Low-temperature Li-S batteries enabled by all amorphous conversion process of organosulfur cathode

Abstract

The high degree of crystallinity of discharging intermediates of Li-S batteries (Li2S2/Li2S) causes a severe capacity attenuation at low temperatures. Herein, a sulfur-rich polymer is fabricated, which enables all the discharging intermediates to exist in an amorphous state without long-range order, promoting the substantial conversion of discharging intermediates and enhancing Li-S batteries' performance at low temperatures greatly. This cathode material exhibits excellent performance both at room and low temperatures. Even under an extremely low temperature (–40 ℃), the discharge capacity can remain 67% of that at room temperature. Besides, in-situ UV/Vis spectroscopy and density functional theory calculations reveal that this organosulfur cathode undergoes a new mechanism during discharge. Li2S6 and Li2S3 are the primary discharging intermediates that are quite different from conventional Li-S batteries. These results provide a new direction for a broader range of applications of Li-S batteries.