Preparation of Li7P2S8I Solid Electrolyte and Its Application in All-Solid-State Lithium-Ion Batteries with Graphite Anode

Abstract

A Li7P2S8I solid electrolyte was prepared by the reaction between raw materials in an ethyl propionate medium and drying of the precursor. The obtained sample was characterized by X-ray diffraction (XRD), cyclic voltammetry, DC polarization test and AC impedance measurements. The formation of Li7P2S8I was confirmed from the results of XRD. Cyclic voltammetry and the DC polarization test indicated that the obtained Li7P2S8I was stable at low potential versus Li/Li+ and against Li metal. The all-solid-state lithium-ion battery was fabricated by using Li–In, Li7P2S8I solid electrolyte and a graphite composite that was prepared by mixing graphite, Li7P2S8I solid electrolyte and vapor grown carbon fiber with a vortex mixer. It was observed that the electrode materials were homogeneously mixed from the scanning electron microscopy image of the composite prepared by using the vortex mixer. The fabricated half-cell was characterized by the charge–discharge test. The Li7P2S8I solid electrolyte is suitable for use with a graphite anode because the charge–discharge test exhibited an initial discharge capacity of 372 mA h g−1 and high reversibility of capacity.