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Origins of the DC-Resistance Increase in HCMRTM Cathodes

Monday, October 12, 2015: 15:40
105-A (Phoenix Convention Center)
R. Kostecki (Lawrence Berkeley National Laboratory), V. Battaglia (Lawrence Berkeley National Laboratory), G. Chen (Energy Storage and Distributed Resources Division, LBNL), W. Chen, G. Liu (Lawrence Berkeley National Laboratory), D. Membreno (LBNL), K. A. Persson (Joint Center for Energy Storage Research (JCESR)), A. K. Shukla (Energy Storage and Distributed Resources Division, LBNL), L. Terborg (Lawrence Berkeley National Laboratory), and T. Yi (LBNL)
High capacity manganese rich (HCMR™) materials are promising candidates for commercial Li-ion battery positive electrodes for applications in electric and plug-in hybrid electric vehicles.1 These oxides, also denoted as xLiMO2 - (1-x)LiMnO3 (M = Co, Mn, Ni), deliver a high discharge capacity (>240 mAh/g) at operating voltages exceeding 3.5 V vs. Li/Li+.2 However, these materials have significant limitations and suffer from high first cycle irreversible capacity loss, impedance rise and voltage fade during cycling.2-4 Extensive studies of HCMR™ electrodes indicated a structural modification/ rearrangement as one of the major reasons for the electrode/material degradation.

In this work three possible scenarios for the origin of the DC-R rise are presented:

  1. 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.
  2. 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.

  1. 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.

Acknowledgements

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.

References

1.  M. M. Thackeray, S. H. Kang, C. S. Johnson, J. T. Vaughey, R. Benedek and S. A. Hackney, J Mater Chem, 17, 3112 (2007).

2.  Y. Li, M. Bettge, B. Polzin, Y. Zhu, M. Balasubramanian and D. P. Abraham, J. Electrochem. Soc., 160, A3006 (2013).

3.  K. J. Carroll, D. Qian, C. Fell, S. Calvin, G. M. Veith, M. F. Chi, L. Baggetto and Y. S. Meng, Phys Chem Chem Phys, 15, 11128 (2013).

4.  D. Mohanty, A. S. Sefat, S. Kalnaus, J. L. Li, R. A. Meisner, E. A. Payzant, D. P. Abraham, D. L. Wood and C. Daniel, J Mater Chem A, 1, 6249 (2013).

See more of: Cathode I
See more of: A06: High-Energy Li-Ion Intercalation Materials
See more of: Batteries and Energy Storage
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