Sumitomo Chemical Company, Limited

Kenichiro Kami

Kenji Nakane

Yasunori Nishida

Hitoshi Miura

Taketsugu Yamamoto

Katsuhiko Iwasaki

Atsushi Terahara

Tomoari Satoh

Tatsuo Tateno

Genjiro Nishikata

A cathode for a lithium secondary battery wherein the surface of the cathode of which a composition containing a cathode active material, a conductive substance and a binder is supported on a current collector, is coated with at least one ion-permeable resin selected from resins having a temperature of deflection under load (measured at 18.6 kg/cm,load according to JIS K 7207) not lower than 100 &deg; C., provide a lithium secondary battery with high energy density having improved safety.

Cathode for lithium secondary battery

A lithium secundary battery cathode composition comprising a cathode active material, a conductive substance and a binder, wherein the binder comprises a fluororesin and a polyolefin resin, and the amount of the fluororesin in the composition is 1 to 10% by weight and the amount of the polyolefin resin in the composition is 0.1 to 2% by weight. The cathode using the cathode composition of the present invention has an excellent binding property with a current collector, and the lithium secondary battery of the present invention has a high energy density and improved safety against an external heating, and the industrial value is very high.

The invention provides a cathode for a lithium secondary battery including lithiated nickel dioxide with a large discharge capacity as an active material and having a high density so that a larger amount of the active material can be charged in a battery container with a limited volume, a production method for the same and a lithium secondary battery utilizing the cathode. The cathode for a lithium secondary battery includes lithiated nickel dioxide as an active material, and the lithiated nickel dioxide is produced by firing a mixture of a lithium compound and a nickel compound at a temperature ranging between 350.degree. C. and 800.degree. C. The supernatant obtained by dispersing 5 g of the lithiated nickel dioxide in 100 cm.sup.3 of water in a glass vessel for 5 minutes and allowing the resultant solution to stand for 30 seconds has pH of 12.00 or less. The production method includes the steps of obtaining the lithiated nickel dioxide as above and treating or milling the lithiated nickel dioxide in an atmosphere including carbon dioxide.

Cathode for lithium secondary battery and production method for the same

Provided is a lithium secondary battery comprising an electrode assembly which consists of a cathode, an anode and a separator laminated therebetween, and a battery case in which the electrode assembly is placed, said lithium secondary battery characterized by having a thermal switch which has a mechanism for electrically connecting the cathode and the anode at a portion other than an active material-contained layer in accordance with an increase in the battery temperature. The lithium secondary battery can prevent itself from being left in a charged condition after having an unusual trouble, and can operate the safety device even when its internal pressure decreases.

Lithium secondary battery having thermal switch

A non-aqueous electrolyte lithium secondary battery, comprising a cathode containing, as active material, a material that can be doped/undoped with lithium ions, an anode containing, as active material, a carbonaceous material that can be doped/undoped with lithium ions, a separator interposed between the cathode and anode and an electrolyte prepared by dissolving lithium salt in an organic solvent, wherein the anode contains a polymer having carbonate groups represented by the structural formula �I!: ##STR1## said polymer having a number average molecular weight of not less than 300 and not more than 200,000. The lithium secondary battery has cycle life and high-rate capacity which are improved without reducing low-temperature capacity.

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Aichi, Japan

Kenichiro Kami