Negative-electrode active material for sodium-ion secondary battery, method for manufacturing said negative-electrode active material, and sodium-ion secondary battery

A method of producing a negative-electrode active substance for a sodium-ion secondary battery, comprising:

• a step of providing an organic material to serve as a carbon source;
• and
• a step of subjecting the organic material to a heat treatment in an inert atmosphere to obtain a porous carbon material, wherein,
• the organic material is a cellulose-type resin;
• the porous carbon material has a plurality of open pores that extend through to a surface, a plurality of closed pores that do not extend through to the surface, and a solid portion made of carbon material;
• a distance between (002) planes of carbon in at least a part of the solid portion is not less than 0.36 nm and not more than 0.41 nm;
• and
• the plurality of closed pores account for a volume ratio of not less than 30% and not more than 90% with respect to a total volume of the plurality of open pores, the plurality of closed pores, and the solid portion.

A method of producing a negative-electrode active substance for a sodium-ion secondary battery, comprising:

• a step of providing an organic material to serve as a carbon source;
• a step of pulverizing the organic material in a mortar;
• and
• a step of subjecting the pulverized organic material to a heat treatment in an inert atmosphere to obtain a porous carbon material, wherein,
• the organic material is phenolphthalein;
• the porous carbon material has a plurality of open pores that extend through to a surface, a plurality of closed pores that do not extend through to the surface, and a solid portion made of carbon material;
• a distance between (002) planes of carbon in at least a part of the solid portion is not less than 0.36 nm and not more than 0.41 nm;
• and
• the plurality of closed pores account for a volume ratio of not less than 30% and not more than 90% with respect to a total volume of the plurality of open pores, the plurality of closed pores, and the solid portion.

A method of producing a negative-electrode active substance for a sodium-ion secondary battery, comprising:

• a step of providing a carbon material having porosity;
• and
• a step of subjecting the carbon material having porosity to a heat treatment in an inert atmosphere to obtain a porous carbon material, wherein,
• the carbon material having porosity is an activated carbon material;
• the porous carbon material has a plurality of open pores that extend through to a surface, a plurality of closed pores that do not extend through to the surface, and a solid portion made of carbon material;
• a distance between (002) planes of carbon in at least a part of the solid portion is not less than 0.36 nm and not more than 0.41 nm;
• and
• the plurality of closed pores account for a volume ratio of not less than 30% and not more than 90% with respect to a total volume of the plurality of open pores, the plurality of closed pores, and the solid portion.

A method of producing a negative-electrode active substance for a sodium-ion secondary battery, comprising:

• a step of providing a carbon material having porosity;
• and
• a step of subjecting the carbon material having porosity to a heat treatment in an inert atmosphere to obtain a porous carbon material, wherein,
• the carbon material having porosity is a template carbon material;
• the porous carbon material has a plurality of open pores that extend through to a surface, a plurality of closed pores that do not extend through to the surface, and a solid portion made of carbon material;
• a distance between (002) planes of carbon in at least a part of the solid portion is not less than 0.36 nm and not more than 0.41 nm;
• and
• the plurality of closed pores account for a volume ratio of not less than 30% and not more than 90% with respect to a total volume of the plurality of open pores, the plurality of closed pores, and the solid portion.