Modulating reactivity and stability of metallic lithium via atomic doping†
Many approaches have been described to address challenges in metallic Li anodes; but they rarely modulate the inherent chemical reactivities. Here we describe a general approach for modulating Li metal properties and enabling stable metal batteries by doping with ∼0.1 at% Ag or Al. The dopants were atomically dispersed in the vacant face-centered sites of the body-centered cubic Li crystals and pull electrons strongly due to higher electronegativity (Ag: 1.98; Al: 1.61 vs. Li: 0.98). As a result, the doped Li anodes have increased work function with reduced chemical reactivity and remained shiny in dry air for months. They also exhibited enhanced Li+/Li redox kinetics and generated thinner but stronger solid-electrolyte interphases in carbonate electrolytes. The dopant atoms are lithophilic and have stronger binding with Li adatoms, which guide uniform Li deposition and ensures dendrite-free Li interface during battery cycling. Overall, the doped anodes enabled stable operations of not only high current symmetric cells but also practical full cells in which Ni-rich layered cathodes were paired with 30 μm anodes and 7 μL electrolytes. The doping approach is facile and scalable, and opens up new and promising opportunities for designing practical high energy density metal batteries.