Suppression of Interphase Dissolution Via Solvent Molecule Tuning for Sodium Metal Batteries

Abstract

Solvent molecule tuning is used to alter redox potentials of solvents or ion‐solvent binding energy for high‐voltage or low‐temperature electrolyte. Herein, we propose an electrolyte design strategy that effectively suppresses solid electrolyte interphase (SEI) dissolution and passivates highly‐reactive metallic Na anode via solvent molecule tuning. With rationally lengthened phosphate backbones with –CH2– units, the low‐solvation tris(2‐ethylhexyl) phosphate (TOP) molecule effectively weakens the solvation ability of carbonate‐based electrolytes, reduces the free solvent ratio and enables an anion‐enriched primary Na+ ion solvation sheath. The decreased free solvent and compact lower‐solubility interphase established in this electrolyte prevent electrodes from the continuous SEI dissolution and parasitic reactions at both room temperature (RT) and high temperature (HT). As a result, the Na/Na3V2(PO4)3 cell with the new electrolyte achieves impressive cycling stability of 95.7% capacity retention after 1800 cycles at 25 °C, and 62.1% capacity retention after 700 cycles at 60 °C. Moreover, TOP molecule not only maintains the nonflammable feature of phosphate but also attains a higher thermal stability, which endows the electrolyte with high safety and thermal stability. Our design concept for electrolytes offers a promising path to long‐cycling and high safe sodium metal batteries.This article is protected by copyright. All rights reserved

Highly Performing Sodium Metal Batteries Reinforced by a Self-Regulated Dual-Layered Solid Electrolyte Interphase via a Metal–Organic Framework

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Sulfur-Containing Inorganic-Rich Interfacial Chemistry Empowers Advanced Sodium-Ion Full Batteries

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