Reduced graphene oxide for secondary battery, preparation method therefor, and electrode and secondary battery which use same

A method of preparing a reduced graphene oxide for secondary battery, the method comprising:

• synthesizing graphite oxide flakes from powdery graphite flakes;
• preparing a graphene oxide dispersion solution by introducing the graphite oxide flakes into a solvent, followed by exfoliation and dispersion through pH control;
• preparing a reduced graphene oxide dispersion solution by reducing the graphene oxide dispersion solution;
• and
• preparing the reduced graphene oxide in powder form by spray-drying the reduced graphene oxide dispersion solution,
• wherein the reduced graphene oxide in powder form is a two-dimensional crystalline reduced graphene oxide satisfying Relational Expressions 1 to 3 shown below:
• 1≤TQ≤5 [Relational Expression 1]
• 100≤EQ≤1,000 [Relational Expression 2]
• 1≤BETQ≤100 [Relational expression 3]
• wherein in Relational Expression 1, TQ represents the thickness (nm) of the reduced graphene oxide,
• in Relational Expression 2, EQ represents the electrical conductivity (S/cm) of the reduced graphene oxide, and
• in Relational Expression 3, BETQ represents the specific surface area (m2/g) of the reduced graphene oxide.