Self-assembled NaV₆O₁₅ flower-like microstructures for high-capacity and long-life sodium-ion battery cathode

Na-ion batteries are one of the promising alternative energy storage devices for current Li-ion batteries due to the low cost and similar electrochemistry. The most critical challenge for Na-ion batteries is to develop high-capacity and long-lifespan electrode materials which are comparable to Li-ion batteries. Herein, we use a simple method to prepare nanoflake-constructed microflowers layered sodium vanadium oxide (NaV6O15) via self-assembled process. As cathode material of sodium ion battery, the prepared NaV6O15 microflowers deliver a capacity of 126 mAh g(-1) at 100 mA g(-1). Significantly, the capacity can remain 87% after 2000 cycles at a current density of 5 A g(-1). This superior performance can be attributed to the continuous electron transport pathway, improved electrical conductivity, and excellent stress relaxation, which are revealed by the electrochemical kinetics and structure evolution studies of the material in the cell.