scholarly journals Highly Conducting Li(Fe1−xMnx)0.88V0.08PO4 Cathode Materials Nanocrystallized from the Glassy State (x = 0.25, 0.5, 0.75)

Materials ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6434
Author(s):  
Justyna E. Frąckiewicz ◽  
Tomasz K. Pietrzak

This study showed that thermal nanocrystallization of glassy analogs of LiFe1−xMnxPO4 (with the addition of vanadium for improvement of glass forming properties) resulted in highly conducting materials that may be used as cathodes for Li-ion batteries. The glasses and nanomaterials were studied with differential thermal analysis, X-ray diffractometry, and impedance spectroscopy. The electrical conductivity of the nanocrystalline samples varied, depending on the composition. For x=0.5, it exceeded 10−3 S/cm at room temperature with an activation energy as low as 0.15 eV. The giant and irreversible increase in the conductivity was explained on the basis of Mott’s theory of electron hopping and a core-shell concept. Electrochemical performance of the active material with x=0.5 was also reported.

2019 ◽  
Vol 11 (34) ◽  
pp. 30719-30727 ◽  
Author(s):  
Selvamani Vadivel ◽  
Nutthaphon Phattharasupakun ◽  
Juthaporn Wutthiprom ◽  
Salatan duangdangchote ◽  
Montree Sawangphruk

2011 ◽  
Vol 347-353 ◽  
pp. 3662-3665 ◽  
Author(s):  
Yu Hui Wang ◽  
Zhe Li ◽  
Kai Zhu ◽  
Gang Li ◽  
Ying Jin Wei ◽  
...  

The Li[Li0.2Co0.4Mn0.4]O2 cathode material was prepared by a sol-gel method. Combinative X-ray diffraction (XRD) studies showed that the material was a solid solution of LiCoO2 and Li2MnO3. The material showed a reversible discharge capacity of 155.0 mAhg−1 at -20 °C, which is smaller than that at room temperature (245.5 mAhg−1). However, the sample exhibited capacity retention of 96.3 % at -20 °C, only 74.2 % at 25 °C. The good electrochemical cycle performance at low temperature was due to the inexistence of Mn3+ in the material.


1993 ◽  
Vol 321 ◽  
Author(s):  
Sunil V. Gokhale ◽  
Krassimir G. Marchev ◽  
Welville B. Nowak ◽  
Bill C. Giessen

ABSTRACTThere are no reported gold-rich alloys that are both readily glass forming (RGF) upon rapid solidification processing (RSP) and, in the glassy state, have crystallization temperatures Tc sufficiently high to insure long metastable life times at room temperature. A representative of a new family of ternary gold-based glasses is described that contain Cu and a rare earth (RE) Metal (or Y), with total addition element concentrations as low as 15 at. pet., and its crystallization characteristics are reported. Under RSP processing by arc furnace hammer-and-anvil quenching, the alloy Au0.80Cu0.10Y0.10 readily forms a ductile glass, with Tc = 685 K, ΔHc = 1.25 kJ/g-Mole and an activation energy of crystallization ΔE3 (cryst.) = 190 kJ/g-Mole.


2020 ◽  
Vol MA2020-01 (2) ◽  
pp. 381-381
Author(s):  
Cédric Haon ◽  
Antoine Desues ◽  
Nathalie Herlin ◽  
Florent Boismain ◽  
Pierre-Eugène Coulon ◽  
...  

RSC Advances ◽  
2017 ◽  
Vol 7 (5) ◽  
pp. 2407-2414 ◽  
Author(s):  
Dan Shao ◽  
Inna Smolianova ◽  
Daoping Tang ◽  
Lingzhi Zhang

Novel core–shell structured Si/S-doped carbon composite with buffering voids prepared by hydrothermal method and followed by carbonization and removal of template layer, exhibiting a reversible capacity of 664 mA h g−1 over 300 cycles.


2014 ◽  
Vol 70 (a1) ◽  
pp. C1101-C1101
Author(s):  
Laurent Castro ◽  
Nicolas Penin ◽  
Dany Carlier ◽  
Alain Wattiaux ◽  
Stanislav Pechev ◽  
...  

Iron vanadates and phosphates have been widely explored [1-2] as possible electrode material for Li-ion batteries. In the goal of finding new materials, our approach was to consider existing materials and to investigate the flexibility of their network for possible substitutions. Among the different materials containing iron and vanadium, Cu3Fe4(XO4)6 (X = P, V) are isostructural to Fe7(PO4)6. Lafontaine et al. [3] discussed the structural relationships between β-Cu3Fe4(VO4)6 and several other vanadates, phosphates and molybdates of general formula AxBy(VO4)6. The interesting network flexibility was then demonstrated with the existence of four different crystallographic sites, which can be partially occupied depending on the x+y value : x+y = 7 for β-Cu3Fe4(VO4)6) and x+y = 8 for NaCuFe2(VO4)3. The LixFey(VO4)6 phase was then prepared considering the substitution of Li+ and Fe3+ for Cu2+ ions in β-Cu3Fe4(VO4)6 and the existence of an extra site to accommodate the charge compensation (7 ≤ x+y ≤ 8). As expected, a new lithium iron vanadate, isotructural to mineral Howardevansite was then obtained. Single crystal diffraction data were collected at room temperature on Enraf-Nonius CAD-4 diffractometer. Structure was refined with JANA-2006 program package. Mössbauer and magnetic measurements were also used to check the oxidation state of iron ions, to support the obtained crystal structure and to consider any possible structural/magnetic transitions. All the results will be presented and discussed in this presentation.


Molecules ◽  
2021 ◽  
Vol 26 (15) ◽  
pp. 4531
Author(s):  
Mihaela-Ramona Buga ◽  
Adnana Alina Spinu-Zaulet ◽  
Cosmin Giorgian Ungureanu ◽  
Raul-Augustin Mitran ◽  
Eugeniu Vasile ◽  
...  

Porous silica-based materials are a promising alternative to graphite anodes for Li-ion batteries due to their high theoretical capacity, low discharge potential similar to pure silicon, superior cycling stability compared to silicon, abundance, and environmental friendliness. However, several challenges prevent the practical application of silica anodes, such as low coulombic efficiency and irreversible capacity losses during cycling. The main strategy to tackle the challenges of silica as an anode material has been developed to prepare carbon-coated SiO2 composites by carbonization in argon atmosphere. A facile and eco-friendly method of preparing carbon-coated SiO2 composites using sucrose is reported herein. The carbon-coated SiO2 composites were characterized using X-ray diffraction, X-ray photoelectron spectroscopy, thermogravimetry, transmission and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy, cyclic voltammetry, and charge–discharge cycling. A C/SiO2-0.085 M calendered electrode displays the best cycling stability, capacity of 714.3 mAh·g−1, and coulombic efficiency as well as the lowest charge transfer resistance over 200 cycles without electrode degradation. The electrochemical performance improvement could be attributed to the positive effect of the carbon thin layer that can effectively diminish interfacial impedance.


Author(s):  
Partha P. Paul ◽  
Chuntian Cao ◽  
Vivek Thampy ◽  
Hans-Georg Steinrück ◽  
Tanvir R. Tanim ◽  
...  

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