| 摘要 |
<P>PROBLEM TO BE SOLVED: To constitute a lithium ion secondary battery used for such application that the charging/discharging of a large current is repeated by a power tool or the like, whose cycle life is improved and reliability is enhanced. <P>SOLUTION: The lithium ion secondary battery comprises a negative electrode comprising a negative electrode mixture layer containing a negative electrode active material, a positive electrode comprising a positive electrode mixture layer containing a positive electrode active material, a separator, and a nonaqueous electrolyte. As the negative electrode active material such as a carbon material is used as an R value of a Raman spectrum when excited by an argon laser of a wavelength 514.5 nm is 0.3 to 0.8, with a surface interval d<SB>002</SB>of 002 surface being 0.34 nm or shorter. The density of the negative electrode mixture layer is 1.4-1.6 g/cm<SP>3</SP>. Such a laminate which comprises a porous resin layer whose melting point is 120-140°C and a porous resin layer whose melting point is 150°C or higher or a porous layer whose main material is an inorganic particle whose a heatproof temperature is 150°C or higher is used as a separator. <P>COPYRIGHT: (C)2009,JPO&INPIT |
