Preparation and electrochemical properties of cationic substitution Li2Mn0.98M0.02SiO4 (M = Mg, Ni, Cr) as cathode material for lithium-ion batteries

Abstract

Li2Mn0.98M0.02SiO4 (M = Mg, Ni, Cr) cathode material for lithium-ion batteries was synthesized by traditional solid-phase doping method used Li2CO3, MnCO3, (C2H5O)4Si, and MgC2O4·2H2O (or NiC2O4·2H2O or C2O3) as staring materials. The suitable calcination temperature (700 °C) was obtained by TG-DTA curve. The influence of different doping amount on the crystal structure, micromorphology, and electrochemical properties of Li2MnSiO4 was studied by XRD, SEM, and electrochemical performance measurement. The XRD patterns indicate that the Li2MnSiO4 crystallized in an orthorhombic structure with a space group of Pmn21. It can be seen from SEM images that Mg doping has no effect on the micromorphology, Cr doping can refine the powder, and the particle size is about 200–800 nm. The electrochemical performance measurement demonstrates that the Li2Mn0.98Cr0.02SiO4 shows the best electrochemical performance with an initial discharge capacity of 29.8 mAh g−1 at 0.1 C, and the discharge capacity retention rate after 70 cycles is 20.1%.