Optimized LiMn y Fe1 − y PO 4 as the Cathode for Lithium Batteries

A new synthesis route has been developed for LiMn y Fe 1-y PO 4 powders. A significant improvement in electrode performance has been achieved by adding carbon black to the synthetic precursor. The carbon-containing LiMn y Fe 1-y PO 4 was synthesized under various conditions and the performance of the cathodes was evaluated using coin cells. The samples were characterized by X-ray diffraction, particle-size distribution measurements, scanning electron microscope observations. and Brunauer, Emmett, and Teller surface area measurements. The addition of carbon black limited the particle size growth and enabled high electronic conductivity. Another advantage is simplification of electrode preparation, only needs the cathode powder to be mixed with hinder. Even at the large Mn content of y = 0.75, a high capacity of 164 mAh/g has been achieved with an average discharge voltage of 3.63 V (595 Wh/kg) at room temperature. In addition, LiMn y Fe 1-y PO 4 demonstrated excellent storage performance at elevated temperatures. The thermal stability of the charged cathode was evaluated by thermogravimetric and differential scanning calorimetric thermal analyses.