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

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.