TY  - JOUR
AU  - Melke, Julia
AU  - Martin, Julian
AU  - Bruns, Michael
AU  - Hügenell, Philipp
AU  - Schökel, Alexander
AU  - Montoya Isaza, Sebastian
AU  - Fink, Felix
AU  - Elsässer, Patrick
AU  - Fischer, Anna
TI  - Investigating the Effect of Microstructure and Surface Functionalization of Mesoporous N-Doped Carbons on V<sup>4+</sup>/V<sup>5+</sup> Kinetics
JO  - ACS applied energy materials
VL  - 3
IS  - 12
SN  - 2574-0962
CY  - Washington, DC
PB  - ACS Publications
M1  - PUBDB-2021-01435
SP  - 11627 - 11640
PY  - 2020
N1  - Waiting for fulltext
AB  - State-of-the-art electrode materials for all-vanadium redox flow batteries are based on carbon. Unfortunately, the impact of the carbon structure, i.e., microstructure/crystallinity, surface functional groups, and porosity/morphology/surface area, on the electrochemical performance is still unclear. This is due to the fact that usually several structural characteristics are varied due to synthesis or post-treatment procedures at the same time. Therefore, this paper shows systematically how microstructure, porosity, and surface functional groups vary with carbonization and graphitization temperature (ranging from 700 to 1500 °C) for a mesoporous N-doped carbon (MPNC). Changes in the material’s structure (e.g., morphology, porosity, crystal structure, surface functionalization), determined by scanning and transmission electron microscopy, X-ray diffraction (pair distribution function analysis), X-ray photoelectron spectroscopy, near-edge X-ray absorption fine structure spectroscopy, and N2 sorption measurements, are correlated to changes in wettability, conductivity, and electrochemical kinetics, investigated by H<sub>2</sub>O sorption measurements, cyclic voltammetry, and electrochemical impedance spectroscopy in the VOV<sup>2+</sup> electrolyte, respectively. We found that the kinetics of the VO<sup>2+</sup>/VO<sub>2</sub><sup>+</sup> reaction increases with an increase in sp<sup>2</sup>-C content and therefore an increase in crystallite size and conductivity of the mesoporous N-doped carbon. Nevertheless, the largest current for the VO<sup>2+</sup>/VO<sub>2</sub><sup>+</sup> reaction for the same amount of carbon during cyclic voltammetry is observed for the MPNC carbonized at an intermediate temperature, 1000 °C, as a result of its larger wettability and thus available surface area compared to the MPNC carbonized at 1500 °C.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000618839200015
DO  - DOI:10.1021/acsaem.0c01489
UR  - https://bib-pubdb1.desy.de/record/456284
ER  -