Joule
Volume 2, Issue 12, 19 December 2018, Pages 2649-2666
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Article
Tailoring the Discharge Reaction in Li-CO2 Batteries through Incorporation of CO2 Capture Chemistry

https://doi.org/10.1016/j.joule.2018.09.002Get rights and content
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Highlights

  • Develop a new strategy for promoting CO2 activity in nonaqueous media

  • Identify the role of alkyl amines in facilitating discharge in Li-CO2 batteries

  • Demonstrate pathways to combine CO2 capture and conversion in a single device

Context & Scale

The negative environmental impact of rising CO2 emissions has underscored the need for innovative approaches toward CO2 management, which are crucial not only for developing mitigation technologies to address sustainability challenges, but also for enhancing our scientific understanding of CO2 reactivity in different environments. This work presents the design and study of a novel chemistry for post-combustion CO2 capture and conversion. We show that adding a CO2 capture agent such as an alkyl amine into an organic, Li+-containing electrolyte yields a new redox-active species that can be directly reduced at a catalyst-free carbon electrode in a Li-CO2 battery with high discharge voltage and capacity. The central advance reported herein is the first-time coupling of CO2 capture chemistry to nonaqueous electrochemistry, which opens up new avenues for realizing electrochemical CO2 transformations with high selectivity.

Summary

The search for viable end-uses of CO2 has motivated considerable research into CO2 utilization in energy storage devices such as alkali metal-based O2/CO2 and -CO2 batteries. However, efforts have been stymied by the low electrochemical activity of CO2 in most organic media. In this work, we report a mediated CO2 capture and conversion process, based on amine (e.g., 2-ethoxyethylamine) chemisorption, which provides a new electrolyte system for facilitating the discharge reaction in Li-CO2 batteries. Our results indicate that electrochemical reduction of CO2-loaded amines proceeds at significantly higher discharge potentials (∼2.9 V versus Li/Li+) compared with physically dissolved CO2, which is inactive in the amine's absence. The discharge reaction forms solid-phase Li2CO3 as the primary discharge product and yields high discharge capacities (>1,000 mAh/gc), highlighting the coupling of CO2 capture chemistry to nonaqueous batteries as a promising approach for the design and manipulation of CO2 conversion reactions.

Keywords

carbon dioxide
CO2
CO2 capture
CO2 conversion
amine
Li-CO2 battery
electrochemical reduction
ethoxyethylamine
Li2CO3

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