Chemical vs Electrochemical Formation of Li2CO3 as a Discharge Product in Li-O2/CO2 Batteries by Controlling the Superoxide Intermediate

Wei Yin; Alexis Grimaud; Florent Lepoivre; Chunzhen Yang; Jean Marie Tarascon

doi:10.1021/acs.jpclett.6b02610

Chemical vs Electrochemical Formation of Li₂CO₃ as a Discharge Product in Li-O₂/CO₂ Batteries by Controlling the Superoxide Intermediate

J Phys Chem Lett. 2017 Jan 5;8(1):214-222. doi: 10.1021/acs.jpclett.6b02610. Epub 2016 Dec 19.

Authors

Wei Yin^{1

2}, Alexis Grimaud^{1

3}, Florent Lepoivre^{1

2}, Chunzhen Yang¹, Jean Marie Tarascon^{1

2

3

4}

Affiliations

¹ Chimie du Solide et de l'Energie, UMR 8260, Collège de France , 75231, Paris Cedex 05, France.
² Sorbonne Universités - UPMC Université Paris 06 , F-75005 Paris, France.
³ Réseau sur le Stockage Electrochimique de l'Energie (RS2E), CNRS FR 3459 , 33 rue Saint Leu, 80039, Amiens Cedex, France.
⁴ ALISTORE-European Research Institute , FR CNRS 3104, 80039 Amiens, France.

PMID: 27960058
DOI: 10.1021/acs.jpclett.6b02610

Abstract

The Li-O₂/CO₂ battery with high capacity has recently been proposed as a new protocol to convert CO₂. However, the fundamental mechanism for the reaction still remains hazy. Here, we investigated the discharge processes of Li-O₂/CO₂ (70%/30%) batteries in two solvents, dimethyl sulfoxide (DMSO) and 1,2-dimethoxyethane (DME). During discharge, both solvents initially show the reduction of oxygen. However, afterward, the solvent affects the reaction pathways of superoxide species by solvating Li⁺ with different strength, depending on the so-called donor number. More precisely, the initial formation of CO₄^•- is favored in DMSO at the expense of lithium superoxide formation that we observed in DME. Despite the different intermediate processes, X-ray diffraction showed that Li₂CO₃ was the final discharge product in both solvents. Moreover, we observed that CO₂ cannot be reduced within the electrochemical stability window of DMSO and DME.