In-situ and in-operando investigation of lithium/sulfur batteries porous systems

Abstract

Electrochemical energy storage (EES) is becoming more prevalent in the power grid, enabling the concentration of electricity generation on intermittent renewable sources. Positive conversion electrodes for the next generation of lithium-sulfur (Li-S) batteries have attracted considerable interest. This is because Li-S systems have high specific capacity and energy. However, the Li-S system has some drawbacks that need to be addressed before it can be commercialized. The incorporation of sulfur into porous structures has become increasingly popular in recent years. Metal Organic Frameworks (MOFs) and other porous systems have attracted attention due to the versatile modulation of the structure. These novel sulfur-based electrode designs have significantly improved the electrochemical performance of Li-S batteries. However, the development of Li-S batteries requires a detailed understanding of the underlying electrochemical reaction mechanism and kinetics, as well as the degradation process. In-situ and in-operando methods have been developed to evaluate Li/S systems. The mechanistic knowledge of Li-S batteries has dramatically benefited from advanced characterization techniques, especially X-ray techniques and neutron scattering. This includes X-ray diffraction (XRD), which is helpful for observing crystal structures, while X-ray absorption spectroscopy (XAS) can provide information on the most delicate local structural changes. X-ray imaging such as phase and transition contrast computed tomography (CT) can give information on morphological changes. Small-angle neutron scattering (SANS) and small-angle X-ray scattering (SAXS) are also used, particularly in the studies of porous materials. Therefore, these complementary methods can be used to study the microstructure of positive carbon compounds in Li-S batteries. The project will enable new insights into the positive electrodes of Li-S batteries during their performances to provide new mechanistic insights that will help develop improved electrodes for Li-S cells. (AU)