Electrochemical measurements of the electronic density of states

Abstract

PostprintThis is the accepted version of a paper published in Physica Scripta. This paper has been peer-reviewed but does not include the final publisher proof-corrections or journal pagination.Citation for the original published paper (version of record):Niklasson, G A. (2015) Electrochemical measurements of the electronic density of states.Physica Scripta, 90 (9) AbstractWe present a simple electrochemical method, called intercalation spectroscopy, to study the electronic density-of-states of intercalation materials. It is based on the realization that electrochemical quasi-steady state potential curves of a number of materials exhibit fine structure in good agreement with features in the density of electronic states. Different electrochemical techniques are able to give this information, but chronopotentiometry appears to have advantages from an experimental viewpoint. In this paper we compare the so called "electrochemical density-of-states" of amorphous and crystalline structures. We also address the limitations of intercalation spectroscopy due to kinetic effects, i.e. very slow relaxations of the charge carriers. Intercalation spectroscopy is in principle very sensitive, although in limited energy ranges, and is able to give information complementary to electron and X-ray spectroscopies for a number of materials.

Sustainable Rejuvenation of Electrochromic WO3 Films

“…18,19 As apparent from the CV data in Figure 2A and Figure S3, Li + ion insertion and extraction initially take place in a wide potential range, specifically at 2.0-3.5 V, indicating a broad distribution of electronic energies in the host material. However, the high-potential limit for ion insertion and extraction shifts monotonically towards lower potentials upon extended cycling and, for example, Li + ion intercalation only occurs in the 2.0-3.0 V range after 500 CV cycles.…”

“…The details of the trapping and detrapping/rejuvenation processes are still not accurately known, but a number of interesting observations can be made from the data presented here. Ion intercalation in EC materials takes place together with insertion of charge-balancing electrons from the outer electrical circuit, and the distribution of ion insertion potentials is known to be governed by the density of electronic states in the material. , As apparent from the CV data in Figure A and Figure S3, Li + ion insertion and extraction initially take place in a wide potential range, specifically at 2.0–3.5 V, indicating a broad distribution of electronic energies in the host material. However, the high-potential limit for ion insertion and extraction shifts monotonically toward lower potentials upon extended cycling and, for example, Li + ion intercalation only occurs in the 2.0–3.0 V range after 500 CV cycles.…”

Impedance Spectroscopy of Electrochromic Hydrous Tungsten Oxide Films

“…It has the appearance of an effective density-of-states and shows how many ions per host atom, or alternatively charge-compensating electrons, that are inserted in the film at a certain energy. This parameter gives a measure of the potential-dependent charge capacity and can give qualitative information about the electronic density of states in the film [39][40][41].…”