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Cálculo directo del transporte de iones de litio en la interfase del electrolito sólido
Siqi Shi1, Peng Lu, Zhongyi Liu
1School of Engineering, Brown University, Providence, Rhode Island 02912, USA.
Journal of the American Chemical Society
|August 23, 2012
Resumen
Comprender el transporte de iones de litio en películas de interfase de electrolito sólido (SEI) es crucial. Este estudio revela el transporte de Li(+) a través de un mecanismo de knock-off en el Li(2)CO(3) cristalino dentro de las capas SEI.
Área de la Ciencia:
- Ciencia de los materiales Ciencia de los materiales.
- La electroquímica es electroquímica.
- Química computacional es la química computacional.
Sus antecedentes:
- La interfase de electrolito sólido (SEI) es crítica para el rendimiento y la longevidad de la batería de iones de litio.
- El mecanismo preciso del transporte de Li (((+) a través del SEI sigue siendo poco conocido.
- Las películas SEI típicas comprenden capas externas orgánicas porosas y capas internas inorgánicas densas.
Objetivo del estudio:
- Para dilucidar el mecanismo de transporte de Li ((+) dentro de las películas SEI utilizando una metodología teórica multiscala.
- Para investigar la difusión de Li(+) en el Li(2) CO(3) cristalino, un componente importante de la capa interna del SEI.
- Desarrollar un modelo predictivo para las propiedades de transporte de Li ((+) en capas de IES.
Principales métodos:
- Desarrollo de una metodología teórica multiscala que combine cálculos de primeros principios y ecuaciones de difusión de mesoscala.
- Utilizando la teoría funcional de la densidad (DFT) para determinar los portadores y mecanismos de difusión dominantes en Li(2) CO(3).
- Formulación de un modelo de difusión de dos capas/dos mecanismos (difusión de poros y difusión knock-off) basado en datos experimentales.
Principales resultados:
- La teoría funcional de la densidad identificó el exceso de Li intersticial (((+) como el portador de difusión dominante en Li (((2) CO ((3).
- Se determinó que un mecanismo de difusión "nock-off", que mantiene la coordinación O, prevalece sobre el salto directo.
- El modelo multiscala predijo con precisión el perfil de relación de isótopos de litio medido a través de la capa SEI sin parámetros de ajuste.
Conclusiones:
- El estudio aclara el mecanismo a escala atómica del transporte de Li (((+) en el Li (((2) CO ((3) cristalino dentro de las capas SEI.
- Un nuevo modelo multiscala describe con éxito el transporte de Li ((+) a través de diferentes capas y mecanismos de SEI.
- La metodología proporciona un marco para predecir las propiedades de transporte de SEI y comprender el envejecimiento de la batería.
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