Electrolyte solvation chemistry to construct an anion-tuned interphase for stable high-temperature lithium metal batteries

Lithium metal batteries are regarded as promising alternative next-generation energy storage systems. However, the unstable anode interphase results in dendrite growth and irreversible lithium consumption with low Coulombic efficiency (CE). Herein, we rationally design a Li+ coordination structure via electrolyte solvation chemistry. Nitrate anions are aggregated in the solvation sheath, even at low concentration in a solvent with moderate solvation ability, which promotes Li+ desolvation and constructs a nitrate anion-tuned interphase. Meanwhile, a high-donor-number solvent is introduced as an additive to strongly coordinate with Li+, which accelerates the ion-transfer kinetics and rate performance. This not only results in micro-sized lithium deposition and a high CE of 99.5% over 3500 h, but also enables superior anode stability even under 50% depth plating/stripping and with a lean electrolyte of 3 g Ah–1 at 50 °C. A lithium–sulfur battery exhibits a prolonged lifespan of 2000 cycles with an average CE of 100%. A full battery using 1x excess lithium exhibits a high capacity near 1600 mAh gS–1 for 100 cycles without capacity loss. Moreover, a 0.55 Ah pouch cell delivers a reversible energy density of 423 Wh kg–1 based on these electrodes and electrolyte.