Effect of Milling on the Electrochemical Properties of Nanostructured Li(Fe0.8Mn0.2)PO4 as Cathodes for Li-ion Batteries

Abstract

Phospho-olivine Li(Fe0.8Mn0.2)PO4 was synthesized using high-temperature solid state procedure. Ball milling was used to decrease the particle size of the active material. X-ray diffraction (XRD) confirmed formation of the phospho-olivines. The crystallite size of the ball-milled particles was calculated about 64.9 nm. Scanning electron microscopy (SEM) also showed polygonal particles of the ball-milled Li(Fe0.8Mn0.2)PO4 and homogeneous distribution of the iron and manganese. Electrochemical evaluation of the ball-milled Li(Fe0.8Mn0.2)PO4 demonstrated faster kinetic reaction with respect to the as-synthesized Li(Fe0.8Mn0.2)PO4. The ball milling process led to highest capacity between the samples (150 mAh g-1 at 0.1 mA cm-2); however, annealing the ball-milled samples showed the best cyclic performance (3% fading after 50 cycles). Ball milling process caused nanostructured Li(Fe0.8Mn0.2)PO4 with lower diffusion length, higher electrical conductivity and higher capacity.