Scalable shear-exfoliation of high-quality phosphorene nanoflakes with reliable electrochemical cycleability in nano batteries

Abstract

Atomically thin black phosphorus (called phosphorene) holds great promise as an alternative to graphene and other two-dimensional transition-metal dichalcogenides as an anode material for lithium-ion batteries (LIBs). However, bulk black phosphorus (BP) suffers from rapid capacity fading and poor rechargeable performance. This work reports for the first time the use of in situ transmission electron microscopy (TEM) to construct nanoscale phosphorene LIBs. This enables direct visualization of the mechanisms underlying capacity fading in thick multilayer phosphorene through real-time capture of delithiation-induced structural decomposition, which serves to reduce electrical conductivity thus causing irreversibility of the lithiated phases. We further demonstrate that fewlayer-thick phosphorene successfully circumvents the structural decomposition and holds superior structural restorability, even when subject to multi-cycle lithiation/delithiation processes and concomitant huge volume expansion. This finding provides breakthrough insights into thicknessdependent lithium diffusion kinetics in phosphorene. More importantly, a scalable liquid-phase shear exfoliation route has been developed to produce high-quality ultrathin phosphorene using simple means such as a high-speed shear mixer or even a household kitchen blender with the shear rate threshold of ∼1.25×10 4 s −1. The results reported here will pave the way for industrial-scale applications of rechargeable phosphorene LIBs.

Emerging Applications of Elemental 2D Materials

“…Copyright 2014, American Chemical Society. d–f) Reproduced with permission . Copyright 2016, Institute of Physics.…”

“…In group V elemental 2D analogues, phosphorene is reported to be rather dissimilar to the remaining group V materials due to its lighter atomic mass. Liquid shear exfoliation of bulk black phosphorus has proven successful in isolating multilayer black phosphorous in solvents such as n‐methyl pyrrolidone, dimethyl sulfoxide, and dimethyl formamide . Phosphorene degrades in air via dissociative chemisorption of O 2 .…”

2D Black Phosphorus for Energy Storage and Thermoelectric Applications

“…Alternatively, liquid‐phase exfoliation and shear mixing or their combination are viable options as promising large‐scale production techniques. The size selection of as‐exfoliated phosphorene can be realized by controlling different centrifuge speeds .…”

“…Isolating BP bulk into ultrathin phosphorene has been demonstrated as an answer to prolonging its cycling life. As evidenced by in situ TEM, phosphorene exhibits excellent structural integrity even after several lithiation/delithiation cycles . Nevertheless, they exhibit poor initial reversible capacity of 210 mAh g −1 accompanied by the low first‐cycle Coloumbic efficiency (11.5%), which is far from its theoretical capacity (2596 mAh g −1 ) .…”

Synthesis, characterization, and electronic properties of novel 2D materials : transition metal dichalcogenides and phosphorene.

“…For anodes, it is extremely important to have high diffusion rates [170][171][172]. Due to the topological structure of phosphorene, anisotropic diffusion in the zigzag and armchair directions is difficult to determine and current theoretical models show conflicting results [164,[170][171][172][173][174][175][176]. The anisotropy in phosphorene can be utilized to make novel batteries and optoelectronic devices.…”