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

摘要

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 PPyprGO/CNTs (PCG) paper as sulfur host is constructed by integrating multiwalled carbon nanotubes into polypyrrolepreduced 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(-1), 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.