Electrochemical performance of MoS2, Sb2S3, and SnS anodes in sodium-ion batteries using a conductive polypyrrole-carbon black composite and an LBG sustainable binder

Abstract

This study explores enhancement of electrochemical performance in sodium-ion battery anodes by integrating metal sulfides—tin sulfide (SnS), molybdenum disulfide (MoS₂), and antimony(III) sulfide (Sb₂S₃)—with an innovative conductive composite of polypyrrole and carbon black (PPyCB), combined with a water-soluble binder, locust bean gum (LBG). The main aim was to investigate how this new electrode formulation influences sodiation behavior, structural stability, and charge transfer properties. The electrodes exhibited high initial sodiation capacities of 1021, 800, and 786 mA h g⁻¹ for SnS, MoS₂, and Sb₂S₃, respectively, with good kinetic parameters and activation energies (E^#_el, E^#_SEI and E^#_CT) comparable to those reported for lithium-ion systems. Morphological analysis via SEM revealed material-dependent structural evolution during cycling, including particle size changes and SEI formation, which influenced electrochemical reversibility and capacity retention. Adhesion tests before and after sodiation confirmed the robust binding properties of LBG, with adhesion trends dependent on the type of active material and the degree of volume expansion. Electrochemical impedance studies showed significant differences in interfacial resistances and charge transfer characteristics across the tested materials, with MoS₂ displaying the most thermally stable impedance behavior and Sb₂S₃ showing the highest SEI activation energy. Bode plot analysis provided novel insight into frequency-dependent ion diffusion efficiency, highlighting temperature-sensitive transport dynamics and the beneficial role of the PPyCB conductive matrix. These findings demonstrate that the synergistic effect of the PPyCB-LBG matrix with metal sulfide anodes offers a promising route toward improving the stability, kinetics, and overall efficiency of sodium-ion energy storage systems.