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In operando X-ray absorption spectroscopy study of charge rate effects on the atomic environment in graphene-coated Li-rich mixed oxide cathode

DOI: 10.1016/j.matdes.2016.03.028 DOI Help

Authors: Taehoon Kim (University of Oxford) , Bohang Song (University of Oxford) , Alexander J. G. Lunt (University of Oxford) , Giannantonio Cibin (Diamond Light Source) , Andrew J. Dent (Diamond Light Source Ltd) , Li Lu (National University of Singapore) , Alexander M. Korsunsky (University of Oxford)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Materials & Design , VOL 98 , PAGES 231-242

State: Published (Approved)
Published: March 2016

Abstract: Li2O extraction from the electrode material is known to be a dominant mechanism of irreversible battery capacity loss in the first cycle. The extraction mechanism of the Li+ ions shows dependence on the charge rate. Here for the first time we report the difference in the electrochemical behavior at two different charge rates (0.125 C vs 0.5 C) observed using novel design transmission coin cells in the graphene-coated Li(Li0.2Mn0.54Ni0.13Co0.13)O2 cathode by in operando X-ray absorption spectroscopy (XAS). The results obtained from Mn, Co, and Ni atom XANES/EXAFS demonstrate that, whilst during fast charge Li2O extraction is localized to the lithium slab in the crystal structure, the delithiation is deeper at the slower charge rate, when Li+ ions are removed from both the transition metal and lithium layers. In the slow charge cell, Nisingle bondO bond splitting resulting from the Jahn-Teller distortion were clearly identified at approximately 4.224 V when a sudden rise in the bond length was observed in the EXAFS analysis of Mnsingle bondO and Cosingle bondO bonds. The results demonstrate the power of using the novel cell design for transmission in operando XAS.

Journal Keywords: Lithium-ion batteries; Li-rich mixed oxide cathode; Graphene coating; In operando XAS

Subject Areas: Engineering, Materials

Technical Areas: