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Kinetics and Stability of Li-Ion Transfer at the LiCoO2 (104) Plane and Electrolyte Interface.

Authors :
Akira Yano
Kazuhiro Hikima
Junichi Hata
Kota Suzuki
Masaaki Hirayama
Ryoji Kanno
Source :
Journal of The Electrochemical Society; 11/1/2018, Vol. 165 Issue 14, pA3221-A3229, 9p
Publication Year :
2018

Abstract

Surface-coated/uncoated epitaxial LiCoO<subscript>2</subscript> film electrodes with (104) orientations were fabricated on SrRuO<subscript>3</subscript>(100)/Nb:SrTiO<subscript>3</subscript>(100) using pulsed laser deposition. Films with thicknesses of ∼18 nm and flat surfaces with roughnesses of less than 1 nm were model systems for clarifying the kinetics of Li-ion transfer at the electrode/electrolyte interface. The Li-ion transfer characteristics at the interface between the LiCoO<subscript>2</subscript> electrode and the electrolyte (LiPF6, ethylene carbonate + diethyl carbonate) were investigated by electrochemical impedance spectrometry. The charge-transfer resistance (R<subscript>ct</subscript>) of uncoated LiCoO<subscript>2</subscript> increased from the early cycles when charged/discharged at 3.0-4.2 V. When charged/discharged at 3.0-4.5 V, the R<subscript>ct</subscript> of the uncoated LiCoO<subscript>2</subscript> rapidly increased from the first charge. In contrast, the R<subscript>ct</subscript> of Li2ZrO<subscript>3</subscript>-coated LiCoO<subscript>2</subscript> remained almost constant during the early cycles when charged/discharged either at 3.0-4.2 or at 3.0-4.5 V. The interfacial resistances of the coated and uncoated LiCoO<subscript>2</subscript> electrodes were almost equal (~100 Ω cm<superscript>2</superscript>). The activation energy for charge transfer was lower for the coated LiCoO<subscript>2</subscript> electrode compared to that for the uncoated electrode. The current-rate capability was significantly improved by surface coating even at high-voltage charge/discharge at 3.0-4.5 V. The charge transfer process is the rate-determining step of the charge/discharge reaction. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
00134651
Volume :
165
Issue :
14
Database :
Supplemental Index
Journal :
Journal of The Electrochemical Society
Publication Type :
Academic Journal
Accession number :
133394717
Full Text :
https://doi.org/10.1149/2.0151814jes