Work

From Fluorinated to All-Fluorine-Free Systems: Hückel Anion-Based Electrolytes for Lithium–Sulfur Batteries with Enhanced High C-Rate Sulfur Utilization

Year: 2026

Type: article

Abstract: Lithium-sulfur (Li-S) batteries are considered a promising alternative to conventional lithium-ion systems; however, their practical deployment is still limited by insufficient sulfur utilization, polysulfide shuttling, and capacity fading. In this work, two complementary modification strategies for Li-S batteries are systematically investigated. First, obtaining simple, easy-to-prepare, and low-cost model cathodes enables the simulation of cycling of the cell with different sulfur availability through a comparative assessment of conductive carbon blacks (Super P, Ketjen Black EC-300-JD, and Vulcan XC-72), NaCMC binder, and sulfur content. The influence of electrode formulation, sulfur loading, electrolyte-to-sulfur (E/S) ratio, and conductive carbon type on electrochemical performance is evaluated, enabling the identification of an optimized model cathode. In the second part of the study, electrolyte optimization is explored using a series of Hückel anion-based lithium salts, including fluorine-free candidates. The electrochemical performance of lithium 4,5-dicyano-2-(n-heptafluoropropyl)-imidazolide (LiHDI), lithium 4,5-dicyano-2-(pentafluoroethyl)-imidazolide (LiPDI), lithium 4,5-dicyano-2-(trifluoromethyl)-imidazolide (LiTDI), and lithium 2,4,5-tricyanoimidazolide (LiTIM) is benchmarked against the conventional LiTFSI-based electrolyte. The investigated salts generally deliver higher discharge capacities, particularly at elevated charge rates, and exhibit improved capacity retention during prolonged cycling. The combined cathode and electrolyte engineering approach demonstrates enhanced electrochemical stability and reduced capacity decay, indicating that Hückel anion-based electrolytes represent a viable direction for further optimization of Li-S battery systems.

Source: ACS Omega

DOI: 10.1021/acsomega.6c01071

Authors: Maciej Smoliński, Adam Łaszcz, Aleksandra Ossowska, Marek Marcinek, Maciej Marczewski

Institutions: Warsaw University of Technology, Łukasiewicz Research Network - Institute of Microelectronics and Photonics

Language: English

Topic: Advanced Battery Materials and Technologies

Subfield: Electrical and Electronic Engineering

Field: Engineering

Domain: Physical Sciences

SDG: Affordable and clean energy

Open Access status: gold

Estimated APC paid: $1,935