The Mechanism of Capacity Enhancement in LiFePO[sub 4] Cathodes Through Polyetheramine Coating

This paper addresses the possible mechanisms underlying the capacity enhancement through polyetheramine [PEA, glyceryl poly(oxypropylene)triamine] coating on (Phostech Lithium) particle surface. X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared studies have confirmed the presence of PEA on the surface by the appearance of the N 1s peak in the XPS spectra and bands in the wavenumber range of the IR spectra. Potentiostatic measurements in organic electrolytes have shown that the discharge capacity is increased ca. 12% compared to the as-received material, i.e., more ions are utilized during the redox process. This is due to better wettability of the electrolyte to the particle surface, which is indicated by the slower sedimentation of coated particles. Furthermore, cyclic voltammetry has shown that PEA-coated particles display higher capacity than the as-received material also in an aqueous electrolyte, which to some extent can be explained by the difference in wettability between the materials, but also by the protection of from spontaneous formation of a surface layer and -containing solids when in contact with water.