moniq25's Posts

Improved electrochemical performance of LiMn2O4 cathode material by Ce doping

Posted by moniq25 on May 1, 2018 at 10:20pm

M. Michalska, D.A Ziółkowska, J.B. Jasiński, P.-H. Lee, P. Ławniczak, B. Andrzejewski, A. Ostrowski, W. Bednarski, S.-H. Wu, J.-Y. Lin

Abstract

Lithium manganese oxide nanopowders doped with Ce ions are synthesized using modified sol-gel method and the effect of annealing atmosphere (air vs. nitrogen) on the structure, morphology, and phase composition is studied thoroughly. Electrochemical testing is conducted to evaluate the effect of annealing atmosphere on electrochemical performance. The X-ray diffraction indicates the cubic spinel structure for all the obtained samples. The lattice parameter is observed to slightly decrease with increasing concentration of Ce³⁺ ions substituting Mn³⁺ions from 8.230 to 8.228 Ẵ and from 8.227 to 8.224 Ẵ for air annealing and for nitrogen-air annealing, respectively. A limited solubility of cerium in LiMn₂O₄ is also observed, as small amounts of cerium dioxide is detected on the surface of LiMn_2-xCe_xO₄ grains and confirmed by XPS analysis of cerium which shows only the spectrum of Ce⁴⁺ ions. Electrochemical testing is conducted to evaluate the effect of annealing atmosphere on electrochemical performance. It is shown that annealing in nitrogen and then in air results in excellent capacity retention with minimal, 4–8% capacity loss after 150 cycles. LiMn_1.99Ce_0.01O₄ samples prepared that way display better high rate performance in comparison with pristine LiMn₂O₄.

Electrochimica Acta 276 (2018) 37-46.

doi.org/10.1016/j.electacta.2018.04.165

https://www.sciencedirect.com/science/article/pii/S0013468618309344

Analysis of the surface decoration of TiO2 grains using silver nanoparticles obtained by ultrasonochemical synthesis towards organic photovoltaics

Posted by moniq25 on May 1, 2018 at 5:45pm

Monika Michalska, Agnieszka Iwan, Mariusz Andrzejczuk, Agata Roguska, Andrzej Sikora, Bartosz Boharewicz, Igor Tazbir, Agnieszka Hreniak, Sebastian Popłoński and Krzysztof P. Korona

Abstract

In this article, we present a wet ultrasonochemical synthesis of nanocrystalline TiO₂ powders in the anatase form in ethanol solution and their surface decoration using uniformly dispersed Ag metallic nanoparticles of about 4 nm at concentration of n = 0.5 to 2.5 wt% and those of 10–20 nm larger at a higher concentration than 1 wt%. The structure of the prepared composites was characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), atomic force microscopy (AFM), Raman and X-ray photoelectron spectroscopy (XPS). Optical properties were determined using UV-vis spectroscopy. Six polymer solar cells with modification by an TiO₂/n-Ag hole transporting layer were manufactured and studied under AM 1.5G-simulated solar illumination (100 mW cm⁻²). The best performance was obtained for a device with the ITO/(PEDOT:PSS):1.5%Ag in TiO₂/P3HT:PCBM/Al architectures. Under these conditions, a PCE of 2.07% with open circuit voltage V_oc = 0.612 V, short circuit current density J_sc = 5.94 mA cm⁻², and fill factor FF = 0.57 was achieved. Additionally, devices were tested by electrochemical impedance spectroscopy under illumination and a well-fitted equivalent circuit was proposed. Finally, our idea of the linkage of TiO₂/n-Ag with PEDOT:PSS and P3HT in the constructed devices taking into account the amount of Ag in TiO₂ was proposed.

New Journal of Chemistry 42 (2018) 7340-7354.

DOI: 10.1039/C7NJ05180H

http://pubs.rsc.org/en/content/articlelanding/2018/nj/c7nj05180h/unauth#!divAbstract

Morphology-controlled synthesis of nanosphere-like NiCo 2 S 4 as cathode materials for high-rate asymmetric supercapacitors

Posted by moniq25 on May 1, 2018 at 5:43pm

Yin-Ying Chen, Periyathambi Dhaiveegan, Monika Michalska, Jeng-Yu Lin

Abstract

In this study, we successfully synthesized nanosphere-like NiCo₂S₄(NCS) materials via one-pot polyvinylpyrrolidone (PVP)-assisted hydrothermal method, and directly were employed as cathode materials for asymmetric supercapacitors (ASCs). It is found that the surface morphology of the NCS materials can effectively tuned from the irregular to nanosphere-like shape along with the reduced particle size by simply altering the concentration of PVP contents. After the optimization of the PVP concentration, the resultant NCS electrode delivered remarkable specific capacity up to 82.6 and 46.2 mAh g⁻¹at a current density of 1 and 16 A g⁻¹, respectively. Additionally, an ASC fabricated by employing the nanosphere-like NCS as the cathode and graphene hydrogel (GH) as anode demonstrated a high energy density of 23.8 Wh kg⁻¹ at a power density 1016.5 W kg⁻¹. More importantly, the as-assembled ASC retained 91.4% of its initial capacity after charged/discharged at 8 A g⁻¹ for 5000 cycles, signifying its excellent cycling performance.

Electrochimica Acta 274 (2018) 209-216.

https://doi.org/10.1016/j.electacta.2018.04.086

https://www.sciencedirect.com/science/article/pii/S0013468618308302

Investigation of carbon coating approach on electrochemical performance of Li4Ti5O12/C composite anodes for high-rate lithium-ion batteries

Posted by moniq25 on February 9, 2018 at 9:26pm

Periyathambi Dhaiveegan, Hao-Ting Peng, Monika Michalska, Yaoming Xiao, Jeng-Yu Lin, Chien-Kuo Hsieh

Investigation of carbon coating approach on electrochemical performance of Li₄Ti₅O₁₂/C composite anodes for high-rate lithium-ion batteries

Abstract:

Submicron-sized Li₄Ti₅O₁₂/C (LTO/C) composites were successfully synthesized by using one-step and two-step route, in which sucrose was used as carbon precursor, and employed as anode materials for lithium-ion batteries (LIBs). The structure, surface morphology, and chemical compositions were characterized by X-ray diffraction, Raman spectroscopy, scanning, and transmission electron microscopy techniques. The electrochemical properties of the carbon-coated samples were examined by using the charge/discharge tests, cyclic voltammetry, and electrochemical impedance spectroscopy. It was found that the LTO/C synthesized by one-step method (designated as LTO/C-O) possessed smaller LTO/C particle size, more cohesive particle distribution, and more uniform conductive carbon layer on LTO surface compared with that synthesized by two-step method (LTO/C-T). As a result, the LTO/C-O electrode illustrated a high discharge capacity of 173.6 mAh g⁻¹ at a charge/discharge rate of 0.1 C. Moreover, the discharge capacity retention of the LTO/C-O electrode can effectively deliver to 95.9, 90.9, 87.9, and 80.9%, whereas the LTO/C-T electrode exhibited 94.0, 79.9, 68.0, and 50.1% at 1, 5, 10, and 20 C, respectively. Therefore, the LTO/C-O can be considered as one of the promising anode materials for high-rate LIBs.

Journal of Solid State Electrochemistry (2018) https://doi.org/10.1007/s10008-018-3886-2

LInk to article:

https://link.springer.com/article/10.1007/s10008-018-3886-2#citeas

Electrochemical properties of lithium–titanium oxide, modified with Ag–Cu particles, as a negative electrode for lithium-ion batteries

Posted by moniq25 on December 18, 2017 at 10:58pm

Michał Krajewski, Bartosz Hamankiewicz, Monika Michalska, Mariusz Andrzejczuk, Ludwika Lipińska, Andrzej Czerwiński

Abstract

Composites of Li4Ti5O12 with Ag–Cu particles were successfully synthesized by solid-state reaction followed by thermal decomposition of the metal substrates. The presence of metallic particles was confirmed by X-ray diffraction, scanning transmission electron microscopy and X-ray photoelectron spectroscopy. Galvanostatic charge–discharge tests showed improved specific capacity and capacity retention of Li4Ti5O12/Ag–Cu composites at a 10C current rate, while cyclic voltammetry and electrochemical impedance spectroscopy revealed changes in Li⁺ ion chemical diffusion coefficient values and charge-transfer resistance with increasing amount of Ag–Cu in prepared powders. The synthesis and structural, morphological and electrochemical evaluation of Li4Ti5O12/Ag–Cu powders, carried out in this work, were also presented here for the first time.

RSC Advances 7 (2017) 52151-52164

http://pubs.rsc.org/en/content/articlehtml/2017/ra/c7ra10608d

Synthesis and characterization of nanocrystalline tin sulfide (SnS) with SnO2 nanoislands flakes

Posted by moniq25 on August 15, 2017 at 10:09pm

Monika Michalska, Mariusz Andrzejczuk, Krzysztof Oberda

Abstract:

In this paper, we present the results of an investigation of the compositional and structural features of nanocrystalline tin sulfide (SnS) decorated with SnO₂, which was synthesized in a high-energy ball-milled (HEBM) process. Tin and sulfur powders were used as starting reagents. The materials were turned into nanopowders after the heating (followed by HEBM) that was carried out in nitrogen in the temperature range of 500–800 °C. The surface morphology, structure, and composition of samples were characterized by the following methods: X-ray diffraction patterns (XRD), Raman and X-ray photoelectron spectroscopy (XPS). The well-defined XPS peaks at 495.1eV and 486.7eV corresponded to Sn 3d_5/2 and 3d_3/2 states confirm the formation of SnO₂ nanoislands flakes on SnS surface of orthorhombic structure. Scanning (SEM) and transmission electron microscopy (TEM) imaging techniques were used to study the presence of SnO₂ on tin sulfide surface.

Journal of Alloys and Compounds 726 (2017) 388-393.

http://www.sciencedirect.com/science/article/pii/S0925838817327482

New synthesis route to decorate Li4Ti5O12 grains with GO flakes

Posted by moniq25 on July 13, 2017 at 8:17pm

Monika Michalska, Dominika A Ziółkowska, Mariusz Andrzejczuk, Agnieszka Krawczyńska, Agata Roguska, Andrzej Sikora

Abstract:

Lithium titanium oxide (Li₄Ti₅O₁₂) particles were surface-decorated with 1–5% wt. of graphene oxide (GO) using new low temperature method (LTM). All the synthesized materials have been characterized by a number of methods: X-ray powder diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and atomic force microscopy (AFM). The study includes the influence of the graphene oxide flakes decoration on lithium titanium oxide crystal structure. Raman analysis demonstrates a typical spinel spectra of Li₄Ti₅O₁₂ (LTO) and relatively sharp D and G lines of GO structure. The XPS measurements shows the most intense peaks at the binding energy of 284.5 eV, which corresponds to CC/CC in aromatic rings of GO located on the surface of Li₄Ti₅O₁₂. The peaks observed at 285.8, 286.9 and 288.3 eV belong to CO in hydroxyl and epoxy groups, carbonyl functional groups, and OCO in carboxyl groups, respectively. The correlation between the structural and morphological analysis of spinel Li₄Ti₅O₁₂ structure decorated with graphene oxide (GO) flakes was examined for the first time in this work.

Journal of Alloys and Compounds 719 (2017) 210-217.

doi.org/10.1016/j.jallcom.2017.05.173

Formation of Fe and Ni substituted LiMn2–XMXO4 nanopowders and their crystal and electronic structure and magnetic properties

Posted by moniq25 on July 13, 2017 at 8:14pm

E. Talik, L. Lipińska, A. Guzik, P. Zajdel, M. Michalska, M. Szubka, M. Kądziołka-Gaweł, R. L. Paul

Abstract:

The Pechini sol-gel method was applied to obtain LiMn_2–xT_xO₄ (T = Ni, Fe; x = 0.1 to 0.5) nanopowders. Crystal and electronic structures, chemical composition and magnetic properties of the materials were characterized by X-ray diffraction, XPS, SEM/EDX microscopy, prompt gamma-ray activation analysis (PGAA), Mössbauer spectroscopy and magnetic susceptibility, respectively. XRD measurements showed that the LiMn_2–xNi_xO₄ were single phase for x = 0.1 and 0.2. Three samples with higher Ni content contained some addition of a second phase. Analysis of the oxidation state of the dopants by XPS revealed ionic Ni²⁺ and Fe³⁺. Mössbauer spectroscopy also confirmed 3+ oxidation state of iron and its location in octahedral sites, which excluded the inverse spinel configuration. XPS examinations showed that Mn³⁺ ions dominated in the iron substituted series whereas the Mn⁴⁺ was dominant in the nickel series.

Materials Science-Poland 35 (2017) 159-172.

https://www.degruyter.com/view/j/msp.2017.35.issue-1/msp-2017-0014/msp-2017-0014.xml

Comparison of different sintering methods of Pb 1-x Cr x Te thermoelectric nanocomposites doped with iodine

Posted by moniq25 on July 13, 2017 at 8:11pm

Aleksandra Królicka, Monika Michalska

Abstract

N-type PbTe polycrystals were fabricated by the Bridgman method. Subsequently, the materials were pulverized in a planetary ball mill for 15 hours, pressed and sintered. In this paper we compare two sintering techniques: cold pressing followed by the sintering in a furnace (CPS) and the spark plasma sintering (SPS). The electrical and thermoelectric measurements were conducted for both materials (CPS and SPS) and the results are presented and discussed in the paper. Maximal ZT values of 0.2 and 0.45 were obtained for the CPS and SPS materials, respectively. Additionally, SEM and EDX analyses were performed. To determine the obtained crystallites size, the X-ray diffraction measurements were carried out. The obtained results show that the significant reduction in particle size may be obtained by the milling procedure - from a few milimeters in the polycrystalline material to a few tens of nanometers for the powdered one.

Physica B: Condensed Matter (2017) doi.org/10.1016/j.physb.2017.06.004

STEM study of Li4Ti5O12 anode material modified with Ag nanoparticles

Posted by moniq25 on May 8, 2016 at 9:59pm

M. Andrzejczuk, A. Roguska, M. Michalska, L. Lipińska, A. Czerwiński, M. Cantoni, A. T. Krawczyńska, M. Lewandowska

Abstract:

Comprehensive scanning transmission electron microscopy (STEM) analysis of Li4Ti5O12 (LTO) powder modified by deposited Ag nanoparticles was performed. Nanocomposite powders with Ag content of 1 wt.%, 4 wt.%, 10 wt.% were fabricated in a chemical process from suspensions of Ag and LTO. Apart from the STEM results, the presence of pure silver on the surface of the ceramic powder was confirmed by XRD and XPS analyses. The silver particles deposited on the LTO particles were characterized using the EDS mapping technique. The quantified results of the EDS mapping showed a relatively homogenous distribution of silver nanoparticles on the powder surface for every metal content. The mean diameter of the nanoparticles deposited on the LTO powder was about 4 nm in all cases. An increase in the Ag content during chemical surface modification did not cause changes in the microstructure. Focusing on an analysis of the metallic nanoparticles on the ceramic powder, electron tomography was used as an investigative technique. A very precise analysis of three-dimensional nanostructures is desirable for a comprehensive analysis of complex materials. The quantified analysis of the Ag nanoparticles visualized using electron tomography confirmed the results of the size measurements taken from the two-dimensional EDS maps.

Journal of Microscopy (2016). doi:10.1111/jmi.12414

http://onlinelibrary.wiley.com/doi/10.1111/jmi.12414/full

moniq25's Posts (10)

Improved electrochemical performance of LiMn2O4 cathode material by Ce doping

Analysis of the surface decoration of TiO2 grains using silver nanoparticles obtained by ultrasonochemical synthesis towards organic photovoltaics

Abstract

Morphology-controlled synthesis of nanosphere-like NiCo 2 S 4 as cathode materials for high-rate asymmetric supercapacitors

Abstract

Investigation of carbon coating approach on electrochemical performance of Li4Ti5O12/C composite anodes for high-rate lithium-ion batteries

Electrochemical properties of lithium–titanium oxide, modified with Ag–Cu particles, as a negative electrode for lithium-ion batteries

Synthesis and characterization of nanocrystalline tin sulfide (SnS) with SnO2 nanoislands flakes

New synthesis route to decorate Li4Ti5O12 grains with GO flakes

Formation of Fe and Ni substituted LiMn2–XMXO4 nanopowders and their crystal and electronic structure and magnetic properties

Comparison of different sintering methods of Pb 1-x Cr x Te thermoelectric nanocomposites doped with iodine

STEM study of Li4Ti5O12 anode material modified with Ag nanoparticles

Note: this page contains paid content.