Size and shape controlled LiMnPO₄ nanocrystals by a supercritical ethanol process and their electrochemical properties

In this paper, we report the preparation of systematically size and shape controlled LiMnPO₄ nanocrystals under supercritical fluid conditions. The effect of different reaction conditions such as the reaction time, temperature, surfactant and precursor concentration on the size and shape of the LiMnPO₄ nanocrystals was studied in detail. It was noticed that shorter reaction time and lower reaction temperature facilitated the formation of crystalline LiMnPO₄ nanocrystals with size ∼10 nm. The nanocrystals ranging from 7 to 24 nm were obtained by controlling different reaction conditions. The formation mechanism for the LiMnPO₄ nanocrystals is proposed based on the obtained results. The effect of nanosize on the electrochemical properties of LiMnPO₄ nanocrystals was studied. Improved electrochemical performance was observed for ∼20 nm sized LiMnPO₄ after conductive carbon coating. This study indicates the importance of LiMnPO₄ nanocrystals below 50 nm size in improving the electrochemical performance of LiMnPO₄ cathodes.