Tailoring the Discharge Reaction in Li-CO2 Batteries through Incorporation of CO2 Capture Chemistry  Aliza Khurram, Mingfu He, Betar M. Gallant  Joule  Volume 2, Issue 12, Pages 2649-2666 (December 2018) DOI: 10.1016/j.joule.2018.09.002 Copyright © 2018 Elsevier Inc. Terms and Conditions

Joule 2018 2, 2649-2666DOI: (10.1016/j.joule.2018.09.002) Copyright © 2018 Elsevier Inc. Terms and Conditions

Figure 1 Cell Schematic and Reaction Scheme of a CO2 Capture-and-Electrochemical Conversion Process (A) Schematic of a combined capture and conversion Li-CO2 cell with amine regeneration. (B) Discharge reaction scheme showing the target reduction pathway via selective cleavage of the N-C bond. Joule 2018 2, 2649-2666DOI: (10.1016/j.joule.2018.09.002) Copyright © 2018 Elsevier Inc. Terms and Conditions

Figure 2 State of Amine-Containing Solvents upon CO2 Uptake with and without Electrolyte Co-Salts Solvent samples containing 0.1 M CO2-loaded EEA species (top row) and the same solutions upon introduction of 0.3 M LiClO4 (bottom row). Joule 2018 2, 2649-2666DOI: (10.1016/j.joule.2018.09.002) Copyright © 2018 Elsevier Inc. Terms and Conditions

Figure 3 Characterization of Amine-Containing DMSO before and after CO2 Uptake 1H NMR spectra of 50 mM lean EEA (bottom) and CO2-loaded EEA (top) in DMSO-d6. Joule 2018 2, 2649-2666DOI: (10.1016/j.joule.2018.09.002) Copyright © 2018 Elsevier Inc. Terms and Conditions

Figure 4 Characterization of Temporal Evolution of Carbamic Acid-Carbamate Equilibria upon Electrolyte Salt Addition (A) Time-dependent 1H NMR spectra of a solution containing 50 mM CO2-bound EEA in DMSO-d6 before the addition of 0.3 M LiClO4 (a), and 1 hr (b), 9 hr (c), and 24 hr (d) after the addition of 0.3 M LiClO4. (B) Reaction scheme showing conversion of carbamic acid to carbamate and a free CO2 upon Li+-salt addition in DMSO. Joule 2018 2, 2649-2666DOI: (10.1016/j.joule.2018.09.002) Copyright © 2018 Elsevier Inc. Terms and Conditions

Figure 5 Homogeneous Reduction of CO2-Loaded EEA by a Redox Mediator (CoCp2) (A) UV-visible spectra of 0.3 M LiClO4/DMSO containing CoCp2 and EEA in the presence and absence of CO2. The spectra of CoCp2 and CoCp2+ are provided as reference. (B) Photograph showing color changes upon addition of CoCp2 to the electrolyte containing either lean EEA (right) or CO2-loaded EEA (center). A solution containing CoCp2 and the electrolyte, not shown, yielded a color identical to the one observed for CoCp2 with lean EEA. Joule 2018 2, 2649-2666DOI: (10.1016/j.joule.2018.09.002) Copyright © 2018 Elsevier Inc. Terms and Conditions

Figure 6 Discharge Performance of Li-CO2 Cells Containing CO2-Loaded EEA at Varying Rates and Amine Concentrations (A) Discharge profiles of Li-CO2 cells at 10 mA/gc under Ar only, CO2 only (physically dissolved, no EEA), lean EEA (unloaded, no CO2) in DMSO, and loaded EEA-CO2 in DMSO. (B) Discharge profiles for cells containing 100 mM EEA-CO2 at varying current densities. (C and D) Concentration effect of EEA-CO2 on discharge potential (C) and capacities (D) for Li-CO2 cells discharged at 30 mA/gc. Joule 2018 2, 2649-2666DOI: (10.1016/j.joule.2018.09.002) Copyright © 2018 Elsevier Inc. Terms and Conditions

Figure 7 Characterization of Discharge Products and Evidence for Process Selectivity (A) X-ray diffraction of a GDL electrode discharged at 5.65 μA/cm2. The XRD spectrum of crystalline Li2CO3, acquired from the International Center for Diffraction Data database (ref. code: 00-001-0996), is provided as a reference. (B) SEM images of a Vulcan carbon cathode discharged at 30 mA/gc. The inset shows an SEM image of a pristine electrode (same scale bar). (C) Attenuated total reflectance infrared (transmittance) spectra of a pristine electrode, and an electrode discharged at 30 mA/gc. (D) Ex situ mass spectrometer analysis measuring moles of CO2 evolved after discharged electrode treatment with H3PO4 and Fenton's reagent.69 The discharged Li-CO2 cell contained 13CO2 and a 12C cathode. Joule 2018 2, 2649-2666DOI: (10.1016/j.joule.2018.09.002) Copyright © 2018 Elsevier Inc. Terms and Conditions