Chlorination design for highly stable electrolyte towards high mass loading and long cycle life sodium-based dual-ion battery.

Sodium-based dual ion batteries (SDIBs) have garnered significant attention as novel energy storage devices offering the advantages of high-voltage and low-cost. Nonetheless, conventional electrolytes exhibit low resistance to oxidation and poor compatibility with electrode materials, resulting in rapid battery failure. In this study, for the first time, we propose a chlorination design of electrolytes for SDIB. Using ethyl methyl carbonate (EMC) as a representative solvent, chlorine-substituted EMC (Cl-EMC) not only demonstrates increased oxidative stability ascribed to the electron-withdrawing characteristics of chlorine atom, electrolyte compatibility with both the cathode and anode have also been greatly improved by forming Cl-containing interface layers. Consequently, a discharge capacity of 104.6 mAh g -1 within voltage range of 3.0-5.0 V is achieved for Na||graphite SDIB that employs a high graphite cathode mass loading of 5.0 mg cm -2 , along with almost no capacity decay after 900 cycles. Notably, the Na||graphite SDIB can be revived for additional 900 cycles through the replacement of a fresh Na anode. As the mass loading of graphite cathode increased to 10 mg cm -2 , Na||graphite SDIB is still capable of sustaining over 700 times with ≈100% capacity retention. These results mark the best outcome among reported SDIBs. This study corroborates the effectiveness of chlorination design in developing high-voltage electrolytes and attaining enduring cycle stability of Na-based energy storage devices. This article is protected by copyright. All rights reserved.