"Zero-Strain" NiNb₂O₆ Fibers for All-Climate Lithium Storage

Niobates are promising all-climate Li⁺-storage anode material due to their fast charge transport, large specific capacities, and resistance to electrolyte reaction. However, their moderate unit-cell-volume expansion (generally 5%-10%) during Li⁺ storage causes unsatisfactory long-term cyclability. Here, "zero-strain" NiNb₂O₆ fibers are explored as a new anode material with comprehensively good electrochemical properties. During Li⁺ storage, the expansion of electrochemical inactive NiO₆ octahedra almost fully offsets the shrinkage of active NbO₆ octahedra through reversible O movement. Such superior volume-accommodation capability of the NiO₆ layers guarantees the "zero-strain" behavior of NiNb₂O₆ in a broad temperature range (0.53%//0.51%//0.74% at 25// - 10//60 °C), leading to the excellent cyclability of the NiNb₂O₆ fibers (92.8%//99.2% // 91.1% capacity retention after 1000//2000//1000 cycles at 10C and 25// - 10//60 °C). This NiNb₂O₆ material further exhibits a large reversible capacity (300//184//318 mAh g^-1 at 0.1C and 25// - 10//60 °C) and outstanding rate performance (10 to 0.5C capacity percentage of 64.3%//50.0%//65.4% at 25// - 10//60 °C). Therefore, the NiNb₂O₆ fibers are especially suitable for large-capacity, fast-charging, long-life, and all-climate lithium-ion batteries.