NOVELTY - The stirrer comprises a premixer for mixing ferric solution and lithium solution, and a tube that provides supercritical water to a main mixer for agitating the ferric solution and the lithium solution, where the supercritical water is emitted through multiple nozzles. A center tube in which the ferric solution and the solution are mixed and passed through the center of the main mixer. The center tube is connected to perpendicular direction to both sides of the supercritical water tube. The center tube is inclinedly connected to both sides of the supercritical water tube.    USE - The stirrer is useful for producing cathode active material (claimed) that is useful in lithium-ion secondary battery in hybrid electric vehicles.    ADVANTAGE - The lithium solution and ferric solution are mixed by spraying the supercritical water emitted through the nozzle so as to widen the reaction area and to provide even and uniform mixing due to the flow of the supercritical water is minimized and delayed before the supercritical water is emitted in advance. The pre-mixer can segregate the ferric salt in the ferric solution and lithium solution in the introduction line due to the application of the supercritical water so that the cathode active material is smoothly produced with high quality.    DETAILED DESCRIPTION - The stirrer comprises a premixer for mixing ferric solution and lithium solution, and a tube that provides supercritical water to a main mixer for agitating the ferric solution and the lithium solution, where the supercritical water is emitted through multiple nozzles. A center tube in which the ferric solution and the solution are mixed and passed through the center of the main mixer. The center tube is connected to both sides of the supercritical water tube in perpendicular direction, and is inclinedly connected to both sides of the supercritical water tube with an acute angle. The nozzle is arranged in multiple rows and is positioned in an upstream or downstream relative to the position of the center tube. An extension part in which the flow cross section of the supercritical water is expanded at the end of the supercritical water tube. The nozzle is formed in the extension part. The extension part is formed in order to surround the center tube.