Most electrolyte additives can improve lithium-ion batteries’ performance by forming a solid electrolyte interphase (SEI) layer on the electrode surface. However, the influences of such additives on the lithium-ion (Li+) solvation structure, particularly on the Li+ desolvation process and its relationship with the attained electrode performance, are mostly overlooked. Herein, we designed a novel ether-based electrolyte to stabilize the alloying anode (e.g., Sb, antimony) by introducing LiNO3 as an additive, where a new interfacial model was constructed to show the additive effect on the kinetic and thermodynamic properties of Li+–solvent–anion complex in the electrolyte. We find that the NO3– anion can weaken the Li+–solvent interaction, promote the Li+ desolvation, particularly mitigate electrolyte decomposition by tuning the location of the Li+–solvent–anion complex on the electrode surface, and then improve electrolyte stability. This is the first time to show that the LiNO3 additive can contribute to a far distance of the Li+–solvent–anion complex from the Sb anode surface rather than the role of forming SEI. Eventually, an extremely high capacity of 664 mAh g–1, extraordinary rate capability over 5C, and good cycle performance over hundreds of cycles were obtained. This work provides new insight into understanding the role of additives more comprehensively and offers guidance in designing electrolytes for stable lithium-ion batteries using alloying anodes.