Boosting the rate performance of Li–S batteries under high mass-loading of sulfur based on a hierarchical NCNT@Co-CoP nanowire integrated electrode

Abstract

Lithium–sulfur batteries (Li–S) have been gradually becoming one of the most promising next-generation storage systems, but their practical application is still limited by the extremely low S loading as well as the poor rate capability. Herein, Li–S batteries with boosting rate performance under high mass-loading of S have been achieved based on the hierarchical NCNT@Co-CoP nanowire integrated electrode. The experiments and density functional theory calculations demonstrate that the Co-CoP heterojunction interface simultaneously improves the ion transportation/electron migration, and efficiently confines and catalyzes the conversion of lithium polysulfides (LiPSs). Moreover, the ex situ scanning electron microscopy image and in situ Raman spectra further demonstrate the obviously reduced volume expansion and efficient catalytic conversion of LiPSs on NCNT@Co-CoP-1 even at a high S loading. As a result, Li–S batteries with the NCNT@Co-CoP cathode deliver superior cyclability and remarkable rate capability with 603.9 mA h g⁻¹ after 900 cycles at 5C. Moreover, a high areal capacity retention of 4.4 mA h cm⁻² after 100 cycles at 2C rate can also be achieved even under higher loading (10 mg cm⁻²) and low E/S ratio (7 μL mg⁻¹), illustrating its great practical application in high-rate performance Li–S batteries.