Molten salt synthesis of submicron NiNb2O6 anode material with ultra-high rate performance for lithium-ion batteries

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 NiNb2O6 submicron particles, with synthetic temperature of 900 °C, gram-scale production and high reaction yield of 96.6%. Remarkably, NiNb2O6 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 NiNb2O6||LiFePO4 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 NiNb2O6 submicron particles as anode material for fast -charging lithium-ion batteries.