Abstract: An energy storage device according to one aspect of the present invention includes: a negative electrode including a negative active material layer; and a nonaqueous electrolyte. The negative active material layer contains a negative active material. The negative active material contains natural graphite particles. The natural graphite particles have an internal porosity of 2% or less. A state of charge of the negative active material in a charged state is 0.6 or less.

Abstract: The present embodiment provides a lithium ion secondary battery including a positive electrode containing LiaNixCoyMzO2 (0.9?a?1.2, 0.3?x?0.8, 0.2?y+z?0.7, where M is a metal element other than Li, Ni, and Co) as a positive active material, and a negative electrode containing non-graphitic carbon as a negative active material. In this lithium ion secondary battery, at a portion where the positive electrode and the negative electrode face each other, a basis weight (P) of the positive active material and a basis weight (N) of the negative active material satisfy a relational expression of 0.65?P/N?1.05.

Abstract: An energy storage device according to an aspect of the present invention includes: a negative electrode including a negative substrate made of pure aluminum or an aluminum alloy, a conductive layer directly or indirectly layered on the negative substrate and containing a conductive agent, and a negative active material layer containing a negative active material capable of occluding lithium ions at a potential of 0.05 V vs. Li/Li+ or lower; and a positive electrode opposed to the negative electrode and including a positive substrate and a positive active material layer directly or indirectly layered on the positive substrate, and the negative active material layer is layered on the negative substrate and the conductive layer so as to include a region in contact with the negative substrate and a region in contact with the conductive layer.

Abstract: An energy storage device includes a negative electrode having a negative active material layer containing amorphous carbon as an active material, a curve attained by determining a rate of change (dQ/dV) in a potential (V) of the amorphous carbon in a discharge capacity (Q) of the amorphous carbon per unit quantity based on a result attained by measuring the potential (V) with respect to the discharge capacity (Q) and representing the rate of change (dQ/dV) with respect to the potential (V) has one or more peaks in a range in which the potential of the amorphous carbon is 0.8 V or more and 1.5 V or less, and a potential of the negative electrode at time of full charge is 0.25 V or more with respect to a lithium potential.

Abstract: An energy storage device includes a positive electrode provided with a positive composite layer containing a positive active material, a negative electrode provided with a negative composite layer containing a negative active material, and a separator partitioning between the positive electrode and the negative electrode, wherein the separator includes a substrate uniaxially drawn into a sheet shape and a coating layer coating at least one of surfaces of the substrate, and the coating layer has an anisotropic structure with orientation in a direction different from a drawing direction of the substrate.

Abstract: One aspect of the present invention is an energy storage device including; a negative electrode containing a negative active material; a positive electrode containing a positive active material; and a nonaqueous electrolyte. The negative active material contains solid graphite particles with an aspect ratio of 1 to 5 as a main component, and the nonaqueous electrolyte contains an imide salt containing phosphorus or sulfur.

Abstract: An energy storage device includes: a positive electrode plate containing a positive composite layer including a positive active material capable of occluding and releasing a lithium ion; and a negative electrode plate containing a negative composite layer including a negative active material capable of occluding and releasing a lithium ion. A peak pore diameter Rp of the positive composite layer in a pore distribution measured by a mercury penetration method is 0.5 ?m or less, and a peak pore diameter Rn of the negative composite layer in a pore distribution measured by a mercury penetration method is 0.5 ?m or less. A ratio Rp/Rn of the peak pore diameter of the positive composite layer to the peak pore diameter of the negative composite layer is 0.60 or more and 1.70 or less.

Abstract: An energy storage device is provided that has improved power performance at low temperature. In the present embodiment, an energy storage device is provided that includes an electrode having an active material layer, the active material layer contains at least active material particles, the particles contained in the active material layer gives a volume-based particle size frequency distribution that has a first peak and a second peak appearing in a particle size larger than a particle size of the first peak, and particles having particle sizes equal to or smaller than a particle size Dx have a volume proportion of 49% or more and 62% or less in a volume of whole particles contained in the active material layer, with the particle size Dx defined as a particle size at a local minimum frequency between the first peak and the second peak in the particle size frequency distribution.

Abstract: An energy storage device includes a positive electrode having a positive active material layer containing an active material in the form of particles. The positive active material layer contains primary particles of the active material and secondary particles formed by aggregation of a plurality of primary particles. The proportion of primary particles relative to all particles of the active material in the positive active material layer is 5% or more and 40% or less. An method for producing an energy storage device includes preparing a positive electrode having a positive active material layer by forming a positive active material layer from a composite containing at least secondary particles of an active material, and assembling an energy storage device using the prepared positive electrode.

Abstract: An aspect of the present invention is a nonaqueous electrolyte energy storage device including: a positive electrode having a positive composite layer including a positive active material; a negative electrode having a negative composite layer including a negative active material; and a nonaqueous electrolyte including a nonaqueous solvent, in which the positive active material includes a lithium-transition metal composite oxide that contains nickel as a transition metal and has a layered ?-NaFeO2-type crystal structure, a ratio (N/P) between mass (N) per unit area of the negative active material and mass (P) per unit area of the positive active material is 0.30 or more and 0.

Abstract: One aspect of the present invention is an energy storage device including a positive electrode containing: first positive active material particles containing a metal element capable of forming a conductive metal oxide; and second positive active material particles not containing the metal element, in which the first positive active material particles include a nickel-cobalt-manganese-containing lithium-transition metal composite oxide containing lithium, nickel, cobalt, and manganese as constituent elements, and the first positive active material particles are larger in median diameter than the second positive active material particles.

Abstract: An energy storage device includes a negative electrode having a negative active material layer containing amorphous carbon as an active material, a curve attained by determining a rate of change (dQ/dV) in a potential (V) of the amorphous carbon in a discharge capacity (Q) of the amorphous carbon per unit quantity based on a result attained by measuring the potential (V) with respect to the discharge capacity (Q) and representing the rate of change (dQ/dV) with respect to the potential (V) has one or more peaks in a range in which the potential of the amorphous carbon is 0.8 V or more and 1.5 V or less, and a potential of the negative electrode at time of full charge is 0.25 V or more with respect to a lithium potential.

Abstract: An energy storage device includes: an electrode assembly which includes: an approximately rectangular positive electrode; an approximately rectangular negative electrode which is stacked alternately with the positive electrode; and a strip-like elongated separator having a base material layer and an inorganic layer which is made to overlap with the first base material layer, wherein the elongated separator is arranged between the positive electrode and the negative electrode, and the base material layer of the elongated separator faces the negative electrode in an opposed manner between the positive electrode and the negative electrode.

Abstract: The present embodiment provides a lithium ion secondary battery including a positive electrode containing LiaNixCoyMzO2 (0.9?a?1.2, 0.3?x?0.8, 0.2?y+z?0.7, where M is a metal element other than Li, Ni, and Co) as a positive active material, and a negative electrode containing non-graphitic carbon as a negative active material. In this lithium ion secondary battery, at a portion where the positive electrode and the negative electrode face each other, a basis weight (P) of the positive active material and a basis weight (N) of the negative active material satisfy a relational expression of 0.65?P/N?1.05.

Abstract: There is provided an energy storage device which can have a relatively high initial power and whereby it becomes possible to prevent the occurrence of electrodeposition of lithium even when a charge-discharge procedure is performed repeatedly at a high rate.

Abstract: An energy storage device having sufficient energy density and sufficient power is provided. In this embodiment, an energy storage device that includes a negative electrode containing an active material layer including an active material is provided. The active material layer includes particulate graphite as the active material. A particle diameter frequency distribution of the graphite includes a first peak and a second peak which appears in a region where a particle diameter is larger than a particle diameter of the first peak, the particle diameter of the first peak is equal to or less than 10 ?m and the particle diameter of the second peak is more than 10 ?m. The active material layer further includes a particulate high hardness active material which has higher hardness than the graphite.

Abstract: An energy storage device is provided that has improved power performance at low temperature. In the present embodiment, an energy storage device is provided that includes an electrode having an active material layer, the active material layer contains at least active material particles, the particles contained in the active material layer gives a volume-based particle size frequency distribution that has a first peak and a second peak appearing in a particle size larger than a particle size of the first peak, and particles having particle sizes equal to or smaller than a particle size Dx have a volume proportion of 49% or more and 62% or less in a volume of whole particles contained in the active material layer, with the particle size Dx defined as a particle size at a local minimum frequency between the first peak and the second peak in the particle size frequency distribution.

Abstract: An energy storage device includes a positive electrode having a positive active material layer containing an active material in the form of particles. The positive active material layer contains primary particles of the active material and secondary particles formed by aggregation of a plurality of primary particles. The proportion of primary particles relative to all particles of the active material in the positive active material layer is 5% or more and 40% or less. An method for producing an energy storage device includes preparing a positive electrode having a positive active material layer by forming a positive active material layer from a composite containing at least secondary particles of an active material, and assembling an energy storage device using the prepared positive electrode.

Abstract: An energy storage device of which endurance capacity retention ratio is improved is provided. An energy storage device 10 includes: a positive electrode plate 12 containing a positive composite layer including a positive active material capable of occluding and releasing a lithium ion; and a negative electrode plate 13 containing a negative composite layer including a negative active material capable of occluding and releasing a lithium ion. A peak pore diameter Rp of the positive composite layer in a pore distribution measured by a mercury penetration method is 0.5 ?m or less, and a peak pore diameter Rn of the negative composite layer in a pore distribution measured by a mercury penetration method is 0.5 ?m or less. A ratio Rp/Rn of the peak pore diameter of the positive composite layer to the peak pore diameter of the negative composite layer is 0.60 or more and 1.70 or less.

Abstract: An energy storage device having sufficient energy density and sufficient power is provided. In this embodiment, an energy storage device that includes a negative electrode containing an active material layer including an active material is provided. The active material layer includes particulate graphite as the active material. A particle diameter frequency distribution of the graphite includes a first peak and a second peak which appears in a region where a particle diameter is larger than a particle diameter of the first peak, the particle diameter of the first peak is equal to or less than 10 ?m and the particle diameter of the second peak is more than 10 ?m. The active material layer further includes a particulate high hardness active material which has higher hardness than the graphite.