Exploring Soft Matter and Modified-Liquid Electrolytes for Alkali metal (Li, Na) Based Rechargeable Batteries

Abstract

The current upsurge in demand for high energy density batteries for applications across industries ranging from small scale portable electronics, electric automobiles to storage grids, has led to research in next generation, beyond lithium -ion batteries. Alkali metals like lithium and sodium, by virtue of their high theoretical capacity (3860 mAhg-1 for Li and 1165 mAhg-1 for Na) and low electrochemical potentials, are most suitable anodes for producing high energy density batteries. The vigorous reactivity, unstable solid-electrolyte interface and dendrite formation are some of the major hurdles towards use of lithium and sodium as anodes in a conventional liquid electrolyte battery. A well designed and optimised electrolyte plays a paramount role towards safe operation of an alkali metal battery. In the present thesis, we have explored few free-standing, mechanically stable plasticised gel polymer electrolytes (GPE) for lithium and sodium metal battery which has been demonstrated to have a good ionic conductivity with very stable interfacial properties and suppressed dendrite growth. A spectroscopic investigation into the ion-conduction mechanism in a concentrated lithium gel polymer electrolyte system has also been described in detail. Along with the stable performance of alkali metal batteries with the designed GPEs, we have also ventured into few high-capacity cathodes like sulphur and oxygen using modified electrolytes.