Abundant Defects-Induced Interfaces Enabling Effective Anchoring for Polysulfides and Enhanced Kinetics in Lean Electrolyte Lithium–Sulfur Batteries

Abstract

In response to the concept of “compact energy storage”, research on electrolyte dosage dwindling is definitely efficient owing to present electrolyte usage up to 70 wt % in a cell. While less electrolyte usage leads to slow reaction kinetics. Herein, a heterojunction, MoP/MoS2 core with much defects and vacancies coated by porous carbon shell, is synthesized. Besides, the small particle size of MoP/MoS2@C facilitates a close packing to form a dense and porous modified layer on PP-based (F-PP) separator. The heterojunction with defects exposes abundant interfaces and assures an adequate local electrolyte availability and an improved electrolyte affinity that are beneficial for Li+ transfer. When using F-PP separator, Li–S cell performs well in the lean electrolyte. Apart from a high discharging capacity of 517.1 mAh g–1 at 5 C in E/S = 10 (only half benchmark dosage), the cell realizes a favorable stability at C/2 over 500 cycles even in E/S = 7 (0.065% decay per cycle), demonstrating an effective polysulfides (PS) shuttling relief and reversibility of PS-relating chemical conversion. All these enhanced electrochemical behaviors in lean electrolyte result from a three-in-one strategy realized by defects-included MoP/MoS2@C heterojunction, including incorporating the lithiuphilic and sulfophilic sites for PS confinement and electrocatalysis triggered by abundant S vacancies and Lewis and Brønsted acid sites.