機械学習のアプローチにより、固体電池のために追求されている材料の全クラスへの洞察を開く Machine learning approach opens insights into an entire class of materials being pursued for solid-state batteries
2023-05-22 デューク大学(Duke)
◆研究結果は、Nature Materials誌にオンラインで発表されました。この発見と機械学習アプローチは、リチウムイオンバッテリーの代替品開発に向けた研究を加速することが期待されます。
＜関連情報＞
- https://pratt.duke.edu/about/news/argyrodite-solid-state
- https://www.nature.com/articles/s41563-023-01560-x
アーグロダイトAg8SnSe6における超イオン拡散と超低熱伝導を支える極端なフォノン非調和性 Extreme phonon anharmonicity underpins superionic diffusion and ultralow thermal conductivity in argyrodite Ag8SnSe6
Qingyong Ren,Mayanak K. Gupta,Min Jin,Jingxuan Ding,Jiangtao Wu,Zhiwei Chen,Siqi Lin,Oscar Fabelo,Jose Alberto Rodríguez-Velamazán,Maiko Kofu,Kenji Nakajima,Marcell Wolf,Fengfeng Zhu,Jianli Wang,Zhenxiang Cheng,Guohua Wang,Xin Tong,Yanzhong Pei,Olivier Delaire & Jie Ma
Nature Materials Published:18 May 2023
DOI:https://doi.org/10.1038/s41563-023-01560-x
Abstract
Ultralow thermal conductivity and fast ionic diffusion endow superionic materials with excellent performance both as thermoelectric converters and as solid-state electrolytes. Yet the correlation and interdependence between these two features remain unclear owing to a limited understanding of their complex atomic dynamics. Here we investigate ionic diffusion and lattice dynamics in argyrodite Ag8SnSe6 using synchrotron X-ray and neutron scattering techniques along with machine-learned molecular dynamics. We identify a critical interplay of the vibrational dynamics of mobile Ag and a host framework that controls the overdamping of low-energy Ag-dominated phonons into a quasi-elastic response, enabling superionicity. Concomitantly, the persistence of long-wavelength transverse acoustic phonons across the superionic transition challenges a proposed ‘liquid-like thermal conduction’ picture. Rather, a striking thermal broadening of low-energy phonons, starting even below 50 K, reveals extreme phonon anharmonicity and weak bonding as underlying features of the potential energy surface responsible for the ultralow thermal conductivity (<0.5 W m−1 K−1) and fast diffusion. Our results provide fundamental insights into the complex atomic dynamics in superionic materials for energy conversion and storage.
