Preparation of lithium ion conductive Li6PS5Cl solid electrolyte from solution for the fabrication of composite cathode of all-solid-state lithium battery

Abstract

An argyrodite type Li6PS5Cl was prepared by the solution process using a mixture of solvents with a fast evaporation rate. The crystal phase and ionic conductivity of the Li6PS5Cl solid electrolyte were examined by X-ray diffraction and electrochemical impedance spectroscopy, respectively. Li6PS5Cl derived from solution process shows an argyrodite structure with an ionic conductivity of 6 × 10-5 S cm−1 at room temperature. Composite cathode was directly prepared by dispersing LiNi1/3Mn1/3Co1/3O2 (84 wt%) and a conductive additive (2 wt%) into a Li6PS5Cl precursor solution (14 wt%), with subsequent heating at 150 °C. Morphology of the composite cathode was evaluated by scanning electron microscopy and energy-dispersive X-ray spectroscopy. The formation of Li6PS5Cl-layer on the active material particles was observed. A bulk-type all-solid-state cell was fabricated with composite cathode derived from the solution process, achieving an initial discharge capacity of 160 mAh g−1 and capacity retention of ~80% after 20 cycles with a capacity efficiency of 100%.