COMPOSITE GRAPHITE PARTICLES AND PRODUCTION METHOD THEREFOR, AND CATHODE MATERIAL OF LITHIUM ION SECONDARY BATTERY AND LITHIUM ION SECONDARY BATTERY USING THIS

摘要

A lithium ion secondary battery capable of very successfully achieving both performances that have been conventionally incompatible and difficult to accomplish concurrently - a high initial charging/discharging efficiency and a large discharge capacity, and also being provided with both of excellent quick discharge characteristics and cyclic characteristics; and constituting materials thereof. Specifically, composite graphite particles comprising a carbon material, lower in crystallinity than graphite having an X-ray diffraction interplanar spacing d002 of less than 0.337 nm, on the at least surface portion of the graphite, wherein the aspect ratio of the composite graphite particles is up to 3, 0.5-20 mass% of the composite graphite particles consists of the carbon material, and a ratio (I1580/I1360) between a peak intensity (I1580 ) at 1580 cm<-1> at the Raman spectrum of the composite graphite particles and a peak intensity (I1360)at 1360 cm<-1> is at least 0.1 and less than 0.3, and a production method therefore; and a cathode material and a lithium secondary battery using the composite graphite particles.