Smart Flow Electrosynthesis and Application of Organodisulfides in Redox Flow Batteries

Advances in Functional Organosulfur-Based Mediators for Regulating Performance of Lithium Metal Batteries

Rechargeable lithium metal batteries (LMBs) are promising next-generation energy storage systems due to their high theoretical energy density. However, their practical applications are hindered by lithium dendrite growth and various intricate issues associated with the cathodes. These challenges can be mitigated by using organosulfur-based mediators (OSMs), which offer the advantages of abundance, tailorable structures, and unique functional adaptability. These features enable the rational design of targeted functionalities, enhance the interfacial stability of the lithium anode and cathode, and accelerate the redox kinetics of electrodes via alternative reaction pathways, thereby effectively improving the performance of LMBs. Unlike the extensively explored field of organosulfur cathode materials, OSMs have garnered little attention. This review systematically summarizes recent advancements in OSMs for various LMB systems, including lithium-sulfur, lithium-selenium, lithium-oxygen, lithium-intercalation cathode batteries, and other LMB systems. It briefly elucidates the operating principles of these LMB systems, the regulatory mechanisms of the corresponding OSMs, and the fundamentals of OSMs activity. Ultimately, strategic optimizations are proposed for designing novel OSMs, advanced mechanism investigation, expanded applications, and the development of safe battery systems, thereby providing directions to narrow the gap between rational modulation of organosulfur compounds and their practical implementation in batteries.

Xanthate-Mediated Oxidation of Li2S as the Lithium-Containing Cathode in Lithium-Sulfur Batteries with Extremely Low Overpotential

Lithium-sulfide (Li2S) has long been pursued as a lithium-containing cathode material for high-energy-density lithium-sulfur (Li-S) batteries. Unfortunately, its direct oxidation generally has a large overpotential, giving rise to low energy efficiency. The use of redox mediators to accelerate the conversion of solid Li2S to polysulfides represents a possible solution to lower the initial oxidation overpotential. However, most reported redox mediators exhibit significantly higher redox potentials than the desirable value. Herein, it is serendipitously found that lithium ethyl xanthate (LiEX) formed from the reaction among Li2S, ethanol, and CS2 at room temperature is an efficient redox mediator. It has a redox potential (≈2.3 V vs Li+/Li) close to the electrochemical oxidation potential of Li2S (2.25 V vs Li+/Li), which enables fast Li2S oxidation reaction kinetics, and more importantly, lowers the Li2S oxidation potential from ≈3.6 to ≈2.3 V. When further integrated with an Ni-NC catalyst in a tandem catalysis scheme, a remarkable specific capacity of ≈1100 mAh g-1 at 0.2 mA cm-2 and long cycle life of 1400 cycles with ∼73% capacity retention is achieved, outperforming those of other Li2S-based cathode materials from recent literature.

Organosulfur Materials for Rechargeable Batteries: Structure, Mechanism, and Application

Lithium-ion batteries have received significant attention over the last decades due to the wide application of portable electronics and increasing deployment of electric vehicles. In order to further enhance the performance of the batteries and overcome the capacity limitations of inorganic electrode materials, it is imperative to explore new cathode and functional materials for rechargeable lithium batteries. Organosulfur materials containing sulfur-sulfur bonds as a kind of promising organic electrode materials have the advantages of high capacities, abundant resources, tunable structures, and environmental benignity. In addition, organosulfur materials have been widely used in almost every aspect of rechargeable batteries because of their multiple functionalities. This review aims to provide a comprehensive overview on the development of organosulfur materials including the synthesis and application as cathode materials, electrolyte additives, electrolytes, binders, active materials in lithium redox flow batteries, and other metal battery systems. We also give an in-depth analysis of structure-property-performance relationship of organosulfur materials, and guidance for the future development of organosulfur materials for next generation rechargeable lithium batteries and beyond.