Electrode assembly for ultracapacitors

Abstract

To provide an electrode assembly and an ultracapacitor that mitigate the problem of increase in the equivalent series resistance (ESR), especially at a high temperature.SOLUTION: An electrode assembly for an ultracapacitor contains a first electrode 12 comprising a first current collector 20 electrically coupled to first carbonaceous coatings 22, 24, a second electrode 14 comprising a second current collector 40 electrically coupled to second carbonaceous coatings 42, 44, and a separator 60 positioned between the first electrode and the second electrode. At least a part of the first current collector projects beyond a first longitudinal edge to define a first projecting portion, where an offset ratio of the first projecting portion is from about 0.02 to about 0.3.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 62 / 527,278, filed on 30 June 2017 (which is incorporated herein by reference in its entirety). [Background technology]

[0002] Electrical energy storage cells are widely used to power electronic devices, electromechanical devices, electrochemical devices, and other useful devices. For example, electric double-layer ultracapacitors generally use a pair of polarizing electrodes containing electrolyte-impregnated carbon particles (e.g., activated carbon). The effective surface area of ​​the particles and the small spacing between the electrodes allow for the achievement of large capacitance values. However, problems remain. For example, many conventional ultracapacitors are sensitive to high temperatures, which can result in increased equivalent series resistance (ESR). Therefore, there is now a need for ultracapacitors with improved electrical properties. [Overview of the project]

[0003] According to one embodiment of the present invention, an electrode assembly for an ultracapacitor is disclosed that defines the length between opposing first and second longitudinal edges. The electrode assembly includes a first electrode comprising a first current collector electrically coupled to a first carbonaceous coating, a second electrode comprising a second current collector electrically coupled to a second carbonaceous coating, and a separator positioned between the first and second electrodes. At least a portion of the first current collector protrudes beyond the first longitudinal edge, defining a first protruding portion. The offset ratio of the first protruding portion is about 0.02 to about 0.3.

[0004] Other features and embodiments of the present invention are described in more detail below. A complete and implementable disclosure of the present invention, including the best mode of the invention, directed towards those skilled in the art, is described in more detail in the remainder of this specification with reference to the accompanying drawings. [Brief explanation of the drawing]

[0005] [Figure 1] Figure 1 is an exploded cross-sectional view of one embodiment of the electrode assembly of the present invention. [Figure 2] Figure 2 is a top view of the electrode assembly shown in Figure 1. [Figure 3] Figure 3 is a schematic diagram of one embodiment of an ultracapacitor that can be formed according to the present invention, before it is sealed with a lid. [Figure 4] Figure 4 is a schematic diagram of one embodiment of an ultracapacitor that can be formed according to the present invention. [Modes for carrying out the invention]

[0006] The repeated use of reference numerals in this specification and drawings is intended to represent identical or similar features or elements of the present invention. Those skilled in the art will understand that this discussion is merely a description of exemplary embodiments and is not intended to limit broader embodiments of the present invention, which are embodied in the exemplary configurations.

[0007] Generally speaking, the present invention relates to an electrode assembly for use in an ultracapacitor. The electrode assembly includes a first electrode comprising a first carbonaceous coating (e.g., activated carbon particles) electrically coupled to a first current collector, and a second electrode comprising a second carbonaceous coating (e.g., activated carbon particles) electrically coupled to a second current collector. A separator is also placed between the first electrode and the second electrode. The electrode assembly is configured such that the electrodes and the separator are connected, for example, by a multiplier. It is formed by combining elements through layering, spiral winding, and other methods.

[0008] Regardless of the technology used, at least one of the current collectors (first and / or second current collectors) protrudes beyond the longitudinal edge of the electrode assembly. The protruding portion of the current collector can provide an increased surface area for contact with the terminals in the housing, thereby reducing the ESR. For example, the resulting ultracapacitor may exhibit an ESR of about 100 milliohms or less, measured without applied voltage at a frequency of 100 kHz and a temperature of 25°C, less than about 80 milliohms in some embodiments, about 0.01 to about 50 milliohms in some embodiments, and about 0.05 to about 20 milliohms in some embodiments. The ESR can also be maintained stably at a variety of different temperatures. For example, the ultracapacitor can be placed in contact with an atmosphere having a temperature of about 80°C or higher, about 100°C to about 150°C in some embodiments, and about 105°C to about 130°C (e.g., 85°C or 105°C) in some embodiments. Even at such high temperatures, the ESR can be maintained within the above range for a considerable time, generally about 100 hours or more, about 300 to about 5000 hours in some embodiments, and about 600 to about 4500 hours in some embodiments (e.g., 168, 336, 504, 672, 840, 1008, 1512, 2040, 3024, or 4032 hours). For example, in one embodiment, the ratio of the ESR of an ultracapacitor after exposure to a high-temperature atmosphere (e.g., 85°C or 105°C) for 1008 hours to the ESR of the ultracapacitor at the time of initial exposure to the high-temperature atmosphere is about 1.3 or less, about 1.2 or less in some embodiments, and about 0.2 to about 1 in some embodiments.

[0009] Such low ESR values ​​can be maintained, as described above, even under various extreme conditions such as when high voltages are applied and / or in a high-humidity atmosphere. For example, the ratio of the ESR of an ultracapacitor after exposure to a high-temperature atmosphere (e.g., 85°C or 105°C) and applied voltage to the initial ESR of an ultracapacitor before exposure to a high-temperature atmosphere but before voltage application may be about 1.8 or less, about 1.7 or less in some embodiments, and about 0.2 to about 1.6 in some embodiments. The voltage may be, for example, about 1 volt or more, about 1.5 volt or more in some embodiments, and about 2 to about 10 volts (e.g., 2.1 volts) in some embodiments. For example, in one embodiment, the above ratio can be maintained for 1008 hours or more. Ultracapacitors can also maintain the above-mentioned ESR values ​​when exposed to high humidity levels. For example, the ratio of the ESR of an ultracapacitor after exposure to a high-temperature atmosphere (e.g., 85°C or 105°C) and high humidity (e.g., 85%) to the initial capacitance value of the ultracapacitor before exposure to the high-temperature but high-humidity atmosphere may be about 1.5 or less, about 1.4 or less in some embodiments, and about 0.2 to about 1.2 in some embodiments. For example, in one embodiment, this ratio can be maintained for 1008 hours or more.

[0010] The "offset ratio" of the protruding current collector, determined by dividing the length of the current collector's protruding portion by the length of the electrode assembly, is generally controlled within the range of approximately 0.02 to 0.3, approximately 0.04 to 0.2 in some embodiments, and approximately 0.05 to 0.1 in some embodiments. For example, the length of the current collector's protruding portion can be approximately 1 to 20 millimeters, approximately 2 to 16 millimeters in some embodiments, and approximately 5 to 15 millimeters in some embodiments. The length of the electrode assembly can be approximately 5 to 100 millimeters, approximately 8 to 60 millimeters in some embodiments, and approximately 10 to 25 millimeters in some embodiments. The inventors have found that by selectively controlling the electrode offset ratio and relative length of the protruding portion and the electrode assembly, the resulting ultracapacitor can achieve not only a reduced ESR but also a high capacitance value. The ultracapacitor is, for example, 12 At a frequency of 0 Hz and a temperature of 25°C, the measured value without applied voltage was approximately 6 farads / square centimeter (F / cm²). 2 ) In some embodiments, the temperature is approximately 8 F / cm². 2 In some embodiments described above, the temperature is approximately 9 to 100 F / cm². 2 , and in some embodiments, about 10 to about 80 F / cm 2 The capacitance value can be shown.

[0011] Capacitance can also be stably maintained at the above high temperatures for a considerable period of time, such as approximately 100 hours or more, approximately 300 to approximately 5000 hours in some embodiments, and approximately 600 to approximately 4500 hours in some embodiments (e.g., 168, 336, 504, 672, 840, 1008, 1512, 2040, 3024, or 4032 hours). For example, in one embodiment, the ratio of the capacitance value of the ultracapacitor after 1008 hours of exposure to a high-temperature atmosphere (e.g., 85°C or 105°C) to the capacitance value of the ultracapacitor at the time of initial exposure to the high-temperature atmosphere is approximately 0.75 or more, approximately 0.8 to 1.0 in some embodiments, and approximately 0.85 to 1.0 in some embodiments. Furthermore, high capacitance values ​​can be maintained when a voltage is applied and / or in a high-humidity atmosphere. For example, the ratio of the capacitance value of an ultracapacitor after exposure to a high-temperature atmosphere (e.g., 85°C or 105°C) and applied voltage to the initial capacitance value of the ultracapacitor before exposure to the high-temperature atmosphere but before the voltage was applied may be about 0.60 or more, about 0.65 to 1.0 in some embodiments, and about 0.7 to 1.0 in some embodiments. The voltage may be, for example, about 1 volt or more, about 1.5 volt or more in some embodiments, and about 2 to about 10 volts (e.g., 2.1 volts) in some embodiments. For example, in one embodiment, the above ratio can be maintained for 1008 hours or more. The ultracapacitor can also maintain the above capacitance value when exposed to high humidity levels, such as when placed in contact with an atmosphere having a relative humidity of about 40% or more, about 45% or more in some embodiments, about 50% or more in some embodiments, and about 70% or more in some embodiments (e.g., about 85% to 100%). The relative humidity can be determined, for example, according to ASTM-E337-02, Method A (2007).For example, the ratio of the capacitance value of an ultracapacitor after exposure to a high-temperature atmosphere (e.g., 85°C or 105°C) and high humidity (e.g., 85%) to the initial capacitance value of the ultracapacitor before exposure to the high-temperature atmosphere but high humidity may be about 0.7 or more, about 0.75 to 1.0 in some embodiments, and about 0.80 to 1.0 in some embodiments. For example, in one embodiment, this ratio can be maintained for 1008 hours or more.

[0012] Herein, various embodiments of the present invention will be described in more detail. I. Electrode Assembly: A. Electrode: As described above, the electrode assembly includes first and second electrodes, which each include first and second current collectors. It should be understood that additional current collectors may be used if desired, especially if the ultracapacitor includes multiple energy storage cells. The current collectors may be formed from the same or different materials. However, each current collector is typically formed from a substrate containing conductive metals such as aluminum, stainless steel, nickel, silver, palladium, and alloys thereof. Aluminum and aluminum alloys are particularly suitable for use in the present invention. The substrate may be in the form of foil, sheet, plate, mesh, etc. The substrate may also have relatively small thicknesses, such as about 200 micrometers or less, about 1 to about 100 micrometers in some embodiments, about 5 to about 80 micrometers in some embodiments, and about 10 to about 50 micrometers in some embodiments. Although not essential, the surface of the substrate may be roughened by washing, etching, blasting, etc.

[0013] The first and second carbonaceous coatings are also electrically coupled to the first and second current collectors, respectively. They can be formed from the same or different types of materials and may include one or more layers, although each of the carbonaceous coatings generally includes at least one layer containing activated particles. For example, in some embodiments, an activated carbon layer can be disposed directly on the current collector, and in some cases, this may be the only layer of the carbonaceous coating. Examples of suitable activated carbon particles include, for example, coconut shell-based activated carbon, petroleum coke-based activated carbon, pitch-based activated carbon, polyvinylidene chloride-based activated carbon, phenolic resin-based activated carbon, polyacrylonitrile-based activated carbon, and activated carbon from natural sources such as coal, charcoal, or other natural organic sources.

[0014] In some embodiments, it may be desirable to selectively control some characteristics of the activated carbon particles, such as their particle size distribution, surface area, and pore size distribution, to help improve the ion mobility with respect to some types of electrolytes after one or more charge-discharge cycles. For example, at least 50% by volume of the particles may have a dimension (D50 diameter) in the range of about 0.01 to about 30 micrometers, in some embodiments about 0.1 to about 20 micrometers, and in some embodiments about 0.5 to about 10 micrometers. Also, at least 90% by volume of the particles may have a dimension (D90 diameter) in the range of about 2 to about 40 micrometers, in some embodiments about 5 to about 30 micrometers, and in some embodiments about 6 to about 15 micrometers. Also, the BET surface area may be from about 900 m 2 / g to about 3,000 m 2 / g, in some embodiments from about 1,000 m 2 / g to about 2,500 m 2 / g, and in some embodiments from about 1,100 m 2 / g to about 1,800 m 2 / g.

[0015] In addition to having specific dimensions and surface area, activated carbon particles may also contain pores with a specific diameter distribution. For example, the amount of pores with a diameter of less than about 2 nanometers (i.e., micropores) can give a pore volume of about 50% or less by volume of the total pore volume, about 30% or less by volume in some embodiments, and 0.1% to 15% by volume in some embodiments. The amount of pores with a diameter between about 2 nanometers and about 50 nanometers (i.e., mesopores) may be about 20% to about 80% by volume, about 25% to about 75% by volume in some embodiments, and about 35% to about 65% by volume in some embodiments. Finally, the amount of pores with a diameter greater than about 50 nanometers (i.e., macropores) may be about 1% to about 50% by volume, about 5% to about 40% by volume in some embodiments, and about 10% to about 35% by volume in some embodiments. The total pore volume of the carbon particles is about 0.2 cm³. 3 / g ~ approx. 1.5cm 3 / g, approximately 0.4cm in some embodiments 3 / g ~ approx. 1.0cm 3 The pore size may be in the range of / g, and the median pore width may be about 8 nanometers or less, about 1 nanometer to about 5 nanometers in some embodiments, and about 2 to about 4 nanometers in some embodiments. The pore diameter and total pore volume can be measured using nitrogen adsorption and analyzed by the Barrett-Joyner-Halenda (BJH) method, as is well known in the art.

[0016] If desired, the binder may be present in an amount of about 60 parts or less, in some embodiments 40 parts or less, and in some embodiments about 1 to about 25 parts per 100 parts of carbon in the first and / or second carbonaceous coating. The binder may constitute, for example, about 15% by weight or less, in some embodiments about 10% by weight or less, and in some embodiments about 0.5% to about 5% by weight of the total weight of the carbonaceous coating. Any variety of suitable binders can be used in the electrode. For example, in some embodiments, styrene-butadiene copolymer, polyvinyl acetate homopolymer, vinyl acetate ethylene copolymer, vinyl acetate acrylic copolymer, ethylene-vinyl chloride copolymer, ethylene-vinyl chloride-vinyl acetate terpolymer, acrylic polyvinyl chloride polymer, acrylic polymer, nitrile polymer, polytetrafluoroethylene, or polyvinylidene fluoride. Water-insoluble organic binders such as fluoropolymers, polyolefins, and mixtures thereof can be used. Water-soluble organic binders such as polysaccharides and their derivatives can also be used. In one particular embodiment, the polysaccharide may be a nonionic cellulose ether such as alkylcellulose ethers (e.g., methylcellulose and ethylcellulose); hydroxyalkylcellulose ethers (e.g., hydroxyethylcellulose, hydroxypropylcellulose, hydroxypropylhydroxybutylcellulose, hydroxyethylhydroxypropylcellulose, hydroxyethylhydroxybutylcellulose, hydroxyethylhydroxypropylhydroxybutylcellulose, etc.); alkylhydroxyalkylcellulose ethers (e.g., methylhydroxyethylcellulose, methylhydroxypropylcellulose, ethylhydroxyethylcellulose, ethylhydroxypropylcellulose, methylethylhydroxyethylcellulose, and methylethylhydroxypropylcellulose); carboxyalkylcellulose ethers (e.g., carboxymethylcellulose); and any of the above protonated salts such as sodium carboxymethylcellulose.

[0017] Other materials can also be used within the activated carbon layer of the first and / or second carbonaceous coating, and / or within other layers of the first and / or second carbonaceous coating. For example, in some embodiments, a conductivity promoter can be used to further increase conductivity. Representative conductivity promoters include, for example, carbon black, graphite (natural or artificial), graphite, carbon nanotubes, nanowires or nanotubes, metal fibers, graphene, etc., as well as mixtures thereof. Carbon black is particularly preferred. When used, the conductivity promoter usually constitutes about 60 parts or less per 100 parts of activated carbon particles in the carbonaceous coating, about 40 parts or less in some embodiments, and about 1 to about 25 parts in some embodiments. The conductivity promoter can constitute, for example, about 15 wt% or less of the total weight of the carbonaceous coating, about 10 wt% or less in some embodiments, and about 0.5 wt% to about 5 wt% in some embodiments. Also, the activated carbon particles usually constitute 85 wt% or more of the carbonaceous coating, about 90 wt% or more in some embodiments, and about 95 wt% to about 99.5 wt% in some embodiments.

[0018] The specific method of applying the carbonaceous coating to the current collector can be varied as is well known to those skilled in the art, such as printing (e.g., rotary gravure), spraying, slot die coating, drop coating, dip coating, etc. Regardless of the method of applying it, the resulting electrode is usually dried at a temperature of about 100 °C or higher, about 200 °C or higher in some embodiments, and about 300 °C to about 500 °C in some embodiments to remove moisture from the coating. The electrode can also be compressed (e.g., calendared) to optimize the volumetric efficiency of the ultracapacitor. After any optional compression, the thickness of each carbonaceous coating can generally be varied based on the desired electrical performance and operating range of the ultracapacitor. However, usually, the thickness of the coating is about 20 to about 200 micrometers, 30 to about 150 micrometers, and about 40 to about 100 micrometers in some embodiments. The coating can be present on one or both sides of the current collector. However, the thickness of the entire electrode (including the current collector and carbonaceous coating after optional compression) is typically in the range of about 20 to about 350 micrometers, in some embodiments about 30 to about 300 micrometers, and in some embodiments about 50 to about 250 micrometers.

[0019] B. Separator: A separator is also disposed between the first electrode and the second electrode. If desired, other separators can also be used in the electrode assembly. For example, one or more separators can be disposed on the first electrode, the second electrode, or both. The separator helps to electrically insulate one electrode from the other to prevent an electrical short circuit, yet still allows for the transport of ions between the two electrodes. For example, in some embodiments, separators including cellulose fiber materials (such as airlaid paper webs, wetlaid paper webs, etc.), non-woven fiber materials (such as polyolefin non-woven webs), woven fabrics, films (such as polyolefin films), etc. can be used. Cellulose fiber materials such as those including natural fibers, synthetic fibers, etc. are particularly suitable for use in ultracapacitors. Specific examples of cellulose fibers suitable for use in the separator can include, for example, hardwood pulp fibers, softwood pulp fibers, rayon fibers, regenerated cellulose fibers, etc. Regardless of the specific material used, the separator typically has a thickness of about 5 to about 150 micrometers, in some embodiments about 10 to about 100 micrometers, and in some embodiments about 20 to about 80 micrometers.

[0020] The method of assembling the components of an electrode assembly can be varied as is known in the art. For example, the electrodes and separators can be folded, wound, or otherwise brought into contact together to form an electrode assembly. In one particular embodiment, the electrodes, separators, and optionally the electrolyte can be wound to form an electrode assembly having a "jelly roll" structure. Referring to Figures 1-2, for example, one embodiment of an electrode assembly 10 is shown, which includes a first electrode 12, a second electrode 14, and a separator 60 positioned between electrodes 12 and 14. In this particular embodiment, the electrode assembly 10 also includes another separator 70 positioned on top of the second electrode 14. In this way, each of the two coated surfaces of the electrode is separated by the separator, thereby maximizing the surface area and capacitance per unit volume. The first electrode 12 includes carbonaceous coatings 22 and 24 placed on opposing surfaces of the first current collector 20, while the second electrode 14 includes carbonaceous coatings 42 and 44 placed on opposing surfaces of the second current collector 40. Of course, it should be understood that not both surfaces of the current collector need to include carbonaceous coatings.

[0021] As shown in Figure 2, electrodes 12 and 14 and separators 60 and 70 are wound together such that the assembly 10 extends longitudinally between the longitudinal edges 41 and 21 to define a length "L". For example, in the illustrated embodiment, separators 60 and 70 are shown as having equivalent values ​​and lengths greater than the corresponding lengths of the carbonaceous coating. Thus, the length "L" of the assembly 10 in this embodiment is effectively the distance between the outermost edges of the separators. For example, the length "L" may be about 5 to about 100 millimeters, about 8 to about 60 millimeters in some embodiments, and about 10 to about 25 millimeters in some embodiments. The first current collector 20 is arranged to have a first protruding portion 64 that projects beyond the longitudinal edge 21 of the assembly 10. Similarly, the second current collector 40 is arranged to have a second protruding portion 62 that projects beyond the longitudinal edge 41 of the assembly 10. For example, the length "L1" of the first protruding portion 64, the length "L2" of the second protruding portion 62, or both, may be about 1 to about 20 millimeters, about 2 to about 16 millimeters in some embodiments, or about 5 to about 15 millimeters in some embodiments. In the illustrated embodiment, the projection of the current collector is achieved by using a current collector having a length greater than the corresponding carbonaceous coating. However, the projection of the current collector can also be achieved by simply offsetting the current collector relative to the other parts of the assembly.

[0022] II. Nonaqueous electrolytes: To form an ultracapacitor, the electrolyte is placed in ionic contact with the first and second electrodes before, during, and / or after, assembling the electrodes and separators to form the electrode assembly. The electrolyte is generally non-aqueous and therefore contains at least one non-aqueous solvent. To help extend the operating temperature range of the ultracapacitor, the non-aqueous solvent is typically rated at about 150°C or higher, and in some embodiments at about 200°C or higher. In that embodiment, it is desirable to have a relatively high boiling point, such as about 220°C to about 300°C. Particularly suitable high-boiling point solvents include, for example, cyclic carbonate solvents such as ethylene carbonate, propylene carbonate, butylene carbonate, and vinylene carbonate. Of course, other non-aqueous solvents can also be used alone or in combination with cyclic carbonate solvents. Examples of such solvents include, for example, open-chain carbonates (e.g., dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, etc.), aliphatic monocarboxylates (e.g., methyl acetate, methyl propionate, etc.), lactone solvents (e.g., butyrolactone, valerolactone, etc.), nitriles (e.g., acetonitrile, glutaronitrile, adiponitrile, methoxyacetonitrile, 3-methoxypropionitrile, etc.), amides (e.g., N,N-dimethylformamide, N,N-diethylacetamide, N-methylpyrrolidinone), alkanes (e.g., nitromethane, nitroethane, etc.), and sulfur compounds (e.g., sulfolane, dimethyl sulfoxide, etc.).

[0023] The electrolyte may also contain at least one ionic liquid dissolved in a non-aqueous solvent. The concentration of the ionic liquid can be varied, but it is generally desirable to have the ionic liquid present at a relatively high concentration. For example, the ionic liquid may be present in an amount of about 0.8 moles (M) or more per liter of electrolyte, about 1.0 M or more in some embodiments, about 1.2 M or more in some embodiments, and about 1.3 to about 1.8 M in some embodiments.

[0024] Ionic liquids are generally salts with relatively low melting points, such as about 400°C or less, about 350°C or less in some embodiments, about 1°C to about 100°C in some embodiments, and about 5°C to about 50°C in some embodiments. Salts contain cation species and counterions. Cationic species include compounds having at least one heteroatom (e.g., nitrogen or phosphorus) as a "cation center". Examples of such heteroatom compounds include, for example, Examples of unsubstituted or substituted organic quaternary ammonium compounds include ammonium (e.g., trimethylammonium, tetraethylammonium, etc.), pyridinium, pyridazinium, pyramidinium, pyrazinium, imidazolium, pyrazorium, oxazolium, triazolium, thiazolium, quinolinium, piperidinium, pyrrolidinium, quaternary ammonium spiro compounds (where two or more rings are bonded together by a spiro atom (e.g., carbon, heteroatom, etc.)), and quaternary ammonium condensed ring structures (e.g., quinolinium, isoquinolinium, etc.). For example, in one particular embodiment, the cationic species may be an N-spironicyclic compound, such as a symmetric or asymmetric N-spironicyclic compound having a cyclic ring. An example of such a compound has the following structure:

[0025] [ka]

[0026] (In the formula, m and n are independently numbers from 3 to 7, and in some embodiments from 4 to 5.) It contains (for example, pyrrolidinium or piperidinium).

[0027] Furthermore, suitable counterions for cationic species include halogens (e.g., chlorides, bromides, iodides, etc.); sulfates or sulfonates (e.g., methyl sulfate, ethyl sulfate, Butyl sulfate, hexyl sulfate, octyl sulfate, hydrogen sulfate, methanesulfonate, dodecylbenzenesulfonate, dodecyl sulfate, trifluoromethanesulfonate, heptadecafluorooctanesulfonate, sodium dodecylethoxysulfate, etc.); sulfosuccinates; amides (e.g., dicyanamide); imides (e.g., bis(pentafluoroethylsulfonyl)imide, bis(trifluoromethylsulfonyl)imide, bis(trifluoromethyl)imide, etc.); borates (e.g., tetrafluoroborate, tetracyanoborate, bis[oxalato]borate, bis[s]) Examples include lithylate borate, etc.); phosphates or phosphinates (e.g., hexafluorophosphate, diethyl phosphate, bis(pentafluoroethyl) phosphinate, tris(pentafluoroethyl) trifluorophosphate, tris(nonafluorobutyl) trifluorophosphate, etc.); antimonates (e.g., hexafluoroantimonate); aluminates (e.g., tetrachloroaluminate); fatty acid carboxylates (e.g., oleate, isostearate, pentadecafluorooctanoate, etc.); cyanates, acetates, etc., as well as any combination of the above.

[0028] Some examples of suitable ionic liquids include, for example, spiro-(1,1')-bipyrrolidinium tetrafluoroborate, triethylmethylammonium tetrafluoroborate, tetraethylammonium tetrafluoroborate, spiro-(1,1')-bipyrrolidinium iodide, triethylmethylammonium iodide, tetraethylammonium iodide, methyltriethylammonium tetrafluoroborate, tetrabutylammonium tetrafluoroborate, and tetraethylammonium hexafluorophosphate.

[0029] III. Housing: The ultracapacitor may also include a housing in which the electrode assembly and electrolyte are held and optionally hermetically sealed. The properties of the housing can be varied as desired. For example, in one embodiment, the housing may include a metal container (can) formed from tantalum, niobium, aluminum, nickel, hafnium, titanium, copper, silver, steel (e.g., stainless steel), alloys thereof, or composites thereof (e.g., metals coated with conductive oxides). Aluminum is particularly suitable for use in the present invention. The metal container may have any various different shapes, such as cylindrical or D-shaped. A cylindrical container is particularly preferred.

[0030] Referring to Figures 3 and 4, one embodiment of a housing that can be used in an ultracapacitor is shown in more detail. In this particular embodiment, the housing includes a metal container 2122 (e.g., a cylindrical can) defining a base 3000 and an open end 3200. A lid 2118 is placed over the open end 3200 and attached to (e.g., welded) to the container 2122 to seal the housing. In one particular embodiment, as shown in Figure 4, the lid 2118 may include a first current collector disk 2114 comprising a disk-shaped portion 2134, a stud portion 2136, and fasteners 2138 (e.g., screws). The current collector disk 2114 is aligned with the first end of the hollow core 2160 formed in the center of the electrode assembly 10, and then the stud portion 2136 is inserted into the opening of the core such that the first current collector disk 2114 (e.g., the disk-shaped portion 2134 and / or the stud portion 2136) contacts the second protruding portion 62 of the second current collector 40. In this way, the second current collector 40 is positioned in electrical contact with the lid 2118. The fastener 2138 may also be coupled (e.g., screw-coupled) to the first terminal 2116. Alternatively, the metal container 2122 may contain the second current collector disk 2120, which includes the disk-shaped portion 2142, the stud portion 2140, and the second terminal 2144. The second current collector disk 2120 is aligned with the second end of the hollow core 2160, and then the stud portion 2140 is aligned with the second current collector disk 2120 (for example, the disk-shaped portion) Insert the protruding portion 62 and / or stud portion 64) into the opening of the core so that it contacts the first projection portion 64 of the first current collector 20. In this way, the first current collector 20 is positioned in electrical contact with the base 3000. Although not specifically shown in Figures 3-4, the length of the protruding portion 62 and / or 64 can be folded or otherwise deformed when in contact with the current collector disk.

[0031] Test method: Equivalent series resistance (ESR): The equivalent series resistance was measured using a Keithley 3330 Precision LCZ meter, at 0.0 volts and 1.1 volts. Measurements can be taken using a DC bias of volts or 2.1 volts (a 0.5 volt peak-to-peak sine wave signal). The operating frequency is 100 kHz. Various temperature and relative humidity levels can be tested. For example, the temperature may be 25°C, 85°C, or 105°C, and the relative humidity may be 25% or 85%.

[0032] capacitance: Capacitance was measured using a Keithley 3330 Precision LCZ meter, at 0.0 volts, 1 volt. Measurements can be taken using a DC bias of 1 volt or 2.1 volts (0.5 volt peak-to-peak sine wave signal). The operating frequency is 120 Hz. Various temperature and relative humidity levels can be tested. For example, the temperature may be 25°C, 85°C, or 105°C, and the relative humidity may be 25% or 85%.

[0033] These and other modifications and variations of the present invention can be practiced by those skilled in the art without departing from the spirit and scope of the invention. Furthermore, it should be understood that multiple aspects of the various embodiments can be replaced in whole or in part. Moreover, those skilled in the art will understand that the above description is merely illustrative and is not intended to limit the invention to what is further described in the appended claims. The present invention includes the following embodiments. [1] An electrode assembly for an ultracapacitor defining the length between opposing first longitudinal edge and second longitudinal edge, wherein the electrode assembly comprises: A first electrode comprising a first current collector electrically coupled to a first carbonaceous coating, wherein at least a portion of the first current collector protrudes beyond the first longitudinal edge, defining a first protruding portion, and the offset ratio of the first protruding portion is approximately 0.02 to approximately 0.3; A second electrode including a second current collector electrically coupled to a second carbonaceous coating; and A separator positioned between the first electrode and the second electrode; The electrode assembly including the above. [2] The electrode assembly according to [1], wherein at least a portion of the second current collector protrudes beyond the second longitudinal edge to define a second protruding portion, the offset ratio of the second protruding portion being about 0.02 to about 0.3. [3] The electrode assembly according to [1] or [2], wherein the length of the first projection, the second projection, or both is approximately 1 to approximately 20 millimeters. [4] The electrode assembly according to [1], wherein the length of the electrode assembly is approximately 5 to approximately 100 millimeters. [5] The electrode assembly according to [1], wherein the electrode assembly has a jelly roll structure. [6] The electrode assembly according to [1], wherein the first current collector and the second current collector each include a substrate containing a conductive metal. [7] The electrode assembly according to [6], wherein the conductive metal is aluminum or an alloy thereof. [8] The electrode assembly according to [1], wherein the first carbonaceous coating, the second carbonaceous coating, or both comprises activated carbon particles. [9] The electrode assembly according to [1], wherein the separator comprises a cellulose fiber material. An ultracapacitor comprising an electrode assembly as described in any of

[10] [1] to [9], and a non-aqueous electrolyte in ionic contact with the first electrode and the second electrode.

[11] The ultracapacitor according to

[10] , comprising an ionic liquid in which the nonaqueous electrolyte is dissolved in a nonaqueous solvent, wherein the ionic liquid comprises a cation species and a counterion.

[12] The ultracapacitor according to

[11] , wherein the non-aqueous solvent comprises propylene carbonate, a nitrile, or a combination thereof.

[13] The ultracapacitor according to

[11] , wherein the cation species comprises an organic quaternary ammonium compound.

[14] The organic quaternary ammonium compound has the following structure:

change

[13] , having the following characteristics.

[15] The ultracapacitor according to

[11] , wherein the ionic liquid is present at a concentration of approximately 1.0 M or higher.

[16] The ultracapacitor according to

[10] , wherein the ultracapacitor exhibits an ESR of approximately 100 milliohms or less when measured at a frequency of 100 kHz and a temperature of 25°C.

[17] The ultracapacitor according to

[10] , wherein the ultracapacitor exhibits a capacitance value of approximately 6 farads / cm² or more when determined at a frequency of 120 Hz and a temperature of 25°C.

[18] The ultracapacitor according to

[10] , comprising a housing including a container having a base and an open end, wherein a lid is positioned adjacent to the open end, and further comprising the electrode assembly positioned such that the first protruding portion is in electrical contact with the base or the lid.

[19] The ultracapacitor according to

[18] , wherein at least a portion of the second current collector protrudes beyond the second longitudinal edge to define a second protruding portion, the offset ratio of the second protruding portion being about 0.02 to about 0.3.

[20] The ultracapacitor according to

[19] , wherein the first protruding portion is in electrical contact with the base and the second protruding portion is in electrical contact with the lid.

[21] The ultracapacitor according to

[18] , wherein the container is formed from metal.

[22] The ultracapacitor according to

[18] , wherein the container has a cylindrical shape.

Claims

1. An ultracapacitor comprising an electrode assembly and a non-aqueous electrolyte in ionic contact with a first electrode and a second electrode, The electrode assembly defines the length between the opposing first longitudinal edge and the second longitudinal edge, and the electrode assembly The first electrode comprising a first current collector electrically coupled to a first carbonaceous coating containing activated carbon, wherein the first current collector comprises a substrate containing a conductive metal, and at least a portion of the first current collector protrudes beyond the first longitudinal edge to define a first protruding portion, the offset ratio of the first protruding portion being 0.05 to 0.3; The second electrode comprises a second current collector electrically coupled to a second carbonaceous coating containing activated carbon, wherein the second current collector comprises a substrate containing a conductive metal, and at least a portion of the second current collector protrudes beyond the second longitudinal edge to define a second protruding portion, the offset ratio of the second protruding portion being 0.05 to 0.3, and the length of the first protruding portion, the second protruding portion, or both being 1 to 20 millimeters; and A separator positioned between the first electrode and the second electrode; Includes, The length of the electrode assembly is 5 to 100 millimeters. The aforementioned ultracapacitor exhibits an ESR of 100 milliohms or less when measured at a frequency of 100 kHz and a temperature of 25°C. The ultracapacitor comprises a housing including a container having a base and an open end, a lid positioned adjacent to the open end, and further, the electrode assembly is positioned within the housing such that the first protruding portion is in electrical contact with the base or the lid.

2. The ultracapacitor according to claim 1, wherein the offset ratio of the first protruding portion is 0.05 to 0.2, and / or the offset ratio of the second protruding portion is 0.05 to 0.

2.

3. The ultracapacitor according to claim 1 or 2, wherein the length of the first protruding portion, the second protruding portion, or both is 2 to 16 millimeters.

4. The ultracapacitor according to claim 1, wherein the electrode assembly has a jelly roll structure.

5. The ultracapacitor according to claim 1, wherein the conductive metal is aluminum or an alloy thereof.

6. The ultracapacitor according to claim 1, wherein the separator includes a cellulose fiber material.

7. The ultracapacitor according to claim 1, wherein the nonaqueous electrolyte comprises an ionic liquid in which the nonaqueous electrolyte is dissolved in a nonaqueous solvent, and the ionic liquid comprises a cation species and a counterion.

8. The ultracapacitor according to claim 7, wherein the non-aqueous solvent comprises propylene carbonate, a nitrile, or a combination thereof.

9. The ultracapacitor according to claim 7, wherein the cation species comprises an organic quaternary ammonium compound.

10. The aforementioned organic quaternary ammonium compound has the following structure: 【Chemistry 1】 (In the formula, m and n are independently numbers between 3 and 7.) The ultracapacitor according to claim 9, having the following characteristics.

11. The ultracapacitor according to claim 7, wherein the ionic liquid is present at a concentration of 1.0 M or higher.

12. The ultracapacitor according to claim 1, wherein the ultracapacitor exhibits a capacitance value of 6 farads / cm² or more when determined at a frequency of 120 Hz and a temperature of 25°C.

13. The ultracapacitor according to claim 1, wherein the first protruding portion is in electrical contact with the base portion, and the second protruding portion is in electrical contact with the lid.

14. The ultracapacitor according to claim 1, wherein the container is formed from metal.

15. The ultracapacitor according to claim 1, wherein the container has a cylindrical shape.

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