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Upadhyayula V Varadaraju
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Upadhyayula V Varadaraju
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Upadhyayula V Varadaraju
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Varadaraju, Upadhyayula V.
Varadaraju, Upadhyayula
Varadaraju, U. V.
Varadaraju, Upadhyayula Venkata
Varadaraju, Upadhayayula V.
Varadaraju, U.
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6 results
Now showing 1 - 6 of 6
- PublicationElectrochemical reaction of lithium with Zn3P2(01-06-2005)
;Satya Kishore, M. V.V.M.Zn3P2 has been studied as an anode material for lithium-ion batteries. Electrochemical studies demonstrate that the initial discharge and charge capacities are 1056 and 710 mAh g-1, respectively. The discharge-charge reaction mechanism of lithium with Zn 3P2 is analyzed by ex situ X-ray diffraction. On initial discharge, LiZn alloy is formed in a matrix of Li3P. Upon charge, LiZn alloy is transformed completely into Zn metal and Li3P is converted partially to P, which reacts with Zn to form the original Zn 3P2 phase. The reversible capacity of Zn3P 2 is improved when cycled in the limited voltage window. © 2005 Elsevier B.V. All rights reserved. - PublicationPb3O4 type antimony oxides MSb2O 4 (M = Co, Ni) as anode for Li-ion batteries(01-06-2012)
;Jibin, A. K. ;Reddy, M. V. ;Subba Rao, G. V.; Chowdari, B. V.R.Polycrystalline samples of isostructural MSb2O4 (M = Co, Ni) have been prepared by solid state synthesis and lithium-storage is investigated as possible anode materials for lithium-ion batteries. The reaction mechanism of lithium with MSb2O4 (M = Co, Ni) is explored by galvanostatic cycling, cyclic voltammo-gram and ex situ studies. Both CoSb2O4 and NiSb2O4 exhibit similar electrochemical behavior and show reversible capacity of 490 and 412 mAhg -1 respectively in the first cycle. Reversible alloying de-alloying of Lix Sb takes place in an amorphous matrix of M (Co, Ni) and Li2O during electrochemical cycling. © 2012 Elsevier Ltd. All rights reserved. - PublicationElectrochemical performance of LiMSnO 4 (M=Fe, In) phases with ramsdellite structure as anodes for lithium batteries(01-11-2004)
;Satya Kishore, M. V.V.M.; Raveau, B.LiMSnO 4 (M=Fe, In) compounds were synthesized by high temperature solid-state reaction method and the electrochemical studies were carried out vs. lithium metal. Lithium is reversibly intercalated and deintercalated in LiFeSnO 4 with a constant capacity of ∼90 mAh/g. In situ X-ray diffraction data show that ramsdellite structure is stable for lithium intercalation and deintercalation in LiFeSnO 4. Galvanostatic discharge/charge of LiFeSnO 4 in the voltage window 0.05-2.0 V shows a reversible capacity of ∼100 mAh/g. The observed capacity in LiFeSnO 4 is due to the two processes involving alloying/dealloying of Li 4.4Sn and formation/decomposition of Li 2O. In contrast, the new isotypic oxide LiInSnO 4 does not exhibit any lithium intercalation due to the absence of mixed valence for indium. Its reversible capacity is strongly dependent on the voltage window. LiInSnO 4 exhibits severe capacity fading on cycling in the voltage window 0.05-2.0 V, but shows a stable capacity of ∼90 mAh/g in the voltage range 0.75-2.0 V. In situ XRD patterns of Li xFeSnO 4 (1≤x≤2) at various Li contents during initial lithium intercalation and deintercalation. © 2004 Elsevier Inc. All rights reserved. - PublicationNbSb2 as an anode material for Li-ion batteries(13-09-2006)
;Reddy, M. AnjiPolycrystalline samples of NbSb2 have been synthesized and studied as anode material for lithium-ion batteries. The reaction mechanism of lithium with NbSb2 is investigated by ex situ XRD and cyclic voltammogram studies. Li3Sb and Nb are formed during first discharge and during charge lithium is extracted from Li3Sb. The first cycle discharge capacity is 420 mA hg-1 and first cycle charge capacity is 315 mA hg-1. © 2006. - PublicationEnhanced nanoscale conduction capability of a MoO 2/Graphene composite for high performance anodes in lithium ion batteries(15-10-2012)
;Bhaskar, Akkisetty ;Deepa, Melepurath ;Rao, T. N.A MoO 2/Graphene composite as a high performance anode for Li ion batteries is synthesized by a one pot in-situ low temperature solution phase reduction method. Electron microscopy and Raman spectroscopy results confirm that 2D graphene layers entrap MoO 2 nanoparticles homogeneously in the composite. X-ray photoelectron spectroscopy shows the presence of oxygen functionalities on graphene, which allows intimate contact between MoO 2 nanoparticles and the graphene. Conductive atomic force microscopy reveals an extraordinarily high nanoscale electronic conductivity for MoO 2/Graphene, greater by 8 orders of magnitude in comparison to bulk MoO 2. The layered nanostructure and the conductive matrix provide uninhibited conducting pathways for fast charge transfer and transport between the oxide nanoparticles and graphene which are responsible for the high rate capability, a large lithium ion capacity of 770 mAh g -1, and an excellent cycling stability (550 mAh g -1 reversible capacity retained even after 1000 cycles!) at a current density of 540 mA g -1, thereby rendering it to be superior to previously reported values for neat MoO 2 or MoO 2/Graphene composite. Impedance analyses demonstrate a lowered interfacial resistance for the composite in comparison to neat MoO 2. Our results demonstrate the enormous promise that MoO 2/Graphene holds for practical Li-ion batteries. © 2012 Elsevier B.V. - PublicationPhosphides with zinc blende structure as anodes for lithium-ion batteries(01-06-2006)
;Satya Kishore, M. V.V.M.The phosphides InP and GaP with a zinc blende structure are examined as anode materials for lithium-ion batteries. During discharge, X-ray diffraction phase analysis reveals the formation of Li-In/Li-Ga alloy and amorphous Li3P. On charge, lithium is extracted from both LixM (M = In, Ga) alloy and Li3P. InP shows a reversible capacity of ∼475 mAh g-1 in the voltage range between 0.2 and 1.5 V, whereas GaP exhibits poor capacity retention compared with that of InP. © 2005 Elsevier B.V. All rights reserved.