Abstract: Disclosed is a sodium secondary battery. The sodium secondary battery comprises a first electrode and a second electrode comprising a carbonaceous material. The carbonaceous material satisfies one or more requirements selected from the group consisting of requirements 1, 2, 3 and 4. Requirement 1: R value (=ID/IG) obtained by Raman spectroscopic measurement is 1.07 to 3. Requirement 2: A value and ?A value obtained by small angle X-ray scattering measurement are ?0.5 to 0 and 0 to 0.010, respectively. Requirement 3: for an electrode comprising an electrode mixture obtained by mixing 85 parts by weight of the carbonaceous material with 15 parts by weight of poly(vinylidene fluoride), the carbonaceous material in the electrode after being doped and dedoped with sodium ions is substantially free from pores having a size of not less than 10 nm. Requirement 4: Q1 value obtained by a calorimetric differential thermal analysis is not more than 800 joules/g.

Abstract: Disclosed is a sodium secondary battery. The sodium secondary battery comprises a first electrode and a second electrode comprising a carbonaceous material. The carbonaceous material satisfies one or more requirements selected from the group consisting of requirements 1, 2, 3 and 4. Requirement 1: R value (=ID/IG) obtained by Raman spectroscopic measurement is 1.07 to 3. Requirement 2: A value and ?A value obtained by small angle X-ray scattering measurement are ?0.5 to 0 and 0 to 0.010, respectively. Requirement 3: for an electrode comprising an electrode mixture obtained by mixing 85 parts by weight of the carbonaceous material with 15 parts by weight of poly(vinylidene fluoride), the carbonaceous material in the electrode after being doped and dedoped with sodium ions is substantially free from pores having a size of not less than 10 nm. Requirement 4: Q1 value obtained by a calorimetric differential thermal analysis is not more than 800 joules/g.