Synergistic Cathode-Electrolyte Engineering for Enhanced Longevity in Li-S Batteries.

Abstract

Due to the notorious shuttle effect and the uneven deposition of lithium ions under high current conditions, lithium-sulfur batteries with ultra-high sulfur loading struggle to achieve stable long-cycle performance. Herein, a novel MBene-based composite material is prepared using the ultrasonic freeze etching method as a cathode host. The shuttle effect is effectively inhibited, thanks to its unique structure and abundant active sites. Moreover, a small amount of Na2SeO3 is introduced into the electrolyte to further enhance the long-cycle performance. Due to the "reverse tip effect," where sodium ions preferentially deposit over lithium ions, the growth of lithium dendrites is effectively suppressed. Remarkably, the cell with the novel cathode and electrolyte design exhibits an initial capacity of 778.2 mAh g-1 and sustains stability for up to 850 cycles with a capacity retention rate of 93.6% and a sulfur loading of 10.62 mg cm-2. The synergistic strategy of optimizing both cathode and electrolyte systems effectively mitigates the shuttle effect and suppresses lithium dendrite growth, offering an innovative approach to designing ultra-high-sulfur-loading lithium-sulfur batteries with extended lifespans.