High Areal Capacity Na0.67CoO2 Bundle Array Cathode Tailored for High-Performance Sodium-Ion Batteries

Sodium-ion batteries are enjoying increasing attention as the most optimal alternative to lithium-ion batteries, due to their advantage of cost-effectiveness. As a typical cathode material for SIBs, layered NaxCoO2 was introduced, demonstrating a satisfactory ion diffusion efficiency. Nevertheless, the mass loading of cathode materials in most of the literature is between 0.5 and 2.0 mg cm(-2). In this regard, we introduce a facile sodiation and calcination method, to directly build self-supported Na0.67CoO2 bundle arrays on three-dimensional conductive Ni foam. By this fabrication pathway, the mass loading of NaxCoO2 on Ni substrate can reach values as high as similar to 10 mg cm(-2). A high areal capacity of 1.66 mAh cm(-2) can be achieved based on a current rate of 0.33 C with a voltage window of 2.0-3.8 V (vs Na/Na+). Intriguingly, this high mass loading Na(0.67)CoO2 cathode also performs with a satisfactory cyclic stability over 100 cycles at a current rate of 1.4 C, with a discharge capacity of 123.6 mAh g(-1) remaining without obvious capacity fading.