Structural Basis of Ultralow Capacitances at Metal-Nonaqueous Solution Interfaces.
Juan Chen, Zengming Zhang, Xiaoting Yin, Chenkun Li, Fengjiao Yu, Yuping Wu, Jiawei Yan, Jun Huang, Yuhui Chen
Author Information
Juan Chen: State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemical Engineering, Nanjing Tech University, Nanjing 211816, China.
Zengming Zhang: Institute of Energy Technologies, IET-3: Theory and Computation of Energy Materials, Forschungszentrum J��lich GmbH, J��lich 52425, Germany.
Xiaoting Yin: State Key Laboratory of Physical Chemistry of Solid Surfaces and College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China.
Chenkun Li: Institute of Energy Technologies, IET-3: Theory and Computation of Energy Materials, Forschungszentrum J��lich GmbH, J��lich 52425, Germany. ORCID
Fengjiao Yu: State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemical Engineering, Nanjing Tech University, Nanjing 211816, China. ORCID
Yuping Wu: State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemical Engineering, Nanjing Tech University, Nanjing 211816, China. ORCID
Jiawei Yan: State Key Laboratory of Physical Chemistry of Solid Surfaces and College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China. ORCID
Jun Huang: Institute of Energy Technologies, IET-3: Theory and Computation of Energy Materials, Forschungszentrum J��lich GmbH, J��lich 52425, Germany. ORCID
Yuhui Chen: State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemical Engineering, Nanjing Tech University, Nanjing 211816, China. ORCID
Metal-nonaqueous solution interfaces, a key to many electrochemical technologies, including lithium metal batteries, are much less understood than their aqueous counterparts. Herein, on several metal-nonaqueous solution interfaces, we observe capacitances that are 2 orders of magnitude lower than the usual double-layer capacitance. Combining electrochemical impedance spectroscopy, atomic force microscopy, and physical modeling, we ascribe the ultralow capacitance to an interfacial layer of 10-100 nm above the metal surface. This nanometric layer has a Young's modulus around 2 MPa, which is much softer than typical solid-electrolyte interphase films. In addition, its AC ionic conductivity is 4-to-5 orders of magnitude lower than that of the bulk electrolyte. The temperature dependencies of the AC ionic conductivity and thickness suggest that the soft layer is formed from metal-mediated, dipole-dipole interactions of the nonaqueous solvent molecules. The observed soft layer opens new avenues of modulating battery performance via rational design of ion transport, (de)solvation, and charge transfer in this interfacial region.
