Lithiated Sulfur-Incorporated, Polymeric Cathode for Durable Lithium–Sulfur Batteries with Promoted Redox Kinetics

Abstract

Even though lithium−sulfur (Li−S) batteries have made much progress in terms of the delivered specific capacity and cycling stability by the encapsulation of sulfur within conductive carbon matrixes or polar materials, challenges such as low active sulfur utilization and unacceptable Coulombic efficiency are still hindering their commercial use. Herein, a lithium-rich conjugated sulfur-incorporated, polymeric material based on poly(Li 2 S 6 -r-1,3diisopropenylbenzene) (DIB) is developed as a cathode material for high rate and stable Li−S batteries. Motivated by extra Li + ions affording fast Li + redox kinetics across the conjugated aromatic backbones, the Li-rich sulfur-based copolymer exhibits high delivery capacities (934 mAh g −1 at 120 cycles), impressive rate capabilities (727 mAh g −1 even under a current of 2 A g −1 ), and long electrochemical cycling performance over 500 cycles. Moreover, by use of the elastic nature and thermoplastic properties of the sulfur-incorporated, polymeric material, a prototype of a flexible Li−S pouch cell is constructed by using a poly(Li 2 S 6 -r-DIB) copolymer cathode and paired with the flexible carbon cloth/Si/Li anode, which exhibits stable electrochemical performance (658 mAh g −1 after 100 cycles) and operational capability even under folding at various angle (30°, 60°, 90°, 120°, 150°, 180°). This work extends the molecular-design approach to obtaining a high-performance organosulfur cathode material by introducing extra Li + ions to promote redox kinetics, which provides valuable guidance for the development of high-performance Li−S batteries for practical applications.

Designing and tuning the components of random terpolymers toward Ampere-hour-scale organic lithium batteries

“…4d and Table S5 †). [43][44][45][46][47] Investigations on cycled cells, including the morphology and molecular structures of cycled electrodes, were conducted to study the electrochemical process and the reasons for the excellent electrochemical performance. The morphology of the cycled cathode is an important parameter to evaluate the exfoliation of cathodes aer cycling.…”

Recent advances in carbon-based sulfur host materials for lithium-sulfur batteries

“…PAN is commonly taken as a coating for sulfur due to the abundance of nitrogen-containing groups on the skeleton. To improve the chemisorption effect, Chen et al grafted phytic acid (PA) containing P onto the -NH-group on the main chain of PAN to prepare N and P rich in quinone imide (-NH + =/-N=) polymer [Figure 5B] [81] Quinone imide-doped GO was prepared by coating the polymer on GO as a sulfur host, which can adsorb Li 2 S 8 and speed up sulfur redox reaction. When the sulfur loading is 3.3 mg cm -2 , the areal specific capacity is 3.72 mAh cm -2 .…”

Organosulfur polymer-based cathode materials for rechargeable batteries

“…Later, Dong et al prepared a prelithiated sulfur-rich copolymer poly(Li 2 S 6 -r-1,3-diisopropenylbenzene) (Li 2 S 6 -rDIB) by mixing Li 2 S 6 and DIB at 150 °C (Fig. 2f), 35 which effectively inhibites the formation of long-chain polysulfides through the chemical interaction between Li 2 S 6 and the conjugated aromatic backbone. The extra Li + can promote the Li + reaction kinetics.…”