Urea, a basic chemical compound, holds diverse applications across numerous domains, ranging from agriculture to energy storage. Of particular interest is its role as a hydrogen bond donor (HBD). This specific characteristic has propelled its utilization as an essential component in crafting deep eutectic solvents (DESs) for battery electrolytes. Incorporating urea into DESs presents a promising avenue to address environmental concerns associated with traditional electrolytes, thereby advancing battery technology. Conventional electrolytes, often composed of hazardous and combustible solvents, pose significant environmental risks upon improper disposal potentially contaminating soil and water and threatening both human health and ecosystems. Consequently, there is a pressing need for eco-friendly alternatives capable of upholding high performance and safety standards. DESs, categorized as organic salts resulting from the blending of two or more compounds, have emerged as promising contenders for the next generation of electrolytes. Urea stands out among DES electrolytes by enhancing ion transport, widening the electrochemical window stability (ESW), and prolonging battery cycle life. Further, its non-toxic nature, limited flammability, and elevated thermal stability play pivotal roles in mitigating environmental concerns and safety issues associated with traditional electrolytes. Laboratory testing of urea-based DES electrolytes across various battery systems, including Al-ion, Na-ion, and Zn-ion batteries, has already been demonstrated. This review examines the evolution of urea-based DES electrolytes by elucidating their structure, molecular interaction mechanisms, performance attributes, and preparation methodologies.

Nanotechnology, with its critical influence across diverse disciplines, has increasingly drawn the attention of global researchers. This is predominantly due to the extraordinary potential that nanomaterials possess. Therefore, there is an utmost necessity to assimilate earlier studies and highlight the latest developments transpiring in the realm of nanotechnology. Indeed, numerous reviews are being carried out within the nanotechnology sector to examine the ongoing advancements. With this context in mind, the present chapter aims to provide a comprehensive review of the latest progress and developments related to nanomaterials. In particular, it seeks to outline the various types of nanomaterials, their synthesis methods – including physical, chemical, and biological procdures – and their characterization techniques. Additionally, the chapter strives to underscore recent applications of nanomaterials across a diverse array of fields. By providing such an inclusive view, this chapter aspires to function as a rich resource of information, equipping researchers, and scholars with a current understanding of the field. In doing so, it hopes to spark further exploration and innovation in this constantly evolving discipline. <!----> <!----> <!----> <!---->