Lithium ion secondary battery

Abstract

Provided is a lithium-ion secondary battery having an excellent initial capacity as well as a good capacity retention rate. The battery comprises a positive electrode comprising a positive electrode active material, a negative electrode comprising a negative electrode active material, and a non-aqueous liquid electrolyte. The negative electrode active material comprises a graphitic material that satisfies each of the following properties: (a) in its Raman spectrum obtained by Raman scattering analysis using an exciting light at a wavelength of 532 nm, having a ratio of its D-peak intensity ID to its G-peak intensity IG, an R value (ID/IG), of 0.15 or smaller; and (b) having a full width at half maximum of the G peak, ΔvG, of 23 cm−1 or smaller. The secondary battery has a capacity retention rate of 70% or greater when subjected to 500 cycles of charging and discharging at a constant current rate of 2 C at 60° C.

Dependencies are inferred from the claim text.