Fibrous organosulfur cathode materials with high bonded sulfur for high-performance lithium-sulfur batteries

Abstract

Organosulfur compounds are promising cathode materials for lithium-sulfur (Li–S) batteries because of their sustainability, lightweight, and environmental kindness. Recently, sulfurized-polyacrylonitrile (SPAN) with chemically anchored sulfur has drawn tremendous attention. However, the low sulfur content in the SPAN (mostly below 50 wt%) hampers its practical application as a cathode material in Li–S batteries. Herein, we introduce trithiocyanuric acid (TTCA) with polyacrylonitrile (PAN) to synthesize fibrous sulfurized TTCA/PAN (STTCA@SPAN) via an electrospinning technique followed by inverse vulcanization. The thiol groups in TTCA are more readily oxidizing in the sulfurization process and increased the sulfur content to 58 wt% in the fibrous STTCA@SPAN composite. The chemically bonded short-chain sulfur species endow STTCA@SPAN cathode excellent compatibility with carbonate-based electrolytes. Moreover, the fibrous cathodes exhibit an initial discharge capacity of 1301 mAh g−1, excellent cycle stability over 400 cycles, and high-rate capabilities of 1028, 957, 827, and 660 mAh g−1 at 0.2, 0.5, 1.0, 2.0 C-rates, respectively. The cross-linked fibrous morphology maintains the structural stability of the cathode after a continuous charge/discharge process.