Electrolyte Engineering for Rejuvenating Inactive Lithium and Constructing High-Performance Lithium Metal Batteries

Lithium metal batteries with gel polymer electrolytes have garnered significant interest due to their high energy-density and enhanced safety. However, the persistent challenges of inactive lithium accumulation and the unstable solid-electrolyte interphase (SEI) remain significant obstacles to their practical application. To mitigate these issues, a tiny amount of iodobenzene is employed as a source of triiodine/iodine ion (I₃ ^-/I^-) redox couple, exhibiting dual functionality in rejuvenating inactive lithium and simultaneously optimizing the SEI composition. Combined by experimental characterization and theoretical analysis, it is demonstrated that the I₃ ^-/I^- redox couple can actively participate in lithium regeneration chemistry to compensate for irreversible lithium loss, while promoting the formation of a robust LiI-endorsed and LiF-rich SEI layer. Consequently, symmetrical Li batteries with the engineered electrolyte achieve an improved cycling performance of 4000 h at a current density of 0.2 mA cm^-2. Moreover, the assembled NCM811||Li batteries perform an impressive capacity retention of 70.31% after cycling for 720 cycles at 3C, and even at 4C, an equally remarkable capacity retention rate of 75.94% is maintained after 650 cycles.