Low Z-fold battery seal

A portable electronic device comprises an electromechanical module having an actuator for positioning a mechanical element between first and second positions, and a controller coupled to the electromechanical module. The controller is configured to detect a mechanical event coupling to the electromechanical module, select an actuation signal to position the mechanical element in a safe position between the first and second positions, and transmit the selected signal, such that the mechanical element is positioned in the safe position during the event.

BACKGROUND

This disclosure relates generally to portable electronic devices, and specifically to battery powered mobile devices. In particular, the disclosure relates to sealing structures for the battery assembly, as related to overall battery size, energy density and form factor.

Batteries come in a range of different architectures and forms, including traditional rod-and-tube (dry cell) and flat plate (flooded cell) designs, and more advanced “jelly roll” configurations in which the anode and cathode layers are laid down on opposite sides of a flat sheet or flexible substrate, coated with a liquid or gel electrolyte, and rolled up for insertion into a cylindrical battery case, which is then sealed at either end. In flat battery designs, the anode and cathode structure may be folded inside a low-profile casing or pouch, which is sealed along one or more opposite sides. Where the seal or “tail” structure is folded over the top of the battery, as in typical existing designs, it may increase battery height or thickness. Alternatively, where battery thickness is constrained, a tail structure folded over the top of the battery reduces the available volume for energy storage.

Battery configurations for portable electronics and mobile devices require a range of design tradeoffs, including size, weight, power consumption, manufacturability, durability and thermal loading. Each of these factors impacts overall storage capacity and energy density, as defined by the amount of useful energy that can be delivered per unit volume or mass. The battery form factor (or package shape) is also an important design consideration, particularly for compact portable and mobile devices where space is at a premium. At the same time, effective sealing and insulating mechanism are also required, in order to provide high energy density and service life with improved durability leakage prevention.

SUMMARY

Exemplary embodiments of the present disclosure include.

DETAILED DESCRIPTION

FIG. 1is a perspective view of battery assembly10with casing12and protective wrap or film14. Low z-fold seal structures16seal battery casing12to prevent leakage of electrolytes and other materials from the inside of battery assembly10, to inhibit moisture intrusion, and to reduce oxidation and corrosion of the anode and cathode surfaces.

In the particular configuration ofFIG. 1, battery assembly10has a substantially oblong or rectangular geometry or form factor, with width W defined between opposite sides18A and18B, and length L defined between opposite sides or ends19A and19B. Battery assembly10may also have a flat or substantially planar profile, with first and second major surfaces20A and20B separated by thickness T.

Length L, width W and thickness T define the form factor of battery assembly10, as installed in an electronic device. Length L and width W are measured along first or second major surface20A or20B, in the direction of (horizontal) axes x and y, excluding the thickness of protective wrapper or film14. Similarly, height or thickness T is measured between major surfaces20A and20B, along (vertical) axis z, also excluding protective wrapper14.

In low-profile or flat configurations of battery assembly10, thickness T is generally less than length L or width W, such that major surfaces20A and20B have substantially greater surface area than side and end surfaces18A,18B,19A and19B. Note, however, that the orientation of coordinate axes x, y, and z is arbitrary, and length L and width W may be interchanged, such that L≧W or W≧L. The designation of sides18A,18B and ends19A,19B is also arbitrary, and they may be interchanged without loss of generality.

Depending on application, low z-fold seal structures16may thus be provided along opposite sides18A and18B of battery case12, as shown inFIG. 1, or along opposite ends19A and19B. Alternatively, a single low z-fold seal16may be provided along a single side or end of battery assembly10, for example first side18A or first end19A, with casing12formed as a continuous structure along the opposite corresponding surface, for example second side18B or second end19B.

Connector22provides electrical (power) connections to battery assembly10, for example in a “pig tail” configuration with a connector board or manifold23coupled to battery assembly10via flex circuit24, as shown inFIG. 1. Flex circuit24accommodates a range of battery connection configurations and allows connector board23to be relocated away from battery casing12during wrapping and unwrapping of protective film14. Connector22also provides for a variety of different couplings to battery assembly10, for example along a side surface (e.g., side18A or18B) or an end surface (e.g., end19A or19B) of batter casing12, or at a corner interface (e.g., between side18A and end19A, as shown inFIG. 1).

Because low z-fold seal structures16are provided on the side surfaces of battery assembly10(e.g., sides18A and18B, or ends19A and19B), and do not extend onto or above major surfaces20A and20B, the z-dimension (thickness T) of battery assembly10is reduced, as compared to other designs, where the seal structure or “tail” is folded over the top of the battery. That is, where seal structure16is not folded over onto top surface20A or bottom surface20B of battery assembly10, thickness T is less than in other designs, in which the seal structure extends over a portion of the top or bottom surface. Thus, the reduced z-fold configuration ofFIG. 1provides a smaller overall battery design, as adaptable to a range of battery powered devices in which battery size is at a premium, including, but not limited to, portable electronics and mobile devices.

Where the total battery thickness is constrained, moreover, “fold-over” seal designs may decrease the available height (z-dimension) on the inside of the battery. Where the lateral dimensions (e.g., x and y) are held head steady, or where the lateral area is otherwise constrained, this leads to reduced interior battery volume, with a commensurate decrease in battery capacity. The reduced z-fold seal design ofFIG. 1, on the other hand, provides battery assembly10with a corresponding increase in the available interior battery volume, because the seal fold does not extend over the top or bottom of battery itself; that is, seal structure16does not extend over top surface20A or bottom surface20B of battery assembly10, as described above.

In applications where the battery form factor (or volume envelope) is constrained, therefore, or where there is a fixed available volume (for example, in the interior of an electronic device, where space is constrained), the interior volume of battery assembly10may be increased in height, as compared to other designs, by the amount that the “old” tail stuck up above or below the top or bottom surface of the battery. This low z-fold seal configuration, as shown inFIG. 1and as further described below, thus provides battery assembly10with an improved size envelope and higher potential energy density, based on an increase in the available interior height and volume, as compared to the exterior size envelope.

In applications with a fixed available height or thickness T, for example, low z-fold seals16increase the available interior volume of battery assembly10, providing higher net energy density and a greater power/weight (or power/size) ratio, as compared to other seal configurations that increase battery height and reduce interior volume. This is particularly relevant in low-profile battery assemblies10, where major surfaces20A and20B are substantially larger than side surfaces18A,18B,19A and19B, and where even modest increases or decreases in absolute thickness may correspond to substantially much higher relative changes in interior volume and available anode and cathode area, with commensurate impact on battery system performance.

Protective wrapper or film14is configured to cover and protect battery assembly10during shipping and storage, and to retain low z-fold seal structures16in a generally vertical orientation against side surfaces18A and18B; that is, substantially perpendicular to major surfaces20A and20B. Protective wrapper14is also configured to accommodate connector22during installation and removal, and to provide for barcode scanning and other functions during manufacture and assembly, as described below.

FIG. 2is a cross-sectional view of battery assembly10, taken along line2-2ofFIG. 1. First and second portions12A and12B of battery case12are formed about inner battery element28, which stores electrical energy and provides power. Casing portions12A and12B define the major surfaces of battery10, for example upper and lower surfaces20A and20B, as described above.

In rechargeable embodiments of battery12, battery element28may typically have a jelly roll electrode structure, with a “wet” liquid or gel electrolyte interspersed between anode and cathode layers laid down on opposite surfaces of a rolled of folded plate structure, for example using intercalated lithium electrode material. Alternatively, a parallel plate (flooded electrode) structure may be used, for example with an acid electrolyte, or a post (or rod) configuration with a “dry” or paste (e.g., alkaline) electrolyte. Other types of batteries, including solid-state batteries, may be employed.

At least one low z-fold seal16is provided to seal casing portions12A and12B about inner battery element28, for example along opposite sides18A and18B of battery assembly10, as shown inFIG. 2. Alternatively, a single low z-fold seal16may be provided, for example by forming casing12as a flat sheet and bending the sheet around interior battery assembly22, with low z-fold seal structure16on side18B and with a substantially continuous casing12along opposite side18A.

Battery casing12is typically formed of a laminated material, for example an aluminum or other metal core layer12A (see inset) with plastic, polymer or other insulating layers12B and12C on the opposite (e.g., interior and exterior) surfaces of core layer12A. Typically, core layer12A provides strength, durability and additional structural features, while layers12B and12C provide electrical insulation and chemical protection from caustic or corrosive components of battery element28, for example acid or alkali electrolytes.

Low z-fold seals16are formed in a laminar, folded configuration, for example by heat sealing or bonding top and bottom (laminated) battery casings12A and12B (dashed lines) together along first or second side18A or18B of battery assembly10. Insulating layer or sheet32may be provided to cover the exposed edge of seal16, for example using a polyimide insulator such as a KAPTON® sheet or film, as available from E. I. du Pont de Nemours and Company of Wilmington, Del.

The bonded, insulated (e.g., top and bottom) battery case portions12A and12B are then bent or folded upward along the end or side surface (e.g., side18B) of battery assembly10, in a substantially vertical orientation along the +z direction (that is, along the shortest dimension or thickness, T, of battery assembly10). Alternatively, seal structure16may be formed by bonding case portions12A and12B along the top surface of battery assembly10, and bending downward, in the −z direction.

Typically, polymer and similar insulating layers12B and12C may also provide a restoring bias to metal core layer12A, so that low z-fold seal structures16tend to migrate from a substantially vertical or perpendicular orientation to a more horizontal or parallel orientation, as defined with respect to major surfaces20A and20B of battery assembly10. This tendency is addressed by providing retention features to keep seal structures16in the substantially perpendicular orientation along the side of battery10during shipping and storage.

First, adhesive layer34may be provided to overcome the residual bias in battery case portions12A and12B, in order to bond seal structures16against sides18A and18B. Suitable materials for adhesive layer34include pressure sensitive adhesive (PSA) materials such as acrylics, rubber, acetate, nitrile and styrene compositions. Alternatively, other adhesive materials may be used, including, but not limited to, cyanoacrylate (CA) adhesives, epoxy resin adhesives, polymer cement materials, thermoplastics, urethane adhesives, and ultraviolet or heat-cured adhesive compounds.

Protective wrapper14may also be positioned about battery assembly10to protect during shipping, with overlapping layers14A and14B providing a compressive coupling to retain seal16in a substantially vertical orientation prior to installation. Alternatively, battery assembly10may be placed in a tray, shipping container or other device configured to provide a compressive coupling, as described below.

Protective wrapper14is typically formed of an insulating polymer such as a polyethylene terephthalate (PET) film, or another protective polymer wrap in sheet or film form. Low tack adhesive30may be provided to detachably retain wrapper14about battery casing12, so that wrapper14provides a compressive coupling along opposite sides18A and18B of battery assembly10. The compressive coupling prevents unfolding, and retains low z-fold seal structures16in a substantially perpendicular orientation with respect to first and second major surfaces20A and20B of battery10.

For example, wrapper14may be provided in two (or more) overlapping layers14A and14B, with a low-tack adhesive30forming a detachable bond therebetween. Alternatively, low-tack adhesive30may be absent, and layers14A and14B of protective wrapper14may be coupled with via surface forces, or a static interaction, or using a mechanical retainer.

FIG. 3is a perspective view of battery assembly10with protective wrapper14, in an alternate form factor embodiment. In this particular configuration, battery assembly10is approximately square, with length L substantially equal to or about the same as width W, for example within ten or twenty percent. Height or thickness T is substantially less than length L and width W, as described above (that is, T<<L and T<<W).

In the lengthwise wrapping configuration ofFIG. 3, protective wrapper14provides a compressive coupling for low z-fold seals16along ends19A and19B of battery assembly10. Protective wrapper14is sized with width W selected to cover most or substantially all of the top and bottom surfaces of battery assembly10, leaving sides18A and18B free, so that battery case12is uncovered or exposed in these regions.

As shown inFIG. 3, protective wrapper14may also be substantially transparent, or may include a substantially clear, transparent or see-through portion14C, in order to allow for barcode scanning and reading of other identifying indicia36on the outer surface (e.g., top or bottom surface) of battery assembly10, when film14is wrapped about battery cover12. Low tack adhesive30may also be provided in two or more separate layers30and31, for example with film-battery layer30to removably bond first (inner) layer14A of protective wrap or film14to cover12of battery assembly10, and film-film layer31to removable bond first (inner) layer14A and second (outer) layer14B of protective film14.

Low-tack adhesive layers30and31allow protective wrapper14to be attached to battery case12for shipping, as described above, providing compressive coupling to retain low x-fold seals16in a vertical orientation during shipping. Protective wrap or film14may also be wrapped about battery assembly10either in the lengthwise direction, as shown inFIG. 3, or in the widthwise direction, as described above with respect toFIGS. 1 and 2.

Where low-tack adhesive layers30and31are provided on either side of inner layer14A, protective wrapper14may be substantially reversible, and positionable for wrapping with either surface facing battery cover12. Alternatively, low-tack (battery-film) adhesive layer131may also be provided with substantially lower bonding strength than (film-film) adhesive layer30, in order to prevent discoloration or marring the outer surface of battery casing12. Battery-film adhesive layer14D may also be absent, with a static or frictional coupling between protective wrapper14and the outer surface of battery casing12.

Protective wrapper14is removable for installation, as described above, for example by pulling on tab38and unwrapping first and second layers14A and14B of protective wrapper14from battery cover12. Pull tab38may include a reduced-width portion in outer layer14A of protective wrapper14, as defined by one or more tapers40. Pull tab38may also be provided with color coding (e.g., red, yellow, blue, green, etc.), in order to provide a visual cue indicating the presence of protective wrapper14, and the location of pull tab38.

One or more additional cutouts or other edge features42may also be provided on first layer14B of protective wrapper14, adjacent battery cover12, in order to accommodate the pigtail or other connector22. Connector22may also be provided with connector cover44for additional protection during shipping, for example by attaching connector cover44to battery case12with protective wrapper14, or as a separately detachable element.

FIG. 4Ais a top perspective view of battery assembly10with protective wrapper14, in a width-wise wrapping configuration. In this configuration, protective wrapper14provides a compressive coupling to retain low z-fold seals16in a substantially vertical orientation along sides18A and18B of battery assembly10. Protective wrapper14is sized with length L selected to cover portions of, or substantially all of, the top and bottom surfaces of battery assembly10, along with first and second sides18A and18B. Ends19A and19B, however, may be free, with battery case12uncovered or exposed in these regions.

As shown inFIG. 4A, protective wrapper14may also be removed by pulling outer layer14B directly away from inner layer14A, and then unwrapping protective wrapper14from cover12of battery assembly10. Thus, no separate tab feature is necessary, and outer later14B may or may not be color coded, depending on application.

FIG. 4Bis a bottom perspective view of battery assembly10as shown inFIG. 4A, illustrating cutout feature42for a pigtail or other connector22. Cutout42is configured to space the edge of protective wrapper14from the connection point between connector22and battery assembly10, for example where flex circuit24couples to the corner interface of second side18B and first end19A, as shown inFIG. 4B.

Cutout feature42thus prevents interference with connector22during installation and removal of protective wrapper14. In particular, flex circuit24allows connector board23to be manipulated or positioned away from battery assembly10during installation of protective wrapper14, and cutout42allows connector board23to be repositioned along side18B of battery assembly10after installation of protective wrapper14, without interference between the edge of protective wrapper14and flex circuit24, or the other components of connector22.

Cutout feature42may also be configured as a scallop, divot, groove, slot, channel or depression along a portion of length L of wrapper14, with or without the particular corner structure ofFIG. 4B. Thus, cutout42is not limited to a step configuration, where width W decreases from feature42in the vicinity of connector22to the end of wrapper14, but also encompasses other designs. For example, cutout feature42may be formed only in a region of wrapper14that is adjacent to connector22. Further, width W of wrapper14may decrease in the vicinity of connector22to form cutout42, and then increase back to a nominal value or to a different value along the rest of length L or wrapper14. The wrapping configuration may also be either lengthwise or widthwise with respect to battery assembly10, as described above, and the designations of length L and width W can be reversed with respect the configuration of cutout feature42, along either side or edge of wrapper14, without loss of generality.

FIG. 5is a top perspective view of battery assembly10, positioned in shipping or storage tray46. Shipping tray46includes sides48A,48B and ends50A,50B having suitable tolerance with respect to length L and width W of corresponding sides18A,18B or ends19A,19B of battery casing12, in order to generate compressive coupling to retain one or more low z-fold seals16in a substantially vertical or perpendicular orientation with respect to the major surfaces of battery10. Unit46may also include a port, receptacle or similar feature52to accommodate connector22, for example with flex circuit24extending within side48A of shipping tray46, and connector board23extending through side48A at port feature52.

Tray46may be used in combination with protective wrapper14, in order to provide additional compressive retention for low z-fold seals16along one or more of sides18A,18B and ends19A,19B. Alternatively, battery assembly10may be placed in tray46without protective wrapper14, with the compressive coupling provided by selecting suitable tolerances for sides48A,48B and ends50A,50B with respect to the corresponding surfaces of battery10.

FIG. 6is a plan view of protective film wrapper14for battery assembly10. Wrapper14extends from first end52to second end54, within a perimeter defined by outer edge56. When wrapped about a battery, first end52of protective wrapper14typically forms first (inner) layer14A, and second end54forms second (outer layer)14B, as described above. The designations first and second, however, are merely arbitrary, and may be interchanged without loss of generality. In addition, protective wrapper14may be wrapped about the battery in either orientation or direction, depending on application.

One or more adhesive layers may be provided to detachably retain protective wrapper14, for example film-film detachable adhesive layer30or film-battery detachable adhesive layer31, or both. For example, low tack adhesive may be provided in one or more layers30and31, for example film-battery or film-film layers on one or both sides of protective wrapper or film14, in order to removably bond wrapper14to the battery assembly, or to removably bond different layers of wrapper14together, or to perform both functions. Alternatively, one or both of low tack adhesive layers30and31may be absent, or a different adhesive material may be used.

Transparent window14C (dashed line; transparent or translucent material) may also be provided to view the surface of the battery casing, e.g., for bar code scanning or for reading an identifier or indicia, as described above. Alternatively, wrapper14may be transparent or translucent over substantially all or over a substantial majority of its surface area, for example over substantially all or most of the top or bottom surface of the battery assembly, or both. Wrapper14may also be substantially transparent over substantially all of its surface area except where color coding and other indicia are provided, for example color-coding indicia58on tab portion38. Indicia58may provide a color coding to indicate the presence or location of tab feature38, or indicia58may provide other identifying information such as model, size, date or serial number, and indicia58be located anywhere on wrapper14, for example at first or second end52or54, or between ends52and54.

One or more taper features40may be provided to define pull tab portion38of protective wrapper14, for example in first end54, as shown inFIG. 6. In addition, one or more tapers, ports, slots, cutouts or other edge features42may also be provided to space edge56of protective wrapper14from the battery connector, for example to avoid interference during installation and removal, as described above. Cutouts42may be provided, for example, between first end52and second end54or wrapper14, as shown inFIG. 6, or in one or both of first end52and second end54, depending on the battery size, connector location and wrapping configuration. One or more cutouts42may further provide a “step” feature of reduced width extending to first or second end52or54of wrapper14, or a more localized region of reduced width between ends52and54, for example adjacent the connector when film14is wrapped about a battery assembly, as described above.

FIG. 7is a block diagram of method70for retaining low z-fold seals against the side of a battery assembly. Method70comprises forming a battery case (step71), bonding the battery case to form a seal (step72), bending the seal into a substantially perpendicular orientation (step73), and retaining the seal against the side of the battery (step74).

Forming the battery case (step71) comprises forming first and second portions of the case about a battery element. The first and second casing portions define first and second major surfaces of the battery, for example top and bottom surfaces. The sides of the battery extend between the first and second major surfaces.

Bonding the battery case (step72) comprises bonding the first and second casing portions together along a selected side, in order to form a seal structure. The bonding may be performed, for example, by heat treatment or thermal bonding, or using an adhesive or mechanical attachment.

Bending the seal (step73) comprises bending the seal into a substantially vertical or perpendicular orientation with respect to the first and second major surfaces of the battery. Thus, the seal structure is oriented substantially parallel to the selected side. The seal may also be provided with an insulating material such as a KAPTON® or polyimide sheet, in order to cover the exposed edge.

Retaining the seal (step74) comprises retaining the seal structure in the substantially perpendicular orientation with respect to the selected side. Retention may be accomplished, for example, by use of a contact adhesive, glue, epoxy or other adhesive material to bond the seal structure to the selected side.

Method70may also include wrapping the battery casing with a protective film (step75). The protective film forms a compressing coupling to retain the seal in the substantially perpendicular orientation along and against the selected side of the battery, so that the residual bias in the casing material is overcome, and the form factor of the battery is preserved.

Wrapping the battery casing may include positioning a cutout with respect to a connector on the battery, so that an edge of the protective film is spaced from the connector. The cutout is configured to avoid interference while repositioning the battery connector during installation and removal of the protective film.

Generally, the adhesive film remains in place for a substantial time during storage and shipment (step76), allowing the adhesive to set sufficiently to overcome any residual bias in the battery casing. Thus, the seal structure is retained against the selected side of the battery even after unwrapping the protective film (step77). As a result, the seal structure remains in the substantially perpendicular orientation during installation (step78) and use, for example in a portable electronic device or mobile phone.

The battery assembly may also be placed in a shipping tray or storage unit (step79). The storage unit maintains a tightly selected tolerance with respect to the battery casing, generating a compressive coupling to retain the seal structure against the selected side. The battery may be wrapped first, before placement into the shipping or storage tray, or the battery may be unwrapped, so that the storage unit provides the primary compressive coupling to retain the seal structure against the side of the battery while the adhesive sets.