Electrostatic Regulation of Na+ Coordination Chemistry for High-Performance All-Solid-State Sodium Batteries

Ion migration capability and interfacial chemistry of solid polymer electrolytes (SPEs) in all-solid-state sodium metal batteries (ASSMBs) are closely related to the Na⁺ coordination environment. Herein, an electrostatic engineering strategy is proposed to regulate the Na⁺ coordinated structure by employing a fluorinated metal-organic framework as an electron-rich model. Theoretical and experimental results revealed that the abundant electron-rich F sites can accelerate the disassociation of Na-salt through electrostatic attraction to release free Na⁺, while forcing anions into a Na⁺ coordination structure though electrostatic repulsion to weaken the Na⁺ coordination with polymer, thus promoting rapid Na⁺ transport. The optimized anion-rich weak solvation structure fosters a stable inorganic-dominated solid-electrolyte interphase, significantly enhancing the interfacial stability toward Na anode. Consequently, the Na/Na symmetric cell delivered stable Na plating/stripping over 2500 h at 0.1 mA cm^-2. Impressively, the assembled ASSMBs demonstrated stable performance of over 2000 cycles even under high rate of 2 C with capacity retention nearly 100%, surpassing most reported ASSMBs using various solid-state electrolytes. This work provides a new avenue for regulating the Na⁺ coordination structure of SPEs by exploration of electrostatic effect engineering to achieve high-performance all-solid-state alkali metal batteries.