Transition Metal Phthalocyanines as Redox Mediators in Li-O2Batteries: A Combined Experimental and Theoretical Study of the Influence of 3d Electrons in Redox Mediation

Mandal, S and Samajdar, RN and Parida, S and Mishra, S and Bhattacharyya, AJ (2022) Transition Metal Phthalocyanines as Redox Mediators in Li-O2Batteries: A Combined Experimental and Theoretical Study of the Influence of 3d Electrons in Redox Mediation. In: ACS Applied Materials and Interfaces, 14 (23). pp. 26714-26723.

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Abstract

Redox mediation is an innovative strategy for ensuring efficient energy harvesting from metal-oxygen systems. This work presents a systematic exploratory analysis of first-row transition-metal phthalocyanines as solution-state redox mediators for lithium-oxygen batteries. Our findings, based on experiment and theory, convincingly demonstrate that d5 (Mn), d7 (Co), and d8 (Ni) configurations function better compared to d6 (Fe) and d9 (Cu) in redox mediation of the discharge step. The d10 configuration (Zn) and non-d analogues (Mg) do not show any redox mediation because of the inability of binding with oxygen. The solution-state discharge product, transition-metal bound Li2O2, undergoes dissociation and oxidation in the charging step of the battery, thus confirming a bifunctional redox mediation. Apart from the reaction pathways predicted based on thermodynamic considerations, density functional theory calculations also reveal interesting effects of electrochemical perturbation on the redox mediation mechanisms and the role of the transition-metal center.

Item Type:	Journal Article
Publication:	ACS Applied Materials and Interfaces
Publisher:	American Chemical Society
Additional Information:	The copyright for this article belongs to the American Chemical Society.
Keywords:	Density functional theory; Energy harvesting; Lithium; Lithium batteries; Oxygen, DFT calculation; Electrochemistry of transition-metal phthalocyanine; GITT; Impedance; Li-oxygen battery; Metalphthalocyanines; Reaction mechanism; Reaction mechanism of ORR and OER; Redox mediators; Theoretical study, Transition metals
Department/Centre:	Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Date Deposited:	21 Jul 2022 05:21
Last Modified:	21 Jul 2022 05:21
URI:	https://eprints.iisc.ac.in/id/eprint/74964

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