BATTERY CELLS HAVING NOTCHED ELECTRODES

Battery cells are presented that have notched electrodes. In one embodiment, the battery cells have a first notch in an electrode and a second notch in a seal. The second notch allows a first portion of the seal adjacent the first edge to fold without overlapping a second portion of the seal adjacent the second edge. The first notch serves as a relief zone that enables the seal to maintain a seal distance during folding. In another embodiment, the battery cells have a first notch in an electrode and a second notch in a portion of a separator. The first notch and the second notch, in combination, allow the separator to fold along a fold line without tearing. Other battery cells are presented.

FIELD

This disclosure relates generally to battery cells, and more particularly, to battery cells having notched electrodes.

BACKGROUND

Battery cells can utilize rectangular packaging shapes. However, these battery cells are often targeted for operating environments that do not offer mating pockets that are rectangular. As such, unused space may result when a rectangular battery cell occupies a pocket having a different shape, a different scale, or some combination thereof. Such unused space represents a wasted volume that otherwise could have been filled to increase a storage and delivery capacity of the battery cell.

In the battery industry, packaging shapes are being increasingly explored to increase pocket utilization within an operating environment (e.g., within portable electronics). Such increases may involve designing a non-rectangular packaging shape in view of a non-rectangular pocket, or vice versa. Design of the non-rectangular packaging shape may also involve changing a shape of electrodes within the battery cell to allow the non-rectangular packaging shape.

SUMMARY

In various aspects, the description is directed to battery cells having notched electrodes. In various embodiments, a battery cell includes an electrode having a first edge and a second edge. The first edge and the second edge meet at a virtual intersection. A first notch is in the electrode at an offset distance from the virtual intersection. The battery cell also includes a seal adjacent the first edge, the first notch, and the second edge. The seal has a fold line that is displaced a first seal distance from the first edge and displaced a second seal distance from the second edge. The first and second seal distances can be the same or different. Each offset distance of the fold line from the first edge and second edge can be equal to or greater than the seal distance. A second notch is in the seal opposite the first notch (and/or proximate to the virtual intersection) to create a relief for a first portion of the seal adjacent the first edge of the electrode to fold without overlapping a second portion of the seal adjacent the second edge of the electrode.

In some embodiments, the battery cell includes an electrode and a separator with a non-rectangular shape. The electrode has a first edge and a second edge that meet at a first virtual intersection. The battery cell also includes a first notch in the electrode at an offset distance from the first virtual intersection. A portion of a separator extends along the first edge, the first notch, and the second edge of the electrode and has a fold line. The portion of the separator and the fold line meet at, respectively, a second virtual intersection and a third virtual intersection. The battery cell additionally includes a second notch in the portion of the separator. The second notch encompasses at least the second virtual intersection and the third virtual intersection to create a relief in the portion of the separator extending along the first edge, the first notch and the second edge.

In some embodiments, the battery cell includes an electrode, a separator and a seal with a non-rectangular shape. The electrode has a first edge and a second edge that meet at a first virtual intersection. A first notch is in the electrode at an offset distance from the first virtual intersection. The offset distance is equal to or greater than the seal distance, thereby allowing the first notch to maintain the seal distance proximate to the first virtual intersection. The battery cell also includes a seal adjacent the first edge, the first notch, and the second edge. The seal has a seal fold line displaced at a first seal distance from the first edge and a second seal distance from the second edge. The battery cell additionally includes a second notch in the seal proximate to the first virtual intersection and opposite first notch. The second notch creates a relief to allow a first portion of the seal adjacent the first edge of the electrode to fold without overlapping a second portion of the seal adjacent the second edge of the electrode. Meanwhile, the separator has a portion that extends along the first edge, the first notch, and the second edge and has a separator fold line. The portion of the separator and the separator fold line meet at, respectively, a second virtual intersection and a third virtual intersection. A third notch is in the portion of the separator and encompasses at least the second virtual intersection and the third virtual intersection to create a relief in a portion of the separator.

Other battery cells having notched electrodes are presented.

DETAILED DESCRIPTION

In general, a battery cell utilizes a housing to enclose an electrode therein (among other components). The housing isolates the electrode from an ambient environment of the battery cell and commonly includes a seal. The seal (or a portion thereof) facilitates closure of the housing during manufacture, i.e., after the electrode has been disposed into the housing. The seal may run along a perimeter of the housing and may be formed into a flat seal or a flange seal. Protrusion of the seal from the housing is undesirable and subtracts from a volume that would otherwise be available to increase a power capacity of the battery cell. To reduce wasted volume, the seal—when formed into the flat seal or the flange seal—is subsequently folded. However, corners are often prevalent along the perimeter, especially for battery cells having a non-rectangular shape. These corners present challenges in maintaining integrity of the seal during folding. Such challenges may be addressed by forming a first notch in the electrode and a second notch in the seal proximate to such corners.

As used herein, the term “non-rectangular” refers to a perimeter having any number sides and corners that do not define a rectangular (or square) shape. The sides of the perimeter may be straight or curved. Moreover, the corners may include any combination of inner corners and outer corners. Inner corners are formed when adjacent sides of the perimeter meet at a juncture and have an angle exterior to the perimeter that is less than 180°. Outer corners are formed when adjacent sides of the perimeter meet at a juncture and have an angle exterior to the perimeter that is greater than 180°.

Now referring toFIGS. 1A & 1B, a schematic top view is presented of a portion of a battery cell100having an electrode102, in accordance with embodiments of this disclosure.FIGS. 1A & 1Bdepict the portion of the battery cell100in the context of, respectively, an outer corner and an inner corner. The electrode102has a first edge104and a second edge106that meet at a virtual intersection108. The virtual intersection108defines a juncture where the first edge104and the second edge106would meet if extended beyond their existing lengths to form a corner. InFIGS. 1A & 1B, such extensions (i.e., hypothetical extensions) are illustrated by dotted lines210. The first edge104and the second edge106may define a portion112of a perimeter that, when disposed in the battery cell100, abuts against a housing thereof.

A first notch114is in the electrode102at an offset distance116from the virtual intersection108. InFIGS. 1A & 1B, the first notch114is depicted as equidistant from the virtual intersection108at all points (i.e., equidistant by the offset distance116). However, this depiction is not intended as limiting. Other profiles are possible for the first notch114. In general, the first notch114may be shaped such that all points thereon are separated from the virtual intersection108by at least the offset distance116.

The battery cell100includes a seal118extending along the first edge104, the first notch114, and the second edge106. The seal118may be in a housing of the battery cell100and may be a flat seal (or flange seal). The seal118has a fold line120displaced at a first seal distance122afrom the first edge104, and a second seal distance122bfrom the second edge106. The offset distance116is equal to or greater than each of the first seal distance122aand the second seal distance122b.The first seal distance122aand the second seal distance122bcan be same to each other (as depicted), while in other embodiments, the first seal distance and the second seal distance can be different. InFIGS. 1A & 1B, the fold line120is depicted by a dashed line. First seal distance122aand/or second seal distance122bmay serve as a minimum seal distance around the portion112of the perimeter. In this capacity, first seal distance122aand/or second seal distance122bmay ensure integrity of the seal118during operation of the battery cell100. For example, and without limitation, seal distance122aand seal distance122bmay provide that the seal118resists swelling of the electrode102during cycles associated with charging and discharging of the battery cell100.

In some embodiments, an exclusion area is associated with the virtual intersection108. In these embodiments, the exclusion area encircles the virtual intersection108. The second notch124is prohibited from extending into the exclusion area. In some embodiments, the seal118is a flat seal formed into a pouch. In these embodiments, the electrode102is disposed into the pouch.

The battery cell also includes a second notch124in the seal118proximate the virtual intersection108and opposite the first notch114. A first portion126of the seal118is adjacent the first edge104and a second portion128of the seal is adjacent the second edge106. The second notch124creates a relief to allow a first portion126to fold without overlapping a second portion128. The second notch124may terminate a fold point130defined by a juncture of the fold line120. InFIG. 1A, the second notch124is depicted as having a “V-shape” with an apex that terminates at the fold point130. InFIG. 1Bthe second notch is depicted as a slit that terminates at the fold point130. However, these depictions are not intended as limiting. The second notch124may be any shape that maintains first seal distance122aand second seal distance122bwhile allowing the first portion126to fold without overlapping the second portion128. In some embodiments, the second notch124is defined by a border that includes the virtual intersection108. In further embodiments, the border includes an apex positioned at the virtual intersection108.

In operation, the first portion126and the second portion126are folded along the fold line120. Such folding may include folding towards, respectively, the first edge104and the second edge106. Other directions of folding, however, are possible. The second notch124enables the first portion124and the second portion126to fold independently of each other and without contact (i.e., without overlap). It will be appreciated that folding may generate stress within the seal118along the fold line120. Such stress may concentrate at the fold point130where the first portion124and the second portion126meet (e.g., at an apex of the second notch124). The first notch114allows the seal118to extend into an area created by the offset distance116. Thus, if stress during folding causes local failure of the seal118around the fold point130, the area is able to bridge continuity of the seal118along the portion112of the perimeter.

It will be appreciated that, in general, battery cells also include a separator disposed on an electrode, which may include the separator being interposed between two electrodes. Such interposing is also common within a stack of electrodes, which is typically formed by a sequence of layers that alternates between electrode and separator. In some embodiments, the electrode and the separator share a common outline or “footprint.” In some embodiments, the electrode and the separator share a common outline or “footprint,” but the separator is slightly larger in scale and therefore extends past the electrode. This extension generates a protrusion along the common outline. During manufacture, the protrusion of the separator is folded against the electrode to minimize a non-functional volume of the electrode stack. Adjacent inner corners, however, the separator lacks sufficient material to completely fold without tearing (i.e., due to a poor ability to stretch). To prevent tearing, the separator may involve a notch therein adjacent an inner corner. The notch in the separator is complemented by a corresponding notch in the electrode, which provides a relief against a tear propagating out of the notch in the separator.

Now referring toFIG. 2, a schematic top view is presented of a portion of a battery cell200having an electrode202and a separator204, in accordance with embodiments of this disclosure. The separator204may protrude past the electrode202. A non-limiting example of such protrusion is shown inFIG. 2. The electrode202is non-rectangular in shape and has a first edge206and a second edge208that meet at a first virtual intersection210. The first virtual intersection210defines a first juncture where the first edge206and the second edge208would meet if extended beyond their existing lengths to form a first corner. InFIG. 2, such (hypothetical) extensions are illustrated by dotted lines. The first edge206and the second edge208may define a portion212of a perimeter that, when disposed in the battery cell200, abuts against a housing thereof. In some embodiments, such as that shown inFIG. 2, the first virtual intersection210defines an inner corner214of the electrode202.

A first notch216is in the electrode202at an offset distance218from the first virtual intersection210. InFIG. 2, the first notch216is depicted as equidistant from the virtual intersection210at all points (i.e., equidistant by the offset distance218). However, this depiction is not intended as limiting. Other profiles are possible for the first notch216. In general, the first notch216may be shaped such that all points thereon are separated from the virtual intersection210by at least the offset distance218.

The separator204has a portion220extending along the first edge206, the first notch216, and the second edge208. The portion220has a fold line222, which inFIG. 2is depicted by a dashed line. The portion220of the separator204and the fold line222meet at, respectively, a second virtual intersection224and a third virtual intersection226. The second virtual intersection224defines a second juncture where adjacent edges of the separator204would meet if extended beyond their existing lengths to form a second corner. The third virtual intersection226defines a third juncture where adjacent fold lines222would meet if extended beyond their existing lengths to form a third corner. InFIG. 2, such extensions (i.e., hypothetical extensions) are illustrated by dotted lines. In some embodiments, the electrode202and the portion220of the separator204are disposed in a pouch.

A second notch228is in the portion220of the separator204and encompasses at least the second virtual intersection224and the third virtual intersection226. The second notch228may be a slit, a “V-shaped” notch, a “U-shaped” notch, or some other shape. InFIG. 2, the second notch228is depicted as the “U-shaped” notch. However, this depiction is for purposes of illustration only. In some embodiments, the second notch228encompasses the first virtual intersection210.

In operation, the portion220of the separator204is folded along the fold line222, which may include folding towards the electrode202. The second notch228enables adjacent portions of the separator204to fold independently of each other and without “pulling” on neighboring material (i.e., around the second virtual intersection224and the third virtual intersection226). Such independent folding may prevent tearing of the separator204. This benefit may be useful when the electrode202and the separator204are disposed into the housing of the battery cell200(e.g., when the portion212of the perimeter abuts against the housing). Other benefits, however, are possible.

It will be appreciated that embodiments described in relation toFIGS. 1A & 1Bcan be combined at a single corner with those described in relation toFIG. 2. According to an illustrative embodiment, a battery cell includes an electrode having a first edge and a second edge that meet at a first virtual intersection. A first notch is in the electrode at an offset distance from the first virtual intersection. The battery cell also includes a seal adjacent the first edge, the first notch, and the second edge. The seal has seal fold line displaced at a first seal distance from the first edge and a second seal distance from the second edge. The first and second seal distances can be the same or different. The offset distance is equal to or greater than the seal distance, thereby allowing the first notch to maintain the seal distance proximate to the first virtual intersection. The battery cell additionally includes a separator having a portion that extends along the first edge, the first notch, and the second edge. The portion has a separator fold line. The portion of the separator and the separator fold line meet at, respectively, a second virtual intersection and a third virtual intersection.

The battery cell additionally includes a second notch in the seal proximate to the first virtual intersection and opposite first notch. The second notch creates a relief to allow a first portion of the seal adjacent the first edge to fold without overlapping a second portion of the seal adjacent the second edge. A third notch is in the portion of the separator and encompasses at least the second virtual intersection and the third virtual intersection. It will be appreciated that the third notch creates a relief that allows the separator to fold along the separator fold line without tearing. By way of illustration, the relief allows for a portion of the separator extending along the first edge to fold independent of a portion extending along the second edge.

In some embodiments, the seal distance is not greater than 1 mm. In some embodiments, the seal distance is at least 0.5 μm. In some embodiments, the second notch comprises an apex positioned at the first virtual intersection. In some embodiments, the portion of the separator is folded along separator fold line. In further embodiments, the electrode and the portion of the separator are disposed into a housing of the battery cell. In some embodiments, the portion of the separator is folded along separator fold line and the seal is flat seal formed into a pouch. In these embodiments, the electrode and the portion of the separator are disposed into the pouch.

Now referring toFIG. 3, a perspective view is presented of a battery cell300having a non-rectangular housing302, in accordance with embodiments of this disclosure. The battery cell300includes inner corners304and outer corners306along a perimeter308of the non-rectangular housing302. A seal310extends along a portion of the perimeter308and is folded towards the non-rectangular housing302and terminals316extend from the housing302beyond the seal310to allow for electrical connections to the battery cell300. The terminals316can be can be a negative or positive tab. The battery cell300also includes an electrode stack disposed within the non-rectangular housing302(i.e., not shown). The electrode stack is formed of an alternating sequence of electrodes and separators, which may include electrode layers interposed by separator layers. Neighboring electrodes in the electrode stack may alternate between cathode functionality and anode functionality. The non-rectangular housing308conforms in shape to instances of a first notch310in the electrode stack (or electrode). Shapes associated with instances of the first notch310are depicted inFIG. 3for purposes of illustration only and are not intended as limiting. Other shapes are possible.

A seal312extends along a portion of the perimeter308and is folded towards the non-rectangular housing302. The seal312contains instances of a second notch314formed therein that enables folding of the seal312adjacent the inner corners304and the outer corners306. Instances of the first notch310and instances of second notch314function, in combination, to allow the seal312to fold while maintaining a seal distance adjacent the corners304,306. The electrode stack within the non-rectangular housing302may contain separators that protrude past neighboring electrodes. To enable folding of these separators, instances of a third notch (not shown) may be formed in the separators. Such instances may be adjacent the inner corners304and opposite instances of the first notch310in the electrode stack (or electrode). In combination, instances of the third notch and instances of the first notch310allow the separators to fold without tearing in a vicinity of the first corners304.

Now referring toFIG. 4, a side view is presented of a battery cell400having a single side fold, in accordance with embodiments of the disclosure. The battery cell includes housing402. A seal410extends along a portion of the perimeter408and is folded towards the non-rectangular housing402. More particularly, the seal410is a single side fold that is folded in an upwards direction. For example, as illustrated inFIG. 4, housing402may be a pouch having an upper portion402aand a lower portion402b.The upper portion402aand lower portion402bmay also include upper and lower extensions403aand403b,respectively. Upper and lower extensions403aand403baid in facilitating sealing of the pouch. To seal the pouch, upper portion402aand402binclude are joined along seal410. However after sealing, upper and lower extensions403aand403bcan extend beyond the perimeter408of housing402and be an unused space that represents wasted volume when battery cell400is incorporated into devices. To minimize the wasted volume within devices, the upper and lower extensions403aand403bare folded upwards to be adjacent a side402cof housing, thereby reducing protrusions from battery cell400, which eases the packaging constraints imposed by battery cell400. Folding of upper and lower extensions403aand403balso has the benefit of reducing manufacturing cost, as it reduces the need to trim or cut the extension.

In other embodiments, as illustrated inFIG. 5, the housing can have a double side fold.FIG. 5is a side view of a battery cell500having a double side fold, in accordance with embodiments of the disclosure. The battery cell includes housing502. A seal510extends along a portion of the perimeter508and is folded towards the non-rectangular housing502. More particularly, the housing508has a first portion folded in an upwards direction and then a second portion folded in a downwards directed to create a double side fold. For example, as illustrated inFIG. 5, housing502may be a pouch having an upper portion502aand a lower portion502b. The upper portion502aand lower portion502bmay also include upper and lower extensions503aand503b,respectively. Upper and lower extensions503aand503baid in facilitating sealing of the pouch. To seal the pouch, upper portion502aand502b,including extensions503aand503b,are joined along seal410. Like housing402, upper and lower extensions503aand503bcan extend beyond the perimeter508of housing502and be an unused space that represents wasted volume when battery cell500is incorporated into devices. Thus to minimize the wasted volume within devices, the upper and lower extensions503aand503bare folded to be adjacent a side502cof housing, thereby reducing protrusions from battery cell400.

Further, to enhance the durability of seal510, the upper and lower extensions503aand503bcan be folded twice to have a double fold. In other words, the upper and lower extensions503aand503bhave first portions513aand513b,respectively, that are folded in an upwards direction and second portions523aand523b,respectively, that extend for the first portions513aand513b,which is folded in a downwards direction creating elbow joint525, thereby reducing the chances the seal510will separate.

Now referring toFIG. 6, is a corner portion of a battery cell600having a corner geometry in accordance with embodiments of this disclosure. Corner606of battery600includes a radiused (i.e. rounded) portion606aand a chamfered portion612a(i.e., sloping surface at the corner). To create chamfered portion612a,the seal612can be cut along the edge612bof the corner, thereby facilitating folding of the seal at the outer corner.

Similar to seal118shown inFIG. 1A, a first portion626of the seal612is adjacent a first edge614and a second portion628of the seal is adjacent the second edge616. The chamfer creates a relief to allow the first portion626of the seal to fold without overlapping a second portion628. In operation, the first portion626and the second portion628are folded along a fold line620. Such folding may include folding towards, respectively, the first edge614and the second edge616. Other directions of folding, however, are possible.