Mechanochemical Synthesis of Orthorhombic Nickel Niobate (NiNb₂O₆) as a Robust and Fast Charging Anode Material for Lithium-Ion Batteries

A generation of lithium-ion batteries that can deliver high energy and fast charging rates without compromising safety is in high demand. Despite extensive research efforts, the current Li-ion technology cannot match the requirements for large-scale electrochemical energy storage applications. Niobium-based oxides have been of particular interest lately due to their fast charging capabilities, moderately high capacity, long cycle life, and high working voltage, which prevents lithium plating and dendrite formation. However, the synthesis of niobate compounds typically involves high temperatures exceeding 1100 °C or complex chemical synthesis. In this work, a nickel niobate compound (NiNb2O6) has been synthesized through a facile and scalable method based on solid-state reaction between nickel and niobium precursors. The synthesis was assisted by mechanical techniques to enhance the reaction rate and drive the reaction to completion prior to a heat treatment at 900 °C. Findings from X-ray diffraction confirmed the formation of pure orthorhombic NiNb2O6. The as-prepared anode material was assembled in a half-cell vs Li/Li+ and delivered a maximum specific charge capacity of about 240 mAh g–1 at a rate of 0.1 A g–1 (0.42 C) with 100% Coulombic efficiency. Orthorhombic NiNb2O6 exhibited a stable cyclability (145 mAh g–1 for 0.8 A g–1 (3.4 C)), high capacity retention (90% after 1000 cycles at 3.4 C), and robust rate performance. Electrochemical tests and post-mortem analysis results confirm an intercalation-type mechanism during lithiation with high reversibility and pseudocapacitive behavior.