Charge storage mechanism of α-MnO2 in protic and aprotic ionic liquid electrolytes
Journal article, 2020

In this work we have investigated the charge storage mechanism of MnO2 electrodes in ionic liquid electrolytes. We show that by using an ionic liquid with a cation that has the ability to form hydrogen bonds with the active material (MnO2) on the surface of the electrode, a clear faradaic contribution is obtained. This situation is found for ionic liquids with cations that have a low pKa, i.e. protic ionic liquids. For a protic ionic liquid, the specific capacity at low scan rate rates can be explained by a densely packed layer of cations that are in a standing geometry, with a proton directly interacting through a hydrogen bond with the surface of the active material in the electrode. In contrast, for aprotic ionic liquids there is no interaction and only a double layer contribution to the charge storage is observed. However, by adding an alkali salt to the aprotic ionic liquid, a faradaic contribution is obtained from the insertion of Li+ into the surface of the MnO2 electrode. No effect can be observed when Li+ is added to the protic IL, suggesting that a densely packed cation layer in this case prevent Li-ions from reaching the active material surface.

Hybrid

Ionic liquid

MnO2

Supercapacitor

Protic

Author

Simon Lindberg

Chalmers, Physics, Subatomic and Plasma Physics

Steffen Jeschke

Chalmers, Physics, Materials Physics

Piotr Jankowski

Technical University of Denmark (DTU)

Warsaw University of Technology

Muhammad Abdelhamid

Uppsala University

T. Brousse

Centre national de la recherche scientifique (CNRS)

Nantes University

J. Le Bideau

Centre national de la recherche scientifique (CNRS)

Nantes University

Patrik Johansson

Chalmers, Physics, Materials Physics

Aleksandar Matic

Chalmers, Physics, Materials Physics

Journal of Power Sources

0378-7753 (ISSN)

Vol. 460 228111

Subject Categories

Inorganic Chemistry

Physical Chemistry

Other Chemistry Topics

DOI

10.1016/j.jpowsour.2020.228111

More information

Latest update

8/28/2020