Sulfur-enriched, hierarchically nanoporous carbonaceous materials for sodium-ion storage

Abstract

Na-ion batteries (NIBs) have had much attention as post Li-ion batteries (LIBs) due to abundant Na resources and a similar chemistry to LIBs; however NIBs have suffered from a lack of proper anode materials. In this study, sulfur-enriched, hierarchically nanoporous carbonaceous materials (SH-NCMs) were fabricated by an inclusion complex of cellulose hosted by urea hydrate through simple pyrolysis and heating with elemental sulfur. SH-NCMs had unique materials characteristics, such as a large amount of heteroatoms, containing 21.7at.% sulfur, 12.6at.% oxygen and 5.7at.% nitrogen, and a 3D-interconnected mesostructure with a high surface area of 201m2g−1. Interestingly, SH-NCMs showed a high specific capacity of 456mAhg−1 at a current density of 1A g−1, and even after 50 cycles at 10Ag−1, a specific capacity of 170mAhg−1 was achieved. In addition, stability over more than 500 repetitive cycles with nearly 100% Coulombic efficiency was maintained.