Spray-Printed Flexible Li₂S Cathode with Inorganic Ion-Conductive Binder Nano-Li₃PS₄

Flexible solid-state batteries fabricated by printing techniques are promising integrated power supplies for miniaturized and customized electronic devices. While typically these batteries use polymer solid electrolytes, a flexible Li₂S cathode with sulfide solid electrolyte is spray-printed in this work, by using solvated Li₃PS₄ nanoparticles as inorganic ion-conductive binder. This benefits from a novel low-temperature-sintering property of these nanoparticles, which can be pressure-free densified, along with the desolvation process, and thus bind the cathode at 250 °C. The battery can be stably charged and discharged for 300 cycles with no stacking pressure, and the capacity maintains at 840 mA h g_Li2 S^-1. We believe this low-temperature-sintering phenomenon of solid electrolyte nanoparticles will open a new path toward the application of sulfide solid electrolytes in printed solid-state batteries.