Undesired reactions between layered sodium transition-metal oxide cathodes and air impede their utilization in practical sodium-ion batteries. Consequently, a fundamental understanding of how layered oxide cathodes degrade in air is of paramount importance, but it has not been fully understood yet. Here a comprehensive study on a model material NaNiMnCoO reveals its reaction chemistry with air and the dynamic evolution of the degradation species upon air exposure. We find that besides the extraction of Na ions from the crystal lattice to form NaOH, NaCO, and NaCO·HO in contact with air, nickel ions gradually dissolve from the bulk to form NiO and accumulate on the particle surface as revealed by subnanometer surface-sensitive time-of-flight secondary ion mass spectroscopy. The degradation species on the surface are insulating, leading to an increase in interfacial resistance and declined electrochemical performance. We also demonstrate a feasible surface coating strategy for suppressing the unfavorable degradation process. Understanding the degradation mechanism at a nanoscale can facilitate the future development of high-energy cathodes for sodium-ion batteries.
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http://dx.doi.org/10.1021/acs.nanolett.8b03637 | DOI Listing |
ACS Appl Mater Interfaces
January 2025
Research Center of Resource Chemistry and Energy Materials, Key Laboratory of Clay Mineral of Gansu, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, P.R. China.
Clay minerals show significant potential as fillers in polymer composite solid electrolytes (CSEs), whereas the influence of their microstructures on lithium-ion (Li) transport properties remains insufficiently understood. Herein, we design advanced poly(ethylene oxide) (PEO)-based CSEs incorporating clay minerals with diverse microstructures including 1D halloysite nanotubes, 2D Laponite (Lap) nanosheets, and 3D porous diatomite. These minerals form distinct Li transport pathways at the clay-PEO interfaces due to their varied structural configurations.
View Article and Find Full Text PDFMaterials (Basel)
January 2025
College of Physics and Electronic Information, Shandong Key Laboratory of Biophysics, Dezhou University, Dezhou 253023, China.
Electrochromic capacitors, which are capable of altering their appearances in line with their charged states, are drawing substantial attention from both academia and industry. Tungsten oxide is usually used as an electrochromic layer material for electrochromic devices, or as an active material for high-performance capacitor electrodes. Despite this, acceptable visual aesthetics in electrochromic capacitors have almost never been achieved using tungsten oxide, because, in its pure form, this compound only displays a onefold color modulation from transparent to blue.
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December 2024
Faculty of Chemistry, University of Warsaw, Pasteura 1, 02-093 Warsaw, Poland.
Cyclic voltammetry (CV) can be applied as a reliable method for the determination of chloride ions in a range from several to a couple hundred (about 200) ppm. Since the standard potential of chloride ion/gaseous chlorine is 1.36 V vs.
View Article and Find Full Text PDFMaterials (Basel)
December 2024
Department of Mechatronic Engineering, Guangdong Polytechnic Normal University, Guangzhou 510665, China.
Molecules
December 2024
College of Mechanical and Electronic Engineering, Tarim University, Alar 843300, China.
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