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CNO-V 0.005 anode material prepared by simple molten salt method not only has faster lithium-ion diffusion kinetics and lower transfer internal resistance, but also has 276.9 mAh g−1 of high discharge capacity at current density of 2000 mA g−1 over 1000 cycles. [Display omitted] • CoNb 2 O 6 was prepared and was in-situ doped with V5+ ion by a molten-salt method. • The interstitial-doped CNO-V 0.005 exhibits long cycling stability at 2000 mA g−1 (≈ 8C). • The CNO-V 0.005 ||LiFePO 4 full cell has discharge capacity of 150.6 mAh g−1 after 200 cycles. Niobium-based bimetallic oxide, as a potential anode material for fast-charging lithium-ion batteries, has attracted much attention owing to its unique lithium intercalation channel. However, the poor conductivity and structural instability of such material severely limit its further application. In this paper, CoNb 2 O 6 was prepared by a molten-salt method and was in-situ doped with high-valence V5+ ion in different proportions. Different from conventional substitutional doping, a small amount of interstitial doping is more conducive to the entry of V5+ into the gap, which leads to lattice expansion. With the increase of doping amount, elemental Nb5+ was gradually replaced by V5+, which then hinders the Li+ intercalation/de-intercalation to a certain extent. Based on the DFT and electrochemical tests, the interstitial-doped CNO-V 0.005 nanoparticles has not only faster Li+ diffusion kinetics and lower energy barrier, but also delivers high discharge capacity with long cycling stability at high current density of 2000 mA g−1 (≈ 8C). After assembling the full cell with CNO-V 0.005 and commercial LiFePO 4 cathode material, the reversible capacity of 150.6 mAh g−1 could be achieved after 200 cycles at the current density of 1000 mA g−1, demonstrating its application potential in fast- charging lithium-ion batteries. [ABSTRACT FROM AUTHOR]

[Display omitted] • A molten salt method for large-scale synthesis of NiNb 2 O 6 submicron particles is proposed. • The NiNb 2 O 6 anode material exhibits an outstanding cycling stability and rate performance up to 20 A g−1 in a Li half-cell. • The assembled NiNb 2 O 6 ||LiFePO 4 full cell can retain 89.3% capacity after 800 cycles at 1.0 A g−1. Niobium-based oxides as lithium-ion battery anode materials have attracted much attention due to their excellent fast-charging capability. However, the solid-phase synthesis of niobates often involves harsh reaction conditions, especially high temperature over 1100 °C. Herein, a molten salt method is proposed to synthesize NiNb 2 O 6 submicron particles, with synthetic temperature of 900 °C, gram-scale production and high reaction yield of 96.6%. Remarkably, NiNb 2 O 6 at the sub-micron scale shows superior electrochemical performance compared to the micron and nano scale sizes, i.e., reversible capacity of 320.9 mAh g−1 after 500 cycles at 2.0 A g−1 (≈8.5C) and high capacity retention of 85.8% over 5000 cycles at 20 A g−1 (≈85C), mainly arising from the pseudo-capacitance electrochemical behavior and stable structure of material during repeated cycles. Moreover, the assembled NiNb 2 O 6 ||LiFePO 4 full cell can retain 89.3% capacity after 800 cycles at 1.0 A g−1. This work offers a simple and efficient method for preparing NiNb 2 O 6 submicron particles as anode material for fast -charging lithium-ion batteries. [ABSTRACT FROM AUTHOR]