Intramolecular charge redistribution of phosphate anions enabling ultrahigh-voltage lithium metal battery of 600 Wh kg-1.

The advancement of ultrahigh-voltage lithium metal batteries (LMBs) is hindered by the lack of efficient guidelines for electrolyte material development, with current approaches still largely relying on inefficient trial-and-error methods. Herein, we report a high-performance additive design and screening strategy. A library of phosphorus-centered candidates (containing 15,200 molecules) is constructed by simultaneously introducing electron-withdrawing and electron-donating groups to induce intramolecular charge redistribution and tune the electrochemical properties of the molecules. Through unsupervised machine learning-assisted screening, lithium diperfluoropinacolatophosphate (LiDPFP) is identified as the optimal candidate. LiDPFP features localized electron-deficient and electron-rich regions, which tune interfacial reactivity and enhance lithium ion (Li+) coordination to promote contact ion pairs. This unique structure leads to the formation of a phosphorus-oxygen polymer-rich cathode electrolyte interphase and a Li2O (lithium oxide)-rich solid electrolyte interphase, effectively suppressing cathode degradation and lithium dendrite growth. Consequently, the as-assembled NCM811||Li cells exhibit stable cycling at 4.8 volts over a wide temperature range from -40° to 80°C. A practical 4.7-volt pouch cell with the energy density of 628 Wh kg-1 (watt-hours per kilogram) exhibits an 80% capacity retention rate after 112 cycles. This work combines machine learning with molecular design, exhibiting a paradigm for practical ultrahigh-energy-density LMBs.