Electrode active material with high stability and electrochemical device using the same

The present invention provides an electrochemical device is provided with an electrode active material, the electrode surface treated electrode and the electrode of a compound containing an active material or with the acid site characteristics including the acid sites (acid site) at least a portion of the surface . Inorganic or organic electrode active material according to the present invention is formed on the surface by the inorganic complex acid sites (acid site) to secure structural stability of the can appropriately control the surface acid site strength, as well as the to be formed, part reactive reduction of the electrolyte and the electrode active material It can provide a better performance of the battery through. Electrode active material, a composite, a surface, an electrochemical device, the lithium secondary battery