Highly Ordered Three-Dimensional Ni-TiO2 Nanoarrays as Sodium Ion Battery Anodes

Sodium ion batteries (SIBs) represent an effective energy storage technology with potentially lower material costs than lithium ion batteries. Here, we show that the electrochemical performance of SIBs, especially rate capability, is intimately connected to the electrode design at the nanoscale by taking anatase TiO2 as an example. Highly ordered three-dimensional (3D) Ni-TiO2 core-shell nanoarrays were fabricated using nanoimprited AAO templating technique and directly used as anode. The nanoarrays delivered a reversible capacity of similar to 200 mAh g(-1) after 100 cycles at the current density of 50 mAh g(-1) and were able to retain a capacity of similar to 95 mAh g(-1) at the current density as high as 5 A g(-1) and fully recover low rate capacity. High ion accessibility, fast electron transport, and excellent electrode integrity were shown as great merits to obtain the presented electrochemical performance. Our work demonstrates the possibility of highly ordered 3D heterostructured nanoarrays as a promising electrode design for Na energy storage to alleviate the reliance on the materials intrinsic nature and provides a versatile and cost-effective technique for the fabrication of such perfectly ordered nanostructures.