Abstract: A nonaqueous electrolyte for an energy storage device according to an aspect of the present invention includes an imide salt (a), a salt (b) in which a charge center element of an anion is boron and which has an oxalato group, and a difluorophosphate (c), in which a content of the imide salt (a) is 3 or more in terms of molar ratio with respect to a total content of the salt (b) in which the charge center element of the anion is boron and which has the oxalato group and the difluorophosphate (c). A nonaqueous electrolyte for an energy storage device according to another embodiment of the present invention includes an imide salt (a), a salt (b) in which a charge center element of an anion is boron and which has an oxalato group, and a difluorophosphate (c), in which a content of the imide salt (a) is 25 mol % or more with respect to a total content of all ionic compounds.

Abstract: One aspect of the present invention is a nonaqueous electrolyte energy storage device including a positive electrode containing a positive composite, the positive composite containing a positive active material, a phosphorus atom and an aluminum atom, in which in a spectrum of the positive composite as measured by X-ray photoelectron spectroscopy, a peak position of P2p is at 134.7 eV or less, and a peak height ratio of Al2p to P2p (Al2p/P2p) is 0.1 or more.

Abstract: Provided are a nonaqueous electrolyte energy storage device having high capacity retention ratio after charge-discharge cycles at a high temperature of about 45° C., and a method for producing such a nonaqueous electrolyte energy storage device. One aspect of the present invention is a nonaqueous electrolyte energy storage device including a positive electrode having a positive composite that contains a phosphorus atom and a lithium-transition metal composite oxide containing manganese, wherein, in a spectrum of the positive composite by X-ray photoelectron spectroscopy, a peak position for P2p is observed at 134.7 eV or less. Another aspect of the present invention is a method for producing a nonaqueous electrolyte energy storage device, the method including forming a positive electrode using a positive composite paste that contains a phosphorus oxo acid and a lithium-transition metal composite oxide containing manganese.

Abstract: One aspect of the present invention is a nonaqueous electrolyte energy storage device including: a positive electrode including a positive electrode mix containing a phosphorus atom; and a nonaqueous electrolyte containing an imide salt, wherein a peak attributed to P2p appears at a position corresponding to 135 eV or less in an X-ray photoelectron spectroscopic spectrum of the positive electrode mix. Another aspect of the present invention is a method for manufacturing a nonaqueous electrolyte energy storage device including: a positive electrode including a positive electrode mix produced using a positive electrode mix paste containing an oxoacid of phosphorus; and a nonaqueous electrolyte containing an imide salt.

Abstract: Provided are a nonaqueous electrolyte energy storage device having high capacity retention ratio after charge-discharge cycles at a high temperature of about 45° C., and a method for producing such a nonaqueous electrolyte energy storage device. One aspect of the present invention is a nonaqueous electrolyte energy storage device including a positive electrode having a positive composite that contains a phosphorus atom and a lithium-transition metal composite oxide containing manganese, wherein, in a spectrum of the positive composite by X-ray photoelectron spectroscopy, a peak position for P2p is observed at 134.7 eV or less. Another aspect of the present invention is a method for producing a nonaqueous electrolyte energy storage device, the method including forming a positive electrode using a positive composite paste that contains a phosphorus oxo acid and a lithium-transition metal composite oxide containing manganese.

Abstract: One aspect of the present invention is a nonaqueous electrolyte energy storage device including a positive electrode containing a positive composite, the positive composite containing a positive active material, a phosphorus atom and an aluminum atom, in which in a spectrum of the positive composite as measured by X-ray photoelectron spectroscopy, a peak position of P2p is at 134.7 eV or less, and a peak height ratio of Al2p to P2p (Al2p/P2p) is 0.1 or more.