Over- and Hyper-Lithiated Oxides as Sacrificial Cathodes for Lithium-Ion Batteries

By incorporating sacrificial lithium (Li) sources during electrode fabrication, researchers aim to address the challenge of initial capacity loss due to the formation of a solid electrolyte interphase layer during the early cycles of lithium-ion batteries (LIBs). This research contributes to the augmentation of Li+ inventory within the electrode to compensate for the irreversible loss of Li+, thereby enhancing the reversibility and cycling performance of LIBs. There are various types of pre-lithiation additives; however, this perspective specifically discusses over- and hyper-lithiated oxide materials. Within these oxides, research directions are characterized by contrasting approaches aimed at either enhancing the reversibility or inducing the irreversibility of these materials. Intriguingly, both opposing approaches align with the common objective of increasing the energy density of LIBs by providing surplus Li+ to compensate for irreversible Li+ consumption. From this perspective, a concise overview of diverse pre-lithiation methodologies is provided and the reaction mechanisms associated with over- and hyper-lithiated oxides as sacrificial cathode additives for pre-lithiation are investigated. Subsequently, strategies to modulate the electrochemical properties of these oxides for practical use in sacrificial cathodes are briefly explored. Following this, discussions are carried out and perspectives on research that adopts the aforementioned contrasting directions are presented. This perspective explores research on over- and hyper-lithiated oxide materials focusing on approaches to regulate reversibility or irreversibility, aiming to increase the energy density of lithium-ion batteries. Here, an overview of pre-lithiation methodologies is provided, reaction mechanisms are investigated, and strategies to modify electrochemical properties for practical use in sacrificial cathodes are briefly explored, concluding with discussions on contrasting research directions. image