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
References
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TL;DR: In this article, the magnetic properties of Na 0.78 CoO 2 (0.70≤ x ≤ 0.84) samples were synthesized and characterized by X-ray diffraction analysis, inductive-coupled plasma atomic emission spectroscopy, and redox titration.
Abstract: Powder Na x CoO 2 (0.70≤ x ≤0.84) samples were synthesized and characterized carefully by X-ray diffraction analysis, inductive-coupled plasma atomic emission spectroscopy, and redox titration. It was proved that γ-Na x CoO 2 is formed only in the narrow range of 0.70≤ x ≤0.78. Nevertheless, the magnetic properties depend strongly on x . We found, for the first time, two characteristic features in the magnetic susceptibility of Na 0.78 CoO 2 , a sharp peak at T p =16 K and an anomaly at T k =9 K, as well as the transition at T c =22 K and the broad maximum at T m =50 K which had already been reported. A type of weak ferromagnetic transition seems to occur at T k . The transition at T c , which is believed to be caused by spin density wave formation, was observed clearly for x ≥0.74 with constant T c and T p independent of x . On the other hand, ferromagnetic moment varies systematically depending on x . These facts suggest the occurrence of a phase separation at the microscopic level, such as the sepa...
26 citations
TL;DR: In this article, two different Na x CoO 2−− y oxides were studied in terms of their crystal structure, sodium content, oxygen nonstoichiometry, transport properties (electrical conductivity and thermoelectric power) and electrochemical properties.
25 citations
"Effects of fluorination on the stru..." refers background in this paper
...The galvanostatic electrochemical curve of the P2 type NaxCoO2 has a complex profile: it consists of several voltage plateaus, which imply the existence of biphasic domains, potential drops that are related to stable single-phase domains, and the sloping parts that are typical of solid-solution behaviour [10,14]....
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TL;DR: In this paper, urchin-like CoO microspheres are composed of numerous nanoparticles, with a large specific surface area of 103m2−g−1.
23 citations
"Effects of fluorination on the stru..." refers background in this paper
...The presence of Co 2+ can be excluded [41]....
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TL;DR: In this article, the authors present an approach to explain the step-like character of the discharge/charge curve in LixCoO2 (monotonous curve in large range of lithium content) and NaxCoO 2−−y (step-like curve).
19 citations
TL;DR: The magnetic, thermoelectric, and structural properties of Li x Na y CoO 2, prepared by intercalation and deintercalation chemistry from the thermodynamically stable phase Li 0.41 Na 0.31 CoO2, which has an alternating Li/Na sequence along the c -axis, are reported as discussed by the authors.
19 citations