Hybrid Supercapacitor

Abstract

A hybrid supercapacitor has two electrodes, one of which functions as a cathode, and the other as an anode. The hybrid supercapacitor further includes an electrolyte arranged between the cathode and the anode. The electrolyte contains a solvent selected from the group consisting of methanol, 1-propanol, 1-heptanol, ethyl acetoacetate, ethylene glycol, diethylene glycol, glycerol, benzyl alcohol, di-n-butyl phthalate and mixtures thereof.

Claims

1. A hybrid supercapacitor, comprising: an electrolyte including a solvent, wherein the solvent is at least one of methanol, 1-propanol, 1-heptanol, ethyl acetoacetate, ethylene glycol, diethylene glycol, glycerol, benzyl alcohol, di-n-butyl phthalate, and mixtures thereof.

2. The hybrid supercapacitor according to claim 1, wherein the solvent is at least one of methanol, 1-propanol, 1-heptanol, ethyl acetoacetate, and mixtures thereof.

3. The hybrid supercapacitor according to claim 1, wherein the solvent is at least one of ethylene glycol, diethylene glycol, glycerol, benzyl alcohol, di-n-butyl phthalate, and mixtures thereof.

4. The hybrid supercapacitor according to claim 1, wherein at least one of tetraethyl-ammonium tetrafluoroborate and at least one lithium salt is dissolved in the solvent.

5. The hybrid supercapacitor according to claim 4, wherein the at least one lithium salt is at least one of lithium perchlorate, lithium hexafluorophosphate, lithium tetrafluoro-borate, lithium bistrifluoromethanesulfonimide, lithium bispentafluoroethanesulfonimide, lithium bisfluorosulfonylimide, lithium bisoxalatoborate, lithium oxalyldifluoroborate, lithium fluoroalkyl-phosphate, and lithium trifluoromethanesulfonate.

6. The hybrid supercapacitor according to claim 4, wherein at least one of the tetraethylammonium tetrafluoroborate and the at least one lithium salt has a concentration in the solvent in a range of approximately 0.1 mol/L and approximately 2.0 mol/L.

7. The hybrid supercapacitor according to claim 6, wherein the electrolyte contains 0.1% by weight to 10.0% by weight of an additive other than the tetraethylammonium tetrafluoroborate and the at least one lithium salt.

8. The hybrid supercapacitor according to claim 7, wherein that the additive is a lithium salt.

9. The hybrid supercapacitor according to claim 7, wherein the additive is an organic solvent.

10. The hybrid supercapacitor according to claim 1, further comprising: a first electrode containing at least one material selected from a first group consisting of activated carbon, graphene, carbon nanotubes, carbon aerogels, carbon nanofibers, ruthenium oxide, manganese oxide, titanium oxide, polyaniline and polypyrrole, and a second electrode containing at least one material selected from a second group consisting of Co.sub.3O.sub.4, V.sub.2O.sub.5, TiO.sub.2, Li.sub.4Ti.sub.5O.sub.12, Li.sub.3V.sub.2(PO.sub.4).sub.3, LiMoO.sub.2, LiMn.sub.2O.sub.4, LiNiMnCoO.sub.2 and LiMn.sub.xFe.sub.1-xPO.sub.4, wherein x is in a range from 0 to 1.

11. The hybrid supercapacitor according to claim 10, wherein: the first electrode further contains at least one material selected from the second group, and the second electrode further contains at least one material selected from the first group.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Working examples of the disclosure are illustrated by the drawing and elucidated in detail in the description which follows.

[0019] The FIGURE shows, in schematic form, the construction of a hybrid supercapacitor according to various working examples of the disclosure.

DETAILED DESCRIPTION

[0020] In all the working examples of the hybrid super-capacitor 1 described hereinafter, it has the construction shown in the FIGURE. It has a cathode 2 containing LiMn.sub.2O.sub.4 in a matrix composed of activated carbon. The cathode 2 has been applied to a first collector 3. In addition, the hybrid supercapacitor 1 has an anode 4 consisting of Li.sub.4Ti.sub.5O.sub.12 in a matrix composed of activated carbon. The anode 4 has been applied to a second collector 5. Arranged between the cathode 2 and the anode 4 is an electrolyte 6. A porous separator 7 separates the two electrodes 2, 4 from one another. Embedding of Li.sup.+ ions into the cathode 2 and into the anode 4 is shown in schematic form in the FIGURE in four enlargements.

[0021] The electrolyte 6, in different working examples of the disclosure, contains different solvents in each case as main constituent. 1.0 mol/L lithium perchlorate is dissolved in each solvent. As additives, the electrolyte 6 in all working examples contains 3.0% by weight of lithium bistrifluoromethanesulfonimide. In working examples B5 to B9, it additionally contains 5.0% by weight of ethyl acetate.

[0022] In working examples B1 to B4, the solvent in each case is one of the solvents listed in table 1:

TABLE-US-00001 TABLE 1 # Solvent BP [° C.] MP [° C.] ρ [g/mL] P B1 methanol CH.sub.4O 64.6 −98.0 0.791 0.762 B2 1-propanol C.sub.3H.sub.8O 97.0 −126.0 0.803 0.617 B3 1-heptanol C.sub.7H.sub.16O.sub.2 176.4 −35.0 0.819 0.549 B4 ethyl aceto- C.sub.6H.sub.10O.sub.3 180.4 −80.0 1.028 0.577 acetate

[0023] In this table, BP denotes the boiling temperature, MP the melting temperature, ρ the density and P the relative polarity.

[0024] Hybrid supercapacitors 1 according to working examples B1 to B4 can be used at operating temperatures down to −100° C., since the salts dissolved in the solvents and the ethyl acetate still further lower the melting temperatures of the solvents, which were already low in any case.

[0025] According to working examples B5 to B9, one of the solvents mentioned in table 2 is used.

TABLE-US-00002 TABLE 2 ρ # Solvent BP [° C.] MP [° C.] [g/mL] P B5 ethylene C.sub.2H.sub.8O.sub.3 197.0 −13.0 1.115 0.790 glycol B6 glycerol C.sub.3H.sub.8O.sub.3 290.0 17.8 1.261 0.812 B7 diethylene C.sub.4H.sub.10O.sub.3 245.0 −10.0 1.118 0.713 glycol B8 benzyl alcohol C.sub.7H.sub.8O 205.4 −15.3 1.042 0.608 B9 di-n-butyl C.sub.16H.sub.10O.sub.3 340.0 −35.0 1.049 0.272 phthalate

[0026] The high boiling points of these solvents, which are increased even further by the salts added, enable use of the hybrid supercapacitor 1 at temperatures up to 240° C. In examples B5 and B9, it is possible to achieve even higher operating temperatures.