Charge storage mechanism of α-MnO2 in protic and aprotic ionic liquid electrolytes
Artikel i vetenskaplig tidskrift, 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

MnO2

Ionic liquid

Protic

Supercapacitor

Författare

Simon Lindberg

Chalmers, Fysik, Subatomär fysik och plasmafysik

Steffen Jeschke

Chalmers, Fysik, Kondenserade materiens fysik

Piotr Jankowski

Politechnika Warszawska

Danmarks Tekniske Universitet (DTU)

Muhammad Abdelhamid

Uppsala universitet

T. Brousse

Centre national de la recherche scientifique (CNRS)

Université de Nantes

J. Le Bideau

Université de Nantes

Centre national de la recherche scientifique (CNRS)

Patrik Johansson

Chalmers, Fysik, Kondenserade materiens fysik

Aleksandar Matic

Chalmers, Fysik, Kondenserade materiens fysik

Journal of Power Sources

0378-7753 (ISSN)

Vol. 460 228111

Ämneskategorier

Oorganisk kemi

Fysikalisk kemi

Annan kemi

DOI

10.1016/j.jpowsour.2020.228111

Mer information

Senast uppdaterat

2020-05-15