Effects of fluorination on the structure, magnetic and electrochemical properties of the P2-type NaxCoO2 powder
TL;DR: In this article, the effects of fluorination on the crystal structure, magnetic, and electrochemical properties of the P2-type NaxCoO2 powder were investigated for the first time.
About: This article is published in Journal of Alloys and Compounds.The article was published on 2019-02-05 and is currently open access. It has received 15 citations till now. The article focuses on the topics: Rietveld refinement & Fluorine.
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28,685 citations
TL;DR: In this paper, the structural, magnetic, transport, and electronic properties of LaCoO3 with Sr/Nb cosubstitution were studied using X-ray and neutron diffraction, dc-and ac-magnetiza...
Abstract: We study the structural, magnetic, transport, and electronic properties of LaCoO3 with Sr/Nb cosubstitution, i.e., La(1–2x)Sr2xCo(1–x)NbxO3 using X-ray and neutron diffraction, dc- and ac-magnetiza...
20 citations
TL;DR: In this paper, a review of the recent advances in sample digestion methods, especially on open-vessel acid digestion, microwave digestion, alkali fusion, high-pressure asher, and sample preparation methods for laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) analysis, is presented.
20 citations
TL;DR: In this paper, the authors used molybdenum doping strategy to synthesize P2-type Na0.59Co0.20Mn 0.77Mo0.03O2 material with a hexagonal layer structure as the cathode of sodium-ion batteries through a solid-state reaction route.
Abstract: Layered P2-type Mn-based material is considered as one of the most promising cathode materials for sodium-ion batteries, but its unsatisfactory cyclic performance is one of the problems that need to be overcome. Here, we used molybdenum doping strategy to synthesize P2-type Na0.59Co0.20Mn0.77Mo0.03O2 material with a hexagonal layer structure as the cathode of sodium-ion batteries through a solid-state reaction route. The maximum discharge capacity of the Mo-doped cathode is 131.9 mAh g−1 with the capacity retention rate of 91.51% after 100 cycles at 0.1 C (1 C = 156 mAh g−1). Optimized Mo doping effectively decreases the charge transfer resistance and the interface resistance of the Na0.59Co0.20Mn0.80O2 cathode at open circuit and after 100 cycles, respectively, and the growth trends of the charge transfer resistance and the interface resistance are obviously slowed down, which is proved that the cycling stability of the pristine cathode is significantly improved by Mo doping. The main reasons are as follows: (1) Mo doping expands the a-axis and shortens the TM–O bond, which enhances the structural stability of the P2-type oxide; (2) Mo doping increases the crystallinity of the pristine and decreases the degree of cation disorder in the P2-type oxide; (3) the bond energy of Mo–O is stronger than that of Mn–O and Co–O, resulting in a more stable structure of the material. The results provide a meaningful reference for improving the cycle stability and kinetic performance of P2-type cathode materials for sodium-ion batteries.
12 citations
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TL;DR: The results of measurements of the dc-magnetic susceptibility and the NMR response of the Co ion at temperatures between 50 and 340 K were presented in this article. But no evidence for magnetic phase transitions was found in the dc magnetometer data.
Abstract: We present the results of measurements of the dc-magnetic susceptibility $\ensuremath{\chi}(T)$ and the ${}^{23}\mathrm{Na}$-NMR response of ${\mathrm{Na}}_{0.70}{\mathrm{CoO}}_{2}$ at temperatures between 50 and 340 K. The $\ensuremath{\chi}(T)$ data suggest that for $Tg75\mathrm{K},$ the Co ions adopt an effective configuration of ${\mathrm{Co}}^{3.4+}.$ The ${}^{23}\mathrm{Na}$-NMR response reveals pronounced anomalies near 250 and 295 K, but no evidence for magnetic phase transitions is found in $\ensuremath{\chi}(T).$ Our data suggest the onset of a dramatic change in the Co $3d$-electron spin dynamics at 295 K. This process is completed at 230 K. Our results may be interpreted as evidence for either a tendency to electron localization or an unconventional charge-density-wave phenomenon within the Co $3d$ electron system near room temperature.
57 citations
TL;DR: X-ray photoelectron spectroscopy has been used to investigate the lithium deintercalation and the lithium intercalation processes, respectively, in LiCoO 2 and in MO 3 compounds (M=W, Mo) as discussed by the authors.
54 citations
"Effects of fluorination on the stru..." refers background in this paper
...4 eV) is ascribed to Co 4+ ions, which is less commonly presented in the literature [39,40]....
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TL;DR: In this article, LiNi0.8Co0.1Mn 0.1O2 oxides have been synthesized by hydroxide co-precipitation method.
51 citations