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.

The present invention discloses a process for preparing a functionalized choline chloride ionic liquid as defined in formula (I), and thereof use in an electrochemical energy storage device, as an electrolyte solution or an additive for a lithium ion battery and a supercapacitor. The ionic liquid electrolyte material has better biocompatibility, flame retardance, high ionic conductivity, low viscosity, and wide electrochemical window. ##STR00001## wherein R.sup.1 is selected from the group consisting of: (CH.sub.2═CH—(CH.sub.2).sub.n)—, CN(CH.sub.2).sub.n—, or R.sup.2.sub.3Si—; R.sup.2 is selected from CH.sub.3—(CH.sub.2).sub.m—, n is an integer selected from 1 to 3, m is an integer selected from 0 to 2; or one of R.sup.2 is (CH.sub.3).sub.3Si—O—. Anion A in Formula I is selected from the group consisting of: Cl.sup.−, Br.sup.−, I.sup.−, BF.sub.4.sup.−, NO.sub.3.sup.−, SO.sub.4.sup.2−, CF.sub.3COO.sup.−, CF.sub.3SO.sub.3.sup.−, (CF.sub.3SO.sub.2).sub.2N.sup.−, PF.sub.6.sup.−, BF.sub.2C.sub.2O.sub.4.sup.−, or B(C.sub.2O.sub.4).sub.2.sup.−.

An electrochemical cell has an anode comprising a silicon-based active material, a cathode comprising a cathode active material, and an electrolyte having no ethylene carbonate. The electrolyte comprises a solvent, the solvent being 20 wt % to 50 wt % propylene carbonate with the remainder being a linear solvent, a lithium salt, and less than 15 wt % of one or more additives. The silicon-based anode active material has a specific capacity of ≥700 mAh/g.

The present invention provides an electrolytic solution capable of restraining gas generation. The present invention relates to an electrolytic solution containing a nonaqueous solvent (I), an electrolyte salt (II), and a compound (III) represented by the following formula (1):

##STR00001##

wherein Rf represents a C1-C20 linear or branched fluorinated alkyl group or a C3-C20 fluorinated alkyl group having a cyclic structure, R represents a C1-C20 linear or branched alkylene group or a C3-C20 alkylene group having a cyclic structure, hydrogen atoms in R may be partially or fully replaced by fluorine atoms, Rf and R may each contain an oxygen atom between carbon atoms when having a carbon number of 2 or more as long as oxygen atoms are not adjacent to each other.

The present invention provides an electrolytic solution capable of restraining gas generation. The present invention relates to an electrolytic solution containing a nonaqueous solvent (I), an electrolyte salt (II), and a compound (III) represented by the following formula (1):

##STR00001##

wherein Rf represents a C1-C20 linear or branched fluorinated alkyl group or a C3-C20 fluorinated alkyl group having a cyclic structure, R represents a C1-C20 linear or branched alkylene group or a C3-C20 alkylene group having a cyclic structure, hydrogen atoms in R may be partially or fully replaced by fluorine atoms, Rf and R may each contain an oxygen atom between carbon atoms when having a carbon number of 2 or more as long as oxygen atoms are not adjacent to each other.

Electrolytes and electrolyte additives for energy storage devices comprising linear carbonate compounds.

Electrolytes and electrolyte additives for energy storage devices comprising linear carbonate compounds.

A secondary battery includes a positive electrode, a first aqueous electrolyte held on the positive electrode, a negative electrode, a second aqueous electrolyte held on the negative electrode, and a separator interposed between the positive electrode and the negative electrode. A difference between an osmotic pressure (N/m.sup.2) of the first aqueous electrolyte and an osmotic pressure (N/m.sup.2) of the second aqueous electrolyte is 90% or less (including 0%) of the higher one of the osmotic pressure of the first aqueous electrolyte and the osmotic pressure of the second aqueous electrolyte.

This application provides an electrolyte and an electrochemical device, wherein the electrolyte comprises an additive A and an additive B, the additive A is present in an amount of 0.001% to 10% by mass in the electrolyte, and the additive B is present in an amount of 0.1% to 10% by mass in the electrolyte. This application can improve the cycle performance and storage performance of the electrochemical device, especially the cycle performance and storage performance of the electrochemical device under high temperature and high voltage conditions.

Disclosed is an electrochemical cell, which may be used for advanced rechargeable batteries. The electrochemical cell comprises two or more electrodes within an electrolyte solution, where the electrolyte solution containing (i) an aliphatic or cyclic sulfone and (ii) a metal perfluoroalkylsulfonylimide salt.