Synchronous Gains of Areal and Volumetric Capacities in Lithium-Sulfur Batteries Promised by Flower-like Porous Ti3C2T x Matrix.

Abstract

The areal and volumetric capacities are important metrics in practical deployment of advanced energy storage systems with the imposed constraints of device volume and chip area. Conductive carbons are promising sulfur host materials for improving areal capacity in lithium-sulfur (Li-S) batteries, but they face a few congenital deficiencies, such as low tap density and weak polysulfide entrapment ability, resulting in poor volumetric performance. Here, we report one type of cathode system based on flower-like porous Ti3C2T x (FLPT) without the incorporation of any carbon hosts or conductive additives. The resultant FLPT-S electrode synchronously acquires a high areal capacity of 10.04 mAh cm-2 and ultrahigh volumetric capacity of 2009 mAh cm-3. Furthermore, ex situ electron paramagnetic resonance and UV-visible spectra have demonstrated that FLPT enables a fast dynamic equilibrium between S62- anion and S3•- radical during cycling, which promotes the redox reactions of sulfur species.