CNT encapsulated nickel-doped hollow porous manganese oxide scaffold as a sulfur cathode host for Li–S battery applications

Abstract

Recently, lithium–sulfur batteries have captivated those in the energy storage industry due to the low cost and high theoretical capacity of the sulfur cathode (1675 mA h g⁻¹). However, to enhance the practical usability of Li–S batteries, it is crucial to address issues such as the insulating nature of sulfur cathodes and the high solubility of lithium polysulfides (LiPS, Li₂S_x, 4 ≤ n ≤ 8) that cause poor active sulfur utilization. Designing innovative sulfur hosts can effectively overcome sulfur bottlenecks and achieve stable Li–sulfur batteries. This study presents novel hollow porous structures of Ni-doped MnO₂ encapsulated with multi-walled carbon nanotubes (CNTs) used as an efficient host material for a sulfur cathode. These hollow, porous, hierarchical structures, combined with transition metal (Ni) doping, serve to enhance the adsorption of LiPS and contribute to improved redox kinetics during the electrochemical process. Furthermore, the remarkable conductivity provided by the CNT encapsulation significantly enhances the sulfur and LiPS conversion kinetics, effectively suppressing the undesirable shuttling effect and promoting efficient utilization of the active material. The prepared cathode (S@Ni-MO/CNT) not only meets but exceeds expectations, delivering superior cyclability, rate capability results, and improved Li-diffusion properties. These results underscore the effectiveness of constructing novel host materials for sulfur cathodes, leaving no doubt about the potential of this novel host material to address the challenges in lithium–sulfur batteries.