Evaluation of Li6P2S8I solid electrolyte for all solid-state lithium battery applications

In this work, we prepared an iodine-doped Li3PS4 solid electrolyte by wet ball milling. We added pure iodine to the Li3PS4 solid electrolyte to achieve a novel composite/phase. We optimized the highest ionic conductivity of the composite by changing the iodine concentration and sintering temperature. The selected Li6P2S8I solid electrolyte exhibited the ionic conductivity of 1 x 10(-3) S cm(-1), at room temperature. We used high-power X-ray diffraction to analyse the crystalline nature and find the formation of a new, unknown phase. We studied the surface morphology of the electrolyte by field-emission microscopy. We analysed the surface functional group of the Li6P2S8I solid electrolyte by X-ray photoelectron spectroscopy and its electrochemical behaviour by cyclic voltammetry, DC polarization, charge-discharge and impedance spectroscopy. The cyclic voltammetry and DC polarization showed that the synthesized Li6P2S8I solid electrolyte is highly stable to Li. The fabricated In/Li6P2S8I /NCM composite 2032-type asymmetric cell exhibited the specific capacity of 135.1 mAh g(-1) and showed good cycle stability.