Al2O3, SiO2 and TiO2 as coatings for safer LiNi0. 8Co0. 15Al0. 05O2 cathodes: electrochemical performance and thermal analysis by accelerating rate calorimetry

S Hildebrand, C Vollmer, M Winter… - Journal of The …, 2017 - iopscience.iop.org
S Hildebrand, C Vollmer, M Winter, FM Schappacher
Journal of The Electrochemical Society, 2017iopscience.iop.org
Abstract Al 2 O 3, SiO 2 and TiO 2 were coated on LiNi 0.8 Co 0.15 Al 0.05 O 2 (NCA) in
varying amounts and investigated regarding their influence on thermal stability and
electrochemical performance. The presence of the coating on the surface was confirmed by
Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). Al 2 O 3
showed agglomerated nano-scaled particles. SiO 2 was coated homogeneously. TiO 2
showed loose nano-scaled particles on the surface. The coated materials showed a …
Abstract
Al 2 O 3, SiO 2 and TiO 2 were coated on LiNi 0.8 Co 0.15 Al 0.05 O 2 (NCA) in varying amounts and investigated regarding their influence on thermal stability and electrochemical performance. The presence of the coating on the surface was confirmed by Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). Al 2 O 3 showed agglomerated nano-scaled particles. SiO 2 was coated homogeneously. TiO 2 showed loose nano-scaled particles on the surface. The coated materials showed a decrease in capacity of≈ 10 mAh g− 1 with slightly higher cycling stability compared to the pristine NCA. Accelerating Rate Calorimetry (ARC) of the delithiated materials was conducted with 1 M LiPF 6 in ethylene carbonate (EC): diethyl carbonate (DEC) 3: 7 (by weight)+ 2 wt% vinylene carbonate (VC)+ 0.5 wt% lithium bis (oxalate) borate (LiBOB). The TiO 2 coating resulted in an increase of the onset temperature of thermal runaway (T dT/dt> 0.2 K/min) of 5 C. Coatings with Al 2 O 3 and SiO 2 led to a significant increase of T dT/dt> 0.2 K/min of up to 10 and 11 C, respectively. The coatings are able to lower the extent of reaction between the highly reactive oxygen evolving from the charged cathode at higher temperatures and the organic solvent-based electrolyte.
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