Varta Batterie Aktiengesellschaft

Martin G Hake

Peter Kramer

Frank Mengel

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%.

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Idstein-Eschenhahn, Germany

Martin G Hake