A Dual-Phase Electrolyte for High-Energy Lithium–Sulfur Batteries

摘要

Dissolution of lithium polysulfides (LiPSs) is essential for fast cathodekinetics, but detrimental for anode stability, especially under lean electrolyteconditions. In this work, the phase separation phenomenon betweensolvents with different polarities (tetramethyl sulfone TMS and dibutylether DBE) is utilized to enable the design of a dual-phase electrolyte.High-polarity, high-density TMS–lithium bis(trifluoromethanesulfonyl)imide–ammonium trifluoroacetate as the cathode electrolyte stronglysolvates LiPSs, which propel the sulfur redox reaction. Moreover, thecomposite of DBE and a polymeric ion conductor serves as the anodeelectrolyte. The addition of DBE in the anode side effectively preventsthe crossover of corrosive species (LiPSs and ammonia trifluoroacetate),enabling a significant improvement in Li-metal anode stability. Theelectrode-specific dual-phase electrolyte design provides electrochemicalperformance superior to conventional electrolytes. Without additional electrodeengineering, pouch cells assemble with the dual-phase electrolytecycle under a lean electrolyte (4 μL mg~(?1)) and low-Li-excess condition(N/P = 3) for 120 cycles.