High Volumetric Capacity FeS2/SPAN Composite with Promoted Kinetics for Li-S Battery.

Abstract

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, FeS₂ 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 FeS₂/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 FeS₂/SPAN composite cathode presents a high specific capacity of 683.56 mAh g^-1 after 140 cycles at 0.5 C, corresponding to a 91.90% retention, and achieves a volumetric capacity of 716.19 Ah L^-1 at 0.2 C with a high areal mass loading of 6.1 mg cm^-2. 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.