Amorphous–crystalline-heterostructured niobium oxide as two-in-one host matrix for high-performance lithium–sulfur batteries

Abstract

Advanced host materials are requisite for both cathode and anode in the development of high-performance lithium–sulfur (Li–S) batteries. Herein, for the first time, we report a unique niobium oxide matrix with amorphous/crystalline hetero-conjunctions (A/T-Nb₂O₅) as a two-in-one host in a Li–S system. The heterostructure is constructed by simply regulating the calcination temperature at a modest level to generate partially-crystalized Nb₂O₅, rather than completely crystalline or amorphous. As the cathode matrix, the heterostructured design is unveiled, combining the preferably high sulfur affinity and fast ion transfer from the amorphous and crystalline phase, respectively, thus rendering a simultaneous stabilization and catalyzation for sulfur electrochemistry with excellent cyclability over 800 cycles and rate capability up to 3C. On the other hand, the as-developed A/T-Nb₂O₅ is found capable of facilitating the Li redox kinetics and uniformizing the Li nucleation/growth behaviors when applied as the anode matrix, contributing to durable Li plating/stripping at varied capacity limit up to 10 mA h cm⁻². Collectively, these advantageous features are integrated into a S–A/T-Nb₂O₅|Li–A/T-Nb₂O₅ full-cell configuration, which realizes decent areal capacity, cyclability, and rate capability under a high sulfur loading of 5 mg cm⁻², demonstrating an instructive paradigm for rational material engineering in Li–S batteries.