1. Lithiation Mechanism in High-Entropy Oxides as Anode Materials for Li-Ion Batteries: An Operando XAS Study
- Author
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Ghigna, P, Airoldi, L, Fracchia, M, Callegari, D, Anselmi-Tamburini, U, D'Angelo, P, Pianta, N, Ruffo, R, Cibin, G, De Souza, D, Quartarone, E, Ghigna P., Airoldi L., Fracchia M., Callegari D., Anselmi-Tamburini U., D'angelo P., Pianta N., Ruffo R., Cibin G., De Souza D. O., Quartarone E., Ghigna, P, Airoldi, L, Fracchia, M, Callegari, D, Anselmi-Tamburini, U, D'Angelo, P, Pianta, N, Ruffo, R, Cibin, G, De Souza, D, Quartarone, E, Ghigna P., Airoldi L., Fracchia M., Callegari D., Anselmi-Tamburini U., D'angelo P., Pianta N., Ruffo R., Cibin G., De Souza D. O., and Quartarone E.
- Abstract
High-entropy oxides based on transition metals, such as Mg0.2Co0.2Ni0.2Cu0.2Zn0.2O (TM-HEO), have recently drawn special attention as potential anodes in lithium-ion batteries due to high specific capacity and cycling reversibility. However, the lithiation/delithiation mechanism of such systems is still controversial and not clearly addressed. Here, we report on an operando XAS investigation into TM-HEO-based anodes for lithium-ion cells during the first lithiation/delithiation cycle. This material showed a high specific capacity exceeding 600 mAh g-1 at 0.1 C and Coulombic efficiency very close to unity. The combination of functional and advanced spectroscopic studies revealed complex charging mechanisms, developing through the reduction of transition-metal (TM) cations, which triggers the conversion reaction below 1.0 V. The conversion is irreversible and incomplete, leading to the final collapse of the HEO rock-salt structure. Other redox processes are therefore discussed and called to account for the observed cycling behavior of the TM-HEO-based anode. Despite the irreversible phenomena, the HEO cubic structure remains intact for ∼60% of lithiation capacity, so proving the beneficial role of the configuration entropy in enhancing the stability of the HEO rock-salt structure during the redox phenomena.
- Published
- 2020