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  • Author: K. Vijaya Babu x
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K. Vijaya Babu and V. Veeraiah

Abstract

The most attractive property of Li0.5La0.5TiO3 (LLTO) electrolytes is their high ionic conductivity. Studies have shown that LLTO is capable of existing in a state with an ionic conductivity of 10-3 S/cm, which is comparable to liquid electrolytes. In addition to the high ionic conductivity of the material, LLTO is electrochemically stable and able to withstand hundreds of cycles. So, the studies of the solid electrolyte material are very important for the development of lithium-ion batteries. In the present paper, Li0.5La0.5Ti1-xZrxO3 (x = 0.05 and 0.1) have been prepared by a solid-state reaction method at 1300 °C for 6 hours to improve electrolyte materials for lithium-ion batteries. The phase identified by X-ray diffractometry and crystal structure corresponds to pm3m (2 2 1) space group (Z = 1). The frequency and temperature dependence of impedance, dielectric permittivity, dielectric loss and electric modulus of the Li0.5La0.5Ti1-xZrxO3 (x = 0.05 and 0.1) have been investigated. The dielectric and impedance properties have been studied over a range of frequency (42 Hz to 5 MHz) and temperatures (30 °C to 100 °C). The frequency dependent plot of modulus shows that the conductivity relaxation is of non-Debye type.

Open access

N. Murali, K. Vijaya babu, K. Ephraim babu and V. Veeraiah

Abstract

Layered oxide LiMO2 (Ni, Co, Mn) have been proposed as cathode materials for lithium-ion batteries. Mainly LiNiO2 is accepted as an attractive cathode material because of its various advantages such as low cost, high discharge capacity, good reversibility. The LiNi0.5Mn0.5O2 powders are synthesized by a sol-gel method using citric acid as a chelating agent. The structure of the synthesized material is analyzed by using XRD, FT-IR and the microstructures of the samples are observed by using FESEM. The intensities and positions of the peaks are in a good agreement with the previous results. The morphological changes are clearly observed as a result of manganese substitution. The Fourier transform infrared (FT-IR) spectra obtained with KBr pellet data reveal the structure of the oxide lattice constituted by LiO6 and NiO6 octahedra. The conductivity studies are characterized by (EIS) in the frequency range of 42 Hz to 1 MHz at room temperature to 120 °C. The dielectric properties are analyzed in the framework of complex dielectric permittivity and complex electric modulus formalisms. It indicates that the conductivity increases with increasing temperature. The fitting data of EIS plots replicate the non-Debye relaxation process with negative temperature coefficient of resistance (NTCR) behavior.

Open access

K. Anand, B. Ramamurthy, V. Veeraiah and K. Vijaya Babu

Abstract

The aim of this paper is to study the effect of Mg2+ doping in place of Ni in LiNiPO4 compounds synthesized by solid state reaction method. As Mg is a relatively light and cheap, and is expected to stabilize the structure, it has been considered as a substituent for Ni. The structural and conductivity studies of the substituted phases are discussed in comparison with LiNiPO4. In this study, we have proposed cation-substituted compounds, LiNi1–xMgxPO4 (x = 0, 0.05, 0.1 and 0.15) where a part of the divalent state of Ni2+ is replaced with the corresponding amount of Mg2+ and where the charge compensation is maintained by lithium deficiency. It is possible to obtain the mentioned compounds because the pristine LiNiPO4 compound is stable in ambient atmosphere, which differs considerably from the LiCoPO4 compound.