High Volumetric Capacity FeS/SPAN Composite with Promoted Kinetics for Li-S Battery.

Sulfurized polyacrylonitrile (SPAN) exhibits a unique solid-phase conversion mechanism in carbonate electrolytes during electrochemical reactions, which avoids the dissolution of polysulfides and self-discharge. However, the limited sulfur content, unsatisfactory redox kinetics, and low volumetric energy density restrict the development of SPAN. Herein, FeS nanodots and carbon nanotubes are proposed to composite with SPAN to achieve better dynamic performance and higher volumetric capacity at higher sulfur content. The as-prepared FeS/SPAN composite is designed using spray granulation to obtain interspersed and interlaced secondary particles with abundant ion/electron transport channels, which ensures a more stable cathode interface and exhibits excellent rate performance. As a result, the FeS/SPAN composite cathode presents a high specific capacity of 683.56 mAh g after 140 cycles at 0.5 C, corresponding to a 91.90% retention, and achieves a volumetric capacity of 716.19 Ah L at 0.2 C with a high areal mass loading of 6.1 mg cm. The outstanding electrochemical performance exhibited at both high sulfur content and mass loading provides a new approach for designing higher energy density sulfur-based cathode materials in the future.