| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a lithium-ion secondary battery having excellent safety and good battery performance, as to a large-sized lithium-ion secondary battery having a battery capacity of 5 Ah or more in particular, and electric capacity of 10 mAh or more per 1 cm<SP>2</SP>of a positive electrode and a negative electrode. <P>SOLUTION: In this lithium-ion secondary battery, olivine type LiFePO<SB>4</SB>which is a material reconciling high potential and high energy density with contradictory elements of high safety and high stability, having iron as a main component, and materializing a low environment load is used as a positive electrode active material, and γ-butyrolactone having a property with both a high dielectric constant and low viscosity, and also having advantages such as excellent oxidation resistance, a high boiling point, a low vapor pressure, a high flash point, and the like is used as a nonaqueous electrolyte. Thereby, the lithium-ion secondary battery having larger size and more excellent safety in comparison with a conventional lithium-ion secondary battery for a power supply of a portable apparatus can be provided. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
