Atomic-scale study clarifying the role of space-charge layers in a Li-ion-conducting solid electrolyte

Zhenqi Gu; Jiale Ma; Feng Zhu; Ting Liu; Kai Wang; Ce-Wen Nan; Zhenyu Li; Cheng Ma

doi:10.1038/s41467-023-37313-2

Atomic-scale study clarifying the role of space-charge layers in a Li-ion-conducting solid electrolyte

Nat Commun. 2023 Mar 24;14(1):1632. doi: 10.1038/s41467-023-37313-2.

Authors

Zhenqi Gu^#^{1

2}, Jiale Ma^#³, Feng Zhu^#^{1

2}, Ting Liu^{4

5}, Kai Wang^{1

2}, Ce-Wen Nan⁴, Zhenyu Li⁶, Cheng Ma^{7

8

9}

Affiliations

¹ Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui, 230026, China.
² CAS Key Laboratory of Materials for Energy Conversion, Department of Materials Science and Engineering, University of Science and Technology of China, Hefei, Anhui, 230026, China.
³ Key Laboratory of Precision and Intelligent Chemistry, University of Science and Technology of China, Hefei, Anhui, 230026, China.
⁴ School of Materials Science and Engineering, State Key Laboratory of New Ceramics and Fine Processing, Tsinghua University, Beijing, 100084, China.
⁵ Foshan (Southern China) Institute for New Materials, Foshan, Guangdong, 528200, China.
⁶ Key Laboratory of Precision and Intelligent Chemistry, University of Science and Technology of China, Hefei, Anhui, 230026, China. zyli@ustc.edu.cn.
⁷ Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui, 230026, China. mach16@ustc.edu.cn.
⁸ CAS Key Laboratory of Materials for Energy Conversion, Department of Materials Science and Engineering, University of Science and Technology of China, Hefei, Anhui, 230026, China. mach16@ustc.edu.cn.
⁹ National Synchrotron Radiation Laboratory, Hefei, Anhui, 230026, China. mach16@ustc.edu.cn.

^# Contributed equally.

Abstract

Space-charge layers are frequently believed responsible for the large resistance of different interfaces in all-solid-state Li batteries. However, such propositions are based on the presumed existence of a Li-deficient space-charge layer with insufficient charge carriers, instead of a comprehensive investigation on the atomic configuration and its ion transport behavior. Consequently, the real influence of space-charge layers remains elusive. Here, we clarify the role of space-charge layers in Li_0.33La_0.56TiO₃, a prototype solid electrolyte with large grain-boundary resistance, through a combined experimental and computational study at the atomic scale. In contrast to previous speculations, we do not observe the Li-deficient space-charge layers commonly believed to result in large resistance. Instead, the actual space-charge layers are Li-excess; accommodating the additional Li⁺ at the 3c interstitials, such space-charge layers allow for rather efficient ion transport. With the space-charge layers excluded from the potential bottlenecks, we identify the Li-depleted grain-boundary cores as the major cause for the large grain-boundary resistance in Li_0.33La_0.56TiO₃.

Abstract

Grants and funding