Preparation and Electrochemical Characteristics of Sm2S3–SnS Composite Electrodes

Abstract

Abstract The influences of Sm2S3 incorporation on the structural features and electrochemical behavior of Sm2S3–SnS composite electrodes were investigated. Both SnS and Sm2S3 maintain their intrinsic crystal structures. Sm2S3 particles are reasonably dispersed on or among the layered SnS particles at low to moderate loadings, while higher Sm2S3 contents lead to partial agglomeration. Sm2S3 incorporation affects the charge–storage characteristics of SnS. The cyclic voltammetry (CV) curves of the Sm2S3–SnS composite electrodes exhibit non-ideal profiles with distorted capacitive shapes and noticeable faradaic contributions. The Sm2S3–SnS composites exhibit improved rate capability and prolonged discharge behavior compared with pristine SnS. A pure Sm2S3 electrode prepared and tested under the same conditions was further introduced as a control sample. The comparison confirms that pure Sm2S3 is electrochemically active but is not superior to the optimized Sm2S3–SnS composites, indicating that SnS plays an active role in constructing an ion-accessible layered framework and improving the utilization of Sm2S3 domains. Different Sm2S3 loadings favor different electrochemical metrics under different current-density conditions. Electrochemical impedance spectroscopy (EIS) of Sm2S3–SnS composite electrode demonstrates a non-monotonic evolution of solution resistance and charge-transfer resistance with increasing Sm2S3 content, suggesting changes in interfacial charge-transport pathways. The Sm2S3–SnS composite electrodes possess stable cycling performance and high Coulombic efficiency. The possible role of Sm2S3 in modulating phase contact and charge–storage characteristics of SnS-based composite electrodes is discussed.