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LiMnBO<sub>3</sub>/C: A Potential Cathode Material for Lithium Batteries
Aravindan, V.,Karthikeyan, K.,Amaresh, S.,Lee, Y.S. Korean Chemical Society 2010 Bulletin of the Korean Chemical Society Vol.31 No.6
$LiMnBO_3$ was successfully synthesized by a solid-state reaction method both with and without a carbon coating. Adipic acid was used as source material for the carbon coating. $LiMnBO_3$ was composed of many small polycrystalline particles with a size of about 50 - 70 nm, which showed a very even particle morphology and highly ordered crystalline particulates. Whereas the carbon coated $LiMnBO_3$ was well covered by mat-like, fine material consisting of amorphous carbon derived from the carbonization of adipic acid during the synthetic process. Carbon coated cell exhibited improved and stable discharge capacity profile over the untreated. Two cells delivered an initial discharge capacity of 111 and 58 mAh/g for $LiMnBO_3$/C and $LiMnBO_3$, respectively. Carbon coating on the surface of the $LiMnBO_3$ drastically improved discharge capacity due to the improved electric conductivity in the $LiMnBO_3$ material.
Aravindan, Vanchiappan,Sundaramurthy, Jayaraman,Suresh Kumar, Palaniswamy,Lee, Yun-Sung,Ramakrishna, Seeram,Madhavi, Srinivasan The Royal Society of Chemistry 2015 Chemical communications Vol.51 No.12
<P>In the present review, we describe the development of a high energy density LIB fabricated with all 1D nanofibers as the anode and cathode, as well as a separator-cum-electrolyte prepared by an electrospinning technique without compromising the power capability and cycle life. Such a unique assembly certainly enables realizing the advantages of using 1D nanostructures in practical LIBs, irrespective of the anode or cathode in the presence of gelled polyvinylidene fluoride-<I>co</I>-hexafluoropropylene as the separator-cum-electrolyte. Outstanding cycling profiles with high power densities were noted for all the configurations evaluated. This excellent performance opens up new avenues for the development of high performance Li-ion power packs with a long cycle life and high energy and power densities to drive zero emission transportation applications in the near future, and opens up new research activities in this field as well.</P> <P>Graphic Abstract</P><P>The present review outlines high performance Li-ion cells fabricated with all one-dimensional materials as the cathode and anode, as well as a separator-cum-electrolyte prepared by an electrospinning technique. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c4cc07824a'> </P>
Insertion-Type Electrodes for Nonaqueous Li-Ion Capacitors
Aravindan, Vanchiappan,Gnanaraj, Joe,Lee, Yun-Sung,Madhavi, Srinivasan American Chemical Society 2014 Chemical reviews Vol.114 No.23
<P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/chreay/2014/chreay.2014.114.issue-23/cr5000915/production/images/medium/cr-2014-000915_0019.gif'></P>
Aravindan, V.,Karthikeyan, K.,Kang, K. S.,Yoon, W. S.,Kim, W. S.,Lee, Y. S. Royal Society of Chemistry 2011 Journal of materials chemistry Vol.21 No.8
<P>Superior lithium storage in Li<SUB>2</SUB>MnSiO<SUB>4</SUB> cathodes was observed by altering carbon content during the formulation of electrodes. Initially, Li<SUB>2</SUB>MnSiO<SUB>4</SUB> was prepared by a conventional solid-state reaction at 900 °C under Ar flow with a fixed amount of adipic acid, which acts as a gelating agent during synthesis. The phase formation was confirmed through powder X-ray diffraction measurements. Scanning electron microscope pictures indicate the particulate morphology of synthesized Li<SUB>2</SUB>MnSiO<SUB>4</SUB> particles. Various compositions of electrodes were formulated using the conducting carbon (ketjen black) from 3 to 11 mg along with active material. All the fabricated electrodes were cycled in a Li/Li<SUB>2</SUB>MnSiO<SUB>4</SUB> cell configuration to evaluate its lithium storage performance at 0.05 C rate. Among the electrodes, 42% carbon in the composite electrode exhibited a very stable discharge behaviour ∼140 mA h g<SUP>−1</SUP> for 40 cycles at room temperature. Such storage performance was ascribed to the improved electronic conductivity of Li<SUB>2</SUB>MnSiO<SUB>4</SUB> electrodes by incorporating carbon. This improvement was supported by electrochemical impedance spectroscopy measurements. Rate performance studies were also conducted and presented in the manuscript.</P> <P>Graphic Abstract</P><P>The effect of carbon content during the formulation of electrode was studied and it showed increasing carbon content (up to 42%) leads to improved cell performance (140 mA h g<SUP>−1</SUP>) which is due to the enhancement in electronic conductivity and it was validated through electrochemical impedance measurements. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c0jm03471a'> </P>
Vanchiappan Aravindan,Palanisamy Vickraman,Kaliappa Krishnaraj 한국물리학회 2009 Current Applied Physics Vol.9 No.6
This paper describes, nanocomposite polymer electrolyte (NCPE) based on polyvinylidenefluoride-cohexafluoropropylene (PVdF-HFP), which comprises the novel lithium difluoro(oxalato)borate (LiDFOB). Ehtylene carbonate (EC) and diethyl carbonate (DEC) mixture was used as gelling agent and nanoparticulate TiO2 used as filler. The NCPE membranes were subjected to a.c. impedance, tensile strength, Raman studies, TG/DTA and morphological studies. 5 wt% TiO2 comprising membranes exhibited enhanced conductivity of 0.56 mS cm-1and the Young’s modulus was increased from 1.32 to 2.74 MPa. The structural change of α to β phase was confirmed by Raman studies. The thermal stability of the NCPE membrane is found to be 130 ℃. Calculation of activation energy and synthesis of LiDFOB has also been presented. This paper describes, nanocomposite polymer electrolyte (NCPE) based on polyvinylidenefluoride-cohexafluoropropylene (PVdF-HFP), which comprises the novel lithium difluoro(oxalato)borate (LiDFOB). Ehtylene carbonate (EC) and diethyl carbonate (DEC) mixture was used as gelling agent and nanoparticulate TiO2 used as filler. The NCPE membranes were subjected to a.c. impedance, tensile strength, Raman studies, TG/DTA and morphological studies. 5 wt% TiO2 comprising membranes exhibited enhanced conductivity of 0.56 mS cm-1and the Young’s modulus was increased from 1.32 to 2.74 MPa. The structural change of α to β phase was confirmed by Raman studies. The thermal stability of the NCPE membrane is found to be 130 ℃. Calculation of activation energy and synthesis of LiDFOB has also been presented.
Jayaraman, Aravindan,Lee, Sunwoo American Chemical Society 2019 ORGANIC LETTERS Vol.21 No.10
<P>A variety of arylalkynoic acids reacted with 1,3-diiodo-5,5-dimethylhydantoin and HF·pyridine in the presence of AgOAc to provide the corresponding 1-fluoro-2,2-diiodovinylarenes in good yields and high regioselectivity. In addition, Pd-catalyzed cross-coupling reaction of 1-fluoro-2,2-diiodovinylarenes afforded diaryl coupling products in the Suzuki reaction and monoaryl coupling products with high stereoselectivity in the Hiyama reaction. It was found that C-F-activated borylation of fluoroalkenes using Pd catalyst afforded the vinylboranes with good yields.</P> [FIG OMISSION]</BR>
V. Aravindan,P. Vickramana,A. Sivashanmugam,R. Thirunakaran,S. Gopukumar 한국물리학회 2013 Current Applied Physics Vol.13 No.1
This paper describes the physico-chemical and electrochemical properties of polyvinylidenefluoridehexafluoropropylene (PVdF-HFP) membranes (GPM) prepared by phase inversion technique. Nanocomposite polymer membranes (NCPM) are also prepared by the same technique using AlO(OH)n nanoparticles. The prepared GPM and NCPM are gelled with liquid electrolyte containing three different salts namely, lithium bis(oxalate)borate, lithium fluoroalkylphosphate and lithium difluoro(oxalato) borate. Prepared membranes were subjected to various physico-chemical characterizations likely, mechanical stability, ionic conductivity, morphological studies, surface area and thermal analysis. Electrochemical chemical properties of membranes are evaluated in half-cell configurations (Li/NCPM or GPM/LiFePO4) at room temperature conditions. Galvanostatic cycling profiles clearly indicates the improved performance of chelato borate based anions i.e. BOB and DFOB when compared to fluoroalkyl group (FAP).