Atomic V- and Co-Modified Ketjen Black–Sulfur Composite for High-Performance Lithium–Sulfur Batteries

Abstract

In the present study, we encapsulated sulfur with atomic vanadium (V)- and cobalt (Co)-modified Ketjen black (VCKBS) to hinder the shuttle mechanism and enhance the redox kinetics in Li–S batteries. The synthesized composite provided plenty of interfacial active sites and assured smooth electron transfer, which assisted in attaining the balance of the enhanced catalytic activity due to Co and the adsorption ability mainly derived from V. Consequently, the Li–S cells having an optimized composition presented alleviated shuttle effect, enhanced sulfur utilization and conversion efficiency, and showed stable cycling performance and an outstanding rate performance with an initial capacity of 1329 mAh g–1, which was maintained as 1249 mAh g–1 after 100 cycles. Due to impressive experimental specific capacities, the system-level specific energies and energy densities were also predicted using the 1st and 100th discharge capacities. Compared to regular Ketjen black-based cathodes, VCKBS cathodes showed 1342 and 568% improvement in the system-level energy density and specific energy based on the 100th discharge capacities, respectively. This indicates that VCKBS cathodes synthesized in a facile manner are advantageous for higher sulfur loadings at electrolyte-depleted cells and represent a viable endeavor to develop highly stable Li–S batteries.

Electrochemical Impedance Spectroscopy of Li‐S Batteries: Effect of Atomic Vanadium‐ and Cobalt‐Modified Ketjen Black‐Sulfur Cathode, Sulfur Loading, and Electrolyte‐to‐Sulfur Ratio

“…In our previously reported work, the synthesis of the materials was confirmed by various characterization methods [26] . The SEM images and EDX mapping of the materials are provided in Figure S1.…”

“…In our previously reported work, the synthesis of the materials was confirmed by various characterization methods. [26] The SEM images and EDX mapping of the materials are provided in Figure S1. To investigate the effect of the S loading and the E/S ratio on the cell resistances, LiÀ S cells were fabricated with E/S ratios of 6, 13, 20, 35 mL g À 1 and S loadings of 0.8, 1.2, and 3 mg cm À 2 using KBS and VCKBS composites as cathode materials.…”

“…[26] When compared to the sulfur cathode encapsulated with pure Ketjen black, LiÀ S cells with the VCKBS cathodes showed significantly improved performance due to the presence of abundant interfacial active sites; the addition of Co provided catalytic activity, whereas V offered polysulfide adsorption capability. [26] Therefore, to better understand the limits of the proposed material, the impact of prepared cathodes on the cell resistance and, hence, the LiÀ S battery performance is mechanistically studied here. Moreover, the impact of S loading and E/S ratio on the cell resistance of both cathode materials (VCKBS and KBS) is analyzed via the EIS technique.…”

“…In a recent study, we described a straightforward, viable, and cheap method for producing an atomic vanadium (V) and cobalt (Co) modified Ketjen black (KB)‐sulfur composite (VCKBS) as a cathode host for Li−S batteries [26] . When compared to the sulfur cathode encapsulated with pure Ketjen black, Li−S cells with the VCKBS cathodes showed significantly improved performance due to the presence of abundant interfacial active sites; the addition of Co provided catalytic activity, whereas V offered polysulfide adsorption capability [26] . Therefore, to better understand the limits of the proposed material, the impact of prepared cathodes on the cell resistance and, hence, the Li−S battery performance is mechanistically studied here.…”

Band Structure Engineering and Orbital Orientation Control Constructing Dual Active Sites for Efficient Sulfur Redox Reaction

“…[12,13] However, researchers generally focus on specific LiPSs as a representation for modeling to compare the electrocatalytic effect [14] while it is insufficient for various sulfur species due to molecular configuration and electronic structure differences. [15] Such simulation inevitably misses the influence of binding energy trend throughout the entire SRR. Systematic investigations of catalytic activity with the evolution of sulfur species and the underlying mechanism to address the LiPSs shuttle effect are rarely mentioned, limiting catalyst design based on primitive reaction characteristics.…”