In this study, this concept is extended into other lithium-excess compounds, and the use of Li3PO4 is targeted. A new binary system with Mo3+ is prepared according to the chemical formula of x Li3PO4 – (1 – x) LiMoO2. Since the molar mass of P is much smaller than that of Nb, the P-based samples are expected to deliver higher reversible capacity. Crystal structures and electrode performance in this binary system are systematically examined. A mixture of Li3PO4 and LiMoO2 was mechanically ball milled at room temperature with a ZrO2 container and balls. The samples of x = 0.4 (Li9/7P2/7Mo3/7O2) and 0.6 (Li11/8P3/8Mo1/4O2) show a relatively small reversible capacities in Li cells (Figure 1). In contrast, the sample of x = 0.2 (Li7/6P1/6Mo2/3O2) delivers the highest reversible capacity of ca. 330 mAh g-1with relatively higher operating voltage compared with the samples without P ions.
From these results, we will discuss the possibility of a new series of high-capacity positive electrode materials with Mo3+ions for rechargeable lithium batteries.