LOW COST REDOX ACTIVE MATERIALS FOR SODIUM ION BATTERIES

Abstract

In pursuit of alternative energy storage technologies, cathode and anode materials for intercalation based sodium ion batteries are developed in this work. Earth abundant elements and cost-effective synthesis routes are used for designing materials in this thesis. Layered oxides offer advantage of low-cost of synthesis and high theoretical capacities on account of lower molecular weights. For these reasons, layered oxides have been chosen for this thesis work. Cu, Ti, Ni, Fe and Mn based Na-ion layered oxide cathodes are studied for their electrochemistry. Three O3 type layered oxides and one P3 type layered oxide is reported in this work with systematic improvements in specific energy density. For anode materials, hard carbon/soft carbon is considered to be the state of the technology for sodium ion batteries. However, synthesis of these carbonaceous electroactive material releases high amount of CO2/CO even when derived from biomasses. This motivated us to explore organic salts as possible anode materials for Na-ion batteries. Na3BTC (tri-sodium-1,3,5- benzene tricarboxylate) which is synthesized through a solution based synthesis at 70-90 ˚C has been investigated as a possible anode material for sodium storage