Dendrite-free lithium deposition enabled by interfacial regulation via dipole-dipole interaction in anode-free lithium metal batteries

The structure and composition of solid electrolyte interphase (SEI) on lithium (Li) electrode surface dictate Li plating/stripping behavior in Li metal batteries (LMBs), which is determined by the solvation structure of Li+ ion in the electrolyte. Herein, it is found that the dipole-dipole interaction between the electron-deficient boron (B) site in 3-(trifluoromethyl) phenylboronic acid (FBA) molecule and the TFSI− anion is capable of reducing the reduction stability of the TFSI− anion, and meanwhile promoting the participation of abundant TFSI− anions in the solvation sheath of Li+ ion in the electrolyte. Moreover, as an anion receptor, the FBA molecule with strong anionic affinity effectively enhances the contribution of NO3− anions in forming the SEI. Therefore, a favorable interphase enriched with LiF and Li3N is successfully constructed on the surface of Li electrode, which presents high mechanical strength, high Li+ ion conductivity and electronic insulation. As a result, Li plating/stripping reversibility can extend to over 1200 h with a low polarization potential of 42 mV in this anion receptor modified electrolyte. And the as-assembled anode-free Cu||LFP full cells can deliver excellent capacity retention of above 73.6% after 180 cycle.