Rational design of materials and cell configuration for metal (Li/Na/Mg)-sulfur batteries

Abstract

The increasing demand for energy and limited availability of fossil fuels trigger the development of renewable resources. However, large scale-up application of renewable energy is inhibited by the inability of storage. High efficient electrical energy storage (EES) becomes one of the tools for utilizing electricity produced from intermittent renewable sources. Despite Lithium ion batteries (LIBs) being the most mature technology in current portable devices, metal-sulfur batteries (MSB) show great promise as the future energy storage device due to the low cost ($0.065/kg) and high theoretical capacity (1675 mAh/g) of sulphur. This thesis starts with the well-renowned Li-S batteries by exploring safer Li metal replacement. Pairing Al-Li alloy with S is of great promise to suppressing the dendrite growth and enhancing ambient stability, thus achieving high-energy rechargeable batteries with improved safety. A parallel interface engineering (PIE) strategy is proposed in the full cell design, and the improvement is attributable to the more efficient and uniform lithium sulphides deposition on the chemically uniform surfaces of the carbon cathode, as well as the suppressed growth of dendritic species on the Li-Al alloy anode with an implantable solid-electrolyte interphase. The second stage of the research focuses on the studies of Na-S batteries. A unique intertwined sponge is also prepared to facilitate ion diffusion/mass transfer of Na-S batteries, and to provide reservoir to adsorb polysulfides. The last section presents Mg-S batteries with a dual-doped (Co and N) Lychee-like sulfur host (Co@NC) to effectively mitigate magnesium polysulfides shuttling. The mesopores of Co@NC precursor can physically confine the sulfur species, while Co and N elements doping play significant role in strongly binding polysulfides. This strategy provides a promising example for the development of novel post Li-ion batteries in terms of the rational design of carbon materials.