Liquid exfoliation of interlayer spacing-tunable 2D vanadium oxide nanosheets: High capacity and rate handling Li-ion battery cathodes

5 years ago

Liquid exfoliation of interlayer spacing-tunable 2D vanadium oxide nanosheets: High capacity and rate handling Li-ion battery cathodes

With a layered crystal structure and good Li⁺ storage performance, vanadium pentoxide (V2O5) is potentially a high-energy and cost-effective cathode material for Li-ion batteries (LiBs). Networks of two-dimensional V2O5 nanosheets (2D V2O5 NS), with large interlayer distance, are ideal for enhancing the Li⁺ diffusion kinetics and thus for building high power LiBs. However, the lack of a simple, scalable and environmentally friendly route to nanosheet production still hinders the development of V2O5 applications. Here we demonstrate, liquid-phase exfoliation (LPE) of commercial V2O5 powder in environmental friendly solvents (water and ethanol) to achieve large quantities of 2D V2O5 NS dispersions. The V2O5 NS are of high-quality whose interlayer spacing can be well manipulated, ranging from 4.4Å to 11.5Å in ethanol and water (forming NS xerogel), respectively. Ultrasonic aerosol printing of V2O5 NS xerogel/single-wall carbon nanotube (SWCNT) blended dispersions resulted in large-area, flexible, and binder-free hybrid electrodes, which showcase a high discharge capacity of 370mAhg⁻¹ at 0.05C, high energy density (555Whkg⁻¹) and power density (2175Wkg⁻¹), etc. These properties can be attributed to the synergistic effects between the expanded hydrated NS and the conductive SWCNT matrix; the latter improves the reversible phase transition reactions of the NS, enhances the ion diffusion kinetics, maintains the electrode's mechanical integrity and provides electron transport pathways. The Li⁺ storage mechanism was investigated, suggesting the capacity was majorly contributed by the non-diffusion controlled process (pseudocapacitive). We believe the LPE/aerosol printing approach is environmentally green, general and scalable, and could be extended to other layered transitional metal oxides or dichalcogenides for fabrication of corresponding flexible, binder-free, conductive composites for energy storage systems.

Publisher URL: www.sciencedirect.com/science

DOI: S2211285517303981