Hyphae Carbon Coupled with Gel Composite Assembly for Construction of Advanced Carbon/Sulfur Cathodes for Lithium-Sulfur Batteries.

The design and fabrication of novel carbon hosts with high conductivity, accelerated electrochemical catalytic activities, and superior physical/chemical confinement on sulfur and its reaction intermediates polysulfides are essential for the construction of high-performance C/S cathodes for lithium-sulfur batteries (LSBs). In this work, a novel biofermentation coupled gel composite assembly technology is developed to prepare cross-linked carbon composite hosts consisting of conductive Rhizopus hyphae carbon fiber (RHCF) skeleton and lamellar sodium alginate carbon (SAC) uniformly implanted with polarized nanoparticles (VO, Ag, Co, etc.) with diameters of several nanometers. Impressively, the RHCF/SAC/VO composites exhibit enhanced physical/chemical adsorption of polysulfides due to the synergistic effect between hierarchical pore structures, heteroatoms (N, P) doping, and polar VO generation. Additionally, the catalytic conversion kinetics of cathodes are effectively improved by regulating the 3D carbon structure and optimizing the VO catalyst. Consequently, the LSBs assembled with RHCF/SAC/VO-S cathode show exceptional cycle stability (capacity retention rate of 94.0% after 200 cycles at 0.1 C) and excellent rate performance (specific capacity of 578 mA h g at 5 C). This work opens a new door for the fabrication of hyphae carbon composites via fermentation for electrochemical energy storage.