▎ 摘　　要

NOVELTY - Three-dimensional structure complex comprises alkali metal (M1)-transition metal (M2)-phosphorus-oxide-based phosphate, and graphene. The composite has Brunauer-Emmett-Teller specific surface area of 10-500 m2/g. USE - The three-dimensional structure complex is useful as negative electrode active material (claimed) for sodium secondary battery. ADVANTAGE - The three-dimensional structure complex can be produced through a single process, and economical manner, improves reversibility and charge/discharge capacity, and provides sodium secondary battery having excellent electrochemical characteristics.