anode current collector comprising a first silicon-containing anode active material layer disposed on the first side of the anode current collector and a second silicon-containing anode active material layer disposed on the second side of the anode current collector, wherein at least one of the first silicon-containing anode active material layer and the second silicon-containing anode active material layer is deposited by a PVD or CVD process and contains at least 85 atomic percent silicon, and at least one anode, b) A cathode comprising a cathode current collector, a first cathode active material layer disposed on the first side of the cathode current collector, and a second cathode active material layer disposed on the second side of the cathode current collector, c) The electrode assembly comprising a solid electrolyte layer disposed between the first cathode active material layer and the first anode active material layer, The battery cell housing includes the electrode assembly, which includes a positive battery terminal for external connection to at least one cathode and a negative battery terminal for external connection to at least one anode. The aforementioned battery cell is i) A compressible outer liner disposed between the battery cell housing and the electrode assembly, ii) A compressible central element around which the electrode assembly is wrapped, iii) Compressible cathode active material layer, iv) Compressible current collector structure, or The lithium-ion battery cell comprising any combination of v)(i) to (iv).

[0316] Enumerated Embodiment 140. A lithium-ion battery cell, An electrode assembly, a) comprising an anode current collector and a first silicon-containing anode active material layer disposed on the first side of the anode current collector, wherein the first silicon-containing anode active material layer contains at least 85 atomic percent silicon, and b) The electrode assembly includes a cathode current collector and a compressible first cathode active material layer disposed on a first side of the cathode current collector, wherein the first side of the cathode current collector is adjacent to the first side of the anode current collector and the cathode active material layer is optionally compressible, A lithium ion-containing electrolyte is disposed between the anode and the cathode and in contact with the anode and the cathode. The battery cell housing includes an electrode assembly that includes a positive battery terminal electrically connected to the cathode and a negative battery terminal electrically connected to the anode, The lithium-ion battery cell wherein the first cathode active material layer is configured to be compressible to less than 95% of its thickness before at least one electrochemical charging event during at least one electrochemical charging event.

[0317] Enumerated Embodiment 141. The battery cell according to Enumerated Embodiment 140, wherein the first cathode active material layer is configured to be compressible to less than 85% of its thickness before at least one electrochemical charge event.

[0318] Enumerated Embodiment 142. The battery cell according to Enumerated Embodiment 140 or 141, wherein the at least one electrochemical charging event is an initial charging event performed as part of an electrochemical formation protocol.

[0319] Enumerated Embodiment 143. A battery cell according to any of the enumerated embodiments 140 to 142, wherein the first cathode active material layer is configured to have a thickness of 95% or less of the thickness before the at least one electrochemical charge event during a subsequent electrochemical discharge event.

[0320] Enumerated Embodiment 144. A battery according to any of the enumerated embodiments 144 to 142, wherein the at least one electrochemical charge event occurs during normal operation of the battery, and the first cathode active material layer is configured to recover to a thickness greater than 95% of its thickness before the at least one electrochemical charge event during a subsequent electrochemical discharge event.

[0321] Enumerated Embodiment 145. A battery cell according to any of the enumerated embodiments 140 to 144, wherein the first cathode active material layer has a thickness in the range of 40 to 200 μm prior to the at least one electrochemical charging event.

[0322] Enumerated Embodiment 146. A battery cell according to any of the enumerated embodiments 140 to 145, wherein the first cathode active material layer contains a lithium metal oxide compound.

[0323] Enumerated Embodiment 147. A battery cell according to any of the enumerated embodiments 140 to 145, wherein the first cathode active material layer comprises sulfur, selenium, or both sulfur and selenium.

[0324] Enumerated Embodiment 148. A battery cell according to any of the enumerated embodiments 140 to 147, wherein the at least one electrochemical charging event applies a pressure of 100 MPa or less to the first cathode active material layer.

[0325] Enumerated Embodiment 149. A battery cell according to any of the enumerated embodiments 140 to 148, wherein, prior to the at least one electrochemical charging event, the first cathode active material layer includes a first sublayer located proximal to the cathode current collector having a higher density than a second sublayer located distal to the cathode current collector.

[0326] Enumerated Embodiment 150. A battery cell according to any of the enumerated embodiments 140 to 149, wherein the first anode active material layer has a thickness in the range of 4 to 20 μm before the at least one electrochemical charge event and has a thickness in the range of 8 to 60 μm when charged in the at least one electrochemical charge event.

[0327] Enumerated Embodiment 151. A battery cell according to any of the enumerated embodiments 140 to 150, wherein the first anode active material layer comprises a quasi-stoichiometric nitride of silicon, and the N to Si ratio is in the range of 0.02 to 0.10.

[0328] Enumerated Embodiment 152. A battery cell according to any of the enumerated embodiments 140 to 151, wherein the first anode active material layer is deposited on the anode current collector by PECVD, CVD, or PVD.

[0329] Enumerated Embodiment 153. A battery cell according to any of the enumerated embodiments 140 to 152, wherein the anode current collector includes a metal foil and has a tensile strength R in the range of 500 to 1000 MPa. m The battery cell characterized by having the following features.

[0330] Enumerated Embodiment 154. A battery cell according to any of the enumerated embodiments 140 to 153, wherein at least one current collector includes a compressible current collector structure configured to be compressible to less than 90% of its thickness before the at least one electrochemical charging event, and the thickness before the at least one electrochemical charging event is in the range of 10 to 30 microns.

[0331] Enumerated Embodiment 155. The battery cell according to Enumerated Embodiment 154, wherein the compressible current collector structure includes a compressible core, a first conductive layer provided on the compressible core corresponding to the first side of the current collector, and a second conductive layer provided on the compressible core corresponding to the second side of the current collector.

[0332] Enumerated Embodiment 156. The battery cell according to Enumerated Embodiment 155, wherein the compressible core comprises an electrically insulating polymer.

[0333] Enumerated Embodiment 157. The battery cell according to Enumerated Embodiment 155, wherein the compressible core defines internal bubbles or voids, and the compressible core is electrically insulating.

[0334] Enumerated Embodiment 158. The battery cell according to Enumerated Embodiment 155, wherein the compressible core defines internal bubbles or voids, and the compressible core is electrically conductive.

[0335] Enumerated Embodiment 159. A battery cell according to any of the enumerated embodiments 154 to 158, wherein the compressible current collector structure is configured such that, during a subsequent electrochemical discharge event, its thickness is 95% or less of the thickness it had before the at least one electrochemical charge event.

[0336] Enumerated Embodiment 160. A battery cell according to any of the enumerated embodiments 154 to 158, wherein the compressible current collector structure is configured to recover to a thickness greater than 95% of the thickness before at least one electrochemical charge event during a subsequent electrochemical discharge event.

[0337] Enumerated Embodiment 161. A battery cell according to any of the enumerated embodiments 140 to 160, wherein the electrolyte is a solid electrolyte (SSE).

[0338] Enumerated Embodiment 162. The battery cell according to Enumerated Embodiment 161, wherein the SSE comprises a solid polymer electrolyte, a solid inorganic electrolyte, or a combination thereof.

[0339] Enumerated Embodiment 163. The battery cell according to Enumerated Embodiment 161 or 162, wherein the SSE comprises a solid sulfide electrolyte.

[0340] Enumerated Embodiment 164. A battery cell according to any of the enumerated embodiments 1 to 160, wherein the electrolyte is a non-aqueous solvent-based electrolyte.

[0341] Enumerated Embodiment 165. A battery cell according to any of the enumerated embodiments 140 to 164, wherein the electrode assembly further includes a first separator disposed between the first cathode active material layer and the first anode active material layer.

[0342] Enumerated Embodiment 166. The battery cell according to Enumerated Embodiment 165, wherein the first separator is configured to be compressible by at least 25% from its initial thickness during the at least one electrochemical charging event.

[0343] Enumerated Embodiment 167. The battery cell according to Enumerated Embodiment 165 or 166, wherein the first separator comprises a ceramic material.

[0344] Enumerated Embodiment 168. A battery cell according to any of the enumerated embodiments 140 to 167, The anode includes a second silicon-containing anode active material layer disposed on the second side of the anode current collector, The battery cell wherein the cathode includes a second cathode active material layer located on the second side of the cathode current collector, and the second side of the cathode current collector is distal to the first side of the anode current collector.

[0345] Enumerated Embodiment 169. The battery cell according to Enumerated Embodiment 168, wherein the electrode assembly further includes a second separator, and the cathode is disposed between the first separator and the second separator.

[0346] Enumerated Embodiment 170. The battery cell according to Enumerated Embodiment 169, wherein the electrode assembly includes a jelly roll structure or a stack structure.

[0347] Enumerated Embodiment 171. A battery cell according to the enumerated embodiment 169 or 170, In cross-section, the anode, the first separator, the cathode, and the second separator form a first subunit of the electrode assembly. The first subunit is one of a plurality of subunits, each subunit comprising its respective anode, its respective first separator, its respective cathode, and its respective second separator. The battery cell wherein the plurality of subunits are arranged in a stacked structure or a jelly roll structure.

[0348] Enumerated Embodiment 172. The lithium-ion battery according to Enumerated Embodiment 171, wherein the plurality of subunits comprises at least five subunits.

[0349] Enumerated Embodiment 173. A battery cell according to any of the enumerated embodiments 140 to 172, wherein the housing comprises a metal having a thickness in the range of 0.2 mm to 1.5 mm, and the battery cell further comprises a compressible liner disposed between at least a portion of the housing and the electrode assembly.

[0350] Enumerated Embodiment 174. The battery cell according to Enumerated Embodiment 173, wherein the compressible liner comprises an electrically insulating polymer having a bending yield strength of less than 10 MPa.

[0351] Enumerated Embodiment 175. A battery cell according to Enumerated Embodiment 173 or 174, wherein the housing includes a cylindrical or rectangular casing.

[0352] Enumerated Embodiment 176. A battery cell according to any of the enumerated embodiments 140 to 175, wherein the electrode assembly has a jelly roll structure, and the battery cell further includes a compressible central element around which the jelly roll structure is wound.

[0353] Enumerated Embodiment 177. The battery cell according to Enumerated Embodiment 176, wherein the compressible central element comprises an electrically insulating polymer having a bending yield strength of less than 10 MPa.

[0354] Enumerated Embodiment 178. A battery cell according to any of the enumerated embodiments 1 to 111 or 139 to 177, further comprising at least one compressible current collector, a compressible liner, or a compressible central element characterized by having a bending yield strength of less than 5 MPa.

[0355] Enumerated Embodiment 179. A method for manufacturing a battery cell according to any of the enumerated embodiments 139 to 178, comprising subjecting the battery cell to one or more electrochemical formation cycles, wherein the battery cell includes at least one compressible element.

[0356] Enumerated Embodiment 180. The method according to Enumerated Embodiment 179, wherein the at least one compressible element is i) A compressible outer liner disposed between the battery cell housing and the electrode assembly, ii) A compressible central element around which the electrode assembly is wrapped, iii) Compressible cathode active material layer, iv) Compressible current collector structure, or v) The method, wherein the separator is compressible.

[0357] Enumerated Embodiment 181. The method according to Enumerated Embodiment 180, wherein the battery cell comprises a combination of two or more compressible elements selected from (i) to (v).

[0358] Details of specific embodiments can be combined in any suitable manner without departing from the spirit and scope of the embodiments of the present invention. However, other embodiments of the present invention may be directed to specific embodiments relating to each individual aspect or to a particular combination of these individual aspects. The above description of exemplary embodiments of the present invention is presented for illustrative and explanatory purposes only. It is not intended to be exhaustive or to limit the invention to the exact forms described, and many modifications and variations are possible in light of the above teachings.

[0359] In the preceding description, various details were given for illustrative purposes to help understand the various embodiments of the present technology. However, as will be apparent to those skilled in the art, certain embodiments can be implemented without some of these details or with additional details. After describing several embodiments, those skilled in the art will recognize that various modifications, alternative configurations, and equivalents can be used without departing from the spirit of the invention. Furthermore, to avoid unnecessarily obscuring the invention, descriptions of some well-known processes and elements have been omitted. Moreover, details of any particular embodiment are not always present in variations of that embodiment and may be added to other embodiments. Where a range of values ​​is provided, it should be understood that each intermediate value between the upper and lower limits of that range, up to one-tenth of the lower limit, is also specifically disclosed unless the context explicitly indicates otherwise. The present invention includes, in each case, any stated value or intermediate value within the stated range and any other stated value or intermediate value within the stated range, each smaller range between them. These smaller upper and lower limits may or may not be included independently within this range, and each of these smaller ranges that includes either one of these limits, does not include any limits, or includes both of these limits is included in the present invention, subject to any specifically excluded limitations within this range. If a range includes one or both of the limits, a range that excludes one or both of the limits that it includes is also included.

[0360] As used herein and in the appended claims, the singular forms "a," "an," and "the" include plural references unless the context indicates otherwise. For example, a reference to "method" includes multiple such methods, and a reference to "the battery cell" includes one or more battery cells and their equivalents known to those skilled in the art. The present invention has been described in detail above for the purposes of clarity and understanding. However, it will be understood that certain changes and modifications may be made within the scope of the appended claims.

[0361] All publications, patents, and patent applications cited herein are incorporated herein by reference in their entirety for all purposes only. None of them are considered to be prior art.

Claims

1. Lithium-ion battery cell, An electrode assembly, a) An anode comprising an anode current collector and a first silicon-containing anode active material layer disposed on the first side of the anode current collector, wherein the first silicon-containing anode active material layer contains at least 85 atomic percent silicon, and the anode and b) The electrode assembly includes a cathode comprising a cathode current collector and a cathode comprising a compressible first cathode active material layer disposed on the first side of the cathode current collector, wherein the first side of the cathode current collector is adjacent to the first side of the anode current collector, A lithium ion-containing electrolyte is disposed between the anode and the cathode and in contact with the anode and the cathode. A battery cell housing for housing the electrode assembly and the electrolyte, wherein the housing includes a positive electrode battery terminal electrically connected to the cathode and a negative electrode battery terminal electrically connected to the anode, The lithium-ion battery cell wherein the first cathode active material layer is configured to be compressible to less than 95% of its thickness before at least one electrochemical charging event during at least one electrochemical charging event.

2. The battery cell according to claim 1, wherein the first cathode active material layer is configured to be compressible to less than 85% of its thickness before at least one electrochemical charge event.

3. The battery cell according to claim 1 or 2, wherein the at least one electrochemical charging event is an initial charging event performed as part of an electrochemical formation protocol.

4. The battery cell according to claim 3, wherein the first cathode active material layer is configured to have a thickness of 95% or less of the thickness before the at least one electrochemical charge event during a subsequent electrochemical discharge event.

5. The battery cell according to claim 1 or 2, wherein the at least one electrochemical charge event occurs during normal operation of the battery, and the first cathode active material layer is configured to recover to a thickness greater than 95% of its thickness before the at least one electrochemical charge event during a subsequent electrochemical discharge event.

6. The battery cell according to claim 1 or 2, wherein the first cathode active material layer has a thickness in the range of 40 to 200 μm prior to the at least one electrochemical charge event.

7. The battery cell according to claim 1 or 2, wherein the first cathode active material layer comprises a lithium metal oxide compound.

8. The battery cell according to claim 1 or 2, wherein the first cathode active material layer comprises sulfur, selenium, or both sulfur and selenium.

9. The battery cell according to claim 1 or 2, wherein the at least one electrochemical charging event applies a pressure of 100 MPa or less to the first cathode active material layer.

10. The battery cell according to claim 1 or 2, wherein, prior to at least one electrochemical charging event, the first cathode active material layer includes a first sublayer located proximal to the cathode current collector having a higher density than a second sublayer located distal to the cathode current collector.

11. The battery cell according to claim 1 or 2, wherein the first anode active material layer has a thickness in the range of 4 to 20 μm before the at least one electrochemical charge event and has a thickness in the range of 8 to 60 μm when charged in the at least one electrochemical charge event.

12. The battery cell according to claim 1 or 2, wherein the first anode active material layer comprises a quasi-stoichiometric nitride of silicon, and the N-to-Si ratio is in the range of 0.02 to 0.

10.

13. The battery cell according to claim 1 or 2, wherein the first anode active material layer is deposited on the anode current collector by PECVD, CVD, or PVD.

14. The anode current collector includes a metal foil and has a tensile strength R in the range of 500 to 1000 MPa. ｍ A battery cell according to claim 1 or 2, characterized by having the following features.

15. The battery cell according to claim 1 or 2, wherein at least one current collector includes a compressible current collector structure configured to be compressible to less than 90% of its thickness before the at least one electrochemical charging event, the thickness before the at least one electrochemical charging event being in the range of 10 to 30 microns.

16. The battery cell according to claim 15, wherein the compressible current collector structure includes a compressible core, a first conductive layer provided on the compressible core corresponding to the first side of the current collector, and a second conductive layer provided on the compressible core corresponding to the second side of the current collector.

17. The battery cell according to claim 16, wherein the compressible core comprises an electrically insulating polymer.

18. The battery cell according to claim 16, wherein the compressible core defines internal bubbles or voids, and the compressible core is electrically insulating.

19. The battery cell according to claim 16, wherein the compressible core defines internal bubbles or voids, and the compressible core is conductive.

20. The battery cell according to claim 15, wherein the compressible current collector structure is configured to have a thickness of 95% or less of the thickness before the at least one electrochemical charge event during a subsequent electrochemical discharge event.

21. The battery cell according to claim 15, wherein the compressible current collector structure is configured to recover to a thickness exceeding 95% of the thickness before at least one electrochemical charge event during a subsequent electrochemical discharge event.

22. The battery cell according to claim 1 or 2, wherein the electrolyte is a solid electrolyte (SSE).

23. The battery cell according to claim 22, wherein the SSE includes a solid polymer electrolyte, a solid inorganic electrolyte, or a combination thereof.

24. The battery cell according to claim 22, wherein the SSE comprises a solid sulfide electrolyte.

25. The battery cell according to claim 1 or 2, wherein the electrolyte is a non-aqueous solvent-based electrolyte.

26. The battery cell according to claim 1 or 2, wherein the electrode assembly further comprises a first separator disposed between the first cathode active material layer and the first anode active material layer.

27. The battery cell according to claim 26, wherein the first separator is configured to be compressible by at least 25% from its initial thickness during the at least one electrochemical charging event.

28. The battery cell according to claim 26, wherein the first separator comprises a ceramic material.

29. A battery cell according to claim 26, The anode includes a second silicon-containing anode active material layer disposed on the second side of the anode current collector, The battery cell wherein the cathode includes a second cathode active material layer disposed on the second side of the cathode current collector, and the second side of the cathode current collector is distal to the first side of the anode current collector.

30. The battery cell according to claim 29, wherein the electrode assembly further includes a second separator, and the cathode is disposed between the first separator and the first separator.

31. The battery cell according to claim 30, wherein the electrode assembly includes a jelly roll structure or a stack structure.

32. In cross-section, the anode, the first separator, the cathode, and the second separator form a first subunit of the electrode assembly. The first subunit is one of a plurality of subunits, and each subunit includes its respective anode, its respective first separator, its respective cathode, and its respective second separator. The battery cell according to claim 30, wherein the plurality of subunits are arranged in a stacked structure or a jelly roll structure.

33. The battery cell according to claim 32, wherein the plurality of subunits includes at least five subunits.

34. The battery cell according to claim 31, wherein the housing comprises a metal having a thickness in the range of 0.2 mm to 1.5 mm, and the battery cell further comprises a compressible liner disposed between at least a portion of the housing and the electrode assembly.

35. The battery cell according to claim 34, wherein the compressible liner comprises an electrically insulating polymer having a bending yield strength of less than 10 MPa.

36. The battery cell according to claim 34, wherein the housing includes a cylindrical or rectangular casing.

37. The battery cell according to claim 31, wherein the electrode assembly has a jelly roll structure, and the battery cell further includes a compressible central element around which the jelly roll structure is wound.

38. The battery cell according to claim 37, wherein the compressible central element comprises an electrically insulating polymer having a bending yield strength of less than 10 MPa.

39. The battery cell according to claim 22, wherein the housing comprises a metal having a thickness in the range of 0.2 mm to 1.5 mm, and the battery cell further comprises a compressible liner disposed between at least a portion of the housing and the electrode assembly.

40. The battery cell according to claim 39, wherein the compressible liner comprises an electrically insulating polymer having a bending yield strength of less than 10 MPa.

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