  Lithium phosphorus oxynitride (LiPON) is an amorphous solid-state lithium ion
conductor displaying exemplary cyclability against lithium metal anodes. There
is no definitive explanation for this stability due to the limited
understanding of the structure of LiPON. We provide a structural model of
RF-sputtered LiPON via experimental and computational spectroscopic methods.
Information about the short-range structure results from 1D and 2D solid-state
nuclear magnetic resonance experiments investigating chemical shift anisotropy
and dipolar interactions. These results are compared with first principles
chemical shielding calculations of Li-P-O/N crystals and ab initio molecular
dynamics-generated amorphous LiPON models to unequivocally identify the glassy
structure as primarily isolated phosphate monomers with N incorporated in both
apical and as bridging sites in phosphate dimers. Structural results suggest
LiPON's stability is a result of its glassy character. Free-standing LiPON
films are produced that exhibit a high degree of flexibility highlighting the
unique mechanical properties of glassy materials.
