Universität zu Köln

Ludwig, Tim, Je, Minyeong, Choi, Heechae, Fischer, Thomas, Roitsch, Stefan, Mueller, Ralf, Mane, Rajaram S., Kim, Kwang Ho and Mathur, Sanjay ORCID: 0000-0003-2765-2693 (2020). Boosting nitrogen-doping and controlling interlayer spacing in pre-reduced graphene oxides. Nano Energy, 78. AMSTERDAM: ELSEVIER. ISSN 2211-3282

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Abstract

Controlling interlayer spacing in graphene oxide materials is an effective strategy to unify high conductivity with high intercalation and storage properties. Free-standing films of reduced graphene oxide (rGO) match these characteristics and are capable of replacing metal-based anodes in lithium-ion batteries (LIBs) crucially essential for enhanced flexibility and gravimetric energy density of devices currently sought for wearable and stretchable electronics. Restoring high electrical conductivity through chemical reduction of graphene oxide (GO) remains elusive due to interplay of desired in-plane conductivity and interlayer ion transport. A chemical pre-reduction step introduced in this work alleviated the defect density in graphene oxides to enable the incorporation of nitrogen by annealing in NH3 atmosphere. Decreased oxygen contents were observed upon pre-reduction through a deoxygenation process (C:O ratio GO: 1.7, rGO: 11.4, pre-reduced rGO: 34.8) to effectively restore the aromatic character in rGO films. The pre-reduction altered the chemical topography and reinforced the interlayer interactions of the resulting N:rGO films to boost the electrical conductivity (pre-reduced rGO: 11759 S m(-1), pre-reduced N:rGO: 25253 S m(-1)) and produce more densely packed structures. DFT calculations confirmed a gradual decrease in interlayer spacing values in GO (4.85 angstrom), N:rGO (3.83 angstrom) and pre-reduced N: rGO* (3.61 angstrom) samples, which validated the critical role of chemical pre-reduction. The DFT calculations also explained the differential behavior of N-doped and pre-reduced rGO films on significantly enhanced electrical conductivity and lithium storage capacity (rGO: 1208 S m(-1), 261 mAh g(-1); N:rGO: 10574 S m(-1), 529 mAh g(-1)). This work presents a facile pathway to overcome the persisting limitation of 2D carbon nanostructures prepared by aqueous processing to produce chemically engineered graphitic carbons as anodes for lithium ion batteries.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Ludwig, Tim UNSPECIFIED UNSPECIFIED UNSPECIFIED Je, Minyeong UNSPECIFIED UNSPECIFIED UNSPECIFIED Choi, Heechae UNSPECIFIED UNSPECIFIED UNSPECIFIED Fischer, Thomas UNSPECIFIED UNSPECIFIED UNSPECIFIED Roitsch, Stefan UNSPECIFIED UNSPECIFIED UNSPECIFIED Mueller, Ralf UNSPECIFIED UNSPECIFIED UNSPECIFIED Mane, Rajaram S. UNSPECIFIED UNSPECIFIED UNSPECIFIED Kim, Kwang Ho UNSPECIFIED UNSPECIFIED UNSPECIFIED Mathur, Sanjay UNSPECIFIED orcid.org/0000-0003-2765-2693 UNSPECIFIED
URN:	urn:nbn:de:hbz:38-309631
DOI:	10.1016/j.nanoen.2020.105286
Journal or Publication Title:	Nano Energy
Volume:	78
Date:	2020
Publisher:	ELSEVIER
Place of Publication:	AMSTERDAM
ISSN:	2211-3282
Language:	English
Faculty:	Faculty of Mathematics and Natural Sciences
Divisions:	Faculty of Mathematics and Natural Sciences > Department of Chemistry > Institute of Inorganic Chemistry
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language GENERALIZED GRADIENT APPROXIMATION; CHEMICAL-REDUCTION; DOPED GRAPHENE; THIN-FILM; FACILE FABRICATION; HIGH-QUALITY; ANODE; GRAPHITE; CONDUCTIVITY; NANOSHEETS Multiple languages Chemistry, Physical; Nanoscience & Nanotechnology; Materials Science, Multidisciplinary; Physics, Applied Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/30963