Electric double layer capacitor device

Abstract

An electric double layer capacitor (EDLC) device (1) for reflow soldering to a printed circuit board (PCB) (2). The device (1) comprises 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 away from the opening (7) and terminating at the end (6). A cylindrical capacitor element (9) is complementarily housed in the cavity (8) and comprises two carbon-based electrodes (11, 12). The diaphragms in the form of two elongate paper-based diaphragm sheets (13, 14) are alternating and helically wound together with the electrodes (11, 12). The tabs (13, 14) hold the electrodes (11, 12) in a spaced and opposed configuration. An electrolyte impregnates the electrodes (11, 12) and the sheets (13, 14) and is contained within the cavity (6) for allowing ion conduction between the electrodes (11, 12). The electrolyte has a freezing point of less than 0 DEG C and a boiling point of more than 200 DEG C at 1 atmospheric pressure. A sealing element in the form of a rubber cover (15) extends over the opening (7) and seals the opening (7). In use, the two terminals (17, 18) each extend between a first end (19) disposed in 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 openings (7) such that the ends (20) can be used for electrical connection to the PCB (2).

Description

Technical Field

[0001] The present invention relates to a supercapacitor, and more particularly to an electric double-layer capacitor (EDLC) device.

[0002] Embodiments of the present invention have been developed for surface mount EDLC devices in electronic components and circuits for computing devices, and will be described specifically with reference to this application. However, it should be understood that the present invention is not limited to such fields of use, but can be applied to a wider range of environments, including but not limited to mobile devices, wearable devices, asset tracking devices, battery-powered devices, and the like. Background Art

[0003] Any discussion of background art in the entire specification should not be construed as an admission that such technology is well known or constitutes a part of common general knowledge in the art.

[0004] EDLC devices, often also referred to as supercapacitors or ultracapacitors, are high specific capacitance devices that utilize high surface area counter electrodes. Such electrodes can be carbon-based and include, for example, corresponding thin coatings or layers having one or more of activated carbon, carbon nanotubes, carbon black, etc. An electrolyte is provided to allow ion conduction between the electrodes. When a potential is applied to the electrodes, the ions in the electrolyte are directed and migrate towards the oppositely polarized electrodes to define two layers of charge adjacent to these respective electrodes. Thus, the EDLC device defines two capacitors in series, where the first capacitor is between the positive electrode and the adjacent negative ion layer formed in the electrolyte, and the second capacitor is between the negative electrode and the adjacent positive ion layer formed in the electrolyte.

[0005] The term "supercapacitor" is synonymous with the term "ultracapacitor", and both are considered interchangeable in this specification.

[0006] For a given weight or volume, EDLC devices typically provide much larger capacitance than conventional capacitors. By comparison, an electrolytic capacitor may be able to provide a volumetric capacitance on the order of 1 mF / cm -3 while an EDLC device can provide a volumetric capacitance on the order of 10 F / cm -3 to 15 F / cm -3 Thus, measures have been taken to apply EDLC devices to a wider range of electronic circuits, particularly those such as microelectronic circuits for computing devices where volume considerations for each electronic component in the circuit are of utmost importance.

[0007] The large-scale manufacture of microelectronic circuits has become increasingly automated and uses a reflow process to surface mount electronic components onto a printed circuit board (PCB). This form of manufacture utilizes surface mount technology (SMT), and the electronic components used in SMT manufacture are referred to in this specification as: surface mount devices (SMDs); or SMT devices. The latter two terms are synonymous and are considered interchangeable in this specification. It should be understood that a PCB may include only SMT devices, or a combination of SMT devices and non-SMT devices.

[0008] The thermal profile for a given reflow process is typically well-defined. For example, this can include a six-minute cycle that has an initial ramp-up phase starting at room temperature, a hold phase at approximately 160°C for 100 seconds, a further ramp-up phase that peaks at approximately 260°C, and a final cool-down phase. Other profiles are also used. In some reflow processes, one or more additional passes through the reflow oven are required to rework components.

[0009] It has been found that conventional EDLC devices typically have a relatively high failure rate or an unacceptable shortened life when subjected to the thermal shock from a reflow process as described above. This problem is more severe for smaller EDLC devices because the smaller devices have less volume to thermally protect the sensitive internal components of the EDLC device.

[0010] To address some of these issues, it is known to provide an EDLC device for a reflow process. In this specification, the EDLC device for the process will be referred to as an SMD EDLC device. A known SMD EDLC device is pre-mounted onto a specially formed PCB using a ceramic substrate (PCT International Application PCT / KR2011 / 008979). The need for such a PCB not only increases the material cost of the process but also the manufacturing complexity as it involves thermocompression bonding a metal casing to the substrate. Other alternatives include: SMD EDLC devices that utilize a sulfuric acid electrolyte with a reinforced encapsulation to better avoid plastic deformation of the encapsulation during reflow; and other SMD EDLC devices that have an organic electrolyte disposed within a hermetic package that provides thermal insulation to reduce the thermal shock experienced by the sensitive internal components of the SMD EDLC device. Examples of the latter package include laser-welded ceramics (PCT International Application PCT / US2021 / 040625), thermally welded LCP (US 8,773,841), and other materials. The above encapsulation options generally involve using materials that are relatively expensive, sometimes prohibitively so; require a fair amount of additional, often time-consuming and expensive manufacturing steps to produce the EDLC device; and are bulky.

[0011] Accordingly, there is a need in the art for an improved EDLC device for reflow soldering to a PCB. SUMMARY OF THE INVENTION

[0012] It is an object of the present invention to overcome or ameliorate at least one disadvantage of the prior art, or to provide a useful alternative.

[0013] One embodiment provides an electric double layer capacitor (EDLC) device for reflow soldering to a printed circuit board (PCB), the device comprising:

[0014] a housing for defining an opening and a cavity extending away from the opening;

[0015] a substantially cylindrical capacitor element received within the cavity, the element including two carbon-based electrodes and a separator helically wound therewith, wherein the separator holds the electrodes in a spaced-apart and opposing configuration;

[0016] an electrolyte within the cavity for allowing ionic conduction between the electrodes;

[0017] a sealing element for sealing the opening; and

[0018] Two terminals, each extending between a first end disposed within the cavity and a second end disposed outside the cavity, wherein: the first end is electrically connected to a respective electrode; and the terminal extends through the opening such that the second end can be used for electrical connection to a PCB.

[0019] In one embodiment, the PCB includes a PCB surface on which the device is to be mounted, and the device includes a base having a first face opposite the PCB surface, and the terminal extends relative to the base such that in use, the second end is substantially parallel to the PCB surface. In one embodiment, the terminal extends through the base. In one embodiment, the terminal extends along the base. In one embodiment, the terminal captively holds the base to the housing. In one embodiment, in use, the base is disposed between the housing and the PCB surface. In one embodiment, the base includes a conductive portion which, in use, is disposed adjacent to the terminal.

[0020] In one embodiment, the sealing element provides a compression seal. In one embodiment, the housing includes a ductile sidewall that plastically deforms to define a sealing surface for the compression seal. In one embodiment, the ductile sidewall includes aluminum, an aluminum alloy, or stainless steel. In one embodiment, the wall thickness of the ductile sidewall is less than at least one of: 1 millimeter; 0.5 millimeter; 300 micrometers; 290 micrometers; 280 micrometers; 270 micrometers; 260 micrometers; and 250 micrometers. In one embodiment, the wall thickness of the ductile sidewall is greater than at least one of: 300 micrometers; 350 micrometers; 370 micrometers; 380 micrometers; 390 micrometers; and 400 micrometers.

[0021] In one embodiment, at least one of the electrodes includes a high surface area carbon-based material. In one embodiment, the carbon-based material has a surface area greater than or equal to 400 m 2 / g. In one embodiment, the carbon-based material includes one or more of: carbon particles; graphene; reduced graphene oxide; carbon nanotubes; carbon fibers; and carbon foam. In one embodiment, the carbon particles include one or more of: activated carbon particles; and carbon black particles. In one embodiment, the carbon particles include mesoporous carbon particles.

[0022] In one embodiment, at least one electrode includes a binder. In one embodiment, the binder is one or more of the following: carboxymethylcellulose (CMC); salts of CMC such as sodium carboxymethylcellulose; polytetrafluoroethylene (PTFE); salts of polystyrenesulfonate (PSS), such as Group I or Group II metal salts 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. In one embodiment, the binder includes a fluorinated polymer. In one embodiment, the binder is stable at at least 200 °C.

[0023] In one embodiment, at least one electrode is binder-free. In one embodiment, at least one electrode includes one or more of the following: graphene; and carbon nanotubes.

[0024] In one embodiment, the electrolyte is an organic electrolyte having a boiling point greater than 200 °C at 1 atmosphere.

[0025] In one embodiment, the EDLC device has an initial ESR (ESR1), where:

[0026] The housing has a housing temperature (T H );

[0027] At T H After following a predetermined thermal curve, the device has a second ESR (ESR2), where:

[0028] ESR2 ≥ ESR1; and

[0029] And

[0030] The predetermined thermal curve includes a temperature threshold (T T ) of at least 180 °C and a threshold duration (t D ), where 25 seconds ≤ t D ≤ 40 seconds.

[0031] In one embodiment, TT is one of the following: 180 °C; and 217 °C.

[0032] In one embodiment, at least one of the following conditions is satisfied:

[0033]

[0034] and

[0035] In one embodiment, T T = 180 °C, and one or more of the following conditions are satisfied:

[0036] and

[0037] In one embodiment, the EDLC device has a rated voltage between 2 volts and 4 volts. In one embodiment, the capacitor element defines at least one capacitor unit, wherein, in use, the unit is exposed to the rated voltage. In one embodiment, the EDLC device has a rated voltage of at least 3 volts and

[0038] In one embodiment, during a predetermined thermal curve, the maximum value of T H is T max where T max ≥ T T and at least one of the following conditions is satisfied: T max ≤ 260 °C; T max ≤ 250 °C; T max ≤ 240 °C; T max ≤ 230 °C; T max ≤ 220 °C; T max ≤ 210 °C; and T max ≤ 200 °C.

[0039] In one embodiment, at least one electrode comprises a mixture of activated carbon particles and conductive carbon particles. In one embodiment, the carbon particles comprise one or more of the following: mesoporous carbon particles; and microporous carbon particles.

[0040] In one embodiment, at least one electrode comprises entangled carbon nanotubes.

[0041] The electrolyte can be any suitable electrolyte. In one embodiment, the electrolyte includes an organic salt (such as an ionic liquid) or an organic salt (solid or liquid) included as a solution in a neutral organic compound / solvent. Although a single salt or a single organic compound / solvent may be mentioned herein, it should be understood throughout the disclosure that a single electrolyte can contain one or more organic salts and may or may not contain a neutral organic compound / solvent, or can contain one or two or more neutral organic compounds / solvents.

[0042] In one embodiment, the electrolyte includes at least one of the following: 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 includes an organic salt. In one embodiment, the organic electrolyte includes two or more organic salts. In one embodiment, the electrolyte has a boiling point of 210 °C or higher, 220 °C or higher, 230 °C or higher, 240 °C or higher, or 250 °C or higher at 1 atmosphere. In one embodiment, the electrolyte has a freezing point of -10 °C or lower, -20 °C or lower, -30 °C or lower, or -40 °C or lower at 1 atmosphere.

[0043] In one embodiment, the electrolyte is immiscible with the binder used in the electrode. In another embodiment, the electrolyte is immiscible with the binder at a temperature of 200 °C or higher, 210 °C or higher, 220 °C or higher, 240 °C or higher, 250 °C or higher, or 260 °C or higher.

[0044] In one embodiment, the neutral compound is a neutral organic compound. The neutral organic compound can be a liquid or a solid at room temperature (such as at 20 °C and 1 atmosphere). It should be understood that when used, the neutral organic compound acts as a solvent and can thus also be alternatively referred to as a neutral organic solvent. The neutral organic solvent preferably has certain properties suitable for solvating the organic salt (in some embodiments, an ionic liquid). In one embodiment, the neutral organic solvent is a liquid, such as an aprotic liquid solvent in which the organic salt is mixed or dissolved. In another embodiment, when the neutral organic solvent is a solid at 20 °C and 1 atmosphere, the organic solvent can be heated above its melting point so that it is in a liquid state 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.

[0045] 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.

[0046] In one embodiment, the at least one neutral organic compound or polar aprotic organic solvent is selected from: linear or cyclic carbonates (R-O-C(=O)-O-R'), cyclic lactones (-C(=O)-O-), or linear or cyclic sulfones (R-S(=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 following chemical structure:

[0047]

[0048] wherein R 9 is: H, CH3, fluoromethyl or F. In one embodiment, the cyclic carbonate contains at least one C-F bond.

[0049] In one embodiment, the at least one neutral organic compound or polar aprotic solvent is a linear or cyclic sulfone. In one embodiment, the sulfone has the following linear structure:

[0050]

[0051] wherein R 10 and R 11 are each independently a C1-C4 alkyl group. In one embodiment, R 10 and R 11 are the same. In one embodiment, R 10 and R 11 are both ethyl. In one embodiment, R 10 and R 11 are different alkyl groups.

[0052] In one embodiment, the sulfone has the following cyclic structure:

[0053]

[0054] wherein R 12 is H or CH3. In one embodiment, the sulfone is sulfolane.

[0055] In one embodiment, the at least one neutral organic compound or polar aprotic solvent is a lactone. In one embodiment, the cyclic lactone is γ-butyrolactone.

[0056] 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 or polar aprotic organic solvent, or two or more organic salts dissolved in a mixture of two or more organic or polar aprotic organic solvents.

[0057] 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 chemical structure:

[0058]

[0059] wherein R 1 、R 2 、R 3 and R 4 are each an alkyl substituent. In one embodiment, R 1 、R 2 、R 3 and R 4 are each independently a straight-chain or branched C1-C7 alkyl. In one embodiment, R 1 、R 2 、R 3 and R 4 are each independently a straight-chain or branched C1-C4 alkyl. In one embodiment, R 1 、R 2 、R 3 and R 4 are each independently a straight-chain or branched C1-C2 alkyl.

[0060] In one embodiment, R 1 is different from at least one of R 2 、R 3 and R 4 In one embodiment, R 1 、R 2 、R 3 and R 4 are different from each other.

[0061] In one embodiment, the quaternary ammonium cation has the chemical structure:

[0062]

[0063] wherein R 5 and R 6 are each an alkyl substituent. In one embodiment, R 5 and R 6 are each independently a straight-chain or branched C1-C7 alkyl. In one embodiment, R 5 is different from R 6. In one embodiment, the quaternary ammonium cation is a spiro-bicyclic compound, wherein 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.

[0064] In one embodiment, the anion is one or more of borate, phosphate, and sulfonimide. In one embodiment, the anion is one or more of tetrafluoroborate (TFB), tetracyanoborate, fluorotricyanoborate, difluorodicyanoborate, trifluorocyanoborate, bis(oxalato)borate, and difluoro(oxalato)borate. In one embodiment, the anion is one or more of bis(fluorosulfonyl)imide (FSI) and bis(trifluoromethylsulfonyl)imide (TFSI).

[0065] In another embodiment, the organic salt is 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 thermal decomposition temperature of the ionic liquid is: 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 solid at 20 °C and 1 atmosphere.

[0066] In one embodiment, the outer shell is formed at least substantially of metal. In one embodiment, the metal includes aluminum, aluminum alloy, or stainless steel alloy.

[0067] In one embodiment, the cavity is substantially cylindrical and complementarily houses the capacitor element. In one embodiment, the housing includes: a substantially cylindrical first sidewall axially extending between a first end and a second end, wherein the first end defines an opening; and a substantially circular second sidewall extending on the second end. In one embodiment, the first sidewall is thin and ductile. In one embodiment, the wall thickness of the first sidewall is less than 1 mm. In one embodiment, the wall thickness of the first sidewall is less than 0.5 mm. In one embodiment, the first sidewall and the second sidewall are integrally formed.

[0068] In one embodiment, the separator includes one or more porous separator sheets, each separator sheet containing at least one of the following: polytetrafluoroethylene (PTFE); cellulose fibers; polyacrylonitrile fibers; aramid fibers; glass fibers; and polyethylene terephthalate (PET).

[0069] In one embodiment, the melting point of the separator is: 200 °C or higher; 220 °C or higher; 230 °C or higher; 240 °C or higher; and 250 °C or higher.

[0070] Another embodiment provides an electric double layer capacitor (EDLC) device for reflow soldering to a printed circuit board (PCB), the device including:

[0071] A housing for defining an opening and a cavity extending away from the opening;

[0072] A substantially cylindrical capacitor element housed in the cavity, the element including two carbon-based electrodes and a separator helically wound with the electrodes, wherein the separator holds the electrodes in a spaced-apart and opposing configuration;

[0073] An electrolyte within the cavity for allowing ionic conduction between the electrodes, the electrolyte having a freezing point of 0 °C or lower and a boiling point of 200 °C or higher at 1 atmosphere;

[0074] A sealing element for sealing the opening; and

[0075] Two terminals, each terminal extending between a first end disposed within the cavity and a second end disposed outside the cavity, wherein: the first end is electrically connected to a corresponding electrode; and the terminal extends through the opening such that the second end can be used for electrical connection to the PCB.

[0076] Another embodiment provides an electric double layer capacitor (EDLC) device for reflow soldering to a printed circuit board (PCB), the device including:

[0077] A housing for defining an opening and a cavity extending away from the opening;

[0078] A capacitor element received in the cavity, the element including two carbon-based electrodes and a separator for holding the electrodes in a spaced-apart and opposing configuration;

[0079] An electrolyte within the cavity for permitting ionic conduction between the electrodes, the electrolyte having a freezing point of 0 °C or lower and a boiling point of 200 °C or higher at 1 atmosphere;

[0080] A sealing element for providing a compression seal that seals the opening; and

[0081] Two terminals, each extending between a first end disposed within the cavity and a second end disposed outside the cavity, wherein: the first end is electrically connected to a respective electrode; and the terminal extends through the opening such that the second end can be used for electrical connection to a PCB.

[0082] Another embodiment provides an electric double layer capacitor (EDLC) device for reflow soldering to a printed circuit board (PCB), the device including:

[0083] A ductile housing for defining an opening and a cavity extending away from the opening;

[0084] A capacitor element received in the cavity, the element including two carbon-based electrodes and a separator helically wound with the electrodes, wherein the separator holds the electrodes in a spaced-apart and opposing configuration;

[0085] An electrolyte within the cavity for permitting ionic conduction between the electrodes

[0086] A sealing element for sealing the opening; and

[0087] Two terminals, each extending between a respective first end located within the cavity and a respective second end located outside the cavity, wherein: the first end is electrically connected to a respective electrode; and the terminal extends through the opening such that the second end can be used for electrical connection to a PCB.

[0088] Another embodiment provides an electric double layer capacitor (EDLC) device for reflow soldering to a printed circuit board (PCB), the device including:

[0089] A housing having high thermal conductivity for defining an opening and a cavity extending away from the opening;

[0090] A capacitor element, which is received in the cavity, the element comprising two carbon-based electrodes and a separator spirally wound with the electrodes, wherein the separator holds the electrodes in a spaced-apart and opposing configuration;

[0091] An electrolyte within the cavity, which is for allowing ionic conduction between the electrodes;

[0092] A sealing element, which is for sealing the opening; and

[0093] Two terminals, each terminal extending between a respective first end located within the cavity and a respective second end located outside the cavity, wherein: the first end is electrically connected to the respective electrode; and the terminal extends through the opening such that the second end can be used for electrical connection to a PCB.

[0094] Another embodiment provides an electric double layer capacitor (EDLC) device for reflow soldering to a printed circuit board (PCB), the device comprising:

[0095] A substantially cylindrical housing, which is for defining an opening and a cavity extending away from the opening;

[0096] A capacitor element, which is received in the cavity, the element comprising two carbon-based electrodes and a separator spirally wound with the electrodes, wherein the separator holds the electrodes in a spaced-apart and opposing configuration;

[0097] An electrolyte within the cavity, which is for allowing ionic conduction between the electrodes, the electrolyte having a freezing point of 0 °C or lower and a boiling point of 200 °C or higher at 1 atmosphere;

[0098] A sealing element, which is for sealing the opening; and

[0099] Two terminals, each terminal extending between a first end disposed within the cavity and a second end disposed outside the cavity, wherein: the first end is electrically connected to the respective electrode; and the terminal extends through the opening such that the second end can be used for electrical connection to a PCB.

[0100] Another embodiment provides an electric double layer capacitor (EDLC) device for reflow soldering to a printed circuit board (PCB), the device comprising:

[0101] A substantially cylindrical housing, which is for defining an opening and a cavity extending away from the opening;

[0102] A capacitor element, which is received in the cavity, the element comprising two carbon-based electrodes and a separator spirally wound with the electrodes, wherein the separator holds the electrodes in a spaced-apart and opposing configuration;

[0103] An electrolyte within the cavity for allowing ion conduction between the electrodes;

[0104] A sealing element for sealing the opening; and

[0105] Two terminals, each extending between a respective first end located within the cavity and a respective second end located outside the cavity, wherein: the first end is electrically connected to the respective electrode; and the terminals extend through the opening such that the second ends can be used for electrical connection to a PCB.

[0106] Another embodiment provides an electric double layer capacitor (EDLC) device for reflow soldering to a printed circuit board (PCB), the device comprising:

[0107] A ductile housing for defining an opening, a cavity extending away from the opening, a sealing surface adjacent to the opening, and a retaining structure;

[0108] A substantially cylindrical capacitor element received within the cavity, the element comprising two carbon-based electrodes and a separator spirally wound together with the electrodes, wherein the separator holds the electrodes in a spaced-apart and opposing configuration;

[0109] An electrolyte within the cavity for allowing ion conduction between the electrodes;

[0110] A sealing element for being disposed against the sealing surface to seal the opening, wherein the retaining structure maintains the disposition of the sealing element; and

[0111] Two terminals, each extending between a first end disposed within the cavity and a second end disposed outside the cavity, wherein: the first end is electrically connected to the respective electrode; and the terminals extend through the opening such that the second ends can be used for electrical connection to a PCB.

[0112] In one embodiment, the boiling point of the electrolyte at 1 atmosphere is at least one of the following: 210 °C or higher; 220 °C or higher; 230 °C or higher; 240 °C or higher; and 250 °C or higher.

[0113] In one embodiment, the freezing point of the electrolyte at 1 atmosphere is at least one of the following: -10 °C or lower; -20 °C or lower; -30 °C or lower; and -40 °C or lower.

[0114] In one embodiment, the housing includes a substantially cylindrical first sidewall extending along a sidewall axis. In one embodiment, the wall thickness of the first sidewall is less than 1 mm. In one embodiment, the wall thickness of the first sidewall is 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 defines an opening; and the housing includes a second sidewall extending at the second end. In one embodiment, the first sidewall defines an opening and a sealing surface adjacent to the opening for engaging with a sealing element. In one embodiment, the first sidewall defines a retaining structure for retaining the sealing element in engagement with the sealing surface in a limiting manner. In one embodiment, the engagement of the sealing element with the sealing surface defines a compression seal. In one embodiment, the retaining structure is integrally formed with the first sidewall. In one embodiment, the terminal is directly and hermetically engaged with the sealing element. In one embodiment, the sealing element is integral.

[0115] In one embodiment, each electrode includes carbon particles. In one embodiment, the EDLC device includes an adhesive for providing cohesion between the particles. In one embodiment: each electrode includes a current collector for electrically connecting the carbon particles of the electrode to a corresponding terminal; and the adhesive provides adhesion between the particles of each electrode and their respective current collectors. In one embodiment, the carbon particles have an average pore size greater than 2 nm.

[0116] In one embodiment, the electrolyte is an organic electrolyte having a freezing point of 0 °C or lower and a boiling point of 200 °C or higher at 1 atmosphere, and the organic electrolyte includes at least one of the following: an ionic liquid; an organic solvent including a cyclic or linear organic sulfur or sulfone compound and at least one organic salt; an organic liquid including a cyclic or linear carbonate and at least one organic salt; and an organic liquid including a cyclic lactone (such as γ-butyrolactone) and at least one organic salt.

[0117] In one embodiment, the organic sulfur is sulfolane. In one embodiment, the carbonate is propylene carbonate. In one embodiment, the organic solvent includes γ-butyrolactone. In one embodiment, the organic liquid contains tetrafluoroborate, such as the organic salt contains a tetrafluoroborate anion.

[0118] In one embodiment, each electrode includes a carbon base layer and a current collector for electrically connecting the carbon base layer to a corresponding terminal; two carbon-based electrodes and a separator are spirally wound together along a winding axis; and the separator extends along the winding axis beyond the electrodes. In one embodiment, the separator extends along the winding axis beyond the electrodes to define two opposite free ends that are inclined towards the winding axis.

[0119] Another embodiment provides an electric double - layer capacitor (EDLC) device for reflow soldering to a printed circuit board (PCB), the device comprising:

[0120] A housing for defining an opening and a cavity extending away from the opening;

[0121] A substantially cylindrical capacitor element received in the cavity, the element comprising two electrodes, each electrode including carbon particles, a binder for providing cohesion between the particles in each binder, and a separator helically wound with the electrode, wherein the separator holds the electrodes in a spaced - apart and opposed configuration, and the binder comprises at least one of: carboxymethyl cellulose (CMC); a salt of CMC such as sodium carboxymethyl cellulose; polytetrafluoroethylene (PTFE); a salt of polystyrene sulfonate (PSS), such as a Group I or Group II 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;

[0122] An electrolyte within the cavity for permitting ionic conduction between the electrodes;

[0123] A sealing element for sealing the opening; and

[0124] Two terminals, each terminal extending between a first end disposed within the cavity and a second end disposed outside the cavity, wherein: the first end is electrically connected to a respective electrode; and the terminal extends through the opening such that the second end can be used for electrical connection to the PCB.

[0125] Another embodiment provides an electric double - layer capacitor (EDLC) device for reflow soldering to a printed circuit board (PCB), the printed circuit board having a PCB surface with two pads, the device comprising:

[0126] A base having a first face for facing the PCB surface and a second face opposite the first face;

[0127] A housing for defining an opening opposite the second face in use and a cavity extending away from the opening;

[0128] A substantially cylindrical capacitor element received in the cavity, the element comprising:

[0129] Two carbon - based electrodes, wherein each electrode includes carbon particles;

[0130] A porous separator, which is wound spirally with the electrodes, wherein the separator holds the electrodes in a spaced-apart and opposite configuration and comprises one or more of the following: polytetrafluoroethylene; cellulose fibers; polyacrylonitrile fibers; aramid fibers; and glass fibers;

[0131] An electrolyte within the cavity, which is used to allow ion conduction between the electrodes, and the electrolyte has a freezing point of 0 °C or lower and a boiling point of 200 °C or higher at 1 atmosphere;

[0132] A sealing element, which is used to provide a compression seal for sealing the opening; and

[0133] Two terminals, each terminal extending between a first end disposed within the cavity and a second end disposed outside the cavity, wherein: the first end is electrically connected to the corresponding electrode; and the terminals extend through the opening and the base such that in use, the second end is substantially parallel to the PCB surface and is electrically connected to the corresponding pad.

[0134] Another embodiment provides an electronic device, which comprises at least one EDLC device of any one of the foregoing embodiments.

[0135] Another embodiment comprises a platform, which comprises any one or more of the following: at least one EDLC device according to any one of the above embodiments of the EDLC device; and at least one electronic device according to the above embodiments for an electronic device.

[0136] Another embodiment comprises a system, which comprises one or more of the following: at least one EDLC device according to any one of the above embodiments of the EDLC device; at least one electronic device according to the above embodiments of the electronic device; and at least one platform according to the above embodiments of the platform.

[0137] Another embodiment comprises a printed circuit board, to which at least one EDLC device according to any one of the above embodiments of the EDLC device is reflow soldered.

[0138] Another embodiment comprises a method for manufacturing a double-layer capacitor (EDLC) device for reflow soldering to a printed circuit board (PCB), the method comprising:

[0139] (a) Providing a substantially cylindrical ductile housing, which has an opening and a cavity extending away from the opening;

[0140] (b) Plasticly deforming the housing to define a sealing surface adjacent to the opening;

[0141] (c) Plasticly deforming the housing to define a holding structure;

[0142] (d)Helically wind two carbon-based electrodes with a separator to provide a substantially cylindrical capacitor element, wherein the separator holds the electrodes in a spaced-apart and opposing configuration;

[0143] (e)Accommodate the capacitor element within a cavity;

[0144] (f)Provide an electrolyte within the cavity to permit ionic conduction between the electrodes;

[0145] (g)Provide a sealing element for placement against a sealing surface to seal the opening, wherein a retaining structure maintains the placement of the sealing element; and

[0146] (h)Provide two terminals, each extending between a first end disposed within the cavity and a second end disposed outside the cavity, wherein: the first end is electrically connected to a respective electrode; and the terminals extend through the opening such that the second ends can be used for electrical connection to a PCB.

[0147] In one embodiment, step (e) is before step (b). In one embodiment, step (e) is before step (c). In one embodiment, step (e) is before step (f). In one embodiment, steps (b) and (c) occur synchronously. In one embodiment, steps (b) and (c) occur simultaneously.

[0148] Another embodiment provides a method of manufacturing an electric double layer capacitor (EDLC) device for reflow soldering to a printed circuit board (PCB), the printed circuit board having a PCB surface with two solder pads, the method comprising the steps of:

[0149] Provide a base having a first face for opposing the PCB surface and a second face opposite the first face;

[0150] Define, with a housing, an opening opposite the second face in use and a cavity extending away from the opening;

[0151] Accommodate a substantially cylindrical capacitor element within the cavity, the element comprising:

[0152] Two carbon-based electrodes, wherein each electrode comprises carbon particles; and

[0153] A porous separator helically wound with the electrodes, wherein the separator holds the electrodes in a spaced-apart and opposing configuration and comprises one or more of the following: polytetrafluoroethylene; cellulose fibers; polyacrylonitrile fibers; aramid fibers;

[0154] And glass fibers;

[0155] Provide an electrolyte within the cavity for allowing ionic conduction between the electrodes, the electrolyte having a freezing point of 0 °C or lower and a boiling point of 200 °C or higher at 1 atmosphere;

[0156] Provide a compression seal having a sealing element for sealing the opening; and

[0157] Provide two terminals, each terminal extending between a first end disposed within the cavity and a second end disposed outside the cavity, wherein: the first end is electrically connected to a corresponding electrode; and the terminal extends through the opening and the base such that, in use, the second end is substantially parallel to the PCB surface and electrically connected to a corresponding pad.

[0158] Another embodiment provides a method of manufacturing an electric double layer capacitor (EDLC) device for reflow soldering to a printed circuit board (PCB), the method comprising the steps of:

[0159] Define an opening and a cavity extending away from the opening with a housing;

[0160] Accommodate a substantially cylindrical capacitor element within the cavity, the element comprising two carbon-based electrodes and a separator helically wound with the electrodes, wherein the separator holds the electrodes in a spaced-apart and opposing configuration;

[0161] Provide an electrolyte within the cavity for allowing ionic conduction between the electrodes, the electrolyte having a freezing point of 0 °C or lower and a boiling point of 200 °C or higher at 1 atmosphere;

[0162] Seal the opening with a sealing element; and

[0163] Provide two terminals, each terminal extending between a first end disposed within the cavity and a second end disposed outside the cavity, wherein: the first end is electrically connected to a corresponding electrode; and the terminal extends through the opening such that the second end can be used for electrical connection to the PCB.

[0164] Another embodiment provides a method of manufacturing an electric double layer capacitor (EDLC) device for reflow soldering to a printed circuit board (PCB), the method comprising the steps of:

[0165] Define an opening and a cavity extending away from the opening with a housing;

[0166] Accommodate a capacitor element within the cavity, the element comprising two carbon-based electrodes and a separator for holding the electrodes in a spaced-apart and opposing configuration;

[0167] Provide an electrolyte within the cavity for allowing ionic conduction between the electrodes, the electrolyte having a freezing point of 0 °C or lower and a boiling point of 200 °C or higher at 1 atmosphere;

[0168] Provide a compression seal having a sealing element for sealing the opening; and

[0169] Provide two terminals, each terminal extending between a first end disposed within the cavity and a second end disposed outside the cavity, wherein: the first end is electrically connected to a corresponding electrode; and the terminal extends through the opening such that the second end can be used for electrical connection to a PCB.

[0170] Another embodiment provides a method of manufacturing an electric double layer capacitor (EDLC) device for reflow soldering to a printed circuit board (PCB), the method comprising the steps of:

[0171] Define an opening and a cavity extending away from the opening with a housing;

[0172] Accommodate a substantially cylindrical capacitor element within the cavity, the element comprising two carbon-based electrodes and a separator helically wound with the electrodes, wherein the separator holds the electrodes in a spaced-apart and opposing configuration;

[0173] Provide an electrolyte within the cavity for allowing ionic conduction between the electrodes;

[0174] Seal the opening with a sealing element; and

[0175] Provide two terminals, each terminal extending between a first end disposed within the cavity and a second end disposed outside the cavity, wherein: the first end is electrically connected to a corresponding electrode; and the terminal extends through the opening such that the second end can be used for electrical connection to a PCB.

[0176] Another embodiment provides a method of manufacturing an electric double layer capacitor (EDLC) device for reflow soldering to a printed circuit board (PCB), the method comprising the steps of:

[0177] Define an opening and a cavity extending away from the opening with a ductile housing;

[0178] Accommodate a capacitor element within the cavity, the element comprising two carbon-based electrodes and a separator helically wound with the electrodes, wherein the separator holds the electrodes in a spaced-apart and opposing configuration;

[0179] Provide an electrolyte within the cavity for allowing ionic conduction between the electrodes;

[0180] Seal the opening with a sealing element; and

[0181] Two terminals are provided, each extending between a respective first end located within a cavity and a respective second end located outside the cavity, wherein: the first end is electrically connected to a respective electrode; and the terminal extends through an opening such that the second end can be used for electrical connection to a PCB.

[0182] Another embodiment provides a method of manufacturing an electric double layer capacitor (EDLC) device for reflow soldering to a printed circuit board (PCB), the method comprising the steps of:

[0183] Defining an opening and a cavity extending away from the opening with a housing having high thermal conductivity;

[0184] Accommodating a capacitor element in the cavity, the element comprising two carbon-based electrodes and a separator helically wound with the electrodes, wherein the separator holds the electrodes in a spaced and opposite configuration;

[0185] Providing an electrolyte within the cavity for allowing ionic conduction between the electrodes;

[0186] Sealing the opening with a sealing element; and

[0187] Two terminals are provided, each extending between a respective first end located within a cavity and a respective second end located outside the cavity, wherein: the first end is electrically connected to a respective electrode; and the terminal extends through an opening such that the second end can be used for electrical connection to a PCB.

[0188] Another embodiment provides a method of manufacturing an electric double layer capacitor (EDLC) device for reflow soldering to a printed circuit board (PCB), the method comprising the steps of:

[0189] Defining an opening and a cavity extending away from the opening with a substantially cylindrical housing;

[0190] Accommodating a capacitor element in the cavity, the element comprising two carbon-based electrodes and a separator helically wound with the electrodes, wherein the separator holds the electrodes in a spaced and opposite configuration;

[0191] Providing an electrolyte within the cavity for allowing ionic conduction between the electrodes, the electrolyte having a freezing point of 0 °C or lower and a boiling point of 200 °C or higher at 1 atmosphere;

[0192] Sealing the opening with a sealing element; and

[0193] Two terminals are provided, each extending between a first end disposed within the cavity and a second end disposed outside the cavity, wherein: the first end is electrically connected to a corresponding electrode; and the terminal extends through the opening such that the second end can be used for electrical connection to a PCB.

[0194] Another embodiment provides a method of manufacturing a double - layer capacitor (EDLC) device for reflow soldering to a printed circuit board (PCB), the method comprising the steps of:

[0195] Defining an opening and a cavity extending away from the opening with a housing;

[0196] Accommodating a substantially cylindrical capacitor element within the cavity, the element comprising two electrodes, each electrode comprising carbon particles, a binder for providing cohesion between the particles in each binder, and a separator helically wound with the electrode, wherein the separator holds the electrodes in a spaced - apart and opposite configuration, and the binder comprises at least one of: carboxymethyl cellulose (CMC); a salt of CMC such as sodium carboxymethyl cellulose; polytetrafluoroethylene (PTFE); a salt of polystyrene sulfonate (PSS), such as a Group I or II 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;

[0197] Providing an electrolyte within the cavity for allowing ionic conduction between the electrodes;

[0198] Sealing the opening with a sealing element; and

[0199] Two terminals are provided, each extending between a first end disposed within the cavity and a second end disposed outside the cavity, wherein: the first end is electrically connected to a corresponding electrode; and the terminal extends through the opening such that the second end can be used for electrical connection to a PCB.

[0200] Another embodiment provides a method of manufacturing a double - layer capacitor (EDLC) device for reflow soldering to a printed circuit board (PCB), the method comprising:

[0201] Defining an opening and a cavity extending away from the opening with a substantially cylindrical housing;

[0202] Accommodating a capacitor element within the cavity, the element comprising two carbon - based electrodes and a separator helically wound with the electrodes, wherein the separator holds the electrodes in a spaced - apart and opposite configuration;

[0203] Provide an electrolyte within the cavity for allowing ionic conduction between the electrodes;

[0204] Seal the opening with a sealing element; and

[0205] Provide two terminals, each extending between a respective first end located within the cavity and a respective second end located outside the cavity, wherein: the first end is electrically connected to a respective electrode; and the terminal extends through the opening such that the second end can be used for electrical connection to a PCB.

[0206] Another embodiment provides a method of manufacturing an electric double layer capacitor (EDLC) device for reflow soldering to a printed circuit board (PCB), the method comprising the steps of:

[0207] Define an opening, a cavity extending away from the opening, a sealing surface adjacent to the opening, and a retaining structure with a ductile housing;

[0208] Accommodate a substantially cylindrical capacitor element within the cavity, the element comprising two carbon-based electrodes and a separator spirally wound together with the electrodes, wherein the separator holds the electrodes in a spaced-apart and opposing configuration;

[0209] Provide an electrolyte within the cavity for allowing ionic conduction between the electrodes;

[0210] Position a sealing element against the sealing surface to seal the opening, wherein the retaining structure maintains the positioning of the sealing element; and

[0211] Provide two terminals, each extending between a first end disposed within the cavity and a second end disposed outside the cavity, wherein: the first end is electrically connected to a respective electrode; and the terminal extends through the opening such that the second end can be used for electrical connection to a PCB.

[0212] Throughout the specification, references to "one embodiment", "some embodiments", "another embodiment", "other embodiments", "an embodiment", or similar terms mean that the particular features, structures, or characteristics described in connection with the embodiment are included in at least one embodiment of the invention. Thus, appearances of the phrases "in one embodiment", "in some embodiments", "in an embodiment", or similar phrases throughout this specification are not necessarily all referring to the same embodiment, but may. Furthermore, in one or more embodiments, the particular features, structures, or characteristics may be combined in any suitable manner, as will be apparent to those of ordinary skill in the art from this disclosure.

[0213] Unless otherwise specified, when ordinal numbers such as "first", "second", "third", etc. are used in this document to describe the same object, they only indicate different instances of the same type of object, and are not intended to imply that the object being modified must have a chronological order, spatial arrangement, hierarchical order, priority, or any other form of specific order.

[0214] In the following claims and throughout this specification, the terms "comprising", "comprised of", "which comprises", and similar expressions are, unless otherwise clearly specified, open-ended terms, meaning "including at least the recited element / feature, but not excluding other elements / features". Thus, the terms "comprising" and similar terms, if used in a claim, should not be construed as limiting the apparatus or element or step listed thereafter. For example, the scope of the expression "an apparatus comprising A and B" should not be limited to an apparatus consisting only of elements A and B. Unless otherwise clearly specified, the terms "including", "which includes", "that includes", and similar expressions used in this document are also open-ended terms, meaning "including at least the recited element / feature after the term, but not excluding other elements / features". Thus, the term "including" is synonymous with "comprising", meaning "including".

[0215] The term "exemplary" as used in this document means providing an example, rather than indicating quality. That is, an "exemplary embodiment" is an embodiment provided as an example, and not necessarily an embodiment of exemplary quality. Similarly, terms such as "for example" are used in this specification.

[0216] When the term "carbon-based" is used in this specification for the electrodes of SMD EDLC devices, it is a broad term used to describe one or more specific components of the electrodes. The components can include one or more of the following: carbon particles, such as activated carbon particles, carbon black particles (whether amorphous or not), or carbide-derived carbon particles, either alone or in combination; graphene; carbon nanotubes; carbon fibers; carbon foam; carbon aerogel; and similar materials. The components can also include a mixture of types and / or grades of such carbon-based materials. For example, the components of carbon particles can include a predetermined combination of similar types of components, such as high-surface-area carbon particles (activated carbon) and high-conductivity carbon particles (carbon black). As another example, the components of carbon particles can include a predetermined combination of different types of components, such as high-surface-area carbon particles (activated carbon) and carbon nanotubes. In some embodiments, the carbon-based electrodes include 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) in the electrode. It should also be understood that in other embodiments, binder-free electrodes are used.

[0217] An important characteristic of an SMD EDLC device is its DC capacitance I, measured in Farads (F). The DC capacitance is measured by drawing a constant current (I D ) from a fully charged EDLC device and measuring the time (T D ) required to discharge from a first DC voltage (V1) to a second voltage (V2). The DC capacitance C of a given EDLC device is then calculated according to the following formula:

[0218]

[0219] For similarly manufactured SMD EDLC devices, the measured DC capacitance will vary between devices. Typically, the acceptable manufacturing tolerance for DC capacitance is ±20% of the rated capacitance value of the device, although some production runs require tighter tolerances. In further production runs, the acceptable tolerance is ±30% of the rated capacitance value of the device.

[0220] Another important characteristic of an SMD EDLC device is its equivalent series resistance (ESR), measured in Ohms (Ω). The ESR of a given EDLC device can be estimated using the actual impedance of the device measured at 1 kHz using the AC current method.

[0221] In this specification, the term "liquid" is used to describe one or more elements, compounds, materials, or other substances. Unless otherwise specified, the term "liquid" in this specification is intended to mean that the described element, compound, material, or substance has a state that is between the freezing point and the boiling point of the corresponding element, compound, material, or substance.

[0222] Any numerical range recited in this specification is intended to include all sub-ranges subsumed therein. For example, a range “from x to y” or “between x and y” is intended to include all sub-ranges between x and y as well as the endpoints x and y. BRIEF DESCRIPTION OF THE DRAWINGS

[0223] Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0224] Figure 1 is a perspective view of a first exemplary EDLC device;

[0225] Figure 2 is a side view of the EDLC device mounted to a PCB Figure 1 ;

[0226] Figure 3 is Figure 1 the rear view of the EDLC device;

[0227] Figure 4 is Figure 1 the bottom view of the EDLC device;

[0228] Figure 5 is Figure 1 the plan view of the EDLC device;

[0229] Figure 6 is Figure 1 the bottom perspective view of the EDLC device, prior to being fitted with a plastic base, the terminals of which are formed to hold the base to the housing in a limiting manner;

[0230] Figure 7 is Figure 1 the perspective view of the capacitor element of the EDLC device, in which the radially outer ends of the separator and the electrodes are shown in a partially unfolded state;

[0231] Figure 8 is Figure 1 the perspective view of one terminal of the EDLC device;

[0232] Figure 9 is Figure 8 the rear view of the terminal;

[0233] Figure 10 is Figure 1 the perspective view of the sealing element in the form of a rubber cap of the EDLC device;

[0234] Figure 11 is an enlarged cross-sectional view showing Figure 7 the adjacent edges of a single winding of the electrodes and the separator in the element;

[0235] Figure 12is a perspective view of the housing of a second exemplary EDLC device;

[0236] Figure 13 is a perspective view of the housing aligned with the assembled capacitor element and the lid of the second exemplary EDLC device; Figure 12 ;

[0237] Figure 14 is a perspective view of the assembled capacitor element and the lid housed within the housing of; Figure 12 ;

[0238] Figure 15 is a perspective view of the housing of after a first forming operation; Figure 12 ;

[0239] Figure 16 is a perspective view of the housing of after a second forming operation; Figure 12 ;

[0240] Figure 17 is an enlarged cross-sectional view taken along section line 17-17 of; Figure 16 ;

[0241] Figure 18 is a flow chart showing a method of manufacturing an SMD EDLC device of; Figure 1 ;

[0242] Figure 19 is a table of performance characteristics of an exemplary embodiment; and

[0243] Figure 20 is a schematic diagram (not to scale) of the thermal curve of the housing of an SMD EDLC.

[0244] The above figures are provided to illustratively show the features included in the described specific embodiments, and these features are not necessarily to scale. Detailed Description

[0245] Referring to, there is shown a double electric layer capacitor (EDLC) device 1 for reflow soldering to a printed circuit board (PCB) 2. The device 1 includes a substantially cylindrical thin-walled ductile aluminum housing 3 that extends along a housing axis 4 between an open end 5 and a closed end 6. The housing 3 has high thermal conductivity, and as best shown in, the housing 3 defines a substantially circular opening 7 adjacent to the end 5 and a substantially cylindrical cavity 8 that is remote from the opening and extends along the axis 4 and terminates at the end 6. Figures 1 to 7 ; Figure 6 The substantially cylindrical capacitor element 9 shown is complementarily received within the cavity 8 and includes two elongated porous double-sided high surface area carbon-based electrodes 11 and 12. As shown in, Figure 7 ; Figure 6As best shown, the separators, in the form of two elongated paper-based separator sheets 13 and 14, are alternating and helically wound together with the electrodes 11 and 12. Sheets 13 and 14 hold the electrodes 11 and 12 in a spaced-apart and opposed configuration. The electrolyte impregnates the porous electrodes 11 and 12 and the sheets 13 and 14 and is contained within the cavity 6 for allowing ionic conduction between the electrodes 11 and 12. The electrolyte has a freezing point below 0 °C and a boiling point above 200 °C at 1 atmosphere, which will be described in further detail below. A sealing element in the form of an integral substantially cylindrical butyl rubber cap 15 extends over and seals the opening 7. In Figure 8 and Figure 9 one of two highly conductive, metal-like terminals 17 and 18 is shown in more detail. In use, each of the terminals 17 and 18 extends 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 as Figure 6 best shown, the terminals 17 and 18 extend through the opening 7 such that the second ends 20 can be used for electrical connection to the PCB 2.

[0246] In the described embodiment, the element 9 is pre-assembled before being disposed within the cavity 8 and is helically wound along the winding axis. The winding axis is also the imaginary axis of the substantially cylindrical element 9. Once the element 9 is received within the cavity 8, the winding axis is substantially aligned with the axis 4. Similarly, the substantially cylindrical cap 15 includes an axis which, in the assembled device 1, is also substantially aligned with the housing axis. Thus, for the exemplary embodiment described in this specification, the housing axis, the winding axis, the imaginary axis of the element 9, and the axis of the cap 15 are considered to be the same in the final assembled EDLC device and are all labeled with the reference numeral 4 in the drawings. However, it will be understood that these different axes are functionally independent and only effectively directly correspond when the relevant EDLC device is assembled.

[0247] In the absence of an express contrary indication, the term "substantially", when used in this specification to modify a qualitative characteristic of an object, means that the characteristic is essentially as described, and any deviation from the ideal value of the characteristic is non-substantial in terms of the actual performance of the object. By way of example, component 9 was described above as "substantially cylindrical", which indicates that component 9 may not provide: a precisely cylindrical outer sidewall due to the helical winding characteristics of component 9; and two completely flat circular ends due to the different axial lengths and degrees of overlap of the helical winding assemblies included within component 9. However, for practical applications in SMT devices, component 9 can be considered cylindrical. Further, in the absence of an express contrary indication, the term "substantially", when used in this specification to modify a quantitative characteristic of an object, means that the characteristic is essentially as described, and any deviation from the specified amount is ±5%, ±4%, ±3%, ±2%, and ±1%.

[0248] Although one or more embodiments are described with reference to one or a combination of specific manufacturing steps, those skilled in the art will understand that non-SMT cylindrical EDLC devices are known and the manufacture of such devices is also known. When determining the specific manufacturing steps for an embodiment, those skilled in the art may select known manufacturing steps other than those described in this specification that are most suitable for the specific embodiment; or combinations of manufacturing steps, in the same or a different order, to replace or supplement those described in this specification.

[0249] In other embodiments, the separator includes a single sheet that is folded back on itself to define two sheets that are integrally connected along the fold line. One of the electrodes is placed between the two sheets, while the other electrode is placed against the outer side of one of the sheets. The resulting stack is then helically wound together to define a substantially cylindrical capacitor element 9. In a further embodiment, the two sheets are different, for example, the axial width of one sheet is greater than the axial width of the other sheet. As another example, in one embodiment, perpendicular to axis 4, one sheet is longer than the other sheet, and when helically wound, one sheet extends further circumferentially to define the radially outer surface of element 9.

[0250] Device 1 has a rated voltage of 3 volts, a capacitance of 3.4 farads, and an ESR of 83 mΩ. Other embodiments provide different combinations of rated voltage, capacitance, and ESR.

[0251] The housing 3 includes a substantially cylindrical thin-walled ductile sidewall 25 extending between ends 5 and 6, and a substantially planar and circular thin-walled sidewall 26 extending through end 6 and integrally formed with the sidewall 25. Although the housing 3 is initially formed with a substantially axially consistent sidewall 25, during the manufacture and assembly of the device 1, the sidewall 25 is subjected to two separate forming operations which change the shape of the sidewall 25 from its initial regular cylindrical shape. The first of these forming operations occurs after the assembly combination of the element 9 and the cover 15 is inserted into the cavity 8, where the element 9 is adjacent to end 6 and the cover 15 is adjacent to end 5. The first forming operation involves the progressive plastic deformation of the sidewall 25 to include a substantially uniform and continuous circumferential concave channel 27 which is adjacent to end 5 and extends radially inwards into the axial gap between the element 9 and the cover 15. The channel 27 defines a complementary convex structure within the cavity 8 which partially defines the sealing surface for the cover 15 within the housing 3. The form and function of the sealing surface are described in more detail below with reference to another exemplary embodiment of the present invention.

[0252] In a further embodiment, the element 9 includes more than two electrodes and a diaphragm for maintaining the required physical isolation between all the electrodes. For example, in some embodiments, four electrodes are helically wound together in the element 9, where two are electrically connected to the terminal 17 to define a composite electrode 11, and the other two are electrically connected to the terminal 18 to define a composite electrode 12. In other exemplary embodiments, the device 1 includes two additional terminals for allowing separate external electrical connection to each of the four electrodes. Those skilled in the art will appreciate that the element 9 can include more than four electrodes.

[0253] As Figure 10 best shown, the cover 15 includes a substantially circular inner surface 29 and a substantially circular outer surface 30, and a substantially cylindrical and circumferentially continuous outer sidewall 31 extending between the surfaces 29 and 30. The cover 15 also includes two spaced-apart similar holes 33 and 34 which extend between the faces 29 and 30 and receive and sealingly engage the corresponding terminals 17 and 18 located midway between ends 19 and 20 in an interference fit manner. The cover 15 together with the terminals 17 and 18 defines a compression seal which has a sealing path which, in this embodiment, is substantially equal to the axial distance between the faces 29 and 30. In the static state as Figure 10 shown, the distance between the faces 2 and 30 is 3 mm. However, when the cover 15 is installed in the housing 3, the face 31 is substantially uniformly compressed radially inwards around its circumference, which has the effect of increasing the axial dimension of the cover 15 and thus increasing the sealing path length between the faces 29 and 30. In other embodiments, the cover 15 has different dimensions and provides different sealing path lengths.

[0254] In a further embodiment, the element 9 is initially received within the cavity 8 without the cover 15. After a first forming operation, the cover 15 is then axially advanced such that the ends 20 of the terminals 17 and 18 are received by and extend through the respective holes 33 and 34, and the cover 15 is received within the cavity 8.

[0255] After the first forming operation, with the cover 15 disposed within the cavity 8, the outer radial periphery of the face 29 abuts a convex structure defined by the channel 27 within the cavity 8. The partially assembled device 1 then undergoes a second forming operation which gradually plastically deforms the ends 5 of the side walls 25 to define a retaining structure for the cover 15. More specifically, the retaining structure in this embodiment is a continuous circumferential flange 28 that extends radially inwards at the ends 5 of the housing 3. During the formation of the flange 28, it is pressed into biasing engagement with the radial periphery of the face 30. The cover 15 elastically deforms and is biased into the sealing engagement with the flange 28. Additionally, the cover 15 is clamped into engagement with the housing 3 between the flange 28 and the convex structure within the cavity 8 defined by the channel 27. The side wall 31 of the cover 15 also seals against the inner surface of the side wall 25 which extends between the flange 28 and the convex structure within the cavity 8 defined by the channel 27. Thus, the housing 3 defines a sealing surface against which the cover 15 abuts to effect a compression seal. The compression seal includes a sealing path that is longer than the axial distance between the faces 29 and 30.

[0256] Although the first forming operation and the second forming operation are described as two discrete operations, those skilled in the art will understand that they may be carried out in rapid succession at a single forming station. In some embodiments, the forming operations are synchronous (since the operations overlap in time), while in further embodiments, the forming operations are substantially simultaneous.

[0257] The above description focuses on the nature of the forming operations. It should be understood that there are many steps between the first operation and the second operation in addition to the first operation and the second operation, and these steps have been omitted for the sake of clearly presenting the details of the above-described forming operations.

[0258] As Figure 8 and Figure 9 Best shown, the end 19 of the terminal 17 includes two relatively large surface area faces 37 and 38. The end 19 of the terminal 17 is formed of aluminum, while the end 20 is formed of copper and includes a tin coating to facilitate good electrical contact with the associated contact pads on the PCB 2 during and after a reflow process. In other embodiments, different coatings are used, such as a gold coating. In a further embodiment, the ends 19 and 20 are formed of different conductive materials.

[0259] In use, the face 37 of the relatively large surface area of the terminal 17 abuts against the electrode 11 to define a relatively large electrical contact patch with the electrode. Then, before the sheets 13 and 14 are helically wound with the electrodes 11 and 12, the end 19 is fixedly physically and electrically connected to the electrode. In the present embodiment, the fixing of the terminal 17 to the electrode 11 is accomplished by a machine by means of riveting, wire stitching, etc. As will be described in more detail below, the electrodes 11 and 12 include a porous carbon base layer and an aluminum current collector. In the said embodiment, each terminal is connected such that a direct electrical contact is achieved between the terminal and the current collector of the corresponding electrode.

[0260] Once the helical winding occurs, the face 38 of the terminal 17 abuts against the separator sheet 13 and is electrically insulated from the adjacent electrode 12. The terminal 17 includes a symmetry axis 39 which, following the helical winding of the electrodes 11 and 12 with the sheets 13 and 14, is parallel to the axis 4 and radially offset from the axis 4. The terminals 17 and 18 are fixedly connected to the corresponding electrodes 11 and 12 such that after the helical winding of the electrodes and the separator, the terminals are substantially radially opposite and the corresponding axes 39 are substantially radially equidistant from the axis 4. In one embodiment, the relative radial positions of the terminals are different from those described above. For example, in one embodiment, the terminals are offset from the axis 4 by different distances. Additionally, in another embodiment, the terminals are circumferentially offset by an angle other than 180°.

[0261] The terminal 17 includes a mounting structure located midway between its ends 19 and 20 in the form of a ferrule 41 integrally formed with the end 19. The ferrule includes a substantially cylindrical outer surface 42 for defining a continuous sealing surface and a cavity (not shown) for receiving the end 20 and physically and electrically fixedly engaging with the end 20. Once the end 20 is received within the cavity, the physical and electrical fixed engagement between the ferrule 41 and the end 20 is effected by inserting a dose of a fixing compound into the cavity. In some embodiments, the fixing compound is a conductive epoxy resin, while in other embodiments, different fixing compounds such as solder, etc. are used. In other embodiments, the ends 19 and 20 are fixedly connected by ultrasonic welding.

[0262] In some embodiments, the face 42 of the ferrule 41 is non-cylindrical to form a longer sealing path with the cover 15. For example, in one embodiment, the profile of the face 42 has circumferentially and / or radially extending grooves or other structures to provide a curved sealing path with the cover 15. That is, once the terminals 17 and 18 are received within the corresponding holes 33 and 34, the cover 15 automatically elastically deforms within and around the grooves or other structures to sealingly engage with the face 42 and define a sealing path longer than the axial distance between the faces 29 and 30.

[0263] The end 20 of terminal 17 includes two opposite faces 45 and 46 with relatively large surface areas, which are connected by a narrower face 47. Applying a force perpendicular to faces 45 and 46 causes the end 20 to plastically deform from Figure 6 , Figure 8 and Figure 9 the first position shown to Figures 1 to 5 the second position shown (with particular reference to Figure 4 ).

[0264] Although only terminal 17 has been explicitly described above, it should be understood that terminal 18 is a similar terminal and shares the same structural and functional characteristics.

[0265] Device 1 includes a non-conductive rigid high-temperature polymer plastic base 51, the shape of which facilitates machine handling and placement of device 1 on PCB 2. Base 51 is also used to hold the ends 20 of terminals 17 and 18 substantially perpendicular to axis 4 and substantially parallel to the adjacent face of PCB 2 in use. This facilitates the use of device 1 in the reflow process as it is configured for machine handling and placement on PCB 2 such that the ends 20 are parallel to and cover corresponding generally horizontally extending pads on PCB 2, and terminals 17 and 18 are physically and electrically connected to said pads.

[0266] Base 51 is integrally formed and includes two circular and spaced-apart holes 53 and 54 which are used to accommodate the ends 20 of the respective terminals 17 and 18 when the end 5 of housing 3 engages with the base. On its underside, base 51 includes four projecting and spaced-apart mounting structures 55 for abutting against the adjacent surface of PCB 2 in use.

[0267] By comparison, for example Figure 4 and Figure 6 it will be noted that after the terminals 17 and 18 are accommodated in holes 53 and 54, the ends 20 of the terminals plastically deform perpendicular to faces 45 and 46 such that the ends 20 extend substantially perpendicular to ends 19 and axis 39, thereby holding base 51 in engagement with end 5 in a limiting manner. In addition, the deformation of the ends 20 of terminals 17 and 18 causes these ends to extend away from each other along a common line, and faces 46 and 45 can be respectively used to abut against two corresponding spaced-apart pads 56 on PCB 2. (See specifically Figure 2)。These pads extend along the upper surface 2a of the PCB 2, and each provides a relatively large upward-facing surface area that can be used for contact with the ends 20 of the respective terminals 17 and 18. In use, the faces 45 and 46 of the ends 20 extend substantially parallel to the adjacent upper surface 2a of the PCB 2 and the exposed upper surface of the respective pad 56. The relatively large and exposed upper surface of the pad 56 accommodates the tolerances when the device 1 is machine-mounted onto the PCB 2 and helps to establish a good electrical and physical connection between the ends 20 and the corresponding pads after the PCB 2 and the device 1 pass through the reflow soldering furnace together.

[0268] It should be understood that the PCB 2 can be single-sided, double-sided, single-layer, multi-layer or other styles, depending on its design. The PCB 2 will also include a predetermined arrangement of tracks, pads, vias and other structures for providing the required conductive paths and connection points for the required electronic components to be mounted on the PCB. Although it is mentioned in this specification that the PCB 2 has two pads 56, this is done to simplify the disclosure of the implementation, rather than implying that the PCB 2 only needs to have two pads.

[0269] As Figure 3 As best shown, the base 51 has a first face 51a (the lower face in use) opposite to the surface 2a and a second face 51b (the upper face in use) opposite to the face 51a. In use, the opening 7 is opposite to the face 51b.

[0270] It will also be noted that, particularly from Figure 4 it can be seen that the base 51 includes two continuous linear channels 57 and 58, along which the ends 20 of the respective terminals 17 and 18 extend. The channel 57 extends from the hole 53 in a first direction and terminates at the first side of the base 51, while the channel 58 extends from the hole 54 in a second direction opposite to the first direction and terminates at the second side of the base 51 opposite to the first side. The ends 20 are partially nested within the respective channels 57 and 58 and extend beyond the respective sides of the base 51. In other embodiments, the channels 57 and 58 are omitted. In one embodiment, either or both of the channels 57 and 58 extend through the base 51 to define holes for the respective elongated end openings.

[0271] In one embodiment, the ends 20 extend in the same direction, although spaced apart. In one embodiment, the ends 20 extend away from each other, but not along a common line. In other embodiments, the ends 20 generally extend away from each other.

[0272] In one embodiment, the functions of holes 53 and 54 are implemented by a single larger hole. In one embodiment, base 51 includes a conductive portion (not shown) in the form of a conductive pad which, in use, defines an extension of corresponding end 20. In one embodiment, the conductive portion extends partially along face 51a and is adjacent to end 20 in use. In one embodiment, the conductive portion extends along respective channels 57 and 58. The conductive portion provides a greater surface area for solder for terminals 17 and 18 - more specifically, end 20 - in order to effect the required electrical and physical connection to PCB 2.

[0273] Base 51 is non-conductive and is capable of withstanding the thermal shock applied during the reflow process without experiencing any significant physical deformation or other structural degradation. In the described embodiment, base 51 is made substantially of polyphthalamide (PPA). In other embodiments, other materials or combinations of materials may be employed, including one or more of polyether ether ketone (PEEK), liquid crystal polymer (LCP), and similar materials which remain stable at temperatures greater than 200°C.

[0274] Specific reference is made to Figure 7 , in which electrode 11 in the deployed state is substantially rectangular and extends perpendicular to axis 4. Electrode 11 includes two substantially parallel elongate edges 61 and 62 which are spaced apart along axis 4. Electrode 11 includes a radially outer end 63 having an axially extending edge 64 which is perpendicular to and connected to edges 61 and 62. Similarly, electrode 12 in the deployed state is substantially rectangular and extends perpendicular to axis 4. Electrode 12 includes two substantially parallel elongate edges 65 and 66 which are spaced apart along axis 4, substantially the same as edges 61 and 62. Additionally, when helically wound to form element 9, edges 61 and 62 are adjacent to and cover corresponding edges 65 and 66. Electrode 12 includes a radially outer end 67 having an axially extending edge 68 which is perpendicular to and connected to edges 65 and 66. In the helically wound structure, edges 64 and 68 are joined since in the outermost helix of the electrodes of element 9, edges 64 and 68 substantially overlap each other circumferentially.

[0275] The sheet 13 in the deployed state is substantially rectangular and elongated, and includes two substantially parallel elongated edges 69 and 70, which are spaced apart along the axis 4 by a distance greater than the axial spacing between the edges 61 and 62, and thus greater than the axial spacing between the edges 65 and 66. In addition, the edge 69 axially extends beyond the edges 61 and 65, while the edge 70 axially extends beyond the edges 62 and 66 in a direction opposite to the edge 69. The sheet 13 includes a radially outer end 71 having an axially extending edge 72, which extends perpendicular to and is connected to the edges 69 and 70. When helically wound to form the element 9, the edge 72 circumferentially extends beyond the edges 64 and 68. Similarly, the sheet 14 in the deployed state is substantially rectangular and elongated, and includes two elongated edges 73 and 74, which are spaced apart along the axis 4 to respectively cover the edges 69 and 70. The sheet 14 includes a radially outer end 75 having an axially extending edge 76, which is perpendicular to and connected to the edges 73 and 74. In the helically wound structure, the edge 74 circumferentially extends beyond the end 72 and is fixed to itself with an adhesive tape 77. In some embodiments, the edge 76 extends beyond the edge 72 by more than one turn of the sheet 14 around the element 9, and in some embodiments by more than multiple turns of the sheet 14. The additional windings of the sheet 14 radially outside the element 9 will provide one or more of the following: increasing frictional engagement at the periphery of the element 9 and thus increasing the structural integrity of the element 9; and increasing the electrical insulation from unintended contact of the electrode edge with the sidewall 26 or other conductive elements.

[0276] Figure 11 Further details of the elongated edges of a single winding of the helically wound element 9 are shown. More specifically, with reference to the figure, the electrode 11 includes a first carbon base layer 81 with a thickness of 20 microns, a second carbon base layer 82 with a thickness of 20 microns, and an intermediate aluminum sheet current collector 83 with a thickness of 20 microns, and the carbon base layers 81 and 82 are mounted and electrically connected to the current collector 83. Similarly, the electrode 12 includes a third carbon base layer 85 with a thickness of 20 microns, a fourth carbon base layer 86 with a thickness of 20 microns, and an intermediate aluminum sheet current collector 87 with a thickness of 20 microns, and the layers 85 and 86 are mounted and electrically connected to the current collector 87. Those skilled in the art will note that the edges 61 and 65 substantially axially overlap, and the ends 69 and 73 are located axially outside the edges 61 and 65. In addition, during the helically winding operation of forming the element 9, the components wound into a helix are held under tension to ensure a tight and firm fit and to contribute to the structural integrity of the finally formed element. For some separator sheet materials during the helical winding operation, this tension combined with the material properties of the sheet causes the axial outer edges to radially deform inwardly towards the axis 4, thereby providing partial or complete overlap of the edges 61 and 65 through the sheets 13 and 14 respectively. In Figure 11, full overlap is shown. For other diaphragm sheet materials or lower applied tension, deformation may not occur automatically. In such embodiments, angled rollers or guides can be used in the winding operation to mechanically cause deformation or other deflection of sheets 13 and 14.

[0277] Those skilled in the art will appreciate that although Figure 11 Only the edges 69 and 70 of the diaphragms 13 and 14 are shown, but the edges 70 and 74 achieve a corresponding effect. Figure 11 Only a single winding of element 9 is shown in FIG. 1 , but it will be appreciated that the other windings of sheets 13 and 14 in element 9 can be similarly formed.

[0278] In other embodiments, the carbon layer has a thickness other than 20 microns. Typical thickness ranges for such electrodes are in the range of about 10 microns to 200 microns, although thicknesses outside of this range may also be used.

[0279] The diaphragm sheets used in the above-described embodiments are made of nonwoven fibers, more specifically, sheets each containing cellulose fibers. Sheets 13 and 14 each have a thickness of about 30 microns. For the selected diaphragm sheets, it has been found that this thickness is suitable for spirally wound devices, wherein tension is applied when the electrodes and diaphragm sheets are wound together. Since the diaphragm sheets are very porous, if they are made too thin, they will easily cause short circuit connections between the electrodes, which will make the EDLC device defective. In other embodiments, when a smaller tension is used when winding the capacitor element, or when a higher manufacturing failure rate can be tolerated, a thinner diaphragm can be used.

[0280] In some embodiments, the paper substrate sheets 13 and 14 include a polymer to provide either or both of: additional puncture resistance to the sheets and additional mechanical integrity to the element 9 when subjected to thermal expansion during and after the reflow process. This is particularly advantageously applied to those embodiments where the selected electrolyte would tend to soften or otherwise weaken a paper-only sheet during the high temperatures of the reflow process.

[0281] In other embodiments, sheets 13 and 14 are made of different materials or material combinations. Further, in one embodiment, sheets 13 and 14 are made of different materials or material combinations that are different from each other. For example, in one embodiment, sheet 14 extending circumferentially around the radial periphery of element 9 is thicker than sheet 13 to provide additional uniformly applied mechanical strength around the periphery.

[0282] In one embodiment, sheets 13 and 14 are made primarily of PTFE. Generally, such sheets can be thinner than paper-based sheets and have relatively high puncture resistance even when stretched during the winding of element 9. Preferably, such sheets include a surface treatment to increase wettability with the electrolyte.

[0283] In other embodiments, different thicknesses are used for the separator sheets. In an exemplary embodiment, the thickness of the paper-based sheet is between 20 microns and 30 microns. In one embodiment, the sheet has a thickness of 30 microns to 40 microns. In one embodiment, the sheet has a thickness of 40 to 50 microns. In yet another embodiment, the sheet has a different thickness.

[0284] In the above embodiments, sheets 13 and 14 are formed substantially of non-woven cellulose fibers. However, in other embodiments, sheets 13 and 14 are formed substantially of other fibers or non-fiber 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 those embodiments using PTFE sheets 13 and 14, these sheets are preferentially surface-treated to reduce the reactivity of these sheets with the electrolyte and improve wettability.

[0285] In the described embodiment, the housing 3 is formed substantially entirely of aluminum alloy, and the side wall 25 has a substantially uniform wall thickness of about 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 other 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 considering the expected internal pressure within the cavity 8 during the reflow process and the expected mechanical shock to be endured during the subsequent operation of the device 1. The amount of material required to construct the housing 3 must also be considered. Another consideration in selecting the side wall thickness is to provide the required plastic deformation ability for the side wall 25 to define the sealing structure and the retaining structure of the sealing element. In one embodiment, the housing 3 and the side wall 25 are formed of stainless steel.

[0286] In the above embodiment, the side wall 25 of the housing 3 axially extends 12.6 mm between the ends 5 and 6 and has an outer diameter of 12.5 mm. Before undergoing two forming operations, the side wall 25 of the housing 3 axially extends 13.5 mm between the ends 5 and 6.

[0287] The wall thickness of the side wall 26 is 370 microns. Additionally, the side wall 26 includes one or more exhaust structures (not shown), which are integrally formed channels for preferential rupture when the internal pressure within the cavity 8 exceeds a predetermined threshold. In the described embodiment, the exhaust structures are two generally intersecting channels that extend radially within the side wall 26. Once the pressure on the side wall reaches 20 kg / cm -2 to 30 kg / cm -2 , these channels cause the side wall 26 to rupture. The reduced wall thickness of the side wall 26 adjacent to the channels is approximately 70 microns. In other embodiments, different exhaust structures or different configurations of exhaust structures are used. Additionally, when different rupture pressures are desired, deeper or shallower channels are used.

[0288] In other embodiments, the side wall 26 has a different side wall thickness. Additionally, in further embodiments, the side wall 26 is not substantially flat and includes a convex outer surface for providing additional structural strength to the housing 3, or alternatively, includes a concave outer surface for providing predetermined deformation characteristics to the housing 3 under load.

[0289] It is understood that when the device 1 is mounted to the PCB 2, the side walls 25 and 26 are exposed to the surrounding atmospheric conditions during the reflow process and during the subsequent operating life of the device 1. Additionally, the thin-walled side walls 25 and 26 are formed substantially only of aluminum alloy, which has a thermal conductivity greater than 100 W / (m·K) at room temperature. -1 K -1 Therefore, for a given reflow process, the internal components within the cavity 8 (especially the capacitor element 9) will experience a higher maximum temperature than in the case of prior art EDLC devices having adiabatic encapsulations and / or housings. Conversely, after the reflow process, the device 1 will reach the ambient temperature faster than prior art devices. Taking this into account, the combined selection of the internal components of the device 1 is not for continuous high-temperature performance, but rather to fully withstand the one-time thermal shock during the reflow process (whether including a single pass or multiple passes through the reflow oven), while still providing a predetermined operating life at a maximum operating temperature that is well below the maximum temperature experienced during the reflow process. Although the maximum temperature may be higher than the typical case of prior art SMD EDLC devices, the thermal shock experienced by the internal components within the device 1 during the reflow process should be maintained at that maximum temperature for a shorter duration.

[0290] In one embodiment, the side wall 25 is formed of a material having a thermal conductivity of 50 to 100 W / (m·K) at room temperature. In one embodiment, the side wall 25 is formed of a material having a thermal conductivity of 100 to 150 W / (m·K) at room temperature. -1 K -1 In one embodiment, the side wall 25 is formed of a material having a thermal conductivity of 100 to 150 W / (m·K) at room temperature. -1 K -1formed of a material with thermal conductivity. In one embodiment, sidewall 25 is formed of a material having a thermal conductivity of 150 to 200 Wm -1 K -1 at room temperature. In one embodiment, sidewall 25 is formed of a material having a thermal conductivity of 200 to 250 Wm -1 K -1 at room temperature.

[0291] In other embodiments, different-sized housings are used to complementarily accommodate commensurately sized electrodes.

[0292] Electrode 11 of device 1 axially extends 7 mm between edges 61 and 62, while electrode 12 also axially extends 7 mm between edges 65 and 66. Sheet 13 axially extends 8 mm between edges 69 and 70, while sheet 14 also axially extends 8 mm between edges 73 and 74. Electrodes 11 and 12 are axially centered with respect to each other and have 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 can be obtained by using different electrode sizes, different electrode materials (with different surface areas), different thicknesses of the electrodes and separator sheets, and different lengths of the electrodes and separator sheets. In the case where the sizes of electrodes 11 and 12 and sheets 13 and 14 are different from those used in the current embodiment, or the number of windings of the components forming element 9 is different from the number used in the current embodiment, it may be necessary to use a housing with a different size from housing 3.

[0293] The outsides of sidewalls 25 and 26 are pre-coated with a thin paint layer, which is cured to provide an electrical insulation barrier. An additional pre-assembly step in this embodiment is to adhere a paper gasket with a thickness of 30 micrometers to the inner surface of sidewall 26. This is done to reduce the risk of establishing any accidental electrical contact between sidewall 26 and electrodes 11 and 12 in element 9. In the said embodiment, a paper sheet of the same material as sheet 13 is used.

[0294] In the said embodiment, layers 81, 82, 85, and 86 are substantially the same and include similar compositions. In particular, each layer includes 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 carbon particles within the same layer; and the adhesion of each carbon base layer to the adjacent current collector.

[0295] The activated carbon particles in the described embodiments are selected to have a pore volume greater than 50% with a pore diameter greater than 2 nm to better bind an electrolyte having a higher viscosity than more conventional electrolytes using organic liquids such as acetonitrile. These activated carbon particles are referred to as mesoporous activated carbon particles. It has been found that using such mesoporous carbon particles in the embodiments not only improves the electrical performance of the EDLC device with a relatively viscous electrolyte, but also facilitates the manufacture of the EDLC device because the carbon particles are more easily wetted by the electrolyte and thus contribute to greater predictability during the manufacturing process.

[0296] It will be appreciated that the pore diameter of the carbon particles mentioned in the previous paragraph is different from the porosity of the layers 81, 82, 85, and 86 themselves. More specifically, the device 1 utilizes porous electrodes, each porous electrode comprising a mixture of active particles. The active particles in the described embodiments are activated carbon particles having pores and conductive particles in the form of carbon black particles. While all active materials contribute to the high surface area between the electrode and the adjacent electrolyte, this is especially true for the activated carbon particles. The electrolyte penetrates into the pores of the porous electrode and the activated carbon particles. The Helmholtz double layer is formed not only by the external carbon particles contained within the electrode, but also by the subsurface carbon particles within the electrode. This penetration or wetting of the electrode by the electrolyte contributes to a higher volumetric capacitance through the EDLC device as compared to a conventional electrolytic capacitor. To obtain the highest capacitance in a given volume of an EDLC device, microporous activated carbon particles are typically used because these particles generally provide the highest surface area per unit volume of particles. The inventors have found that for those embodiments using a more viscous electrolyte, instead of or in addition to microporous carbon particles, it may be advantageous for the electrode to also include mesoporous activated carbon particles. These mesoporous carbon particles generally provide a smaller surface area per unit volume than microporous carbon particles and thus reduce the capacitance provided by the electrode. However, it has been found that the larger pores of the mesoporous particles reduce the ionic resistance of the electrolyte and thus improve the performance of the EDLC device mainly by helping to reduce the ESR of the device. This effect is particularly pronounced in electrolytes with a higher viscosity.

[0297] Mesoporous particles are particles in which more than 50% of their pore volume has a pore diameter greater than 2 μm. While in the above-described embodiments, 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.

[0298] In one embodiment, the viscosity of the electrolyte at room temperature is greater 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 an embodiment, the viscosity of the electrolyte at room temperature is in the following ranges respectively: 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. In one embodiment, the viscosity of the electrolyte at room temperature is less than ten times the viscosity of water at room temperature.

[0299] The binder in this specific embodiment includes carboxymethyl cellulose (CMC). However, in other embodiments, other binders that do not degrade significantly at 200 °C or higher are used. In one embodiment, the binder alternatively or additionally includes one or more of the following: salts of CMC (such as sodium carboxymethylcellulose); polytetrafluoroethylene (PTFE); salts of polystyrene sulfonate (PSS), such as Group I or Group II metal salts 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. These binders have been found to be relatively stable at elevated temperatures (such as the high temperatures encountered by the binder in a reflux process). Although such a binder may soften during reflux, the use of the cylindrical helically wound element 9 can maintain a more uniform pressure over the entire surface of the electrode, thereby better maintaining the shape and structure of layers 81, 82, 85, and 86. In a further embodiment, when the material of the electrode is selected such that sufficient structural integrity can be achieved without the use of a binder, the binder is omitted for one or both of adhesion and / or cohesion. For example, this can occur in some embodiments where the electrode includes a predetermined combination of carbon nanotubes and carbon particles. The use of the helically wound element 9 has been found to be well adapted to the use of binder-free electrodes because any potential structural weaknesses resulting from the omission of the binder are at least partially mitigated by the structural benefits obtained from the construction of the element 9. In other embodiments, different binder-free electrodes are used. Examples of other binder-free electrodes for EDLC devices include: vertically aligned carbon nanotubes grown directly on the current collector, entangled carbon nanotubes, and entangled carbon nanotubes with other high surface area carbon materials (such as activated carbon particles or graphene materials).

[0300] The electrolyte within the outer casing 3 consists of a neutral organic compound (such as a polar aprotic solvent) and an organic salt. The neutral organic compound contains an organic sulfone compound (such as sulfolane), and the organic salt includes: tetrafluoroborate salts of quaternary ammonium cations (such as tetramethylammonium, tetraethylammonium, tetrapropylammonium, tetrabutylammonium, 2-(methylthio)ethylammonium, spiro-bis-pyrrolidinium (SBP), N,N-dimethylpyrrolidinium, N-methyl-N'-propylpyrrolidinium, N,N'-dimethylimidazolium, N-methyl-N'-ethylimidazolium, or N-methyl-N'-propylimidazolium). The salt is present at a high enough concentration such that the freezing point of the electrolyte is reduced to less than or equal to 0 °C at 1 atmosphere of pressure.

[0301] In other embodiments, the neutral organic compound or solvent (such as a polar aprotic solvent) includes a carbonate (such as propylene carbonate (PC)) or a cyclic lactone (such as gamma-butyrolactone (GBL)). These neutral organic compounds / solvents are combined with the organic salt such that ionic conduction can occur within the electrolyte. Once such an organic salt contains a tetrafluoroborate anion. In one embodiment, the salt is present at a high enough concentration such that the boiling point of the resulting electrolyte is elevated to greater than or equal to 200 °C at 1 atmosphere of pressure. In one embodiment, the salt is present at a high enough concentration such that the boiling point of the resulting electrolyte is elevated to greater than or equal to 210 °C at 1 atmosphere of pressure. In other embodiments, the concentration of the salt is such that the boiling point of the resulting electrolyte is greater than or equal to 220 °C at 1 atmosphere of pressure. In an exemplary embodiment, the concentration of the salt is such that the boiling point of the resulting electrolyte is greater than or equal to 230 °C at 1 atmosphere of pressure. In a further embodiment, the concentration of the salt is such that the boiling point of the resulting electrolyte is greater than or equal to 240 °C at 1 atmosphere of pressure.

[0302] In one embodiment, the electrolyte includes 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 includes two or more carbonates. In an exemplary embodiment, the electrolyte includes a mixture of sulfones, such as a mixture of linear sulfones and cyclic sulfones. In another exemplary embodiment, the electrolyte includes a mixture of two cyclic sulfones. In another exemplary embodiment, the electrolyte includes a mixture of carbonates, such as a mixture of linear carbonates and cyclic carbonates. In another exemplary embodiment, the electrolyte includes a mixture of cyclic carbonates.

[0303] In a further embodiment, the electrolyte includes an ionic liquid. In yet another embodiment, the electrolyte includes a predetermined combination of an ionic liquid and a neutral organic compound or solvent. Exemplary neutral organic compounds or solvents include a combination of one or at least two of sulfolane, PC, and GBL.

[0304] The selection of the electrolyte for the current embodiment is based on a combination of multiple factors, such as the electrolyte having one or more of the following characteristics:

[0305] (a) The boiling point at 1 atmosphere is greater than or equal to 200 °C, which reduces the pressure increase within the housing during the reflux process;

[0306] (b) A relatively high ionic mobility for the selected operating temperature range of Device 1;

[0307] (c) Good temperature stability during thermal shock experienced during the reflux process;

[0308] (d) Low reactivity with the selected electrodes within the operating temperature range and during the thermal shock experienced during the reflux process, with particular consideration given to the potential reactivity of the electrolyte with the carbon-based layers, and more specifically, with any adhesives contained in these layers or any impurities commonly found in the carbon particles;

[0309] (e) Low reactivity with the selected separator within the operating temperature range and during the thermal shock experienced during the reflux process;

[0310] (f) A low transmission rate due to electrolyte vapor permeating through Cover 15 within the required operating temperature range and during the thermal shock experienced during the reflux process; and

[0311] (g) Low leakage from Cavity 8 due to advancement along the sealing path within the required operating temperature range and during the thermal shock experienced during the reflux process.

[0312] It has been found that for the SMD EDLC devices of the above embodiments that are subjected to a reflux process, it is preferable to select the electrolyte from those that are liquid at 1 atmosphere between at least 0 °C and 200 °C. It is understood that in some embodiments, the electrolyte may include an organic solvent and / or an organic salt having a specified freezing point above 0 °C. This occurs when such an organic solvent and / or organic salt effectively inhibits their freezing point in situ. For example, in one embodiment, the in situ freezing point of the electrolyte is inhibited below 0 °C due to one or both of the following two reasons: the concentration of the dissolved organic salt; and the high surface area of the activated carbon.

[0313] In a preferred embodiment, the adhesive is substantially insoluble when mixed in an electrolyte sample heated to 200 °C at 1 atmosphere. In some embodiments, Electrodes 11 and 12 do not include an adhesive, which may allow for a wider range of electrolytes to be used in the SMD EDLC device, as the reactivity of the adhesive with the electrolyte at the high temperatures encountered during the reflux process does not need to be considered.

[0314] As those skilled in the art will understand, the electrolyte provides a source of charged ions for the SMD EDLC device, and the charged ions migrate to the surface of the corresponding electrode to form a pair of Helmholtz layers in the device. In addition, it should be understood that using a high thermal conductivity housing for the SMD EDLC device, as occurs in the embodiments described herein, causes the electrolyte and other internal components of the EDLC device to reach a maximum temperature of about 200 °C to 240 °C during the reflow process, even if only for a short time. Therefore, an electrolyte is selected for Device 1 to withstand this temperature profile while still providing the desired lifetime performance. Some embodiments are designed for a reflow process that causes the electrolyte to be exposed to a maximum temperature above 240 °C.

[0315] It should be noted that Device 1 is a single-cell device. During normal use within the planned lifetime, the voltage that a single cell can maintain is called the cell voltage. Therefore, the rated voltage of Device 1 as a single-cell device is the same as the cell voltage of Device 1. The electrolyte used in Device 1 and other embodiments described in this specification is an organic electrolyte that allows the cell voltage to be higher than 2 volts.

[0316] In other embodiments, multiple such connected cells are used:

[0317] (a) In parallel - usually to reduce the overall ESR of the resulting device or to increase the overall capacitance of the resulting device relative to a single-cell device; and / or

[0318] (b) In series - usually to increase the operating voltage of the resulting device relative to a single-cell device.

[0319] Those skilled in the art will understand that an EDLC device using an aqueous electrolyte has a cell voltage of less than 2 volts. In contrast, an EDLC device of an embodiment using an organic electrolyte typically provides a cell voltage in the range of 2.3 to 4 volts. The maximum operating voltage of the SMD EDLC device is usually determined by the performance required by the device under the predetermined operating lifetime and operating conditions, because those devices with higher cell voltages usually experience accelerated aging characteristics.

[0320] The electrolyte used in the embodiments described in this specification is partially selected such that it does not generate excessive pressure in the housing 3 when Device 1 is subjected to the reflow oven temperature. This reduces the risk of electrolyte leakage from the housing during reflow due to: excessive stress and weakening of the seal; and cracking and failure of the housing. The electrolyte of one embodiment is selected to have a vapor pressure of less than 1 atm (1.013 bar or 101.3 Kpa) at 200 °C. In other embodiments, the corresponding electrolyte has a vapor pressure of less than 1 atm at the following temperatures: 210 °C; 220 °C; 230 °C; 240 °C; 250 °C; and 260 °C.

[0321] In one embodiment, the electrolyte is also selected to be chemically stable with respect to the reflow oven temperature that the device will experience. Additionally, the electrolyte is selected such that at the relevant reflow oven temperature, it is substantially insoluble, non-degrading, or non-binding to other components of the EDLC device, such as any adhesives, separators, current collectors, any carbon used in the electrodes, the housing, and the lid (or other sealing elements).

[0322] When evaluating whether the electrolyte is substantially insoluble, non-degrading, or non-binding to other components of the EDLC device, electrical tests performed before and after the device experiences the reflow process are considered in one embodiment.

[0323] As understood by those skilled in the art, the change in ESR is typically an increase, while the change in capacitance is typically a decrease. For some devices, the ESR decreases and / or the capacitance increases after the reflow process.

[0324] In one embodiment, the electrolyte comprises an organic salt that is liquid at room temperature, or a mixture of two or more organic salts that are 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 discrete solid salt at room temperature and is mixed with a neutral organic compound or solvent. This mixture provides, in part or in whole, an electrolyte that is an ionically conductive liquid within the temperature range required for the reflow process used to connect the SMD EDLC device to the PCB 2 and within the operating temperature range of the SMD ELDC device once so installed. The neutral organic compound or solvent used in one embodiment can be a liquid solid. However, when an organic solid is used, the organic solid is preferably heated and mixed with the organic salt, organic liquid, or liquid organic salt (ionic liquid) to form a eutectic-type mixture, where the melting point of the mixture is much lower than the melting point of the organic solid or the organic salt / organic liquid. In some embodiments, one or more organic liquids can be added, and in further embodiments, one or more organic salts can be added to form a eutectic-type mixture. The eutectic-type mixtures of the embodiments result in a liquid electrolyte at room temperature and typically at lower temperatures. In one embodiment, the freezing point of the eutectic-type mixture is below 0 °C. In one embodiment, the freezing point of the eutectic-type mixture is below -10 °C. In one embodiment, the freezing point of the eutectic-type mixture is below -20 °C.

[0325] The organic salt comprises a cation and an anion. In embodiments where the salt is liquid at room temperature (i.e., the salt is an ionic liquid), the salt can be used without mixing with a neutral organic compound or solvent, although it can be. 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, which is solid or liquid at room temperature. The organic compound or solvent is capable of or enhances the dissociation of the salt ions.

[0326] In one embodiment, the ionic liquid comprises a mixture of two or more salts, i.e., two or more different ionic liquids can be mixed or combined.

[0327] As described above, the salt component of the electrolyte consists of a cation and an anion. For an organic electrolyte in an EDLC device, it is preferred that there is only a weak interaction between the anion and the cation, such that the salt dissociates easily into the cation and the anion. For one embodiment, the selection of the salt also takes into account that the salt is stable enough: at the cell voltage required for the EDLC device; for the reflow oven temperature profile that the EDLC device will undergo; and during the planned operating life of the device at a given maximum operating temperature.

[0328] It has been found that an exemplary cation that is stable enough in embodiments is a quaternary ammonium salt. More specifically, such an exemplary cation has the following chemical structure:

[0329]

[0330] where R 1 、R 2 、R 3 and R 4 are alkyl substituents. In one embodiment, R 1 、R 2 、R 3 and R 4 are each independently a straight-chain or branched C1-C7 alkyl. In one embodiment, R 1 、R 2 、R 3 and R 4 are each independently a straight-chain or branched C1-C4 alkyl. In one embodiment, R 1 、R 2 、R 3 and R 4 are each independently a straight-chain or branched C1-C2 alkyl, and these salts can be dissolved in an organic solvent in use. In one embodiment, R 1 is different from at least one of R 2 、R 3 and R 4 In one embodiment, R 1, R 2 , R 3 and R 4 are different from each other.

[0331] In other embodiments, the quaternary ammonium cation comprises a disubstituted pyrrolidinium having the following chemical structure:

[0332]

[0333] wherein R 5 and R 6 are each an alkyl substituent. In one embodiment, R 5 and R 6 are each independently a straight-chain or branched C1-C7 alkyl group. In one embodiment, R 5 is different from R 6 .

[0334] In a further embodiment, the quaternary ammonium cation comprises a spiro-bicyclic compound, wherein the common atom in the spiro structure is nitrogen. An exemplary chemical structure of such a cation is as follows:

[0335]

[0336] This structure represents a spiro-bis(pyrrolidinium) cation (SBP), wherein two five-membered rings are connected by a common nitrogen atom. In other embodiments, cations with a similar spiro configuration are used, but wherein one five-membered ring is connected to a six-membered ring. In additional embodiments, two six-membered rings are connected in a spiro configuration by a common nitrogen atom.

[0337] In other embodiments, the cation comprises a nitrogen-containing heterocyclic cation. An example of the chemical structure of such a cation is as follows:

[0338]

[0339] This structure comprises an imidazolium ring having substituents R 7 and R 8 on two nitrogen atoms of the heterocycle. In various embodiments, R 7 and R 8 are each independently a straight-chain or branched C1-C7 alkyl group.

[0340] In one embodiment, the anion is borate and / or phosphate, and more specifically, tetrafluoroborate (TFB) and / or hexafluorophosphate (HFP). Other embodiments utilize alternative and / or additional anions from different borate compounds, such as tetracyano borate, fluoro tricyano borate, difluoro dicyano borate, trifluoro cyano borate, bis(oxalato) borate, difluoro(oxalato) borate.

[0341] In a further embodiment, the anion is sulfonylimide, and more specifically, one or more of bis(fluorosulfonyl)imide (FSI) and bis(trifluoromethylsulfonyl)imide (TFSI).

[0342] It will be appreciated that TFSI and EMI-TFB form an electrolyte that acts as an ionic liquid. Those embodiments that utilize such an ionic liquid do not need to include an organic solvent. However, in other embodiments, the ionic liquid or liquid is combined with one or more organic solvents to improve the conductivity and other selected properties of the resulting electrolyte.

[0343] Further embodiments utilize alternative or additional organic salts, such as SBP-TFB and / or SBP-TFSI. These salts are solids at room temperature alone and in some embodiments are premixed with one or more organic solvents in solid or liquid form to provide the desired liquid electrolyte.

[0344] For those embodiments that use one or more neutral organic compounds / solvents (whether in liquid and / or solid form), the selection of the compound / solvent or those compounds / solvents takes into account the temperature profile of the reflux process and the expected maximum temperature to which the electrolyte will be exposed. In fact, the relevant embodiments utilize neutral organic compounds / solvents having a relatively high boiling point. Given the benefits taught herein, it should be understood that the boiling point of the neutral organic compound does not necessarily need to be higher than 250 °C, or even higher than 200 °C. Instead, the inventors have found that the more important factor is that the resulting electrolyte has a sufficiently high boiling point when measured at 1 atm. For example, in some embodiments, an electrolyte having a very high cation and anion concentration is used to significantly reduce the vapor pressure of the electrolyte relative to a low-concentration mixture. This provides a significant increase in the temperature at which the vapor pressure of the electrolyte will be 1 atm.

[0345] In some embodiments, organic solvents with high dielectric constants, such as polar aprotic solvents, are preferred to facilitate the dissolution and / or mixing of salts during use and to maximize the dissociation of salts. In a preferred embodiment, the solvent is a polar aprotic solvent.

[0346] Exemplary embodiments utilize neutral organic compounds or solvents comprising one or more linear or cyclic carbonates. In one embodiment, the neutral organic compound comprises one or more linear carbonates. For example, in one embodiment, the linear carbonate is diethyl carbonate.

[0347] In one embodiment, the neutral organic compound comprises one or more cyclic carbonates. These cyclic carbonates are high-boiling, high-dielectric liquids, such as those including carbonates having the following chemical structures:

[0348]

[0349] The five-membered ring carbonate includes R 9 , which is H, methyl, fluorinated methyl, or F. In other embodiments, the neutral organic compound includes those further substituted with fluorine on the carbon atoms of the cyclic structure, i.e., the cyclic carbonate includes at least one C-F bond.

[0350] In a further embodiment, the neutral organic compound is a lactone. For example, in some embodiments, the neutral organic compound is a liquid such as γ-butyrolactone (GBL), which has the following chemical structure:

[0351]

[0352] Note that GBL has a lower viscosity than many carbonate liquids and can be selected for those embodiments where the SMD EDLC device requires a higher ionic conductivity of the electrolyte.

[0353] In an even further embodiment, the neutral organic compound includes linear or cyclic sulfones, which have relatively high boiling points. By way of example, the following chemical structures of linear sulfones are provided:

[0354]

[0355] The substituents R 10 and R 11 are each independently a C1-C4 alkyl group. In some embodiments, R 10 and R 11 are the same alkyl group, while in other embodiments, R 10 and R 11 are different alkyl groups. In an exemplary embodiment, R 10 and R 11Both are ethyl groups, and the organic liquid is diethylsulfone (DES).

[0356] As another example, in further embodiments, the neutral organic compound includes a cyclic sulfone, such as a cyclic sulfone having the following chemical structure:

[0357]

[0358] In this structure, R 12 is H (where the neutral organic compound is sulfolane) or methyl (where the neutral organic compound is 3-methyl sulfolane).

[0359] It has been found that the above neutral organic compounds can be applied to embodiments of SMD EDLC devices because they have relatively high boiling points and are generally very stable electrochemically.

[0360] In other embodiments, the neutral organic compound includes 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:

[0361]

[0362] While some embodiments utilize an electrolyte comprising a single organic salt, in other embodiments, the electrolyte comprises a mixture of two or more organic salts. Similarly, although there are embodiments that utilize an electrolyte comprising a single neutral organic compound / solvent, in other embodiments, the electrolyte comprises a mixture of two or more neutral organic compounds / solvents.

[0363] In an exemplary embodiment, the weight percentage of the salt in the electrolyte is between 10% and 100%. The upper end of this range is mainly for embodiments that use an organic salt (i.e., an ionic liquid) without additionally adding an organic liquid solvent for use in combination with the ionic liquid. For other embodiments, the weight percentage of the salt in the electrolyte is between 20% and 100%. In a further embodiment, the weight percentage of the salt in the electrolyte is between: 30% and 100%; 40% and 100%; or 50% and 100%.

[0364] Since the size of SMD EDLC devices is relatively small and there are significant design limitations on the footprint and overall volume of the devices, it becomes even more important to optimize the volume and structure of the components used in the devices to provide the required electrical performance. For example, the ability to use a thin-walled housing helps the resulting EDLC device have more volume available for components that directly contribute to a larger capacitance and / or lower ESR. By avoiding the need for a bulky housing in the prior art to provide thermal protection, these embodiments can provide good electrical characteristics per unit volume and can be manufactured with lower-cost materials and less complex manufacturing steps.

[0365] The axial thickness of the lid 15 is 3 mm, and it has been found that, in the case of a reflow process, this provides: sufficient sealing length for the selected electrolyte; sufficient thickness to contain the rate of electrolyte vapor permeating through the lid; and sufficient resistance to the rupture of the compression seal due to gas accumulation in the cavity during reflow and during the normal operating life of the device. In other embodiments, to provide an additional safety factor, or to better accommodate other electrolyte / diaphragm / electrode combinations, one or more of the following are used: an axially thinner lid or an axially thicker lid; a structurally reinforced lid; and a lid composed of one or more different materials. For example, in a particular other embodiment, the lid 15 uses an alternative synthetic rubber such as ethylene propylene diene monomer (EPDM) rubber. Additionally, in other embodiments, the lid 15 is a composite lid and includes more than one material. For example, in one embodiment, the lid 15 includes a central portion of rigid electrical insulating plastic (in which holes 33 and 34 are formed) and a continuous circumferential outer radial portion of synthetic rubber. In another embodiment, the lid 15 includes a reinforcing element wrapped in rubber, so that its center further resists axial outward deflection due to any gas pressure accumulated in the cavity 8 during the reflow process and during the service life of the device.

[0366] Since the device 1 includes a compression seal, the lid 15 can include other deformable and compressible materials to affect the seal. Similar to the other materials mentioned above, the choice of the material is also based on its ability to withstand the reflow oven temperature and its particular inertness to the electrolyte, so as to substantially not affect the service life of the device.

[0367] In some embodiments, the cap 15 includes an internal or external barrier element for preventing electrolyte vapor from flowing through the cap 15. In one such embodiment, the barrier element is a PTFE layer applied to one or both of the faces 29 and 30. In another such embodiment, the barrier element is a dopant within the rubber, or a dopant within a rubber layer. In another such embodiment, the barrier element is separate from but adjacent to the cap 15.

[0368] When selecting one or more materials for the cap 15, not only the expected thicknesses that provide the desired barrier and sealing properties are considered, but also any components within the materials that may interact with the electrolyte or other components of the device 1. When selecting any dopants or additives for the rubber, particular consideration is given to the fact that those dopants or additives are inert when exposed to the electrolyte, or at least sufficiently inert over the expected temperature range and the lifetime of the device.

[0369] Those skilled in the art will appreciate that the thin-walled aluminum housing 3 provides very little thermal mass or thermal protection for the device 1, and the compression seal of the opening 7 is generally not an airtight seal. Accordingly, the electrolyte and other components used in the device 1 are selected to ensure both: that the EDLC device is sufficient to withstand the reflow process despite the high thermal conductivity of the housing 3; and a sufficiently low rate of electrolyte loss from the cavity 8 through the compression seal. Once the selection is made, the use of the thin-walled aluminum housing 3 and the compression seal is advantageous because they can contribute to one or more of the following:

[0370] (a) Reduced manufacturing complexity and cost relative to the manufacturing techniques for known SMD EDLC devices;

[0371] (b) A reduction in the volume occupied by materials that are primarily used to provide thermal mass or thermal protection, as compared to known SMD EDLC devices.

[0372] (c) For a given footprint / volume on the PCB 2, a greater volume can be used for the internal components within the device 1, which contributes to higher capacitance and / or lower ESR; and

[0373] (d) Reduced use of expensive materials that are primarily intended to provide thermal mass or thermal protection.

[0374] Those skilled in the art will understand that, given the benefits disclosed herein, device 1 is relatively small in volume and mass, and the housing 3 provides little or no thermal shielding for component 9 and the electrolyte. Thus, the design assumption for device 1 is that all of its components will be exposed to near the full range of reflow oven temperatures with little delay during the reflow process. Additionally, conversely, once removed from the reflow oven, device 1 will return to ambient temperature relatively quickly. These design assumptions are different from those for conventional SMD EDLC devices and allow the embodiments to use a thin-walled housing with high thermal conductivity. This in turn simplifies the manufacture of the embodiments, reduces the need for large and expensive packages, and facilitates the mass production of the design.

[0375] Although device 1 is designed for use during reflow, its operating temperature range is from -20°C to 70°C. In other embodiments, the operating temperature range is from -20°C to 80°C, while in further embodiments, the operating temperature range is from -10°C to 70°C. In yet another embodiment, the operating temperature range is from -40°C to 70°C or from -20°C to 85°C. In any case, device 1 is designed for mass production and use, and the operating temperature range has an upper limit that is significantly lower than the temperatures experienced during the reflow process and also lower than the temperatures that devices directly applicable to extreme environments need to withstand. For the planned working life, device 1 will be expected to undergo a single reflow process but otherwise remain within its designed operating temperature range. Although device 1 can withstand exposure to many individual reflow processes, such exposure will affect the device's lifespan.

[0376] It can be understood that a single reflow process can include a single pass through the reflow oven or multiple passes through the reflow oven. If multiple passes are used, this typically includes two passes.

[0377] Now referring to Figures 12 to 17 , which shows a series of steps in the assembly / production of a second exemplary SMD EDLC device 91. In these figures, features corresponding to those of device 1 are denoted by corresponding reference numerals. This does not mean that the corresponding features in device 91 are the same in size, shape, material, or performance as those in device 1, although they may be. Instead, this correspondence exists in the general functions of the similarly marked features.

[0378] Moving on to Figure 12 , the integrally formed thin-walled aluminum alloy housing 3 is sent to a machining station and held in a fixed configuration by a station fixture (not shown). The sidewall 25 of the housing 3 is substantially uniformly cylindrical along axis 4. Figure 13Shows an assembled combination of component 9 and cover 15, which is loaded into an automatic assembly fixture (not shown) and presented to a processing station axially aligned with housing 3. Further, edge 74 is adjacent to end 5 and opening 7. In this embodiment, the maximum outer diameter of component 9 is approximately 0.9 mm smaller than the inner diameter of cavity 8. This allows for easy automatic insertion of component 9 into housing 3 and leaves room for the radial thermal expansion of component 9 within cavity 8 during a subsequent reflow process.

[0379] When it is mentioned that component 9 is complementarily received within cavity 8, this is mainly to express that the outwardly curved exterior of component 9 generally complements the adjacent and opposing inner surfaces of sidewall 25. The outer diameter of component 9 will be smaller than the inner diameter of sidewall 25 to allow component 9 to be inserted into cavity 8. Preferably, the difference between the two diameters is small. As will be understood, in view of the benefits taught herein, the axial dimensions of sidewall 25 and component 9 are significantly different to accommodate the first forming operation and the second forming operation as well as the accommodation of cover 15.

[0380] Component 9 is complementarily received within cavity 8, and due to the use of a thin wall thickness, the difference between the outer diameter of component 9 and the outer diameter of sidewall 25 is 1.5 mm. In one embodiment, the difference between the outer diameter of component 9 and the outer diameter of sidewall 25 is from 1.4 mm to 1.5 mm. In one embodiment, the difference between the outer diameter of component 9 and the outer diameter of sidewall 25 is from 1.3 mm to 1.4 mm. In one embodiment, the difference between the outer diameter of component 9 and the outer diameter of sidewall 25 is from 1.5 mm to 1.6 mm. In one embodiment, the difference between the outer diameter of component 9 and the outer diameter of sidewall 25 is from 1.6 mm to 1.7 mm.

[0381] After automatic insertion, the resulting assembly is as Figure 14 shown. Like device 1, device 91 includes a thin paper liner adhered to the inner surface of sidewall 26. In the Figure 14 structure shown, edges 70 and 74 of respective sheets 13 and 14 are adjacent to or in contact with the paper liner. Further, edges 70 and 74 have been deformed radially inwardly towards axis 4 and provide a complete overlap of edges 62 and 66 through sheets 13 and 14 respectively. This combination of complete overlap and the accommodation of the paper liner within cavity 8 reduces the risk of an accidental short circuit occurring between either of electrodes 11 and 12 and conductive sidewall 26.

[0382] In other embodiments, the difference between the diameter of component 9 and the inner diameter of cavity 8 is less than 0.9 mm, and the mechanical precision for the automatic insertion of component 9 into cavity 8 is higher than that required for the production of device 91.

[0383] In this embodiment, the diameter of the lid 15 is close to the inner diameter of the cavity 8. During the process of advancing the assembled combination of the element 9 and the lid 15 into the cavity 8, the chance of at least a part of the radial periphery of the face 29 engaging with the end 5 is increased. If such engagement occurs, the material properties of the lid 15 will cause the lid to elastically deform and continue to push the lid into the cavity 8 and into Figure 14 the structure shown.

[0384] Then, the automatic assembly fixture releases the combination of the element 9 and the lid 15 and retracts it from the processing station. Subsequently, a first forming tool (not shown) is advanced to the processing station to perform a first forming operation to form the channel 27. Figure 15 The resulting assembled combination is shown. In this embodiment, the first forming tool radially moves to gradually engage with the outer surface of the side wall 25, while the station fixture rotates the contents of the housing 3 and the cavity 8 about the axis 4. In other embodiments, the station fixture moves radially and rotationally about the axis 4, and the first forming tool remains fixed. In other embodiments, other options are used to affect the required relative movement between the station fixture and the first forming tool to form the channel 27.

[0385] Then, the first forming tool retracts from the processing station, and a second forming tool (not shown) is advanced to the processing station. The second forming tool is gradually advanced to roll the end 5 to define the flange 28, the result of which is as shown in Figure 16 and 17 shown. In this embodiment, the second forming tool radially moves to gradually engage with the outer surface of the side wall 25 adjacent to the end 5, while the station fixture rotates the contents of the housing 3 and the cavity 8 about the axis 4. In other embodiments, the station fixture moves radially and rotationally about the axis 4, and the second forming tool remains fixed. In a further embodiment, other options are used to affect the required relative movement between the station fixture and the second forming tool to form the flange 28.

[0386] Now referring more specifically to Figure 17 , in which the shape, configuration and position of the channel 27 and the compression seal provided by the lid 15 are shown in more detail. More specifically, the channel 27 defines a convex protrusion 92 on the inner surface of the side wall 25, the convex protrusion 92 extending radially inwards into the cavity 8 and circumferentially continuously around the housing 3 in a plane perpendicular to the axis 4. The protrusion 92 includes a first shoulder 93 and a second shoulder 94, wherein the shoulder 94 defines a first internal sealing surface 95 of the housing 3. The housing 3 includes a substantially cylindrical engaging portion 96, the engaging portion 96 axially extending between the shoulder 94 and the radially outer end of the flange 28 for defining a second internal sealing surface 97 of the housing 3. The flange 28 defines a third internal sealing surface 98 and an adjacent fourth internal sealing surface 99 of the housing 3.

[0387] In use, as Figure 17 shown, the protrusion 92 extends radially inwards into the cavity 8 and is disposed between the element 9 and the cover 15. In Figure 17 , the axial spacing between the element 9 and the cover 15 is magnified to more clearly show other features. The shoulder 93 limits any post-production axial clearance of the element 9 within the cavity 8.

[0388] During the formation of the flange 28, the radial periphery of the cover 15 is clamped and elastically deformed to conform to the surfaces 95, 97, 98 and 99. The operation forms a continuous compression seal between the following components:

[0389] (a) The sealing surface 95; and both the radially outer periphery of the face 29 and a part of the face 31;

[0390] (b) The sealing surface 97 and another part of the face 31;

[0391] (c) The sealing surface 98 and the radially outer periphery of the face 30; and

[0392] (d) The sealing surface 99 and another part of the face 30;

[0393] The length of the sealing path provided by the above combination is greater than the axial distance between the faces 29 and 30.

[0394] The formation of the flange 28, during the process of compressing the cover 15 around its radial periphery, also has the effect of reducing the diameters of the holes 33 and 34, and thus, improves the sealing engagement and interference fit between the cover 15 and the terminals 11 and 12. If any pressure is formed within the cavity 8 during normal operation due to the generation of gas within the device 1, then this interference fit helps the cover 15 to resist axial deflection.

[0395] In some embodiments, the ferrules 41 of the terminals 11 and 12 are pre-coated with a sealing compound to facilitate the sealing engagement and interference fit with the cover 15.

[0396] Figure 19 Details (examples) of 52 exemplary embodiments are provided. Each of these examples includes a manually wound capacitor element and the same housing for the above-described device 1. The common features of these examples include:

[0397]

[0398]

[0399] The thickness of each carbon layer is 50 μm, except for Examples 38 - 43, where minor variations in the electrode thickness were observed; and Examples 44 - 52, which have carbon layers with a thickness of 70 μm.

[0400] For Figure 19 the binders mentioned in: The term "CMC" refers to sodium carboxymethyl cellulose; the term "PSS70k" refers to sodium polystyrene sulfonate (MW = 70000 amu); the term "PVDF / PSS" refers to a mixture of PVDF and PSS with solid weight percentages of 67% and 33%, respectively. For the PVDF / PSS binder, an exemplary form of PSS is sodium polystyrene sulfonate (MW = 70000 amu), and exemplary commercially available forms of PVDF include the product named 2042Latex provided by Solvay Speciality Polymers

[0401] For Examples 1 to 23, 26, 27, 29 to 34, and 37 to 43, the mixture of activated carbon, carbon black, and binder is: 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 is: 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 is: 100 parts by weight of activated carbon; 30 parts by weight of carbon black; and 15 parts by weight of binder.

[0402] The following table further describes the electrolytes used in the examples.

[0403] The electrolytes listed Description 2M Sulfolane 2M SBPBF4 in sulfolane was dried to a water content of less than 20 ppm 50% GBL 50 wt% SBPBF4 in γ-butyrolactone was dried to a water content of less than 20 ppm 1.2M PC 1.2M SBPBF4 in propylene carbonate was dried to a water content of less than 20 ppm

[0404] It is expected that the manual assembly of these examples will contribute to achieving greater performance variations in the eventual automated manufacturing of such EDLC devices.

[0405] These examples were tested as follows. First, before the device was subjected to reflux simulation, the initial ESR or pre-reflux ESR (referred to as ESR1) and DC capacitance of the device were measured at room temperature and atmospheric pressure. Then, a thermocouple was placed against the outer cylindrical sidewall of the housing, approximately at the mid-axial position, and held in place with a small piece of sticky tape. The temperature measurements provided by the thermocouple during the simulated reflux are referred to as the housing temperature (T H ) of the device. It can be understood that due to the high thermal conductivity of the housing, T Hshould be less sensitive to small variations in the position of the thermocouple on the sidewall. The device is located on the PCB as a separate component, and the device terminals extend parallel to and are placed on the respective pads on the PCB. Then both the PCB and the device are placed in a test oven. The test oven is controlled such that the device and the PCB are exposed to an oven thermal profile that simulates the thermal profile of a typical reflow oven. The oven thermal profile results in a predetermined thermal profile of the case temperature, which is schematically shown in Figure 20 For each thermal profile, a temperature threshold (T H ), and a temperature duration (t T ) are specified. For these embodiments, T D is selected to be 180 °C or 217 °C, which represent two temperatures associated with the liquidus states of two common solder types, respectively. In addition, t T is selected to be between about 25 and 40 seconds, as representative of the time during which T D remains above T H during the reflow process, to best ensure that the solder forms the desired physical and electrical connections between the device terminals and the respective pads on the PCB. T Measurements of the maximum case temperature of each exemplary device obtained during the implementation of the simulated reflow process are also provided in Figure 19 After the simulated reflow process, the device is allowed to cool, and at room temperature and pressure, post-test ESR measurements are performed to provide a second ESR or post-reflow ESR (referred to as ESR2), and for most embodiments, the DC capacitance of the device is provided.

[0406] Measurements of ESR1, ESR2, and the pre- and post-DC capacitances of each exemplary device, as well as the corresponding percentage changes in these values, are listed in Figure 19 It can be understood that during the simulation, the temperature of the surface of the PCB is typically higher than T

[0407] at the corresponding time because the PCB is coated with a heat-absorbing material to assist in heating the solder paste that has been pre-applied to the pads. In addition, T H lags behind the furnace temperature in time, and during the normal duration of the predetermined thermal profile, its maximum temperature is lower than the maximum furnace temperature. H It can be noted from

[0408] that, except for Example 9, T Figure 19 follows the predetermined thermal profile, ESR2 ≥ ESR1, and H It can also be noted from

[0409] that at least one embodiment shows that each of the following conditions is satisfied: Figure 19 respectively: and

[0410] from Figure 19 It can also be noted that when T T = 180 °C, at least one embodiment shows each of the following conditions being met: and

[0411] from Figure 19 it can also be seen that the rated voltages of these embodiments are between 2 volts and 4 volts.

[0412] Figure 19 The embodiments of Figure 19 use an electrolyte based on an organic liquid (i.e., a non-aqueous liquid) to reduce environmental problems associated with aqueous electrolytes. However, one embodiment includes a device containing an aqueous electrolyte.

[0413] Further details of an exemplary method for manufacturing the devices of the embodiments are provided below.

[0414] According to one embodiment, there is provided an electric double layer capacitor (EDLC) device for reflow soldering to a PCB 2, the PCB 2 having a PCB surface 2a with two pads 56, wherein the device comprises:

[0415] A base 51 having a first face 51a opposite to the surface 2a and a second face 51b opposite to the face 51a;

[0416] A housing 3 for defining: an opening 7 opposite to the face 51b in use; and a cavity 8 extending away from the opening 7;

[0417] A substantially cylindrical capacitor element 9 received in the cavity 8, the element 9 comprising:

[0418] Two carbon-based electrodes 11 and 12, each electrode comprising carbon particles; and

[0419] A porous separator in the form of two separator sheets 13 and 14, which are helically wound together with the electrodes 11 and 12, wherein

[0420] The sheets 13 and 14 hold the electrodes in a spaced-apart and opposite configuration and comprise one or more of the following: polytetrafluoroethylene; cellulose fibers; polyacrylonitrile fibers; aramid fibers; and glass fibers;

[0421] An electrolyte within the cavity 8 for allowing ionic conduction between the electrodes 11 and 12, the electrolyte having a freezing point of 0 °C or lower and a boiling point of 200 °C or higher at 1 atmosphere;

[0422] A sealing element in the form of a lid 15 for providing a compression seal for sealing the opening 7; and

[0423] Two terminals 17 and 18, each terminal extending between a first end 19 disposed in the cavity 8 and a second end 20 disposed outside the cavity 8, wherein: the end 19 is electrically connected to the respective electrodes 11 and 12; and the terminals 17 and 18 extend through the opening 7 and the base 51 such that in use, the end 20 is substantially parallel to the surface 2a and is electrically connected to the respective pads 56.

[0424] According to an embodiment of the present invention, there is provided an SMD EDLC device for reflow soldering to a PCB 2, the device comprising:

[0425] A housing 3 for defining an opening 7 and a cavity 8 extending away from the opening 7;

[0426] A capacitor element 9 accommodated in the cavity 8, the element 9 including two carbon-based electrodes 11 and 12 and a separator formed by two separator sheets 13 and 14 for holding the electrodes 11 and 12 in a spaced-apart and opposite configuration;

[0427] An electrolyte within the cavity 8 for allowing ionic conduction between the electrodes 11 and 12, the electrolyte having a freezing point of 0 °C or lower and a boiling point of 200 °C or higher at 1 atmosphere;

[0428] A sealing element in the form of a lid 15 for providing a compression seal for sealing the opening 7; and

[0429] Two terminals 17 and 18, each terminal extending between a first end 19 disposed in the cavity 8 and a second end 20 disposed outside the cavity 8, wherein: the end 19 is electrically connected to the respective electrodes 11 and 12; and the terminals 17 and 18 extend through the opening 7 such that the end 20 can be used for electrical connection to the PCB 2.

[0430] In other embodiments, the boiling point of the electrolyte at 1 atm is: 210 °C or higher; 220 °C or higher; 230 °C or higher; 240 °C or higher; 250 °C or higher; or 260 °C or higher. In other embodiments, the freezing point of the electrolyte at 1 atm is: 10 °C or lower; 20 °C or lower; 30 °C or lower; or 40 °C or lower.

[0431] According to an embodiment of the present invention, there is provided an SMD EDLC device for reflow soldering to a PCB 2, the device comprising:

[0432] A ductile housing 3 for defining an opening 7 and a cavity 8 extending away from the opening 7;

[0433] A capacitor element 9, which is received in a 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, the separator sheets 13 and 14 being helically wound together with the electrodes 11 and 12, wherein the sheets 13 and 14 hold the electrodes 11 and 12 in a spaced-apart and opposite configuration;

[0434] An electrolyte within the cavity 8 for permitting ionic conduction between the electrodes 11 and 12;

[0435] A sealing element in the form of a lid 15 for sealing the opening 7; and

[0436] Two terminals 17 and 18, each terminal extending between a respective first end 19 located within the cavity 8 and a respective second end 20 located outside the cavity 8, wherein: the ends 19 are electrically connected to the respective electrodes 11 and 12; and the terminals 17 and 18 extend through the opening 7 such that the ends 20 can be used for electrical connection to the PCB 2.

[0437] According to one embodiment of the present invention, there is provided an SMD EDLC device for reflow soldering to a PCB 2, the device comprising:

[0438] A housing 3 having high thermal conductivity for defining an opening 7 and a cavity 8 extending away from the opening 7;

[0439] A capacitor element 9, which is received in the cavity 8, the element 9 including two carbon-based electrodes 11 and 12 and a separator formed by two separator sheets 13 and 14, the separator sheets 13 and 14 being helically wound together with the electrodes 11 and 12, wherein the separator sheets 13 and 14 hold the electrodes 11 and 12 in a spaced-apart and opposite configuration;

[0440] An electrolyte within the cavity 8 for permitting ionic conduction between the electrodes 11 and 12;

[0441] A sealing element in the form of a lid 15 for sealing the opening 7; and

[0442] Two terminals 17 and 18, each terminal extending between a respective first end 19 located within the cavity 8 and a respective second end 20 located outside the cavity 8, wherein: the ends 19 are electrically connected to the respective electrodes 11 and 12; and the terminals 17 and 18 extend through the opening 7 such that the ends 20 can be used for electrical connection to the PCB 2.

[0443] According to one embodiment of the present invention, there is provided an SMD EDLC device for reflow soldering to a PCB 2, the device comprising:

[0444] A substantially cylindrical housing 3 for defining an opening 7 and a cavity 8 extending away from the opening 7;

[0445] A capacitor element 9, which is received in a cavity 8, the element 9 including two carbon-based electrodes 11 and 12 and a separator formed by two separator sheets 13 and 14, the separator sheets 13 and 14 being helically wound together with the electrodes 11 and 12, wherein the sheets 13 and 14 hold the electrodes 11 and 12 in a spaced-apart and opposed configuration;

[0446] An electrolyte within the cavity 8 for permitting ionic conduction between the electrodes 11 and 12, the electrolyte having a freezing point of 0 °C or lower and a boiling point of 200 °C or higher at 1 atmosphere;

[0447] A sealing element in the form of a lid 15 for sealing the opening 7; and

[0448] Two terminals 17 and 18, each terminal extending between a first end 19 disposed within the cavity 8 and a second end 20 disposed outside the cavity 8, wherein: the end 19 is electrically connected to the respective electrodes 11 and 12; and the terminals 17 and 18 extend through the opening 7 such that the ends 20 can be used for electrical connection to the PCB 2.

[0449] According to one embodiment of the present invention, there is provided an SMD EDLC device for reflow soldering to a PCB 2, the device including:

[0450] A housing 3 for defining an opening 7 and a cavity 8 extending away from the opening 7;

[0451] A substantially cylindrical capacitor element 9, which is received in the cavity 8, the element 9 including two electrodes 11 and 12, each electrode containing carbon particles, a binder for providing cohesion between the particles in each electrode, and a separator in the form of two separator sheets 13 and 14 helically wound together with the electrodes 11 and 12, wherein the separator sheets 13 and 14 hold the electrodes 11 and 12 in a spaced-apart and opposed configuration, and the binder includes at least one of the following: carboxymethyl cellulose (CMC); a salt of CMC (such as sodium carboxymethyl cellulose); polytetrafluoroethylene (PTFE); polystyrene sulfonate (PSS), such as a Group I or Group II 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;

[0452] An electrolyte within the cavity 8 for permitting ionic conduction between the electrodes 11 and 12;

[0453] A sealing element in the form of a lid 15 for sealing the opening 7; and

[0454] 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, wherein: the end 19 is electrically connected to the respective electrodes 11 and 12; and the terminals 17 and 18 extend through the opening 7 such that the end 20 can be used for electrical connection to the PCB 2.

[0455] According to an embodiment of the present invention, there is provided an SMD EDLC device for reflow soldering to a PCB 2, the device comprising:

[0456] A substantially cylindrical housing 3 for defining an opening 7 and a cavity 8 extending away from the opening 7;

[0457] A capacitor element 9 received within the cavity 8, the element 9 including two carbon-based electrodes 11 and 12, and two separators in the form of separator sheets 13 and 14, the separator sheets 13 and 14 being helically wound with the electrodes 11 and 12, wherein the separator sheets 13 and 14 hold the electrodes 11 and 12 in a spaced-apart and opposed configuration;

[0458] An electrolyte within the cavity 8 for permitting ionic conduction between the electrodes 11 and 12;

[0459] A sealing element in the form of a lid 15 for sealing the opening 7; and

[0460] 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, wherein: the end 19 is electrically connected to the respective electrodes 11 and 12; and the terminals 17 and 18 extend through the opening 7 such that the end 20 can be used for electrical connection to the PCB 2.

[0461] According to an embodiment of the present invention, there is provided an SMD EDLC device for reflow soldering to a PCB 2, the device comprising:

[0462] A ductile housing 3 for defining an opening 7, a cavity 8 extending away from the opening 7, a sealing surface adjacent to the opening 7, and a retaining structure in the form of a flange 28;

[0463] A substantially cylindrical capacitor element 9 received within the cavity 7, the element 9 including two carbon-based electrodes 11 and 12 and two separators in the form of separator sheets 13 and 14, the separator sheets 13 and 14 being helically wound with the electrodes 11 and 12, wherein the sheets 13 and 14 hold the electrodes 11 and 12 in a spaced-apart and opposed configuration;

[0464] An electrolyte within the cavity 8 for permitting ionic conduction between the electrodes 11 and 12;

[0465] A sealing element in the form of a cover 15 for placement against a sealing surface to seal an opening 7, wherein a flange 28 holds the cover 15 in place; and

[0466] Two terminals 17 and 18, each extending between a first end 19 disposed within a cavity 8 and a second end 20 disposed outside the cavity 8, wherein: the end 19 is electrically connected to a respective electrode 11 and 12; and the terminals 17 and 18 extend through the opening 7 such that the ends 20 can be used for electrical connection to a PCB 2.

[0467] Those skilled in the art will understand 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 a material for the electrodes that contributes to this larger surface area generally also results in the electrodes being relatively more mechanically fragile and / or more prone to chemical reactions with other components in the device. These phenomena become more pronounced with the design of smaller EDLC devices suitable for surface mount applications, due to: the drive to use thinner layer materials; and less heat capacity throughout the device to protect the electrolyte and other components from the thermal shock of the reflow process. Additionally, smaller EDLC devices with lower heat capacity experience faster temperature changes when subjected to the reflow process compared to larger non-SMD EDLC devices. The faster thermal expansion of the individual components in an SMD EDLC device, and the different expansion rates of the different components, create greater structural and chemical strain within the device. The inventors have recognized that accommodating this increased rate of temperature change contributes to the overall advantages of these embodiments without the need for bulky packaging and expensive manufacturing techniques. Factors contributing to embodiments with better performance include: the electrolyte having low reactivity with the other materials within and of the housing under the temperature and temperature profile conditions of the reflow process; a helically wound cylindrical capacitor element; complementary cavities for the capacitor element; a thin-walled housing that not only provides a high level of mechanical support for the capacitor element during the reflow process but also provides substantially uniform mechanical support as the capacitor element expands thermally due to the reflow process. In particular, it has been found that the thermal expansion of a helically wound capacitor element is more significant radially than axially. While not wishing to be bound by theory, it should be understood that when radial expansion occurs, the tension winding process acts on the relatively small helically wound capacitor element such that the expansion of the element is substantially equal in all radial directions. This reduction in any point load is understood to reduce the risk of causing local deformation or damage in the electrodes or separator sheets. Additionally, as the element 9 expands radially, its outer radial surface gradually engages the inner surface of the sidewall 25. If the expansion continues and the outer radial surface of the element 9 moves to fully or nearly fully engage the sidewall 25, then the shape of the sidewall can withstand any expected radial forces and maintain the shape of the element 9. For example, if the element 9 is initially slightly misaligned with the axis 4, it will become aligned during any subsequent thermal expansion due to the shape and construction within the sidewall 25.

[0468] While not wishing to be bound by theory, it should be understood that high surface area materials in the electrodes for EDLC devices, particularly materials for carbon-based electrodes, may be difficult to completely remove impurities before or during the manufacture of the electrodes and EDLC devices. This results in an increased sensitivity of such devices to the reaction between any chemical functional groups in these impurities and the ions in the electrolyte. This effect is typically exacerbated at higher operating voltages and higher temperatures, such as those encountered during a reflow process, because the generation of unwanted gases within the enclosure increases. Conventional SMD EDLC devices attempt to counteract this reactivity with a prismatic enclosure having one or more of the following characteristics: an airtight seal to best prevent the entry of unwanted materials that would cause additional gases; a more structurally robust enclosure to withstand the greater internal pressure resulting from the increased gas; and an increased heat capacity to prevent the electrolyte from reaching higher temperatures at which more gas evolution occurs. These prior art prismatic enclosures increase one or both of the following: a significant package volume; and / or a significant material cost and / or manufacturing complexity. It has been found that the designs of element 9 and enclosure 3 used in the above embodiments accommodate the pressure buildup in cavity 8 that occurs during the simulated reflow process and during the simulated operating life of device 1.

[0469] Now refer to Figure 18 , which shows a flow chart of an exemplary method for manufacturing device 1. In step 201, a predetermined proportion of carbon particles and a 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 cleaned and dried at room temperature before being helically wound into a coil. The dried sheet is then gradually unwound and transported to a coating station where it is coated along its width with a thin layer of the slurry comprising a mixture of a liquid, carbon particles, and a binder. The aluminum sheet is immediately advanced to a drying station including a drying oven to remove a substantial amount of the liquid from the mixture of carbon particles and binder. This drying results in the formation of a 20-micron-thick carbon base layer on the aluminum sheet. In other embodiments, the carbon base layer has a different thickness. The aluminum sheet is then rewound and placed in a low humidity, clean environment to dry more thoroughly.

[0470] In one embodiment, the activated carbon particles include a surface area between 1200 m 2 / g and 3000 m 2Activated carbon between / g. In one embodiment, the activated carbon has a D50 particle size between 3 μm and 10 μm, and D10 > 1 μm, D90 < 30 μm. In one embodiment, the activated carbon is microporous carbon, where more than 50% of the pore volume has a size less than 2 nm. 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), YEC-8B (IHUAN Carbon), Y-Carbon (Y-Carbon Company), ZL-302 (Huzhou Sensheng Activated Carbon Co., Ltd), MCSP 2005 (Calgon Mitsubishi Chemical Corporation), MCSP 1805A (Calgon Mitsubishi Chemical Corporation), and MCSP 1805-1 (Calgon Mitsubishi Chemical Corporation).

[0471] In one embodiment, the activated carbon can be classified as mesoporous carbon, where more than 50% of the pore volume has a pore diameter 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), TDA 60 (TDA Research Institute), SO-15A (TDA Research Institute), and ACC (Xiamen All Carbon Corporation).

[0472] The conductive particles present in the carbon-based electrode matrix contribute to efficient electron transport. Typical conductive particles used in EDLCs are carbon blacks. Carbon blacks generally have a submicron primary particle size of 10 nm to 100 nm. Carbon black particles often aggregate and require high shear forces to fully disperse them in the electrode slurry. Examples of suitable carbon blacks include: Printex carbon blacks such as L6 (Orion Carbons), kappa 100 (Orion Engineered Carbons), XE2 (Orion Engineered Carbons), ENSACO 150G (IMERYS), ENSACO 210G (IMERYS), ENSACO 250G (IMERYS), ENSACO 250F (IMERYS), ENSACO 260G (IMERYS), ENSACO 350G (IMERYS), Super C65 (IMERYS), HP (CABOT), LITX300 (CABOT), LITX200 (CABOT), VXC72R (CABOT), BP 700 (CABOT), BP 2000 (CABOT), SC2A (CABOT), TPX1278 (CABOT), Lump Black (Degussa), Ketjenblack EC300J (AkzoNoble), Ketjenblack EC600JD (Akzo Noble), E-MM-198G (Timcal), and Super P (Timcal).

[0473] In some embodiments, both surfaces of the aluminum sheet are coated with the slurry simultaneously. In other embodiments, the coating operation is staged, i.e., one surface is coated and the opposite surface is coated after drying. In other embodiments, the aluminum sheet is coated on only one surface.

[0474] In step 202, the rewound aluminum sheet is placed at a cutting station where the sheet is unwound and transversely cut to define a substantially rectangular and longitudinally extending sheet portion separated from the coil. The longitudinal length of the sheet portion is determined by the electrode length required in device 1. The portion is then cut along a longitudinal path that is transversely offset 7 mm 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 cutting is repeated, with the next transverse offset starting from the new edge created by the previous cutting operation, to define an elongated double-sided carbon-based electrode 12. The cutting operation is repeated until all or substantially all of the sheet portion has been converted into electrodes, then another sheet portion is removed from the coil and the cutting process is restarted. Although this cutting is mechanically achieved with one or more blades, in one embodiment, the sheet segmentation is implemented by another form of cutting, such as laser cutting.

[0475] Once electrodes 11 and 12 are produced, they are advanced in step 204 to a connection station where they are fixedly electrically connected to respective terminals 17 and 18. For device 1, the connection between each terminal and the corresponding electrode includes two separate and spaced-apart connection points. In particular, the face 38 of the end 19 of terminal 17 abuts a surface of electrode 11 at a predetermined longitudinal position, and axis 39 is substantially perpendicular to axis 4. The end 19 is then pierced with two spaced-apart circular punches that first contact surface 37 and then advance through the end 19 and the adjacent electrode 11. This operation creates two spaced-apart radial structures, each extending from the end 19, through the electrode 11 and beyond the opposite face of the electrode 11. The radial structures are flattened and moved into engagement with the opposite face of the electrode 11 to establish the required constrained mechanical and electrical contact between the electrode 11 and the terminal 17. A similar operation is performed on electrode 12 and terminal 18. In other embodiments, a different number of connection points are created. In other embodiments, a different number of connection points are used, or other forms of connection and / or connection points.

[0476] Then, in step 205, electrodes 11 and 12 are connected to respective terminals 17 and 18 and helically wound together with intermediate sheets 13 and 14 about axis 4. The winding process uses a generally cylindrical mandrel extending along axis 4 having an effective diameter of 4 mm. The mandrel comprises two axially extending mandrel members having semi-circular cross-sections. The flat portions of the mandrel members are opposed and define jaws for receiving and clamping the inner ends of each of sheets 13 and 14. Once these ends are received and held in the jaws, the sheets are tensioned and the mandrel is rotated two to three turns to form a hollow cylindrical central core of element 9 having the inner ends of sheets 13 and 14. Then, the tension on the sheets is released and electrodes 11 and 12 and sheets 13 and 14 are alternately arranged. Tension is again applied such that electrodes 11 and 12 are also subject to the same tension. The mandrel is rotated again to effect progressive winding of the electrodes and separator sheets about the core under substantially uniform tension.

[0477] The final winding of sheet 14 extends circumferentially beyond the outer edge 72 of sheet 13 and an adhesive tape 77 is applied to secure the end 75 of sheet 14 to the immediately preceding winding below and adjacent to sheet 14. Then, the mandrel members are moved slightly radially apart from each other to release the clamping force on the inner ends of sheets 13 and 14. Then, the mandrel members are withdrawn from the core by axially advancing the mandrel relative to element 9. This leaves a hollow central axial hole in element 9.

[0478] In other embodiments, the mandrel has a different effective diameter. In a further embodiment, the mandrel comprises slots for receiving and holding the inner ends of sheets 13 and 14 in an interference fit rather than a clamping engagement. In yet another embodiment, the mandrel comprises a non-circular cross-section and is removably and complementarily received in a hole in a spool to which the inner ends of sheets 13 and 14 are connected. At the end of the winding process, the spool is removed from the mandrel and remains with element 9.

[0479] When step 205 is completed, a substantially cylindrical element 9 has been manufactured.

[0480] Element 9 is advanced to a filling station where, in step 206, element 9 is inserted into cavity 8 of still end-open housing 3. Then, this station establishes a negative pressure, low humidity and high temperature environment for the combination of element 9 and housing 3 to reduce any residual liquid and in particular to remove residual water molecules. Then, a predetermined dose of electrolyte is placed into cavity 8 and is absorbed by separator sheets 13 and 14 and moves into the voids of the carbon-based electrodes to wet these electrodes.

[0481] While still at the filling station and while still being subjected to one or more of negative pressure, low humidity, and high temperature, in step 207, the cover 15 is advanced relative to the opening 7 along the axis 4 such that the ends 20 of the terminals 17 and 18 are received by the respective holes 33 and 34 and then extend through the respective holes 33 and 34. The cover 15 continues to advance along the axis 4 relative to the housing 3 until the ferrule 41 is received within the holes 33 and 34 and the face 42 engages the adjacent surface of the cover 15 in an interference fit. At this time, the face 30 of the cover 15 has passed through the opening 7 and is located within the cavity 8.

[0482] In step 208, the assembly of the above components is advanced to the forming station for the first forming operation and the second forming operation to seal the opening 7, which has been described above.

[0483] In step 209, the base 51 is advanced along the axis 4 relative to the element 9 such that the ends 20 of the terminals 17 and 18 are received within the respective holes 53 and 54. Then, the base 51 is further advanced along the axis 4 relative to the element 9 such that the ends 20 axially extend through and beyond the base 51 and the base 51 abuts the end 5 of the housing 3. Then, the ends 20 of the terminals 17 and 18 are plastically deformed perpendicular to the faces 45 and 46 such that the ends 20 extend substantially perpendicular to the ends 19 and the axis 39. The resulting structure of the terminals 17 and 18 is to fixedly hold the base 51 in engagement with the end 5. Further, the deformation of the ends 20 of the terminals 17 and 18 causes them to extend away from each other and the faces 46 and 45 are respectively available for abutting against the pads 56 on the PCB 2.

[0484] Then, in step 210, the device 1 is advanced to the test station where a series of electrical tests are performed to determine whether the characteristics of the manufactured SMD EDLC device fall within the required tolerances and / or other required operating standards.

[0485] According to an embodiment of the present invention, there is provided a method of manufacturing a device 1, the device 1 being an electric double layer capacitor (EDLC) device for reflow soldering to a PCB 2, and wherein the method comprises:

[0486] (a) providing a substantially cylindrical ductile housing 3 having an opening 7 and a cavity 8 extending away from the opening 7;

[0487] (b) plastically deforming the housing 3 to define a sealing surface adjacent to the opening 7;

[0488] (c) plastically deforming the housing 3 to define a retaining structure in the form of a flange 28;

[0489] (d) The two carbon-based electrodes 11 and 12 are helically wound together with the separator in the form of two separator sheets 13 and 14 to provide a substantially cylindrical capacitor element 9, wherein the separator sheets 13 and 14 hold the electrodes 11 and 12 in a spaced-apart and opposing configuration;

[0490] (e) The element 9 is received in the cavity 8;

[0491] (f) An electrolyte is provided within the cavity 8 for allowing ionic conduction between the electrodes 11 and 12;

[0492] (g) A sealing element in the form of a lid 15 is provided for placement against the sealing surface to seal the opening 7, wherein the flange 28 holds the lid 15 in place; and

[0493] (h) Two terminals 17 and 18 are provided, each extending between a first end 19 disposed within the cavity 8 and a second end 20 disposed outside the cavity 8, wherein: the end 19 is electrically connected to the respective electrode 11 and 12; and the terminals 17 and 18 extend through the opening 7 such that the ends 20 can be used for electrical connection to the PCB 2.

[0494] The above-described embodiments of the present invention have been developed for surface mount technology applications and are applicable to a wide range: electrical equipment incorporating EDLC surface mount devices; platforms using one or more of these electrical equipment; and systems utilizing one or more of these devices or one or more of these platforms. Examples of electronic devices include computing devices such as desktop computers, servers, controllers, laptops, tablets, etc. In such computing devices, the SMD EDLC devices can more specifically be included in the electronic device, such as a graphics card, memory card, motherboard, computer peripherals, or any other circuitry in the electronic device or peripheral. Other electronic devices to which the embodiments of the present invention are advantageously applied include: communication devices such as smartphones, cellular phones, other cellular devices, etc.; control devices such as pump controllers, motor controllers, power management controllers, etc.; remote monitoring devices; asset tracking devices; power train control of electric vehicles or vehicles using internal combustion engines; vehicle accessories such as key fobs; control devices for electronic locks, etc.; wireless handheld devices such as point-of-sale devices; scanning devices; measuring devices; wireless remote control devices; smart meters or other such fixed meters; wearable technology devices such as smart watches and health monitoring patches; Internet of Things devices; wireless sensors; and others.

[0495] The electronic devices described above can be used on, in, or near a wide variety of platforms, whether mobile or stationary. Examples of such platforms include: land-based vehicular platforms (whether utilizing propulsion systems powered by internal combustion engines, electrical energy, or other means); aircraft platforms, including drones; computing platforms; surveillance platforms; military platforms; communications platforms; mobile and stationary maritime platforms; wearable technology platforms; and other platforms.

[0496] The electronic devices and platforms mentioned above can be used on, in or through a variety of systems, such as: telecommunication systems; server systems (including single servers, distributed server systems, server clusters, etc.); control systems (such as fleet management systems, building management systems, manufacturing systems, etc.); and other systems.

[0497] It should be understood that in the above description of exemplary embodiments of the invention, various features of the invention are sometimes combined in a single embodiment, figure, or description thereof for the purpose of simplifying the disclosure and aiding in the understanding of one or more various inventive aspects. However, this method of disclosure should not be interpreted as reflecting an intention that the claimed invention requires more features than those expressly recited in each claim. On the contrary, as reflected in the following claims, the inventive aspects are less than all the features of a single preceding disclosed embodiment. Therefore, the claims following the detailed description are hereby expressly incorporated into the detailed description, with each claim independently serving as a separate embodiment of the invention.

[0498] In addition, although some embodiments described herein include some but do not include other features included in other embodiments, the combination of features of different embodiments is meant to be within the scope of the present invention and to form different embodiments, as will be understood by those skilled in the art. For example, in the claims below, any claimed embodiment may be used in any combination.

[0499] In the description provided herein, many specific details are set forth. However, it should be understood that embodiments of the present invention can be implemented without these specific details. In other cases, well-known methods, structures and techniques are not shown in detail to avoid blurring the understanding of this specification.

[0500] Similarly, it should be noted that the term "connected", as used in this specification, particularly in the claims, should not be construed as limited to direct connection. The terms "connected" and its derivatives may be used. It should be understood that these terms are not intended as synonyms for each other. Thus, the scope of the expression "device A connected to device B" should not be limited to devices or systems where the output or element of device A is directly connected to the input or element of device B. This means that there is a functional path between the output of A and the input of B, and the path may be one that includes other components or devices. "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.

[0501] Accordingly, while the preferred embodiments of the invention have been described, those skilled in the art will recognize that other and further modifications can be made thereto without departing from the spirit of the invention, and it is intended that all such changes and modifications fall within the scope of the invention.

Claims

1. 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 away from the opening; a substantially cylindrical capacitor element received in the cavity, the element comprising two carbon-based electrodes and a separator helically wound together with the electrodes, wherein the separator holds the electrodes in a spaced-apart and opposed configuration; an electrolyte within the cavity for permitting ionic conduction between the electrodes; a sealing element for sealing the opening; and two terminals, each terminal extending between a first end disposed within the cavity and a second end disposed outside the cavity, wherein: the first end is electrically connected to a respective electrode; and the terminals extend through the opening such that the second ends can be used for electrical connection to the PCB.

2. The EDLC device according to claim 1, wherein, The PCB includes a PCB surface on which the device is to be mounted, and the device includes a base having a first face opposite the PCB surface, and the terminals extend relative to the base such that in use, the second ends are substantially parallel to the PCB surface.

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

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

5. The EDLC device according to any one of claims 2 to 4, wherein, The terminals hold the base to the housing in a limiting manner.

6. The EDLC device according to any one of claims 2 to 5, wherein, In use, the base is disposed between the housing and the PCB surface.

7. The EDLC device according to any one of claims 2 to 6, wherein, The base includes a conductive portion which, in use, is disposed adjacent to the terminals.

8. The EDLC device according to any one of claims 1 to 6, wherein, The sealing element provides a compression seal.

9. The EDLC device according to claim 8, wherein, The housing includes a ductile sidewall that plastically deforms to define a sealing surface for the compression seal.

10. The EDLC device according to claim 9, wherein, The ductile sidewall comprises aluminum, an aluminum alloy or stainless steel.

11. The EDLC device according to any one of claims 1 to 10, wherein, At least one of the electrodes includes a high surface area carbon-based material.

12. The EDLC device according to claim 11, wherein, The carbon-based material includes mesoporous carbon particles.

13. The EDLC device according to any one of claims 1 to 12, wherein, At least one of the electrodes includes an adhesive that is stable at at least 200°C.

14. The EDLC device according to any one of claims 1 to 13, wherein, The electrolyte is an organic electrolyte having a boiling point greater than 200°C at 1 atmosphere.

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

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