A solid-state reaction to synthesize a lithium multi-transition metal phosphate LiCo(1/3)Mn(1/3)Fe(1/3)PO(4) is used in this work, which has a high voltage of 3.72 V and capacity of 140 mAh g(-1) at a 0.05 C rate. From the in-situ XRD analysis, LiCo(1/3)Mn(1/3)Fe(1/3)PO(4) has shown a high stability during cell charge/discharge, even operating at 5 V, which is due to the stable olivine structure. Although all the transition metals Co(2+), Mn(2+) and Fe(2+) are at the same 4c site of the LiCo(1/3)Mn(1/3)Fe(1/3)PO(4) structure, they seem to have different chemical activities and reflect on the electrochemical performance. The capacity contributed by the Co(2+)/Co(3+) redox couple is only 20 mAh g(-1), which is less than that of the Fe(2+)/Fe(3+) and Mn(2+)/Mn(3+) redox couples. This is because of the fact that the diffusivity of lithium ion for the Co(2+)/Co(3+) redox couple is 10(-16) cm(2) s(-1) which is one order less than that of the Fe(2+)/Fe(3+) and Mn(2+)/Mn(3+) redox couples in LiCo(1/3)Mn(1/3)Fe(1/3)PO(4). Crown Copyright (C) 2010 Published by Elsevier B.V. All rights reserved.
