The Effect of Particle Size on Phase Stability of the Delithiated LixMnPO4

The effect of particle size on the phase stability of delithiated LixMnPO4 (x < 1) is elucidated using temperature-controlled in situ X-ray diffraction (XRD). The phase transformation of LixMnPO4 (x < 1) at high temperature was apparently altered by the particle size. While LixMnPO4 phase having large particle size (ca. 200 nm to 1 mu m) decomposed into Mn2P2O7 at the temperature between 200 degrees C and 250 degrees C, consistent with previous studies, phase transformation into Mn-3(PO4)(2) was observed at the same temperature when the delithiated LixMnPO4 phase had a small particle size (ca. 50 nm). This indicates that the phase transformation of a LiMnPO4-based battery may vary with particle size. (C) 2011 The Electrochemical Society. [DOI: 10.1149/2.065201jes]