Kim, Jae-Bum Kim, Chihun Chung, Wootack Yoon, Da Hye Lyu, Lulu Jang, Jeongmin Shin, Hee Jun Nam, Kyung-Wan Lee, Byungju Kang, Yong-Mook 2025-09-23T02:30:11Z 2025-09-23T02:30:11Z 2025-09-16 2025-09 0002-7863 https://pubs.kist.re.kr/handle/201004/153218 The thermodynamic equilibrium assumption often invoked in modeling ion migration in solid-state materials remains insufficient to capture the true migration behavior of Li ions, particularly in less-crystalline superionic conductors that exhibit anomalously high Li ion conductivity. Such materials challenge classical frameworks and necessitate a lattice dynamics-based perspective that explicitly accounts for nonequilibrium phonon interactions and transient structural responses. Here, we uncover a phonon-governed Li ion migration mechanism in garnet-structured superionic conductors by comparing Ta-doped Li6.6La3Zr1.6Ta0.4O12 (LLZTO4) to its undoped analogue, Li6.24La3Zr2Al0.24O11.98 (LLZO). Through a synergistic combination of terahertz time-domain spectroscopy (THz-TDS), 7Li magic-angle spinning nuclear magnetic resonance (MAS-NMR), and Raman spectroscopy, we show that Ta doping softens the host lattice and enhances anharmonic phonons, enabling collective, thereby multi-ion migration beyond the limit of single-ion hopping models. This lattice softening induces a dynamically disordered energy landscape that lowers activation barriers and yields Li ion conductivities approaching those of liquid electrolytes. Our findings demonstrate that anharmonic lattice vibrations can serve as the driving force for ultrafast Li ion migration in solid electrolytes. This paradigm shift establishes a fundamental link between lattice thermodynamics and superionic conduction, providing a conceptual and experimental framework for the design of highly conductive solid-state electrolytes. English American Chemical Society Anharmonic Phonon Scattering Triggering Multi-ion Migration in Oxide-Based Superionic Conductors Article 10.1021/jacs.5c09777 1 Journal of the American Chemical Society, v.147, no.37, pp.33743 - 33753 Journal of the American Chemical Society 147 37 33743 33753 N scie scopus 001565528700001 Chemistry, Multidisciplinary Chemistry Article; Early Access ION DYNAMICS LITHIUM-ION LI-7 NMR RANGE