Enhanced energy storage performance of nanocrystalline Sm-doped CoFe2O4 as an effective anode material for Li-ion battery applications

A simple modified combustion method was demonstrated in the development of cobalt ferrite (CoFe2O4) and samarium (Sm)-doped CoFe2O4 nanostructures. The Sm3+-doped CoFe2O4 can significantly affect their crystallite size, lattice parameter, and electrical and electrochemical properties. The powder X-ray diffraction analysis revealed the formation of cubic spinel CoFe2O4. The structural coordination of pristine and Sm3+-doped CoFe2O4 samples was confirmed by Raman and Fourier transform infrared spectroscopy analyses and also peak positions of Sm3+-doped CoFe2O4 sample shifted toward lower wavenumber, which may be due to the cell expansion resulting from Sm3+ doping in CoFe2O4 structure. In addition to above, X-ray photoelectron spectroscopy results clearly demonstrated the doping of Sm3+ into CoFe2O4 crystal lattice. The electrical conductivity of Sm3+-doped CoFe2O4 is one order of magnitude higher than that of pristine CoF2O4. The prepared pristine and Sm3+-doped CoFe2O4 samples were investigated as an anode material for lithium (Li)-ion batteries. The Sm3+-doped CoFe2O4 anode showed a better reversibility and rate performance than the pristine CoFe2O4 anode. Also, the Sm3+-doped CoFe2O4 electrode exhibited a stable cycling performance with a discharge capacity of 800 mAh g(-1) after 150 cycles at 0.1 C and delivered a discharge capacity of 778 mAh g(-1) after 400 cycles at 200 mA g(-1). The observed high electrochemical performance of Sm3+-doped CoFe2O4 electrode may be attributed to its improved structural stability and enhanced oxidation reaction which maintain the number of Li ions involved in the charge-discharge process.