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Title: New Insights into the Instability of Discharge Products in Na–O 2 Batteries

Abstract

Sodium–oxygen batteries currently stimulate extensive research due to their high theoretical energy density and improved operational stability when compared to lithium–oxygen batteries. Cell stability, however, needs to be demonstrated also under resting conditions before future implementation of these batteries. In this work we analyze the effect of resting periods on the stability of the sodium superoxide (NaO 2) discharge product. The instability of NaO 2 in the cell environment is demonstrated leading to the evolution of oxygen during the resting period and the decrease of the cell efficiency. In addition, migration of the superoxide anion (O2–) in the electrolyte is observed and demonstrated to be an important factor affecting Coulombic efficiency.

Authors:
; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE)
OSTI Identifier:
1340687
DOE Contract Number:
AC02-06CH11357
Resource Type:
Journal Article
Resource Relation:
Journal Name: ACS Applied Materials and Interfaces; Journal Volume: 8; Journal Issue: 31
Country of Publication:
United States
Language:
English
Subject:
25 ENERGY STORAGE; discharge stability; Na−O2 batteries

Citation Formats

Landa-Medrano, Imanol, Pinedo, Ricardo, Bi, Xuanxuan, Ruiz de Larramendi, Idoia, Lezama, Luis, Janek, Jürgen, Amine, Khalil, Lu, Jun, and Rojo, Teófilo. New Insights into the Instability of Discharge Products in Na–O 2 Batteries. United States: N. p., 2016. Web. doi:10.1021/acsami.6b06577.
Landa-Medrano, Imanol, Pinedo, Ricardo, Bi, Xuanxuan, Ruiz de Larramendi, Idoia, Lezama, Luis, Janek, Jürgen, Amine, Khalil, Lu, Jun, & Rojo, Teófilo. New Insights into the Instability of Discharge Products in Na–O 2 Batteries. United States. doi:10.1021/acsami.6b06577.
Landa-Medrano, Imanol, Pinedo, Ricardo, Bi, Xuanxuan, Ruiz de Larramendi, Idoia, Lezama, Luis, Janek, Jürgen, Amine, Khalil, Lu, Jun, and Rojo, Teófilo. Wed . "New Insights into the Instability of Discharge Products in Na–O 2 Batteries". United States. doi:10.1021/acsami.6b06577.
@article{osti_1340687,
title = {New Insights into the Instability of Discharge Products in Na–O 2 Batteries},
author = {Landa-Medrano, Imanol and Pinedo, Ricardo and Bi, Xuanxuan and Ruiz de Larramendi, Idoia and Lezama, Luis and Janek, Jürgen and Amine, Khalil and Lu, Jun and Rojo, Teófilo},
abstractNote = {Sodium–oxygen batteries currently stimulate extensive research due to their high theoretical energy density and improved operational stability when compared to lithium–oxygen batteries. Cell stability, however, needs to be demonstrated also under resting conditions before future implementation of these batteries. In this work we analyze the effect of resting periods on the stability of the sodium superoxide (NaO2) discharge product. The instability of NaO2 in the cell environment is demonstrated leading to the evolution of oxygen during the resting period and the decrease of the cell efficiency. In addition, migration of the superoxide anion (O2–) in the electrolyte is observed and demonstrated to be an important factor affecting Coulombic efficiency.},
doi = {10.1021/acsami.6b06577},
journal = {ACS Applied Materials and Interfaces},
number = 31,
volume = 8,
place = {United States},
year = {Wed Aug 10 00:00:00 EDT 2016},
month = {Wed Aug 10 00:00:00 EDT 2016}
}
  • Sodium-ion batteries are now close to replacing lithium-ion batteries because they provide superior alternative energy storage solutions that are in great demand, particularly for large-scale applications. To that end, the present study is focused on the properties of a new type of dual-electrode material, Na 0.5Ni 0.25Mn 0.75O 2, synthesized using a mixed hydroxycarbonate route. Cyclic voltammetry confirms that redox couples, at high and low voltage ranges, are facilitated by the unique features and properties of this dual-electrode, through sodium ion deintercalation/intercalation into the layered Na 0.5Ni 0.25Mn 0.25O 2 material. This material provides superior performance for Na-ion batteries, asmore » evidenced by the fabricated sodium cell that yielded initial charge discharge capacities of 125/218 mAh g -1 in the voltage range of 1.5-4.4 V at 0.5 C. At a low voltage range (1.5-2.6 V), the anode cell delivered discharge charge capacities of 100/99 mAh g -1 with 99% capacity retention, which corresponds to highly reversible redox reaction of the Mn 4+/3+ reduction and the Mn 3+/4+ oxidation observed at 1.85 and 2.06 V, respectively. The symmetric Na-ion cell, fabricated using Na 0.5Ni 0.25Mn 0.25O 2, yielded initial charge discharge capacities of 196/187 μAh at 107 μA. Lastly, these results encourage the further development of new types of futuristic sodium-ion battery-based energy storage systems.« less
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  • The new compounds NaBi{sub 6}O{sub 9}X (X = Br, I) were synthesized. Attempts to synthesize the analogous RbBi{sub 6}O{sub 9}X (X = Br, I) compounds yielded mixed systems with about 10% of the Rb atoms replaced by Na and K atoms. Another mixed system, Na{sub 0.77(3)}K{sub 0.23(3)}Bi{sub 6}O{sub 9}I, was obtained incidentally. The corresponding ABi{sub 6}O{sub 9}X compounds with X = Cl or A = Cs could not be obtained. The influence of A and X on the size of the ABi{sub 6}O{sub 9}X unit cell is discussed.
  • The development of nonaqueous Li–oxygen batteries, which relies on the reversible reaction of Li + O 2 to give lithium peroxide (Li 2O 2), is challenged by several factors, not the least being the high charging voltage that results when carbon is typically employed as the cathode host. We report here on the remarkably low 3.2 V potential for Li 2O 2 oxidation on a passivated nanostructured metallic carbide (Mo 2C), carbon-free cathode host. Furthermore, online mass spectrometry coupled with X-ray photoelectron spectroscopy unequivocally demonstrates that lithium peroxide is simultaneously oxidized together with the Li xMoO 3-passivated conductive interface formedmore » on the carbide, owing to their close redox potentials. We found that the process rejuvenates the surface on each cycle upon electrochemical charge by releasing Li xMoO 3 into the electrolyte, explaining the low charging potential.« less
  • Catalytic conversion of N{sub 2}O to N{sub 2} over Na- and K-impregnated activated carbon (Na/AC and K/AC) was investigated. K and Na are two representative and most active catalysts for the C-NO{sub x} reactions. Carbon samples with different K and Na loadings were characterized by N{sub 2} adsorption, thermal decomposition (with TGA), TPD, and CO{sub 2} chemisorption at 250 C. CO{sub 2} chemisorption at 250 C proved to be effective for the measurement of potassium dispersion but not for sodium. Using N{sub 2}O as the reactant facilitated the observation and analysis of the reaction mechanism of gas-carbon reactions due tomore » its readiness for dissociative chemisorption and also because the C-N{sub 2}O reaction is an elementary reaction. Based on isothermal reactions and TPR, potassium was found to be more active in both N{sub 2}O dissociation and oxygen transfer thus gave rise to a much higher activity. It was found that K/C was an excellent catalyst for N{sub 2}O decomposition. In the low-temperature range of 150--250 C, a significant amount of N{sub 2} was produced on K/C with no carbon gasification. Significant CO{sub 2} production occurred only at higher temperatures. The fundamental reason for the difference in activities of the two alkali metals is a combination of three factors. First, K/C is highly active for N{sub 2}O dissociation. The O atoms thus produced would form active surface intermediates, most likely the epoxy intermediate which significantly weakened the surface C-C bonds for gasification (which is the basis of the unified mechanism of Chen and Yang). Second, the surface phenolate group also weakened the C-C bond to facilitate gasification, but the weakening was more pronounced by the -C-O-K group than by the -C-O-Na group. Third, the dispersion of K{sub 2}O on carbon was higher than that of Na{sub 2}O.« less