Three-dimensional NiCo2O4 nanowire arrays: preparation and storage behavior for flexible lithium-ion and sodium-ion batteries with improved electrochemical performance

Abstract

The growth of three-dimensional (3D) porous NiCo₂O₄ nanowire arrays on a carbon fiber cloth (denoted as NCO@CFC) via a facile low-cost solution method combined with a subsequent annealing treatment is reported. The structure and morphology of the materials were characterized by X-ray diffraction, field-emission scanning electron microscopy, and transmission electron microscopy. Owing to the unique 3D hierarchical architecture, the NCO@CFC nanowires as a flexible electrode material for lithium-ion batteries exhibit a stable cycling performance (92.3% retention after 100 cycles), a fairly high rate capacity (507 mA h g⁻¹ at 4000 mA g⁻¹), and an enhanced lithium storage capacity. When employed as an electrode material for sodium-ion batteries, the NCO@CFC is investigated in comparison with a 3D ordered array structure and exhibits similar charge/discharge characteristics and a feasible electrochemical performance. The greatly improved electrochemical performance could be ascribed to the 3D porous nanostructure of the NCO@CFC nanowire arrays together with a novel carbon skeleton, which provides enough space to allow volume expansion during the Li⁺/Na⁺ insertion/extraction process and facilitates rapid transport of ions and electrons.