Authors: Piergiorgio Marziani, Eugenio Gibertini, Rafael Müller, Margarita Russina, Adèl Len, Christian Höhn, Nikolay Kardjilov, André Hilger, Luca Magagnin, Sebastian Risse, Maurizio Sansotera

Source: Journal of Power Sources
Published: Feb (2026)
DOI: https://doi.org/10.1016/j.jpowsour.2025.239030

ABSTRACT:

We present the use of fluorinated carbon black (FCB) with different degrees of surface functionalization as an efficient class of materials for sulfur cathodes in lithium-sulfur batteries (LSBs), suitable for the entrapment of polysulfides. The direct fluorination treatment at different temperatures endowed the carbonaceous surface with C–F functionalities, which mitigated polysulfides migration, enhanced sulfur utilization and inhibited the shuttle effect. FCBs were characterized by X-ray photoelectron spectroscopy (XPS), small-angle neutron scattering (SANS), and UV–vis spectroscopy. Moreover, the “diffusion-limited aggregation” (DLA) was model used for the first time for the analysis of the performance of LSBs cathodes incorporating FCBs via operando X-ray imaging. This method provided insights on the growth of the sulfur crystals and on the dynamics of polysulfides within the cathode materials, highlighting the effectiveness of FCB in promoting homogeneous sulfur deposition and enhancing polysulfide retention. Charge-discharge tests at 0.2C and 3C on cells with FCB-containing electrodes demonstrated a remarkable improvement in capacity retention: a threshold of 80 % was reached after 128 cycles, i.e. 7.5 times more than a reference cell containing pure carbon black (CB) that lasted only for 17 cycles. In addition, cells with FCB-containing cathodes exhibited a coulombic efficiency of 98 % for 200 cycles, exceeding the performance of electrodes prepared with pristine carbon black as sulfur-host matrix.