Li2+xMn1-xPxSi1-xO4 are prepared by a sol-gel method and characterized as novel cathode materials for lithium ion batteries. Single-phase Li2+xMn1-xPxSi1-xO4 can be obtained when x is equal to 0, 0.05 and 0.1 and the calcination temperature is 700 C. Calcining at 900 degrees C is of no avail to prepare single-phase Li2+5 Mni,P5Si1,04. In contrast to Li2MnSiO4 and Li2.1Mn0.9P0.1Si0.9O4, Li2.05Mn0.95P0.05Si0.95O4 has nearly the same structure at both calcination temperatures. The Li2.05Mn0 95P0.05Si0.95O4/C sample calcined at 700 degrees C has the best electrochemical performance among the three single-phase samples, which is in accordance with the fact that it has the lowest charge transfer resistance. Smaller particle size and larger specific surface area are obtained at higher x value, and all the Li2+xMn1-xPxSi1-xO4/C (x= 0, 0.05 and 0.1) samples have a core-shell structure. The calcination temperature of 700 degrees C is the best between 600 and 800 degrees C in consideration of both phase purity and crystallinity, resulting in the highest discharge capacity Of Li2.05Mn0.95P0.05Si0.9SO4. (C) 2013 Elsevier Ltd. All rights reserved.