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 aims to provide an electrolyte solution containing a quaternary ammonium salt as an electrolyte salt and is capable of providing an electrochemical device having a high capacitance retention and reducing generation of gas. The electrolyte solution of the present invention contains a solvent, a quaternary ammonium salt, and a nitrogen-containing unsaturated cyclic compound. The unsaturated cyclic compound is a nitrogen-containing unsaturated heterocyclic compound. The unsaturated cyclic compound excludes salts of the unsaturated cyclic compound and ionic liquids obtainable from the unsaturated cyclic compound.

In one aspect, the present disclosure relates to an improved method of preparing concentrated MnO.sub.2 ink with increased efficiency and cost effectiveness. The method involves mixing KMnO.sub.4 solution with highly crystalline carbon particles (HCCPs) with average diameters less than 800 nm at 30-60° C. for at least 8 hours. The present disclosure further relates to a symmetric supercapacitor device comprising MnO.sub.2 coated electrodes and a solid state ionic liquid as electrolyte, as well as an interdigital transparent SC (IT-SC) device comprising aqueous MnO.sub.2 ink.

In one aspect, the present disclosure relates to an improved method of preparing concentrated MnO.sub.2 ink with increased efficiency and cost effectiveness. The method involves mixing KMnO.sub.4 solution with highly crystalline carbon particles (HCCPs) with average diameters less than 800 nm at 30-60° C. for at least 8 hours. The present disclosure further relates to a symmetric supercapacitor device comprising MnO.sub.2 coated electrodes and a solid state ionic liquid as electrolyte, as well as an interdigital transparent SC (IT-SC) device comprising aqueous MnO.sub.2 ink.

Described are compounds of the structure R4—.sub.a—Si—(Sp-Y).sub.a—Z.sub.b, wherein “a” is integer from 1 to 4; “b” is an integer from 0 to (3×a); “Z,” which is absent when “b”“R” or formula (II), wherein each “R” is halogen, C.sub.1-6 linear or branched alkyl, alkenyl, or alkynyl or C.sub.1-6 linear or branched halo-alkyl, halo-alkenyl, or halo-alkynyl; each “Sp” C.sub.1-15 linear or branched alkylenyl or CMS linear or branched halo-alkylenyl; and each “Y” an organic polar group. Also described are electrolyte compositions containing one or more of these compounds.

Described are compounds of the structure R4—.sub.a—Si—(Sp-Y).sub.a—Z.sub.b, wherein “a” is integer from 1 to 4; “b” is an integer from 0 to (3×a); “Z,” which is absent when “b”“R” or formula (II), wherein each “R” is halogen, C.sub.1-6 linear or branched alkyl, alkenyl, or alkynyl or C.sub.1-6 linear or branched halo-alkyl, halo-alkenyl, or halo-alkynyl; each “Sp” C.sub.1-15 linear or branched alkylenyl or CMS linear or branched halo-alkylenyl; and each “Y” an organic polar group. Also described are electrolyte compositions containing one or more of these compounds.

An electrolytic solution for lithium ion secondary batteries contains: a lithium salt electrolyte; an organic solvent; and an aliphatic compound having three or more carboxylic acid groups in a molecule. A lithium ion secondary battery includes: a cathode including a cathode active material that is capable of absorbing and releasing lithium and contains manganese (Mn) as a major transit metal species; an anode; and a non-aqueous electrolytic solution. The electrolytic solution is the above-described solution. The aliphatic compound has a molecular weight within the range from 50,000 to 500,000.

An electrolytic solution for lithium ion secondary batteries contains: a lithium salt electrolyte; an organic solvent; and an aliphatic compound having three or more carboxylic acid groups in a molecule. A lithium ion secondary battery includes: a cathode including a cathode active material that is capable of absorbing and releasing lithium and contains manganese (Mn) as a major transit metal species; an anode; and a non-aqueous electrolytic solution. The electrolytic solution is the above-described solution. The aliphatic compound has a molecular weight within the range from 50,000 to 500,000.

The present disclosure provides supercapacitors that may avoid the shortcomings of current energy storage technology. Provided herein are electrochemical systems, comprising three dimensional porous reduced graphene oxide film electrodes. Prototype supercapacitors disclosed herein may exhibit improved performance compared to commercial supercapacitors. Additionally, the present disclosure provides a simple, yet versatile technique for the fabrication of supercapacitors through the direct preparation of three dimensional porous reduced graphene oxide films by filtration and freeze casting.