Electrochemical Evolution of the Surface and Subsurface Properties of Layered Nickel-Rich Oxide Cathodes

The limitation and degradation of the ionic and electronic transport across the positive electrode/electrolyte interface can potentially reduce the achievable capacity of Li-ion batteries.  This is evident for the layered oxides such as those based on nickel that operate outside the stability of today’s organic electrolytes.  The rise in impedance and capacity fade with cycling has been identified as a result of loss of electrical contact originating from the instability of electrode surface and decomposition of the electrolyte.  In this talk, we will discuss the surface and subsurface properties of LiNi0.8Co0.15Al0.05O2 (NCA). NCA provides a model system for correlating capacity fade with the formation and evolution of the cathode electrolyte interface with cycling.  Our studies directly compare x-ray spectroscopy, electron spectromicroscopy, and high-resolution electrochemical characterization of the same NCA electrodes as a function of both initial charging and extended cycling.   This research is supported by the Northeast Center for Chemical Energy Storage (NECCESS), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award Number DE-SC0001294.