Hierarchical Sb-Ni nanoarrays as robust binder-free anodes for high-performance sodium-ion half and full cells

A novel hierarchical electrode material for Na-ion batteries composed of Sb nanoplates on Ni nanorod arrays is developed to tackle the issues of the rapid capacity fading and poor rate capability of Sb-based materials. The three- dimensional (3D) Sb-Ni nanoarrays as anodes exhibit the synergistic effects of the two-dimensional nanoplates and the open and conductive array structure as well as strong structural integrity. Further, their capacitive behavior is confirmed through a kinetics analysis, which shows that their excellent Na-storage performance is attributable to their unique nanostructure. When used as binder-free sodium-ion battery (SIB) anodes, the nanoarrays exhibit a high capacity retention rate (more than 80% over 200 cycles) at a current density of 0.5 A·g^–1 and excellent rate capacity (up to 20 A·g^–1), with their capacity being 580 mAh·g^–1. Moreover, a P2-Na_2/3Ni_1/3Mn_2/3O₂//3D Sb-Ni nanoarrays full cell delivers a highly reversible capacity of 579.8 mAh·g^–1 over 200 cycles and an energy density as high as 100 Wh·kg^–1. This design strategy for ensuring fast and stable Na storage may work with other electrode materials as well.