The effect of particle size on phase stability of the delithiated Li _xMnPO ₄

The effect of particle size on the phase stability of delithiated Li _xMnPO ₄ (x ≤ 1) is elucidated using temperature- controlled in situ X-ray diffraction (XRD). The phase transformation of Li _xMnPO ₄ (x ≤ 1) at high temperature was apparently altered by the particle size. While Li _xMnPO ₄ phase having large particle size (ca. 200 nm to 1 m) decomposed into Mn ₂P ₂O ₇ at the temperature between 200°C and 250°C, consistent with previous studies, phase transformation into Mn ₃(PO ₄) ₂ was observed at the same temperature when the delithiated Li _xMnPO ₄ phase had a small particle size (ca. 50 nm). This indicates that the phase transformation of a LiMnPO ₄-based battery may vary with particle size.