Al3+-doped FeNb11O29 anode materials with enhanced lithium-storage performance

FeNb11O29 has a high theoretical capacity as a potential anode material for lithium-ion batteries; however, the practical capacity of FeNb11O29 reported was unsatisfactory. In this study, a simple and efficient Al3+-doping technique was demonstrated to improve the electrochemical performance of FeNb11O29 successfully. The influences of the Al3+ doping amount were investigated. It was found that the crystal structure of FeNb11O29 could be preserved when a suitable amount of Al3+ was added, and that Al0.2Fe0.8Nb11O29 demonstrated better electrochemical performance than FeNb11O29 because the structure of Al0.2Fe0.8Nb11O29 is more stable. At 0.1C, Al0.2Fe0.8Nb11O29 possessed a high reversible capacity of 318 mAh g−1 with an initial-cycle Coulombic efficiency of 95.0%. Al0.2Fe0.8Nb11O29 exhibited outstanding cycling stability with capacity retention of 92.9% at 10C over after 1000 cycles. Moreover, A LiFePO4/Al0.2Fe0.8Nb11O29 full cell was prepared successfully with a discharge capacity of 206 mAh g−1. The full cell exhibited good cycling stability showing the capacity retention of 84.2% over after 200 cycles at 1C and 89.8% over after 1000 cycles at 5C, respectively. This work suggests that Al0.2Fe0.8Nb11O29 has great application prospects in lithium-ion batteries. A suitable amount of Al3+ doping in FeNb11O29 significantly improves the electrochemical performance (especially the reversible capacity) of FeNb11O29.