US 6,485,864 B1 · Production process of material for lithium-ion secondary batteries, material obtained by the process, and batteries

Abstract

Boron-substituted graphite, which contains N-bonded boron atoms in a small proportion relative to whole substituted boron atoms, is produced by heating a feed fine particulate mixture of an infusibilized carbonaceous material and a boron compound such that the carbonaceous material is carbonized into a carbon structure, raising a temperature of the resulting heated fine particulate mixture promptly to a graphitization treatment temperature in an inert atmosphere unreactive with boron, retaining the graphitization treatment temperature for a time sufficient to allow graphitization of the carbon structure to proceed to a desired extent, and then quickly cooling the resulting graphitized mixture. The boron-substituted graphite is useful as a negative electrode in a lithium-ion secondary battery.

Claims34

Dependent claims

A process for producing a boron-substituted graphite, the boron-substituted graphite containing nitrogen-bonded boron atoms, the nitrogen-bonded boron atoms being present in an amount of 10 atom % or less of surface layer elements relative to whole-substituted boron atoms, which process comprises the steps of:

a) heating a feed fine particulate mixture of an infusibilized carbonaceous material and a boron compound, whereby the carbonaceous material is carbonized into a carbon structure;
b) raising a temperature of the resulting heated fine particulate mixture to a graphitization treatment temperature in an inert atmosphere which is unreactive with boron;
c) retaining said graphitization treatment temperature for a time sufficient to allow graphitization of the carbon structure to proceed to a desired extent;
and
d) cooling the resulting graphitized mixture to a temperature of 100° C. in not more than 100 hours.

2 more elements

A process for the production of boron-substituted graphite, which comprises the following steps:

(a) adding and mixing a boron compound with a carbonaceous material, and heat-treating the resulting mixture;
(b) pulverizing said heat-treated mixture into fine particles;
(c) infusibilizing said fine particles by oxidation treatment;
(d) heating said infusibilized fine particles such that said carbonaceous material is carbonized into a carbon structure;
and
(e) subjecting said heated fine particles to graphitization treatment such that said carbon structure is graphitized;
wherein
in step (a), said carbonaceous material is pitch having a softening point of from 100 to 115° C., said boron compound is added and mixed in a proportion of from 0.1 to 7 wt. % in terms of boron element with said pitch, and the resulting mixture is heat-treated to at least 420° C. such that said pitch is converted into high softening-point pitch comprising 5 to 98 vol. % of optically isotropic portions and having a softening point of at least 250° C.,
in step (b), said fine particles have an average particle size of at most 50 μm,
in step (c), said oxidation treatment is conducted under conditions such that said oxidation-treated particles contain 2 to 10 wt. % of oxygen,
in step (d), said heating is conducted at 600 to 1,200° C.,
in step (e), a temperature of said heated infusibilized fine particles is raised in 100 hours to said graphitization treatment temperature, said graphitization treatment is conducted at at least 2,200° C. for 1 to 12 hours, and said graphitized fine particles are quickly cooled to 100° C. from said graphitization treatment temperature in 100 hours after said graphitization treatment.

9 more elements

Dependencies are inferred from the claim text.

Production process of material for lithium-ion secondary batteries, material obtained by the process, and batteries

Life of this patent

Production process of material for lithium-ion secondary batteries, material obtained by the process, and batteries

Life of this patent

Abstract

Claims34