Molecularly Integrated Additive Engineering for Rapid Rejuvenation of Spent Electrolyte

ABSTRACT The escalating deployment of lithium‐ion batteries (LIBs) necessitates sustainable electrolyte recycling, yet conventional methods fail to address the intertwined challenges of hydrofluoric acid (HF) generation, moisture ingress, and transition metal (TM) ion dissolution in an economical and effective way. Here, we present a molecularly integrated additive, tetrakis(trimethylsilyl)tetrazene (TMSTz), engineered to synchronously neutralize HF, scavenge water, chelate TM ions, and construct stable electrode interfaces via redox‐driven polymerization. Density functional theory and experimental analyses reveal TMSTz's dual redox‐active centers enable spontaneous HF conversion, water sequestration and TM removal, while forming LiF‐rich, ion‐conductive solid‐electrolyte interphases. NCM811/graphite pouch cells with TMSTz‐regenerated electrolytes achieve 81.2% capacity retention after 500 cycles at 1C, alongside suppressed thermal runaway and dendrite‐free Li plating. This atomic‐to‐system design establishes a scalable paradigm for closed‐loop electrolyte upcycling, bridging resource sustainability and high‐performance LIBs.