The electric double layer effect and its strong suppression at Li+ solid electrolyte/hydrogenated diamond interfaces

Shigenori Ueda,Masataka Imura,Kazuya Terabe,Takashi Tsuchiya,Makoto Takayanagi,Kazutaka Mitsuishi,Tohru Higuchi,Yasuo Koide

doi:10.1038/s42004-021-00554-7

Abstract

The electric double layer (EDL) effect at solid electrolyte/electrode interfaces has been a key topic in many energy and nanoelectronics applications (e.g., all-solid-state Li+ batteries and memristors). However, its characterization remains difficult in comparison with liquid electrolytes. Herein, we use a novel method to show that the EDL effect, and its suppression at solid electrolyte/electronic material interfaces, can be characterized on the basis of the electric conduction characteristics of hydrogenated diamond(H-diamond)-based EDL transistors (EDLTs). Whereas H-diamond-based EDLT with a Li-Si-Zr-O Li+ solid electrolyte showed EDL-induced hole density modulation over a range of up to three orders of magnitude, EDLT with a Li-La-Ti-O (LLTO) Li+ solid electrolyte showed negligible enhancement, which indicates strong suppression of the EDL effect. Such suppression is attributed to charge neutralization in the LLTO, which is due to variation in the valence state of the Ti ions present. The method described is useful for quantitatively evaluating the EDL effect in various solid electrolytes.

Highlights

The electric double layer (EDL) effect at solid electrolyte/electrode interfaces has been a key topic in many energy and nanoelectronics applications
The high resolution transmission electron microscope (HR-TEM) image of the LSZO/ H-diamond interface shown in Fig. 1d confirms well crystalized H-diamond (100) and completely amorphized LSZO
EDL-induced electronic carrier accumulation and its suppression at Li+ conducting solid electrolyte thin films/electronic material interfaces were investigated on the basis of the electric conduction characteristics of H-diamond-based EDL transistors (EDLTs)

Summary

Introduction

The electric double layer (EDL) effect at solid electrolyte/electrode interfaces has been a key topic in many energy and nanoelectronics applications (e.g., all-solid-state Li+ batteries and memristors). While the importance of the clarification (e.g., extent of ion concentration variation, existence of induced charge on electrode surface, thickness of the EDL) is widely understood, direct observation of the EDL in the vicinity of solid/solid electrolytes interface has been difficult even by state-of-art transmission electron microscope (TEM) technologies. It is because, analogous to the EDL for liquid electrolytes, the EDL for solid electrolytes is expected to be extremely thin (e.g., in nm order) and extent of ion concentration variation is small. The present technique is useful for revealing EDL behavior in the vicinity of solid/solid electrolyte interfaces and for clarifying the effect of the interface characteristics on the total performance of solid state ionic devices, including ASS-LIBs

Methods

Results

Conclusion