Particle size control of cathode components for high‐performance all‐solid‐state lithium–sulfur batteries

Abstract Understanding the size effect of each component on battery performance is essential for designing high‐performance Li 2 S/S cathode for all‐solid‐state Li–S batteries. However, the size effects of different components are always coupled because ball‐milling, an indispensable process to synthesize reversible cathode, simultaneously and uncontrollably reduces the particle size of all the components. Here, a liquid‐phase method, without ball‐milling, is developed to synthesize the Li 2 S composite cathode, so that the particle size of the active material Li 2 S and the solid electrolyte Li 3 PS 4 (LPS) can be independently controlled at nano‐ or microscale. This helps reveal that compositing Li 2 S and the conductive agent at nanoscale is essential for enhancing the reaction kinetics, whereas the nanoscale particle size and homogenous distribution of LPS is important for accommodating the large volume change of the cathode. By reducing the particle size of Li 2 S to 9.4 nm and that of LPS to 44 nm, the liquid‐phase‐synthesized composite cathode exhibits reversible capacity and 100% utilization of Li 2 S under 0.1 C rate.