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A graphite-based negative electrode active material including a first graphite particle being spheroidized and a second graphite particle having a roundness lower than the roundness of the first graphite particle, wherein the content of the second graphite particle based on the sum of the first graphite particle and the second graphite particle is in the range of 1 to 30 % by mass, the ratio of a median particle diameter (D_(50)) to a particle diameter at 5 cumulative% (D_(5)), D_(50)/D_(5), in a cumulative distribution of the first graphite particle is smaller than the ratio of a median particle diameter (D_(50)) to a particle diameter at 5 cumulative% (D_(5)), D_(50)/D_(5), in a cumulative distribution of the second graphite particle, and the tap density in saturation of the particle mixture of the first graphite particle and the second graphite particle is higher than both the tap density in saturation of the first graphite particle and the tap density in saturation of the second graphite particle.


Patent
NEC Energy Devices Ltd. | Date: 2017-02-08

Secondary battery 1 includes: battery electrode assembly 5 that has a quadrangular planar shape, and includes a positive electrode and a negative electrode laminated with a separator interposed therebetween; and an exterior container that is formed of flexible films 7, and contains battery electrode assembly 5. The exterior container has recessed emboss portion 8 that contains battery electrode assembly 5 therein. Four corners 4a of an outer peripheral portion of battery electrode assembly 5 are either folded to be contained inside emboss portion 8, or inserted between flexible films 7 outside emboss portion 8. A length of at least one side among four sides forming the quadrangular planar shape of battery electrode assembly 5 is shorter than an inner dimension of emboss portion 8 in the direction in which the one side extends.


Patent
Nec Energy Devices Ltd. | Date: 2016-12-23

Provided is a battery in which collector foil is unlikely to break. In a lithium-ion secondary battery, as for a distance from a connection section between a positive electrode tab and the positive electrode terminal to a boundary section between applying and non-applying sections of positive-electrode active material in a direction perpendicular to a stacking direction, compared with a reference positive electrode having the boundary section that is located farthest to the connection section by straight-line distance, a layer of a positive electrode that is stacked in such a way as to be farthest from the reference positive electrode has a smaller distance from a boundary of the applying and non-applying sections of the positive-electrode active material to a connection section with the positive electrode tab in a direction perpendicular to a stacking direction.


A graphite-based negative electrode active material including a first graphite particle being spheroidized and a second graphite particle having a roundness lower than the roundness of the first graphite particle, wherein the content of the second graphite particle based on the sum of the first graphite particle and the second graphite particle is in the range of 1 to 30% by mass, the ratio of a median particle diameter (D_(50)) to a particle diameter at 5 cumulative % (D_(5)), D_(50)/D_(5), in a cumulative distribution of the first graphite particle is smaller than the ratio of a median particle diameter (D_(50)) to a particle diameter at 5 cumulative % (D_(5)), D_(50)/D_(5), in a cumulative distribution of the second graphite particle, and the tap density in saturation of the particle mixture of the first graphite particle and the second graphite particle is higher than both the tap density in saturation of the first graphite particle and the tap density in saturation of the second graphite particle.


Patent
NEC Energy Devices Ltd. | Date: 2016-06-15

There is provided a nonaqueous electrolyte secondary battery having high capacity in which the reduction in the capacity of the battery due to the irreversible capacity in the first charge and discharge is suppressed using a high capacity positive electrode. The nonaqueous electrolyte secondary battery according to the exemplary embodiment includes a positive electrode (6) and a negative electrode (3) comprising at least one negative electrode active material selected from the group consisting of Si, a Si oxide and carbon,wherein the positive electrode (6) comprises a positive electrode active material comprising an oxide capable of absorbing and releasing lithium and a transition metal oxide, the transition metal oxide being represented by Li_(2)MO_(2) (wherein M is at least one of Cu and Ni) and including a square-planar coordination MO_(4) structure, the square-planar coordination MO_(4) structure forming a one-dimensional chain which shares an edge formed by two opposing oxygen atoms, wherein a relation Z Y is satisfied provided that Y represents a first charge capacity of the negative electrode, and Z represents a first charge capacity of the positive electrode, characterized in that a relation < is satisfied provided that represents an amount of Li corresponding to a first irreversible capacity of the negative electrode active material, and represents an amount of Li released during a first charge by the transition metal oxide, wherein the negative electrode comprises at least Si or a Si oxide as the negative electrode active material.


Patent
NEC Energy Devices Ltd. | Date: 2016-06-08

A secondary battery includes a battery electrode assembly in which positive electrode 1 and negative electrode 6 are stacked alternately with separator 20 interposed therebetween. Positive electrode 1 and negative electrode 6 each have current collector 3, 8 and active material 2, 7. Each surface of current collectors 3, 8 has a coated portion and an uncoated portion of active materials 2, 8. Active material 2, 7 has inclined portions 2a, 7a having decreasing thickness. Insulators 40 are arranged to cover boundaries 4a between the coated portion and the uncoated portion of positive electrode 1. One or both of insulators 40 on both surfaces of positive electrode current collector 3 have one end 40a which is located on inclined surface 2a and which is opposite to inclined portion 7a of one or both of active materials 7 on both surfaces of negative electrode current collector 3, and have other end 40b which is located on uncoated portion of positive electrode 1.


Patent
NEC Energy Devices Ltd. | Date: 2016-01-13

To provide a non-aqueous electrolyte secondary battery capable of preventing formation of lithium on a negative electrode during charging and preventing a short circuit between positive and negative electrodes due to contraction of a separator at high temperature. A non-aqueous electrolyte secondary battery includes a negative electrode in which a negative electrode active material layer is formed on a negative electrode collector, and a positive electrode laminated on the negative electrode through a separator, in which a positive electrode active material layer is formed on a positive electrode collector. The positive electrode active material layer on a surface of a positive electrode tab drawn from the positive electrode collector has a region which extends in a drawing direction of the positive electrode tab, exceeding a leading end line of a vertically projected negative electrode active material layer opposed to the positive electrode active material layer and in which an existing amount of the positive electrode active material layer is reduced toward its leading end portion.


Patent
NEC Energy Devices Ltd. | Date: 2016-05-11

Battery cell 1 in the present invention includes, within flexible outer case 10, an electrolyte solution, and battery assembly 4 in which positive electrodes 6 and negative electrodes 7 are alternately laminated so as to sandwich separators 8 therebetween. Battery cell 1 includes positive electrode terminal 2 that has one end electrically connected with positive electrodes 6 and that has the other end which extends to outside of outer case 10, and negative electrode terminal 3 that has one end electrically connected with negative electrodes 7 and that has the other end that extends outside outer case 10. In battery assembly 4, fixation members 5 are provided on a pair of opposite lateral surfaces as viewed in a laminating direction of positive electrodes 6 and negative electrodes 7.


Patent
NEC Energy Devices Ltd. | Date: 2016-04-27

Secondary battery includes a battery assembly configured by alternately stacking positive electrodes 1 and negative electrodes 6 via separators 20, in which the positive electrode and the negative electrode respectively include collectors 3 and 8, and active materials 2 and 7 applied on the collectors. On each surface of the collector, a coated portion coated with the active material and an uncoated portion not coated with any active material are provided. In one or both of the positive electrode and the negative electrode, boundary portion 4a between the coated portion and the uncoated portion on the front surface of the collector, is positioned planarly away from boundary portion 4b between the coated portion and the uncoated portion on the rear surface of the collector.


Patent
NEC Energy Devices Ltd. | Date: 2016-04-13

To provide a film-covered battery and a battery module having high resistance to external impact. A frame body is placed on a peripheral portion of a film-covered battery. The frame body has a protruding portion. The peripheral portion of film-covered body is supported by the protruding portion.

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