Promoting Reversible Redox Kinetics by Separator Architectures Based on CoS₂/HPGC Interlayer as Efficient Polysulfide‐Trapping Shield for Li–S Batteries

Abstract

Main obstacles from the shuttle effect and slow conversion rate of soluble polysulfide compromise the sulfur utilization and cycling life for lithium sulfur (Li–S) batteries. In pursuit of a practically viable high performance Li–S battery, a separator configuration (CoS2/HPGC/interlayer) as efficient polysulfide trapping barrier is reported. This configuration endows great advantages, particularly enhanced conductivity, promoted polysulfide trapping capability, accelerated sulfur electrochemistry, when using the functional interlayer for Li–S cells. Attributed to the above merits, such cell shows excellent cyclability, with a capacity of 846 mAh g−1 after 250 cycles corresponding to a high capacity retention of 80.2% at 0.2 C, and 519 mAh g−1 after 500 cycles at 1C (1C = 1675 mA g−1). In addition, the optimized separator exhibits a high initial areal capacity of 4.293 mAh cm−2 at 0.1C. Moreover, with CoS2/HPGC/interlayer, the sulfur cell enables a low self‐discharge rate with a very high capacity retention of 97.1%. This work presents a structural engineering of the separator toward suppressing the dissolution of soluble Li2Sn moieties and simultaneously promoting the sulfur conversion kinetics, thus achieving durable and high capacity Li–S batteries.

A Polysulfides‐Confined All‐in‐One Porous Microcapsule Lithium–Sulfur Battery Cathode

“…[41,42] Figure 2a displays the charge-discharge curves of the porous CNTs/QDs/S microcapsules at 0.1 C. In the discharging process, the plateau at about 2.3 V corresponds to the reduction of sulfur to soluble polysulfides (Li 2 S n , 4 ≤ n ≤ 8), and the plateau at 2.0 V is assigned to the long-chain sulfides, which are further reduced to low-order polysulfides (Li 2 S or Li 2 S 2 ). [43][44][45] Figure 2b shows the cyclic voltammetry (CV) curve in the potential range of 1.7-2.8 V versus Li/Li + at 0.1 mV s −1 . The reduction peaks at 2.0 and 2.3 V correspond to the conversion of solid S 8 to soluble long-chain polysulfides, [46] and the further reduction to insoluble short-chain polysulfides (Li 2 S 2 /Li 2 S).…”

Sandwiched Cathodes Assembled from CoS2‐Modified Carbon Clothes for High‐Performance Lithium‐Sulfur Batteries

“…They can effectively capture polysulfides and promote their reversible redox kinetics, thereby resulting in improved electrochemical performance. [ 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 ] Therefore, designing advanced cell configuration to integrate both physical confinement and chemical adsorption of polysulfides is a promising route to enhance electrochemical performance of LSBs, especially the high sulfur loading LSBs.…”

Hierarchical Porous Carbon Membrane Embedded with Pyrolyzed Co‐Based Metal−Organic Frameworks as Multifunctional Interlayers for Advanced Li−SeS2 Batteries

“…[ 28 ] Moreover, the characteristic peaks of Co sharply shift to higher binding energy after adsorbing Li 2 S 6 , demonstrating strong chemical interactions between Co−N−C and LiPSs (Figure 5c). [13a] As shown in Figure S10, Supporting Information, the symmetric cells with pure C or Co−N−C@C as electrode were tested at 0.2 mV s −1 in the potential range from −0.8 to 0.8 V. Compared with the pure C electrode, the Co−N−C@C electrode displays higher current density with two reduction peaks at 0.41 and 0.59 eV and two oxidation peaks at −0.41 and −0.59 eV, which confirm the significantly promoted LiPSs conventions catalyzed by Co in Co−N−C@C. [ 17 ]…”

“…[ 16 ] Recently, we reported a novel interlayer coating based on hierarchical porous carbon modified by CoS 2 (CoS 2 /HPC). [ 17 ] Due to the enhanced redox reaction kinetics, the cell with CoS 2 /HPC interlayer exhibited excellent rate ability at 2 C. Inspired by our previous work, we report our latest progress on a multifunctional Co−N−C@C interlayer derived from PAN and a MOF (ZIF‐67) on the substrate. The abundant and homogeneous decoration of Co−N−C polyhedra on the carbon membrane endows Co−N−C@C with a good combination of a hierarchically porous conductive network and multiple adsorptive/catalytic sites, which is beneficial for improving the performance of Li−SeS 2 batteries.…”