PNNL

Abstract

LiMnPO4 is synthesized from MnPO4•H2O precursor precipitated via a spontaneous reaction. These MnPO4•H2O nano-plates react quickly with the lithium source and form a pure phase of LiMnPO4 that has good electrochemical properties. Thermogravimetric analysis (TGA) was used to determine the optimum synthesis temperature. It is found that the crystallization of LiMnPO4 occurs before 438°C. After full nucleation at 550°C, the samples exhibit a discharge capacity of 115mAh/g (C/20 rate, 2.5-4.4 V) in the first cycle. The Coulombic efficiency is maintained at near 100% after the first few cycles.When the synthesis temperature decreases to 350°C, the particle size of the LiMnPO4 is further reduced to 10-50 nm with a reversible capacity of more than 90 mAh/g. For 550°C-synthesized LiMnPO4, 73% of the initial capacity is retained at the sixtieth cycle. After high rate (5C) discharge, the reversible capacity of the LiMnPO4 can be recovered to nearly the original value of 110 mAh/g at the C/20 rate. This precipitation method provides a cost effective approach for manufacturing high-performance LiMnPO4 cathode material for Li-ion batteries.