An integrated electrode assembly having a structure in which a cathode, an anode, and a separation layer disposed between the cathode and the anode are integrated with one another, wherein the separation layer has a multilayer structure comprising: at least one two-phase electrolyte comprising a liquid phase component and a polymer matrix; and at least one three-phase electrolyte comprising a liquid phase component, a solid phase component, and a polymer matrix, wherein the polymer matrices of the separation layer are coupled to the cathode or the anode, and the liquid phase components of the separation layer are partially introduced into an electrode in a process of manufacturing the electrode assembly, characterized in that: - the liquid phase component in the two-phase electrolyte and the liquid phase component in the three-phase electrolyte comprise an ionic salt, - the solid phase component in the three-phase electrolyte supports the separation layer between the cathode and the anode, - in the polymer matrix of the two-phase electrolyte, a linear polymer and a crosslinked polymer form a viscoelastic structure in a state of the liquid phase component being embedded, and - in the polymer matrix of the three-phase electrolyte, a linear polymer and a crosslinked polymer form a viscoelastic structure in a state of the liquid and solid phase components being embedded, wherein the viscoelastic structure has a structure in which independent gels comprising the crosslinked polymer are physically interconnected by the linear polymers in a state in which the liquid phase component is impregnated. wherein the separation layer has a multilayer structure comprising: at least one two-phase electrolyte comprising a liquid phase component and a polymer matrix; and at least one three-phase electrolyte comprising a liquid phase component, a solid phase component, and a polymer matrix, wherein the polymer matrices of the separation layer are coupled to the cathode or the anode, and the liquid phase components of the separation layer are partially introduced into an electrode in a process of manufacturing the electrode assembly, characterized in that: - the liquid phase component in the two-phase electrolyte and the liquid phase component in the three-phase electrolyte comprise an ionic salt, - the solid phase component in the three-phase electrolyte supports the separation layer between the cathode and the anode, - in the polymer matrix of the two-phase electrolyte, a linear polymer and a crosslinked polymer form a viscoelastic structure in a state of the liquid phase component being embedded, and - in the polymer matrix of the three-phase electrolyte, a linear polymer and a crosslinked polymer form a viscoelastic structure in a state of the liquid and solid phase components being embedded, - the liquid phase component in the two-phase electrolyte and the liquid phase component in the three-phase electrolyte comprise an ionic salt, - the solid phase component in the three-phase electrolyte supports the separation layer between the cathode and the anode, - in the polymer matrix of the two-phase electrolyte, a linear polymer and a crosslinked polymer form a viscoelastic structure in a state of the liquid phase component being embedded, and - in the polymer matrix of the three-phase electrolyte, a linear polymer and a crosslinked polymer form a viscoelastic structure in a state of the liquid and solid phase components being embedded, wherein the viscoelastic structure has a structure in which independent gels comprising the crosslinked polymer are physically interconnected by the linear polymers in a state in which the liquid phase component is impregnated.