Construction of high-performance sulfurized poly(acrylonitrile) cathodes for lithium-sulfur batteries via catalytic and conductive regulation

Abstract

Sulfurized poly(acrylonitrile) (SPAN) is an attractive cathode material for lithium-sulfur (Li-S) batteries with demonstrated stable cycling, reduced polysulfide shuttle, and low self-discharge rates. However, the sluggish reaction kinetics of SPAN cathodes greatly limit their capacity output and rate performance. Here, we report novel Se 0.03 SPAN/CNT-3 nanofibers as sulfur cathode materials, aiming to promote the redox kinetics of sulfur conversion by imparting both electronic conductivity and catalytic activity to SPAN. Specifically, selenium is uniformly distributed in the Se 0.03 SPAN/CNT-3 composite through Se–S bonds and facilitates the fast transport of Li-ions. While the CNTs embedded in nanofibers enable high electronic conductivity and provide extra contact between electrode and electrolyte, offering smooth transport channels for both electrons and ions. As a result, the Se 0.03 SPAN/CNT-3 cathode presents a high reversible capacity (791 mAh g −1 composite at 0.2 C), superior rate performance (638 mAh g −1 composite at 4 C), and extremely stable cycle life over 800 cycles. In particular, when tested in practical conditions of high areal loading (Se 0.03 S: 5.2 mg cm −2 ) and lean electrolyte (E/Se 0.03 S: 10 μL mg −1 ), this cathode delivers high reversible capacities of 733 mAh g −1 composite (0.1 C) and 672 mAh g −1 composite (0.2 C), demonstrating its great potential for future application. • A novel Se 0.03 SPAN/CNT-3 nanofibers material was prepared and studied as the cathode for Li-S batteries. • The electrode reaction kinetics was greatly enhanced by the catalytic and conductive regulation. • A remarkable active materials utilization of 94.8 % was achieved by the Se 0.03 SPAN/CNT-3 cathode at 0.2 C. • High reversible capacity and good cycle stability were maintained under high areal loading and lean electrolyte conditions.