Synthesis of La-doped Li2MnSiO4 nano-particle with high-capacity via polyol-assisted hydrothermal method

Li2Mn1LaxSiO4/C (x = 0, 0.01 and 0.04) composites are prepared via a polyol-assisted hydrothermal method followed by carbon coating. X-ray diffraction patterns confirm that the unit cell volume of Li2MnSiO4 has been enlarged by doping a small amount of La3+. The scanning electron micrographs and elemental maps indicate that the sizes of the Li2MnSiO4 particles can be reduced by homogeneously doping La3+. The transmission electron microscopy shows the well crystallized Li2MnSiO4 nanoparticles. The electrochemical performances of all samples are evaluated by galvanostatic charge/discharge tests and electrochemical impedance spectroscopy. 1 at.% La3+ doped Li2MnSiO4 (AL1) delivers the highest initial discharge capacity of about 257 mAh g−1, corresponding to the intercalation of about 1.55 lithium ions per formula unit. AL1 also exhibits improved capacity retentions of about 51.1%. The above improvements of electrochemical properties are related to the decreased charge transfer resistance and enhanced lithium ion diffusion for La-doped samples, whose crystal structure is maintained and lattice has been slightly enlarged.