The Doping of FeNb11O29 as a Way to Improve Its Electrochemical Performances

FeNb11O29, with the possibility to exchange up to 23 electrons
per formula unit and a theoretical capacity value of 400 mAh/g,
is nowadays a very promising anode material for Li-ion
batteries. However, the improvement of its electrochemical
performances is still an open challenge, and the doping is a
well-recognized method to obtain this goal. In this paper,
orthorhombic Fe0.8Mn0.2Nb11O29 and Fe0.8V0.2Nb11O29 samples
were prepared by solid state synthesis. The redox processes, as
determined by cyclic voltammetry, involve only Fe and Nb ions
as in the undoped compound. FeNb11O29 is a well-known mixed
oxide with pseudocapacitive behavior, which is increased with
the Mn doping. The doped samples show better performances
during long term cycling at 2 C, with capacities of 240 and 220
mAh/g and capacity retention of 100.9 and 98.7% for Mn and V
doped respectively.