Regulating Interface Dipole Interaction between Ethers and Active Species Toward Highly Stable Li-SPAN Batteries.

Abstract

Sulfurized polyacrylonitrile (SPAN) is recognized as a promising organic cathode for long-lifespan lithium metal batteries. Nevertheless, the irreversible cleavage/formation of multiple sulfur-sulfur (S-S) bonds of SPAN within conventional ether-based electrolytes results in loss of active S species, severe capacity fading and shuttle effects. Herein, we propose a new electrolyte based on dipropyl ether (PE) solvent for Li-SPAN batteries. Benefiting from the particular chain-coordination structure and weak dipole interactions with Li⁺ and active species, the resulting electrolyte not only achieves low desolvation energy barrier and high Li⁺ transference number, but also displays stable electrolyte-electrode interface (EEI). Consequently, the full cells utilizing this electrolyte exhibit good cyclability, outstanding capacity retention and superior extreme-temperature (-50 °C to 50 °C) performance. Furthermore, the Ah-scale pouch cell with lean electrolyte (2.5 g Ah^-1) achieves record cycle stability with 96.5 % capacity retention after 75 cycles, which deliver an initial specific energy density of 150 Wh kg^-1 (based on the weight of the entire cell). Impressively, this strategy demonstrates universality in a series of organic electrodes employing with PE-based electrolytes. This work highlights the strategy for modulating the dipole interaction at EEI for long-lifespan Li-organic batteries at extreme conditions.