Cathode-doped sulfide electrolyte strategy for boosting all-solid-state lithium batteries

Low lithium ionic conductivity of the solid-state electrolyte and large interface resistance have hampered the application of all-solid-state lithium batteries. Although various methods have been proposed to address these challenge, a high-efficient method still needs for all-solid-state batteries. For the first time that Pyrite (FeS₂) cathode is used as doping agent for Li₇P₃S₁₁-type glass–ceramic electrolyte that could simultaneously improve the ionic conductivity and decrease the interfacial resistance between FeS₂ cathode and electrolyte. A new series of Li₇P₃S₁₁-type glass–ceramic electrolytes (x = 0, 0.5, 1, 2) are prepared by high energy ball milling method, and the 99.5(70Li₂S–30P₂S₅)–0.5FeS₂ glass–ceramic electrolyte shows a high lithium ionic conductivity, up to 2.22 mS cm⁻¹ at room temperature. Solid-state NMR studies found that the presence of FeS₂ doping could controllably adjust the crystallisation portions in glass–ceramic electrolyte, thus achieving the superior ionic conductivity. Moreover, the fabricated FeS₂/99.5(70Li₂S–30P₂S₅)–0.5FeS₂/Li–Ln cell exhibited lower resistance. As a result, the novel all-solid-state lithium battery presented a higher initial capacity of 543 mAh g⁻¹ at the current density of 0.03 mA cm⁻² and also better cycling stability (462 mAh g⁻¹ after 20 cycles) than the counterpart. The proposed cathode-doped electrolyte strategy not only figure out the key factors that determine the ionic conductivity of the glass–ceramic electrolyte and cathode/electrolyte interfacial resistance, and also provides an efficient route for design electrode configuration of high-performance solid-state lithium batteries.