Electrochemical performances of LiFe1-xMnxPO4 with high Mn content

A series of LiFe1-xMnxPO4/C materials with high Mn content (0.7 <= x <= 0.9) are synthesized by solid state reaction. The samples have mesoporous structure with an average pore size of 25 nm, particle size around 200-300 nm, crystalline size around 30 nm and specific areas around 50 m(2) g(-1). Their electrochemical performances are studied and the reversible capacity and rate performance decrease with the increase of Mn content. The redox potential of the Fe2+/Fe3+ and Mn2+/Mn3+ redox couple also shift accordingly. The overpotential value of the Mn2+/Mn3+ redox couple (80 mV) is close to that of the Fe2+/Fe3+ couple (60 mV) in all three compositions and shows a maximum (similar to 300 mV) in the regions of voltage transition. (C) 2010 Elsevier B.V. All rights reserved.