Insight into bulk charge transfer of lithium metal anodes by synergism of nickel seeding and LiF-Li3N-Li2S co-doped interphase

Abstract Cycling lithium (Li) metal anode with a low negative/positive capacity (N/P) ratio is critical to build high-energy-density Li metal batteries (LMBs). Many strategies focusing on interfacial protection are limited to shallow conditions using excessive Li with a high negative/positive capacity (N/P) ratio > 50. Herein, we demonstrate a deeply enhanced charge transfer kinetic by a rational incorporation of nickel (Ni) seeds in the Li anodes with a tailored interfacial chemistry. The Ni seeds in the bulk Li anode not only act as well-dispersed nucleation sites to enable Ni-seeded growth of granular Li deposits, but also adsorb acetonitrile (AN) molecules when the Ni-seeded Li anodes are paired with an AN-based electrolyte using lithium bis-(fluorosulfonyl)imide as salt, forming a fast Li+ conducting interphase with co-produced LiF, Li3N and Li2S components. These benefits conduct an exchange current density ~ 20 times higher than that of the bare Li in conventional carbonate electrolytes. Stable cycling of LMBs with a practical cathode loading (~ 5 mAh cm−2) and a low N/P capacity ratio of 2 is also demonstrated, showing the prominence of this remedy for developing high-energy-density LMBs.