Importance

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Abstract

The electrochemical device of the present invention comprises a positive electrode (2), a negative electrode (1), a nonaqueous electrolyte and a separator (3). The separator (3) includes a porous layer (I) composed of a microporous film composed predominantly of a thermoplastic resin and a porous layer (II) containing a filler having a heat-resistant temperature of 150° C. or higher as the main component. The negative electrode (1) contains graphite having an R value of 0.1 to 0.5 and d₀₀₂ of 0.338 nm or less as a negative electrode active material, where the R value is a ratio of a peak intensity at 1360 cm⁻¹ to a peak intensity at 1580 cm⁻¹ in an argon ion laser Raman spectrum and the d₀₀₂ is a lattice spacing between 002 planes. The ratio of the graphite to the negative electrode active material is 30 mass % or more, and the nonaqueous electrolyte contains vinyl ethylene carbonate or a derivative thereof, or a dinitrile compound or acid anhydride.

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First Claim