Recent advances in green deep eutectic solvents for lithium-ion battery recycling: A perspective on bibliometric analysis

Abstract

The rapid growth of electric vehicles worldwide has resulted in a significant increase in the demand for lithium-ion batteries (LIBs), thereby accelerating the development of the LIBs recycling industry. Currently, the predominant methods for recycling spent LIBs include pyrometallurgical, hydrometallurgical, and direct recycling techniques, each with its own advantages and disadvantages. To enhance the recycling efficiency of cathode metals from spent LIBs while promoting environmental sustainability, green deep eutectic solvents (DESs) have attracted scholarly interest. In this study, we conducted a bibliometric analysis of DESs to elucidate research progress from both quantitative and visual perspectives and to delineate the evolution of research hotspots. The published literature in the Science Citation Index Expanded (SCIE) database of the Web of Science Core Collection from 2014 to 2023 was analyzed, resulting in a total of 393 articles and reviews through the CiteSpace and VOSviewer tools. The results indicate a substantial increase in the number of relevant publications since 2019, with China leading in the volume of publications, followed by the United States, Australia, and India. As a subset of hydrometallurgy, DESs remain closely associated with the hotspots of hydrometallurgy and spent LIBs. Given that DESs are similar to hydrometallurgical technologies, their industrial application for leaching processes is feasible. However, challenges such as high viscosity, metal precipitation, and separation difficulties present significant obstacles. This research aims to enhance the understanding of the current state of DESs in the field of positive electrode metal recycling from spent LIBs and serves as a historical reference for future investigations.

Keywords: Bibliometric analysis; Deep eutectic solvents; Metal recycling; Spent lithium-ion batteries.