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1
Content available remote

Electrochemical Characterization of Al^{3+} Doped Spinel Cathode Active Nanoparticles for Li-Ion Batteries

100%
Bulut E., Can M., Özacar M., Akbulut H.
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EN
Al^{3+} doped spinel structured cathode active nanoparticles were produced by microwave hydrothermal synthesis. Structural characterization of as synthesized nanoparticles was performed by X-Ray Diffraction (XRD) Spectroscopy and Scanning Electron Microscopy (SEM). Electrochemical characteristics of the material have been investigated by packaging cell material into a CR 2016 button cells. All electrochemical experiments were carried out using lithium metal foil as the counter electrode. First discharge capacitiy of doped material is 303 mAh/g at 0.1 C rate. We have obtained 69 mAh/g specific capacity and 98.7 percent capacity retention for the first cycle at 0.5 C rate.
2
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Cyclic Performance Study of Silicon/Carbon Nanotube Composite Anodes Using Electrochemical Impedance Spectroscopy

100%
Tocoglu U., Cevher O., Cetinkaya T., Guler M., Akbulut H.
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EN
Silicon based carbon nanotube composites were produced and their galvanostatic cycling properties analyzed depended on the electrochemical impedance spectroscopy. Composite anodes were produced via vacuum filtration and DC magnetron sputtering technique. Carbon nanotube papers were produced with vacuum filtration as substrate for silicon deposition and silicon was sputtered onto carbon nanotube papers via DC magnetron sputtering. Scanning electron microscopy and X-ray diffraction analysis were conducted for structural analysis of anodes. CR2016 coin cells were assembled for electrochemical tests. Electrochemical performance of anodes was tested via galvanostatic charge/discharge (100 cycles) analysis. Electrochemical impedance spectroscopy was carried out at every 25 charge/discharge cycle to determine relation between cyclic performance and electrochemical impedance of cells.
3
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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.
4
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The Effect of Calcination Temperature on the Electrochemical Performance of ZnO Coated LiMn_2O_4/MWCNT Nanocomposite Cathodes

51%
Akbulut A., Cetinkaya T., Guler M., Akbulut H.
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vol. 125
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issue 2
331-334
EN
In this study, it is aimed to develop LiMn_2O_4/MWCNT nanocomposite cathode materials by using different calcination temperatures (300, 500, 700°C). The aim of using MWCNTs in the active material is to overcome poor conductivity and to increase stability of the electrodes during charging and discharging. The nanocomposites were produced by sol-gel method, which allows producing very fine particle size of LiMn_2O_4. LiMn_2O_4 and LiMn_2O_4/MWCNT were uniformly coated on an Al-foil to obtain 500 μm thicknesses with a specific amount of binder and conducting agent. The surfaces of cathodes were coated with ZnO by using magnetron sputtering PVD with a thickness of 10 nm. Coin-type (CR2016) test cells were assembled, directly using the LiMn_2O_4/MWCNTs and surface coated LiMn_2O_4/MWCNTs as anode and a lithium metal foil as the counter electrode.
5
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The Superior Surface Discharge Capacity of Core-Shell Tinoxide/Multi Walled Carbon Nanotube Nanocomposite Anodes for Li-Ion Batteries

51%
Akbulut H., Alaf M., Gultekin D.
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vol. 125
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issue 2
335-337
EN
In this study, tin/tinoxide/multiwalled carbon nanotube (Sn/SnO_2/MWCNT) nanocomposites were produced as anode materials for Li-ion batteries by a two-step process. Metallic tin was evaporated onto free-standing MWCNT buckypapers having controlled porosity and subsequently rf plasma oxidized in Ar:O_2 (1:1) gas mixture. Besides, Sn/SnO_2 nanocomposites were produced in the same conditions onto stainless steel substrates to make a comparison. X-ray diffraction and scanning electron microscopy were used to determine the structure and morphology of the obtained nanocomposites. The discharge/charge tests, cyclic voltammetry and electrochemical impedance spectroscopy were carried out to characterize the electrochemical properties of these composites. Promising results were obtained in the tin based MWCNT nanocomposites for next-generation micro battery applications because of the high active surface area of the SnO_2/MWCNT core-shell structures.
6
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Electrochemical Performance of Pulse Electrodeposited Sn-Ni/MWCNT Composite Anode for Lithium-Ion Batteries

51%
Uysal M., Görmüş H., Karslıoğlu R., Alp A., Akbulut H.
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vol. 125
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issue 2
353-356
EN
Grain size, and MWCNT content in the electrolyte of nanocrystalline Sn-Ni/MWCNT composite deposits produced from a solution containing nickel chloride and tin chloride at constant electrodeposition conditions (pulse on-time T_{on} at 2.5 ms and pulse off-time T_{off} at 7.5 ms) but with different peak current densities were investigated. The structure of the electroplated thin film Sn-Ni/MWCNTs composite electrode is investigated by X-ray diffraction, scanning electron microscopy. Galvanostatic charge/discharge measurements were performed in the assembled CR2016 cells designed by using anode composite material produced by pulse electro co-deposition. These cells discharge capacities were cyclically tested by a battery tester at a constant current in voltage range between 0.02 and 1.5 V. The electrochemical results showed that the increase in the discharge capacity of the assembled cell was produced when compared with conventionally used graphite lithium-ion batteries.
7
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Electrochemical Performance of SnO₂ and SnO₂/MWCNT/Graphene Composite Anodes for Li-Ion Batteries

51%
Cevher O., Akbulut H.
Acta Physica Polonica A
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2017
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vol. 131
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issue 1
204-206
EN
In this study, tin oxide (SnO₂) coatings on Cr coated stainless steel and multi-walled carbon nanotube (MWCNT)/graphene substrates were prepared using a radio frequency magnetron sputtering process as anode materials in lithium-ion batteries. SnO₂ thin film and SnO₂/MWCNT/graphene composite were characterized with field-emission scanning electron microscopy, X-ray diffraction, and electrochemical tests (cyclic voltammetry and galvanostatic cycling). The electrochemical properties of SnO₂ and SnO₂/MWCNT/graphene composite anodes were studied using 2016-type coin cells assembled in an argon-filled glove box. The cells were cyclically tested on a MTI BST8-MA battery analyzer. The cyclic voltammograms of SnO₂ anode and SnO₂/MWCNT/graphene composite anode were obtained over the potential range of 0.05-3.0 V and 0.05-2.5 V at a scan rate of 0.05 mV s¯¹, respectively.
8
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Preparation and Electrochemical Performance of ZnO Films as Anode Materials for Li-Ion Batteries

51%
Cevher O., Cetinkaya T., Tocoglu U., Guler M., Akbulut H.
Acta Physica Polonica A
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2013
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vol. 123
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issue 2
355-357
EN
In this work, the effect of rf power on the structural, electrical and electrochemical properties of ZnO thin films was investigated. ZnO thin films were deposited on glass and Cr coated stainless steel substrates by rf magnetron sputtering in pure Ar gas environment. ZnO thin films for different rf powers (75, 100, and 125 W) were deposited keeping all other deposition parameters fixed. ZnO thin films were used as negative electrode materials for lithium-ion batteries, whose charge-discharge properties, cyclic voltammetry and cycle performance were examined. A high initial discharge capacity about 908 mAh g^{-1} was observed at a 0.5 C rate between 0.05 and 2.5 V. The crystallographic structure of the sample was determined by X-ray diffraction. The electrical resistivity of the deposited films was measured by the four-point-probe method. The thickness of the ZnO thin films was measured using a profilometer.
9
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Investigation of Tin Oxide Based Nanocomposites for Li-Ion Batteries

51%
Cevher O., Cetinkaya T., Tocoglu U., Guler M., Akbulut H.
Acta Physica Polonica A
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2013
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vol. 123
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issue 2
358-360
EN
In this work, tin oxide (SnO_2) films were deposited on multiwall carbon nanotube buckypaper using a rf magnetron sputter process in a mixed oxygen/argon (1/9) gas environment. Conditions for the growth of SnO_2 thin films on multiwall carbon nanotube buckypaper by rf sputtering are: target composition SnO_2 (99.999 wt%); total system pressure 1 Pa; sputtering power (rf) 75, 100 and 125 W, respectively; O_2/Ar (1/9) gas mixture. The surface morphology of the SnO_2 multiwall carbon nanotube composite films was investigated by scanning electron microscopy. The crystallographic structure of the sample was determined by X-ray diffraction. The electrochemical properties of SnO_2 multiwall carbon nanotube composite anodes were investigated by galvanostatic charge-discharge experiments.
10
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Nanostructured ATO Anodes Produced by RF Magnetron Sputtering for Li-Ion Batteries

51%
Cevher O., Tocoglu U., Akbulut H.
Acta Physica Polonica A
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2015
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vol. 127
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issue 4
1065-1067
EN
In this study, the reversible capacities, as well as the cycling behavior, of crystalline antimony-doped tin oxide (ATO) films have been investigated. ATO films were deposited on Cr-coated stainless steel substrates by the RF magnetron sputtering technique, with antimony-doped tin oxide (SnO₂:Sb) target in a mixed oxygen/argon gas environment. The ATO films were deposited for 1.0 h in a mixture of Ar and O₂ environment with O₂/Ar ratio of 10/90, at sputtering power of 75 W, 100 W and 125 W RF. ATO films were examined by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM). The electrochemical properties of ATO anodes were studied using 2016-type coin cells assembled in an argon-filled glove box.
11
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Si/Mo/MWCNT Nanocomposites for Lithium Ion Battery Applications

51%
Cetinkaya T., Uysal M., Tokur M., Kartal M., Akbulut H.
Acta Physica Polonica A
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2015
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vol. 127
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issue 4
1048-1051
EN
In this study, silicon/multi-wall carbon nanotube (Si/MWCNT) and silicon/molybdenum/multi-wall carbon nanotube (Si/Mo/MWCNT) composites were produced by high speed planetary ball milling. Produced Si/MWCNT composite containing 50 wt.% Si and 50 wt.% MWCNT and dispersingdifferent amount of molybdenum nanopowders (1 wt.%, 3 wt.% and 5 wt.%) Si/Mo/MWCNT composites were produced by high speed planetary ball milling. Surface morphology of produced composite electrodes was characterized using scanning electron microscopy (SEM) and EDS dot-map analyze was performed to investigate dispersion of MWCNT and molybdenum powders in the composite structure. X-ray diffraction (XRD) technique was carried out to investigate structure of produced Si/Mo/MWCNT composites. Electrochemical performance of the electrodes were tested between 50 mV and 1.5 V in CR2016 test cell.
12
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Raman Spectroscopy of LiFePO_4 and Li_3V_2(PO_4)_3 Prepared as Cathode Materials

51%
Ziółkowska D., Korona K., Kamińska M., Grzanka E., Andrzejczuk M., Wu S., Chen M.
Acta Physica Polonica A
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2011
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vol. 120
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issue 5
973-975
EN
Structure of samples of lithium iron vanadium phosphates of different compositions were investigated by X-rays, electron microscopy and Raman spectroscopy. The investigated salts were mainly of olivine-like and NASICON-like structures. The X-ray diffraction and the Raman scattering show different crystalline structures, which is probably caused by difference between cores of the crystallites (probed by X-rays) and their shells (probed by the Raman scattering). Most of the Raman spectra were identified with previously published data, however in the samples with high vanadium concentration we have observed new, not reported earlier modes at 835 cm^{-1} and 877 cm^{-1}, that we identified as oscillations related to V_2O_7^{4-} or VO_4^{3-} anions.
13
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Cr and V Substitution in the LiMn₂O₄Spinel Positive Electrode Li-Ion Batteries

51%
Akbulut A., Cetinkaya T., Guler M., Uysal M., Akbulut H.
Acta Physica Polonica A
|
2015
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vol. 127
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issue 4
1019-1022
EN
In this study, LiCr_{0.2}V_{0.4}Mn_{1.4}O₄ cathode active electrode materials were produced via a facile sol-gel method at 800°C. The surfaces of the LiCr_{0.2}V_{0.4}Mn_{1.4}O₄ cathode active electrode materials were then coated with Cu in order to increase the conductivity and suppress the manganese ion dissolution into the electrolyte. The structure and electrochemical properties of the obtained Cr and V substituted LiMn₂O₄ powders were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), galvanostatic charge- discharge test and electrochemical impedance spectroscopy (EIS). The improvement in the cycling performances attributed to stabilization of spinel structure by bication ion substation and Cu coating on the spinel particles. EIS analysis confirmed that bication doping and conductive Cu coating contributed stability of the spinel electrodes and provided stable electrolyte/electrode interface due to the suppression of electrolyte decomposition
14
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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.
15
Content available remote

Nanostructured Silicon Thin Film Electrodes for Li-Ion Batteries

51%
Tocoglu U., Cetinkaya T., Cevher O., Oguz Guler M., Akbulut H.
Acta Physica Polonica A
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2013
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vol. 123
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issue 2
380-382
EN
In this study we produced nanostructured silicon thin films as lithium ion battery electrodes. Films were sputtered onto stainless steel substrates from high purity silicon target via dc magnetron sputtering technique with using different powers. Morphology and crystal structure of films were characterized with the use of scanning electron microscopy, X-ray diffraction and energy dispersive spectroscopy analysis, respectively. The thickness of films was measured by using surface profiler. Coin type test cells were assembled in argon filled glove box. Electrochemical performance of cells was tested on an electrochemical analyzer using constant current densities over a voltage range of 0.2-2 V.
16
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Preparation and Characterization of Copper Powders with Sn Coating by the Electroless Plating

51%
Uysal M., Cetinkaya T., Gul H., Kartal M., Algul H., Tokur M., 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
1106-1108
EN
In this work, Sn-Cu composite powders were produced using an electroless process. The tin content on the surface of copper powders was varied by using different concentrations of SnSO₄ in the plating bath. The surface morphology of the produced Sn-Cu composite powders was characterized using scanning electron microscopy (SEM). Energy dispersive spectroscopy (EDS) was used to determine the elemental surface composition of the composites. X-ray diffraction (XRD) analysis was performed to investigate the structure of the Sn-Cu composite powders. The electrochemical performance of Sn-Cu nanocomposites was studied by charge/discharge tests.
17
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Electrochemical Performance of Silicon/MWCNT Composite Electrodes for Lithium Ion Batteries

51%
Cetinkaya T., Tocoglu U., Cevher O., Guler M., Akbulut H.
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vol. 125
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issue 2
285-287
EN
Silicon/MWCNT composite electrodes were produced using high-speed planetary ball milling. Content of MWCNT were altered in silicon/MWCNT composite electrodes and effect of MWCNT content on the electrochemical performance of silicon electrodes were characterized by scanning electron microscopy and X-ray diffraction techniques. Coin type CR2016 test cells were assembled by using produced nanocomposite electrodes. Prepared test cells were electrochemically cycled at a current density of 200 mA/g. Furthermore, cyclic voltammetry curve of composite electrodes were performed to investigate electrochemical reactions between electrode and electrolyte.
18
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Nanocomposite ZnO:MWCNT Thin Films for Li-Ion Batteries Prepared via Reactive Magnetron Sputtering

51%
Guler M., Cetinkaya T., Cevher O., Tocoglu U., Akbulut H.
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vol. 125
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issue 2
319-321
EN
In this study, ZnO/MWCNT buckypaper nanocomposite structures were obtained as an anode electrode material for Li-ion batteries. MWCNT based buckypapers were produced via vacuum filtration techniques and the surfaces of the buckypapers were coated with ZnO in order to increase stability and mechanical integrity during charging and discharging processes. The effect of deposition powers on the battery performance is also investigated.
19
Content available remote

Thin Film Nanostructured ATO and ATO Based Composite Anodes for Li-Ion Batteries

51%
Cevher O., Guler M., Tocoglu U., Cetinkaya T., Akbulut H., Okumus S.
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vol. 125
|
issue 2
296-298
EN
In this study, antimony doped tin oxide films were deposited on multiwall carbon nanotube buckypaper and Cr coated stainless steel substrates using a radio frequency magnetron sputtering process in a mixed oxygen/argon (5/95) gas environment. The depositions of antimony doped tin oxide on the multiwall carbon nanotube buckypaper and stainless steel substrates were carried out using the parameters organized as: target composition antimony doped tin oxide (SnO_2:Sb = 90:10 wt%); total system pressure 1 Pa; sputtering power (RF) 100 W. The surface morphology of the antimony doped tin oxide films was investigated by field emission scanning electron microscopy. The crystallographic structure of the samples was determined by X-ray diffraction. The electrochemical properties of antimony doped tin oxide and antimony doped tin oxide-multiwall carbon nanotube nanocomposite anodes containing CR2016 cells were measured by galvanostatic charge-discharge experiments.
20
Content available remote

Sol-Gel Synthesis of Nanostructured SnO_2 Thin Film Anodes for Li-Ion Batteries

45%
Köse H., Aydin A., Akbulut H.
Acta Physica Polonica A
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2012
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vol. 121
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issue 1
227-229
EN
Sol-gel technique was employed to prepare semiconductor tin dioxide (SnO_2) thin films. Comparatively, it gives an advantage over other techniques by its low reaction temperature, easy process and low cost. The effect of glycerin addition on the structure and preventing crack formation has been investigated. Scanning electron microscopy, atomic force microscopy, and X-ray diffraction analysis were performed to characterize nanostructured films.
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