Thin film battery assemblies

Solid-state battery structures and methods of manufacturing solid-state batteries, such as thin-film batteries, are disclosed. More particularly, embodiments relate to solid-state batteries having an intermediate adhesive layer between several electrochemical cells. In an embodiment, an anode current collector at least partially fills a notch in a periphery of the intermediate adhesive layer. Other embodiments are also described and claimed.

BACKGROUND

Field

Embodiments relate to electrochemical devices and methods of manufacturing electrochemical devices. More particularly, embodiments relate to solid-state electrochemical devices, including batteries, having an intermediate adhesive layer between several electrochemical cells.

Background Information

Solid-state batteries, such as thin-film batteries, are known to provide better form factors, cycle life, power capability, and safety, as compared to conventional battery technologies. Solid-state battery structures and manufacturing methods, however, may be further optimized to improve battery energy density.

Energy density of a solid-state battery compares the energy availability in electrochemical cells, or stacks of electrochemical cells in an electrochemical device, in relation to the device mass or volume. One factor that can affect energy density is a height of a cell stack. More particularly, energy density may be increased by reducing the space taken in a vertical (or height) direction by elements of the cell stack that do not contribute to power production.

SUMMARY

Embodiments of solid-state battery structures are disclosed. In an embodiment, an electrochemical device, such as a solid-state battery, includes an adhesive layer between a first electrochemical cell and a second electrochemical cell. The first electrochemical cell may have a first electrolyte layer between a first anode layer and a first cathode layer. The second electrochemical cell may have a second electrolyte layer between a second anode layer and a second cathode layer. The adhesive layer may include a gap or notch in (or at) its periphery. In one embodiment, there is an anode current collector between the first anode layer and the second anode layer that at least partially fills the gap in the adhesive layer. For example, the anode current collector may have a first portion that lies between the first anode layer and the second anode layer, and a second portion that is positioned outward of the peripheries of the first anode layer and the second anode layer. The peripheral portion of the anode current collector that lies between the anode layers may conform to and/or abut a portion of the periphery of the adhesive layer. In an embodiment, the adhesive layer and the anode current collector may have a same thickness between the first electrochemical cell and the second electrochemical cell. The adhesive layer may include a layer of pre-formed pressure sensitive adhesive that attaches to one or both of the anode layers of the two electrochemical cells; the pre-formed pressure sensitive adhesive layer may have one or more notches formed along its perimeter or edge that are at least partially filled by the anode current collector.

In an embodiment, a first electrochemical cell may have an electrically conductive sidewall along an outer edge of its first cathode layer. An anode current collector may extend outward or protrude from the first electrochemical cell beyond the electrically conductive sidewall such that a gap exists between the sidewall and the anode current collector. An insulator may be located on the anode current collector, within the gap between the anode current collector and the sidewall, to reduce the likelihood of electrical shorting between the anode current collector and the first cathode layer.

DETAILED DESCRIPTION

Embodiments describe structures and manufacturing methods for solid-state batteries, e.g., thin-film batteries. However, while some embodiments are described with specific regard to manufacturing processes or structures for integration within a solid-state battery, the embodiments are not so limited, and certain embodiments may also be applicable to other uses. For example, one or more of the embodiments described below may be used to manufacture other layered elements, such as silicon-based solar cells.

In various embodiments, description is made with reference to the figures. Certain embodiments may, however, be practiced without one or more of these specific details, or in combination with other known methods and configurations. In the following description, numerous specific details are set forth, such as specific configurations, dimensions, and processes, in order to provide a thorough understanding of the embodiments. In other instances, well-known processes and manufacturing techniques have not been described in particular detail in order to not unnecessarily obscure the description. Reference throughout this specification to “one embodiment,” “an embodiment,” or the like, means that a particular feature, structure, configuration, or characteristic described is included in at least one embodiment. Thus, the appearance of the phrase “one embodiment,” “an embodiment,” or the like, in various places throughout this specification are not necessarily referring to the same embodiment. Furthermore, the particular features, structures, configurations, or characteristics may be combined in any suitable manner in one or more embodiments.

In an aspect, an electrochemical device may include two electrochemical cells bonded together by an intermediate adhesive layer. The intermediate adhesive layer includes one or more gaps or notches in its periphery into which an anode current collector is placed, such that the anode layers of the stacked electrochemical cells (with which the intermediate adhesive layer is in contact) are placed in electrical contact with the anode current collector. The anode current collector and the adhesive layer may have essentially the same thickness to thereby uniformly separate the anode layers across the anode layer surface area. This may enable the adhesive layer and the anode current collector to be nested so as to more fully utilize device space in a z-direction and thus reduce z-height impact of the structure. The intermediate adhesive may be a pressure-sensitive adhesive to enable the electrochemical cells to be bonded firmly together without the need for curing or treatment steps.

Referring toFIG. 1, a side view of an electrochemical cell is shown in accordance with an embodiment. The electrochemical cell100may include an electrolyte layer108between an anode layer110and a cathode layer106. The cathode layer106may, for example, include LiCoO2, LiMn2O4, LiMnO2, LiNiO2, LiFePO4, LiVO2, or any mixture or chemical derivative thereof. The electrolyte layer108may facilitate ion transfer between the cathode layer106and the anode layer110. Accordingly, the electrolyte layer108may be a solid electrolyte, which may not contain any liquid components and may not require any binder or separator materials compounded into a solid thin film. For example, the electrolyte layer108may include lithium phosphorous oxynitride (LiPON) or other solid state thin-film electrolytes such as LiAlF4, Li3PO4doped Li4SiS4. The anode layer110may, for example, include lithium, lithium alloys, metals that can form solid solutions or chemical compounds with lithium, or a so-called lithium-ion compound that may be used as a negative anode material in lithium-based batteries, such as Li4Ti5O12.

In an embodiment, the cathode layer106may be electrically connected with a cathode current collector104, which may be an electrically conductive layer or a tab. Similarly, the anode layer110may be electrically connected with an anode current collector (not shown), which may be an electrically conductive layer or a tab. Optionally, one or more intermediate layers may be disposed between the cathode layer106or the anode layer110, and its respective current collector. For example, a barrier film layer102may separate the cathode layer106from the cathode current collector104. For example, the barrier film layer102may be in direct physical contact with both the cathode layer106and the cathode current collector104. The barrier film layer102may reduce the likelihood of contaminants and/or ions from diffusing between the cathode current collector104and the cathode layer106. Thus, the barrier film layer102may include materials that are poor conductors of ions, such as borides, carbides, diamond, diamond-like carbon, silicides, nitrides, phosphides, oxides, fluorides, chlorides, bromides, iodides, and compounds thereof. Alternatively, an additional intermediate layer, such as a substrate layer, may be disposed between the cathode layer106and the cathode current collector104. The substrate layer may, for example, provide electrical connectivity between the cathode layer106and the cathode current collector104and may also provide structural support, e.g., rigidity, to the electrochemical cell100. Accordingly, the substrate layer may include a metal foil or another electrically conductive layer.

In some instances, the electrochemically active layers of the cell may be formed on one side of a substrate layer, e.g., using material deposition techniques such as physical vapor deposition, and the cathode current collector104may be formed separately and physically coupled to another side of the substrate layer. In other instances, the electrochemically active layers of the cell may be formed on the substrate layer, and then the electrochemically active layers may be removed from the substrate layer and physically coupled to the separately formed cathode current collector104. In still other instances, the electrochemically active layers of the cell may be formed, e.g., physical vapor deposited, directly on the cathode current collector104. Thus, there are many different ways to create an electrochemical cell100having a plurality of electrochemically active layers.

The electrochemical cell100may be a thin film battery cell, whose layers are thin. For example, the cathode current collector104may have a thickness in a range of between 10 to 100 μm, e.g., 50 μm. The composite electrochemical cell100may have a total thickness in a range of between 13 to 300 μm. For example, the barrier film layer102, cathode layer106, electrolyte layer108, and anode layer110may combine to have a thickness in a range of between 3 to 290 μm, e.g., 25 μm.

Referring toFIG. 2, a side view of an electrochemical device is shown in accordance with an embodiment of the invention. A first electrochemical cell202and a second electrochemical cell204may be physically and/or electrically connected to form an electrochemical device200. Each electrochemical cell may include several layers as described above, e.g., a cathode current collector104, a cathode layer106, an electrolyte layer108, and an anode layer110. Respective anode layers110of the first electrochemical cell202and the second electrochemical cell204may be placed in electrical contact with each other, and located between the cathode layers106, to form a stack of at least two electrochemical cells202,204. In an embodiment, the electrochemical device200may include one or both of an anode current collector206or an adhesive layer208between the first electrochemical cell202and the second electrochemical cell204. The anode current collector206or adhesive layer208between the respective anode layers110may be directly contacted by both of the anode layers110. For example, the anode current collector206may placed in physical and/or electrical contact with one or both of the respective anode layers110of the first and second electrochemical cells202,204. Alternatively, there may be one or more intermediate layers between at least one of the anode layers110and the anode current collector206or the adhesive layer208. In an embodiment, the adhesive layer208physically couples the anode layers110to one another, i.e., a first side of the adhesive layer208, e.g., a top side, forms an adhesive bond with an anode layer110of the first electrochemical cell202, and a second side of the adhesive layer208, e.g., a bottom side, forms an adhesive bond with an anode layer110of the second electrochemical cell204.

In an embodiment, there are gaps, portals, or openings formed in at least a portion of the adhesive layer208to permit at least portions of the respective anode layers110of the first and second electrochemical cells202,204to reach through the adhesive layer208to make physical contact with one another. For example, a circular portal may be formed through adhesive layer208and located near a center of adhesive layer. The portal may pass through adhesive layer208perpendicular to a top side of the layer, i.e., may pass through a thickness of adhesive layer208. Accordingly, when adhesive layer208is placed between respective anode layers110, the material forming anode layers110may deform into and across the thickness of adhesive layer208within the portal until the anode layers make physical contact.

Referring toFIG. 3, an exploded view of an electrochemical device is shown in accordance with an embodiment. Separating first electrochemical cell202and second electrochemical cell204reveals the anode current collector206and the adhesive layer208. In an embodiment, the anode current collector206has a tab structure, e.g., a rectangular tab structure. The tab structure may, however, include any of a variety of different shapes, such as other polygonal shapes beside rectangular, circular or curvilinear outer perimeter shapes, etc. The anode current collector206may be formed from an electrically conductive material. For example, the anode current collector206may be a copper or nickel tab.

The adhesive layer208may include an adhesive that bonds the first electrochemical cell202to the second electrochemical cell204. The adhesive layer208may incorporate one or more adhesives that bond an anode layer110of the first electrochemical cell202to an anode layer110of the second electrochemical cell204when the adhesive is located between the anode layers110. More particularly, shear holding between the electrochemical cells may be provided by the adhesive layer208.

The adhesive layer208may incorporate one or more types of adhesives. For example, the adhesive layer may include pressure sensitive adhesive. Accordingly, the adhesive may be manufactured with either a liquid carrier or in a fully solid form. Suitable pressure sensitive adhesive materials may include an elastomer compounded with a suitable tackifier. For example, adhesive layer208may include a pressure sensitive adhesive having elastomers based on acrylics, styrene block copolymers, or vinyl ethers. These are only examples, however, and elastomers may be based on other materials, such as ethylene-vinyl acetate, nitriles, silicone rubbers, etc. The adhesive layer208may also include other adhesives, including drying adhesives, contact adhesives, hot adhesives, and/or reactive adhesives, instead of or in addition to pressure sensitive adhesive. Adhesive layer208may have several layers laminated together. For example, adhesive layer may include a central substrate layer between an upper layer having a first adhesive and a lower layer having a second adhesive.

In an embodiment, the adhesive layer208is electrically conductive, either via the adhesive materials incorporated in the adhesive layer208or conductive fillers added to the adhesives, to provide for electrical conductivity between the bonded components of the electrochemical device200, e.g., the anode layers110and/or an anode current collector206.

The adhesive used in the adhesive layer may be selected or designed to provide permanent bonding between the electrochemical cells202,204. However, the adhesive may also be selected or designed to provide removable bonding between the electrochemical cells. Accordingly, the adhesive may be designed to achieve any desired bond based on the product application.

In an embodiment, the adhesive layer208may be pre-formed, e.g., cured, prior to being applied to the electrochemical cells202,204. For example, the adhesive layer208may include a two-sided pressure sensitive adhesive that may be alternately bonded to the first electrochemical cell202and then to the second electrochemical cell204. Alternatively, the adhesive layer208may include a drying adhesive that may be deposited over a surface, e.g., an anode layer110, of the first electrochemical cell202, and then a surface, e.g., an anode layer110, of the second electrochemical cell204may be brought into contact with the exposed side of the adhesive before the adhesive dries. That is, the electrochemical cells202,204may be bonded together by applying a film of uncured adhesive between the cells and then curing the adhesive to create an adhesive bond. Other adhesives and adhesive curing techniques may be used to dispose the adhesive layer208between the electrochemical cells202,204.

The anode current collector206and the adhesive layer208may fill at least a portion of a space between respective anode layers110of the electrochemical cells202,204. For example, a portion of the anode current collector206may be located within a gap or notch308that is formed in a periphery of the adhesive layer208, to at least partially fill the space defined by the gap308(between respective anode layers110of the electrochemical cells202,204). The periphery of adhesive layer208may include a side surface of adhesive layer208, e.g., as in the sidewall of a flat film layer, that extends between an upper and lower planar surface of the layer around a perimeter of adhesive layer208. More particularly, the first portion302of anode current collector206may fill the space. That is, the first portion302may be considered to be that portion of anode current collector206that fills a portion of the gap308. The first portion302may lie between a first anode layer110and a second anode layer110of respective electrochemical cells202,204. Accordingly, the first portion302may be considered to be positioned inward of the peripheries of the anode layers110, as compared to a second portion306of anode current collector206, which is positioned outward of the peripheries.

The first portion302may be in electrical connection with both of the anode layers110. In an embodiment, an edge of the first portion302of the anode current collector206may be located adjacent to an edge or side of the adhesive layer208that resides within the gap, e.g., adjacent to a gap perimeter edge310. The gap perimeter edge310may be an edge or sidewall of the adhesive layer208that extends around and defines gap308. For example, in an embodiment having a rectangular gap308as shown inFIG. 3, the gap perimeter edge310may include the three sidewalls that are formed in adhesive layer208when a notch, i.e., gap308, is punched, cut, or otherwise formed in the adhesive layer208body. In an embodiment, spaces or voids may exist between the sides of the first portion302of the anode current collector206, i.e., the portion of anode current collector206within gap308, and the perimeter or edge310of the adhesive layer208within the gap308. In another embodiment, however, these spaces or voids may be reduced so that the gap308is essentially filled in its entirety with the first portion302of the anode current collector206. Said differently, in an embodiment, the first portion302may essentially abut a side of the adhesive layer208that defines the gap308, but in other embodiments, there may be some space between the first portion302and the side of the adhesive layer208.

In an embodiment, the space between first electrochemical cell202and second electrochemical cell204within the gap308may be fully occupied by the anode current collector206. To reduce or eliminate spaces or voids between the peripheries or sides of the first portion302of the anode current collector206and the gap308of the adhesive layer208, the first portion302and gap308may have respective shapes that complement each other. For example, a shape or profile of the first portion302may conform to a shape or profile of the gap308. In this way, the anode current collector206may mate or engage with the adhesive layer208to form a unified body. As an example, the anode current collector206may have a rectangular profile with the first portion302opposite the tab body from the second portion306. Second portion306may be that portion of anode current collector206that is positioned outward of the peripheries of the anode layers110. For example, while first portion302may be adjacent to and/or in contact with gap perimeter edge310, second portion306may be outward from and not in contact with gap perimeter edge310. A rectangular profile is provided by way of example, and the anode current collector206may have any shape that may be mated to a gap308in the adhesive layer208. The gap308may be a slot, a notch, or the like, formed in the adhesive layer208using known fabrication techniques, e.g., laser or mechanical machining operations. Alternatively, the adhesive layer208may be deposited over a cell surface, as described below, and thus, the gap308may be formed by masking, gating, or otherwise controlling the shape of a deposited adhesive used to form the adhesive layer208. In an embodiment, the gap308includes a shape similar or identical to the first portion302. For example, the gap308may have a generally rectangular shape with a width that matches a width of the anode current collector206. Thus, the anode current collector206may nest within the gap308with the first portion302filling at least a portion of the gap, e.g., with a perimeter or edge of the first portion302placed in contact with a perimeter or edge310of the gap308. Accordingly, when the anode current collector206is fit into the gap308of the adhesive layer208, the gap308may be entirely filled such that the anode current collector206and adhesive layer208form a unified body. Here, a unified body refers to a body that includes at least two portions (an anode current collector206and an adhesive layer208) that are contiguous with each other to form an external surface that is continuous at all points, e.g., even across the border at which the portions meet. Furthermore, with the anode current collector206nested within the gap308, i.e., either partially or fully filling the gap308between the electrochemical cells202,204, the second portion306of the anode current collector206may extend away or outward of a perimeter or side304of the adhesive layer208. In an embodiment, the second portion306of the anode current collector206may also extend away or outward of a perimeter, side, or edge of the electrochemical cells202,204.

In an embodiment, the adhesive layer208may include several gaps308between electrochemical cells202,204, and each of the gaps308may be partially or fully filled by a respective anode current collector206. For example, a first portion302of a first anode current collector206may fill at least a portion of a first gap308formed along perimeter or edge304of the adhesive layer208. Similarly, a first portion302of a second anode current collector206may fill at least a portion of a second gap308formed along the perimeter or edge304of the adhesive layer208. Accordingly, the first anode current collector206and the second anode current collector206may be used to make electrical connection to different external components, e.g., to external product circuitry or to another anode layer associated with a different electrochemical cell or device.

Referring toFIG. 4, a cross-sectional view, taken about line A-A ofFIG. 2, of an electrochemical device is shown in accordance with an embodiment. The first portion302of the tab206may physically contact an inward adhesive perimeter edge402. Similarly, lateral sides404along a perimeter of the first portion302of the anode current collector206may be in physical contact with a perimeter or side of the gap308within the adhesive layer208. Thus, essentially all of the perimeter or side of the adhesive layer208within gap308may be in contact with the anode current collector206to entirely fill the gap308. In an embodiment, the anode current collector tab206and the adhesive layer208may be co-punched to ensure that the adhesive layer208touches the edges of the anode current collector206over essentially all of the gap perimeter edge310. Physical contact between the adhesive layer208and the anode current collector206may create an adhesive bond between the adhesive layer208and the anode current collector206that retains the anode current collector206in position when tensile loads are applied that tend to pull away the parts during use. Thus, dislodgment of the anode current collector206from the electrochemical device200may be prevented by bonding together the edges of the anode current collector206and the sides of the adhesive layer208within the gap308.

In other embodiments, the anode current collector206may have a different shape, e.g., circular, square, or different polygonal shapes. The gap308in the adhesive layer208may have a mating shape, i.e., one that conforms to the periphery of the anode current collector206. For example, in an embodiment, the anode current collector206is circular and the gap308may be partially circular, e.g., semi-circular, with a same radius as the anode current collector206to allow a first portion302of the anode current collector206to nest within the gap308and a second portion306of the anode current collector206to extend away from or outward of a periphery of the adhesive layer208.

Regardless of the anode current collector206shape, the second portion306of the anode current collector206may be exposed away from the adhesive layer208and the underlying electrochemical cell, to allow for electrical contact to be made between the anode current collector206and other product circuitry. Furthermore, the anode current collector206may initially extend away from the electrochemical cell by an extension distance, e.g., 10 to 20 mm, and then be trimmed back such that the second portion306extends only, for example, 2 to 10 mm, from the outer edge of the electrochemical cell.

Referring toFIG. 5, a cross-sectional view, taken about line B-B ofFIG. 2, of an electrochemical device is shown in accordance with an embodiment. To further eliminate unused space between the electrochemical cells202,204and reduce z-height impact on the electrochemical device200, the anode current collector206and the adhesive layer208may have similar thicknesses in the z-direction. For example, a thickness502of the anode current collector206may be the same as the thickness502of the adhesive layer208. Thus, when the anode current collector206is nested within the gap308of the adhesive layer208, the resulting layer may have a consistent thickness502, and therefore, separation between respective anode layers110may be the same across the mating surfaces of the electrochemical cells202,204. More particularly, the anode layers110may each include respective anode surfaces510, e.g., the planar surfaces that face each other, and the anode surfaces510may be separated by the thickness502of the resulting layer. In an embodiment, the anode current collector206and the adhesive layer208may each have a thickness502in a range of between 5 to 25 μm. For example, both the anode current collector206and the adhesive layer208may have a thickness502of 10 μm. Accordingly, the facing surfaces of the anode layers110of the electrochemical cells202,204may be uniformly spaced apart from each other by a separation distance equal to the thickness502of the anode current collector206(across a first portion of the facing surfaces) and adhesive layer208(across a second portion of the facing surfaces).

Electrical shorting (or strictly speaking, electronic shorting) between layers of electrochemical cells202,204may be caused whenever electrical connection is made between the anode current collector206and other layers, e.g., cathode layer106. Such connection may be through direct contact between the anode current collector206and the other layer, e.g., when the anode current collector206is bent during use and contacts the other layer. In other cases, melting, reflowing, and redeposition of electrochemical cell layer materials may be caused by, e.g., laser cutting operations used during solid-state battery manufacturing, which can result in ejected slag forming a short circuit between cell layers. Thus, since an electrical short can disable an electrochemical cell and reduce performance of an electrochemical device, there may be a need to prevent electrical contact between the anode current collector206and other layers of the electrochemical cells202,204.

Referring toFIG. 6, a partial cross-sectional view of an electrochemical device having an insulated anode current collector is shown in accordance with an embodiment. In an embodiment, a laser cutting operation may eject slag that is redeposited as a slag layer602along a sidewall604of first electrochemical cell202and/or second electrochemical cell204. The slag layer602may extend from the cathode current collector104along an outer edge of the electrochemical cell, e.g., an outer edge of the cathode layer106, toward the anode current collector206. For example, the slag layer602may be material that is redeposited directly from the cathode current collector104, or it may be reflowed material from a substrate layer that is replaced by the cathode current collector104during fabrication of the electrochemical cell. Thus, the exposed surface of the slag layer602may form a sidewall604of an electrochemical cell of the assembled electrochemical device200. As a result, if an electrically conductive portion of the anode current collector206were to contact the slag layer602, a short may form between two or more layers of the electrochemical cell. In particular, when both the anode current collector206and the slag layer602are formed of conductive material, touching them together may cause an electrical short between the anode current collector206and the cathode layer106. Similarly, touching the anode current collector206and the slag layer602together may cause an electronic short between them. As described above, shorting may occur even in the absence of the slag layer602, and so, the slag layer602is being provided only as one example.

In an embodiment, the anode current collector206may include an insulator606over at least a portion of an exposed surface to reduce the likelihood of shorting with the slag layer602on the sidewall604, or any other layer, of the electrochemical cells202,204. For example, a region of anode current collector206exposed away from the anode layers110surface may be covered with an insulator606to reduce the likelihood of electrical shorting between the anode current collector206and another layer of the electrochemical device200. The insulator606may cover at least a portion of the anode current collector206to reduce the likelihood that slag layer602will touch the anode current collector206. Thus, the likelihood of electrical shorting in the electrochemical device200may also be reduced. The insulator606may include any number of insulating materials and may be applied to the anode current collector206in numerous manners. For example, the insulator606may be a parylene film that is chemical vapor deposited over the anode current collector206adjacent to the slag layer602and/or between the sidewalls604of the first and second electrochemical cells202,204. Alternatively, the insulator606may include a heat shrink tubing, e.g., a polyolefin heat shrink tube, which may be located over and shrunk around the anode current collector206. Furthermore, the insulator606may be an insulating tube, such as a polyimide tube, bonded over the anode current collector206at the appropriate location to reduce the likelihood of electrical shorting between the anode current collector206and the slag layer602and/or the cathode current collector104.

In an embodiment, a method of manufacturing an electrochemical device200having an intermediate adhesive layer208is provided. In an operation, a first electrochemical cell202and a second electrochemical cell204are formed. The cells may have equal footprints, e.g., square profiles, to allow them to be stacked without having an overlap of one cell edge beyond another cell edge. The cells may, however, also have different shapes and/or sizes.

In an operation, the adhesive layer208may be formed from a pressure sensitive adhesive, e.g., an electrically conductive pressure sensitive adhesive. For example, the adhesive layer208shape may be cut from a pressure sensitive adhesive film being carried on a carrier film. The gap308may be formed in the pressure sensitive adhesive film in a shape identical to at least a portion of the anode current collector206. For example, the gap308may be a slot or a notch formed through the adhesive film. In an operation, an exposed adhesive surface of the shaped pressure sensitive adhesive film may be pressed against an anode layer110of the first electrochemical cell202. The adhesive layer208perimeter may be aligned with a perimeter of the anode layer110to fully utilize the surface area of the adhesive layer208and the anode layer110. For example, in the case of a rectangular adhesive layer208and anode layers110as shown inFIG. 3, the sides of the rectangles may be aligned and the adhesive layer208and anode layers110may be centered with respect to each other along a same axis perpendicular to their planar surfaces. After applying light pressure, the carrier film may be peeled away from the adhesive layer208, leaving the adhesive layer208in place over the anode layer110of the first electrochemical cell202.

In an operation, the anode current collector206may be inserted into the gap308formed in the adhesive layer208. Contact may be made between the first portion302of the anode current collector206and an inward edge of the gap308to nest the anode current collector206within the adhesive layer208. The anode current collector206may contact the adhesive layer208with sufficient pressure to initiate an adhesive bond that retains the anode current collector206within the gap308.

In an operation, the second electrochemical cell204may be stacked on the first electrochemical cell202, with the anode layer110of the second electrochemical cell204contacting one or both of the exposed surface of the adhesive layer208and the portion of the anode current collector206that fills the gap308. Pressure may be applied to the cathode current collectors104and/or substrate layers of the electrochemical cells202,204to adhesively bond the adhesive layer208to the respective anode layers110. The bonding of the adhesive layer208to the anode layers110may physically connect the electrochemical cells202,204without the need for time-curing or ultraviolet light treatment. The anode current collector206may be trimmed to shorten the second portion306of the anode current collector206extending outward from the stacked electrochemical cells. For example, after bonding the adhesive layer208to the anode layers110, second portion306may initially extend outward of the peripheries of the anode layers110by a first distance, and then a blade, laser, etc. may be used to cut through the anode current collector206to shorten the second portion306such that it extends outward of the peripheries by a second distance less than the first distance. Thus, an electrochemical device having a stack of electrochemical cells bonded together by an intermediate adhesive layer and in electrical connection with an anode current collector may be formed.