Densely Packed 3D Corrugated Papery Electrodes as Polysulfide Reservoirs for Lithium-Sulfur Battery with Ultrahigh Volumetric Capacity

Designing the optimum cathode configuration for lithium-sulfur (Li-S) batteries has held tremendous scientific momentum to achieve high energy density, fast reaction kinetics, and superior cycle retention. Herein, a self-standing and flexible PPy@rGO/CNTs (PCG) paper as sulfur host is constructed by integrating multiwalled carbon nanotubes into polypyrrole@reduced graphene oxide hybrid structure, rooted from in situ redox reaction and spontaneous assembly of pyrrole and graphene oxide. The three-dimensional (3D) corrugated papery frameworks with carbon nanotube (CNT) pillars deliver a highly conducting pathway for electron and ion transfer. Theoretical calculations indicate that ample nitrogen- and oxygen-containing functional groups can form strong polar-polar interaction with lithium polysulfides. Thus, the assembled lightweight PCG-S electrode exhibits a high gravimetric capacity of 1201.9 mA h g^-1 and retains 727.8 mA h g^-1 at 0.2 C after 450 cycles, remarkable rate performance, and excellent cyclic stability with an ultralow decay rate of 0.044% per cycle during 200 cycles at 1 C. Delightedly, thanks to its unique structure, the volumetric sulfur loading amount in the flexible electrode can reach ca. 0.82 g cm^-3, which endows the cathode with an ultrahigh volumetric capacity of 975 A h L^-1 at 0.2 C simultaneously. This dense monolithic paper appears to be a scalable potential for developing high-performance cathodes in emerging flexible devices.