SULFUR-BASED ACTIVE MATERIAL, ELECTRODE, NON-AQUEOUS ELECTROLYTE SECONDARY BATTERY AND PRODUCING METHODS THEREOF

Provided is a sulfur-based active material for a non-aqueous electrolyte secondary battery having a large charge/discharge capacity and excellent cycle characteristics which is inexpensively and easily provided, an electrode comprising the sulfur-based active material, and a non-aqueous electrolyte secondary battery comprising the electrode, as well as a producing method thereof. The sulfur-based active material is obtainable by calcinating a raw material, the raw material comprising (1) a heat-expandable particle comprising an outer shell comprising an acryl-based copolymer and a hydrocarbon included inside the outer shell, the heat-expandable particle having an expansion starting temperature of 150° C. or lower, and (2) sulfur.