Varta Batterie Aktiengesellschaft

Peter Kramer

Hans Sauer

Dieter Bechtold

Jurgen Vollbert

Frank Mengel

Dietrich Bartke

Martin G Hake

Reiner Kretzschmar

The invention relates to a rechargeable lithium-ion cell, a method for its manufacture, and its application. The cell is distinguished by the fact that it has a metallic housing (21) which is electrically insulated internally by two half shells (15), which cover electrode plates (8) and main output tabs (7) and are composed of a non-conductive material, where the metallic housing is electrically insulated externally by means of an insulation coating. The cell also has a bursting membrane (4) which, in its normal position, is located above the electrolyte level of the cell (1). In addition, the cell has a twisting protection (6) which extends over the entire surface of the cover (2) and provides centering and assembly functions for the electrode package, which comprises the electrode plates (8).

Rechargeable lithium-ion cell

An Li/LiMn.sub.2 O.sub.4 secondary cell employing a SWING system (i.e., of the 'rocking chair cell' type) includes a positive electrode formed as a metal gauze-reinforced, rolled electrode, and a negative electrode formed by impregnating a nickel foam with a paste of Li-intercalating graphite. Such electrodes are from 3 to 4 times thicker than the thin-film electrodes fabricated with prior, knife-coating techniques and employed in wound cells, and are therefore particularly suitable for constructing prismatic cells. By prerolling the as yet empty nickel foam to specific thicknesses, the capacity per unit area of the negative electrode can be tailored to that of the positive, rolled electrode. By rerolling the impregnated nickel foam, optimal energy density and electrode capacity is achieved, at a porosity of from 50 to 60%.

Electrochemical secondary cell

A spiral-wound galvanic cell is based upon a lithium system with a nonaqueous electrolyte, and includes a positive electrode, the carrier of which is clamped within the slit of a simple metal splint which serves as the winding mandrel and current collector. Contact with the metal splint is established by a leaf spring associated with the housing cover, which then serves as the positive terminal post for the cell. A high specific contact pressure is developed at this connection by providing the leaf spring with a punched hole which rests on thicker top portions of the metal splint. A small metal plate pressed through the lithium electrode and its separator establishes electrical contact between the lithium electrode and the interior wall of the housing vessel, which then serves as the negative cell pole.

Spiral-wound galvanic cell

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Konigstein, Germany

Peter Kramer