Design of phase interface and defect in niobium-nickel oxide for ultrafast Li-ion storage

Niobium pentoxide (Nb2O5) has attracted much attention in lithium batteries due to its advantages of high operating voltage, large theoretical capacity, environmental friendliness and cost-effectiveness. However, the intrinsic poor electrical conductivity, sluggish kinetics, and large volume changes hinder its electrochemical performance at high power density, making it away from the requirements for practical applications. In this research work, we regulate the electron transport of niobium-nickel oxide (NiNbO) anode material with enhanced structural stability at high power density by constructing the two-phase boundaries between niobium pentoxide (Nb2O5) and nickel niobate (NiNb2O6) through simple solid phase reaction. In addition, the presence of lattice defects in NiNbO-F further speeds up the transport of Li+ and promotes the electrochemical reaction kinetics more effectively. The two-phase boundaries and defect modulated anode material displays high Li+ diffusion coefficient of 1.63×10−10 cm2 s−1, pretty high initial discharge capacity of 222.8 mAh g−1 at 1 C, extraordinary high rate performance (66.7 mAh g−1) at an ultrahigh rate (100 C) and ultra-long cycling stability under high rate of 25 C (83.4 mAh g−1 after 2000 cycles) with only 0.016% attenuation per cycle. These results demonstrate an effective approach for developing electrode materials that greatly improve rate performance and durability.