skip to main content

Search for: All records

Award ID contains: 1749742

Note: When clicking on a Digital Object Identifier (DOI) number, you will be taken to an external site maintained by the publisher. Some full text articles may not yet be available without a charge during the embargo (administrative interval).
What is a DOI Number?

Some links on this page may take you to non-federal websites. Their policies may differ from this site.

  1. Abstract

    The development of next‐generation electrodes for metal‐ion batteries requires an understanding of intercalation dynamics in nanomaterials. Herein, it is shown that microscale mechanical strain significantly affects the formation of ordered lithium phases in graphene. In situ Raman spectroscopy of graphene microflakes mechanically constrained at the edge during lithium intercalation reveals a thickness‐dependent increase of up to 1.26 V in the electrochemical potential that induces lithium staging. While the induced mechanical strain energy increases with graphene thickness to the fourth power, its magnitude is small compared to the observed increase in electrochemical energy. It is hypothesized that the mechanical strain energy increases a nucleation barrier for lithium staging, greatly delaying the formation of ordered lithium phases. These results indicate that electrode assembly may critically impact lithium staging dynamics. The present work demonstrates strain engineering in two dimensional (2D) nanomaterials as an effective approach to manipulate phase transitions and chemical reactivity.

    more » « less
  2. Abstract

    The energetic chemical reaction between Zn(NO3)2and Li is used to create a solid‐state interface between Li metal and Li6.4La3Zr1.4Ta0.6O12(LLZTO) electrolyte. This interlayer, composed of Zn, ZnLixalloy, Li3N, Li2O, and other species, possesses strong affinities with both Li metal and LLZTO and affords highly efficient conductive pathways for Li+transport through the interface. The unique structure and properties of the interlayer lead to Li metal anodes with longer cycle life, higher efficiency, and better safety compared to the current best Li metal electrodes operating in liquid electrolytes while retaining comparable capacity, rate, and overpotential. All‐solid‐state Li||Li cells can operate at very demanding current–capacity conditions of 4 mA cm−2–8 mAh cm−2. Thousands of hours of continuous cycling are achieved at Coulombic efficiency >99.5 % without dendrite formation or side reactions with the electrolyte.

    more » « less
  3. Abstract The phase transitions of two-dimensional (2D) materials are key to the operation of many devices with applications including energy storage and low power electronics. Nanoscale confinement in the form of reduced thickness can modulate the phase transitions of 2D materials both in their thermodynamics and kinetics. Here, using in situ Raman spectroscopy we demonstrate that reducing the thickness of MoS 2 below five layers slows the kinetics of the phase transition from 2H- to 1T′-MoS 2 induced by the electrochemical intercalation of lithium. We observe that the growth rate of 1T′ domains is suppressed in thin MoS 2 supported by SiO 2 , and attribute this growth suppression to increased interfacial effects as the thickness is reduced below 5 nm. The suppressed kinetics can be reversed by placing MoS 2 on a 2D hexagonal boron nitride ( h BN) support, which readily facilitates the release of strain induced by the phase transition. Additionally, we show that the irreversible conversion of intercalated 1T′-MoS 2 into Li 2 S and Mo is also thickness-dependent and the stability of 1T′-MoS 2 is significantly increased below five layers, requiring a much higher applied electrochemical potential to break down 1T′-MoS 2 into Li 2 S and Mo nanoclusters. 
    more » « less
    more » « less
  5. null (Ed.)