초록 ▼

A formation procedure for a NiMH electrochemical cell is disclosed that significantly shortens the time required to fully form such a cell. The formation procedure includes a first step during which the cell is charged at a constant voltage of preferably 1.0 volt for approximately three hours. A sec

A formation procedure for a NiMH electrochemical cell is disclosed that significantly shortens the time required to fully form such a cell. The formation procedure includes a first step during which the cell is charged at a constant voltage of preferably 1.0 volt for approximately three hours. A second charging step is performed by applying either a constant charge current at a predetermined rate of C/3 for five hours or applying a constant voltage of 1.45 to 1.5 volts for five to nine hours. A third step may optionally be used whereby the cell is charged at a constant current of C/10 for about two hours. NiMH cells subjected to this formation procedure have a much greater percentage of the starting cobalt material in the positive electrode converted to CoOOH thereby improving the conductive matrix formed about the Ni(OH).sub.2 /NiOOH particles, which constitute the active material of the positive electrode. The disclosed inventive formation procedures result in higher utilization, higher cell capacities following long-term storage, or storage at high temperatures as well as improved capacity recovery following deep discharge.

대표청구항 ▼

[ The invention claimed is:] [1.]1. A method of forming a cobalt-containing NiMH electrochemical cell comprising the steps of:(a) providing an assembled electrochemical cell having a positive electrode comprising a cobalt(II) compound and Ni(OH).sub.2 ; and(b) charging said cell at a constant voltag

[ The invention claimed is:] [1.]1. A method of forming a cobalt-containing NiMH electrochemical cell comprising the steps of:(a) providing an assembled electrochemical cell having a positive electrode comprising a cobalt(II) compound and Ni(OH).sub.2 ; and(b) charging said cell at a constant voltage, wherein the constant voltage is about 1.0 volt and below 1.1 volt, wherein the current during charging varies from 0 to C/20 mA; and(c) charging said cell, after step (b), at a first constant current.