Stabilizing the high voltage LiCoPO4 cathode via Fe-doping in the gram-scale synthesis

We report the effect of Fe doping on the electrochemical performance of the olivine structure LiCoPO 4 . Here, we employed a solid-state approach followed by a carbon coating for the synthesis of LiFe x Co 1- x PO 4 @C (0 < x < 0.25) in a simple two-step procedure. The structural characteristics of the gram-scale prepared cathodes are investigated by various analytical tools and observed that ∼10 wt.% of carbon content efficiently enhances the electrical conductivity. The galvanostatic studies endorses an enhancement in the electrochemical performance of LiFe x Co 1- x PO 4 @C (0 < x < 0.25) compared to bare LiCoPO 4 . Among the various as-synthesized Fe doped samples, LiFe 0.1 Co 0.9 PO 4 @C and LiFe 0.15 Co 0.85 PO 4 @C perform excellent capacity retention characteristics of 67 and 78% after 50 cycles, respectively, and are optimized to be the better Fe dopant concentrations. Further, the cyclic voltammetry and electrochemical impedance spectroscopy studies display better electronic as well as, Li + diffusion kinetics upon Fe doping. As a proof of concept, enhancement in Li + ion chemical diffusion co-efficient is also observed in the range of 10 –12 cm 2 s –1 in LiFe x Co 1- x PO 4 @C (0 < x < 0.25) whereas only 10 –15 cm 2 s –1 for LiCoPO 4 . These outcomes recommend this valuable approach toward a gram scale preparation of high voltage Fe-doped LiCoPO 4 .