TY  - JOUR
AU  - Ding, Jingxuan
AU  - Gupta, Mayanak K.
AU  - Rosenbach, Carolin
AU  - Lin, Hung-Min
AU  - Osti, Naresh C.
AU  - Abernathy, Douglas L.
AU  - Zeier, Wolfgang
AU  - Delaire, Olivier
TI  - Liquid-like dynamics in a solid-state lithium electrolyte
JO  - Nature physics
VL  - 21
SN  - 1745-2473
CY  - Basingstoke
PB  - Nature Publishing Group
M1  - FZJ-2025-00733
SP  - 118–125
PY  - 2025
AB  - Superionic materials represent a regime intermediate between the crystalline and liquid states of matter. Despite the considerable interest in potential applications for solid-state batteries or thermoelectric devices, it remains unclear whether the fast ionic diffusion observed in superionic materials reflects liquid-like dynamics or whether the hops of mobile ions are inherently coupled to more conventional lattice phonons. Here we reveal a crossover from crystalline vibrations to relaxational dynamics of ionic diffusion in the superionic compound $Li_6PS_5Cl$, a candidate solid-state electrolyte. By combining inelastic and quasi-elastic neutron-scattering measurements with first-principles-based machine-learned molecular dynamics simulations, we found that the vibrational density of states in the superionic state strongly deviates from the quadratic behaviour expected from the Debye law of lattice dynamics. The superionic dynamics emerges from overdamped phonon quasiparticles to give rise to a linear density of states characteristic of instantaneous normal modes in the liquid state. Further, we showed that the coupling of lattice phonons with a dynamic breathing of the $Li^+$ diffusion bottleneck enables an order-of-magnitude increase in diffusivity. Thus, our results shed insights into superionics for future energy storage and conversion technologies.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:001390246300001
DO  - DOI:10.1038/s41567-024-02707-6
UR  - https://juser.fz-juelich.de/record/1037544
ER  -