Electrocatalytic Cathodes Based on Cobalt Nanoparticles Supported on Nitrogen-Doped Porous Carbon by Strong Electrostatic Adsorption for Advanced Lithium-Sulfur Batteries

Abstract

Energy demands have increased rapidly over the previous decades, leading to new innovations in the energy storage field. One of the candidates for advanced energy storage is the lithium-sulfur battery. This Li-S battery is advantageous for its relatively high volumetric and gravimetric energy density and affordability. However, the widespread use and manufacturing of Li-S batteries are hampered by accelerated capacity decay upon cycling due to volume changes at the cathode, a "shuttle effect"of soluble lithium polysulfide (LPS) dissolution from cathode, and kinetically sluggish redox processes. In this study, we have designed a new and unique electrocatalytic cathode composed of ultrasmall cobalt nanoparticles embedded into nitrogen-doped porous carbon to host sulfur for the application of Li-S batteries via strong electrostatic adsorption (SEA). The large surface area (SABET = 2355 m2 g-1) and uniform distribution of ultrafine cobalt nanoparticles embedded in the nitrogen-doped carbon composite enables a high sulfur loading and significantly immobilizes soluble LPS during battery cycling while improving the electrochemical performance through catalytic effects. A sulfur doping of 71 wt % was attained, affording an initial specific capacity of 1219 mAh g-1 at 0.1 C (1C = 1675 mAh g-1) and Coulombic efficiency (99.1%) due to the cathodic multifunctional arrangements. At 0.5 C, the battery initially yields a specific capacity of 968 mAh g-1 and decreases to 858 mAh g-1 after 100 cycles. The battery delivered a specific capacity of 579 mAh g-1 after 300 cycles at 1 C and an exceptionally low capacity fade of 0.07% per cycle. This study demonstrates that SEA can be utilized to incorporate highly active metal nanoparticles into sulfur hosts to advance their electrocatalytic function and thereby advance Li-S batteries' stability.