Evolution of the Electrode–Electrolyte Interface of LiNi0.8Co0.15Al0.05O2 Electrodes Due to Electrochemical and Thermal Stress
- Binghamton Univ., NY (United States)
- Rutgers Univ., New Brunswick, NJ (United States)
- Univ. of Cambridge (United Kingdom)
- Science and Technology Facilities Council (STFC), Oxford (United Kingdom). Diamond Light Source, Ltd.; Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)
- 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)
For layered oxide cathodes, impedance growth and capacity fade related to reactions at the cathode–electrolyte interface (CEI) are particularly prevalent at high voltage and high temperatures. At a minimum, the CEI layer consists of Li2CO3, LiF, reduced (relative to the bulk) metal-ion species, and salt decomposition species, but conflicting reports exist regarding their progression during (dis)charging. Utilizing transport measurements in combination with X-ray and nuclear magnetic resonance spectroscopy techniques in our work, we study the evolution of these CEI species as a function of electrochemical and thermal stress for LiNi0.8Co0.15Al0.05O2 (NCA) particle electrodes using a LiPF6 ethylene carbonate:dimethyl carbonate (1:1 volume ratio) electrolyte. Although initial surface metal reduction does correlate with surface Li2CO3 and LiF, these species are found to decompose upon charging and are absent above 4.25 V. While there is trace LiPF6 breakdown at room temperature above 4.25 V, thermal aggravation is found to strongly promote salt breakdown and contributes to surface degradation even at lower voltages (4.1 V). An interesting finding of our work was the partial reformation of LiF upon discharge, which warrants further consideration for understanding CEI stability during cycling.
- Research Organization:
- Energy Frontier Research Centers (EFRC) (United States). Northeastern Center for Chemical Energy Storage (NECCES); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States). Advanced Light Source (ALS); Science and Technology Facilities Council (STFC), Oxford (United Kingdom). Diamond Light Source, Ltd.
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES). Scientific User Facilities Division
- Grant/Contract Number:
- SC0001294; SC0012583; AC02-05CH11231; SI12764; SI16005
- OSTI ID:
- 1470192
- Journal Information:
- Chemistry of Materials, Vol. 30, Issue 3; 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 0897-4756
- Publisher:
- American Chemical Society (ACS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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