ELECTROLYTE ADDITIVE FOR HYBRID SUPERCAPACITORS TO REDUCE CHARGE TRANSFER RESISTANCE, AND HYBRID SUPERCAPACITOR INCLUDING THE SAME

Abstract

A hybrid supercapacitor, including at least one negative electrode having a statically capacitive active material, an electrochemical redox-active material, or a mixture of them; at least one positive electrode having a statically capacitive active material, an electrochemical redox-active material, or a mixture of them; at least one separator situated between the at least one negative electrode and the at least one positive electrode; and an electrolyte mixture; with the provision that at least one electrode includes a statically capacitive active material, and at least one electrode includes an electrochemical, redox-active material; the electrolyte mixture being a liquid electrolyte mixture and including at least one liquid, aprotic, organic solvent, at least one conducting salt, and at least one at least partially halogenated, aromatic compound.

Claims

1. A hybrid supercapacitor, comprising: at least one negative electrode having one of a statically capacitive active material, an electrochemical redox-active material, or a mixture of a statically capacitive active material and a electrochemical redox-active material; at least one positive electrode having one of a statically capacitive active material, an electrochemical redox-active material, or a mixture of a statically capacitive active material and an electrochemical redox-active material; at least one separator situated between the at least one negative electrode and the at least one positive electrode; and an electrolyte mixture; wherein at least one of the 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, and wherein the electrolyte mixture is a liquid electrolyte mixture and includes at least one liquid, aprotic, organic solvent, at least one conducting salt, and at least one at least partially halogenated, aromatic compound.

2. The hybrid supercapacitor as recited in claim 1, wherein the at least one at least partially halogenated aromatic compound is an at least partially chlorinated and/or fluorinated aromatic compound having 6 to 18 carbon atoms.

3. The hybrid supercapacitor as recited in claim 1, wherein the at least one at least partially halogenated aromatic compound is an at least partially fluorinated benzene derivative.

4. The hybrid supercapacitor as recited in claim 1, wherein the at least one at least partially halogenated aromatic compound is selected from 1,2,3-trichlorobenzene, 1,2,4-trichlorobenzene, 1,3,5-trichlorobenzene, 1,2,3,4-tetrachlorobenzene, 1,2,3,5-tetrachlorobenzene, 1,2,4,5-tetrachlorobenzene, pentachlorobenzene, hexachlorobenzene, 1,2,3-trifluorobenzene, 1,2,4-trifluorobenzene, 1,3,5-trifluorobenzene, 1,2,3,4-tetrafluorobenzene, 1,2,3,5-tetrafluorobenzene, 1,2,4,5-tetrafluorobenzene, pentafluorobenzene, and hexafluorobenzene.

5. The hybrid supercapacitor as recited in claim 1, wherein the at least one at least partially halogenated aromatic compound is 1,3,5-trifluorobenzene.

6. The hybrid supercapacitor as recited in claim 1, wherein the at least one at least partially halogenated aromatic compound makes up up to 10% by weight of the total amount of the electrolyte mixture.

7. The hybrid supercapacitor as recited in claim 1, wherein the at least one liquid, aprotic, organic solvent is selected from acetonitrile, propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, ethylene methyl carbonate, ethyl methyl carbonate, as well as mixtures of them.

8. The hybrid supercapacitor as recited in claim 1, wherein the at least one conducting salt is a lithium salt.

9. An electrolyte mixture for a hybrid supercapacitor, comprising at least one liquid, aprotic, organic solvent, at least one conducting salt, and at least one at least partially halogenated, aromatic compound.

10. A method of using an electrolyte mixture, comprising: providing a hybrid supercapacitor; and using, in the hybrid supercapacitor, an electrolyte mixture including at least one liquid, aprotic, organic solvent, at least one conducting salt, and at least one at least partially halogenated, aromatic compound.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Specific embodiments of the present invention are explained in more detail below in light of the figures.

[0052] FIG. 1 shows a schematic view of a hybrid supercapacitor.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

[0053] A hybrid supercapacitor 2 is schematically represented in FIG. 1. Hybrid supercapacitor 2 includes a capacitor housing 3, which is formed in the shape of a prism, and in the case at hand, in the shape of a block. In the present case, capacitor housing 3 is constructed to conduct electricity and is made, for example, of aluminum. However, capacitor housing 3 may also be made of an electrically insulating material, for example, plastic.

[0054] Hybrid supercapacitor 2 includes a negative terminal 11 and a positive terminal 12. A voltage provided by hybrid supercapacitor 2 may be tapped across terminals 11, 12. In addition, hybrid supercapacitor 2 may also be charged via terminals 11, 12. Terminals 11, 12 are set apart from one another at a top surface of prism-shaped capacitor housing 3.

[0055] An electrode roll, which includes two electrodes, namely, a negative electrode 21 and a positive electrode 22, is situated inside of capacitor housing 3 of hybrid supercapacitor 2. Negative electrode 21 and positive electrode 22 are each constructed as foil and wound to the electrode roll while interposing a separator 18. It is also conceivable for a plurality of electrode rolls to be provided in capacitor housing 3. For example, an electrode stack may also be provided in place of the electrode roll.

[0056] Negative electrode 21 includes a negative active material 41, which is constructed as a foil. Negative active material 41 has activated carbon as a basic material (statically capacitive active material), onto which Li.sub.4Ti.sub.5O.sub.12 (electrochemical redox-active material) is deposited. Negative electrode 21 includes a negative active material 41, which is present in particle form. Additives, in particular, conductive carbon black and binding agents, are situated between the particles of negative active material 41. In this context, negative active material 41 and the above-mentioned additives form, in each instance, a composite, which is constructed as a foil.

[0057] Negative electrode 21 further includes a current diverter 31, which is also manufactured as a foil. The composite made up of negative active material 41 and the additives, and the current diverter 31 of the negative electrode, are laid flat on one another and joined to each other. Current diverter 31 of negative electrode 21 is constructed to be electrically conductive and is made of a metal, for example, copper. Current diverter 31 of negative electrode 21 is electrically connected to negative terminal 11 of hybrid supercapacitor 2.

[0058] Positive electrode 22 presently includes a positive active material 42 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 binding agents, are situated between the particles of positive active material 42. The positive active material 42 and the above-mentioned additives form, in each instance, a composite that is constructed as a foil.

[0059] Positive electrode 22 further includes a current diverter 32, which is also manufactured as a foil. The composite made up of positive active material 42 and the additives, and the current diverter 32 of the positive electrode, are laid flat on one another and joined to each other. Current diverter 32 of positive electrode 22 is constructed to be electrically conductive and is made of a metal, for example, aluminum. Current diverter 32 of positive electrode 22 is electrically connected to positive terminal 12 of hybrid supercapacitor 2.

[0060] Negative electrode 21 and positive electrode 22 are separated from each other by separator 18. Separator 18 is also constructed as a foil. Separator 18 is constructed to be electronically insulating, but transmissive with respect to ionic conductivity, that is, transmissive for ions, in particular, lithium ions.

[0061] Capacitor housing 3 of hybrid supercapacitor 2 is filled with a liquid electrolyte mixture 15. In this context, electrolyte mixture 15 surrounds negative electrode 21, positive electrode 22, and separator 18. Electrolyte mixture 15 is also ionically conductive and includes a liquid solvent, in this case, for example, a mixture of at least one cyclic carbonate (e.g., ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), and at least one linear carbonate (e.g., dimethylene carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (MEC)), as well as a lithium salt (e.g., LiPF.sub.6, LiBF.sub.4) and 1,3,5-trifluorobenzene as an additive. The amount of 1,3,5-trifluorobenzene is, for example, 2% by weight, based on the total electrolyte mixture 15.

[0062] The present invention is not limited to the above-described exemplary embodiments and the aspects emphasized in them. On the contrary, a number of modifications lying within the scope of the actions of one skilled in the art are possible within the field described herein.