Real Time Characterization of the Surface Degradation and Thermal Stability of Charged Ni-based Cathode Materials for Li-Ion Batteries

Title
Real Time Characterization of the Surface Degradation and Thermal Stability of Charged Ni-based Cathode Materials for Li-Ion Batteries
Authors
황수연김세영김승민조병원정경윤이정용Eric A. Stach장원영
Keywords
Surface degradation; thermal stability; cathode; Li-ion batteries; TEM
Issue Date
2014-11
Publisher
2014 MRS Fall Meeting
Abstract
Li-ion batteries (LIBs) have been widely utilized as the power sources in numerous applications from small portable devices to large-scale transportation systems such as various forms of electric vehicles (EVs). The development of new electrode materials with higher capacity, higher power, longer cycle life, and especially lower cost and better safety characteristics is required for the next generation of LIBs for EV applications. Because of their higher energy density, less toxicity, and lower cost compared to LiCoO2, Ni-based layered cathode materials are being considered as one of the prime candidates for alternative cathode materials. Despite these advantages, the thermal instability of Ni-rich materials is the largest hurdle that must be overcome before their widespread usage. In this research, we take advantage of real time electron microscopy to directly investigate the process of thermal decomposition as it occurs at the surface of LixNi0.8Co0.15Al0.05O2 (NCA) and LixNiyMnzCo1-y-zO2 (NMC) cathode materials that have been charged to different state of charge (SOC). Previous studies using x-ray based techniques, such as x-ray diffraction (XRD) and x-ray absorption spectroscopy (XAS), have concluded that the substantial safety issues associated with Ni-rich materials are closely related to the existence of a structural instability. There have been quite a number of studies that have investigated the evolution of the average crystallographic structure of the cathode materials as a function of either temperature or degree of delithiation. However, because the degradation of electrode materials and the initiation of thermal runaway may start very locally within electrode materials, a complementary method is required to elucidate where and how these phenomena start and propagate at the nanoscale. Transmission electron microscopy (TEM) combined with electron energy loss spectroscopy (EELS) allowed us to gain informa
URI
http://pubs.kist.re.kr/handle/201004/49468
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KIST Publication > Conference Paper
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