Synergism of Rare Earth Trihydrides and Graphite in Lithium Storage: Evidence of Hydrogen-Enhanced Lithiation.
basic_science · Level V
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- Also identified by DOI 10.1002/adma.201704353.
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Abstract
The lithium storage capacity of graphite can be significantly promoted by rare earth trihydrides (REH<sub>3</sub> , RE = Y, La, and Gd) through a synergetic mechanism. High reversible capacity of 720 mA h g<sup>-1</sup> after 250 cycles is achieved in YH<sub>3</sub> -graphite nanocomposite, far exceeding the total contribution from the individual components and the effect of ball milling. Comparative study on LaH<sub>3</sub> -graphite and GdH<sub>3</sub> -graphite composites suggests that the enhancement factor is 3.1-3.4 Li per active H in REH<sub>3</sub> , almost independent of the RE metal, which is evident of a hydrogen-enhanced lithium storage mechanism. Theoretical calculation suggests that the active H from REH<sub>3</sub> can enhance the Li<sup>+</sup> binding to the graphene layer by introducing negatively charged sites, leading to energetically favorable lithiation up to a composition Li<sub>5</sub> C<sub>16</sub> H instead of LiC<sub>6</sub> for conventional graphite anode.