离子
锂(药物)
相(物质)
电子
化学物理
量子隧道
电子转移
动力学
离子运输机
原子物理学
化学
凝聚态物理
物理化学
物理
有机化学
医学
量子力学
内分泌学
作者
Xiaoxiao Wang,Jun Huang,Yuwen Liu,Shengli Chen
出处
期刊:Chemical Science
[The Royal Society of Chemistry]
日期:2023-01-01
卷期号:14 (45): 13042-13049
被引量:2
摘要
Understanding the mechanism of slow lithium ion (Li+) transport kinetics in LiFePO4 is not only practically important for high power density batteries but also fundamentally significant as a prototypical ion-coupled electron transfer process. Substantial evidence has shown that the slow ion transport kinetics originates from the coupled transfer between electrons and ions and the phase segregation of Li+. Combining a model Hamiltonian analysis and DFT calculations, we reveal that electrostatic interactions play a decisive role in coupled charge transfer and Li+ segregation. The obtained potential energy surfaces prove that ion-electron coupled transfer is the optimal reaction pathway due to electrostatic attractions between Li+ and e- (Fe2+), while prohibitively large energy barriers are required for separate electron tunneling or ion hopping to overcome the electrostatic energy between the Li+-e- (Fe2+) pair. The model reveals that Li+-Li+ repulsive interaction in the [010] transport channels together with Li+-e- (Fe2+)-Li+ attractive interaction along the [100] direction cause the phase segregation of Li+. It explains why the thermodynamically stable phase interface between Li-rich and Li-poor phases in LiFePO4 is perpendicular to [010] channels.
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