Journal
ENERGY & ENVIRONMENTAL SCIENCE
Volume 7, Issue 9, Pages 3077-3085Publisher
ROYAL SOC CHEMISTRY
DOI: 10.1039/c4ee01400f
Keywords
-
Funding
- Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technologies of the U.S. Department of Energy [DE-AC02- 05CH11231]
- U.S. Department of Energy, Office of Basic Energy Sciences [DE-AC02-98CH10886]
- National Center for Electron Microscopy (NCEM) of the Lawrence Berkeley National Laboratory (LBNL)
- U.S. Department of Energy (DOE) [DE-AC02-05CH11231]
Ask authors/readers for more resources
Chemical and structural evolution in battery materials influences properties relevant to ionic and electronic transport and ultimately impacts the battery performance. Although chemical and structural gradients have been observed in several cathode materials, the origin(s) of these phenomena are poorly understood. Via high-throughput core-level spectroscopies {i.e., X-ray absorption spectroscopy (XAS), depth-profiled X-ray photoelectron spectroscopy (XPS) and electron energy loss spectroscopy (EELS)}, as well as scanning transmission electron microscopy (STEM), the present study seeks to achieve mechanistic understanding for these phenomena in a stoichiometric R (3) over barm layered cathode material (e.g., LiNixMnxCo1-2xO2, NMC). We observed that the surfaces of particles in the composite electrode are complicated by the presence of a surface reaction layer resulting from electrolyte decomposition. In large particle ensembles, the global nickel oxidation state switches between Ni2+ and Ni2+x (x = 1-2) during charging/discharging processes, and hole states are also created at the O2p level due to the TM3d-O2p hybridization states. In primary particles, the surface is less oxidized than the bulk counterpart of the same particle whenever the particle has been cycled. This is partially attributed to the reconstruction from an R (3) over barm structure to an Fm (3) over barm structure at the surfaces of NMC particles. This work provides a unique insight into correlating crystal structures with charge compensation mechanisms and performance fading in stoichiometric layered cathode materials.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available