Nitrate Additives Coordinated with Crown Ether Stabilize Lithium Metal Anodes in Carbonate Electrolyte

Lithium metal anodes (LMAs) are promising for next‐generation batteries but have poor compatibility with the widely used carbonate‐based electrolytes, which is a major reason for their severe dendrite growth and low Coulombic efficiency (CE). A nitrate additive to the electrolyte is an effective solution, but its low solubility in carbonates is a problem that can be solved using a crown ether, as reported. A rubidium nitrate additive coordinated with 18‐crown‐6 crown ether stabilizes the LMA in a carbonate electrolyte. The coordination promotes the dissolution of NO 3 − ions and helps form a dense solid electrolyte interface that is Li 3 N‐rich which guides uniform Li deposition. In addition, the Rb (18‐crown‐6) + complexes are adsorbed on the dendrite tips, shielding them from Li deposition on the dendrite tips. A high CE of 97.1% is achieved with a capacity of 1 mAh cm −2 in a half cell, much higher than when using the additive‐free electrolyte (92.2%). Such an additive is very compatible with a nickel‐rich ternary cathode at a high voltage, and the assembled full battery with a cathode material loading up to 10 mg cm −2 shows an average CE of 99.8% over 200 cycles, indicating a potential for practical use.