Electrochemical Shock: Mechanical Degradation of Ion-Intercalation Materials
Event details
| Date | 28.04.2014 |
| Hour | 13:15 › 14:15 |
| Speaker | Craig Carter, Massachusetts Institute of Technology, Cambridge USA |
| Location | |
| Category | Conferences - Seminars |
(the work presented in this talk is the result of a collaboration with Dr. William Woodford and Prof. Yet-Ming Chiang)
Energy storage is an enabling technology for electrified transportation and for large-scale deployment of renewable energy resources such as solar and wind. For many applications, ion-intercalation chemistries, most notably lithium-ion, are attractive for high energy density and chemical reversibility. However, the electrode materials used in ion-intercalation batteries undergo large composition changes—which correlate to high storage capacity—but also induce structural changes and stresses that can cause performance metrics such as power, achievable storage capacity, and life to degrade.
“Electrochemical shock”—the electrochemical cycling-induced fracture of materials—contributes to impedance growth and performance degradation in ion-intercalation batteries. Using a combination of micromechanical models and in operando acoustic emission experiments, the mechanisms of electrochemical shock are identified, classified, and modeled in targeted model systems with different composition and microstructure. Three distinct mechanisms of electrochemical shock are identified, and a fracture mechanics failure criterion is derived for each mechanism.
This fundamental understanding of electrochemical shock leads naturally to practical design criteria for battery materials and microstructures that improve performance and energy storage efficiency. In a given material system, crystal symmetry and phase-behavior determine the active mechanisms. A surprising result is that electrochemical shock in commercial lithium-storage materials occurs by mechanisms that are insensitive to the electrochemical cycling rate. Using LiCoO2, LiMn2O4, and LiMn1.5Ni0.5O4 as model systems, electrochemical shock is observed during low-rate electrochemical cycling, in agreement with micromechanical models. Finally, iron-doping of LiMn1.5Ni0.5O4 is demonstrated to qualitatively change the phase-behavior in this material; this overcomes the low cycling rate electrochemical shock mechanisms and enables a wider range of particle sizes and duty cycles to be used without electrochemical shock. While lithium-storage materials are used as model systems for experimental study, the physical phenomena are common to other ion-intercalation systems, including sodium- and magnesium-storage compounds.
Bio: Bio
Energy storage is an enabling technology for electrified transportation and for large-scale deployment of renewable energy resources such as solar and wind. For many applications, ion-intercalation chemistries, most notably lithium-ion, are attractive for high energy density and chemical reversibility. However, the electrode materials used in ion-intercalation batteries undergo large composition changes—which correlate to high storage capacity—but also induce structural changes and stresses that can cause performance metrics such as power, achievable storage capacity, and life to degrade.
“Electrochemical shock”—the electrochemical cycling-induced fracture of materials—contributes to impedance growth and performance degradation in ion-intercalation batteries. Using a combination of micromechanical models and in operando acoustic emission experiments, the mechanisms of electrochemical shock are identified, classified, and modeled in targeted model systems with different composition and microstructure. Three distinct mechanisms of electrochemical shock are identified, and a fracture mechanics failure criterion is derived for each mechanism.
This fundamental understanding of electrochemical shock leads naturally to practical design criteria for battery materials and microstructures that improve performance and energy storage efficiency. In a given material system, crystal symmetry and phase-behavior determine the active mechanisms. A surprising result is that electrochemical shock in commercial lithium-storage materials occurs by mechanisms that are insensitive to the electrochemical cycling rate. Using LiCoO2, LiMn2O4, and LiMn1.5Ni0.5O4 as model systems, electrochemical shock is observed during low-rate electrochemical cycling, in agreement with micromechanical models. Finally, iron-doping of LiMn1.5Ni0.5O4 is demonstrated to qualitatively change the phase-behavior in this material; this overcomes the low cycling rate electrochemical shock mechanisms and enables a wider range of particle sizes and duty cycles to be used without electrochemical shock. While lithium-storage materials are used as model systems for experimental study, the physical phenomena are common to other ion-intercalation systems, including sodium- and magnesium-storage compounds.
Bio: Bio
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Practical information
- General public
- Free
Organizer
- Holger Frauenrath
Contact
- Holger Frauenrath