Effect of ball-milling and lithium insertion on the lithium mobility and structure of Li3Fe2(PO4)3

The structure and lithium mobility have been investigated for A- and B-Li3Fe2(PO4)3, before and after mechanical milling and lithium insertion, by using Li NMR. The data indicate that the milling step induces a significant amount of defects in the structure, while it improves the ability of the material to take up lithium. The lithium mobility in the different samples was studied by collecting NMR spectra at different temperatures, extensive lithium mobility being observed for both polytypes at temperatures above 150 °C. This mobility was found to be enhanced after milling. The enhancement in the electrode material utilization is ascribed to both a reduction of the diffusion lengths (particle size) and an increase in the intrinsic mobility of lithium in the sample.