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ORR in Non-Aqueous Solvent for Li-Air Batteries: The Influence of Doped MnO 2 -Nanoelectrocatalyst.
- Source :
-
Nanomaterials (Basel, Switzerland) [Nanomaterials (Basel)] 2020 Sep 01; Vol. 10 (9). Date of Electronic Publication: 2020 Sep 01. - Publication Year :
- 2020
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Abstract
- One of the major drawbacks in Lithium-air batteries is the sluggish kinetics of the oxygen reduction reaction (ORR). In this context, better performances can be achieved by adopting a suitable electrocatalyst, such as MnO <subscript>2</subscript> . Herein, we tried to design nano-MnO <subscript>2</subscript> tuning the final ORR electroactivity by tailoring the doping agent (Co or Fe) and its content (2% or 5% molar ratios). Staircase-linear sweep voltammetries (S-LSV) were performed to investigate the nanopowders electrocatalytic behavior in organic solvent (propylene carbonate, PC and 0.15 M LiNO <subscript>3</subscript> as electrolyte). Two percent Co-doped MnO <subscript>2</subscript> revealed to be the best-performing sample in terms of ORR onset shift (of ~130 mV with respect to bare glassy carbon electrode), due to its great lattice defectivity and presence of the highly electroactive γ polymorph (by X-ray diffraction analyses, XRPD and infrared spectroscopy, FTIR). 5% Co together with 2% Fe could also be promising, since they exhibited fewer diffusive limitations, mainly due to their peculiar pore distribution (by Brunauer-Emmett-Teller, BET) that disfavored the cathode clogging. Particularly, a too-high Fe content led to iron segregation (by energy dispersive X-ray spectroscopy, EDX, X-ray photoelectron spectroscopy, XPS and FTIR) provoking a decrease of the electroactive sites, with negative consequences for the ORR.
Details
- Language :
- English
- ISSN :
- 2079-4991
- Volume :
- 10
- Issue :
- 9
- Database :
- MEDLINE
- Journal :
- Nanomaterials (Basel, Switzerland)
- Publication Type :
- Academic Journal
- Accession number :
- 32882878
- Full Text :
- https://doi.org/10.3390/nano10091735