In situ regulated solid electrolyte interphase via reactive separators for highly efficient lithium metal batteries

Lithium metal batteries (LMBs) with high energy densities are regarded as the most promising candidates for next-generation energy storage. However, the practical applications of LMBs have long been limited by the uncontrollable lithium (Li) dendrite growth resulting from the unstable solid electrolyte interphase (SEI). We herein proposed an in situ regulated SEI that is rationally designed by the introduction of a functional separator. In details, a lignosulfonate film with intrinsic reactivity toward Li metal is integrated onto the surface of a routine separator. The as-regulated SEI possesses favorable inorganic-rich species and inherited aromatic groups, synergistically endowing rapid ion transport capability and superior mechanical stability. Consequently, the in-situ stabilization of the electrode/electrolyte interfaces contributes to a reduced voltage polarization and a remarkably prolonged cycle life of the working LMBs, which intrinsically indicates a more uniform Li electroplating manner with well-suppressed dendrite formation. This work highlights a facile yet highly efficient strategy of designing stable SEI through reactive separator and affords fresh insights into the interface regulation for Li anode protection in practical LMBs.