Three-dimensional ordered macroporous ZIF-8 nanoparticle-derived nitrogen-doped hierarchical porous carbons for high-performance lithium–sulfur batteries

Abstract

Lithium–sulfur (Li–S) batteries have attracted considerable attention due to their ultra-high specific capacity and energy density. However, there are still problems to be resolved such as poor conductivity of sulfur cathodes and dissolution of polysulfides in organic electrolytes. Herein, a novel ZIF-8-derived nitrogen-doped connected ordered macro–microporous carbon (COM-MPC) was developed by a dual solvent-assisted in situ crystallization method within a face-centered cubic stacking sphere template, which acts as an advanced sulfur host for enhanced Li–S battery performance. Compared with the conventional predominant microporous C-ZIF-8, the unique hierarchical macro–microporous structure with nitrogen doping not only renders polysulfide intermediates enhanced entrapment by confining the effect of micropores and chemisorption of doping N atoms, but also facilitates electrolyte accessibility and efficient ion transport owing to the ordered macroporous structure. Benefitting from this, the COM-MPC@S cathode delivers a high initial specific capacity of 1498.5 mA h g⁻¹ and a reversible specific capacity of 1118.9 mA h g⁻¹. Moreover, the COM-MPC@S cathode exhibits 82.3% of capacity retention within 10th to 50th cycle at 0.5C and a large capacity of 608.5 mA h g⁻¹ after 50 cycles at a higher rate of 1C, and this enhanced cycling stability and rate capability demonstrate great practical application potential in Li–S battery systems.