Rational Design of Multifunctional Integrated Host Configuration with Lithiophilicity-Sulfiphilicity toward High-Performance Li-S Full Batteries

High-energy-density Li-S batteries are considered one of the next-generation energy storage systems, but the uncontrolled Li-dendrite growth in Li metal anodes and the shuttling of polysulfides in S cathode severely impede the commercial development of Li-S batteries. Herein, a conductive composite architecture that is made up of bio-derived N-doped porous carbon fiber bundles (N-PCFs) with co-imbedded cobalt and niobium carbide nanoparticles is employed as a multifunctional integrated host for simultaneously addressing the challenges in both Li anodes and S cathodes. The implantation of Co and NbC nanoparticles bestows the N-PCFs matrix with synergistically enhanced degree of graphitization, electrical conductivity, hierarchical porosity, and surface polarization. Theoretical calculations and experimental results show that NbC with specific lithiophilic and sulfiphilic features can synchronously regulate the Li and S electrochemistry by realizing homogeneous lithium deposition with suppressed Li-dendrite growth and exerting catalytic effects for promoting the polysulfide conversion together with fast Li2S nucleation. Hence, the assembled Li-S full batteries exhibit a superb rate capability (704 mAh g(-1)at 5 C) and cycling life (approximate to 82.3% capacity retention after 500 cycles) at a sulfur loading over 3.0 mg cm(-2), as well as high reversible areal capacity (>6.0 mAh cm(-2)) even at a higher sulfur loading of 6.7 mg cm(-2).

Automated summary

In this study, a conductive composite architecture consisting of bio-derived N-doped porous carbon fiber bundles with embedded cobalt and niobium carbide nanoparticles was used to address the challenges in Li-S batteries. It was found that the niobium carbide nanoparticles could regulate the lithium and sulfur electrochemistry simultaneously, resulting in excellent rate performance and cycling life of the assembled Li-S batteries.