Nanofiber-based electrode current collector for high-energy Li-S batteries towards practical application for energy storage

Abstract

The slow sulfur electrochemical reactions are one of the key factors hindering the practical use of lithium-sulfur (Li-S) batteries. However, the polysulfide shuttling and the sluggish redox kinetics, which emerge simultaneously in sulfur cathode, hinder the commercial application of Li-S batteries. Herein, we employ a design to solve the above-mentioned problems via building nitrogen-doping carbon nanofibers with twinborn nickel sulfide nanoparticles (NiS2/Ni3S4@NCNF) as self-supporting current collector for Li-S batteries. Experimental results and theoretical calculations show that the three-dimensional cross-linked carbon structure promotes Li-ion/electron transfer and physically offers wide internal space for sulfur accommodation. Meanwhile, powerful capability of chemical anchoring of the polysulfides endowed by NiS2 mitigates the shuttle effect. Notably, the surface of mixed-valence Ni3S4 has more active sites, which can effectively reduce the energy barrier due to its high catalytic activity and fast sulfur conversion from solid Li2S/Li2S2 to soluble polysulfides. Based on these merits, the Li-S battery with NiS2/Ni3S4@NCNF shows stable sulfur electrochemistry including a highly reversible capacity of 1212.8 mAh g−1 at 0.2C with capacity retention rate of 75.3 % after 100 cycle, and an excellent cycle stability of pouch battery. This work provides a promising strategy to build advanced sulfur current collectors for practical Li-S battery.