Investigating the Influence of the Effective Ionic Transport on the Electrochemical Performance of Si/C‐Argyrodite Solid‐State Composites

Abstract Solid‐state batteries have the potential to outperform conventional lithium‐ion batteries, as they offer higher energy densities, necessary for the increasing demand for portable energy storage. Silicon‐graphite composites are considered to be one of the most promising alternatives to the lithium metal anode due to their low lithiation potential and resistance against dendrite formation. Since these composites show insufficient ionic conductivity, a fast‐conducting solid electrolyte is needed to facilitate the charge carrier transport. Optimizing the volume fractions of the solid electrolyte is crucial to ensure sufficient charge carrier transport and achieve the optimal performance. In this work, the influence of the charge carrier transport in a silicon on graphite (Si/C)/argyrodite solid electrolyte composite on the electrochemical performance is studied. By systematically varying the ratio of the Si/C to solid electrolyte, it was found that the effective ionic conductivity of the electrode composite improves exponentially with increasing content of the solid electrolyte, which in turn leads to an increase in the specific capacity of the composite across all C‐rates. This study highlights the importance of understanding and customizing charge carrier transport properties in solid‐state anode composites to achieve optimum electrochemical performance.