Top-Down Ultrasonication-Assisted Exfoliation for Prebonded Phosphorene-Graphene Heterostructures Enabling Fast Lithiation/Delithiation.

We show a top-down synthesis approach to mass-produce phosphorene-graphene nanosheet composites with superior cycle stability and rate capability. Currently, using exfoliation to achieve two-dimensional (2D) materials is primarily limited to pure crystals. We discover that high-quality nanoscale 2D composite phosphorene-graphene sheets can be directly exfoliated from extremely low-cost bulk three-dimensional (3D) black phosphorus-graphite composites synthesized by mechanical milling while maintaining the chemical bonding and intimate electronic contact between 2D composite layers.

Blade-Type Reaction Front in Micrometer-Sized Germanium Particles during Lithiation.

To investigate the lithium transport mechanism in micrometer-sized germanium (Ge) particles, in situ focused ion beam-scanning electron microscopy was used to monitor the structural evolution of individual Ge particles during lithiation. Our results show that there are two types of reaction fronts during lithiation, representing the differences of reactions on the surface and in bulk. The cross-sectional SEM images and transmission electron microscopy characterizations show that the interface between amorphous LiGe and Ge has a wedge shape because of the higher Li transport rate on the surface of the particle.

Highly ambient-stable few-layer black phosphorene by pulsed laser exfoliation and HEMM.

Pulsed laser exfoliation was successfully applied to fabricate few-layer phosphorene from high energy mechanical milling (HEMM) synthesized black phosphorus (BP) powders and crystals. The results show that the polycrystalline phosphorene laser-exfoliated from the HEMM-synthesized BP powders is highly stable in ambient environments, providing proof-of-concept for the low-cost fabrication of highly stable few-layer phosphorene for large-scale applications.