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Síntesis del LiFeO2 tetraédrico y su comportamiento como cátodo en baterías de litio recargables
A Robert Armstrong1, Daniel W Tee, Fabio La Mantia
1EaStCHEM, School of Chemistry, University of St. Andrews, St. Andrews, Fife, KY16 9ST, UK.
Journal of the American Chemical Society
|February 21, 2008
Resumen
El primer hierro tetraédricamente coordinado ((III) óxido de litio-hierro (LiFeO2) almacena 120 mAhg ((-1) carga, pero se convierte en LiFe5O8 a través de la reacción de electrolito y la pérdida de agua durante el ciclo.
Área de la Ciencia:
- Ciencia de los materiales Ciencia de los materiales.
- La electroquímica es electroquímica.
- Química del estado sólido Química del estado sólido
Sus antecedentes:
- El óxido de hierro de litio (LiFeO2) es un nuevo material para baterías de iones de litio.
- Comprender su comportamiento electroquímico y sus vías de degradación es crucial para el desarrollo de la batería.
Objetivo del estudio:
- Para sintetizar y caracterizar LiFeO2 con Fe3+ coordinado tetraédricamente.
- Para investigar la capacidad de almacenamiento de carga y la estabilidad de ciclo de LiFeO2.2.
- Para dilucidar el mecanismo de conversión de LiFeO2 durante el ciclo electroquímico.
Principales métodos:
- Síntesis de LiFeO2.2, también conocido como LiFeO2.
- Difracción de rayos X en polvo (PXRD).
- Espectrometría de masas electroquímica diferencial (DEMS).
- El ciclo electroquímico.
- Análisis termogravimétrico junto con espectrometría de masas (TG-MS).
Principales resultados:
- Se sintetizó el primer compuesto LiFeO2 con Fe3+ coordinado tetraédricamente.
- El material demostró una capacidad de almacenamiento de carga de hasta 120 mAhg{-1) a 100 mAg{-1).
- En el ciclo, LiFeO2 se convierte en un defecto spinel LiFe5O8 a través de un proceso que implica la pérdida de oxígeno y la reacción con el electrolito, no O2.
Conclusiones:
- El mecanismo de conversión implica el intercambio de Li+/H+ y la pérdida de H2O, lo que lleva a la formación de LiFe5O8.8.
- Esta conversión limita la ciclabilidad a largo plazo de LiFeO2 como material de electrodo positivo.
- Se necesita más investigación para estabilizar el LiFeO2 o desarrollar materiales alternativos con un mejor rendimiento en ciclos.
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