Tungsten oxide electrodes were investigated as charge-storage materials for energy-storable dye-sensitized solar cells (ES-DSSCs) The electrochemical and structural properties of the surface-oxidized tungsten (so-WO(3-x)) and monoclinic nanocrystalline WO(3) (nc-WO(3)) were studied on the difference of the charge-discharge properties. Although, the electromotive force (EMF) curve of the so-WO(3-x) was associated with structural change, the so-WO(3-x) did not show the significant structural change indicated by X-ray diffraction (XRD) patterns. On the other hand, the nc-WO(3) showed crystal transformation from monoclinic phase to tetragonal phase The Li(+) diffusion coefficients of the so-WO(3-x) with different Li(+) content ratios obtained by the galvanostatic intermittent titration technique (GITT) did not fall down up to 0 3 of Li/W ratio, whereas the diffusion coefficients of nc-WO(3) decreased about two orders of magnitude in the vicinity of phase transitions The different electrochemical properties could be explained by the less structural change of so-WO(3-x) compared with the nc-WO(3) The large-sized ES-DSSCs with the so-WO(3-x) were fabricated for the first time, and their photocharge-discharge performances were studied (C) 2009 Elsevier B.V All rights reserved