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Acoplamiento redox de superficie a masa a través de la redistribución de litio impulsada térmicamente en materiales
Shaofeng Li1,2, Sang-Jun Lee1, Xuelong Wang3,4
1Stanford Synchrotron Radiation Lightsource , SLAC National Accelerator Laboratory , Menlo Park , California 94025 , United States.
Journal of the American Chemical Society
|July 10, 2019
Resumen
Las temperaturas ligeramente elevadas desencadenan el acoplamiento redox en materiales catódicos ricos en litio y manganeso (LMR). Este estudio revela la transferencia de carga impulsada térmicamente entre los aniones de oxígeno y los metales de transición en los materiales de LMR.
Área de la Ciencia:
- Ciencias de los materiales
- La electroquímica
- Almacenamiento de energía
Sus antecedentes:
- Los materiales de cátodo en capas ricos en litio y manganeso (LMR) ofrecen una alta capacidad y densidad de energía debido a la actividad redox acoplada de metales de transición y aniones de oxígeno.
- La evolución electroquímica redox en los cátodos LMR está bien estudiada a temperatura ambiente.
- Los efectos térmicos sobre el comportamiento del cátodo de la LMR, especialmente en condiciones no electroquímicas, siguen siendo en gran medida inexplorados.
Objetivo del estudio:
- Para investigar los efectos de acoplamiento redox impulsados térmicamente en materiales cargados de Li1.2Ni0.15Co0.1Mn0.55O2 (LMR) a temperaturas ligeramente elevadas (hasta ~ 100 °C).
- Comprender las interacciones redox de superficie a volumen influenciadas por las perturbaciones de temperatura en ausencia de fuerza motriz electroquímica.
Principales métodos:
- Estudio sistemático del material cargado Li1.2Ni0.15Co0.1Mn0.55O2
- Aplicación de una tensión térmica leve (hasta ~ 100 °C) para inducir el acoplamiento redox de superficie a volumen.
- Análisis de los mecanismos de transferencia de carga entre los aniones de oxígeno y los cationes de metales de transición.
Principales resultados:
- Primera observación de la transferencia de carga entre los aniones de oxígeno en masa y los cationes metálicos de transición superficiales en materiales con LMR a ~ 100 °C.
- Atribución de esta transferencia de carga a la redistribución impulsada térmicamente de iones de litio.
- Demostración de un estado de no equilibrio dinámico en materiales con LMR profundamente deslitizados bajo una perturbación térmica leve.
Conclusiones:
- Las temperaturas ligeramente elevadas pueden inducir una actividad redox significativa en los materiales del cátodo LMR, independientemente del ciclo electroquímico.
- Los resultados ponen de relieve la importancia de las consideraciones de estabilidad térmica para los materiales con LMR en aplicaciones prácticas.
- La comprensión de estos procesos impulsados térmicamente es crucial para optimizar el rendimiento y la seguridad de las tecnologías avanzadas de baterías.
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