JP2007512671A - Alkaline battery with planar housing - Google Patents

Abstract

An alkaline battery preferably having a cubical flat housing. Cell can have an anode comprising zinc and a cathode comprising MnO _2. The housing may have a relatively small overall thickness, typically between 5 and 10 mm. Battery contents are supplied through the open end of the housing, and an end cap assembly is inserted therein to seal the battery. There may be a gap between the separator and the cathode due to the additional electrolyte insertion. The end cap assembly preferably includes a grooved vent ventilation mechanism, which provides a threshold level of gas pressure within the battery typically about 250-800 psig (1724 × 10 ^{3 to} 5515 × 10 ³ Pascal gauge). It can be activated when it reaches. The battery has a supplemental venting mechanism, such as a laser welded area on the housing surface, which can be activated at higher pressure levels.

Description

  The present invention relates to an alkaline battery having a substantially planar outer housing. The present invention also relates to an alkaline battery having an anode containing zinc, a cathode containing manganese dioxide, and an electrolyte containing aqueous potassium hydroxide.

  Conventional alkaline electrochemical cells have an anode containing zinc and a cathode containing manganese dioxide. The battery is typically formed from a cylindrical outer housing. The new battery has an open circuit voltage (EMF) of about 1.5 volts and a typical average operating voltage (100-300 milliamps) between about 1.0 and 1.2 volts in the intermediate drain service. Initially, the cylindrical housing is formed with a closed end opposite the enlarged open end. After the battery contents are supplied, an end cap assembly comprising an insulating grommet and a negative terminal end cap is inserted into the housing open end. In order to crimp the housing edge on the insulating plug and provide a tight seal, the open end is closed by radially compressing the housing around the insulating plug. The insulating grommet electrically insulates the negative terminal cap from the battery housing. A portion of the battery housing at the opposite closed end forms a positive terminal.

  A problem associated with the design of various electrochemical cells, especially alkaline cells, is that when a battery continues to discharge beyond a certain point, usually near the point of complete consumption of the battery's useful capacity, the battery generates gas. There is a tendency to do. Electrochemical cells, particularly alkaline cells, conventionally comprise a rupturable diaphragm or rupturable membrane within the end cap assembly. A rupturable diaphragm or membrane may be formed in a plastic insulating member as described, for example, in US Pat. No. 3,617,386.

  The prior art discloses a rupturable vent diaphragm that is integrally formed as a thin-walled area within an insulating disk contained within an end cap assembly. Such vent membranes can be oriented to lie in a plane orthogonal to the longitudinal axis of the cell, for example, as shown in US Pat. No. 5,589,293, or they can be As shown in Japanese Patent No. 4,227,701, it can be oriented inclined with respect to the longitudinal axis of the battery. U.S. Pat. No. 6,127,062 discloses an insulating sealing disk and an integrally formed rupturable diaphragm that is oriented vertically, in other words, parallel to the central longitudinal axis of the cell. . When the gas pressure in the cell rises to a predetermined level, the membrane ruptures, thereby releasing the gas pressure to the external environment through the end cap.

  Other types of vents for relieving gas pressure in electrochemical cells have been disclosed in the prior art. One such vent is a receiptable rubber plug, which has been used effectively in connection with small planar rectangular rechargeable nickel metal hydride batteries. One such rechargeable battery with a receiptable rubber plug vent is a 7 / 5-F6 size rechargeable nickel metal hydride commercially available as battery type GP14M145 manufactured by Gold Peak Batteries (Hong Kong). It is a battery. The rubber plug is physically compressed so that it sits tightly within the angled opening in the cavity or seats on the end cap assembly of the battery. When the internal gas pressure of the battery reaches a predetermined level, the plug lifts away from its seat, thereby allowing gas to escape from the underlying opening. When the gas pressure in the battery returns to normal, the plug re-seats.

  Major alkaline electrochemical cells typically have electrolyte permeable separation of zinc anode activation material, alkaline electrolyte, manganese dioxide cathode activation material, and typically cellulose or cellulose derivatives and polyvinyl alcohol fibers. Including film. The anodic activation material can include, for example, zinc particles mixed with a conventional gelling agent and electrolyte, such as sodium carboxymethylcellulose or an acrylic acid copolymer. The gelling agent serves to bridge the zinc particles and maintain them in contact with each other. Typically, a conductive metal nail inserted into the anode activation material serves as the anode current collector, which is electrically connected to the negative terminal end cap. The electrolyte can be an aqueous solution of an alkali metal hydroxide such as potassium hydroxide, sodium hydroxide, or lithium hydroxide. The cathode typically includes particulate manganese dioxide as a conductive additive, typically an electrochemically activated material mixed with a graphite material, to increase conductivity. Optionally, small amounts of polymeric binders, such as polyethylene binders, and titanium-containing compounds and other additives can be added to the cathode.

  The manganese dioxide used in the cathode is preferably electrolytic manganese dioxide (EMD) produced by direct electrolysis of manganese sulfate and a bath of sulfuric acid. EMD is desirable because EMD has high density and high purity. The electrical conductivity (resistivity) of EMD is quite low. In order to improve the electrical conductivity between the individual manganese dioxide particles, a conductive material is added to the cathode mixture. Such conductive additives also improve the electrical conductivity between the manganese dioxide particles and the battery housing, which also acts as a cathode current collector in conventional cylindrical alkaline batteries. Suitable conductive additives may include conductive carbon powders such as, for example, graphite, graphite-like materials, carbon black including acetylene black. Preferably, the conductive material comprises flaky crystalline natural graphite or flaky crystalline synthetic graphite comprising expanded or exfoliated graphite or graphitic carbon nanofibers and mixtures thereof.

  Small sized rectangular rechargeable batteries are currently available and are used to power small electronic devices such as MP3 audio players and minidisc (MD) players. These batteries are typically in the form of cubes (straight parallelepipeds) that are somewhat smaller in size of chewing gum packs. As used herein, the term “cube” shall mean its normal geometric definition, ie, “parallelepiped”. For example, such a battery is, for example, a replaceable rechargeable nickel metal hydride (NiMH) size F6 or 7 / 5F6 size according to the standard size for such a battery as defined by the International Electrotechnical Commission (IEC). It can be in the form of a cube. The F6 size has a thickness of 6.0 mm, a width of 17.0 mm, and a length of 35.7 mm (no label). There is an F6 size version that can be as large as about 48.0 in length. The 7 / 5-F6 size has a thickness of 6.0 mm, a width of 17.0 mm, and a length of 67.3 mm. According to the IEC standard, the allowable deviation of the 7 / 5-F6 size is +0, −0.7 mm in thickness, +0, −1 mm in width, and +0, −1.5 mm in length. When used to power a small digital audio player such as an MP3 audio player or a mini-disc (MD) player, the average operating pressure of a F6 or 7 / 5F6NiMH rechargeable battery is about 1.1-1.4 volts. Typically between 1.12 volts.

  When used to power a minidisc (MD) player, the battery is depleted at a rate of about 200-250 milliamps. When used to power a digital audio MP3 player, the battery is typically depleted at a rate of about 100 milliamps.

  Small sized cubic (nickel parallelepiped) nickel metal hydride so that small alkaline size batteries can be used interchangeably with nickel metal hydride batteries to power small electronic devices such as minidiscs (MD) or MP3 players. It is desirable to have a small planar alkaline battery that is the same size and shape as the battery.

It is desirable to use a main (non-rechargeable) alkaline battery, preferably a zinc / MnO ₂ alkaline battery, instead of a small rectangular rechargeable battery, specifically a small sized rechargeable nickel metal hydride battery. .

However, a special problem associated with the design of rectangular (cubic) shaped main Zn / MnO ₂ alkaline batteries is that the electrodes tend to expand during battery discharge. During discharge, both the anode and cathode expand.

  For a given housing wall thickness, a rectangular battery housing can withstand a given increase in battery internal pressure (due to gasification and anode expansion) more than a cylindrical housing of comparable size and capacity. Absent. This is due to the circumferential stress (hoop stress) applied on a rectangular (cube) shaped housing, which is significantly higher than that applied on a similarly sized cylindrical housing for any given pressure and housing wall thickness. is there. By significantly increasing the wall thickness of the housing, bulging or expansion problems associated with rectangular batteries can be overcome. However, a significant increase in housing wall thickness can lead to a significant decrease in the capacity available for small overall thicknesses, eg, anode and cathode materials for rectangular cells with a thickness below about 10 mm. The added wall thickness increases the manufacturing cost of the battery. In this regard, it is desirable to keep the housing wall thickness less than about 0.50, and preferably less than about 0.47 mm.

  Thus, a small planar (non-rechargeable) alkaline battery such as an F6 or 7 / 5-F6 size battery that has a rectangular (cubic) shaped housing but the housing does not swell or expand significantly during normal battery use. It is desirable to design.

  It would be desirable to be able to use such a rectangular battery as a replacement for a planar rechargeable NiMH battery of the same size.

  The main feature of the present invention is mainly directed to an (non-rechargeable) alkaline battery that generates hydrogen gas after discharging, which battery is configured to discharge hydrogen gas when the gas pressure reaches a predetermined value. And an end cap assembly including a vent mechanism for escape from the air. The casing has at least one pair of opposing planar walls that run along the length of the cell.

  An end cap assembly is inserted into the open end of the casing and sealed by crimping or welding to close the casing. The casing edge is crimped on an insulating sealing member, typically nylon or polypropylene, at the open end and can be inserted into the open end, but the metal cover is casing to close the open end. It is preferable to perform laser welding. The alkaline battery may have a parallelepiped shape, but preferably has a cubic (rectangular parallelepiped) shape. Thus, the casing is preferably cubic in shape and does not have any integral cylindrical part. The alkaline battery desirably has an anode containing zinc and an aqueous alkaline electrolyte, preferably an aqueous solution of potassium hydroxide.

  The end cap assembly includes a vent mechanism and preferably a rectangular metal cover. The cover is used to close the open end of the casing after the battery-containing material is inserted into the casing. If an insulator or insulating sealing member is inserted between the edge of the cover and the casing edge and the casing edge is crimped onto the insulator, the metal cover forms the negative terminal of the battery Can do. Alternatively, the cover can be welded directly to the casing edge. If the cover is welded to the casing edge, a separate end cap insulated from the cover can be used in electrical communication with the anode to function as the negative terminal of the battery. The casing is positive and forms the positive terminal of the battery.

  In one feature, the metal cover is welded directly to the casing edge to close the open end of the casing, a plastic extender seal is laminated on the metal cover, and then the negative end plate is plastic. Laminated on the extender. In other features, a paper washer may be used in place of the plastic extender.

A cathode comprising MnO ₂ , preferably in the form of a plurality of compacted slabs or disks, is inserted. The cathode slab or disk is preferably rectangular and each has a central hollow core that runs through the thickness of the slab. The slabs are inserted so as to be stacked. The slab is aligned along the length of the cell so that its outer surface contacts the inner surface of the casing. The laminated cathode slab forms a central hollow core that runs along the longitudinal axis of the battery. The central hollow core in the laminated cathode slab forms an anode cavity. The inner surface of each cathode slab that defines a central hollow core (anode cavity) within the slab is preferably a curved surface. Such a curved inner surface improves the mechanical strength of the slab during transfer and processing and provides a more uniform contact between the electrolyte permeable separator and the cathode. The separator is inserted into the central hollow core (anode cavity) of the battery so that the outer surface of the separator contacts and is in intimate contact with the inner surface of the cathode. An anode slurry containing zinc particles is inserted into an anode cavity with a separator that provides the interface between the anode and the cathode. The end cap assembly has an elongated anode current collector that is inserted into the anode slurry and is in electrical communication with the negative terminal of the battery. The end cap assembly has an insulating sealing member that insulates such an anode current collector from the outer casing of the cell.

  The anode cavity preferably has an elongated or oval structure when the anode cavity is viewed in a plane after taking a cross section of the cathode slab along a plane orthogonal to the longitudinal axis of the cell. The outer casing (housing) is desirably steel, preferably nickel plated steel. The casing wall thickness is desirably between about 0.30 and 0.50 mm, typically between about 0.30 and 0.45 mm, preferably between about 0.30 and 0.40 mm, more desirably about It is between 0.35 and 0.40.

In one aspect, a reusable or re-activatable vent, preferably a receiptable plug vent mechanism may be used as the main vent mechanism. Receiptable plugs are between about 100-300 psig (689.5 × 10 ^{3 to} 2069 × 10 ³ Pascal gauge), preferably about 100-200 psig (689.5 × 10 ^{3 to} 1379 × 10 ³ Pascal gauge). It is preferably designed to activate when the internal gas pressure of the cell in between reaches the threshold level pressure P1.

In other features, the main vent mechanism includes another spaced groove vent, preferably a single continuous groove vent (cast vent) that includes at least one stamped or engraved area on the casing surface. Can be used as The groove vent is punched into the casing surface and cut so that the thin region located below ruptures at a pressure P1 between about 250-800 psig (1724.5 × 10 ^{3 to} 5515 × 10 ³ Pascal gauge) Alternatively, it can be engraved. With such a design, the receiptable plug can be removed. Preferably, the groove vent is positioned near the closed end of the casing near the positive terminal. The groove boundary can be closed or opened. The groove may be straight or substantially straight, preferably parallel to the casing edge. The groove width is typically small, for example, less than about 1 mm. However, the term “groove” or “groove vent” as used herein is not intended to be limited to any particular width or shape, but rather the gas pressure in the battery reaches the target threshold level. It includes any recess in the cell casing that results in a thin material region located below that is sometimes expected to crack or rupture. As a non-limiting example, a 7 / 5-F6 size rectangular cell has a groove vent located on the wide side of the casing and parallel to the wide edge, preferably near the closed end of the casing. There can be a plurality of such groove vents, but only a single groove vent on the wide side of the casing, about 8 mm in length, and about 5-10 mm from the closed end of the casing. It is desirable.

In such a feature of the present invention, the groove vent, under which the thin-walled material is located, is a design explosion pressure between about 250-800 psig (1724 × 10 ^{3 to} 5515 × 10 ³ Pascal gauge) in the battery. It can be designed to rupture when P1 is reached. To achieve such a range in explosion pressure between about 250-800 psig (1724 × 10 ^{3 to} 5515 × 10 ³ Pascal gauge), the groove in which the thin-walled material is located is about 0.04-0. It may have a thickness between 15 mm. Alternatively, the groove vents under which the thin-walled material is located are preferably between about 400 to 800 psig (2758 × 10 ^{3 to} 5515 × 10 ³ Pascal gauge), preferably about 400 to 600 psig (2758). It may be designed to rupture when × reaching design explosion pressure between ^{10 3 ~4136} × ¹⁰ 3 Pascals gauge). In order to achieve a burst pressure between 400 and 800 psig (2758 × 10 ^{3 to} 5515 × 10 ³ Pascal gauge), the groove under which the thin material is located is between about 0.07 and 0.15 mm thick. Can have.

  Groove vents can be created by stamping the casing surface with a mold, preferably a mold having a cutting knife edge. The mandrel is held against the inner surface of the casing when the punching die precedes the outer surface of the casing. The groove can be conveniently cut into a V shape having an isometric side or a V shape having an unequal length side. In the former case, the sides forming the V-shaped grooves desirably form an acute angle of about 40 degrees, in the latter case they preferably form an angle between 10 and 30 degrees.

  There may be a supplemental ventilation system that includes one or more laser welds that secure the metal cover to the casing along with the groove vent. Such a weld may consist of one or both of a weak weld and a strong weld that may be designed to burst at a pressure higher than the burst pressure P1 of the groove vent located below the thin wall region. Such laser welding is done using an Nd: Yag laser.

In a feature of the invention, there can be only one laser weld, ie a strong weld that secures the entire periphery of the metal cover to the casing. A strong weld is under catastrophic conditions, for example if the battery is under a very high current or gas generation in the battery between about 800 psig to 2500 psig (5515 × 10 ^{3 to} 17235 × 10 ³ Pascal gauge). It can function as a supplemental ventilation system designed to rupture if inadvertently exposed to charging under extremely tampering conditions that rapidly increase to a level.

Thus, in a preferred feature, there is at least a single groove vent punched or cut on the battery casing. The single groove vent function serves as the battery's primary vent mechanism, in which case the groove under which the thin material is located is approximately 250 to 800 psig (1724 × 10 ^{3 to} 5515 × 10) of gas in the cell. ³ Pascal Gauge), more typically designed to rupture if it rises to a level between about 400 and 800 psig (2758 × 10 ^{3 to} 5515 × 10 ³ Pascal Gauge). And there is a combination of supplemental ventilation systems that include a strong laser weld that secures the edge of the metal cover to the casing. Such strong laser welds crack or rupture in catastrophic situations where the gas in the battery rapidly rises to a level between about 800 psig to 2500 psig (5515 × 10 ^{3 to} 17235 × 10 ³ Pascal gauge). Designed to do. In such a case, the gas in the battery quickly escapes through the burst and the internal pressure of the battery immediately returns to normal levels.

In a feature of the invention, the battery is balanced so that the cathode is exceeded. Preferably, the cell is MnO divided by the milliamp-hour capacity of zinc (based on a theoretical ratio of 820 milliamps-hour zinc per gram) (based on a theoretical ratio of 370 milliamp-hours of MnO ₂ per gram). The ratio of the theoretical capacity of ₂ is balanced so that it is between about 1.15 and 2.0, desirably between about 1.2 and 2.0, preferably between about 1.4 and 1.8. The The planar alkaline cell design here was measured to reduce the amount of overall expansion at a higher ratio of the theoretical capacity of MnO _{2 to} the theoretical capacity of zinc. In order to reduce the overall expansion, the ratio of the theoretical capacity of MnO _{2 to} the theoretical capacity of zinc can be as high as about 2.5 or even up to about 3.0, but the cell design is about 2. At such high ratios above zero, the battery capacity is more significantly reduced, and thus less desirable from that point of view. It is not known for certain why this happens. It may be due in part to the fact that almost all of the zinc is discharged. In such a case, little if any zinc hydroxide intermediate remains in the anode, which can cause expansion.

  The ratio of the anode thickness to the casing outer thickness is desirably between about 0.30 and 0.40. (Such thickness is measured along a plane parallel to the cell's longitudinal axis across the outer thickness of the cell.) The expansion of the cell after discharge is controlled thereby, flat or rectangular Allows alkaline batteries to be used as the main power source for electronic devices such as portable digital audio players and the like.

  In one aspect, alkaline batteries have a small cubic (straight parallelepiped) overall shape, typically having an outer thickness of about 5-10 mm, specifically about 5-7 mm. . The outer thickness is measured by the distance between the outer surfaces of the opposing sides of the housing that defines the short dimension of the battery. In such an embodiment, the main (non-rechargeable) alkaline battery of the present invention may be used, for example, as a replacement for a small size planar rechargeable battery. Specifically, such a primary alkaline battery can be used as a replacement for rechargeable nickel metal hydride batteries of the same size, for example, 7 / 5-F6 size rectangular rechargeable nickel metal hydride batteries.

  In a feature of the invention, the separator can be assembled into a bag shape having an open end and an opposite closed end. Such separators can be easily formed by wrapping a single sheet of separator material and closing one end with adhesive or heat sealing. After the cathode disk is inserted into the battery casing, the wrapped separator is then inserted so that the separator surface faces the exposed cathode surface. Preferably, the width of the separator is somewhat less than the entire width of the anode cavity. This results in a gap between one short side of the separator and the cathode disk. The gap is between about 2-4 mm, preferably between about 2-3 mm. The anode material can then be filled into the anode cavity through the open end of the separator. This results in a casing filled with anode material, cathode material and separator between them, in which case there is a gap (vacant space) between one short side of the separator and the cathode. is there.

  Additional alkaline electrolyte can now be added inside the battery by injecting additional alkaline electrolyte into the gap. It may be desirable to add a small amount of additional electrolyte inside the battery after the anode and cathode are in place in the battery. Desirably, with a short time interval between incremental electrolyte dispensing, additional electrolyte may be added to the gap between the separator and cathode in small increments. In an alternative embodiment, a portion of additional electrolyte may be added to the gap after the cathode is in place and before the anode is inserted into the anode cavity. The anode material is then inserted into the battery's anode cavity, after which additional electrolyte can be added to the gap. After the last amount of alkaline electrolyte is added to the gap between the separator and the cathode, the anode expands, pressing the separator surface flush against the cathode, thus eliminating the gap.

  The additional electrolyte can help improve anode utilization and overall battery performance. It can be a factor that tends to inhibit battery expansion. If additional electrolyte is added to the gap, it has a sufficient time delay between dispensing, for example between about 1 to 4 minutes, to allow electrolyte absorption, which is in dispensing increments. Preferably it is added. Such a procedure allows absorption of additional electrolyte into the anode and cathode without causing electrolyte overflow into the end cap assembly cavity, ie, the space above the anode. Such overflow causes sufficient wetting of the metal cover surface and edges to prevent uniform laser welding of the metal cover to the casing.

  A specific embodiment of the planar alkaline battery 10 of the present invention is shown in FIGS. The battery 10 has at least two planar opposing sides that are parallel to the longitudinal axis of the battery. As best shown in FIGS. 1 and 1A, the battery is preferably rectangular, in other words, cubic. As used herein, the term “cube” refers to a geometric definition, which is a cuboid. However, the battery 10 may be a parallelepiped. The outer casing 100 as shown in the drawings is preferably cuboid-shaped and thus does not have any integral cone-shaped portion. Battery 10 typically has a thickness that is less than its width and a width that is less than its length. When the battery thickness, width, and length are different dimensions, the thickness is usually considered the smallest of these three dimensions.

The cell preferably includes a nickel-plated steel cubic casing (housing) 100. The back side of the casing 100 is preferably coated with a layer of a carbon coating based on a solvent available, for example, under the trade name TIMREX E-LB carbon coating. In the embodiment shown in the drawings, the casing (housing) 100 comprises a set of opposing large planar walls 106a, 106b, a set of opposing small planar walls 107a, 107b, and a closed end 104. Is bounded by the opposite open end 102. The battery thickness is determined by the distance between the outer surfaces of the walls 106a, 106b. The width of the battery is determined by the distance between the outer surfaces of the walls 107a and 107b. The casing 100 is preferably coated on its inner surface with a layer of carbon or indium to improve conductivity. A battery containing material including the anode 150, the cathode 110, and the separator 140 therebetween is supplied through the open end 102. In a preferred embodiment, the anode 150 includes particulate zinc, the cathode 110 includes MnO _2. An aqueous solution of potassium hydroxide forms part of the anode and cathode.

  As best shown in FIG. 5, the cathode 110 may be in the form of a plurality of slabs 110a having a hollow central core 110b throughout its thickness. The cathode slab 110a is generally rectangular. As shown in FIGS. 2, 3, and 5, the cathode slab 110a is inserted into the casing 100 and stacked vertically stacked along the length of the cell. After insertion into the casing 100, each cathode slab 110a may be recompressed. Such recompression ensures that the outer surface of each cathode slab 110 a is in intimate contact with the inner surface of the casing 100. Preferably, the hollow central core 110b in the cathode slab 110a is aligned to form one continuous central core along the cell's longitudinal axis 190 to receive the anode slurry 150. Optionally, the cathode slab 110 a closest to the closed end 104 of the casing 100 may have a bottom surface that abuts and covers the inner surface of the closed end 104.

  The cathode slab 110a may be die cast or compression molded. Alternatively, the cathode 110 may be formed of a cathode material that is extruded through a nozzle to form a single continuous cathode 110 having a hollow core. The cathode 110 can also be formed using a plurality of slabs 110 a having a hollow core 110 b, in which case each slab is extruded into the casing 100.

  After insertion of the cathode 110, the electrolyte permeable separator 140 is then centered on each slab 110a so that the outer surface of the separator 140 contacts the inner surface of the cathode, as shown in FIGS. Located in the core 110b. The inner surface of each cathode slab 110a defining the hollow center core 110b is preferably a curved surface. Such a curved inner surface improves the mechanical strength of the slab during movement and processing and provides a more uniform contact between the separator 140 and the cathode 110.

  The central core 110b of the slab 110a is aligned to form one continuous core as described above. After insertion of the separator 240, the continuous core forms an anode cavity 155 for receiving the anode material 150. The anode cavity is inside the central core of the cathode slab 110a without any cathode material. The anode cavity 155 has an elongated or oval shape when viewed in a plan view (FIG. 4B) after taking a cross section of the cathode slab 110a along a plane perpendicular to the cell's longitudinal axis 190. FIG. The cross section of the anode cavity 155 defined by the boundary parameter 156 is elliptical or substantially elliptical. The cavity 155 has a long dimension D1 that is larger than the short dimension D2. Thus, the cavity 155 is along a plane path parallel to the wide side (106a or 106b) of the cell that is larger than the diameter (or width) D2 in the direction of the plane parallel to the narrow side (107a or 107b) of the cell. It may have a diameter (or width) D1. Thus, as a non-limiting example, the anode cavity 155 can take an elliptical shape or can be substantially elliptical when viewed in a cross-section along a plane orthogonal to the central longitudinal axis 190. It can seem. The opposing long boundary edges 158a, 158b of the anode cavity, when viewed in cross section (FIG. 4B), are not fully elliptical in overall structure, but are nevertheless elongated or oval as shown. As such, it can be planar or substantially planar.

  The cavity 155 has an elongated or oval shape when viewed in cross-section (FIGS. 4B, 4C, and 4D) obtained by cutting the cathode slab 110a by a plane perpendicular to the central longitudinal axis 190 of the cell. Have Such an elongated shape may be an elongated polygon or rectangle as shown in FIG. 4C. The axis defining the long dimension D1 and the short dimension D2 of the cavity 155 defined by the boundary parameter 156 can be tilted as shown in FIG. 4D. Preferably, the cavity 155 has a curved boundary parameter 156 when viewed in a cross-section (FIG. 4B) obtained by cutting the cathode slab 110a by a plane orthogonal to the cell center longitudinal axis 190 (FIG. 1A). Have at least a portion. The cavity 155 preferably has an oval structure. In the preferred embodiment, substantially all boundary parameters 156 that define the cavity 155 are curved. Specifically, as best shown in FIG. 4B, it is desirable that at least the opposing surfaces 157a, 157b of the cavity 155 that are closest to the opposing narrow side surfaces 107a, 107b of the battery are curved. Preferably, substantially all parameters 156 of the cavity 155 are curved when viewed in cross-section as described above. When viewed from the outer casing 100 as shown in FIG. 4B, the opposing long edges 158a, 158b are preferably curved outward (convex). However, the long edges 158a, 158b can be planar or substantially planar. Alternatively, for example, by having alternating convex and concave surfaces, the long edges 158a, 158b may be slightly inwardly curved (convex) or slightly outwardly curved. (Becomes concave). Similarly, the short edges 157a, 157b may be slightly inwardly curved (convex), slightly outwardly curved (concave), or, for example, alternately concave And by having a convex surface, it can be a convoluted curve. Any cross-section of cathode slab 110a taken along a plane orthogonal to the cell's longitudinal axis has a long dimension D1 of cavity 155 representing the maximum length in the plane and a short representing the maximum width in the plane. There is also a dimension D2. The long diameter (D1) is usually in a direction along a plane parallel to the wide side (106a, 106b) of the cell, and the small dimension (D2) is the narrow side (107a, 106) of the cell as shown in FIG. 4B. 107b) in a direction along the plane. Cavity 155 is characterized by having at least some curvature and having a ratio of D1 / D2 greater than 1.0 when viewed in cross-section as described above, which is an elongated or oval structure. Is reflected. When viewed in a cross-section taken along a plane perpendicular to the longitudinal axis 190, the shape of the cavity 155 has a symmetrical ellipsoidal structure with a 1 / D2 ratio greater than 1.0. desirable. In such a case, dimensions D1 and D2 are orthogonal to each other, as shown in FIG. 4B. As a particular non-limiting example, the shape of the cavity 155 is oval when viewed in such a cross section and can be oval or substantially oval.

  The anode 150 is preferably in the form of a gelled zinc slurry containing zinc particles and an aqueous alkaline electrolyte. The anode slurry 150 is injected into the central core 155 of the battery along the longitudinal axis 190 of the battery. Thus, the anode 150 is isolated from direct contact by the separator 140 between them.

  After supplying the battery contents, the battery assembly (FIG. 4) is then inserted into the open end 102 to seal the battery and provide a negative terminal 290. The closed end 104 of the casing can function as the positive terminal of the battery. The closed end 104 can be withdrawn or stamped to provide a protruding positive pip, or a separate end plate 184 with a protruding pip 180 can be attached to the closed end of the casing 104 as shown in FIG. 1A. It can be welded to part 104.

  The components that make up a specific embodiment of the end cap assembly 12 are best shown in FIG. The end cap assembly 12 includes an elongated anode current collector 160, an insulating sealing member 220, a metal cover 230 positioned over the sealing member 220, and a metal rivet 240 partially penetrating the insulating sealing member 220. A plastic spacer 250 that insulates the rivet 240 from the metal cover 230, a rubber vent plug 260 located in the cavity 248 in the rivet 240, a plastic extender seal 280, and a negative terminal plate 290 on the plastic extender 280, including.

A rubber vent plug 260 when located in the cavity 248 in the rivet 240 and a vent pip cap 270 on the rubber plug 260 are disclosed and are commercial 7 / 5-F6 manufactured by Gold Peak Battery (Hong Kong). It is recognized that it is used in connection with a rectangular rechargeable nickel metal hydride battery model number GP14M145. However, applicants of the present patent application have promoted bubble generation if the end cap assembly generally causes corrosion in the rechargeable nickel metal hydride battery model number GP14M145 and is applied to a primary zinc / MnO ₂ alkaline battery. Measured to do. It has been found that such corrosion occurs between the elongated current collector and the back of the battery housing because the widest part of the current collector is very close to the inner surface of the battery housing (less than about 0.5 mm). It will be appreciated that a large portion of the current collector 160, i.e., the flange 161, is used in conjunction with a receiptable vent plug design. Such a large portion of the current collector (flange 161) is required because the current collector is riveted to the lower surface of the insulating sealing member 220. Thus, the flange 161 must be wide enough to fasten the base 246 of the rivet 240 thereto. If the battery 10 is a small size planar battery, for example a cube-shaped battery having an overall thickness of about 5-10 mm, the edge of the flange 161 is therefore close to the inner surface of the casing 100. Terminate.

  Applicants have modified the subassembly including the current collector 160 and the insulating sealing member 220 by redesigning the insulating sealing member 220 to provide the surrounding skirt 226 to the insulating sealing member. Insulating sealing skirt 226 surrounds the widest portion of anode current collector 160, namely flange 161. Thus, the insulating skirt 161 provides a barrier between the current collector flange 161 and the inner surface of the casing 100. The insulating skirt 161 is measured to reduce the production of metal containing corrosive chemicals, typically composites or compounds, in the space between the flange 161 and the inner surface of the casing 100 during battery discharge. It was. Such corrosive chemicals, if produced in large quantities, can interfere with cell performance and promote cell bubble generation. Also, in the modified design described herein, the widest portion of the anode current collector 160, ie, the flange 161, is between about 0.5-2 mm, preferably about 0.5-1. Between 5 mm. This, in combination with the use of an insulating sealing skirt 226 surrounding the current collector flange 161, produces any significant amount of corrosive chemical between the wide portion of the current collector (flange 161) and the inner surface of the casing 100. It was also measured to prevent. Such a modified design of the present invention then makes the receiptable rubber vent plug assembly suitable as a viable venting mechanism for a planar primary alkaline battery.

  The components of the end cap assembly 12 best shown in FIGS. 4 and 5 may be assembled as follows. The anode current collector 160 includes an elongated shaft 162 that terminates at the tip at the bottom end and terminates at an integral flange 161 that extends outwardly at the top end, which is preferably perpendicular to the shaft 162. Thus, when the current collector 160 is inserted into the anode 150, the outwardly extending flange 161 can be closer to the inner surface of the casing 100 than the shaft 162. The insulating sealing member 220 has a top panel 227 and an open bottom 228 on the opposite side. The insulating sealing member 220 is preferably made of nylon 66 or nylon 612 that is durable, resistant to alkali, and has hydrogen permeability. Alternatively, the insulating sealing member 220 may be constructed from durable and hydrogen permeable polypropylene, talc filled polypropylene, sulfonated polyethylene, or other polyamide (nylon) grades. The insulating member 220 is preferably a rectangle that can be slip-fit into the open end 102 of the casing 100. Opposing side walls 226 a and opposing side walls 226 b extending from the top end 227 of the insulating sealing member 220 form a downwardly extending skirt 226 around the top panel 227. The skirt 226 limits the open bottom 228 of the insulating sealing member 220. There is an opening 224 through the top panel 227. There is a metal cover 230, which can be a metal plate with an opening 234 therethrough. There is a metal rivet 240 having a head 247 and a base 245. The rivet 240 can be nickel-plated steel or stainless steel. The rivet 240 has a cavity 248 in the head 247. The cavity 248 passes completely through the rivet head 247 and the rivet shaft 245. The flange 161 of the current collector 160 is inserted into the open bottom 228 of the insulating sealing member 220 so that the flange 161 of the current collector 160 is surrounded and protected by the skirt 226 of the sealing member 220. As shown in FIG. 4, the flange portion 161 of the current collector 160 has an opening 164 extending therethrough. The base 246 of the rivet 240 can be passed through the opening 164 and riveted to the flange 161 to hold the current collector 160 in electrical contact with the rivet.

  In such an embodiment, the insulating skirt 226 provides a barrier between the current collector flange 161 and the inner surface of the electrical casing 100. A narrow gap, for example, less than about 0.5 mm, between any surface of the anode current collector 160 and the inner surface of the cell casing 100 can provide an area where corrosive byproducts can occur during the discharge of the alkaline cell. Measured. This in turn can passivate adjacent regions of the anode current collector 160 and promote bubble generation. A downwardly extending skirt 226 of the insulating sealing member 220 surrounds an outwardly extending portion of the current collector 160, such as an integral flange 161, thereby providing a barrier between the widest portion of the current collector 160 and the casing 100. Is intended to bring This has been determined to solve the corrosion problem and reduce bubble generation. Applicant has changed the design by redesigning the widest part of the current collector, preferably by providing an insulating skirt 226 that surrounds the widest part of the anode current collector 160, ie, the flange 161. did. In the following paragraphs here, the arrangement and effect of the skirt 226 will be described in more detail. In Applicant's modified design described herein, the widest portion of the anode current collector 160, i.e., the flange 161, is between about 0.5-2 mm, preferably about 0.5-2 mm from the inner surface of the housing. Between 1.5 mm. The go insulation skirt 226 also provided a barrier between the current collector flange 161 and the casing 100. The function of these designs has been measured to solve the corrosion problem and to make the receiptable rubber vent plug assembly a viable venting mechanism for the planar primary alkaline battery of the present invention.

  In forming the end cap assembly 12, the flange portion 161 of the current collector 160 is positioned such that the opening 164 extending therethrough is aligned with the opening 224 extending through the top panel 227 of the insulating sealing member 220. The metal cover 230 is positioned over the top panel 227 of the insulating sealing member 220 such that the opening 234 through the metal cover 230 is aligned with the opening 224. A plastic spacer disk 250 is inserted over the metal cover 230 such that the opening 252 through the spacer disk 250 is aligned with the opening 234 in the metal cover 230. In the preferred embodiment (FIG. 4), the base 246 of the rivet 240 is passed through the opening 252 in the plastic spacer 250 and through the opening in the metal cover 230. The base 246 of the rivet 240 is also passed through the opening 224 of the insulating sealing member 220 and the opening 164 of the current collector flange 161. The plastic spacer 250 insulates the rivet 240 from the metal cover 230. The base 246 of the rivet shaft 245 extends through an opening 224 in the insulating sealing member 220 and an opening 164 located below in the top flange portion 161 of the anode current collector 160. A track rivet hammer can be used to drive the rivet shaft base 246 into place relative to the bottom surface of the current collector flange 161. This locks the rivet shaft in place within the opening 224 of the insulating sealing member 220 and also fixes the current collector 160 to the rivet shaft 245. This keeps the current collector 160 in permanent electrical contact with the rivet 240 and prevents the rivet shaft 245 from being removed or removed from the opening 224 in the insulating sealing member 220. The rivet head 247 is positioned on the plastic spacer 250 in an airtight manner. This forms a subassembly that includes rivets 240, plastic spacers 250, metal cover 230, insulating sealing member 220, and anode current collector 160. The subassembly can be stored until it is ready for further assembly.

The assembly process is completed by inserting the rubber vent plug 260 into the cavity 248 in the rivet head 247. The plug 260 is preferably frustoconical and is designed to slip fit within the cavity 248 in the rivet head 247. The plug 260 is preferably made of a compressible flexible material that is resistant to alkaline electrolyte. A suitable material for the plug 260 is rubber, preferably neoprene or EPDM (ethylene-propylene diene terpolymer) rubber, or other alkali compression resistant rubber. The surface of the plug 240 is preferably coated with a non-wetting material such as Teflon (polytetrafluoroethylene), asphalt, or polyamide. Next, a metal vent pip cap 270 is inserted over the plug 260. The vent pip cap 270 is pressed against the plug 260 with sufficient force to compress the plug by about 0.5 mm. This has been measured to provide a seal that can withstand an internal pressure build-up of approximately 200 psig (13.79 × 10 ⁵ Pascals). The seal is typically between about 100 to 300 psig (6.895 x 10 ^{5 to} 20.69 x 10 ⁵ Pascal gauge), preferably about 100 to 200 psig (6.895 x 10 ^{5 to} 13.79 x 10). ^The plug 260 compression can be adjusted to withstand internal pressures between ⁵ Pascal Gauge). A higher degree of compression of the plug 260 is also possible, if desired, to allow a seal to withstand higher pressures, ie, higher than 300 psig (20.69 × 10 ₅ Pascal gauge). Conversely, if desired, the compression of the plug 260 can be reduced so that the seal is maintained to a pressure threshold at any desired value below 100 psig. The base 273 of the vent pip cap 270 may have indentations in the top surface of the plastic spacer 250 or several downwardly extending segments that fit into the crevasse 253 when the vent cap 270 is pressed onto the plug 260. This is best shown in FIG. A vent cap 270 is welded to the rivet head 247 after a vent pip cap 270 is inserted over the plug 260 thereby compressing the plug in the rivet head cavity 248. The plug 260 is thereby maintained in compression within the rivet head cavity 248. The plastic extender member 280 is disposed on the vent cap head 271. The ventilation cap head 271 protrudes through an opening 282 in the plastic extender 280. Next, the terminal end cap 290 (negative terminal) is welded to the ventilation cap head 271. Thus, the vent cap 270 is welded to both the end plate 290 and the rivet 240. The terminal end plate 290 is composed of a conductive metal having good mechanical strength and corrosion resistance, such as nickel plated cold rolled steel or stainless steel, preferably nickel plated low carbon steel. Thus, the completed end cap assembly 12 is formed with a terminal end plate 290 that is in permanent electrical contact with the current collector 163.

The completed end cap assembly 12 is then inserted into the open end 102 of the casing 100. The current collector shaft 162 penetrates into the anode slurry 150. The edge of the metal cover 230 is welded to the top periphery 104 of the casing, preferably by laser welding. This securely holds the end cap assembly 12 in place and seals the open end 102 of the casing 100 as shown in FIGS. 1 and 1A. Terminal plate 290 is in electrical contact with current connector 160 and anode 150 and thus forms the negative terminal of the battery for the zinc / MnO ₂ alkaline battery embodiment described herein. It will be appreciated that the negative terminal plate 290 is electrically isolated from the casing 100 by the plastic extender 280. The rivet 240 and the current collector 160 are electrically insulated from the casing 100 by the plastic spacer 250 and seal the sealing member 220. As shown in FIGS. 1A, 2, and 3, the pip 180 forms the positive terminal of the battery at the closed end of the opposing casing 100. The pip 180 may be integrally formed from the closed end 104 of the casing 100 or may be formed from a separate plate 184 that is separately welded to the closed end as shown in FIG. 1A. The completed battery is shown in the perspective view of FIGS. 1 and 1A and the cross-sectional views of FIGS.

  In operation, during battery discharge or storage, if the gas pressure in the battery accumulates and exceeds the design threshold level, the plug 260 will detach in the rivet head cavity 248. This allows gas to escape from the cell interior to the external environment through the rivet head cavity 248 and then through the vent opening 272 of the vent cap 270. As the pressure in the battery decreases, the plug 260 will disengage within the rivet head cavity 248.

  As an additional safety feature, the battery may include a second vent device that serves to supplement the receiptable plug vent 260. Supplementary ventilation works in catastrophic situations, for example, if a user inadvertently attempts to charge the main battery 10 over a long period of time using a battery charger that can be charged in a flat manner. Can be designed. The battery 10 of the present invention is designed to be the main (non-rechargeable battery). Charges designed to inadvertently charge a flat charger, for example a flat nickel metal hydride battery, despite the full written notice on the battery label that the battery must not be charged There is always the possibility of trying to charge the battery in the vessel. If the battery is abused in this way by trying to charge it for a long time, there is a risk that the internal pressure level can suddenly rise.

If the battery 10 is inadvertently exposed to charging (despite being intended as the primary non-rechargeable battery), the plug vent 260 will be removed, thereby causing the internal pressure to be at the design threshold, preferably about 100-300. The pressure is released when (pressure between 6.895 × 10 ^{5 to} 20.69 × 10 ⁵ Pascal gauge) is reached. If the pressure builds up again after a long period of continuous charging, the plug 260 will again evacuate. Such plug detachment and re-seat processes can be repeated many times, resulting in a pulse release of gas pressure from within the cell. Under such abuse conditions, the KOH electrolyte may gradually enter and crystallize into the free space between the plug 260 and the inner surface of the rivet head cavity 248 housing plug 260. (The plug 260 is held in compression in the rivet head cavity 248 by a vent cap 270 welded to the rivet head.) Such crystallized KOH buildup is the inner surface of the plug 260 and vent cap 270. Reduce the amount of free space between. As the threshold gas pressure is reached, there may be less free space available for expansion of the plug 260 so that when the charging process continues, this will gradually cause the plug 260 to properly seat. Can be more difficult. Accumulation of crystallized KOH in a small amount of free space in the rivet head 248 may also prevent proper gas flow through the vent opening 272 in the vent cap 270.

  In order to reduce the deleterious effects of such KOH crystal accumulation between the plug 260 and the inner surface of the vent cap 270, several improvements in the design are proposed here.

  The venting system of the present invention may include primary and supplemental venting mechanisms. When the gas pressure in the battery accumulates to the design pressure threshold level P1, the main ventilation mechanism is activated. Having a supplementary venting mechanism that activates at a higher pressure level P2 if the main venting mechanism malfunctions or if the battery is exposed to an unauthorized use situation that produces a rapid accumulation of gas pressure. desirable. For example, one such unauthorized use situation can occur if a battery is inadvertently exposed to charging for an extended period of time. In one specific embodiment of the present invention, the receiptable plug 240 is used as the main vent mechanism, which is activated at a design threshold pressure P1 between about 100-300 psig. The supplemental venting mechanism can be a weak laser weld somewhere in the notch of the end cap assembly 12 or casing body 100. The weak laser weld is designed to rupture when the gas pressure in the cell reaches a higher pressure P2, desirably between about 400-800 psig. There can also be strong welds, preferably in contact with weak welds.

By forming a weak laser weld along a portion of the laser weld interface between the metal cover 230 and the inner surface of the casing 100, one embodiment of a supplemental ventilation system may be provided. (The metal cover 230 is used to close the open end 102 of the casing 100.) Preferably, as shown in FIG. 6, the metal cover has a long edge 230a and one main part of the casing edge 108a. In the middle, a weak weld 310a can be applied. Weak laser welds so that the weld is of a thickness that will crack or rupture as desired when the gas in the battery accumulates to a pressure between about 400-800 psig (2748 × 10 ^{3 to} 5515 × 10 ³ Pascals) 310a can be applied. The penetration depth of the weak weld can be adjusted to achieve the desired burst pressure. Burst pressures between about 400 to 800 psig (2748 × 10 ^{3 to} 5515 × 10 ³ Pascal gauge) can be achieved with laser welding penetration depths between about 2 to 4 mils (0.0508 to 0.102 mm) . The weak weld may desirably run along at least one major portion of the long edge 230a of the metal cover 230. Preferably, the weak weld begins at a point 312a at least about 1 mm from the intersecting corner of the short edge 108c and the long edge 108a of the casing 100. Thus, for a planar 7 / 5-F6 battery, the length of the weak weld can be at least 10 mm, typically about 13 mm.

The remainder of the circumferential interface between the edge of the metal cover 230 and the casing edge (casing edges 107c, 107d, 106d) (FIG. 6) is at a higher pressure level, eg, about 800-2500 psig (5515 × 10 ³ between ~17235 × 10 ³ pascal gage), typically it may comprise a strong laser weld 310b between about ^{800~1600psig (5515 × 10 3 ~11030 ×} 10 3 Pascals gauge). In order to achieve the desired burst pressure, the penetration depth of the strong weld can be adjusted. A burst pressure of between about 800-2500 psig (5515 × 10 ^{3 to} 17235 × 10 ³ Pascal gauge) is achieved at a laser weld penetration depth of between about 5-7 mils (0.127-0.178 mm). obtain. The depth of penetration of a strong weld can be adjusted more finely, allowing the weld to burst at a desired pressure level, eg, about 1300-1600 psig (8962 × 10 ^{3 to} 11030 × 10 ³ Pascal gauge) .

  As shown in FIG. 6, the edge of the metal plate 230 is shown welded to the inner surface of the metal casing 100, but the edge of the metal plate 230 is attached to the edge of the metal casing instead of the inner surface of the casing 100. There may be alternative welded embodiments. One such alternative embodiment is shown in FIG. 6A. In such an embodiment (FIG. 6A), the casing edge 108 defined by the opposing long edges 108a, 108b and the opposing short edges 108c, 108d is such that the edges are substantially flush with the metal plate 230. Crimped to be located at Therefore, the edges 230a and 230b of the metal plate 230 can be directly welded to the crimped casing edge 180. A stronger laser weld 310b can be added between the plate edge 230b and the casing edges 108b, 108c, 108d, and a weak laser weld 310a can be added between the plate edge 230a and the casing edge 108a.

  In still other embodiments, there may be a notch in the body of the casing 100. The notch can have various shapes. For example, the notch can be polygonal (FIG. 7) or have at least a portion of its boundary curved (FIG. 7A). A metal plate, such as plate 400 (FIG. 7) or plate 500 (FIG. 7A), may be inserted into such a notch. To close the notch, the edge of the metal plate 400 (FIG. 7) or metal plate 500 (FIG. 7A) may be welded to the casing. As shown in the embodiment of FIG. 7, the weld may desirably be in the form of a strong laser weld 410b and a weak laser weld 410a in contact. As shown in FIG. 7A, the weld may be in the form of a strong laser weld 510b and preferably a weak laser weld 510a in contact.

Strong and weak welds can be achieved using different types of lasers operating within the range of peak power output. The following are non-limiting examples of weak and strong welds produced using a Nd: Yag laser. Weak welds such as those described above will crack or rupture when the gas pressure in the battery reaches a threshold pressure between about 400-800 psig (2748 × 10 ^{3 to} 5515 × 10 ³ Pascal gauge). Strong welds have a gas pressure in the battery of about 800-2500 psig (5515 × 10 ^{3 to} 17235 × 10 ³ Pascal gauge), typically 800-1600 psig (5515 × 10 ^{3 to} 11030 × 10 ³ Pascal gauge). Rupture when a threshold pressure in between is reached. In particular, the weak weld provides a supplemental ventilation system and allows gas to escape from within the battery if the battery is tampered with as described above.

  Alternatively, the supplemental venting mechanism may be in the form of a slotted vent, i.e. one or more grooves on the surface of the casing 100 that yields a thin material region located below. The depth of the groove and the thickness of the thin material region located below can be adjusted so that the thin region bursts when the gas pressure in the battery rises to a pressure P2 greater than P1. In other embodiments, a laser weld may be used as the main vent mechanism that eliminates the receiptable plug and operates at pressure P1. In such an embodiment, the supplemental venting mechanism can be a thin-walled material region located below the groove on the casing surface. A thin material may be designed to rupture at a higher pressure level P2.

  In still other embodiments, there may be multiple grooves on the casing surface. One groove may have a thin region located below a small thickness and allow it to rupture when the gas in the cell is accumulated to the design pressure level P1. The second groove on the casing surface that can be in contact with or away from the first groove can have a thin walled area located below that is designed to rupture if the gas pressure in the cell accumulates to a higher pressure P2. .

When the casing 100 is made of steel, such as nickel-plated cold-rolled steel or stainless steel, the thin-walled material located below the groove has a gas pressure in the battery of about 400 to 800 psig (2748 × 10 ^{3 to} 5515 × 10 ^3). A groove such as groove 600a (FIG. 8) may be formed on the casing surface to rupture when a pressure between (Pascal gauge) is reached. The non-grooved portion of the casing wall typically has an average wall thickness between about 0.3 and 0.50 mm, desirably between about 0.3 and 0.45 mm. To obtain a bursting pressure between about 400-800 psig (2748 × 10 ^{3 to} 5515 × 10 ³ Pascal gauge), the groove is a thin-walled material located below, typically about 0.07-0.08 mm. Formed to have a thickness between. In a specific, non-limiting example, if the groove is formed so that the thin material underneath has a thickness of about 0.074 mm, such underneath material is Bursts when gas pressure reaches a level of about 435 psig (2999 × 10 ³ Pascal gauge).

  By punching the surface of the casing with a mold, preferably a mold with a cutting knife edge, a groove 600 may be formed which may be in the form of a groove 600a or 600b (FIGS. 8 and 8A) on the casing surface, for example. When the punching die pierces the casing outer surface, the mandrel is held against the inner surface of the casing. For a groove formed with such a punching or cutting die, the thickness of the thin region 610 located below (FIG. 9) mainly determines the pressure at which the thin region bursts. The grooving is desirably V-shaped, which can preferably be obtained with a punching die having a knife edge. The V-shaped groove desirably has an acute angle of about 40 degrees. The groove 600 may be formed by other methods, for example, a chemical etching process.

  The thin-walled material located below the groove 600 is typically the same as the casing material made of nickel-plated cold rolled steel. The groove 600 may have straight or curved boundaries, or may have a combination of straight and curved lines. The groove 600 may have a rectangular, polygonal, or oval boundary. The grooves may have at least a portion of their boundaries that are convoluted, in other words, partially convex and partially concave. The groove boundaries can be closed or opened and closed. In the preferred embodiment here, the grooves can be straight or substantially straight, preferably parallel to the wide edge 108a of the casing (FIGS. 8 and 8A). For example, in a 7 / 5-F6 size rectangular cell, the groove 600a (FIGS. 8 and 8A) may be located parallel to and about 10 mm from the wide edge 108a of the casing and has a length of about 8 mm. Can do.

As shown in FIG. 8A, there may be a second groove 600b spaced from the first groove 600a. In a specific non-limiting embodiment, the second groove 600b is parallel to the groove 600a and can be about 10 mm from the positive terminal 180 (closed end). The groove 600b has a length of about 8 mm. In such a case, the thickness of the material located below each groove 600a, 600b may be different so that the material located below ruptures when the gas pressure in the battery reaches different pressure levels. For example, the groove 600a under which the thin material is located can be designed to rupture when the gas pressure in the battery reaches a design explosion pressure of between about 250-800 psig. To achieve such a range at an explosion pressure between about 250-800 psig (1724 × 10 ^{3 to} 5515 × 10 ³ Pascal gauge), the groove 600a under which the thin-walled material is located is about 0.04- Having a thickness of between 0.15 mm. Alternatively, the groove in which the thin-walled material is positioned so that it bursts when the gas pressure in the battery reaches a design explosion pressure between about 400-800 psig (2758 × 10 ^{3 to} 5515 × 10 ³ Pascal gauge) 600a can be designed. In order to achieve such an explosion pressure that is between about 400-800 psig, the groove 600a under which the thin-walled material is located has a thickness between about 0.07-0.15 mm. When the gas pressure in the battery bursts in a catastrophic situation when the battery is misused and the gas pressure in the battery suddenly rises to a level of about 800-1600 psig (5515 × 103-11030 × 103 Pascal gauge) The groove 600b in which the thin material is located below may be designed to rupture. To achieve rupture at pressure levels between about 800-1600 psig, the groove 600b under which the thin material 610 is located typically has a thickness of about 0.15-0.35 mm.

Example 1 (Weak weld using Nd: Yag laser)
Using a Nd: Yag laser creates a weak weld that is used to weld the metal cover 230 to the casing 100 along the casing edge 106c (FIG. 6 or 6A). The laser is operated at a frequency of about 100 hertz. The peak power output per pulse is about 35 watts. The average power output is 0.5 kilowatts. The pulse width (period time between peak outputs) is about 0.7 milliseconds. The laser feed rate (the rate of laser movement along the welding path) is about 3 inches per minute. A uniform weld along the long edge 106c of the casing is created, thereby welding the long edge 230a of the abutting metal cover 230 thereto. The weld had a uniform penetration depth of between about 2-4 mils (0.0508-0.102 mm), typically about 3 mils (0.0762 mm). If the pressure in the battery reaches a level between about 400-800 psig (), the weld will crack, and if the operation of the main vent (plug 260) becomes compromised, it will be supplementary. Functions as a vent.

Example 2 (Strong weld using a Bd: Yag laser)
By using an Nd: Yag laser, a strong weld used to weld the metal cover 230 to the casing 100 along the casing edges 106d, 107c, 107d (FIG. 6 or 6A) may be generated. By using an Nd: Yag laser, a strong weld used to weld the metal cover 230 to the casing 100 along the casing edges 106d, 107c, 107d can be generated. The laser operates at a frequency of about 12 hertz. The peak power output per pulse is 0.65 kilowatts. The pulse width (cycle time between peak outputs) is about 5.9 milliseconds. The laser feed rate (speed of laser movement along the welding path) is about 2 inches per minute. A uniform weld along the long edges 106d, 107c, 107d is created, thereby welding the edges of the abutting metal cover 230 thereto, as shown in FIG. The weld had an equivalent penetration depth of between about 5-7 mils (0.127-0.178 mm, typically about 6 mils 0.152 mm). Welding when the pressure in the cell reaches a level between about 800-2500 psig (5515 × 103-17235 × 103 Pascal gauge), typically about 800-1600 psig (5515 × 103-11030 × 103 Pascal). The part cracks.

  In commercial production, the Nd: Yag laser described above can operate at a higher peak power of about 125 watts to produce a weak weld and can operate at a peak power of about 150 watts to produce a strong weld. . Such operation at higher peak power allows the laser to be moved along the welding path (feed rate) at higher speeds.

  In addition, to reduce the deleterious effects of any KOH crystal accumulation between the plug 260 and the inner surface of the vent cap 270 that can occur if the battery is inadvertently exposed to charging, the plug plugs the plug 260. The plug 260 can be modified to occupy less space in the cavity in the receiving rivet head 247. A specific embodiment of such an improved design is shown in FIGS. 2A, 3A, and 4A. In the improved design of thread 260 shown in FIG. 4, the plug occupies less space in the rivet head cavity 248 than the truncated design for the plug shown in FIGS. After the plug 260 is compressed into the rivet head cavity 248, the amount of free space in the cavity 248 that houses the plug is about 10%, and preferably greater than about 10-40%. In contrast, the amount of free space in the rivet cavity of the plug 260, shown in the truncated form shown in FIGS. 2, 3, and 4, is typically less than about 10%.

  An amount of free space typically greater than about 10-40% within the rivet head cavity 248 achieved using a modified plug design (FIG. 4A) can be used in tampering situations, for example, as described above. If the battery is inadvertently exposed to charging, it ensures more effective operation of the plug. Such a modified plug 260 (FIG. 4A) desirably dislodges when the gas pressure in the battery reaches a design threshold level, for example, about 100-300 psig. The more free space in the rivet cavities 248 corresponds to any gradual KOH crystal accumulation that accumulates inside the batteries that can occur if the batteries are misused by inadvertent charging. Nevertheless, it enables the plug 260 to operate effectively when seating itself to allow the gas pressure to be released when the pressure in the battery accumulates to the design threshold level. There is sufficient free space in the rivet head cavity 248 to do so.

  To achieve a greater amount of free space within the rivet head cavity 248, the shape of the plug 260 can be modified as shown in FIG. 4A. In the modified design (FIG. 4A), the plug 260 has a cylindrical base 262 and a smaller diameter integrally formed cylindrical body 261 extending therefrom. After the modified plug 260 (FIG. 4A) is compressed in the cavity, a desired higher amount of free space is typically achieved in the rivet head cavity 248, typically between about 10-40%. If necessary, the ratio of the diameter of the body 261 to the diameter of the base 262 can be adjusted. The cylindrical shape of the main body 261 sufficiently withstands the pressure of the compression plug 260 in the rivet head cavity 248. The modified plug 260 (FIG. 4A) is compressed within the rivet head cavity 248 by applying force to the top surface 263 of the plug and then welding the vent cap 270 to the rivet head 247. This keeps the plug 260 seated in a compressed state in the rivet head cavity 248 in a compressed state. In the compressed state, the body 261 of the plug 260 assumes a bulbous structure as shown in FIGS. 1A and 2A. When the gas pressure in the battery accumulates to a threshold level, desirably between about 100-300 psig, the plug will dislodge, thereby allowing gas from within the bulb to escape through the vent opening 272 in the vent cap 270. Preferably, there are at least two vent openings 272 in the vent cap 270 to ensure that there is a clear passage through which gas can escape from the vent cap 270 when the plug 270 is disengaged. The plug 260 is preferably made of an elastomer and is preferably made of a rubber material that is sufficiently compressible and elastic, yet resistant to chemical attack or physical degradation after contact with the alkaline electrolyte. A suitable rubber material for the plug 260 is a vulcanized EPDM rubber and desirably has a durometer hardness of between about 80-85.

  Although a modified configuration for the plug 260 as shown in FIG. 4 is desirable, other shapes of the plug may also help achieve the desired increase in free space within the rivet head cavity 248 that houses the plug. For example, instead of a cylindrical shape as shown in FIG. 4A, the plug body 261 may be slightly inclined. Also, the width of the rivet head cavity can be increased in the direction of the wide side of the battery (FIG. 2A). In such a case, the rivet head cavity 248 is elongated along one axis, i.e. in the direction of the wide side of the battery (Fig. 2A). However, the symmetrical (circular) rivet head cavity 248 currently shown in the drawings is preferred.

  It is not intended to limit the present invention to any particular size rectangular battery. However, as a specific example, the alkaline battery 100 is a small sized rectangle (cube), typically between about 5-10 mm thick, specifically the outer surface of the casing. When measured in the thickness direction, it may have a thickness of about 5-7 mm. The width of the battery is typically about 12-30 mm, and the length of the battery can typically be between about 40-80 mm. Specifically, the alkaline battery 10 of the present invention can be used in place of a rechargeable nickel metal hydride battery of the same size, such as a standard 7 / 5-F6 size rectangular battery. The 7 / 5-F6 size battery has a thickness of 6.1 mm, a width of 17.3 mm, and a length of about 67.3 mm.

Typical Battery Chemical Composition The following description of the battery composition regarding the chemical composition of the anode 150, cathode, and separator 140 is applicable to the planar battery described in the above embodiments.

  In the battery 10 described above, the cathode 110 includes manganese dioxide, and the anode 150 includes zinc and an electrolyte. The aqueous electrolyte consists of a conventional mixture of KOH, zinc oxide, and gelling agent. The anode material 150 can be a gelled mixture containing mercury-free (zero added mercury) zinc alloy powder. In other words, the battery has a total mercury content of less than 100 parts per million (ppm) of zinc by weight, preferably less than 50 parts per million mercury by weight of zinc. The battery preferably does not have any additional amount of lead and is therefore essentially lead-free, in other words, the total lead content is less than 30 ppm, desirably less than 15 ppm of the total zinc in the anode. It is. Such a mixture is typically an aqueous KOH electrolyte solution, a gelling agent (eg, an acrylic acid copolymer available from BF Goodrich under the trade name CARBOPOL C940) and a surfactant ( For example, an organic phosphor ester group surfactant available from Rhone Poulene under the trade name GAFAC RA600. Such a mixture is given only as a ridiculous example and is not intended to limit the invention. Other exemplary gelling agents for the zinc anode are disclosed in US Pat. No. 4,563,404.

  The cathode 110 desirably has the following composition. 87-93 wt% electrolyte manganese dioxide (e.g. Trona D from Kerr-KcGee), 2-6 wt% (total) graphite, 5-7 wt% 7-10 common with about 30-40 wt% KOH concentration An aqueous KOH solution and a 0.1 to 0.5 wt% selective polyethylene binder. The electrolyte manganese dioxide typically has an average particle size of between about 1-100 microns, desirably about 20-60 microns. The graphite is typically in the form of natural, expanded graphite, or a mixture thereof. Graphite may include graphitic carbon nanofibers alone or a mixture with natural or expanded graphite. Such cathode mixtures are exemplary and are not intended to limit the present invention.

  Anode material 150 includes 62-69 wt% zinc alloy powder (99.9% zinc containing indium containing 200-500 ppm indium as an alloy and plating material), an aqueous KOH solution containing 38 wt% KOH and about 2 wt% ZnO. , Under the trade name "CARBOPOL C940" F. Cross-linked acrylic acid copolymer gelling agent commercially available from Goodrich and Grain Processing Co. under the product name “Waterlock A-221”. Hydrolyzed polyacrylonitrile (between 0.01 and 0.5 wt%) grafted onto a starch backbone commercially available from and under the trade name of organophosphate ester surfactant RA-600 or RM-510 Contains dionylphenol phosphate ester surfactant (between 100 and 1000 ppm) available from Rhone-Poulene. The term zinc as used herein should be constrained to include zinc alloy powders that contain very high concentrations of zinc, for example, at least 99.9 percent zinc by weight. Such a zinc alloy material functions essentially as pure zinc electrochemically.

  For the anode 150 of the planar alkaline battery 10 of the present invention, the average average particle size of the zinc powder is desirably between about 1 to 350 microns, desirably between about 1 to 250 microns, preferably about 20 to 250 microns. Between. Typically, the zinc powder can have an average average particle size of about 150 microns. The zinc particles in the anode 150 can be needle-shaped or spherical. Spherical zinc particles are preferred. This is because they dispense better from the dispensing nozzle used to fill the relatively small anode cavities of batteries with zinc slurry. The bulk density of zinc in the anode is about 1.75 to 2.2 grams zinc per cubic centimeter of the anode. The volume percent of aqueous electrolyte solution in the anode is about 69.2 to 75.5 volume percent of the anode.

(Per gram 820 mA - time based) ma Zinc - (- based on time 370 mA MnO ₂ per one gram) milliamp MnO ₂ - time is divided by the capacity to time capacity is about 1, battery 10 is balanced in a conventional manner. However, it is preferable to balance the battery so that the cathode is significantly exceeded. Preferably, the battery 10 has a total theoretical capacity of MnO ₂ divided by the total theoretical capacity of zinc between about 1.15 and 2.0, desirably between about 1.2 and 2.0, preferably 1 Equilibrated to be between .4 and 1.8, more preferably between about 1.5 and 1.7. Since there is a smaller proportion of MnO ₂ to MnOOH conversion during discharge based on total cell weight, the balance of a cell with such cathode excess was determined to reduce the amount of cathode expansion. This in turn reduces the amount of battery casing expansion. In order to reduce the overall expansion, the above ratio of the theoretical capacity of MnO _{2 to} the theoretical capacity of zinc is as high as about 2.5, as high as possible, or as high as about 3.0. However, the battery design significantly reduces battery capacity at such higher ratios above about 2.0, and is therefore less desirable from that point of view.

Between about 0.30 and 0.50 mm, typically between about 0.30 and 0.45 mm, preferably between about 0.30 and 0.40 mm, more desirably between 0.35 and 0.45. It was determined that it was desirable to have a casing 10 wall thickness between. The battery 10 is preferably in the shape of a cube (FIGS. 1 and 2), desirably having an overall thickness between about 5-10 mm. In combination, the battery is balanced so that the cathode is exceeded. Preferably, the cell has a ratio of the theoretical capacity of MnO ₂ (based on 370 milliamp-hour MnO ₂ per gram) divided by the milliamp-hour capacity of zinc (based on 820 milliamp-hour zinc per gram) Equilibration is between about 1.15 and 2.0, desirably between about 1.2 and 2.0, preferably between about 1.4 and 1.8. The ratio of the anode thickness to the outer casing thickness is desirably about 0.30 to 0.40. (Such thickness is measured along a plane perpendicular to the longitudinal axis 190 across the cell thickness (small dimension).)

  Separator 140 may be a conventional iron porous separator comprising an inner layer of cellulose and polyvinyl alcohol fiber nonwoven material and an outer layer of cellophane. Such materials are illustrative only and are not intended to limit the invention.

  The casing 100 is preferably made of nickel-plated steel. The casing 100 is desirably coated on the inner surface with a carbon coating, preferably a graphitic carbon coating. Such a graphite coating is, for example, in the form of an aqueous-based graphite dispersion, which is applied to the inner surface of the casing, which can subsequently be dried under environmental conditions. Graphite carbon can indirectly reduce cell bubble generation by improving conductivity and reducing the possibility of surface corrosion occurring on the inner surface of the casing. The metal cover 230, the negative terminal plate 290, and the positive terminal plate 180 are also preferably nickel-plated steel. The current collector 160 may be selected from a variety of known conductive metals that have been found useful as current collector materials, such as brass, tin plated brass, bronze, copper, or indium plated brass. The insulating sealing member 220 is preferably made of nylon 66 or nylon 612.

  The following are specific examples showing comparative performance using rectangular batteries of the same size with different battery balances. The new battery had a thickness of 5.6 mm, a width of 17 mm, and a length of 67 mm in each case. (Unless otherwise specified, all dimensions are unlabeled outer diameter dimensions around the casing.) The casing wall thickness was the same at 0.38 mm for each of the cells tested. The casing 100 for each battery was nickel plated steel whose inner surface was coated with graphitic carbon. As depicted in the drawings (FIGS. 1-5), the cell structure was the same in each case. The edge of the wide portion (flange 161) of the anode current collector 160 was about 0.5 mm from the inner surface of the casing 100. The surrounding skirt 226 of the insulating sealing member 220 may surround the wide portion (flange 161) of the current collector 160, thereby providing a barrier between it and the inner wall of the casing 100.

All battery components were the same as above, and each battery tested had a vented end cap assembly 12 as shown in the drawings. The only difference was in cell balance and anode composition. The comparative cell (Comparative Example) is MnO divided by the equilibrium ratio, ie, the milliamp-hour capacity of zinc (based on 820 milliamps-hour zinc per gram) (based on 370 milliamps-hour capacity MnO ₂ per gram). The theoretical capacity of ₂ was equilibrated to be 1.1. The test cell of Test Example 1 was equilibrated such that the equilibrium ratio, ie, the theoretical capacity of MnO ₂ divided by the theoretical capacity of zinc, was 1.25. The test cell of Test Example 2 was equilibrated so that the theoretical capacity of MnO ₂ divided by the theoretical capacity of zinc was 1.6 and 2.0, respectively.

  The comparative and test cells in the following examples were intermittently discharged at a 90 milliwatt period with power on and subsequent 3 hours power off until a cut-off voltage of 0.9 volts was reached. (Such intermittent discharges typically simulate the typical use of a portable solid state digital audio player that can use the MP3 audio format.) The actual total usage time is then recorded. The amount of expansion of the battery casing was evaluated and recorded.

Comparative Example (Comparative Battery)
A comparative test battery 10 having a rectangular (cubic) structure and an end cap assembly shown in the drawings was prepared. The battery, as defined by the casing 100 outer diameter, had a length of about 67 mm, a width of about 17 and a thickness of about 5.6 mm (before discharge). The anode 150 and the cathode 110 had the following compositions.

Anode composition:
Wt%
Zinc ¹ 70.0
Surfactant ² 0.088
(RA600)
Electrolyte ³
(9 normal KOH) 29.91
100.00

Note:
1. The zinc particles had an average particle size of about 150 microns and were alloyed and plated with indium to provide a total indium content of about 200 ppm.
2. Organophosphate group surfactant solution RA600 from Rhone Poulenc
3. The electrolyte contained gelling agents Waterlock A221 and Carbopol C940, which together constitute approximately 1.5 wt% of the electrolyte solution.

Cathode composition:
Wt%
MnO ₂ (EMD) 87.5
(Kerr McGee
From Trona D)
Graphite ¹
(NdG15 natural graphite) 7.4
Electrolytes
(9 normal KOH) 5.1
100.00

Note:
1. Graphite NdG15 is natural graphite from Nacional De Grafite.

The casing 100 wall thickness for the battery was 0.38 mm. The new battery had a length of 67 mm, a thickness of 5.6 mm, and a width of 17 mm. The anode 150 and cathode 110 of the cell, is - (based on MnO ₂ times grams per 370 mA) theoretical capacity of MnO ₂ to (grams per 820 mA - - based on zinc time) milliamperes of zinc was divided by the time capacitor Equilibrated to be 1.1. The anode had 2.8 grams of zinc. (The cathode had 6.89 grams of MnO _2. ) The anode 150, cathode 110, and separator 140 constituted about 66% of the external capacity of the casing 100 of the structure shown in FIGS. 1 and 1A. The ratio of anode thickness to casing outer thickness was about 0.35. Thickness is measured along a plane perpendicular to the longitudinal axis 190 across the outer thickness (small dimension) of the cell.

  The cell was discharged intermittently at a 90 milliwatt period with “power on” followed by 3 hours “power off” until a cut-off voltage of 0.9 volts was reached. The actual service life was 24.5 hours. The casing expanded from a thickness of 5.6 mm to a thickness of 6.13 mm. (Thickness was measured between the outer surfaces of the side walls 106a, 106 shown in FIG. 1A.)

Test battery example 1
A test battery having a rectangular structure and the same size as in the comparative example was prepared. The anode 150 and the cathode 110 had the following composition.

Anode composition:
Wt%
Zinc ¹ 66.0
Surfactant ² 0.083
(RA600)
Electrolyte ³
(9 normal KOH) 34.0
100.08

Note:
1. The zinc particles had an average particle size of about 150 microns and were alloyed and plated with indium to provide a total indium content of about 200 ppm.
2. Organophosphate group surfactant solution RA600 from Rhone Poulenc
3. The electrolyte contained gelling agents Waterlock A221 and Carbopol C940, which together constitute approximately 1.5 wt% of the electrolyte solution.

Cathode composition:
Wt%
MnO ₂ (EMD) 87.5
(Kerr McGee
From Trona D)
Graphite ¹
(NdG15 natural graphite) 7.4
Electrolytes
(9 normal KOH) 5.1
100.00

  1. Graphite NdG15 is natural graphite from Nacional De Grafite.

The casing 100 wall thickness for the battery was 0.38 mm. The new battery had a length of 67 mm, a thickness of 5.6 mm, and a width of 17 mm. The anode 150 and cathode 110 of the cell, is - (based on MnO ₂ times grams per 370 mA) theoretical capacity of MnO ₂ to (grams per 820 mA - - based on zinc time) milliamperes of zinc was divided by the time capacitor Equilibrated to be 1.25. The anode had 2.56 grams of zinc. (The cathode had 7.11 grams of MnO _2. ) The anode 150, cathode 110, electrolyte, and separator 140 were measured in other words between the closed end 104 and the open end 102 of the casing. When constructed, it constituted about 66% of the external capacity of the casing 100. The ratio of anode thickness to casing outer thickness was about 0.35. Thickness is measured along a plane perpendicular to the longitudinal axis 190 across the outer thickness (small dimension) of the cell.

  The cell was discharged intermittently at a 90 milliwatt period with “power on” followed by 3 hours “power off” until a cut-off voltage of 0.9 volts was reached. The actual service life was 24.3 hours. The casing expanded from a thickness of 5.6 mm to a thickness of 6.03 mm. (Thickness was measured between the outer surfaces of the side walls 106a, 106 shown in FIG. 1A.) The usage time was almost the same as in the comparative example, but the casing expansion was less.

Test battery example 2
A test battery having a rectangular structure and the same size as in the comparative example was prepared. The anode 150 and the cathode 110 had the following composition.

Anode composition:
Wt%
Zinc ¹ 60.0
Surfactant ² 0.083
(RA600)
Electrolyte ³
(9 normal KOH) 39.92
100.00

Note:
1. The zinc particles had an average particle size of about 150 microns and were alloyed and plated with indium to provide a total indium content of about 200 ppm.
2. Organophosphate group surfactant solution RA600 from Rhone Poulenc
3. The electrolyte contained gelling agents Waterlock A221 and Carbopol C940, which together constitute approximately 1.5 wt% of the electrolyte solution.

Cathode composition:
Wt%
MnO ₂ (EMD) 87.5
(Kerr McGee
From Trona D)
Graphite ¹
(NdG15 natural graphite) 7.4
Electrolytes
(9 normal KOH) 5.1
100.00

  1. Graphite NdG15 is natural graphite from Nacional De Grafite.

The casing 100 wall thickness for the battery was 0.38 mm. The new battery had a length of 67 mm, a thickness of 5.6 mm, and a width of 17 mm. The anode 150 and cathode 110 of the cell, is - (based on MnO ₂ times grams per 370 mA) theoretical capacity of MnO ₂ to (grams per 820 mA - - based on zinc time) milliamperes of zinc was divided by the time capacitor Equilibrated to be 1.6. The anode had 2.01 grams of zinc. (The cathode had 7.13 grams of MnO _2. ) The anode 150, cathode 110, and separator 140 constituted about 66% of the external capacity of the casing 100. The ratio of anode thickness to casing outer thickness was about 0.35.

  Thickness is measured along a plane perpendicular to the longitudinal axis 190 across the outer thickness (small dimension) of the cell.

  The cell was discharged intermittently at a 90 milliwatt period with “power on” followed by 3 hours “power off” until a cut-off voltage of 0.9 volts was reached. The actual service life was 20.9 hours. The casing expanded from a thickness of 5.6 mm to a thickness of 5.95 mm. (Thickness was measured between the outer surfaces of the side walls 106a, 106 shown in FIG. 1A.)

Test battery example 3
A test battery having a rectangular structure and the same size as in the comparative example was prepared. The anode 150 and the cathode 110 had the following composition.

Anode composition:
Wt%
Zinc ¹ 52.0
Surfactant ² 0.083
(RA600)
Electrolyte ³
(9 normal KOH) 47.92
100.00

Note:
1. The zinc particles had an average particle size of about 150 microns and were alloyed and plated with indium to provide a total indium content of about 200 ppm.
2. Organophosphate group surfactant solution RA600 from Rhone Poulenc
3. The electrolyte contained gelling agents Waterlock A221 and Carbopol C940, which together constitute approximately 1.5 wt% of the electrolyte solution.

Cathode composition:
Wt%
MnO ₂ (EMD) 87.5
(Kerr McGee
From Trona D)
Graphite ¹
(NdG15 natural graphite) 7.4
Electrolytes
(9 normal KOH) 5.1
100.00

  1. Graphite NdG15 is natural graphite from Nacional De Grafite.

The casing 100 wall thickness for the battery was 0.38 mm. The new battery had a length of 68 mm, a thickness of 5.6 mm, and a width of 17 mm. The anode 150 and cathode 110 of the cell, is - (based on MnO ₂ times grams per 370 mA) theoretical capacity of MnO ₂ to (grams per 820 mA - - based on zinc time) milliamperes of zinc was divided by the time capacitor Equilibrated to be 2.0. The anode had 1.61 grams of zinc. (The cathode had 7.13 grams of MnO _2. ) The anode 150, cathode 110, and separator 140 constituted about 66% of the external capacity of the casing 100. The ratio of anode thickness to casing outer thickness was about 0.35. Thickness is measured along a plane perpendicular to the longitudinal axis 190 across the outer thickness (small dimension) of the cell.

  The cell was discharged intermittently at a 90 milliwatt period with “power on” followed by 3 hours “power off” until a cut-off voltage of 0.9 volts was reached. The actual service life was 18.5 hours. The casing expanded from a thickness of 5.6 mm to a thickness of 5.87 mm. (Thickness was measured between the outer surfaces of the side walls 106a, 106 shown in FIG. 1A.)

In the above test, the same size flat cells were gradually balanced at higher equilibrium ratios. The edge of the wide portion (flange 161) of the anode current collector 160 was about 0.5 mm from the inner surface of the casing 100 and was surrounded by an insulating barrier 226. The equilibrium ratio was defined as the theoretical capacity of MnO ₂ (based on 370 milliamp-hour MnO ₂ per gram) divided by the milliamp-time capacity of zinc (based on 820 milliamp-hour zinc per gram). In the above comparative test, when the equilibrium ratio of the battery (theoretical capacity of MnO ₂ with respect to the theoretical capacity of zinc) is about 1.1, the expansion of the flat test battery is 5.6 mm to 6.13 mm in overall thickness. Markedly increased. In Test Example 1 (equilibrium ratio of 1.25), the battery has less expansion, ie, 5.6 mm to 6.03 mm. In Test Example 2 (1.6 equilibrium ratio), the cell expanded from 5.6 mm to 5.95 mm. In Test Example 3 (equilibrium ratio of 2.0), the expansion of the battery was less, from 5.6 mm to 5.87 mm. As the equilibrium ratio increases between 1.1 and 1.6, the service life of the battery decreases slowly (from 24.5 hours to 20.9 hours) and becomes more with a maximum equilibrium ratio of 2.0. Remarkably reduced.

Another preferred embodiment of the present invention is shown in FIGS. A reusable or re-activatable venting mechanism such as the receiptable plug 260 is desirable, but can be removed as in the embodiment shown in FIGS. The receiptable plug 260 can be removed and cracked at a pressure P1 between the activation pressure of the receiptable plug, ie preferably between about 100-300 psig (689 × 10 ^{3 to} 2068 × 10 ³ Pascals). Alternatively, it has already been pointed out above that a weak laser weld can be used as the main venting mechanism that bursts. In such cases (where the receiptable plug has been eliminated), the supplemental venting mechanism may be a thin material region located below the groove (groove 600a or 600b) on the casing surface. Stated in. The thin-walled material can be designed to rupture at a higher pressure level P2.

As shown in the embodiment of FIGS. 10-17, one or more groove vents, preferably a single groove vent 600a or 600b, may be used as the main vent mechanism. In such a case, a single groove vent, such as 600a or 600b, can be cut or scribed into the casing surface so that the thin wall region located where possible is ruptured at pressure P1. Preferably, the single groove vent 600b can be located near the closed end of the casing near the positive terminal 180, as shown in FIG. 10A. The groove boundary can be closed or opened. In this preferred embodiment, the groove may be straight or substantially straight, preferably parallel to the wide edge 108a of the casing (FIGS. 8 and 8A). For example, a 7 / 5-F6 size rectangular battery may have a groove vent 600b located on the wide side 106a of the casing (FIG. 10A). In a preferred embodiment, the groove vent 600b includes a unique groove vent on the casing surface. As a non-limiting example, the groove 600b can be a straight groove parallel to the closed end of the battery (FIG. 10A). Preferably, both ends of the straight groove 600b may be equidistant from the narrow side surface of the casing. In such a preferred embodiment, as shown in FIG. 10A, the groove 600b is about 8 mm long and about 5-10 mm from the closed end 104 of the casing. Although a straight groove 600b is desirable, it is not intended to limit such a groove to such a structure. It will be appreciated that the groove vent 600b may have a curved shape or other structure such as partially straight and partially curved to form an open or closed boundary pattern.

The groove 600b (FIG. 10A) in which the thin material is located ruptures when the gas pressure in the battery reaches a design explosion pressure between about 250-800 psig (1724 × 10 ^{3 to} 5515 × 10 ³ Pascal gauge). Can be designed as follows. To achieve such a range in explosion pressure between about 250-800 psig (1724 × 10 ^{3 to} 5515 × 10 ³ Pascal gauge), the groove 600b under which the thin-walled material is located is about 0.04-0. Have a thickness of between 15 mm. Alternatively, the groove 600b in which the thin material is located ruptures when the gas pressure in the battery reaches a design explosion pressure between about 400-800 psig (1758 × 10 ^{3 to} 5515 × 10 ³ Pascal gauge). Can be designed as follows. To achieve such an explosive pressure between about 400-800 psig (1758 × 10 ^{3 to} 5515 × 10 ³ Pascal gauge), the groove 600b under which the thin material is located is about 0.07-0.15 mm. Having a thickness of The width of the groove 600b (FIG. 10A) is typically between about 0.1-1 mm, more typically between about 0.1-0.5 mm at its base (adjacent thinned region 610). It can be. Within such a range, the burst pressure is controlled primarily by the thickness of the thin region located below. However, it will be appreciated that wider grooved or cut areas with a thinned area located below the casing are also possible.

The groove 600b can be created by punching the surface of the casing 100 with a mold, preferably a mold having a cutting knife edge. When the punching die pierces the casing outer surface, the mandrel is held against the inner surface of the casing. The groove 600b can be cut into a V shape having an isometric side surface as shown in FIG. 9, or a V shape having an unequal length side surface as shown in FIG. In the former case (FIG. 9), the side surface forming the V-shaped groove preferably has an acute angle α of about 40 degrees, and in the latter case (FIG. 15) it has an angle between about 10 and 30 degrees. Is preferred. Along with the groove 600b, there may be one or more laser welds that secure the metal cover 230 to the casing 100. Such a weld may be composed of one or both of a weak laser weld and a strong laser weld that may be designed to burst at a pressure higher than the burst pressure of the groove 600b below which the thin wall region is located. As described above, such laser welding can be done using a Nd: Yag laser. The arrangement of adjacent weak and strong laser welds used to secure the metal cover 230 to the casing 100, eg, welds 310a and 310b, was shown and described with reference to FIGS. 6 and 6A. . In the preferred embodiment, there can be only one laser weld, ie, a strong weld 310b that secures the entire periphery of the metal cover 230 to the casing 100, as shown in FIG. The strong weld 310 is under catastrophic conditions, for example if the battery is inadvertently under very high current or suddenly gas evolution within the battery is about 800 psig to 2500 psig (5515 × 10 ^{3 to} 17235 × 10 ³ It can be designed to rupture if exposed to charging under extremely illicit conditions such as raising to a level between Pascal Gauge).

Thus, in the modified preferred battery embodiment shown in FIGS. 10 and 13, the single groove 600b functions as the main ventilation mechanism of the battery, in which case the thin-walled material 610 (FIGS. 9 and 15). The groove 600b is located below, so that the gas in the cell is between about 250-800 psig (1724 × 10 ^{3 to} 5515 × 10 ³ Pascal gauge), more typically about 400-800 psig (2758 × 10 ³ It is designed to rupture if it rises to a level between ˜5515 × 10 ³ Pascal Gauge). And the strong laser weld 310b (FIG. 10) which fixes the edge of the metal cover 230 to the casing 100 is designed to function as a supplementary ventilation system for the battery. Such a strong laser weld 310b is designed to crack or rupture in catastrophic situations, such as when the gas pressure in the battery suddenly rises to a level between about 800 psig and 2500 psig.

  The battery shown in FIGS. 10 and 10A is shown as a cross section of FIG. 11 taken through a plane parallel to the wide side 106a and a cross section of FIG. 12 taken through a plane parallel to the narrow side 107a. . As shown in FIGS. 11 and 12, the receiptable plug 260 incorporating the specific embodiment described above (FIGS. 2 and 4) has been removed. It is also possible to remove the associated members forming the battery end cap assembly 12, i.e., to remove the vent pip cap 270 and plastic spacer disk 250 shown in the previous embodiment (Figs. 2 and 4). The reduction in the number of components forming the end cap assembly 12 is also reflected in FIG. 13, which is an exploded view of the internal components of the battery. Thus, in a modified embodiment (FIGS. 10-13), the rivet 240 can be welded directly to the negative terminal plate 290, as best shown in FIGS.

  The welding of the rivet 240 to the negative terminal plate 290 can be efficiently performed by electrical resistance welding. Rivet 240 is preferably brass, and desirably is brass plated with a layer of tin, typically about 1-3 microns thick. Negative terminal plate 290 is preferably nickel plated cold rolled steel. When the thickness of the terminal plate 290 is about 4 mils (0.102 mm) at the welding site, it has been determined that welding can be done most efficiently and that uniform welding can be easily achieved. For overall strength, it is desirable that the remainder of the terminal plate 290 be thicker, preferably about 8 mils (0.204 mm). Because 8 mil thick cold rolled steel plates are commercially available, a mandrel is used to reduce the thickness of the plate at the welding site to about 4 mils (0.102 mm). It has been determined that the central portion 290a (FIG. 13), ie, the weld area, can be easily stamped. Punching is preferably done from the top surface of the terminal plate 290 (FIG. 13) to form a punching area. Such a procedure leaves the remaining 290b (FIG. 13) thickness of the terminal plate 290 at its original 8 mil (0.204 mm) thickness.

  The central portion 290a (FIG. 13) of the terminal plate 290 can be stamped into a variety of structures, for example, rectangular, circular, or elliptical. In the case of a rectangular or elliptical punching area 290a, the long dimension of the punching area 290a (in the direction of the wide side of the casing) is larger than the rivet head 247 diameter to allow placement of the welding electrode (not shown) Must be somewhat bigger. For example, using a 3 mm diameter rivet head 247, the long dimension of the punch region 290a is about 4 mm, and the long dimension of the punch region 290a is between about 3-4 mm. If the punched area is circular, if the rivet head 247 diameter is about 3 mm, the diameter can be between about 3-4 mm.

When assembling the planar alkaline battery 10 of the modified embodiment (FIGS. 10-13), the anode material 150 containing zinc and the cathode material containing MnO ₂ have an open end with a separator 140 therebetween. It is inserted into the battery casing 100 through the part 102. The end cap assembly 12 (FIG. 13) is formed by inserting the metal cover 230 over the insulating sealing member 220 such that the protruding head 221 of the insulating sealing member is inserted into the opening 234 of the metal cover 230. Is done. Next, the rivet shaft 240 is inserted into the metal cover 230 through the opening 234 (FIG. 13). The rivet shaft 240 is insulated from the metal cover 230 by the protruding head 221 of the insulating sealing member 220. The top flange portion 161 of the anode current collector, preferably made of brass, is pushed up against the bottom surface of the sealing member 220 and fastened to the bottom of the rivet 240, preferably made of brass or tin-plated brass, by conventional riveting techniques. Thus, the current collector 160 is electrically connected to the rivet 240. To facilitate fastening the anode current collector to the rivet 240, the current collector flange 161 has an opening 164, and the rivet 240 also has an opening 249a. (As shown in FIGS. 11 and 12, the upper portion 249 b of the rivet 240 is preferably solid.) After the current collector 160 is fastened to the rivet 240, the sealing member 220 includes the current collector flange 161 and the metal cover 230. It is wedged between the bottom surface.

As best shown in FIGS. 10 and 11, the metal cover 230 is welded to the inner surface of the casing 100 by a strong laser weld (preferably a burst pressure between 800-2500 psig). The central portion of the metal cover 230 is pushed or pressed to form a pond region 235 (FIG. 11). Sealing material 236, preferably asphalt sealant available under the trade name KORITE Asphalt Sealants (Customer Products), is applied to the pressed pond area 235 on the surface of the metal cover 230 (FIG. 11). And 13). KORITE asphalt sealant is an uncured asphalt composed of a mixture of about 55-70 wt% asphalt and 30-45% asphalt. As the encapsulant is applied, the viscosity of the encapsulant can be adjusted by adjusting the asphalt / solvent ratio and the encapsulant temperature. The pond area 235 and rivet head 247 in the cover plate 230 are preferably heated before the asphalt sealant is injected into the pond area 235. Desirably, the asphalt sealant has a viscosity of about 1000 centipoise when injected into the pond region 235. The asphalt fills the recessed area 235 and provides additional sealing protection between the rivet 240 and the sealing member 220. Next, a subassembly consisting of metal cover 230, rivet 240, and insulating sealing member 220 is inserted into the open end of the casing so that current collector shaft 162 penetrates into anode material 150 (FIG. 11). And 12). After the periphery of the metal cover 230 is laser welded to the casing 100, a plastic extender seal 280 (FIG. 13) can be inserted over the rivet 240. This is done by inserting the rivet head 247 through the opening 282 of the plastic extender 280. The flat negative metal plate is then placed on the top surface of the plastic extender 280 so that the flat negative metal plate 290 contacts the protruding rivet head 247. Next, the negative plate 290 is welded to the rivet head 247 to complete the construction of the end cap assembly 12. The completed end cap assembly 12 in the battery 10 is shown in FIGS.

  When laser welding the edge of the metal cover 230 to the casing 100, it is preferable to apply a heat transfer medium, preferably a liquid or metal, to the metal cover. The heat transfer medium is preferably a liquid that can be conveniently placed in a pond or trough region 235 on the surface of the metal cover 230. Such a heat transfer medium can absorb a significant portion of the heat generated during laser welding. In this way, sufficient heat may be absorbed to prevent the metal cover 230 from reaching a temperature above about 100 ° C. during the welding period when using Nd: Yag (or equivalent). Alternatively, the metal cover can be pre-cooled to a temperature below ambient room temperature (21 ° C.), preferably close to the freezing point of water and even lower. Such pre-cooling prevents the metal cover 230 from exceeding 100 ° C. during the welding operation. In addition, the metal cover 230 can be pre-cooled and a heat transfer medium can also be applied to the metal cover 230.

  The plastic extender seal 280 is press fitted into the casing 100 on the metal cover 230. If the metal cover 230 does not continue to cool sufficiently during laser welding, the seal 280 can in some cases overheat to a point that adversely affects its physical properties. This results in a loss of radial compression, i.e., a loose tight fit between the seal 280 and the casing 100, and then the electrolyte can leak into the area between the metal cover 230 and the metal cover 280. Provides a passage to the outside of the casing. Therefore, it is recommended that the metal cover 230 be kept cool enough or that a heat transfer medium be applied to the metal cover to ensure that sufficient heat is absorbed during the laser welding operation. A convenient way to accomplish this is to add a small amount of cooled deionized water to the trough region 235 of the metal cover 230, for example at about 5-10 ° C. This keeps the temperature of the metal cover 230 below about 100 ° C. and then allows the seal (FIGS. 11 and 12) to remain within a suitable operating temperature. (After the laser welding operation, a sealant, eg, asphalt sealant, can be added to the pond area in the manner described above.) Alternatively, a metal block (optionally precooled) is attached to the metal cover. 230 can be applied in contact. In order to ensure that the metal cover 230 does not reach temperatures above 100 ° C., a metal block, typically made of steel, can absorb sufficient heat during the welding operation.

  It will be appreciated that water may be added to keep the metal cover 230 cool during laser operation, although other suitable coolants may be used. For example, instead of pure water, a cooling aqueous solution of polyvinyl alcohol and potassium hydroxide can be used. The polyvinyl alcohol coats outside the surface of the metal cover 230, thereby providing additional sealing protection between the metal cover 230 and the seal 280. Such a solvent can be applied directly to the lower surface of the plastic seal 280 (FIGS. 11 and 12), thereby providing additional sealing protection to the lower surface of the seal 280.

  Alternatively, a gelling agent can be added to the cooling aqueous solution applied to the pond 235. The term gelling agent is intended to include superabsorbents as well as conventional gelling agents. Such gelling agents include polyacrylic acid, polyacrylate, sodium salt of acrylic acid copolymer, carboxymethylcellulose, sodium carboxymethylcellulose, starch graft copolymer, and the like. The gelling agent coats the surface of the metal cover 230 to provide additional sealing protection between the metal cover 230 and the seal 280. Using a compression roller and the like (FIGS. 11 and 12), the gelling agent can be applied as a powder to the lower surface of the plastic seal 280, thereby coating the seal 280 with the gelling agent and adding Can provide sealing protection.

  In the embodiment shown in FIG. 17 using a paper washer 295 instead of the plastic seal 280, the paper washer can be pre-impregnated with an aqueous solution containing a gelling agent or an aqueous solution of polyvinyl alcohol and potassium hydroxide. Such pre-wetting of the paper washer 295 provides additional sealing protection if the electrolyte leaks into the area between the metal cover 230 and the terminal plate 290 (FIG. 17). In addition, a separate layer containing gelling agent powder can be pressed against the underside of washer 295 using a compression roller and the like, or as described in US Pat. No. 4,999,264. Can be dispersed in a fiber network comprising washers 295.

  A separate protruding metal member 180 may be welded to the opposite closed end 104 of the battery. In the completed battery 10 (FIGS. 10-13), the metal member 180 is in electrical contact with the battery casing, thus forming the positive terminal of the battery. End plate 290 is in electrical contact with rivet 240, which in turn is in electrical contact with anode current collector 160, thus forming the negative electrode of the battery.

  Although the present invention has been described in detail with respect to specific embodiments, it will be understood that various designs of specific components are possible and are intended to be within the scope of the inventive concept. . For example, current collector 160 (FIGS. 4 and 13) is shown as an elongated member in the form of a nail, with the top end terminating in a horizontally extending flange 161, which includes an opening 164 therethrough. This design is attractive because it facilitates fastening the top flange 161 of the current collector 160 to the bottom surface of the rivet 240 (FIG. 11). This is accomplished by conventional riveting techniques, where the rivet bottom surface 249 can be inserted into the flange opening 164 and then crimped to secure the current collector flange 161 to the rivet 240. In such a design, the current collector shaft is eccentric, in other words, not located along the central longitudinal axis of the battery. Such eccentricity does not appear to significantly interfere with the efficient discharge of the anode or the overall performance of the battery. The current collector shaft 162 is shown as a straight nail in the embodiment of FIG. 4 and in the embodiment shown in FIG. 13 as a straight nail having a curved surface. In either case, the nail is eccentric from the central longitudinal axis 190 of the battery, for example as shown in FIG.

  It will be appreciated that other current collector designs are possible. For example, the rivet 240 has a head portion 247 (FIG. 11) with an integrally formed elongated shaft portion (not shown) in the form of a nail that extends downward from the head 247 and at least partially enters the anode 150. It can be a solid member. In such a case, the current collector shaft can be positioned to lie along the central longitudinal axis 190 of the cell. Such a rivet head 247 can still be welded to the terminal end plate 290 in the manner described above.

  Another specific embodiment of the planar battery of the present invention is shown in FIG. In this embodiment, instead of the plastic extender 280, for example, a craft paper washer 295 may be used between the metal cover 230 and the negative terminal plate 290. The craft washer is durable and provides the required electrical insulation between the metal cover 230 and the terminal plate 290. Such a design reduces the height of the rivet head 247, thereby compacting the overall height of the end cap assembly 12. It also has the advantage of eliminating the need to mold the plastic extender 280. This in turn results in more available volume for the anode / cathode activation material inside the cell. (Other components of the battery shown in FIG. 17 are essentially the same as those described for the battery shown in FIGS. 10-12). The rivet 240 shown in FIG. 17 with a separate current collector 160 fastened to the rivet, for example, with an integral elongate current collector 160 in the form of a nail that extends from the current collector and enters at least a portion of the anode. Can be replaced with a single rivet. Such an integral current collector can be centrally positioned along the central longitudinal axis 190 of the cell.

  It will be appreciated that each embodiment of the battery is intended to have a conventional film label around which the battery casing is wrapped. Suitable plastic films for such labels are known in the art and typically include polyvinyl chloride. The label can be imprinted with the desired design or display. Such labels are typically coated with an adhesive at the ends and can be applied by wrapping around the casing surface. Alternatively, the label can be applied in the form of a sleeve and heat shrunk on the casing surface. A typical label 12 is shown in FIG.

Separator Assembly In the battery embodiment shown in FIGS. 10-13, separator 140 may be conventionally formed from separator material conventionally used in alkaline batteries. For example, it typically consists of cellulose or cellulose derivatives and polyvinyl alcohol fibers. Battery 10 (FIGS. 10-13) may typically be in the shape of a cube having a thickness of about 16 mm, a width of about 17 mm, and a length of about 35-67 mm. The desired separator is composed of a double layer, the outer layer (facing the cathode 110) contains cellulose derivatives and polyvinyl alcohol fibers, and the inner layer facing the anode 150 contains a cellulosic material such as rayon. After the cathode disk 110 is inserted into the casing through the open end 102 (FIG. 11), the separator 140 is inserted such that the separator is exposed to the cathode surface.

  Separator 140 for use in the above-described planar cell (FIGS. 10-13) is conventionally made by rolling a planar separator sheet, as shown in FIGS. 14 and 14B. First, the proximal end portion 140a is folded inward in the direction of F1 along the bending line 140b displaced by about 3 to 5 mm from the edge portion 140a. A mandrel (not shown) may be placed against the separator surface 140d. Next, the far edge 140c of the separator is wrapped around the mandrel so that the far edge 140c passes around the edge 140a, resulting in the partially wrapped structure shown in FIG. 14A. The far edge portion 140c is continuously wound in the F2 direction on the separator surface (FIG. 14A). The edge 140c may be fixed to the separator surface in an adhesive manner. Next, the bottom separator edge 142 is folded inward about 3 mm over the back of the separator and is adhesively secured thereto, as shown in FIG. 14B. By simply folding the bottom separator edge 143c in the F3 direction and then pressing it to form a bag structure as shown in FIG. 14B, the edge 140c and / or the bottom separator edge 142 are The use of adhesive to fix can be eliminated. When the folded separator is inserted into the casing, the cathode shape also helps to hold the separator in the bag structure shown in FIG. 14B. The mandrel (not shown) is removed. The resulting wrapped separator 140 (FIG. 14B) is in the form of a bag having a closed interface 148 with a closed end 143 opposite the open end 144. Separator interface 148 defines a cavity 155 for insertion of anode material therein.

  After the cathode disk 110a is inserted into the battery casing 100, the separator 140 wound around the structure shown in FIG. 14B is inserted so that the surface of the separator faces the exposed cathode surface. Separator interface 148 forms an anode cavity 155. The anode cavity 155 preferably has an oval structure as shown in FIG. 14B. The short dimension of the oval structure of the cavity 155 is typically between about 2-3 mm for a battery 10 having an overall thickness of about 6 mm in a cubic structure. Preferably, the long dimension of the oval structure is somewhat less than the width of the space available in the cell for the entire anode cavity. This creates a gap 145 between the short side of the separator and the cathode disk 100a, as shown in FIG. The gap 145 is between about 2-4 mm, preferably between about 2-3 mm. The anode material 150 is then filled into the anode cavity 155 through the separator's open end 143 so that the casing 100 is filled with the anode material 150, the cathode material 110, and the separator 140 therebetween. In that case, there is a gap 145 (a void) between one short side of the separator and the cathode, as shown in FIG.

It has been determined that additional alkaline electrolyte can be added to the cell interior by dispensing directly into the gap 145, if desired. Additional electrolyte can be dispensed by inserting a dispensing nozzle directly into the gap. In a preferred embodiment, a small amount of additional electrolyte can be added into gap 145 after anode 150 and cathode 110 are in place in the cell. In an alternative embodiment, after the cathode is in place, before the anode material is inserted into the anode cavity, it may be made a part of the additional electrolyte into the gap 145. The anode material can then be inserted into the battery's anode cavity, after which a final amount of electrolyte can be added into the gap 145. In any case, the additional electrolyte helps improve anode utilization (percentage of active anode discharged) and overall battery performance. It can also be a factor that tends to inhibit battery expansion.

  The addition of electrolyte to gap 145 between separator 140 and cathode 110 as described above avoids overflow problems that can occur if electrolyte is added directly to the anode. For example, if there is initially no gap between separator 140 and cathode 110, and additional electrolyte is added to the interior of the cell, there may be electrolyte overflow to void 146 (FIG. 11) on anode 150. Such overflow is undesirable. This is because it causes wetting along the lower surface or edge of the metal cover 230 after the metal cover 230 is in place over the open end 102 of the battery. Such wetting then adversely affects proper leather welding of the metal cover 230 to the casing 100.

  If additional electrolyte is added to the gap 145, it is recommended that it be done in incremental steps. For example, if additional electrolyte is added to gap 145 after anode 150, cathode 110, and separator 140 are inserted into the casing, such additional electrolyte may be dispensed in multiple dispensing steps. It is recommended that incremental additions be allowed to allow time lapses typically between about 1 to 4 minutes between dispensings. This allows the time for each incremental amount of electrolyte to be absorbed by the anode, separator, and cathode, reducing the possibility of any overflow occurring that could prevent proper welding of the metal cover 230. . If the battery is a rectangular 7 / 5-F6 size battery, the amount of additional electrolyte to be added to the gap 145 is typically below about 1 gram. Preferably, in each such case, about 1-4 minutes between dispensings to allow sufficient time for the incremental amount of electrolyte to be properly absorbed by the anode, cathode, and separator. With the time interval between, the electrolyte can be added in about 4 incremental equal doses. Surprisingly, it has been discovered that when the entire additional electrolyte is dispensed into the gap 145, the anode 150 expands sufficiently to expand the anode cavity 155 bounded by the separator surface 148. It was done. As the anode 150 expands, the separator surface 148 is pressed flush against both the anode and cathode, thereby completely closing the gap 145.

  A performance test of a battery 10 made in accordance with the embodiment shown and disclosed with reference to FIGS. 10-16 was made and reported in Test Battery Example 4 below.

Test battery example 4
A rectangular structure in the embodiment shown in FIGS. 10 to 13 and a test battery of the same size as in the comparative example were prepared. The amount of zinc in the anode was 2.01 grams and the amount of MnO ₂ was 6.69. The anode 150 and the cathode 110 had the following composition.

Anode composition:
Wt%
Zinc ¹ 60.0
Surfactant ² 0.075
(RM510)
Electrolyte ³
(9 normal KOH) 39.9
100.00

Note:
1. The zinc particles had an average particle size of about 150 microns and were alloyed and plated with indium to provide a total indium content of about 200 ppm.
2. Organophosphate group surfactant solution RM510 from Rhone Poulenc
3. The electrolyte contained gelling agents Waterlock A221 and Carbopol C940, which together constitute approximately 1.5 wt% of the electrolyte solution.

Cathode composition:
Wt%
MnO ₂ (EMD) 84.0
(Kerr McGee
From Trona D)
Graphite ¹
(NdG15 natural graphite) 10.0
Electrolytes
(9 normal KOH) 6.0
100.00

  1. Graphite NdG15 is natural graphite from Nacional De Grafite.

  After the anode and cathode are in place in the cell casing, an additional total of 0.82 grams of 9N KOH charge quality is produced in 4 dispenser increments (0.205 grams per increment) with separator 140 And a gap 145 between the cathode (FIG. 6). The time interval between dispensing increments was between about 1-4 minutes. The addition of a total of 0.82 grams of electrolyte did not significantly change the anode and cathode composition described above. Part of the added electrolyte was absorbed into the anode, the other part was absorbed into the cathode, and part was absorbed into the separator. The electrolyte added to gap 145 causes the anode to expand, thereby closing gap 145. This technique allows additional electrolyte to be added to the anode without causing any overflow of electrolyte to the void 146 on the anode. Such electrolyte overflow is undesirable. This is because it causes the edge of the metal cover 230 to be compliant, which in turn can prevent proper welding of the cover 230 to the battery casing.

The casing 100 wall thickness for the battery was 0.38 mm. The new battery had a length of 67 mm, a thickness of 5.6 mm, and a width of 17 mm. The anode 150 and cathode 110 of the cell, is - (based on MnO ₂ times grams per 370 mA) theoretical capacity of MnO ₂ to (grams per 820 mA - - based on zinc time) milliamperes of zinc was divided by the time capacitor Equilibrated to be 1.5. The anode had 2.01 grams of zinc. (The cathode had 6.69 grams of MnO _2. ) The anode 150, cathode 110, and separator 140 constituted about 66% of the external capacity of the casing 100. The ratio of anode thickness to casing outer thickness was about 0.35.

  Thickness is measured along a plane perpendicular to the longitudinal axis 190 across the outer thickness (small dimension) of the cell.

  The cell was discharged intermittently at a 90 milliwatt period with “power on” followed by 3 hours “power off” until a cut-off voltage of 0.9 volts was reached. The actual service life was 20.1 hours. The casing expanded from a thickness of 5.6 mm to a thickness of 5.99 mm. (Thickness was measured between the outer surfaces of the side walls 106a, 106 shown in FIG. 1A.)

In a comparative test, when the equilibrium ratio of the cell (theoretical capacity of MnO ₂ with respect to the theoretical capacity of zinc) is about 1.1, the expansion of the planar test battery is significantly greater than the overall thickness of 5.6 mm to 6.13 mm. Increased. In Test Example 4 above (1.5 equilibrium ratio), the battery has less expansion, ie, 5.6 mm to 6.03 mm. In Test Example 4 (1.5 equilibrium ratio), the cell expanded from 5.6 mm to 5.99 mm.

  While the preferred embodiment of the present invention has been described with respect to a planar alkaline battery having a cubic (straight parallelepiped) overall shape, such overall shape variations are possible and fall within the concept of the present invention. Is intended. In the case of a flat battery, for example, in the shape of a cube (straight parallelepiped), both ends of the housing can be slightly outwardly or inwardly tapered while maintaining their rectangular shape. The overall appearance of such various shapes is still essentially that of a cube and is intended to fall within the meaning of a cube or its legal equivalent. Other variations to the overall shape such that the angle between the ends of the battery and any one of the side surfaces of the housing slightly change so that the parallelepiped is slightly offset from the exact rectangular shape are here and also claimed. Is intended to fall within the meaning of a cube (straight parallelepiped) as used in.

  The present invention is intended to desirably extend to an overall cell shape that is planar in that the side of the outer casing along the length of the casing is substantially planar. Thus, the term “planar” is intended to encompass and include surfaces that are substantially planar in that the curvature of such surfaces is negligible. Specifically, the concept of the present invention is intended to cover a planar battery in which the side of the battery casing surface along the length of the casing has a planar polygonal surface. Thus, the battery may have a polyhedral overall shape with all sides of the outer casing being polygonal. The present invention is also intended to extend to batteries where the side of the battery casing along its length has a plane, which is a parallelogram, and the overall shape of the battery is prismatic.

It is a perspective view which shows the planar alkaline battery of this invention which shows the negative terminal edge part of a battery. It is a perspective view which shows the planar alkaline battery of FIG. 1 which shows the positive terminal edge part of a battery. 1B is a cross-sectional view of the battery shown in FIG. 1A taken along line 2-2. FIG. 2 is a cross-sectional view of the battery shown in FIG. 1 showing the plug design taken along and modified along line 2-2. FIG. 3 is a cross-sectional view of the battery shown in FIG. 1A taken along line 3-3. FIG. 3 is a cross-sectional view of the battery shown in FIG. 1A showing the plug design taken and modified along line 3-3. FIG. It is an expanded view which shows the component which comprises the end cap assembly for a planar alkaline battery. 3B is a perspective view showing the modified plug shown in FIGS. 2A and 3A before the wire is compressed into its housing cavity. FIG. 1B is a plan view showing a cross section of the battery taken in a plane perpendicular to the longitudinal axis of the battery along the line of sight of FIG. 1A to show an elongated anode cavity. FIG. FIG. 6 is a plan view showing a cross section of a battery showing another embodiment of an elongated anode cavity. FIG. 6 is a plan view showing a cross section showing a third embodiment of an elongated anode cavity. It is an expanded view which shows introduction | transduction of the battery containing material and end cap assembly in a battery casing (housing). It is a top view which shows the metal cover plate laser-welded along the edge part provided with the strong welding part to the inner surface of the casing of a battery, and a weak welding part. FIG. 3 is a plan view showing a metal cover plate laser welded along an edge with a strong weld and a weak weld to the crimped edge of the battery casing. It is a side view which shows the battery casing main body which shows the embodiment of a strong weld part and a weak weld part. It is a side view which shows the battery casing main body which shows the embodiment of the curved strong weld part and the weak weld part. It is a side view of the battery which shows the groove | channel in the casing main body which forms the cool air of the thin wall material located below. It is a side view of the battery which shows the some groove | channel in a casing main body, and each groove | channel forms the area | region of the thin-walled material located below. FIG. 9 is a cross-sectional view illustrating a representative groove shown in FIGS. 8 and 8A. It is a top view which shows the metal cover laser-welded to the battery casing shown by FIG. 10A. FIG. 6 is a side view of an embodiment of a planar alkaline battery showing a single groove on the wide side of the casing. It is sectional drawing which shows the wide side surface of the battery shown by FIG. 10A. FIG. 10B is a cross-sectional view along the short side of the battery shown in FIG. 10A. It is an expanded view which shows the structural member which comprises the end cap assembly for the planar battery shown by FIG. 10A. FIG. 10B is a perspective view showing the assembly of the separator for the battery of FIG. 10A from a single sheet of separator material. It is a perspective view which shows the step which forms the wound separator sheet. FIG. 6 is a perspective view of a completed wrapped separator having an open end and an opposite closed end. It is sectional drawing which shows the alternative kind of V-shaped groove | channel cut | disconnected from the vent with a groove | channel. FIG. 6 is a cross-sectional view showing an embodiment in which there is a gap between the short side surface of the separator and the cathode. FIG. 12 is a cross-sectional view illustrating an alternative embodiment similar to the battery of FIG. 11 except that a paper washer is laminated on the welded metal cover instead of a plastic extender.

Claims (79)

A pressure vessel including an outer housing,
The outer housing includes a closed end and an opposite open end, and the container further includes an end cap assembly that seals the open end of the outer housing, the outer housing and the end The cap assembly forms a pressure interface around the interior of the container;
The container includes a vent mechanism located on the pressure interface, the vent mechanism is activated to release gas pressure from within the container, and the vent mechanism forms a groove on the interface. And a second rupture zone on the interface, wherein the groove defines a material region that is thinner than an average thickness of the interface, the first rupture zone having a gas pressure within the cell. A container that ruptures when rising to a first pressure level and the second rupture zone ruptures when a gas pressure in the cell rises to a second pressure level that is higher than the first pressure level.   The container of claim 1, wherein the first rupture zone and the second rupture zone are spaced apart on the interface. The container of claim 1, wherein the first rupture zone ruptures when the gas pressure in the container increases to a pressure between about 250-800 psig (1724 × 10 ^{3 to} 5515 × 10 ³ Pascal gauge). . The container of claim 1, wherein the first rupture zone ruptures when the gas pressure in the container increases to a pressure between about 400-800 psig (2758 × 10 ^{3 to} 5515 × 10 ³ Pascal gauge). . The second rupturable zone ruptures when gas pressure in the vessel reaches a pressure between about ^{800~2500psig (5515 × 10 3 ~17235 ×} 10 3 pascal gage) A container according to claim 1.   The container of claim 1, wherein the second rupture zone includes a laser weld inside a portion of the interface.   The container according to claim 1, wherein the groove is formed by punching the boundary surface.   The container according to claim 6, wherein the laser weld is formed between the outer housing and a metal member fitted in the open end of the external housing, thereby closing the open end.   The laser weld is formed between the inner surface of the outer housing and an edge of the metal member fitted into the open end of the external housing, thereby closing the open end. Item 7. The container according to Item 6. The laser weld is made with an Nd: Yag laser, and the laser weld raises the gas pressure in the cell to a level between about 800-2500 psig (5515 × 10 ^{3 to} 17235 × 10 ³ Pascal gauge). 7. A container according to claim 6, which ruptures when   The container according to claim 8, wherein the container has a cubic shape, and the metal member is a rectangular metal plate.   The container according to claim 8, wherein the metal member is a rectangular plate having an opening therethrough. A main alkaline battery including a negative terminal, a positive terminal, and a cube-shaped outer housing, the outer housing having a closed end and an open end, the battery being in the outer housing And an anode including zinc and a cathode including MnO ₂ , wherein the battery includes a separator between the anode and the cathode and an end cap assembly that seals the open end of the outer housing. And thereby forming an interface around the interior of the battery,
The cathode includes a plurality of rectangular cathode slabs, each cathode slab having a central opening free of cathode material, the cathode slab having an outer surface of the cathode in contact with the inner surface of the outer housing. Laminating within the outer housing such that the opening without the cathode material forms a core;
The battery includes a ventilation mechanism located on the boundary surface, and the ventilation mechanism is activated to release the gas pressure from within the battery as the gas pressure increases, and the ventilation mechanism includes the ventilation mechanism A first rupture zone including a groove on the interface and a second rupture zone on the interface, wherein the groove defines a material region located below and thinner than an average thickness of the boundary; The burst zone bursts when the gas pressure in the battery rises to a first pressure level, and the second burst zone reaches a second pressure level where the gas pressure in the battery is higher than the first pressure level. An alkaline battery that ruptures when rising, thus allowing gas from within the battery to escape from the interior of the battery through the rupture.   The alkaline battery according to claim 13, wherein the first rupture zone and the second rupture zone are separated on the boundary surface. 14. The alkali of claim 13, wherein the first rupture zone ruptures when the gas pressure in the vessel rises to a pressure between about 250-800 psig (1724 × 10 ^{3 to} 5515 × 10 ³ Pascal gauge). battery. 14. The alkali of claim 13, wherein the first rupture zone ruptures when the gas pressure in the vessel rises to a pressure between about 400-800 psig (2758 × 10 ^{3 to} 5515 × 10 ³ Pascal gauge). battery. The alkaline battery of claim 13, wherein the second rupture zone ruptures when the gas pressure in the container reaches a pressure between about 800-2500 psig (5515 × 10 ^{3 to} 17235 × 10 ³ Pascal gauge). .   The alkaline battery according to claim 13, wherein the second rupture zone includes a laser weld inside a part of the boundary surface.   The alkaline battery according to claim 13, wherein the groove is formed by punching the boundary surface.   The end cap assembly includes a metal cover, and the laser weld is formed between the housing and the metal cover that is inserted into the open end of the housing, thereby forming the open end. The alkaline battery according to claim 18, wherein the alkaline battery is closed.   The end cap assembly includes a metal cover, and the laser weld is formed between an inner surface of the housing and an edge of the metal cover that is recessed into the open end of the housing, thereby The alkaline battery according to claim 18, wherein the open end is closed. The laser weld, Nd: created by Yag laser, increasing the laser weld, to a level between the gas pressure of about 800~2500psig in the cell ^{(5515 × 10 3 ~17235 × 10} 3 Pascals gauge) The alkaline battery of claim 18, which bursts when   The alkaline battery according to claim 20, wherein the metal cover is a rectangular metal plate.   The alkaline battery according to claim 20, wherein the metal cover is a rectangular metal plate having an opening therethrough.   The end cap assembly includes the metal cover, a terminal end plate, an insulating sealing member, and an elongated conductive member partially passing through both the insulating sealing member and the metal cover, The alkaline battery according to claim 24, wherein the conductive member is electrically connected to the terminal end plate.   The alkaline battery according to claim 25, wherein the conductive member is electrically connected to the anode.   27. The alkaline battery of claim 26, wherein a portion of the elongated conductive member enters into the anode and functions as an anode current collector (160).   27. The alkaline battery of claim 26, wherein the end cap assembly further includes a conductive member between the terminal end plate and the metal cover, thereby insulating the terminal end plate from the metal cover.   29. The alkaline battery according to claim 28, wherein the conductive member between the terminal end plate and the metal cover includes a plastic material.   29. The alkaline battery according to claim 28, wherein the conductive member between the terminal end plate and the metal cover includes a paper material.   The terminal end plate has a central region having a thickness less than an average thickness of the end plate, and the elongated conductive material is welded to the terminal end plate in the central region by electrical resistance welding; The alkaline battery according to claim 28.   26. A sealing material comprising asphalt is applied between at least a portion of the surface of the elongated conductive member and the metal cover to prevent leakage of alkaline electrolyte therethrough. Alkaline battery.   The alkaline battery according to claim 13, wherein at least a part of the central opening in the cathode slab forms a cavity for accommodating the anode.   The alkaline battery according to claim 33, wherein the cavity has an oval structure.   The alkaline battery according to claim 13, wherein the battery includes an alkaline electrolyte containing an aqueous solution of potassium hydroxide. The cell cathode 820 mA per gram - ma of zinc based on the theoretical specific value of the time of zinc - is divided by the time 370 mA per gram - time theory MnO ₂ based on the theoretical capacity of the MnO ₂ 36. The alkaline battery of claim 35, wherein the alkaline battery is balanced to exceed the capacity ratio between about 1.2 and 2.0. The cell cathode 820 mA per gram - ma of zinc based on the theoretical specific value of the time of zinc - is divided by the time 370 mA per gram - time theory MnO ₂ based on the theoretical capacity of the MnO ₂ 36. The alkaline battery of claim 35, wherein the alkaline battery is balanced to exceed the capacity ratio between about 1.4 and 1.8.   The battery has an overall thickness of between about 5-10 mm, the overall thickness being defined as the distance between the outer surfaces of the opposing sides of the housing that defines a short dimension of the housing. Item 14. The alkaline battery according to Item 13.   The alkaline battery of claim 13, wherein the housing comprises a metal having a wall thickness between about 0.30 mm and 0.50 mm.   The alkaline battery of claim 13, wherein the housing comprises a metal having a wall thickness between about 0.30 mm and 0.40 mm.   The alkaline battery of claim 13, wherein the housing comprises steel. A main alkaline battery including a negative terminal, a positive terminal, and a cube-shaped outer housing, the outer housing having a closed end and an open end, the battery being in the outer housing And an anode including zinc and a cathode including MnO ₂ , wherein the battery includes a separator between the anode and the cathode and an end cap assembly that seals the open end of the outer housing. And thereby forming an interface around the interior of the battery,
The cathode includes a plurality of rectangular cathode slabs, each cathode slab having a central opening free of cathode material, the cathode slab having an outer surface of the cathode in contact with the inner surface of the outer housing. Laminating in the outer housing along the central longitudinal axis of the battery, so that the opening without the cathode material forms a central core along the longitudinal axis;
The battery includes a ventilation mechanism located on the boundary surface, and the ventilation mechanism is activated to release the gas pressure from within the battery as the gas pressure increases, and the ventilation mechanism A first rupture zone and a second rupture zone on the interface, wherein at least one of the rupture zones includes a groove on the interface, the groove being located below the average thickness of the boundary; Defining a region, the first rupture zone ruptures when the gas pressure in the battery rises to a first pressure level, and the second rupture zone has a gas pressure in the battery less than the first pressure level. A battery that ruptures when rising to a higher second pressure level, thus allowing gas from within the battery to escape from the interior of the battery through the rupture.   43. The battery of claim 42, wherein the first rupture zone and the second rupture zone are spaced apart on the interface.   43. The battery of claim 42, wherein the second rupture zone includes a laser weld inside a portion of the interface.   43. The battery according to claim 42, wherein the groove is formed by punching the boundary surface. The first rupture zone on the interface ruptures when the gas pressure within the cell reaches a pressure level between about 250-800 psig (1724 × 10 ^{3 to} 5515 × 10 ³ Pascal gauge), The first rupture zone on the interface ruptures when a gas pressure within the cell interior reaches a pressure level between about 800-2500 psig (5515 × 10 ^{3 to} 17235 × 10 ³ Pascal gauge). 42. The battery according to 42. The first rupture zone on the interface ruptures when the gas pressure inside the cell reaches a pressure level between about 400-800 psig (2758 × 10 ^{3 to} 5515 × 10 ³ Pascal gauge), The first rupture zone on the interface ruptures when a gas pressure within the cell interior reaches a pressure level between about 800-2500 psig (5515 × 10 ^{3 to} 17235 × 10 ³ Pascal gauge). 42. The battery according to 42.   The end cap assembly includes a metal cover, the first rupture zone is formed by a groove on the outer surface of the housing, and the second rupture zone is an edge of a metal member and an inner surface of the housing. 43. Formed by a laser weld in between, thus securing the metal member to the inner surface of the outer housing along a portion of its edge, near the open end of the housing. The battery described in 1.   49. The battery according to claim 48, wherein the metal cover is a rectangular plate.   43. The battery of claim 42, wherein the groove runs parallel to the closed end of the battery.   43. The battery of claim 42, wherein the housing comprises a metal having a wall thickness between about 0.30 mm and 0.50 mm.   The battery has an overall thickness of between about 5-10 mm, the overall thickness being defined as the distance between the outer surfaces of the opposing sides of the housing that defines a short dimension of the housing. Item 43. The battery according to Item 42. A method for closing an external housing of an alkaline battery, wherein the external housing has a closed end, an opposed open end, and at least one plane, the method comprising:
Inserting the metal cover into the housing in the vicinity of the open end so that an edge of the metal cover abuts the housing and at least a part of the metal cover is exposed; and a heat transfer medium Applying to the part of the metal cover; and laser welding the edge of the cover to the housing to close the open end, the heat transfer medium comprising the laser welding To absorb at least part of the heat generated during the period of time.   54. The method of claim 53, wherein a portion of the exposed surface of the metal cover is curved to form a trough, and the method further comprises disposing the heat transfer medium within the trough.   54. The method of claim 53, wherein sufficient heat generated by the welding is absorbed by the heat transfer medium such that the metal cover does not reach a temperature greater than about 100 degrees Celsius during the welding period.   54. The method of claim 53, wherein the heat transfer medium comprises a solid or a liquid.   54. The method of claim 53, wherein the heat transfer medium comprises a metal.   54. The method further includes disposing a non-metallic sealing member on the metal cover so that the sealing member contacts at least a portion of the metal cover after the metal cover is welded to the housing. The method described in 1.   54. The method of claim 53, wherein the heat transfer medium includes deionized water applied to an exposed portion of the metal cover.   The method according to claim 53, wherein the heat transfer medium includes an aqueous solution containing polyvinyl alcohol and potassium hydroxide, and the polyvinyl alcohol covers an exposed portion of the metal cover.   The method according to claim 53, wherein the heat transfer medium includes an aqueous solution containing a gelling agent, and the gelling agent covers an exposed portion of the metal cover.   54. The method of claim 53, further comprising coating a portion of the non-metallic sealing member with a gelling agent prior to placing the sealing member on the metal cover.   59. The method of claim 58, wherein the sealing member comprises plastic.   59. The method of claim 58, wherein the sealing member comprises paper.   54. The method of claim 53, wherein the laser welding is accomplished using a Nd: Yag laser.   54. The method of claim 53, wherein the closed housing is in the shape of a cube.   The housing has an overall thickness between about 5-10 mm, the overall thickness being defined as the distance between the outer surfaces of the opposing sides of the housing that define a short dimension of the housing. 54. The method according to item 53. A method of closing an outer housing of an alkaline battery, wherein the outer housing has a closed end, an opposite open end, and at least one plane, the method comprising:
Inserting the metal cover into the housing in the vicinity of the open end so that an edge of the metal cover abuts the housing and at least a portion of the metal cover is exposed; Cooling the substrate to a temperature below ambient room temperature and laser welding the edge of the metal cover to the housing to close the open end.   69. The method of claim 68, wherein the metal cover is cooled well below ambient room temperature so that the metal cover does not reach a temperature greater than about 100 degrees Celsius during the welding period.   69. After welding the metal cover to the housing, the method further comprises disposing a non-metallic sealing material on the metal cover such that the sealing member contacts at least a portion of the metal cover. The method described in 1.   69. The method of claim 68, wherein the metal cover is cooled by applying deionized water to exposed portions of the metal cover.   69. The method of claim 68, wherein the metal cover is cooled by applying an aqueous solution comprising polyvinyl alcohol and potassium hydroxide, and the polyvinyl alcohol covers an exposed portion of the metal cover.   69. The method of claim 68, wherein the metal cover is cooled by applying an aqueous solution containing a gelling agent, and the gelling agent covers an exposed portion of the metal cover.   71. The method of claim 70, further comprising coating a portion of the non-metallic sealing member with a gelling agent prior to placing the sealing member on the metal cover.   The method of claim 70, wherein the sealing member comprises plastic.   The method of claim 70, wherein the sealing member comprises paper.   69. The method of claim 68, wherein the laser welding is accomplished using a Nd: Yag laser.   69. The method of claim 68, wherein the closed housing is in the shape of a cube.   The housing has an overall thickness between about 5-10 mm, the overall thickness being defined as the distance between the outer surfaces of the opposing sides of the housing that define a short dimension of the housing. Item 79. The method according to Item 78.

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