(Digital Presentation) Electrochemical Relithiation Protocols for Restoration of Cycle Aged NMC Cathodes

Abstract

Recycling end-of-life (EoL) lithium-ion batteries is of great significance to provide additional transition metal resources and alleviate environmental pollution from electric vehicle battery wastes. This study provides essential understanding towards developing an electrochemical relithiation process that will restore lithium loss in EoL intercalation cathode materials. This electrochemical relithiation process is one of several relithiation options being considered as a part of a direct recycling process designed to increase the efficiency of battery recycling by maintaining the composition and morphology of EoL cathode materials. A unique benefit of electrochemical relithiation is that it provides a potential alternative to processes that require EoL to be returned to powder form and then recast. Electrochemically aged NMC cathode materials have been prepared and characterized to establish the extent of EoL material structural transformations and lithium loss. A model-informed experimental process is used to identify the optimal electrochemical relithiation protocol to minimize the time taken to relithiate EoL materials and maximize the amount of lithium restored. Protocols were evaluated based on their ability to enable rapid lithium intercalation, maintain or reinstate structural uniformity in the EoL material and fully restore lithium content. An optimal protocol was identified at elevated temperatures utilizing a novel scanning voltage step. This work is part of ReCell which is a collaborative effort to develop efficient and economical recycle and reuse methods for EoL battery cathodes.