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AssigneeSony Corporation
InventorsKoji Moriguchi, Mitsuharu Yonemura, Kazuhito Kamei, Masaru Abe, Hideya Kaminaka, Noriyuki Negi, Atsuo Omaru, Masayuki Nagamine
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A graphite powder suitable for a negative electrode material of a lithium ion secondary battery which assures a high discharging capacity not lower than 320 mAh/g is to be manufactured at a lower cost. Specifically, a graphite powder containing 0.01 to 5.0 wt % of boron and having a looped closure structure at an end of a graphite c-planar layer on the surface of a powder, with the density of the interstitial planar sections between neighboring closure structures being not less than 100/μm and not more than 1500/μm, and with d002 being preferably not larger than 3.3650 Å, is manufactured by (1) heat-treating a carbon material pulverized at an elevated speed before or after carbonization for graphization at temperature exceeding 1500° C. or by (2) heat-treating the carbon material pulverized before or after carbonization at a temperature exceeding 1500° C. forgraphization and subsequently further heat-treating the graphized material at a temperature exceeding a temperature of the oxidating heat treatment and the heat treatment in the inert gas.
1-9. (canceled)
A graphite powder formed by graphitization at a temperature ranging from about 1500° C. to less than 2200° C., the graphite powder comprising a carbon material containing about 0.01 to less than 1.0 wt % of boron and having a looped closure structure at an end of a graphite c-planar layer on at least a surface of cleavage formed by shearing, wherein the density of the interstitial planar sections between neighboring closure structures is not less than 100/μm and not more than 1500/μm.
A negative electrode material of a lithium ion secondary battery, the negative electrode material consisting essentially of a graphite powder formed by graphitization at a temperature ranging from about 1500° C. to less than 2200° C., the graphite powder comprising a carbon material containing about 0.01 to less than 1.0 wt % of boron and having a looped closure structure at an end of a graphite c-planar layer on at least a surface of cleavage formed by shearing, wherein the density of the interstitial planar sections between neighboring closure structures is not less than 100/μm and not more than 1500/μm.
A lithium ion secondary battery comprising.
Dependencies are inferred from the claim text.