The present invention aims to provide an electrolyte solution for forming, for example, a secondary battery having excellent oxidation resistance and high voltage cycle characteristics; an electrochemical device such as a lithium-ion secondary battery that contains the electrolyte solution; and a module that contains the electrochemical device. The present invention provides an electrolyte solution containing a solvent and an electrolyte salt, wherein the solvent contains a fluorine-containing compound (A) represented by formula (1) shown below, and a fluorine-containing compound (B) represented by formula (2) shown below:
Rf.sup.1OCOOR  (1)
wherein Rf.sup.1 is a C1-C4 fluorine-containing alkyl group, and R is a C1-C4 non-fluorinated alkyl group, and
Rf.sup.2OCOORf.sup.3  (2)
wherein Rf.sup.2 and Rf.sup.3 are the same or different, and each is a C1-C4 fluorine-containing alkyl group.

The present invention aims to provide an electrolyte solution for forming, for example, a secondary battery having excellent oxidation resistance and high voltage cycle characteristics; an electrochemical device such as a lithium-ion secondary battery that contains the electrolyte solution; and a module that contains the electrochemical device. The present invention provides an electrolyte solution containing a solvent and an electrolyte salt, wherein the solvent contains a fluorine-containing compound (A) represented by formula (1) shown below, and a fluorine-containing compound (B) represented by formula (2) shown below:
Rf.sup.1OCOOR  (1)
wherein Rf.sup.1 is a C1-C4 fluorine-containing alkyl group, and R is a C1-C4 non-fluorinated alkyl group, and
Rf.sup.2OCOORf.sup.3  (2)
wherein Rf.sup.2 and Rf.sup.3 are the same or different, and each is a C1-C4 fluorine-containing alkyl group.

The present invention provides a high output voltage supercapacitor having a cathode including layers of phosphorene, an anode comprising zinc, and an organic-solvent-based electrolyte including zinc. The supercapacitor demonstrates a high anti-self-discharge. The organic electrolyte may include an anhydrous zinc salt, tetraethylammonium tetrafluoroborate, and propylene carbonate (Et.sub.4NBF.sub.4/PC). The electrochemical stability window of Et.sub.4NBF.sub.4/PC extends beyond 2.5 V. The supercapacitor can be charged to 2.5 V and possesses high initial discharge voltage. The supercapacitor delivered 130 F g.sup.−1 even after more than 9500 cycles at a current density of 0.5 A g.sup.−1. More importantly, the supercapacitor exhibits a capacitance retention of 70.16% even after 500 hours self-discharge behavior.

The present invention provides a high output voltage supercapacitor having a cathode including layers of phosphorene, an anode comprising zinc, and an organic-solvent-based electrolyte including zinc. The supercapacitor demonstrates a high anti-self-discharge. The organic electrolyte may include an anhydrous zinc salt, tetraethylammonium tetrafluoroborate, and propylene carbonate (Et.sub.4NBF.sub.4/PC). The electrochemical stability window of Et.sub.4NBF.sub.4/PC extends beyond 2.5 V. The supercapacitor can be charged to 2.5 V and possesses high initial discharge voltage. The supercapacitor delivered 130 F g.sup.−1 even after more than 9500 cycles at a current density of 0.5 A g.sup.−1. More importantly, the supercapacitor exhibits a capacitance retention of 70.16% even after 500 hours self-discharge behavior.

An ultracapacitor that is in contact with a hot atmosphere having a temperature of about 80° C. or more is provided. The ultracapacitor contains a first electrode, second electrode, separator, nonaqueous electrolyte, and housing is provided. The first electrode comprises a first current collector electrically coupled to a first carbonaceous coating and the second electrode comprises a second current collector electrically coupled to a second carbonaceous coating. The capacitor exhibits a capacitance value within the hot atmosphere of about 6 Farads per cubic centimeter or more as determined at a frequency of 120 Hz and without an applied voltage.

An ultracapacitor that is in contact with a hot atmosphere having a temperature of about 80° C. or more is provided. The ultracapacitor contains a first electrode, second electrode, separator, nonaqueous electrolyte, and housing is provided. The first electrode comprises a first current collector electrically coupled to a first carbonaceous coating and the second electrode comprises a second current collector electrically coupled to a second carbonaceous coating. The capacitor exhibits a capacitance value within the hot atmosphere of about 6 Farads per cubic centimeter or more as determined at a frequency of 120 Hz and without an applied voltage.

Systems and methods of charging and discharging an ultracapacitor are disclosed. In one embodiment, a circuit for charging a capacitor can include a power source configured to provide a source voltage. The circuit can further include an ultracapacitor, a temperature sensing device, a power converter, and one or more control devices configured to receive signals indicative of a temperature from the temperature sensing device, and to control operation of the power converter based at least in part on the one or more signals indicative of the temperature.

Systems and methods of charging and discharging an ultracapacitor are disclosed. In one embodiment, a circuit for charging a capacitor can include a power source configured to provide a source voltage. The circuit can further include an ultracapacitor, a temperature sensing device, a power converter, and one or more control devices configured to receive signals indicative of a temperature from the temperature sensing device, and to control operation of the power converter based at least in part on the one or more signals indicative of the temperature.

An ultracapacitor that comprises a first and second electrochemical cell that are connected in parallel is provided. The cells are define by a first electrode that contains a current collector having opposing sides coated with a carbonaceous material, a second electrode that contains a current collector having opposing sides coated with a carbonaceous material, and a separator positioned between the first electrode and the second electrode. The second cell is by the second electrode, a third electrode that contains a current collector having opposing sides coated with a carbonaceous material, and a separator positioned between the second electrode and the third electrode. The ultracapacitor also contains a nonaqueous electrolyte that is in ionic contact with the electrodes and contains a nonaqueous solvent and an ionic liquid. A package encloses the first cell, the second cell, and the nonaqueous electrolyte.

An ultracapacitor that comprises a first and second electrochemical cell that are connected in parallel is provided. The cells are define by a first electrode that contains a current collector having opposing sides coated with a carbonaceous material, a second electrode that contains a current collector having opposing sides coated with a carbonaceous material, and a separator positioned between the first electrode and the second electrode. The second cell is by the second electrode, a third electrode that contains a current collector having opposing sides coated with a carbonaceous material, and a separator positioned between the second electrode and the third electrode. The ultracapacitor also contains a nonaqueous electrolyte that is in ionic contact with the electrodes and contains a nonaqueous solvent and an ionic liquid. A package encloses the first cell, the second cell, and the nonaqueous electrolyte.