A step-sintering method for preparing lithium magnesium silicate (LMS, Li2MnSiO4) can produce better optimized-Li2MnSiO4 (O-LMS) with smaller aggregates, more homogeneous phase and better electrochemical performance compared with Li2MnSiO4 prepared by continuously raising the temperature during the thermal treatment used to form Li2MnSiO4. The formation of Li2MnSiO4 is accompanied by three endothermic peaks (>200°C) whose activation energies are calculated to be 350.78, 117.16 and 227.59kJmol−1 respectively using Kissinger differential method. The cell with a step-sintered O-LMS cathode can retain 73.5% of the initial discharge capacities after the 15th cycles, whereas only 55.6% for the cell with a continuously sintered LMS cathode.