Laser-Assisted Ultrafast Exfoliation of Black Phosphorus in Liquid with Tunable Thickness for Li-Ion Batteries

Few-layer black phosphorus (BP) is an emerging 2D material suitable for energy applications. However, its controllable preparation remains challenging. Herein, a highly efficient route is presented for the scalable production of few-layered BP nanosheets using a pulsed laser in low-boiling point solvents. Changing the laser irradiation time, energy, and solvent type leads to precise control over the layer number and lateral size of the nanosheets with a narrow distribution. The process is understood by a plasma quenching mechanism and interlayer interaction weakened by the in situ generated vapor bubbles. The excellent control of the BP nanosheets enables morphological effects on Li-ion battery performance to be studied. Low layer numbers benefit both charge transfer and Li⁺ ion diffusion, while a high aspect ratio can not only improve the charge transfer but also increase the Li⁺ ion diffusion path. This study delivers insights on the tailored fabrication of thin 2D materials using lasers for morphology-dependent electrochemical energy conversion and storage.