Polysulfide Regulation by Hypervalent Iodine Compounds for Durable and Sustainable Lithium–Sulfur Battery

Abstract

Herein, a type of hypervalent iodine compound—iodosobenzene (PhIO)—is proposed to regulate the LiPSs electrochemistry and enhance the performance of Li‐S battery. PhIO owns the practical advantages of low‐cost, commercial availability, environmental friendliness and chemical stability. The lone pair electrons of oxygen atoms in PhIO play a critical role in forming a strong Lewis acid–base interaction with terminal Li in LiPSs. Moreover, the commercial PhIO can be easily converted to nanoparticles (≈20 nm) and uniformly loaded on a carbon nanotube (CNT) scaffold, ensuring sufficient chemisorption for LiPSs. The integrated functional PhIO@CNT interlayer affords a LiPSs‐concentrated shield that not only strongly obstructs the LiPSs penetration but also significantly enhances the electrolyte wettability and Li+ conduction. The PhIO@CNT interlayer also serves as a “vice current collector” to accommodate various LiPSs and render smooth LiPSs transformation, which suppresses insulating Li2S2/Li2S layer formation and facilitates Li+ diffusion. The Li−S battery based on PhIO@CNT interlayer (6 wt% PhIO) exhibits stable cycling over 1000 cycles (0.033% capacity decay per cycle) and excellent rate performance (686.6 mAh g−1 at 3 C). This work demonstrates the great potential of PhIO in regulating LiPSs and provides a new avenue towards the low‐cost and sustainable application of Li−S batteries.

Establishing Transition Metal Phosphides as Effective Sulfur Hosts in Lithium–Sulfur Batteries through the Triple Effect of “Confinement–Adsorption–Catalysis”

“…Furthermore, the UV spectroscopy results indicate that the adsorption capacity of OMCS‐CoP for LiPSs is superior to that of SP, OMCS, and OMCS‐Co, as evidenced by the weakest characteristic peak (≈260 nm) of Li 2 S 6 adsorption, which further confirms that OMCS‐CoP has the best adsorption capacity for LiPSs. [ 60 ]…”

“…Furthermore, the UV spectroscopy results indicate that the adsorption capacity of OMCS-CoP for LiPSs is superior to that of SP, OMCS, and OMCS-Co, as evidenced by the weakest characteristic peak (≈260 nm) of Li 2 S 6 adsorption, which further confirms that OMCS-CoP has the best adsorption capacity for LiPSs. [60] To further investigate the electrochemical properties of OMCS-CoP, Li 2 S precipitation experiments were conducted using different electrodes: OMCS-CoP (Figure 4a), OMCS-Co (Figure 4b), OMCS (Figure 4c), and SP (Figure 4d). Galvanostatic discharge was carried out until reaching 2.06 V, followed by maintaining the voltage at 2.05 V until the current dropped below 10 −5 A.…”

High Energy Density Aqueous Zinc–Chalcogen (S, Se, Te) Batteries: Recent Progress, Challenges, and Perspective

“…In Figure 4e, iodide ion in TUI was considered as an efficient redox mediator to alleviate the charge overpotential, which was commonly used in other storage systems such as Li–O 2 , Li–S, and Na–S batteries. [ 109,110 ] Besides, the author claimed that thiourea (TU) could adjust the crystallographic property and morphology of the Zn surface to inhibit the dendrite growth and corrosion, [ 111,112 ] while the corrosion of Zn anode could be reduced with the coordination of I 3 − , which stems from the formamidine disulfide cation. Benefiting from the aforementioned modification, as illustrated in Figure 4f, at 2 A g −1 , a high capacity of 345 mAh g −1 (1045 mAh g −1 based on S) could be delivered and remarkably maintained 226 mAh g −1 over 300 cycles, within a low‐capacity decay of 0.115% per cycle.…”

Modulating d‐Band Electronic Structures of Molybdenum Disulfide via p/n Doping to Boost Polysulfide Conversion in Lithium‐Sulfur Batteries

“…[3,4] Unfortunately, the intrinsic insulativity of sulfur and lithium sulfides (Li 2 S 2 /Li 2 S), large volume expansion (78%) of the cathode during the charge/discharge process, particularly the serious "shuttle effect" of soluble lithium polysulfides (LiPSs) mediators and the sluggish solid-liquid-solid conversion kinetics of sulfur species make Li-S battery impossible to guarantee its lifespan, which impedes its further developments. [5,6] Previous studies have proposed a lot of rational strategies to address these limitations, such as confining sulfur species into carbon materials, [7,8] adsorbing soluble redox mediators on adsorbents through polar interactions or the interactions, [9][10][11] reducing the solubility of LiPSs in various donor number (DN) solvents [12][13][14] and blocking diffusion of LiPSs through the modified separators. [15][16][17] Electrocatalysis has recently been mentioned as the most powerful strategy to solve the intractable issues above.…”