Origins of the DC-Resistance Increase in HCMRTM Cathodes
In this work three possible scenarios for the origin of the DC-R rise are presented:
- Evidence of Structural Transformation with Cycling and Proposed Strategies Using Lithium and Transition Metal Substitutions
In this section first-principle studies of the structural stability of Li2-xAx(Mn1-yBy)O3 and the effect of doping as well as the structure and possible structural changes of the pristine and aged HTMRTM material are discussed. Preliminary evaluations of the material suggest a single phase, aperiodic crystal consisting of monoclinic domains.
- Ionic and Electronic Barriers at Interphases and Interfaces
In situ Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR) and potentiostatic intermittent titration technique (PITT) provide information about structural changes of the surface, surface layer formation and Li+ diffusivity. Raman spectroscopy suggests transformation to a spinel like structure and FTIR spectroscopy indicates formation of a surface film composed of electrolyte decomposition products. The Li+ diffusivity in HCMRTM correlates strongly with the DC-R behavior within each cycle.
- Loss of Mechanical Integrity in HCMRTM Material - Changes in Morphology and Topology
Discussion of how changes in morphology and topology during cycling correlate with long term impedance rise and changes in the unit cell parameters of the HCMRTM material.
This work was supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technologies of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231, under the Applied Battery Research for Transportation (ABR) Program and Award Number DE-EE0006443.
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