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: In this paper, the effect of fluorine content on the structure and electrochemical performance of LiNi0.6Co0.2Mn 0.2O2−zFz has been extensively studied.
122 citations
TL;DR: In this paper, the performance of fluorine substituted LiNiNi 0.8 Co 0.1 O 2 oxides at a relatively low temperature of 450°C was investigated.
96 citations
TL;DR: In this paper, the second-order quadrupolar splitted central transition of two inequivalent cobalt sites was analyzed and the powder patterns predominantly correspond to typical secondorder quadrrupolar split central transition.
Abstract: ${}^{59}\mathrm{Co}$ NMR studies have been performed in metallic ${\mathrm{NaCo}}_{2}{\mathrm{O}}_{4}$ in the temperature range 350--100 K. The powder patterns predominantly correspond to typical second-order quadrupolar splitted central transition of two inequivalent cobalt sites. Features of magnetic interaction are also present. The analysis of the NMR line shape shows that the electric field gradient (EFG) experienced by one of the two sites (site 1) is independent of temperature, whereas around 47% increment in EFG has been observed for site 2 as the temperature is lowered from 350 to 100 K. ${}^{59}\mathrm{Co}$ NMR shift for each site is almost isotropic in character which varies linearly with susceptibility and basically consists of two parts. Both the sites suffer a large temperature independent shift due to the contribution from orbital paramagnetism $({\ensuremath{\chi}}_{\mathrm{vv}})$ which is analogous in metals to the Van Vleck paramagnetic susceptibility. The temperature-dependent Knight shift for site 1 reveals a negative hyperfine coupling constant ${(A}_{\mathrm{hf}}^{d})$ arising from inner s core polarization by the d electrons which are itinerant in character. A positive ${A}_{\mathrm{hf}}^{d}$ observed for site 2 cannot be interpreted directly in a metallic system such as ${\mathrm{NaCo}}_{2}{\mathrm{O}}_{4}.$ A comparison of the magnitude of ${A}_{\mathrm{hf}}^{d}$ with those of other cobalt oxides suggests that the nucleus which is being probed by NMR, belongs to a diamagnetic cobalt state. Thus the present NMR results together with the susceptibility indicate the presence of ${\mathrm{Co}}^{3+}$ ion with S = 0 and the magnetic ${\mathrm{Co}}^{4+}$ ion.
89 citations
TL;DR: In this article, it was shown that the first shake-up satellite occurring on the high binding energy side of the transition-metal compounds can be attributed to 2pe g → 3de g monopole charge transfer transitions because the probability of the first allowed shakeup, 2pt 2g → 3dt 2g, is very low.
89 citations
TL;DR: In this article, the authors presented a new sodium ion intercalation material, NaxCo2/3Mn2/9Ni1/9O2, which has been synthesized by a sol-gel route in air followed by a heat treatment at 800°C for 12h.
67 citations