Available onlineKeywords: Activation energy dc conductivity ac impedance and diffusion coefficient A B S T R A C T Cathode materials in nano size improve the performance of batteries due to the increased reaction rate and short diffusion lengths. Lithium Iron Phosphate (LiFePO4) is a promising cathode material for Li-ion batteries. However, it has its own limitations such as low conductivity and low diffusion coefficient which lead to high impedance due to which its application is restricted in batteries. In the present work, increase of conductivity with decreasing particle size of LiFePO4/C is studied. Also, the dependence of conductivity and activation energy for hopping of small polaron in LiFePO4/C on variation of particle size is investigated. The micro sized cathode material is ball milled for different durations to reduce the particle size to nano level. The material is characterized for its structure and particle size. The resistivities/ dc conductivities of the pellets are measured using four probe technique at different temperatures, up to 150°C. The activation energies corresponding to different particle sizes are calculated using Arrhenius equation. CR2032 cells are fabricated and electrochemical characteristics, namely, ac impedance and diffusion coefficients, are studied.

Flames generate a large amount of chemically and thermally ionized species, which are involved in the growth dynamics of particles formed in flames. However, existing models predicting particle formation and growth do not consider particle charging, which may lead to bias in the calculated size distribution of particles. In this study, Fuchs' charging theory was coupled with a monodisperse particle growth model to study the simultaneous charging and coagulation of nanoparticles during combustion. In order to quantify the charging characteristics of nanoparticles, a high-resolution DMA was used to measure the mobilities of ions generated from a premixed flat flame operated at various conditions. The effect of temperature on ion-particle and particle-particle combination coefficients was further examined. The proposed model showed that the influence of charging on particle growth dynamics was more prominent when the ion concentration was comparable to or higher than the particle concentrations, a condition that may be encountered in flame synthesis and solid fuel-burning. Simulated results also showed that unipolar ion environments strongly suppressed the coagulation of particles. In the end, a simplified analysis of the relative importance of particle charging and coagulation was proposed by comparing the characteristic time scales of these two mechanisms.

Pulses are one of the most important legume crops in India contributing significantly high quality protein. Among the legumes, black gram (Vigna mungo L. Hepper), is an important legume crop in our country belonging to the family leguminoceae. The low productivity in pulses may be due to the fact that they are normally grown in marginal lands with inadequate soil moisture and poor fertility status. To increase yield under these circumstances, integrated seed treatment is given as a presowing treatment. Hence, a study was attempted to find out the influence of integrated seed treatments on growth and yield parameters in black gram. The seeds of black gram cv VBN 4 were subjected to various seed treatments and treated seeds along with the control were evaluated for their seed quality, growth, gas exchange and yield parameters both in laboratory and field trials. The study revealed that seeds fortified with MgSO4 + polykote + carbendazim + dimethoate + bioinoculant (Pseudomononas fluorescens) + Rhizobium + Azophos + pelleting with DAP recorded higher seed yield and other parameters when compared to control.