| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a battery capable of improving battery properties such as a capacity and a cycle property by preventing a negative electrode from being exposed at a low voltage for a long while. <P>SOLUTION: A positive electrode 12 and a negative electrode 14 are arranged with an interposition of a separator 15. The positive electrode 12 includes a phosphate compound containing lithium and iron as a positive electrode active material. An excessive reduction of the negative electrode voltage is suppressed by lowering a charging voltage as at 3.3 V to 3.8 V and a utilization factor expressed as a positive electrode discharge capacity/negative electrode discharge capacity at 90% to 100%. A load on the negative electrode 14 is reduced by lowering the charging voltage and a resistance is reduced by lowering the utilization factor, so that an acceptance property of the negative electrode 14 is improved. It is preferable that there is a mutual action between the charging voltage and the utilization factor and an index K expressed by charging voltage<SP>3</SP>× utilization factor is maintained within a range from 37 to 47 not inclusive. <P>COPYRIGHT: (C)2004,JPO |
