In order to improve performance of all-solid-state lithium ion battery with honeycomb structure, a compatibility of two commonly used cathode materials, LiCoO2 and LiMn2O4, to Li0.55La0.35TiO3 (LLT) solid electrolyte was studied. LiCoO2/honeycomb LLT and LiMn2O4/honeycomb LLT half cells were fabricated by the impregnation of mixture of the cathode material with its precursor sol into honeycomb holes followed by the calcination. Impurity phases were observed at interface between LiCoO2 and honeycomb LLT, while no impurity phase was confirmed in the case of LiMn2O4. In half cell test, the LiMn2O4/honeycomb LLT cell showed about 6 times larger discharge capacity than the LiCoO2/honeycomb LLT cell, because of high internal resistance of the LiCoO2/honeycomb LLT cell caused by the impurity phases. It can be said that the formation of low resistance interface at active material/electrolyte is one of the most important key to improve performance of the all-solid-state battery. Using LiMn2O4 instead of LiCoO2, better interface between cathode material and LLT was obtained. (C) 2010 Elsevier BM. All rights reserved.