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Title: Understanding local degradation of cycled Ni-rich cathode materials at high operating temperature for Li-ion batteries

We utilize transmission electron microscopy in conjunction with electron energy loss spectroscopy to investigate local degradation that occurs in Li{sub x}Ni{sub 0.8}Co{sub 0.15}Al{sub 0.05}O{sub 2} cathode materials (NCA) after 30 cycles with cutoff voltages of 4.3 V and 4.8 V at 55 °C. NCA has a homogeneous crystallographic structure before electrochemical reactions; however, we observed that 30 cycles of charge/discharge reactions induced inhomogeneity in the crystallographic and electronic structures and also introduced porosity particularly at surface area. These changes were more noticeable in samples cycled with higher cutoff voltage of 4.8 V. Effect of operating temperature was further examined by comparing electronic structures of oxygen of the NCA particles cycled at both room temperature and 55 °C. The working temperature has a greater impact on the NCA cathode materials at a cutoff voltage of 4.3 V that is the practical the upper limit voltage in most applications, while a cutoff voltage of 4.8 V is high enough to cause surface degradation even at room temperature.
Authors:
; ; ;  [1]
  1. Center for Energy Convergence, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of)
Publication Date:
OSTI Identifier:
22310857
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 105; Journal Issue: 10; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ALUMINIUM COMPOUNDS; CATHODES; COBALT COMPOUNDS; CRYSTALLOGRAPHY; ELECTRIC BATTERIES; ELECTRIC POTENTIAL; ELECTROCHEMISTRY; ELECTRONIC STRUCTURE; ENERGY-LOSS SPECTROSCOPY; LITHIUM COMPOUNDS; LITHIUM IONS; NICKEL COMPOUNDS; OXYGEN COMPOUNDS; SURFACE AREA; SURFACES; TEMPERATURE RANGE 0273-0400 K; THERMAL DEGRADATION; TRANSMISSION ELECTRON MICROSCOPY