An electrochemical device comprising a cathode, an anode and an electrolyte, wherein the cathode, the anode or both electrodes are an electrode comprising a current collector; an electrode active material layer formed on at least one surface of the current collector and comprising a mixture of electrode active material particles and a first binder polymer; and a porous coating layer formed on the surface of the electrode active material layer, comprising a mixture of inorganic particles and a second binder polymer and having a thickness deviation defined by the following Formula: T max − T min / T avg ≤ 0.35 wherein T max is a maximum thickness of the porous coating layer formed on the surface of the electrode active material layer, T min is a minimum thickness of the porous coating layer and T avg is an average thickness of the porous coating layer, the thicknesses of the coating layers being observed by an electron microscope with at least four measurement points,, wherein the inorganic particles and the second binder polymer are used in a weight ratio of 50:50 to 99:1, and wherein the porous coating layer replaces a separator, characterized in that the electrode active material layer has a density ranging from 3.0 to 3.9g/cm 3 when the electrode is a cathode and a density ranging from 1.3 to 1.8g/cm 3 when the electrode is an anode, the inorganic particles comprise inorganic particles having the ability to transport lithium ions, wherein the inorganic particles having the ability to transport lithium ions are inorganic particles of any one selected from the group consisting of lithium phosphate Li 3 PO 4, lithium titanium phosphate Li x Ti y (PO 4) 3 with 0<x<2, 0<y<3, lithium aluminum titanium phosphate Li x Al y Ti z (PO 4) 3 with 0<x<2, 0<y<1, 0<z<3, (LiAlTiP) x O y type glass with 0<x<4, 0<y<13, lithium lanthanum titanate Li x La y TiO 3 with 0<x<2, 0<y<3, lithium germanium thiophosphate Li x Ge y P z S w with 0<x<4, 0<y<1, 0<z<1, 0<w<5, lithium nitride Li x N y with 0<x<4, 0<y<2, SiS 2 type glass Li x Si y S z with 0<x<3, 0<y<2, 0<z<4, P 2 S 5 type glass Li x P y S z with 0<x<3, 0<y<3, 0<z<7, and a mixture thereof. a current collector; an electrode active material layer formed on at least one surface of the current collector and comprising a mixture of electrode active material particles and a first binder polymer; and a porous coating layer formed on the surface of the electrode active material layer, comprising a mixture of inorganic particles and a second binder polymer and having a thickness deviation defined by the following Formula: T max − T min / T avg ≤ 0.35 wherein T max is a maximum thickness of the porous coating layer formed on the surface of the electrode active material layer, T min is a minimum thickness of the porous coating layer and T avg is an average thickness of the porous coating layer, the thicknesses of the coating layers being observed by an electron microscope with at least four measurement points,, wherein the inorganic particles and the second binder polymer are used in a weight ratio of 50:50 to 99:1, and wherein the porous coating layer replaces a separator, characterized in that the electrode active material layer has a density ranging from 3.0 to 3.9g/cm 3 when the electrode is a cathode and a density ranging from 1.3 to 1.8g/cm 3 when the electrode is an anode, the inorganic particles comprise inorganic particles having the ability to transport lithium ions, wherein the inorganic particles having the ability to transport lithium ions are inorganic particles of any one selected from the group consisting of lithium phosphate Li 3 PO 4, lithium titanium phosphate Li x Ti y (PO 4) 3 with 0<x<2, 0<y<3, lithium aluminum titanium phosphate Li x Al y Ti z (PO 4) 3 with 0<x<2, 0<y<1, 0<z<3, (LiAlTiP) x O y type glass with 0<x<4, 0<y<13, lithium lanthanum titanate Li x La y TiO 3 with 0<x<2, 0<y<3, lithium germanium thiophosphate Li x Ge y P z S w with 0<x<4, 0<y<1, 0<z<1, 0<w<5, lithium nitride Li x N y with 0<x<4, 0<y<2, SiS 2 type glass Li x Si y S z with 0<x<3, 0<y<2, 0<z<4, P 2 S 5 type glass Li x P y S z with 0<x<3, 0<y<3, 0<z<7, and a mixture thereof. wherein T max is a maximum thickness of the porous coating layer formed on the surface of the electrode active material layer, T min is a minimum thickness of the porous coating layer and T avg is an average thickness of the porous coating layer, the thicknesses of the coating layers being observed by an electron microscope with at least four measurement points,, wherein the inorganic particles and the second binder polymer are used in a weight ratio of 50:50 to 99:1, and wherein the porous coating layer replaces a separator, characterized in that the electrode active material layer has a density ranging from 3.0 to 3.9g/cm 3 when the electrode is a cathode and a density ranging from 1.3 to 1.8g/cm 3 when the electrode is an anode, the inorganic particles comprise inorganic particles having the ability to transport lithium ions, wherein the inorganic particles having the ability to transport lithium ions are inorganic particles of any one selected from the group consisting of lithium phosphate Li 3 PO 4, lithium titanium phosphate Li x Ti y (PO 4) 3 with 0<x<2, 0<y<3, lithium aluminum titanium phosphate Li x Al y Ti z (PO 4) 3 with 0<x<2, 0<y<1, 0<z<3, (LiAlTiP) x O y type glass with 0<x<4, 0<y<13, lithium lanthanum titanate Li x La y TiO 3 with 0<x<2, 0<y<3, lithium germanium thiophosphate Li x Ge y P z S w with 0<x<4, 0<y<1, 0<z<1, 0<w<5, lithium nitride Li x N y with 0<x<4, 0<y<2, SiS 2 type glass Li x Si y S z with 0<x<3, 0<y<2, 0<z<4, P 2 S 5 type glass Li x P y S z with 0<x<3, 0<y<3, 0<z<7, and a mixture thereof.