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-Na2/3Ni1/3Mn2/3O2//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.