Amir H. Farokh Niaei a*, Tanveer Hussain a, Marlies Hankel a, Debra J. Searles a,b

 

a Centre for Theoretical and Computational Molecular Science, Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, QLD 4072, Australia
b
School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia
*Corresponding Author’s E-mail:
amir.farokh@uq.edu.au

 

Abstract: Selection of a suitable anode material plays an important role in achieving good performance and high electrical capacity of rechargeable batteries. Sodium (Na) and calcium (Ca) offer some advantages over lithium (Li), like their abundancy and cheaper price 1. Recent experimental work has demonstrated that basal defects and/or functional groups on the edges of graphene-like sheets can lead to an enhancement of their capacity for adsorbing Li or Na 2-3. We performed first principles calculations using density functional theory (DFT) to investigate the adsorption of Na and Ca to hydrogenated defective graphene as a basal plane and then carbon nanoribbons with different functional groups on the edge.  

According to our results, a single layer of defective graphene with four carbon mono-vacancy and four hydrogen atoms (C68H4) can accommodate up to 16 Na or 14 Ca atoms, equivalent to 173.2 and 202.4 mAhg-1, respectively. Moreover, bulk layers of C68H4 with AA stacking type can accommodate up to 16 Ca atoms on each layer with 29.3% side expansion and 231.4 mAh/g electrical capacity, which is an acceptable value for anode material.

Moreover, Na binds strongly to carboxyl-terminated nanoribbons with Eb of -1.45 eV over the ring to -1.99 eV over the HOOC- group at the zig-zag edge which is reasonably strong. These values for Ca atom’s binding are found pretty stronger at -2.0 and -2.85 eV, respectively. Therefore, carboxylation of nanoribbons’ edges could be expected to increase the binding energy of Na and Ca if present in rechargeable battery anode materials.

References:

  1.  Farokh Niaei, A. H., J. of Power Sources 2017, 343, 354-363.
  2. Yoon, D., Carbon 2016, 98, 213-220.
  3. Lin, K.-H., J. Mater. Chem. A 2017, 5 (10), 4912-4922.

 

First Author: Amir H. Farokh Niaei
Affiliation: PhD Candidate at the Centre for Theoretical and Computational Molecule Sciences, The University of Queensland, Australia  
Phone: Tel: +61 7 3346 3949, Fax: +61 7 3346 3992, Email: amir.farokh@uq.edu.au
Research Interests: Nanomaterials, Carobn – non-carbon hybrid structures, Rechargeable battery materials, Density functional theory for molecular studies
Amir H. Farokh Niaei received his BSc degree from the School of Chemical Engineering, Sahand Technical University (Iran) in 2004 and MSc from the School of Chemical Engineering, AmirKabir Technical University (Iran) in 2007. His current research focuses on theoretical studies (using density functional theory DFT) of carbonaceous material for anodes of sodium and calcium ion rechargeable batteries.

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