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1
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Effects of TiO_2 Source on the Electrochemical Performance of Li_4Ti_5O_{12}

100%
Kiliç Dokan F., Şahan H., Özdemır N., Özdemır B., Patat Ş.
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vol. 125
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issue 2
650-651
EN
This study examined the formation mechanism of Li_4Ti_5O_{12} by a ball mill assisted solid-state reaction between Li_2CO_3 and TiO_2 for applications in lithium ion batteries, also effects of TiO_2 source such as rutile type and anatase type on the electrochemical performance of Li_{4}Ti_5O_{12}. However, it is believed that the particle properties may depend significantly on the synthesis process and starting materials, which lead to final products with a range of sizes, morphologies, and even phases.
2
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Synthesis and Characterization of Spinel Li_4Ti_5O_{12} Anode Material by CTAB Assisted Sol-Gel Method

100%
Kiliç Dokan F., Şahan H., Özdemır B., Özdemır N., Patat Ş.
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vol. 125
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issue 2
648-649
EN
Recently, there has been considerable interest in Li_4Ti_5O_{12} as a potential anode for use in lithium ion batteries. It has many advantages compared to the currently used graphite. It has a good reversibility but no structural change. The material has a theoretical specific capacity of 175 mAh g^{-1}. Li_4Ti_5O_{12} powders are usually synthesized by a solid-state reaction of lithium and titanium salts. This method was generally preferred because the synthesis procedures are simple. But there are some disadvantages of solid-state methods such as larger particle size of the products, inhomogeneous distribution, lack of stoichiometry control, etc. These disadvantages can be overcome by sol-gel method. Using surfactant in sol-gel method is easy control on crystal growth and size of the desired products.
3
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Improvement of Cycling Stability of LiMn_2O_4 Cathode by Al_2O_3 Surface Coating for Li-Ion Batteries

100%
Şahan H., Göktepe H., Kılıç Dokan F., Aydın A., Veziroğlu S., Patat Ş.
Acta Physica Polonica A
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2013
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vol. 123
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issue 2
368-370
EN
The effect of the Al_2O_3 coating on the charge-discharge cycling performance of spinel powder (LiMn_2O_4) was investigated in the range of 3.5-4.5 V at 1C. The Al_2O_3 coating on the surface of the spinel powder was carried out using the solution method, followed by 500C for 6 h in air. Powder X-ray diffraction pattern of the Al_2O_3-coated spinel LiMn_2O_4 showed that the Al_2O_3 coating medium was not incorporated in the spinel bulk structure. Scanning electron microscopy results showed that the Al_2O_3 coating particles were homogeneously distributed on the surface of LiMn_2O_4 powder particles. The Al_2O_3-coated LiMn_2O_4 retained 92.3% of its original capacity after 30 cycles, showing much better cycle ability than the bare lithium manganese oxide. The improvement of electrochemical performance is attributed to suppression of Mn^{2+} dissolution into electrolyte via Al_2O_3 layer.
4
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The Effect of Multiple Cation (Al, Si, Ti, Co) Doping on Electrochemical Performance οf LiMn_2O_4 Cathode Active Material

100%
Kılıç Dokan F., Şahan H., Veziroğlu S., Akkuş Taş N., Aydın A., Patat Ş.
Acta Physica Polonica A
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2013
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vol. 123
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issue 2
365-367
EN
In order to improve the cycling performance of LiMn_2O_4, the spinel phases base and multiple cation doped LiMn_{1.95}Al_{0.0125}Si_{0.0125}Ti_{0.0125}Co_{0.0125}O_4, LiMn_{1.9}Al_{0.025}Si_{0.025}Ti_{0.025}Co_{0.025}O_4 spinels were synthesized by the glycine-nitrate combustion process. The structures of the products were investigated by X-ray diffraction, scanning electron microscopy and electrochemical tests.
5
Content available remote

Sol-Gel Synthesis of Nanocomposite Cu-Li₄Ti₅O_{12} Structures for Ultrahigh Rate Li-Ion Batteries

63%
Erdas A., Ozcan S., Guler M., Akbulut H.
Acta Physica Polonica A
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2015
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vol. 127
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issue 4
1026-1028
EN
In this study, spinel Li₄Ti₅O_{12} materials were successfully synthesized by a simple and facile sol-gel process and electroless copper deposition techniques. The characteristics of the as-prepared Li₄Ti₅O_{12} and Cu-Li₄Ti₅O_{12} were examined by X-ray diffraction and scanning electronic microscopy, while the electrochemical performances including charge/discharge and rate performance tests were also investigated. Cu-Li₄Ti₅O_{12} electrode demonstrated the superior initial discharge capacity and rate capability to Li₄Ti₅O_{12} electrode, cycled between 1.0 and 2.5 V. The enhanced rate capability can be attributed to the higher Li^{+} diffusivity and lower charge-transfer resistance due to the electroless deposition of copper. Moreover, when both electrodes discharged with 80 C state of discharge conditions, the reversible capacities were further increased ım70 mAh g^{-1} with excellent cycling stability and almost no irreversible capability was observed during cycling.
6
Content available remote

The Electrochemical Properties of Cu Coated LiCr_{0.2}V_{0.2}Mn_{0.6}O₂ Nanocomposites for High Rate Li-Ion Batteries

51%
Algul H., Erdas A., Tokur M., Guler M., Akbulut H., Alp A.
Acta Physica Polonica A
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2015
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vol. 127
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issue 4
1038-1041
EN
Several reported problems of commercial LiCoO₂ electrode materials such as high cost, toxicity, limited rate capability and safety concerns are still remain to be problematic to develop the lithium ion consumer electronics such as mobile phones, tablets and notebook computers. In this study, an alternative nanocomposite electrode material based on LiCr_{0.2}V_{0.2}Mn_{0.6}O₂ and copper coated one were produced via a facile sol-gel method and electroless Cu deposition techniques. The resulting samples were characterized by X-ray diffraction (Rigaku DMax 2200 diffractometer) using a monochromatized Cu-Kα source (λ=1.5406 Å) and 2θ scan range from 10° to 80° with a speed of 1° min^{-1}. The scanning electron microscope (SEM) was used in order to characterize the morphology of the active materials. The as-synthesized Cu/LiCr_{0.2}V_{0.2}Mn_{0.6}O₂ composite cathode exhibits a stable capacity on cycling and good rate capability after 50 cycles and total capacity retention of 93% is obtained. The unique 2D structure of the composite cathode material, its good electrochemical performances and its relatively low cost comparing to LiCoO₂, make this material very promising for applications.
7
Content available remote

Evaluation of Li-Air Batteries With EC-DEC Based Nanocomposite Electrolytes

51%
Akbulut A., Guler M., Cetinkaya T., Uysal M., Akbulut H.
Acta Physica Polonica A
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2015
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vol. 127
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issue 4
1023-1025
EN
Electrolytes based on organic carbonate solvents of ethylene carbonate (EC) and diethyl carbonate (DEC) were prepared by using LiPF₆ as the Li-source. Nano sized Al₂O₃ (50 nm) was used as a reinforcing component in order to control corrosion and Li₂CO₃ formation. Corrosion of the Li foil anode and electrochemical tests were performed by using EC/DEC/LiPF₆ and nanocomposite EC/DEC/LiPF₆/5wt.% Al₂O₃ electrolytes. Electrochemical tests were performed in the swagelok cells by using Li foil anode and carbon air cathode electrodes. Structural tests were carried out by using scanning electron microscopy (SEM), x-ray diffraction (XRD) and Raman spectroscopy. Results revealed that incorporation of nano Al₂O₃ leads to a decrease of corrosion rate of Li anode and a small decrease in the capacity of the air cells.
8
Content available remote

Electrical Conductivity, Viscosity and Thermal Properties of TEGDME-Based Composite Electrolytes for Lithium-Air Batteries

45%
Kartal M., Alp A., Akbulut H.
Acta Physica Polonica A
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2016
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vol. 129
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issue 4
816-818
EN
Some important properties of the electrolytes used in Li-air batteries were investigated. Electrolyte composed of a solution of 1 M LiPF₆ in tetra ethylene glycol dimethyl ether (TEGDME) was reinforced with SiO₂, Al₂O₃, poly(ethylene) oxide (PEO) and tris (pentafluorophenyl) borane (TPFPB) additives. The effects of these reinforcements on conductivity, viscosity and thermal stability were investigated. Electrical conductivity tests were carried out using a multiparameter meter. Viscosity tests were performed in a viscometer using tuning-fork vibration method. Thermal stability of the electrolytes was tested by both TG and DSC.
9
Content available remote

The Effect of Inorganic Nano Powder Additives in TEGDME for Lithium Air Batteries

45%
Kartal M., Uysal M., Cetinkaya T., Alp A., Akbulut H.
Acta Physica Polonica A
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2015
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vol. 127
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issue 4
1016-1018
EN
SiO₂ and Al₂O₃ nano fillers were added to an electrolyte composed of a solution 1 M LiPF₆ in tetra ethylene glycol dimethyl ether (TEGDME) and the effects of these nano powders on capacity and cycling performances were investigated. Galvanostatic charge/discharge (GC) measurements were performed in the assembled Li-air cells by using the nanocomposite electrolytes. The discharge capacities of these cells were cyclically tested by a battery tester at a constant current in the voltage range between 2.15 V and 4.25 V. Discharge products of nanocomposite electrolytes were characterized by SEM and XRD spectroscopies. The electrochemical results demonstrated that Al₂O₃ reinforced electrolyte showed higher discharge capacity and cyclability than those of SiO₂ reinforced electrolyte.
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