Increasing the efficiency and cycle life of Na-O2 batteries based on graphene cathodes with heteroatom doping

To overcome the challenges of Na-O2 batteries with respect to efficiency, capacity, and cycle life as well as to develop cheap, metal-free, and abundant electrocatalysts, we explored boron and nitrogen-functionalized graphene aerogels prepared by the hydrothermal self-assembly of graphene oxide with subsequent thermal reduction. The results showed an improve of both the cycling overpotential and the coulombic efficiency for the functionalized graphene aerogels. However, the nitrogen-containing cathode presented a shortened cycle life and decreased charging stability. The postmortem analysis of the full discharge, and the full discharge and charge cathodes demonstrated that nitrogen functionalization triggered the formation of solid parasitic products that passivate the cathode surface, thus resulting in a poorer electrochemical performance. By contrast, functionalization with boron-containing groups demonstrated to be a more promising strategy due to minimized parasitic products, leading to lower oxygen reduction and evolution overpotentials with a concomitantly enhanced cell efficiency vs. the undoped cathodes. This resulted in a cycle life of 70 cycles at a relatively high current density of 0.1 mA cm−2 with a capacity cut-off of 0.5 mAh cm−2. Our study underscores that functionalization with heteroatoms simultaneously alters multiple characteristics of graphene-based materials, including their chemistry, texture and morphology, which in turn presents a critical impact on the electrochemical response of the resultant Na-O2 cells.

Bibliographic Details

Main Authors:	Enterría González, Marina, Mysyk, R., Medinilla, L., Villar Rodil, Silvia, Paredes Nachón, Juan Ignacio, Rincón, I., Fernández-Carretero, F. J., Gómez, K., del Amo, J. M.López, Ortiz-Vitoriano, N.
Other Authors:	European Commission
Format:	artículo biblioteca
Language:	English
Published:	Elsevier 2023-03-20
Subjects:	Sodium, Cycling, Graphene, Metal-air batteries, Parasitic reactions, Ensure access to affordable, reliable, sustainable and modern energy for all, Build resilient infrastructure, promote inclusive and sustainable industrialization and foster innovation, Green chemistry,
Online Access:	http://hdl.handle.net/10261/343117 http://dx.doi.org/10.13039/501100004837 http://dx.doi.org/10.13039/501100000780 http://dx.doi.org/10.13039/100011941 https://api.elsevier.com/content/abstract/scopus_id/85148536807
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