Enhancing the Performance of Aqueous Lithium‐Ion Batteries via N‐Methylpyrrolidone Additive

Abstract

ABSTRACT Aqueous lithium‐ion batteries (ALIBs) have garnered significant attention in the field of energy storage due to their inherent safety. However, their practical application is severely constrained by a narrow electrochemical window and electrolyte crystallization at low temperatures. In this study, a modified electrolyte employed the N‐Methylpyrrolidone (NMP) as the additive designated as P‐N2 was developed. Physicochemical characterization (DSC, Raman, and NMR) revealed that the introduction of the NMP component effectively restructured the Li + solvation sheath, thereby suppressing the activity of water molecules and lowering the freezing point. Electrochemical evaluations demonstrated that, at −20°C, full cells utilizing the P‐N2 electrolyte (LiMn 2 O 4 ||NaTi 2 (PO4) 3 /C) exhibited good rate performance and better cycling stability, retaining high capacity even after 1500 cycles. Further interfacial analysis (SEM/XPS) revealed that P‐N2 induced the formation of a dense solid electrolyte interphase (SEI) film, thereby elucidating the mechanism underlying the observed performance enhancement.