Electric double layer capacitor device

Abstract

An electric double layer capacitor (EDLC) device (1) for reflow soldering to a printed circuit board (PCB) (2) includes a cylindrical, thin-walled, malleable aluminum housing (3) extending between an open end (5) and a closed end (6). The housing (3) defines a circular opening (7) adjacent the end (5) and a cylindrical cavity (8) extending from the opening (7) and terminating at the end (6). A cylindrical capacitor element (9) is complementarily housed within the cavity (8) and includes two carbon-based electrodes (11, 12). A separator in the form of two elongated paper-based separator sheets (13, 14) is alternately arranged and spirally wound with the electrodes (11, 12). The sheets (13, 14) maintain the electrodes (11, 12) in a spaced, opposing arrangement. An electrolyte is contained within the cavity (6) to impregnate the electrodes (11, 12) and sheets (13, 14) and enable ionic conduction between the electrodes (11, 12). The electrolyte has a freezing point below 0°C and a boiling point above 200°C at 1 atmosphere. A sealing element in the form of a rubber cap (15) extends across and seals the opening (7). In use, two terminals (17, 18) each extend between a first end (19) disposed within the cavity (8) and a second end (20) disposed outside the cavity (8). The ends (19) are electrically connected to the respective electrodes (11, 12), and the terminals (17, 18) extend through the opening (7) so that the ends (20) are available for electrical connection to the PCB (2).

Description

[Technical Field]

[0001] The present invention relates to supercapacitors, and more particularly to electric double layer capacitor (EDLC) devices.

[0002] Although embodiments of the present invention have been developed as surface mount EDLC devices for use in electronic components and circuits for computing devices and will be described herein with particular reference to that application, it will be understood that the present invention is not limited to such fields of use and is applicable in broader contexts including, but not limited to, mobile devices, wearable devices, asset tracking devices, battery-supported devices, and the like. [Background technology]

[0003] Any discussion of background art throughout this specification should in no way be taken as an admission that such art is widely known or forms part of the common general knowledge in the field.

[0004] EDLC devices, more commonly referred to as supercapacitors or ultracapacitors, are high-specific capacitance devices that utilize opposing electrodes with high surface areas. Such electrodes can be carbon-based, each containing a thin coating or layer of one or more of activated carbon, carbon nanotubes, carbon black, etc. An electrolyte is provided to enable ionic conduction between the electrodes. When a potential is applied to the electrodes, ions in the electrolyte orient and migrate toward the electrode of opposite polarity, defining two charge layers adjacent to each electrode. Thus, an EDLC device defines two capacitors in series: the first capacitor is between the positive electrode and adjacent layers of anions formed in the electrolyte, and the second capacitor is between the negative electrode and adjacent layers of cations formed in the electrolyte.

[0005] The term "ultracapacitor" is synonymous with the term "supercapacitor," and the two are considered interchangeable herein.

[0006] EDLC devices typically provide much more capacitance for a given weight or volume than that provided by conventional capacitors. By comparison, electrolytic capacitors have a capacitance of 1 mFcm -3 EDLC devices can provide a volumetric capacitance of 10-15 Fcm -3 Accordingly, steps have been taken to apply EDLC devices to a wider range of electronic circuits, particularly microelectronic circuits used in computing devices, where volume considerations for each electronic component in the circuit are particularly important.

[0007] Mass production of microelectronic circuits is increasingly automated and utilizes a reflow process for surface mounting electronic components to printed circuit boards (PCBs). This form of manufacturing utilizes surface mount technology (SMT), and electronic components intended for SMT manufacturing are referred to herein as surface mount devices (SMDs), or SMT devices. The latter two terms are synonymous and are considered interchangeable herein. It will be understood that a PCB may include only SMT devices or a combination of SMT and non-SMT devices.

[0008] The thermal profile for a given reflow process is usually well specified. It may, for example, include a 6-minute cycle with an initial temperature ramp from room temperature, a 100-second hold at about 160°C, a further ramp to a peak at about 260°C, and a final cool-down. Other profiles are also used. In some reflow processes, one or more extra passes through the reflow oven are required to rework the part.

[0009] Conventional EDLC devices have been found to often have relatively high failure rates or unacceptably shortened lifespans when subjected to thermal shock from the reflow process described above. This problem is exacerbated for smaller EDLC devices, where less volume is available to thermally protect the sensitive internal components of the EDLC device.

[0010] In a partial answer to this problem, it is known to provide an EDLC device for use in a reflow process. Herein, EDLC devices for this process are referred to as SMD EDLC devices. One known SMD EDLC device is pre-mounted on a specially formed PCB that utilizes a ceramic substrate (International PCT Application No. PCT / KR2011 / 008979). The need for such a PCB not only adds material costs to the process, but also adds manufacturing complexity because it involves thermocompression bonding of a metal housing to the substrate. Other alternatives include SMD EDLC devices that utilize sulfuric acid electrolytes with reinforced packaging to better avoid plastic deformation of the package during the reflow process, and other SMD EDLC devices with organic electrolytes disposed in hermetically sealed packages that provide thermal insulation to reduce thermal shock experienced by the delicate internal components of the SMD EDLC device. Examples of the latter packages include laser-welded ceramics (International PCT Application No. PCT / US2021 / 040625), heat-welded LCP (U.S. Patent No. 8,773,841), and other materials. The above packaging options typically involve the use of relatively expensive, and sometimes prohibitively expensive, materials, require significant additional, often time-consuming and expensive manufacturing steps to manufacture the EDLC device, and are bulky.

[0011] Therefore, there is a need in the art for improved EDLC devices for reflow soldering to a PCB. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] PCT / KR2011 / 008979 [Patent Document 2] PCT / US2021 / 040625 [Patent Document 3] U.S. Patent No. 8,773,841 Summary of the Invention [Problem to be solved by the invention]

[0013] It is an object of the present invention to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative. [Means for solving the problem]

[0014] One embodiment provides an electric double layer capacitor (EDLC) device for reflow soldering to a printed circuit board (PCB), the device comprising: a housing for defining an opening and a cavity extending from the opening; a substantially cylindrical capacitor element housed within the cavity, the element including two carbon-based electrodes and a separator spirally wound with the electrodes, the separator maintaining the electrodes in a spaced apart, opposing arrangement; an electrolyte within the cavity to allow ionic conduction between the electrodes; a sealing element for sealing the opening; two terminals each extending between a first end disposed within the cavity and a second end disposed outside the cavity, the first ends electrically connected to respective electrodes, and the terminals extending through the openings such that the second ends are available for electrical connection to a PCB; Includes:

[0015] In one embodiment, the PCB includes a PCB surface on which the device is mounted, the device includes a base having a first surface facing the PCB surface, and the terminal extends relative to the base such that the second end is substantially parallel to the PCB surface in use. In one embodiment, the terminal extends through the base. In one embodiment, the terminal extends along the base. In one embodiment, the terminal retains the base to the housing. In one embodiment, the base is disposed between the housing and the PCB surface in use. In one embodiment, the base includes a conductive portion disposed adjacent to the terminal in use.

[0016] In one embodiment, the sealing element provides a compression seal. In one embodiment, the housing includes a malleable sidewall that is plastically deformed to define a sealing surface for the compression seal. In one embodiment, the malleable sidewall includes aluminum, an aluminum alloy, or stainless steel. In one embodiment, the malleable sidewall includes a wall thickness less than at least one of 1 mm, 0.5 mm, 300 microns, 290 microns, 280 microns, 270 microns, 260 microns, and 250 microns. In one embodiment, the malleable sidewall includes a wall thickness greater than at least one of 300 microns, 350 microns, 370 microns, 380 microns, 390 microns, and 400 microns.

[0017] In one embodiment, at least one of the electrodes comprises a high surface area carbon-based material. In one embodiment, the carbon-based material has a surface area of ​​400 m 2 / g or greater. In one embodiment, the carbon-based material comprises one or more of carbon particles, graphene, reduced graphene oxide, carbon nanotubes, carbon fibers, and expanded carbon. In one embodiment, the carbon particles comprise one or more of activated carbon particles and carbon black terminals. In one embodiment, the carbon particles comprise mesoporous carbon particles.

[0018] In one embodiment, at least one of the electrodes includes a binder. In one embodiment, the binder is one or more of carboxymethylcellulose (CMC), a salt of CMC (such as sodium carboxymethylcellulose), polytetrafluoroethylene (PTFE), a salt of polystyrene sulfonic acid (PSS), such as a Group 1 or Group 2 metal salt of PSS, including magnesium polystyrene sulfonate (MgPSS), sodium polystyrene sulfonate (NaPSS), lithium polystyrene sulfonate (LiPSS), and calcium polystyrene sulfonate (CaPSS), polyvinylidene fluoride (PVDF), and a polyimide. In one embodiment, the binder includes a fluorinated polymer. In one embodiment, the binder is stable to at least 200°C.

[0019] In one embodiment, at least one of the electrodes is binderless. In one embodiment, at least one electrode comprises one or more of graphene and carbon nanotubes.

[0020] In one embodiment, the electrolyte is an organic electrolyte having a boiling point above 200° C. at 1 atmosphere.

[0021] In one embodiment, the EDLC has an initial ESR (ESR1), The housing is H ) and T H After following a predetermined thermal profile, the device has a second ESR (ESR2), where: ESR2 ≧ ESR1,

[0022]

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[0023] and A given thermal profile must meet a temperature threshold (T T ) and threshold duration (tD ) where 25 seconds ≦ t D ≦40 seconds.

[0024] In one embodiment, T T is one of 180°C and 217°C.

[0025] In one embodiment, one of the following conditions is met:

[0026]

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[0032]

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[0038]

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[0039] In one embodiment, T T = 180°C and one or more of the following conditions are met:

[0040]

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[0041]

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[0042]

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[0043]

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[0044]

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[0045]

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[0046] In one embodiment, the EDLC device has a rated voltage between 2 and 4 volts. In one embodiment, the capacitor element defines at least one capacitor cell, and in use, the cell is exposed to the rated voltage. In one embodiment, the EDLC device has a rated voltage of at least 3 volts.

[0047]

number

[0048] is.

[0049] In one embodiment, T in a predetermined thermal profile H The maximum value of T max where T max ≧T T and at least one of the following conditions is satisfied: T max ≧260℃, T max ≥ 250℃, T max ≥ 240℃, T max ≥ 230℃, T max ≥ 220℃, T max ≥ 210°C, and T max ≧200℃.

[0050] In one embodiment, at least one of the electrodes comprises a mixture of activated carbon particles and conductive carbon particles, hi one embodiment, the carbon particles comprise one or more of mesoporous carbon particles and microporous carbon particles.

[0051] In one embodiment, at least one electrode comprises entangled carbon nanotubes.

[0052] The electrolyte can be any suitable electrolyte. In one embodiment, the electrolyte includes an organic salt (such as an ionic liquid) or includes an organic salt (solid or liquid) in solution in a neutral organic compound / solvent. Although reference may be made herein to a single salt or a single organic compound / solvent, it will be understood throughout this disclosure that a single electrolyte can include one or more organic salts, zero neutral organic compounds / solvents, one neutral organic compound / solvent, or two or more neutral organic compounds / solvents.

[0053] In one embodiment, the electrolyte comprises at least one of at least one salt and at least one neutral compound. In one embodiment, the electrolyte is an organic electrolyte. In one embodiment, the organic electrolyte comprises an organic salt. In one embodiment, the organic electrolyte comprises two or more organic salts. In one embodiment, the electrolyte has a boiling point at 1 atmosphere of 210°C or higher, 220°C or higher, 230°C or higher, 240°C or higher, or 250°C or higher. In one embodiment, the electrolyte has a freezing point at 1 atmosphere of -10°C or lower, -20°C or lower, -30°C or lower, or -40°C or lower.

[0054] In one embodiment, the electrolyte is immiscible with the binder used in the electrode, hi another embodiment, the electrolyte is immiscible with the binder at temperatures of 200°C or greater, 210°C or greater, 220°C or greater, 240°C or greater, 250°C or greater, or 260°C or greater.

[0055] In one embodiment, the neutral compound is a neutral organic compound. The neutral organic compound may be liquid or solid at room temperature, such as 20°C, and 1 atmosphere pressure. It will be understood that, when used, the neutral organic compound acts as a solvent and is therefore sometimes referred to as a neutral organic solvent. The neutral organic solvent preferably has certain properties suitable for solvating an organic salt (an ionic liquid in some embodiments). In one embodiment, the neutral organic solvent is a liquid, such as a liquid aprotic solvent, in which the organic salt is mixed or dissolved. In another embodiment, such as when the neutral organic solvent is solid at 20°C and 1 atmosphere pressure, the organic solvent can be heated above its melting point to become liquid when the organic salt is mixed or dissolved therein. In one embodiment, the neutral organic compound is an aprotic organic solvent. In another embodiment, the neutral organic compound is a polar aprotic organic solvent.

[0056] In one embodiment, the neutral organic compound is a polar aprotic organic solvent having a freezing point below 60°C and a boiling point above 150°C, 160°C, 180°C, 200°C, 220°C, 240°C, or 260°C.

[0057] In one embodiment, the at least one neutral organic compound or polar aprotic organic solvent is selected from a linear or cyclic carbonate (ROC(=O)-O-R'), a cyclic lactone (-C(=O)-O-), or a linear or cyclic sulfone (RS(=O)2-R'). In one embodiment, the polar aprotic solvent is a linear carbonate. In one embodiment, the linear carbonate is diethyl carbonate. In one embodiment, the polar aprotic solvent is a cyclic carbonate having the formula:

[0058] [ka]

[0059] In the formula, R 9is H, CH, a fluorinated methyl group, or F. In one embodiment, the cyclic carbonate contains at least one C—F bond.

[0060] In one embodiment, at least one of the neutral organic compounds or polar aprotic solvents is a linear or cyclic sulfone. In one embodiment, the sulfone has a linear structure such as:

[0061] [ka]

[0062] In the formula, R 10 and R 11 are each independently a C1-C4 alkyl group. 10 and R 11 are identical. In one embodiment, R 10 and R 11 and are both ethyl groups. 10 and R 11 are different alkyl groups.

[0063] In one embodiment, the sulfone has a cyclic structure such as:

[0064] [ka]

[0065] In the formula, R 12 is H or CH. In one embodiment, the sulfone is sulfolane.

[0066] In one embodiment, the at least one neutral organic compound or polar aprotic solvent is a lactone. In one embodiment, the cyclic lactone is gamma butyrolactone.

[0067] In one embodiment, the salt is an organic salt. In one embodiment, the organic electrolyte comprises two or more organic salts dissolved in an organic solvent or a polar aprotic solvent, or two or more organic salts dissolved in a mixture of two or more organic solvents or polar aprotic organic solvents.

[0068] In one embodiment, the organic salt comprises a cation and an anion. In one embodiment, the cation comprises a quaternary ammonium cation. In one embodiment, the quaternary ammonium cation has the following chemical structure:

[0069] [ka]

[0070] In the formula, R 1 , R 2 , R 3 , and R 4 are each alkyl substituents. In one embodiment, R 1 , R 2 , R 3 , and R 4 are each independently a linear or branched C1 to C7 alkyl group. 1 , R 2 , R 3 , and R 4 are each independently a linear or branched C1-C4 alkyl group. 1 , R 2 , R 3 , and R 4 are each independently a linear or branched C1 to C2 alkyl group.

[0071] In one embodiment, R 1 is R 2 , R 3 , and R 4 In one embodiment, R 1 , R 2 , R 3 , and R 4 are different from each other.

[0072] In one embodiment, the quaternary ammonium cation has the following chemical structure:

[0073] [ka]

[0074] In the formula, R 5 and R 6 are each alkyl substituents. In one embodiment, R 5 and R 6 are each independently a linear or branched C1 to C7 alkyl group. 5 is R 6 In one embodiment, the quaternary ammonium cation is a spiro-bicyclic compound in which the common atom in the spiro structure is nitrogen. In one embodiment, the spiro-bicyclic compound is spiro-bispyrrolidinium (SBP). In one embodiment, the quaternary ammonium cation is a heterocyclic nitrogen-containing cation.

[0075] In one embodiment, the anion is one or more of borate, phosphate, and sulfonylimide. In one embodiment, the anion is one or more of tetrafluoroboric acid (TFB), tetracyanoboric acid, fluorotricyanoboric acid, difluorodisyanoboric acid, trifluorocyanoboric acid, bis(oxalato)boric acid, and difluoro(oxalato)boric acid. In one embodiment, the anion is one or more of bis(fluorosulfonyl)imide (FSI) and bis(trifluoromethylsulfonyl)imide (TFSI).

[0076] In another embodiment, the organic salt is a liquid at or near room temperature and is referred to herein as an ionic liquid. Thus, in one embodiment, the organic salt is an ionic liquid. In one embodiment, the ionic liquid has a melting point of 0°C to 100°C at 1 atmosphere. In one embodiment, the ionic liquid has a thermal decomposition temperature of 210°C or higher, 220°C or higher, 230°C or higher, 240°C or higher, and 250°C or higher, all at 1 atmosphere. In another embodiment, the organic salt is a solid at 20°C and 1 atmosphere.

[0077] In one embodiment, the housing is at least substantially formed from a metal, hi one embodiment, the metal comprises aluminum, an aluminum alloy, or a stainless steel alloy.

[0078] In one embodiment, the cavity is substantially cylindrical and accommodates the complementary capacitor elements. In one embodiment, the housing includes a substantially cylindrical first sidewall extending axially between a first end and a second end, the first end defining an opening, and a substantially circular second sidewall extending across the second end. In one embodiment, the first sidewall is thin and malleable. In one embodiment, the first sidewall has a wall thickness of less than 1 mm. In one embodiment, the first sidewall has a wall thickness of less than 0.5 mm. In one embodiment, the first sidewall and the second sidewall are integrally formed.

[0079] In one embodiment, the separator includes one or more porous separator sheets each including at least one of polytetrafluoroethylene (PTFE), cellulose fibers, polyacrylonitrile fibers, aramid fibers, glass fibers, and polyethylene terephthalate (PET).

[0080] In one embodiment, the separator has a melting point of 200°C or higher, 220°C or higher, 230°C or higher, 240°C or higher, and 250°C or higher.

[0081] Another embodiment provides an electric double layer capacitor (EDLC) device for reflow soldering to a printed circuit board (PCB), the device comprising: a housing for defining an opening and a cavity extending from the opening; a substantially cylindrical capacitor element housed within the cavity, the element including two carbon-based electrodes and a separator spirally wound with the electrodes, the separator maintaining the electrodes in a spaced apart, opposing arrangement; an electrolyte in the cavity for enabling ionic conduction between the electrodes, the electrolyte having a freezing point of 0°C or less and a boiling point of 200°C or more at 1 atmosphere pressure; a sealing element for sealing the opening; two terminals each extending between a first end disposed within the cavity and a second end disposed outside the cavity, the first ends electrically connected to respective electrodes, and the terminals extending through the openings such that the second ends are available for electrical connection to a PCB; Includes:

[0082] Another embodiment provides an electric double layer capacitor (EDLC) device for reflow soldering to a printed circuit board (PCB), the device comprising: a housing for defining an opening and a cavity extending from the opening; a capacitor element housed within the cavity, the element including two carbon-based electrodes and a separator that maintains the electrodes in a spaced apart, opposing arrangement; an electrolyte in the cavity for enabling ionic conduction between the electrodes, the electrolyte having a freezing point of 0°C or less and a boiling point of 200°C or more at 1 atmosphere pressure; a sealing element for providing a compression seal to seal the opening; two terminals each extending between a first end disposed within the cavity and a second end disposed outside the cavity, the first ends electrically connected to respective electrodes, and the terminals extending through the openings such that the second ends are available for electrical connection to a PCB; Includes:

[0083] Another embodiment provides an electric double layer capacitor (EDLC) device for reflow soldering to a printed circuit board (PCB), the device comprising: a malleable housing for defining an opening and a cavity extending from the opening; a capacitor element housed within the cavity, the element including two carbon-based electrodes and a separator spirally wound with the electrodes, the separator maintaining the electrodes in a spaced apart, opposing arrangement; an electrolyte within the cavity to allow ionic conduction between the electrodes; a sealing element for sealing the opening; two terminals each extending between a respective first end located within the cavity and a respective second end located outside the cavity, the first ends electrically connected to the respective electrodes, the terminals extending through the openings such that the second ends are available for electrical connection to a PCB; Includes:

[0084] Another embodiment provides an electric double layer capacitor (EDLC) device for reflow soldering to a printed circuit board (PCB), the device comprising: a housing having high thermal conductivity for defining an opening and a cavity extending from the opening; a capacitor element housed within the cavity, the element including two carbon-based electrodes and a separator spirally wound with the electrodes, the separator maintaining the electrodes in a spaced apart, opposing arrangement; an electrolyte within the cavity to allow ionic conduction between the electrodes; a sealing element for sealing the opening; two terminals each extending between a respective first end located within the cavity and a respective second end located outside the cavity, the first ends electrically connected to the respective electrodes, the terminals extending through the openings such that the second ends are available for electrical connection to a PCB; Includes:

[0085] Another embodiment provides an electric double layer capacitor (EDLC) device for reflow soldering to a printed circuit board (PCB), the device comprising: a substantially cylindrical housing defining an opening and a cavity extending from the opening; a capacitor element housed within the cavity, the element including two carbon-based electrodes and a separator spirally wound with the electrodes, the separator maintaining the electrodes in a spaced apart, opposing arrangement; an electrolyte in the cavity for enabling ionic conduction between the electrodes, the electrolyte having a freezing point of 0°C or less and a boiling point of 200°C or more at 1 atmosphere pressure; a sealing element for sealing the opening; two terminals each extending between a first end disposed within the cavity and a second end disposed outside the cavity, the first ends electrically connected to respective electrodes, and the terminals extending through the openings such that the second ends are available for electrical connection to a PCB; Includes:

[0086] Another embodiment provides an electric double layer capacitor (EDLC) device for reflow soldering to a printed circuit board (PCB), the device comprising: a substantially cylindrical housing defining an opening and a cavity extending from the opening; a capacitor element housed within the cavity, the element including two carbon-based electrodes and a separator spirally wound with the electrodes, the separator maintaining the electrodes in a spaced apart, opposing arrangement; an electrolyte within the cavity to allow ionic conduction between the electrodes; a sealing element for sealing the opening; two terminals each extending between a respective first end located within the cavity and a respective second end located outside the cavity, the first ends electrically connected to the respective electrodes, the terminals extending through the openings such that the second ends are available for electrical connection to a PCB; Includes:

[0087] Another embodiment provides an electric double layer capacitor (EDLC) device for reflow soldering to a printed circuit board (PCB), the device comprising: a malleable housing defining an opening, a cavity extending from the opening, a sealing surface adjacent the opening, and a retention structure; a substantially cylindrical capacitor element housed within the cavity, the element including two carbon-based electrodes and a separator spirally wound with the electrodes, the separator maintaining the electrodes in a spaced apart, opposing arrangement; an electrolyte within the cavity to allow ionic conduction between the electrodes; a seal element for seating against the seal surface to seal the opening, the retaining structure maintaining the seal element seated; two terminals each extending between a first end disposed within the cavity and a second end disposed outside the cavity, the first ends electrically connected to respective electrodes, and the terminals extending through the openings such that the second ends are available for electrical connection to a PCB; Includes:

[0088] In one embodiment, the electrolyte has a boiling point at 1 atmosphere that is at least one of 210°C or higher, 220°C or higher, 230°C or higher, 240°C or higher, or 250°C or higher.

[0089] In one embodiment, the electrolyte has a freezing point at 1 atmosphere that is at least one of -10°C or lower, -20°C or lower, -30°C or lower, or -40°C or lower.

[0090] In one embodiment, the housing includes a substantially cylindrical first sidewall extending along a sidewall axis. In one embodiment, the first sidewall has a wall thickness of less than 1 mm. In one embodiment, the first sidewall has a wall thickness of less than 0.5 mm. In one embodiment, the wall thickness of the first sidewall is substantially uniform. In one embodiment, the first sidewall extends along the sidewall axis between a first end and a second end, the first end defining an opening, and the housing includes a second sidewall extending across the second end. In one embodiment, the first sidewall defines an opening and a sealing surface adjacent the opening for engaging the sealing element. In one embodiment, the first sidewall defines a retention structure for engaging the sealing surface to lock and retain the sealing element. In one embodiment, engagement between the sealing element and the sealing surface defines a compression seal. In one embodiment, the retention structure is integrally formed with the first sidewall. In one embodiment, the terminal is directly sealingly engaged with the sealing element. In one embodiment, the sealing element is one piece.

[0091] In one embodiment, the electrodes each include carbon particles. In one embodiment, the EDLC device includes a binder to provide cohesive force between the particles. In one embodiment, each electrode includes a current collector to electrically connect the carbon particles of that electrode to a respective terminal, and the binder provides adhesion between the particles of each electrode and the respective current collector. In one embodiment, the carbon particles have an average pore size greater than 2 nm.

[0092] In one embodiment, the electrolyte is an organic electrolyte having a freezing point of 0° C. or less and a boiling point of 200° C. or more at 1 atmosphere, and comprising at least one of an ionic liquid, an organic solvent comprising a cyclic or linear organic sulfur or sulfone compound and at least one organic salt, an organic liquid comprising a cyclic or linear carbonate ester and at least one organic salt, and an organic liquid comprising a cyclic lactone, such as gamma butyrolactone, and at least one organic salt.

[0093] In one embodiment, the organic sulfur is sulfolane. In one embodiment, the carbonate ester is propylene carbonate. In one embodiment, the organic solvent comprises gamma butyrolactone. In one embodiment, the organic liquid comprises a tetrafluoroborate salt, e.g., the organic salt comprises a tetrafluoroborate anion.

[0094] In one embodiment, each electrode includes a carbon-based layer and a current collector for electrically connecting the carbon-based layer to a respective terminal, and the two carbon-based electrodes and the separator are spirally wound together along a winding axis, with the separator extending beyond the electrodes along the winding axis. In one embodiment, the separator extends beyond the electrodes along the winding axis to define two opposing free ends inclined toward the winding axis.

[0095] Another embodiment provides an electric double layer capacitor (EDLC) device for reflow soldering to a printed circuit board (PCB), the device comprising: a housing for defining an opening and a cavity extending from the opening; a substantially cylindrical capacitor element contained within the cavity, the element including two electrodes each including carbon particles, a binder for providing cohesion between the particles within each binder, and a separator spirally wound with the electrodes, the separator maintaining the electrodes in a spaced apart, opposing arrangement, the binder including at least one of carboxymethyl cellulose (CMC), a salt of CMC (such as sodium carboxymethyl cellulose), polytetrafluoroethylene (PTFE), a salt of polystyrene sulfonic acid (PSS), such as a Group 1 or Group 2 metal salt of PSS including magnesium polystyrene sulfonate (MgPSS), sodium polystyrene sulfonate (NaPSS), lithium polystyrene sulfonate (LiPSS), and calcium polystyrene sulfonate (CaPSS), polyvinylidene fluoride (PVDF), and a polyimide; an electrolyte within the cavity to allow ionic conduction between the electrodes; a sealing element for sealing the opening; two terminals each extending between a first end disposed within the cavity and a second end disposed outside the cavity, the first ends electrically connected to respective electrodes, and the terminals extending through the openings such that the second ends are available for electrical connection to a PCB; Includes:

[0096] Another embodiment provides an electric double layer capacitor (EDLC) device for reflow soldering to a printed circuit board (PCB) having a PCB surface with two electrical pads, the device comprising: a base having a first surface facing the PCB surface and a second surface opposite the first surface; a housing for defining, in use, an opening facing the second surface and a cavity extending from the opening; A substantially cylindrical capacitor element housed within the cavity, the element comprising: two carbon-based electrodes, each electrode comprising carbon particles; and a porous separator spirally wound with the electrodes, the separator maintaining the electrodes in a spaced apart, opposing arrangement, and comprising one or more of polytetrafluoroethylene, cellulose fibers, polyacrylonitrile fibers, aramid fibers, and glass fibers; a capacitor element; an electrolyte in the cavity for enabling ionic conduction between the electrodes, the electrolyte having a freezing point of 0°C or less and a boiling point of 200°C or more at 1 atmosphere pressure; a sealing element for providing a compression seal to seal the opening; two terminals each extending between a first end disposed within the cavity and a second end disposed outside the cavity, the first ends electrically connected to respective electrodes, the terminals extending through the opening and the base such that, in use, the second ends are substantially parallel to the PCB surface and electrically connected to respective pads; Includes:

[0097] Another embodiment provides an electric device including at least one EDLC device of any one of the preceding embodiments.

[0098] Another embodiment includes a platform including at least one EDLC device according to any one of the above EDLC device embodiments and any one or more of at least one electric device according to the above electric device embodiments.

[0099] Another embodiment includes a system including one or more of at least one EDLC device according to any one of the above EDLC device embodiments, at least one electric device according to the above electric device embodiments, and at least one platform according to the above platform embodiments.

[0100] Another embodiment includes a printed circuit board having reflow soldered thereon at least one EDLC device according to any one of the above EDLC device embodiments.

[0101] Another embodiment includes a method of manufacturing an electric double layer capacitor (EDLC) device for reflow soldering to a printed circuit board (PCB), the method comprising: (a) providing a substantially cylindrical malleable housing having an opening and a cavity extending from the opening; (b) plastically deforming the housing to define a sealing surface adjacent the opening; (c) plastically deforming the housing to define a retention structure; (d) spirally winding two carbon-based electrodes together with a separator to provide a substantially cylindrical capacitor element, the separator maintaining the electrodes in a spaced apart, opposing arrangement; (e) receiving a capacitor element within the cavity; (f) providing an electrolyte within the cavity to enable ionic conduction between the electrodes; (g) providing a sealing element for seating against the sealing surface to seal the opening, wherein a retaining structure maintains the sealing element seated; (h) providing two terminals each extending between a first end disposed within the cavity and a second end disposed outside the cavity, the first ends electrically connected to the respective electrodes and the terminals extending through the openings such that the second ends are available for electrical connection to a PCB; Includes:

[0102] In one embodiment, step (e) precedes step (b). In one embodiment, step (e) precedes step (c). In one embodiment, step (e) precedes step (f). In one embodiment, steps (b) and (c) occur contemporaneously. In one embodiment, steps (b) and (c) occur simultaneously.

[0103] Another embodiment includes a method of manufacturing an electric double layer capacitor (EDLC) device for reflow soldering to a printed circuit board (PCB) having a PCB surface with two electrical pads, the method comprising: providing a base having a first surface facing the PCB surface and a second surface opposite the first surface; defining with the housing an opening facing the second surface in use and a cavity extending from the opening; receiving a substantially cylindrical capacitor element within the cavity, the element comprising: two carbon-based electrodes, each electrode comprising carbon particles; a porous separator spirally wound with the electrodes, the separator maintaining the electrodes in a spaced apart opposing arrangement and comprising one or more of polytetrafluoroethylene, cellulose fiber, polyacrylonitrile fiber, aramid fiber, and glass fiber; Steps and providing an electrolyte within the cavity to enable ionic conduction between the electrodes, the electrolyte having a freezing point of 0°C or less and a boiling point of 200°C or more at 1 atmosphere pressure; providing a compression seal with a sealing element to seal the opening; providing two terminals each extending between a first end disposed within the cavity and a second end disposed outside the cavity, the first ends electrically connected to respective electrodes and the terminals extending through the openings and the base such that, in use, the second ends are substantially parallel to the PCB surface and electrically connected to respective pads; Includes:

[0104] Another embodiment includes a method of manufacturing an electric double layer capacitor (EDLC) device for reflow soldering to a printed circuit board (PCB), the method comprising: defining with a housing an opening and a cavity extending from the opening; receiving a substantially cylindrical capacitor element within the cavity, the element including two carbon-based electrodes and a separator spirally wound together with the electrodes, the separator maintaining the electrodes in a spaced apart, opposing arrangement; providing an electrolyte within the cavity to enable ionic conduction between the electrodes, the electrolyte having a freezing point of 0°C or less and a boiling point of 200°C or more at 1 atmosphere pressure; sealing the opening with a sealing element; providing two terminals, each extending between a first end disposed within the cavity and a second end disposed outside the cavity, the first ends electrically connected to the respective electrodes and the terminals extending through the openings such that the second ends are available for electrical connection to a PCB; Includes:

[0105] Another embodiment includes a method of manufacturing an electric double layer capacitor (EDLC) device for reflow soldering to a printed circuit board (PCB), the method comprising: defining with a housing an opening and a cavity extending from the opening; housing a capacitor element within the cavity, the element including two carbon-based electrodes and a separator for maintaining the electrodes in a spaced, opposing arrangement; providing an electrolyte within the cavity to enable ionic conduction between the electrodes, the electrolyte having a freezing point of 0°C or less and a boiling point of 200°C or more at 1 atmosphere pressure; providing a compression seal with a sealing element to seal the opening; providing two terminals, each extending between a first end disposed within the cavity and a second end disposed outside the cavity, the first ends electrically connected to the respective electrodes and the terminals extending through the openings such that the second ends are available for electrical connection to a PCB; Includes:

[0106] Another embodiment includes a method of manufacturing an electric double layer capacitor (EDLC) device for reflow soldering to a printed circuit board (PCB), the method comprising: defining with a housing an opening and a cavity extending from the opening; receiving a substantially cylindrical capacitor element within the cavity, the element including two carbon-based electrodes and a separator spirally wound together with the electrodes, the separator maintaining the electrodes in a spaced apart, opposing arrangement; providing an electrolyte within the cavity to allow ionic conduction between the electrodes; sealing the opening with a sealing element; providing two terminals, each extending between a first end disposed within the cavity and a second end disposed outside the cavity, the first ends electrically connected to the respective electrodes and the terminals extending through the openings such that the second ends are available for electrical connection to a PCB; Includes:

[0107] Another embodiment includes a method of manufacturing an electric double layer capacitor (EDLC) device for reflow soldering to a printed circuit board (PCB), the method comprising: defining an opening and a cavity extending from the opening with a malleable housing; housing a capacitor element within the cavity, the element including two carbon-based electrodes and a separator spirally wound together with the electrodes, the separator maintaining the electrodes in a spaced apart, opposing arrangement; providing an electrolyte within the cavity to allow ionic conduction between the electrodes; sealing the opening with a sealing element; providing two terminals each extending between a respective first end located within the cavity and a respective second end located outside the cavity, the first ends being electrically connected to the respective electrodes and the terminals extending through the openings such that the second ends are available for electrical connection to a PCB; Includes:

[0108] Another embodiment includes a method of manufacturing an electric double layer capacitor (EDLC) device for reflow soldering to a printed circuit board (PCB), the method comprising: using a housing having a high thermal conductivity to define an opening and a cavity extending from the opening; housing a capacitor element within the cavity, the element including two carbon-based electrodes and a separator spirally wound together with the electrodes, the separator maintaining the electrodes in a spaced apart, opposing arrangement; providing an electrolyte within the cavity to allow ionic conduction between the electrodes; sealing the opening with a sealing element; providing two terminals each extending between a respective first end located within the cavity and a respective second end located outside the cavity, the first ends being electrically connected to the respective electrodes and the terminals extending through the openings such that the second ends are available for electrical connection to a PCB; Includes:

[0109] Another embodiment includes a method of manufacturing an electric double layer capacitor (EDLC) device for reflow soldering to a printed circuit board (PCB), the method comprising: defining an opening and a cavity extending from the opening with a substantially cylindrical housing; housing a capacitor element within the cavity, the element including two carbon-based electrodes and a separator spirally wound together with the electrodes, the separator maintaining the electrodes in a spaced apart, opposing arrangement; providing an electrolyte within the cavity to enable ionic conduction between the electrodes, the electrolyte having a freezing point of 0°C or less and a boiling point of 200°C or more at 1 atmosphere pressure; sealing the opening with a sealing element; providing two terminals, each extending between a first end disposed within the cavity and a second end disposed outside the cavity, the first ends electrically connected to the respective electrodes and the terminals extending through the openings such that the second ends are available for electrical connection to a PCB; Includes:

[0110] Another embodiment includes a method of manufacturing an electric double layer capacitor (EDLC) device for reflow soldering to a printed circuit board (PCB), the method comprising: defining with a housing an opening and a cavity extending from the opening; receiving a substantially cylindrical capacitor element within the cavity, the element including two electrodes each including carbon particles, a binder for providing cohesion between the particles within each binder, and a separator spirally wound with the electrodes, the separator maintaining the electrodes in a spaced apart, opposing arrangement, the binder including at least one of carboxymethyl cellulose (CMC), a salt of CMC (such as sodium carboxymethyl cellulose), polytetrafluoroethylene (PTFE), a salt of polystyrene sulfonic acid (PSS), such as a Group 1 or Group 2 metal salt of PSS including magnesium polystyrene sulfonate (MgPSS), sodium polystyrene sulfonate (NaPSS), lithium polystyrene sulfonate (LiPSS), and calcium polystyrene sulfonate (CaPSS); polyvinylidene fluoride (PVDF); and polyimide; providing an electrolyte within the cavity to allow ionic conduction between the electrodes; sealing the opening with a sealing element; providing two terminals, each extending between a first end disposed within the cavity and a second end disposed outside the cavity, the first ends electrically connected to the respective electrodes and the terminals extending through the openings such that the second ends are available for electrical connection to a PCB; Includes:

[0111] Another embodiment includes a method of manufacturing an electric double layer capacitor (EDLC) device for reflow soldering to a printed circuit board (PCB), the method comprising: defining an opening and a cavity extending from the opening with a substantially cylindrical housing; housing a capacitor element within the cavity, the element including two carbon-based electrodes and a separator spirally wound together with the electrodes, the separator maintaining the electrodes in a spaced apart, opposing arrangement; providing an electrolyte within the cavity to allow ionic conduction between the electrodes; sealing the opening with a sealing element; providing two terminals each extending between a respective first end located within the cavity and a respective second end located outside the cavity, the first ends being electrically connected to the respective electrodes and the terminals extending through the openings such that the second ends are available for electrical connection to a PCB; Includes:

[0112] Another embodiment includes a method of manufacturing an electric double layer capacitor (EDLC) device for reflow soldering to a printed circuit board (PCB), the method comprising: defining with a malleable housing an opening, a cavity extending from the opening, a sealing surface adjacent the opening, and a retention structure; receiving a substantially cylindrical capacitor element within the cavity, the element including two carbon-based electrodes and a separator spirally wound together with the electrodes, the separator maintaining the electrodes in a spaced apart, opposing arrangement; providing an electrolyte within the cavity to allow ionic conduction between the electrodes; Seating a sealing element against the sealing surface to seal the opening, wherein a retaining structure maintains the sealing element seated; providing two terminals, each extending between a first end disposed within the cavity and a second end disposed outside the cavity, the first ends electrically connected to the respective electrodes and the terminals extending through the openings such that the second ends are available for electrical connection to a PCB; Includes:

[0113] Throughout this specification, references to "one embodiment," "some embodiments," "another embodiment," "further embodiment," "an embodiment," etc. mean that a particular feature, structure, or characteristic described in connection with an embodiment is included in at least one embodiment of the invention. Thus, the appearances of the phrases "in one embodiment," "some embodiments," "in an embodiment," or similar phrases in various places throughout this specification do not necessarily all refer to the same embodiment, although they may. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments, as would be apparent to one of ordinary skill in the art from this disclosure.

[0114] As used herein, unless otherwise specified, the use of ordinal adjectives such as "first," "second," "third," etc., merely indicates that different instances of similar objects are being referred to and is not intended to imply that the objects so modified must be in a given order in time, space, ranking, or in any other way.

[0115] In the following claims and the specification body of this specification, any one of the terms "comprising," "comprised of," or "which comprises" is an open term meaning "including at least the following elements / features, but not excluding other elements / features," unless expressly expressed otherwise. Therefore, when used in a claim, the term "comprising" and similar terms should not be construed as being limited to the means, elements, or steps listed thereafter. For example, the scope of the expression "a device comprising A and B" is not limited to a device consisting only of elements A and B. As used herein, any one of the terms "including," "which includes," or "that includes," or similar terms is an open term meaning "including at least the elements / features following the term, but not excluding other elements / features," unless expressly expressed otherwise. Therefore, the term "including" is synonymous with "comprising" and means "comprising."

[0116] As used herein, the term "exemplary" is used in the sense of providing an example, rather than denoting a quality. That is, an "exemplary embodiment" is an embodiment provided as an example, not necessarily an embodiment of exemplary quality. Terms such as "for example" are used analogously herein.

[0117] The term "carbon-based," when used herein with respect to electrodes of SMD EDLC devices, is intended as a broad term to describe one or more specific components of the electrode. These components can include one or more of the following: carbon particles, such as one or a combination of activated carbon particles, or carbon black particles (whether amorphous or not), or carbide-derived carbon particles; graphene; carbon nanotubes; carbon fiber; expanded carbon; carbon aerogel; and the like. The components can also include mixtures of types and / or grades of such carbon-based materials. By way of example, the carbon particle component can include a combination of similar types of components, such as high-surface-area carbon particles (activated carbon) and highly conductive carbon particles (carbon black). By way of further example, the carbon particle component can include a combination of different types of components, such as high-surface-area carbon particles (activated carbon) and carbon nanotubes. In some embodiments, the carbon-based electrode includes non-carbon-based components. For example, in one embodiment, the electrode includes a binder to provide cohesion between the carbon particles (and any other particles) within the electrode. It will be understood that binderless electrodes are used in other embodiments.

[0118] One of the important characteristics of an SMD EDLC device is its DC capacitance, I, in farads. This capacitance is measured by the amount of DC current (I) drawn from a fully charged EDLC device. D ) and the time it takes to discharge from the first DC voltage (V1) to the second voltage (V2) (T D The DC capacitance, C, for a given EDLC device is calculated according to the following formula:

[0119]

number

[0120] For similarly manufactured SMD EDLC devices, there is a variation in the measured DC capacitance from device to device. Typically, the allowable manufacturing tolerance for DC capacitance is ±20% from the rated capacitance value of the device, although some manufacturing processes require tighter tolerances. In further manufacturing processes, the device tolerance is ±30% from the rated capacitance value.

[0121] Another important characteristic of SMD EDLC devices is their equivalent series resistance (ESR) in ohms. The ESR of a given EDLC device can be estimated as the real impedance of the device measured at 1 kHz using the alternating current method.

[0122] The term "liquid" is used herein to describe one or more elements, compounds, materials, or other substances. Unless expressly indicated otherwise, the term "liquid" herein is intended to indicate that the described element, compound, material, or substance has a state that is between the freezing point and boiling point of the respective element, compound, material, or substance.

[0123] Any numerical range described herein is intended to include all subranges subsumed therein. For example, a range "from x to y" or "between x and y" is intended to include all subranges between x and y, including the endpoints of the ranges x and y.

[0124] Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0125] [Figure 1] FIG. 1 is a perspective view of a first exemplary EDLC device. [Figure 2] FIG. 2 is a side view of the EDLC device of FIG. 1 mounted on a PCB. [Figure 3] FIG. 2 is a rear view of the EDLC device of FIG. 1. [Figure 4]FIG. 2 is a bottom view of the EDLC device of FIG. 1. [Figure 5] FIG. 2 is a plan view of the EDLC device of FIG. 1. [Figure 6] 2 is a bottom perspective view of the EDLC device of FIG. 1 with terminals formed to latchingly retain the base to the housing prior to attachment to the plastic base. FIG. [Figure 7] 2 is a perspective view of the capacitor element of the EDLC device of FIG. 1, with the radially outer ends of the separator and electrodes shown partially unwound. [Figure 8] FIG. 2 is a perspective view of one of the terminals of the EDLC device of FIG. 1. [Figure 9] FIG. 9 is a rear view of the terminal of FIG. 8. [Figure 10] FIG. 2 is a perspective view of a sealing element of the EDLC device of FIG. 1 in the form of a rubber lid. [Figure 11] FIG. 8 is an enlarged cross-sectional view showing adjacent edges of a single turn of electrode and separator in the element of FIG. 7. [Figure 12] FIG. 10 is a perspective view of a housing for a second exemplary EDLC device. [Figure 13] FIG. 13 is a perspective view of the housing of FIG. 12 aligned with the assembled capacitor element and lid for the second exemplary EDLC device. [Figure 14] 13 is a perspective view of the assembled capacitor element and lid contained within the housing of FIG. 12. [Figure 15] FIG. 13 is a perspective view of the housing of FIG. 12 after a first forming operation. [Figure 16] FIG. 13 is a perspective view of the housing of FIG. 12 after a second forming operation. [Figure 17] FIG. 17 is an enlarged cross-sectional view taken along section line 17-17 of FIG. 16. [Figure 18] 2 is a flowchart illustrating a method for manufacturing the SMD EDLC of FIG. 1. [Figure 19] 1 is a table of performance characteristics for an exemplary embodiment. [Figure 20]1 is a schematic diagram (not to scale) of the thermal profile for the housing of an SMD EDLC. DETAILED DESCRIPTION OF THE INVENTION

[0126] The above drawings are provided to illustratively illustrate features included in certain described embodiments and are not necessarily drawn to scale.

[0127] Referring to FIGS. 1 through 7, an electric double-layer capacitor (EDLC) device 1 for reflow soldering to a printed circuit board (PCB) 2 is shown. Device 1 includes a substantially cylindrical, thin-walled, malleable aluminum housing 3 extending along a housing axis 4 between an open end 5 and a closed end 6. Housing 3 has high thermal conductivity and defines a substantially circular opening 7 adjacent end 5 and a substantially cylindrical cavity 8 extending from the opening along axis 4 and terminating at end 6, as best shown in FIG. 6. A substantially cylindrical capacitor element 9, shown in FIG. 7, is complementarily housed within cavity 8 and includes two elongated, porous, double-sided, high-surface-area, carbon-based electrodes 11 and 12. As best shown in FIG. 6, separators in the form of two elongated, paper-based separator sheets 13 and 14 are alternately arranged and spirally wound with electrodes 11 and 12. Sheets 13 and 14 maintain electrodes 11 and 12 in a spaced-apart, opposing arrangement. An electrolyte is contained within cavity 6 to impregnate porous electrodes 11 and 12 and sheets 13 and 14 and enable ionic conduction between electrodes 11 and 12. The electrolyte has a freezing point below 0°C and a boiling point above 200°C at 1 atmosphere pressure, and is described in further detail below. A sealing element in the form of a one-piece, substantially cylindrical butyl rubber cap 15 extends across and seals opening 7. Shown in more detail in FIGS. 8 and 9 is one of two highly conductive, similar metal terminals 17 and 18. In use, terminals 17 and 18 each extend between a first end 19 disposed within cavity 8 and a second end 20 disposed outside cavity 8. End 19 is electrically connected to the respective electrodes 11 and 12, and terminals 17 and 18 extend through opening 7 such that second end 20 is available for electrical connection to PCB 2, as best shown in FIG. 6.

[0128] In this embodiment, element 9 is pre-assembled and helically wound along a winding axis prior to placement within cavity 8. This winding axis is also the notional axis for substantially cylindrical element 9. When element 9 is received within cavity 8, the winding axis is substantially aligned with axis 4. Similarly, substantially cylindrical lid 15 includes an axis in assembled device 1 that is also substantially aligned with the housing axis. Thus, for the exemplary embodiments described herein, the housing axis, winding axis, notional axis for element 9, and axis for lid 15 are considered to be the same in the final assembled EDLC device and are all labeled with reference numeral 4 in the drawings. However, it will be understood that these different axes are functionally distinct and that all axes will substantially correspond directly only after the associated EDLC device is assembled.

[0129] Unless expressly indicated to the contrary, the term "substantially," when used herein to modify a qualitative characteristic of an object, indicates that the characteristic is essentially so and that any deviation from the ideal of the characteristic is insignificant from the perspective of the object's practical performance. As an example, consider element 9, described above as "substantially cylindrical." This indicates that element 9 may not provide a precisely cylindrical outer sidewall due to the spirally wound nature of element 9, and may not provide two perfectly flat circular ends due to variations in the axial length and degree of overlap of the spirally wound components contained within element 9. However, for practical application in an SMT device, element 9 can be considered cylindrical. Furthermore, unless expressly indicated to the contrary, the term "substantially" when used herein to modify a quantitative characteristic of an object indicates that the characteristic is essentially so and that deviations from the specified amount are within ±5%, ±4%, ±3%, ±2%, and ±1%.

[0130] Although one or more of the embodiments are described with reference to one or a combination of particular manufacturing steps, it will be understood by those skilled in the art that non-SMT cylindrical EDLC devices are known and the manufacture of such devices is also known. In determining the specific manufacturing steps for an embodiment, one skilled in the art can select known manufacturing steps other than those described herein, or combinations of manufacturing steps instead of or in addition to those described herein, in the same or different order, as best suited to the particular embodiment.

[0131] In another embodiment, the separator comprises a single sheet folded over itself to define two sheets connected together along a fold line. One of the electrodes is disposed between the two sheets, and the other electrode is disposed on the outside of one of the sheets. The resulting stack is then spirally wound together to define a substantially cylindrical capacitor element 9. In a further embodiment, the two sheets are dissimilar, with one including, for example, a larger axial width than the other. As a further example, in one embodiment, one of the sheets is longer than the other sheet normal to axis 4 and, when spirally wound, extends further circumferentially to define the radial outer surface of element 9.

[0132] Device 1 has a voltage rating of 3 volts, a capacitance of 3.4 Farads, and an ESR of 82 mΩ. Other embodiments provide different combinations of voltage rating, capacitance, and ESR.

[0133] Housing 3 includes a substantially cylindrical, thin-walled, malleable sidewall 25 extending between end 5 and end 6, and a substantially planar, circular, thin-walled sidewall 26 extending over end 6 and integrally formed with sidewall 25. Housing 3 is initially formed with sidewall 25 being substantially uniform in the axial direction; however, during manufacture and assembly of device 1, sidewall 25 undergoes two separate forming operations that change the shape of sidewall 25 from its initial regular cylindrical shape. The first of these forming operations occurs following insertion of the assembled combination of element 9 and lid 15 into cavity 8, with element 9 adjacent end 6 and lid 15 adjacent end 5. The first forming operation involves gradual plastic deformation of sidewall 25 to include a substantially uniform, continuous circumferential recessed channel 27 adjacent end 5 and extending radially inward into the axial gap between element 9 and lid 15. Channel 27 defines a complementary convex structure within cavity 8 that partially defines a sealing surface for lid 15 within housing 3. The shape and function of this sealing surface will be described in more detail below with reference to another embodiment of the invention.

[0134] In further embodiments, element 9 includes three or more electrodes and a separator sheet to maintain the necessary physical separation between all of the electrodes. For example, in some embodiments, four electrodes are spirally wound together in element 9, two of which are electrically connected to terminal 17 to define composite electrode 11, and two of which are electrically connected to terminal 18 to define composite electrode 12. In other exemplary embodiments, device 1 includes two additional terminals to allow separate external electrical connections to each of the four electrodes. It will be understood by those skilled in the art that five or more electrodes can be included in element 9.

[0135] As best shown in FIG. 10 , lid 15 includes an inner, substantially circular surface 29, an outer, substantially circular surface 30, and a substantially cylindrical, circumferentially continuous sidewall 31 extending between surfaces 29 and 30. Lid 15 also includes two spaced-apart similar openings 33 and 34 extending between surfaces 29 and 30, which sealingly engage terminals 17 and 18, respectively, intermediate ends 19 and 20, in an interference fit. Lid 15 defines a compression seal with terminals 17 and 18, which in this embodiment has a seal path substantially equal to the axial distance between surfaces 29 and 30. As shown in FIG. 10 , in the rest state, the distance between surfaces 20 and 30 is 3 mm. However, when lid 15 is installed in housing 3, surface 31 is compressed substantially uniformly radially inward about its circumference, which has the effect of increasing the axial dimension of lid 15 and therefore increasing the seal path length between surfaces 29 and 20. In other embodiments, lid 15 has different dimensions to provide different seal path lengths.

[0136] In a further embodiment, element 9 is initially received within cavity 8 without lid 15. Following the first forming operation, lid 15 is then advanced axially such that ends 20 of terminals 17 and 18 are received by and extend through respective openings 33 and 34, and lid 15 is received within cavity 8.

[0137] Following the first forming operation, with the lid 15 positioned within the cavity 8, the radially outer peripheral edge of the surface 29 abuts against a convex structure within the cavity 8 defined by the channel 27. This partially assembled device 1 then undergoes a second forming operation that progressively plastically deforms the end 5 of the sidewall 25 to define a retention structure for the lid 15. More specifically, the retention structure in this embodiment is a continuous circumferential flange 28 extending radially inward at the end 5 of the housing 3. During formation of the flange 28, the flange 28 is pressed into biasing engagement with the radial outer periphery of the surface 30. The lid 15 elastically deforms and is biased against the seal-engaging flange 28. The lid 15 is then clampingly engaged to the housing 3 between the flange 28 and the convex structure within the cavity 8 defined by the channel 27. Side wall 31 of lid 15 also sealingly abuts the inner surface of side wall 25 extending between flange 28 and the convex structure within cavity 8 defined by channel 27. Housing 3 therefore defines a sealing surface against which lid 15 abuts to effect a compression seal that includes a sealing path that is longer than the axial distance between surfaces 29 and 30.

[0138] Although the first forming operation and the second forming operation are described as two separate operations, it will be understood by those skilled in the art that they may be performed in rapid succession at a single forming station. In some embodiments, the forming operations occur contemporaneously (i.e., the operations overlap in time), while in further embodiments, the forming operations occur substantially simultaneously.

[0139] The focus of the above description is on the nature of the forming operations. It will be understood that there are several steps in addition to or between the first and second operations that have been omitted for clarity in articulating the details of the forming operations above.

[0140] As best shown in Figures 8 and 9, end 19 of terminal 17 includes two opposing, relatively large surface area faces 37 and 38. End 19 of terminal 17 is formed from aluminum, and end 20 is formed from copper and includes a tin coating to facilitate making good electrical contact with an associated contact pad on PCB 2 during and following the reflow process. In other embodiments, a different coating, such as gold, is used. In further embodiments, ends 19 and 20 are formed from different conductive materials.

[0141] In use, the relatively large surface area face 37 of terminal 17 abuts electrode 11 to define a correspondingly large electrical contact patch with the electrode. End 19 is then fixedly connected physically and electrically to electrodes 11 and 12 prior to spirally winding the electrodes 11 and 12 with sheets 13 and 14. In this embodiment, terminal 17 is fixed to electrode 11 mechanically by riveting, wire stitching, or the like. As described in more detail below, electrodes 11 and 12 include a porous carbon-based layer and an aluminum current collector. In this embodiment, each terminal is attached such that electrical contact is effected directly between the terminal and the current collector of the respective electrode.

[0142] After the spiral winding, face 38 of terminal 17 abuts separator sheet 13, electrically insulating it from adjacent electrode 12. Terminal 17 includes an axis of symmetry 39 parallel to and radially offset from axis 4 immediately after the spiral winding of electrodes 11 and 12 and sheets 13 and 14. Terminals 17 and 18 are fixedly connected to their respective electrodes 11 and 12 such that, after the spiral winding of the electrodes and separator sheets, the terminals are positioned substantially diametrically opposed and their respective axes 39 are substantially radially equidistant from axis 4. In one embodiment, the relative radial positions of the terminals are other than those described above. For example, in one embodiment, the terminals are offset from axis 4 by different distances. Additionally, in another embodiment, the terminals are circumferentially offset by an angle other than 180°.

[0143] Terminal 17 includes a mounting structure intermediate its ends 19 and 20 in the form of a ferrule 41 integrally formed with end 19. The ferrule includes a substantially cylindrical outer surface 42 for defining a continuous sealing surface and a cavity (not shown) for receiving and securely physically and electrically engaging end 20. Once end 20 is received within the cavity, the secure physical and electrical engagement between ferrule 41 and end 20 is affected by inserting a dose of a securing compound into the cavity. In some embodiments, the securing compound is a conductive epoxy; in other embodiments, a different securing compound, such as solder, is used. In a further embodiment, ends 19 and 20 are securely connected by ultrasonic welding.

[0144] In some embodiments, face 42 of ferrule 41 is non-cylindrical to create a longer seal path relative to lid 15. For example, in one embodiment, face 42 is contoured with circumferentially and / or radially extending grooves or other structures to provide a tortuous seal path relative to lid 15. That is, when terminals 17 and 18 are received within their respective openings 33 and 34, lid 15 automatically resiliently deforms in and around the grooves or other structures to sealingly engage face 42 and define a seal path longer than the axial distance between faces 29 and 30.

[0145] End 20 of terminal 17 includes two opposing, relatively large-area faces 45 and 46 joined by a relatively narrow face 47. Application of a force normal to faces 45 and 46 facilitates plastic deformation of end 20 from a first position illustratively shown in Figures 6, 8, and 9 to a second position illustratively shown in Figures 1 through 5 (with particular reference to Figure 4).

[0146] Although only terminal 17 has been explicitly described above, it will be understood that terminal 18 is a similar terminal and shares the same structural and functional characteristics.

[0147] Device 1 includes a non-conductive, hard, high-temperature polymer plastic base 51 that is molded to facilitate mechanical handling of device 1 and placement of device 1 on PCB 2. Base 51 also functions to maintain ends 20 of terminals 17 and 18 substantially perpendicular to axis 4 and, in use, substantially parallel to the adjacent surface of PCB 2. This facilitates use of device 1 in a reflow process, as device 1 is configured for mechanical handling and placement on PCB 2 such that ends 20 are parallel to and overlap the generally horizontally extending electrical pads on PCB 2 to which terminals 17 and 18 are physically and electrically connected.

[0148] The base 51 is integrally formed and includes two circular, spaced apart through openings 53 and 54 for receiving the ends 20 of the respective terminals 17 and 18 when the end 5 of the housing 3 is engaged with the base. On its underside, the base 51 includes four spaced apart, protruding mounting structures 55 for abutting adjacent surfaces of the PCB 2 in use.

[0149] For example, by comparing FIGS. 4 and 6 , it will be noted that after terminals 17 and 18 are received within openings 53 and 54, ends 20 of the terminals are plastically deformed perpendicular to surfaces 45 and 46 so that ends 20 extend substantially perpendicular to both end 19 and axis 38 to lock and retain base 51 in engagement with end 54. Furthermore, the deformation of ends 20 of terminals 17 and 18 is such that they extend away from each other along a common line, with surfaces 46 and 45 respectively available for presentation for abutment with two correspondingly spaced-apart electrical pads 56 on PCB 2. (See particularly FIG. 2 .) The pads extend along top surface 2 a of PCB 2, each providing a relatively large upper-facing surface area available for contact with end 20 of respective terminals 17 and 18. In use, surfaces 45 and 46 of end 20 extend substantially parallel to adjacent top surface 2 a of PCB 2 and the exposed top surfaces of respective pads 56. The relatively large exposed top surfaces of pads 56 accommodate mechanical placement tolerances of device 1 on PCB 2 and contribute to establishing good electrical and physical connections between ends 20 and their respective pads after PCB 2 and device 1 are passed together through a reflow oven.

[0150] It will be understood that PCB2 can be single-sided, double-sided, single-layered, multi-layered, or otherwise, depending on its design. PCB2 also includes a predetermined arrangement of tracks, pads, vias, and other structures to provide the conductive paths and connection points necessary to mount the necessary electronic components to the PCB. While reference is made herein to PCB2 having two pads 56, this is done to simplify the disclosure of the embodiments and does not imply that PCB2 need have only two pads.

[0151] 3, the base 51 has a first surface 51a (the lower surface in use) facing the surface 2a, and a second surface 51b (the upper surface in use) opposite the surface 51a. The opening 7 faces the surface 51b in use.

[0152] It will also be noted, particularly from FIG. 4 , that base 51 has two continuous linear channels 57 and 58 along which end portions 20 of respective terminals 17 and 18 extend. Channel 57 extends in a first direction from opening 53 and terminates at a first side of base 51, and channel 58 extends from opening 54 in a second direction opposite the first direction and terminates at a second side of base 51 opposite the first side. End portions 20 are partially nested within respective channels 57 and 58 and extend beyond each side of base 51. In other embodiments, channels 57 and 58 are omitted. In one embodiment, either or both of channels 57 and 58 extend through base 51 to define respective elongated open-shaped openings.

[0153] In one embodiment, the ends 20 remain spaced apart but extend in the same direction. In one embodiment, the ends 20 extend away from one another but not along a common line. In another embodiment, the ends 20 extend perpendicularly away from one another.

[0154] In one embodiment, the functions of openings 53 and 54 are performed by a single larger opening. In one embodiment, base 51 includes conductive portions (not shown) in the form of conductive pads that, in use, define extensions of respective ends 20. In one embodiment, the conductive portions extend partially along face 51 a and, in use, abut end 20. In one embodiment, the conductive portions extend along respective channels 57 and 58. The conductive portions provide terminals 17 and 18, and particularly end 20, with a larger surface area for the solder to affect the necessary electrical and physical connection with PCB 2.

[0155] Base 51 is non-conductive and can withstand the thermal shock imparted during the reflow process without experiencing any significant physical deformation or other structural degradation. In this embodiment, base 51 is made substantially from polyphthalamide (PPA). In other embodiments, other materials or combinations of materials are used, including one or more of polyetheretherketone (PEEK), liquid crystal polymer (LCP), and similar materials that are stable at temperatures above 200°C.

[0156] Referring particularly to FIG. 7 , electrode 11, in its unwound state, is substantially rectangular and elongated in a direction perpendicular to axis 4. Electrode 11 includes two substantially parallel elongated edges 61 and 62 spaced apart along axis 4. Electrode 11 includes a radially outer end 63 having an axially extending edge 64 perpendicular to and joining edges 61 and 62. Similarly, electrode 12, in its unwound state, is substantially rectangular and elongated in a direction perpendicular to axis 4. Electrode 12 includes two substantially parallel elongated edges 65 and 66 spaced apart along axis 4, substantially the same as edges 61 and 62. Furthermore, when helically wound to form element 9, edges 61 and 62 abut and overlap edges 65 and 66, respectively. Electrode 12 includes a radially outer end 67 having an axially extending edge 68 that is perpendicular to and joins both edges 65 and 66. In the helically wound configuration, edges 64 and 68 abut, i.e., in the outermost spiral of the electrode within element 9, edges 64 and 68 substantially circumferentially overlap.

[0157] In its unwound state, sheet 13 is substantially rectangular and elongated, and includes two substantially parallel, elongated edges 69 and 70 spaced apart along axis 4 by a distance greater than the axial distance between edges 61 and 62, and thus greater than the axial distance between edges 65 and 66. Furthermore, edge 69 extends axially beyond both edges 61 and 65, and edge 70 extends axially beyond edges 62 and 66 in the opposite direction from edge 69. Sheet 13 includes a radially outer end 71 having an axially extending edge 72 extending perpendicular to and joining both edges 69 and 70. When helically wound to form element 9, edge 72 extends circumferentially beyond edges 64 and 68. Similarly, in its unwound state, sheet 14 is substantially rectangular and elongated, including two elongated edges 73 and 74 spaced apart along axis 4 to overlap edges 69 and 70, respectively. Sheet 14 includes a radially outer end 75 having an axially extending edge 76 perpendicular to and joining both edges 73 and 74. In the spirally wound configuration, edge 74 extends circumferentially beyond edge 72 and is secured to itself by adhesive strip 77. In some embodiments, edge 76 extends beyond edge 72 by more than one wrap of sheet 14 around element 9, and in some embodiments, by multiple wraps of sheet 14. The additional wrap of sheet 14 radially outward of element 9 provides one or more of: increased frictional engagement at the peripheral edges of element 9, and therefore additional structural integrity for element 9; and increased electrical insulation of the edges of the electrode from unintentional contact with sidewall 26 or other conductive elements.

[0158] Further details of the elongated edge of a single turn of spirally wound element 9 are shown in Figure 11. More specifically, with reference to that figure, electrode 11 includes a first carbon-based layer 81 having a thickness of 20 microns, a second carbon-based layer 82 having a thickness of 20 microns, and an intermediate aluminum sheet current collector 83 having a thickness of 20 microns to which carbon-based layers 81 and 82 are attached and electrically connected. Similarly, electrode 12 includes a third carbon-based layer 85 having a thickness of 20 microns, a fourth carbon-based layer 86 having a thickness of 20 microns, and an intermediate aluminum sheet current collector 87 having a thickness of 20 microns to which layers 85 and 86 are attached and electrically connected. It will be noted by those skilled in the art that edges 61 and 65 substantially overlap axially, with ends 69 and 73 located axially outward of edges 61 and 65. Furthermore, during the spiral winding operation to form element 9, the spirally wound components are maintained under tension to ensure a tight and secure fit and contribute to the structural integrity of the ultimately formed element. For some separator sheet materials during the spiral winding operation, this tension, in combination with the material properties of the sheets, results in deformation of the axially outer edges radially inward toward axis 4, providing partial or complete overlap of edges 61 and 65 with sheets 13 and 14, respectively. In FIG. 11, complete overlap is shown. For other separator sheet materials, or for lower applied tensions, deformation may not occur automatically. In such embodiments, angled rollers or guides can be used in the winding operation to mechanically induce deformation or other deflection of sheets 13 and 14.

[0159] 11 shows only edges 69 and 70 of separator sheets 13 and 14, those skilled in the art will understand that a corresponding effect is achieved using edges 70 and 74. Furthermore, while only a single wrap of element 9 is shown in FIG. 11, it will be understood that other wraps of sheets 13 and 14 on element 9 can be similarly formed.

[0160] In other embodiments, the carbon layer has a thickness other than 20 microns. Typical thickness ranges for such electrodes are from about 10 microns to 200 microns, although thicknesses outside this range can also be used.

[0161] The separator sheets used in the above embodiments are made from nonwoven fibers, more specifically, each sheet includes cellulose fibers. Sheets 13 and 14 each have a thickness of approximately 30 microns. For the selected separator sheets, this thickness has been found to be suitable for spirally wound devices in which tension is applied to the winding of the electrodes and separator sheet together. Because the separator sheets are highly porous, if they are made too thin, they are susceptible to allowing short connections between electrodes, which can cause EDLC device failure. In other embodiments, thinner separators can be used when lower tensions are used in winding the capacitor elements or when a higher manufacturing defect rate can be tolerated.

[0162] In some embodiments, paper-based sheets 13 and 14 include a polymer to provide either or both additional puncture resistance of the sheets during and after the reflow process and additional mechanical integrity to element 9 upon thermal expansion. This applies to particular advantages in embodiments where the selected electrolyte tends to soften or otherwise weaken paper-only sheets during the high temperatures of the reflow process.

[0163] In other embodiments, sheets 13 and 14 are made from different materials or combinations of materials. Additionally, in one embodiment, sheets 13 and 14 are made from different materials or combinations of different materials. For example, in one embodiment, sheet 14, which extends circumferentially around the radially outer periphery of element 9, is thicker than sheet 13 to provide additional, uniformly applied mechanical strength to its outer periphery.

[0164] In one embodiment, sheets 13 and 14 are made primarily of PTFE. Typically, such sheets can be thinner than paper-based sheets and are relatively puncture resistant even when stretched during winding of element 9. Preferably, such sheets include a surface treatment to enhance wettability with the electrolyte.

[0165] In other embodiments, different thicknesses are used for the separator sheets. In an exemplary embodiment, the paper-based sheets have a thickness of 20 microns to 30 microns. In one embodiment, the sheets have a thickness of 30 microns to 40 microns. In one embodiment, the sheets have a thickness of 40 microns to 50 microns. In yet other embodiments, the sheets have different thicknesses.

[0166] In the above embodiment, sheets 13 and 14 are formed substantially from nonwoven cellulose fibers. However, in other embodiments, sheets 13 and 14 are formed substantially from other fibrous or non-fibrous materials. Examples of such materials include polytetrafluoroethylene (PTFE), polyacrylonitrile (PAN) fibers, aramid fibers, and glass fibers. These materials can be surface-treated to include one or more layers to provide additional or enhanced properties. For example, for embodiments using polytetrafluoroethylene sheets 13 and 14, the sheets are preferably surface-treated to reduce reactivity and improve wettability of the sheets with the electrolyte.

[0167] In this embodiment, the housing 3 is formed substantially entirely from an aluminum alloy, and the sidewall 25 has a substantially uniform wall thickness of approximately 300 microns. In other embodiments, wall thicknesses greater than 300 microns are used, including greater than 350 microns, greater than 370 microns, greater than 380 microns, greater than 390 microns, and greater than 400 microns. In further embodiments, wall thicknesses less than 300 microns are used, including less than 290 microns, less than 280 microns, less than 270 microns, less than 260 microns, and less than 250 microns. The wall thickness is selected to provide sufficient mechanical strength for the device 1, taking into account the expected internal pressures within the cavity 8 during the reflow process and the expected mechanical shocks that the device 1 must withstand during subsequent operation. Minimizing the amount of material required to construct the housing 3 is also considered. A further consideration in selecting the thickness of the sidewall is providing the necessary ability for the sidewall 25 to plastically deform to define both the sealing and retention structures of the sealing element. In one embodiment, the housing 3 and sidewall 25 are formed from stainless steel.

[0168] In the embodiment described above, side wall 25 of housing 3 extends axially 12.6 mm between ends 5 and 6 and has an outer diameter of 12.5 mm. Before undergoing the two forming operations, side wall 25 of housing 3 extends axially 13.5 mm between ends 5 and 6.

[0169] The sidewall 26 has a wall thickness of 370 microns. Additionally, the sidewall 26 includes one or more vent structures (not shown), which are integrally formed channels for preferentially rupturing when the internal pressure within the cavity 8 exceeds a predetermined threshold. In this embodiment, the vent structures are two perpendicular intersecting channels extending radially in the sidewall 26. These channels are configured to withstand pressures of 20 to 30 kgcm on that sidewall. -2, resulting in rupture of the sidewall 26. The reduced wall thickness of the sidewall 26 adjacent the channel is approximately 70 microns. In other embodiments, different vent configurations or different configurations of vent structures are used. Additionally, deeper or shallower channels are used if different burst pressures are desired.

[0170] In further embodiments, sidewalls 26 have varying sidewall thicknesses. Additionally, in additional embodiments, sidewalls 26 are not substantially planar, but instead include either a convex outwardly facing surface to provide additional structural strength to housing 3, or alternatively a concave outwardly facing surface to provide housing 3 with predetermined deformation characteristics when under load.

[0171] It will be appreciated that once device 1 is mounted to PCB 2, sides 25 and 26 are exposed to ambient atmospheric conditions both during the reflow process and during the subsequent operational life of device 1. Furthermore, thin sidewalls 25 and 26 provide, in embodiments, a resistance of 100 W / m at room temperature. -1 K -1 1. The device 1 is formed substantially exclusively from an aluminum alloy having a thermal conductivity greater than 1000 K. Thus, for a given reflow process, the internal components within cavity 8 (particularly capacitor element 9) will experience a higher maximum temperature than prior art EDLC devices having thermally insulating packaging and / or housings. Conversely, following the reflow process, device 1 will reach ambient temperature more quickly than prior art devices. With this in mind, the internal components of device 1 are selected not for continuous high-temperature performance, but in combination to adequately withstand a one-time thermal shock during the reflow process (whether involving a single pass through a reflow oven or multiple passes) while still providing a predetermined operating life at a maximum operating temperature much lower than the maximum temperature experienced during the reflow process. The thermal shock experienced by the internal components within device 1 during the reflow process may involve a higher maximum temperature than typically occurs in prior art SMD EDLC devices, but should remain at that maximum temperature for a shorter duration.

[0172] In one embodiment, the sidewall 25 has a resistance of 50 to 100 Wm at room temperature. -1 K -1 In one embodiment, the sidewall 25 is made of a material having a thermal conductivity of 100 to 150 Wm at room temperature. -1 K -1 In one embodiment, the sidewall 25 is made of a material having a thermal conductivity of 150 to 200 W / m at room temperature. -1 K -1 In one embodiment, the sidewall 25 is made of a material having a thermal conductivity of 200 to 250 Wm at room temperature. -1 K -1 The heat sink is formed from a material having a thermal conductivity of 0.1.

[0173] In other embodiments, different sized housings are used to complementarily accommodate electrodes of corresponding sizes.

[0174] Electrode 11 for device 1 extends 7 mm axially between edges 61 and 62, and electrode 12 also extends 7 mm axially between edges 65 and 66. Sheet 13 extends 8 mm axially between edges 69 and 70, and sheet 14 also extends 8 mm axially between edges 73 and 74. Electrodes 11 and 12 are axially centered with each other and with sheets 13 and 14. As described above, device 1 provides a capacitance of approximately 3.4 Farads and an equivalent series resistance (ESR) of approximately 83 mΩ. In other embodiments, different capacitance and ESR values ​​are obtained by using different electrode dimensions, different electrode materials (having different surface areas), different thicknesses of the electrodes and separator sheets, and different lengths of the electrodes and separator sheets. If the dimensions of electrodes 11 and 12 and sheets 13 and 14 are changed from those used in this embodiment, or if the number of turns of those components to form element 9 is changed from those used in this embodiment, it may be necessary to use a housing having different dimensions than housing 3.

[0175] The exterior of side walls 25 and 26 are pre-coated with a thin, cured layer of lacquer to provide an electrical insulating barrier. An additional pre-assembly step for this embodiment is the application of a 30 micron thick paper liner onto the interior surface of side wall 26. This is done to reduce the risk of unintended electrical contact between side wall 26 and electrodes 11 and 12 contained within element 9. In this embodiment, a paper sheet of the same material as sheet 13 is used.

[0176] In this embodiment, layers 81, 82, 85, and 86 are substantially identical and contain similar components. In particular, each layer contains a predetermined homogeneous mixture of high surface area activated carbon particles, highly conductive carbon black particles, and a binder. The binder contributes to the cohesion between the carbon particles within the same layer and to the adhesion of each carbon-based layer to the adjacent current collector.

[0177] The activated carbon particles in this embodiment are selected to have more than 50% of their pore volume with pore sizes greater than 2 nm to better mix with electrolytes that have higher viscosities than conventional electrolytes that use organic liquids such as acetonitrile. These activated carbon particles are referred to as mesoporous activated carbon particles. The use of such mesoporous carbon particles in this embodiment has been found to not only improve the electrical performance of EDLC devices with relatively viscous electrolytes, but also facilitate the fabrication of EDLC devices because the carbon particles are more easily wetted by the electrolyte, thereby contributing to greater predictability in the fabrication process.

[0178] It will be understood that the pore size of the carbon particles mentioned in the previous paragraph is different from the porosity of layers 81, 82, 85, and 86 themselves. More specifically, device 1 uses porous electrodes, each containing a mixture of active particles. The active particles in this embodiment are conductive particles in the form of porous activated carbon particles and carbon black particles. While all active materials contribute a high surface area between the electrode and the adjacent electrolyte, this is particularly true for the activated carbon particles. The electrolyte penetrates the porous electrode and the pores of the activated carbon particles. A Helmholtz double layer is formed not only by the outer carbon particles contained within the electrode, but also by the subsurface carbon particles within the electrode. The penetration or wetting of the electrode by the electrolyte contributes to the greater volumetric capacitance achieved by EDLC devices compared to conventional electrolytic capacitors. To achieve the highest capacitance in EDLC devices for a given volume, microporous activated carbon particles are typically used, as they offer the largest surface area per unit volume of particles. The inventors have discovered that for those embodiments using more viscous electrolytes, it may be advantageous for the electrodes to contain mesoporous activated carbon particles instead of, or in addition to, microporous carbon particles. These mesoporous carbon particles typically offer a smaller surface area per volume than microporous carbon particles, thus reducing the capacitance provided by the electrode. However, the larger pores of the mesoporous particles have been found to improve the performance of EDLC devices primarily by reducing the ionic resistance of the electrolyte and, consequently, contributing to a lower ESR of the device. This effect is particularly evident for electrolytes with higher viscosities.

[0179] Mesoporous particles are particles with a pore volume of more than 50% having a pore size greater than 2 μm. In the above embodiment, the mesoporous carbon particles are activated carbon particles; in other embodiments, other mesoporous materials are used. In an exemplary embodiment, the mesoporous carbon particles are contained within a carbon foam.

[0180] In one embodiment, the electrolyte has a viscosity at room temperature that is higher than the viscosity of water at room temperature. In one embodiment, the viscosity of the electrolyte at room temperature is more than twice the viscosity of water at room temperature. In one embodiment, the viscosity of the electrolyte at room temperature is more than three times the viscosity of water at room temperature. In one embodiment, the viscosity of the electrolyte at room temperature is more than four times the viscosity of water at room temperature. In one embodiment, the viscosity of the electrolyte at room temperature is 2 to 2.5 times the viscosity of water at room temperature, 2.5 to 3 times the viscosity of water at room temperature, 3 to 3.5 times the viscosity of water at room temperature, and 3.5 to 4 times the viscosity of water at room temperature, respectively. In one embodiment, the viscosity of the electrolyte at room temperature is less than 10 times the viscosity of water at room temperature.

[0181] The binder in this particular embodiment includes carboxymethyl cellulose (CMC). However, in other embodiments, other binders that do not significantly degrade at temperatures above 200°C are used. In one embodiment, the binder alternatively or additionally includes one or more of a salt of CMC (such as sodium carboxymethyl cellulose), polytetrafluoroethylene (PTFE), a salt of polystyrene sulfonic acid (PSS), such as a Group 1 or Group 2 metal salt of PSS, including magnesium polystyrene sulfonate (MgPSS), sodium polystyrene sulfonate (NaPSS), lithium polystyrene sulfonate (LiPSS), and calcium polystyrene sulfonate (CaPSS), polyvinylidene fluoride (PVDF), and a polyimide. These binders have been found to be relatively stable at high temperatures, such as those encountered in the reflow process. While such binders may soften during the reflow process, the use of a cylindrical, spirally wound element 9 operates to maintain a more uniform pressure across the surface of the electrode, thereby allowing the shape and configuration of layers 81, 82, 85, and 86 to be better maintained. In further embodiments, the binder is omitted for either adhesion and / or cohesion if the electrode's material selection is such that sufficient structural integrity can be achieved without the binder. For example, this may occur in some embodiments where the electrode includes a predetermined combination of carbon nanotubes and carbon particles. The use of a spirally wound element 9 has been found to be well-suited for the use of binderless electrodes, as potential structural weaknesses resulting from the omission of the binder are at least partially mitigated by the structural advantages provided by the structure of element 9. In other embodiments, a different binderless electrode is used. Additional binderless electrode examples for EDLC devices include vertically aligned carbon nanotubes grown directly on a current collector, entangled carbon nanotubes, and entangled carbon nanotubes with other high surface area carbon materials such as activated carbon particles or graphene materials.

[0182] The electrolyte in housing 3 is composed of a neutral organic compound, such as a polar aprotic solvent, including an organic sulfur sulfone compound such as sulfolane, and an organic salt, including a tetrafluoroborate salt of a quaternary ammonium cation, such as tetramethylammonium, tetraethylammonium, tetrapropylammonium, tetrabutylammonium, 2-(methylthio)ethylammonium, spirobispyrrolidinium (SBP), N,N-dimethylpyrrolidinium, N-methyl-N'-propylpyrrolidinium, N,N'-dimethylimidazolium, N-methyl-N'-ethylimidazolium, or N-methyl-N'-propylimidazolium. The salt is present in a sufficiently high concentration such that the freezing point of the electrolyte is depressed below 0°C at 1 atmosphere pressure.

[0183] In other embodiments, the neutral organic compound or solvent, such as a polar aprotic solvent, comprises a carbonate ester (such as propylene carbonate (PC)) or a cyclic lactone (such as gamma butyrolactone (GBL)). These neutral organic compounds / solvents are combined with an organic salt to enable ionic conduction in the electrolyte. Such an organic salt comprises tetrafluoroborate anion. In one embodiment, the salt is present at a sufficiently high concentration such that the boiling point of the resulting electrolyte is raised to 200° C. or greater at 1 atmosphere. In one embodiment, the salt is present at a sufficiently high concentration such that the boiling point of the resulting electrolyte is raised to 210° C. or greater at 1 atmosphere. In a further embodiment, the salt is present at a concentration such that the boiling point of the resulting electrolyte is raised to 220° C. or greater at 1 atmosphere. In an exemplary embodiment, the salt is present at a concentration such that the boiling point of the resulting electrolyte is raised to 230° C. or greater at 1 atmosphere. In a still further embodiment, the salt is present at a concentration such that the boiling point of the resulting electrolyte is raised to 240° C. or greater at 1 atmosphere.

[0184] In one embodiment, the electrolyte comprises a mixture of neutral organic compounds, such as a mixture of two or more different neutral organic solvents, such as two or more different polar aprotic solvents. In one embodiment, the electrolyte comprises two or more carbonate esters. In an exemplary embodiment, the electrolyte comprises a mixture of sulfones, such as a mixture of a linear sulfone and a cyclic sulfone. In another exemplary embodiment, the electrolyte comprises a mixture of two cyclic sulfones. In another exemplary embodiment, the electrolyte comprises a mixture of carbonate esters, such as a mixture of a linear carbonate ester and a cyclic carbonate ester. In another exemplary embodiment, the electrolyte comprises a mixture of cyclic carbonate esters.

[0185] In further embodiments, the electrolyte comprises an ionic liquid. In still further embodiments, the electrolyte comprises a combination of an ionic liquid and a neutral organic compound or solvent. Exemplary neutral organic compounds or solvents include one or a combination of at least two of sulfolane, PC, and GBL.

[0186] The selection of electrolyte for this embodiment is based on the following properties: (a) a boiling point of 200°C or higher at 1 atmosphere to reduce the pressure buildup inside the housing during the reflow process; (b) relatively high ion mobility for the operating temperature range selected for Device 1; (c) good temperature stability during the thermal shock experienced during the reflow process; (d) low reactivity with the selected electrodes throughout the operating temperature range and during the thermal shock experienced during the reflow process, taking into particular consideration the potential reactivity of the electrolyte with the carbon-based layers, more specifically with the binder contained within those layers, or any impurities typically found in the carbon particles; (e) low reactivity with the selected separator throughout the operating temperature range and during the thermal shock experienced during the reflow process; (f) low permeability resulting from electrolyte vapor permeation through lid 15 throughout the required operating temperature range and during the thermal shock experienced during the reflow process; and (g) low leakage from cavity 8 by progressing along the sealing path throughout the required operating temperature range and during the thermal shock experienced during the reflow process; The studies were based on a combination of factors such as electrolytes with one or more of:

[0187] For SMD EDLC devices of the above embodiments that undergo a reflow process, it has been found preferable to select an electrolyte that is liquid at least between 0°C and 200°C at 1 atmosphere pressure. It will be understood that in some embodiments, the electrolyte may include an organic solvent and / or an organic salt that has a defined freezing point greater than 0°C. This occurs when such organic solvent and / or organic salt has a substantially in situ suppressed freezing point. For example, in one embodiment, the in situ freezing point of the electrolyte is suppressed below 0°C by either or both of the concentration of dissolved organic salts or the high surface area of ​​activated carbon.

[0188] In preferred embodiments, the binder does not substantially dissolve when mixed in a sample of electrolyte heated to 200° C. at 1 atmosphere pressure. In some embodiments, electrodes 11 and 12 do not include a binder, which can allow a wider range of electrolytes to be used in SMD EDLC devices because reactivity between the binder and electrolyte at the high temperatures encountered during the reflow process does not have to be considered.

[0189] As will be understood by those skilled in the art, the electrolyte provides an SMD EDLC device with a source of charged ions that migrate to the surfaces of each electrode to form a pair of Helmholtz layers within the device. Furthermore, it will be appreciated that as a result of the use of a highly thermally conductive housing for an SMD EDLC device, as occurs in the embodiments described herein, the electrolyte and other internal components of the EDLC device will reach maximum temperatures of approximately 200°C to 240°C during the reflow process, even if only briefly. Therefore, the electrolyte for device 1 is selected to withstand this temperature profile while still providing the necessary lifetime performance. Some embodiments are designed for a reflow process that results in the electrolyte being exposed to maximum temperatures greater than 240°C.

[0190] Note that Device 1 is a single cell device. The voltage that can be maintained across this single cell during normal use over its planned lifetime is called the cell voltage. Thus, the rated voltage of Device 1, being a single cell device, is the same as the cell voltage of Device 1. The electrolyte used in Device 1 and other embodiments described herein is an organic electrolyte that allows for cell voltages greater than 2 volts.

[0191] In another embodiment, (a) typically in parallel to reduce the overall ESR of the resulting device or to increase the overall capacitance of the resulting device compared to a single cell device; and / or (b) Typically in series to increase the operating voltage of the resulting device compared to a single cell device. A number of such cells connected together are used.

[0192] Those skilled in the art will appreciate that EDLC devices using aqueous electrolytes have cell voltages of less than 2 volts. In contrast, EDLC devices of embodiments using organic electrolytes typically provide cell voltages in the range of 2.3 to 4 volts. Because those devices with higher cell voltages often experience accelerated degradation characteristics, the maximum operating voltage of an SMD EDLC device is often determined by the required performance of the device for a given operating life and operating conditions.

[0193] The electrolytes used in the embodiments described herein are selected, in part, so as not to create excessive pressure within the housing 3 when the device 1 is exposed to the temperatures of a reflow oven. This reduces the risk of overstressing and weakening the seals during the reflow process, as well as the risk of the electrolyte leaking from the housing due to rupture and failure of the housing. The electrolyte in one embodiment is selected to have a vapor pressure of less than 1 atmosphere (1.013 bar or 101.3 Kpa) at 200°C. In other embodiments, each electrolyte has a vapor pressure of less than 1 atmosphere at 210°C, 220°C, 230°C, 240°C, 250°C, and 260°C.

[0194] The electrolyte in one embodiment is also selected to be chemically stable to the reflow oven temperatures experienced by the device, and is further selected so that it does not substantially dissolve, degrade, or become incorporated into other components of the EDLC device, such as the binder, separator, current collectors, any carbon used in the electrodes, the housing, and the lid (or other sealing element), at the relevant reflow oven temperatures.

[0195] In assessing whether the electrolyte does not substantially dissolve, degrade, or become incorporated into other components of the EDLC device, in one embodiment, electrical testing performed before and after the device is subjected to the reflow process is taken into consideration.

[0196] As will be understood by those skilled in the art, a change in ESR is typically an increase and a change in capacitance is typically a decrease. For some devices, following a reflow process, the ESR decreases and / or the capacitance increases.

[0197] In one embodiment, the electrolyte includes an organic salt or a mixture of two or more organic salts that is liquid at room temperature. Such organic salts are commonly referred to as ionic liquids. Alternatively, or additionally, the electrolyte includes an organic salt that is a solid salt alone at room temperature mixed with a neutral organic compound or solvent. This mixture partially or entirely provides an electrolyte that is an ionically conductive liquid in the temperature range required for the reflow process used to connect the SMD EDLC device to PCB 2 and the operating temperature range of the assembled SMD EDLC device. The neutral organic compound or solvent used in one embodiment can be a liquid solid. However, if an organic solid is utilized, the organic solid is preferably heated and mixed with an organic salt, organic liquid, or liquid organic salt (ionic liquid) to form a eutectic-type mixture whose melting point is much lower than that of the organic solid or organic salt / organic liquid. In some embodiments, an organic liquid can be added, and in further embodiments, an organic salt can be added to form a eutectic-type mixture. The eutectic-type mixture of the embodiments results in a liquid electrolyte at room temperature, and typically even at lower temperatures. In one embodiment, the eutectic mixture has a freezing point of less than 0° C. In one embodiment, the eutectic mixture has a freezing point of less than −10° C. In one embodiment, the eutectic mixture has a freezing point of less than −20° C.

[0198] The organic salt comprises a cation and an anion. In embodiments in which the salt is liquid at room temperature, i.e., in embodiments in which the salt is an ionic liquid, the salt can be used without mixing with a neutral organic compound or solvent, but can also be mixed. If the organic salt is solid at room temperature, it is mixed with a neutral organic compound or solvent, such as a polar aprotic solvent, that is either solid or liquid at room temperature. The organic compound or solvent allows or promotes dissociation of the salt's ions.

[0199] In one embodiment, the ionic liquid comprises a mixture of two or more salts, ie, two or more different ionic liquids may be mixed or combined.

[0200] As mentioned above, the salt component of the electrolyte is composed of cations and anions. For organic electrolytes in EDLC devices, it is preferable that only weak interactions exist between the anions and cations so that the salt readily dissociates into the cations and anions. For one embodiment, the selection of the salt also takes into account that the salt is sufficiently stable at the cell voltage required for the EDLC device, over the reflow oven temperature profile to which the EDLC device will be subjected, and over the planned operating life of the device at a given maximum operating temperature.

[0201] Exemplary cations that have been found to be sufficiently stable for use in the embodiments are quaternary ammonium salts. More specifically, such exemplary cations have the following chemical structures:

[0202] [ka]

[0203] In the formula, R 1 , R 2 , R 3 , and R 4 is an alkyl substituent. In one embodiment, R 1 , R 2 , R 3 , and R4 are each independently a linear or branched C1 to C7 alkyl group. 1 , R 2 , R 3 , and R 4 are each independently a linear or branched C1-C4 alkyl group. 1 , R 2 , R 3 , and R 4 are each independently a linear or branched C1-C2 alkyl group, and such salts can be dissolved in an organic solvent at the time of use. 1 is R 2 , R 3 , and R 4 In one embodiment, R 1 , R 2 , R 3 , and R 4 are different from each other.

[0204] In other embodiments, the quaternary ammonium cation comprises a disubstituted pyrrolidinium having the following chemical structure:

[0205] [ka]

[0206] In the formula, R 5 and R 6 are each alkyl substituents. In one embodiment, R 5 and R 6 are each independently a linear or branched C1 to C7 alkyl group. In one embodiment, R5 is different from R6.

[0207] In a further embodiment, the quaternary ammonium cation is a spiro bicyclic compound in which the common atom in the spiro structure is nitrogen. Exemplary chemical structures of such cations are as follows:

[0208] [ka]

[0209] This structure represents a spirobispyrrolidinium cation (SBP) in which two five-membered rings are connected through a common nitrogen atom. In other embodiments, a similar spiro configuration cation is used, but with one five-membered ring attached to a six-membered ring. In additional embodiments, two six-membered rings are connected in a spiro configuration through a common nitrogen.

[0210] In a further embodiment, the cation comprises a heterocyclic nitrogen-containing cation. An example of the chemical structure of such a cation is as follows:

[0211] [ka]

[0212] This structure has substituents R at both nitrogen atoms in the heterocycle. 7 and R 8 In various embodiments, R 7 and R 8 are each independently a linear or branched C1 to C7 alkyl group.

[0213] In one embodiment, the anion is a borate and / or phosphate ion, more specifically, a tetrafluoroborate (TFB) and / or a hexafluorophosphate (HFP) ion. Other embodiments utilized alternative and / or additional anions from different borate compounds, such as tetracyanoborate, fluorotricyanoborate, difluorodisyanoborate, trifluorocyanoborate, bis(oxalato)borate, and difluoro(oxalato)borate.

[0214] In further embodiments, the anion is a sulfonylimide, more specifically one or more of bis(fluorosulfonyl)imide (FSI) and bis(trifluoromethylsulfonyl)imide (TFSI).

[0215] It will be understood that TFSI and EMI-TFB form an electrolyte that is an ionic liquid. Those embodiments utilizing such ionic liquids need not include an organic solvent. However, in other embodiments, the ionic liquid is combined with one or more organic solvents to improve the conductivity and other selected properties of the resulting electrolyte.

[0216] Further embodiments utilize alternative or additional organic salts, such as SBP-TFB and / or SBP-TFSI, which are solids alone at room temperature and, in some embodiments, are premixed with one or more organic solvents in either solid or liquid form to provide the requisite liquid electrolyte.

[0217] For those embodiments utilizing one or more neutral organic compounds / solvents in either liquid and / or solid form, the selection of the compound / solvent should take into account the temperature profile of the reflow process and the maximum expected temperature to which the electrolyte will be exposed. In practice, related embodiments utilize neutral organic compounds / solvents with relatively high boiling points. Given the benefit of the teachings herein, it will be understood that the boiling point of the neutral organic compound need not necessarily exceed 250°C, or even 200°C. Rather, the inventors have discovered that the more important factor is that the final electrolyte have a sufficiently high boiling point, measured at 1 atmosphere. For example, in some embodiments, electrolytes with very high cation and anion concentrations are utilized to provide a significant reduction in the electrolyte's vapor pressure compared to lower concentration mixtures. This provides a significant increase in the temperature at which the electrolyte's vapor pressure reaches 1 atmosphere.

[0218] In some embodiments, organic solvents, such as polar aprotic solvents with high dielectric constants, are preferred to facilitate dissolution and / or mixing of the salt during use and maximize dissociation of the salt. In preferred embodiments, the solvent is a polar aprotic solvent.

[0219] Exemplary embodiments utilize a neutral organic compound or solvent comprising one or more linear or cyclic carbonate esters. In one embodiment, the neutral organic compound comprises one or more linear carbonate esters. For example, in one embodiment, the linear carbonate ester is diethyl carbonate.

[0220] In one embodiment, the neutral organic compound comprises one or more cyclic carbonates, which are high-boiling, highly dielectric liquids, including, by way of example, carbonates having the following chemical structures:

[0221] [ka]

[0222] Five-membered ring carbonates have R which is H, a methyl group, a fluorinated methyl, or F. 9 In other embodiments, the neutral organic compounds include those in which there is further fluorine substitution on a carbon atom of the cyclic structure, i.e., the cyclic carbonate contains at least one C—F bond.

[0223] In further embodiments, the neutral organic compound is a lactone. For example, in some embodiments, the neutral organic compound is a liquid such as gamma butyrolactone (GBL), which has the following chemical structure:

[0224] [ka]

[0225] It should be noted that GBL has a lower viscosity than many carbonate ester liquids and may be selected for embodiments where the SMD EDLC device requires higher ionic conductivity for the electrolyte.

[0226] In a still further embodiment, the neutral organic compound comprises a linear or cyclic sulfone having a relatively high boiling point. By way of example, the following chemical structure of a linear sulfone is provided:

[0227] [ka]

[0228] Substituent R 10 and R 11 are each independently a C1-C4 alkyl group. 10 and R 11 are the same alkyl groups, but in other embodiments, R 10 and R 11 are different alkyl groups. In an exemplary embodiment, R 10 and R 11 are both ethyl groups, and the organic liquid is diethyl sulfone (DES).

[0229] By way of further example, in additional embodiments, the neutral organic compound comprises a cyclic sulfone, such as having the following chemical structure:

[0230] [ka]

[0231] In this structure, R 12 is either H (if the neutral organic compound is a sulfone) or a methyl group (if the neutral organic compound is 3-methylsulfolane).

[0232] The neutral organic compounds described above have been found to be applicable to SMD EDLC device embodiments because they have relatively high boiling points and are generally very stable electrochemically.

[0233] In other embodiments, the neutral organic compounds include one or more nitrile or dinitrile liquids or organic solids having high boiling points and relatively high dielectric constants. By way of example, these include compounds having the following chemical structures:

[0234] [ka]

[0235] Some embodiments utilize an electrolyte comprising a single organic salt, while in other embodiments the electrolyte comprises a mixture of two or more organic salts. Similarly, some embodiments utilize an electrolyte comprising a single neutral organic compound / solvent, while in other embodiments the electrolyte comprises a mixture of two or more neutral organic compounds / solvents.

[0236] In exemplary embodiments, the weight percent of salt in the electrolyte is between 10% and 100%. The upper end of this range is primarily directed to embodiments that use an organic salt that is an ionic liquid and no additional organic liquid solvent is used in combination with the ionic liquid. For other embodiments, the weight percent of salt in the electrolyte is between 20% and 100%. For further embodiments, the weight percent of salt in the electrolyte is between 30% and 100%, between 40% and 100%, or between 50% and 100%.

[0237] Due to the relatively small size of SMD EDLC devices and significant design constraints regarding device footprint and overall volume, it becomes increasingly important to optimize the volume and configuration of components used in the device to provide the necessary electrical characteristics. For example, enabling the use of thin-walled housings contributes to the resulting EDLC device having more available volume for components that directly contribute to higher capacitance and / or lower ESR. By avoiding the prior art's need for large housings to provide thermal protection, embodiments can provide good electrical characteristics per unit volume and can be manufactured using less costly materials and less complex manufacturing steps.

[0238] The axial thickness of lid 15 is 3 mm, which has been found to provide sufficient seal length for the selected electrolyte in the context of the reflow process, sufficient thickness to limit electrolyte vapor transmission through the lid, and sufficient resistance to compressive seal failure due to gas buildup within the cavity during the reflow process and over the normal operating life of the device. In other embodiments, one or more of axially thinner or axially thicker lids, structurally reinforced lids, and lids constructed from different materials are utilized to provide additional safety factors and better accommodate other electrolyte / separator / electrode combinations. For example, in certain other embodiments, lid 15 utilizes an alternative synthetic rubber, such as ethylene propylene diene monomer (EPDM) rubber. In yet further embodiments, lid 15 is a composite lid, comprising two or more materials. For example, in one embodiment, lid 15 comprises a central portion of hard, electrically insulating plastic with openings 33 and 34 formed therein and a continuous radially outer circumferential portion of synthetic rubber. In another embodiment, the lid 15 includes a rubber-covered reinforcing element so that its center further resists axially outward deformation due to gas pressure built up within the cavity 8 during the reflow process and over the operating life of the device.

[0239] Because device 1 includes a compression seal, lid 15 can include other deformable and compressible materials to affect the seal. Materials, like the other materials described above, are also selected based on their ability to withstand the temperatures of the reflow oven and their sufficient inertness, particularly with respect to the electrolyte, so as not to substantially affect the operational life of the device.

[0240] In some embodiments, lid 15 includes an internal or external barrier element to prevent the flow of electrolyte vapor through lid 15. In one such embodiment, the barrier element is a PTFE layer applied to either or both of surfaces 29 and 30. In another such embodiment, the barrier element is a dopant in rubber or a dopant in a layer of rubber. In a further such embodiment, the barrier element is separate from but adjacent to lid 15.

[0241] In selecting a material for lid 15, consideration is given not only to the expected thickness to provide the necessary barrier and sealing properties, but also to components in the material that may interact with the electrolyte or other components of device 1. In selecting any dopants or additives for the rubber, particular consideration is given to the fact that the dopants or additives are inert, or at least sufficiently inert, when exposed to the electrolyte over the intended temperature range and lifetime of the device.

[0242] It will be appreciated by those skilled in the art that the thin-walled aluminum housing 3 provides very little heat capacity and thermal protection for the device 1, and that the compression seal at the opening 7 is typically not a hermetic seal. Accordingly, the electrolyte and other components used within the device 1 are selected to ensure a combination of both that the EDLC device will adequately withstand the reflow process despite the high thermal conductivity of the housing 3, and that the rate of electrolyte loss from the cavity 8 through the compression seal is sufficiently low. Once the selection is made, the use of the thin-walled aluminum housing 3 and compression seal advantageously: (a) reduced manufacturing complexity and cost relative to known manufacturing techniques for SMD EDLC devices; (b) a reduction in the volume occupied by materials relative to known SMD EDLCs whose primary purpose is to provide thermal capacity or thermal protection; (c) for a given footprint / volume on PCB2, more volume is available for internal components within Device 1 that contribute to higher capacitance and / or lower ESR; and (d) reducing the use of expensive materials whose primary purpose is to provide thermal mass or thermal protection; It is advantageous to be able to contribute to one or more of them.

[0243] Given the benefit of this disclosure, it will be understood that device 1 is relatively small in volume and mass, and that housing 3 provides little or no thermal shielding to element 9 and the electrolyte. Accordingly, a design assumption of device 1 is that during the reflow process, all of its components are exposed to nearly the full range of reflow oven temperatures with little delay. Conversely, upon removal from the reflow oven, device 1 returns to ambient temperature relatively quickly. These design assumptions allow embodiments to use thin-walled housings with high thermal conductivity, unlike those used in conventional SMD EDLC devices. This simplifies the manufacture of embodiments, reduces the need for bulky and expensive packaging, and makes the design suitable for mass production.

[0244] Device 1, designed for use in a reflow process, has an operating temperature range of −20° C. to 70° C. In other embodiments, the operating temperature range is −20° C. to 80° C., and in further embodiments, the operating temperature range is −10° C. to 70° C. In still further embodiments, the operating temperature range is −40° C. to 70° C., or −20° C. to 85° C. In either case, device 1 is designed for mass production and use, and the operating temperature range is much lower than the temperatures experienced during the reflow process, with an upper limit that must be tolerated by a device directly applicable to extreme environments. For its planned operating life, device 1 is expected to undergo a single reflow process but otherwise remain within its designed operating temperature range. While device 1 can withstand exposure to several separate reflow processes, such exposure may affect the device's lifetime.

[0245] It will be appreciated that a single reflow process may include one pass through a reflow oven or multiple passes through a reflow oven, where multiple passes are used this typically includes two passes.

[0246] Reference is now made to Figures 12 through 17, which illustrate a sequence of steps in the assembly / manufacturing of a second exemplary SMD EDLC device 91. In these figures, features corresponding to features of device 1 are indicated by corresponding reference numerals. This does not mean that corresponding features in device 91 are identical in size, shape, material, or performance to those in device 1, although they may be. Rather, the correspondence is in the general function of the identically labeled features.

[0247] Turning to FIG. 12, a unitarily formed, thin-walled aluminum alloy housing 3 is presented to a processing station and maintained in a fixed configuration by a station fixture (not shown). The sidewall 25 of the housing 3 is substantially uniformly cylindrical along the axis 4. FIG. 13 shows the assembled combination of the element 9 and lid 15 loaded into an automated assembly fixture (not shown) and presented to the processing station axially aligned with the housing 3. Additionally, the edge 74 is positioned adjacent the end 5 and the opening 7. In this embodiment, the element 9 has a maximum outer diameter that is approximately 0.9 mm less than the inner diameter of the cavity 8. This allows for ease of automated insertion of the element 9 into the housing 3 and space for radial thermal expansion of the element 9 within the cavity 8 during the subsequent reflow process.

[0248] When referring to element 9 being complementarily received within cavity 8, this is primarily intended to indicate that the outer curved surface of element 9 is generally complementary to the opposing inner surface of adjacent side wall 25. The outer diameter of element 9 is less than the inner diameter of side wall 25 to allow insertion of element 9 into cavity 8. Preferably, the difference between the two diameters is small. As will be understood, given the benefit of the teachings herein, the axial dimensions of side wall 25 and element 9 will differ significantly to accommodate the first and second forming operations and the incorporation of lid 15.

[0249] Due to the complementary fit of element 9 within cavity 8 and the use of a thin wall thickness, the difference between the outer diameter of element 9 and the outer diameter of sidewall 25 is 1.5 mm. In one embodiment, the difference between the outer diameter of element 9 and the outer diameter of sidewall 25 is between 1.4 mm and 1.5 mm. In one embodiment, the difference between the outer diameter of element 9 and the outer diameter of sidewall 25 is between 1.3 mm and 1.4 mm. In one embodiment, the difference between the outer diameter of element 9 and the outer diameter of sidewall 25 is between 1.5 mm and 1.6 mm. In one embodiment, the difference between the outer diameter of element 9 and the outer diameter of sidewall 25 is between 1.6 mm and 1.7 mm.

[0250] Following automatic insertion, the resulting assembly appears as shown in FIG. 14. Similar to device 1, device 91 includes a thin paper liner adhered to the inner surface of sidewall 26. In the configuration shown in FIG. 14, edges 70 and 74 of respective sheets 13 and 14 are adjacent to or abut the paper liner. Additionally, edges 70 and 74 are deformed radially inward toward axis 4, providing full overlap of edges 62 and 66 by sheets 13 and 14, respectively. This full overlap, combined with the incorporation of the paper liner within cavity 8, reduces the risk of an unintended short circuit occurring between either of electrodes 11 and 12 and conductive sidewall 26.

[0251] In other embodiments, the difference between the diameter of element 9 and the inner diameter of cavity 8 is less than 0.9 mm, and automatic insertion of element 9 into cavity 8 occurs with greater mechanical precision than required in the manufacture of device 91.

[0252] In this embodiment, lid 15 has a diameter that approximates the inner diameter of cavity 8. During advancement of the assembled combination of element 9 and lid 15 into cavity 8, it is likely that at least a portion of the radial periphery of surface 29 will engage end 5. If such engagement occurs, the material properties of lid 15 will cause the lid to elastically deform, continuing advancement of the lid into cavity 8 and the configuration shown in FIG.

[0253] The automated assembly fixture then releases the combination of element 9 and lid 15 and retracts it from the processing station. Following this, a first forming tool (not shown) is advanced into the processing station to perform a first forming operation to form channel 27. The resulting assembled combination is shown in FIG. 15. In this embodiment, the station fixture rotates housing 3 and the contents of cavity 8 about axis 4, while the first forming tool moves radially, progressively engaging the outer surface of sidewall 25. In other embodiments, the station fixture moves radially and rotationally about axis 4, while the first forming tool remains stationary. In further embodiments, other options are used to affect the necessary relative movement between the station fixture and the first forming tool to form channel 27.

[0254] The first forming tool is then retracted from the processing station and a second forming tool (not shown) is advanced into the processing station. The second forming tool is incrementally advanced to roll over end 5 to define flange 28, the results of which are shown in FIGS. 16 and 17. In this embodiment, the station fixture rotates housing 3 and the contents of cavity 8 about axis 4, while the second forming tool moves radially to incrementally engage the outer surface of sidewall 25 adjacent end 5. In other embodiments, the station fixture moves radially and rotationally about axis 4, while the second forming tool remains stationary. In further embodiments, other options are used to affect the necessary relative movement between the station fixture and the second forming tool to form flange 28.

[0255] Referring now more specifically to FIG. 17 , the shape, configuration, and arrangement of channel 27 and the compression seal provided by lid 15 are shown in greater detail. More specifically, channel 27 defines, on the inner surface of sidewall 25, a convex protrusion 92 extending radially inward into cavity 8 and continuously circumferentially around housing 3 in a plane perpendicular to axis 4. Protrusion 92 includes a first shoulder 93 and a second shoulder 94, which define a first internal sealing surface 95 for housing 3. Housing 3 includes a substantially cylindrical engagement portion 96 extending axially between shoulder 94 and the radially outer end of flange 28 to define a second internal sealing surface 97 for housing 3. Flange 28 defines a third internal sealing surface 98 and an adjacent fourth internal sealing surface 99 for housing 3.

[0256] In use, as shown in Figure 17, the projection 92 extends radially inward into the cavity 8 and is disposed between the element 9 and the lid 15. In Figure 17, the axial spacing between the element 9 and the lid 15 is exaggerated to clearly show other features. The shoulder 93 limits any post-manufacture axial play of the element 9 within the cavity 8.

[0257] During formation of flange 28, the radial periphery of lid 15 is clamped and elastically deformed to conform to surfaces 95, 97, 98, and 99. This action (a) between sealing surface 95 and the radially outer periphery of surface 29 and a portion of surface 31; (b) between sealing surface 97 and a further portion of surface 31; (c) between sealing surface 98 and the radially outer periphery of face 30; and (d) Between sealing surface 99 and a further portion of surface 30 , creating a continuous compression seal.

[0258] The length of the seal path provided by the above combination is greater than the axial distance between surfaces 29 and 30 .

[0259] The formation of flange 28 also has the effect of reducing the diameter of openings 33 and 34 when lid 15 is compressed about its radial periphery, thus improving the sealing engagement and interference fit between lid 15 and terminals 11 and 12. This interference fit facilitates lid 15 resisting axial deflection even when pressure subsequently builds within cavity 8 during normal operation due to gas generation within device 1.

[0260] In some embodiments, the ferrules 41 of terminals 11 and 12 are pre-coated with a sealing compound to further enhance the sealing engagement and interference fit with lid 15 .

[0261] 19 provides details of 52 exemplary embodiments (examples). These examples each include a manually wound capacitor element and the same housing used for device 1 described above. Common features of the examples include:

[0262] [Table 1]

[0263] The carbon-based layers each have a thickness of 50 μm, except for Examples 38 to 43, which had slight variations in thickness along the electrode, and Examples 44 to 52, which had a carbon-based layer with a thickness of 70 μm.

[0264] 19, the term "CMC" refers to carboxymethyl cellulose sodium salt, the term "PSS70k" refers to polystyrene sulfonate sodium salt (MW=70,000 amu), and the term "PVDF / PSS" refers to a mixture of PVDF and PSS having weight percent solids of 67% and 33%, respectively. For the PVDF / PSS binder, an exemplary form of PSS is polystyrene sulfonate sodium salt (MW=70,000 amu), and an exemplary commercially available form of PVDF is that supplied by Solvay Specialty Polymers under the product name Solef® 2042 Latex.

[0265] For Examples 1 to 23, 26, 27, 29 to 34, and 37 to 43, the mixture of activated carbon, carbon black, and binder was 100 parts by weight of activated carbon, 40 parts by weight of carbon black, and 15 parts by weight of binder. For Examples 24, 25, 28, 35, and 36, the mixture of activated carbon, carbon black, and binder was 100 parts by weight of activated carbon, 40 parts by weight of carbon black, and 20 parts by weight of binder. For Examples 44 to 52, the mixture of activated carbon, carbon black, and binder was 100 parts by weight of activated carbon, 30 parts by weight of carbon black, and 15 parts by weight of binder.

[0266] The electrolytes used in the examples are further described in the table below.

[0267] [Table 2]

[0268] The manual assembly of the examples is expected to contribute to greater performance variability than would ultimately be achieved in automated manufacturing of such EDLC devices.

[0269] The examples were individually tested as follows. First, the initial or pre-reflow ESR (referred to as ESR1) and DC capacitance of the device were measured at room temperature and pressure before the device underwent a reflow simulation. A thermocouple was then placed against the outer cylindrical sidewall of the housing, approximately midway axially, and held in place with a short strip of adhesive Kapton® tape. Temperature measurements provided by the thermocouple during the simulated reflow process were used to measure the device's housing temperature (T H ) The high thermal conductivity of the housing allows H It will be appreciated that the temperature is not very sensitive to slight variations in the position of the thermocouple on the sidewall. The device was placed as a single component on a PCB, with the device terminals extending parallel to and resting on their respective pads on the PCB. Both the PCB and device were placed in a test oven. The test oven was controlled to expose the device and PCB to an oven thermal profile that simulated the thermal profile of a typical reflow oven. This oven thermal profile resulted in a predetermined thermal profile of the housing temperature, the latter of which is shown schematically in Figure 20. For each thermal profile, a temperature threshold (T T ) and T H Temperature duration (t D ) is specified. For example, T T is selected to be either 180°C or 217°C, which represent the two temperatures associated with the liquidus state of two common solder types, respectively. Additionally, T is selected during the reflow process to best ensure that the solder forms the necessary physical and electrical connections between the device terminals and the respective pads on the PCB. H T T t represents the time that exceeds D was set to about 25 to 40 seconds. Also provided in Figure 19 are measurements taken of the maximum housing temperature for each exemplary device during the simulated reflow process.

[0270] Following the simulated reflow process, the devices were cooled and post-test ESR measurements were taken at room temperature and pressure to provide a second or post-reflow ESR (referred to as ESR2) and, for most examples, the DC capacitance of the device. The ESR1, ESR2, and pre- and post-DC capacitance measurements taken for each exemplary device are shown in FIG. 19 along with the corresponding percentage changes in values.

[0271] The PCB is coated with a heat-absorbing material to help heat the solder paste pre-applied on the pads, so during the simulation, the temperature on the surface of the PCB is usually T H It will be understood that T H lags behind the furnace temperature and experiences a maximum temperature that is lower than the furnace maximum temperature during the normal duration of a given thermal profile.

[0272] From Figure 19, except for Example 9, T H After following a prescribed thermal profile, ESR2 ≥ ESR1, and

[0273]

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[0274] You will notice that it is.

[0275] From Figure 19, the following conditions are observed:

[0276]

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[0280]

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[0289] It will also be noted that there is at least one example showing that each of the following is satisfied:

[0290] From Figure 19, T T = 180°C and under the following conditions:

[0291]

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[0298] It will also be noted that there is at least one example showing that each of the following is satisfied:

[0299] It will also be noted from FIG. 19 that the examples have voltage ratings of 2 to 4 volts.

[0300] The example of Figure 19 uses an electrolyte based on an organic liquid, i.e., a non-aqueous liquid, to reduce environmental concerns that may be associated with aqueous electrolytes. However, one embodiment includes a device that includes an aqueous electrolyte.

[0301] Further details regarding exemplary methods of fabricating device embodiments are provided below.

[0302] According to one embodiment, there is provided an electric double layer capacitor (EDLC) device for reflow soldering to a PCB 2 having a PCB surface 2a with two electrical pads 56, the device comprising: a base 51 having a first surface 51a facing the surface 2a and a second surface 51b opposite to the surface 51a; a housing 3 for defining an opening 7 facing the face 51b in use and a cavity 8 extending from the opening 7; a substantially cylindrical capacitor element 9 housed within the cavity 8, the element 9 comprising: two carbon-based electrodes 11 and 12, each electrode comprising carbon particles; and a porous separator in the form of two separator sheets 13 and 14 spirally wound with the electrodes 11 and 12, the sheets 13 and 14 maintaining the electrodes in a spaced apart, opposing arrangement and comprising one or more of polytetrafluoroethylene, cellulose fibres, polyacrylonitrile fibres, aramid fibres and glass fibres; a capacitor element 9; an electrolyte in cavity 8 for enabling ionic conduction between electrodes 11 and 12, the electrolyte having a freezing point of 0°C or less and a boiling point of 200°C or more at 1 atmosphere pressure; a sealing element in the form of a lid 15 for providing a compression seal to seal the opening 7; two terminals 17 and 18 each extending between a first end 19 located within the cavity 8 and a second end 20 located outside the cavity 8, the ends 19 being electrically connected to respective electrodes 11 and 12, the terminals 17 and 18 extending through the opening 7 and the base 51 such that, in use, the ends 20 are substantially parallel to the face 2 a and electrically connected to respective pads 56; Includes:

[0303] According to one embodiment of the present invention, there is provided an SMD EDLC device for reflow soldering to a PCB2, the SMD EDLC device comprising: a housing (3) for defining an opening (7) and a cavity (8) extending from the opening (7); a capacitor element 9 housed within the cavity 8, the element 9 including two carbon-based electrodes 11 and 12 and a separator formed from two separator sheets 13 and 14 that maintain the electrodes 11 and 12 in a spaced apart, opposing arrangement; an electrolyte in cavity 8 for enabling ionic conduction between electrodes 11 and 12, the electrolyte having a freezing point of 0°C or less and a boiling point of 200°C or more at 1 atmosphere pressure; a sealing element in the form of a lid 15 for providing a compression seal to seal the opening 7; two terminals 17 and 18 each extending between a first end 19 disposed within the cavity 8 and a second end 20 disposed outside the cavity 8, the ends 19 being electrically connected to the respective electrodes 11 and 12, the terminals 17 and 18 extending through the opening 7 such that the ends 20 are available for electrical connection to the PCB 2; Includes:

[0304] In other embodiments, the electrolyte has a boiling point at 1 atmosphere of 210° C. or greater, 220° C. or greater, 230° C. or greater, 240° C. or greater, 250° C. or greater, or 260° C. or greater. In further embodiments, the electrolyte has a freezing point at 1 atmosphere of 10° C. or less, 20° C. or less, 30° C. or less, or 40° C. or less.

[0305] According to one embodiment of the present invention, there is provided an SMD EDLC device for reflow soldering to a PCB2, the SMD EDLC device comprising: a malleable housing 3 for defining an opening 7 and a cavity 8 extending from the opening 7; a capacitor element 9 housed within the cavity 8, the element 9 comprising two carbon-based electrodes 11 and 12 and a separator in the form of two separator sheets 13 and 14 spirally wound together with the electrodes 11 and 12, the sheets 13 and 14 maintaining the electrodes 11 and 12 in a spaced apart, facing arrangement; an electrolyte in cavity 8 to allow ionic conduction between electrodes 11 and 12; a sealing element in the form of a lid 15 for sealing the opening 7; two terminals 17 and 18 each extending between a respective first end 19 located within the cavity 8 and a respective second end 20 located outside the cavity 8, the ends 19 being electrically connected to the respective electrodes 11 and 12, the terminals 17 and 18 extending through the opening 7 such that the ends 20 are available for electrical connection to the PCB 2; Includes:

[0306] According to one embodiment of the present invention, there is provided an SMD EDLC device for reflow soldering to a PCB2, the device comprising: a housing 3 having high thermal conductivity for defining an opening 7 and a cavity 8 extending from the opening 7; a capacitor element 9 housed within the cavity 8, the element 9 including two carbon-based electrodes 11 and 12 and a separator formed from two separator sheets 13 and 14 spirally wound together with the electrodes 11 and 12, the separator sheets 13 and 14 maintaining the electrodes 11 and 12 in a spaced apart, facing arrangement; an electrolyte in cavity 8 to allow ionic conduction between electrodes 11 and 12; a sealing element in the form of a lid 15 for sealing the opening 7; two terminals 17 and 18 each extending between a respective first end 19 located within the cavity 8 and a respective second end 20 located outside the cavity 8, the ends 19 being electrically connected to the respective electrodes 11 and 12, the terminals 17 and 18 extending through the opening 7 such that the ends 20 are available for electrical connection to the PCB 2; Includes:

[0307] According to one embodiment of the present invention, there is provided an SMD EDLC device for reflow soldering to a PCB2, the device comprising: a substantially cylindrical housing 3 defining an opening 7 and a cavity 8 extending from the opening 7; a capacitor element 9 housed within the cavity 8, the element 9 including two carbon-based electrodes 11 and 12 and a separator formed from two separator sheets 13 and 14 spirally wound together with the electrodes 11 and 12, the sheets 13 and 14 maintaining the electrodes 11 and 12 in a spaced apart, opposing arrangement; an electrolyte in cavity 8 for enabling ionic conduction between electrodes 11 and 12, the electrolyte having a freezing point of 0°C or less and a boiling point of 200°C or more at 1 atmosphere pressure; a sealing element in the form of a lid 15 for sealing the opening 7; two terminals 17 and 18 each extending between a first end 19 disposed within the cavity 8 and a second end 20 disposed outside the cavity 8, the ends 19 being electrically connected to the respective electrodes 11 and 12, the terminals 17 and 18 extending through the opening 7 such that the ends 20 are available for electrical connection to the PCB 2; Includes:

[0308] According to one embodiment of the present invention, there is provided an SMD EDLC device for reflow soldering to a PCB2, the device comprising: a housing (3) for defining an opening (7) and a cavity (8) extending from the opening (7); A substantially cylindrical capacitor element 9 is housed within the cavity 8, the element 9 including two electrodes 11 and 12 each comprising carbon particles, a binder for providing cohesion between the particles within each electrode, and a separator in the form of two separator sheets 13 and 14 spirally wound with the electrodes 11 and 12, the separator sheets 13 and 14 maintaining the electrodes 11 and 12 in a spaced apart, opposing arrangement, the binder being selected from the group consisting of carboxymethyl cellulose (CMC), a salt of CMC (carboxymethyl cellulose), a substantially cylindrical capacitor element comprising at least one of a salt of polystyrene sulfonic acid (PSS), such as a Group 1 or Group 2 metal salt of PSS, including magnesium polystyrene sulfonate (MgPSS), sodium polystyrene sulfonate (NaPSS), lithium polystyrene sulfonate (LiPSS), and calcium polystyrene sulfonate (CaPSS), polyvinylidene fluoride (PVDF), and a polyimide; an electrolyte in cavity 8 to allow ionic conduction between electrodes 11 and 12; a sealing element in the form of a lid 15 for sealing the opening 7; two terminals 17 and 18 each extending between a first end 19 disposed within the cavity 8 and a second end 20 disposed outside the cavity 8, the ends 19 being electrically connected to the respective electrodes 11 and 12, the terminals 17 and 18 extending through the opening 7 such that the ends 20 are available for electrical connection to the PCB 2; Includes:

[0309] According to one embodiment of the present invention, there is provided an SMD EDLC device for reflow soldering to a PCB2, the device comprising: a substantially cylindrical housing 3 for defining an opening 7 and a cavity 8 extending from the opening 7; a capacitor element 9 housed within the cavity 8, the element 9 comprising two carbon-based electrodes 11 and 12 and a separator in the form of two separator sheets 13 and 14 spirally wound together with the electrodes 11 and 12, the separator sheets 13 and 14 maintaining the electrodes 11 and 12 in a spaced apart, facing arrangement; an electrolyte in cavity 8 to allow ionic conduction between electrodes 11 and 12; a sealing element in the form of a lid 15 for sealing the opening 7; two terminals 17 and 18 each extending between a respective first end 19 located within the cavity 8 and a respective second end 20 located outside the cavity 8, the ends 19 being electrically connected to the respective electrodes 11 and 12, the terminals 17 and 18 extending through the opening 7 such that the ends 20 are available for electrical connection to the PCB 2; Includes:

[0310] According to one embodiment of the present invention, there is provided an SMD EDLC device for reflow soldering to a PCB2, the device comprising: a malleable housing 3 defining an opening 7, a cavity 8 extending from the opening 7, a sealing surface adjacent the opening 7, and a retention structure in the form of a flange 28; a substantially cylindrical capacitor element 9 housed within the cavity 8, the element 9 including two carbon-based electrodes 11 and 12 and a separator in the form of two separator sheets 13 and 14 spirally wound together with the electrodes 11 and 12, the sheets 13 and 14 maintaining the electrodes 11 and 12 in a spaced apart, opposing arrangement; an electrolyte in cavity 8 to allow ionic conduction between electrodes 11 and 12; a sealing element in the form of a lid 15 for seating against a sealing surface to seal the opening 7, the flange 28 maintaining the seating of the lid 15; two terminals 17 and 18 each extending between a first end 19 disposed within the cavity 8 and a second end 20 disposed outside the cavity 8, the ends 19 being electrically connected to the respective electrodes 11 and 12, the terminals 17 and 18 extending through the opening 7 such that the ends 20 are available for electrical connection to the PCB 2; Includes:

[0311] Those skilled in the art will appreciate that the electrodes of an EDLC device have a much larger surface area than the electrodes of a conventional electrolytic capacitor of the same size. Selecting electrode materials that contribute to this larger surface area typically also results in electrodes that are relatively mechanically more fragile and / or chemically more reactive with other elements within the device. These phenomena become more pronounced in the design of smaller EDLC devices suitable for surface-mount applications due to the desire to use thinner layers of material and the lower overall thermal mass of the device to protect the electrolyte and other components from the thermal shock of the reflow process. Furthermore, smaller EDLC devices with lower thermal mass experience more rapid temperature changes when subjected to the reflow process than larger, non-SMD EDLC devices. The more rapid thermal expansion of individual components within an SMD EDLC device, and the different expansion rates of different components, cause greater structural and chemical strain within the device. The inventors have recognized that accommodating this increased rate of temperature change contributes to the overall benefits of their embodiments, without the need to resort to bulky packaging and expensive manufacturing techniques. Factors in embodiments that contribute to better performance include an electrolyte that has low reactivity with other materials within or on the housing to the temperatures and temperature profiles of the reflow process, a spirally wound cylindrical capacitor element, a complementary cavity for the capacitor element, and a thin-walled housing that not only provides a high level of mechanical support to the capacitor element during the reflow process, but also provides substantially uniform mechanical support to the capacitor element as it undergoes thermal expansion during the reflow process. In particular, it has been found that thermal expansion of spirally wound capacitor elements is more pronounced in the radial direction than in the axial direction. While not wishing to be bound by theory, it is understood that when radial expansion occurs, the action of tensioned winding of the components in a relatively small spirally wound capacitor element results in substantially equal expansion in all radial directions. It is understood that this reduction in any point load reduces the risk of inducing localized deformation or damage in the electrodes or separator sheets.Furthermore, as element 9 expands radially, its outer radial surface progresses into engagement with the inner surface of sidewall 25. As that expansion continues and the radially outer surface of element 9 moves into full or near-full engagement with sidewall 25, that sidewall assumes a shape that will withstand any anticipated radial forces while maintaining the shape of element 9. For example, if element 9 is initially slightly misaligned with axis 4, it will become aligned during any subsequent thermal expansion due to the internal shape and configuration of sidewall 25.

[0312] While not wishing to be bound by theory, it is understood that high-surface-area materials used in electrodes for EDLC devices, particularly those used in carbon-based electrodes, can be difficult to thoroughly remove impurities from before or during electrode and EDLC device fabrication. This results in an increased susceptibility of such devices to reactivity between any chemical functional groups in those impurities and ions in the electrolyte. This effect is typically exacerbated at higher operating voltages and temperatures, such as those encountered during the reflow process, as unwanted gas generation within the housing increases. Prior SMD EDLC devices have attempted to combat this reactivity by using prismatic housings with one or more of the following features: hermetic seals to best prevent the intrusion of unwanted materials that would cause additional gas generation; structurally stronger housings to withstand the increased internal pressure resulting from increased gas generation; and increased thermal mass to prevent the electrolyte from reaching higher temperatures at which increased gas generation occurs. These prior art prismatic housings add significant packaging bulk and / or significant cost in materials and / or manufacturing complexity. The design of element 9 and housing 3 used in the above-described embodiment has been found to accommodate the buildup of pressure within cavity 8 that occurs during a simulated reflow process and during a simulated operating life of device 1.

[0313] Reference is now made to FIG. 18, which illustrates a flowchart of an exemplary method for fabricating device 1. In step 201, predetermined proportions of carbon particles and binder are combined and mixed with a liquid to form a substantially homogeneous slurry. In step 202, a 20-micron-thick elongated aluminum sheet is washed and dried at room temperature before being spirally wound into a coil. The dried sheet is then gradually uncoiled and fed to a coating station, where it is coated across its entire width with a thin layer of slurry containing a liquid and a mixture of carbon particles and binder. The aluminum sheet is immediately advanced to a drying station, including a drying oven, to remove a substantial amount of liquid from the carbon particle and binder mixture. This drying results in the formation of a 20-micron-thick carbon-based layer on the aluminum sheet. In other embodiments, the carbon-based layer has a different thickness. The aluminum sheet is then recoiled and placed in a low-humidity, clean environment to dry more thoroughly.

[0314] In one embodiment, the activated carbon particles are 1200 m 2 / g and 3000m 2 / g。 In one embodiment, the activated carbon has a particle size D50 between 3 μm and 10 μm, D10 > 1 μm, and D90 < 30 μm. In one embodiment, the activated carbon is a microporous carbon, with more than 50% of the pore volume being less than 2 nm in size. Examples of suitable commercially available microporous activated carbons include MSP20 (Kansai Coke), MSC-30 (Kansai Coke), FAR01X (Kansai Coke), YP-80F (Kuraray), RP-25 (Kuraray), RP-20 (Kuraray), NY1151 (Kuraray Chemical Co., Ltd.), NK261H (Kuraray), HDLC 20B STUW (Haycarb PLC), DLC 30 (Haycarb PLC), DLC 20P (Haycarb PLC), HCE-201 (Haycarb PLC), HCE-202 (Haycarb PLC), ACS20 (China Steel Chemical Corporation), ACS25 (China Steel Chemical Corporation), Yec-200E (IHUAN Carbon), YEC-8A (IHUAN Carbon), and YEC-8B (IHUAN Carbon). Carbon), Y-Carbon (Y-Carbon Inc.), ZL-302 (Huzhou Sensheng Activated Carbon Co., Ltd), MCSP2005 (Calgon Mitsubishi Chemical Corporation), MCSP1805A (Calgon Mitsubishi Chemical Corporation), and MCSP1805-1 (Calgon Mitsubishi Chemical Corporation).

[0315] In one embodiment, the activated carbon can be classified as a mesoporous carbon, with more than 50% of the pore volume having a pore size greater than 2 nm. Examples of suitable commercially available mesoporous carbons are P2-15 (EnerG2), MSA-20 (Kansai Coke and Chemicals), YP-50F (Kuraray), NY1251H (Kuraray), YPS (Kuraray), ACS15 (China Steel Chemical Corporation), TDA60 (TDA Research), SO-15A (TDA Research), and ACC (Xiamen All Carbon Corporation).

[0316] Conductive particles present in the carbon-based electrode matrix facilitate efficient electron transport. A typical conductive particle used in EDLCs is carbon black. Carbon black typically has a submicron primary particle size of 10 to 100 nm. Carbon black particles often agglomerate and require high shear forces to disperse well in the electrode slurry. Examples of suitable carbon blacks include L6 (Orion Carbons), PRINTEX® kappa 100 (Orion Engineered Carbons), PRINTEX® XE2 (Orion Engineered Carbons), ENSACO 150G (IMERYS), ENSACO 210G (IMERYS), ENSACO 250G (IMERYS), ENSACO 250F (IMERYS), ENSACO 260G (IMERYS), ENSACO 350G (IMERYS), Super Printex carbon blacks such as C65 (IMERYS), LITX® HP (CABOT), LITX300 (CABOT), LITX200 (CABOT), VXC72R (CABOT), BP700 (CABOT), BP2000 (CABOT), SC2A (CABOT), TPX1278 (CABOT), Lump Black (Degussa), Ketjenblack EC300J (Akzo Noble), Ketjenblack EC600JD (Akzo Noble), E-MM-198G (Timcal), and Super P (Timcal).

[0317] In some embodiments, both sides of the aluminum sheet are coated with the slurry simultaneously. In other embodiments, the coating operation is split, with one side coated and the other side coated following drying. In further embodiments, the aluminum sheet is coated on only one side.

[0318] In step 202, the recoiled aluminum sheet is placed into a slitting station, where the sheet is uncoiled and transversely cut to define a substantially rectangular, longitudinally elongated sheet portion separated from the coil. The longitudinal length of the sheet portion is determined by the required length of the electrode in device 1. The portion is then slit along a longitudinal path offset 7 mm laterally from the elongated longitudinal edge of the portion to remove a sheet segment from the sheet portion. The sheet segment defines an elongated, double-sided carbon-based electrode 11 for device 1. The longitudinal slitting is repeated, with each subsequent transverse offset from the new edge created by the previous slitting operation, to define an elongated, double-sided carbon-based electrode 12. The slitting operation occurs repeatedly until all or substantially all of the sheet portion has been converted into an electrode, at which point an additional sheet portion is removed from the coil and the slitting process begins again. Such slitting may be mechanically acted upon using a blade, however, in one embodiment, the separation of the sheet is performed by another type of cutting, such as laser cutting.

[0319] Once electrodes 11 and 12 are fabricated, they are advanced to a connection station in step 204, where electrodes 11 and 12 are fixedly and electrically connected to their respective terminals 17 and 18. For device 1, the connection between each terminal and its respective electrode includes two separate, spaced-apart connection points. Specifically, face 38 of end 19 of terminal 17 is abutted against one of the surfaces of electrode 11 at a predetermined longitudinal position, with axis 39 substantially perpendicular to axis 4. End 19 is then pierced with two spaced-apart circular punches, which first contact face 37 and then advance through end 19 and the adjacent electrode 11. This action creates two spaced-apart radial structures, each extending from end 19 through electrode 11 and beyond the opposite surface of electrode 11. The radial structures are flattened and moved to engage the opposite surface of electrode 11, thus establishing the necessary locking mechanical and electrical contact between electrode 11 and terminal 17. Similar operations are performed with electrodes 12 and terminals 18. In other embodiments, a different number of contact points are made. In further embodiments, a different number of contact points or other forms of contact and / or contact points are used.

[0320] Electrodes 11 and 12, with terminals 17 and 18 attached, respectively, are then spirally wound around axis 4 along with intermediate sheets 13 and 14 in step 205. The winding process uses a generally cylindrical mandrel extending along axis 4 and having an effective diameter of 4 mm. The mandrel includes two axially extending mandrel pieces with semicircular cross sections. Flat portions of the mandrel pieces face each other and define jaws for receiving and clamping the inner ends of sheets 13 and 14. Once the ends are received and held in the jaws, tension is applied to the sheets, and the mandrel is rotated two or three times to form a hollow cylindrical central core for element 9 along with the inner ends of sheets 13 and 14. The tension on the sheets is then released, and electrodes 11 and 12 are alternately positioned with sheets 13 and 14. Tension is then reapplied so that electrodes 11 and 12 are also under the same tension. The mandrel is again rotated to affect progressive winding of the electrode and separator sheets around the core in substantially uniform tension.

[0321] The final turn of sheet 14 extends circumferentially beyond outer edge 72 of sheet 13, and an adhesive strip 77 is applied to secure end 75 of sheet 14 to the previous underlying turn of sheet 14. The mandrel pieces are then moved slightly radially away from each other to release the clamping force on the inner ends of sheets 13 and 14. The mandrel pieces are then withdrawn from the core by advancing the mandrel pieces axially relative to element 9. This leaves a hollow central axial opening in element 9.

[0322] In other embodiments, the mandrels have different effective diameters. In a further embodiment, the mandrel includes slots for receiving and holding the inner ends of sheets 13 and 14 in an interference fit rather than a pinching engagement. In a still further embodiment, the mandrel includes a non-circular cross-section and is removably received complementary within an opening in the reel to which the inner ends of sheets 13 and 14 are attached. At the end of the winding process, the reel is removed from the mandrel and remains with element 9.

[0323] Upon completion of step 205, a substantially cylindrical element 9 is produced.

[0324] The element 9 is advanced to a filling station where, in step 206, the element 9 is inserted into the cavity 8 of the still-open housing 3. This station then establishes a negative pressure, low humidity, and high temperature environment for the combination of the element 9 and housing 3 to reduce any residual liquid, particularly to remove residual water molecules. A predetermined amount of electrolyte is then placed into the cavity 8 and is absorbed by the separator sheets 13 and 14, migrating into the gap between the carbon-based electrodes to wet them.

[0325] While still at the filling station and still subjected to one or more of negative pressure, low humidity, and elevated temperature, lid 15 is relatively advanced along axis 4 toward opening 7 in step 207 so that ends 20 of terminals 17 and 18 are received by and then extend through respective openings 33 and 34. Lid 15 continues to be advanced along axis 4 relative to housing 3 until ferrule 41 is received within openings 33 and 34 and face 42 engages an adjacent surface of lid 15 in an interference fit. At this point, face 30 of lid 15 advances through opening 7 and is positioned within cavity 8.

[0326] In step 208, the assembly of the above parts is advanced to a forming station for the first and second forming operations described above to seal the opening 7.

[0327] In step 209, base 51 is advanced along axis 4 relative to element 9 so that ends 20 of terminals 17 and 18 are received within respective openings 53 and 54. Base 51 is then further advanced along axis 4 relative to element 9 so that ends 20 extend axially through and beyond base 51, and base 51 abuts end 5 of housing 3. Ends 20 of terminals 17 and 18 are then plastically deformed perpendicular to surfaces 45 and 46 so that ends 20 extend substantially perpendicular to both ends 19 and axis 39. The resulting configuration of terminals 17 and 18 locks and retains base 51 in engagement with end 5. Furthermore, the deformation of ends 20 of terminals 17 and 18 is such that ends 20 of terminals 17 and 18 extend away from each other, and surfaces 46 and 45, respectively, are available for abutment with electrical pads 56 on PCB 2.

[0328] The device 1 is then advanced to a testing station in step 210 where a series of electrical tests are performed to verify that the characteristics of the manufactured SMD EDLC device are within required tolerances and / or other required operating criteria.

[0329] According to an embodiment of the present invention, there is provided a method of manufacturing a device 1 that is an electric double layer capacitor (EDLC) device for reflow soldering to a PCB 2, the method comprising: (a) providing a substantially cylindrical malleable housing having an opening 7 and a cavity 8 extending from the opening 7; (b) plastically deforming the housing 3 to define a sealing surface adjacent the opening 7; (c) plastically deforming the housing 3 to define a retention structure in the form of a flange 28; (d) spirally winding the two carbon-based electrodes 11 and 12 together with a separator in the form of two separator sheets 13 and 14, which maintain the electrodes 11 and 12 in a spaced apart, opposing arrangement, to provide a substantially cylindrical capacitor element 9; (e) placing the element 9 in the cavity 8; (f) providing an electrolyte in cavity 8 to allow ionic conduction between electrodes 11 and 12; (g) providing a sealing element in the form of a lid 15 for seating against a sealing surface to seal the opening 7, a flange 28 maintaining the seating of the lid 15; (h) providing two terminals 17 and 18, each extending between a first end 19 disposed within the cavity 8 and a second end 20 disposed outside the cavity 8; the ends 19 are electrically connected to the respective electrodes 11 and 12, and the terminals 17 and 18 extend through the openings 7 so that the ends 20 are available for electrical connection to the PCB 2; Includes:

[0330] The above-described embodiments of the present invention have been developed for surface mount technology applications and are applicable to a wide range of electrical devices incorporating EDLC surface mount devices, platforms using one or more of these electrical devices, and systems utilizing one or more of these devices or platforms. Examples of electrical devices include computing devices such as desktop computers, servers, controllers, laptop computers, and tablet computers. Within such computing devices, SMD EDLC devices may be included within electrical devices such as graphics cards, memory cards, motherboards, computer peripheral devices, or any other electrical circuitry within an electrical or peripheral device. Other electrical devices to which embodiments of the present invention may be advantageously applied include communication devices such as smartphones, mobile phones, and other cellular devices; control devices such as pump controllers, motor controllers, power management controllers, remote monitoring devices, asset tracking devices, powertrain controllers for electric vehicles or vehicles utilizing internal combustion engines, accessories such as vehicle key fobs, control devices such as electronic locks, wireless handheld devices such as point-of-sale devices, scanning devices, measurement devices, wireless remote control devices, smart meters or other such fixed meters, wearable technology devices such as smart watches and health monitoring patches, IoT devices, wireless sensors, and the like.

[0331] The electrical devices described above may be used on, within, or by a wide variety of platforms, whether mobile or stationary, including, by way of example, land vehicle platforms (whether utilizing propulsion systems powered by internal combustion engines, electrical energy, or otherwise), airborne platforms including drones, computing platforms, surveillance platforms, military platforms, communications platforms, marine platforms both mobile and stationary, wearable technology platforms, etc.

[0332] The electrical devices and platforms described above may be used on, within, or by a wide range of systems, such as telecommunications systems, server systems including single servers, distributed server systems, server farms, etc., and control systems such as fleet management systems, building management systems, manufacturing systems, etc.

[0333] In the foregoing description of exemplary embodiments of the invention, it should be understood that various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and facilitating understanding of one or more of the various inventive aspects. This method of disclosure, however, is not to be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single above-disclosed embodiment. Thus, the claims following the detailed description are expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of this invention.

[0334] Furthermore, some embodiments described herein may include some features but not other features included in other embodiments, but combinations of features from different embodiments are within the scope of the present invention and mean to form different embodiments, as will be understood by those skilled in the art. For example, in the following claims, any of the claimed embodiments can be used in any combination.

[0335] In the description provided herein, numerous specific details are set forth. However, it will be understood that embodiments of the present invention may be practiced without these specific details. In other instances, well-known methods, structures, and techniques have not been shown in detail in order not to obscure an understanding of this description.

[0336] Similarly, it should be noted that the term "connected" as used herein, particularly in the claims, should not be interpreted as being limited only to direct connections. The term "connected" may be used along with its derivatives. It should be understood that these terms are not intended as synonyms for each other. The scope of the expression "device A connected to device B" should not be limited to devices or systems in which the output or element of device A is directly connected to the input or element of device B. This means that a functional path exists between the output of A and the input of B, and this path may include other devices or means. "Coupled" may mean that two or more elements are in direct physical and / or electrical contact, or that two or more elements are not in direct contact with each other but still cooperate or interact with each other to provide a defined connection.

[0337] Having thus described what are believed to be preferred embodiments of the present invention, those skilled in the art will recognize that other or further modifications may be made without departing from the spirit of the present invention, and it is intended that all such changes and modifications be claimed as being within the scope of the present invention. [Explanation of symbols]

[0338] 1 Electric double layer capacitor (EDLC) device, device 2 printed circuit board (PCB), PCB 2a Top, surface 3 Thin-walled malleable aluminum housing, housing, thin-walled aluminum alloy housing 4 Housing shaft, shaft 5 open end, end 6 closed end, end 7 Openings 8 hollow 9 Capacitor element, element 11 Carbon-based electrodes, electrodes, composite electrodes, double-sided carbon-based electrodes 12 Carbon-based electrodes, electrodes, composite electrodes, double-sided carbon-based electrodes 13 Paper-based separator sheet, sheet, separator sheet, paper-based sheet, polytetrafluoroethylene sheet, intermediate sheet 14 Paper-based separator sheet, sheet, paper-based sheet, polytetrafluoroethylene sheet, separator sheet, intermediate sheet 15 Butyl rubber lid, lid 17 Metal terminals, terminals 18 Metal terminals, terminals 19 First end, end 20 second end 25 Side wall 26 Side wall 27 concave channel, channel 28 Circumferential flange, flange 29 sides 30 sides 31 Side wall, surface 33 Opening 34 Opening 37 sides 38 sides 39 Axis of symmetry, axis 41 Ferrule 42 External surface, surface 45 sides 46 sides 47 sides 51 Non-conductive hard high temperature polymer plastic base, base 51a First Side 51b Second Side 53 Through opening, opening 54 Through opening, opening 55 Mounting structure 56 Electric Pads, Pads 57 Linear Channels, Channels 58 Linear Channels, Channels 61 Edge 62 Edge 63 End 64 Edge 65 Edge 66 Edge 67 End 68 Edge 69 Edge 70 Edge 71 End 72 Edge, outer edge 73 Edge 74 Edge 75 End 76 Edge 77 adhesive strips 81 first carbon-based layer, carbon-based layer, layer 82 second carbon-based layer, carbon-based layer, layer 83 Intermediate aluminum sheet current collector 85 First carbon-based layer, layer 86 Second carbon-based layer, layer 87 Intermediate aluminum sheet current collector 91 SMD EDLC devices 92 Protrusion 93 First Shoulder, Shoulder 94 Second Shoulder, Shoulder 95 first internal sealing surface, surface, sealing surface 96 Engagement part 97 Second internal sealing surface, surface, sealing face 98 Third internal sealing surface, surface, sealing surface 99 Fourth internal sealing surface, surface, sealing surface

Claims

1. 1. An electric double layer capacitor (EDLC) device for reflow soldering to a printed circuit board (PCB), said device comprising: a housing for defining an opening and a cavity extending from said opening; a substantially cylindrical capacitor element housed within the cavity, the element including two carbon-based electrodes and a separator spirally wound with the electrodes, the separator maintaining the electrodes in a spaced apart, opposing arrangement; an electrolyte within the cavity to allow ionic conduction between the electrodes; a sealing element for sealing the opening; two terminals each extending between a first end disposed within the cavity and a second end disposed outside the cavity, the first ends electrically connected to respective electrodes, the terminals extending through the openings such that the second ends are available for electrical connection to the PCB; 1. An EDLC device comprising:

2. 2. The EDLC device of claim 1, wherein the PCB includes a PCB surface on which the device is mounted, the device includes a base having a first surface facing the PCB surface, and the terminal extends relative to the base such that the second end is substantially parallel to the PCB surface in use.

3. The EDLC device of claim 2 , wherein the terminals extend through the base.

4. The EDLC device of claim 2 or 3, wherein the terminals extend along the base.

5. The EDLC device of claim 2 , wherein the terminals latchably hold the base to the housing.

6. 6. The EDLC device of claim 2, wherein, in use, the base is disposed between the housing and the PCB surface.

7. 7. The EDLC device of claim 2, wherein the base includes a conductive portion that, in use, is located adjacent the terminal.

8. The EDLC device of claim 1 , wherein the sealing element provides a compressive seal.

9. 10. The EDLC device of claim 8, wherein the housing includes a malleable sidewall that is plastically deformed to define a sealing surface for the compression seal.

10. 10. The EDLC device of claim 9, wherein the malleable sidewall comprises aluminum, an aluminum alloy, or stainless steel.

11. 11. The EDLC device of claim 1, wherein at least one of the electrodes comprises a high surface area carbon-based material.

12. The EDLC device of claim 11 , wherein the carbon-based material comprises mesoporous carbon particles.

13. 13. The EDLC device of claim 1, wherein at least one of the electrodes comprises a binder that is stable to at least 200°C.

14. 14. The EDLC device of claim 1, wherein the electrolyte is an organic electrolyte having a boiling point above 200°C at 1 atmosphere.

15. 15. The EDLC device of any one of claims 1 to 14, having a rated voltage between 2 volts and 4 volts.

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