In this study, binary core-shell CoSe2/CoO nanocomposites are synthesized as cathodic electrodes for the Li-O-2 cell, which exhibits enhanced cycle performance. From theoretical calculations, aberration-corrected scanning transmission electron microscopy observation, and gas chromatography mass spectrum verification, we propose that an enhanced cycle performance can be attributed to the improvement of the compatibility of the cathode/Li2O2 interface, which results from preferable interaction between Li2O2 intermediates and the CoO "shell" and then reduction of interfacial Li2CO3 formation on the carbon surface. Furthermore, our findings demonstrate that the CoSe2 "core" may impact the electronic structure of surface metal ions, generating a superior cycling performance than that of pristine CoO materials. These results will offer some critical insights into the mechanistic process of Li-O-2 batteries.