WO1998006115A1 - Separateurs de condensateur electrolytique a haute resistance, condensateurs les incorporant et leur procede de fabrication - Google Patents
Separateurs de condensateur electrolytique a haute resistance, condensateurs les incorporant et leur procede de fabrication Download PDFInfo
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- WO1998006115A1 WO1998006115A1 PCT/AU1996/000491 AU9600491W WO9806115A1 WO 1998006115 A1 WO1998006115 A1 WO 1998006115A1 AU 9600491 W AU9600491 W AU 9600491W WO 9806115 A1 WO9806115 A1 WO 9806115A1
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- Prior art keywords
- group
- electrolyte
- salt
- ammonium
- weight
- Prior art date
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- 239000003990 capacitor Substances 0.000 title claims abstract description 94
- 238000000034 method Methods 0.000 title claims abstract description 59
- 239000003792 electrolyte Substances 0.000 claims abstract description 120
- 238000003860 storage Methods 0.000 claims abstract description 31
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical group OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 claims description 75
- 150000003839 salts Chemical class 0.000 claims description 45
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 43
- 239000002655 kraft paper Substances 0.000 claims description 38
- 125000006850 spacer group Chemical group 0.000 claims description 35
- HCLJOFJIQIJXHS-UHFFFAOYSA-N 2-[2-[2-(2-prop-2-enoyloxyethoxy)ethoxy]ethoxy]ethyl prop-2-enoate Chemical compound C=CC(=O)OCCOCCOCCOCCOC(=O)C=C HCLJOFJIQIJXHS-UHFFFAOYSA-N 0.000 claims description 32
- 239000000203 mixture Substances 0.000 claims description 31
- 239000004014 plasticizer Substances 0.000 claims description 28
- ZMXDDKWLCZADIW-UHFFFAOYSA-N N,N-Dimethylformamide Chemical compound CN(C)C=O ZMXDDKWLCZADIW-UHFFFAOYSA-N 0.000 claims description 27
- MTHSVFCYNBDYFN-UHFFFAOYSA-N diethylene glycol Chemical compound OCCOCCO MTHSVFCYNBDYFN-UHFFFAOYSA-N 0.000 claims description 27
- 229920000642 polymer Polymers 0.000 claims description 27
- 239000007788 liquid Substances 0.000 claims description 25
- 239000000178 monomer Substances 0.000 claims description 25
- 150000001875 compounds Chemical class 0.000 claims description 21
- 239000002253 acid Substances 0.000 claims description 20
- 239000003431 cross linking reagent Substances 0.000 claims description 20
- 239000002904 solvent Substances 0.000 claims description 20
- KAKZBPTYRLMSJV-UHFFFAOYSA-N Butadiene Chemical group C=CC=C KAKZBPTYRLMSJV-UHFFFAOYSA-N 0.000 claims description 18
- IAZDPXIOMUYVGZ-UHFFFAOYSA-N Dimethylsulphoxide Chemical compound CS(C)=O IAZDPXIOMUYVGZ-UHFFFAOYSA-N 0.000 claims description 18
- FLDCSPABIQBYKP-UHFFFAOYSA-N 5-chloro-1,2-dimethylbenzimidazole Chemical compound ClC1=CC=C2N(C)C(C)=NC2=C1 FLDCSPABIQBYKP-UHFFFAOYSA-N 0.000 claims description 15
- 239000001741 Ammonium adipate Substances 0.000 claims description 15
- 235000019293 ammonium adipate Nutrition 0.000 claims description 15
- OKUGAOMPLZNWRT-UHFFFAOYSA-N diazanium;pentanedioate Chemical compound [NH4+].[NH4+].[O-]C(=O)CCCC([O-])=O OKUGAOMPLZNWRT-UHFFFAOYSA-N 0.000 claims description 13
- QGZKDVFQNNGYKY-UHFFFAOYSA-O Ammonium Chemical compound [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 0.000 claims description 11
- 150000003863 ammonium salts Chemical class 0.000 claims description 10
- 229940068918 polyethylene glycol 400 Drugs 0.000 claims description 10
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical group [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 9
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical class [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 claims description 9
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical class [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 claims description 9
- 150000007513 acids Chemical class 0.000 claims description 9
- 229910052783 alkali metal Inorganic materials 0.000 claims description 9
- 150000001340 alkali metals Chemical class 0.000 claims description 9
- 229910052784 alkaline earth metal Inorganic materials 0.000 claims description 9
- 150000001342 alkaline earth metals Chemical class 0.000 claims description 9
- 125000000217 alkyl group Chemical group 0.000 claims description 9
- 150000001661 cadmium Chemical class 0.000 claims description 9
- 238000010276 construction Methods 0.000 claims description 9
- 125000004386 diacrylate group Chemical group 0.000 claims description 9
- 239000001257 hydrogen Chemical group 0.000 claims description 9
- 229910052739 hydrogen Chemical group 0.000 claims description 9
- 239000011159 matrix material Substances 0.000 claims description 9
- -1 polypropylene Polymers 0.000 claims description 9
- RUOJZAUFBMNUDX-UHFFFAOYSA-N propylene carbonate Chemical compound CC1COC(=O)O1 RUOJZAUFBMNUDX-UHFFFAOYSA-N 0.000 claims description 9
- 229910052718 tin Inorganic materials 0.000 claims description 9
- 229910052723 transition metal Inorganic materials 0.000 claims description 9
- 150000003624 transition metals Chemical class 0.000 claims description 9
- 229910052725 zinc Inorganic materials 0.000 claims description 9
- 239000011701 zinc Chemical class 0.000 claims description 9
- 229920002338 polyhydroxyethylmethacrylate Polymers 0.000 claims description 8
- 238000006116 polymerization reaction Methods 0.000 claims description 8
- 229940044192 2-hydroxyethyl methacrylate Drugs 0.000 claims description 7
- WOBHKFSMXKNTIM-UHFFFAOYSA-N Hydroxyethyl methacrylate Chemical compound CC(=C)C(=O)OCCO WOBHKFSMXKNTIM-UHFFFAOYSA-N 0.000 claims description 7
- 239000004744 fabric Substances 0.000 claims description 7
- OMIGHNLMNHATMP-UHFFFAOYSA-N 2-hydroxyethyl prop-2-enoate Chemical compound OCCOC(=O)C=C OMIGHNLMNHATMP-UHFFFAOYSA-N 0.000 claims description 6
- 229920001577 copolymer Polymers 0.000 claims description 6
- 229940095095 2-hydroxyethyl acrylate Drugs 0.000 claims description 5
- 239000004698 Polyethylene Substances 0.000 claims description 5
- 239000004743 Polypropylene Substances 0.000 claims description 5
- 229920001155 polypropylene Polymers 0.000 claims description 5
- 125000000391 vinyl group Chemical group [H]C([*])=C([H])[H] 0.000 claims description 5
- 229920002554 vinyl polymer Polymers 0.000 claims description 5
- 229920000573 polyethylene Polymers 0.000 claims description 4
- 238000007614 solvation Methods 0.000 claims description 3
- 229920006037 cross link polymer Polymers 0.000 claims 8
- NIXOWILDQLNWCW-UHFFFAOYSA-N acrylic acid group Chemical group C(C=C)(=O)O NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 claims 4
- WHNWPMSKXPGLAX-UHFFFAOYSA-N N-Vinyl-2-pyrrolidone Chemical compound C=CN1CCCC1=O WHNWPMSKXPGLAX-UHFFFAOYSA-N 0.000 claims 3
- PNJWIWWMYCMZRO-UHFFFAOYSA-N pent‐4‐en‐2‐one Natural products CC(=O)CC=C PNJWIWWMYCMZRO-UHFFFAOYSA-N 0.000 claims 3
- JFCQEDHGNNZCLN-UHFFFAOYSA-N glutaric acid Chemical compound OC(=O)CCCC(O)=O JFCQEDHGNNZCLN-UHFFFAOYSA-N 0.000 claims 2
- WROUWQQRXUBECT-UHFFFAOYSA-N 2-ethylacrylic acid Chemical compound CCC(=C)C(O)=O WROUWQQRXUBECT-UHFFFAOYSA-N 0.000 claims 1
- 229920001730 Moisture cure polyurethane Polymers 0.000 claims 1
- 239000005518 polymer electrolyte Substances 0.000 claims 1
- 229920000136 polysorbate Polymers 0.000 claims 1
- 239000000463 material Substances 0.000 abstract description 18
- 229910052782 aluminium Inorganic materials 0.000 abstract description 11
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 abstract description 11
- 238000004146 energy storage Methods 0.000 abstract description 8
- 230000006872 improvement Effects 0.000 abstract description 5
- 239000000306 component Substances 0.000 description 26
- 239000000123 paper Substances 0.000 description 22
- 239000011888 foil Substances 0.000 description 13
- 239000011244 liquid electrolyte Substances 0.000 description 8
- 239000000243 solution Substances 0.000 description 8
- 239000000126 substance Substances 0.000 description 7
- ROOXNKNUYICQNP-UHFFFAOYSA-N ammonium peroxydisulfate Substances [NH4+].[NH4+].[O-]S(=O)(=O)OOS([O-])(=O)=O ROOXNKNUYICQNP-UHFFFAOYSA-N 0.000 description 5
- VAZSKTXWXKYQJF-UHFFFAOYSA-N ammonium persulfate Chemical compound [NH4+].[NH4+].[O-]S(=O)OOS([O-])=O VAZSKTXWXKYQJF-UHFFFAOYSA-N 0.000 description 5
- 229910001870 ammonium persulfate Inorganic materials 0.000 description 5
- 230000000747 cardiac effect Effects 0.000 description 4
- 239000003795 chemical substances by application Substances 0.000 description 4
- 238000005470 impregnation Methods 0.000 description 4
- 239000003505 polymerization initiator Substances 0.000 description 4
- 230000009467 reduction Effects 0.000 description 4
- 230000035882 stress Effects 0.000 description 4
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 3
- 239000007767 bonding agent Substances 0.000 description 3
- 238000001816 cooling Methods 0.000 description 3
- 229920001971 elastomer Polymers 0.000 description 3
- 239000000806 elastomer Substances 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 239000001301 oxygen Substances 0.000 description 3
- 229910052760 oxygen Inorganic materials 0.000 description 3
- 238000003756 stirring Methods 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical class [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- MZRVEZGGRBJDDB-UHFFFAOYSA-N N-Butyllithium Chemical compound [Li]CCCC MZRVEZGGRBJDDB-UHFFFAOYSA-N 0.000 description 2
- 239000000853 adhesive Substances 0.000 description 2
- 230000001070 adhesive effect Effects 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 238000013461 design Methods 0.000 description 2
- 239000003999 initiator Substances 0.000 description 2
- 230000000977 initiatory effect Effects 0.000 description 2
- 239000012528 membrane Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 239000012047 saturated solution Substances 0.000 description 2
- 238000007789 sealing Methods 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 239000007784 solid electrolyte Substances 0.000 description 2
- NIXOWILDQLNWCW-UHFFFAOYSA-M Acrylate Chemical compound [O-]C(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-M 0.000 description 1
- 239000004342 Benzoyl peroxide Substances 0.000 description 1
- OMPJBNCRMGITSC-UHFFFAOYSA-N Benzoylperoxide Chemical compound C=1C=CC=CC=1C(=O)OOC(=O)C1=CC=CC=C1 OMPJBNCRMGITSC-UHFFFAOYSA-N 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical class [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 241001137251 Corvidae Species 0.000 description 1
- 239000004971 Cross linker Substances 0.000 description 1
- DWAQJAXMDSEUJJ-UHFFFAOYSA-M Sodium bisulfite Chemical class [Na+].OS([O-])=O DWAQJAXMDSEUJJ-UHFFFAOYSA-M 0.000 description 1
- 239000000370 acceptor Substances 0.000 description 1
- 239000002390 adhesive tape Substances 0.000 description 1
- 230000032683 aging Effects 0.000 description 1
- 125000001931 aliphatic group Chemical group 0.000 description 1
- 239000010405 anode material Substances 0.000 description 1
- 239000012298 atmosphere Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 235000019400 benzoyl peroxide Nutrition 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 229940000425 combination drug Drugs 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 229910052802 copper Chemical class 0.000 description 1
- 239000010949 copper Chemical class 0.000 description 1
- 238000004132 cross linking Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 230000001627 detrimental effect Effects 0.000 description 1
- 150000001991 dicarboxylic acids Chemical class 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000007772 electrode material Substances 0.000 description 1
- 238000011010 flushing procedure Methods 0.000 description 1
- 238000009472 formulation Methods 0.000 description 1
- 238000002513 implantation Methods 0.000 description 1
- 238000011065 in-situ storage Methods 0.000 description 1
- 239000003112 inhibitor Substances 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 1
- 150000002978 peroxides Chemical class 0.000 description 1
- JRKICGRDRMAZLK-UHFFFAOYSA-L persulfate group Chemical group S(=O)(=O)([O-])OOS(=O)(=O)[O-] JRKICGRDRMAZLK-UHFFFAOYSA-L 0.000 description 1
- 235000015108 pies Nutrition 0.000 description 1
- 229920006254 polymer film Polymers 0.000 description 1
- 230000000379 polymerizing effect Effects 0.000 description 1
- USHAGKDGDHPEEY-UHFFFAOYSA-L potassium persulfate Chemical compound [K+].[K+].[O-]S(=O)(=O)OOS([O-])(=O)=O USHAGKDGDHPEEY-UHFFFAOYSA-L 0.000 description 1
- 150000003254 radicals Chemical class 0.000 description 1
- 238000005057 refrigeration Methods 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 239000004289 sodium hydrogen sulphite Chemical class 0.000 description 1
- 235000010267 sodium hydrogen sulphite Nutrition 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 230000002522 swelling effect Effects 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- YONPGGFAJWQGJC-UHFFFAOYSA-K titanium(iii) chloride Chemical compound Cl[Ti](Cl)Cl YONPGGFAJWQGJC-UHFFFAOYSA-K 0.000 description 1
- VOITXYVAKOUIBA-UHFFFAOYSA-N triethylaluminium Chemical compound CC[Al](CC)CC VOITXYVAKOUIBA-UHFFFAOYSA-N 0.000 description 1
- 238000004804 winding Methods 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
- H01G9/00—Electrolytic capacitors, rectifiers, detectors, switching devices, light-sensitive or temperature-sensitive devices; Processes of their manufacture
- H01G9/004—Details
- H01G9/02—Diaphragms; Separators
Definitions
- This invention relates to electrical energy storage devices such as electrolytic capacitors and batteries. More particularly, although not necessarily limited to such, it relates to electrolytic capacitors which utilize an elastomeric electrolyte and to methods of making such capacitors. Even more particularly, it relates to separator materials for use in aluminum electrolytic capacitors, and to methods of making elastomeric electrolytes that are compatible with such separator materials and act to strengthen them. A major feature of these capacitors is that they are able to employ separator materials of reduced thickness. The invention finds particular suitability for use in implantable biomedical electronic devices such as cardiac pacemakers and defibrillators.
- Cardiac defibrillators and pacemakers are commonly designed to be implanted within a human patient.
- Such cardiac defibrillators include an electrical energy storage component as part of a power supply designed to provide repeated burst discharges of several joules of electrical energy.
- Cardiac pacemakers include similar storage components designed to supply lower energy bursts but much more frequently. Both devices therefore require energy storage components of large capacity in order to reduce the number of occasions on which the device must be explanted to renew its energy storage component. It is therefore advantageous that the energy storage component be both compact and capable of large energy storage.
- the energy storage component can be configured to the shape of the overall device, which is typically a flat, disc-shaped configuration to facilitate implantation subcutaneously in the patient. It is well known that aluminum electrolytic capacitors have some properties that are suited for this purpose. Nevertheless, attempts to minimize the volume of electrolytic capacitors have met with only limited success.
- a capacitor of this type conventionally includes an etched aluminum foil anode, an aluminum foil or film cathode, and an interposed Kraft paper or fabric gauze separator impregnated with a solvent-based liquid electrolyte.
- the electrolytic or ion-producing component of the electrolyte is a salt that is dissolved in the solvent.
- the electrolyte thus provides ionic electrical conductivity from the cathode to an oxide layer that is typically formed on the aluminum anode and that functions as a dielectric layer between the anode and the cathode.
- the entire laminate is rolled up into the form of a substantially cylindrical body that is held together with adhesive tape and is encased, with the aid of suitable insulation, in an aluminum tube or canister. Connections to the anode and the cathode are made via tabs.
- Alternative flat constructions for aluminum electrolytic capacitors are also known, comprising a planar, layered structure of electrode materials with separators interposed therebetween. Regardless of their ultimate shape and configuration, electrolytic capacitors that employ a conventional liquid electrolyte are subject to leakage, which can damage electrical components and lead to failure of the device. Sealing the device hermetically is not an adequate solution of this problem because of gases that may build up within the device.
- Expansion chambers adapted to receive the gases have been provided to deal with such problems, but that has led to the disadvantage of even a larger size of the capacitor.
- a liquid electrolyte commonly causes the aluminum oxide dielectric layer on the aluminum anode to de-form, and although the potential across the electrodes can result in currents that re-form the oxide layer, the de-formation results in a shorter lifetime of the formed oxide layer.
- Electrolytic capacitors that employ a conventional liquid electrolyte are also inherently relatively thick. This is due, in part, to the thickness of the mechanical separator, which is typically made of Kraft paper that is impregnated with and acts as a reservoir for the electrolyte. In order to be conductive the paper must be swollen by the electrolyte, but this swelling action also makes the paper more weak and pliable. Its tensile strength is also much reduced. Thus, in order to prevent a short-circuit, the integrity of the prior art separators must be maintained by assuring that they are relatively thick. In the prior art electrolytic capacitors of the high-voltage "photoflash" type, the separators are generally no less than about 40 microns thick, and are typically made of two layers of 20 ⁇ -thick Kraft paper.
- U.S. Patent No. 3,555,369 proposed to reduce the volume of electrolytic capacitors by replacing the Kraft paper separator with a semipermeable membrane of a polymeric material.
- this required that the membrane be impregnated with a solvent-based liquid electrolyte, requiring the hermetic sealing and the provision of expansion chambers to deal with the gas generated, and left unsolved the problem of the de-forming of the oxide layer of the capacitor.
- U.S. Patent No. 3,883,784 proposed to produce capacitors employing a polymeric material having ionic acceptors and ionic donors. This patent suggested interposing the polymeric material in a film in place of the Kraft paper separator. Since the film was in fact thicker than the paper it was intended to replace, it did not contribute to a reduction in the size of the capacitor.
- the preferred method of constructing these capacitors is to deposit a liquid prepolymer electrolyte mixture onto the surface of the anode, and then to cause polymerization to take place to cure the electrolyte.
- the cathode is thereafter formed by deposition upon the surface of the cured electrolyte layer.
- these capacitors are more costly to manufacture than those employing conventional liquid electrolytes, since they require formation of the cathode by means of non-conventional coating equipment, thus requiring substantial capital investment.
- Japanese Patent Application No. JP 4-184811 also discloses a solid polymer film having both ionic and electronic conductivity which is suitable for use as an electrolyte for electrolytic capacitors, provided that it is integrated with a mechanical separator, such as Kraft paper or a porous film or a fabric, so as to increase the mechanical and physical strength of the solid electrolyte.
- a mechanical separator such as Kraft paper or a porous film or a fabric
- the objectives of the present invention are attained by utilizing, between the anode and cathode of an electrolytic capacitor, a spacer comprised ' of mechanical separator means such as Kraft paper that is less than 40 ⁇ thick and that is impregnated with an elastomeric ' electrolyte comprised of a solution of at least one salt in a crosslinked elastomeric solvent.
- the electrolyte is formed by polymerizing a liquid prepolymer electrolyte mixture containing the salt(s) , a plasticizer, at least one poly erizable monomer, a cross- linking agent and a polymerization initiator.
- this mixture may also include water.
- the cross- linked elastomeric electrolytes described herein are compatible with the Kraft paper or other mechanical separator, act to swell it and make it conductive, but once cured also act to improve its tensile strength.
- the total thickness of the paper or other separator material used can be reduced, such that an improvement in the energy density of the capacitor is achieved.
- An improvement in internal resistance is also achieved, other things being equal.
- the life of the capacitor is also improved.
- FIG. 1 is a graph showing the results of a stress/strain analysis that was performed with respect to both a capacitor according to the invention and another capacitor of the same specifications but utilizing a prior art electrolyte.
- a low volume, high capacity aluminum electrolytic capacitor may be advantageously constructed in accordance with the invention by interposing, between the electrically conductive anode and cathode layer(s) thereof, a spacer comprised of mechanical separator means that is of reduce thickness as compared with the prior art, and that is impregnated with a crosslinked elastomeric electrolyte of the type described herein.
- electrolytes which are the subject of this invention are based on a polymeric component which is plasticized by a low molecular weight liquid such as ethylene glycol.
- these electrolytes contain:
- a polymeric component comprising at least one long chain polymer which is miscible with the other liquid compo- nents of the electrolyte and which is crosslinked by the addition of a crosslinker and which is compatible with the mechanical separator means and which is also compatible with and preferably a solvent for the salt component of the electrolyte;
- a liquid plasticizer of low molecular weight which is miscible with the polymeric component (in both its monomer and polymerized forms) and which is a good solvent for the salt component of the electrolyte;
- an ionic salt an ionic salt; and (iv) between 0 and 50% by weight of water.
- the polymeric component is chosen so as to include polar groups capable of imparting high solvation power to the polymer.
- Typical polymeric components that are preferred include polymers of the general structure:
- polyhydroxyethylmethacrylate and poly- hydroxyethylacrylate are most preferred.
- other long chain polymers may be utilized, including polyvinyl- pyrrolidinone, polyvinylsulfonic acid and other vinyl, acrylate and alkacrylate polymers.
- copolymers of two or more of the foregoing polymers are also of utility in this invention.
- the electrolytes are crosslinked by inclusion in the prepolymer mixture of an agent capable of crosslinking the polymer component (s) .
- the crosslinking agent may be a difunc- tional monomer, for example a divinyl or diacrylate or dialkacrylate compound. The content of this group will determine the tensile strength of the spacer materials ultimately obtained.
- the crosslinking agent can be present at concentrations in the range of from 0.015 to 20% by mole, but preferably in the range 1-4% by mole, calculated on the basis of the total of only the polymerizable components of the electrolyte.
- the liquid plasticizer of low molecular weight is ethylene glycol, although other plasticizers such as polyethylene glycol 400, propylene carbonate, dimethyl formamide, dimethylsulfoxide, diethylene glycol and any of the other liquids that are well known in the capacitor electrolyte field may be utilized instead.
- the content of the plasticizer in the electrolyte can be as high as 80% by weight, but such materials have lower strength than materials having a plasti- cizer content in the region of 30-70%.
- the electrolyte may generally contain up to 50% by weight of water, this maximum applies primarily to low-voltage capacitors (i.e., those with a working voltage that is less than 250V) ; for high-voltage capacitors, it is desirable to limit the amount of water in the electrolyte to no more than about 15% by weight.
- the water component of the electrolyte optionally can be omitted completely, a minimum water content of about 4% by weight is preferable, regardless of the desired working voltage of the resulting capacitor. Water can be beneficial in that it can increase the conductivity of the electrolyte and decrease the failure rate during initial ageing. On the other hand, the use of too much water can increase the leakage current of the capacitor and accordingly can be detrimental to performance.
- the electrolyte of the invention contains about 6% water, and it may be introduced by admixing the appropriate amount of water with the liquid plasticizer component of the electrolyte prior to utilization of the plasticizer.
- the salt may be chosen from any of the ionic salts that have heretofore been utilized in electrolytic capacitors that incorporate solid polymeric electrolytes, particularly including those mentioned in U.S. Patent Nos. 4,942,501, 5,146,391 and 5,153,820, the disclosures of which in relevant part are incorporated herein by reference.
- Preferred salts include the alkali metal, alkaline earth metal, transition metal, ammonium, substituted ammonium, lead, tin, zinc and cadmium salts of mono-, di-, tri- and tetrabasic acids, especially the ammonium salts of the lower aliphatic saturated dicarboxylic acids, e.g., pentanedioic (glutaric) acid and hexanedioic (adipic) acid. Most preferably, a mixture of two salts, particularly ammonium glutarate and ammonium adipate, in approximately equal molar concentrations, is utilized.
- the electrolyte is preferably made up as a liquid prepolymer electrolyte mixture prior to impregnation into the capacitor element, and the polymer is preferably formed in situ thereafter from that prepolymer mixture.
- the mixture is preferably made up by first dissolving the salt(s) into the liquid plasticizer component by stirring at elevated temperatures, e.g., 65-90"C, cooling the mixture to room temperature, and then adding to the mixture the monomer(s) corresponding to the desired polymer(s) and the crosslinking agent, as well as a polymerization initiator. Refrigeration and/or maintenance of an oxygen containing atmosphere allows the mixture to be stored for long periods without unwanted polymerization.
- the polymerization initiator may be chosen from any of the initiating agents that are well known in the polymerization field, including (a) free radical initiating agents such as potassium persulfate, ammonium persulfate, azoxyisobuty- ronitrile, benzoyl peroxide and other suitable peroxides and persulfates, as well as any of the foregoing agents in combina- tion with a redox co-initiator such as salts of iron or copper or sodium bisulphite; (b) ionic initiators such as butyl lithium, and (c) co-ordination catalysts such as triethyl- aluminum in combination with titanium trichloride.
- free radical initiating agents such as potassium persulfate, ammonium persulfate, azoxyisobuty- ronitrile, benzoyl peroxide and other suitable peroxides and persulfates, as well as any of the foregoing agents in combina- tion with a
- the spacer for the capacitor also comprises mechanical separator means that is impregnated with the electrolyte.
- the mechanical separator means may be constructed of conventional materials, such as Kraft paper, gauze fabric, porous polypropylene or porous polyethylene, although Kraft paper is preferred because of its widespread availability, low cost and ease of handling.
- the Kraft paper or other mechanical separator is disposed between the anode and the cathode of the capacitor, in a layer that is of significantly reduced thickness as compared with the mechanical separators heretofore utilized in prior art capacitors of the same type and specifications. In particular, reductions in thickness of 25-50% and even somewhat beyond may be achieved with the present invention.
- the Kraft paper or other mechanical separator may be provided in a layer the thickness of which is no greater than 35 ⁇ , preferably in the range of 18-30 ⁇ , and most preferably about 20 ⁇ .
- a capacitor in accordance with the present invention may be constructed by first assembling at least one capacitor element by disposing mechanical separator means of reduced thickness as described hereinabove between an anode layer and a cathode layer. Thereafter, because the viscosity of the electrolyte in its prepolymer form is low, the impregnation of the electrolyte proceeds in the same way as is standard in the art.
- the liquid prepolymer electrolyte mixture may be impregnated into the capacitor element by vacuum impregnation. Thereafter, the capacitor element is allowed to stand for a period between 0.1 and 48 hours for complete paper impregnation to take place and is then either wound and then placed into a canister or, in the case of flat capacitor elements, placed in a press. The element is then subjected to heat, preferably by placing it into an oven at 55 ° C for 3 hours and then at 70 ' C for 12 hours, during which time the electro- lyte cures into an elastomer. Oxygen acts as a powerful inhibitor for some of the polymerization reactions, and it is therefore preferable in those cases that air be excluded from the canister or the press during this stage.
- crosslinked electrolyte impregnated paper separator is then removed from the capacitor and subjected to a tensile strength measurement, it is found that the strength of the separator is increased by up to 100% as compared with the paper removed from a prior art electrolyte containing capacitor of a similar type.
- the crosslinked electrolyte impregnated paper is also observed to have a modulus of elongation up to 100% higher than prior art materials. This property is important in determining the extent to which the paper will deform at points or regions of high local stress, for example in the vicinity of the points at which the tab is attached to the anode foil.
- a further advantage of the crosslinked electrolyte impregnated separator of the present invention is its adhesion to the cathode and anode foils. Because of the adhesive nature of the crosslinked electrolyte, it forms a particularly strong bond between the paper separator and the cathode and anode foils. This bond is such that in a peel test where the crosslinked electrolyte impregnated paper is peeled away from the foil, the paper will disintegrate and delaminate within itself before the bond to the foil is ruptured. This property is of particular importance to the flat electrolytic capacitor construction in which a number of anode foil pieces are interleaved with paper and cathode foil to create a flat multilayer structure.
- EXAMPLE 1 A solution of 7 parts ammonium adipate and 7 parts ammonium glutarate in 65 parts of ethylene glycol is made up by stirring at 70'C. After cooling to room temperature the solution is mixed with 35 parts of 2-hydroxyethylmethacrylate, 2 parts of tetraethyleneglycol diacrylate and 0.2 parts of a saturated solution of ammonium persulfate in water. The solution is then stored at or below room temperature until needed.
- a spirally wound capacitor element consisting of two layers of anode material, 2 layers of 20 ⁇ thick Kraft paper, a cathode foil and a further two layers of 20 ⁇ thick Kraft paper is impregnated with the electrolyte by removing air from the element under vacuum and then flooding with the electrolyte under vacuum. After the element has been completely impregnated by the electrolyte, the element is removed from the container and pressed into an aluminum canister. The canister is then placed in a container from which air is excluded by flushing with nitrogen and the container placed in an oven at 55 * C for 3 hours and 70 'C for 12 hours during which time the electrolyte cures into an elastomer. The capacitor is then aged by charging to full working voltage at maximum operating temperature .
- this example was created expressly for the purpose of comparison with prior art electrolytic capacitors, as explained in further detail herein- above in connection with the graph of FIG. 1 , and therefore this example is not representative of the reduction in the thickness of the mechanical separator that can be achieved using the present invention.
- the Kraft paper separators used in this Example 1 were purposely chosen to be of the same thickness (40 ⁇ ) as the Kraft paper separators used in the prior art capacitors, so that the results of the stress/strain analysis could be compared.
- the capacitor constructions set forth in the remaining examples are representative of the reduction in the thickness of the mechanical separator that can be achieved using the present invention.
- EXAMPLE 2 A capacitor is constructed as in Example 1, except that in the construction of the element only one 20 ⁇ thick layer of Kraft paper is used on either side of the cathode. The resultant element has a smaller volume because of the smaller volume of paper used.
- the crosslinked electrolyte serves to increase the tensile strength of the paper such that no degradation in capacitor performance is observed, i.e., the same separating effect as is achieved in the prior art with two layers of paper (40 ⁇ ) is achieved in this example with only one layer of paper (20 ⁇ ) .
- EXAMPLE 3 A solution of 7 parts ammonium adipate and 7 parts ammonium glutarate in 65 parts of ethylene glycol is made up by stirring at 70 "C. After cooling to room temperature the solution is mixed with 35 parts of 2-hydroxyethylmethacrylate, 1 part of tetraethyleneglycol diacrylate and 0.2 parts of a saturated solution of ammonium persulfate in water. The solution is then stored at or below room temperature until needed.
- a capacitor element is constructed by interleaving rectangular segments of anode foil 35mm x 45mm between 20 ⁇ thick layers of Kraft paper and cathode foil. The element has dimensions 45mm x 35mm x 2.5mm, and is impregnated with electrolyte under vacuum.
- the excess electrolyte is removed, the element placed in a press such that pressure is applied to the large face of the element and the press is placed in a sealed container in an oven at 55 °C for 3 hours and 70 "C for 12 hours, during which time the electrolyte cures into an elastomer.
- the result is a flat profile capacitor in which the electrolyte acts as a bonding agent to hold the various layers together without any need for compression to be applied via a rigid case.
- EXAMPLES 4-5 In these examples, the procedures and chemical components are the same as in Examples 2 and 3, respectively, except that the monomer is replaced by 2-hydroxyethylacrylate. The result in each case is a capacitor with improved ESR as compared with the capacitors of the earlier examples in which 2-hydroxyethyl- methacrylate was used.
- EXAMPLES 10-17 In these examples, the procedures and chemical components are the same as in Examples 2-9, respectively, except that an amount of water is added to the plasticizer such that about 6% by weight of the final electrolyte is water.
- the result in each case is an electrolyte with increased conductivity, yielding a capacitor with improved ESR and decreased failure rate, as compared with the electrolytes and corresponding capacitors of the earlier examples in which no water was added to the plasticizer.
- EXAMPLES 18-25 In these examples, the procedures and chemical components are the same as in Examples 3, 5, 7, 9, 11, 13, 15 and 17, respectively, except that the tetraethyleneglycol diacrylate content is 0.5 parts and the ammonium persulfate content is 1.0 parts. The result in each case is an electrolyte with improved tensile strength as compared with the electrolytes of the earlier examples in which 1 part of tetraethyleneglycol diacrylate and 0.2 parts of ammonium persulfate were used.
- the electrolytes of these Examples 18-25 are particularly suited for use in a flat multilayer capacitor construction, wherein they also act as a bonding agent due to their adhesive nature.
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Abstract
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
PCT/AU1996/000491 WO1998006115A1 (fr) | 1996-08-05 | 1996-08-05 | Separateurs de condensateur electrolytique a haute resistance, condensateurs les incorporant et leur procede de fabrication |
EP96925603A EP0948796A1 (fr) | 1996-08-05 | 1996-08-05 | Separateurs de condensateur electrolytique a haute resistance, condensateurs les incorporant et leur procede de fabrication |
AU66072/96A AU6607296A (en) | 1996-08-05 | 1996-08-05 | High strength electrolytic capacitor separators, capacitors incorporating the s ame and methods of making the same |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
PCT/AU1996/000491 WO1998006115A1 (fr) | 1996-08-05 | 1996-08-05 | Separateurs de condensateur electrolytique a haute resistance, condensateurs les incorporant et leur procede de fabrication |
Publications (1)
Publication Number | Publication Date |
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WO1998006115A1 true WO1998006115A1 (fr) | 1998-02-12 |
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Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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PCT/AU1996/000491 WO1998006115A1 (fr) | 1996-08-05 | 1996-08-05 | Separateurs de condensateur electrolytique a haute resistance, condensateurs les incorporant et leur procede de fabrication |
Country Status (3)
Country | Link |
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EP (1) | EP0948796A1 (fr) |
AU (1) | AU6607296A (fr) |
WO (1) | WO1998006115A1 (fr) |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
AU1724888A (en) * | 1987-04-30 | 1988-12-02 | Specialised Conductives Pty Limited | Solid polymer electrolyte capacitors and method of making the same |
AU7016691A (en) * | 1987-04-30 | 1991-05-23 | Specialised Conductives Pty Limited | Solid electrolyte capacitors and method of making the same |
AU8968391A (en) * | 1990-12-21 | 1992-06-25 | Imperial Chemical Industries Plc | Solid electrolytes |
-
1996
- 1996-08-05 AU AU66072/96A patent/AU6607296A/en not_active Abandoned
- 1996-08-05 EP EP96925603A patent/EP0948796A1/fr not_active Withdrawn
- 1996-08-05 WO PCT/AU1996/000491 patent/WO1998006115A1/fr not_active Application Discontinuation
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
AU1724888A (en) * | 1987-04-30 | 1988-12-02 | Specialised Conductives Pty Limited | Solid polymer electrolyte capacitors and method of making the same |
AU7016691A (en) * | 1987-04-30 | 1991-05-23 | Specialised Conductives Pty Limited | Solid electrolyte capacitors and method of making the same |
AU8968391A (en) * | 1990-12-21 | 1992-06-25 | Imperial Chemical Industries Plc | Solid electrolytes |
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AU6607296A (en) | 1998-02-25 |
EP0948796A1 (fr) | 1999-10-13 |
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