Surface degradation of Li1–xNi0.80Co0.15Al0.05O2 cathodes: Correlating charge transfer impedance with surface phase transformations
- Binghamton Univ., NY (United States)
- Rutgers Univ., New Brunswick, NJ (United States)
- Science and Technology Facilities Council (STFC), Oxford (United Kingdom). Diamond Light Source, Ltd.
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Advanced Light Source (ALS)
The pronounced capacity fade in Ni-rich layered oxide lithium ion battery cathodes observed when cycling above 4.1V (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–xNi0.8Co0.15Al0.05O2 binderfree 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 (4.1V, 4.5V, and 4.75V) 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.
- Research Organization:
- Energy Frontier Research Centers (EFRC) (United States). Northeastern Center for Chemical Energy Storage (NECCES)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES)
- Grant/Contract Number:
- SC0001294; AC02-05CH11231; SC0012583
- OSTI ID:
- 1388017
- Alternate ID(s):
- OSTI ID: 1259367
- Journal Information:
- Applied Physics Letters, Vol. 108, Issue 26; Related Information: NECCES partners with Stony Brook University (lead); Argonne National Laboratory; Binghamton University; Brookhaven National University; University of California, San Diego; University of Cambridge, UK; Lawrence Berkeley National Laboratory; Massachusetts Institute of Technology; University of Michigan; Rutgers University; ISSN 0003-6951
- Publisher:
- American Institute of Physics (AIP)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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