TY - JOUR
T1 - Revisiting Solvent-Dependent Roles of the Electrolyte Counteranion in Li-O2 Batteries upon CO2 Incorporation
AU - Marques Mota, Filipe
AU - Kim, Yeonseo
AU - Hong, Haeji
AU - Yu, Subin
AU - Lee, Sangheon
AU - Kim, Dong Ha
N1 - Publisher Copyright:
© 2022 American Chemical Society
PY - 2022/2/28
Y1 - 2022/2/28
N2 - Lithium-oxygen batteries are promising next-generation high-energy storage candidates. Replacing pure O2 with air and uncovering moisture and CO2-contamination effects on the O2 electrochemistry, however, represent necessary steps toward commercialization. Representatively, a CO2-induced shift toward Li2CO3 formation has been systematically disclosed in a number of electrolyte solvents. Here, we show that in tetraglyme only Li2CO3 is formed without Li2O2. Using explicit theoretical calculations, we reveal that discharge is governed by the strong chelation effect induced by oxygen lone electron pairs of the glyme, which emphasizes the importance of assessing direct interatomic interactions between Li+ and solvent molecules when determining preferred reaction pathways in these O2/CO2 systems. The choice of the electrolyte counteranion investigated here for the first time, however, has no apparent effect on the O2/CO2 electrochemistry, leading to Li2CO3. Galvanostatic results and product analysisnonetheless reveal that highly dissociated Li+ counteranions in tetraglyme favorably stabilize soluble peroxocarbonate reaction intermediates during discharge, whereas highly associated salts accelerate Li2CO3 precipitation, dramatically narrowing the cell capacity. Importantly, these observations are also distinct from prior conclusions from rationally designed electrolytes under pure O2 conditions and emphasize the need to revisit established correlations between uncovered counteranion···Li+···solvent interaction degrees and the balance between mechanistic pathways in practical Li-air devices.
AB - Lithium-oxygen batteries are promising next-generation high-energy storage candidates. Replacing pure O2 with air and uncovering moisture and CO2-contamination effects on the O2 electrochemistry, however, represent necessary steps toward commercialization. Representatively, a CO2-induced shift toward Li2CO3 formation has been systematically disclosed in a number of electrolyte solvents. Here, we show that in tetraglyme only Li2CO3 is formed without Li2O2. Using explicit theoretical calculations, we reveal that discharge is governed by the strong chelation effect induced by oxygen lone electron pairs of the glyme, which emphasizes the importance of assessing direct interatomic interactions between Li+ and solvent molecules when determining preferred reaction pathways in these O2/CO2 systems. The choice of the electrolyte counteranion investigated here for the first time, however, has no apparent effect on the O2/CO2 electrochemistry, leading to Li2CO3. Galvanostatic results and product analysisnonetheless reveal that highly dissociated Li+ counteranions in tetraglyme favorably stabilize soluble peroxocarbonate reaction intermediates during discharge, whereas highly associated salts accelerate Li2CO3 precipitation, dramatically narrowing the cell capacity. Importantly, these observations are also distinct from prior conclusions from rationally designed electrolytes under pure O2 conditions and emphasize the need to revisit established correlations between uncovered counteranion···Li+···solvent interaction degrees and the balance between mechanistic pathways in practical Li-air devices.
KW - CO
KW - Li counteranion
KW - Li−air
KW - energy storage
KW - lithium−oxygen battery
UR - http://www.scopus.com/inward/record.url?scp=85124161747&partnerID=8YFLogxK
U2 - 10.1021/acsaem.1c03712
DO - 10.1021/acsaem.1c03712
M3 - Article
AN - SCOPUS:85124161747
SN - 2574-0962
VL - 5
SP - 2150
EP - 2160
JO - ACS Applied Energy Materials
JF - ACS Applied Energy Materials
IS - 2
ER -