Synthesis, Characterization and Electrochemical performance of Li_2Mn_(0.7)Fe_(0.3)SiO_4 Prepared from Solid-state Reaction

摘要

Li_2MSiO_4(M=Mn, Co, Ni) is a potential high capacity cathode material because of its outstanding properties that exchange of two electrons per transition metal atom is possible and the theoretical capacity of Li_2MSiO_4 can reach as high as 330 mAhg~(-1). In this family, the cathode performance of Li_2MnSiO_4 synthesized by solution route has been published recently. However, it seems that the cycle life of Li_2MnSiO_4 fell short of our expectation. In this work, the Li_2Mn_(0.7)Fe_(0.3)SiO_4 cathode material was synthesized by traditional solid-state reaction method. The prepared powder was consisted of majority of Li_2Mn_(0.7)Fe_(0.3)SiO_4 and minor impurities which were examined by XRD. FESEM morphology showed that the products of Li_2Mn_(0.7)Fe_(0.3)SiO_4 and Li_2SiO_4 have similar particle size (about 50-300 nm). The electrochemical performance of Li_2Mn_(0.7)Fe_(0.3)SiO_4, especially for reversible capacity and cycle life, exhibited better than those of Li_2MnSiO_4.