Patent Description:
A rechargeable battery is a type of electrical battery which can be charged, discharged into a load, and recharged many times, while a non-rechargeable (or so-called primary battery) is supplied fully charged, and discarded once discharged. Rechargeable batteries are produced in many different shapes and sizes, ranging from button cells to megawatt systems connected to stabilize an electrical distribution network.

Rechargeable batteries initially cost more than disposable batteries, but have a much lower total cost of ownership and environmental impact, as rechargeable batteries can be recharged inexpensively many times before they need replacing. Some rechargeable battery types are available in the same sizes and voltages as disposable types, and can be used interchangeably with them. Despite the numerous rechargeable batteries that exist, there is a need for providing rechargeable batteries that have a high-capacity (i.e., a capacity of <NUM> mAh/gm or greater and exhibit high-performance. European Patent Application Publication Number <CIT> relates to an electrode for a rechargeable lithium battery. United States Patent Application Publication Number <CIT> discloses a monolithically integrated lithium thin film battery. United States Patent Application Publication Number <CIT> describes solid-state lithium batteries.

A high-capacity (i.e., a capacity of <NUM> mAh/gm or greater) and a high-performance rechargeable battery is provided by forming a rechargeable battery stack that includes a spalled material structure that includes a spalled cathode material layer that has a textured surface and a stressor layer that has a textured surface. An interface between the spalled cathode material layer and the stressor layer is planar. The spalled cathode material layer may include a single crystalline or polycrystalline cathode material. That spalled cathode material layer is typically devoid of polymeric binders. The stressor layer serves as a cathode current collector of the rechargeable battery stack. The textured surface of the spalled cathode material layer forms a large interface area between the cathode and electrolyte which is formed above the spalled cathode material layer. The large interface area between the cathode and the electrolyte reduces interface resistance within the rechargeable battery stack.

In one aspect of the present application, there is provided a method of forming a rechargeable battery stack according to claim <NUM>.

In another aspect of the present application, there is provided a rechargeable battery according to claim <NUM>.

The present application will now be described in greater detail by referring to the following discussion and drawings that accompany the present application. It is noted that the drawings of the present application are provided for illustrative purposes only and, as such, the drawings are not drawn to scale. It is also noted that like and corresponding elements are referred to by like reference numerals.

In the following description, numerous specific details are set forth, such as particular structures, components, materials, dimensions, processing steps and techniques, in order to provide an understanding of the various embodiments of the present application. However, it will be appreciated by one of ordinary skill in the art that the various embodiments of the present application may be practiced without these specific details. In other instances, well-known structures or processing steps have not been described in detail in order to avoid obscuring the present application.

It will be understood that when an element as a layer, region or substrate is referred to as being "on" or "over" another element, it can be directly on the other element or intervening elements may also be present. In contrast, when an element is referred to as being "directly on" or "directly over" another element, there are no intervening elements present. It will also be understood that when an element is referred to as being "beneath" or "under" another element, it can be directly beneath or under the other element, or intervening elements may be present. In contrast, when an element is referred to as being "directly beneath" or "directly under" another element, there are no intervening elements present.

Referring first to <FIG>, there is illustrated an exemplary structure of a cathode material substrate <NUM>. The cathode material substrate <NUM> has a uniform thickness across the entire length of the cathode material substrate <NUM>. Moreover, the topmost surface and the bottommost surface of the cathode material substrate <NUM> that can be employed are both planar across the entire length of the cathode material substrate <NUM>. Stated in other terms, the cathode material substrate <NUM> that is initially used in the present application has non-textured (i.e., planar or flat) surfaces. The term "non-textured surface" denotes a surface that is smooth and has a surface roughness on the order of less than <NUM> root mean square as measured by profilometry.

The cathode material substrate <NUM> that can be employed in one embodiment of the present application may comprise any cathode material of a rechargeable battery whose fracture toughness is less than that of the stressor material to be subsequently described. Fracture toughness is a property which describes the ability of a material containing a crack to resist fracture. Fracture toughness is denoted KIc. The subscript /c denotes mode I crack opening under a normal tensile stress perpendicular to the crack, and c signifies that it is a critical value. Mode I fracture toughness is typically the most important value because spalling mode fracture usually occurs at a location in the substrate where mode II stress (shearing) is zero, and mode III stress (tearing) is generally absent from the loading conditions. Fracture toughness is a quantitative way of expressing a material's resistance to brittle fracture when a crack is present.

In one embodiment of the present application, the cathode material that provides the cathode material substrate <NUM> is a lithiated material such as, for example, a lithium-based mixed oxide. Examples of lithium-based mixed oxides that may be employed as the cathode material substrate <NUM> include, but are not limited to, lithium cobalt oxide (LiCoO<NUM>), lithium nickel oxide (LiNiO<NUM>), lithium manganese oxide (LiMn<NUM>O<NUM>), lithium cobalt manganese oxide (LiCoMnO<NUM>), a lithium nickel manganese cobalt oxide (LiNixMnyCozO<NUM>), lithium vanadium pentoxide (LiV<NUM>O<NUM>) or lithium iron phosphate (LiFePO<NUM>). In another embodiment, the cathode material that provides the cathode material substrate is a not lithiated and can be any solid cathode material that meets the spalling criteria of brittleness and toughness as mentioned above.

In one embodiment, the cathode material substrate <NUM> is a single crystalline cathode material (i.e., a cathode material in which the crystal lattice of the entire sample is continuous and unbroken to the edges of the sample, with no grain boundaries). A cathode material substrate <NUM> that is composed of a single crystalline cathode material can be used to provide a cathode material layer of a battery material stack that exhibits fast cathode ion, e.g., Li ion, and electron transport. In another embodiment, the cathode material substrate <NUM> is a polycrystalline cathode material (i.e., a cathode material that is composed of many crystallites of varying size and orientation). Typically, the cathode material substrate <NUM> is devoid of any polymer binder material. Polymeric bonder free cathodes can provide a battery stack that exhibits robust operation without capacity degradation.

The cathode material substrate <NUM> may have a thickness greater than <NUM> (microns). Other thicknesses can also be used as the thickness of the cathode material substrate <NUM>.

In some embodiments of the present application, at least the topmost surface of the cathode material substrate <NUM> can be cleaned prior to further processing to remove surface oxides and/or other contaminants therefrom. In one embodiment of the present application, the cathode material substrate <NUM> is cleaned by applying a solvent such as, for example, acetone and isopropanol, which is capable of removing contaminates and/or surface oxides from the topmost surface of the cathode material substrate <NUM>.

In some embodiments of the present application, the topmost surface of the cathode material substrate <NUM> can be made hydrophobic by oxide removal prior to use by dipping the topmost surface of the cathode material substrate <NUM> into hydrofluoric acid. A hydrophobic, or non-oxide, surface provides improved adhesion between the cleaned surface and certain stressor materials to be deposited.

Referring now to <FIG>, there is illustrated the exemplary structure of <FIG> after patterning (i.e., texturing) a physically exposed surface (e.g., a topmost surface) of the cathode material substrate <NUM> to provide a first textured surface, TS1, to the cathode material substrate; the cathode material substrate having the textured surface can be referred to as textured cathode material substrate <NUM>. The surface roughness of the textured cathode material substrate <NUM> can be in a range from <NUM> root mean square to <NUM> root mean square as also measured by profilometry.

Patterning (i.e., texturing) can be performed by forming a plurality of etching masks (e.g., metal, insulator, or polymer) on the surface of a non-textured cathode material substrate <NUM>, etching the non-textured cathode material substrate <NUM> utilizing the plurality of masks as an etch mask, and then removing the etch masks. In some embodiments (and as shown in the drawings), the textured surface, TS1, of the textured cathode material substrate <NUM> is composed of a plurality of pyramids. In yet another embodiment (not shown), the textured surface, TS1, of the textured cathode material substrate <NUM> is composed of a plurality of cones. In some embodiments, a plurality of metallic masks are used, which may be formed by depositing a layer of a metallic material and then performing an anneal. During the anneal, the layer of metallic material melts and balls-ups such that de-wetting of the surface of the cathode material substrate <NUM> occurs. Details concerning the use of metallic masks in texturing a surface of a substrate can be found in co-pending and co-assigned <CIT>, the entire content of which is incorporated herein by reference.

Patterning (i.e., texturing) can be performed utilizing a grinding process.

Referring now to <FIG>, there is illustrated the exemplary structure of <FIG> after forming a stressor layer <NUM> on the textured surface, TS1, of the texture cathode material substrate <NUM>. The stressor layer <NUM> follows the contour of the textured cathode material substrate <NUM> and thus the stressor layer <NUM> has a first textured surface, TS3, and a second textured surface, TS4, which is opposite to the first textured surface, TS3.

The stressor layer <NUM> that can be employed in the present application includes any cathode-side electrode material that is under tensile stress on textured cathode material substrate <NUM> at a spalling temperature. As such, the stressor layer <NUM> can also be referred to herein as a stress-inducing layer; after spalling the stressor layer <NUM> that is attached to a spalled portion of the cathode material substrate will serve as a cathode current collector (i.e., cathode-side electrode) of a rechargeable battery stack. In accordance with the present application, the stressor layer <NUM> has a critical thickness and stress value that cause spalling mode fracture to occur within the textured cathode material substrate <NUM>. By "spalling mode fracture" it is meant that a crack is formed within textured cathode material substrate <NUM> and the combination of loading forces maintain a crack trajectory at a depth below the stressor/substrate interface. By critical condition, it is meant that for a given stressor material and base substrate material combination, a thickness value and a stressor value for the stressor layer is chosen that render spalling mode fracture possible (can produce a KI value greater than the KIC of the substrate).

The thickness of the stressor layer <NUM> is chosen to provide the desired fracture depth within the textured cathode material substrate <NUM>. For example, if the stressor layer <NUM> is chosen to be nickel (Ni), then fracture will occur at a depth below the stressor layer <NUM> roughly <NUM> to <NUM> times the Ni thickness. The stress value for the stressor layer <NUM> is then chosen to satisfy the critical condition for spalling mode fracture. This can be estimated by inverting the empirical equation given by t*=[(<NUM>×<NUM><NUM>)(KIC<NUM>/<NUM>)]/σ<NUM>, where t* is the critical stressor layer thickness (in microns), KIC is the fracture toughness (in units of MPa·m<NUM>/<NUM>) of the textured cathode material substrate <NUM> and σ is the stress value of the stressor layer (in MPa or megapascals). The above expression is a guide, in practice, spalling can occur at stress or thickness values up to <NUM>% less than that predicted by the above expression.

Illustrative examples of cathode electrode materials that are under tensile stress when applied to the textured cathode material substrate <NUM> and thus can be used as the stressor layer <NUM> include, but are not limited to, titanium (Ti), platinum (Pt), nickel (Ni), aluminum (Al) or titanium nitride (TiN). In one example, the stressor layer <NUM> includes a stack of, from bottom to top, titanium (Ti), platinum (Pt) and titanium (Ti). In one embodiment, the stressor layer <NUM> consists of Ni.

In one embodiment, the stressor layer <NUM> employed in the present disclosure can be formed at a first temperature which is at room temperature (<NUM>-<NUM>). The stressor layer <NUM> can be formed utilizing a deposition process that is well known to those skilled in the art including, for example, a physical vapor deposition process (e.g., sputtering or evaporation) or an electrochemical deposition process (e.g., electroplating or electroless plating).

In some embodiments of the preset application, the stressor layer <NUM> has a thickness of from <NUM> to <NUM>. Other thicknesses for the stressor layer <NUM> that are below and/or above the aforementioned thickness ranges can also be employed in the present disclosure.

In some embodiments of the present application, an adhesion layer can be formed directly on cathode material substrate prior to forming the stressor layer <NUM>. The adhesion layer is employed in embodiments in which the stressor layer to be subsequently formed has poor adhesion to the cathode material that provides the cathode material substrate. In some embodiments (not shown in this embodiment), a corrosion inhibitor layer can be formed directly on the cathode material substrate prior to forming the stressor layer <NUM>. In yet another embodiment (not shown in this embodiment, but shown in <FIG>), a stack of, from bottom to top, a corrosion inhibitor layer and an adhesion layer is formed directly on the cathode material substrate prior to forming the stressor layer <NUM>.

Each of the adhesion layer and the corrosion inhibitor layer follows the contour of the underlying cathode material. For example, if the cathode material substrate is textured as shown in <FIG>, both the adhesion layer and the corrosion inhibitor layer have textured first and second surfaces. If the cathode material substrate is non-textured, as shown in <FIG>, both the adhesion layer and the corrosion inhibitor layer have planar surfaces.

The adhesion layer that can be employed in some embodiments of the present application includes any metal adhesion material such as, but not limited to, titanium (Ti), tantalum (Ta), titanium nitride (TiN), tantalum nitride (TaN) or any combination thereof. The adhesion layer may comprise a single layer or it may include a multilayered structure comprising at least two layers of different metal adhesion materials.

The adhesion layer that can be employed in the present application can be formed at room temperature (<NUM>-<NUM>, i.e., <NUM> to <NUM>) or above. In one embodiment, the adhesion layer can be formed at a temperature which is from <NUM> (<NUM>) to <NUM> (<NUM>). In another embodiment, the adhesion layer can be formed at a temperature which is from <NUM> (<NUM>) to <NUM> (<NUM>). The adhesion layer, which may be optionally employed, can be formed utilizing a deposition technique such as, for example, sputtering or plating. When sputter deposition is employed, the sputter deposition process may further include an in-situ sputter clean process before the deposition.

When employed, the adhesion layer typically has a thickness from <NUM> to <NUM>, with a thickness from <NUM> to <NUM> being more typical. Other thicknesses for the adhesion layer that are below and/or above the aforementioned thickness ranges can also be employed in the present application.

The corrosion inhibitor layer includes any metal or metal alloy that is electrochemically stable with the cathode current collector (i.e., stressor layer) potential. For example, when Ni is employed as the cathode current collector (i.e., stressor) material, the corrosion inhibitor layer may be composed of aluminum (Al). The corrosion inhibitor layer may comprise a single layer or it may include a multilayered structure comprising at least two layers of corrosion inhibitor materials.

The corrosion inhibitor layer may have a thickness from <NUM> to <NUM>; although other thickness that are lesser than or greater than the aforementioned thickness range may also be employed. The corrosion inhibitor layer can be formed by a deposition process including, for example, chemical vapor deposition (CVD), plasmaenhanced chemical vapor deposition (PECVD), atomic layer deposition (ALD), or physical vapor deposition (PVD) techniques that may include evaporation and/or sputtering. The corrosion inhibitor layer may be formed within temperatures ranges mentioned above for the adhesion layer.

In accordance with the present application, the adhesion layer and/or the corrosion inhibitor layer is (are) formed at a temperature which does not effectuate spontaneous spalling to occur within the cathode material substrate (textured or non-textured). By "spontaneous" it is meant that the removal of a thin material layer from a substrate occurs without the need to employ any manual means to initiate crack formation and propagation for breaking apart the thin material layer from the base substrate. By "manual" it is meant that crack formation and propagation are explicit for breaking apart the thin material layer from the substrate.

In some embodiments (not shown in this embodiment, but shown in <FIG>), a handle substrate can be attached to a physically exposed surface of the stressor layer prior to spalling. The handle substrate may include any flexible material which has a minimum radius of curvature that is typically less than <NUM>. Illustrative examples of flexible materials that can be employed as the handle substrate include a polymeric tape, a metal foil or a polyimide foil. The handle substrate can be used to provide better fracture control and more versatility in handling the spalled portion of the cathode material substrate. Moreover, the handle substrate can be used to guide the crack propagation during spalling. The handle substrate is typically, but not necessarily, formed at a first temperature which is at room temperature (<NUM> - <NUM>).

The handle substrate typical has a thickness of from <NUM> to few mm, with a thickness of from <NUM> to <NUM> being more typical. Other thicknesses for the handle substrate that are below and/or above the aforementioned thickness ranges can also be employed in the present disclosure. In some embodiments, the handle substrate can be employed to the attached to the physically exposed surface of the stressor layer utilizing an adhesive material.

Referring now to <FIG>, there is illustrated the exemplary structure of <FIG> after performing a spontaneous spalling process (hereinafter just "spalling:"). Spalling is a controlled and scalable surface layer removal process in which a thin layer of a material is removed from a base substrate without utilizing an etching process or mechanical means. The spalling process transfers the original textured surfaces into a spalled surface of the material that is removed from the base substrate. By thin, it is meant that the removed layer thickness is typically less than <NUM>. In some embodiments, the spalled cathode material layer of the present application can have a thickness that is greater than <NUM> and less than <NUM>. In other embodiments, the spalled cathode material layer of the present application can have a thickness that is greater than <NUM> and less than <NUM>. In some embodiments, the spalled cathode material layer can have a thickness of less than <NUM>. In some embodiments, the controlled spalling process of the present application may be aided by pulling the handle substrate away from structure including the cathode material substrate and the stressor layer.

In the present application, the spalling process removes a portion of the cathode material from the cathode material substrate. The removed portion of the cathode material, which is still attached to the stressor layer, is referred to herein as spalled cathode material layer. The spalled cathode material layer contains at least one textured surface. The remaining portion of the textured cathode material substrate <NUM>, which is no longer attached to the stressor layer, is referred to herein as a cathode material substrate portion. The cathode material substrate portion can be reused in other applications. The spalled cathode material layer and the attached stressor layer (an optionally the adhesion layer and/or the optional corrosion inhibitor layer) may be referred to herein as a spalled material layer structure.

In the example illustrated in <FIG>, the spalled cathode material layer is designated as element <NUM>, while the remaining cathode material substrate portion is designated as element 12P. In the example illustrated in <FIG>, the spalled cathode material layer <NUM> has a first textured surface, TS1, and a second textured surface, TS2, that is opposite to the first textured surface, TS1, the cathode material substrate portion 12P also has a textured topmost surface. In this example, the spalled material layer structure includes a spalled cathode material layer <NUM> containing textured surfaces TS1 and TS2, and a stressor layer <NUM> containing textured surfaces, TS3 and TS4. The interface between the spalled cathode material layer <NUM> and the stressor layer <NUM> is textured in this embodiment of the present application.

Spalling can be initiated at room temperature or at a temperature that is less than room temperature. In one embodiment, spalling is performed at room temperature (i.e., <NUM> to <NUM>). In other embodiments, spalling is performed at a temperature less than <NUM>. In a further embodiment, spalling occurs at a temperature of <NUM> or less. In an even further embodiment, spalling occurs at a temperature of less than <NUM>. In still yet another embodiment, spalling occurs at a temperature from <NUM> to <NUM>. When a temperature that is less than room temperature is used, the less than room temperature spalling process can be achieved by cooling the structure down below room temperature utilizing any cooling means. For example, cooling can be achieved by placing the structure in a liquid nitrogen bath, a liquid helium bath, an ice bath, a dry ice bath, a supercritical fluid bath, or any cryogenic environment liquid or gas.

When spalling is performed at a temperature that is below room temperature, the spalled structure is returned to room temperature by allowing the spalled structure to slowly warm up to room temperature by allowing the same to stand at room temperature. Alternatively, the spalled structure can be heated up to room temperature utilizing any heating means. After spalling, the handle substrate can be removed from the spalled material layer structure. The handle substrate can be removed from the spalled material layer structure utilizing conventional techniques well known to those skilled in the art. For example, UV or heat treatment can be used to remove the handle substrate.

Referring now to <FIG>, there are shown various rechargeable battery stacks which include the spalled material structure (<NUM>/<NUM>) shown in <FIG>. Notably, the rechargeable battery stack shown in <FIG> includes a stressor layer <NUM> having textured first and second surfaces (TS3 and TS4) as the cathode current collector (i.e., cathode-side electrode), a spalled cathode material layer <NUM> having the textured first and second surfaces (TS1 and TS2), a first region 16A of an electrolyte, a separator <NUM>, a second region 16B of an electrolyte, an anode <NUM> and an anode current collector <NUM> (i.e., anode-side electrode). The rechargeable battery stack shown in <FIG> is similar to the one shown in <FIG> except that a single region <NUM> of electrolyte is present; no separator is used in the rechargeable battery shown in <FIG>. As is shown in <FIG>, the bottommost surface of the electrolyte, which forms an interface with the spalled cathode material layer <NUM>, follows the contour of the textured surface of the spalled cathode material layer <NUM>.

In providing the rechargeable battery stacks shown in <FIG>, the spalled material structure (<NUM>,<NUM>) shown in <FIG> is flipped such that the stressor layer <NUM> is located beneath the spalled cathode material layer <NUM> and then the other components of the rechargeable battery stacks are formed one atop the other above the spalled cathode material layer <NUM>.

The electrolyte that can be used in the present application may include any conventional electrolyte that can be used in a rechargeable battery. The electrolyte may be a liquid electrolyte, a solid-state electrolyte or a gel type electrolyte. In some embodiments, the solid-state electrolyte may be a polymer based material or an inorganic material. In other embodiments, the electrolyte is a solid-state electrolyte that includes a material that enables the conduction of lithium ions. Such materials may be electrically insulating or ionic conducting. Examples of materials that can be employed as the solid-state electrolyte include, but are not limited to, lithium phosphorus oxynitride (LiPON) or lithium phosphosilicate oxynitride (LiSiPON).

In embodiments in which a solid-state electrolyte layer is employed, the solid-state electrolyte may be formed utilizing a deposition process such as, sputtering, solution deposition or plating. In one embodiment, the solid-state electrolyte is formed by sputtering utilizing any conventional precursor source material. Sputtering may be performed in the presence of at least a nitrogen-containing ambient. Examples of nitrogen-containing ambients that can be employed include, but are not limited to, N<NUM>, NH<NUM>, NH<NUM>, NO, or NHx wherein x is between <NUM> and <NUM>. Mixtures of the aforementioned nitrogen-containing ambients can also be employed. In some embodiments, the nitrogen-containing ambient is used neat, i.e., non-diluted. In other embodiments, the nitrogen-containing ambient can be diluted with an inert gas such as, for example, helium (He), neon (Ne), argon (Ar) and mixtures thereof. The content of nitrogen (N<NUM>) within the nitrogen-containing ambient employed is typically from <NUM> % to <NUM>%, with a nitrogen content within the ambient from <NUM> % to <NUM> % being more typical.

The separator <NUM>, which is used in cases in which a liquid electrolyte is used, may include one or more of a flexible porous material, a gel, or a sheet that is composed of cellulose, cellophane, polyvinyl acetate (PVA), PVA/cellulous blends, polyethylene (PE), polypropylene (PP) or a mixture of PE and PP. The separator <NUM> may also be composed of inorganic insulating nano/microparticles.

The anode <NUM> may include any conventional anode material that is found in a rechargeable battery. In some embodiments, the anode <NUM> is composed of a lithium metal, a lithium-base alloy such as, for example, LixSi, or a lithium-based mixed oxide such as, for example, lithium titanium oxide (Li<NUM>TiO<NUM>). The anode <NUM> may also be composed of Si, graphite, or amorphous carbon.

In some embodiments, the anode <NUM> is formed prior to performing a charging/recharging process. In such an embodiment, the anode <NUM> can be formed utilizing a deposition process such as, for example, chemical vapor deposition (CVD), plasma enhanced chemical vapor deposition (PECVD), evaporation, sputtering or plating. In some embodiments, the anode <NUM> is a lithium accumulation region that is formed during a charging/recharging process. The anode <NUM> may have a thickness from <NUM> to <NUM>.

The anode current collector <NUM> (i.e., anode-side electrode) may include any metallic electrode material such as, for example, titanium (Ti), platinum (Pt), nickel (Ni), copper (Cu) or titanium nitride (TiN). In one example, the anode current collector <NUM> includes a stack of, from bottom to top, nickel (Ni) and copper (Cu). In one embodiment, the metallic electrode material that provides the anode current collector <NUM> may be the same as the metallic electrode material that provides the cathode current collector (i.e., stressor layer <NUM>). In another embodiment, the metallic electrode material that provides the anode current collector <NUM> may be different from the metallic electrode material that provides the cathode current collector The anode current collector <NUM> may be formed utilizing a deposition process such as, for example, chemical vapor deposition, sputtering or plating. The anode current collector may have a thickness from <NUM> to <NUM>.

Referring now to <FIG>, there are illustrated exemplary structures that can be used in providing a spalled material structure that can be used in providing a rechargeable battery stack according to an embodiment. Notably, <FIG> illustrates an exemplary structure that includes, from bottom to top, a cathode material substrate <NUM> and a stressor layer <NUM>, while <FIG> illustrates an exemplary structure that includes, from bottom to top, a cathode material substrate <NUM>, an adhesion layer <NUM>, a corrosion inhibitor layer <NUM>, and a stressor layer <NUM>.

In the exemplary structures shown in <FIG>, no texturing of the cathode material substrate <NUM> is performed prior to stressor layer <NUM> formation. Instead, the cathode material substrate <NUM> is non-textured and it has planar surfaces. Also, the stressor layer <NUM> shown in <FIG> as well as the adhesion layer <NUM>, and the corrosion inhibitor layer <NUM> of <FIG> have planar surfaces.

The cathode material substrate <NUM>, stressor layer <NUM>, adhesion layer <NUM>, and the corrosion inhibitor layer <NUM> of the embodiments illustrated in <FIG> have been previously described above in regard to the examples shown in <FIG> of the present application.

Referring now to <FIG>, there illustrated the exemplary structure of <FIG> after patterning (i.e., texturing) a physically exposed (i.e., topmost) surface of the stressor layer <NUM> to provide a textured surface, TS1, to the stressor layer <NUM>. The surface roughness of the textured stressor layer <NUM> can be in a range from <NUM> root mean square to <NUM> root mean square as also measured by profilometry. While patterning of the stressor layer <NUM> is shown for the exemplary structure illustrated in <FIG>, patterning of the stressor layer <NUM> shown for the exemplary structure illustrated in <FIG> may also be performed.

In some embodiments of the present application, patterning (i.e., texturing) can be performed by forming a plurality of etching masks (e.g., metal, insulator, or polymer) on the surface of a non-textured stressor layer <NUM>, etching the non-textured stressor layer <NUM> utilizing the plurality of masks as an etch mask, and then removing the etch masks. In some embodiments (and as shown in the drawings), the textured surface, TS1, of the textured stressor layer <NUM> is composed of a plurality of pyramids. In yet another embodiment (not shown), the textured surface, TS1, of the textured stressor layer <NUM> is composed of a plurality of cones. In some embodiments, a plurality of metallic masks are used, which may be formed by depositing a layer of a metallic material and then performing an anneal. During the anneal, the layer of metallic material melts and balls-ups such that de-wetting of the surface of the stressor layer <NUM> occurs. Details concerning the use of metallic masks in texturing a surface of a substrate can be found in co-pending and co-assigned <CIT>, the entire content of which is incorporated herein by reference.

In another embodiment of the present application, patterning (i.e., texturing) can be performed utilizing a grinding process.

In some embodiments, and as shown in <FIG>, a handle substrate <NUM>, as described above, can be attached to the stressor layer <NUM> prior to spalling.

Referring now to <FIG>, there is illustrated the exemplary structure of <FIG> after performing a spontaneous spalling process. Spalling is performed as defined above.

In the embodiment illustrated in <FIG>, the spalled cathode material layer is designated as element <NUM>, while the remaining cathode material substrate portion is designated as element 12P. In the embodiment illustrated in <FIG>, the spalled cathode material layer <NUM> has a textured surface, TS2; the cathode material substrate portion also has a textured surface, T3. In this embodiment, the spalled material layer structure includes a spalled cathode material layer <NUM> containing a textured surface, TS2, and a stressor layer <NUM> containing a textured surface, TS1. The interface between the spalled cathode material layer <NUM> and the stressor layer <NUM> is planar (i.e., non-textured) in this embodiment of the present application.

After spalling, and as mentioned above, the handle substrate <NUM> can be removed from the spalled material structure.

Referring now to <FIG>, there are shown various rechargeable battery stacks which include the spalled material structure (<NUM>/<NUM>) shown in <FIG>. Notably, the rechargeable battery stack shown in <FIG> includes a stressor layer <NUM> having a textured bottommost surface, TS1, as the cathode current collector (i.e., cathode-side electrode), a spalled cathode material layer <NUM> having a textured topmost surface, TS2, a first region 16A of an electrolyte, a separator <NUM>, a second region 16B of an electrolyte, an anode <NUM> and an anode current collector <NUM> (i.e., anode-side electrode). The rechargeable battery stack shown in <FIG> is similar to the one shown in <FIG> except that a single region <NUM> of electrolyte is present; no separator is used in the rechargeable battery shown in <FIG>. The electrolyte, separator <NUM>, anode <NUM> and anode current collector <NUM> (i.e., anode-side electrode) illustrated in used in providing the rechargeable battery stack shown in <FIG> are the same as defined above in the providing the rechargeable battery stack shown in <FIG>. As is the previous embodiment of the present application, the bottommost surface of the electrolyte, which forms and interface with the spalled cathode material layer <NUM>, follows the contour of the textured surface of the spalled cathode material layer <NUM>.

In providing the rechargeable battery stacks shown in <FIG>, the spalled material structure (<NUM>/<NUM>) shown in <FIG> is flipped such that the stressor layer <NUM> is located beneath the spalled cathode material layer <NUM> and then the other components of the rechargeable battery stacks are formed one atop the other above the spalled cathode material layer <NUM> utilizing the techniques and materials mentioned above for providing the rechargeable battery stacks shown in <FIG>.

It is noted that the rechargeable battery stacks according to proposed embodiment, as shown, for example, in <FIG> exhibit high-capacity, as defined above, and high-performance. Also, the rechargeable battery stacks of the present application have reduced interface resistance due to the texturing that is present in the spalled cathode material layer. Notably, a large area is provided between the spalled cathode material layer and the electrode.

Claim 1:
A method of forming a rechargeable battery stack, the method comprising:
providing a cathode material (<NUM>) substrate having a non-textured surface;
forming a stressor layer (<NUM>) on the non-textured surface of the cathode material substrate so that an interface between the cathode material substrate (<NUM>) and the stressor layer (<NUM>) is non-textured;
texturing a physically exposed surface of the stressor layer to provide a first textured surface (TS1) on the physically exposed surface of the stressor layer; and
performing a spalling process to remove a spalled cathode material layer from the cathode material substrate, wherein the spalled cathode material layer is attached to the stressor layer and includes a second textured surface (TS2) that is opposite the non-textured interface between the cathode material substrate (<NUM>) and the stressor layer (<NUM>).