Phd in CHEMICAL SCIENCES

Thesis title: Lithium-Sulfur, Solid-State and Seawater Batteries as Strategic Approach to Diversified Electrochemical Energy Storage

Within the dynamic landscape of battery technology's rapid expansion, diversity of options plays a pivotal role to boost the transition towards a more energy-sustainable society. The battery industry could face a potential pitfall by overreliance on a single component. When examining predictions from energy analysts, it becomes evident that the demand for batteries remains robust and is continuously growing, sustained not only by even more greener government policies but also by more individual awareness of the climate situation. To mitigate the risks associated with the forthcoming surge in demand, the battery industry must prioritize diversity in its technological offerings to meet evolving requirements in different applications. Diversifying energy storage systems is essential to leverage the strengths of various technologies to address the unique challenges posed by different energy sources and grid conditions while promoting sustainability and technological advancement. Aligning chemistries with their optimal and most suitable applications will ultimately yield significant benefits for the entire battery industry alleviating the costs and reinforcing the material supply chains facilitating, finally, the transition towards a greener society. This thesis endeavors to explore various storage technologies within the context of next-generation batteries. In Chapter 3, in the pursuit to overcome the inherent performance limitations of rocking-chair batteries and address concerns regarding material volatility and availability, we have examined lithium-sulfur batteries. The present work encompasses the preparation of a carbon/sulfur cathode, which has been tested in conjunction with lithium metal using various electrolyte solutions based on different amount of a highly stable and safe ionic liquid combined with ether solvents. The goal was to realize a benefit from the IL addition inhibiting the potential sulfur cathode dissolution. In Chapter 4, with a focus on safety, we delve into the study of a sulfide-based solid electrolyte. Specifically, we fabricated polyethylene oxide-based polymer interlayers as a strategy to enhance the compatibility between lithium metal and a sulfide solid electrolyte. Three distinct PEO-based interlayers, varying in salt composition, have been synthesized. Comprehensive physicochemical and electrochemical characterizations have been conducted. Pushing the boundaries of chemistry beyond lithium, we have explored a unique sodium-based battery system that utilizes seawater as an abundant source of sodium ions, known as the Seawater Battery (SWB), discussed in Chapter 5. Building upon prior research involving the addition of Na-Biphenyl in the electrolyte solution, which facilitates reversible storage and enables uniform, low-overpotential sodium-metal deposition, our investigation now extends to the incorporation of Tin (II) chloride (SnCl2) as an in-situ-forming additive for the Na-Sn alloy layer in the BP anolyte of anode-less SWBs. Furthermore, in the view of a scaling-up of the system employing Na-Biphenyl in an anode-free configuration, the implementation of techniques able to provide a fast and real-time response is essential. In this context, the intermittent current interruption method can provide insightful feedback on the state of health of the battery, real-time monitoring and defect detection, making it suitable for applications such as battery diagnostics. Each Chapter will present a brief introduction on the specific topic, the materials and methods adopted, the obtained results and their discussion, to finally come to the conclusions. In the end, General Remarks and Perspectives about the specific works discussed will be provided.