Black potassium titanate nanobelts: Ultrafast and durable aqueous redox electrolyte energy storage

Black KTi8O16 nanobelts (NBs) are grown on Ti substrate by a facile one-step method for the first time. The synthetic method is ingenious and novel. The growth mechanism for the formation of KTi8O16 NBs is tentatively explained. The KTi8O16 NBs are about 5.1 nm thick, 100-300 nm wide and several micrometers long. The black KTi8O16 NBs show high energy storage performance with specific energy density of 91.7 Wh kg(-1) at a power density of 3.14 kW kg(-1), and still have a high energy density of 58.8 Wh kg(-1) at a power density of 180 kW kg(-1) in aqueous KOH solution. A novel energy storage mechanism of potassium ion de/intercalation in black KTi8O16 nanobelts, which is different from conventional supercapacitor, is revealed by a series of experiments and density functional theory (DFT) calculations. Ab initio molecular dynamics (AIMD) simulations reveals that potassium ion diffusion has little effect on the structure of KTi8O16 and it is not easy to form clusters, proving that the diffusion of potassium ions in KTi8O16 is reversible. This innovative synthetic strategy and high energy density enable various breakthroughs in this field.

Automated summary

The black KTi8O16 nanobelts show high energy storage performance with specific energy density at different power densities in aqueous KOH solution. The potassium ion diffusion in KTi8O16 is reversible, which enables various breakthroughs in the field of energy storage.