Degradation Dynamics for Electrochromic WO3Films under Extended Charge Insertion and Extraction: Unveiling Physicochemical Mechanisms.
Degradation of electrochromic thin films under extended charge insertion and extraction is a technically important phenomenon for which no in-depth understanding is currently on hand. Here, we report on an explorative study of sputter-deposited WO3films in a Li-ion-conducting electrolyte by use of cyclic voltammetry, in situ optical transmittance, and impedance spectroscopy. A cycling-dependent decrease of the charge capacity could be accurately modeled by a power-law function, and impedance spectroscopy gave evidence for anomalous diffusion as well as a higher charge-transfer resistance during deintercalation than during intercalation. Thus, a consistent conceptual picture emerged for the degradation dynamics; it includes the growth of an interfacial barrier layer and also embraces anomalous diffusion coupled with dispersive power-law chemical kinetics.
Department of Engineering Sciences, The Ångström Laboratory, Uppsala University , SE-75121 Uppsala, Sweden.|Materials Processing Center, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States.
Rui-Tao
http://orcid.org/0000-0002-3153-1539
RT
Wen
Department of Engineering Sciences, The Ångström Laboratory, Uppsala University , SE-75121 Uppsala, Sweden.
Sara
S
Malmgren
Department of Engineering Sciences, The Ångström Laboratory, Uppsala University , SE-75121 Uppsala, Sweden.
Claes G
CG
Granqvist
Department of Engineering Sciences, The Ångström Laboratory, Uppsala University , SE-75121 Uppsala, Sweden.
Gunnar A
GA
Niklasson
WO3; detrapping; electrochromism; physicochemical mechanisms; thin films