Process for producing spherical carbon material
A process for producing a spherical carbon material, comprising: subjecting a spherical vinyl resin to an oxidation treatment in an oxidizing gas atmosphere to obtain a spherical carbon precursor, and carbonizing the spherical carbon precursor at 1000-2000° C. in a non-oxidizing gas atmosphere. The thus-obtained spherical carbon material exhibits excellent performances, including high output performance and durability, when used, e.g., as a negative electrode material for non-aqueous electrolyte secondary batteries.
1. A process for producing a spherical carbon material, comprising:
subjecting a spherical crosslinked vinyl resin to an oxidation treatment in an oxidizing gas atmosphere to obtain a spherical carbon precursor, and
carbonizing the spherical carbon precursor at 1000-2000° C. in a non-oxidizing gas atmosphere;
wherein the spherical crosslinked vinyl resin comprises a suspension polymerization product of a monomer mixture which comprises 10-80 wt. % of a styrene monomer and 10-90 wt. % of an acrylonitrile monomer, respectively based on the monomer mixture, and further contains a crosslinking agent in a proportion of at least 15 wt. % of the styrene monomer.
2. The production process according to claim 1 , wherein the spherical crosslinked vinyl resin is subjected to the oxidation treatment at a temperature of 150-400° C.
3. The production process according to claim 1 , wherein the suspension polymerization is performed in an aqueous medium containing a dispersion stabilizer comprising colloidal silica in an amount of 0.1-10 wt. parts per 100 wt. parts of the monomer mixture.
4. A negative electrode material for non-aqueous electrolyte secondary batteries, comprising a spherical carbon material produced through a production process according to claim 1 ; wherein the spherical carbon material is a carbonization product of a crosslinked polymer formed by suspension polymerization of a monomer mixture which comprises 10-80 wt. % of a styrene monomer and 10-90 wt. % of an acrylonitrile monomer, respectively based on the monomer mixture, and further contains a crosslinking agent in a proportion of at least 15 wt. % of the styrene monomer; and the spherical carbon material has a nitrogen content of 0.5-5 wt. % and a sphericity of at least 0.8.
5. The negative electrode material according to claim 4 , wherein the spherical carbon material is surface-coated with 0.1-10 wt. % of silicon compound.