Cobalt-Based Double Catalytic Sites on Mesoporous Carbon as Reversible Polysulfide Catalysts for Fast-Kinetic Li–S Batteries

Abstract

Li−S batteries are considered to be the most promising nextgeneration advanced energy-storage systems. However, the sluggish reaction kinetics and the "shuttle effect" of lithium polysulfides (LiPSs) severely limit their battery performances. To overcome the complex and multiphase sulfur redox chemistry of LiPSs, in this study, we propose a new type of cobalt-based double catalytic sites (DCSs) codoped mesoporous carbon to immobilize and reversibly catalyze the LiPS intermediates in the cycling process, thus eliminating the shuttle effect and improving the charge−discharge kinetics. The theoretical calculation shows that the well-designed DCS configuration endows LiPSs with both strong and weak binding capabilities, which will facilitate the synergistic and reversible catalytic conversion. Furthermore, the experimental results also confirm that the DCS structure shows significantly enhanced catalytic kinetics than the single catalytic sites. The Li−S battery equipped with the DCS structure displays an extremely high discharge capacity of 918 mA h g −1 at a current density of 0.2 C and can reach a capacity of 867 mA h g −1 after 200 cycles with an ultralow capacity attenuation rate of 0.028% for each cycle. This study opens new avenues to address the catalytic requirements both in discharging and charging processes.

Role of the Metal Atom in a Carbon‐Based Single‐Atom Electrocatalyst for LiS Redox Reactions

“…The catalytic activities of carbon-based SACs toward sulfur species depend on both the single metal active sites and the carbon support, for example, the metal atom loading, coordination of the M-N-C center, and the pore structure and electrical conductivity of the carbon substrate. [23][24][25][26] Considering the complexity of the different effects that determine the catalytic activities of carbonbased SACs, it is quite challenging to exclusively determine the critical role of the central metal atoms in LiS chemistry.…”

Sulfur‐containing polymer cathode materials: From energy storage mechanism to energy density

“…Although Li‐S batteries have many benefits compared with LIBs, Li‐S batteries also suffer from the inherently insulating nature and large volume change of sulfur (as high as 80%). In addition, shuttle soluble polysulfides (Li 2 S x , x ≥ 4) in the electrolyte is a critical problem, making the energy density of Li‐S batteries low 8–13 . Therefore, a variety of strategies have been developed to form sulfur composites with porous carbon and other favorable structures to optimize the properties of Li‐S batteries 12,14–19 …”

“…In addition, shuttle soluble polysulfides (Li 2 S x , x ≥ 4) in the electrolyte is a critical problem, making the energy density of Li-S batteries low. [8][9][10][11][12][13] Therefore, a variety of strategies have been developed to form sulfur composites with porous carbon and other favorable structures to optimize the properties of Li-S batteries. 12,[14][15][16][17][18][19] As is well-known, traditional Li-S batteries 20 have a "solid-liquid-solid reactions" corresponding to two discharging plateaus in its voltage profile as shown in Figure 1.…”

Nitrogen/sulfur dual-doped micro-mesoporous hierarchical porous carbon as host for Li-S batteries

“…Nevertheless, low sulfur loading reduces the overall energy density of Li-S batteries, which is a result of the carbon materials with microporosity having significantly smaller pore volumes. In comparison to the microporous carbon, the distribution of pore diameter for mesoporous carbon is larger, which accommodates more sulfur to increase the loading of sulfur ( Liu et al, 2021a ; Yang et al, 2021a ). But, presence of excessive sulfur inside mesoporous carbon prevents the formation of good electrical contact between sulfur and the pore walls of conductive carbon.…”