Anomalous High Ionic Conductivity of Nanoporous β-Li₃PS₄

TLDR

Lithium‑ion‑conducting solid electrolytes promise high‑energy, safe batteries, yet simultaneously achieving high conductivity and a wide electrochemical window remains a major challenge with broad implications for energy devices. Nanoporous Li(3)PS(4) boosts conductivity by stabilizing the high‑conduction β phase at nanometer scales and by enhancing surface conduction through a high surface‑to‑bulk ratio. Nanostructured Li(3)PS(4) exhibits a 1000‑fold increase in room‑temperature lithium‑ion conductivity, a 5‑V electrochemical window, and excellent stability against lithium metal.

Abstract

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.