Lithium-ion-conducting solid electrolytes hold promise for enabling high-energy battery chemistries and circumventing safety issues of conventional lithium batteries. Achieving the combination of high ionic conductivity and a broad electrochemical window in solid electrolytes is a grand challenge for the synthesis of battery materials. Herein we show an enhancement of the room-temperature lithium-ion conductivity by 3 orders of magnitude through the creation of nanostructured Li(3)PS(4). This material has a wide electrochemical window (5 V) and superior chemical stability against lithium metal. The nanoporous structure of Li(3)PS(4) reconciles two vital effects that enhance the ionic conductivity: (1) the reduction of the dimensions to a nanometer-sized framework stabilizes the high-conduction β phase that occurs at elevated temperatures, and (2) the high surface-to-bulk ratio of nanoporous β-Li(3)PS(4) promotes surface conduction. Manipulating the ionic conductivity of solid electrolytes has far-reaching implications for materials design and synthesis in a broad range of applications, including batteries, fuel cells, sensors, photovoltaic systems, and so forth.

Lithium‐sulfur (Li‐S) batteries suffer from rapid capacity decay and low energy efficiency because of the low solubility of lithium sulfide (Li2S) in organic solvents and the intrinsic polysulfide shuttle phenomenon. Here, a novel additive, phosphorus pentasulfide (P2S5) in organic electrolyte, is reported to boost the cycling performance of Li‐S batteries. The function of the additive is two‐fold: 1) P2S5 promotes the dissolution of Li2S and alleviates the loss of capacity caused by the precipitation of Li2S and 2) P2S5 passivates the surface of lithium metal and therefore eliminates the polysulfide shuttle phenomenon. A Li‐S test cell demonstrates a high reversible capacity of 900–1350 mAh g−1 and a high coulombic efficiency of ≥90% for at least 40 stable cycles at 0.1 C.

Sulfur-rich lithium polysulfidophosphates (LPSPs) act as an enabler for long-lasting and efficient lithium-sulfur batteries. LPSPs have ionic conductivities of 3.0×10(-5)  S cm(-1) at 25 °C, which is 8 orders of magnitude higher than that of Li2S. The high lithium ion conductivity imparts excellent cycling performance, and the batteries are configured in an all-solid state, which promises safe cycling with metallic lithium anodes.