Premium
First‐Principles Study of Magnesium Peroxide Nucleation for Mg‐Air Battery
Author(s) -
Bhauriyal Preeti,
Rawat Kuber Singh,
Bhattacharyya Gargee,
Garg Priyanka,
Pathak Biswarup
Publication year - 2018
Publication title -
chemistry – an asian journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.18
H-Index - 106
eISSN - 1861-471X
pISSN - 1861-4728
DOI - 10.1002/asia.201801057
Subject(s) - nucleation , overpotential , graphene , graphite , materials science , cathode , density functional theory , anode , battery (electricity) , chemical engineering , carbon fibers , magnesium , chemical physics , nanotechnology , chemistry , thermodynamics , computational chemistry , composite material , electrode , metallurgy , electrochemistry , organic chemistry , power (physics) , physics , composite number , engineering
Recently, rechargeable non‐aqueous Mg‐air batteries have gained a lot of interest as the next‐generation energy storage device due to the high theoretical volumetric density (3832 Ah L −1 for Mg anode vs. 2062 Ah L −1 for Li), low cost and safety. The field of Mg‐air batteries is in the initial stage of development having a limited number of experimental and theoretical reports, in which mainly a carbon cathode is used; however, the information regarding the structural form of carbon is still missing. In this work, using first‐principles density functional theory (DFT) calculations, we demonstrate the possibility of graphene and graphite as a cathode material towards Mg‐air batteries by studying the initial MgO and MgO 2 nucleation processes on the surfaces of graphene and graphite. The calculated free energy diagrams for the redox reactions of oxygen are used to identify the rate‐determining step controlling the overpotentials for initial nucleation of MgO and MgO 2 . We observe that graphene and graphite surfaces show similar reactivity towards the nucleation of MgO or MgO 2 , and the overpotential of the controlling steps for MgO 2 nucleation is comparatively less than that of MgO nucleation, which is supported by a recent experimental study, where a higher discharge voltage was observed in a cell having a mixed MgO/MgO 2 discharge product than MgO‐based cells. Furthermore, the preferable formation of MgO 2 cluster compared to MgO on the graphene surface during the ab initio molecular dynamic (AIMD) simulations confirms the selectivity of MgO 2 formation over MgO as the final discharge product. We believe that our study will be helpful in understanding the initial nucleation processes during the oxygen reduction reaction (ORR) mechanism and development of suitable cathodes for the future Mg‐air batteries.