High‐Performance Flexible Sulfur Cathodes with Robust Electrode Skeletons Built by a Hierarchical Self‐Assembling Slurry

Abstract

Abstract The electrochemical performance of lithium–sulfur batteries is fundamentally determined by the structural and mechanical stability of their composite sulfur cathodes. However, the development of cost‐effective strategies for realizing robust hierarchical composite electrode structures remains highly challenging due to uncontrollable interactions among the components. The present work addresses this issue by proposing a type of self‐assembling electrode slurry based on a well‐designed two‐component (polyacrylonitrile and polyvinylpyrrolidone) polar binder system with carbon nanotubes that forms hierarchical porous structures via optimized water‐vapor‐induced phase separation. The electrode skeleton is a highly robust and flexible electron‐conductive network, and the porous structure provides hierarchical ion‐transport channels with strong polysulfide trapping capability. Composite sulfur cathodes prepared with a sulfur loading of 4.53 mg cm−2 realize a very stable specific capacity of 485 mAh g−1 at a current density of 3.74 mA cm−2 after 1000 cycles. Meanwhile, a composite sulfur cathode with a high sulfur loading of 14.5 mg cm−2 in a lithium–sulfur pouch cell provides good flexibility and delivers a high capacity of 600 mAh g−1 at a current density of 0.72 mA cm−2 for 78 cycles.

Keywords

• electrode skeleton structures
• flexible lithium–sulfur batteries
• hierarchical pores
• phase separation
• self‐assembling electrode slurry