Bismuthene from Sonoelectrochemistry as Superior Anode for Potassium-Ion Batteries
Bismuth has a great potential as the anode for PIBs, due to its the layered structure with large interlayer spacing, long mean free path, high volumetric capacity (3800 mAh L-1) and environmental friendliness. Bismuthene, a 2D-layered structure, can be exfoliated from bismuth by mechanical or chemical methods. The unique structure of bismuthene is beneficial to the diffusion of potassium, penetrating of the electrolyte, and buffering the volume change along c-axis, which will boost the anode performance of the PIBs. Herein, an ultrasonication assisted electrochemical exfoliation method was proposed in this study to prepare ultra-thin few layered bismuthene nanosheets (FBNs) simply and quickly. The as-prepared FBNs were employed in KIBs as anode and deliver high stabilized capacities of 423, 356, 275 and 227 at the current densities of 2.5, 5, 10, 15 A g-1, respectively. There is no obvious decay over 2,500 cycles with a capacity of over 200 mAh g-1 at 20 A g-1, realizing the excellent rate-capability and long cycle stability in KIBs. Furthermore, the mechanism of the excellent electrochemical performances was elucidated via the in-depth characterizations and theory calculations. This work provides a new strategy to prepare scalable ultra-thin nanosheets, and offers a promising candidate to energy storage systems.