Li-Rich Li1+xMn2鈥?i>xO4 Spinel Electrode Materials: An Operando Neutron Diffraction Study during Li+ Extraction/Insertion

详细信息    查看全文

• 作者：Matteo Bianchini ; Emmanuelle Suard ; Laurence Croguennec ; Christian Masquelier
• 刊名：Journal of Physical Chemistry C
• 出版年：2014
• 出版时间：November 13, 2014
• 年：2014
• 卷：118
• 期：45
• 页码：25947-25955
• 全文大小：727K
• ISSN：1932-7455

文摘

In situ neutron diffraction (ND) during battery operation is becoming a promising technique for the study of electrode materials in Li-ion batteries. We recently designed an electrochemical cell for operando ND studies and demonstrated that it can deliver powder patterns of good quality for Rietveld structural refinements. Herein we used such a cell to study the deintercalation process occurring in manganese spinels of general formula Li_1+xMn_2鈥?i>xO₄. Three samples with increasing Li/Mn ratio (x = 0, x = 0.05, and x = 0.10) were synthesized and measured on the D20 high-flux powder diffractometer at ILL. We found fundamental differences between the phase diagrams of the three samples, intimately related to their electrochemical features. Upon charge, the study revealed a sequence of two biphasic reactions for LiMn₂O₄ (with an intermediate phase of composition close to Li_0.6Mn₂O₄), a solid solution followed by a biphasic reaction for Li_1.05Mn_1.95O₄, and a full solid solution for Li_1.10Mn_1.90O₄. Moreover, Rietveld refinement led to key parameters such as cell parameters, oxygen鈥檚 fractional atomic coordinates, and more importantly, lithium鈥檚 site occupancy factors, whose rate of variation is found to be related to the state of charge of the electrode.