Abstract: The invention provides a method for evaluating the safety of a battery under an internal short-circuit condition. The battery includes: an electrode group including a positive electrode, a negative electrode, and an insulating layer for electrically insulating the electrodes, which are wound or laminated; an electrolyte; a housing for housing the electrode group and the electrolyte; and a current-collecting terminal for electrically connecting the electrode group and the housing. The method of the invention includes: placing a foreign object at a location inside the electrode group of the battery where the positive electrode and the negative electrode face each other; and pressing the location by the pressure applied by a pressing tool to locally crush the insulating layer between the positive and negative electrodes, thereby causing an internal short-circuit.

Abstract: A separator for use in a non-aqueous electrolyte secondary battery including a first porous layer (layer A) having a shutdown function which becomes substantially a non-porous layer at a high temperature, and a second porous layer (layer B) including an aramid resin and an inorganic material, wherein a ratio (TA/TB) of a thickness (TA) of the layer A relative to a thickness (TB) of the layer B is 2.5 or more and 13 or less.

Abstract: Disclosed is a non-aqueous electrolyte including a non-aqueous solvent, and a solute dissolved in the non-aqueous solvent. The non-aqueous solvent contains ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), and an additive. The weight percentage WEC of EC the total weight of EC, PC, and DEC is more than 20 wt % and equal to or less than 35 wt %; the weight percentage WPC of PC is 20 to 40 wt %; and the weight percentage WDEC of DEC is 30 to 50 wt %. The additive contains a cyclic carbonate having a C?C unsaturated bond, and a sultone compound. The ratio WC/WSL of a weight percentage WC of the cyclic carbonate having a C?C unsaturated bond contained in the non-aqueous electrolyte, to a weight percentage WSL of the sultone compound contained in the non-aqueous electrolyte is 1 to 6.

Abstract: In a lithium ion secondary battery including a flat-plate electrode assembly which is configured by stacking the positive electrode, the separator, and the negative electrode in the thickness direction thereof, each of the positive electrode and the negative electrode includes a current collector and an active material layer. Each of the current collector includes a substantially rectangular current collector body, a heat radiating portion, and a lead portion, and the heat radiating portions are projected toward the outside of the electrode assembly so as not to overlap with each other in the thickness direction of the electrode assembly. In this way, heat caused inside the lithium ion secondary battery can be diffused efficiently to the outside, and safety of the lithium ion secondary battery can be further increased, without complicating the battery structure and decreasing mechanical strength of the battery.

Abstract: In a non-aqueous electrolyte secondary battery, a separator in which its dynamic hardness DH obtained when the load to an indenter reaches 12 kgf/cm2 is 1000 or more is used. This separator includes at least one porous layer X including a polyolefin, and at least one porous layer Y including a heat resistant resin. The porosity of the porous layer X is 35% or more and 65% or less. In a pore size distribution of the porous layer X measured with a mercury porosimeter, a ratio of pores having a pore size of 0.02 ?m or more and 0.2 ?m or less is 40 vol % or more relative to a total pore volume. The thermal deformation temperature of the heat resistant resin is 160° C. or more.

Abstract: A non-aqueous electrolyte secondary battery includes a positive electrode, a negative electrode, a non-aqueous electrolyte, and an insulating layer formed on a surface of the positive electrode. The positive electrode includes a lithium nickel composite oxide having a layer structure, and the lithium nickel composite oxide is represented by the general formula: LixNiyM1-yO2 where M is at least one selected from the group consisting of Na, Mg, Sc, Y, Mn, Fe, Co, Cu, Zn, Al, Cr, Pb, Sb, and B, 0<x?1.2, and 0.5<y?1.0. The non-aqueous electrolyte includes a solute and a non-aqueous solvent dissolving the solute, and the non-aqueous solvent contains 40% by weight or more of a cyclic carbonic acid ester. The insulating layer includes an insulating polymeric material.

Abstract: A lithium ion secondary battery includes a positive electrode capable of absorbing and desorbing lithium ion, a negative electrode capable of absorbing and desorbing lithium ion, a porous film interposed between the positive electrode and the negative electrode, and a non-aqueous electrolyte, the porous film being adhered to a surface of at least the negative electrode. The porous film includes an inorganic filler and a first binder: The content of the first binder in the porous film is 1.5 to 8 parts by weight per 100 parts by weight of the filler: The first binder includes a first rubber including an acrylonitrile unit: The first rubber is water-insoluble and has a decomposition temperature of 250° C. or higher. The negative electrode includes a negative electrode active material capable of absorbing and desorbing lithium ion and a second binder, and the second binder includes a second rubber particle and a water-soluble polymer.

Abstract: A non-aqueous electrolyte secondary battery including: a positive electrode having a positive electrode material mixture containing a composite lithium oxide; a negative electrode; a polyolefin separator; a non-aqueous electrolyte; and a heat-resistant insulating layer interposed between the positive and negative electrodes. The positive electrode material mixture has an estimated heat generation rate at 200° C. of not greater than 50 W/kg. The positive electrode and the negative electrode are wound together with the separator and the heat-resistant insulating layer interposed therebetween.

Abstract: Methods for evaluating battery safety under internal short-circuit conditions are improved to eliminate variations in evaluation results and accurately evaluate battery safety under internal short-circuit conditions. An internal short-circuit is caused in a battery by using an internal short-circuit causing method in which battery information obtained upon the occurrence of an internal short-circuit hardly changes with the structure of the battery. At this time, the battery information is detected to accurately evaluate the safety of the battery upon the internal short-circuit and identify the safety level.

Abstract: A method for evaluating the safety of a battery under an internal short-circuit condition. The method for evaluating an internal short-circuit of a battery is characterized in that a short-circuit can be caused at a desired location inside the battery. According to the evaluation method of the invention, the evaluation result is not affected by the constitution of the outermost part of the battery unlike nail penetration tests which are conventional evaluation methods. Also, unlike crush tests which are conventional evaluation methods, the locations of short-circuits do not vary among tests and the safety under an internal short-circuit condition can be evaluated accurately.

Abstract: The present invention relates to an internal short circuit evaluation method for a battery including an electrode group including a positive electrode plate, a negative electrode plate and a separator disposed between the positive electrode plate and the negative electrode plate, and an outer jacket covering the electrode group, the method including the steps of: (I) processing the electrode group to a predetermined position of the electrode group, from the outside of the electrode group toward the inside thereof; and (II) causing a short circuit between a portion of the electrode plate and a portion of the negative electrode plate of the electrode group that are located inside from the predetermined position, and measuring battery information that is changed by the short circuit, and an evaluation apparatus used for the above-described method.

Abstract: A negative electrode for a lithium ion secondary battery includes a negative electrode core member and a negative electrode mixture layer adhering to the negative electrode core member. The negative electrode mixture layer includes active material particles, a cellulose ether compound, and rubber particles. The cellulose ether compound has a degree of etherification of 0.25 or more and 0.7 or less and an average degree of polymerization of 20 or more and 1200 or less. The negative electrode mixture layer contains remaining particles including a water-insoluble portion of the cellulose ether compound and having a mean particle size of 1 ?m or more and 75 ?m or less. The bonding strength between the active material particles is 98 N/cm2 or more.

Abstract: A nonaqueous electrolyte secondary battery comprising a positive electrode 5, a negative electrode 6, a separator 7 and a nonaqueous electrolyte, wherein a material mixture layer containing an active material and a binder is formed on a surface of a current collector 51 of at least one of the positive electrode 5 and the negative electrode 6. The material mixture layer includes a first layer 52 and a second layer 53 which are different in volume ratio of the binder to the active material. The volume ratio (A) of the binder in the first layer 52 in contact with the surface of the current collector 51 is lower than the volume ratio (B) of the binder in the second layer 53.

Abstract: The invention provides an evaluation method and an evaluation apparatus with which it is possible to know the safety level of batteries when an internal short circuit occurs through a chemical process, and a battery whose safety level has been determined with the evaluation method and the evaluation apparatus. A battery that has been charged to a predetermined voltage and into which conductive foreign matter has been incorporated is immersed in an electrolyte. The time at which the battery started to dissolve in the electrolyte is determined. Occurrence of an internal short circuit in the battery is detected based on a battery voltage. A time required for occurrence of short circuit is computed based on the above-described dissolution start time and the time of occurrence of the internal short circuit, and then output.

Abstract: A negative electrode for a non-aqueous electrolyte secondary battery includes a negative electrode core member and a negative electrode mixture layer adhering to the negative electrode core member. The negative electrode mixture layer includes graphite particles, a water-soluble polymer coating the surfaces of the graphite particles, and a binder bonding the graphite particles coated with the water-soluble polymer. The negative electrode mixture layer has a specific surface area of 2.2 to 3 m2/g, and the bonding strength between the graphite particles coated with the water-soluble polymer is 14 kgf/cm2 or more. A non-aqueous electrolyte secondary battery including this electrode has good coulombic efficiency, since decomposition of the components of the non-aqueous electrolyte due to reaction between the graphite particles and the non-aqueous electrolyte is suppressed.

Abstract: A lithium secondary battery including: an electrode group, a non-aqueous electrolyte and a battery case housing the electrode group and the non-aqueous electrolyte, the electrode group including a positive electrode, a negative electrode and a separator layer interposed between the positive electrode and the negative electrode, wherein an end-of-charge voltage and an end-of-discharge voltage are set in such a manner that the electrode group has an energy density of not less than 700 Wh/L, the separator layer includes a porous heat-resistant layer, and a short circuit area A produced when an internal short circuit has occurred between the positive electrode and the negative electrode, and a reduced area B of the porous heat-resistant layer that is produced by heat generation satisfy 1?(A+B)/A?10.

Abstract: An object is to provide a high capacity non-aqueous electrolyte secondary battery in which decomposition of propylene carbonate is suppressed. The non-aqueous electrolyte secondary battery includes: a negative electrode including graphite particles as a negative electrode active material; a positive electrode; a separator; and a non-aqueous electrolyte including propylene carbonate as a non-aqueous solvent. Each of the graphite particles has a surface portion including an amorphous region and a crystal region which includes a plurality of carbon hexagonal net planes stacked along a surface of the graphite particle. Ends of the stacked carbon hexagonal net planes form loops exposed on the surface of the graphite particle. At least a part of the loops are stacked, and the average number of the loops stacked is more than 1 and not more than 2.

Abstract: A negative electrode, whose tensile strength is 15 N/cm or lower when the percentage elongation in the longitudinal direction is 1%, is used in a non-aqueous electrolyte secondary battery including: a flat electrode group 10 including a positive electrode, the negative electrode and a separator; and a non-aqueous electrolyte, which are housed in a prismatic battery case.

Abstract: Provided is a non-aqueous electrolyte capable of favorably suppressing the gas generation during storage in a high temperature environment and during charge/discharge cycling of a non-aqueous electrolyte secondary battery. The non-aqueous electrolyte includes a non-aqueous solvent and a solute dissolved in the non-aqueous solvent, wherein: the non-aqueous solvent includes ethylene carbonate, propylene carbonate, diethyl carbonate, and an additive; the additive includes a sultone compound and a cyclic carbonate having a C?C unsaturated bond; a weight percentage WPC of the propylene carbonate relative to a total of the ethylene carbonate, propylene carbonate, and diethyl carbonate is 30 to 60% by weight; a ratio WPC/WEC of the weight percentage WPC of the propylene carbonate to a weight percentage WEC of the ethylene carbonate relative to the total satisfies 2.

Abstract: A PTC resistor according to the present invention comprises at least one PTC composition which comprises at least one resin and at least two conductive materials. The at least two conductive materials comprises at least two conductive materials different from each other. The at least one PTC composition may comprise a first PTC composition which comprises a first resin and at least one first conductive material and a second PTC composition which is compounded with the first PTC composition and comprises a second resin and at least one second conductive material. The at least one first conductive material is at least partially different from the at least one second conductive material. One of the first resin and the second resin may comprise a reactant resin and a reactive resin which is cross-linked with the reactant resin. The PTC resistor may comprise a flame retardant agent. The PTC resistor may comprise a liquid-resistant resin.