Facile synthesis and high lithium storage properties of mesoporous polypyrrole coated CoFe2O4 nanofibers

The CoFe2O4 has been recognized as promising anode materials for lithium ions storage because of its merits of high theoretical capacity, low price and environmental friendliness. However, conductivity and structure stability are highly concerned as anode materials in lithium ion batteries (LIBs) applications. Herein, a mesoporous polypyrrole (PPy) coated CoFe2O4 nanofibers were successfully synthesized via combined electrospinning technique and polymerization method. After the covering of polypyrrole, both conductivity and structural stability were improved. Featuring desired specific surface area (SSA), pore distribution and unique nanofiber structure, the as prepared CoFe2O4/PPy showed superior electrochemical performance as anode in LIBs. Briefly, a high reversible capacity of 1246 mAh g−1 after 150 cycles is retained with a coulombic efficiency (CE) of ~100%, which is much higher than that of bare CoFe2O4 nanofibers (693 mAh g−1), for the prepared CoFe2O4/PPy composite nanofibers. The specific capacity of 1309 mAh g−1 is recovered when the current density is reduced back to 0.05 A g−1 after cycling at different current densities ranging from low to high (0.05–2 A g−1) for many cycles. The propped route offers another perspective to improve the electrochemical performance of anode material for LIBs.