TY - JOUR
T1 - Tuning the solution structure of electrolyte for optimal solid-electrolyte-interphase formation in high-voltage lithium metal batteries
AU - Chen, Juner
AU - Liu, Tingyu
AU - Gao, Lina
AU - Qian, Yumin
AU - Liu, Yaqin
AU - Kong, Xueqian
N1 - Publisher Copyright:
© 2021 Science Press
PY - 2021/9
Y1 - 2021/9
N2 - The continuous reduction of electrolytes by Li metal leads to a poor lifespan of lithium metal batteries (LMBs). Low Coulombic efficiency (CE) and safety concern due to dendrite growth are the challenging issues for LMB electrolyte design. Novel electrolytes such as highly concentrated electrolytes (HCEs) have been proposed for improving interphase stability. However, this strategy is currently limited for high cost due to the use of a large amount of lithium salts as well as their high viscosity, reduced ion mobility, and poor wettability. In this work, we propose a new type of electrolyte having a moderate concentration. The electrolyte has the advantage of HCEs as the anion is preferentially reduced to form inorganic solid-electrolyte-interphase (SEI). Such optimization has been confirmed through combined spectroscopic and electrochemical characterizations and supported with the first-principle molecular dynamics simulation. We have shown the intrinsic connections between solution structure and their electrochemical stability. The 2.0 M LiDFOB/PC electrolyte, as predicted by our characterizations and simulations, allows stable charge–discharge of LNMO|Li cells at 5C for more than 1500 cycles. The 2.0 M electrolyte generates a dense layer of SEI containing fluoro-oxoborates, Li3BO3, LiF, Li2CO3, and some organic species effectively passivating the lithium metal, as confirmed by electron microscopy, X-ray photoelectron spectroscopy, and solid-state nuclear magnetic resonance.
AB - The continuous reduction of electrolytes by Li metal leads to a poor lifespan of lithium metal batteries (LMBs). Low Coulombic efficiency (CE) and safety concern due to dendrite growth are the challenging issues for LMB electrolyte design. Novel electrolytes such as highly concentrated electrolytes (HCEs) have been proposed for improving interphase stability. However, this strategy is currently limited for high cost due to the use of a large amount of lithium salts as well as their high viscosity, reduced ion mobility, and poor wettability. In this work, we propose a new type of electrolyte having a moderate concentration. The electrolyte has the advantage of HCEs as the anion is preferentially reduced to form inorganic solid-electrolyte-interphase (SEI). Such optimization has been confirmed through combined spectroscopic and electrochemical characterizations and supported with the first-principle molecular dynamics simulation. We have shown the intrinsic connections between solution structure and their electrochemical stability. The 2.0 M LiDFOB/PC electrolyte, as predicted by our characterizations and simulations, allows stable charge–discharge of LNMO|Li cells at 5C for more than 1500 cycles. The 2.0 M electrolyte generates a dense layer of SEI containing fluoro-oxoborates, Li3BO3, LiF, Li2CO3, and some organic species effectively passivating the lithium metal, as confirmed by electron microscopy, X-ray photoelectron spectroscopy, and solid-state nuclear magnetic resonance.
KW - Electrolyte
KW - First principle molecular dynamics
KW - Li metal battery
KW - Solid-electrolyte-interphase
KW - Solution structure
UR - http://www.scopus.com/inward/record.url?scp=85100389002&partnerID=8YFLogxK
U2 - 10.1016/j.jechem.2021.01.007
DO - 10.1016/j.jechem.2021.01.007
M3 - Article
AN - SCOPUS:85100389002
SN - 2095-4956
VL - 60
SP - 178
EP - 185
JO - Journal of Energy Chemistry
JF - Journal of Energy Chemistry
ER -