EAGER: CET: Advancing Sustainable Cathode Recycling of Spent Lithium-Ion Batteries using Deep Eutectic Solvents

This EArly-concept Grants for Exploratory Research (EAGER) award is made in response to Dear Colleague Letter 23-109, as part of the NSF-wide Clean Energy Technology initiative. Reliable and robust energy storage systems play a crucial role in the national transition towards a carbon-neutral economy. Lithium-ion batteries have brought a paradigm shift in the field of energy generation and storage, particularly in electric transportation.

However, the annual generation of spent lithium-ion battery waste is projected to exceed 5 million tons by 2030, with only 5% being recycled worldwide. While existing recycling processes have been implemented industrially, they face significant challenges such as high energy consumption, low metal separation efficiency, limited recyclability, and substantial waste generation.

To promote a circular economy and establish a waste-to-resource supply chain, it is imperative to develop efficient and sustainable metallurgical technologies for lithium-ion battery recycling. The objective of this EAGER research project is to advance the recycling of spent lithium-ion batteries through the development of next-generation recycling technologies based on benign leaching and electrodeposition using deep eutectic solvents.

This project will develop a closed-loop process that minimizes waste while maximizing metal recovery. The project will enable sustainable recycling of spent lithium-ion batteries thereby saving energy, reducing pollutants, and accelerating electrification. Furthermore, the intrinsically interdisciplinary nature of the research will foster a diverse training environment, providing opportunities for training and mentorship for both graduate and undergraduate students.

Knowledge gained through this study will be incorporated into existing courses, thus extending the experimental design approach to education activities, and benefiting more than 80 undergraduate and graduate students annually.

This research project will elucidate the mechanisms and chemistry involved in the recovery of battery metals using deep eutectic solvents and provide an innovative approach to recycling and reusing end-of-life products. The integrated research approach entails experimental testing, operando diagnostics, and statistical analysis, to develop a sustainable battery recycling process comprising leaching and electrodeposition within deep eutectic solvents.

The physicochemical mechanisms of the process along with their impact on process efficiency will be revealed through solubility measurements and coordination complex identification under various conditions, complemented by morphological characterization, quantitative elemental mapping, and microstructural analysis. These efforts will offer valuable insights into the solvating capabilities of various deep eutectic solvents, transport properties of battery metals in deep eutectic solvent electrolytes, and coordination behaviors of battery metals in diverse deep eutectic solvent environments.

Enhanced selectivity and product purity will be realized by exploring different solution chemistries and fine-tuning process operating parameters. The project will also unveil reaction pathways, rate-determining steps, and apparent activation energies, and provide a robust framework for accurately predicting process responses based on operating parameters, thus facilitating effective metal recovery from waste lithium-ion batteries.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.