Ultra-thin lithium ion capacitors with ultra-high power performance are provided. Ultra-thin electrodes and ultra-thin lithium films can be used for the ultra-thin lithium ion capacitor. A lithium ion capacitor can include a first positive electrode and a second positive electrode, a negative electrode disposed between the first positive electrode and the second positive electrode, a first lithium film disposed between the first positive electrode and the negative electrode, and a second lithium film disposed between the second positive electrode and the negative electrode. Each of the first and second lithium films can include an electrolyte. In addition, at least one separator can be provided between the first positive electrode and the first lithium film, and at least one separator can be provided between the second positive electrode and the second lithium film.

An electrolyte solution containing at least one selected from a compound represented by the following formula (1-1) (wherein Rf.sup.111s are the same as or different from each other and are each a C2-C4 fluorinated alkenyl group), a compound represented by the following formula (1-2) (wherein R.sup.121 is a C1-C4 alkyl group; and Rf.sup.121 is a C2-C4 fluorinated alkenyl group), and a compound represented by the following formula (1-3) (wherein Rf.sup.131 is a C1-C3 fluorinated alkyl group; and R.sup.131 is a C6-C12 aryl group): ##STR00001##

A capacitor includes a first metal layer disposed on a wafer or substrate, a first polarized dielectric layer above the first metal layer and comprising a plurality of electrets formed by aligning molecular dipoles throughout a three-dimensional surface area of a polarizable dielectric material during polarization by applying a momentary electric field of positive or negative polarity, a second metal layer disposed on the first polarized dielectric layer to electrically isolate the first polarized dielectric layer, and a second polarized dielectric layer above the second metal layer, the second polarized dielectric layer comprising a plurality of electrets formed by aligning molecular dipoles throughout a three-dimensional surface area of a polarizable dielectric material during polarization by applying a second momentary electric field of opposing polarity. A plurality of alternating polarized dielectric layers and metal layers may be arranged in series to form a stack, with an internal passivation layer disposed between each stack.

A capacitor includes a first metal layer disposed on a wafer or substrate, a first polarized dielectric layer above the first metal layer and comprising a plurality of electrets formed by aligning molecular dipoles throughout a three-dimensional surface area of a polarizable dielectric material during polarization by applying a momentary electric field of positive or negative polarity, a second metal layer disposed on the first polarized dielectric layer to electrically isolate the first polarized dielectric layer, and a second polarized dielectric layer above the second metal layer, the second polarized dielectric layer comprising a plurality of electrets formed by aligning molecular dipoles throughout a three-dimensional surface area of a polarizable dielectric material during polarization by applying a second momentary electric field of opposing polarity. A plurality of alternating polarized dielectric layers and metal layers may be arranged in series to form a stack, with an internal passivation layer disposed between each stack.

An electrochemical device, which is a non-aqueous electrochemical device, comprising a polymer (P) enclosed in an inside of the electrochemical device, wherein the polymer (P) is a polymer having a molecular structure containing a unit (P) represented by the following formula (P), the polymer (P) having a weight-average molecular weight of greater than 50,000, as well as an electrode for an electrochemical device, a coating liquid for an electrochemical device, an insulating layer for an electrochemical device, an undercoat layer for an electrochemical device, and an electrolytic solution for an electrochemical device including the polymer (P) and other ingredients:

##STR00001## in the formula (P), R.sup.P is a group of 1 to 20 carbon atoms.

The present invention provides a non-aqueous electrolytic solution which can be handled industrially stably, and which allows for achieving a good durability performance, particularly, a good capacity retention rate during repeated charging and discharging, of an energy device typified by a non-aqueous electrolytic solution secondary battery. The non-aqueous electrolytic solution contains a compound(s) represented by the following general formula(e) (A1) and/or (A2). In formula (A1), X.sup.1 represents a halogen atom; each of R.sup.1, R.sup.2, R.sup.5 and R.sup.6 independently represents a hydrogen atom, a halogen atom, or a hydrocarbon group having 10 or less carbon atoms optionally substituted with a halogen atom; and each of R.sup.3 and R.sup.4 independently represents a halogen atom, or a hydrocarbon group having 10 or less carbon atoms optionally substituted with a halogen atom; wherein at least two of R.sup.1 to R.sup.6 may be bonded to each other to form a ring. In formula (A2), each of X.sup.2 and X.sup.3 independently represents a halogen atom; and each of R.sup.7 to R.sup.14 independently represents a hydrogen atom, a halogen atom, or a hydrocarbon group having 10 or less carbon atoms optionally substituted with a halogen atom; wherein at least two of R.sup.7 to R.sup.14 may be bonded to each other to form a ring.

##STR00001##

A secondary battery includes a positive electrode, a negative electrode, and an electrolytic solution. The positive electrode includes a positive electrode active material layer. The positive electrode active material layer includes a lithium-nickel composite oxide of a layered rock-salt type.

An electrolyte solution including a solvent, the solvent containing a compound (1a) represented by the following formula (1a); and

##STR00001##

a compound (2) represented by the following formula (2):

##STR00002##

wherein R.sup.e is a C1-C5 linear or branched alkyl group optionally containing an ether bond; R.sup.f is a C1-C5 linear or branched alkyl group optionally containing an ether bond; and at least one of R.sup.e or R.sup.f contains a fluorine atom. Also disclosed is an electrochemical device including the electrolyte solution, a lithium-ion secondary battery including the electrolyte solution, and a module including the electrochemical device or the lithium-ion secondary battery.

An electrolyte solution including a solvent, the solvent containing a compound (1a) represented by the following formula (1a); and

##STR00001##

a compound (2) represented by the following formula (2):

##STR00002##

wherein R.sup.e is a C1-C5 linear or branched alkyl group optionally containing an ether bond; R.sup.f is a C1-C5 linear or branched alkyl group optionally containing an ether bond; and at least one of R.sup.e or R.sup.f contains a fluorine atom. Also disclosed is an electrochemical device including the electrolyte solution, a lithium-ion secondary battery including the electrolyte solution, and a module including the electrochemical device or the lithium-ion secondary battery.

An aspect of the present invention is a nonaqueous electrolyte energy storage device including: a negative electrode including a negative active material layer with a thickness expansion rate of 10% or more due to charge; and a separator, in which the absolute value (|dR/dP|) of an increase in resistance (dR) to a change in pressure (dP) in pressurization is 0.15 Ω.Math.cm.sup.2/MPa or less in the separator impregnated with a measurement electrolyte solution, the measurement electrolyte solution contains an ethylene carbonate and an ethyl methyl carbonate as a solvent, and a lithium hexafluorophosphate as an electrolyte salt, the volume ratio between the ethylene carbonate and the ethyl methyl carbonate is 30:70, and the concentration of the lithium hexafluorophosphate is 1.0 mol/L.