Procedure for preparing a positive electrode material by extrusion in the presence of an aqueous solvent, positive electrode obtained by the process and applications

摘要

Method of preparing a positive electrode consisting of a composite material comprising the following ingredients: - at least one positive electrode active material selected from iron phosphate based materials, - at least one water-soluble polymer and having properties of ionic conduction in the presence of a lithium salt, - at least one lithium sa and - possibly at least one material that confers electronic conduction properties, said process comprising at least one stage of mixing, by extrusion, of the ingredients of the composite material to obtain an extruded composite material, at least one step of forming the extruded material through a matrix, at least one stage of rolling or calendering of the extruded composite material in the form of a positive electrode film on a current collector, and at least one drying stage of the positive electrode film applied on the collector of current, said procedure being characterized in that the extrusion step is carried out by means of a co-mixer, a double screw extruder, or a multi-screw extruder, in the presence of an aqueous solvent constituted of demineralized or distilled water or of a mixture of demineralized or distilled water and of at least one hydromiscible solvent representing as m a maximum of 30% by mass of the total mass of the aqueous solvent, said aqueous solvent representing approximately 3 to 25% by mass with respect to the total mass of the ingredients constituting the composite material, and at a temperature of 20 to 95 ° C, and because the water-soluble polymer is selected from polymers, copolymers and terpolymers of polyoxyethylene, polyoxypropylene and polyoxybutylene.