Large-scale highly ordered Sb nanorod array anodes with high capacity and rate capability for sodium-ion batteries

Abstract

Na-ion batteries are a potential substitute to Li-ion batteries for energy storage devices. However, their poor electrochemical performance, especially capacity and rate capability, is the major bottleneck to future development. Here we propose a performance-oriented electrode structure, which is 1D nanostructure arrays with large-scale high ordering, good vertical alignment, and large interval spacing. Benefiting from these structural merits, a great enhancement in electrochemical performance could be achieved. Taking Sb as an example, we firstly report large-scale highly ordered Sb nanorod arrays with uniform large interval spacing (190 nm). In return for this electrode design, high ion accessibility, fast electron transport, and strong electrode integrity are presented here. Used as additive- and binder-free anodes for Na-ion batteries, Sb nanorod arrays showed a high capacity of 620 mA h g⁻¹ at the 100th cycle with a retention of 84% up to 250 cycles at 0.2 A g⁻¹, and a superior rate capability for delivering reversible capacities of 579.7 and 557.7 mA h g⁻¹ at 10 and 20 A g⁻¹, respectively. A full cell coupled by a P2-Na_2/3Ni_1/3Mn_2/3O₂ cathode and a Sb nanorod array anode was also constructed, which showed good cycle performance up to 250 cycles, high rate capability up to 20 A g⁻¹, and large energy density up to 130 Wh kg⁻¹. These excellent electrochemical performances shall pave the way for developing more applications of Sb nanorod arrays in energy storage devices.