Sphere-in-fiber hybrid of N-doped carbon/cerium dioxide as an interlayer material with superior electrocatalytic performance for lithium sulfide precipitation and conversion

A Review of Electrospun Carbon-Based Nanofibers Materials used in Lithium-Sulfur Batteries

Commercial lithium-ion batteries are gradually approaching their theoretical specific energy, which cannot meet the fast-growing energy storage demands. Lithium-sulfur (Li-S) batteries are anticipated to supersede lithium-ion batteries as the next-generation energy storage system owing to their high atheoretical specific capacity (1675 mAh g-1) and energy density (2600 Wh kg-1). Nonetheless, Li-S batteries encounter several challenges, including the inadequate conductivity of sulfur and lithium sulfide, sulfur's volume expansion, and the shuttle effect of lithium polysulfides, all of which significantly impact the practical utilization of Li-S batteries. Electrospun carbon-based nanofibers can simultaneously resolve these issues with their economical preparation, distinctive nanostructure, and exceptional flexibility. This review presents the most recent research findings on electrospun carbon-based nanofibers materials serving as sulfur hosts and interlayer components in Li-S batteries. We analyzed the impact of the material's structural design on the performance of Li-S batteries and the relative underlying mechanism. Finally, the current challenges and issues faced by carbon-based nanofibers composites in the application of Li-S batteries are summarized, and the future development trajectory are outlined.

Polyaniline-Coated Porous Vanadium Nitride Microrods for Enhanced Performance of a Lithium-Sulfur Battery

To solve the slow kinetics of polysulfide conversion reaction in Li-S battery, many transition metal nitrides were developed for sulfur hosts. Herein, novel polyaniline-coated porous vanadium nitride (VN) microrods were synthesized via a calcination, washing and polyaniline-coating process, which served as sulfur host for Li-S battery exhibited high electrochemical performance. The porous VN microrods with high specific surface area provided enough interspace to overcome the volume change of the cathode. The outer layer of polyaniline as a conductive shell enhanced the cathode conductivity, effectively blocked the shuttle effect of polysulfides, thus improving the cycling capacity of Li-S battery. The cathode exhibited an initial capacity of 1007 mAh g^-1 at 0.5 A g^-1, and the reversible capacity remained at 735 mAh g^-1 over 150 cycles.

An interwoven carbon nanotubes/cerium dioxide electrocatalyst accelerating the conversion kinetics of lithium sulfide toward high-performance lithium-sulfur batteries

Rechargeable lithium-sulfur (Li-S) batteries with environmental friendliness, low price, high specific capacity and energy density could be promising alternatives to a larger scope of energy storage in the near future. However, the practical application is impeded by the intrinsic insulation of sulfur and the fatal shuttle effect during the (dis)charging process. Herein, we report a strategy to address the drawbacks of Li-S batteries by inserting an interwoven carbon nanotubes/cerium dioxide electrocatalyst interlayer material (CNTs@CeO₂) between the sulfur cathode and the separator. In the CNTs@CeO₂ composite, the conductive network interwoven by CNTs facilitates electron transportation, and the abundant active sites in CeO₂ cavities ensuring the adsorption-catalytic conversion of lithium polysulfides as well as the hollow structure of CeO₂ is conducive to rapid electrolyte penetration and lithium ion migration. Benefiting from such multifunction, the battery with a CNTs@CeO₂ interlayer exhibits superior rate performance, delivering a high discharge specific capacity of 1040.6 mAh g^-1 at 0.2C and 652.5 mAh g^-1 at 4C, respectively. Moreover, the battery shows excellent cycling stability with a capacity decay rate of 0.064% per cycle at 1C over 1000 cycles. These promising results demonstrate the potential application of CeO₂-based electrocatalysts for high energy density Li-S batteries.