Suspended Lithium Nitrate-Based Electrolytes: Electrostatic Interactions for Mutually Rewarding Interface Optimization Strategies.

Designing a stable electrode-electrolyte interface (EEI) is critical for developing lithium metal batteries with high energy density, enhanced safety, and broad applicability. Lithium nitrate (LiNO) is an attractive sacrificial additive for lithium metal anode, while its poor solubility in high-voltage-resistant ester/nitrile electrolytes severely limits its utility. To solve it, a novel suspension electrolyte strategy is proposed that uniformly disperses LiNO particles in an ester/nitrile mixed electrolyte to stabilize the electrode interface. The suspended LiNO particles exhibit dual functionality: LiNO enhances the compatibility between the electrode and the electrolyte by affecting the Li solvation environment and preferentially adsorb on the electrode surface; moreover, the in situ formed LiNO-rich EEI by LiNO decomposition with accelerated Li⁺ transport kinetics, effectively suppresses parasitic reactions and improves rate performance. The optimized electrolyte makes Li||NCM523 battery run stably for 100 cycles with a high capacity retention of 90.05% at 60 °C and stably operated at low temperature (-10 °C). Moreover, the electrolyte shows excellent electrochemical stability at a high-voltage of 4.5 V. This work presents a dual-strategy advancement featuring wide-temperature electrolyte formulation and precision interface engineering, synergistically achieving high-specific-energy lithium metal batteries.