Charge storage mechanism of α-MnO2 in protic and aprotic ionic liquid electrolytes

JOURNAL OF POWER SOURCES

卷:460

Article

Lindberg, S.¹  Jeschke, S.¹  Jankowski, P.^5,6  Abdelhamid, M.³  Brousse, T.^2,4  Le Bideau, J.^2,4  Johansson, P.¹  Matic, A.¹ 

[1] Chalmers Univ Technol, Dept Phys, S-41296 Gothenburg, Sweden

[2] Univ Nantes, Inst Mat Jean Rouxel, CNRS, UMR 6502, F-44322 Nantes 3, France

[3] Uppsala Univ, Angstrom Lab, Dept Chem, Box 538, S-75121 Uppsala, Sweden

[4] CNRS FR 3459, Reseau Stockage Electrochim Energie, F-80039 Amiens, France

[5] Tech Univ Denmark, Dept Energy Convers & Storage, DK-2800 Lyngby, Denmark

[6] Warsaw Univ Technol, Fac Chem, PL-00664 Warsaw, Poland

关键词: MnO2;    Protic;    Ionic liquid;    Hybrid;    Supercapacitor;   

DOI  :  10.1016/j.jpowsour.2020.228111

来源: Elsevier

【 摘 要 】

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.

【 授权许可】

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