One-pot mechanochemical synthesis of N-doped porous carbons at room temperature using a planetary ball mill.

The chelating ability of quinoxaline cores and the redox activity of organosulfide bridges in layered covalent organic frameworks (COFs) offer dual active sites for reversible lithium (Li)‐storage. The designed COFs combining these properties feature disulfide and polysulfide‐bridged networks showcasing an intriguing Li‐storage mechanism, which can be considered as a lithium–organosulfide (Li–OrS) battery. The experimental–computational elucidation of three quinoxaline COFs containing systematically enhanced sulfur atoms in sulfide bridging demonstrates fast kinetics during Li interactions with the quinoxaline core. Meanwhile, bilateral covalent bonding of sulfide bridges to the quinoxaline core enables a redox‐mediated reversible cleavage of the sulfursulfur bond and the formation of covalently anchored lithium–sulfide chains or clusters during Li‐interactions, accompanied by a marked reduction of Li–polysulfide (Li–PS) dissolution into the electrolyte, a frequent drawback of lithium–sulfur (Li–S) batteries. The electrochemical behavior of model compounds mimicking the sulfide linkages of the COFs and operando Raman studies on the framework structure unravels the reversibility of the profound Li‐ion–organosulfide interactions. Thus, integrating redox‐active organic‐framework materials with covalently anchored sulfides enables a stable Li–OrS battery mechanism which shows benefits over a typical Li–S battery.

In the market for next-generation energy storage, lithium-sulfur (LiÀ S) technology is one of the most promising candidates due to its high theoretical specific energy and cost-efficient ubiquitous active materials. In this study, this cell system was combined with a cost-efficient sustainable solvent-free electrode dry-coating process (DRYtraec®). So far, this process has been only feasible with polytetrafluoroethylene (PTFE)-based binders. To increase the sustainability of electrode processing and to decrease the undesired fluorine content of LiÀ S batteries, a renewable, biodegradable, and fluorine-free polypeptide was employed as a binder for solvent-free electrode manufacturing. The yielded sulfur/carbon dry-film cathodes were electrochemically evaluated under lean electrolyte conditions at coin and pouch cell level, using the state-of-the-art 1,2-dimethoxyethane/1,3-dioxolane electrolyte (DME/DOL) as well as the sparingly polysulfide-solvating electrolytes hexylmethylether (HME)/DOL and tetramethylene sulfone/ 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TMS/ TTE). These results demonstrated that the PTFE binder can be replaced by the biodegradable sericin as the cycle stability and performance of the cathodes was retained.

The lithium-sulfur (Li−S) technology is the most promising candidate for next-generation batteries due to its high theoretical specific energy and steady progress for applications requiring lightweight batteries such as aviation or heavy electric vehicles. For these applications, however, the rate capability of Li−S cells requires significant improvement. Advanced electrolyte formulations in Li−S batteries enable new pathways for cell development and adjustment of all components. However, their rate capability at pouch cell level is often neither evaluated nor compared to state of the art (SOTA) LiTFSI/dimethoxyethane/dioxolane (LITFSI: lithium-bis(trifluoromethylsulfonyl)imide) electrolyte. Herein, the combination of the sparingly polysulfide (PS) solvating hexylmethylether/1,2-dimethoxyethane (HME/DME) electrolyte and highly conductive carbon nanotube Buckypaper (CNT-BP) with low porosity was evaluated in both coin and pouch cells and compared to dimethoxyethane/dioxolane reference electrolyte. An advanced sulfur transfer melt infiltration was employed for cathode production with CNT-BP. The Li+ ion coordination in the HME/DME electrolyte was investigated by nuclear magnetic resonance (NMR) and Raman spectroscopy. Additionally, ionic conductivity and viscosity was investigated for the pristine electrolyte and a polysulfide-statured solution. Both electrolytes, DME/DOL-1/1 (DOL: 1,3-dioxolane) and HME/DME-8/2, are then combined with CNT-BP and transferred to multi-layered pouch cells. This study reveals that the ionic conductivity of the electrolyte increases drastically over state of (dis)charge especially for DME/DOL electrolyte and lean electrolyte regime leading to a better rate capability for the sparingly polysulfide solvating electrolyte. The evaluation in prototype cells is an important step towards bespoke adaption of Li−S batteries for practical applications.