METHOD FOR PREPARING ALKALI METAL AND TRANSITION METAL FLUOROSULFATES

摘要

The invention relates to a method for preparing an alkali metal and transition metal fluorosulfate that is useful as an electrode material in an electrochemical battery that operates by alkali ion exchange. The method includes a first step that involves: preparing a mixture of precursors of elements making up fluorosulfate, placing said mixture in contact with a solid polymer at ambient temperature, subjecting the reaction medium to a heat treatment that aims to melt the polymer, and subsequently reacting the precursors with one another. Said polymer is one that is solid at ambient temperature, has a melting point lower than the reaction temperature of the precursors, is stable at least up to the reaction temperature of the precursors, and is soluble in a nonpolar aprotic organic solvent.

主权项

1. A method for preparing a material having particles of a compound that has a structure of the tavorite type and that corresponds to the formula (A1-aA′a)x(Z1-bZ′b)z(SO4)sFf (I) in which: A represents Li or Na; A′ represents a vacancy or at least one doping element; Z represents at least one 3d element selected from Fe, Co, and Ni; Z′represents a vacancy or at least one doping element; the subscripts a, b, x, z, s and fare selected so as to ensure electroneutrality of the compound, and a≧0, b≧0, x≧0, z>0, s>0, f>0; and the respective amounts “a” and “b” of dopant A and Z′ are such that the structure of the tavorite type is preserved, said method comprising the steps of:
a 1st step consisting of preparing a mixture of precursors containing a hydrated sulfate of the element or elements Z, the fluoride of the element or elements A, a precursor of the element or elements Z′ when a>0 and a precursor of the element or elements A′ when b>0; a 2nd step consisting of contacting the mixture obtained in the 1st step, with a solid substrate; a 3rd step consisting of bringing the mixture obtained at the end of the 2nd step up to the reaction temperature of the precursors mixed during the 1st step, and maintaining said temperature until the end of the reaction; a 4th step consisting of removing the solid substrate; wherein the solid substrate is a polymer that is solid at room temperature, that has a melting point below the reaction temperature of the precursors and that is stable at least up to the reaction temperature of the precursors, said polymer being soluble in an organic solvent.