Hival Ltd.

Voltec Incorporated

Goldtron Limited

Toru Nagaura

To provide a method which allows a battery with a flat base to be produced in a cylindrical battery manufacturing method in which a metallic casing with a larger outside diameter than the outside diameter of the metallic casing in the finished battery is used, a battery element is housed in the said metallic casing, then the outside diameter of the metallic casing reduced; to reduce the occurrence of defective batteries due to deficient electric conduction between the metallic casing and the electrode lead; and to improve the safety of the said cylindrical battery in the event of an outside short circuit. In the making of a battery in which the outside diameter of the metallic casing in the finished battery is A, the outside diameter of the metallic casing used is made to satisfy the relationship L2&gt;A.gtoreq.L3. The battery element, made by winding in a coil shape, is wound so that when winding is completed the end of electrode or electrode current collector of either the negative electrode or the positive electrode is positioned at the outermost periphery of the battery element, then the said battery element is housed in a cylindrical metallic casing, after which the outside diameter of the said metallic casing is reduced to strengthen the contact between the end of electrode or electrode current collector positioned at the outermost periphery of the battery element and the internal wall of the metallic casing, and make the electric resistance of contact between the electrode and metallic casing sufficiently small.

Cylindrical battery

A non-aqueous electrolyte battery wherein the battery element comprising a cathode, an anode and separator, is housed and sealed completely into a cylindrical metallic casing after being impregnated with electrolyte, and said battery is featured by that the opening of its casing is sandwiched between and closed by the insulating gasket placed at the internal surface, and the metallic reinforcement placed at the external surface.

The present invention provides nonaqueous electrolyte secondary cells capable of withstanding severe overdischarge to obtain nonaqueous electrolyte secondary batteries having satisfactory cycle characteristics. A spinel-type lithium-containing metallic oxide represented by LiM.sub.2 O.sub.4 (where M is a transitional metal element) is used as an active substance for each of the positive and negative electrodes of the cell embodying the invention. In an organic electrolyte containing lithium ion, the spinel-type lithium-containing metallic oxide represented by LiM.sub.2 O.sub.4 is capable of reversibly undergoing an electrochemical oxidation reaction involving removal of doping lithium ion and also an electrochemical reduction reaction involving lithium ion doping. Accordingly, when the cell of the invention is overdischarged (.apprxeq. reversibly charged), a reversible reaction involving lithium ion doping/undoping occurs at the positive electrode and negative electrode without entailing any damage due to overdischarge. As a result, when many cells are connected in series to obtain a battery, the cycle characteristics of the battery are not impaired even if the component cells are different in capacity.

Secondary cell

At least one of a positive electrode and a negative electrode constituting an electrode assembly comprises at least two divided electrode portions not connected through electron conduction. The divided electrode portions each have an electrode lead extending outward from a battery container, which has at least two external terminals of the same polarity which is provided by the lead. The external terminals of the same polarity are connected to each other via a resistor having a PTC effect. The battery is assured of improved safety even when large-sized.

Battery having divided electrode portions

A nonaqueous electrolyte secondary battery comprising a cathode, an anode, a separator and a nonaqueous electrolyte, wherein a spinel type lithium manganese complex oxide is used as main active substance for the cathode, which is characterized in that a solid state lithium ion conductor is mixed with the main active substance in the cathode.

Growing community of inventors

Fukuoka, Japan

Toru Nagaura