HYBRID SUPERCAPACITOR, INCLUDING AN ELECTROLYTE COMPOSITION, HAVING IMPROVED CONDUCTIVITY

Abstract

A hybrid supercapacitor, including at least one negative electrode that includes a statically capacitive active material, an electrochemical redox active material, or a mixture thereof, at least one positive electrode that includes a statically capacitive active material, an electrochemical redox active material, or a mixture thereof, at least one separator that is situated between the at least one negative electrode and the at least one positive electrode, and an electrolyte composition, with the condition that at least one electrode includes a statically capacitive active material, and at least one electrode includes an electrochemical redox active material, the electrolyte composition being a liquid electrolyte composition and including at least one liquid, aprotic, organic solvent, at least one conducting salt, and at least one additive.

Claims

1. A hybrid supercapacitor, comprising: at least one negative electrode that includes one of: a statically capacitive active material, an electrochemical redox active material, or a mixture of a statically capactivie active compound and an electrochemical redox active material; at least one positive electrode that includes one of: a statically capacitive active material, an electrochemical redox active material, or a mixture of a statically capactivie active compound and an electrochemical redox active material; at least one separator that is situated between the at least one negative electrode and the at least one positive electrode; and an electrolyte composition; wherein, at least one of negative and positive electrodes includes a statically capacitive active material, and at least one of the negative and positive electrodes includes an electrochemical redox active material; wherein the electrolyte composition is a liquid electrolyte composition and includes at least one liquid, aprotic, organic solvent, at least one conducting salt, composed of at least one cation and at least one anion, that is suitable for balancing the charge of the cation, and at least one additive, selected from at least one Lewis acid, that is suitable for forming a complex compound with the at least one anion.

2. The hybrid supercapacitor as recited in claim 1, wherein the at least one additive includes a Lewis acid selected from a boron(III) compound and an aluminum(III) compound.

3. The hybrid supercapacitor as recited in claim 1, wherein the at least one additive includes a boron(III) compound of formula (I): ##STR00009## where R, R′, and R″ may be independently selected from: a hydrogen atom, a halogen atom, a hydroxy group, a linear or branched, saturated or unsaturated, hydrocarbon moiety having either 1 to 18 carbon atoms or halogen atoms; a cyclic, saturated or unsaturated, hydrocarbon moiety having 3 to 18 carbon, hydrogen atoms, or linear saturated alkyl moieties having 1 to 3 carbon atoms; an aromatic hydrocarbon moiety having 6 to 18 carbon atoms, halogen atoms or linear, completely or partially fluorinated, saturated alkyl moieties having 1 to 3 carbon atoms; and a moiety —OR.

4. The hybrid supercapacitor as recited in claim 3, wherein e adjacent moieties R, R′, R″ are joined together to form a cyclic compound.

5. The hybrid supercapacitor as recited in claim 1, wherein the at least one additive includes a Lewis acid selected from a polydentate nitrogen compound.

6. The hybrid supercapacitor as recited in claim 5, wherein the polydentate nitrogen compound is a compound of formula (II): ##STR00010## where R′″ represents at least one of an alkylene group —(CH.sub.2).sub.n— having 1 to 10 carbon atoms (n=1 to 10), or at least one linear alkyl moiety having 1 to 6 cabon atoms, and at least one halogen atom; EWG represents an electron-attracting group; and R.sup.11, R.sup.12 independently represent a hydrogen atom, a linear or branched, saturated or unsaturated, alkyl moiety having 1 to 6 carbon atoms, an aryl moiety having 6 to 12 carbon atoms, or a moiety —R′″— NR.sup.3(EWG), where R′″ and EWG have the meanings defined above, and R.sup.3 represents a further group R.sup.11 or a further group R′″, with the condition that R.sup.11 and R.sup.12 are joined together via this alkylene group R′″ to form a cyclic compound.

7. The hybrid supercapacitor (2) as recited in claim 6, wherein the polydentate nitrogen compound is a cyclic compound of formula (III): ##STR00011## where E represents an electron-attracting group selected from a tosyl group (—SO.sub.2—C.sub.6H.sub.4—CH.sub.3), a mesyl group (—SO.sub.2—CH.sub.3), and a triflyl group (—SO.sub.2—CF.sub.3); Q represents an alkylene group of formula —(CH.sub.2).sub.m and m is an integer from 1 to 4; and N represents an integer from 1 to 4.

8. The hybrid supercapacitor as recited in claim 1, wherein the at least one additive is a boron(III) compound of formula (I): ##STR00012## where R, R′, and R″ may be independently selected from: a hydrogen atom, a halogen atom, a hydroxy group, a linear or branched, saturated or unsaturated, hydrocarbon moiety having either 1 to 18 carbon atoms or halogen atoms, a cyclic, saturated or unsaturated, hydrocarbon moiety having 3 to 18 carbon, hydrogen atoms, or linear saturated alkyl moieties having 1 to 3 carbon atoms, an aromatic hydrocarbon moiety having 6 to 18 carbon atoms, halogen atoms or linear, completely or partially fluorinated, saturated alkyl moieties having 1 to 3 carbon atoms, and a moiety —OR; wherein the boron(III) compound is in combination with a polydentate nitrogen compound wherein the polydentate nitrogen compound is a compound of formula (II): ##STR00013## where R′″ represents at least one of an alkylene group —(CH.sub.2).sub.n— having 1 to 10 carbon atoms (n=1 to 10), or at least one linear alkyl moiety having 1 to 6 cabon atoms, and at least one halogen atom; EWG represents an electron-attracting group; and R.sup.11, R.sup.12 independently represent a hydrogen atom, a linear or branched, saturated or unsaturated, alkyl moiety having 1 to 6 carbon atoms, an aryl moiety having 6 to 12 carbon atoms, or a moiety —R′″—NR.sup.3(EWG), where R′″ and EWG have the meanings defined above, and R.sup.3 represents a further group R.sup.11 or a further group R′″, with the condition that R.sup.11 and R.sup.12 are joined together via this alkylene group R′″ to form a cyclic compound.

9. The hybrid supercapacitor as recited in claim 1, wherein the at least one additive is added to the electrolyte composition in a quantity such that a molar ratio of conducting salt to additive of 1:0.5 to 1:5 is set.

10. An electrolyte composition for a hybrid supercapacitor, including at least one liquid, aprotic, organic solvent, at least one conducting salt, composed of at least one cation and at least one anion, that is suitable for balancing the charge of the cation, and at least one additive, selected from at least one Lewis acid, that is suitable for forming a complex compound with the at least one anion.

11. The electrolyte composition as recited in claim 9, wherein the electrolyte composition is used in a hybrid supercapacitor.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0110] Specific embodiments of the present invention are described below with reference to the figure.

[0111] FIG. 1 shows a schematic illustration of a hybrid supercapacitor.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

[0112] A hybrid supercapacitor 2 is schematically illustrated in FIG. 1. Hybrid supercapacitor 2 includes a capacitor housing 3 having a prismatic design, in the present case a cuboidal design. In the present case, capacitor housing 3 has an electrically conductive design and is made of aluminum, for example. However, capacitor housing 3 may also be made of an electrically insulating material, for example plastic.

[0113] Hybrid supercapacitor 2 includes a negative terminal 11 and a positive terminal 12. A voltage provided by hybrid supercapacitor 2 may be tapped via terminals 11, 12. In addition, hybrid supercapacitor 2 may also be charged via terminals 11, 12. Terminals 11, 12 are situated spaced apart from one another on a top surface of prismatic capacitor housing 3.

[0114] An electrode winding which includes two electrodes, namely, a negative electrode 21 and a positive electrode 22, is situated within capacitor housing 3 of hybrid supercapacitor 2. Negative electrode 21 and positive electrode 22 each have a foil-like design, and are wound to form an electrode winding with a separator 18 situated in between. It is also possible to provide multiple electrode windings in capacitor housing 3. An electrode stack, for example, may be provided instead of the electrode winding.

[0115] Negative electrode 21 includes a negative active material 41 which has a foil-like design. Negative active material 41 has activated carbon (statically capacitive active material) as a base material, to which Li.sub.4Ti.sub.5O.sub.12 (electrochemical redox active material) is applied. Negative electrode 21 includes a negative active material 41 which is present in particle form. Additives, in particular conductive carbon black and binder, are situated between the particles of negative active material 41. Negative active material 41 and the additives in each case form a composite which has a foil-like design.

[0116] Negative electrode 21 also includes a current collector 31, which likewise has a foil-like design. The composite of negative active material 41, the additives, and current collector 31 are placed flatly against one another and joined together. Current collector 31 of negative electrode 21 has an electrically conductive design and is made of a metal, for example copper. Current collector 31 of negative electrode 21 is electrically connected to negative terminal 11 of hybrid supercapacitor 2.

[0117] In the present case, positive electrode 22 includes a positive active material made of a mixture of activated carbon (statically capacitive active material) and LiMn.sub.2O.sub.4 (electrochemical redox active material). Positive electrode 22 includes a positive active material 42 which is present in particle form. Additives, in particular conductive carbon black and binder, are situated between the particles of positive active material 42. Positive active material 42 and the additives in each case form a composite which has a foil-like design.

[0118] Positive electrode 22 also includes a current collector 32 which likewise has a foil-like design. The composite, made up of positive active material 42, the additives, and current collector 32 are placed flatly against one another and joined together. Current collector 32 of positive electrode 22 has an electrically conductive design and is made of a metal, for example aluminum. Current collector 32 of positive electrode 22 is electrically connected to positive terminal 12 of hybrid supercapacitor 2.

[0119] Negative electrode 21 and positive electrode 22 are separated from one another by separator 18. Separator 18 likewise has a foil-like design. Separator 18 has an electronically insulating design, but is ionically conductive, i.e., is permeable for ions, in particular lithium ions.

[0120] Capacitor housing 3 of hybrid supercapacitor 2 is filled with a liquid electrolyte composition 15. Electrolyte composition 15 surrounds negative electrode 21, positive electrode 22, and separator 18. Electrolyte composition 15 is ionically conductive, and includes a liquid solvent, in the present case, for example, a mixture of at least one cyclic carbonate (for example, ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC)), and at least one linear carbonate (for example, dimethylene carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (MEC)), and a lithium salt (for example, LiPF.sub.6, LiBF.sub.4) and a compound of formula (III-c), where E=—SO.sub.2—C.sub.6H.sub.4—CH.sub.3, as additive. The quantity of additive is, for example, 2% by weight in each case, based on entire electrolyte composition 15.

[0121] The present invention is not limited to the exemplary embodiments described here and the aspects highlighted therein. Rather, numerous modifications within the range set forth herein are possible which are within the scope of activities carried out by those skilled in the art.