Lithium intercalation in a lithium excess layered material Li2RuO3 was investigated using two-dimensional model electrodes with a restricted reaction plane of (002). Li2RuO3 films were synthesized on Al2O3(0001) substrate by a pulsed laser deposition, and X-ray diffraction measurements confirmed epitaxial growth of Li2RuO3(002). Electrochemical characterization using cyclic voltammetry and charge/discharge measurements indicated electrochemical reactions with a discharge capacity of 200 mAh g(-1) for the film deposited at 400 degrees C followed by post-annealing at 550 degrees C. The electrochemical activity on the (002) plane indicated three-dimensional lithium diffusion in the two-dimensional layered rocksalt structure through the lithium sites in the transition metal layer. (c) 2012 Elsevier B.V. All rights reserved.