Investigation of one-dimensional Ti-O based materials and their derivatives for energy storage application

Abstract

Emerging energy storage demands in smart grid and electric vehicles are requiring an energy storage capability several times higher than that of the state of the art Li-ion technology. In this regard Li-sulfur battery is expected to transform the electrochemical energy storage technology to the next level as it holds the possibility to get two to three times higher energy density than the state of the art Li-ion battery. However, the poor electrical conductivity of sulfur and the high dissolution of the intermediate lithium polysulfides create various problems, which limited the utilization of its full potential. Non-carbonaceous sulfur hosts such as $TiO_2$ and TiN, which can effectively immobilize polysulfides in the cathode, make it possible to get remarkable improvements in active material utilization and capacity retention for long term cycling. However, it has not been possible to use these polar, conductive, ceramic materials for higher active material loading (> 2 mg/$cm^2$) due to their low flexibility compared to carbonaceous materials. Here we demonstrated the possibility of designing three dimensional freestanding electrode using 1-D $TiO_2$ and polycrystalline 1-D TiN for a relatively higher sulfur loading of 2.5 mg/$cm^2$. Structural analysis of the electrodes and electrochemical performances reveal that the 1-D ceramic materials are promising candidates to be used as freestanding electrode for high loading Li-S system. This study is among the early attempts to use non-carbon based materials for freestanding electrode design and paves way for the development such system to higher loading and better performance.