セミナー・シンポジウム Seminars & Symposium

【4/9】「AIMR Special Seminar」のご案内

AIMR主任研究者Chris J. Pickard教授が所属するケンブリッジ大学材料科学・冶金学科、材料理論グループの博士研究員であるZiheng Lu氏にab initio random structure searching (AIRSS) 法を用いたリチウムイオン電池正極材料の理論的探索に関する研究成果を講演いただきます。AIMR Friday Tea Timeを利用したセミナーとなりますが、更に深く話を聞きたい参加者はTea Time終了後も議論を継続可能です。

講演者

Ziheng Lu 博士
（ケンブリッジ大学材料科学・冶金学科　材料理論グループ）

講演題目

Ab initio random structure searching for battery cathodes and more

日時

2021年4月9日（金）16:00～16:40
Friday Tea Timeとしては16:40頃に一旦散会としますが、17:30頃までオンライン接続を継続して講演者と議論することが可能です。

会場

オンライン （Zoom）

講演要旨

Cathodes are critical components of rechargeable batteries. Conventionally, the search for cathode materials relies on experimental trial-and-error and a traversing of existing computational/experimental databases. While these methods have led to the discovery of several commercially-viable cathode materials, the chemical space explored so far is limited and many phases will have been overlooked, in particular those that are metastable. We describe a computational framework for battery cathode exploration, based on ab initio random structure searching (AIRSS), an approach that samples local minima on the potential energy surface to identify new crystal structures. We show that, by delimiting the search space using a number of constraints, including chemically aware minimum interatomic separations, cell volumes, and space group symmetries, AIRSS can efficiently predict both thermodynamically stable and metastable cathode materials.

Specifically, we investigate LiCoO₂, LiFePO₄, and Li_xCu_yF_z to demonstrate the efficiency of the method by rediscovering the known crystal structures of these cathode materials. The effect of parameters, such as minimum separations and symmetries, on the efficiency of the sampling is discussed in detail. The adaptation of the minimum interatomic distances, on a species-pair basis, from low-energy optimized structures to efficiently capture the local coordination environment of atoms, is explored. A family of novel cathode materials based, on the transition-metal oxalates, is proposed. They are predicted to demonstrate superb energy density, oxygen-redox stability, and lithium diffusion properties.

The application of AIRSS and density functional theory-based thermodynamics to solid electrolytes and interfaces will also be briefly talked about.

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