N, S‐Coordinated Co Single Atomic Catalyst Boosting Adsorption and Conversion of Lithium Polysulfides for Lithium‐Sulfur Batteries

Abstract

Boosting reversible solid‐liquid phase transformation from lithium polysulfides to Li2S and suppressing the shuttling of lithium polysulfides from the cathode to the lithium anode are critical challenges in lithium‐sulfur batteries. Here, sulfiphilic single atomic cobalt implanted in lithiophilic heteroatoms‐dopped carbon (SACo@HC) matrix with a CoN3S structure for high‐performance lithium‐sulfur batteries is reported. Density functional theory calculation and in situ experiments demonstrate that the optimal CoN3S structure in SACo@HC can effectively improve the adsorption and redox conversion efficiency of lithium polysulfides. Consequently, the S‐SACo@HC composite with sulfur loading of 80 wt% delivers a high capacity of 1425.1 mAh g−1 at 0.05 C and outstanding rate performance with 745.9 mAh g−1 at 4 C. Furthermore, a capacity of 680.8 mAh g−1 at 0.5 C with a low electrolyte/sulfur ratio (6 µL mg−1) can be achieved even after 300 cycles. With the harsh conditions of lean electrolyte (E/S = 4 µL mg−1) and high sulfur loading (5.4 mg cm−2), a superior area capacity of 5.8 mAh cm−2 can be obtained. This work contributes to building a profound understanding of the adsorption and interface engineering of lithium polysulfides and provides ideas to tackle the long‐standing polysulfide shuttle problem of lithium‐sulfur batteries.

d-p Hybridization-Induced “Trapping–Coupling–Conversion” Enables High-Efficiency Nb Single-Atom Catalysis for Li–S Batteries

“…However, the reduction of the E/S ratio means the increase of polysulfide concentration, which reduces the sulfur reaction kinetics and aggravates the shuttle effect. The introduction of SACs is an effective promoter to facilitate sulfur electrocatalysis kinetics at the reaction interface, which is particularly crucial under low-E/S ratio conditions. , Specifically, compared with the traditional catalysts such as high polar compounds and electronic configuration regulation, SACs can utilize the trace electrolytes due to an improved two-phase interface dynamics but not the traditional three-phase interface limited by the electron-transfer kinetics. Therefore, SACs maximize the atom utilization, allowing for higher active sites, better chemical stability, and good reversibility in contrast to conventional electrocatalysis.…”

Atomically Dispersed Fe–N4 and Ni–N4 Independent Sites Enable Bidirectional Sulfur Redox Electrocatalysis

“…Theoretical simulation on Ti, V, Cr, and Mn with four nitrogen atom coordination (M–N 4 ) showed strong SAC–S bonds and simultaneously weakened S–S bonds in LiPSs . Apart from the LiPSs shuttling suppression, the reaction rate for the charging process is highly determined by the oxidation of insulating Li 2 S. An insufficient catalytic effect will cause surface passivation and lower the sulfur utilization. , Progress has been achieved in enhancing the catalytic activity (especially for sulfur reduction) by regulating the coordinated ligands or controlling the distance of the SAC sites. − Nevertheless, achieving a fast bidirectional sulfur conversion process by using a single metal atom catalyst is challenging. Recently, constructing dual-atom catalysts (DACs) also has been reported as an effective strategy to propel the kinetics of oxygen reduction reaction and polysulfides conversion by tailoring the electronic structure of metal centers. , Compared with coordination engineering of the SACs and electron structure modulation of the DACs, the appropriate selection of independent dual single atoms to separate sulfur oxidation and reduction could offer a viable approach toward a high catalytic effect, which has not been reported.…”

A separator modified by barium titanate with macroscopic polarization electric field for high-performance lithium–sulfur batteries

“…Lithium-sulfur batteries (LSBs) have attracted increasing attention as a promising next-generation energy storage candidate on account of their high theoretical capacity (1675 mA h g −1 ) and high energy density (2600 W h kg −1 ). [1][2][3] However, the technical difficulties of LSBs are still limited by the well-recognized dissolution and diffusion behaviors of polysulfides (Li 2 S n , 4 ≤ n ≤ 8) between both electrodes during cycling. In order to solve this problem, enormous efforts have been dedicated to embedding elemental sulfur with conductive and polar materials to anchor polysulfides.…”