Upadhyayula V Varadaraju

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.

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.

Polycrystalline 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.

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.