Phase-Homogeneous LiFePO4 Powders with Crystallites Protected by Ferric-Graphite-Graphene Composite

Phase-homogeneous LiFePO4 powders have been synthesized. The content of impurity crystalline phases was less than 0.1%, according to synchrotron diffractometry (SXRD) data. Anisotropic crystallite sizes L¯Vhkl were determined by XRD. A low resistance covering layer mechanically strong ferric-graphite-graphene composite with impregnated ferric (Fe3+) particles < 10 nm in size increases the cycleability compared industrial cathodes. In accordance corrosion model, destruction Fe3+-containing protective crystallites predominates at first stage, and second stage Fe escapes into electrolyte anode. decreases due amorphization that starts from surface. rate capability, Q(t), has studied as a function L¯Vhkl, correlation coefficients rik between sizes, Li diffusion coefficient, D, electrical relaxation time, τel. For test cathode thickness 8 μm, values D = 0.12 nm2/s, τel s obtained. To predict dependence it is theoretically ranges closest experimental values: 0.5 ÷ 0.03 8/1 s, average along [010] L¯1 90/30 nm, averaged r¯ 0/1.