Sumitomo Chemical Company, Limited

Chikae Yoshimaru

Chikara Murakami

Toshihiko Ogata

Kosuke Kurakane

Ichiro Arise

Syusaku Hara

Daizaburo Yashiki

Junji Suzuki

Hiroki Hashiwaki

Takahiro Okugawa

The present invention provides a nonaqueous electrolyte secondary battery in which a decrease in discharge capacity after a charge-discharge cycle is reduced. The nonaqueous electrolyte secondary battery in accordance with an aspect of the present invention includes (i) a positive electrode plate and a negative electrode plate whose results of a scratch test carried out in the TD and the MD fall within predetermined ranges, (ii) a nonaqueous electrolyte secondary battery separator that includes a porous film whose temperature rise ending period with respect to a resin amount per unit area at irradiation with microwave falls within a predetermined range, and (iii) a porous layer that contains an &#x3b1;-form polyvinylidene fluoride-based resin of a polyvinylidene fluoride-based resin at a predetermined proportion. The porous layer is arranged between the nonaqueous electrolyte secondary battery separator and at least one of the positive electrode plate and the negative electrode plate.

Nonaqueous electrolyte secondary battery

A nonaqueous electrolyte secondary battery which satisfies four requirements is provided. A porous layer contains &#x3b1;-form polyvinylidene fluoride-based resin in an amount of not less than 35.0 mol % with respect to 100 mol % of a total amount of (i) the &#x3b1;-form polyvinylidene fluoride-based resin and (ii) &#x3b2;-form polyvinylidene fluoride-based resin. A porous film has a temperature rise ending period of 2.9 sec&#xb7;m/g to 5.7 sec&#xb7;m/g with respect to an amount of a resin per unit area when the porous film is impregnated with N-methylpyrrolidone containing water in an amount of 3% by weight and then (ii) irradiated, at an output of 1,800 W, with a microwave having a frequency of 2,455 MHz. A positive electrode plate has a capacitance of 1 nF to 1000 nF per measurement area of 900 mm. A negative electrode plate has a capacitance of 4 nF to 8500 nF per measurement area of 900 mm.

Provided is a separator including a first later consisting of a porous polyolefin and a secondary battery utilizing the separator. The first layer exhibits a temperature-increase convergence time equal to or longer than 2.9 s&#xb7;m/g and equal to or shorter than 5.7 s&#xb7;m/g when the first layer is irradiated with a microwave having a frequency of 2455 MHz and an output power of 1800 W after being dipped in N-methylpyrrolidone containing 3 wt % of water. A minimum height of a ball placed over the first layer and having a diameter of 14.3 mm and a weight of 11.9 g is equal to or more than 50 cm and equal to or less than 150 cm, the minimum height causing a split in the first layer when the ball freely falls on the first layer.

Separator and secondary battery including the separator

The present invention provides a nonaqueous electrolyte secondary battery insulating porous layer having an excellent charge resistance characteristic. The nonaqueous electrolyte secondary battery insulating porous layer has a fractal dimension of 2.42 to 2.60, the fractal dimension being calculated from a three-dimensional image showing a void part and a porous layer part on respective two gradation levels, the three-dimensional image being prepared by analyzing images of cross sections obtained by making observation at intervals of 20 nm in a thickness direction from a surface of the nonaqueous electrolyte secondary battery insulating porous layer by FIB-SEM measurement at a magnification of 6500 times.

Nonaqueous electrolyte secondary battery insulating porous layer

The present invention provides a nonaqueous electrolyte secondary battery separator which is excellent in cycle characteristic. The nonaqueous electrolyte secondary battery separator includes a polyolefin porous film in which a difference between (i) a porosity calculated from a continuous image which is formed so as to extend from a surface to an inside of the polyolefin porous film in a thickness direction and in which a void part and a resin part are shown at respective two gray levels and (ii) a porosity calculated from a thickness, a weight per unit area, and a real density of the polyolefin porous film is 4% to 20%.

Nonaqueous electrolyte secondary battery separator

To afford a laminated body that is usable as a nonaqueous electrolyte secondary battery separator and that is not easily curled, a laminated body includes: a porous base material containing a polyolefin-based resin as a main component; and a porous layer containing a polyvinylidene fluoride-based resin, the porous base material having a temperature rise ending period of a particular value with respect to the amount of resin per unit area, the polyvinylidene fluoride-based resin containing crystal form &#x3b1; in an amount of not less than 36 mol % with respect to 100 mol % of a total amount of the crystal form &#x3b1; and crystal form &#x3b2; contained in the polyvinylidene fluoride-based resin.

Laminated body

A nonaqueous secondary battery separator, disposed between a cathode and an anode, includes: a porous base material containing a polyolefin as a main component; and a porous layer containing a polyvinylidene fluoride-based resin on at least one surface of the porous base material. The separator satisfies (C)/(D)&#x2264;0.13, where (C) represents the average pore diameter (&#x3bc;m) of the porous base material, and (D) represents the porosity of the porous base material, in the porous layer after being immersed for 24 hours in an electrolyte solution having a temperature of 25&#xb0; C. in which electrolyte solution LiPFhaving a concentration of 1.0 mole per liter is dissolved in a mixed solvent containing ethyl methyl carbonate, diethyl carbonate, and ethylene carbonate at a volume ratio of 50:20:30, the resin having absorbed the electrolyte solution having a volume of 0.05 to 5.00 cmper square meter of the porous layer.

Laminated body, separator, and nonaqueous secondary battery

Provided is a laminate which is capable of ensuring a high level of safety by preventing an internal short circuit due to, for example, breakage of a non-aqueous electrolyte secondary battery while maintaining various performance capabilities of the non-aqueous electrolyte secondary battery. A laminate () includes: a porous film containing polyolefin as a main component; and a porous layer containing fine particles; the porous layer being laminated to at least one side of the porous film, in an electrical conduction test by nail penetration in which test a displacement in a thickness direction of the laminate () during a period from when a dielectric breakdown occurs in the laminate () to when the laminate () is brought into electrical conduction is measured by use of a nail () of N50 specified in JIS A 5508 and under a condition in which the nail () descends at a descending speed of 50 &#x3bc;m/min, the displacement being not less than 20 &#x3bc;m and not more than 200 &#x3bc;m.

Laminate, non-aqueous electrolyte secondary battery separator including the laminate, and non-aqueous electrolyte secondary battery including the laminate

Provided is a laminate which is capable of ensuring a high level of safety by preventing an internal short circuit due to, for example, breakage of a non-aqueous electrolyte secondary battery while maintaining various performance capabilities of the non-aqueous electrolyte secondary battery. A laminate () includes: a porous film containing polyolefin as a main component; and a porous layer containing fine particles; the porous layer being laminated to at least one side of the porous film, in an electrical conduction test by nail penetration in which test a difference between (a) a test force of the laminate () which is brought into electrical conduction and (b) a test force of the laminate () in which a dielectric breakdown occurs, the difference being obtained by subtracting the test force (b) from the test force (a), is measured by use of a nail () of N50 specified in JIS A 5508 and under a condition in which the nail () descends at a descending speed of 50 &#x3bc;m/min, the difference being not less than 5 N and not more than 50 N.

A first laminated body includes: a porous film containing a polyolefin as a main component; and a porous layer on at least one surface of the porous film, the porous layer containing a resin. A second laminated body includes: a porous film containing a polyolefin as a main component; and a porous layer containing a resin. The laminated body is usable as a secondary battery separator having a higher dielectric strength. A third laminated body is provided in which occurrence of a curl is prevented. A nonaqueous secondary battery separator is provided disposed between a cathode and an anode, the separator including: a porous base material containing a polyolefin as a main component; and a porous layer on at least one surface of the porous base material, the porous layer containing a polyvinylidene fluoride-based resin.

A laminated body of the present invention includes: a porous film containing a polyolefin as a main component; and a porous layer on at least one surface of the porous film, the porous layer containing a resin, the laminated body satisfying 0&#x2266;(A)&#x2212;(B)&#x2266;20 mN/m, where (A) represents the critical surface tension over the outermost surface of the porous layer, and (B) represents the critical surface tension that, in a case where the porous layer has been peeled from the laminated body at an interface with the porous film, the porous film has on the side of the interface.

A laminated body of the present invention includes: a porous film containing a polyolefin as a main component; and a porous layer containing a resin, the laminated body satisfying (A)&#x3e;(B), where (A) represents the amount of an increase in the dielectric strength with respect to the amount of an increase in the amount of the resin contained per unit area of the porous layer, and (B) represents the amount of an increase in the dielectric strength with respect to the amount of an increase in the amount of the polyolefin contained per unit area of the porous film. The laminated body is usable as a secondary battery separator having a higher dielectric strength.

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Osaka, Japan

Chikae Yoshimaru