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Evolution of the electrode-electrolyte interface of LiNi 0.8 Co 0.15 Al 0.05 O 2 electrodes due to electrochemical and thermal stress

DOI: 10.1021/acs.chemmater.7b04782 DOI Help

Authors: Zachary W. Lebens-higgins (Binghamton University) , Shawn Sallis (Binghamton University) , Nicholas V. Faenza (Rutgers University) , Fadwa Badway (Rutgers University) , Nathalie Pereira (Rutgers University) , David M. Halat (University of Cambridge) , Matthew Wahila (Binghamton University) , Christoph Schlueter (Diamond Light Source; Deutsches Elektronen-Synchrotron) , Tien-lin Lee (Diamond Light Source) , Wanli Yang (Advanced Light Source) , Clare P. Grey (University of Cambridge) , Glenn G. Amatucci (Rutgers University) , Louis F. J. Piper (Binghamton University)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Chemistry Of Materials

State: Published (Approved)
Published: January 2018
Diamond Proposal Number(s): 12764 , 16005

Abstract: For layered oxide cathodes, impedance growth and capacity fade related to reactions at the cathode-electrolyte interface (CEI) are particularly prevalent at high voltage and high temperatures. At a minimum, the CEI layer consists of Li2CO3, LiF, reduced (relative to the bulk) metal-ion species, and salt decomposition species but conflicting reports exist regarding their progression during (dis)charging. Utilizing transport measurements in combination with x-ray and nuclear magnetic resonance spectroscopy techniques, we study the evolution of these CEI species as a function of electrochemical and thermal stress for LiNi0.8Co0.15Al0.05O2 (NCA) particle electrodes using a LiPF6 ethylene carbonate: dimethyl carbonate (1:1 volume ratio) electrolyte. Although initial surface metal reduction does correlate with surface Li2CO3 and LiF, these species are found to decompose upon charging and are absent above 4.25 V. While there is trace LiPF6 breakdown at room temperature above 4.25 V, thermal aggravation is found to strongly promote salt breakdown and contributes to surface degradation even at lower voltages (4.1 V). An interesting finding of our work was the partial reformation of LiF upon discharge which warrants further consideration for understanding CEI stability during cycling.

Subject Areas: Chemistry, Materials


Instruments: I09-Surface and Interface Structural Analysis

Other Facilities: ALS