2 research outputs found
Electrolyte-Induced Surface Transformation and Transition-Metal Dissolution of Fully Delithiated LiNi<sub>0.8</sub>Co<sub>0.15</sub>Al<sub>0.05</sub>O<sub>2</sub>
Enabling practical utilization of
layered <i>R</i>3Ì…<i>m</i> positive electrodes
near full delithiation requires an
enhanced understanding of the complex electrode–electrolyte
interactions that often induce failure. Using LiÂ[Ni<sub>0.8</sub>Co<sub>0.15</sub>Al<sub>0.05</sub>]ÂO<sub>2</sub> (NCA) as a model layered
compound, the chemical and structural stability in a strenuous thermal
and electrochemical environment was explored. <i>Operando</i> microcalorimetry and electrochemical impedance spectroscopy identified
a fingerprint for a structural decomposition and transition-metal
dissolution reaction that occurs on the positive electrode at full
delithiation. Surface-sensitive characterization techniques, including
X-ray absorption spectroscopy and high-resolution transmission electron
microscopy, measured a structural and morphological transformation
of the surface and subsurface regions of NCA. Despite the bulk structural
integrity being maintained, NCA surface degradation at a high state
of charge induces excessive transition-metal dissolution and significant
positive electrode impedance development, resulting in a rapid decrease
in electrochemical performance. Additionally, the impact of electrolyte
salt, positive electrode surface area, and surface Li<sub>2</sub>CO<sub>3</sub> content on the magnitude and character of the dissolution
reaction was studied
Electrolyte-Induced Surface Transformation and Transition-Metal Dissolution of Fully Delithiated LiNi<sub>0.8</sub>Co<sub>0.15</sub>Al<sub>0.05</sub>O<sub>2</sub>
Enabling practical utilization of
layered <i>R</i>3Ì…<i>m</i> positive electrodes
near full delithiation requires an
enhanced understanding of the complex electrode–electrolyte
interactions that often induce failure. Using LiÂ[Ni<sub>0.8</sub>Co<sub>0.15</sub>Al<sub>0.05</sub>]ÂO<sub>2</sub> (NCA) as a model layered
compound, the chemical and structural stability in a strenuous thermal
and electrochemical environment was explored. <i>Operando</i> microcalorimetry and electrochemical impedance spectroscopy identified
a fingerprint for a structural decomposition and transition-metal
dissolution reaction that occurs on the positive electrode at full
delithiation. Surface-sensitive characterization techniques, including
X-ray absorption spectroscopy and high-resolution transmission electron
microscopy, measured a structural and morphological transformation
of the surface and subsurface regions of NCA. Despite the bulk structural
integrity being maintained, NCA surface degradation at a high state
of charge induces excessive transition-metal dissolution and significant
positive electrode impedance development, resulting in a rapid decrease
in electrochemical performance. Additionally, the impact of electrolyte
salt, positive electrode surface area, and surface Li<sub>2</sub>CO<sub>3</sub> content on the magnitude and character of the dissolution
reaction was studied