Disclosed is an electrode whose surface includes an organic/inorganic composite porous coating layer comprising heat-absorbing inorganic particles and a binder polymer, wherein the heat-absorbing inorganic particle is at least one particle selected from the group consisting of antimony- containing compounds, metal hydroxides, guanidine-based compounds, born-containing compounds and zinc tartrate compounds. A separator using the heat-absorbing inorganic particles as a component for forming or coating the separator, and an electrochemical device including the electrode and/or the separator are also disclosed. The separator using the heat-absorbing inorganic particles as a component for forming or coating the separator can ensure excellent thermal safety and minimizes degradation of the quality of a battery.