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Surface degradation of Li1–xNi0.80Co0.15Al0.05O2 cathodes: Correlating charge transfer impedance with surface phase transformations

DOI: 10.1063/1.4954800 DOI Help

Authors: Shawn Sallis (Binghamton University) , N. Pereira (Department of Materials Science and Engineering, Rutgers University) , P. Mukherjee (Department of Materials Science and Engineering, Rutgers University) , Nicholas Quackenbush (Binghamton University) , N. Faenza (Department of Materials Science and Engineering, Rutgers University) , Christoph Schlueter (Diamond Light Source) , Tien-lin Lee (Diamond Light Source) , W. L. Yang (Advanced Light Source, Lawrence Berkeley National Laboratory) , F. Cosandey (Department of Materials Science and Engineering, Rutgers University) , G. G. Amatucci (Department of Materials Science and Engineering, Rutgers University) , Louis Piper (Binghamton University)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Applied Physics Letters , VOL 108

State: Published (Approved)
Published: June 2016
Diamond Proposal Number(s): 12764

Abstract: The pronounced capacity fade in Ni-rich layered oxide lithium ion battery cathodes observed when cycling above 4.1 V (versus Li/Li+) is associated with a rise in impedance, which is thought to be due to either bulk structural fatigue or surface reactions with the electrolyte (or combination of both). Here, we examine the surface reactions at electrochemically stressed Li1– x Ni 0.8Co0.15Al0.05O2 binder-free powder electrodes with a combination of electrochemical impedance spectroscopy, spatially resolving electron microscopy, and spatially averaging X-ray spectroscopy techniques. We circumvent issues associated with cycling by holding our electrodes at high states of charge (4.1 V, 4.5 V, and 4.75 V) for extended periods and correlate charge-transfer impedance rises observed at high voltages with surface modifications retained in the discharged state (2.7 V). The surface modifications involve significant cation migration (and disorder) along with Ni and Co reduction, and can occur even in the absence of significant Li2CO3 and LiF. These data provide evidence that surface oxygen loss at the highest levels of Li+ extraction is driving the rise in impedance.

Subject Areas: Materials


Instruments: I09-Surface and Interface Structural Analysis

Other Facilities: beamline 8.0.1 at Advanced Light Source, USA