TY - JOUR
T1 - Revealing the Conversion Mechanism of Transition Metal Oxide Electrodes during Lithiation from First-Principles
AU - Yao, Zhenpeng
AU - Kim, Soo
AU - Aykol, Muratahan
AU - Li, Qianqian
AU - Wu, Jinsong
AU - He, Jiangang
AU - Wolverton, Chris
N1 - Funding Information:
Z.Y., Q.L., J.W., and C.W. (overall conception and design of calculations, major DFT calculation of structural pathway and voltage, and interpretation of data) were supported as part of the Center for Electrochemical Energy Science (CEES), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of the Science, Basic Energy Science. S.K. (initial voltage calculations) was supported by Northwestern-Argonne Institute of Science and Engineering (NAISE). M.A. (structure evolution analysis) was supported by the Dow Chemical Company. J.H. (Bader charge analysis) was supported by ONR STTR N00014-13-P-1056. We gratefully acknowledge the computing resources from the following: (1) The National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under Contract DE-AC02-05CH11231. (2) Blues, a high-performance computing cluster operated by the Laboratory Computing Resource Center at Argonne National Laboratory. We gratefully acknowledge professor Jordi Cabana from University of Illinois at Chicago, for helping us interpret the EXAFS data. We thank Dr. Michael M. Thackeray, Professor Vinayak P. Dravid, Dr. Maria K.Y. Chan, and Dr. Logan Ward for useful discussions.
Publisher Copyright:
© 2017 American Chemical Society.
PY - 2017/11/14
Y1 - 2017/11/14
N2 - Transition metal oxides such as Co3O4 and NiO are of significant interest as conversion anode materials for lithium-ion batteries (LIBs), due to their remarkably high theoretical capacities and low cost. While many previous experiments have found that the charge/discharge reactions of Co3O4 and NiO can be highly reversible, detailed information about the mechanisms of these reactions, such as the origin of the voltage hysteresis (>1.0 V) between the charge/discharge cycles, is still poorly understood. In this work, we develop and utilize a new computational mechanistic approach that helps elucidate the hysteresis and nonequilibrium reaction pathways associated with these conversion materials. We apply this methodology to investigate a variety of lithiation reaction pathways of Co3O4 and NiO by systematically exploring the energetics of a large number of equilibrium and nonequilibrium LixCo3O4 (0 ≤ x ≤ 8) and LixNiO (0 ≤ x ≤ 2) structural configurations using first-principles calculations. The overall value of the voltages from our nonequilibrium pathway is in much better agreement with experimental lithiation than the calculated equilibrium voltage while the overall value of the latter reasonably agrees with experimental delithiation. Hence, we propose the charge and discharge processes proceed through equilibrium and nonequilibrium reaction paths, respectively, which contribute significantly to the experimentally observed voltage hysteresis in Co3O4 and NiO. Additionally, we find a low-energy, lithiated intermediate phase (Li3Co3O4) with an oxygen framework equal to that of the initial Co3O4 spinel phase. This intermediate phase represents the capacity threshold below which limited volume expansion and better reversibility can be realized and above which reactions lead to structural degradation and huge expansion.
AB - Transition metal oxides such as Co3O4 and NiO are of significant interest as conversion anode materials for lithium-ion batteries (LIBs), due to their remarkably high theoretical capacities and low cost. While many previous experiments have found that the charge/discharge reactions of Co3O4 and NiO can be highly reversible, detailed information about the mechanisms of these reactions, such as the origin of the voltage hysteresis (>1.0 V) between the charge/discharge cycles, is still poorly understood. In this work, we develop and utilize a new computational mechanistic approach that helps elucidate the hysteresis and nonequilibrium reaction pathways associated with these conversion materials. We apply this methodology to investigate a variety of lithiation reaction pathways of Co3O4 and NiO by systematically exploring the energetics of a large number of equilibrium and nonequilibrium LixCo3O4 (0 ≤ x ≤ 8) and LixNiO (0 ≤ x ≤ 2) structural configurations using first-principles calculations. The overall value of the voltages from our nonequilibrium pathway is in much better agreement with experimental lithiation than the calculated equilibrium voltage while the overall value of the latter reasonably agrees with experimental delithiation. Hence, we propose the charge and discharge processes proceed through equilibrium and nonequilibrium reaction paths, respectively, which contribute significantly to the experimentally observed voltage hysteresis in Co3O4 and NiO. Additionally, we find a low-energy, lithiated intermediate phase (Li3Co3O4) with an oxygen framework equal to that of the initial Co3O4 spinel phase. This intermediate phase represents the capacity threshold below which limited volume expansion and better reversibility can be realized and above which reactions lead to structural degradation and huge expansion.
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U2 - 10.1021/acs.chemmater.7b02058
DO - 10.1021/acs.chemmater.7b02058
M3 - Article
AN - SCOPUS:85034020465
SN - 0897-4756
VL - 29
SP - 9011
EP - 9022
JO - Chemistry of Materials
JF - Chemistry of Materials
IS - 21
ER -