A three-dimensional (“3D”) electrode structure includes an electrode collector plate, a plurality of active material plates disposed on the electrode collector plate and protruding from the electrode collector plate, and partition walls arranged on the electrode collector plate and substantially perpendicular to the plurality of active material plates in a plan view so as to provide structural stability of the plurality of first active material plates where the 3D electrode structure may be one of two electrode structures that are spaced apart from each other with an electrolyte layer therebetween.